Project Dissertation -Standardization of BEV Battery Module for circular economy copy

Standardization of
BEV Battery modules
for circular economy
ES327 Final Report
by Othman Laraqui, ID number 1325995
26 April 2016
Supervised by: Dr Antony Allen

i
1325995 STANDARDISATION OF BEV BATTERY MODULE FOR CIRCULAR ECONOMY
Summary
This study is an attempt of standardizing external features related to a BEV battery module,
based on current literature, in order to increase the feasibility of circular economy regarding
batteries. An overall positive impact is highlighted on downstream stakeholders concerned with
the after first life of BEV batteries, which shows that standardisation enhance this concept of
circular economy even though some negative impact is also noticed on stakeholders concerned
with the top of the battery life chain (before its first life).
Author’s self-assessment
This study is based on the analysis of many sets of secondary data, including papers, patents,
reports, books, design concepts and battery affiliate company’s electronic documents.
Assembling and analysing all of these contributes to an attempt of creating standards on a part
of the EV battery. This has never been attempted in the past, for several reasons, including a
immature market.
As it has never been attempted before, this contribution is relevant to engineering and the
electric car industry. In every domain of engineering, standards are developed for several
reasons. For instance, standard are developed for regulating transport of battery, for safety
reasons. This study attempt to develop standards in order to enhance circular economy for
batteries.
This study can be used for redesigning features that fits the standards. OEMs and battery
manufacturer can apply these standard in a circular economy approach, in order to benefit
circular economy. Also, this project can be used to motivate standardisation of other battery
features such as the BMS. Other students may use this contribution in order to improve it by
using primary data analysis.

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As the standards proposed are impacting positively circular economy, the aim of the study has
been achieved, therefore the study is considered as successful. However, many weaknesses
have been noticed. With regard to quantification of the cost-impacts on stakeholders, this is
hasn’t been done, and it’s the main drawback of this contribution. There is no quantification
for priority of stakeholder’s requirements. This provides a higher reliability on the selected
standards. Quantification is a necessary recommendation for improving this contribution.
Table of Contents
SUMMARY
I

AUTHOR’S
SELF-‐ASSESSMENT
I

LIST
OF
ACRONYMS
IV

GLOSSARY
V

LIST
OF
FIGURES
VII

LIST
OF
TABLES
VIII

1
INTRODUCTION
1

2
AIM
AND
OBJECTIVES
1

3
LITERATURE
REVIEW
2

3.1
HISTORIC
VIEW
OF
THE
EV
MARKET
2

3.2
LITHIUM-‐ION
BATTERIES
3

3.2.1
LI-‐ION
BATTERIES
HISTORIC
DEVELOPMENT
3

3.2.2
LI-‐ION
BATTERIES
PERFORMANCE
3

3.2.3
LI-‐ION
BATTERIES
CELL
5

iii
3.2.4
LI-‐ION
BATTERY
PACK
8

3.2.5
LI-‐ION
BATTERY
MARKET
10

3.3
CIRCULAR
ECONOMY
MODEL
13

3.4
CIRCULAR
ECONOMY
FOR
LI-‐ION
BATTERIES
13

3.4.1
THE
BATTERY
LIFE
CYCLE
AND
STAKEHOLDERS
15

3.4.2
REMANUFACTURING
16

3.4.3
RE-‐USE
FOR
SECOND
APPLICATION
18

3.4.4
RECYCLING
19

3.4.5
CURRENT
PROPOSED
SOLUTIONS
FOR
EASE
OF
CIRCULAR
ECONOMY
21

4
METHODOLOGY
25

4.1
METHODOLOGY
SELECTION
25

4.2
ELECTRIC
CAR
SELECTION
25

5
ELECTRICAL
STANDARDIZATION
OF
THE
MODULE
26

5.1
OBSERVATIONS
AND
RESULTS
27

5.2
DESIGN
RULES
FOR
ELECTRIC
STANDARDIZATION
28

5.3
STANDARDS
PROPOSED
29

5.4
IMPACT
ON
STAKEHOLDERS
30

5.4.1
STANDARDISATION
IMPACT
ON
STAKEHOLDER’S
REQUIREMENT
30

5.4.2
IMPACT
OF
ELECTRICAL
STANDARDIZATION
ON
STAKEHOLDERS
31

6
STANDARDIZATION
OF
THE
COOLING
SYSTEM
32

6.1
THE
COOLING
SYSTEM:
AN
ESSENTIAL
FEATURE
FOR
BATTERY
SAFETY,
RELIABILITY
AND
DURABILITY
32

6.2
AIR
COOLING/LIQUID
COOLING
33

6.3
PASSIVE
OR
ACTIVE
SYSTEMS
35

6.4
INTEGRATED
LIQUID/
LIQUID
COOLING
36

iv
6.5
IMPACT
OF
STANDARDISED
BTMS
ON
STAKEHOLDER
REQUIREMENT
37

7
INTERFACE
AND
PACKAGING
STANDARDIZATION
38

7.1
MODULE
TO
MODULE
INTERFACE
38

7.2
MODULE
TO
BMS
INTERFACE
39

7.3
MODULE
TO
CAR
(OR
PACK)
INTERFACE
41

7.4
PACKAGING
MATERIAL
STANDARD
42

8
COST
ANALYSIS
43

9
RECOMMENDATION
FOR
FUTURE
WORK
44

10
CONCLUSION
45

11
BIBLIOGRAPHY
46

12
APPENDICES
55

12.1
APPENDIX
A:
ACCELERATION
AND
RANGE
THEORY
[66]
55

12.2
APPENDIX
B:
STANDARDIZATION
OF
THE
CELL
FORMAT
56

12.3
APPENDIX
C:
LIST
OF
TABLES
FOR
ELECTRICAL
STANDARDIZATION
[67],
[68]
60

List of acronyms
EV: Electric Vehicle HEV: Hybrid electric Vehicle
BEV: Battery Electric Vehicle or fully electrified vehicle
PHEV: Plug-in Hybrid Electric Vehicle BMS: Battery Management System
BTMS: Battery Thermal Management System E-o-L: End-of-Life

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LFP: Lithium-Iron-Phosphate àLiFePO4 LMO: Lithium-Manganese-Oxideà LiMnO
NMC: Lithium-Nickel-Manganese-Cobalt-Oxideà LiNiMnCoO2
LCO: Lithium-Cobalt-OxideàLiCoO2 LTO: Lithium-Titanate-OxideàLi4Ti5O12
NCA: Lithium-Nickel-Cobalt-Aluminium-OxideàLiNiCoAlO2
Q: Charge in Coulombs (C) t: time in seconds (s) or hours (h)
V: Nominal Voltage in Volts (V) P: Power in Watts (W)
E: Energy transformed in Joules (J)
Glossary
Battery Ampere –hour (Ah) Capacity is the total charge Q that can be discharged from a
fully charged battery under specific conditions:
Q= I.t, therefore Q unit is Ah (Ampere-hour)
Watt-Hour (Wh) Capacity is the capacity of the battery in Wh (Watt-hour)
𝑊ℎ = 𝐴ℎ×𝑉
Specific Energy (gravimetric energy density): rated power capacity/Battery massàWh/kg.
. Determines the battery weight required to achieve a given electric range.
Specific power: Rated peak power/Battery massàW/kg. Determines the battery weight
required to achieve a given performance (acceleration) target.
Volumetric Energy Density: is the nominal battery energy per unit of volumeàWh/l. It
determines along with the nrj consumption), the battery size required to achieve a given electric
range

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Power density: W/l. It determines the battery size required to achieve a given performance
(acceleration) target
Internal resistance R is the overall equivalent resistance within the battery. Different for
charging and discharging and may vary as the operating condition changes. The battery
efficiency decreases and thermal stability is reduced as more of the charging energy is
converted into heat.
State of Charge (SOC): SOC is defined as the remaining capacity and it is affected by its
operating conditions such as load current and temperature.
SOC= Remaining Capacity/ Rated capacity
SOC critical condition parameter for Battery management.
Depth Of Discharge (DOD) = 1-SOC, higher DOD induces lower life cycle of the battery.
Cycle life: number of discharge/charge cycle the battery can handle at a specific DOD
(normally 80%). It’s affected by C-rates DOD and other condition such as temperature and size
of the battery.
Calendar life: life span of battery under storage or periodic cycling conditions. Strongly
affected by SOC and temperature during storage
Battery Management System (BMS): Combination of sensors, controller, communication,
and computation hardware with software algorithms designed to decide the max
charge/discharge current and duration from the estimation of SOC and SOH of the battery pack.
Critical for enabling second life
Thermal Management System (TMS): TMS is designed to protect the battery pack from
overheating and to extend its calendar life. Sophisticated and powerful liquid-cooling is
required by most of the Li-ion batteries in EV applications.

vii
Recommended) Charge Current – The ideal current at which the battery is initially charged
(to roughly 70 percent SOC) under constant charging scheme before transitioning into constant
voltage charging.
State of health (SOH) is the ratio of the maximum charge capacity of an aged battery to the
maximum charge capacity when the battery was new [7]. SOH is an important
parameter for indicating the degree of performance degradation of a battery and for
estimating the battery remaining lifetime.
List of Figures
FIGURE
1:
EV
HISTORY
TIMELINE
[1]
......................................................................................................................
2

FIGURE
3:
GRAVIMETRIC
VS
VOLUMETRIC
ENERGY
DENSITY
FOR
DIFFERENT
TYPES
OF
CHEMISTRIES
................
4

FIGURE
3:
CELL
INTERNAL
COMPONENTS
AND
REACTIONS
[11]
[12]
....................................................................
5

FIGURE
4:
CELL
FORMATS
BREAKDOWN
[12]
[13]
.................................................................................................
6

FIGURE
5:
LI-‐ION
CHEMISTRIES
APPLICATION
DIAGRAM
[14]
...............................................................................
7

FIGURE
6:
BATTERY
COMPONENTS
BREAKDOWN
[17]
..........................................................................................
8

FIGURE
7:
BATTERY
BREAKDOWN
MATERIAL
(BOTTOM
LEFT)
AND
MANUFACTURING
COST(TOP
LEFT)

BREAKDOWN
WITH
OVERHEADS
(BOTTOM
RIGHT)
[18]
.............................................................................
9

FIGURE
8:
EVOLUTION
AND
FORECAST
OF
LITHIUM
DEMAND
PER
USE
[12]
......................................................
11

FIGURE
9:
HISTORICAL
LITHIUM
CARBONATE
PRICES
[12]
[13]
...........................................................................
11

FIGURE
10:
BATTERY
PACK
COST
FORECAST
TOWARD
2030
...............................................................................
12

FIGURE
11:
ELECTRIC
VEHICLE
SALES
(UK)
BY
YEAR
2010-‐2015
[14]
....................................................................
12

FIGURE
12:
CIRCULAR
ECONOMY
MODEL
[21]
....................................................................................................
13

FIGURE
13:
BATTERY
VALUE
CHAIN
MODEL
[25]
.................................................................................................
15

FIGURE
14:
ADAPTED
V-‐MODEL
METHODOLOGY
................................................................................................
25

FIGURE
15:
COMPARISONS
RATIOS
BETWEEN
ORIGINAL
AND
STANDARDIZED
MODULE
CHARACTERISTICS
....
29

FIGURE
16:
COMPARISON
RATIOS
BETWEEN
ORIGINAL
AND
POST
STANDARDIZATION
RANGE
AND

ACCELERATION
...........................................................................................................................................
30

viii
FIGURE
17:
INHOMOGENEITY
AND
AGEING
OF
MODULES
..................................................................................
32

FIGURE
18:
MODULE/MODULE
STANDARDIZED
INTERFACE
[61]
........................................................................
39

FIGURE
19:
CONTROL
MODULE
PROPOSED
STANDARD
[61]
...............................................................................
40

List of Tables
TABLE
1:
ADVANTAGES
AND
DRAWBACKS
OF
DIFFERENT
CELL
FORMATS
[13]
....................................................
6

TABLE
2:
ADVANTAGE
AND
DRAWBACKS
OF
DIFFERENT
LI-‐ION
CHEMISTRIES
[14]
..............................................
7

TABLE
3:
LMO
BATTERY
MATERIAL
WEIGHT
BREAKDOWN
[18]
..........................................................................
10

TABLE
4:
BATTERY
MAIN
COMPONENTS
COST
AND
WEIGHT
[8]
.........................................................................
10

TABLE
5:
BEV
CONSIDERED
FOR
THE
CASE
STUDY
[50]
........................................................................................
26

TABLE
6:
CELL
CHARACTERISTICS
FOR
EACH
CAR
[51]
.........................................................................................
27

TABLE
7:
TABLE
OF
ELECTRICAL
STANDARDS
FOR
THE
BEV
MODULE
..................................................................
29

TABLE
8:
ADVANTAGE
AND
DRAWBACK
OF
LIQUID
AND
AIR
COOLING
[54]
[55]
...............................................
33

TABLE
9:
TYPE
OF
COOLING
SYSTEM
USED
BY
EACH
CAR
MODEL
[55]
................................................................
34

TABLE
9:
COMPARISON
TABLE
OF
DIFFERENT
BMS/MODULE
INTERFACE
CONFIGURATION
[61]
......................
40

1

1 Introduction
The battery is one of the he main components of electric vehicle. It’s the power source that
drives and perform the main function of a vehicle. In the past and today, it’s subject to many
research in order to optimise its performance, viability durability, safety, cost in every level,
cell, module pack. As a complex assembly, the battery is always subject to new improvements.
A single battery pack assembly design regroups all the engineering areas including, energy,
environmental, industrial, mechanical, electrical, electrochemical, system and materials. A
battery pack is an assembly of cell, regroup in sub-parts called modules that are connected
together in series or parallel to achieve a required voltage and capacity. These cells and module
have their physical and electrical characteristics managed by a BMS often included on the
battery. Other features of the battery pack include safety devices, wiring and cooling system.
2 Aim and Objectives
The aim of this study is to standardize all features related to a BEV battery module, and to
show the impact of this standardisation on stakeholders concerned with the battery life cycle.
Objectives are:
• Determine who are the stakeholders and their requirements
• Propose an optimum standard, based on current literature and stakeholder requirements,
for external features related to the module which are characteristics (voltage,
resistance…), cooling system, interfaces and packaging.
• Illustrate the impact of each standard on the stakeholder.

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3 Literature Review
3.1 Historic view of the EV market
FIGURE 1: EV HISTORY TIMELINE [1]
In the 1990’s, Environmental concerns have led the restart of the EV market. More energy
policies like the voting of the 1990 Clean Air Act Amendment and the 1992 Energy Policy
Act helped create a renewed interest in EVs in the U.S. More investments are awarded to the
research and development of EVs technologies, especially in the battery area. This led to the
first commercialization of the Lithium-ion cell in 1991 by Sony, which is today the mostly
used chemistry in nowadays, Laptops, Smartphones and EVs [2].
The Global EV Stock (in the end of 2012) represents 0.02% of total passenger cars which
means more than 180,000. [3] The global EV stock reached more than 665,000 units, which

3
represents 0.02 of total passenger cars. [3] This marks the start of a new era in the automotive
market. The consumers have now more choices than ever when it comes to buy an EV.
Today, the EV market is widely supported by government policies around the world. In 2009,
the Renewables Directive set binding targets for all EU Member States, so that the EV
constitute 10% of the total EU car fleet by 2020 [4]. The US President Barack Obama launched
in 2012, the “EV Everywhere Challenge”, which aims is to make EVs more affordable than
gasoline vehicles by 2022 [2]. The main challenge is the reducing the cost of the battery pack.
In 2011, the Battery pack cost average account between 30 and 50% of the whole EV cost [5].
In January 2016, four UK cities have been awarded £40 million by the ministry of transports,
to promote green vehicles technology [6].
3.2 Lithium-Ion Batteries
3.2.1 Li-Ion Batteries historic development
Lithium-ion cells are the most widely used cells in the electric automotive industry. This is due
to the work of several researchers. Dr John Goodenough and Dr Koichi Mizuchima developed
the first positive electrode usable in a battery using lithium cobalt oxide 𝐿𝑖𝐶𝑜𝑂,. Dr Rachid
Yazami demonstrated the usability of graphite as an anode in 1984. Finally, Dr Akira Yoshino
developed the first prototype of Li-ion battery, by combining carboneous materials as an anode
and 𝐿𝑖𝐶𝑜𝑂, as a cathode. [7] This has increased the safety of the Li-ion, by using materials
without metallic lithium, and thus allow it’s first commercialisation in 1991 by Sony. [2]
3.2.2 Li-ion Batteries performance
Lithium-ion success is due to it’s high performance versus cost, compared to other type of
batteries. The Ragone chart below illustrate this. Li-ion has the best balance between specific
energy density and specific power density. These parameters are really important as they
directly affect the range, the acceleration and the weight of the car.

4
FIGURE 2: RAGONE CHART [8]
FIGURE 3: GRAVIMETRIC VS VOLUMETRIC ENERGY DENSITY FOR DIFFERENT
TYPES OF CHEMISTRIES [9]
The same applies for the volume of the cells required to deliver the same performance. Li-ion
requires less volume than other types of batteries as they have higher volumetric densities
shown in the table above.
Other advantages of Lithium ion cells are:

5
• High life cycle: Between 1000 and 2000 cycles to reach 80% discharge.
• Low toxicity compared to Ni-Cd and Lead Acid cells
• Li-ion is the only type of cells with no maintenance required.
• It’s relatively cheap compared to Nickel and Cobalt, which prices are volatile.
• Low self discharge (less than 10%/month versus 30% for Nickel based cells) [10] [8].
However, Li-ions batteries are thermally unstable. Hence a thermal management system
(cooling/heating system) and a Battery Management System (BMS) are required, which
significantly rise the cost of the battery pack. A cost average of a BMS is about $1500. [8]
3.2.3 Li-ion Batteries cell
Li-ion cells are combination of 2 electrodes (cathode and anode) and one electrolyte. The
electrolyte is the chemical energy stored. Using Red-Ox reactions, there is a transfer of
electrons which provides energy to the motor, as shown below:
FIGURE 3: CELL INTERNAL COMPONENTS AND REACTIONS [11] [12]
Lithium-ion cells exist within different formats. The 3 formats that exist in the automotive
industry are: Cylindrical, Pouch, and Prismatic.

6
FIGURE 4: CELL FORMATS BREAKDOWN [13] [12]
The advantages and drawbacks of each type of cells is summarized in the table below:
TABLE 1: ADVANTAGES AND DRAWBACKS OF DIFFERENT CELL FORMATS [13]

7
Li-ion cells exist also under different combination of chemistries: LFP, LMO, NMC, LCO,
NCA, LTO. Their main areas of application and advantage and drawbacks are summarised in
the figures below:
FIGURE 5: LI-ION CHEMISTRIES APPLICATION DIAGRAM [14]
TABLE 2: ADVANTAGE AND DRAWBACKS OF DIFFERENT LI-ION CHEMISTRIES [14]
According the the figures above, the Li-ion chemistries used for automotive industry and
stationary storage are NCAs and NMCs cells. However, others type of chemistries are also
used in the automotive industry such as LMO LFP, used by Chinese automotive manufacturer

8
[15] and LTO’s, used in the new I-Miev [16] for other reasons such as safety, reliability and
cost.
3.2.4 Li-ion Battery pack
A Battery pack is a complex assembly of many components. Each component has a specific
function: charging, connecting, packaging, cooling, fitting, managing, safety. The main
components of the battery pack are highlighted in the figure below:
FIGURE 6: BATTERY COMPONENTS BREAKDOWN [17]
Battery packs features also many type of materials that embed polymers, metals, electronic
components and graphite. Breakdown of their costs are highlighted in the figures below:

9
FIGURE 7: BATTERY BREAKDOWN MATERIAL (BOTTOM LEFT) AND
MANUFACTURING COST(TOP LEFT) BREAKDOWN WITH OVERHEADS (BOTTOM
RIGHT) [18]
Most of the material costs are related directly to the cell, there is only a little percentage that is
directly related to the module and pack level. In BEVs, 61% (these value varies with the
chemistry used), of the weight of the battery accounts for cells materials.
With regards to manufacturing costs, More, than 91% of manufacturing costs are related to the
cells assembly. Therefore, the main costs are directly related to the battery cell.

10
TABLE 3: LMO BATTERY MATERIAL WEIGHT BREAKDOWN [19]
In BEVs, 48% of the battery weight is related to the two electrodes (excluding the BMS and
its interface). Hence, improvement for reducing weight needs to be focused on reducing the
weight of electrodes.
The breakdowns above don’t take into account the BMS, which is the most expensive part of
the battery.
TABLE 4: BATTERY MAIN COMPONENTS COST AND WEIGHT [8]
3.2.5 Li-ion Battery Market
The success of Lithium-ion batteries is illustrated in the graph below, designed by Fox Davis.
It highlights the evolution and forecast demand of lithium until 2017 per use. The increase in
lithium demand is mainly due to the increase in demand of rechargeable batteries.

11
FIGURE 8: EVOLUTION AND FORECAST OF LITHIUM DEMAND PER USE [20]
In 2011, 5% of the lithium demand for rechargeable batteries comes from the automotive
industry. It’s forecasted that this percentage will increase to 41% in 2025, making the
automotive industry the largest consumers of rechargeable batteries [21].
Lithium is the main active material of current cells used in nowadays automotive traction
batteries.
The weight of lithium material inside a battery pack range from 8kg to 40kg [8].
The graph below shows the evolution of lithium price per ton since 2000 to 2012. It’s clear that
lithium price is increasing. This is mainly due to the increasing demand in rechargeable
batteries as stated above.
FIGURE 9: HISTORICAL LITHIUM CARBONATE PRICES [20] [21]

12
However, it’s forecasted that the overall battery pack cost will decrease with time, thanks to
R&D improvements toward weight and cost reduction as shown in figure below:
FIGURE 10: BATTERY PACK COST FORECAST TOWARD 2030
The histogram below shows that there was about 100 EVs sold in 2010. In 2015, 30000 EVs
were sold. This represents a significant increase in the number of EVs in the UK roads.
FIGURE 11: ELECTRIC VEHICLE SALES (UK) BY YEAR 2010-2015 [22]
It’s also forecasted that 100000 EV’s (cars and vans) will be sold in the only year 2022 [23].
As the number of EVs increases year after year in the UK as long as the price of lithium, it’s
important to consider an End-Of-Life (EOL) strategy for the batteries, hence the importance of
circular economy [24].

13
3.3 Circular economy model
Circular economy has many definitions. McKinsey refers it as “the removal of wastes during
the life-cycle of a product” [25]. A better definition from the WRAP is valuing a product
differently and creating a more robust economy in the process [26].
The process can be really valuable as it benefits to the overall economy. Between 2008 and
2011, WRAP has generated £2.2billion of benefit to the UK economy, by implementing
circular economy in different sectors [27]. Defra calculates that UK businesses could benefit
by up to £23 billion per year through circular economy [28], whilst McKinsey estimates that
the global value of resource efficiency could eventually reach $3.7 trillion per year [27]. This
shows that there is a high opportunity in creating businesses in the circular economy domain.
FIGURE 12: CIRCULAR ECONOMY MODEL [29]
However, all these forecasts don’t take in account challenges to implement circular economy,
especially for long-term consumer goods such as Li-ions Batteries for electric cars.
3.4 Circular economy for Li-ion batteries
Based on the previous section, there is a:

14
• Significant increase in the lithium ore price.
• Significant number of lithium-ion batteries will be introduced in the market.
Following a linear life-cycle for the product, a considerable amount of money is wasted:
• It requires more space to store the increasing number of used batteries (Landfills).
The occupied space will provide no value to the overall economy. This also can be
noxious to the environment when they are stored in large numbers, even though their
low toxicity.
• There is about 80% of remaining capacity inside the battery after first use [30], [31].
Throwing the battery after first use will mean that inherent capacity is wasted.
Moreover, the materials inside the batteries are valuable, as lithium and they can be
extracted through recycling and then re-used (as highlighted in figure 6 above).
Therefore, importing lithium from other countries instead of re-using the available on
inside old batteries is considered as a waste.
Many scientific research papers discuss this issues and addresses solutions in order to integrate
batteries in the circular economy. NREL addresses stated that profitable businesses are possible
in two areas of circular economy: Remanufacturing for same use; and Re-use for another
application [32].

15
3.4.1 The battery life cycle and stakeholders
FIGURE 13: BATTERY VALUE CHAIN MODEL [33]
From the value chain above, stakeholders are identified. Each stakeholder’s values common
and different parameters that are related to the battery pack, which are highlighted next to each,
below.
The 7 start steps are related to:
Ø Battery manufacturer (mining supplier are not taken into account) values the
manufacturing process efficiency and customer satisfaction.
Ø OEM values the same as the battery manufacturer.
The 3 last and longest steps are respectively related to:
Ø Car user values the performance, durability, cost and safety of the battery.
Ø Second life user values the same as the first user plus the ease of assembling the
modules in their second life application.
Ø Recycler values are in the cost of recycling. This is related to the ease of disassembling
the modules, and the number of various materials present inside it.
Other stakeholders concerned with the Battery regulation are:

16
Ø Governments are concerned with the environmental impact and safety issues.
Ø Standardisation organisms assesses all the standard regarding some part of the battery
such as the charging system [34].
This study aims to standardize all the features above by taking in account parameters that are
valued by the different stakeholders.
3.4.2 Remanufacturing
A general definition of Remanufacturing would be “the process of returning a used product to
like-new condition with a warranty to match.” [35] This process is commonly used in the
automotive industry. It’s estimated that there are 22 million units’ vehicles (Cars and light
vans) remanufactured/ rebuild each year across the E-U [36].
A complete definition would be “transforming a post-vehicle-application battery to once again
meet the standards for use in a moving vehicle.” It involves partial disassembly of the battery
pack, removal of damaged cells, replacement of these cells by new ones, and reassembly of the
battery.
A cost benefit analysis has been made by researcher from Grand Valley State University in the
USA. This analysis is based on reasonable assumptions on overhead, labour, material cost, and
reasonable forecasts on availability of EOL batteries and the demand. These forecasts comprise
optimist, pessimist and middle view [36].
The conclusion that has been drawn is that remanufacturing batteries cost 60% less than brand
new batteries [36].
This shows a real potential for OEM’s, and car users as saving estimation per battery is £7500
[36]. This may be a solution to the key barrier of EV market growth, which is cost related to
the battery. A drop in battery cost will boost EV sales, which bring more batteries in the

17
market. Thus, more batteries will be remanufactured, and so on. Therefore, there is a potential
in creating a virtuous cycle, thanks to remanufacturing batteries.
A business model has been created, based on a parallel with a new LG Chem battery
manufacturing plant, as there is no current remanufacturing plant. This model illustrates in
depth the potential of remanufacturing as a business [36].
However, this analysis doesn’t show the negative challenges in remanufacturing,
For a better alternative, a set of questions is raised:
• How many cells need to be replaced until remanufacturing starts to be cost-inefficient?
• What is the maximum difference between the cells SOH allowed, so remanufacturing
can be considered as cost-effective solution?
• How long remanufactured battery will last compared to new batteries, and what is the
difference between their performances?
• What is the range of customer allowance in regard to limited battery performance?
• How the cell inhomogeneity affects the remanufacturing area?
Advantages and disadvantages of remanufacturing are hence listed below:
+ Cost per new battery manufactured is $1515, versus $833 for remanufactured battery
(business model scenario).
+ Remanufacturing plant are easier to manage, as there is less operation required than
a manufacturing new plan
+ Environmental issues reduced, as less space is required. A greener solution as it avoid
storage of Lithium, which rises concerns regarding the environment.
+ Part of the circular economy

18
-‐ 30 years’ payback (with the actual forecast, based on the business model scenario).
Most of the investors would never accept a payback over 5 years.
-‐ Cell inhomogeneity issues
A better solution would be a broader business model, which will consider, three solutions of
circular economy.
3.4.3 Re-use for second application
Re-use for another application is the last stream of circular economy considered in this review.
Re-use for another application would be re-using batteries for application other than
automotive.
Re-using batteries allows an extended use of capacity, which increases the inherent value of
the battery.
Andrew Burke and Marshall Millers stated that used batteries are suitable for low power
application and high energy application [37]. Therefore, their main applications of re-use are
stationary application, as grid systems, micro-grids, renewable grids [32] [38].
Sharma and Keeli discuss the uses of second life battery in order to achieve peak load reduction
in commercial buildings [39]. It shows significant benefits in the uses of second life batteries.
For a 30% peak load reduction, which saves about $7812 per year, 51 second life batteries are
used with an 80% SOC. This equivalent a 545 kWh storage of second use batteries. However,
this paper doesn’t include repurposing and maintenance cost, depreciation and recycling costs
or End-Of-Second-Life Costs. This project is already carried out by Nissan, using old Leaf
batteries in order to supply power during mid-day peak energy demand, where electricity is the
most expensive.
A similar project is carried by Nissan Europe, in order to store old Nissan-Leaf batteries to
deliver power for Vehicle-to-grid storage.

19
Other applications are residential service. Benefits shows a cost reduction for the overall
community plus a power back up, in case of a blackout [40].
3.4.4 Recycling
Recycling Li-ion cells is a complicated process at every scale. At the cell level, there is a wide
variety of chemistries present in each cells. Active material is under the form of powder, which
makes the process complicated. Foil recovering the cathodes, the outside envelope itself have
different materials. These chemistries need to be separated for recycling. [41]
According to Mr Tatsuo Horiba [42] and section 3.2.3, a single Li-ion cells uses a variety of
different chemistries. Moreover, Li-ion cells are packaged in different format, such as the
Cylindrical Panasonic NCR18650 used by Tesla, and Pouch cells used by the Nissan Leaf.
This might increase the complexity of recycling EVs as more equipment is required, which
increases the cost. [43]
At the battery pack level, the arrangement of the cells into modules makes recycling even more
complexes as the modules have they one circuitry (CLC1
chip). The modules can sometimes
include an integrated cooling system. If not there is a Battery thermal management system that
regulate temperature across all the battery. In both case, disassembly is quite complicated and
requires high and costly equipment. [41]
All of these shows the variety of valuable material that is present inside a Li-ion battery pack.
However, the complexity of separating these materials and the processes to recycle each type
of material makes the whole process expensive. [44]
1
CLC : Configurable Logic Cell : A small circuitry installed on the module, that record temperature and voltage
of each cell in the module, and sen dit via busbars to the BMS.

20
Recycling Li-Ion batteries is an unprofitable business for the moment. This is due to the
complexity of its layout and variety of its materials. [36] However, it’s a compulsory duty to
recycle them as the OEMs are responsible of their E-o-L.
There are potential solutions, in order to make recycling easier and possible for Li-ion batteries
would be:
• Standardization of packaging: Uses bolts and nuts instead of welding, in order to ease
assembly and disassembly.
• Standardization of the cooling systems: Uses separate cooling system instead of
integrated cooling system in modules, (trade off with performance).
• Labelling the batteries chemistries in order to help identification (avoid cross-
contamination2
) [44]
• Standardization of format and materials
• Reduce the number of materials
• Regulations would assure safe transport and handling, and discourage any sort of
cross-contamination. [44]
However, these requirements that are part of the design for recycling requirement shouldn’t
affects battery performance and safety.
Therefore, recycling must come as the final step of circular economy. In other terms, when the
battery capacity is no more useable for any other applications and have no more inherent value.
2
Cross-contamination : Battery cell contamination by external features such as dust.

21
3.4.5 Current Proposed solutions for ease of circular economy
Dr Ahmed Pesaran assesses a methodology in order to asses the feasibility of second life
project. [32] This is achieved by dividing the processes into 3 phases, first is to assess the merit
of second uses applications and strategies, second verify performance (testing) and finally
facilitate implementation of second use programs. In every phase, assets of useful
requirements are derived. These Pesaran requirements address a wide range of potential
issues regarding regulation, safety, durability, technical (testing) and profitability. This
feasibility methodology can be extended to the whole value chain. For the final phase, the
requirements are [32]:
-‐ Disseminate study findings to inform the market of the potential profitability of the
second use of traction batteries
-‐ Provide validated tools and data to industry
-‐ Develop design and manufacture standards for PHEV/EV batteries that
facilitate their reuse
-‐ Propose regulatory changes to encourage the reuse of retired traction batteries in other
applications
A lot of current research tries to address the second requirement, as they provide many
validated tool and data regarding testing of the batteries at their E-o-L.
Ciccone [30] demonstrates the feasibility of second life of Li-Ions cells using ageing test. Then
a technical analysis shows for how long they can be re-use. Finally, a Life Cycle Analysis
shows the environmental gain of it. This approach contains many issues:
• No information is provided on the time and manner of testing. If the cells are tested
one by one, the methodology will be time constraining regarding disassembly and
time for testing. No information is provided on the time of testing.

22
• This approach only considers the technical and environmental aspect, whereas the
economical and safety aspects are neglected, and strongly related to the point above.
• It doesn’t consider the entire SOH of the battery.
Andrew Burkes and Marshall Millans [37] proposes a similar methodology but applied to
modules, which significantly reduces the time constraints.
An NREL study [45] proposes a set of tools and testing in order to identify the State Of Health
of the battery. Another NREL study [46] shows how calendar effects, driving behavior can
affect the SOH of a battery. These are the reasons of the variability of the SOH of battery packs,
and hence why these parameters are important to consider in testing the batteries. This same
study considers also a techno-economical feasibility analysis of a second life application,
highlighting all the steps, from battery collection to storage of the modules inside a grid system.
They highlight all the testing requirement and the cost incurred with it, based on reasonable
assumptions.
Gladwin and Stone established a broad sets of conditions metrics that should be tested in order
to enable second life, which concerns physical conditions of the battery, pack terminal voltage,
pack impedance, pack capacity, and BMS recorder data [47].
Fangdan, Jiushun and others [48] proposes a way to establish capacity estimation of large scale
Li-ion for Second Use based on Support Vector Machine.
Other methodologies are also proposed, in order to optimize the implementation of second life
application:
Stanciu [40] sets that a challenge for second life implementation is minimizing the size of
storage systems considering an economic profit and limiting the ageing of the batteries
(inhomogeneity of cells).

23
Keeli and Ratnesh [39] focus on maximizing the second life time by setting an ideal
charge/discharge pattern.
Other methodologies are used in order to assess the feasibility and the techno-economic
feasibility of second use.
Cready and Lippert [49] shows a technical-feasibility analysis for Ni-MH batteries, which
proves that re-use for second life seems to be a viable concept. This study, doesn’t take into
consideration the Li-ion batteries. This factor challenges the whole paper as it doesn’t show a
long term viability. In facts chemistries are in continuous evolution.
Many of the literature above tries to address the two first Pesaran requirements. However, this
is not the case for the third requirement.
This is the potential gap has been identified in order to ease not only the re-use but the whole
circular economy model. This gap is design for second life and recycling, and this can be made
in first step toward standardization of the EV Battery module. Design for circular economy,
would be designing the product at an early stage in order to meet requirement for first use, but
also second use, and recycling. In fact, standardizing the module has the potential to reduce
costs for businesses in circular economy.
In his book, [31] John Warner assess that standardization of the module wouldn’t occur in the
near future for two reasons. The first one is that each vehicle manufacturer and Energy Storage
Systems (ESS) has their own way to design the battery pack that can fit one or two car models
or stationary grids, which is actually true for the moment. The second reason is that there is
wide variety of Hybrid-Electrified Vehicles (HEV), and therefore the battery packs are
designed to fit between the combustion engines, and therefore have different designs.
Indirectly, he defines standards as a precise value of each characteristic of the module or battery
pack (size, voltage, weight, internal resistance, location), but this is only a small type of

24
standard rules. Standards could be defined as a limit, a range, a manufacturing process, rules
of transports, recommendations… An international standards of electrical connectors and
charging mods of all EV settle is by the IEC62196, that settled 4 modes of charging and three
type of plugs (SAE J1772, or Yazaki connector for North America; Mannekes Connector for
Europe, and CHAdeMO for Japan) [34].
In this paper, standardization of the BEV module is considered. HEV battery packs are smaller
and have lower requirement regarding performance of their batteries, and have higher
constrains regarding weight and volume of their batteries. This includes electrical
characteristics, cooling systems, external mechanical fittings, external packaging and
Module/BMS interface. A possible attempt inner standardization is then carried out. Finally, a
set of recommendations for different stakeholders is made, and benefits for them will be
highlighted.
Standardizing other parts of the battery pack is complicated, but can be considered in future
work. This includes standardization of:
• The chemistry of the cells used in the battery pack.
• Material used for packaging the battery pack.
• Electrical features of the battery pack (Contactors, battery back fuses, HVIL3
).
• Standardizing the BMS circuit, and software for first and second uses.
• Standardize the electrical parameters of the battery pack, weight and size for each
vehicle category (Motor bikes, small, medium, large, luxury cars, small and large
vans, trucks…)
• Standardize the location of the pack.
3
High Voltage Interlock Loop : A safety device tha consist in series of switch that close the circuit when measured
voltage by the BMS are high.

25
4 Methodology
4.1 Methodology Selection
The V-model methodology used in system Engineering is chosen to carry out the study. A V-
model different from the original is adapted to this study as shown below:
FIGURE 14: ADAPTED V-MODEL METHODOLOGY
Standard rule is settled to match a maximum of stakeholder’s requirements referred in section
3.4.1.
4.2 Electric Car Selection
Six models of different EVs car are considered. Their choice is based on the UK, as the study
considers than the six most presents BEVs in the UK’s road. The six models are ranked below:

26
TABLE 5: BEV CONSIDERED FOR THE CASE STUDY [50]
5 Electrical Standardization of the module
Referring to section 3.4.1, stakeholders values a number of features in the module, including
performance and safety. Therefore, the aim of this section is to set a number of rules regarding
five parameters: Voltage, current capacity Ah, maximum current capability, weight and size of
the module.
Voltage and current are factors that affects respectively Wh capacity of the battery and power
delivered to the motor of the car, which are respectively key factors for driving range and
acceleration (see appendix A section 12.1). These two feature are valued by customers (first
and second users).
4
Based on the European Car Segmentation
5
C: Medium Car
6
B: Supermini Car
7
F: Luxury car
8
M: Minivan
9
A: Mini Car
Nissan
Leaf
Renault Zoe Tesla Model S
Nissan e-
NV200
Renault
Kangoo Z.E
Peugeot iOn
Type of car
Small size
car
Small size car
Large size
luxury car
Van Van Small size car
Number in
the UK
(end 2015)
10441 2401 1346 896 731 250
Segment4
C5
B6
F7
M8
M A9

27
5.1 Observations and Results
Data has been gathered on 6 cars regarding the type of cell used, shown in the table below:
Cell Maker AESC Panasonic Li-Energy
Japan
Toshiba LG Chem
Chemistry G/LMO-
NCA
G/NCA G/LMO-NMC LTO/NMC G/LMO-
NMC
Format Pouch Cylindrical Prismatic Prismatic Pouch
Capacity Ah 33 3.1 50 20 36
Voltage (V) 3.75 3.6 3.7 2.3 3.75
Weight (kg) 0.8 0.045 1.7 0.52 0.86
Volume (L) 0.4 0.018 0.85 0.23 0.49
Volumetric Energy Density (Wh/L) 309 630 218 200 275
Gravimetric Energy Density
(Wh/kg)
155 248 109 89 157
Car used Nissan
Leaf/e-NV
200
Tesla S Peugeot Ion Peugeot Ion Renault
Zoe/
Kangoo Z.E
TABLE 6: CELL CHARACTERISTICS FOR EACH CAR [51]
Tables embedding the characteristics of the car are in Appendix C (see section 12.3). Some
observations while carrying the research on those characteristics are made:
• The nominal voltage is settled according to the car manufacturer, this voltage can be
chosen at different State-of-Charge of the battery (mainly between 60 and 85% SOC).

28
• Most of the cars model, have differences between the battery voltages calculated
using the cell nominal voltage and the nominal battery voltages given by the OEM.
The same applies for all cars, with regards to both Ah and Wh capacities.
5.2 Design rules for Electric standardization
From the previous observations, a set of design rules is derived:
• The nominal values, given by the OEM for each car characteristics, are used as targets
for standardization. Therefore, the standards design is based on these nominal values.
• The Battery characteristics calculated using the cell characteristics are used as
comparison tools. These are compared to the new battery characteristics calculated
similarly using a cell-basis. This method gives a realistic view on the differences
between the characteristics.
• Module volume of the Tesla is calculated by using a rectangular conversion of the
cylindrical cells, in order to match better the real module size.
• Standardized Modules are assumed to be in a rectangular box format.
• The New standardized Battery Weight of each car is calculated using the value of
cell-to-battery weight ratio (CBW).
𝐶𝐵𝑊 =
𝑇𝑜𝑡𝑎𝑙
𝑤 𝑒𝑖𝑔ℎ𝑡
𝑜 𝑓
𝑡ℎ𝑒
𝑐 𝑒𝑙𝑙𝑠
𝑇𝑜𝑡𝑎𝑙
𝑊 𝑒𝑖𝑔ℎ𝑡
𝑜 𝑓
𝑏 𝑎𝑡𝑡𝑒𝑟𝑦
𝑁𝑒𝑤
𝐵 𝑎𝑡𝑡𝑒𝑟𝑦
𝑊 𝑒𝑖𝑔ℎ𝑡
𝑓 𝑜𝑟
𝑐 𝑎𝑟
𝑥 =

>?@
ABCDE

F?GHIC
BJ
K?EEL

MNF

.
• The impacts of post-standardize modifications are presented under the form of positive
and negative ratios.
• Customer satisfaction is assumed to be affected under 5%, under current performance of
the car.
These rules are applied in the tables available in appendix C (see section12.3).

29
5.3 Standards proposed
Standardized
Characteristics
Standardized
Value
Comments
Voltage (V) 15 ± 0.75 As pretty all the voltage modules are over 300V, taking 5% of this value will
ensure a matching percentage lower than 5%.
Max Current
Capability (A)
510 Based on the highest motor power which is Tesla’s
Max charging rate 1C Charging above 1C=Ah Capacity, causes faster degradation of the modules,
hence reducing its life cycle. If not appropriately supervised, an overcharge of
the circuit can be caused. Avoid Ultra-fast charging. Allows a controlled
degradation of batteries.
Max Weight (kg) 7 Based on the heaviest module of the set of cars (I-Miev), using the less
performant cells (Li-Japan). No specific limit for height, width and length of the
modules.
Format/Volume (L) Rectangular /4
TABLE 7: TABLE OF ELECTRICAL STANDARDS FOR THE BEV MODULE
Applying the standards above on the cars (see appendix C, see section 12.3). Percentage of
fitting for each characteristic derived from the table is presented in the chart below:
FIGURE 15: COMPARISONS RATIOS BETWEEN ORIGINAL AND STANDARDIZED
MODULE CHARACTERISTICS
-‐10.00
-‐5.00
0.00
5.00
10.00
15.00
20.00
Percentage

Fitting

Car
models
Ratio
Voltage
(%)
Ratio
Ah
Capacity
(%)
Ratio
Wh
Capacity
(%)
Ratio
Weight
(%)
Ratio
Volume
(%)
Ratio
Power
(%)

30
The main positive impacts on the Tesla S is a higher Wh capacity. The standardized capacity
has a closer value to the nominal capacity of 85 kWh, as the non-standardized pack have 79
kWh to 80 kWh. In counterpart, there is a negative impact, as there is a 1% increase in weight
and size. In counterpart there is a 4% power losses for the same car. Regarding the Kangoo,
there is a 16% increase in power, whereas a 1% decrease in power for the Ion is noticed.
The range and acceleration affection is calculated based on theory available in appendix C, see
section 12.3.
FIGURE 16: COMPARISON RATIOS BETWEEN ORIGINAL AND POST
STANDARDIZATION RANGE AND ACCELERATION
There is no negative affection on range and acceleration of each car selected, as the highest
negative impact is 4% drop of initial acceleration for the Model S. The Standardization rules
are then acceptable for stakeholders with regard to performance of the car.
5.4 Impact on stakeholders
5.4.1 Standardisation impact on stakeholder’s requirement
Common Impact of standardization on stakeholder’s requirements are:
o Manufacturers and recyclers:
-‐10.00
-‐5.00
0.00
5.00
10.00
15.00
20.00
Percentage
ratio
Car
models
Ratio

Range
(%)
Ratio
Acceleration
(%)

31
Ø Reduction of the cost of equipment and testing facilities for manufacturers
and recyclers due to standardization. In this case, settling standard rule means
reducing the characteristics range of modules. Therefore, it’s a first step toward
multi-testing facilities, as one facility is required to test battery of each type of
car model.
o Second life users:
Ø Standardisation of features increases the availability of second use features,
which reduces costs for all second life application.
o All stakeholders (except government):
Ø Cost reduction at the top of the battery life cycle positively impacts
stakeholders concerned with the bottom life cycle of the battery. (see section
3.4.1).
o All stakeholders:
Ø First step toward BMS and battery standardization, as reducing the range of
characteristics, reduces the variety of safety and thermal issues. Then the variety
of BMS software’s is needed, and reduce the threat of warranty (risk costs).
These four points are positive impacts related to standardization in each section
5.4.2 Impact of electrical standardization on stakeholders
Impact of electrical standardization on stakeholder’s requirements are:
o OEM:
Ø Reduce costs due to transportation. Limited Ah Capacity allows OEMs to
reduce their transportation costs as it’s proportional to the ELC, which is the Ah
capacity module times 0.3.

32
6 Standardization of the cooling System
6.1 The cooling system: an essential feature for battery safety, reliability
and durability
Temperature is an important factor to consider for first and second use of the battery.
It affects battery performance, safety and durability.
Heat generation increases with higher rates of SOC and lower temperature, which will cause
faster degradation of the battery. Li-Ion cells generates heat in a smaller volume and are
sensitive to extreme cold and hot, so a complete thermal battery management system is required
[52].
Uneven temperature distribution causes inhomogeneity in the modules. Modules under high
temperature area age faster than others in low temperature area as shown below:
FIGURE 17: INHOMOGENEITY AND AGEING OF MODULES
Even distribution of temperature within the battery pack optimizes the power and energy
density, efficiency and the life of the pack.
Many failures are related to high and low temperature operating condition, for instance thermal
runaways, where heat generation is higher than the heat dissipated, or power decrease due to
decreasing temperature condition (as chemical reaction decrease with temperature). An
optimum balance of operating temperature would be between 20°C and 40°C [53].

33
Therefore, cooling systems (or battery thermal management systems) are critical for optimizing
battery life. According to the NREL: a battery thermal management system is used for reducing
variation of temperature within the modules and the pack [54].
Ideally, standardized cooling system need to be:
Ø Compact, lightweight.
Ø Reliable and serviceable.
Ø Low-cost.
Ø Easily packaged (For second life). [54]
6.2 Air cooling/Liquid Cooling
There are two types of cooling systems that are used in nowadays packs: Liquid and Air
cooling. Their advantages and drawbacks are summarized in the table below:
Air cooling Liquid cooling
+ Low cost - High Cost
+ Easier maintenance - High cost and complicated maintenance
+ Simple design - Complex design
- Less effective heat transferàLarge pressure drops + Higher heat transfer rate
- Low volume efficiencyà runs on the battery + Compact design
- Location sensitive10
+ Location insensitive
+ Handle a large pulse of power
- Potential of leakage
TABLE 8: ADVANTAGE AND DRAWBACK OF LIQUID AND AIR COOLING [54] [55]
10
If the location present lot of variation of temperature

34
EV
model
Cell
shape
Cooling
Method

Nissan
Leaf
Laminated
Prismatic

Passive
air

Renault
Zoe
Pouch

Active
air

Tesla
Model
S
Cylindrical
Active-‐liquid

Nissan
N-‐EV200
Laminated
prismatic

Passive
air

Renault
Kangoo
Z.E
Pouch

Active
air

Peugeot
Ion
Prismatic
Active
air

TABLE 9: TYPE OF COOLING SYSTEM USED BY EACH CAR MODEL [56]
Many of this characteristics should be taken in account while designing the standardized
module. “Good pack thermal design starts with good module thermal design”. A local analysis
is made in order to determine whether a liquid or an air cooling system is more suitable for EV
batteries in the UK:
• American manufacturers such as Tesla uses liquid cooling for their batteries as they
are mainly implemented in the US, which has high variation of temperature inside its
territory (minimum average is -18°C whereas maximum average is 30°C within a
year, for the state of North Dakota) [57].
• However, the UK has low variability of temperature inside its territory (minimum
average is 0°C and maximum average is 22°C [58]), hence liquid cooling can be seen
as a useless additional cost.
• Volume and power: Liquid system takes less space than air system, therefore the
volumetric energy and power density are affected. Less volume will provide a better
range and acceleration of the car.

35
• NREL recommend the use of liquid cooling for pure EV batteries and series HEV as
it will reach the optimal thermal performance. This shown in the table above, as the
only pure EV car that uses air-cooling, this for low cost purpose. [54]
Liquid cooling are recommended to be used as a standard purpose. The channels within the
battery needs to be layout in a parallel flow line, so the temperature is evenly distributed.
Parallel flow means that the coolant have many entries. [54]
6.3 Passive or active systems
Passive systems are used for ambient temperature, whereas active system are used for extreme
temperatures.
From this table, it’s shown that all American EV models uses active cooling. This is mainly
due to their market location where extreme variation of temperature exists. BMW and Nissan
have mainly their market in Europe. There is low-variation of temperature in central and
southern Europe, and passive cooling system are less complicated, have lower cost and lower
number of components and they consume less energy.
Therefore, standardizing the system must depend on the location. For the moment, different
European Governments such as the UK must set standards regarding the systems, by testing
their batteries under average maximal and minimal conditions. This will decide on which
system to use. For other countries where extreme temperatures are obvious, such as the US,
will set the standard to active systems.
However, having different standards in each country is an issue for OEMs. They will need to
assemble both, passive and active systems for a same model, regarding on where the model
will be used. This will increase costs on the manufacturing process, if the EVs are assembled
outside the country of use. Also, there is issue with second life application for two main reason:

36
• Disassembling: Active and passive system have different layout. Therefore, it requires
more equipment, and a trained workforce. It may require a second work chain, one for
passive, and another for active. All theses parameters will increase the total cost of
repurposing.
• Second life application: Modules under active system must be repurposed in a
different application than those under passive system, in order to avoid
inhomogeneity of the modules in second life. This is die to the difference in efficiency
between the two systems.
Moreover, research is carried out in order to decrease the cost of active system, in order to have
a less complicated layout with an increase in efficiency.
Therefore, a global standard should be set to active systems. Ducts must be implemented
between each module.
6.4 Integrated Liquid/ Liquid Cooling
• According to the NREL: Integrated liquid cooling in a module reduces temperature
distribution in addition to lowering the overall temperature for large modules, which
is good for electrical balancing. Also it provides a better control of temperature
variation as it’s located at a module scale [59].
• However, integrated liquid cooling systems in the modules are expensive and makes
assembly and disassembly of the pack more difficult, hence increases the number of
equipment. Moreover, it adds costs in recycling the modules, as the number of
channels has increased, and are more expensive to manufacture.
Therefore, it’s recommended to set the standard to liquid only-system.

37
6.5 Impact of standardised BTMS on stakeholder requirement
From the previous points, the issue of cooling systems is addressed by using active liquid
cooling system using parallel flow standard for BEVs. The main drawbacks are initial costs of
manufacture and purchase and complexity. However, theses drawbacks are overcome as most
of the requirement for stakeholders are met:
o Common Impact: (see section 5.4.1)
o Manufacturers:
Ø Economy of scale: Ordering higher quantity of different components
composing the BTMS decrease its manufacturing cost per unit produced. à
this feature in the 5th
point of the common advantages of standardization
and added to section 5.4.1).
o First users:
Ø Increasing performance, due to less volume and weight occupied by the
BTMS, more module can be added.
Ø Increase Reliability and Efficiency due to higher heat transfer., which increase
durability of the car
o Second users:
Ø Same advantage as first users
Ø Ease of testing and fitting of the battery thanks to standardisation: A standard
type of cooling system is used, hence any battery using this standard fits to the
ESS.
o New Businesses:
Ø First step toward the creation of a new type of business: Cooling system
manufacturer for EVs. Due to the increasing demand of EVs (see section
3.2.5) and standardisation of cooling system, there is high demand of a same

38
cooling system, it can be manufactured in high batches with a fully automated
system, an opportunity for new business.
7 Interface and packaging standardization
The module interface is a set of electrical components that allows communication between
modules and the Battery Management System.
7.1 Module to Module Interface
Inter-module connections are subject to electrical transient and EMI/EMC due to high
operating temperature. [60] Therefore, the communication scheme standardization would
feature:
• Copper Strap Format Bus Bars for inter-module communication [61]. Bus Bars
need to handle between 100A and 510 A ampacity (see section 5.3), Only thickness of
bus bars is subject to variation regarding the module current capability, for
standardisation purposes. Bus-bar connection with modules is made by clamps, in order
to reduce manufacturing costs relating to bolting, and ease of assembly and
disassembly.
• Capacitive coupling (coupling of both capacitors and transformers) for DC
isolation. [60]
• Layout of the modules must be symmetrical, two-wire, bi-directional,
asynchronous daisy chain for series connections; distributed for parallel connections.
[62]
• Combine both voltage and current mode scheme [60]: in order to minimize electrical
transient and EMC/EMI interface.

39
• Connectors close to each other [60] in order to contain current in a restricted area and
avoid electrical transient across the PCB.
• Zener Diodes [60] as protection devices placed before the cable termination points on
the PCB. Simple and cost-effective device.
• High quality multi-layer PCB [60], with a continuous ground plane layer.
FIGURE 18: MODULE/MODULE STANDARDIZED INTERFACE [60]
Impact on stakeholders are:
o First users:
Ø The model offers a high reliable and safe module to module interface, with
risk of failure reduced.
7.2 Module to BMS Interface
Different configuration of BMS/Module interface are compared in the table below:

40
TABLE 9: COMPARISON TABLE OF DIFFERENT BMS/MODULE INTERFACE
CONFIGURATION [63]
The Table base comparisons on 5 aspects, which are accuracy, reliability, manufacturability,
cost and power consumption. These serves as a measure of impact on different stakeholder’s
requirements.
The standardized control module below, is the control module used for the parallel module
with CAN gateway and Series modules with can Gateway.
FIGURE 19: CONTROL MODULE PROPOSED STANDARD [63]
It uses SPI bus to communicate with modules, connected in series or parallel or both. Then it
communicates via CAN bus toward the BMS.
For safety issues, each module has a fuse, that protects the cells from overcharging, and
external short circuits, control module is protected by an isolator.

41
Each module must have a standardized CLC chip (for instance an LTC6802s) with a 12 cell
entry located on the battery module for more accuracy. This CLC chip communicate data via
connectors and appropriate fusing located at the surface of the module toward the BMS.
Number of CLC required is proportional to the number of the cells inside the module.
Stakeholder impact:
o Manufacturers:
Ø Rather series connection of modules than parallel one: these is another
drawback on the standardized Tesla model S, as it uses parallel module
configuration. This increases cost and manufacturability of the BMS/interface
and the power consumption. [64]
o First and Second users:
Ø Power consumption affects cost for users.
o Second user:
Ø High accuracy of the system increase accuracy of SOH estimation. Hence,
increases reliability of modules sent for second use.
7.3 Module to car (or pack) Interface
Mechanical fittings must ideally be made with the same material used for packaging, with
regards to manufacturing and recycling purposes. It should be a simple and easy design, that
ease assembly and disassembly of the modules from the battery pack. Welding is proposed as
a low-cost and easier alternative to bolts and nuts, as the process requires less material (Lower
weight and size), however it makes the disassembly process and repurposing for second life
harder. The study then considers the use of clip fixings instead, which is commonly uses in

42
simple and non-durable designs. Clip fixings are machined directly on the module package.
The number of clips used increases with higher weight and sizes of the module.
Clip fixings must be present on all the faces that have a direct contact with the battery pack, in
order to provide stability. If there is only one interface between the module and the battery (for
instance modules located in the middle), larger clip fixings must be used. Impact on
stakeholders are:
o Manufacturers:
Ø Ease of assembling and disassembling, cost reduction due to clip fixing instead
of bolts and nuts, in along term basis.
o Recyclers:
Ø Reduce amount of material needed to recycle, which reduce cost of recycling
7.4 Packaging material standard
The ideal of passive materials standardization is to use one unique material that fits all the
external features and packaging of the module. This significantly reduce costs of
manufacturing and recycling the battery pack, hence impacting on the all overall costs of the
battery.
Module Packaging main objective is protection of the cells. Many safety issues related to Li-
ion are explosion and fire ignition due to poor packaging. The module packaging should meet
the same requirement as the whole battery packaging, that are settled by NEMA and IEC IP
standards, that are respectively settled for stationary systems and automotive application.
Combining their specifications, the packaging requirement are listed below:
1) The material must be able to sustain high mechanical forces abuses
2) The material must also be electrically safe; therefore, an isolate material is required.

43
3) Material should have a high resistance to vapour and liquid corrosion, as the cooling
method used is liquid cooling.
4) The material used must have a melting point higher than the Battery maximum
running temperature, in order to avoid melting.
5) Protect from physical intrusion (dust, liquid…)
6) The volume, weight and cost of material should also be important factor to consider,
as they will affect final performance and cost of the battery.
A good standard should meet the 4 first requirements and provide a fair balance between the
parameters listed in the fifth point, and this would be a glass fibre composite material. This
material is commonly used for module scale sizes enclosure, or slightly bigger such as some
HEV Battery packs. According to modulus diagrams, [65] glass fibre composites have higher
yield strength and lower density than metals (steel). They have a high thermal melting point
above 100°C and they have 0 thermal conductivity and low electrical conductivity.
Impact on stakeholders:
o First and second user:
Ø High reliability, durability and safety of the packaging, but high cost incurred.
o Manufacturers:
Ø Hard machinability and high material costs
8 Cost Analysis
Cost-benefit analysis is related to time gain thanks to ease of assembly and disassembly,
featured on the standardized BTMS, Module/Module interface and car/module interface.
Increased reliability and durability, decrease threat of warranty, thus cost related to risks.

44
Cost savings made in the upper supply-chain, at the battery manufacturer level, positively
impact on the rest of the stakeholders, as long as negative cost impact, such as the parallel
layout of modules, which negatively impact the manufacturing cost of the car.
Issues related to cost-assessment is that few quantifications are made, as it requires more data
that are OEMs property, with limited accessibility
Cost related to Academic and research staff: 45 minutes’ average per week spend by
project supervisor (meetings only, time for responding e-mail and correcting templates is not
taken in account), 14 weeks in total, plus 1-hour interview with academic researcher. Cost
per hour is £50, which gives a total of £575.
Cost related to student research: An average of 8 hours per week consecrated by the author,
for a total of 23 weeks (including bank holidays). Cost per hour is £15, which gives a total of
£2760. Therefore, the total project cost is 2760+575= £3335.
9 Recommendation for future work
The main issue encountered in this study wad the limited data accessibility on each car model
and the trading-off between different features that affects different stakeholder’s requirements,
regarding electrical, thermal system, interface and packaging standardisation.
Recommendation for further work includes:
v Setting an order of priority for stakeholder’s requirement, with regard to each feature
that is attempted to standardize. This allows a better selection, when it comes to trade-
offs.
v Table of interactions between different stakeholder’s requirements.
v Accuracy of data: Dismantle a set of different car models batteries. Test and record
their characteristics directly.

45
v More accessible data on each car model: Detailed information on each stage of the
design process for each car model: Bill of material, CAD&CAM files, risk assessment
and costs specification, are useful to increase the accuracy of the study and the cost
benefit analysis.
v Standard should always be updated, whenever a validated improvement in one area of
the battery is made. In facts, researchers seek to lighter, safer and more performant
batteries. New chemistries are developed such as Li-S and Lithium-air, that in a short
term basis may be validated. Therefore, the standard rules need to be reviewed.
An attempt of standardizing the battery cell format is available on Appendix C in section 12.2.
10 Conclusion
This study highlights an overall positive aspect regarding ethics and costs on standardizing the
external features of a BEV module. In fact, most of the positive impact noticed are for second
users and recyclers. With regard to circular economy, standardisation has then a positive impact
in enhancing this concept. However, some concession at the top of the battery life-chain are
done, with regard to manufacturability, cost and performance, which are balanced by other
positive aspect of standardisation such as circular economy. Issues related to this study are
mainly quantitative, as many of the impacts on stakeholders are noticed but hard to quantify,
especially with regard to cost. Another possible study would be to quantify the cost impact on
stakeholders of each proposes standard.

46
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12 Appendices
12.1 Appendix A: Acceleration and Range theory [66]

56
12.2 Appendix B: Standardization of the Cell Format

57

58

59

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12.3 Appendix C: List of Tables for electrical standardization [67], [68]

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