3. CONTENTS
Need of Energy Storage
Devices commonly used for Energy storage
Comparison among Energy storage devices
History of Supercapacitors (SCs)
Merits and Demerits of Supercapacitors
Applications of Supercapacitors
Strategies to improve energy density of SCs
Role of Electrode materials
Role of electrolytes
Electrochemical measurements
Asymmetric electrode to increase
4. Growing Population Depletion of Fossil Fuels
Trend of Portable Devices Discontinuous nature of Renewable Resources
NEED OF ENERGY STORAGE DEVICES
6. COMPARISON AMONG ENERGY STORAGE
DEVICES
Charging Time
Capacitors Batteries
1-10s 1-10s 10-60 minutes
Cyclic Life 1000000 1000000 500-1000
Service Life 10-15 Years 10-15 Years 5-10 Years
Cell Voltage Drop Remain sameDrop
Energy density Moderate Low Very High
Power density High High Low
Weight 1-10g 1-10g 1g-10kg
Storage
Mechanism Static ElectrochemicalStatic/EC
Charging OverNot overNot over
9. In 1957 Becker employed 1st time porous carbon electrode in
capacitors
In 1970 SOHIO company introduce 1st electrochemical capacitors
for commercial applications
In 1978 NEC (Nippon Electric Company) introduced the term“Supercapacitor”
In 1990s Conway’s group developed the concept of “pseudo
capacitance”
In 2006 Zhang and Hu introduced hybrid electrode material strategy
(K. Samantara and Ratha 2018)
HISTORY OF SUPERCAPACITORS
10. High power density
High Cyclic efficiency (95%)
Good cryogenic properties
Environmental friendly nature
Wide range of operating temperature
High rate capability
Shorter charging time
Longer life
WHY SUPERCAPACITORS?
12. WHY NOT BATTERIES?
Low power density
Poor cycle life (shelf life)
Low power density
Self-discharging (Fast at high temperature),
Expensive and fire hazards nature
(Kumar, Choudhary et al. 2018)
14. PARTS OF EDLC SCS
1- Electrode
2-Electrolyte
3-Separator
4-Current Collector
https://doi.org/10.1149/2.017310jes
15. STRATEGY TO IMPROVE ENERGY DENSITY
Formula of energy density
C = Specific capacitance
V = Potential window
16. FACTOR AFFECTING SPECIFIC CAPACITANCE
1- Nature of electrode material (High conductivity)
2- Structure of electrode material (Porous)
3- Surface area of the electrodes
4- Distance between the plates
5- Dielectric Permittivity of the medium
6- Effect of binder, effect of electrolyte concentration, effect of electrode
thickness, effect of redox active substances
(Tsay, Zhang et al. 2012)
(Azari, Rahmanifar et al. 2017)
18. CLASSIFICATION OF SCS BASED ON EMS
SCS
EDLCPseudo -capacitor
Based on EDL Materials
( Carbon based Materials)
Based on Redox Materials
(TMOs & CPs) Hybrid
SCs
Based on composite of EDL & Redox Materials
Symmetric 1st GenerationSymmetric 2nd Generation
Asymmetric 3rd Generation
(Ji, Ji et al. 2015)
19. FEATURES OF NOVEL EMS
High electronic Conductivity
High surface area
Controlled pore structure
Low Cost
High temperature and cyclic stability
High theoretical capacitance
Good corrosion resistance
(Kate, Khalate et al. 2018)
20. CARBONACEOUS MATERIALS
MERITS/DEMERITS /SOLUTION
MERITS
Thermal /Chemical /Cyclic stability
Good electrical conductivity
DEMERITS
Low specific capacitance
SOLUTION OF THE PROBLEM
Their Nanostructure formation with TMOs improved the specific capacitance
High surface area
Low cost
(Parveen, Ansari et al. 2017)
21. TMOS MERITS/DEMERITS /SOLUTION
MERITS OF TMOs
High theoretical capacitance
Store charge by fast faradic process
DEMERITS OF TMOs
Less surface area
Poor cyclic performance
Low conductivity
SOLUTION OF THE PROBLEM
Nanostructure formation of TMOs improved its surface area
Composite Formation with carbonaceous materials improve their conductivity
22. CPS MERITS/DEMERITS /SOLUTION
MERITS OF CPs
Controlled conductivity
Low cost
Low Equivalent series resistance
DEMERITS OF CPs
Poor cyclic stability
Less specific capacitance
Less surface area
SOLUTION OF THE PROBLEM
Composite formation of CPs with TMOs improved its specific capacitance
Composite formation of CPs with Carbonaceous materials improved its
surface area and cyclic stability
23. ROLE OF ELECTROLYTES IN SCS
Electrolytes nature controlled the Potential window (V)
P.W is the voltage range between which electrolyte neither oxidized or reduced
P.W is calculated as
P.W = Reduction Potential – Oxidation potential
Aqueous electrolyte have less P.W due to dissociation of water
P.W = Cathodic limit– Anodic limit
OR
Ionic resistivity in electrolyte reduce the Power density of the SCs
Low concentration of electrolyte reduce P.W and Energy density
Interaction b/w electrolyte and electrode material control the cyclic stability
24. FEATURES OF NOVEL ELECTROLYTE
Wide potential window
High ionic mobility / high e resistivity
Low solvated ionic radius
Low viscosity and volatility
High purity and safety
Low toxicity and cost
Moderate concentration
(Wang, Zhang et al. 2012)
26. AQUEOUS ELECTROLYTES (AELS)
MERITS OF AELs
High Conductivity & concentration of ions ( low ESR)
Low ionic resistivity and cost
Environmental friendly and non- corrosive nature
Low viscosity but high safety
DEMERITS OFAELs
Low Potential window
SOLUTION OF THE PROBLEM
Super-concentrated salt solution can extend P.W up to 3.0V
P.W of AELs can also be improved by using a symmetric configuration
EXAMPLES H2SO4 Na2SO4 KOH
27. ORGANIC ELECTROLYTES (OELS)
MERITS OF AELs
Wide potential window
Low ionic conductivity (high ESR)
High Toxicity and volatility
High flammability and cost
DEMERITS OF AELs
High viscosity
Examples
Acetonitrile Propylene carbonate
28. SOLID ELECTROLYTES (SELS)
Solid electrolytes further classified into Polymer and Ionic
solid electrolytes
Polymer electrolytes may be “Dry polymer” or “Gel Polymer”
Gel polymer have advantage due to High ionic conductivity
Ionic solid electrolyte may be Crystalline , amorphous or Mixed
30. CYCLIC VOLTAMMETRY (CV)
Specific capacitance Formula
Ccv = I / (ΔV/ Δt) m
I = current
ΔV/ Δt = Potential sweep rate
m = mass of deposited analyte
Basic Purpose To measure Voltage windowTo measure Specific capacitance
To measure cyclic life
32. ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY
Basic Purpose To measure ESR of SCsTo measure Capacitance of SCs
To measure non- Ideality of a SCs
Formula For Specific capacitance
CEIS = 1 / m x J x 2πf x Z ⸗
Semicircle indicate the Rct
Vertical line represent the fast ion
diffusion (EDLC)
Nyquist Impedanc