2. Primary vs. Secondary Batteries
Primary batteries are disposable because
their electrochemical reaction cannot be
reversed.
Secondary batteries are rechargeable,
because their electrochemical reaction
can be reversed by applying a certain
voltage to the battery in the opposite
direction of the discharge.
3. Standard Modern Batteries
Zinc-Carbon: used in all inexpensive AA, C and
Zinc-Carbon
D dry-cell batteries. The electrodes are zinc and
carbon, with an acidic paste between them that
serves as the electrolyte. (disposable)
Alkaline: used in common Duracell and
Alkaline
Energizer batteries, the electrodes are zinc and
manganese-oxide, with an alkaline electrolyte.
(disposable)
Lead-Acid: used in cars, the electrodes are lead
Lead-Acid
and lead-oxide, with an acidic electrolyte.
(rechargeable)
5. Recharge-ability & the “memory
effect”
Recharge-ability: basically, when the
direction of electron discharge (negative to
positive) is reversed, restoring power.
the Memory Effect: (generally) When a
Effect
battery is repeatedly recharged before it has
discharged more than half of its power, it will
“forget” its original power capacity.
Cadmium crystals are the culprit! (NiCd)
6. Lithium.
Periodic Table Symbol: Li
Atomic Weight: 3 (light!)
Like sodium and potassium, an alkali metal.
(Group 1 – #s 1 through 7)
Highly reactive, with a high energy density.
Used to treat manic-depression because it is
particularly effective at calming a person in
a “manic” state.
8. Lithium (Ion) Battery Development
In the 1970’s, Lithium metal was used but
its instability rendered it unsafe and
impractical. Lithium-cobalt oxide and
graphite are now used as the lithium-Ionmoving electrodes.
The Lithium-Ion battery has a slightly
lower energy density than Lithium metal,
but is much safer. Introduced by Sony in
1991.
9. Advantages of Using
Li-Ion Batteries
POWER – High energy density means greater
power in a smaller package.
160% greater than NiMH
220% greater than NiCd
HIGHER VOLTAGE – a strong current allows it
to power complex mechanical devices.
LONG SHELF-LIFE – only 5% discharge loss
per month.
10% for NiMH, 20% for NiCd
10.
11. Disadvantages of Li-Ion
EXPENSIVE -- 40% more than NiCd.
DELICATE -- battery temp must be
monitored from within (which raises the
price), and sealed particularly well.
REGULATIONS -- when shipping Li-Ion
batteries in bulk (which also raises the
price).
Class 9 miscellaneous hazardous
material
UN Manual of Tests and Criteria (III,
38.3)
12. The Intersection
“In terms of weight and size, batteries have become
one of the limiting factors in the development of
electronic devices.”
http://“The problem with...lithium batteries is that
none of the existing electrode materials alone can
deliver all the required performance characteristics
including high capacity, higher operating voltage,
and long cycle life. Consequently, researchers are
trying to optimize available electrode materials by
designing new composite structures on the
nanoscale.”
13. “Nano”-Science and
-Technology
The attempt to manufacture and control
objects at the atomic and molecular level
(i.e. 100 nanometers or smaller).
1 nanometer = 1 billionth of a meter (109
)
1 nanometer : 1 meter :: 1 marble : Earth
1 sheet of paper = 100,000 nanometers
14. Nano S & T (cont’d)
Nano-science: research of the
Nano-science
differing behavioral properties of
elements on the nano scale.
Conductivity (electric/thermal), strength,
magnetism, reflectivity.... Sometimes
these properties differ on the nanoscale.
Carbon is particularly strong on the nano
scale.
C60 = “Fullerene,” a.k.a “buckyball”
15. Nano S & T (cont’d)
Nano-technology: the use of nanoscale
Nano-technology
materials in critical dimensions of
mechanical devices.
Nanotubes -- carbon molecules have greater
mechanical strength at less weight per volume.
Nanotransistors -- the computer industry’s best
technology features microchips with transistors as
small as 45nm.
Batteries with nanoscale materials deliver
more power quickly with less heat.
16. Environmental Impacts and Use of
Nanotechnology
Smaller scale technology means less
resources used and less waste.
The EPA recently issued research grants
to use nanotechnology to develop new
methods of detecting toxins in water.
17. An example of the intersection...
From graphite to metallic tin (electrodes), but
metallic tin isn’t great either…yet.
“...the biggest challenge for employing
metallic tin...is that it suffers from huge
volume variation during the lithium
insertion/extraction cycle, which leads to
pulverization of the electrode and very rapid
capacity decay."
But nanotechnology could offer a solution...
18. Another example...
“The storage capacity of a Li-Ion battery is
limited by how much lithium can be held in
the battery's anode, which is typically made of
carbon. Silicon has a much higher capacity
than carbon, but also has a drawback.”
“Silicon placed in a battery swells as it
absorbs positively charged lithium atoms
during charging, then shrinks during use as the
lithium ion is drawn out of the silicon. This
cycle typically causes the silicon to pulverize,
degrading the performance of the battery.”
19. The Nano-technology solution...
“The lithium is stored in a forest of tiny
silicon nanowires, each with a diameter
one one-thousandth the thickness of a
sheet of paper. The nanowires inflate to
four times their normal size as they soak
up lithium but, unlike other silicon
shapes, they do not fracture.”
See next slide…
20. • Photos taken by a scanning electron microscope of silicon
nanowires before (left) and after (right) absorbing lithium. Both
photos were taken at the same magnification. The work is
described in “High-performance lithium battery anodes using
silicon nanowires,” published online Dec. 16 in Nature
Nanotechnology.
24. Finally, an interesting idea...
Background:
battery research results in annual capacity gains of
approximately 6%
Moore’s Law: The number of transistors on a
computer microchip will double every two years.
(40 years of proof!)
Idea: If battery technology had developed at
the same rate, a heavy duty car battery would
be the size of a penny.
