Transcript Lithium-Ion Battery + Nano

Lithium-Ion Battery
+
Nano-technology
___________________________
?
An Overview of the battery technology that powers
our mobile society.
Bryan Lamble
Energy Law, Spring 2008
Battery History and Basics
The modern battery was developed by Italian
physicist Alessandro Volta in 1800.
Ingredients: Zinc, Saltwater paper, and Silver
An electrochemical reaction.
The “Voltaic Pile”
The Voltaic Pile
Battery Chemistry 101
Electrochemical reaction - a chemical reaction
between elements which creates electrons.
Oxidation occurs on the metals (“electrodes”),
which creates the electrons.
Electrons are transferred down the pile via the
saltwater paper (the “electrolyte”).
A charge is introduced at one pole, which builds
as it moves down the pile.
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.
Standard Modern Batteries
Zinc-Carbon: used in all inexpensive AA, C and 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 Energizer
batteries, the electrodes are zinc and manganeseoxide, with an alkaline electrolyte. (disposable)
Lead-Acid: used in cars, the electrodes are lead and
lead-oxide, with an acidic electrolyte. (rechargeable)
Battery types (cont’d)
Nickel-cadmium: (NiCd)

rechargeable,

“memory effect”
Nickel-metal hydride: (NiMH)

rechargeable

no “memory effect”
Lithium-Ion: (Li-Ion)

rechargeable

no “memory effect”
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 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)
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.
The Periodic Table

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-Ion-moving electrodes.
The Lithium-Ion battery has a slightly lower
energy density than Lithium metal, but is
much safer. Introduced by Sony in 1991.
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
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)
Environmental Impact of
Li-Ion Batteries
Rechargeable batteries are often recyclable.
Oxidized Lithium is non-toxic, and can be
extracted from the battery, neutralized, and
used as feedstock for new Li-Ion batteries.
The Intersection
“In terms of weight and size, batteries have become one
of the limiting factors in the development of electronic
devices.”
http://www.nanowerk.com/spotlight/spotid=5210.php
“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.”
“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 (10-9)
1 nanometer : 1 meter :: 1 marble : Earth
1 sheet of paper = 100,000 nanometers
Nano S & T (cont’d)
Nano-science: research of the 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”
Nano S & T (cont’d)
Nano-technology: the use of nanoscale 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.
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.
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...
The Director of the Institute of Chemistry at
the Chinese Academy of Sciences published
a paper in February describing the novel
carbon nanocomposite above as “a promising
[electrode] material for lithium-ion batteries.”
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.”
The Nano-technology
solution...
“The lithium is stored in a forest of tiny silicon
nanowires, each with a diameter one onethousandth 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…
•
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.
The Potential of Li-Ion
Batteries
Electrodes that don’t deteriorate
metallic tin with carbon hollow spheres
silicon nanowires
2D & 3D battery design
“Forested” rods on a thin film electrode
“Stacked” rods in a truck bed
Nano + Li-Ion = ?
Nanotechnology and Li-Ion applications in the
commercial sector are apparent...
lighter, more powerful batteries increase
user mobility and equipment life.
DeWalt 36volt cordless power tools
Nanotechnology & Li-Ion applications in the
residential sector are not so obvious...
HVAC system batteries? Micro-generated
energy storage?
Micro-Generated
Energy Storage
Li-Ion batteries’ high energy density allows
batteries them to power complex machinery.
Li-Ion batteries recharge quickly and hold
their charge longer, which provides flexibility
to the micro-generator.
particularly helpful for wind and solar
generators!
Lightness, and power per volume allow for
storage and design flexibility.
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.
Links to References
http://electronics.howstuffworks.com/battery.htm
http://everything2.com/e2node/Lithium%2520ion%2520battery
http://www.batteryuniversity.com
http://news-service.stanford.edu/news/2008/january9/nanowire010908.html
http://www.nano.gov/html/research/industry.html
http://en.wikipedia.org/wiki/Buckminster_Fuller
http://www.nanowerk.com/spotlight/spotid=5210.php