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Introduction
of Polymer Lithium Ion (PLI)
From the 1970's and throughout most of the 1980's the rechargeable
battery of choice for portable devices was almost exclusively
the NiCd (Nickel Cadmium) battery. Concerns about safety, the
environment, memory effect problems and their relatively short
life span have seen the NiCd battery being replaced by NiMH
(nickel Metal hydride) battery. The NiMH battery overcame some,
but not all of these problems, with concerns about safety and
the environment still being prevalent.
Since the first commercial introduction of the (Liquid electrolyte)
lithium-ion battery by Sony in 1990, their sales have soared.
Lithium-ion battery quickly overtook the market share of NiMH
battery and is poised to overtake the NiMH battery. Their
lack of memory effect, minimal environmental impact and increase
in safety combined with better power characteristics and longer
life span have found a ready market with Original Equipment
Manufacturers ("OEM") portable device manufacturers.
The seemingly insatiable appetite of consumers for all things
electronic and portable has created exponential growth of
demand for smaller but even more powerful and reliable batteries
to drive these products. At this time, the technology of choice,
balancing power, weight, reliability, durability, safety,
cost and environmental concerns, is the lithium-ion battery.
Until 1999, the only Lithium-ion batteries available to portable
device manufacturers were those utilizing liquid electrolytes.
The introduction of commercially viable supplies of lithium-ion
polymer batteries has excited portable device manufacturers
because such batteries are much thinner, lighter and more powerful,
permitting greater design flexibility. Mobile or cellular phone,
PDA, and notebook computer manufacturers are already shipping
products equipped with PLI. Currently the market is abuzz with
talk about being able to produce mobile or cellular phones with
"wrap-around" batteries, and notebook computers in
which battery "sheets" fit behind the LCD screen,
without sacrificing power to weight considerations like the
PDA currently does. About the only problem for portable devices
manufacturers willing to incorporate PLI into their products
at this time is their restricted availability. The principals
of the group saw the market potential of PLI, particularly in
the PRC market, which will provide the group an expansion thrust
to become one of the leading distributors there.
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Progression
of Polymer Lithium-Ion (PLI)
| Lead
Acid: |
Low capacity,
heavy weight, high self-discharge rate, contains
toxic material and non-environmentally friendly. |
| Nickel-cadmium (NiCd): |
Low capacity, heavy weight,
high self-discharge rate, contains toxic material
and non-environmentally friendly. |
| Nickel
-metal hydride (NiMH): |
Medium
capacity, heavy weight, high self discharge rate,
contains toxic material, non environmentally friendly
and comparatively short cycle life. |
Lithium:
| 1st
Generation: Lithium Metal (Li-Metal) |
have safety
problem because Lithium is unstable at solid stage. |
| 2nd Generation:
Liquid Lithium ion (Lli-ion) |
Since the liquid electrolytes
was toxic and flammable, it must have a rigid metal
housing which adds considerable weight and design
restriction. |
| 3rd
Generation: Lithium Polymer (Li-Polymer) |
Use a
Lithium metal anode and a solid or gel polymer electrolyte,
but are plagued by safety issues related to Lithium
metal and have low life cycle. |
| 4th Generation:
Polymer Lithium Ion (PLI) |
The most advanced technology
in Lithium-based rechargeable battery. Using safe
polymer materials, it offers better safety, longer
cycle life, better energy density, much more flexible
in cell design, and no toxic material hence environmentally
friendly. |
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b)
Evolution & advantages of Lithium Ion (PLI)
| Light
Weight: |
Mainly
using polymer material, it has lightest weight among
the entire category. |
| High Energy capacity: |
Reserve more energy for longer
operation time for all potable devices. |
| Long
Life Cycle: |
500 Plus |
| Low self-discharge
rate: |
5-6% per month |
| Environmentally
friendly: |
Contains
no lead, acid, Nickel and Cadmium materials and
no restriction on disposal and transportation. |
| High scalability: |
No need to use metal housing,
it has high flexibility in designing various shapes
and sizes. It is destined to be the major power
for all future portable devices. |
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Comparisons
of the characteristics of the aforementioned batteries
are as follows:
| Battery
Type |
NiCd |
NiMH |
Li-ion |
Li-ion
Polymer (PLI) |
| Year
of Introduction |
1948 |
1991 |
1991 |
2000 |
| Voltage
(V) |
1.2 |
1.2 |
3.6 |
3.6 |
| Capacity
Energy Density (Wh/I) |
200 |
300 |
350 |
290 |
| Weight
Energy Density (Wh/kg) |
50-60 |
60-90 |
120 |
100-160 |
| Power
Density |
190 |
200 |
300 |
250 |
| Energy
Efficiency (%) |
75 |
70 |
>95 |
>75 |
| Service
Life (cycles) |
300 |
500 |
1000 |
1000-1500 |
| Memory
Effect |
Yes |
Few |
None |
None |
| Size |
Cylindrical
/ Square |
Cylindrical/
Square |
Cylindrical/
Square |
Thin
Sheet |
| Toxicity |
Cd |
None |
None |
None |
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