Is Lithium-ion the Ideal Battery?
For many years, nickel-cadmium had been the only suitable
battery for portable equipment from wireless communications to
mobile computing. Nickel-metal-hydride and lithium-ion emerged
In the early 1990s, fighting nose-to-nose to gain customer's
acceptance. Today, lithium-ion is the fastest growing and most
promising battery chemistry.
The New Lithium-ion Battery
for the Lexis Light now only weights seven pounds, it has (2) 18
AH Cells Offering three times the power of the standard battery
and gives the Lexis Light 3 times more power meaning it will go
up steeper inclines and travel three times as far as sealed lead
acid. The New Lithium-ion Battery for the Lexis Light can be
fully charged in under 30 minutes and is good for 5000 cycles,
that's ten time more life then the standard lead acid battery.
The New Lithium-ion Battery for the Lexis Light is not only FAA
approved it is recommended by airlines across the country and
throughout the world..
The lithium-ion battery
Pioneer work with the lithium battery began in 1912 under G.N.
Lewis but it was not until the early 1970s when the first
non-rechargeable lithium batteries became commercially
available. lithium is the lightest of all metals, has the
greatest electrochemical potential and provides the largest
energy density for weight.
Attempts to develop rechargeable lithium batteries failed due
to safety problems. Because of the inherent instability of
lithium metal, especially during charging, research shifted to
a non-metallic lithium battery using lithium ions. Although
slightly lower in energy density than lithium metal,
lithium-ion is safe, provided certain precautions are met when
charging and discharging. In 1991, the Sony Corporation
commercialized the first lithium-ion battery. Other
manufacturers followed suit.
The energy density of lithium-ion is typically twice that of
the standard nickel-cadmium. There is potential for higher
energy densities. The load characteristics are reasonably good
and behave similarly to nickel-cadmium in terms of discharge.
The high cell voltage of 3.6 volts allows battery pack designs
with only one cell. Most of today's mobile phones run on a
single cell. A nickel-based pack would require three 1.2-volt
cells connected in series.
Lithium-ion is a low maintenance battery, an advantage that
most other chemistries cannot claim. There is no memory and no
scheduled cycling is required to prolong the battery's life.
In addition, the self-discharge is less than half compared to
nickel-cadmium, making lithium-ion well suited for modern fuel
gauge applications. lithium-ion cells cause little harm when
Manufacturers are constantly improving lithium-ion. New and
enhanced chemical combinations are introduced every six months
or so. With such rapid progress, it is difficult to assess how
well the revised battery will age.
Storage in a cool place slows the aging process of lithium-ion
(and other chemistries). Manufacturers recommend storage
temperatures of 15°C (59°F). In addition, the battery should
be partially charged during storage. The manufacturer
recommends a 40% charge.
The most economical lithium-ion battery in terms of
cost-to-energy ratio is the cylindrical 18650 (size is 18mm
This cell is used for mobile computing and other applications
that do not demand ultra-thin geometry. If a slim pack is
required, the prismatic lithium-ion cell is the best choice.
These cells come at a higher cost in terms of stored energy.
energy density - potential for yet higher capacities.
need prolonged priming when new. One regular charge is all
Relatively low self-discharge - self-discharge is less than
half that of nickel-based batteries.
Maintenance - no periodic discharge is needed; there is no
cells can provide very high current to applications such as
protection circuit to maintain voltage and current within
to manufacture - about 40 percent higher in cost than
The lithium polymer battery
The lithium-polymer differentiates itself from conventional
battery systems in the type of electrolyte used. The original
design, dating back to the 1970s, uses a dry solid polymer
electrolyte. This electrolyte resembles a plastic-like film
that does not conduct electricity but allows ions exchange
(electrically charged atoms or groups of atoms). The polymer
electrolyte replaces the traditional porous separator, which
is soaked with electrolyte.
The dry polymer design offers simplifications with respect to
fabrication, ruggedness, safety and thin-profile geometry.
With a cell thickness measuring as little as one millimeter
(0.039 inches), equipment designers are left to their own
imagination in terms of form, shape and size.
profile - batteries resembling the profile of a credit card
form factor - manufacturers are not bound by standard cell
formats. With high volume, any reasonable size can be
Lightweight - gelled electrolytes enable simplified
packaging by eliminating the metal shell.
safety - more resistant to overcharge; less chance for
energy density and decreased cycle count compared to
standard sizes. Most cells are produced for high volume
cost-to-energy ratio than lithium-ion
Restrictions on lithium content for air travel
Air travelers ask the question, "How much lithium in a
battery am I allowed to bring on board?" We differentiate
between two battery types: Lithium metal and lithium-ion.
Most lithium metal batteries are non-rechargeable and are used
in film cameras. Lithium-ion packs are rechargeable and power
laptops, cellular phones and camcorders. Both battery types,
including spare packs, are allowed as carry-on but cannot
exceed the following lithium content:
- 2 grams for lithium metal or lithium alloy batteries
- 8 grams for lithium-ion batteries
Lithium-ion batteries exceeding 8 grams but no more than 25
grams may be carried in carry-on baggage if individually
protected to prevent short circuits and are limited to two
spare batteries per person.
How do I know the lithium content of a lithium-ion
battery? From a theoretical perspective, there is no
metallic lithium in a typical lithium-ion battery. There is,
however, equivalent lithium content that must be considered.
For a lithium-ion cell, this is calculated at 0.3 times the
rated capacity (in ampere-hours).
Example: A 2Ah 18650 Li-ion cell has 0.6 grams
of lithium content. On a typical 60 Wh laptop battery with 8
cells (4 in series and 2 in parallel), this adds up to 4.8g.
To stay under the 8-gram UN limit, the largest battery you can
bring is 96 Wh. This pack could include 2.2Ah cells in a 12
cells arrangement (4s3p). If the 2.4Ah cell were used instead,
the pack would need to be limited to 9 cells (3s3p).
Restrictions on shipment of lithium-ion batteries
shipping lithium-ion batteries in bulk is responsible to
meet transportation regulations. This applies to domestic
and international shipments by land, sea and air.
Lithium-ion cells whose equivalent lithium content exceeds
1.5 grams or 8 grams per battery pack must be shipped as
"Class 9 miscellaneous hazardous material." Cell capacity
and the number of cells in a pack determine the lithium
is given to packs that contain less than 8 grams of lithium
content. If, however, a shipment contains more than 24
lithium cells or 12 lithium-ion battery packs, special
markings and shipping documents will be required. Each
package must be marked that it contains lithium batteries.
lithium-ion batteries must be tested in accordance with
specifications detailed in UN 3090 regardless of lithium
content (UN manual of Tests and Criteria, Part III,
subsection 38.3). This precaution safeguards against the
shipment of flawed batteries.
batteries must be separated to prevent short-circuiting and
packaged in strong boxes.