Reference number: CH000350

Issues and information on LI-ION batteries.

Issue:

Issues and information on LI-ION batteries.

Additional information:

Li-ion batteries are a fragile technology requiring protector circuit; the Li-ion is used where very high energy density is needed and cost is secondary.

Pioneering work for the lithium battery began in 1912 by G. N. Lewis but it was not until the early 1970's that the first non-rechargeable lithium batteries became commercially available. Attempts to develop rechargeable lithium batteries followed in the eighties, but failed due to safety concerns.

Lithium is the lightest of all metals, has the greatest electrochemical potential, and provides the largest energy content. Rechargeable batteries using lithium metal as an electrode are capable of providing both high voltage and excellent capacity, resulting in an extraordinary energy density.

After much research during the eighties, it was found that occasional shorts from lithium dendrites could cause thermal run-away. The cell temperature quickly approaches the melting temperature of lithium which results in violent reactions. A large quantity of rechargeable lithium batteries sent to Japan had to be recalled in 1991 after a battery in a cellular phone exploded and inflicted burns to a man's face.

Because of the inherent instability of lithium metal, especially during charging, research shifted to a non-metallic lithium battery using lithium ions from chemicals such as Lithium-Cobalt Dioxide (LiCoO₂ ). Although slightly lower in energy density than with lithium metal, the Li-ion is safe, provided certain precautions are met when charging and discharging. In 1991, Sony commercialized the Li-ion and is presently the largest supplier of this type of battery.

Distinct advantages of today's Li-ion batteries are:

The energy density of the Li-ion is at least twice that of the NICAD and its load current rating is reasonably high. In fact, the Li-ion behaves similarly to the NICAD in terms of discharge characteristics. In addition, the Li-ion has a relatively low self-discharge.

No memory effect

500 to 800 charging cycles

Negative attributes of today's NiMH batteries are:

Susceptible to damage from overcharge and over discharge.

Charging: Only use battery chargers especially designed for the Li-ion battery.

Caution: Li-ion batteries have a very high energy density. Exercise precaution when handling and testing. Do not short circuit, overcharge, crush, mutilate, nail penetrate, apply reverse polarity, expose to high temperature or disassemble. High case temperature resulting from abuse of the cell could cause physical injury. Never try to charge a non-rechargeable lithium battery! Attempting to charge these batteries can cause explosion and fire which spreads toxic material that can inflict injury and damage equipment.

Important: In case of rupture, leaking electrolyte or any other cause of skin or eye exposure to the electrolyte, immediately flush with water. If eye exposure, flush with water for 15 minutes and consult physician.

Solutions:

Below is a listing of issues and solutions to those issues relating to the NiMH batteries.

Main battery does not charge

• See document CH000353 for additional information to why the main battery may not charge.