Li-ion

Short for Lithium-ion, Li-ion is a fragile technology requiring protector circuit, the Li-ion is used where very high energy density is needed and cost is secondary. Li-ion batters are generally more expensive but have never experienced memory issues that have affected other battery technologies.
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.