Lithium ion batteries are a huge technological advancement from lead acid batteries which have existed since the late 1850's. Thanks to their low weight, high energy density and slower loss of charge when not in use, these have become the preferred choice for consumer electronics. Lithium-ion cells with cobalt cathodes hold twice the energy of a nickel-based battery and four-times that of lead acid. Despite being a superior consumer battery, lithium-ion batteries still have some drawbacks. Current manufacturing technology is reaching the theoretical energy density limit for lithium ion batteries and overheating leading to thermal runaway i.e. "venting with flame" is a serious concern.
from Geochemistry News -- ScienceDaily http://ift.tt/1CQBWAV