Li-ion batteries began appearing in the early 1990's. They have the highest energy density of all rechargeable batteries. But due to safety concerns, developers had to incorporate special features into the design to prevent explosion under certain conditions. These concerns, along with market demands for thinner batteries, led scientists to investigate Li-ion polymer technology. VEV-3288S Walkie Talkie Li-ion Battery. Stay powered up for a long time, It has the longest performance with no memory effect, highest quality, it is 100% compatible with original equipment.