The nature of the lithium-ion chemistries produces high amounts of electricity with light-weight materials, so 18650 batteries generally provide the best power sources for portable electronic devices. And, continuing research into lithium-ion and lithium-polymer chemistries and materials will increase the capabilities of these batteries for some time.

But, do not expect to find bare lithium-ion cells on your distributor’s shelf. Reputable cell manufacturers sell only to qualified and authorized companies that place these cells in battery packs. Those packs include electronics that protect users and batteries.

Safety circuits assume people will do something wrong, such as try to over-charge a pack or connect it to the wrong charger. In these cases, the safety circuits can stop the charge, temporarily reset the charger or blow a fuse to stop charging completely and prevent anyone from using the battery pack again.

Polymer lithium ion battery have the same common electrochemistry as conventional lithium ion batteries. They have a lithiated oxide cathode and a graphite anode held together in a binder matrix of polyvinlydiene fluoride and coated and/or laminated to a current collector grid. However, they contain a highly porous separator, which converts to a gel when a minimum amount of electrolyte is added to operate the cell. Lithium polymer technology uses stacked plate cell architecture, as opposed to a wound jelly roll found in conventional lithium ion cells, which means that they consist of die-cut anode and cathode plates that are about the size of the battery and are stacked on top of each other like a deck of cards, with the plates connected in parallel.

Lithium polymer batteries have comparable energy density to NiMh batteries and are achieving cost parity. The cells are sealed in a plastic aluminum laminate, so if the battery sees an overcharge condition, the seal ruptures and vents any gases due to electrolyte oxidation and the cell shuts down rather than having steel or aluminum casings fragment, as in the case of lithium ion batteries that may result in metal shards.