A Li-Po battery, or more correctly lithium-ion polymer battery (abbreviated variously as LiPo, LIP, Li-poly and others), is a rechargeable battery of lithium-ion technology in a pouch format. Unlike cylindrical and prismatic cells, LiPos come in a soft package or pouch, which makes them lighter but also less rigid.
Just as with other lithium-ion cells, LiPos work on the principle of intercalation and de-intercalation of lithium ions from a positive electrode material and a negative electrode material, with the liquid electrolyte providing a conductive medium. To prevent the electrodes from touching each other directly, a microporous separator is in between which allows only the ions and not the electrode particles to migrate from one side to the other.
LiPo cells follow the history of lithium-ion and lithium-metal cells which underwent significant research during the 1980s, reaching a significant milestone with Sony's first commercial cylindrical Li-ion cell in 1991. After that, other packaging techniques evolved, including the pouch format now also called "LiPo". In 2015, the High-Voltage Lithium Polymer Battery were introduced to the Hobby and DIY Market by Hyperion HK ltd., this new HvLi technology ushers in an increase of 10% in overall energy density.