the polyanion. [ 31 ] In 1991, Sony and Asahi Kasei released the first commercial lithium-ion battery. In 1996, Goodenough, Akshaya Padhi and coworkers identified lithium iron phosphate ( LiFePO 4 ) and other phospho- olivines (lithium metal phosphates with the same structure as mineral olivine) as cathode materials. [ 32 ] In