Sony brings lithium-ion batteries to the mass market

Sony and battery partner Asahi Kasei turned the laboratory advances into a commercial product in 1991. The new cells combined a lithium cobalt oxide cathode with a carbon anode and included separators, electrolytes and control measures suitable for mass production. Compared with common rechargeable chemistries of the period, lithium-ion offered a higher operating voltage, greater energy density and no need for routine full discharge before charging. Camcorders were an early showcase, followed by laptops, digital cameras and mobile phones. The milestone was not a single final recipe: manufacturers continued refining carbon materials, electrolytes, separators and protective circuits. Lithium-ion became dominant because the whole cell system improved together, not merely because lithium itself stores energy efficiently.