The Energizer Ultimate Lithium batteries are different from alkaline batteries in both chemistry and construction. The spiral construction featuring two long, thin electrodes rolled together to form a jellyroll shape provides 20 times interfacial surface area than a standard alkaline. Electrodes in lithium iron disulfide batteries are isolated from each other by a microporous polymer membrane, which allows ions to move easily during use, but restricts movement in certain abuse situations, ensuring superior performance and safety. Ultimate Lithium batteries are long-lasting AA batteries, complete with leak resistance and performance in extreme temperatures (-40°F to +140°F or -40°C to +60°C).