A123

A123 Systems, LLC, commonly known as A123, is a battery technology company that developed lithium-ion cells and energy storage systems. Founded in 2001 and based in Watertown, Massachusetts, A123 specialized in lithium iron phosphate (LiFePO4) chemistry, emphasizing high power output and thermal stability for automotive and grid storage applications. The company supplied cells to automakers and energy projects and played a prominent role in early electric-vehicle development.

Technology and products: A123 produced cylindrical and prismatic LiFePO4 cells and complete battery packs for electric vehicles and stationary storage. Its high-power cells were used in various demonstration fleets and early electric vehicles, including Fisker Automotive’s Karma. The company pursued U.S. manufacturing scale-up, building and expanding plants with government support.

History: A123 received backing from the U.S. Department of Energy to support domestic manufacturing. Facing financial difficulties, the company filed for Chapter 11 bankruptcy protection in 2012. Wanxiang Group, a Chinese automotive components company, acquired A123 in 2012, and its assets and technology were integrated into Wanxiang’s energy-storage operations. The A123 brand and some of its technology continued to be referenced in the combined corporate structure.

Impact and legacy: A123 contributed to the early adoption of lithium-ion chemistry for high‑power applications, particularly in the U.S. automotive sector. The company's technology and manufacturing projects influenced subsequent energy storage developments and the broader shift toward domestic and international partnerships in electric vehicle supply chains.