21700 lithium-ion battery cells deliver higher capacity, improved thermal performance, and greater energy density compared to traditional 18650 cells. This format is widely adopted in electric vehicles, high-power e-bikes, drones, and. . A 21700 battery is a high-capacity, rechargeable lithium-ion cell designed for superior energy efficiency and performance. With a standard size of 21mm in diameter and 70mm in length, these batteries were developed as a next-generation improvement over 18650 cells, offering increased power output. . Electric Vehicle 21700 Battery Pack by Application (Passenger car, Commercial vehicle), by Types (Series Battery Pack, Parallel Battery Pack), by North America (United States, Canada, Mexico), by South America (Brazil, Argentina, Rest of South America), by Europe (United Kingdom, Germany, France. . Forge Battery, the commercial lithium-ion battery production subsidiary of Forge Nano, Inc.