Development of Large Scale Lithium-Ion Cells for Spacecraft Applications

Abstract

Rechargeable cells, e.g. alkaline (Ni–Cd, Ni–MH, and so on) and Li–ion cells have important roles in spacecrafts. They store electric power from other power generation devices such as solar cells and supply it to all the components, especially during eclipses. Lithium–ion cells have many advantages such as high energy density, low self–discharge rate and no memory effect compared to conventional alkaline cells. The cycle life performance of large–scale lithium–ion cells has been evaluated by the Japan Aerospace Exploration Agency (JAXA) since the 1990s and the requirements for their use with spacecraft have been satisfied. Accordingly, large scale lithium–ion cells manufactured by GS Yuasa Technology Ltd. (GYT) were categorized by JAXA as key components and successfully approved for use in spacecraft. Recently, we have been studying the applicability of improved lithium–ion cells in spacecraft. We have accumulated a many kinds of data and are now ready for certification of lithium ion cell qualification for use in space.