Development of the lithium ion battery system for space: report on the result of development of the lithium ion battery system for space

As the battery for space, Ni-Cd and Ni-H/sub 2/ is used. Recently, lithium ion battery, which has high energy density high discharge voltage and high efficiency of charge/discharge, is being developed for electric vehicle. We have developed the battery system for GEO to reduce the weight and cost. As the result of the development test and qualification test, we have taken the following data: to meet the life requirement of GEO satellite with protection circuit; GEO: 15 years 3200 cycles; to perform qualification test for GEO satellite; to improve energy to weight at battery system level (from 40 w/g to 110 w/g). Since Mitsubishi Electric Corporation has developed the lithium ion battery system (LIB) which applied large capacity lithium-ion cell (Li-ion cell) for GEO satellite, we describe summary of its system and result of development test. As compared with nickel-hydrogen (Ni-H/sub 2/) or nickel-cadmium (Ni-Cd) cells which has been used for satellite, Li-ion cell has more than two times much energy density and three times much discharge voltage. Therefore Li-ion cell can be realized weight saving, small volume and low cost. Also its cycle life performance is enough to expect long life according to life test at the ground. This LIB consists of battery module (BM) and battery charge control (BBC). BM connects 24 cells, that are nominal capacity 100 AH cells, in series. This LIB and its system are determined to be on GEO satellite.