Simulated low-earth-orbit cycle-life testing of commercial laminated lithium-ion cells in a vacuum

We tested the life cycle of commercial laminated lithium-ion cells with both liquid (LE cells) and polymer (PE cells) electrolytes by simulating a satellite's low earth orbit (LEO) operation under various environmental conditions to develop a power storage system for microsatellites. We completed 4000 cycles, corresponding to about 8 months of LEO satellite operation. The LE cell initially exhibited better performance than the PE cell in a normal atmosphere. However, the LE cell began to expand in a vacuum (about 20 Pa), accompanied by capacity loss and voltage decline at the end of the discharge. In contrast, the PE cell exhibited excellent endurance in a vacuum and maintained high capacity and voltage at the end of the discharge. The reliable cycling of the PE cell in a vacuum was attributed to the adhesive properties of the gel electrolyte that held the laminate film package and active electrode materials together. A comparison of cell performance at various ambient temperatures demonstrated that the proper ambient temperature range for a PE cell is from 10 to 30 °C.