Improvement in Cycle Performance and Clarification of Deterioration Mechanism of Lithium-Ion Full Cells Using SiO Anodes

We have succeeded in obtaining good cycle performance by control cutoff voltage suitable for an ambient temperature in Li-ion full cells with carbon-coated SiO (C-SiO) anode. The optimized cells showed that the retention ratio of discharge capacity was above 90% after 500 cycles at 20°C. We also found that the origins of capacity fading were very different at 20° C and 60°C. In the former, C-SiO electrode caused the phase separation of Li concentration during charge-discharge due to the slow diffusion rate of the Li ion, and the thick heterogeneous phase was formed on C-SiO particles. In the latter, the decomposition of electrolyte became the main deterioration factor. The improved performance of full cell and the elucidation of the deterioration mechanism can accelerate the practical application of next generation high capacity Li-ion cells.