Improving Cycle Stability of Silicon Anodes Via Control of Charge/Discharge Protocols

It is well-known that silicon anodes experience large volume expansion (> 300%) when fully lithiated. By introducing engineered voids into a Si/C core-shell structure to form Si@void@C structure, volume expansion of Si@void@C particles can be minimized, thereby improving the cycle stability of the Si@void@C electrode. This study reveals that by adjusting charge/discharge protocols the cycle stability of the Si@void@C electrode can be further enhanced. It is shown that both lower and upper cutoff voltages during charge and discharge, respectively, have strong influence on the cycle stability of the Si@void@C electrode. These phenomena are interpreted based on volume expansion and shrinkage of the Si@void@C electrode as a function of lower and upper cutoff voltages. The post-mortem analysis of the thickness change in the cycled electrode cross-section offers corroborating evidence to support the enhancement of the cycle stability of Si@void@C electrodes via control of charge/discharge protocols to minimize the volume change of Si@void@C electrodes with a small sacrifice in their specific capacity.