SiO x–graphite as negative for high energy Li-ion batteries

Abstract

Negative electrodes containing SiO x were investigated as alternative negative electrodes to carbon for Li-ion batteries. The results obtained on the effect of binders and carbon additives on the electrochemical performance (i.e., reversible capacity, coulombic efficiency, charge–discharge rate capability) of the SiO x –graphite electrode and SiO x electrode are presented. SEM analysis that utilizes facilities for in situ and ex situ studies were applied to better understand the performance and cycle life of the SiO x -based electrodes. The SEM analysis clearly showed that the SiO x particles expand and contract during charge–discharge cycling, and that some of the particles undergo mechanical degradation during this process. The SiO x –graphite electrode with polyimide binder exhibited a stable capacity of 600 mAh g −1 during high-rate charge–discharge from C/4 to 1 C. These results suggest that the use of a flexible binder like polyimide and reasonably small SiO x particles (nano-particles) facilitates improved cycle life and higher rate capability.