Lawrence Berkeley National Laboratory

Silicon suboxide (SiOx) is one of the promising anode materials for the next-generation lithium-ion batteries. However, SiOx has a severe capacity fading problem during cycling. It is thus desired to investigate the detailed fading mechanisms of SiOx anode materials. In this study, limited capacity cycling was employed to examine the electrochemical behaviors of the SiOx anode, and the lithiation/delithiation cycling was limited within a range of 10% theoretical capacity. This strategy minimizes the volume variation of SiOx materials upon charging/discharging, which helps to reveal their decay factors other than volume fluctuation. It is demonstrated that the instability of the SiOx surface during cycling was likely a parallel factor of active material fading, which seems to cause unfavored electrode interface rearrangements with lowered electric conductivity.