LAUSR

Lithium-ion batteries (LIBs) are major energy storage in portable electronic devices, hybrid/plug-in hybrid vehicles (HV/PHV), and electric vehicles (EV). Especially, with regard to the use in HV/PHV and EV, LIBs are expected to have much higher gravimetric and volumetric energy densities than current LIBs. Silicon is an attractive material as an alternative anode of LIB because its theoretical capacity is more than tenfold greater than the current carbon (graphite) anode, so LIBs containing Si anode have been the subject of much recent investigation [1]. However, Si has some problems to be used as LIB anode. One of the problems is “hysteresis”; cell voltage (Open Circuit Voltage; OCV) profiles at the discharging state decrease compared with the charging state. Although hysteresis leads to declining the performance of LIB, the reason why it occurs has been poorly understood. Recently, a study was conducted on macroscopic analysis of voltage hysteresis and it was reported that the mechanical stress of Si anode might have relation to hysteresis [2]. However, no study has been reported on the microscopic analysis to investigate hysteresis of Si anode LIB. Therefore, in this work, we aimed to study the microscopic mechanism of hysteresis.