Effect of Film-forming Additive on Electrochemical Performance of Silicon Negative-Electrode in Lithium-Ion Batteries

Effect of film-forming additives, such as vinylene carbonate (VC) and fluoroethylene carbonate (FEC), on electrochemical performance of Si negative-electrode in lithium-ion batteries was investigated using a thick-film prepared by gas-deposition without any binder and conductive additive. In VC-containing electrolyte, Si electrode exhibited better cycle performance with a discharge capacity of 1000 mA h g-1 beyond 750th cycles at a constant charge capacity of 1000 mA h g-1. In FEC-containing electrolyte, in addition, Si electrode showed good rate performance with a discharge capacity of 2000 mA h g-1 even at a high current rate of 10 C. When the current rate was returned to an initial low current rate of 0.4 C, more than 90% of initial discharge capacity was maintained. Film-forming additives relatively suppressed change in the surface morphology of Si thick-film electrode after charge-discharge cycling; disintegration of Si electrode was prevented by the additives.