Application of Li2S to compensate for loss of active lithium in a Si-C anode

Mixed silicon and carbon (Si-C) materials with high capacity are ideal candidates for the substitution of graphite or other carbon anodes in lithium-ion batteries. However, the low coulombic efficiency of the Si-C anode in the first cycle due to the formation of a solid electrolyte interphase and the consumption of active lithium have hindered its commercial applications. Here, we report using Li2S as a prelithiation material to compensate for the loss of active lithium in the first cycle and, consequently, to enhance the specific energy of lithium-ion batteries. The Si-C anode has an initial discharge specific capacity of similar to 738 mA h g(-1) and a charge specific capacity of similar to 638 mA h g(-1). The prelithiationmaterial with a core-shell structure is prepared by mixing Li2S, Ketjenblack (KB) and poly(vinylpyrrolidone) (PVP) in anhydrous ethanol, which shows a high irreversible capacity of similar to 1084 mA h g(-1). The effect of the compensation of lost active lithium is verified via a LiFePO4 (Li2S)/Si-C full cell, which exhibits not only a high specific capacity but also a stable cycling performance. The specific energy of the LiFePO4 (Li2S)/Si-C full cell shows a remarkable increase compared to the LiFePO4/Si-C full cell, exhibiting similar to 13.4%, similar to 26.7%, similar to 65.0% and similar to 110.2% more specific energy after the 1(st), 10(th), 100(th) and 200(th) cycle, respectively.