Mechanism Study on Garnet-type Li_6.4La₃Zr_1.4Ta_0.6O₁₂ Regulating the Solid Electrolyte Interphases of Si/C Anodes

The large volume change of silicon anode leads to rupture of the solid electrolyte interface (SEI) and the pulverization of Si electrode during charge-discharge process, which results in uncontrolled capacity loss. In this work, a strategy to regulate the SEI composition of Si/C anodes utilizing Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 (LLZTO) solid electrolyte was proposed. LLZTO layer is uniformly coated on the surface of polypropylene (PP) separator, which not only improves wettability of the electrolyte to the separator, thereby homogenizing the lithium-ion flux, but also increases the proportion of inorganic components in SEI and enhances the interfacial stability of Si/C anodes. As a result, Li batteries using the LLZTO coated PP separator exhibit better cycling stability and rate capability. Li-Si/C half cell exhibits a reversible capacity of 876 mAhg -1 with 81% capacity retention for more than 200 cycles at 0.3C (1C= 1.5 Ag -1 ), and Si/C-LiFePO 4 (LFP) full cell delivers a capacity of 125 mAhg -1 with 91.8% capacity retention after 100 cycles at 0.3C (1C=170 mAg -1 ). This work reveals the mechanism of LLZTO solid electrolytes in regulating the SEI of Si/C anodes and sparks new ideas for developing high-performance silicon-based lithium batteries.