Favored Amorphous Li_xSi Process with Restrained Volume Change Enabling Long Cycling Quasi-Solid-State SiO_x anode

Silicon-based anodes are becoming promising materials due to their high specific capacity. However, the intrinsically large volume change brought about by the alloying reaction results in the crushing of the active particles and destruction of the electrode structure, which severely limits its practical application. Various structured and modified silica-based anodes exhibit improved cycling stability and the demonstrated ability to mitigate their volume changes through interfacial and binder strategies. However, the issue of large volume changes in silicon-based anodes remains. Herein, we report a gel polymer electrolyte (GPE) prepared through an in situ thermal polymerization process that is suitable for SiO_x anode materials and achieving long-term cycling stability. GPE-based cells essentially mitigate the volume change of SiO_x anodes by guiding the unique lithiation/delithiation mechanism that tends to favor the formation and delithiation of amorphous-Li_xSi (a-Li_xSi) with smaller volume change, thereby mitigating electrode damage and cracking, and achieving the significant improvement in cycling performance. The prepared GPE-SiO_x cells retained 693.80 mAh g^-1 reversible capacity after 450 cycles at 500 mA g^-1. In addition, the prelithiation process was incorporated to mitigate capacity fluctuations and improve the Initial Coulombic Efficiency (ICE), and a reversible capacity of 641.90 mAh g^-1 was retained after 480 cycles.