Rational design of silicon nano-micro sheet anodes for high performance all-solid-state batteries

초록

Si anodes have emerged as a promising focus of intensive research in all-solid-state batteries, driven by the pursuit of high energy density and safety. However, interfacial contact resistance (i.e. long pathway of Li-ion and mechanical failure) originating from the massive volume variation of Si within the electrode hinders overall battery performance. Here, we propose a design of Si nano-micro sheet with micro-length scale and nanothickness scale using a simple method via chemical vapor deposition (CVD) and mechanical milling. The nanoscale thickness of the Si nano-micro sheet alleviates mechanical stress from volume expansion, preventing structural degradation of the electrode and ensuring long-term stability, while its microscale length reduces tortuosity in ion transport pathways, enabling more direct and efficient lithium-ion movement. As a result, Si nano-micro sheet electrodes demonstrate high initial capacity (2386 mAh g- 1) and excellent cycle stability (80% retention after 100 cycles). This stability is greatly superior to that of the nano and micro-sized Si with less than 5% capacity retention after 50 cycles. Full-cell tests with NCM811 show a high discharge capacity (192 mAh g- 1), a capacity retention of 84.4% after 250 cycles, and superior rate performance (3C rate, retention 71.1%).

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