Solid-state amorphization to alleviate severe volume expansion in silicon-based anodes.

The anisotropic lithiation-induced expansion of crystalline silicon leads to uneven volume expansion and extreme stress concentration. This issue will be effectively mitigated by employing an isotropic amorphous structure. Here, an isotropic porous amorphous silicon (aSi) was prepared using a simple and safe method, followed by mechanical mixing with graphite to form an aSi/graphite composite (aSG60). Experimental results demonstrate that the isotropic nature and porous structure of aSi effectively suppress volume change during Li insertion and extraction. The aSG60 delivers a capacity of 1219.0 mAh g at 1 A g, with a 70 % capacity retention after 200 cycles. Notably, the composite exhibits a volume expansion of only 38 % after 50 cycles, significantly lower than the 85 % observed in the micro‑silicon/graphite composite (uSG60) with a similar silicon content. These findings highlight the potential of aSi as a promising material for high-performance silicon-based anodes.