Extremely High Yield Conversion from Low‐Cost Sand to High‐Capacity Si Electrodes for Li‐Ion Batteries

Although magnesiothermic reduction has attracted immense attention as a facile route for the fabrication of mass‐scale Si nanostructures for high‐capacity lithium‐ion battery applications, its low conversion yield (<50%) and the discovery of a sustainable and low‐cost precursor remain challenging. Here, an unprecedentedly high final conversion yield (>98%) of magnesiothermic reduction based on control of reaction pressure is reported. The successful use of sand as a nearly infinite and extremely low‐cost source for the high‐yield fabrication of nanostructured Si electrodes for Li‐ion batteries is demonstrated. On the basis of a step‐by‐step analysis of the material's structural, morphological, and compositional changes, a two‐step conversion reaction mechanism is proposed that can clearly explain the phase behavior and the high conversion yield. The excellent charge–discharge performance…