Scalable Synthesis of Si Nanosheets as Stable Anodes for Practical Lithium‐Ion Batteries

Abstract Silicon (Si) is regarded as a promising anode material because of its outstanding theoretical capacity, abundant existence, and mature infrastructure, but it suffers from an inherent volume expansion problem. Herein, a facile, scalable, and cost‐effective route to produce Si nanosheets (Si NSs) using a low‐cost silica fume as the start materials is proposed. After coated with carbon, the as‐prepared Si‐NSs@C material delivers ultrahigh capability (2770 mAh g −1 at 0.1 C), high initial Coulombic efficiency (87.9%), and long cycling lifespan (100 cycles at 0.5 C with a capacity decay rate of 0.3% per cycle). Beyond proof of concept, this work demonstrates a Si‐NSs based pouch cell with an impressive capacity retention of 70.9% after 400 cycles, making it more promising for practical application. Revealed by the theoretical simulation, kinetics analysis, and in situ thickness/pressure detection, it is found that the superior performance of Si‐NSs is attributed to the improved diffusivity and reversibility of Li + ions and low expansion.