Ultra-Reversible Electrochemical Behavior of Silicon with Dense Penetrating Stacking Faults via Crystal Engineering

Silicon represents a promising anode material for next-generation lithium-ion batteries (LIBs), owing to exceptionally high theoretical capacity and natural abundance. Nanosizing can significantly alleviate the intractable problems (bulk effects) of Si anodes with great simplicity and effectiveness. However, a typical problem of low initial coulombic efficiency (ICE) of Si is thus severely amplified by the enlarged specific surface and enhanced reactivity. To break through this bottleneck, this have ingeniously built a simple and precise crystal engineering to create a uniform and dense stacking faults (SFs) with the enlarged channels running through the interior of Si grains. It is achieved by controlling the thermal motion state of Si atoms via annealing and liquid-nitrogen freezing without the introduction of other substances. The reshaped nano-silicon reaches an ICE of up to 90.3% at 80 wt% in the electrode (initial specific capacity of 2700.8 mAh g⁻¹), refreshing the electrochemical reversible performance of bare nano-silicon, which can be accounted for by extremely low Li loss and robust adaptability within confined LIBs. Further detailed Li-trapped investigations from microscopic nanostructure to macroscopic electrode confirm that SFs constructed in grains help to realize such ultra-reversible electrochemical behavior, which properly guides Li shuttling through preferential exchange of charge and energy.