Facile Synthesis of 2D SiOx‐3D Si Hybrid Anode Materials by Ca Modification Effect for Enhanced Lithium Storage Performance

Abstract

AbstractAl‐Si dealloying method is widely used to prepare Si anode for alleviating the issues caused by a drastic volume change of Si‐based anode. However, this method suffers from the problems of low Si powder yield (<20 wt.% Si) and complicated cooling equipment due to the hindrance of large‐size primary Si particles. Here, a new modification strategy to convert primary Si to 2D SiOx nanosheets by introducing a Ca modifier into Al‐Si alloy melt is presented. The thermodynamics calculation shows that the primary Si is preferentially converted to CaAl2Si2 intermetallic compound in Al‐Si‐Ca alloy system. After the dealloying process, the CaAl2Si2 is further converted to 2D SiOx nanosheets, and eutectic Si is converted to 3D Si, thus obtaining the 2D SiOx‐3D Si hybrid Si‐based materials (HSiBM). Benefiting from the modification effect, the HSiBM anode shows a significantly improved electrochemical performance, which delivers a capacity retention of over 90% after 100 cycles and keeps 98.94% capacity after the rate test. This work exhibits an innovative approach to produce stable Si‐based anode through Al‐Si dealloying method with a high Si yield and without complicated rapid cooling techniques, which has a certain significance for the scalable production of Si‐based anodes.