Polyaniline-Induced Prepassivation and Postactivation Strategy to Improve Lithium Ion Storage in Multilayer Silicon-Based Anodes

Silicon nanosheets (Si-NSs) are considered one of the most competitive anode materials for lithium ion batteries. However, the chemical synthesis route of Si-NSs is usually time-consuming and environmentally unfriendly, with uncontrollable surface defects. Besides, the traditional utilization rate of Si-NSs heavily depends on exfoliation yields, which are relatively low due to the strong interlayer van der Waals forces between adjacent Si-NS layers. Therefore, it is a great challenge to develop new strategies for preparing Si-NSs with controlled defects, high utilization rates, and improved performance. This work proposes a polyaniline (PANI)-induced prepassivation and postactivation strategy to regulate defects and improve the utilization rate of Si-NSs without exfoliation via an electrochemical route. When used as an anode material, the activated PANI@Si-NSs delivered an initial specific capacity of 1521.5 mAh g–1, much higher than 444.3 mAh g–1 of Si-NSs. The as-prepared Si-NSs are physically passivated and well-protected from overoxidation by presynthesized PANI during the electrochemical etching of CaSi2. Besides, Si-NSs show optimized and accelerated intralayer and extra-layer lithium ion and electron transport via the induction and activation of PANI. The proposed strategy is demonstrated to be feasible and effective, indicating promising prospects toward high-performance anode materials.