Hierarchical Porous Structured Si/C Anode Material for Lithium‐Ion Batteries by Dual Encapsulating Layers for Enhanced Lithium‐Ion and Electron Transports Rates

Abstract Silicon (Si) is a promising anode material for next‐generation lithium‐ion batteries (LIBs) due to its high specific capacity and abundance. However, challenges such as significant volume expansion during cycling and poor electrical conductivity hinder its large‐scale application. In this study, the multifunction of sodium polyacrylate (PAAS) utilized to develop a hierarchical porous silicon–carbon anode (Si/SiO x @C) through a simple and efficient method. The hierarchical porous structure successively consists of nano‐silicon cores, SiO x encapsulating layers, surrounding space, and phenolic resin‐derived carbon shells with carbon chains connecting the SiO x layers and carbon shells in the space. The SiO x nanolayers promote Li⁺ transport, while excess PAAS, removed by washing, generates space for volume expansion, improving cycling performance. Residual carbon chains of PAAS and carbon shells form a conducting carbon network, enhancing electron transport and rate performance. As an anode for LIBs, the composite delivers a high reversible capacity of 685.3 mAh g⁻¹ after 1000 cycles at 1 C with a capacity retention rate of 54.7%. Full cells with the Si/SiO x @C anode and LiNi 0.8 Co 0.1 Mn 0.1 O 2 cathode exhibit an excellent capacity retention rate of 96.8% after 200 cycles at 1 C. This work provides a novel approach for the rational design and engineering of advanced LIBs.