A Stress‐Buffering Hierarchically Porous Silicon/Carbon Composite for High‐Energy Lithium‐Ion Batteries

Abstract The electrochemical performance of Si anodes for lithium‐ion batteries (LIBs) is primarily influenced by the stress–strain and transport dynamics. However, traditional Si/carbon composites often fail to well balance these two factors. Herein, a hierarchically porous silicon/carbon composite (denoted as pSi@void@NMC) with high lithium storage capacity is developed under the guidance of finite element analysis, where porous Si (pSi) and nitrogen‐doped mesoporous carbon (NMC) is used as the yolk and shell, respectively. The internal and external cultivation design endows the pSi@void@NMC composite with fast transfer kinetics, effective stress‐buffering, low volume expansion, and superior mechanical stability. Compared with core–shell pSi@NMC and bare pSi electrodes, the resulting pSi@void@NMC anode demonstrates a high reversible capacity of 1769.8 mAh g −1 after 300 cycles at 0.2 A g −1 and exceptional cycling stability only with 0.016% capacity decay rate per cycle. In situ and ex situ characterization results further confirm its high reversibility of Li + insertion/extraction during electrochemical reactions benefiting from the formation of inorganic LiF‐rich SEI film. Moreover, the developed pSi@void@NMC composite also shows a good potential for full‐cell applications. These findings provide a facile design concept and research strategy for addressing stress fractures and inadequate transport kinetics of Si‐based anode materials for high‐performance LIBs.