Balancing pore development and mechanical strength for high-performance silicon-porous carbon anodes in lithium-ion batteries

Silicon-porous carbon composites (Si@PC) are considered promising candidates for next-generation anodes in lithium-ion batteries (LIBs). However, the intrinsic relationship between the pore structure of Si@PC and its electrochemical performance remains largely unexplored. Additionally, fabricating high-performance Si@PC typically involves complex processes, significant risks, and extensive solvent use. This study proposes a simple, safe, solvent-free dry method to prepare Si@PC, using Si nanoparticles as the Si source, (NH₄)₂SO₄ as the pore-forming agent, and pitch as the porous carbon precursor, through a one-step carbonization process. Through the results of mechanical performance, the relationship between the degree of pore development and electrochemical performance of Si@PC is investigated. We find that pore development is not positively correlated with electrochemical stability. Moderately developed pores effectively alleviate Si's volume expansion, maintaining structural integrity and electrochemical stability of the electrode. However, excessively developed pores significantly reduce mechanical strength, leading to electrode pulverization and rapid performance decay during cycling, even underperforming non-porous electrodes. The optimized Si@PC anode retains a high specific capacity of 847 mAh g^-1 after 500 cycles at 1.0 C, with a retention of 74.4%. This study offers guidance on optimizing Si@PC electrode structures by balancing pore development and mechanical strength.