Cross-linking chemistry enables robust conductive polymeric network for high-performance silicon microparticle anodes in lithium-ion batteries

Low-cost silicon microparticles (SiMPs) are more promising anode materials towards practical implementation due to their higher volumetric energy density and less side reactions than Si nanoparticles. However, SiMPs always suffer from extremely dramatic mechanical fracture caused by volume expansion during cycling, and hence a far inferior cycle stability to Si nanoparticles. Herein, a highly cross-linked 3D conductive polymeric network, consisting of amino-functionalized long single-wall carbon nanotubes (SCNT–NH2–L) and poly(acrylic acid)/sodium carboxymethyl cellulose, has been prepared via esterification and amidation reactions during electrode preparation process. Benefiting from limiting effect and stress-dissipation provided by the unique network, it can keep complete electrode structure and ensure good electrical connection between broken Si particles during cycling. Meanwhile, the newly formed ester groups in the network can greatly enhance the reaction kinetics of silicon for superior Li+ storage. As a result, the as-prepared SiMPs anode delivers an ultrahigh initial discharge capacity of 3861.4 mAh g−1 at 100 mA g−1 and a superior cycle stability with high capacity retention of 74.3% from 20th to 200th cycle at 2000 mA g−1. Our work provides a novel but simple stress-dissipation strategy to enable the stable operation of silicon microparticle in lithium-ion batteries.