Study on the thermal crosslinking preparation of 3D binder and its lithium storage performance for silicon

Silicon (Si) is regarded as a highly promising anode material for lithium-ion batteries (LIBs) due to its exceptionally high theoretical capacity and environmental compatibility. However, the significant volume expansion of Si during cycling often leads to electrode pulverization and electrical contact failure, which significantly limits its practical application. To address this issue, this study employs guar gum (GG), a crosslinking agent and polyacrylic acid (PAA), as the main polymer backbone to construct a novel three-dimensional crosslinked binder, PA2G1, through an in situ thermal crosslinking strategy. The abundant polar functional groups in the binder endow itself with high elasticity and strong adhesion, while the incorporation of GG further enhances lithium-ion transport capability. Consequently, this binder effectively mitigates the volume expansion of Si particles and ensures stable electrical connectivity within the electrode. As a result, the Si@PA2G1 electrode exhibits only a 7.95% thickness variation after 50 cycles at a current density of 0.5 A/g. It retains a high specific capacity of 1 587.6 mAh/g after 300 cycles at 1 A/g, with a capacity retention rate of 62.6%. These findings demonstrate the excellent structural stability and electrochemical cycling performance of the proposed binder system.