A water-soluble binder in high-performance silicon-based anodes for lithium-ion batteries based on sodium carboxymethyl cellulose and waterborne polyurethane

Abstract

Silicon (Si) materials have attracted growing attention in lithium-ion batteries (LIBs) due to their remarkably high-theoretical capacity and abundance on Earth. Despite the excellent edges, the widespread application of silicon materials in LIBs has been severely limited by rapid capacity decay and an unstable solid-electrolyte interphase (SEI) due to their substantial volume changes (>300%). Here, we report a novel water-soluble binder (CW-20), comprising sodium carboxymethyl cellulose (CMC-Na) and waterborne polyurethane (WPU). Not only the novel binder can establish a cross-linked three-dimensional (3D) network through hydrogen bonding, which effectively maintains the electrodes’ integrity, but also the binder can form a stable SEI layer, thereby improving the cycling stability and durability. Thus, the Si@CW-20 electrode maintains a specific capacity of 2626.2 mA h g⁻¹ after 100 cycles at 0.1C. After 500 cycles at 0.5C, the Si@CW-20 electrode exhibits excellent stability, maintaining a high specific capacity of 1450.7 mA h g⁻¹ with a capacity decline rate of 0.08% per cycle. Moreover, Si/C@CW-20 exhibits a capacity retention rate of 86.93% after 250 cycles at 1C. The cycling stability and durability of Si and Si/C anodes demonstrate significant potential for this strategy in facilitating the widespread implementation of high-capacity LIBs.