Double-wrapping design of gradient energy-dissipative binder for enhanced performances of SiC anodes

Silicon carbon (SiC) has emerged as a promising alternative to conventional graphite anodes for high-energy lithium-ion batteries (LIBs) by virtue of their higher specific capacity, high safety and abundant resources. However, the practical implementation of SiC1000 (SiC with a specific capacity of 1000mAh/g) electrodes remains challenging due to the disintegration and interfacial instability of the internal Si particles. Herein, a novel double-layer-binder designing strategy was proposed to address these issues. The inner "hard" layer comprises lithiated polyacrylic acid (LiPAA) filled with single-walled carbon nanotubes (SWCNTs), providing high modulus and dual electronic and ionic conductivity. The outer "soft" layer, inspired by a fishnet structure, consists of a low-modulus and self-healing three-dimensional polyurethane (3D-s-PU) network. This outer 3D-s-PU layer serves as a buffer, mitigating residual stress and preventing structural damage to the rigid LiPAA layer. This gradient binder design, transitioning from hard to soft, demonstrates excellent cycle stability and rate performance of SiC anodes, presenting a new strategy for polymer binder design and advancing high-performance LIBs development.