High-Toughness and Hierarchical Stress-Dissipating Binder Based on Physicochemical Dual-Cross-Linking for High-Performance Silicon Anodes

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Silicon (Si) is a promising anode material for next-generation lithium-ion batteries (LIBs), but the huge volume change of Si particles causes anode fracture and delamination from the current collector, thereby stifling practical implementation. Herein, a high-toughness and hierarchical stress-dissipating binder for Si anodes is prepared by the covalent and hydrogen bonding of poly(acrylic acid) (PAA) and a cross-linked polyurethane (CPU). The physicochemical dual-cross-linked CPU-PAA binder with high toughness, large tensile strength, and hierarchical stress dissipation improves the structural integrity of Si anodes and minimizes thickness swelling. Finite element analysis confirms that the CPU-PAA binder reduces and uniformizes the stress distribution within the Si anodes during cycling. As a result, the Si/CPU-PAA anode shows a high capacity retention of 82.3% after 150 cycles at a high current density of 5 A g⁻¹. Moreover, the Si/CPU-PAA//LiNi0.5Co0.2Mn0.3O₂ full cell delivers stable cycling performance, highlighting the great potential of the CPU-PAA binder in high-energy-density LIBs. This work provides insights into the design of high-strength, large-toughness, and efficient stress-dissipating binders for high-performance Si anodes.