Low-Cost and Multifunctional Copolymer Binder for Stabilizing High-Capacity Si/C Composite Anodes in Practical Lithium–Ion Batteries

Although high-capacity silicon/carbon (Si/C) composites are widely recognized as the most promising alternative to commercial graphite anodes for next-generation high-energy lithium–ion batteries (LIBs), their practical implementation faces significant challenges due to structural and interfacial instability caused by the substantial volume expansion of Si during charge–discharge cycles. Developing cost-effective binders with superior bonding strength and excellent interfacial compatibility for multicomponent Si/C electrodes is crucial to overcoming these limitations. Herein, we have successfully synthesized a linear copolymer binder (HAMN) incorporating four distinct functional units through a facile one-pot aqueous radical polymerization method. This innovative binder demonstrates multiple advantages, including cost efficiency, exceptional water solubility, superior slurry rheology, remarkable mechanical flexibility, and strong interfacial affinity for Si/C composites. The HAMN-based Si/C electrode exhibits outstanding electrochemical performance, maintaining 91.24% capacity retention after 600 cycles at 0.5C in a half-cell configuration. More importantly, in practical 18,650 cylindrical full-cell tests, the battery demonstrates impressive cycling stability with capacity retention rates of 86.2% after 400 cycles at 0.5C and 78.84% after 700 cycles at 1C. These compelling results underscore the tremendous potential of the HAMN binder in enabling the practical application of high-energy Si/C composite anodes for advanced LIBs.