A copolymer binder with balanced mechanical properties for high-capacity Si/C anodes in lithium−Ion batteries

Silicon-carbon composite material (Si/C) with high specific capacity is regarded as the most promising alternative to graphite and has been commercialized gradually. However, the practical implementation of Si/C anodes remains challenging due to electrode structure disintegration and interfacial instability induced by the substantial volume change of the internal Si-based particles. Herein, we synthesized a hydro-soluble binder with modulated mechanical properties by radical polymerization between acrylic acid (AA) as hard monomer and 2-methoxyethyl acrylate (MEA) as soft monomer simply for Si/C anodes. The as-developed binder exhibits the trade-off mechanical properties between elasticity and rigidness, excellent adhesivity and enhanced lithium-ion diffusion compared with PAA, which is conducive to accommodate the significant volume variation of Si/C during cycling and keeping the integrity of electrode structure. The Si/C anode with P(AA-co-MEA) binder manifests the improved cycling stability (502 mAh g −1 and 82.6% capacity retention rate after 500 cycles at 0.5C) and rate capability compared to that with PAA binder. This work offers valuable insights into the pursuit of high-capacity lithium-ion batteries (LIBs) with enhanced cycling stability.