A novel functional polymeric binder for silicon anodes in lithium-ion batteries

Si is known to have an extremely high theoretical capacity and regarded as an optimal anode candidate for the next-generation LIBs. But unfortunately, the dramatic volume change during repeated charge/discharge processes leads to its repaid capacity fading. Here we report a novel composite functional binder, which is constructed by cross-linking PEDOT: PSS and CMC by C-O-S bonds. The obtained polymeric binder features superb electrical conductivity, strong interactions (hydrogen bonds) between binder and Si surface and robust mechanical strength through cross-linking, thus the structural and electrochemical properties of the Si anode was dramatically improved, including the smooth electrode surface and the low electrode expansion rate after repeated cycles, as well as the high initial capacity (3892 mAh∙g^-1) and coulomb efficiency (81%), the excellent capacity retention (1106.4 mAh∙g^-1 after 100 cycles) and rate capability (600 mAh∙g^-1 at 5 A∙g^-1).