Partially lithiated ternary graft copolymer with enhanced elasticity as aqueous binder for Si anode

Partially lithiated ternary graft copolymers were synthesized through free radical graft polymerization of acrylic acid (AA), lithium acrylate (LiAA) and hydroxyethyl acrylate (HEA) onto polyvinyl alcohol (PVA). With optimized feeding molar ratio of AA/LiAA/HEA (2:1:2), the ternary graft copolymer with partial lithiation shows the best flexibility, elasticity and adhesion strength comparing to PVA-g-PAA and PVA-g-P(AA-HEA) when used as aqueous binder for Si anode. The Si anode using PVA-g-P(AA-LiAA-HEA) with the optimized molar ratio of AA-LiAA-HEA exhibits better cycling stability and rate performance, delivering a capacity of 2265 mAh g −1 with a capacity retention of 82.4% after 200 cycles at 1A g −1 . Even at a high current of 10 A g −1 , the Si electrode still obtained a high capacity of 1300 mAh g −1 .