Enhanced adhesion and electrochemical performance of Si anodes with gum arabic grafted poly(acrylic acid) as a water-soluble binder

Gum arabic grafted poly(acrylic acid) (GA-g-PAA) is synthesized as a mechanically robust water-soluble binder for silicon (Si) anodes in lithium-ion batteries by graft polymerization of acrylic acid onto GA backbone via a free radical reaction. H-1 NMR and Fourier transform infrared spectroscopies and thermogravimetric analysis are systematically conducted to confirm the grafting polymerization process. GA-g-PAA with different grafting length of PAA shows enhanced adhesion strength and excellent flexibility after grafting. Optimal Si-GA-g-8PAA electrode displays better cyclic stability, higher Coulombic efficiency and superior rate properties compared with a Si electrode with linear PAA binder. The Si-GA-g-8PAA electrode exhibits a high electrical conductivity, low interfacial/charge transfer resistance and high lithium-ion diffusion coefficient. GA-g-8PAA binder with grafted structure not only can maintain the mechanical and electrical integrity of the electrode, facilitating favorable electrochemical kinetics, but also assists in preserving a stable solid electrolyte interphase on Si surface upon long-term cycling. Such a facile strategy for designing a novel grafted binder shows potential for practical application on high-capacity anode materials with large volume change. (c) 2021 Society of Industrial Chemistry