Polyvinyl alcohol grafted poly (acrylic acid) as water-soluble binder with enhanced adhesion capability and electrochemical performances for Si anode

• Published in: Journal of alloys and compounds 2018-09, Vol.763, p.228-240
• Main Authors: He, Jiarong, Zhang, Lingzhi
• Format: Article
• Language: English
• Subjects: Acrylic acid; Adhesive strength; Adhesives; Anodes; Charge transfer; Chemical synthesis; Diffusion coefficient; Diffusion rate; Electrical resistivity; Electrodes; Free radical polymerization; Free radicals; Graft polymerization; Grafting; Ion diffusion; Lithium; Lithium-ion batteries; Lithium-ion battery; Polymerization; Polyvinyl alcohol; Polyvinyl alcohol-g-poly (acrylic acid); Reaction kinetics; Rechargeable batteries; Si anode; Silicon; Water chemistry; Water-soluble binder
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2018.05.286

Polyvinyl alcohol grafted poly (acrylic acid) (PVA-g-PAA) is synthesized through graft polymerization of acrylic acid (AA) onto PVA backbone via a free radical reaction. PVA-g-PAA is used as a water-soluble binder for silicon (Si) anodes in lithium-ion batteries (LIBs). The enhanced adhesion strength, excellent flexibility and high electrolyte uptake after grafting reaction render PVA-g-PAA a robust binder for Si anodes. Compared to linear PVA, PAA and CMC, optimal Si-PVA-g-10PAA electrode exhibits better cycle stability, higher Coulombic efficiency and more excellent rate capability, possessing a high electrical conductivity, low SEI/charge transfer resistance and fast lithium-ion diffusion coefficient. PVA-g-PAA binder not only maintains the electrode's mechanical and electrical integrity, facilitates a favorable electrochemical kinetics, but also assists in forming a stable SEI layer on Si surface upon long-term cycling. Such a strategy sheds light on the design of novel polymer binders for practical applications of high-capacity active materials with great volume change. [Display omitted] •Polyvinyl alcohol grafted poly (acrylic acid) (PVA-g-PAA) was synthesized through a free radical reaction.•PVA-g-PAA exhibited enhanced adhesion strength, excellent flexibility and high electrolyte uptake.•Si-PVA-g-PAA electrode possessed better cycle stability and higher Coulombic efficiency than PVA, PAA and CMC.•Si-PVA-g-PAA electrode had favorable electrochemical kinetics.