Ligand-Anchoring Effect of a PAA/PVDF-Cross-Linked Binder Promoting Interfacial Stability and Electrochemical Performance of a Cathode Material

Abstract

Lithium-ion batteries (LIB) are extensively utilized across industries for their rechargeable nature, but capacity degradation during charge/discharge cycling poses the risk of battery failure. The LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) cathode material encounters challenges in maintaining high capacity and cycling performance due to cation mixing, ion migration, and electrolyte chemical reactions. While the conventional inorganic coating layer offers some physical protection, it is susceptible to detachment. We introduce organic poly(acrylic acid) (PAA) and adhesive polyvinylidene fluoride (PVDF) cross-linked to form a composite cross-linked adhesive. The combination of PAA and PVDF improves the viscosity of the adhesive and enhances the bonding strength of the cathode material. The C=O group in PAA forms coordination bonds with transition metals, creating a coordinated anchoring effect that enhances the stability of the cathode structure. The reversible ion exchange between H⁺ of −COOH and Li⁺ promotes lithium-ion transport at the electrode interface, enhancing electrochemical performance. After 200 cycles, the capacity retention under 1C conditions reached 90.20%.