One Stone, Three Birds: Self-Repaired OSA/AM Water-Based Binder in Situ Anchored Electrode Interface Remodeling CEI Components with Superior Sodium Adsorption Property

Abstract

Herein, this work proposes an environmentally benign multifunctional water-based binder with superior self-repairing properties and beneficial effects for electrode materials. Different from the single-chain polyvinylidene fluoride (PVDF) binder, we employ the interlinked long-chain rigid template of oxidized sodium alginate (OSA) as the basis material, among which acrylamide (AM) acts as a cross-linker to form a self-healing adhesive OSA/AM with an interpenetrating network. Comprehensive experimental tests and density functional theory calculations synergistically demonstrate that the OSA/AM binder possesses superior mechanical stability and higher binding energy than general electrode materials. Moreover, benefiting from the covalency and electrostatic interactions from the OSA/AM system, this special binder could in situ anchor on the interfacial surface of the cathode, restraining the dissolution of electrochemically active substances and electrolytes. Significantly, the OSA/AM adhesive is rich in functional groups, resulting in a tight combination with active oxygen in the electrolyte and inducing inorganic-rich components in the cathode electrolyte interphase membrane. Furthermore, experiments and theoretical simulations indicate that OSA/AM has much better sodium adsorption properties, suggesting accelerated ionic migration capability for the whole battery. When combined with Na3V2(PO4)3 (NVP), it retains 90.3% capacity after 500 cycles at 1C. After 12,500 cycles at 70C, the average per-cycle capacity loss is merely 0.0023%. A high reversible capacity of 73.3 mAh·g–1 is also maintained at 360C. The excellent universality of the OSA/AM binder is also verified in different cathode systems (Na4Fe3(PO4)P2O7/Na3V2(PO4)2F3/NaV(P2O7)/Na3V(PO3)3N).