Multiple Hydrogen Bonding Induced by Semi-Interpenetrating Polymer Network Binder to Enhance the Electrochemical Performance of Sodium-Ion Batteries Electrodes

Abstract

Molybdenum disulfide (MoS2) serves as an ideal anode for sodium-ion batteries (SIBs), boasting a high theoretical specific capacity and large interlayer spacing. However, the substantial volume change and low conductivity present significant challenges in maintaining the electrochemical stability of the electrode. Herein, a novel semi-interpenetrating polymer network (SIPN) binder (sodium alginate-g-poly (acrylamide-co-2-hydroxyethyl acrylate)-boric acid, SA-PAHB) is synthesized by free radical copolymerization grafting and the multiple hydrogen bonding crosslinking (bond energies spanning from −33.89 to −45.49 kcal mol−1by theoretical calculations), which can effectively mitigate stress in Na+ deintercalation in MoS2 anodes under the synergy of the unique structure of the SIPN, maintaining electrode stability. Simultaneously, the variable hydrogen bonding crosslinking and abundant -NH2 groups greatly facilitate Na+ diffusion and enhance kinetic performance. Leveraging the advantages of SA-PAHB, the electrochemical performance is significantly enhanced compared to traditional SA and grafted SA-based binders. Specifically, MoS2 anodes using SA-PAHB binder exhibit an initial discharge specific capacity of 772.1 mAh g−1 at 0.1 A g-1 and retain 511.2 mAh g-1 at 0.5 A g-1 after 200 cycles, with no capacity loss. Additionally, an outstanding rate performance is achieved, delivering 378.5 mAh g−1 at 10 A g−1. For sodium-ion coin full-cells, a discharge specific capacity of 125.2 mAh g−1 is maintained at 0.5 A g−1 after 50 cycles.

Keywords: multiple hydrogen bonding, semi-interpenetrating polymer network binder, Sodium alginate, MoS2 anode, Sodium-ion batteries