Interface engineering of electron-ion dual transmission channels for ultra-long lifespan quasi-solid zinc-ion batteries

Abstract

Hydrogel electrolytes have emerged as effective strategies to prolong the lifespan of aqueous zinc ion batteries (AZIBs). However, dendrites and side reactions are still inescapable due to the residual active water and chaotic migration of Zn²⁺. Herein, a super stable Zn anode is realized through the synergistic effect of interfacial electron-ion dual transmission channels (EIDC) and an intermediate sodium alginate (SA) gel. Specifically, the SA gel can adjust the solvation structure of Zn²⁺ and weaken the strong bonding of Zn²⁺ and H₂O molecules. The EIDC polymer layer (PEDOT:PSS) is engineered on the SA hydrogel surfaces, in which PSS chains can offer uniform ion transmission channels via the electrostatic interaction between SO₃^– groups and Zn²⁺. While another PEDOT chains can provide electron conducting channels through the conjugated π-π bonds to accelerate charge exchange. Benefiting from the synergistic effect of EIDC polymer layer and SA gel, the as-prepared SA/EIDC gel electrolyte achieves a high ionic conductivity of 41 mS cm^–1. The Zn//Zn symmetric batteries exhibit a super-long lifespan of 6750 h at 1 mA cm^–2 and 1 mAh cm^–2 (>9 months), and cycling life of MnO₂-Zn full battery surpasses 4000 cycles. This work presents a new perspective on designing hydrogel electrolytes towards ultra-long lifespan ZIBs.