Chain-length engineered interfacial architecture enables dendrite-free aqueous zinc-ion batteries

Abstract

The growth of zinc dendrites in aqueous zinc-ion batteries (AZIBs) significantly compromises the cycling stability and operational lifespan, especially under prolonged charge–discharge cycles at high load, where dendrite formation poses serious safety risks. In this work, we propose a “critical network equilibrium” mechanism enabled by molecular weight-optimized dextran (DEX). Specifically, DEX with a molecular weight of 70 000 (D7) reaches a stabilization threshold in the ZnSO₄ electrolyte, where it self-assembles into an adaptive interfacial architecture. This dynamic network serves as an intelligent protective layer, effectively shielding the Zn anode from H⁺ corrosion, optimizing the solvation shell to reinforce interfacial stability, and ensuring uniform Zn²⁺ deposition through adaptive restructuring. Moreover, the D7-mediated interface preferentially directs Zn²⁺ deposition onto the Zn(002) plane, while inhibiting disordered growth on the Zn(101) plane. Experimental results indicate that the Zn//Zn cell modified with D7 exhibits an ultra-stable lifespan of up to 4800 h at 1 mA cm⁻²/1 mA h cm⁻², while the Zn//MnO₂ full-cell retains 83% of its capacity after 3000 cycles. We believe that our innovative strategy for optimizing electrolytes will offer new insights for prolonging the operational lifespan of AZIBs.