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.