Self-assembled vertically aligned organic-inorganic interphase for dendrite-free and reversible zinc metal anodes

Aqueous zinc-ion batteries (AZIBs) are considered promising for safe, low-cost, and sustainable energy storage. However, their practical deployment is critically hindered by dendrite formation and parasitic reactions at the Zn anode-electrolyte interface. To address this challenge, we present a self-assembly strategy to construct vertically aligned organic-inorganic hybrid nanosheet arrays composed of polyethyleneimine-zinc hydroxide sulfate (PEI-ZHS) via a simple coating-immersion method. The protonation of polyethyleneimine in ZnSO4 electrolyte provides localized alkaline conditions for controlled nucleation and growth of ZHS nanosheets at the anode interface. This vertically aligned nanoarchitecture allows for fast Zn2+ transport and even nucleation by providing abundant oriented ion-conductive microchannels and accelerating desolvation. Benefiting from these characteristics, the PEI-ZHS layer effectively mitigates side reactions and dendrite growth. As a result, the modified zinc anodes achieve excellent cycling lifespans of 5200 and 1200 h at 1 mA cm−2/1 mAh cm−2 and 5 mA cm−2/5 mAh cm−2, respectively, in symmetric cells. The Zn||I2 full cell also shows great reversibility, retaining 93.02 % of initial capacity after 4000 cycles at 1 A g−1. This work introduces a thermodynamically guided and scalable interfacial engineering approach that advances the stability and performance of Zn metal anodes in AZIBs.