Do Zinc Dendrites Exist in Neutral Zinc Batteries: A Developed Electrohealing Strategy to In Situ Rescue In‐Service Batteries

TLDR

The dendritic issue in aqueous zinc‑ion batteries using neutral/mild electrolytes remains controversial, with some researchers asserting severe dendrite formation while others report excellent cycling stability without protection. This study investigates charge/discharge‑condition‑dependent Zn dendrite formation and proposes an electrohealing strategy to rescue in‑service batteries, aiming to extend their lifetime. The authors develop a first‑in‑class electrohealing methodology that eliminates pre‑formed dendrites, extending lifespans by 410 % at 7.5 mA cm⁻² and 516 % at 10 mA cm⁻². Higher current densities and larger loading masses accelerate Zn dendrite growth, reducing lifespans from 120 h to 1.2 h and increasing voltage hysteresis from 134 mV to 380 mV, while morphological analysis shows that passivation of sharp‑tipped dendrites eventually yields a smooth surface, confirming dendrite formation as the primary degradation driver.

Abstract

Abstract The dendritic issue in aqueous zinc‐ion batteries (ZBs) using neutral/mild electrolytes has remained an intensive controversy for a long time: some researchers assert that dendrites severely exist while others claim great cycling stability without any protection. This issue is clarified by investigating charge/discharge‐condition‐dependent formation of Zn dendrites. Lifespan degradation (120 to 1.2 h) and voltage hysteresis deterioration (134 to 380 mV) are observed with increased current densities due to the formation of Zn dendrites (edge size: 0.69–4.37 µm). In addition, the capacity is also found to remarkably affect the appearance of the dendrites as well. Therefore, at small current densities or loading mass, Zn dendrites might not be an issue, while the large conditions may rapidly ruin batteries. Based on this discovery, a first‐in‐class electrohealing methodology is developed to eliminate already‐formed dendrites, generating extremely prolonged lifespans by 410% at 7.5 mA cm –2 and 516% at 10 mA cm –2 . Morphological analysis reveals that vertically aligned Zn dendrites with sharp tips gradually become passivated and finally generate a smooth surface. This developed electrohealing strategy may promote research on metal dendrites in various batteries evolving from passive prevention to active elimination, rescuing in‐service batteries in situ to achieve elongated lifetime.