Manipulating crystallographic growth orientation by cation-enhanced gel-polymer electrolytes toward reversible low-temperature zinc-ion batteries

Abstract

Aqueous zinc-ion batteries (AZIBs) have garnered significant research interest as promising next-generation energy storage technologies owing to their affordability and high level of safety. However, their restricted ionic conductivity at subzero temperatures, along with dendrite formation and subsequent side reactions, unavoidably hinder the implementation of grid-scale applications. In this study, a novel bimetallic cation-enhanced gel polymer electrolyte (Ni/Zn-GPE) was engineered to address these issues. The Ni/Zn-GPE effectively disrupted the hydrogen-bonding network of water, resulting in a significant reduction in the freezing point of the electrolyte. Consequently, the designed electrolyte demonstrates an impressive ionic conductivity of 28.70 mS cm⁻¹ at −20°C. In addition, Ni²⁺ creates an electrostatic shielding interphase on the Zn surface, which confines the sequential Zn²⁺ nucleation and deposition to the Zn (002) crystal plane. Moreover, the intrinsically high activation energy of the Zn (002) crystal plane generated a dense and dendrite-free plating/stripping morphology and resisted side reactions. Consequently, symmetrical batteries can achieve over 2700 hours of reversible cycling at 5 mA cm⁻², while the Zn || V₂O₅ battery retains 85.3% capacity after 1000 cycles at −20°C. This study provides novel insights for the development and design of reversible low-temperature zinc-ion batteries.