A eutectic electrolyte for an ultralong-lived Zn//V2O5 cell: an in situ generated gradient solid-electrolyte interphase

Abstract

Turbulent interfacial evolution at the Zn anode/electrolyte, leading to rampant dendrites and parasitic reactions, is responsible for low Coulombic efficiency (CE) and premature failure in Zn metal batteries. To address this issue, an integrated eutectic electrolyte was introduced to construct a gradient organic/inorganic hybrid SEI (GHS) layer on the Zn anode through in situ chemical reconstruction. The entanglement between the thermodynamic equilibrium of the species and the evolution of the GHS layer in a coordinated state was revealed. The GHS layer with a gradient structure and composition alleviates corrosion and passivation on the Zn anode, as well as the hydrogen evolution reaction. Additionally, the diffusion behavior of Zn²⁺ at the interface is optimized, allowing epitaxial deposition of Zn²⁺ along the (002) plane to eradicate dendrites. This results in an ultra-stable Zn anode with a substantially improved CE of 99.8% over 1200 cycles and a high cumulative plated capacity of 5.57 A h cm⁻² at 5 mA cm⁻². The effectiveness of this approach is demonstrated by the extremely long lifespan of 22 000 cycles of a Zn//V₂O₅ full cell.