Novel in situ SEI fabrication on Zn anodes for ultra-high current density tolerance enabled by electrical excitation–conjugation of iminoacetonitriles

Abstract

Aqueous zinc-ion batteries (AZIBs) offer significant advantages, including low cost, inherent safety, and high theoretical capacity. However, they are prone to surface corrosion and uncontrolled dendrite growth on zinc anodes, particularly under high current densities. Herein, we propose an artificial solid electrolyte interphase (SEI) composed of complex Zn²⁺ salts to alter the de-solvation process and homogenize the electric field, thereby enabling stable circulation of AZIBs. This SEI is formed through the excitation of iminodiacetonitrile (IDAN) into iminodiacetic acid (IDA) on the surface of the zinc anode during electroplating. Simultaneously, the generated IDAs conjugate with flowing zinc ions thus creating a dense protective layer embedded into the anode surface. The obtained SEI exhibits superior Zn²⁺ conductivity, super-hydrophilic properties, electrical insulation and negligible interfacial resistance, imparting outstanding durability to the zinc anode even at an ultra-high current density (100 mA cm⁻², over 630 h) without dendrite growth, giving a cumulative plating capacity exceeding 31.5 A h cm⁻². Moreover, the favorable zinc plating/stripping behavior facilitated by the SEI enables stable operation under harsh conditions (90% depth of discharge, 440 h of Zn||Zn and 20 A g⁻¹, 2000 cycles of Zn||NH₄V₄O₁₀). The current density tolerance provided by the complex SEI, achieved through a novel in situ excitation/conjugation fabrication process, promises to enrich SEI strategies and expand the application of AZIBs, particularly in fast-charging/discharging battery systems.