Mass-producible in-situ amorphous solid/electrolyte interface with high ionic conductivity for long-cycling aqueous Zn-ion batteries

Although aqueous Zn-ion batteries (aZIBs) have garnered significant attention, they are yet to be commercialized due to severe corrosion and dendrite growth on Zn anodes. In this work, an artificial solid-electrolyte interface (SEI) with amorphous structure was created in-situ on the anode by immersing Zn foil in ethylene diamine tetra(methylene phosphonic acid) sodium (EDTMPNA5) liquid. This facile and effective method provides the possibility for Zn anode protection in large-scale applications. Experimental results, combined with theoretical calculations, indicate that the artificial SEI remains intact and adheres tightly to the Zn substrate. The negatively-charged phosphonic acid groups and disordered inner structure offer adequate sites for rapid Zn2+ transference and facilitate [Zn(H2O)6]2+ desolvation during charging/discharging. Due to the synergistic effect of the aforementioned advantages, the artificial SEI endows high Coulombic efficiency (CE, 99.75%) and smooth Zn deposition/stripping under the SEI. The symmetric cell exhibits a long cycling life of over 2400 h with low-voltage hysteresis. Additionally, full cells with MVO cathodes demonstrate the superiority of the modified anodes. This work provides insight into the design of in-situ artificial SEI on the Zn anode and self-discharge suppression to expedite the practical application of aZIBs.