Uniform zinc electrodeposition directed by interfacial cation reservoir for stable Zn-I2 battery

Rough interfacial Zn electrodeposition and severe parasitic side reactions in aqueous electrolyte, resulting in increased internal resistance and limited reversibility, have significantly hindered the commercial deployment of Zn metal anode. Interfacial engineering offers a versatile platform for manipulating the zinc-ion flux and suppressing side reactions, via pre-formation of an artificial interlayer. Herein, we demonstrate a zincophile inter phase based on metal-organic framework cation reservoir. The zinc hexacyanoferrate nanocubes with interconnected open cation transfer channels uniformize the interfacial electric field and render the protected electrode with faster zinc redox kinetic and higher exchange current density. The cations within the reservoir served as an ion-transfer mediator could regulate interfacial Zn2+ even distribution and lower zinc-ion nucleation energy barrier, consequently promoting the homogeneous Zn electrodeposition. Additionally, the in situ preformed film also enhances the thermodynamic stability of metal anode and avoids the water-induced side interfacial reaction. The protected anode exhibits an extremely low voltage hysteresis and achieves a high average Coulombic efficiency (similar to 99.6%) for 400 h with dendrite-free behaviors. When coupled with an iodine cathode, the favorable electrochemical performance of full Zn-I-2 cells is realized, representing an advanced practical step toward stable Zn metal anode for real applications.

Automated summary

Interfacial engineering using a metal-organic framework cation reservoir as a zincophile interphase offers a solution to manipulate zinc-ion flux, suppress side reactions, and improve the performance of zinc metal anodes.