Thickness-Controlled Synthesis of Compact and Uniform MOF Protective Layer for Zinc Anode to Achieve 85% Zinc...

Zinc anode-based aqueous batteries have attracted considerable interest for large-scale energy storage and wearable devices. Unfortunately, the formation of Zn dendrite, parasitic hydrogen evolution reaction (HER), and irreversible by-products, seriously restrict their practical applications. Herein, a series of compact and uniform metal-organic frameworks (MOFs) films with precisely controlled thickness (150-600 nm) are constructed by a pre-oxide gas deposition (POGD) method on Zn foil. Under the protection of MOF layer with optimum thickness, the corrosion of zinc, the side reaction of hydrogen evolution, and the growth of dendrites on the zinc surface are suppressed. The symmetric cell based on Zn@ZIF-8 anode exhibits exceptional cyclicality for over 1100 h with low voltage hysteresis of≈38 mV at 1 mA cm^-2 . Even at current densities of 50 mA cm^-2 with an area capacity of 50 mAh cm^-2 (85% Zn utilization), the electrode can keep cycling for >100 h. Besides, this Zn@ZIF-8 anode also delivers a high average CE of 99.4% at 1 mA cm^-2 . Moreover, a rechargeable Zn ion battery is fabricated based on the Zn@ZIF-8 anode and MnO₂ cathode, which presents an exceptionally long lifespan with no capacity attenuation for 1000 cycles.