In Situ Construction of an Amorphous and Ultrathin Manganese Oxide Protective Layer for Highly Stable Zinc Anodes

Zn anodes always suffer from severe dendrite growth and slow ion transfer kinetics at the Zn/electrolyte interface, leading to poor cycling stability and rate performance. Rational design of an artificial solid electrolyte interphase (SEI) with uniform structure and rapid ion transport capability is regarded as a promising strategy to solve the Zn anode issues. Herein, a manganese oxide (MnOx) protective layer is in situ constructed on a Zn anode (denoted as Mn@Zn), circumventing the conventional slurry casting method. The ultrathin and amorphous (30–40 nm) protective layer provides numerous isotropic Zn2+ transport pathways, realizing the Zn2+ homogeneous deposition to inhibit the formation of Zn dendrite. More importantly, when Zn2+ transfers in the ultrathin protective layer, the Mn element exhibits a low valence state. The adjacent element can easily bind with Zn2+ and constructs rapid Zn2+ diffusion pathways in the SEI layer, which effectively reduces the deposition energy barrier. As a result, the symmetric cells based on Mn@Zn electrodes display a long lifetime up to 1000 h at 1.0 mA cm–2. In addition, the Mn@Zn||V2O5 full batteries also exhibit excellent cycling stability with a high capacity retention of 87.6% after 3000 cycles at 5.0 A g–1. This work offers a reliable method for the in situ construction of artificial SEI layers on Zn anodes.