In-situ doped Zn2+ modified MnO molecular structure to achieve the ultrahigh capacity aqueous zinc ion batteries

Abstract

Faintly acidic Zn-MnO_X batteries has been ultra-discussed as a focal point of the scientific community due to the rich natural resources and advanced industrial lines. However, its variable valence state and complex crystal structure can lead to the collapse of crystal phase structure and Mn dissolution in electrolyte. Herein, a Zn²⁺ doped Mn₃O₄ on carbon nanosheet arrays (Zn-Mn₃O₄/CNA) has been developed by calcination and electrochemical deposition. The Zn²⁺ insertion can make the structure will not collapse during the transition from spinel structure (Mn₃O₄) to layered structure (MnO₂). The carbon nanosheet arrays can improve the electric conductivity of electrochemical interface and easily in situ electrochemical deposition Mn₃O₄. It is worth noting that the Zn-Mn₃O₄/CNA cathode shows high-capacity of 316 mAh g⁻¹ and energy density of 420.8 Wh kg⁻¹ at 0.1 A g⁻¹. Besides, its capacity retention can reach 76.3 % after 600 cycles. This work proves that cationic doping can effectively suppress the Jahn-Teller effect and promote zinc ion diffusion during discharge.