Exploring the Mechanism of Single-Crystal MnO2 as Cathodes for Zinc Ion Batteries.

Abstract

MnO2 has the advantages of low cost and abundant resources, so it is considered to be an important electrode material in zinc ion batteries. However, its practical application is still challenged by easy collapse and capacity loss. In this paper, a stable single crystal β-MnO2 nanorod cathode material was prepared. When used as ZIBs cathode material, single crystal β-MnO2 has high ionic diffusion kinetics and calculability. In this paper, we prepared single-crystal MnO2 through hydrothermal nanotechnology. By leveraging the benefits of the single-crystal structure, we optimized the structural stability, ion conductivity, surface reactions, and phase control of the cathode material, resulting in improved battery performance and cycle life. In the fabricated single-crystal MnO2 aqueous zinc-ion battery, the elimination of internal crystal faces in MnO2 leads to ordered lattice arrangement, enabling a more direct and unobstructed diffusion path for H+ ions within the lattice. This significantly enhances the ion conductivity of the cathode material, promoting the rate and efficiency of the battery's charge and discharge processes. Therefore, single-crystal MnO2 exhibits excellent cycling performance for zinc-ion storage in ZIBs, achieving a high specific capacity of 224.7 mA h g-1 after 250 cycles under a current density of 0.3 A g-1 , while maintaining a Coulombic efficiency of 99.58 %.