Mno 2  With Enhanced Performance as Cathode Material for Aqueous Zinc Ion Battery Enabled by Surface Oxygen Defect

Abstract

Compared with conventional lithium-ion batteries with organic electrolyte, the aqueous batteries have considerable advantages in safety performance, cost, environmental compatibility and so on. The zinc-ion batteries have incomparable advantages in electrochemical performance, and they are the most promising batteries to break the monopoly of lithium-ion batteries at the present stage. However, a series of defects such as poor conductivity and unstable structure of cathode materials hinder the further development of zinc-ion batteries. In this paper, Manganese oxide with oxygen defects on the surface (Od-MnO2) was successfully constructed by chemical reduction and characterized by XRD, SEM, XPS and TEM, confirming the presence of oxygen defects. On the one hand, surface oxygen defects increase ion active transfer sites; on the other hand, the regulation of electronic structure by defects result in improved electronic conductivity. Compared with raw MnO2, the electrochemical performance of Od-MnO2 as aqueous zinc-ion battery was significantly improved. Od-MnO2 gives a special capacity of 486.9 mAh g-1 at a current density of 0.1 A g-1, and the special capacity can remain 110.5 mAh g-1 at a current density of 10.0 A g-1, to 92.5 mAh g-1, meanwhile the cycle stability is also good with a capacity retention rate of 83.75%.

Keywords: Aqueous zinc-ion batteries, Chemical reduction method, Oxygen defects, Manganese dioxide