Enhanced cycling stability achieved by the nitrogen doped carbon coating layer for electrodeposited Mn3O4 in aqueous zinc ion batteries

Aqueous rechargeable Zn-ion batteries (ZIBs) are promising candidates for large scale energy storage. Unfortu-nately, their application is hindered by the quick capacity fading. Herein, the Mn3O4@N-doped carbon coated carbon cloth electrodes (Mn3O4@NC/CC) are prepared by electrodeposition and calcination and are used as the cathode for ZIBs. The thickness of the electrodeposited Mn3O4 is -200 nm, and the NC layer is -10 nm. The ZIB with Mn3O4@NC/CC displays the capacity of 265.8 mAh g-1 at 0.2 A g-1, and has a high reversible capacity of 165.6 mAh g-1 after 2000 charged -discharged cycles at 3 A g-1. The capacitive-controlled processes contribute mainly to the charge storage mechanism. The introduction of NC layer can effectively prevent the disintegration of active material during charge-discharge cycling. The NC layer can also hinder the diffusion of Zn2+ and enhance Rct, that leads to suppressed Zn ion insertion/extraction and possibly milder change in crystal structure. Ex-situ characterization shows that the Mn3O4 is irreversibly converted to R-MnO2 after multiple charge -discharge cycles, and both H+ and Zn2+ participate in the charge storage processes.