A carbon-coated spinel zinc cobaltate doped with manganese and nickel as a cathode material for aqueous zinc-ion batteries.

Here, a new amorphous material composed of carbon-coated zinc cobaltate doped with manganese and nickel ZNMC@C (ZnNi0.5Mn0.5CoO4@C) with a spinel structure is proposed as a cathode material for use in aqueous zinc-ion batteries. This cathode material exhibits a high charge/discharge capacity with an initial capacity of about 160 mA h g-1 and its capacity retention rate remains at 60% after 500 cycles at 0.2 A g-1, which is higher than that of some reported spinel cathode materials. This superior electrochemical performance can be ascribed to the synergistic effect of the co-doping of manganese and nickel, which produces reversible multivalence redox transition activity (Co4+/Co3+, Ni4+/Ni3+/Ni2+, and Mn4+/Mn3+) that facilitates the insertion and migration of zinc ions and the existence of an outer amorphous carbon coating that effectively inhibits the dissolution of the cathode structure and stabilizes the cathode structure. In addition, the cycling mechanism of ZNMC@C was analyzed in detail through electrochemical measurements of the different cycling stages, including the kinetic behavior based on cyclic voltammetry and electrochemical impedance spectroscopic analysis and the reaction mechanism from X-ray photoelectron spectroscopy, ex situ X-ray diffractometry and ex situ scanning electron microscopy analysis. These research results suggest that the ZNMC@C composite material could be a competitive cathode material for Abs (aqueous rechargeable batteries).