Electrochemical activated MoO2/Mo2N heterostructured nanobelts as superior zinc rechargeable battery cathode

Abstract Aqueous Zn-ion batteries are desirable for large-scale application over Li-ion batteries due to the low cost, high safety and environment friendliness. However, the development of Zn-ion batteries is seriously impeded by a limited choice of positive electrodes. Herein, we report an electrochemical activated porous MoO 2 /Mo 2 N heterostructured nanobelts cathode. During the electrochemical activation, it is interesting to find that MoO 2 grains in-situ generate in Mo 2 N matrix. The generated MoO 2 grains can not only accommodate the intercalated zinc ions, leading to high reversible capacity, but also provide high electronic conductivity, thereby improving the rate capability. On the other hand, the Mo 2 N matrix could protect the MoO 2 grains from structure degradation during cycling and keep stable in the slight acidic electrolyte. Based on the synergic effect of MoO 2 and Mo 2 N, electrochemical activated MoO 2 /Mo 2 N heterostructured nanobelts exhibit a high reversible capacity of 113 mAh/g at high current density of 1 A/g for 1000 cycles, showing long-term cyclic stability (capacity retention is 78.8%) and remarkable rate capability. It is believed that the superior performance is attributed to the synergistic effect of integrated MoO 2 grains and Mo 2 N nanobelt matrix. This strategy of electrochemical activation process can be expanded to other metal nitride as zinc battery cathode.