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

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 MoO2/Mo2N heterostructured nanobelts cathode. During the electrochemical activation, it is interesting to find that MoO2 grains in-situ generate in Mo2N matrix. The generated MoO2 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 Mo2N matrix could protect the MoO2 grains from structure degradation during cycling and keep stable in the slight acidic electrolyte. Based on the synergic effect of MoO2 and Mo2N, electrochemical activated MoO2/Mo2N 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 MoO2 grains and Mo2N nanobelt matrix. This strategy of electrochemical activation process can be expanded to other metal nitride as zinc battery cathode.