Cobalt-doped molybdenum disulfide with rich defects and extended layered structure for rechargeable zinc-ion batteries

Abstract

Zinc-ion batteries (ZIBs) have become potential energy storage devices due to its low cost, environmentally friendly and high safety. The development of ZIBs is facing huge challenges especially in cathode materials. Here, we report a strategy of doping Co into MoS 2 to get Co x Mo 1−x S 2 nanosheets with rich dislocation-defects and expanded layer spacing. MoS 2 itself has poor Zn 2+ diffusivity and low specific capacity due to small layer spacing. The diffusion of Zn 2+ is greatly improved by doping of Co. When Co x Mo 1−x S 2 nanosheets are used as positive electrode in ZIBs, the capacity increased from 31.3 mA h g −1 to 164.1 mA h g −1 , which is increased by more than five times. What’s more, even if the current is increased ten times, it still has high capacity (about 40% capacity retention). In addition, the peaks of the Zn 2+ intercalation/deintercalation in the Co x Mo 1−x S 2 electrode have been effectively improved, which indicates a much more efficiency Zn 2+ intercalation kinetic. Therefore, its capacity has been greatly improved. This research provides a general and effective strategy to reduce the embedding energy barrier of Zn 2+ to increase the diffusion rate of Zn 2+ and the capacity of ZIBs. • The addition of Co leads to dislocations defects and extending the layer spacing. • The transition metal doping method is convenient and efficient. • The rapid diffusion of Zn 2+ is achieved and the capacity is increased.