Anchoring MoSe2 nanosheets on N-doped carbon nanotubes as high performance anodes for potassium-ion batteries

Abstract

Transition metal dichalcogenides (TMDs) such as MoSe2 have received extensive attention as anodes for Potassium-ion batteries (KIBs) due to their high energy density and unique layered structure. However, the low conductivity and structural collapse during the insertion and extraction of K+ can lead to fast capacity decay and poor rate performance. Herein, a sheet-on-tube structure of MoSe2 nanosheets@N-doped carbon nanotubes (MoSe2@NCT) is rationally designed and prepared by hydrothermal and subsequent annealing process. The NCT can increase the electrical conductivity and stabilize the MoSe2 nanosheets during repeated charging and discharging processes, thus improving the electrochemical performance of MoSe2@NCT. In addition, the high level N-doping in NCT can create paramount defects serving as the active sites to facilitate K+ storage. Electrochemical tests reveal that the MoSe2@NCT demonstrates a high reversible capacity (247 mA h g − 1 after 100 cycles at 0.1 A g − 1), cycling stability and superior rate performance. A series of physic-chemical tests indicate the very good electrochemical performances are resulting from the nanosheet structure of MoSe2, high conductivity of carbon and functional N-doping. The proposed strategy in structure engineering and the excellent electrochemical properties delivered in this work may provide a new idea to develop high performance anodes in KIBs.