Carbon-Coated MoSe2/MXene Hybrid Nanosheets for Superior Potassium Storage.

Potassium-ion batteries (PIBs) are attracting intensive interest for large-scale applications due to the high natural abundance of potassium sources. However, the large radius of K+ makes it difficult for electrode materials to accommodate the repeated K+ insertion and extraction. Thus, developing high-performance electrode materials for PIBs remains a great challenge. Herein, we present the rational design and fabrication of hierarchical carbon-coated MoSe2/MXene hybrid nanosheets (MoSe2/MXene@C) as a superior anode material for PIBs. Specifically, the highly conductive MXene substrate can effectively relieve the aggregation of MoSe2 nanosheets and improve the electronic conductivity. Moreover, the carbon layer enables us to reinforce the composite structure and further enhance the overall conductivity of the hybrid nanosheets. Meanwhile, strong chemical interactions are found at the interface of MoSe2 nanosheets and MXene flakes, contributing to promoting the charge-transfer kinetics and improving the structural durability. Consequently, as an anode material for PIBs, the resulting MoSe2/MXene@C achieves a high reversible capacity of 355 mA h g-1 at 200 mA g-1 after 100 cycles and an outstanding rate performance with 183 mA h g-1 at 10.0 A g-1. The presented design strategy holds great promise for developing more-efficient electrode materials for PIBs.