VSe2/MXene composite with hierarchical three-dimensional structure encapsulated in dopamine as an anode for potassium-ion batteries

Potassium-ion batteries (PIBs) receive intensive interest because of the natural abundance of potassium sources and their potency to achieve high energy density. VSe2 is one of the promising electrode materials equipped with a huge interlayer distance, which can accommodate more K+ ions and reduce the structural distortion caused by the diffusion of K+ ions. But the problem of self-aggregation of VSe2 hinder its further application. Therefore, taking advantage of excellent electrical conductivity and mechanical strength of MXene, VSe2/MXene@C composites with a hierarchical three-dimensional structure are designed. Especially, VSe2 nanosheets are anchored on MXene substrates by strong covalent bonds, bridging with an oxygen atom. In addition, coating the carbon layer can avoid the deterioration of VSe2/MXene and improve the capacity and cycling stability of batteries effectively. As a result, the VSe2/MXene@C exhibits an excellent reversible capacity of 302.4 mAh g(-1) with a coulombic efficiency of 99.49% at 200 mA g(-1) after 200 cycles, long-term cycling performance of 138.7 mAh g(-1) at 1 A g(-1) after 500 cycles, and superior rate performance of 106.9 mAh g(-1) at 2 A g(-1). With outstanding electrochemical performance, the VSe2/MXene@C shows promise to become an excellent anode material for potassium-ion batteries(PIBs).