Encapsulation of CoS2 nanoparticles in bamboo-like carbon nanotubes as advanced potassium-ion batteries anodes

Transition metal sulfides (TMSs) have been widely investigated as anode materials for potassium ion batteries (PIBs) due to their high theoretical capacity. However, the intense volume change of TMSs in the process of charge/discharge will lead to the destruction of material structure and the decrease of potassium storage performance. Herein, CoS2/CNTs composites are prepared by carbonization and in-situ vulcanization, and the CoS2 nanoparticles are encapsulated in bamboo-like carbon nanotubes. The unique structure can buffer the volume change during charge/discharge, which is responsible for the strong structural stability and remarkable electrochemical storage performance of the composite. When assembled as PIBs half-cell, the CoS2/CNT-600 composite exhibits excellent rate performance (303.7 mAh g−1 at 2000 mA g−1) and favorable cycling stability (325.7mAh g−1 at 100 mA g−1 after 500 cycles). In addition, the successful assembly of the full cell validates the practical application prospects of CoS2/CNT-600 electrodes.