Enhanced potassium-ion storage in MoS2@CNT composites via supercritical CO2 exfoliation and metallic 1T-phase engineering

Potassium-ion batteries (PIBs) offer a promising alternative to lithium-ion batteries due to the abundant storage and low cost of potassium. However, they still suffer from severe volume expansion and sluggish kinetics. Herein, a supercritical CO 2 (SC CO 2 )-assisted strategy is employed to fabricate MoS 2 @CNT composites with enhanced electrochemical performance. The SC CO 2 process exfoliates bulk MoS 2 into ultrathin nanosheets and simultaneously anchors them onto single-walled carbon nanotubes (SWCNTs), forming a stable 3D conductive network. One step further, this method concurrently induces a partial phase transition of MoS 2 from the semiconducting 2H phase to the metallic 1 T phase, significantly improving electrical conductivity and ion transport. The MoS 2 @CNT/20 MPa composite demonstrates a high reversible capacity of 706.89 mA h g −1 at 0.1 A g −1 and retains 380.10 mA h g −1 at 2.0 A g −1 . Kinetic analysis reveals predominantly capacitive K + storage behavior, while ex situ characterizations after 100 cycles confirm the structural stability and the stable solid electrolyte interphase (SEI). This study highlights the synergistic effects of SC CO 2 exfoliation and SWCNT hybridization, offering a scalable and environmentally friendly approach for designing high-performance anode materials for next-generation PIBs.