Re-doped MoS2 nanolayers encapsulated within dual‑carbon architecture for potassium-ion capacitors

Due to the abundance and low cost of potassium resources, potassium-ion capacitors (PICs), comprising battery-type anode electrodes and capacitor-type cathode electrodes, are gradually receiving more attention. Identifying anode materials with superior performance holds the key to resolving the kinetic mismatch between anode and cathode electrode materials. In this work, carbon-coating, rhenium (Re)-doped MoS 2 nanolayers grown on carbon nanotubes (CRMC) were prepared as an anode for PICs. As a group-VII element, Re shares chemical similarities with Mo and can be easily doped into the MoS 2 lattice. The doping of Re atoms modulates the intrinsic conductivity of MoS 2 , improves the diffusion rate of K + in the electrode material, and enhances reaction kinetics. Additionally, the increased number of active sites facilitates improved K + storage. The incorporation of CNTs and carbon coatings not only enhances the electrical conductivity of the material but also alleviates volume expansion during cycling, thereby improving the cycling stability. Benefiting from the spatial network structure, rapid electron/ion transport and abundant active sites of CRMC, the CRMC electrode exhibits a high reversible capacity of 350.6 mA h g −1 at 50 mA g −1 , an impressive high-rate performance of 193.2 mA h g −1 at 5.0 A g −1 , and excellent cycling stability. The PICs with CRMC as the anode provide a high-power density of 12.3 kW kg −1 while achieving a high energy density of 54.8 Wh kg −1 , along with a capacity retention rate of up to 76.5 % over 10,000 cycles. This study presents an optimization strategy for the structural design of PICs' anode materials to enhance reaction kinetics, which holds great promise for practical applications. • Re-doped MoS 2 are integrated into a dual-carbon architecture. • Re doping enhances the intrinsic conductivity of MoS 2 . • The dual-carbon structure ensures structural stability. • PICs using CRMC as anode materials exhibit good energy-power output.