Co3C/Mxene composites wrapped in N-rich carbon as stable-performance anodes for potassium/sodium-ion batteries

Potassium-ion and sodium-ion batteries (PIBs and SIBs) attract the attention of researchers because of their high earth abundance, low cost, and even similar principle to lithium-ion batteries. MOF-derived transition metal carbide composites are regarded as promising electrode materials because of their high specific capacity and excellent electrochemical activities while equipped with excellent sodiophilic for sodium nucleation and deposition. Therefore, Co3C/MXene@C composites with a large specific surface area are designed for both PIBs and SIBs. In detail, the Co3C component plays a key role in electrocatalysis of reversible conversion of some components of solid electrolyte interface films, while rich defective carbon and nitrogen content can improve the whole activity of the material. As results, the Co3C/MXene@C electrodes deliver an excellent reversible capacity of 236 mA h g−1 with the coulombic efficiency of 98.51% (for PIBs) and 275.9 mA h g−1 with the coulombic efficiency of 98.43% at 200 mA g−1 (for SIBs) after 100 cycles, superior rate performance of 80.6 mA h g−1 and 105 mA h g−1 at 2000 mA g−1 for PIBs and SIBs, respectively. With these outstanding electrochemical performances, the Co3C/MXene@C electrodes show a potential application prospect for potassium-ion and sodium-ion batteries.