Sulfur-Decorated Ti₃ C₂ T_X MXene for High-Performance Sodium/Potassium-Ion Batteries

As post-lithium ion batteries, both sodium-ion batteries (SIBs) and potassium ion batteries (PIBs) possess great potential for large scale energy storage. However, the application of both SIBs and PIBs are hindered by the lack of suitable electrode materials. Here, we synthesized the sulfur decorated Ti₃ C₂ T_x (S-T₃ C₂ T_x ) MXene as electrode material for SIBs and PIBs. Thanks to the sulfur functional group and the formation of Ti-S bond, which facilitates the sodium in-/desertion and strengthens the potassium ion adsorption ability, as well as enhances ion reaction kinetics and improved structure stability, the S-T₃ C₂ T_x exhibit excellent sodium/potassium storage performance, high reversible capacities of 151 and 101 mAh g^-1 at 0.1 mA g^-1 were achieved for SIBs and PIBs, respectively. Moreover, the S-T₃ C₂ T_x exhibits remarkable long-term capacity stability at a high density of 500 mA g^-1 , providing an impressive storage of 88 mAh g^-1 for SIBs and 41 mAh g^-1 for PIBs even after 2000 cycles. This work could give a deep comprehension of the heteroatom modification influence on the MXene-based framework and promote the application of MXene electrodes.