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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 Ti3C2Tx (S−T3C2Tx) 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−T3C2Tx 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−T3C2Tx 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. [ABSTRACT FROM AUTHOR]

Tavorite LiFeSO 4 F with high Li-ion conductivity has been considered a promising alternative to LiFePO 4 . However, its poor cycle stability and low electronic conductivity limit the practical application of Tavorite LiFeSO 4 F. In the present study, we employ a solvothermal method to produce magnesium-substitution LiMg x Fe 1- x SO 4 F ( x = 0, 0.02, 0.04) cathode materials in which the Mg substitutes the Fe(2) sites. The first-principles calculations demonstrate that Mg-substitution could reduce the bandgap of LiFeSO 4 F and increase its electronic conductivity to 2.5 × 10 -11 S cm -1 . Meanwhile, CI-NEB and BV calculations reveal that the diffusion energy barrier of lithium along the (100) direction after Mg substitution is lower than the pristine sample, and the electrochemical inactive Mg 2+ could improve the structure stability. The results show that the Mg-substituted LiFeSO 4 F exhibits enhanced cycle stability and rate performance compared with the pristine LiFeSO 4 F, suggesting that the use of electrochemically inactive ion substitution may be critical for the development of high-performance LiFeSO 4 F cathode materials for lithium-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 Ti 3 C 2 T x (S-T 3 C 2 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-T 3 C 2 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-T 3 C 2 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., (© 2023 Wiley-VCH GmbH.)