3D Alk-MXene@Fe₃O₄ as Cathode Additive for Rechargeable Lithium−Sulfur Batteries

Lithium−sulfur battery (LSB) is one of the most promising next-generation batteries due to its high energy density and low cost. However, the serious shuttle effect, large volume change, and poor conductivity have hindered their commercialization. Herein, alk-MXene@Fe₃O₄ composite is synthesized through ultrasonic treatment of alkalized MXene and Fe₃O₄ and it is used as additive in the sulfur cathode. The results indicate that Alk-MXene@Fe₃O₄ additive can anchor polysulfides by the strong polar adsorption and accelerate the conversion of the LiPSs. The cathode with Alk-MXene@Fe₃O₄ retains a substantially stable discharge capacity of 681.7 mAh g⁻¹ after 120 cycles at a rate of 0.2 C, which is equivalent to 58.6% of the initial discharge capacity (1163 mAh g⁻¹), and the corresponding capacity decay per cycle is 0.35%. At a rate of 1 C, it can still retain 595 mAh g⁻¹ after 200 cycles. It has important reference value for the development of cathode additives to improve the performance of active sulfur.