Petal-Shaped Fe-Based MBene Nanosheets for Efficient Lithium Polysulfide Conversion

The shuttle effect and slow reaction kinetics of soluble lithium polysulfides (LiPSs) have a significant impact on the cycle life and rapid charging and discharging capacity of lithium-sulfur (Li-S) batteries. Herein, the Fe-based MBene material was adopted to alleviate the above problems. Unlike previous LiF etching techniques, petal-shaped Fe₂Al1-_xB₂ was obtained through simple, nontoxic alkaline solution etching. The sheet-like two-dimensional structure not only effectively provided a large quantity of FeB adsorption active sites but also effectively reduced the resistance to charge transfer. Based on these advantages, the sulfur cathode modified with Fe₂Al1-_xB₂ thin layers achieved reversible capacities of 1103 and 478 mA h g^-1 at rates of 0.2 and 4 C, respectively. Even under high loading, the solution could provide an initial areal capacity of 5.4 mg cm^-2. It provided a new idea for the Li-S application of Fe-based two-dimensional borides.