Rapid Growth of Bi2Se3 Nanodots on MXene Nanosheets at Room Temperature for Promoting Sulfur Redox Kinetics

Li-S batteries are hampered by problems with their cathodes and anodes simultaneously. The improvement of Li-S batteries needs to consider both the anode and cathode. Herein, a Bi₂Se₃@MXene composite is prepared for the first time by rapidly growing Bi₂Se₃ nanodots on two-dimensional (2D) MXene nanosheets at room temperature through simply adding high-reactive hydroxyethylthioselenide in Bi³⁺/MXene aqueous solution. Bi₂Se₃@MXene exhibits a 2D structure due to the template effect of 2D MXene. Bi₂Se₃@MXene can not only facilitate the conversion of lithium polysulfides (LiPSs) but also inhibit their shuttling in the S cathode due to its catalytic effect and adsorption force with LiPSs. Bi₂Se₃@MXene can also be used as an interfacial lithiophilic layer to inhibit Li dendrite growth in the Li metal anode. Theoretical calculations reveal that Bi₂Se₃ nanodots in Bi₂Se₃@MXene can effectively boost the adsorption ability with LiPSs, and the MXene in Bi₂Se₃@MXene can accelerate the electron transport. Under the bidirectional regulation of Bi₂Se₃@MXene in the Li metal anode and S cathode, the Li-S battery shows an enhanced electrochemical performance.