Rapid Growth of BiSe 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 BiSe@MXene composite is prepared for the first time by rapidly growing BiSe nanodots on two-dimensional (2D) MXene nanosheets at room temperature through simply adding high-reactive hydroxyethylthioselenide in Bi/MXene aqueous solution. BiSe@MXene exhibits a 2D structure due to the template effect of 2D MXene. BiSe@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. BiSe@MXene can also be used as an interfacial lithiophilic layer to inhibit Li dendrite growth in the Li metal anode. Theoretical calculations reveal that BiSe nanodots in BiSe@MXene can effectively boost the adsorption ability with LiPSs, and the MXene in BiSe@MXene can accelerate the electron transport. Under the bidirectional regulation of BiSe@MXene in the Li metal anode and S cathode, the Li-S battery shows an enhanced electrochemical performance.