Reasonable suppression of polysulfides/polyselenides shuttle based on MXene in Na-SeS₂ batteries

Metal-sulfur/selenium batteries have become the focus of new-generation energy storage systems due to the advantages of low-cost and high energy density. However, it still suffers from the notorious shuttle of polysulfides/polyselenides, poor electronic conductivity and tremendous volume expansion. Herein, a dual defense system for polysulfides/polyselenides was proposed and constructed based on MXene. The nitrogen-doped porous carbon (NPC) decorated by Ti₃C₂T_x MXene (M@NPC) was employed as the SeS₂ host (SeS₂@M@NPC). Particularly, Ti₃C₂T_x sheets wrapped on NPC guarantee the rapid ion diffusion and serve as the first barrier for SeS₂ and dissolved sodium polysulfides/polyselenides. Meanwhile, the few-layered Ti₃C₂T_x sheets coated on glass fiber separators act as the second barrier for alleviating the shuttle of polysulfides/polyselenides through physical interception and chemical adsorption. With this elaborate design, the integrated Na-SeS₂ battery achieves a high specific capacity of 1243 mAh·g⁻¹ at 1.0C, revealing a distinct superiority over its counterparts (SeS₂@M@NPC, 1083 mAh·g⁻¹ at 0.5C; and SeS₂@NPC, 823 mAh·g⁻¹ at 0.5C). The findings gained in this work provide a creative idea for the construction of durable room-temperature Na-SeS₂ batteries based on MXenes and their derivative materials.