Facile Synthesis of FePS Nanosheets@MXene Composite as a High-Performance Anode Material for Sodium Storage.

Searching for advanced anode materials with excellent electrochemical properties in sodium-ion battery is essential and imperative for next-generation energy storage system to solve the energy shortage problem. In this work, two-dimensional (2D) ultrathin FePS nanosheets, a typical ternary metal phosphosulfide, are first prepared by ultrasonic exfoliation. The novel 2D/2D heterojunction of FePS nanosheets@MXene composite is then successfully synthesized by in situ mixing ultrathin MXene nanosheets with FePS nanosheets. The resultant FePS nanosheets@MXene hybrids can increase the electronic conductivity and specific surface area, assuring excellent surface and interfacial charge transfer abilities. Furthermore, the unique heterojunction endows FePS nanosheets@MXene composite to promote the diffusion of Na and alleviate the drastic change in volume in the cyclic process, enhancing the sodium storage capability. Consequently, the few-layered FePS nanosheets uniformly coated by ultrathin MXene provide an exceptional reversible capacity of 676.1 mAh g at the current of 100 mA g after 90 cycles, which is equivalent to around 90.6% of the second-cycle capacity (746.4 mAh g). This work provides an original protocol for constructing 2D/2D material and demonstrates the FePS@MXene composite as a potential anode material with excellent property for sodium-ion batteries.