Achieving stable and fast potassium storage of Sb2S3@MXene anode via interfacial bonding and electrolyte chemistry

Antimony sulfide (Sb2S3) is a promising high-capacity anode material for potassium ion batteries but suffers from intrinsic low electronic conductivity and large volume variation during cycling due to the large size of potassium ion, resulting in poor cycle and rate performance. Here, a unique MXene-wrapped Sb2S3 nanocomposite (Sb2S3@MXene) with robust interfacial Sb-O-Ti bonding was designed as an anode material for PIBs, where the metallic MXene framework and interfacial Sb-O-Ti bonding can promote the charge transfer of the Sb2S3@MXene, restrain the nano-Sb2S3 agglomeration, and alleviate the volume expansion of Sb2S3 during potassiation. Moreover, the positive effect of high-concentrated 5 M KFSI-DME electrolyte was revealed through X-ray photoelectron spectroscopy, Raman spectroscopy, and density functional theory simulation, which can form a robust inorganic-rich solid electrolyte interphase layer on the electrode surface, enhancing the stability of the electrode. The robust interfacial characteristics between MXene, Sb2S3, and electrolyte endow the Sb2S3@MXene with boosted potassium storage performances, which delivered a high reversible capacity of 399.7 mAh g-1 at 100 mA g−1, excellent cycle stability (422.1 mAh g-1 after 100 cycles), and superior rate capability (119.0 mAh g-1 at 2 A g-1), demonstrating its great potential as an anode material for PIBs.