Tuning p‐Band Centers and Interfacial Built‐In Electric Field of Heterostructure Catalysts to Expedite Bidirectional Sulfur Redox for High‐Performance Li–S Batteries
Xinying Wang, Li Chen, Yaojiang Yu, Wei Wang, Liguo Yue, Zhuhang Shao, Hao Wu, Yunyong Li
Abstract
Abstract Transition‐metal compound based heterostructures hold promise but challenge in expediting stepwise sulfur redox because of their inferior adsorption‐catalysis activity and unclear mechanism in Li–S batteries (LSBs). Herein, the p‐band centers and interfacial charge rearrangement of Mo‐doped VS 2 /MXene heterostructure are tuned through Mo doping and built‐in electric field (BIEF) effect to boost dual‐directional sulfur redox. Experimental and theoretical calculations demonstrate that Mo doping tunes the p‐band center of active S in VS 2 , shifting it positively toward the Fermi level to enhance the polysulfide adsorption ability and electrocatalytic activity. Whereas BIEF between Mo‐VS 2 and MXene accelerates electrons transfer from MXene to Mo‐VS 2 surface, generating more electrons accumulation at the surface‐S sites. Their synergy accelerates sulfur‐species conversion by reducing the energy barrier of polysulfide reduction and Li 2 S oxidation. Ultimately, S/Mo‐VS 2 /MXene cathode exhibits large initial capacity of 1387 mAh g −1 at 0.2 C and stable 500‐cycle long‐term lifespan at 0.5 C. Impressively, the thick S/Mo‐VS 2 /MXene cathode (S loading: 5.4 mg cm −2 , lean electrolyte: 4.5 µL mg sulfur −1 ) achieves a high areal capacity of 6.44 mAh cm −2 with 91.5% retention for 61 cycles. This work highlights the synergistic strategy of doping engineering and BIEF to tune the p‐band centers and interfacial charge rearrangement for designing high‐performance LSBs.