Steering Isotropic Li 2 S Growth via Bi‐Metallic Coupling: d ‐State Reengineering for Durable Li‐S Batteries
Qi Liang, Haojie Song, Fei Liang, Yunfei Bai, Yi Gu, Yanjie Wang, Yao Yao, Hengzhi Liu, Yiyong Zhang, Rui Tian, Jiaxuan Liao, Sizhe WangABSTRACT
Uncontrolled Li 2 S accumulation and high nucleation barriers severely hinder the sulfur utilization and cycle lifespan of lithium‐sulfur batteries (LSBs). Herein, we report an advanced bimetallic Mo 2 V 2 C 3 T x MXene as a functional separator modifier designed to accelerate the Li 2 S nucleation and growth kinetics. Compared with V 4 C 3 T x , strategic substitution of Mo 2+ effectively modulates the d ‐orbital occupancy of V 2+ centers. This electronic reconfiguration drives an upshift of the d ‐band center toward the Fermi level, accompanied by a significant broadening of the d ‐band. Theoretical calculations combined with in situ analyses reveal that the unique Mo‐V bimetallic coupling induces d ‐orbital delocalization, which strengthens d‐p orbital hybridization between the Mo 2 V 2 C 3 T x and polysulfides, ultimately achieving an isotropic electric field distribution. This precise modulation dictates the Li 2 S deposition morphology, facilitating the isotropic growth of ultra‐uniform 3D spheres while maintaining high interfacial Li + flux. Consequently, the full battery exhibits a low‐capacity fading rate of 0.017% per cycle after 1500 cycles at 2 C. Even under a high sulfur loading of 6.8 mg cm −2 , the cell retains 92.1 of its initial capacity over 200 cycles at 1 C. This work establishes a new paradigm for the structure‐property relationship between Li 2 S deposition morphology and electrochemical performance by employing a bimetallic coupling strategy.