Regulating Electron Filling and Orbital Occupancy of Anti-Bonding States of Transition Metal Nitride Heterojunction for High Areal Capacity Lithium-Sulfur Full Batteries.

Abstract

The commercialization of lithium-sulfur (Li-S) battery is seriously hindered by the shuttle behavior of lithium (Li) polysulfide, slow conversion kinetics, and Li dendrite growth. Herein, a novel hierarchical p-type iron nitride and n-type vanadium nitride (p-Fe2N/n-VN) heterostructure with optimal electronic structure, confined in vesicle-like N-doped nanofibers (p-Fe2N/n-VN⊂PNCF), is meticulously constructed to work as "one stone two birds" dual-functional hosts for both the sulfur cathode and Li anode. As demonstrated, the d-band center of high-spin Fe atom captures more electrons from V atom to realize more π* and moderate σ* bond electron filling and orbital occupation; thus, allowing moderate adsorption intensity for polysulfides and more effective d-p orbital hybridization to improve reaction kinetics. Meanwhile, this unique structure can dynamically balance the deposition and transport of Li on the anode; thereby, more effectively inhibiting Li dendrite growth and promoting the formation of a uniform solid electrolyte interface. The as-assembled Li-S full batteries exhibit the conspicuous capacities and ultralong cycling lifespan over 2000 cycles at 5.0 C. Even at a higher S loading (20mg cm-2) and lean electrolyte (2.5µL mg-1), the full cells can still achieve an ultrahigh areal capacity of 16.1 mAh cm-2 after 500 cycles at 0.1 C.