High Rate and Long-Cycle Life of Lithium-Sulfur Battery Enabled by High d-Band Center of High-Entropy Alloys.

Abstract

Efficient catalysis of intermediate lithium polysulfide (LiPS) conversion in lithium-sulfur batteries is crucial for enhancing sulfur reduction reaction (SRR) kinetics and suppressing the shuttle effect of LiPSs. High-entropy alloys (HEAs), with their compositional flexibility, structural diversity, and multielement synergy, are promising high-efficiency catalyst candidates. Herein, a work function-dominated d-band center rule is proposed to modulate the chemical absorption ability of LiPSs and the catalytic performance of HEA catalysts. The d-band center of the as-screened PtCuFeCoNi HEAs (PCFCN-HEAs) is modulated via distinct work functions of its five metallic elements. In addition, detailed density functional theory (DFT) calculations and X-ray absorption spectroscopy are performed to reveal the roles of individual metallic elements in HEAs. Optimizing the d-band center of PCFCN-HEAs notably enhances the adsorption of LiPSs and accelerates the SRR. PCFCN-HEA nanoparticles are deposited on the surface of hollow carbon spheres (HCSs) and they combine with hyphae carbon nanobelts (HCNBs) to form a PCFCN-HEA/HCS/HCNB composite as the sulfur host. The cathode with PCNFC-HEA catalyst exhibits stable cycling at 6C and delivers a high reversible capacity of 652 mAh g^-1 even at a high rate of 8C. DFT calculations further elucidate the stepwise catalytic mechanism of PCFCN-HEAs, offering a pathway for designing high-efficiency catalysts.