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.