P-Doped NiTe2 with Te-Vacancies in Lithium-Sulfur Batteries Prevents Shuttling and Promotes Polysulfide Conversion

Lithium-sulfur (Li-S) batteries have been hindered by the shuttle effect and sluggish polysulfide conversion kinetics. Here, a P-doped nickel tellurium electrocatalyst with Te-vacancies (P subset of NiTe2-x) anchored on maize-straw carbon (MSC) nanosheets, served as a functional layer (MSC/P subset of NiTe2-x) on the separator of high-performance Li-S batteries. The P subset of NiTe2-x electrocatalyst enhanced the intrinsic conductivity, strengthened the chemical affinity for polysulfides, and accelerated sulfur redox conversion. The MSC nanosheets enabled NiTe2 nanoparticle dispersion and Li+ diffusion. In situ Raman and ex situ X-ray absorption spectra confirmed that the MSC/P subset of NiTe2-x restrained the shuttle effect and accelerated the redox conversion. The MSC/P subset of NiTe2-x-based cell has a cyclability of 637 mAh g(-1) at 4 C over 1800 cycles with a degradation rate of 0.0139% per cycle, high rate performance of 726 mAh g(-1) at 6 C, and a high areal capacity of 8.47 mAh cm(-2) under a sulfur configuration of 10.2 mg cm(-2), and a low electrolyte/sulfur usage ratio of 3.9. This work demonstrates that vacancy-induced doping of heterogeneous atoms enables durable sulfur electrochemistry and can impact future electrocatalytic designs related to various energy-storage applications.