Wide-Temperature Operation of Lithium-Sulfur Batteries Enabled by Multi-Branched Vanadium Nitride Electrocatalyst.

Abstract

High-performance lithium-sulfur (Li-S) batteries that can work normally under harsh conditions have attracted tremendous attention; however, the sluggish reaction kinetics of polysulfide conversions at low temperatures as well as the notorious polysulfide shuttling at high temperatures remain to be resolved. Herein, a multibranched vanadium nitride (MB-VN) electrocatalyst has been designed and deployed for Li-S batteries. Both experimental (time-of-flight secondary ion mass spectroscopy and adsorption tests) and theoretical results verify the strong chemical adsorption capability and high electrocatalytic activity of MB-VN with respect to polysulfides. Moreover, in situ Raman characterization manifests the effective inhibition of polysulfide shuttling by the MB-VN electrocatalyst. Using MB-VN-modified separators, the Li-S batteries deliver an excellent rate capability (707 mAh g-1 at 3.0 C) and great cyclic stability (678 mAh g-1 after 400 cycles at 1.0 C) at room temperature. With 6.0 mg cm-2 of sulfur and a lean electrolyte volume of ∼6 μL mgs-1, Li-S batteries exhibit a high areal capacity of 5.47 mAh cm-2. Even over a wide temperature range (-20 to +60 °C), the Li-S batteries still maintain stable cyclic performance at high current rates. This work demonstrates that metal nitride based electrocatalysts can realize low-/high-temperature-tolerant Li-S batteries.