MOF-Derived Hollow Carbon Supported Nickel-Cobalt Alloy Catalysts Driving Fast Polysulfide Conversion for Lithium-Sulfur Batteries

Abstract

Transition-metal compounds can be used as electrocatalysts to expedite polysulfide conversion effectively in lithiumsulfur batteries. However, insufficient conductivity and tedious preparation process still limit their practical applications. In this work, NiCo alloy nanoparticles embedded in hollow carbon spheres (NiCo@HCS) are fabricated via a facile, template-free strategy from the NiCo-metal−organic framework (MOF) precursor and used as electrocatalysts for separator modification. NiCo@HCS can not only improve the adsorption capacity of polysulfides by d-band deviation to the Fermi level but also reduce the energy barrier in the process of catalytic polysulfide conversion. Due to favorable three-dimensional (3-D) morphology, improved adsorption, and promoted kinetics of NiCo@HCS, the battery containing the NiCo@HCS-modified separator gives a starting capacity of 1377 mAh g −1 at 0.2C, which is retained by 72% over 500 charge/discharge operations at 1.0C current density. Moreover, the battery's start capacity reaches 1180 mAh g −1 (5.9 mAh cm −2 ) with a high sulfur content of 5.0 mg cm −1 at 0.2C.

Oxygen-Defect-Rich B-ZnCo2O4-x Nanocatalyst for Efficient Conversion Kinetics of Lithium–Sulfur Batteries

“…This indicates that B-ZnCo 2 O 4‑x has a strong chemisorption effect toward soluble LiPSs. Moreover, UV–vis spectroscopy confirms that the characteristic absorption peak intensity of Li 2 S 6 between 260 and 290 nm was the lowest for the solution soaking B-ZnCo 2 O 4‑x . After the adsorption of Li 2 S 6 , the main peaks of Zn 2p and Co 2p moved to a lower binding energy (Figure c,d), which was attributed to the transfer of electrons from Li 2 S 6 to metal atoms, indicating that Zn and Co had a strong chemical adsorption effect on soluble polysulfides .…”

Vanadium-doped graphitic carbon nitride for high performance lithium–sulfur batteries

“…To study the catalytic effect on sulfur and polysulfide conversion, 17,18 batteries with different catalyst-modified separators were assembled. Fig.…”