Bifunctional Catalytic Effect of CoSe₂ for Lithium–Sulfur Batteries: Single Doping versus Dual Doping

Abstract

Designing catalysts to accelerate the conversion of soluble lithium polysulfides (LiPSs) is regarded as a promising strategy to inhibit the shuttle effect, improving cathode performance of lithium–sulfur batteries (LSBs). Herein, a bifunctional Ni/Zn dual‐doped CoSe2 is designed to enhance the catalytic effect of CoSe2. Specifically, Ni functions better in catalyzing the conversion of LiPSs into Li2S with shorter CoS bond and longer SS bonds than Zn, while Zn demonstrates a better catalytic effect for Li2S decomposition with reduced Li2S decomposition barrier and elongated LiS bonds than Ni. Those endows Ni/Zn dual‐doped CoSe2 with bifunction in catalyzing conversion reaction of LiPSs and Li2S precipitation as well as the decomposition of Li2S, originating from the modified molecular structure of LiPSs and Li2S. As a result, the sulfur cathode with Ni0.1Zn0.1Co0.8Se2 achieves a rate capability of 681.74 mAh g–1 at 2C, and a cycling stability for 400 cycles with a decay rate of 0.065%. This work provides an effective way to improve catalytic effect of transition metal compounds for advanced LSBs by homogenous dual doping.

Synergism of Flame‐Retardant, Self‐Healing, High‐Conductive and Polar to a Multi‐Functional Binder for Lithium–Sulfur Batteries

“…The Li-S cell with FHCP binder delivers higher specific capacity of 254.9 mAh g -1 than that of Li-S cell with PVDF binder (204.6 mAh g -1 ), demonstrating the effective deposition of Li 2 S caused by FHCP binder. These results clearly confirm that the FHCP binder significantly reduces the overpotential for the initial nucleation of Li 2 S and promotes the precipitation of Li 2 S. [34][35][36] In situ XRD based on Li-S cell with PVDF and FHCP-10 binders was also performed to reveal the evolution mechanism of sulfur species and the redox kinetics during the reaction. As displayed in Figure 5c,d, the diffraction peaks located at 23.14°, 25.92°, 26.82°, and 27.8° are attributed to crystalline α-S 8 (JCPDS 008-0247) at the beginning of discharge.…”

One-Step Electrochemical Synthesis of Co0.8Fe0.2Se@NiF Spheres Enclosed with Nanoparticles and Integrated Porous FeSe2@NiF as Electrode Materials for High-Performance Asymmetric Supercapacitor

“…where ΔV(s) expresses the operating potential window (OPW). 51 while the peaks at ∼778.42 and ∼793.52.4 eV manifest the presence of Co 3+ in the as-prepared electrode material. 48,51 Also, the peaks at ∼784.71 and ∼802.46 eV were the satellite peaks of the Co element.…”

Designing principles of advanced sulfur cathodes toward practical lithium‐sulfur batteries

“…Notably, the bidirectional catalyst was also extended to a single component host. 180,181 With spectroscopic investigations and theoretical calculations, it was revealed that an in-built Janus crystal facet self-mediation was onsite constructed by the exposed B and Zr atoms for selective S/Li 2 S conversion in ZrB 2 . 180 Briefly, the smooth "adsorption-conversion" process could be conducted by coupling with enhanced interfacial charge transfer rate 185 when heterostructure is involved.…”