Conductive and Catalytic VTe₂@MgO Heterostructure as Effective Polysulfide Promotor for Lithium–Sulfur Batteries

Abstract

Lithium–sulfur (Li–S) batteries are recognized as one of the most promising energy storage systems due to the high energy density and cost effectiveness. However, their practical implementation has still been handicapped due to notorious lithium polysulfide (LiPS) shuttle and depressed sulfur redox kinetics. It is therefore desirable to exploit key mediators synergizing electrical conductivity and electrocatalytic activity for the cathode. Herein, we report the employment of atmospheric pressure chemical vapor deposition to harness the efficient and controllable synthesis of metallic VTe2 over particulated MgO substrates, which has scarcely been demonstrated by conventional wet-chemical synthetic routes thus far. The thus-derived VTe2@MgO heterostructure as an efficient promotor enables effective regulation of LiPSs with respect to polysulfide capture/conversion and Li2S decomposition. As a result, a S/VTe2@MgO cathode with a sulfur loading of 1.6 mg cm–2 harvests long-term cyclability with a negligible capacity decay of 0.055% per cycle over 1000 cycles at 1.0 C. Even at a sulfur loading of 6.9 mg cm–2, the cathode still delivers electrochemical performances that can rival the state-of-the-art high-loading counterparts. Our work might offer a feasible solution for developing heterostructured promotors with multifunctionality and electrocatalytic activity for high-performance Li–S batteries.

Conductive FeOOH as Multifunctional Interlayer for Superior Lithium–Sulfur Batteries

“…And the slope of curves can be used to evaluate the Li‐ion diffusion rate according to classical Randles–Sevcik equation ( D 0.5 ∝ I p /ν 0.5 , D is the Li ion diffusion coefficient, I p is the peak current, and ν is the scan rate). [ 33,34 ] Clearly, the slope of oxide peak (Figure 6d) and reduction peak (Figure 6e,f) of LSBs with FeOOH/PP separator are both relatively larger than SP/PP and pristine PP separator, implying the fast diffusion rate of LiPSs for subquent electrocatalysis process induced by FeOOH. Morever, with the introduction of Super P (SP/PP), the Li ion diffusion efficiency is decreased compared to pristine PP seperator.…”

Emerging Catalysts to Promote Kinetics of Lithium–Sulfur Batteries

“…Thus far, key efforts have been devoted to designing reasonable heterostructure system to realize the synergy of catalysis and adsorption, such as TiO 2 –TiN, VO 2 –VN, MoN–VN, VTe 2 @MgO, WS 2 –WO 3 , TiO 2 –TiN, V 2 O 3 /V 8 C 7 , NiO–NiCo 2 O 4 , SnS 2 /SnO 2 , and ZnS–FeS, etc. [ 29,62,168–174 ] In this section, we focus on the effective construction strategies for heterostructure with respect to simultaneously improved adsorption and catalysis throughout catalytic materials design.…”

“…Up to now, numerous explorations have paved the way to rationally designing and developing some polar catalytic materials including metal, metal‐free hosts, metal oxides, metal sulfides, metal nitrides, metal carbides and composite heterostructures with high catalytic activity for LiPSs redox. [ 23–32 ] In the specific implementation, these catalytic materials are mainly used as cathode sulfur hosts, separator modification and cathode additives for adjusting the adsorption–diffusion–conversion of LiPSs to a certain degree. Due to the extensive and far‐reaching study of these materials in Li–S system, we can refer to them as “traditional catalytic materials.” Many peer reviews have summarized recent progress of these materials in Li–S system and proposed impactful and insightful perspectives.…”

Catalyzing the polysulfide conversion for promoting lithium sulfur battery performances: A review

“…Besides, the highly conductive and polar bimetallic merit of NiCo 2 -Se 4 benefits the rapid electron transfer and catalytic enhancement of the electrochemical reaction kinetics. Recently, vanadium telluride (VTe 2 ), another member of metal dichalcogenides, has been substantiated as an efficient catalyst for sulfur reaction kinetics [100]. With the cooperation of MgO core, the thus-designed VTe 2 @MgO heterostructured composites could adsorb LiPSs throughout the strong chemical interaction, and provide smooth electron transport pathway due to the metallic VTe 2 shells, thereby facilitate the polysulfides conversion and subsequent Li 2 S deposition.…”