Altering Local Chemistry of Single‐Atom Coordination Boosts Bidirectional Polysulfide Conversion of Li–S Batteries

Abstract

Single-atom catalysts affording multifarious typed metal centers and varied coordination numbers are extensively employed in Li−S realm to promote redox kinetics. Nevertheless, the modulation of coordination environment pertaining to local atomic composition to dictate the catalytic efficiency toward sulfur electrochemistry, has remains meaningful yet unexplored thus far. In this contribution, a new type of single-atomic iron mediator with a designed FeN 3 P 1 coordination structure is reported to boost bidirectional polysulfide conversion in comparison with FeN 4 counterpart. Theoretical calculations imply that the substitution by one P atom at the first-coordination shell of Fe center will be beneficial to strengthen adsorption toward sulfur species and reduce energy barrier for Li 2 S decomposition. The bidirectional electrocatalytic behavior for polysulfide conversion via FeN 3 P 1 mediator is confirmed by electrokinetic analysis. Consequently, the constructed Li−S battery achieves elongated lifespan with a capacity decay of 0.04% per cycle at 1.0 C and exhibits considerable capacity release of 6.2 mAh cm −2 even under a sulfur loading of 6.4 mg cm −2 . This strategy of local composition engineering offers a vivid example in probing the correlation between the definitive structure of single atoms and their catalytic performance in Li−S chemistry.

Oxygen Vacancies in Bismuth Tantalum Oxide to Anchor Polysulfide and Accelerate the Sulfur Evolution Reaction in Lithium–Sulfur Batteries

“…The different electrodes were prepared and measured to explore the application potential for Li-S batteries. Figure 6 a shows the CV curves of three electrodes in a voltage range of 1.7 to 2.8 V at a scan rate of 0.1 mV s −1 [ 33 ]. It was found that the S/C@Bi 3 TaO 7−x cathode displays two typical cathodic peaks at 2.03 V (peak i) and 2.35 V (peak ii), which correspond to the reduction of sulfur into high-order soluble LiPSs and the subsequent conversion of the LiPSs to insoluble Li 2 S 2 /Li 2 S. The anodic peaks at 2.38 V (peak iii) are associated with reverse oxidation conversion from Li 2 S to LiPSs and finally to sulfur.…”

Coordination Manipulation of Single Atom Catalysts for Lithium‐Sulfur Batteries: Advances and Prospects

“…P atoms are also employed to assist the realization of such dual coordination toward efficient electrochemical reaction. Huang et al [79] . devised an efficient polymerization‐carbonization strategy to fabricate N, P coordinated Fe single atoms for Li−S batteries.…”

“…In another work, Wang et al [78] P atoms are also employed to assist the realization of such dual coordination toward efficient electrochemical reaction. Huang et al [79] devised an efficient polymerization-carboniza-tion strategy to fabricate N, P coordinated Fe single atoms for LiÀ S batteries. Figure 3a and b demonstrate that N and P atoms are successfully coordinated with single metal Fe moieties.…”

Rationalizing Functionalized MXenes as Effective Anchor Materials for Lithium–Sulfur Batteries via First-Principles Calculations

“…On the basis of this equation, we classified these materials into three types: strong adsorption ( E ad > 2.5 eV), moderate adsorption (1 eV < E ad < 2.5 eV), and weak adsorption ( E ad < 1 eV). To suppress the competitive interaction between long chain Li 2 S x ( x = 4, 6, or 8) and solvent molecules, , an efficient anchor material should bind long chain Li 2 S x more firmly than do solvent molecules DME and DOL to avoid degradation of cell performance. However, once the binding energy exceeds the cleavage energy of the Li–S bond, the LiPSs would decompose and hinder the effective utilization of S. , Therefore, a moderate binding strength for polysulfides is a prerequisite for designing ideal anchor materials.…”