Electrocatalytic MOF‐Carbon Bridged Network Accelerates Li⁺‐Solvents Desolvation for High Li⁺ Diffusion toward Rapid Sulfur Redox Kinetics

Abstract

Lithium-sulfur batteries are famous for high energy density but prevented by shuttling effect and sluggish electrochemical conversion kinetics due to the high energy barriers of Li + transport across the electrode/electrolyte interface. Herein, the Li + -solvents dissociation kinetics is catalyzed and stimulated by designing a carbon bridged metal-organic framework (MOF@CC), aimed at realizing increased bare Li + transport for the rapid conversion kinetics of sulfur species. Theoretical simulations and spectroscopic results demonstrate that the bridged MOF@CC well grants a special transport channel for accelerating Li + benefited from aggregated anion/cation clusters. Moreover, the CN bridge between -NH 2 ligand in MOF and carbon shell enhances electron exchange, and thus promotes polysulfide catalytic efficiency and hinder polysulfide aggregation and accumulation. With the MOF@CC-modified separators, the assembled Li/S batteries deliver a reversible capability of 1063 mAh g -1 at 0.5 C, a capacity retention of 88% after 100 cycles, and a highrate performance of 765 mAh g -1 at 5 C. Moreover, the large areal pouch cell with 100 µm Li foil and lean electrolyte is capable of stabilizing 855 mAh g -1 after 70 cycles. These results well demonstrate the efficiency of catalyzing desolvation for fast Li+ transport kinetics and the conversion of polysulfides.

Delocalized Isoelectronic Heterostructured FeCoOxSy Catalysts with Tunable Electron Density for Accelerated Sulfur Redox Kinetics in Li‐S batteries

“…As summarized in Figure 3g, the Li 2 S precipitation capacity on the various DIHC shows a volcanic tendency, which is consistent with above results. For example, among them, the cell based on FeCoO 1.5 S 1.0 /NC DIHC has the earliest nucleation response time (765 s) and highest peak current (0.37 mA), showing more polysulfides were catalytically converted into Li 2 S. [46] Furthermore, the reversibility of Li 2 S has the decisive role in the later capacity and lifespan. In the Li 2 S dissolution experiment, the Li 2 S potentiostatic charge curve and capacity is recorded and summarized (Figure S20a-f…”

Delocalized Isoelectronic Heterostructured FeCoOxSy Catalysts with Tunable Electron Density for Accelerated Sulfur Redox Kinetics in Li‐S batteries

“…As summarized in Figure 3g, the Li 2 S precipitation capacity on the various DIHC shows a volcanic tendency, which is consistent with above results. For example, among them, the cell based on FeCoO 1.5 S 1.0 /NC DIHC has the earliest nucleation response time (765 s) and highest peak current (0.37 mA), showing more polysulfides were catalytically converted into Li 2 S. [46] Furthermore, the reversibility of Li 2 S has the decisive role in the later capacity and lifespan. In the Li 2 S dissolution experiment, the Li 2 S potentiostatic charge curve and capacity is recorded and summarized (Figure S20a-f DIHCs.…”

Accelerated Li+ Desolvation for Diffusion Booster Enabling Low‐Temperature Sulfur Redox Kinetics via Electrocatalytic Carbon‐Grazfted‐CoP Porous Nanosheets

“…For example, our group indicated that a MOF-Carbon bridged catalytic network is beneficial for promoting the formation of anion-involved Li + solvation structure, catalyzing the Li +solvents dissociation kinetics and providing a fast channel for Li + transport. [13] As pointed above, owing to the instability of MOFs and the lack of active sites, the strategy might fail in the low-temperature environments, limiting the dissociation of solvent molecules from the solvation sheath of cations, which is detrimental to the catalytic efficiency of obtaining free Li ion to propel polysulfide conversions. Therefore, designing a stable yet highly catalytic layer to accelerate the dissociation of Li + -solvents in low-temperature environment is of great significance to generate more free Li ions to facilitate sulfur redox reaction kinetics.…”