Cooperative Catalysis of Polysulfides in Lithium‐Sulfur Batteries through Adsorption Competition by Tuning Cationic Geometric Configuration of Dual‐active Sites in Spinel Oxides

Abstract

Fundamentally understanding the structureproperty relationship is critical to design advanced electrocatalysts for lithium-sulfur (LiÀ S) batteries, which remains a formidable challenge. Herein, by manipulating the regulable cations in spinel oxides, their geometrical-site-dependent catalytic activity for sulfur redox is investigated. Experimental and theoretical analyses validate that the modulation essence of cooperative catalysis of lithium polysulfides (LiPSs) is dominated by LiPSs adsorption competition between Co 3 + tetrahedral (Td) and Mn 3 + octahedral (Oh) sites on Mn 3 + Oh À OÀ Co 3 + Td backbones. Specifically, high-spin Co 3 + Td with stronger CoÀ S covalency anchors LiPSs persistently, while electron delocalized Mn 3 + Oh with adsorptive orbital (d z 2 ) functions better in catalyzing specialized LiPSs conversion. This work inaugurates a universal strategy for sculpting geometrical configuration to achieve charge, spin, and orbital topological regulation in electrocatalysts for LiÀ S batteries.

Field‐assisted electrocatalysts spark sulfur redox kinetics: From fundamentals to applications

“…[109][110][111][112] Meanwhile, our group took full advantage of spinel-type electrocatalysts with tetrahedral (Td) and octahedral (Oh) configuration simultaneously, plowing a universal concept of geometrical-site-dependent electrocatalytic activity to enrich the scope of applications for spin manipulation (Figure 4D). [103] Once Mn 3+ is incorporated into Oh sites in antiferromagnetic Co Oh -O-Co Td backbones, the originally located Co 3+ Oh is driven into Td sites to construct ferromagnetic Mn 3+ Oh -O-Co 3+ Td backbones instead. Ridding of the localized electronic structure brought by low-spin Co 3+ Oh in Co Oh -O-Co Td backbones, the high-spin Co 3+ Td not only delocalizes the electrons to facilitate oriented electron hopping but also strengthens LiPSs adsorption via the spin pinning effect.…”

“…Reproduced with permission. [103] Copyright 2022, Wiley-VCH. achieve internal heating paves another way to accelerate LiPSs conversion.…”

“…[177][178][179] Except for the d-band model, the strain effect in metal-based electrocatalysts can be explained by crystal field theory as well (Figure 7B). [93,103,111] Beneficial from the versatile strategies (e.g., external force, defect, and lattice mismatch) for the introduction of strain in electrocatalysts, which is in response to flexible manipulation of tensile/ compressive strain, strain engineering flourishes in the exploration of SF-assisted electrocatalysts in Li-S batteries. [180][181][182][183][184][185][186]…”

“…[188][189][190] It is worth noting that although the d-band center descriptor has been successfully applied in metal/alloy systems, its inadaptability for some electrocatalysts in which p orbitals/nonbonding interaction dominate should attract sufficient attention, such as metal oxides or metal-free catalysts. [103,188,[191][192][193][194][195][196]…”

“…[197] To fully consider the role of ligands in metal oxides, structural descriptors can relate the geometry of electrocatalytic active sites to their properties. [103,117,175,193] Originating from the geometrical-site-dependent reactivity, Wang and coworkers offer an intriguing concept for surface electronic structure modulation by transforming the crystalline counterpart (c-CoO nanosheets) with CoO 6 octahedrons into amorphous a-CoO nanosheets with partial distorted or truncated CoO 4 tetrahedrons (Figure 7G). [111] In conjunction with theoretical calculations and X-ray absorption spectroscopy analysis, it is elucidated that the amorphization-induced reformed crystal fields makes more electrons occupy a high energy level and results in more electrons transferring to Li 2 S 4 , in response to the high binding energy with LiPSs for favorable adsorption.…”