Manipulating the Spin State of Fe Sites via Fe–O–Si Bridge Bonds for Enhanced Polysulfide Redox Kinetics in the Li–S Battery

Abstract

Transition metals with 3d unoccupied orbitals have superior catalytic activity, but inherent high spin suppresses their adsorption capability, leading to sluggish polysulfide conversion kinetics for Li−S batteries. Herein, we provide Fe−O−Si bridge bonds to manipulate e g filling and induce a high-to-medium spin transition of Fe 3+ sites, which enhances polysulfide adsorption and facilitates sulfur redox reaction kinetics. The resultant cathodes exhibit outstanding performances under high sulfur loading, which can deliver a high battery specific energy of 1061 mA h•g −1 even after 100 cycles in Li−S pouch batteries. This work provides new insights into the kinetic and multi-step conversion mechanism of the sulfur redox reaction process, helping in the understanding and design of spin-dependent catalysts.

How advances in theoretical chemistry meet industrial expectations in electrocatalysts for water splitting

“…The inclusion of quantum correlations in catalytic design is essential if we consider that novel predictors mainly based on spin-potentials from open-shell orbitals have already contributed to identify magnetic material combinations that exhibit OER activities at least one order of magnitude larger than that of IrO 2 (usually identified as the state-of-the-art in industrial OER). 11,97–99 These advances will reduce the gap between fundamental research and applied technology for clean energy, 15,43,100–103 and we are moving towards a ±0.1 V error in the computational accuracy of reaction pathways when comparing and screening active catalysts. Likewise, accurate computational chemistry can also deliver improvements in noble metal based catalysts utilised in PEM_EL, by maximising the efficiency and concomitantly lowering the Pt content, via orbital engineering of magnetic elements, as in the case of Pt 3 Co. 52,53…”

“…The inclusion of quantum correlations in catalytic design is essential if we consider that novel predictors mainly based on spin-potentials from open-shell orbitals have already contributed to identify magnetic material combinations that exhibit OER activities at least one order of magnitude larger than that of IrO 2 (usually identified as the state-of-the-art in industrial OER). 11,97-99 These advances will reduce the gap between fundamental research and applied technology for clean energy, 15,43,[100][101][102][103] and we are moving towards a ±0.1 V error in the computational accuracy of reaction pathways when comparing and screening active catalysts. Likewise, accurate computational chemistry can also deliver improvements in noble metal based catalysts utilised in PEM_EL, by maximising the efficiency and concomitantly lowering the Pt content, via orbital engineering of magnetic elements, as in the case of Pt 3 Co. 52,53 Because there is no clear indication at the present time of which WEL technology will become dominant in the near future (although PEM_EL might be the technology of choice when coupled to highly volatile renewables) 63 specific developments and optimisation methods should not be limited to a single technology, but they should be extended to all six possible (different) catalytic interphases (i.e., three set ups previously seen for HER and OER).…”

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

“…More recently, versatile spin electrocatalysis has been in full swing and helped integrate a comprehensive understanding of sulfur redox. [ 109–112 ]…”

“…More recently, versatile spin electrocatalysis has been in full swing and helped integrate a comprehensive understanding of sulfur redox. [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.…”

Regulating the Spin State Configuration in Bimetallic Phosphorus Trisulfides for Promoting Sulfur Redox Kinetics

“…It is widely accepted that the spin state configuration of 3d transition metals can be a critical catalytic descriptor in electrocatalytic and photocatalytic systems. − This is because spin state configuration is an index of the overall structure, energy, and redox profile of the catalyst, which determines the occupancy of e g orbital and impacts key reaction steps. ,, The spin state of transition-metal atom can be rationally modulated by the ligand field, magnetic field, or stress field. ,− Zhang et al have found that the Co atom experiences a transition from low-spin to high-spin states, generating more unpaired electrons under an external magnetic field . Such spin delocalization increases the charge transfer and orbital interactions between the sulfur species and the catalyst, thus lowering the energy barrier and increasing the reaction kinetics.…”