Strategies to Explore and Develop Reversible Redox Reactions of Li–S in Electrode Architectures Using Silver-Polyoxometalate Clusters

Abstract

Investigations of the Ag (I)-substituted Keggin K[HAgPWO] as a bifunctional Lewis acidic and basic catalyst are reported that explore the stabilization of LiS moieties so that reversible redox reactions in S-based electrodes would be possible. Spectroscopic investigations showed that the LiS-moieties can be strongly adsorbed on the {AgPWO} cluster, where the Ag(I) ion can act as a Lewis acid site to further enhance the adsorption of the S-moieties, and these interactions were investigated and rationalized using DFT. These results were used to construct an electrode for use in a Li-S battery with a very high S utilization of 94%, and a coulometric capacity of 1580 mAh g. This means, as a result of using the AgPOM, both a high active S content, as well as a high areal S mass loading, is achieved in the composite electrode giving a highly stable battery with cycling performance at high rates (1050 and 810 mAh g at 1C and 2C over 100 to 300 cycles, respectively).

Highly Efficient Photoreduction of Low‐Concentration CO2to Syngas by Using a Polyoxometalates/RuIIComposite

“…[24,25] Note that the abundant negative charges of polyoxometalates (POMs) might make them ideal candidates to combine [Ru(bpy) 3 ] 2 + by non-covalentbonds. [26,27] Moreover, the superiority of POMs in terms of their visible-light adsorption, fast and reversible multi-electront ransfer properties, and adjustable energy level structure will contribute to the improvement of CO 2 reduction efficiency. [28] Herein [29][30][31] as well as the redox properties of the molybdophosphoric unit.…”

Polyoxometalates: Tailoring metal oxides in molecular dimension toward energy applications

“…The sulfur dissolution is a critical issue since it severely degrades the device performance. Silver‐based polyoxotungstate K 3 [H 3 AgIPW 11 O 39 ] is found to efficiently improve the cycling performance of lithium‐sulfur battery, ascribed to the coexistence of Lewis acidic and basic sites in the polyoxotungstate available for sulfur adsorption and anchoring (Figure ) . K 3 PW 12 O 40 ‐based polyoxotungstates have been employed in the lithium‐sulfur battery cathode .…”

“…Schematic view of the proposed atomic representation of the interactions between polyoxometalate and the sulfur species by leveraging the Lewis acidic and basic sites in the polyoxometalate to anchoring Li 2 S n moieties in lithium‐sulfur batteries. Reproduced with permission from Ye et al Copyright ACS (2018)…”

“…258 The F I G U R E 7 Schematic view of the proposed atomic representation of the interactions between polyoxometalate and the sulfur species by leveraging the Lewis acidic and basic sites in the polyoxometalate to anchoring Li 2 S n moieties in lithiumsulfur batteries. Reproduced with permission from Ye et al 226 Copyright ACS (2018) 226 [Colour figure can be viewed at wileyonlinelibrary.com] chemisorption of light-harvesting molybdenum cluster on TiO 2 and NiO could lead to electron/hole transfer either from the cluster to the substrate or the reverse direction. 259 The interfacial charge transfer is determined to be efficient between the Dawson-type polyoxomolybdate P 2 Mo 18 and phthalocyanine, contributing to the desired dissociation of excitons and decent photovoltaic effects.…”

A microporous carbon derived from metal‐organic frameworks for long‐life lithium sulfur batteries

“…6,7 However, the insulativity of active sulfur and discharge product (Li 2 S), the solubility of discharge intermediates (Li 2 S x , 4 ≤ x < 8) into organic electrolyte, and the "shuttle effect" by diffusing polysulfides into the negative electrode to produce parasitic reactions, cause serious active sulfur loss from cathode and cycle deterioration of the batteries, greatly hindering the Li-S batteries' development and commercialization. [8][9][10] In order to address these issues, significant progresses have been made in the last decade by immobilizing sulfur within various host materials to form sulfur-based composites, like sulfur/carbon composites, [11][12][13][14][15][16][17][18] sulfur/metallic compounds composites, [19][20][21][22][23][24][25][26] and sulfur/polymer composites. [27][28][29][30][31] It is noted that among the various host materials, microporous carbon is quite distinctive, because esterbased electrolyte was usually used for sulfur/microporous carbon (S/MC) composites based Li-S batteries, while ether-based electrolyte was commonly used in other composites based Li-S battery systems.…”