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JACS, Xiamen University: Cathode Material Of Li-sulfur Battery Based On Cluster-like Molecules

- Dec 17, 2018 -

At present, lithium ion batteries are widely used in all kinds of portable electronic equipment in the electric car, but with the continuous development of these devices, lithium-ion batteries gradually cannot satisfy the development of the society needs in order to further development of the application prospect of lithium ion batteries, all kinds of system of battery to get the attention of the researchers, lithium sulfur batteries are increasingly brought to the attention of the people as sulfur lithium sulfur batteries battery anode materials, lithium metal as the cathode material of a lithium battery elemental sulfur is abundant in the earth, possesses the characteristics of cheap environmentally friendlyLithium sulfur battery with sulfur as the positive electrode material has a higher theoretical specific capacity of material and theoretical specific energy of battery, reaching 1675m Ah/g and 2600Wh/kg respectively, which is almost 10 times of the theoretical capacity of traditional positive electrode materials, such as transition metal oxide phosphate material.In addition, the sulfur also has the advantages of low cost environment friendly, is a very promising lithium battery.

Recently, xiamen university, college of chemistry and chemical engineering professor dong group and the university of Glasgow Leroy professor Cronin team made new progress in lithium battery research, relevant results to Strategies to Explore and Develop Reversible Redox Reactions of Li - S Electrode in ArchitecturesClusters using silver-polyoxometalate Clusters were published in JACS (DOI:10.1021 / jacs. 8 b0041) prior to that, professor dong group of lithium sulfur batteries sulfur composite cathode material for the research of the system in the early by in situ Raman technology combined with the theoretical calculation to explore the reaction mechanism of lithium sulfur batteries, confirmed to the load of s-based body material doped nitrogen modification can be complete with elemental sulfur as the positive active material charge and discharge cycle (Chem. Mater., 2015, 27, 2048?2055);Subsequently, the synergistic catalytic effect of co-n was successfully applied to the REDOX process of S for the first time, and the multi-functional and bicatalytic concepts were proposed (EES, 2016, 9, 1998-2004).On the basis of improving the sulfur content of composite anode materials, the research group prepared non-carbon mesoporous Co4N microspheres for the first time to achieve up to 95% sulfur loading capacity (ACS Nano, 2017, 11, 6031-6039).

 POMs is a kind of molecular cluster material with nano-size and the characteristics of reversible multi-electron reaction.Is referred to as the electronic image of the sponge, because it can be reversible storage of ions and electrons, which has become a higher specific capacity of energy storage materials, the feasibility of the research for the first time in clusters of polymetallic oxygen sour salt lithium battery cathode substrate material, the material (K3 [H3AgIPW11O39]) with lewis acid and lewis base in the meantime, thus has the function of double loci adsorption polysulphide can realize effective control of sulphur electrochemical reaction processExperimental results and DFT theoretical calculations show that Ag(I) hetero-metal ions can regulate the adsorption of polysulphides and end-point oxygen atoms to lithium ions in the framework structure of polyanions, and that lithium sulfur batteries prepared with Ag(I) as the framework material exhibit excellent electrochemical properties.

1

Schematic diagram of Li2S produced by the lithium sulfur battery system absorbed by POMs

2

The optimized structure of adsorption gibbs free energy difference ( Gads) and Li2Sn (n = 8, 6, 4) combined with PW12O40 and K3 [H3AgIPW11O39] clusters was calculated

3

Raman spectra and optical photographs of A, B, C, D and E

A: blank solution of DME/DOXL;

B: DME/DOXL solution of Li2S6;

C: DME/DOXL solution of Li2S6 and superconductive carbon black;

D: DME/DOXL solution of Li2S6 and PW12O40;

E: DME/DOXL solution of Li2S6 and AgIPW11O39.

4

Electrochemical characterization of AgPW11 / S electrode

A) : discharge - charging curve of AgPW11 / S electrode at different rates;

B) battery cycle test of AgPW11 / S, K3PW12O40 / S and super-conductive carbon black/S electrode li-sulfur battery at a rate of 1C;

C) : AgPW11 / S electrode and super-conductive carbon black/S long battery cycle at a rate of 2C.