A Design of high potential organic cathodes for Lithium – ion batteries, using first- principle DFT modelling approach.: Design of high potential organic cathodes for Lithium – ion batteries, using first- principle DFT modelling approach.

Abstract

The Li-ion battery technology is very efficient because of the significant energy and power density [1]. While manufacturing the commercial prototype cathode materials, the 3d transition metals like Co, Ni, Cr, Mn, and Fe are extensively used. However, they usually suffer from high production costs due to less abundant raw materials [2-3]. Apart from the commercial cathodes, toxic metals like Co and Ni pollute the earth surface and need to be recycled. Alternatively, many research groups focus on developing cathode materials consisting of earth-abundant elements viz., C, H, S, N, O. The organic-based materials are promising candidates for the advancement of Lithium-ion/sodium – ion/dual- ion battery technologies [4-5]. Because low-cost, nontoxic nature of organic compounds makes them promising alternatives to their inorganic counterparts [6]. Among the many examples of organic compounds, carbonyl group-containing compounds are most popularly used for rechargeable batteries because they have a high theoretical capacity with good redox chemistry. Each carbonyl group can except electron reversibly favours stable charge/discharge. However, they a few challenges for commercial applications, namely, high solubility in organic solvents, multiple synthesis steps involved during the synthesis process, low electronic conductivity due to wide intrinsic bandgap and relatively low redox potentials (lower than the 3V). Many research groups are working to resolve the obstacles mentioned above [7-8].

In the present study, our emphasis is on pyrenetetrones compounds as they possess high redox potential due to the multi redox centres of carbonyl groups present in the structure [9]. DFT methods are applied to investigate the redox properties of substituted pyrenetetrone compounds, such as 4,5,9,10-tetroane (PT), 2,7- difluoropyrene-4,5,9,10-tetroane (PT-2F), 2,7-trifluoropyrene-4,5,9,10-tetroane (PT-2CF3), 2,7- diacylchloropyrene-4,5,9,10-tetroane (PT-2AcCl), 2,7- dicyanopyrene-4,5,9,10-tetroane (PT-2CN), 2,7- dinitropyrene-4,5,9,10-tetroane (PT-2NO₂), 2,7- diaminopyrene-4,5,9,10-tetroane (PT-2NH₂) in Figure (A). the computed redox properties are calculated based on the nature of the substituents like EWG (electron withdrawing) and EDG (electron-donating group) present on the pyrene ring. the electronic properties are affecting with addition of any substituent to the core molecules, first, we find out the higher electron acceptability character containing pyrenetetrone molecules and performed a lithiation process. This investigation reveals EWG shows higher redox potentials than the EDG. Among all the examples, PT-2CN shows higher redox potential ~ 3.6V Li/Li⁺ with two lithium binding, apart from that PT-2CN maintain a stable voltage until four lithiums binding to the structure. Also, we calculated the theoretical charge capacities of the highest redox potential exhibiting molecules. Finally, we found that PT-2CN highest redox potential and theoretical charge capacities. It can store four lithiums per molecule, showing an exceptionally high charge capacity (343 mAh/g). the complete finding of my research work will be presented.