Organic electrode materials are becoming increasingly attractive owing to their unprecedented low cost, safety, tunable voltages and most importantly, environmental friendliness. Quinone derivatives have gained increased attention in energy storage and conversion applications. Crystalline quinones in particular, have seen increased use in rechargeable batteries as electrode material, mainly due to their tunable voltages and high capacities. The mechanism of charge transport through crystalline quinones in different electrolytic media is however not well understood. In highly acidic electrolytes like concentrated sulfuric acid, quinone molecules store charge in the form of electrons and protons by forming hydroquinones. In order to understand the charge storage/transport mechanism which involves proton-coupled electron transfer, we have carried out benchmark studies on the density functional tight binding (DFTB3) method with the 3OB parameter set for the energetics of proton/electron transfer involving quinones, electronic properties of crystalline quinones and prediction of the crystal structure of quinones. Being semi-empirical in nature, the DFTB3 method provides a good balance between computational accuracy and efficiency for the study of long-time scale charge transport processes in crystalline systems. The insights gained from our study provide guidelines for further development of the DFTB3 method and will lead to new avenues for concerted computational/experimental design efforts aimed at better quinone-based electrode materials.

Benchmarking the density functional tight binding (DFTB3) method for charge transport in quinone-based electrode materials for batteries

ACS Spring Meeting 2021

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