Electron transfer in TEMPO-based organic radical batteries governed by electronic coupling

Abstract

This research elucidates the intricate nature of electronic coupling values for the redox-active (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) often used in organic radical batteries (ORBs), employing a combination of classical molecular dynamics (MD) and multiconfigurational simulations, i.e., the Complete active space self-consistent field (CASSCF) methods. Our study reveals the significant influence of both distance and relative orientation of the redox pairs (TEMPO and TEMPO+) on the electronic coupling. Thus, our simulations suggest that the electronic communication between the redox centres and this the charge mobility heavily depends on both - TEMPO's intrinsic molecular properties as well as the supramolecular environment in the electrode material. Additionally, our study highlights the limitations of the frontier molecular orbital (FMO) method in this context. Our findings underscore the significance of integrating molecular dynamics and advanced electronic structure methods, like CASSCF, to garner a holistic understanding of electronic coupling for charge transfer reactions in organic electrodes.