Towards simulation driven materials design – decoding electrochemical interfaces at molecular level with emerging supercomputing resources

With the first European Exascale supercomputer being currently installed at Forschungszentrum Jülich GmbH, advanced molecular-level simulations of large model systems containing thousands of atoms are foreseen to drive designing of new, well performing and economically viable energy materials. In order to put virtual materials design on equal footing with experiment, the applied computational methods must show accuracy exceeding that offered by standard density functional theory (DFT)-based approaches. An electrochemical interface must also be computed with a sense of realism, including often neglected effect of electrolyte. We will discuss non-standard computational approaches we successfully apply to decode different aspects of electrochemical processes: the effective screening medium reference interaction site model (ESM-RISM) [1-3] and the parameter free DFT+U method with Wannier functions-based projectors [2,6]. We will show the advantage of such novel computational schemes for improved description of electrode-electrolyte systems, including electric double layer [2], electrode materials [4-6] and electrochemical pathways [6]. In particular, we identified severe overestimation of the occupancy of d- and -f orbitals by the widely applied DFT+U method as the origin of inaccurate prediction of electronic structure of various energy materials. This shortcoming was corrected by employing localized Wannier functions as projectors of orbitals occupancy [6,4]. Among others, this improvement revealed never considered before electronic structure of Fe-doped NiOOH, with Fe existing in the low-spin state at Fe contents below its solubility limit in NiOOH. The low-spin solution allows for consistent explanation of measured data on ionic and electronic structure, magnetic and electrochemical properties of this material [6,7].

[1] Nishihara & Otani Phys. Rev. B 96 115429 (2017)

[2] Tesch, Kowalski & Eikerling, J. Phys.: Condens. Matter 33, 444004 (2021)

[3] Kowalski et al. Front. Energy Res. 10, 1096190 (2023)

[4] Ting & Kowalski, Electrochim. Acta 443, 141912 (2023)

[5] He et al., Angew. Chem., Int. Ed. 136, e202315371 (2023)

[6] He et al., Nat, Commun. 14, 3498 (2023)

[7] Friebel et al., J. Am. Chem. Soc. 137, 1305 (2015)