Theoretical analysis of doped graphene as cathode catalyst in Li-O2 and Na-O2 batteries -- the impact of the computational scheme

TL;DR

This paper introduces a new computational scheme combining high-level CCSD(T) and DFT methods to model reactions in Li-O2 and Na-O2 batteries, highlighting the importance of dispersion corrections and identifying B-doped graphene as an effective catalyst.

Contribution

A novel hybrid computational approach for modeling M-O2 cell reactions, integrating high-level and DFT calculations, with insights into catalyst design and the role of dispersion interactions.

Findings

B-doped graphene is the most effective catalyst among those considered.

Including dispersion corrections significantly affects predicted potentials.

Guidelines for designing improved ORR catalysts for M-O2 batteries.

Abstract

Understanding the reactions in M-O2 cells (M = Li or Na) is of great importance for further advancement of this promising technology. Computational modelling can be helpful along this way, but an adequate approach is needed to model such complex systems. We propose a new scheme for modelling processes in M-O2 cells, where reference energies are obtained from high-level theory, CCSD(T), while the interactions of reaction intermediates with catalyst surfaces are extracted from computationally less expensive DFT. The approach is demonstrated for the case of graphene-based surfaces as model catalysts in Li-O2 and Na-O2 cells using the minimum viable mechanism. B-doped graphene was identified as the best catalyst among considered surfaces, while pristine graphene performs poorly. Moreover, we show that the inclusion of dispersion corrections for DFT has a significant impact on calculated discharge and charge potentials and suggests that long-range dispersion interactions should always be considered when graphene-based materials are modelled as electrocatalysts. Finally, we offer general guidelines for designing new ORR catalysts for M-O2 cells in terms of the optimization of the interactions of catalyst surface with reaction intermediates.