Atomistic view on structures and processes in electrochemical energy conversion and storage from first principles

Axel Groß
Institute of Theoretical Chemistry, Ulm University, 89069 Ulm/Germany
Helmholtz Institute Ulm (HIU) Electrochemical Energy Storage, 89081 Ulm/Germany

Room B10, White City Campus, Wood Lane – Imperial College London and hybrid

Abstract: Electrochemical energy storage and conversion is of critical importance for our future sustainable, environmentally friendly energy supply. Due to this importance, significant research and development efforts are undertaken worldwide in order to improve our understanding of electrochemical processes at electrolyte/electrode interfaces and to develop more efficient electrochemical devices such as electrocatalysts, fuel cells and batteries. Many concepts still used today in electrochemistry are rooted in insightful thermodynamical concepts developed more than one century ago. Thermodynamics is a field that deals with measurable macroscopic physical quantities, but a full understanding of the nature of these quantities requires a connection to microscopic properties via statistical mechanics. In this talk, I will try to illustrate this connection using recent examples of first-principles studies addressing structures and processes in electrocatalysis and batteries on the atomic level.

The atomistic modelling of electrochemical interfaces between liquid electrolytes and electrodes requires to perform appropriate statistical averages to capture the liquid nature of electrolytes. Fortunately, due to the increase in computer power and the development of more efficient first-principles codes, it has nowadays become possible to perform these averages based on ab initio molecular dynamics simulations. I will address the recent progress in our understanding of the interfaces between aqueous electrolytes and metal electrodes [1], but also present examples how stable adsorbate structures can be derived based on grand-canonical concepts [2].

In the second part, I will focus on structures and processes in batteries from an atomistic perspective. I will particularly use the concept of descriptors to relate materials properties to desired or undesired functional properties of these materials. It will be shown that dendrite growth in batteries might be related to the height of metal self-diffusion barriers [3]. Furthermore, I will show that the competition between coordination and bond length that governs the ionic site preference in spinel compounds upon trigonal distortions can only be understood by also taking covalent interactions into account [4]. This has led to the identification of a descriptor for the ion mobility in crystalline battery electrodes and solid electrolytes [5], that combines ion radii, oxidations states and the difference in the electronegativity of the migrating cations and the anions of the host lattice, resulting in linear scaling relations between the height of the migration barrier and this descriptor.

Literature:

[1] Axel Groß and Sung Sakong, Chem. Rev. 2022, DOI: 10.1021/acs.chemrev.1c00679
[2] Axel Groß, Curr. Opin. Electrochem. 2021, 27, 100684.
[3] M. Jäckle, K. Helmbrecht, M. Smits, D. Stottmeister, A. Groß, Energy Environ. Sci. 2018, 11, 3400.
[4] M. Sotoudeh, M. Dillenz, A. Groß, Adv. Energy Sustainability Res. 2021, 2, 2100113.
[5] Mohsen Sotoudeh and Axel Groß, JACS Au 2022, 2, 463–471

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