Looking below the surface: Revealing Interfacial Reactions for Sustainable Electrochemical Technologies

One of the greatest challenges of our time is to rapidly transition towards a low-carbon economy in order to limit the extent of climate change. The UK government's pledge to achieve net-zero emissions by 2050 will require decarburisation across all sectors, and thus the development of new technologies to ensure secure, reliable energy supplies are maintained. The expansion of solar and wind power has resulted in renewable energy costs that are competitive with or even undercut fossil fuel alternatives. However, further transition to renewable energy sources will require major changes in how we convert, store and use energy, including measures to deal with their intermittency and increased electrification. Electrochemical energy storage and conversion technologies will be central to this decarburisation effort, offering potential improvements in efficiency compared to current thermochemical processes (e.g. combustion). However, realising these efficiencies along with the performance needed for large-scale deployment requires the design of improved battery and electrocatalyst materials. This requires understanding of the nature of these materials and the reactions occurring on their surfaces during use. Although we can currently study these materials post-mortem, this tells us little about the reactions that occurred during their active life. This fellowship details a plan to develop and apply a suite of innovative characterisation techniques that will enable chemical reactions occurring at the buried interfaces in electrochemical devices to be directly observed during operation. By using windows that are transparent to X-rays, electrons and neutrons, the atomic-scale processes occurring on the surface of rechargeable battery electrodes and electrocatalysts for producing valuable chemicals will be revealed without disturbing the liquid environments in which they operate. This will enable the limitations of existing material combinations to be understood, and for new material solutions to be identified and tested. A unifying theme between the battery and electrocatalysis strands of this project will be a focus on concentrated electrolytes, in which the positively and negatively charged ions are no longer fully surrounded by a solvent (e.g. water). This is a promising strategy for supressing undesired reactions in order to extend battery life and improve electrocatalyst efficiency. It can also potentially reduce toxicity and improve safety in devices based on these electrolytes, which is highly desirable for their implementation at scale. The proposed approach will improve our understanding of how ions and solvents arrange at electrochemical interfaces in these concentrated solutions, and the resulting impact on the electrochemical reactions occurring. The understanding developed through this program of research is expected to inform the design of low-cost, safe battery systems suitable for grid-scale storage to buffer intermittent renewable energy sources. It will also contribute to the identification of improved electrocatalyst materials and processes for the production of carbon-neutral liquid fuels and chemicals. These advances will reduce our reliance on fossil fuel extraction, ultimately helping to tackle long-term challenges such as climate change.