Exploring All-Solid-State Batteries using First-Principles Modelling: Effective Computational Strategies towards Better Batteries

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Energy storage has a more central role in our society today than ever before and has become one of the greatest research challenges of our time. The UK's Department of Energy & Climate Change has committed to the green-house gas emission reduction of 80% by 2050 through the Climate Change Act and has recently announced an £246-million investment in energy storage R&D. Such moves are motivated by the necessity for the UK to benefit from what is a global transition to new energy sources and more effective storage. However, solving the limitations in the current battery technologies will be key in order for the UK to develop high-performance, sustainable energy storage with low environmental impact. Since the 1980s, rechargeable Lithium-ion batteries (LIBs) have pioneered clean and effective energy storage and revolutionised portable electronics. Similarly, LIBs can be the key technology for the development of electric vehicles and grid-scale storage of renewable energy. The upscaling of the LIBs is, however, not straightforward due to safety issues. Organic electrolyte solutions -commonly used in the conventional Li-ion batteries- are volatile, flammable and even explosive, potentially causing catastrophic failures, specifically when used in substantial amounts in multi-cell batteries to power energy-intensive applications. As we near the theoretical limits of conventional Li-ion batteries, there is an ever-growing need for next-generation battery technologies that can meet the stringent energy demand.By replacing the organic electrolyte solutions with solid equivalents, all solid-state batteries (ASSB) can not only mitigate these safety issues, but also provide superior battery performances due to their higher energy density. This renders ASSBs ideal for challenging applications in various industries, on a small (battery on a chip or sensor), medium (electric vehicles) to large scale (grid-level storage for renewables). Three major setbacks, however, still need to be addressed before ASSBs can be fully commercialised: (1) the limited performance of the current ASSB components compared to traditional battery ones; (2) chemical, electrochemical and mechanical incompatibilities between the solid electrolytes and electrodes; (3) globally limited Li reserves, increasing the battery unit costs whilst demands for Li-ion batteries are growing.The full potential of ASSBs as next-generation batteries can be unlocked by the discovery of new battery materials with superior features compared to current technology, such as higher energy densities, faster charge rates, safer operation, better component compatibility and lower prices. Based on lab-based trial-and-error, the experimental materials discovery can be both expensive and time consuming: a new material must be synthesised and stabilized in the lab before its efficiency as a battery component can be assessed. Computational modelling tools can help accelerate this trial-and-error process both by predicting novel materials from scratch and by providing computer-based experiments to characterize the novel materials, complementing the physical experiments.In this framework, the main goal of this project is to improve all-solid-state battery technology using a bottom-up approach by tackling these primary limitations at an atomic level using computational modelling. This goal will be achieved by addressing three objectives:(1) To discover novel ASSB materials with superior performance, namely new solid-state electrolytes and suitable electrodes for the Li-ion and beyond Li-ion (e.g. sodium and potassium) battery technologies.(2) To engineer better solid electrolyte-electrode interfaces within ASSBs to augment their mechanical and electrochemical stability.(3) To rationally design ultrathin film deposition strategies to coat ASSB components to augment their compatibility with each other.