The quest for improved energy storage is currently one of the most important scientific challenges. The UK is investing heavily in energy storage and renewable energy technologies and is committed to reducing its CO2 emissions by replacing the majority of its electricity generating capacity over the next few decades. Building better batteries is key to the use of electricity in a low-carbon future and for the exploitation of current and next-generation technologies. Current Li-ion batteries based on liquid electrolytes cannot meet the requirements of future applications. The creation of safer, cheaper, recyclable and higher energy density batteries is therefore essential for the electrification of transport and grid-scale storage of energy from renewable resources. This EPSRC New Investigator Award will develop transformative methods that will deliver solutions to these societally and industrially critical problems. Solid-state Li-ion batteries are a rapidly emerging technology with the potential to revolutionise energy storage. This technology utilises solid electrolytes instead of the flammable liquid electrolytes found in current Li-ion batteries. The solid-state architecture has the potential to significantly increase both the safety and energy density of next-generation batteries. Their performance is, however, currently limited by a number of underlying challenges, including the presence of highly resistive interfaces and difficulties in controlling the microstructures of the solid electrolytes that these batteries are built around. These challenges greatly hinder Li-ion transport and are therefore highly detrimental to the operation of the battery. To address these pertinent issues, the team will develop and apply state-of-the-art computational and experimental techniques to provide a fundamental understanding of ion transport at the microscale of solid electrolytes for solid-state batteries. Such an understanding will allow for the design of solid electrolyte microstructures that promote Li-ion transport instead of restricting it. The insights obtained for solid-state batteries in this project will also have direct implications for other battery and energy technologies where the microstructure and solid-solid interfaces again play crucial roles in determining their performance.