Energy is one of the primary challenges of the 21st century, and is driven by a need to decarbonise the energy sector and increase energy security and supply. These issues are well documented and do not require reiterating, except to highlight that success is paramount for continued economic and societal growth. Batteries have an important role to play here in the areas of portable electronics, electrified vehicles and grid storage. To date, lithium-ion has revolutionised energy storage, but UK lithium reserves are limited and globally the majority is located in only four countries, placing future UK industry subject to external market and geopolitical forces. Technology diversification is essential and batteries based on abundant sodium (Na ~ 2.6 % vs. Li ~ 0.005 % in the Earth's crust) must be developed. The sodium-ion battery has the potential to meet performance and cost targets in emerging battery markets. The battery benefits from the use of widely available and abundant sodium and unlike the lithium-ion battery, does not rely on cobalt for its electrode materials, making it a sustainable alternative to lithium-ion. This project will accelerate delivery of this technology, which will provide UK PLC with an alternative high performance battery technology. A number of key challenges limit development of this battery and these include identification of stable high performance battery electrodes and electrolytes. Significant progress has been made in this space and numerous advanced materials have been reported, but development of the negative electrode lags behind the other components. The main reason for this is that current electrolytes used in these batteries react with the negative electrode. The goal of this research programme will be to understand how changing this electrolyte affects the fundamental chemistry at the negative electrode in the battery and to build on this to identify new battery components able to provide a high performance and long life sodium-ion battery. This programme will be supported by close interaction with leading industrial stakeholders in the field to ensure technology relevant outputs and to provide a route to commercialisation.