The growing demand for safe, sustainable and energy-dense energy storage devices has spurred intensive investigations into post-lithium battery technologies. Rechargeable aluminium batteries are promising candidates for future electrochemical energy storage systems due to the high theoretical volumetric capacity of aluminium and its natural abundance in the Earth’s crust. While several different classes of liquid electrolytes have been explored in aluminium battery research, including aqueous solutions, organic solvents, inorganic molten salts and deep eutectic solvents, imidazolium-based chloroaluminate ionic liquids are the most commonly used due to their ability to reversibly electrodeposit aluminium with very high coulombic efficiencies. Unfortunately, these ionic liquids are extremely expensive, hygroscopic and corrosive to conventional battery components, while issues characteristic of liquid electrolytes, such as leakage and gaseous emissions, further complicate their application in practical systems. This PhD project will focus on the synthesis and characterisation of ionic liquid derived solid and semi-solid electrolytes for aluminium batteries, aiming to combine the core requirements of safety, sustainability and performance for future energy storage systems.