Rechargeable lithium batteries are a game-changing technology for electric vehicles and portable electronics due to their benefits in energy density. However, safety is a concern because of the use of flammable organic liquid electrolytes in lithium batteries. Solid state electrolytes not only address the safety issue but also eliminate the issues related to Li metal anode and thus improve gravimetric as well as volumetric energy density, cycle life, and operable temperature range. Whilst there have been recent efforts to create solid state batteries, no real transformative progress has yet been made in this area. The work performed in this proposal will address the limitations of commercialization of solid-state lithium batteries whilst utilizing novel composite solid electrolyte (CSE) fabrication techniques to design composite solid electrolytes. The proposed undertaking presents an excellent training and career acceleration opportunity - enabling me to apply my academic research in an industrial setting whilst also gaining world class advanced innovation management and product development techniques. This will help transform my career and my applied academic profile into a leading authority in solid state lithium batteries and composite solid electrolyte technology.