In this NASA STTR project, Aegis Technology is teamed with Cornell University and proposes to develop a novel class of all-solid-state Li-ion batteries (ASSLiBs) based on a proprietary solid electrolyte and a novel cell structure design. This electrolyte can provide not only high ionic conductivities, but also wide operating temperature ranges, and good compatibilities with designed electrodes. By integrating this class of electrolytes with properly designed high energy electrodes, interfacial resistance issues oftentimes found in conventional ASSLiBs can be effectively addressed, resulting in more desirable battery performance such as enhanced energy/power densities, improved cyclability, and excellent safety. In addition, the proposed ASSLiBs can be processed using an industrially mature multilayer ceramic capacitor (MLCCs) processing technology, allowing for the mass production in a cost-effective and scalable manner. Phase I will focus on the feasibility demonstration of the proposed technology, through material design, processing, prototyping and characterizations, in which small-scaled ASSLiB cells will be prototyped and demonstrated. In Phase II, further optimization, scaling up, characterization and evaluation will be carried out for both scaled-up material design/processing and the full-scale cell fabrication, which will pave the way to the successful development of a commercially viable battery product suitable for NASA and other military/civil applications. Potential NASA Applications (Limit 1500 characters, approximately 150 words) High performance, long cycling life, and low costs ASSLiBs, once successfully developed, will find wide applications in NASA systems. EAP is an area of strong and growing interest in NASA's Aeronautics Research Mission Directorate (ARMD). High performance ASSLiBs are required for aircraft to have sufficient range, safety, and operational economics for regular service. It will fulfill the markets needs for span Urban Air Mobility (UAM), thin/short haul aviation, and commercial air transport vehicles which use electrified aircraft propulsion. Potential Non-NASA Applications (Limit 1500 characters, approximately 150 words) Potential non-nasa applications include both military systems (such as silent watch applications, electric vehicle and spacecraft) and commercial systems (hybrid electric, all electric power generation as well as distributed propulsive power).