A novel surface coating approach to enable high voltage cathode materials in an all solid state lithium anode battery

High voltage cathodes with a spinel structure and nominal voltage above 4.6V, provide a unique opportunity to deliver higher energy density (Wh/kg) relative to state-of-the-art lithium-ion batteries, most of which are based on either layered material (3.6V) or phosphate (3.4V). The use of a solid electrolyte in a high voltage cathode-based cell has the potential to meet the safety requirements for Army applications and enable the use of lithium metal anodes to greatly increase energy density. A particular challenge in using high voltage cathodes with solid electrolyte is the high charge transfer resistance that exists at the cathode-solid electrolyte interface. Another problem is that common solid electrolytes have a limited electrochemical window (well below 5V) and therefore do not support high voltage cathodes. The proposed technology addresses these unmet needs by taking advantage of the synergy between conductive coatings on cathode particles and a newly developed solid electrolyte system that is stable up to 5V. The present program is a collaboration between NEI Corporation and Rowan University (STTR partner). Building upon the proof of concept demonstrated during Phase I, the primary objective of the Phase II program is to optimize the composition, morphology and distribution of the components in the cathode and separator so as to deliver the maximum energy density with a cycle life that is acceptable to the Army, while being operational over a wide temperature range (-20°C to 45°C). An additional objective is to demonstrate the technology at a pouch cell level (1 – 2 Ah), so that by the end of the Phase II program, the solid electrolyte - based battery is ready for prototype development and testing in conjunction with a DoD battery manufacturer. The Phase II work plan includes materials synthesis, laboratory scale-up, coin and pouch cell fabrication, electrochemical testing, structural and chemical analysis to aid the optimization effort, culminating in the delivery of a set of 20 pouch cells to the Army for testing and validation. We expect the TRL to be 5 at the end of the Phase II STTR program.