Roll-to-Roll Production of Flexible Composite Solid-State Electrolytes for Lithium Metal Batteries in Electric and Hybrid Electric Vehicles using Gravure Printing

To make the electrical vehicles more competitive with internal combustion engine ones, the United States Advanced Battery Consortium has listed a set of goals for future lithium-ion batteries to meet, which includes a higher specific energy (275 Wh/kg) and energy output (50 kWh). Since current lithium-ion batteries aren’t capable of reaching these goals, rechargeable lithium-metal batteries have been of particular interest in recent years. However, due to the dendrite growth issue of lithium metal anodes, the key factor to commercialize lithium-metal batteries is to develop suitable solid-state electrolytes to replace the organic liquid electrolytes. Among the solid-state materials, sulfide ceramics are the most promising owing to their high ionic conductivity and stability. Unfortunately, their brittleness still hinders their application in large scale production. To overcome this drawback, fabrication of composite electrolyte by the integration of sulfide ceramics with specific polymers has been proven to be a promising route. The composite electrolyte shows good flexibility, chemical compatibility with high-performance cathodes and efficient ability to block lithium dendrite growth. However, a suitable processing method should be developed to meet the high output, good reproducibility requirements for composite electrolyte production. In Phase I, a low-cost roll-to-roll method will be developed for the formation of a ceramic/polymer composite. The ceramic/polymer composite slurry will be developed so that it can be tape casted into high ionic conductive and mechanically flexible and strong membranes. The membrane will be assembled into all solid-state lithium batteries in coin cell and pouch cell format and evaluated for its performance. The slurry will be used to develop a scalable Gravure Printing process to make the process more appropriate for mass production and easily integrated with mass production assembly lines. The product will be put into pouch cells and tested under United States Battery Consortium guideline. Future Phases will focus on optimization of the roll-to-roll process in order to achieve optimal composite electrolyte. Furthermore, cells in larger format (2Ah) and different configurations such as cylindrical cells will be fabricated for practical applications. Electrochemical performance and safety testing will also be conducted at various temperatures to show the applicational capabilities of the electrolytes. It is anticipated that this solid electrolyte fabrication approach will greatly accelerate the commercialization of lithium-metal batteries in electric vehicle industries.