Pennsylvania State University (Penn State)

Demand for Lithium-ion (Li-ion) batteries has increased significantly as products such as smartphones, laptops, electric vehicles, and grid storage batteries rise in popularity. However, Li-ion batteries have numerous safety and performance limitations due to their flammable electrolyte and the charge storage density of their active materials, which are not easily overcome by incremental progress. New types of high-performance separators and electrodes built with solid-state ion conductors could simultaneously improve the energy density and safety of lithium ion batteries by removing the most flammable battery components, and also improving the driving range and durability of electric vehicles. Solid-state separators also open the door to the use of lithium metal as an active material, resulting in a significant increase in cell energy content, and the subject of research efforts for the past several decades. New battery technology that employs energy dense, thermally stable, and long-lasting materials will also be of interest for grid storage, particularly in dense, urban environments where the space occupied by storage systems is more of a concern.

Pennsylvania State University (Penn State) will develop a process for cold-sintering of ceramic ion conductors below 200°C to achieve a commercially viable process for integration into batteries. Compared to liquid electrolytes, ceramics and ceramic composites exhibit various advantages, such as lower flammability, and larger electrochemical and thermal stability. One challenge with traditional ceramics is the propagation of lithium dendrites, branchlike metal fibers that short-circuit battery cells. Penn State will create ceramic and ceramic/polymer composite electrolytes that resist dendrite growth by creating optimized microstructures via cold sintering. Sintering is the process of compacting and forming a solid mass by heat and/or pressure without melting it to the point of changing it to a liquid, similar to pressing a snowball together from loose snow. However, the high temperature required for traditional sintering of ceramics limits opportunities for integration in electrochemical systems and leads to high processing costs. Cold-sintering below 200°C changes the ability to control grain boundaries within ceramic materials, creates opportunities to tune interfaces, and opens the door for integration of different materials. It also allows large area co-processing of organic and inorganic materials in a one-step process, leading to savings in fabricating costs by eliminating the separate ceramic sintering steps and high-temperature processing.

If successful, developments made under the IONICS program will increase the energy storage content for vehicle batteries by about 30% compared to today's Li-ion batteries and significantly reduce battery storage system costs.