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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.

3M will develop a new anion exchange membrane (AEM) technology with widespread applications in fuel cells, electrolyzers, and flow batteries. Unlike many proton exchange membrane (PEM) applications, the team’s AEM will operate in an alkaline environment, which means lower-cost electrodes can be used. The team plans to engineer a membrane that simultaneously meets key goals for resistance, mechanical and chemical stability, and cost. They will do this by focusing on simple, hydroxide-stable polymers, such as polyethylene, and stable cations, such as tetraalkylammonium and imidazolium groups.

The University of California, San Diego (UC San Diego), in partnership with Liox Power and the University of Maryland, will develop a self-forming, high temperature solid-state lithium battery that solves the critical cost and performance problems impeding commercialization of solid-state batteries for electric vehicles. The battery will possess a very long life due to a chemical mechanism that repairs cycling damage automatically. This self-healing electrolyte will also limit the growth of dendrites.

Rensselaer Polytechnic Institute (RPI) will develop hydroxide ion-conducting polymers that are chemically and mechanically stable for use in anion exchange membranes (AEM). Unlike PEMs, AEMs can be used in an alkaline environment and can use inexpensive, non-precious metal catalysts such as nickel. Simultaneously achieving high ion conductivity and mechanical stability has been a challenge because high ion exchange capacity causes swelling, which degrades the system’s mechanical strength.

The University of Colorado, Boulder (CU-Boulder) will develop a new type of anion-exchange membrane for chloride (Cl-) transport that is based on a nanoporous lyotropic liquid crystal structure that minimizes cation crossover by molecular size-exclusion and charge exclusion. Due to a lack of suitable Cl- conducting membranes, flow batteries often use microporous membranes or cation-exchange membranes (CEM) to separate the two electrode chambers.

United Technologies Research Center (UTRC) will develop a redox flow battery system that combines next-generation reactants with an inexpensive and highly selective membrane. This SMART-FBS project addresses the two highest cost components in redox flow battery systems: reactants and membranes. The team plans to develop these two components simultaneously using core materials that will work in tandem. Polymer membranes will be developed that include benzimidazole or pyridine structures; ionic conductivity will come from the membrane’s structure that allows acid to be imbibed into the polymer.

Iowa State University (ISU) will develop new lithium-ion-conducting glassy solid electrolytes to address the shortcomings of present-day lithium batteries. The electrolytes will have high ionic conductivities and excellent mechanical, thermal, chemical, and electrochemical properties. Because glasses lack grain boundaries, they will also be impermeable to lithium dendrites, branchlike metal fibers that can short-circuit battery cells. These glassy solid electrolytes can enhance the safety, performance, manufacturability, and cost of lithium batteries.

The Colorado School of Mines will develop a new membrane for redox flow battery systems based on novel, low-cost materials. The membrane is a hybrid polymer that includes heteropoly acid molecules and a special purpose fluorocarbon-based synthetic rubber called a fluoroelastomer. The team will enhance the membrane's selectivity by refining the polymer structure, employing crosslinking techniques, and also through doping the polymer with cesium. The fluoroelastmer is commercially available, thereby contributing to a superior performance-to-cost ratio for the membrane.

24M Technologies will lead a team to develop low cost, durable, enhanced separators/solid state electrolytes to build batteries using a lithium metal anode. Using a polymer/solid electrolyte ceramic blend, 24M will be able to make a protective layer that will help eliminate side reactions that have previously contributed to performance degradation and provide a robust mechanical barrier to branchlike metal fibers called dendrites. Unimpeded, dendrites can grow to span the space between the negative and positive electrodes, causing a short-circuit.

American Manufacturing, in collaboration with the University of Colorado at Boulder, will develop a flash sintering system to manufacture solid lithium-conducting electrolytes with high ionic conductivity. Conventional 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. In conventional sintering a friable ceramic “bisque” is heated for several hours at very high temperatures until it becomes dense and strong.