Persistent battery power and anti-corrosion coatings are key to sustaining military operations. Batteries power everything from tactical radios and handheld devices to unmanned systems. Protective coatings shield flight surfaces, rotor blades, and ship hulls from corrosion caused by humidity, sand, and saltwater. A challenge to creating more persistent batteries and coatings, however, is the inability to address microscopic irregularities that form at the interfaces of electrochemical materials.
Both persistent battery power and anti-corrosion coatings are key to sustaining military operations, however there is an inability to address microscopic irregularities that form at the interfaces of electrochemical materials.
DARPA announced the Morphogenic Interfaces (MINT) program in June 2021, which seeks to enhance the persistence of high-performance electrochemical systems by developing self-regulating interfaces that exploit detrimental local gradients to maintain optimal functionality over the planned operational life cycle. The inspiration for pursuing novel, adaptive electrochemical interfaces comes from biology and the concept of morphogenesis, which explains the process of how cells and tissues take shape.
“Batteries and anti-corrosion coatings both rely on electrochemical reactions that take place at material interfaces from the atomic through millimeter scale,” said Vishnu Sundaresan, MINT program manager in DARPA’s Defense Sciences Office. “It’s at these microscopic interfaces that high energy density solid-state batteries and novel corrosion resistant coatings/alloys run into problems.
In solid-state batteries, as positively charged ions are deposited on the negative electrode during charging and the positive electrode during discharging, changes to the interface leads to nanoscale voids at solid/solid ion transfer interfaces. With each cycle the number and size of voids increase rapidly, diminishing battery capacity until it can no longer hold a charge. Solving the voids issue at these interfaces is key to enabling practical solid-state batteries. Because solid-state batteries do not use liquid electrolytes, they’re inherently safe from catastrophic fire up to 150 degrees Celsius.
Solving the problem of voids at these interfaces is key to enabling practical solid-state batteries, which have high theoretical energy density and don’t use organic liquid electrolytes that are common in lithium-ion batteries used widely today. Because solid-state batteries do not use liquid electrolytes, they’re inherently safe from catastrophic fire up to 150 degrees Celsius.”
Corrosion resistant coatings/alloys on ship hulls, power plants and critical aircraft surfaces have similar electrochemical reactions at solid/liquid and solid/vapor interfaces. In aggressive corrosive environments, nanoscale pits form at the material interface due to corrosion penetrate the underlying metal and rapidly expand into larger cracks, weakening the hull, control surfaces, and engine components.
DARPA has selected six teams of industry and university researchers for the Morphogenic Interfaces (MINT) program. MINT aims to enhance the performance and persistence of batteries, anti-corrosion coatings, and other electrochemical systems that power and protect critical Department of Defense hardware and platforms.
The teams will develop novel solid-solid electrochemical interfaces for solid-state batteries and solid-liquid interfaces for corrosion-resistant coatings. The inspiration for pursuing novel, adaptive electrochemical interfaces comes from biology and the concept of morphogenesis, which captures the physics behind how cells and tissues take shape.
“Current solid-state batteries that have high energy density have limited charge/recharge cycles and current corrosion-resistant coatings require frequent maintenance in aggressive performance environments,” said Vishnu Sundaresan, MINT program manager in DARPA’s Defense Sciences Office. “Premature failure in these systems is due to the formation of structural defects such as voids at the interfaces between two materials. The teams we’ve selected will develop and demonstrate novel morphogenic interface materials to enable long-lasting and high-performance solid-state batteries that power everything from warfighter battery packs to unmanned aerial and ground vehicles as well as provide low-maintenance corrosion resistant coatings for critical maritime assets deployed in harsh environments.”
Morphogenesis was coined in the early 20th Century by D’Arcy Thompson, a Scottish naturalist mathematician, and the mathematical model for morphogenesis was first developed by Alan Turing. The concept of morphogenesis is so universal that it has been applied to pattern formation in almost any system – in geology, in the patterns on desert sands, floral patterns in plants, and even in 3D digital works of art.
“This approach can be naturally extended to electrochemical systems,” Sundaresan said. “Through this program, I want to spur the scientific community to exploit the mathematical framework offered by morphogenesis models to understand the evolution of morphology in solid/solid, solid/liquid, and solid/vapor interfaces, and extend this understanding to build better solid-state batteries, corrosion-resistant coatings and alloys.”
MINT development efforts are focused on two application-centric focus areas. The first is solid/solid charge transfer interfaces to enable solid-state batteries with unprecedented combinations of energy density and cycle life. The second focus area addresses solid/liquid and solid/vapor interfaces for high- performance corrosion resistant coatings and alloys.
The following research teams are on contract to pursue a variety of approaches within the program’s two focus areas:
Solid/solid charge transfer interfaces for solid-state batteries
- GE Research, teamed with the University of Michigan, University of California Santa Barbara, and Storagenergy, will develop a multi-scale integrable deep neural network model to design an intermetallic solid/solid charge transfer interface material to enhance the performance of lithium-ion solid-state batteries (Li-SSBs).
- Carnegie Mellon University, teamed with MIT, Harvard University, Argonne National Laboratory, 24M Technologies, and QuantumScape, will develop an end-to-end model for solid-state batteries using differentiable physics to discover new soft solid materials and demonstrate its application in Li-SSBs.
- University of Illinois Urbana-Champaign, teamed with University of Michigan, Purdue University, Princeton University, Caltech, Georgia Tech, and Xerion Advanced Battery Corp., will develop a chemo-mechanical model of solid/solid interfaces using atomistic, molecular dynamics and continuum models and use this knowledge to design and fabricate Li-SSBs containing novel interface materials.
Solid/liquid and solid/vapor interfaces for corrosion resistant coatings
- Johns Hopkins University, teamed with Northwestern University and Northrop Grumman Corporation, will develop thermodynamic, quantum mechanical, and dynamic models to explore self-organized titanium-chromium (Ti-Cr) coatings with a hierarchical microstructure that offer resistance to cracking and corrosion fatigue.
- University of Virginia, teamed with Saint Louis University and Florida State University, will develop physics-based design and control of material-environment interfaces to design anticorrosion surface treatments that extend the fatigue life of aluminum-magnesium (Al-Mg) and magnesium-aluminum (Mg-Al) alloys.
- GE Research, teamed with University of Virginia, DNV GL USA, and Brigham Young University, will explore the design of high entropy alloy coating via atomic, electrochemical models and physics-based machine learning that use controlled corrosion of surface treatments to form a protective barrier film.
The initial challenge for program performers in both focus areas during Phase I will be to model interfacial processes (i.e., address the performance-degrading microscopic irregularities that form at the interfaces of electrochemical materials), design and discover morphogenic interfaces, and demonstrate the performance improvements due to the morphogenic interface in a solid-state battery and for corrosion mitigation of structural alloys. In Phase 2, the teams will improve upon their models to increase accuracy and improve the performance of interface materials in batteries and corrosion protection.