As part of the $125 million awarded to 41 projects under its 2015 OPEN funding (earlier post), ARPA-E has selected two projects developing manufacturing techniques for ceramic electrolytes for solid-state EV batteries for awards of a combined $6.6 million. Of that, $3.5 million will go to a consortium led by the University of Michigan, and $3.1 million will go to Corning Incorporated.
Solid-state Li batteries could double the energy density of today’s Li-ion cells and also eliminate the use of conventional flammable electrolytes, increasing abuse tolerance and reducing the need for battery thermal management systems. ARPA-E has already funded a number of solid-state battery projects (e.g., earlier post). Solid-state batteries face conductivity challenges, however.
University of Michigan. In a project labeled “Transitioning Advanced Ceramic Electrolytes into Manufacturable Solid-State EV Batteries,” researchers at the University of Michigan and partners will develop new electrode structures and manufacturing techniques to incorporate Lithium (Li)-conducting ceramic electrolytes into solid-state batteries.
The U-M project is led by Jeff Sakamoto, an associate professor of mechanical engineering, who is also affiliated with with U-M’s Energy Institute.
Like many energy storage researchers, Sakamoto has been exploring solid-state batteries, which don’t use a liquid electrolyte. Liquid electrolyte contributes to many of the lithium-ion battery’s limitations. His APRA-E proposal aims for an inexpensive, highly efficient solid-state battery that is tough and safe enough to power a vehicle.
However, while many researchers feel that new electrolytes must be developed to meet the conductivity threshold required for a true battery breakthrough, Sakamoto posits that existing materials are fine, and what’s really needed is a groundbreaking design and manufacturing process.
Super-ionic conducting oxide (SCO) electrolytes are a unique subset of ceramic electrolytes that offer numerous benefits in the development of solid-state battery technology. First, SCOs are typically synthesize in air and are reasonably stable in ambient air. This stability can simplify cell fabrication, reduce packaging mass, and dramatically improve safety. Second, the thermal stability and increasing conductivity with an increasing temperature can enable an inherently stable cell chemistry that reduces peripheral component such as thermal management and power electronics. In the context of electric vehicles, this can significantly reduce the battery pack mass, cost, and complexity. Third, consisting of stable inorganic materials, solid state oxide batteries can considerably have a longer cycle life compared to liquid electrolyte technology.
Indeed the features offered by solid-state batteries are appealing; however, there are few examples of bulk-scale SCO-enabled technology. Interestingly, it is not due to the lack of available state-of-the-art SCOs, rather it is the numerous processing, scaling and integration challenges that have limited the advancement of bulk-scale solid-state battery technology.
For example, most oxide ceramics require high temperature processing to bond or sinter components together. How the high temperature processing affects reactions with electrodes is a considerable issue. Similarly, maintaining adequate electrolyte/electrode contact area without amplifying chemical reactions is challenging and requires novel cell stack designs and fabrication techniques. In bonding and operating monolithic batteries, mechanical properties are of particular importance since most ceramics are relatively brittle. Lastly, and perhaps most importantly, identifying SCOs with inherent stability against Li or developing technology to enable the use of state-of-the-art SCOs is the key.—J. Sakamoto in Handbook of Solid State Batteries
Sakamoto will work with other researchers from U-M, Ford Motor Company, Oak Ridge National Laboratory, the Army Research Laboratory, Solid Power, and the University of Rochester.
Corning. In Corning’s project, “Roll-to-Roll Processing Ceramic Battery Electrolyte,” researchers there will develop roll-to-roll manufacturing techniques to produce thin ceramic electrolytes for solid-state batteries. The technology developed in this project is intended to enable solid-state batteries to be produced economically and at high volumes.
Corning holds patents on a number of ceramic electrolyte materials for solid-state batteries, including fluorine-containing lithium-garnet-type oxide ceramics and lithium orthophosphate glasses. The company holds numerous patents in other areas of battery technology as well.
Corning also partnered with PolyPlus in an earlier ARPA-E project on Li-air batteries. (Earlier post.)
Final award amounts may vary.
Nakamoto, Jeff. “Chapter 12: Super-ionic Conducting Oxide Electrolytes” Handbook of Solid State Batteries