Scientists at the Department of Energy’s Oak Ridge National Laboratory have developed a scalable and inexpensive method of improving material assembly in solid-state batteries, solving one of the great challenges in the commercial development of safe and long-life energy storage systems.
Solid-state batteries incorporate a safer, faster-charging architecture incorporating a solid-state electrolyte compared to the liquid electrolytes in today’s lithium-ion batteries. A successful commercial solid-state battery system could deliver at least twice the energy density of lithium-ion batteries in a much smaller footprint. The system would allow, for example, electric vehicles with significantly improved range.
One of the challenges of solid-state battery manufacturing is the difficulty of properly assembling materials and remaining stable during repeated charge and discharge cycles. Scientists studying laboratory methods to overcome this characteristic, called contact impedance, have so far focused on the application of high pressures and other methods. But this process can lead to a short circuit and should be reapplied periodically to extend battery life with the help of an expensive aftermarket app.
ORNL researchers used an electrochemical pulse that removes voids that form when layers of lithium metal anode material are joined with a solid electrolyte material: in this case the garnet-like electrolyte ceramic LALZO (Li6.25Al0.25The3Zr2oh12). The application of short high voltage pulses led to increased contact at the interface of the materials without causing adverse effects, as detailed in an open access article in ACS Energy Letters.
ORNL scientists have developed a scalable and inexpensive electrochemical pulse method to improve the contact between layers of materials in solid-state batteries, solving a key challenge in high-energy-density solid-state batteries . Credit: Andy Sproles / ORNL, US DOE
The inexpensive, non-destructive pulsation method drives a local heat-generating current that surrounds the voids coated with lithium metal and causes them to dissipate. The team repeated experiments and advanced material characterization, which found that the battery components did not degrade after applying the pulsation method. This approach could be scaled to allow the solid-state battery to be removed and refreshed, bringing it almost back to its original capacity.
This method will allow an all-solid architecture without applying an extrinsic force which can damage the cell and is inconvenient to deploy while using the battery. In the process we developed, the battery can be manufactured normally and then a pulse can be applied to rejuvenate and refresh the interface if the battery becomes tired.
—Ilias Belharouak, co-head of the project and head of the electrification section at ORNL
The idea for the method came from earlier work in which ORNL battery researchers used electrochemical pulses to heal damaging dendrites that can form in solid electrolytes.
Research is ongoing, including experiments with more advanced electrolytic materials. ORNL’s multidisciplinary energy storage team is also working to extend its breakthroughs to a functional-scale solid-state battery system.
The project used the capacities of the DOE battery manufacturing plant at ORNL. The research was funded by the DOE Office of Energy Efficiency and Renewable Energy’s Vehicle Technologies Office, as well as the research and development program led by ORNL laboratories.
Anand Parejiya, Ruhul Amin, Marm B. Dixit, Rachid Essehli, Charl J. Jafta, David L. Wood and Ilias Belharouak (2021) “Improve contact impedance via electrochemical pulses applied to the lithium-solid electrolyte interface in semiconductor batteries’ ACS Energy Letters 6 (10), 3669-3675 doi: 10.1021 / acsenergylett.1c01573