High-tech labs could help design future generations of batteries
Designing a battery is a three-part process. You need a positive electrode, you need a negative electrode, and โ importantly โ you need an electrolyte that works with both electrodes.
An electrolyte is the battery component that transfers ions โ charge-carrying particles โ back and forth between the batteryโs two electrodes, causing the battery to charge and discharge. For todayโs lithium-ionย batteries, electrolyte chemistry is relatively well-defined.ย For future generations ofย batteriesย being developed around the world and at the U.S. Department of Energyโs (DOE) Argonne National Laboratory, however, the question of electrolyte design is wide open.
โWhile we are locked into a particular concept for electrolytes that will work with todayโs commercialย batteries, for beyond-lithium-ionย batteriesย the design and development of different electrolytes will be crucial,โ said Shirley Meng, chief scientist at the Argonne Collaborative Center for Energy Storage Science (ACCESS) and professor of molecular engineering at theย Pritzker School of Molecular Engineeringย of The University of Chicago.ย โโElectrolyte development is one key to the progress we will achieve in making these cheaper, longer-lasting and more powerfulย batteriesย a reality, and taking one major step towards continuing to decarbonize our economy.โ
In a new paper published in Science, Meng and colleagues laid out their vision for electrolyte design in future generations ofย batteries.
Even relatively small departures from todayโsย batteriesย will require a rethinking of electrolyte design, according to Meng. Switching from a nickel-containing oxide to a sulfur-based material as the main constituent of a lithium-ion batteryโs positive electrode could yield significant performance benefits and reduce costs if scientists can figure out how to rejigger the electrolyte, she said.
For other beyond-lithium-ion battery chemistries, like rechargeable sodium-ion or lithium-oxygen, scientists will similarly have to devote considerable attention to the question of the electrolyte.
One major factor that scientists are considering in the development of new electrolytes is how they tend to form an intermediary layer called an interphase, which harnesses the reactivity of the electrodes.ย โโInterphases are crucially important to the functioning of a battery because they control how the selective ions flow into and out of the electrodes,โ Meng said.ย โโInterphases function like a gate to the rest of the battery; if your gate doesnโt function properly, the selective transport doesnโt work.โ
The near-term goal, according to the team, is to design electrolytes with the right chemical and electrochemical properties to enable the optimal formation of interphases at both the batteryโs positive and negative electrodes. Ultimately, however, researchers believe that they may be able to develop a group of solid electrolytes that would be stable at extreme (both high and low) temperatures and enableย batteriesย with high energy to have much longer lifetimes.
โA solid-state electrolyte for an all-solid battery will be a game changer,โ said Venkat Srinivasan, director ofย ACCESS, deputy director of the Joint Center for Energy Storage Research, and co-author on the paper.ย โโThe key to a solid-state battery is a metal anode, but its performance is currently limited by the formation of needle-like structures called dendrites that can short out the battery. By finding a solid electrolyte that prevents or inhibits dendrite formation, we may be able to realize the benefits of some really exciting battery chemistries.โ
In order to speed up their hunt for electrolyte breakthroughs, scientists have turned to the power of advanced characterization andย artificial intelligenceย (AI) to search digitally through many more possible candidates, accelerating what had been a slow and painstaking process of laboratory synthesis.ย โโHigh performance computing andย artificial intelligenceย are allowing us to identify the best descriptors and characteristics that will enable the tailored design of various electrolytes for specific uses,โ Meng said.ย โโInstead of looking at a few dozen electrolyte possibilities a year in the lab, weโre looking at many thousands with the aid of computation.โ
โElectrolytes have billions of possible combinations of components โ salts, solvents and additives โ that we can play with,โ Srinivasan said.ย โโTo make that number into something more manageable, weโre beginning to really use the power ofย AI,ย machine learningย and automated laboratories.โ
The automated laboratories to which Srinivasan referred will incorporate a robot-driven experimental regime. In this way, machines can perform unassisted ever more carefully refined and calibrated experiments to eventually determine which combination of components will form the perfect electrolyte.ย โโAutomated discovery can dramatically increase the power of our research, as machines can work around the clock and reduce the potential for human error,โ he said.
Meng, Srinivasan and Army Research Laboratory scientist Kang Xu discuss the electrolyte challenge in a paper entitledย โโDesigning better electrolytes,โ which appeared inย Scienceย on Dec. 8.
The work was funded by the Joint Center for Energy Storage Research, aย DOEย Office of Science Energy Innovation Hub, and byย DOEโs Office of Science, Basic Energy Sciences program.
