BATTERIESA New Blueprint for Designing High-Performance Batteries
Cooperative behavior among components in batteries points to an exciting new approach to designing next-generation technologies, pointing the way to better electric vehicle batteries and storage of renewable energy on the grid.
A team of scientists at the U.S. Department of Energy’s (DOE) Argonne National Laboratory discovered an intriguing “cooperative” behavior that occurs among complex mixtures of components in electrolytes in batteries. Electrolytes are materials that move charge-carrying particles known as ions between a battery’s two electrodes, converting stored chemical energy into electricity.
The team found that combining two different types of anions (negatively charged ions) with cations (positively charged ions) can significantly improve the overall battery’s performance. This suggests that careful selection of ion mixtures can enable battery developers to precisely tailor their devices to produce desired performance characteristics.
The study focused on a type of next-generation battery called the multivalent battery. Today’s lithium-ion batteries have a limited ability to provide performance attributes needed in critical applications like passenger electric vehicles and storing renewable energy on the grid. Many researchers see multivalent batteries as a potential alternative.
These potentially game-changing technologies use cations such as zinc, magnesium and calcium that have a charge of +2 as opposed to +1 for lithium ions. By moving more charge, multivalent batteries can store and release more energy. This makes them attractive candidates to replace existing lithium-ion battery technologies in electric vehicles. They are also envisioned for grid storage.
Another advantage of multivalent batteries is that they use abundant elements supplied through stable, domestic supply chains. In contrast, lithium is less abundant and has an expensive, volatile international supply chain.
The Quest to Advance Multivalent Batteries
Optimizing how an electrolyte moves ions between battery electrodes is crucial for good performance and long lifetimes. This back-and-forth process results in the deposition and stripping of metal atoms on the surface of a battery’s anode (negative electrode). A high-performance, long-lasting battery should be able to reversibly deposit and strip a uniform layer of metal for thousands of cycles.
Today, most multivalent batteries under investigation by researchers do not perform well, limiting their commercial viability. The ions and electrodes tend to be unstable and degrade. As a result, the electrolytes are unable to efficiently transport cations, diminishing the battery’s ability to generate and store electricity.
Researchers need to know what causes the degradation and inefficiency. This requires a much deeper understanding of how cations interact with other ions, atoms and molecules in the electrolyte. Gaining this knowledge is particularly important as researchers explore electrolytes with more complex mixtures of cations and anions.
