Scientists have found out why solid-state batteries degrade and are ready to make them much better

One of the modern approaches to developing new materials can be characterized by the phrase: “It is better to see once than to calculate ten times.” From a scientific point of view, this is not entirely correct, since theoretical justification allows saving money on experiments and creating prototypes. However, today they strive to save on everything, including work on theory. Fortunately, modern tools for analyzing atomic structures come to the rescue, which significantly simplify the work of scientists.

Mercedes-Benz’s solid-state battery electric vehicle has begun testing. Image source: Mercedes-Benz

In particular, a new method in electron microscopy, 4D STEM (Four-Dimensional Scanning Transmission Electron Microscopy), helped to make a breakthrough in the development of highly reliable solid-state batteries. This advanced technology combines spatial scanning with full electron diffraction analysis, allowing us to obtain detailed information about the structure of materials at the nano- and atomic levels.

One of the reasons for the degradation of solid-state batteries is the formation of a thin (up to 100 nm) interphase layer at the boundary between the cathode and the electrolyte. This layer prevents the movement of lithium ions from the cathode to the anode and back, which over time significantly worsens the battery’s characteristics.

Using the 4D STEM method, scientists from the University of Missouri were able to study the processes of interphase layer formation at the atomic level. The data obtained will help to select and test special cathode coatings that will prevent the formation of these layers without compromising the ionic conductivity of the electrolyte. In the next stage, the researchers will test suitable coatings.

They also reported on their study of the properties of solid-state batteries in a paper in the journal Advanced Energy Materials, which will help other research groups advance the field. Discovering new properties of solid-state batteries and studying their interaction with certain types of protective materials will lead to the creation of batteries with improved characteristics: electric cars will be able to travel further and electronics will work longer.