For quite a while the trend has been to make batteries thinner. So smartphones slip into our pockets easier, and we can cram more batteries into electric vehicles. A team from Penn State University Materials Research Institute, would like to turn this theory of its head. They would like to see denser, thicker electrodes because they figure they are the business end of a battery.
Thicker Electrodes Contribute to Better Performance
If we think about it, the team from Penn State says, only the electrodes contribute to battery performance. All the other parts – packaging, separator, current collector and so on – play a passive, supporting role. Therefore it follows we need to work on the battery electrode materials, if we really want to improve battery performance.
Typical modern batteries have thin-film anode and cathode electrodes, they continue. Merely increasing their thicknesses could improve energy storage capacity and density, by providing more space for storing and releasing energy. However, thicker electrodes would also exchange their electrons at a slower rate, resulting in degraded overall performance.
How the Team Increased the Electron Exchange Rate
The Penn State team turned their attention to speeding the flow of electrons between their thicker electrodes. They found a way to do so, using pressure and heat to compact and densify the materials into solid objects. This technique is called spark plasma sintering (SPS), if you would like to investigate it further.
“SPS enabled us to fabricate a very thick and dense electrode,” the team leader explains. “The typical thickness of the battery electrode is only about 50 microns to 100 microns,” he continues. “But now, in this work, we are talking about 300 microns, 500 microns. That is five times higher than the proportion of mass of the electrode in a real battery device.”
This relatively novel approach to battery electrodes increases the percentage of active components, without degrading overall performance. The battery case does not become thicker, due to the greater compression of the denser electrodes. The team is now investigating ways to commercialize their discovery.
More Information
Electrode Chemistry Inside a Storage Battery
Energy Density in Batteries and How It Matters
