A research team at Virginia Tech (VT) (Blacksburg, Virginia, USA), in collaboration with researchers from other academic institutions and scientific organizations, co-led a study to determine the activity within lithium-ion batteries that leads to battery electrode failure.
Led by Feng Lin, an assistant professor of chemistry in VT’s College of Science, the research team took a macro view of the battery failure problem, as opposed to other battery research studies that examined individual, or micro, areas. “If you have a perfect electrode, every single particle should behave in the same fashion,” Lin says. “But battery electrodes are very heterogeneous. We have millions, if not billions, of particles. There’s no way to ensure each particle behaves at the same time.”
To conduct their research, Lin’s team used the synchrotron X-ray method, which offers a method for visualizing the three-dimensional interior structure of an object. Because only a few synchrotron facilities exist in the United States, the team received their results from outside institutions, most notably the European Synchrotron Radiation Facility in Grenoble, France.
Lin compares individual battery particles inside an active battery to grains of rice inside a pot. “It’s impossible to have every single grain of rice identical in terms of their shapes and how far away it is to its neighbor,” he explains. “To make a better battery, you need to maximize the contribution from each individual particle.” Lin adds that researchers are excited to have established battery electrode chemistry from the atomic scale to the many-particle electrode scale.
While certain problems, such as individual particle inefficiencies, have been identified, researchers are still working to develop solutions due to the unique interactions of disparate elements within batteries. As a result, batteries seem to lose power at uneven rates. “When you’re charging, the top layer charges first, and the bottom layer charges later,” says Linqin Mu, a postdoctoral researcher in Lin’s Lab at VT. “Which part would you use to tell when your charge is complete? If you use the bottom layer as your fingerprint, the top layer will be overcharged and has safety problems.”
The results of the lithium-ion battery study were published in Advanced Energy Materials, a peer-reviewed scientific journal covering energy-related research. These findings are expected to establish the theoretical framework that will help battery researchers learn more about the heterogenous nature of battery electrodes.
Source: Virginia Tech Daily, www.vtnews.vt.edu.