Computer vision helps SLAC scientists study lithium ion batteries

A new computer vision algorithm for identifying particles in a lithium-ion battery cathode has helped researchers track the cathode's degradation over time. Image courtesy Yijin Liu/SLAC National Accelerator Laboratory

The new study, published May 8 in Nature Communications, focused on how to better visualize what's going on in cathodes made of nickel-manganese-cobalt, or NMC. In these cathodes, NMC particles are held together by a conductive carbon matrix, and researchers have speculated that one cause of performance decline could be particles breaking away from that matrix.

The team's goal was to combine cutting-edge capabilities at SLAC's Stanford Synchrotron Radiation Lightsource (SSRL) and the European Synchrotron Radiation Facility (ESRF) to develop a comprehensive picture of how NMC particles break apart and break away from the matrix and how that might contribute to performance losses.

Of course, it's a tall order for humans to figure out what's going on just by looking at pictures of an NMC cathode, so the team turned to computer vision, a subfield of machine learning algorithms originally designed to scan images or videos and identify and track objects like dogs or cars.

Even then, there were challenges. Computer vision algorithms often zero in on boundaries defined by light or dark lines, so they'd have a hard time differentiating between several small NMC particles stuck together and a single large but partially fractured one; to most computer vision systems, those fractures would look like clean breaks.

To address that problem, the team used a type of algorithm set up to deal with hierarchical objects – for example, a jigsaw puzzle, which we would think of as a complete entity even though it's made up of many individual pieces.

With input and judgments from the researchers themselves, they trained this algorithm to distinguish different kinds of particles and thus develop a three-dimensional picture of how NMC particles, whether large or small, fractured or not, break away from the cathode.

They discovered that particles detaching from the carbon matrix really do contribute significantly to a battery's decline, at least under conditions one would typically see in consumer electronics, such as smart phones.

Second, while large NMC particles are more likely to become damaged and break away, quite a few smaller particles break away, too, and overall, there's more variation in the way small particles behave, said Yijin Liu, a staff scientist at SLAC and a senior author of the new paper. That's important because researchers had generally assumed that by making battery particles smaller, they could make longer-lasting batteries – something the new study suggests might not be so straightforward, Liu said.

###

SSRL is a DOE Office of Science user facility. Additional authors include researchers from the Howard Hughes Medical Institute, the European Synchrotron Radiation Facility, Virginia Polytechnic Institute and State University, the Chinese Academy of Sciences and Purdue University. The research at SLAC was supported by the DOE Office of Science.

All latest news from the category: Materials Sciences

Materials management deals with the research, development, manufacturing and processing of raw and industrial materials. Key aspects here are biological and medical issues, which play an increasingly important role in this field.

innovations-report offers in-depth articles related to the development and application of materials and the structure and properties of new materials.

Back to home

Comments (0)

Write a comment

Newest articles

Lighting up the future

New multidisciplinary research from the University of St Andrews could lead to more efficient televisions, computer screens and lighting. Researchers at the Organic Semiconductor Centre in the School of Physics and…

Researchers crack sugarcane’s complex genetic code

Sweet success: Scientists created a highly accurate reference genome for one of the most important modern crops and found a rare example of how genes confer disease resistance in plants….

Evolution of the most powerful ocean current on Earth

The Antarctic Circumpolar Current plays an important part in global overturning circulation, the exchange of heat and CO2 between the ocean and atmosphere, and the stability of Antarctica’s ice sheets….

Partners & Sponsors