Argonne Lab unveils novel technique to track battery aging in real time

Researchers at Argonne National Laboratory (ANL) have developed and shown a new way to monitor battery degradation using nuclear magnetic resonance (NMR) spectroscopy. This marks the first application of this technique to track chemical changes in commercial pouch cells during operation.

The method allows manufacturers to study battery aging without dismantling cells, providing insights into how electrode materials and electrolytes evolve over months or years of use.

This capability arrives as manufacturers work to integrate silicon anodes into electric vehicle batteries to increase energy density. And, NMR is common in medical imaging, making it a more mature technology, and is a nondestructive and noninvasive technique.

“NMR applications in batteries have been limited until now,” says Argonne chemist Baris Key and one of the authors of the newly published paper on the topic. “This capability could become standard practice for researchers and manufacturers who need to probe battery evolution without cell teardown.”

The research team demonstrated the technique on silicon-anode cells through seven months of cycling. Their findings revealed that lithium atoms become trapped in the anode during charging, forming lithium silicides that reduce the cell’s storage capacity.

Silicon-anode batteries have been used in smartphones, from brands including Honor, OnePlus, Oppo, and more, using batteries developed by leading manufacturer in smartphone cells, TDK.

Testing process

The tests used commercial-grade pouch cells manufactured at Argonne’s Cell Analysis, Modeling and Prototyping facility. These cells match the construction of EV batteries more closely than laboratory prototypes, enabling more accurate aging studies.

The technique detected that adding magnesium salt to the electrolyte reduced trapped lithium formation. This discovery points to potential solutions involving electrolyte additives to extend silicon anode lifespans.

“What we did in our study was like taking MRIs of operating battery cells, except that we didn’t produce images of the cells,” said Evelyna Wang, an Argonne postdoctoral appointee and the study’s main author. ​“Instead, the output was information on how the lithium chemical environment in the cells changed due to charging, discharging, resting and aging.” 

While the initial work focused on silicon anodes, the NMR method can examine other battery technologies, including sodium-ion and solid-state designs. The team plans to expand testing to standard-sized commercial cells.

The findings appear in the Journal of Power Sources under the title “Operando NMR characterization of cycled and calendar aged nanoparticulate silicon anodes for Li-ion batteries.”