Energy Focus: Noninvasive acoustic sensing diagnoses lithium-ion battery health
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phenomenon in a timely manner. Most previous approaches typically relied on postmortem analyses of disassembled cells. What is needed is real-time (in operando) assessment of battery health. In order to develop a nondestructive and more precise diagnostic method, Daniel Steingart of Columbia University and his colleagues at Columbia and Princeton Universities took advantage of the fact that density variations in solids alter the speed of sound as it travels through them. The researchers pinged cycled commercial lithium-ion pouch cells with ultrasonic signals and analyzed the wave forms of the received signals. Intercalation of lithium into the graphite or plating on its surface changes the densities and modulus of the cell and thus alters the length of time it takes for the incident sound wave to return back to the analyzer. This is known as “time of flight.” The researchers identified the cycling and temperature conditions that induced lithium plating and corresponding time-of-flight measurements. They published their findings in a recent issue of Cell Reports Physical Science (doi:10.1016/ j.xcrp.2020.100035). Steingart says, “We think acoustics provide an important complement to existing characterization and diagnostic tools for batteries. The methods
Energy Focus
• VOLUME 45 • JUNE 2020 mrs.org/bulletin Downloaded MRS fromBULLETIN https://www.cambridge.org/core. IP•address: 91.204.14.219, on 31 Aug 2020 at 02:37:58, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1557/mrs.2020.152
NEWS & ANALYSIS MATERIALS NEWS enabling risk assessment, which is difficult to achieve with the EIS analysis.” Unlike other characterization tools, acoustic sensing is noninvasive, diagnoses specific segments of battery cells, and aptly discerns between different degradation mechanisms. This approach will
provide valuable fundamental insight into optimal temperature and charge/discharge regimes for novel battery designs, according to the research team. Most importantly, the required diagnostic equipment is relatively compact and simple. This allows many cells to be tested in the laboratory at
once, and eventually electric transportation vehicles and grid-scale battery banks will stand to benefit from built-in sensors that will provide real-time tracking of battery health and warn about impending degradation or safety concerns. Boris Dyatkin
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