The service life of lithium-ion batteries is altered, among other things, by the formation of lithium metal on the graphite-based negative electrode (a phenomenon known as lithium-plating). To better understand the mechanisms leading to this electrode alteration, researchers at Liten, a CEA Tech institute, in collaboration with CEA-IRIG, have set up a lithium NMR (Nuclear Magnetic Resonance) characterization methodology to detect lithium metal formation in real time.
Until now, this type of characterization has been carried out on electrode samples extracted from post-mortem electrochemical cells, in ex-situ mode. However, lithium deposition continues to evolve even after the battery cell has ceased operating. CEA researchers therefore developed an experimental cell with a design similar to that of commercially available cells, but with a reduced format to enable its insertion into the NMR coil, itself adapted for the occasion.
Several operando tests were carried out under different experimental conditions. The positive results obtained will enable us to better understand the mechanisms of lithium metal formation on the negative electrode, and to determine charging protocols that minimize this inconvenience. This information will then be integrated into the BMS (battery management system) to extend battery life, or enable the design of electrodes less sensitive to this degrading phenomenon.
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