Flexible Probe for Measuring Local Conductivity Variations in Li-ion Electrode Films

Li-ion battery performance is governed by electronic and ionic properties of the battery. A key metric that characterizes Li-ion battery cell performance is the electronic conductivity of the electrodes, which are metal foils with thin coatings of electrochemically active materials. To accurately measure the spatial variation of electronic conductivity of these electrodes, a micro-four-line probe (mu 4LP) was designed and used to non-destructively measure the properties of commercial-quality Li-ion battery films. This previous research established that the electronic conductivity of film electrodes is not homogeneous throughout the entirety of the deposited film area. In this work, a micro-N-line probe (mu NLP) and a flexible micro-flex-line probe (mu FLP) were developed to improve the non-destructive micro-scale conductivity measurements that we can take. These devices were validated by comparing test results to that of the predecessor, the micro-four-line probe (mu 4LP), on various commercial-quality Li-ion battery electrodes. Results show that there is significant variation in conductivity on a millimeter and even micrometer length scale through the electrode film. Compared to the mu 4LP, the mu NLP and mu FLP also introduce additional measurement configuration possibilities, while providing a more robust design. Researchers and manufacturers can use these probes to identify heterogeneity in their electrodes during the fabrication process, which will lead to the development of better batteries.