Yiyang Li1
University of Michigan1
Advanced characterization methods including in situ microscopy have often shown substantial heterogeneity and variability upon electrochemical charge and discharge. However, while such methods can uncover qualitative differences in electrochemistry, they do not directly quantify current and voltage. In this work, we utilize the microelectrode array which enables direct measurements of electrochemical current and voltage of individual micron-sized battery particles. After cycling >20 individual NMC-532 particles, we found that, while the specific volumetric capacity of the particles has <2% variability, the exchange current density has >3x variability between the "best" and the "worst" particles. This intrinsic variability is presently not considered in electrochemical models, and can provide opportunities for uncovering structure-property relationships and engineering improved battery particles.