Analysis of LiCoO2 electrodes through principal component analysis of current–voltage datacubes measured using atomic force microscopy

Abstract

This study aimed to reveal the electrical characteristics of the composite electrodes of Li-ion batteries. LiCoO2 electrodes were analyzed using atomic force microscopy, and three-dimensional datasets of current–voltage (I–V) curves (IV-datacubes) were obtained. The IV-datacubes were then analyzed using principal component analysis to determine the typical I–V curve corresponding to each LiCoO2 particle on a statistical basis. Detailed analysis based on the thermionic emission model with series resistance showed that some of the particles exhibited poor electrical contact in the electrode. Overall, the obtained results suggested that our IV-datacube analysis can reveal the characteristics of buried electrical contacts within electrodes, which is otherwise difficult to accomplish using alternative methods. We, therefore, believe that the method presented herein is a promising analytical method for composite electrodes.