Novel Method of Contrast Improvement Applied to Lithium Ion Battery Electrode Materials Enabling Multi Modal and Super-High Resolution 3D Imaging and Advanced Quantification

Abstract

The authors present for the first time a new methodology of contrast enhancement for multi modal 3D imaging including novel advanced quantification for a commercial Lithium Iron Phosphate (LFP) LiFePO4 cathode. The research aim of this work is to improve the 3D imaging of challenging battery materials by developing methods to increase the contrast between otherwise previously poorly differentiated phases. This is necessary to enable the capture of the real geometry of electrode microstructures, which allows measurement of a wide range of microstructural properties such as pore/particle size distributions, surface area, tortuosity and porosity. Those properties play vital roles in determining the performance of battery electrodes. In this study we present a novel method of sample preparation which is introduced here for the first time for this purpose and found suitable for multi modal imaging, for both FIB-SEM tomography and X-ray tomography. This novel method improves image contrast, which enables higher FIB-SEM resolution (3D image) the highest yet reported for carbon containing electrode materials (e.g. composite LFP cathodes) using FIB-SEM. It means that all the particles are well defined and the size distribution of each phase can be analysed very accurately from the complex 3D electrode microstructure using an advanced novel quantification algorithm.