Tomographic 3D analysis of reduction displacement reaction with associated formation of a conductive network in high energy primary batteries

Hybrid Ag₂VO₂PO₄-CF_x battery electrodes with high energy and pulse performance were investigated in regards to their structural and morphological changes during electrochemical discharge. Reduction products of CF_x and Ag₂VO₂PO₄, carbon and Ag⁰, respectively, were identified via bulk laboratory X-ray diffraction and were characterized further by SEM-EDS to identify variations in Ag₂VO₂PO₄-Ag⁰ agglomerate distributions in the electrode. X-ray tomography was used to characterize the statistical formation and redistribution of these agglomerates at a higher discharge state. Using this technique, we observed the agglomerates within the electrode to increase from 20–40 μm³ to larger sizes (>500 μm³) upon discharge. These data were used to rationalize the changes in conductivity of the composite material upon galvanostatic discharge, as determined under high rate pulsatile discharge and impedance spectroscopy. Both volumetric and spatial redistribution of the materials identified in this study provides insight toward the development and understanding of future high energy and high power primary batteries.