The porous network structure of Li-ion battery electrodes has been first studied by combining the X-ray computed tomography (CT) technology and the three-dimensional image processing using medial axis. High resolution X-ray CT images of the electrodes were obtained at the synchrotron facility. Gallium injection technique was utilized to obtain a high contrast CT image for anode, so that the material and void are clearly separated in the further image processing. The tortuosity of voids in x-, y-, and z-directions was calculated after thinning process. The path of Li ion in electrodes is visualized and analyzed by this method. This analysis may accelerate the research and development of Li-ion battery electrode.

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Pt-Ti alloy nanoparticles (NPs) were synthesized over carbon-black supports via a wet-chemistry route. The prepared Pt-Ti NPs were atomically disordered and surrounded by high-index facets to have a spherical form. Controlled vacuum-annealing yielded atomically ordered Pt_0.75Ti_0.25 NPs, which were surrounded by the low-index {111} facets. The spherical Pt-Ti NPs exhibited enhanced activity than pure Pt NPs or even faceted Pt_0.75Ti_0.25 NPs toward the electrochemical oxygen-reduction reaction (ORR).

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The degradation of Pt nanoparticles in the Pt/C electrode catalyst of PEFC (polymer electrolyte fuel cell) during a potential pulse durability test was investigated using identical location field emission scanning electron microscopy (IL-FE-SEM). The degradation was classified as disappearance, migration, precipitation, coalescence, transformation, or other processes, although the size of most particles changed. Furthermore, several combinations of consecutive degradation were first observed. Thus, the IL-FE-SEM observations allowed us to discuss the degradation mechanism semi-quantitatively. Disappearance was recognized if the particle was not observed at the original position or a neighboring position and the frequency of this phenomenon reached a maximum of 10%. Migration was recognized if the particle moved from its original position to a neighboring position. The frequency of migration increased to 10% after the 2,000th pulse, then decreased up to the 5,000th pulse, and increased again after further pulses. Precipitation was observed at a frequency that reached 4% after the 5,000th pulse. Interestingly, migration and transformation were observed to occur following precipitation of Pt particles. Coalescence following migration was found to be a comparatively minor phenomenon. Transformation was the major phenomenon recognized in this study and was frequently observed following coalescence or precipitation of Pt particles.

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