Imaging of Li distribution in Li-ion batteries by Particle-Induced Gamma Ray Emission using proton microbeam

Mima, Kunioki*; Azuma, Hirozumi*; Yamazaki, Akiyoshi; Kamiya, Tomihiro; Okuda, Chikaaki*; Ukyo, Yoshio*; Kato, Yoshiaki* ; Gonzales, R.*; Soldo, F.*; Perlado, J. M.*; Nishimura, Hiroaki*; Nakai, Sadao*

The micro-meter scale distribution of Li in a positive electrode of a Li-ion battery contains LiNiCoAlMgO (x = 1.050.5) micro particles was imaged by micro-PIGE (Particle-Induced Gamma Ray Emission) technique with the beam diameter of 11.5 m at Takasaki Ion Accelerators for Advanced Radiation Application facility. In the experiments, measurements were made on the cross section of a positive electrode which was disassembled from the Li-ion battery after rapid charging. As a result, we found that the Li concentration distribution is non-uniform along the depth direction as is expected from the Li diffusion velocity and the charging speed of the sample. This results show that the IBMA is a powerful tool for the diagnostics of the Li-ion batteries and also for that of other battery structures under various charge and discharge conditions. Those data are expected to be useful for the R&D of the advanced batteries.