Page 14 - Shimadzu Journal vol.10 Issue1

Materials Science

Polychromatic Simultaneous

WDXRF Spectrometer

— Application to Valence Analysis of

Cathode Materials of Lithium-Ion Batteries

1
Kazuhiro Takahashi , Kenji Sato 2
1 X-ray/Surface Analysis Business Unit, Analytical & Measuring Instruments Division, Shimadzu Corporation
2 Spectroscopic Analysis Group, Advanced Analysis Unit, Technology Research Laboratory, Shimadzu Corporation

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Abstract A polychromatic simultaneous wavelength-dispersive fluorescence (PS-WDXRF) spectrometer is an extremely useful
Xray fluorescence (PS-WDXRF) spectrometer has an ability to measure device for the development of LIB cathode materials because it can
the valence changes of 3d transition metals with high precision in the measure simultaneously the valence changes of 3d transition metals
laboratory. Adjustment and maintenance of the drive mechanism are un-
necessary, and high-precision measurements are possible in a short time with high precision in the laboratory. Adjustment and maintenance
because the optical system has no moving parts and is compact. of the drive mechanism are unnecessary, and high-precision meas-
In this article, an application of the PS-WDXRF spectrometer to a valence urements are possible in a short time because the optical system
analysis of Mn, Co, and Ni, which are the 3d transition metals used as has no moving parts and is compact. A schematic of PS-WDXRF
cathode materials in Li-ion batteries (LIBs), is reported.
is presented in Figure 1. It is composed of an X-ray tube, a slit,
a flat analyzing crystal, and a one-dimensional position-sensitive
X-ray detector. In this optical system, fluorescent X-rays from a
specimen pass through the slit and are dispersed by the flat analyz-
Introduction ing crystal. They are simultaneously detected by different channels
of the detector corresponding to different energies. Because fluo-
Electric vehicles (EVs) are attracting attention worldwide as a means rescent X-rays spread and are incident on the crystal at different
to solve the problems of global warming and oil depletion. The angles, only X-rays that satisfy the Bragg condition at each angle
spread of EVs depends on the development of high-performance are diffracted and incident on the detector. In this approach, all the
secondary batteries. Li-ion batteries (LIBs) are currently the pre- X-rays corresponding to Bragg angles ranging from θ to θ can
L H
ferred option for EVs due to their high energy density, rapid charg- be measured simultaneously. Furthermore, the rotation mechanism
ing, long lifetime, and low cost. In particular, Ni-rich materials with of the specimen eliminates the position dependence of the meas-
a high proportion of Ni instead of expensive Co are suitable for urement point, and the spatially averaged measurement data can
achieving high energy density with low cost. Knowing the va- be obtained.
1−3
lence changes of the 3d transition metals in the LIB cathode materi- The developed PS-WDXRF spectrometer is capable of meas-
als during charging and discharging is important for understanding uring simultaneously the three main elements in LIB cathode ma-
the redox mechanism and improving the performance of LIBs. 4−8 terials: Mn, Co, and Ni. In this report, an application to a valence
A polychromatic simultaneous wavelength-dispersive X-ray analysis of these 3d transition metals is shown.

Shimadzu Journal vol.10 Issue1 13