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Acquiring the quantitative state-of-charge (SOC) distribution of a lithium-ion battery cathode is important to improve the performance of lithium-ion batteries for the application to large-scale devices. The conventional method to obtain SOC distribution, i.e., X-ray absorption spectroscopy (XAS), requires a synchrotron radiation facility, references that are difficult to prepare, and an investigation of the XAS spectra of the references. Herein, we demonstrate that laser-induced breakdown spectroscopy (LIBS) can acquire a quantitative SOC of a charged lithium-ion battery cathode with high accuracy by comparing the SOC values of charged cathodes containing Li2NaV2(PO4)3 as an active material determined by LIBS, XAS, and a charge-discharge curve. We perform LIBS measurements in a reduced argon atmosphere of 1000 Pa and use a calibration curve obtained by measuring the emission intensities at 610.4 nm of the pristine cathode. The SOCs of the charged cathodes agree well with the average SOCs estimated from the charge-discharge curves, whereas those determined by XAS do not. Therefore, LIBS is more suitable to acquire a quantitative SOC distribution of a lithium-ion battery cathode than XAS because LIBS is a laboratory-scale measurement and requires a single simple reference in addition to its high accuracy. [ABSTRACT FROM AUTHOR]

Recent developments in the field of vibration-based power generators have highlighted the advantages of using Fe–Ga alloys; these are excellent-magnetostrictive materials having good mechanical properties, which makes them well suited for use as magnetostrictive elements. A rectangular Fe–Ga element oriented along the 〈100〉 direction in a U-shaped unimorph device produces a higher power generation efficiency than samples with other orientations such as 〈110〉 and 〈111〉. The crystal growth direction of the ingots and plane orientation of the elements have a minimal effect on the power-generation efficiency. The observations of the magnetic domain and elastic properties suggest that the anisotropy in power generation is attributable to the anisotropic magnetic and elastic properties of the Fe–Ga alloy. Thus, a high-performance, vibration-based power generator using the Fe–Ga alloy should be fabricated using elements with a 〈100〉 orientation, cut from a single-crystal Fe–Ga ingot. [ABSTRACT FROM AUTHOR]