hamon

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The Li-Ni-Mn-O related layered oxides are one of the promising cathode materials of lithium secondary battery. These materials show the superior characteristics of the low cost and thermal stability. A variety of Li-Ni-Mn-O related materials were synthesized and characterized by neutron diffraction and scattering measurements. Neutron diffraction and scattering measurements can reveal the average and local structures, respectively. For examples, Rietveld analysis using neutron diffraction data clarified that the chemical formula of LiNi_1/2Mn_1/2O₂ can be expressed as [Li_0.92Ni_0.08] _3a [Li_0.08Ni_0.42Mn_0.5] _3bO₂. The pair distribution function, g (r), obtained by neutron scattering data clarified that the Li-O, Ni-O, and Mn-Obondlengths were confirmed to be 2.12Å, 2.08Å, and 1.89Å, respectively, in LiNi_1/2Mn_1/2O₂. In this paper, we report on the reason why the neutron measurements are effective way to investigate the average and local structures of these cathode materials for lithium secondary batteries.

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A 2D-detector and an analyzer had been installed on iNSE neutron spin echo spectrometer for wide-area data acquisition. Since the areas of the 2nd π/2 spin flipper and the last Fresnel coil were not wide enough for a full area measurement, only the center area of the detector had been used. In 2006, we renewed the spin flipper and the Fresnel coils to expand the detection area. To improve the efficiency of the data acquisition, we proposed a novel method for phase correction of NSE signals. Finally, the efficiency of the NSE measurement increased by approximately one order of magnitude.

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