Effect of supersonic-wave treatment in Zn aqueous solution on property, crystal structure and cycle performance of LiMn_(1.5)Ni _(0.5)O_4 as a cathode material for 5 v class Li ion battery

摘要

We focused on LiMn_(1.5)Ni_(0.5)O_4 with the spinel structure, and performed a supersonic-wave treatment in Zn~(2+) aqueous solution and a subsequent heat-treatment at lower temperature than the sintering temperature. From the X-ray diffraction, ICP, potentiometric titration and TEM-EDX measurements, it was indicated that the samples after the treatments had a single phase of the spinel structure and Zn~(2+) was substituted partially for the transition-metals. Such a partial substitution was also suggested by the Rietveld analysis using neutron diffractions. As for these samples, charge-discharge cycle tests were carried out at room temperature and 45 °C. These experiments demonstrated that the treatments in Zn 2+ aqueous solution could improve the cycle performance although they deteriorated first discharge capacities slightly. Such an improvement of the cathode properties may be attributed to the structural change induced by the supersonic-wave treatments.