Li二次電池正極活物質Li_1.041Ni_0.8Co_0.2O_yの物性，結晶構造と電極特性の熱処理条件依存

抄録

We investigated the dependence of property, crystal and electrode structure and electrode characteristics on heat treatment for Li_1.041Ni_0.8Co_0.2O_y. Li_1.041Ni_0.8Co_0.2O₂ was prepared by solid-state method using performed heat treatment. Crystal structure was determined by X-ray and neutron diffractions using Rietveld analysis. The metal composition of the samples was determined by ICP. Nuclear and electron density images were calculated by MEM / Rietveld analysis using X-ray diffraction. All samples were determined to single phase with a well defined layered structure (R-3m) by XRD, and controlled the composition. From the charge-discharge test after the heat treatment in high P_O2 (450°C, P_O2 2.03 MPa, 48 h) and Ar reduction (600°C, Ar, 48 h) conditions, discharge capacity decreased. From the crystal structure analysis, the cation mixing of 3a (Li site) and 3b (transition metal site), the bond length between 3b and 6c (oxygen site) increased by heat treatment. From the distributions of electron density, the nature of covalent bond of 3b-6c was weakened by heat treatment. It was suggested that these factors should provide an effective electrode properties.