EPR analysis of the local structure of Ni3+ ions in Ni-based electrode materials obtained under high-pressure

X-band and high-frequency EPR spectroscopy was applied to monitor the short-range cation ordering in Ga, Al and Li substituted LiNiO2 with a layered crystal structure. The mixed oxides were obtained by a high-pressure synthesis in an oxygen rich atmosphere. Analysis of the EPR line-width from the X-band experiments together with the values of the g-tensor from the high-frequency EPR experiments permits assesing the local structure of the mixed metal layers. The results obtained show that LiGayNi1–yO2, LiAlyNi1–yO2 and Li1 + xNi1–xO2 are homogeneous solid solutions, whereas the Li1 + xNi1–x–yAlyO2 compositions have rather a complex domain structure of the type (1–a)LiAlyNi1–yO2.aLi[Li1/3Ni2/3]O2.