Effects of supersonic treatment on the electrochemical properties and crystal structure of LiMn sub(1.5Ni) sub(0).5O sub(4 as a cathode material for Li ion batteries)

The electrochemical properties and crystal structure of LiMn sub(1.5Ni) sub(0).5O sub(4 treated with supersonic waves in an aqueous Ni-containing solution were investigated by performing charge-discharge tests, inductively coupled plasma (ICP) analysis, scanning electron microscopy (SEM), iodometry, X-ray diffraction (XRD), powder neutron diffraction and synchrotron powder XRD. The charge-discharge curve of LiMn) sub(1).5Ni sub(0.5O) sub(4) versus Li/Li super(+ has plateaus at 4.1 and 4.7 V. The 4.1 V versus Li/Li) super(+) plateau due to the oxidation of Mn super(3+/4+ was reduced by the supersonic treatment. During the charge-discharge cycling test at 25 degree C, the supersonic treatment increased the discharge capacity of the 50th cycle. Rietveld analysis of the neutron diffraction patterns revealed that the Ni occupancy of the 4b site in LiMn) sub(1).5Mn sub(0.5O) sub(4), which is mainly occupied by Ni, was increased by the supersonic treatment. This result suggests that Ni super(2+ is partially substituted for Mn) super(3)+/4+ during the supersonic treatment.