In-situ Raman spectroscopy is employed to investigate the valence state variations of nickel and manganese, as well as the local structure change of LiMn1.45Ni0.45M0.1O4 (M = Cr, Co) cathodes (LMN) during galvanostatic charge discharge. Raman spectra are collected between 3.5 and 4.9 V in the wave number range of 100-800 cm(-1). The Raman observations showed that the pristine cathodes of Cr- and Co-doped LMN have essentially the same spectra, and they also have similar evolution patterns during cycling showing their reversible behaviour in the de-lithiation and lithiation processes. The Raman spectra of the pristine cathodes have eleven bands, located at 162, 220, 378, 408, 486, 498, 528, 593, 613, 639 and 672 cm(-1). The bands with wave number <300 cm(-1) are attributed to the translation mode of molecular vibration; the 486, 593 and 639 cm(-1) bands are assigned to the stretching mode of Mn-O bond; and the vibration modes at 408, 498, 528 and 613 cm(-1) originated from the Ni-O bond; The band at 672 cm(-1) is attributed to A(1g) mode of Cr3+-O/Co3+-O. During cycling, several new bands are detected near the end of charge, among which the T-2g(T) band at 170 cm(-1) is attributed to the translation mode of lattice vibration in which the lithium concentration is low, and the T-2g band at 538 cm(-1) is due to the presence of Ni4+-O bond in the crystal structure. The T-2g(T) and T-2g(Ni4+-O) bands are clearly evident at V >= 4.78 (x similar to 0.32) and V >= 4.82 (x similar to 0.28). for Cr- and Co-doped LMN, respectively. (C) 2015 Elsevier B.V. All rights reserved.