Alleviation of voltage fade of lithium-rich layered oxide cathodes of Li-ion battery by incorporation of Cr

The voltage fade on lithium-rich layered oxides could be alleviated by substitution of Mn and Ni for Cr. A series of Cr substituted lithium-rich layered oxides, (Li1.2Mn0.6-xNi0.2-xCr2xO2, x = 0, 0.03, 0.065, and 0.1) was prepared by the ethylenediaminetetraacetic acid (EDTA) sol-gel method. For x = 0.03, the reduced voltage fade and a superior capacity retention were obtained, leading to a higher specific energy. When x increased to 0.1, the sample exhibited a comparable voltage fade behavior with the pristine Ni-Mn oxide. The alleviation of the voltage fade was attributed to the suppression of the phase transformation from layer to spinel structures. The reason for this was due to both the reduction of the oxygen loss from the lattice and a decreased content of Mn3+ at the first charge. Because of the combined effect of these two factors, the conversion of layered oxides to spinel was suppressed, resulting in the alleviation of the voltage fade.