Li[Cr x Li(1/3−x/3)Mn(2/3−2x/3)]O2 materials with x=0.1, 0.15, and 0.2 are prepared by a solution method. The materials are calcined at 900°C for 12h in air, and then quenched to room temperature. The quenching procedure results in material with improved capacity and rate capability. In fact, layered Li1.27Cr0.2Mn0.53O2 not only shows a good cycle performance, but also exhibits an excellent discharge capacity of around 260mAhg−1. Cyclic voltammetry and a.c. impedance spectroscopy are also employed to characterize the reversibility and reactions of lithium insertion and extraction in Li[Cr x Li(1/3−x/3)Mn(2/3−2x/3)]O2 electrodes.