A new type of Li1−x Fe0.8Ni0.2O2–Li x MnO2 (Mn/(Fe+Ni+Mn)=0.8) material was synthesized at 350°C in air atmosphere using a solid-state reaction. The material had an XRD pattern that closely resembled that of the original Li1−x FeO2–Li x MnO2 (Mn/(Fe+Mn)=0.8) with much reduced impurity peaks. The Li/Li1−x Fe0.8Ni0.2O2–Li x MnO2 cell showed a high initial discharge capacity above 192mAhg−1, which was higher than that of the parent Li/Li1−x FeO2–Li x MnO2 (186mAhg−1). We expected that the increase of initial discharge capacity and the change of shape of discharge curve for the Li/Li1−x Fe0.8Ni0.2O2–Li x MnO2 cell is the result from the redox reaction from Ni2+ to Ni3+ during charge/discharge process. This cell exhibited not only a typical voltage plateau in the 2.8V region, but also an excellent cycle retention rate (96%) up to 45 cycles.