Layered Lithium-Sodium Manganese Oxide as a Cathode Material for Lithium Ion Batteries

A mixed lithium-sodium layered manganese oxide, i.e. Na0.6[Li0.2Mn0.8]O2, with a P2 structure, is synthesized using a simple solid-state method. An initial discharge capacity of 247 mAh g[?]1 is achieved for Na0.6[Li0.2Mn0.8]O2/Li cells cycled between 2.0 and 4.8 V at 0.1 C. The average voltage is 3.52 V, which corresponds to an energy density of 878.2 Wh kg[?]1; this is almost 50% higher than that of LiCoO2. During the following cycles, the material undergoes Na/Li exchange and structural changes. Although a new phase similar to Li2MnO3 forms after cycling, the material displays a stable capacity greater than 240 mAh g[?]1 over 30 cycles.