High Performance P2-Type Na_2/3(Mn_1/2Fe_1/4Co_1/4)O₂ Cathode Material with Superior Rate Capability for Na-Ion Batteries

We designed a new P2 type cathode material, P2-Na 2/3 (Mn 1/2 Fe 1/4 Co 1/4 )O 2 , by mixing transition metals in the TM layer in P2 type layered oxide to prevent the long range ordering of Na or transition metals and create a large single phase region which is conductive to good Na + transport. Futhermore, we suppressed the undesirable monoclinic transition commonly observed in Mn-containing layered oxides by introducing the Co2+/3+ redox couple. As a result, P2-Na 2/3 (Mn 1/2 Fe 1/4 Co 1/4 )O 2 shows so far the largest single phase region and the highest rate performance among layered oxide cathode materials. We believe this work has opened the door for the application of sodium ion batteries in high power energy storage devices.