New P2 - Na_0.70Mn_0.60Ni_0.30Co_0.10O₂Layered Oxide as Electrode Material for Na-Ion Batteries

Sodium layered oxide, Na 0.70 Mn 0.60 Ni 0.30 Co 0.10 O 2 , with a P2-type structure was synthesized by a co - precipitation method and characterized as positive electrode of sodium batteries. The P2-Na x Mn 0.60 Ni 0.30 Co 0.10 O 2 electrode delivered a high specific capacity of 185 mAh/g in the 1.5–4.3 V range at 1 st cycle at C/20 rate; however, rapid capacity decay is observed. In the 1.7–4.0 V range the capacity is equal to 125 mAh/g with a fading considerably reduced. The rate capability is reasonably good. According to the electrochemical profile, a potential plateau around 4.2 V vs. Na + /Na, meaning a bi-phasic domain, and several voltage drops that could be related to single phase domains in a narrow sodium content range are observed. Even if the capacity decreases when the battery is cycled above 4.0 V, there is no irreversible structural change.