Mg-doped layered oxide cathode for Na-ion batteries

Na-ion batteries (NIBs) are regarding as the optimum complement for Li-ion batteries along with the rapid development of stationary energy storage systems. In order to meet the commercial demands of cathodes for NIBs, O3-type Cu containing layered oxide Na 0.90 Cu 0.22 Fe 0.30 Mn 0.48 O 2 with good comprehensive performance and low-cost element components is very promising for the practical use. However, only part of the Cu 3+ /Cu 2+ redox couple participated in the redox reaction, thus impairing the specific capacity of the cathode materials. Herein, Mg 2+ -doped O3-Na 0.90 Mg 0.08 Cu 0.22 Fe 0.30 Mn 0.40 O 2 layered oxide without Mn 3+ was synthesized successfully, which exhibited improved reversible specific capacity of 118 mAh/g in the voltage range of 2.4–4.0 V at 0.2 C, corresponding to the intercalation/deintercalation of 0.47 Na + (0.1 more than that of Na 0.90 Cu 0.22 Fe 0.30 Mn 0.48 O 2 ). This work demonstrates an important strategy to obtain advanced layered oxide cathodes for NIBs.