Layered cathode-Na0.67Li0.15Ni0.18Mg0.02Mn0.8O2 with P-2/O-3 hybrid phase for high-performance Na-ion batteries

Sodium-ion batteries (SIBs) are regarded as one of the most promising low-cost rechargeable battery technologies because of their abundant reserves and chemical resemblance to lithium. The cathodes with single P-type or O-type structures cannot fully exploit the higher electrochemical performance than the biphasic P/O structures. Therefore, biphasic P-type/O-type structures have attracted more and more attention. Herein, we design a layered cathode-Na0.67Li0.15Ni0.18Mg0.02Mn0.8O2 combined with the P2 and O3 composite phase, which has exceptional long-term stability and tremendous potential. Considering the synergistic effect of the P2 and O3 phases, the complex phase transition in charge and discharge can be effectively inhibited. The layered composite delivers a high reversible capacity of more than 160 mA h/g, with a capacity retention of more than 70 % after 100 cycles at 0.1 C. This research provides a new idea for the development of promising cathodes for SIBs.