Research on P2-type layered cathode materials for sodium-ion batteries

The precursor was synthesized by sol-gel method, and then Na_0.5Ni_0.25Mn_0.75O₂, the P2-type layered positive electrode material for sodium-ion batteries was obtained by high temperature solid phase method. The optimal preparation conditions of the materials were studied.The results showed that the materials prepared by calcinations in ambient atmosphere at 900 ℃ for 16h had the best performance. The results of electron microscope showed that the materials were with a P2-type layered structure, a lamellar morphology, and particles in uniform size. Tests on the electrochemical performance showed that the specific capacity of the first discharge could reach 205 mAh/g and that the initial charge-discharge efficiency was 99.86% at 0.1 C within the voltage range of 1.5~4.2 V. After 60 cycles, the capacity could reach 130 mAh/g and the charge-discharge efficiency was 100%, keeping a capacity retention rate of nearly 65%, and demonstrating good recycling performance.