Superior rate performance and structural evolution of O3-type layered NaCrO2 for sodium ion batteries at high temperatures

In order to meet the practical application of sodium ion batteries (SIBs), a low energy consumption method is recommended to synthesize the layered NaCrO 2 cathode materials. Enabled by the larger Na + diffusion coefficients promoted by a proper high temperature, the as-synthesized O3-type NaCrO 2 material shows superior rate performance even at elevated temperatures, exhibiting 47.4 mA h g −1 at 100 C and 60°C. Opposite to the good cyclic capability at room temperature, however, the high-temperature cyclability of NaCrO 2 deteriorates due to the complex irreversible structural evolution in NaCrO 2 during cycling at elevated temperatures. This work boosts the industrial development of layered oxide cathode materials for SIBs with outstanding high-rate performance especially at high temperatures, and in the meantime deepens the understanding of the high-temperature capacity decay mechanism for layered oxide cathode materials.