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 NaCrO2 cathode materials. Enabled by the larger Na+ diffusion coefficients promoted by a proper high temperature, the as-synthesized O3-type NaCrO2 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 NaCrO2 deteriorates due to the complex irreversible structural evolution in NaCrO2 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.