Ce doping and CeO2 coating synergistic modification strategy: an effective approach to enhance the electrochemical performance of P2-Na0.67Mn0.5Fe0.5O2

P2-Na0.67Mn0.5Fe0.5O2 has been thought to be one of the potential cathode materials for sodium-ion batteries because of its economic efficiency and high specific capacity (260 mAh g(-1)). However, its practical applicability was limited by rapid capacity degradation and poor rate performance. In this work, the Spherical Ce-modified Na0.67Mn0.5Fe0.5O2 materials were successfully synthesized by the hydrothermal method, which simultaneously realized Ce doping and CeO2 coating. During the high-temperature calcination process, a section of Ce was doped into the lattice, and the stronger Ce-O bonding reduces the TMO2 layer spacing and enhanced the structural stability of the material, in addition, the larger radius of Ce4+ provides a larger interlayer gap for the diffusion of sodium ions and reduces the migration potential of Na+. The other section of Ce was coated on the material surface in the form of CeO2, which protects the electrode from electrolyte erosion and avoids side reactions. Electrochemical tests demonstrated that the 3 wt% Ce-modified FM sample (FM-3) displays good cycling performance and rate capability, with a capacity retention of 61.8% after 100 cycles at 1 C, compared to just 52.6% for the pristine sample (FM-0). Even at 2 C, the FM-3 has a discharge-specific capacity of 99.7 mAh g(-1), whereas FM-0 only has 79.6 mAh g(-1). An efficient modification technique for creating high-performance sodium-ion battery cathode materials is presented in this work.