Effect of particle dispersion on electrochemical performance of Prussian blue analogues electrode materials for sodium ion batteries.

ABSTRACT

Prussian blue analogues (PBAs) have advantages such as high voltage and low cost, making them one kind of the promising positive electrode materials for sodium-ion batteries. Particle dispersion is a key physical parameter of electrode materials, and understanding its impact on electrochemical performance is a prerequisite for obtaining high-performance PBAs. In this article, two PBAs samples with different particle dispersion were synthesized through sodium citrate-assisted co-precipitation method by means of staying and stirring. The influence of particle dispersion on electrochemical performance was investigated through polarization curve and AC impedance tests. It was found that PBAs with well-dispersed particles exhibited excellent rate performance, with a capacity of ~120 mAh g-1 at 1 C rate and a capacity retention of 75 % after 100 cycles. The capacity retention rate could reach 63 % at 5 C rate, far higher than that of PBAs samples with poor particle dispersion. From the perspective of electrochemical kinetics analysis, it has been shown that PBAs with well-dispersed particles exhibit smaller electrochemical polarization and faster Na+ diffusion reaction kinetics, which are key factors in achieving excellent rate performance.