Selective sodium-ion diffusion channels in Na2-xFe3(PO4)3 positive electrode for Na-ion batteries

Abstract The electrochemical community around the world is focusing heavily on sodium-ion batteries RD the sodium ion diffusivity is of the order of ~10−11 cm2s−1 and then slightly decreases. This is further confirmed by comparing the calculated sodium diffusion barriers along the individual 1-D channels as well as between the channels. Nevertheless, the exchange current density slowly increases up to x = 1.0 and remains quite constant thereafter. The magnitude of exchange current density is very low suggesting that the interfacial kinetics are the rate limiting factor. The obtained results suggest that Na2-xFe3(PO4)3 could achieve better rate performance with long cycling stability through engineering of the particle morphology and microstructure.