Spray-Drying Synthesis of Na2FePO4F as Positive Electrode for Na-ion Batteries

The goal of this works is minimized post-treatment of batteries material synthesis, as grinding or carbon addition. We have add during synthesis carbon nanotubes to enhance the conductivity of the phosphate based material Na2FePO4F. This addition of carbon induce a modifications of the cristallisation and lead to impureties. By modifying the attack of iron(0) and adapting the heat treatment we have enhance the purity of the material. We have also compare the influence of the injection mode on the size which is drastically reduce (8micron to 1.5micron); on the electrochemical performance ( 110mAh/g for rotative nozzle, 140mAh/g for the bifluid) and on the oxidation state of the iron in the product analysed by mossbauer spectroscopy (16% of Fe(III) with rotative nozzle; 12% of Fe(III) with the bifluid nozzle).