Synthesis of Na3Fe2(PO4)3 with NASICON-type structure from ferrous oxalate precursor in the presence of colloidal silicon dioxide

Abstract The widespread presence of sodium in the earth’s crust, the significant stability of its compounds and its great ecological recycling possibilities are all factors that lead researchers to new structures exhibiting ion migration of sodium and high electrochemical potential. The present research shows a new way for Na3Fe2(PO4)3 synthesis with Na Super Ion Conductor structure. The use of ferrous oxalate precursor Na3Fe(C2O4)3 changes the reaction pathway of the iron-phosphate system synthesis and leads to the formation of a structure that allows ion migration that enhances electrochemical charge storage properties. At best the measured capacity was 85 mAh g−1 over a voltage range of 4.2 V–1.5 V versus Na/Na+. It is shown that the presence of colloidal silicon dioxide helps the main phase crystallization, without entering its structure.