Synthesis of Na3Fe2(PO4)3 with NASICON-Type Structure fromFerrous Oxalate Precursor in the Presence of Colloidal SiliconDioxide

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 to 1.5 V vs Na/Na+. It is shown that the presence of colloidal silicon dioxide helps the main phase crystallization, without entering its structure.