Study On The Preparation And Performance Of Lithium Iron Phosphate Cathode Materials

Lithium-ion batteries have the advantages of high energy d ensity,high operating voltage,and long service life,and widely used in various related fields.However,lithium-ion batteries still have the disadvantages of high production cost,low production efficiency,lack of safety,and easy environmental polluti on.In this paper,Li Fe PO₄ cathode materials with good safety,low cost and environmentally benign are taken as the object of study by different methods.We explored the effects of different synthesis conditions on the materials morphologies and electroche mical properties,which were characterised with XRD,C-S analysis,SEM,particle size analysis,and electrochemical testing.First,Fe PO₄ with different crystal forms,particle sizes and morphologies was obtained by changing the dehydration temperature of Fe PO₄·2H₂O.Afterwards,we investigated the effect of Fe PO ₄ obtained at different temperatures on the synthesized Li Fe PO ₄/C composite.It can be concluded that the change of the dehydration temperature has no obvious effect on the crystal structure and particle morphology of the Li Fe PO ₄/C material.The electrochemical performance of Li Fe PO ₄/C synthesized from Fe PO₄ sample dehydrated at 500 ? is the best.On this basis,we explored the effect of different milling parameters and sintering parameters on the s ynthesis of Li Fe PO₄/C material by the carbothermal reduction method.When ball milling parameters were 0.5?ratio of liquid to solid?for 4 h,and sintering parameters were 150 ? for 1h,300 ? for 2 h,450 ? for 1 h,700 ? for 6 h,the sample showed best electrochemical performance that the capacity could reach 140 m Ah g^-1 at 1C rate and no decay after 100 cycles.In order to further improve the efficiency of synthesis,Li Fe PO ₄/C were synthesized by spray drying and the effects of different spray dry ing parameters on the properties of Li Fe PO ₄/C were studied.The spray-dried materials are all regular micron-sized spherical particles.When the atomizer rotates at 380 rpm,the inlet temperature is 250 ?,the solid content is 20%,the feed rate is 50 rpm,the carbon content is 8 wt.%,and the solvent is deionized water,the material has the best electrochemical performance.