HIGH PERFORMANCE CATHODE MATERIAL LiFePO4, ITS PRECURSORS AND METHODS OF MAKING THEREOF
AssigneeGuiqing Huang
InventorGuiqing Huang
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Abstract
In one aspect of the invention, methods of synthesizing iron phosphate precursors and lithium iron phosphate active material usable for a lithium secondary battery include the steps of first forming fine particle iron phosphate precursors hydrated and anhydrous, then forming electrode active material lithium iron phosphate with said iron phosphate precursors. The unique methods are generally efficient and cost effective, as well as stable and scalable for a high performance electrode active material with high capacity, good discharge profile, high electronic conductivity, as well as long cycle life.
Claims26
A method for synthesizing fine particle iron phosphate precursors (FP) and their application in producing electrochemically active material lithium iron phosphate (LFP), comprising the steps of;
- (a) Preparing a first solution and a second solution, wherein the first solution comprises iron source compounds mixed in water, and wherein the second solution comprises phosphate source compound mixed in water;
- (b) Adding the second solution into the first solution with stirring in pre-determined molar ratios to form a first mixture;
- (c) Stirring the first mixture for 2 to 5 hours and adjust pH between about 1 to about 6.5 to form second mixture;
- (d) Heating the second mixture to a temperature between about 25° C. to less than or equal to the boiling point for about 1 to about 10 hours to obtain the third mixture;
- (e) Separating solid substance from the third mixture and rinsing it with water to obtain solid substance;
- (f) Drying the solid substance by heating it at a temperature between about 60° C. to about 105° C. for about 2 to about 12 hours to obtain the first fine particle iron phosphate hydrated precursor (FP1);
- (g) Heating FP1 at about 250° C. to about 600° C. for about 2 to about 20 hours to generate the second fine particle iron phosphate anhydrous precursor (FP2);
- (h) Mixing pre-determined molar ratios of a lithium compound and FP precursor (FP1 and/or FP2) in water and/or organic solvent in the present of carbon source compound, at a temperature between about room temperature to less than or equal to the boiling point at atmospheric pressure for about 2 to about 8 hours to form the first lithium iron phosphate precursor (LFP1);
- (i) Sintering the LFP1 in an inert atmosphere at about 300° C. to about 500° C. for about 2 to about 10 hours to form the second lithium iron phosphate precursor (LFP2);
- (j) Sintering the LFP1 or LFP2 in an inert atmosphere first at about 300° C. to about 400° C. for about 2 to about 5 hours then at about 500° C. to about 900° C. for about 2 to about 15 hours, thereby obtaining a nanometer-sized electrochemically active material LFP.
A method for synthesizing a nanometer size lithium iron phosphate active material (LFP) usable for lithium secondary battery, comprising the steps of:
- (a) Mixing a lithium source compound and FP precursor in water or/and organic solvent in the present of carbon source, at a temperature between about room temperature to less than or equal to the boiling point at atmospheric pressure for about 2 to about 8 hours to form the first nanometer-size lithium iron phosphate precursor (LFP1);
- (b) Sintering the LFP1 in an inert atmosphere at about 300° C. to about 400° C. for about 2 to about 10 hours to form the second nanometer-size lithium iron phosphate precursor (LFP2);
- (c) Sintering the LFP1 or/and LFP2 precursor in an inert atmosphere first at about 300° C. to about 400° C. for about 2 to about 5 hours then at about 500° C. to about 900° C. for about 2 to about 15 hours, thereby obtaining a nanometer-size electrochemically active material LFP.
The method of claim 16, wherein the weight ratio of the carbon source material:the iron source material is from 1 to about 45 g per molar.
Dependencies are inferred from the claim text.