Cathode active material including lithium transition metal phosphate particles, preparation method thereof, and lithium secondary battery including the same
View Patent ↗Provided are a cathode active material including lithium transition metal phosphate particles, including a first secondary particle formed by agglomeration of two or more first primary particles, and a second secondary particle formed by agglomeration of two or more second primary particles in the first secondary particle, and a method of preparing the same. Since the cathode active material may include first and second primary particles having different average particle diameters, the exfoliation of the cathode active material from a cathode collector may be minimized and performance characteristics, such as high output characteristics and an increase in available capacity, of a secondary battery may be further improved.
1. A method of preparing a cathode active material, the method comprising:
(i) preparing second secondary particles of lithium transition metal phosphate by primary spray drying and primary sintering a first spray solution including first lithium transition metal phosphate, a first carbon precursor, and water in a spray chamber; and
(ii) preparing first secondary particles of lithium transition metal phosphate respectively including the second secondary particle therein by secondary spray drying and secondary sintering a second spray solution including the second secondary particles, second lithium transition metal phosphate, a second carbon precursor, and water in a spray chamber,
wherein the first secondary particle is formed by agglomeration of two or more first primary particles and is porous, and the second secondary particle is formed by agglomeration of two or more second primary particles whereby a porous portion is created between the first primary particles and the second primary particles, and
wherein the cathode active material further comprises a carbon coating layer on the first primary particles and the second primary particles.
2. The method of claim 1 , wherein the secondary sintering is performed in a temperature range of 700° C. to 800° C.
3. The method of claim 1 , wherein the primary spray drying and the secondary spray drying are performed in a temperature range of 20° C. to 350° C.
4. The method of claim 1 , wherein the first and second carbon precursors are saccharides.
5. The method of claim 4 , wherein the saccharides comprise a solution including any one selected from the group consisting of glucose, fructose, galactose, sucrose, maltose, and lactose, or a mixture of two or more thereof.
6. The method of claim 1 , wherein the first and second carbon precursors are used in an amount of 1 part by weight to 40 parts by weight based on 100 parts by weight of the lithium transition metal phosphate.
7. The method of claim 1 , wherein the first and second spray solutions further comprise a cellulose-based dispersant.
8. The method of claim 7 , wherein the cellulose-based dispersant comprises any one selected from the group consisting of carboxymethyl cellulose, carboxyethyl cellulose, aminoethyl cellulose, and oxyethyl cellulose, or a mixture of two or more thereof.
9. The method of claim 7 , wherein the dispersant is used in an amount of 1 part by weight to 10 parts by weight based on 100 parts by weight of the lithium transition metal phosphate.
10. A method of preparing a cathode active material, the method comprising:
(i) preparing second secondary particles of lithium transition metal phosphate by primary spray drying and primary sintering a first spray solution including first lithium transition metal phosphate, a first carbon precursor, and water in a spray chamber; and
(ii) preparing first secondary particles of lithium transition metal phosphate respectively including the second secondary particle therein by secondary spray drying and secondary sintering a second spray solution including the second secondary particles, second lithium transition metal phosphate, a second carbon precursor, and water in a spray chamber
wherein the first secondary particle is formed by agglomeration of two or more first primary particles, and the second secondary particle is formed by agglomeration of two or more second primary particles,
wherein the cathode active material further comprises a carbon coating layer on the first primary particles and the second primary particles,
wherein a total solid content (TSC) of the second secondary particles is in a range of 25% to 40%.
11. A method of preparing a cathode active material, the method comprising:
(i) preparing second secondary particles of lithium transition metal phosphate by primary spray drying and primary sintering a first spray solution including first lithium transition metal phosphate, a first carbon precursor, and water in a spray chamber; and
(ii) preparing first secondary particles of lithium transition metal phosphate respectively including the second secondary particle therein by secondary spray drying and secondary sintering a second spray solution including the second secondary particles, second lithium transition metal phosphate, a second carbon precursor, and water in a spray chamber
wherein the first secondary particle is formed by agglomeration of two or more first primary particles, and the second secondary particle is formed by agglomeration of two or more second primary particles,
wherein the cathode active material further comprises a carbon coating layer on the first primary particles and the second primary particles,
wherein a total solid content [TSC] of the first secondary particles is in a range of 10% to 20%.
12. A method of preparing a cathode active material, the method comprising:
(i) preparing second secondary particles of lithium transition metal phosphate by primary spray drying and primary sintering a first spray solution including first lithium transition metal phosphate, a first carbon precursor, and water in a spray chamber; and
(ii) preparing first secondary particles of lithium transition metal phosphate respectively including the second secondary particle therein by secondary spray drying and secondary sintering a second spray solution including the second secondary particles, second lithium transition metal phosphate, a second carbon precursor, and water in a spray chamber
wherein the first secondary particle is formed by agglomeration of two or more first primary particles, and the second secondary particle is formed by agglomeration of two or more second primary particles,
wherein the cathode active material further comprises a carbon coating layer on the first primary particles and the second primary particles,
wherein a ratio of the second secondary particles to the second lithium transition metal phosphate is in a range of 1:0.3 to 1:5 as a weight ratio.
13. A method of preparing a cathode active material, the method comprising:
(i) preparing second secondary particles of lithium transition metal phosphate by primary spray drying and primary sintering a first spray solution including first lithium transition metal phosphate, a first carbon precursor, and water in a spray chamber; and
(ii) preparing first secondary particles of lithium transition metal phosphate respectively including the second secondary particle therein by secondary spray drying and secondary sintering a second spray solution including the second secondary particles, second lithium transition metal phosphate, a second carbon precursor, and water in a spray chamber
wherein the first secondary particle is formed by agglomeration of two or more first primary particles, and the second secondary particle is formed by agglomeration of two or more second primary particles
wherein the cathode active material further comprises a carbon coating layer on the first primary particles and the second primary particles,
wherein the primary sintering is performed in a temperature range of 150° C. to 300° C.
14. A method of preparing a cathode active material, the method comprising:
(i) preparing second secondary particles of lithium transition metal phosphate by primary spray drying and primary sintering a first spray solution including first lithium transition metal phosphate, a first carbon precursor, and water in a spray chamber; and
(ii) preparing first secondary particles of lithium transition metal phosphate respectively including the second secondary particle therein by secondary spray drying and secondary sintering a second spray solution including the second secondary particles, second lithium transition metal phosphate, a second carbon precursor, and water in a spray chamber
wherein the first secondary particle is formed by agglomeration of two or more first primary particles, and the second secondary particle is formed by agglomeration of two or more second primary particles,
wherein the cathode active material further comprises a carbon coating layer on the first primary particles and the second primary particles,
wherein the second spray solution is spray-dried in a flow rate range of 10 ml/min to 90 ml/min.