KR-20260064107-A - LMFP CATHODE ACTIVE MATERIAL, METHOD OF MANUFACTURING THE SAME AND LITHIUM SECONDARY BATTERY INCLUDING THE SAME

Abstract

A lithium iron manganese phosphate cathode active material, a method for manufacturing the same, and a lithium secondary battery containing the same are disclosed. The lithium iron manganese phosphate cathode active material according to the present invention is expressed by the following Formula 1 and satisfies Formula 2. [Equation 1] Li ​ ​ ​ ​ [Equation 2] 0.60 ≤ (D50/BET) × Compressive Density (PD) ≤ 0.70

Inventors

• 박혜림
• 황정욱
• 류제광
• 고수환
• 이승원

Assignees

• (주)포스코퓨처엠

Dates

Publication Date

20260507

Application Date

20241031

Claims (14)

1. A lithium iron manganese phosphate cathode active material expressed by the following Equation 1 and satisfying Equation 2. [Equation 1] Li ​ ​ ​ ​ [Equation 2] 0.60 ≤ (D50/BET) × Compressive Density (PD) ≤ 0.70 (In Equation 2, D50 is the 50% volume particle size (㎛), BET is the BET (Brunauer-Emmett-Teller) specific surface area ( m² /g), and compressive density (PD) is the density (g/cc) when 1.1g of cathode active material powder is fed into a pellet generator with a cross-sectional area of 1.3cm² and pressed with a force of approximately 4 ton/ cm² )
2. In paragraph 1, The above x is 1.09 to 1.12, and is a lithium iron manganese phosphate cathode active material.
3. In paragraph 1, Lithium iron manganese phosphate cathode active material having x/y of 1.06 to 1.08.
4. In paragraph 1, The above lithium iron manganese phosphate cathode active material further comprises Ti, wherein the Ti is included in a molar ratio of 0.005 or less.
5. In paragraph 1, The above lithium manganese phosphate cathode active material is a lithium manganese phosphate cathode active material that further comprises carbon.
6. In paragraph 1, The lithium iron manganese phosphate cathode active material has a BET value of 23 to 26 m² /g, and the lithium iron manganese phosphate cathode active material has a D50 value of 7 to 8 μm.
7. In paragraph 1, The above positive active material is a lithium iron manganese phosphate positive active material in the form of secondary particles.
8. The whole house; and The above-mentioned current collector includes a positive material disposed on one or both sides, and The above-mentioned cathode material is a cathode comprising a cathode active material, a conductive material, and a binder according to any one of claims 1 to 7.
9. A positive electrode comprising a positive electrode active material according to any one of claims 1 to 7; A cathode comprising a cathode active material; and A lithium secondary battery containing an electrolyte.
10. (a) A step of forming a slurry by mixing and grinding a plurality of raw materials and a solvent containing one or more of Li, Mn, Fe, and P; (b) a step of spray-drying the above slurry to form a powder; and (c) a step of preparing an anode active material represented by Formula 1 below by calcining the above powder at 630 to 670°C; [Equation 1] Li ​ ​ ​ ​ A method for manufacturing a lithium iron manganese phosphate cathode active material comprising
11. In Paragraph 10, A method for manufacturing a lithium iron manganese phosphate cathode active material, wherein x is 1.09 to 1.12.
12. In Paragraph 10, A method for manufacturing a lithium iron manganese phosphate cathode active material having x/y of 1.06 to 1.08.
13. In Paragraph 11, A method for manufacturing a lithium iron manganese phosphate cathode active material, wherein, in step (a) above, the plurality of raw materials includes a raw material containing Ti.
14. In Paragraph 13, A method for manufacturing a lithium iron manganese phosphate cathode active material, wherein the above Ti is included in a molar ratio of 0.005 or less.

Description

Lithium Manganese Iron Phosphate Cathode Active Material, Method of Manufacturing the Same, and Lithium Secondary Battery Including the Same The present invention relates to a lithium manganese iron phosphate (LMFP) positive electrode active material. In addition, the present invention relates to a method for manufacturing a lithium manganese iron phosphate cathode active material. In addition, the present invention relates to a lithium secondary battery comprising a lithium iron manganese phosphate positive electrode active material. Lithium iron phosphate (LFP) cathode active material is an olivine-based structure composed of octahedral sites of FeO6 and tetrahedral sites of PO4 , and is a material in which lithium ions are deinserted and inserted through a one-dimensional pathway. LFP cathode active material has a main composition of Li, Fe, and P, and offers a cost advantage due to the lower cost of metal minerals compared to NCA or NCM materials that mainly use Ni and Co. In addition, LFP cathode active material has a stable structure due to strong P-O bonds, resulting in excellent thermal stability as there is no oxygen dissociation at high temperatures during charging, and it also has the advantage of excellent lifespan characteristics. However, LFP cathode active materials have the disadvantage of low energy density due to their low operating voltage (3.4 V vs. Li + /Li). To overcome this drawback, research is currently being conducted on lithium manganese iron phosphate (LMFP) cathode active materials in which manganese (Mn) is substituted for the iron (Fe) sites of LFP cathode active materials. Lithium manganese iron phosphate (LMFP) having an olivine crystal structure has a portion of the iron substituted with manganese compared to lithium iron phosphate (LFP), resulting in improved operating voltage and energy density. However, the substitution of iron with manganese has an adverse effect on stability and conductivity, and may lead to a decrease in capacity development and cycling performance. Figure 1 schematically illustrates a method for manufacturing a lithium iron manganese phosphate cathode active material according to an embodiment of the present invention. The aforementioned objectives, features, and advantages are described in detail below with reference to the attached drawings, thereby enabling those skilled in the art to easily implement the technical concept of the present invention. In describing the present invention, detailed descriptions of known technologies related to the present invention are omitted if it is determined that such descriptions would unnecessarily obscure the essence of the invention. Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the attached drawings. In the drawings, the same reference numerals are used to indicate the same or similar components. Hereinafter, a lithium iron manganese phosphate cathode active material according to some embodiments of the present invention, a method for manufacturing the same, and a lithium secondary battery including the same will be described. Cathode active material for lithium secondary batteries Research is underway on lithium manganese iron phosphate (LMFP) cathode active materials in which manganese (Mn) is substituted for the iron (Fe) in lithium iron phosphate (LFP) cathode active materials. The positive electrode active material according to the present invention relates to such an LMFP-based positive electrode active material. More specifically, the positive electrode active material according to the present invention is expressed by the following Formula 1. [Equation 1] Li​​​​ The molar ratio (x) of lithium may be 0.9 to 1.2. Preferably, the molar ratio (x) of lithium may be 1.09 to 1.12. The lithium iron manganese phosphate cathode active material according to a preferred embodiment of the present invention may exhibit a lithium content that is relatively higher than that of a general lithium iron manganese phosphate cathode active material, with a lithium molar ratio of 1.09 to 1.12. This high lithium ratio increases the amount of energy that a battery cell can store. This means that more energy can be stored for the same volume and weight. In addition, due to the high lithium ratio, the movement of lithium ions becomes smoother, increasing the efficiency of charging and discharging. This can result in reduced energy loss, leading to an increase in the actual usable capacity and lifespan of the battery. The molar ratio (y) of phosphoric acid ( PO₄ ) may be 0.9 to 1.1. The lithium iron manganese phosphate cathode active material according to the present invention may have a lithium molar ratio of 1.09 to 1.12, which may exhibit a relatively higher lithium content than a general lithium iron manganese phosphate cathode active material. Preferably, in the present invention, the molar ratio (x/y) of lithium to phosphoric acid may be 1.06 to 1.08. Wh