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KR-20260064204-A - CATHODE ACTIVE MATERIAL AND LITHIUM SECONDARY BATTERY USING THE SAME

KR20260064204AKR 20260064204 AKR20260064204 AKR 20260064204AKR-20260064204-A

Abstract

The present invention discloses a positive electrode active material with excellent initial discharge capacity and a lithium secondary battery using the same by controlling the distance traveled by Li ions from the volume and dopant content of the (101) plane and (020) plane and the average particle size (D50) of the slurry after grinding the raw material and improving the ion conductivity. The positive electrode active material according to the present invention is characterized by satisfying the following relationship 1. [Relationship 1] 3.1 ≤ [V(101)/V(020)] / [D'ΧD50(WM)] ≤ 5.1 In the above equation 1, V (101) is the total volume of the (101) plane where the Li ion is located, V (020) is the total volume of the (020) plane in the direction of movement of the Li ion, D' is the content of the 1+ dopant (mol%), and D50 (WM) is the average particle size (D50) (μm) measured by a Malvern particle size meter after grinding the raw material.

Inventors

  • 황정욱
  • 류제광
  • 박혜림
  • 고수환
  • 노현국
  • 이승원

Assignees

  • (주)포스코퓨처엠

Dates

Publication Date
20260507
Application Date
20241031

Claims (10)

  1. A positive active material satisfying the following relationship 1. [Relationship 1] 3.1 ≤ [V(101)/V(020)] / [D'ΧD50(WM)] ≤ 5.1 In the above equation 1, V (101) is the total volume of the (101) plane where the Li ion is located, V (020) is the total volume of the (020) plane in the direction of movement of the Li ion, D' is the content of the 1+ dopant (mol%), and D50 (WM) is the average particle size (D50) (μm) measured by a Malvern particle size meter after grinding the raw material.
  2. In paragraph 1, In the above relationship 1, Satisfies the above V(101) = (4/3)π Χ (CS(101)/2) 3 , and The above CS (101) is a positive active material with a total lattice size (nm) of the (101) plane measured by an X-ray diffraction analyzer.
  3. In paragraph 1, In the above relationship 1, Satisfies the above V(020) = (4/3)π Χ (CS(020)/2) 3 , and The above CS (020) is a positive active material with a total lattice size (nm) of the (020) plane measured by an X-ray diffraction analyzer.
  4. In paragraph 1, In the above relationship 1, Satisfies the above V(101) = (4/3)π Χ (CS(101)/2) 3 , and Satisfies the above V(020) = (4/3)π Χ (CS(020)/2) 3 , and The above CS (101) is larger than CS (020), and The difference between the above CS (101) and CS (020) is an anode satisfying 3 or more. Active substance.
  5. In paragraph 1, The above D50(WM) is a positive active material having a diameter of 210 nm or less.
  6. In paragraph 1, A positive active material comprising an LMFP represented by LiMn a Fe b PO 4 (a + b ≤ 1, a > 0, b > 0).
  7. In paragraph 1, The above dopant is a positive active material comprising one or more of Ti and Mg.
  8. In paragraph 1 or 6, A positive electrode active material comprising 0.1 to 0.5 mol% of a dopant with respect to 100 mol% of the total of the above dopants, Mn, and Fe.
  9. In paragraph 1 or 6, Further including carbon coated on the surface of the above LMFP, A positive electrode active material having a carbon content of 1 to 3 weight percent based on 100 weight percent of the total.
  10. A positive electrode comprising a positive electrode active material according to any one of claims 1 to 9; cathode; and A lithium secondary battery containing an electrolyte.

Description

Cathode Active Material and Lithium Secondary Battery Using the Same The present invention relates to a positive electrode active material and a lithium secondary battery using the same. 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 is Li, Fe, and P, and has a cost advantage over NCA or NCM materials that mainly use Ni and Co because the cost of metal minerals is lower. In addition, LFP cathode active materials have the advantage of excellent thermal stability because their structure is stable due to strong P-O bonds, preventing oxygen dissociation at high temperatures during charging. In addition, LFP cathode active materials have excellent lifespan characteristics, and there is a history of many electric vehicles being produced in China using them. However, LFP cathode active materials have the disadvantage of low energy density. 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. Because LMFP cathode active material is rich in manganese compared to LFP cathode active material, it has the advantage of increasing energy density by about 15% as the operating voltage increases. However, LMFP cathode active materials have the disadvantage of lower lithium ion diffusion rate and electrical conductivity compared to LFP cathode active materials, so they are being studied from various perspectives by controlling various factors that can affect electrochemical performance. 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. In the following, the statement that any configuration is placed on the "upper (or lower)" of a component or on the "upper (or lower)" of a component may mean not only that any configuration is placed in contact with the upper (or lower) surface of said component, but also that another configuration may be interposed between said component and any configuration placed on (or below) said component. In addition, where it is stated that one component is "connected," "combined," or "connected" to another component, it should be understood that while the components may be directly connected or connected to each other, another component may be "interposed" between each component, or each component may be "connected," "combined," or "connected" through another component. Hereinafter, a positive electrode active material according to some embodiments of the present invention and a lithium secondary battery using the same will be described. 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. LMFP cathode active material has the disadvantage of lower lithium ion diffusion rate and electrical conductivity compared to LFP cathode active material. Accordingly, research is being conducted from various perspectives by controlling various factors that can affect the electrochemical performance, such as the electrical conductivity of LMFP cathode active materials. After long research, the inventors confirmed that the larger the volume of the (101) plane where the Li ions are located within the LMFP structure, the greater the number of diffusion channels for Li ions within the particle, and the smaller the volume of the (020) plane which is the direction of diffusion of Li ions, the smaller the space for Li ions to move within the crystal plane, thus having an advantage in the initial discharge capacity of the lithium secondary battery. In other words, the number of diffusion channels for Li ions and the distance traveled by Li ions within the crystal are related to the volume of the crystal plane (the three-dimensional Li ion diffusion space), and had a close influence on the initial discharge capacity of the LMFP cathode material performance. First, in order to increase the number of diffusion channels for Li ions, the total volume of the (101) plane must be large. (101) Since the total volume of the plane is spherical,