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KR-20260064006-A - Negative Electrode Active Material for Li Secondary Battery and the Negative Electrode including the Same

KR20260064006AKR 20260064006 AKR20260064006 AKR 20260064006AKR-20260064006-A

Abstract

A negative electrode material for a lithium secondary battery according to the disclosure comprises spherical natural graphite and amorphous carbon located on top of the spherical natural graphite, and a torque curve, which is a torque value (Nm) according to the volume (mL) of linseed oil dropped onto the negative electrode material obtained under the following conditions, satisfies the following physical property 1: (Conditions) using an oil absorption meter to measure the change in torque according to the volume of the supplied liquid by supplying liquid while stirring the powder, 30 g of negative electrode material, a stirring speed of 126 rpm, a volume of 0.01 mL of linseed oil per drop, a linseed oil dropping speed of 4 mL/min, and a measurement temperature of 25 ℃; (Physical property 1) having two peaks, a first peak and a second peak, in the direction of increasing volume of linseed oil, and in the torque curve, the peak value T1 (Nm) of the first peak is 45 to 60% of the peak value T2 (Nm) of the second peak.

Inventors

  • 최호선
  • 정수연
  • 김수민
  • 이경묵

Assignees

  • (주)포스코퓨처엠

Dates

Publication Date
20260507
Application Date
20241031

Claims (11)

  1. It comprises spherical natural graphite and amorphous carbon located on top of the spherical natural graphite, and A negative electrode material for a lithium secondary battery, wherein the torque curve, which is the torque value (Nm) according to the volume (ml) of linseed oil dropped onto the negative electrode material obtained under the following conditions, satisfies the following physical property 1. (Conditions) Use of an oil absorption meter that measures the change in torque according to the volume of the supplied liquid while stirring the powder, 30 g of cathode material, stirring speed of 126 rpm, volume of 1 drop of 0.01 ml of linseed oil, linseed oil drip rate of 4 ml/min, and measurement temperature of 25°C (Physical Property 1) It has two peaks, a first peak and a second peak, in the direction of increasing volume of linseed oil, and the peak value T1 (Nm) of the first peak is 45 to 60% of the peak value T2 (Nm) of the second peak.
  2. In Article 1, (Physical Property 2) Among the rising curve and the falling curve forming the second peak, there is an intersection point between the rising curve and a straight line having a torque value of T2×0.5 for all linseed oil volumes, and the ratio of the linseed oil volume value Vc at the intersection point to the linseed oil volume value Vp2 where the peak value of the second peak is located is 0.80 to 0.95
  3. In Paragraph 2, A negative electrode material for a lithium secondary battery, wherein the distance between the first peak and the second peak based on the volume of linseed oil is 4 ml or more.
  4. In Paragraph 2, A negative electrode material for a lithium secondary battery, wherein the ratio of the BET specific surface area of the negative electrode material in units of m² /g to the cumulative volume median diameter D50 of the negative electrode material in units of μm is 0.08 to 0.15.
  5. In Article 1, A negative electrode material for a lithium secondary battery having a tap density of 1.00 to 1.30 g/ cm³ .
  6. In Article 1, A negative electrode material for a lithium secondary battery having a composite orientation index defined by the following relationship 1 of 13.0 to 22.0. (Relationship 1) (In Equation 1, R is the intensity ratio (I D / I G ) obtained by dividing I D , the maximum intensity of the D-band peak in the cathode material Raman spectrum, by I G , and I 110 , I 102 , I 103 , and I 002 are the maximum intensities of the (110) peak, (102) peak, (103) peak, and (002) peak in the X-ray diffraction pattern of the cathode material.)
  7. In Article 1, A negative electrode material for a lithium secondary battery, wherein the cumulative volume median diameter D 50 of the negative electrode material is 8 to 25 μm.
  8. In Article 1, A negative electrode material for a lithium secondary battery, wherein the span value of the above negative electrode material is 0.7 to 0.9.
  9. In Article 1, A negative electrode material for a lithium secondary battery, wherein the degree of sphericity of the above negative electrode material is 0.90 to 0.95.
  10. In Article 1, A negative electrode material for a lithium secondary battery, wherein the weight ratio of spherical natural graphite to amorphous carbon contained in the above negative electrode material is 100:1 to 7.
  11. A negative electrode for a lithium secondary battery containing a negative electrode material according to any one of claims 1 to 10.

Description

Negative Electrode Active Material for Lithium Secondary Battery and the Negative Electrode including the Same The present invention relates to a negative electrode material for a lithium secondary battery and a negative electrode for a lithium secondary battery including the same, and more specifically, to a natural graphite-based negative electrode material for a lithium secondary battery. Among the components of a lithium-ion battery, the anode stores lithium ions during charging and plays a crucial role in determining charging speed and battery capacity. Carbon-based active materials are representative commercially used anode materials. Among carbon-based active materials, natural graphite has high cost competitiveness and a higher capacity than artificial graphite, but it has the problem of large irreversible reactions due to exposed edge surfaces, limited lithium ion diffusion paths due to the uniaxial orientation of the graphene layer, resulting in poor high-rate power characteristics, and low electrode density because it is easy to orient in a planar shape on the current collector. To solve these problems, a technology is being developed to mechanically process natural graphite into a spherical shape, densify it by isotropic pressure to remove internal pores of the spherical natural graphite, and then form a carbon coating layer on the surface of the natural graphite. However, densified natural graphite has the problem that its crystallinity decreases due to a large number of defects resulting from mechanical processing and isotropic pressurization. Furthermore, when a carbon coating layer is formed on densified natural graphite, the active surface area in contact with the electrolyte is also reduced, leaving room for improvement in its lifespan and high-rate characteristics. Preferred embodiments of the present invention are described below. However, embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. In addition, embodiments of the present invention are provided to more fully explain the present invention to those with average knowledge in the relevant technical field. In describing the embodiments of the present invention, if it is determined that a detailed description of known technology related to the present invention may unnecessarily obscure the essence of the present invention, such detailed description will be omitted. Furthermore, the terms described below are defined considering their functions in the present invention, and these may vary depending on the intentions or conventions of the user or operator. Therefore, such definitions should be based on the content throughout this specification. The terms used in the detailed description are merely for describing the embodiments of the present invention and should not be limited in any way. Unless explicitly stated otherwise, expressions in the singular form include the meaning of the plural form. In this description, expressions such as “include” or “equipped” are intended to refer to certain characteristics, numbers, steps, actions, elements, parts or combinations thereof, and should not be interpreted to exclude the existence or possibility of one or more other characteristics, numbers, steps, actions, elements, parts or combinations thereof other than those described. Unless otherwise specifically defined in the specification of the present invention, % units mean weight %. Additionally, throughout the specification, when it is said that one part is 'connected' to another part, this includes not only cases where they are 'directly connected,' but also cases where they are 'indirectly connected' with other elements in between. The present invention will be described in detail below through each embodiment or example of the invention. It should be noted that each embodiment or example described in this specification is not limited to a single embodiment or example, but may also be combined with other embodiments or examples. Accordingly, the citation of claims in the patent claims is merely an example of an embodiment, and the technical concept of the present invention should not be interpreted as being limited only to a combination with the cited claims; rather, combinations with various claims are also included within the scope of the technical concept of the present invention. The inventors have continuously conducted research to develop natural graphite-based cathode materials. When natural graphite is mechanically processed to adjust its shape into a spherical form to reduce the uniaxial orientation of the graphene layer and improve crystallographic isotropy, pores remain within the spherical natural graphite due to the limitations of mechanical processing. These internal pores not only reduce the density of the cathode material but also induce significant deformation during rolling for the production of the active mat