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EP-4152429-B1 - ANODE FOR LITHIUM SECONDARY BATTERY, LITHIUM SECONDARY BATTERY INCLUDING THE SAME AND METHOD OF FABRICATING THE SAME

EP4152429B1EP 4152429 B1EP4152429 B1EP 4152429B1EP-4152429-B1

Inventors

  • JO, BYUNG WOOK
  • PARK, SUNG JUN
  • KANG, BYUNG CHAN
  • KIM, IN HA

Dates

Publication Date
20260513
Application Date
20220826

Claims (14)

  1. An anode (130) for a lithium secondary battery, comprising: an anode current collector (125); and an anode active material layer (120) formed on the anode current collector (125), the anode active material layer (120) comprising a first portion (122) and a second portion (124) which have different porosities from each other and are repeatedly and alternately arranged, wherein the porosities are obtained by X-ray microscopy (XRM), wherein the anode current collector (125) comprises an anode tab (126) protruding from one side of the anode current collector (125), and the first portion (122) and the second portion (124) are alternately and repeatedly arranged along a protruding direction of the anode tab (126) or a direction perpendicular to the protruding direction of the anode tab (126), defined as a width direction of an electrode.
  2. The anode (130) for a lithium secondary battery of claim 1, wherein the first portion (122) and the second portion (124) extend in the direction perpendicular to the protruding direction of the anode tab (126), and are alternately and repeatedly arranged along the protruding direction.
  3. The anode (130) for a lithium secondary battery of claim 2, wherein the first portion (122) and the second portion (124) each has a uniform porosity along the protruding direction.
  4. The anode (130) for a lithium secondary battery of claim 1, wherein the first portion (122) and the second portion (124) have the same thickness.
  5. The anode (130) for a lithium secondary battery of claim 1, wherein Y/X of the anode active material layer (120) is in a range from 0.57 to 0.87, and X is a maximum porosity obtained by an X-ray microscopy (XRM) measurement of the anode active material layer (120) and Y is a minimum porosity obtained by the XRM measurement of the anode active material layer (120).
  6. The anode (130) for a lithium secondary battery of claim 1, wherein the first portion (122) has a higher porosity than that of the second portion (124), and a distance between a point of a maximum porosity in the first portion (122) and a point of a minimum porosity in the second portion (124) is in a range from 0.3 mm to 2 mm.
  7. A lithium secondary battery, comprising: a cathode (100); and the anode (130) for a lithium secondary battery of claim 1 facing the cathode.
  8. A method of fabricating an anode (130) for a lithium secondary battery according to claim 1, comprising: preparing a slurry coating apparatus (200) including a plurality of slits arranged in a grid shape; discharging an anode slurry on a current collector using the slurry coating apparatus (200) to form a preliminary anode active material layer (220); and pressing the preliminary anode active material layer (220) to form an anode active material layer (120) having a uniform thickness.
  9. The method of claim 8, wherein the slurry coating apparatus (200) comprises discharging portions (211) defined as the slits, and a closed portion (212) defined between the discharging portions.
  10. The method of claim 9, wherein each width (W, W') of the discharging portions (211) and the closed portion (212) is in a range from 300 µm to 2,000 µm.
  11. The method of claim 8, wherein B/A is in a range from 0.64 to 0.93, and A is a maximum thickness of the preliminary anode active material layer (220), and B is a minimum thickness of the preliminary anode active material layer (220).
  12. The method of claim 8, wherein the preliminary anode active material layer (220) has a wavy upper profile.
  13. The method according to claim 8, wherein a minimum thickness of the preliminary anode active material layer (220) is greater than the thickness of the anode active material layer (120).
  14. The method according to claim 8, wherein the preliminary anode active material layer (220) has a uniform porosity, and pressing the preliminary anode active material layer (220) comprises forming a first portion (122) and a second portion (124) having different porosities from each other.

Description

CROSS-REFERENCE TO RELATED APPLICATION AND CLAIM OF PRIORITY This application claims priority to Korean Patent Application No. 10-2021-0116212 filed on September 1, 2021 in the Korean Intellectual Property Office (KIPO). BACKGROUND 1. Field The present invention relates to an anode for a lithium secondary battery, a lithium secondary battery including the same, and a method of fabricating the same. More particularly, the present invention relates to an anode including an anode current collector and an anode active material layer, a lithium secondary battery including the same and a method of fabricating the same. 2. Description of the Related Art A secondary battery which can be charged and discharged repeatedly has been widely employed as a power source of a mobile electronic device such as a camcorder, a mobile phone, a laptop computer, etc., according to developments of information and display technologies. Recently, a battery pack including the secondary battery is being developed and applied as a power source of an eco-friendly vehicle. The lithium secondary battery is highlighted due to high operational voltage and energy density per unit weight, a high charging rate, a compact dimension, etc. In a high C-rate rapid charging of the lithium secondary battery, lithium salts may be deposited on a surface of the anode due to an anode resistance to decrease a capacity as charge/discharge cycles are repeated. Accordingly, diffusivity of lithium ions may be preferably increased so as to reduce the anode resistance. To increase the lithium-ion diffusivity in an electrode, a lithium-ion channel in the electrode may be formed. For example, micro-holes or line-shaped channels may be formed in the electrode using a laser etching, an imprinting, etc., so that lithium ions may penetrate or diffuse into the electrode through the channels. However, in the above-described method, ion channels having a fine pattern in the electrode may not be uniformly formed at a high speed, and a production efficiency may also be deteriorated. Additionally, when the fine pattern is formed, burr may be caused on the electrode surface, and an electrode thickness may be increased. Further, pore properties and battery cell performance in the electrode may be deteriorated by the micro-pattern formation. EP 3 817 098 A1 and US 2021/143414 A1 disclose anodes for lithium secondary batteries. SUMMARY According to an aspect of the present invention, there is provided an anode for a lithium secondary battery having improved electrical, physical and chemical properties. According to an aspect of the present invention, there is provided a method of fabricating an anode for a lithium secondary battery having improved stability and reliability. According to an aspect of the present invention, there is provided a lithium secondary battery including the anode for a lithium secondary battery. An anode for a lithium secondary battery according to the present invention is defined in claim 1. It includes an anode current collector, and an anode active material layer formed on the anode current collector. The anode active material layer includes a first portion and a second portion which have different porosities from each other and are repeatedly and alternately arranged. In some embodiments, the first portion and the second portion may each have a uniform porosity along the protruding directior of the anode tab. In some embodiments, the first portion and the second portion may have the same thickness. In some embodiments, Y/X of the anode active material layer may be in a range from 0.57 to 0.87. X is a maximum porosity obtained by an X-ray microscopy (XRM) measurement of the anode active material layer and Y is a minimum porosity obtained by the XRM measurement of the anode active material layer. In some embodiments, the first portion may have a higher porosity than that of the second portion, and a distance between a point of a maximum porosity in the first portion and a point of a minimum porosity in the second portion is in a range from 0.3 mm to 2 mm. A lithium secondary battery includes a cathode and the anode for a lithium secondary battery according to embodiments as described above facing the cathode. In a method of fabricating an anode for a lithium secondary battery according to embodiments of the present invention, a slurry coating apparatus including a plurality of slits arranged in a grid shape is prepared. An anode slurry is discharged on a current collector using the slurry coating apparatus to form a preliminary anode active material layer. The preliminary anode active material layer is pressed to form an anode active material layer having a uniform thickness. In some embodiments, the slurry coating apparatus may include discharging portions defined as the slits, and a closed portion defined between the discharging portions. In some embodiments, each width of the discharging portions and the closed portion may be in a range from 300 µm