CN-121986408-A - Pouch-type battery case and lithium secondary battery including the same

Abstract

The pouch-type battery case according to the present invention includes a cup-shaped portion having an accommodating space in which an electrode assembly is accommodated, a plateau portion formed along the circumference of the accommodating space, and a gas discharge portion, wherein the gas discharge portion includes at least one through-hole formed in the cup-shaped portion or the plateau portion and a gas permeable film covering the through-hole, the gas permeable film is sealed in the battery case so as to form a sealing region around the through-hole, and the gas discharge portion has an anti-leakage index (AVI) of 3.0 or less. In the case of satisfying the gas discharge portion of the anti-gassing index, the gas is smoothly discharged due to the relatively low operating pressure, and the durability is excellent due to the high full gassing pressure, and thus a pouch type secondary battery having improved safety and service life can be provided.

Inventors

• LI WEIZHEN
• HUANG ZHIYING
• PU ENSHU
• ZHU HUIYING
• JIN XIANGXUN
• YU HENGJUN

Assignees

• 株式会社LG新能源

Dates

Publication Date

20260505

Application Date

20241122

Priority Date

20231122

Claims (15)

1. 1. A pouch-type battery case, comprising: A cup-shaped portion provided with an accommodation space for accommodating the electrode assembly, a platform portion formed along a circumference of the accommodation portion, and a gas discharge portion, Wherein the gas discharge portions are provided in at least one of the cup-shaped portion or the platform portion, and each of the gas discharge portions includes at least one through hole and a gas permeable membrane covering the through hole, The gas-permeable membrane is sealed to the battery case to form a sealed region around the through-hole, and The illustrated gas discharge portion has an anti-outgassing index (AVI) of 3.0 or less, which is defined by the following equation 1: [ equation 1] AVI = [A h x r h ] / [W s x C h ] Wherein in said equation 1, a h is the total cross-sectional area of the through-hole given as the number of no units (mm 2 ）,r h is the average radius (mm) of the through-hole given as the number of no units, W s is the average width (mm) of the sealing region given as the number of no units, and C h is the total circumference (mm) of the through-hole given as the number of no units.
2. 2. The pouch-type battery case according to claim 1, wherein the anti-outgassing index (AVI) is in the range of 0.10 to 2.50.
3. 3. The pouch type battery case according to claim 1, wherein a ratio of an average width of the sealing region of the gas discharge part to an average radius of the through-hole is 0.45 to 3.00.
4. 4. The pouch-type battery case according to claim 1, wherein a ratio of a total cross-sectional area of the through-holes of the gas discharge portion to a total circumference of the through-holes is 0.25 mm to 2.50 mm.
5. 5. The pouch-type battery case according to claim 1, wherein the gas discharge portion is formed at least one position selected from the platform portion and the cup-shaped portion positioned adjacent to the platform portion without internal contact with the electrode assembly.
6. 6. The pouch-type battery case according to claim 1, wherein the number of the through-holes is in the range of 1 to 6.
7. 7. The pouch-type battery case according to claim 1, wherein the through-hole has a total cross-sectional area (a H ) of 5mm 2 to 25 mm 2 .
8. 8. The pouch-type battery case according to claim 1, wherein the gas-permeable film has a thickness of 80 μm to 500 μm.
9. 9. The pouch-type battery case according to claim 1, wherein the gas-permeable film is provided inside the battery case.
10. 10. The pouch-type battery case according to claim 1, wherein the gas-permeable film comprises an adhesive resin layer in contact with the battery case and a gas-permeable resin layer disposed on the adhesive resin layer.
11. 11. The pouch type battery case according to claim 10, wherein the adhesive resin layer comprises a non-fluorinated polyolefin-based resin.
12. 12. The pouch-type battery case according to claim 10, wherein the breathable resin layer comprises a fluorinated polyolefin-based resin.
13. 13. The pouch type battery case according to claim 10, wherein a ratio (T A /T T ) of the thickness (T A ) of the adhesive resin layer to the thickness (T T ) of the gas-permeable resin layer is in the range of 0.4 to 2.0.
14. 14. The pouch type battery case according to claim 1, wherein the pouch type battery case has a structure in which a base layer, a gas barrier layer, and a sealant layer are sequentially stacked from the outside.
15. 15. A pouch type secondary battery comprising: the pouch type battery case according to claim 1, an electrode lead connected to the electrode assembly and protruding to the outside of the pouch type battery case via the plateau portion, and a lead film disposed between the electrode lead and the pouch type battery case on the plateau portion, Wherein a portion of the platform portion is sealed along a periphery of the cup portion to form a sealed portion.

Description

Pouch-type battery case and lithium secondary battery including the same Technical Field The present invention relates to a pouch type battery case and a pouch type secondary battery including the same, and more particularly, to a pouch type battery case including a gas discharge part exhibiting excellent durability and effective gas discharge performance, and a pouch type secondary battery including the same. Background Secondary batteries are used in various categories including small-sized products such as digital cameras, P-DVDs, MP3 ps, mobile phones, PDAs, portable game devices, electric tools, and electric bicycles, large-sized products requiring high power such as electric vehicles and hybrid vehicles, power storage devices for storing surplus power or renewable energy, and backup power storage devices. Secondary batteries include nickel-cadmium batteries, nickel-hydrogen batteries, lithium ion batteries, and lithium ion polymer batteries. A secondary battery may be manufactured by accommodating electrode assemblies, in which positive electrodes, negative electrodes, and separators interposed therebetween are alternately stacked, in a battery case, injecting an electrolyte, and then sealing the battery case. Secondary batteries are classified into pouch-type secondary batteries and can-type secondary batteries according to the material of the case accommodating the electrode assembly. In particular, the pouch-type battery may be manufactured by press-working a ductile pouch film laminate to form a cup-shaped portion and then accommodating an electrode assembly in an accommodating space inside the cup-shaped portion and sealing the sealing portion. When operating at high temperature, overcharging, or short-circuiting occurs, the pouch-type secondary battery may generate gas inside the pouch. When the gas pressure inside the bag increases, the bag may be deflated to explode or catch fire. In order to overcome the above limitations, a member designed to continuously discharge gas without stopping the operation of the battery is required. Although extensive studies are being conducted to incorporate a valve type gas discharge member for discharging gas generated inside the battery, most valve type gas discharge members are made of heavy materials and require high operating pressure, and thus expansion caused by gas generation cannot generally be solved. Accordingly, efforts are being made to develop a gas discharge member that allows only gas to pass through while preventing migration of moisture and electrolyte by modifying a lead film in a lead portion of an electrode or by punching a hole in a portion of a battery case and sealing the hole with a gas-permeable film. However, in the case of the film that allows only gas to pass therethrough as described above, depending on the material used, when the gas permeability is high, there is a concern that the possibility of liquid permeation becomes high and poor adhesion to the battery case, and when the liquid permeation risk is reduced to zero, the desired level of gas discharge performance cannot be achieved. In addition, dimensional characteristics of elements constituting the gas discharge member cause variations in gas discharge performance, pressure at the start of operation, and pressure at the occurrence of outgassing, and since specific dimensions that may affect the gas discharge performance have not been clearly identified, intensive studies are required to develop a gas discharge member exhibiting excellent performance. Disclosure of Invention Technical problem The present invention has been designed to overcome the above-described limitations, and therefore, an aspect of the present invention provides a pouch-type battery case that facilitates gas discharge and exhibits excellent durability at high internal pressure by defining an anti-outgassing index using a through-hole communicating with the inside and outside of the case and a precise design of a breathable film covering the through-hole, the through-hole and the breathable film forming a gas discharge portion. In addition, the present invention is designed to overcome the above-described limitations, and therefore, another aspect of the present invention provides a pouch type secondary battery exhibiting excellent safety and prolonged service life by applying the above-described pouch type battery case. Technical proposal [1] According to an aspect of the present invention, there is provided a pouch-type battery case including a cup-shaped portion provided with a receiving space for receiving an electrode assembly, a platform portion formed along the circumference of the receiving portion, and gas discharge portions, wherein the gas discharge portions are provided at least one position in the cup-shaped portion and the platform portion, each of the gas discharge portions includes at least one through-hole and a gas permeable film covering the through-hole, the gas permeable film is seal