CN-122029679-A - Pouch type battery case and pouch type secondary battery including the same

Abstract

The pouch-type battery case according to the present invention includes a cup-shaped portion provided with an accommodating space in which an electrode assembly is accommodated, a platform portion formed along the circumference of the accommodating portion, and one or more gas discharge portions. The gas discharge portions are disposed at one or more positions on the cup portion and the land portion, each of the gas discharge portions includes one or more through holes and a gas-permeable film covering the through holes, the gas-permeable film includes an adhesive resin layer and a gas-permeable resin layer disposed on the adhesive resin layer, the gas-permeable film is sealed on the battery case to thereby form a sealed region around the through holes, and each of the gas discharge portions has a Water Blocking Index (WBI) of 2.0 to 10.5. The gas discharge portion satisfying the water blocking index exhibits excellent performance in preventing water from penetrating from the outside and electrolyte from leaking while continuously discharging gas, thereby improving safety and service life of the pouch type secondary battery.

Inventors

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

Assignees

• 株式会社LG新能源

Dates

Publication Date

20260512

Application Date

20241122

Priority Date

20231122

Claims (15)

1. 1. A pouch-type battery case, comprising: A cup-shaped portion having an accommodation space for accommodating the electrode assembly, a platform portion formed along a circumference of the accommodation portion, and at least one gas discharge portion, Wherein the gas discharge portions are provided at least one position of the cup portion and the land 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 includes a binder resin layer and a permeable resin layer disposed on the binder resin layer, and The gas permeable membrane is sealed to the battery case to form a sealed region around the through-hole, and Each gas discharge portion has a Water Blocking Index (WBI) of 2.0 to 10.5, which is indicated by the following equation 1: [ equation 1] WBI = (A S x T F x T T )/(A H x T A x 100) Wherein, in the above equation 1, a S is the area of the sealing region given as the number of no units (mm 2 ）,T F is the total thickness (μm) of the gas-permeable membrane given as the number of no units), T A is the thickness (μm) of the adhesive resin layer given as the number of no units, T T is the thickness (μm) of the permeable resin layer given as the number of no units, and a H is the area of the through holes (mm 2 ) given as the number of no units.
2. 2. The pouch-type battery case according to claim 1, wherein the Water Blocking Index (WBI) is in the range of 2.3 to 10.0.
3. 3. The pouch type battery case according to claim 1, wherein the adhesive resin layer comprises a non-fluorinated polyolefin-based resin.
4. 4. The pouch-type battery case according to claim 1, wherein the permeable resin layer comprises a fluorinated polyolefin-based resin.
5. 5. The pouch-type battery case according to claim 1, wherein the gas permeable film has a thickness (T F ) of 80 to 500 μm.
6. 6. The pouch type battery case according to claim 1, wherein a ratio (T A /T T ) of the thickness (T A ) of the adhesive resin layer to the thickness (T T ) of the permeable resin layer is in the range of 0.4 to 2.0.
7. 7. The pouch type battery case according to claim 1, wherein a ratio (T A /T T ) of the thickness (T A ) of the adhesive resin layer to the thickness (T T ) of the permeable resin layer is in the range of 0.4 to 1.2.
8. 8. The pouch type battery case according to claim 1, wherein the adhesive resin layer has a thickness (T A ) of 20 to 250 μm.
9. 9. The pouch-type battery case according to claim 1, wherein the permeable resin layer has a thickness (T T ) of 30 to 200 μm.
10. 10. The pouch-type battery case according to claim 1, wherein the through-hole has an area (a H ) of 5mm 2 to 25 mm 2 .
11. 11. The pouch-type battery case according to claim 1, wherein the sealing region has an area (a AD ) of 10 mm 2 to 40 mm 2 .
12. 12. 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.
13. 13. The pouch type battery case according to claim 1, wherein the gas discharge part is disposed such that the adhesive resin layer is in contact with the pouch type battery case.
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 pouch type 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 water blocking 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, 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, there is a concern that there is a greater possibility that liquid permeation and poor adhesion to the battery case occur when the gas permeability is high, and that a desired level of gas discharge performance cannot be achieved when the liquid permeation risk is reduced to zero, depending on the material used. In addition, dimensional characteristics of elements constituting the gas discharge member cause variation in gas discharge performance or liquid blocking performance, and since given 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-mentioned limitations, and therefore, an aspect of the present invention provides a pouch-type battery case that exhibits excellent water blocking performance and minimizes electrolyte leakage while also ensuring efficient gas discharge by defining a water blocking index using through holes communicating with the inside and the outside of the case and a design size of a permeable membrane covering the through holes, the through holes and the permeable membrane 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 part for receiving an electrode assembly, a platform part formed along the circumference of the receiving part, and at least one gas discharge part, wherein the gas discharge parts are provided at least one position in the cup-shaped portion and the platform part, each of the gas discharge parts includes at least one through-hole and a gas permeable film covering the through-hole, the gas permeable film includes an adhesive resin layer a