Electrolyte reinjection method and reinjectable electrolyte secondary battery

Abstract

The present invention relates to a method for electrolyte reinjection into a secondary battery that permits such reinjection. The electrolyte reinjection method, according to the present invention, consists of a method for reinjecting electrolytes into a secondary battery that has an electrode assembly and an electrolyte contained in a pouch, which comprises: an aluminum foil with a functional hole and a polymer layer stacked on the aluminum foil. The method comprises: a reinjection step consisting of opening the functional hole to inject additional electrolyte into the pouch through said hole; and a sealing step consisting of sealing the functional hole after the reinjection step.

Description

Electrolyte reinjection method and reinjectable electrolyte secondary battery Cross-reference to related request This application claims the benefit of priority of Korean Patent Application No. 10-2020-0182659, filed on December 23, 2020. Technology sector The present invention relates to a bag and a secondary battery comprising the same, and to a method of manufacturing the same. Background of the invention Recently, secondary batteries have been the subject of much research and development because they are rechargeable, unlike primary batteries, and there are possibilities for reducing their size and increasing their capacity. As technological development and the demand for mobile devices increase, the demand for secondary batteries as a power source is also increasing dramatically. Based on the shape of the battery case, secondary batteries are classified as button cell batteries, cylindrical batteries, prismatic batteries, and pouch batteries. In a secondary battery, an electrode array mounted within the battery case has a stacked structure consisting of an electrode and a separator, and it is a chargeable and dischargeable energy-generating element. The electrode assembly can be generally classified into a rolled-sheet type, which is rolled up with a separator between the positive and negative electrodes in the form of a sheet coated with an active material, a stacked type, in which multiple positive and negative electrodes are stacked in sequence with a separator interposed between them, and a stack and fold type, in which stacked-type unit cells are rolled up using a long separator film. Recently, a pouch-type battery, which has a structure in which the stacked or pile-type and folded electrode assembly is incorporated into a pouch-type battery case made of a laminated sheet of aluminum, has received much interest due to its low manufacturing cost, small weight, easy shape change, etc., and its use has gradually increased. However, there is the problem that an electrolyte is consumed during repeated charging and discharging of the secondary battery, and consequently, performance degradation occurs. Examples of background information on the technique can be found in documents KR10-2014-0015647, KR101543494B1, JP2019503058A, KR20170112186A and KR20160090562A. Explanation of the invention Technical problem One aspect of the present invention is to provide a method for reinjecting an electrolyte, whereby the electrolyte is easy to reinject, and a secondary battery capable of being reinjected with an electrolyte. Technical solution A method for reinjecting an electrolyte according to the present invention, as defined in independent claim 1, is a method for reinjecting an electrolyte into a secondary battery in which an electrode assembly and an electrolyte are housed in a pouch. The pouch may comprise an aluminum foil in which a functional orifice is formed, and a polymer layer stacked on top of the aluminum foil. Furthermore, the polymer layer covers the functional orifice of the aluminum foil without filling the functional orifice. The polymer layer further comprises a polymeric material permeable to at least CO and CO2 gases, such that the polymer layer is configured to discharge internal gas. The method comprises a reinjection process of injecting additional electrolyte into the pouch through the functional orifice by opening the functional orifice, and a sealing process of sealing the functional orifice after the reinjection process. Furthermore, a secondary battery capable of being refilled with an electrolyte according to the present invention, as defined in independent claim 12, comprises an electrode assembly, wherein electrodes and separators are stacked alternately to combine with each other, and a pouch in which the electrode assembly is housed, wherein the pouch comprises an aluminum foil in which a functional hole is formed, and a polymer layer laminated with the aluminum foil. Further, the polymer layer covers the functional hole of the aluminum foil without filling the functional hole. Further, the polymer layer comprises a polymer material permeable to at least CO gas and CO2 gas, such that the polymer layer is configured to discharge internal gas. The secondary battery comprises a coating portion provided on an inner circumferential surface of the functional hole in the aluminum foil. Advantageous effects According to the present invention, the secondary battery uses a bag in which the polymer layer is stacked on an aluminum sheet having a functional hole formed therein, so that the electrolyte is easily reinjected through the functional hole. In the secondary battery, the gas inside the bag can penetrate the polymer layer through the functional hole and easily discharge to the outside. Brief description of the drawings FIG. 1 is a plan view illustrating a secondary battery, which applies to a method for reinjecting an electrolyte according to an embodiment of the present invention, in a state prior to an electrode assembly being housed in a bag. FIG.2 is a cross-sectional view taken along line AA in FIG.1. FIG. 3 is a plan view illustrating the secondary battery, which is applied to the method for reinjecting an electrolyte according to an embodiment of the present invention. FIG.4 is a cross-sectional view taken along line BB in FIG.3. FIG. 5 is an enlarged cross-sectional view illustrating area C in FIG. 4. FIG. 6 is a cross-sectional view illustrating a concept of a reinjection process in the method for reinjecting an electrolyte according to an embodiment of the present invention. FIG. 7 is a cross-sectional view illustrating a concept of a sealing process in the method for reinjecting an electrolyte according to an embodiment of the present invention. Preferred embodiment of the invention The object, advantages, and features of the present invention will become clearer through the following embodiments described with reference to the accompanying drawings. It should be noted that identical or similar components in the drawings are designated with the same reference numbers whenever possible, even if they are shown in different drawings. The present invention can be embodied in different ways and should not be interpreted as being limited to the embodiments set forth herein. Furthermore, detailed descriptions of the related prior art that might unnecessarily obscure the subject matter of the present invention are omitted. Electrolyte reinjection method Figure 1 is a plan view illustrating a secondary battery, applied to a method for reinjecting an electrolyte according to an embodiment of the present invention, in a state prior to the placement of an electrode assembly in a pouch. Figure 2 is a cross-sectional view taken along line AA in Figure 1. Figure 3 is a plan view illustrating the secondary battery, applied to the method for reinjecting an electrolyte according to an embodiment of the present invention. Figure 4 is a cross-sectional view taken along line BB in Figure 3. Figure 5 is an enlarged cross-sectional view illustrating area C in Figure 4. Figure 6 is a cross-sectional view illustrating a concept of a reinjection process in the method for reinjecting an electrolyte according to an embodiment of the present invention.Figure 7 is a cross-sectional view illustrating a sealing process concept in the method for reinjecting an electrolyte according to an embodiment of the present invention. Figures 6 and 7 are views illustrating respective examples of the reinjection process and the sealing process concepts by enlarging area C in Figure 4. With reference to Figures 1 to 7, the method for reinjecting an electrolyte into a secondary battery according to an embodiment of the present invention is a method for reinjecting an electrolyte into a secondary battery 100 in which an electrode assembly 120 and an electrolyte are housed in a pouch 110. The pouch 110 comprises an aluminum sheet 113, in which a functional hole 113a is formed, and a polymeric layer 111 and 116 stacked on the aluminum sheet 113. The method comprises a reinjection process of injecting additional electrolyte into the pouch 110 through the functional hole 113a, and a sealing process of sealing the functional hole 113a after the reinjection process. More specifically, with reference to FIGS. 1 to 5, the method for reinjecting an electrolyte into the secondary battery 100 according to an embodiment of the present invention is a method for reinjecting an electrolyte into the secondary battery 100 in which the electrode assembly 120, which is mounted by alternately stacking an electrode and a separator, and an electrolyte are housed in the bag 110. The bag 110 comprises the aluminum sheet 113, in which the functional hole 113a is formed, and the polymeric layers 111 and 116 stacked on the aluminum sheet 113. A coating portion 113b may be formed on an inner circumferential surface of the functional hole 113a in the aluminum sheet 113. The coating portion 113b may comprise an insulating and chemically resistant material. Therefore, after a hole is formed in a portion, corresponding to the functional hole 113a, of the polymer layer 111 and 116 to reinject an electrolyte in the subsequent electrolyte reinjection process, and then sealed through the sealing process, it is possible to prevent the aluminum sheet 113 from oxidizing due to the contact of the electrolyte with the functional hole 113a portion, or it is possible to prevent electric current from being conducted between the electrode assembly 120 and the aluminum sheet 113 through the functional hole 113a.Part 113b coating may comprise, for example, silicone, but the material of Part 113b coating is not necessarily limited to it. With reference to FIGS. 4 and 6, in the reinjection process, an additional electrolyte is injected into the bag 110 through the functional orifice 113a. In the reinjection process, the functional orifice 113a can be opened by means of a tool P in the portion, covering the functional orifice 113a, of the polymer layer 111 and 116. In one example, in the reinjection process, the additional electrolyte can be injected through the functional hole 113a by piercing the portion, which covers the functional hole 113a, of the polymeric layer 111 and 116. In another example, in the reinjection process, the additional electrolyte can be injected through the functional orifice 113a by penetrating an injection needle into the portion, covering the functional orifice 113a, of the polymeric layer 111 and 116. The polymeric layers 111 and 116 may comprise a first polymeric layer 116 and a second polymeric layer 111. The first polymeric layer 116, the aluminum sheet 113, and the second polymeric layer 111 may be stacked in the bag 110 from the inside, where the electrode assembly 120 is housed, to the outside. The first polymeric layer 116 and the second polymeric layer 111 may be formed on both surfaces of the aluminum sheet 113 to cover the functional hole 113a formed in the aluminum sheet 113. The first polymeric layer 116 and the second polymeric layer 111 may each comprise a polymeric material. Accordingly, the first polymeric layer 116 and the second polymeric layer 111, each comprising the gas-permeable polymeric material such as CO and CO2, cover the functional orifice 113a in such a way that the internal gas can be discharged and leakage of the electrolyte through the functional orifice 113a can be prevented.In the reinjection process, the electrolyte can be injected into the bag 110 through the functional orifice 113a by opening portions, covering the functional orifice 113a, of the first polymeric layer 116 and the second polymeric layer 111. In the bag 110, a nylon layer 112 can also be stacked between the aluminum sheet 113 and the second polymeric layer 111. In the reinjection process, the electrolyte can be injected into the bag 110 through the functional orifice 113a by opening portions, covering the functional orifice 113a, of the first polymeric layer 116, the nylon layer 112, and the second polymeric layer 111. In one example, the first polymeric layer 116 may be made of polypropylene (PP), and the second polymeric layer 111 may be made of polyethylene terephthalate (PET). In another example, in the first polymeric layer 116, an inner layer, which houses the electrode assembly 120, may be made of polypropylene (PP), and an outer layer, facing the aluminum sheet 113, may be made of polyphthalamide (PPa). The second polymeric layer 111 may be made of polyethylene terephthalate (PET). With reference to FIGS. 4 and 7, in the sealing process, the functional hole 113a can be sealed after the reinjection process. In the sealing process, the functional hole 113a can be sealed by sealing the portion corresponding to the functional hole 113a, which is open in the second polymeric layer 111. In the sealing process, the portion of the hole corresponding to the functional hole 113a, which is open in the second polymeric layer 111, can be filled with a sealing material R to seal the functional hole 113a. In one example, in the sealing process, the open portion of the second polymeric layer 111 can be sealed using a resin material R. In another example, in the sealing process, the open portion of the second polymeric layer 111 can be sealed using the same material as the second polymeric layer 111. Accordingly, the open portion of the second polymeric layer 111 is sealed using the same material as the second polymeric layer 111, comprising the gas-permeable polymeric material such as CO and CO2, so that the internal gas can be discharged, even though the injection portion is sealed through the sealing process after electrolyte reinjection, and electrolyte leakage through the functional orifice 113a can be prevented. secondary battery with reinjectable electrolyte A secondary battery capable of being reinjected with an electrolyte according to an embodiment of the present invention will now be described. With reference to FIGS. 1 to 4, a secondary battery 100 capable of being reinjected with an electrolyte according to an embodiment of the present invention comprises an electrode assembly 120, which is assembled by alternately stacking an electrode and a separator, and a pouch 110 in which the electrode assembly 120 is housed. The pouch 110 comprises an aluminum sheet 113 and a polymeric layer 111 and 116 laminated with the aluminum sheet 113. A functional hole 113a is formed in the aluminum sheet 113. The secondary battery 100 capable of being reinjected with an electrolyte according to an embodiment of the present invention belongs to the secondary battery 100 to which the method for reinjecting an electrolyte according to the embodiment described above is applied. Therefore, the content common to the embodiment described above will be omitted or briefly stated, and the description of this embodiment will focus on the differences. More specifically, in the secondary battery 100 capable of being reinjected with an electrolyte according to an embodiment of the present invention, the electrode assembly 120 is a chargeable and dischargeable power generating element, and is assembled by alternately stacking an electrode and a separator. The electrode may comprise a positive electrode and a negative electrode, and the positive electrode, the separator, and the negative electrode may be arranged alternately. Furthermore, the electrode assembly 120 may further comprise an electrode conductor 130 connected to one end of the electrode. The electrode assembly 120 may be electrically connected to an external device via the electrode conductor 130. The bag 110 can accommodate the electrode assembly 120. A housing portion, in which the electrode assembly 120 is housed, can be formed within the bag 110. In addition, bag 110 may comprise aluminum sheet 113, and polymeric layer 111 and 116 laminated with aluminum sheet 113. The 113 aluminum sheet can form a layer in a sheet shape of an aluminum material. The functional hole 113a can be formed in the aluminum sheet 113. The functional hole 113a can be formed in the aluminum sheet 113 to have a size of approximately 1-9 mm. The functional hole can be formed to penetrate the aluminum sheet 113 with respect to a stacked direction of the aluminum sheet 113 and the polymeric layer 111 and 116. The functional hole 113a can be formed between the electrode assembly 120 in the bag 110 and an outer circumferential surface of the bag 110. Furthermore, the functional hole 113a can be formed in a portion of aluminum sheet 113 on one side on which the electrode conductor 130 is disposed. The polymeric layer 111 and 116 may comprise a first polymeric layer 116 and a second polymeric layer 111. The first polymeric layer 116 and the second polymeric layer 111 may be formed on both surfaces of the aluminum sheet 113 to cover the functional orifice 113a formed in the aluminum sheet 113. The first polymeric layer 116 and the second polymeric layer 111 may each comprise a polymeric material. Accordingly, the first polymeric layer 116 and the second polymeric layer 111, each comprising a gas-permeable polymeric material such as CO and CO2, cover the functional orifice 113a in such a way that the internal gas can be discharged and leakage of the electrolyte through the functional orifice 113a can be prevented. With reference to FIGS. 4 and 5, a coating part 113b can be provided over an inner circumferential surface of the functional hole 113a in the aluminum sheet 113. Coating part 113b can be applied to cover the entire inner circumferential surface of the functional hole 113a in the aluminum sheet 113. The coating part 113b can comprise an insulating and chemically resistant material. Therefore, after a hole is formed in a portion of the polymeric layer 111 and 116, corresponding to the functional hole 113a, for reinjection of an electrolyte and subsequent sealing, oxidation of the aluminum sheet 113 due to contact of the electrolyte with the functional hole 113a can be prevented, or electrical current can be prevented from being conducted between the electrode assembly and the aluminum sheet 113 through the functional hole 113a.That is, coating portion 113b is formed along the inner circumferential surface of the functional hole 113a so that the electrolyte can be prevented from coming into direct contact with the aluminum sheet 113 when the electrolyte enters the functional hole 113a in the aluminum sheet 113 through the hole portion of the first polymer layer 116 after holes are formed in the portions corresponding to the functional hole 113a of the first polymer layer 116 and the second polymer layer 111. The hole portion of the second polymer layer 111 is then sealed after the electrolyte is reinjected. Furthermore, coating portion 113b is formed along the inner circumferential surface of the functional hole 113a so that the electrode assembly 120 can be prevented from coming into direct contact with the aluminum sheet 113 through the hole portion of the first polymer layer 116. The coating part 113b may comprise, for example, silicone, but the material of the coating part 113b of the present invention is not necessarily limited to it. Furthermore, the first polymeric layer 116, the aluminum sheet 113, and the second polymeric layer 111 can be stacked in the bag 110 from the inside, where the electrode assembly 120 is housed, to the outside. In the bag 110, the first polymeric layer 116, the aluminum sheet 113, and the second polymeric layer 111, each approximately 10–90 µm thick, can be stacked and bonded together. Additionally, in the bag 110, a nylon layer 112 can be stacked between the aluminum sheet 113 and the second polymeric layer 111. The nylon layer 112 is made of a nylon material that allows gas to pass through it. When holes are formed in the portions, corresponding to the functional hole 113a in the aluminum sheet 113, of the first polymeric layer 116 and the second polymeric layer 111 for reinjecting the electrolyte, a corresponding hole can be formed in the nylon layer 112. The second polymeric layer 111 can be made of a polyethylene terephthalate (PET) material. In one example, the first polymeric layer 116 can be made of a polypropylene (PP) material. In another example, in the first polymeric layer 116, an inner layer 115, in which the electrode assembly 120 is housed, can be made of a polypropylene (PP) material, and an outer layer 114, facing the aluminum sheet 113, can be made of a polyphthalamide (PPa) material. With reference to FIG. 3, a sealing part S can be formed on the outer circumferential surface of bag 110 to seal the inside of bag 110. The sealing part S can be formed by thermal fusion of the outer circumferential surface of bag 110 in a third or fourth direction. Although the present invention has been described with reference to the limited embodiments and drawings, the present invention is not limited to them and may be implemented in various ways by persons of ordinary skill in the art to which the present invention belongs, within the technical concept of the present invention. The scope of the present invention is defined by the appended claims. Description of the symbols 100: secondary battery 110: bag 111: second polymer layer 112: nylon layer 113: aluminum sheet 113a: functional orifice 113b: part of coating 116: first polymer layer 120: electrode assembly : electrode conductor

Claims

1. A method for reinjecting an electrolyte into a secondary battery (100) in which an electrode assembly (120) and an electrolyte are housed in a pouch (110), comprising an aluminum sheet (113) in which a functional hole (113a) is formed, and a polymer layer (111, 116) stacked on the aluminum sheet (113), the method comprising: a reinjection process of injecting additional electrolyte into the pouch (110) through the functional hole (113a) by opening the functional hole (113a); and a sealing process of sealing the functional hole (113a) after the reinjection process; characterized in that the polymer layer covers the functional hole of the aluminum sheet without filling the functional hole, and the polymer layer comprises a polymeric material permeable to at least CO gas and CO2 gas, such that the polymer layer is configured to discharge internal gas. 2.The method of claim 1, wherein in the reinjection process, the additional electrolyte is injected through the functional orifice (113a) by piercing a portion, covering the functional orifice (113a), of the polymer layer (111, 116).

3. The method of claim 1, wherein in the reinjection process, the additional electrolyte is injected through the functional orifice (113a) by penetrating an injection needle (P) into a portion, covering the functional orifice (113a), of the polymer layer (111, 116). 4.The method of claim 1, wherein the polymer layer (111, 116) comprises a first polymer layer (116) and a second polymer layer (111), wherein the first polymer layer (116), the aluminum sheet (113), and the second polymer layer (111) are stacked in the bag (110) from an interior, in which the electrode assembly is housed, to an exterior, and in the reinjection process, the electrolyte is injected into the bag (110) through the functional orifice (113a) by opening portions, covering the functional orifice (113a), of the first polymer layer (116) and the second polymer layer (111).

5. The method of claim 4, wherein in the sealing process, the functional hole (113a) is sealed by sealing the portion corresponding to the functional hole (113a) and opening in the second polymeric layer (111). 6.The method of claim 5, wherein in the sealing process, the open portion of the second polymeric layer (111) is sealed using a resin material.

7. The method of claim 5, wherein in the sealing process, the open portion of the second polymeric layer (111) is sealed using the same material as the second polymeric layer (111).

8. The method of claim 4, wherein the first polymeric layer (116) is made of a polypropylene material, PP, and the second polymeric layer (111) is made of a polyethylene terephthalate material, PET.

9. The method of claim 4, wherein in the first polymeric layer (116), an inner layer (115), in which the electrode assembly (120) is housed, is made of a polypropylene material, PP, and an outer layer (114), facing the aluminum foil, is made of a polyphthalamide material, PPa, and the second polymeric layer (111) is made of a polyethylene terephthalate material, PET.

10. The method of claim 1, wherein a coating portion (113b) is formed on an inner circumferential surface of the functional hole (113a) in the aluminum sheet (113).

11. The method of claim 10, wherein the coating portion (113b) comprises an insulating and chemically resistant material. 12.A secondary battery (100), which is capable of being reinjected with an electrolyte, comprising: an electrode assembly (120) in which electrodes and separators are stacked alternately to combine with each other; and a bag (110) housing the electrode assembly, wherein the bag (110) comprises an aluminum sheet (113) in which a functional hole (113a) is formed, and a polymeric layer (111, 116) laminated with the aluminum sheet (113), characterized in that the polymeric layer (111, 116) covers the functional hole (113a) of the aluminum sheet (113) without filling the functional hole (113a), wherein the polymeric layer (111, 116) comprises a polymeric material permeable to at least CO gas and CO2 gas, such that the polymeric layer (111, 116) is configured to discharge internal gas, and a coating portion (113b) provided on an inner circumferential surface of the functional hole (113a) in the aluminum sheet (113). 13.The secondary battery (100) of claim 12, wherein the coating portion (113b) is applied to cover the entire inner circumferential surface of the functional hole (113a) in the aluminum sheet (113).

14. The secondary battery (100) of claim 12, wherein the coating portion (113b) comprises an insulating and chemically resistant material.

15. The secondary battery (100) of claim 12, wherein the coating portion (113b) comprises silicone.

16. The secondary battery (100) of claim 12, wherein the functional hole (113a) penetrates the aluminum sheet (113) with respect to a stacked direction of the aluminum sheet (113) and the polymer layer (111, 116). 17.The secondary battery (100) of claim 12, wherein the polymer layer (111, 116) comprises a first polymer layer (116) and a second polymer layer (111), wherein the first polymer layer (116), the aluminum sheet (113), and the second polymer layer (111) are stacked in the bag (110) from an interior, in which the electrode assembly (120) is housed, to an exterior.

18. The secondary battery (100) of claim 17, wherein the first polymer layer (116) is made of a polypropylene material, PP, and the second polymer layer (111) is made of a polyethylene terephthalate material, PET. 19.The secondary battery (100) of claim 17, wherein in the first polymeric layer (116), an inner layer (115), in which the electrode assembly (120) is housed, is made of a polypropylene material, PP, and an outer layer (114), facing the aluminum sheet (113), is made of a polyphthalamide material, PPa, and the second polymeric layer (111) is made of a polyethylene terephthalate material, PET.

20. The secondary battery (100) of claim 18, wherein the functional hole (113a) is formed between the electrode assembly (120) and an outer circumferential surface of the bag (110) in the bag.

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