Pouch-Shaped Battery Case Having Hidden-Type Gas Pocket, Pouch-Shaped Secondary Battery Including the Same, and Battery Module Including the Same

Abstract

A pouch-shaped battery case (and a pouch-shaped secondary battery including the same) includes a hidden-type gas pocket having a folded configuration such that, when gas is generated in the pouch-shaped case, the gas pocket unfolds to form a space for collecting the gas, whereby it is possible to reduce the extent of swelling of the battery when the gas is generated. The gas pocket may be configured so as not to occupy any space in a normal operating state of the battery, such that the gas pocket is unfolded to form the gas reception space only when the gas is generated, whereby it is possible to improve the efficiency of utilization of space in the battery.

Claims

1. A method of forming a pouch-shaped secondary battery, comprising: folding a single laminate sheet at a fold so as to define a pouch-shaped case having an upper portion and a lower portion on opposing sides of the fold, the upper and lower portions being integrally joined by an intermediate portion therebetween, the intermediate portion containing the fold, and the pouch-shaped case receiving and enclosing an electrode assembly between the upper and lower portions; sealing the electrode assembly within the pouch-shaped case by adhering contacting edges of the upper and lower portions to one another along an adhered interface; and contracting a gas pocket enveloped by the intermediate portion of the pouch-shaped case into an initial contracted configuration in which at least a portion of the gas pocket is contracted towards the electrode assembly, wherein the intermediate portion is configured such that, when gas is generated in the pouch-shaped case, the gas pocket expands away from the electrode assembly into an expanded configuration forming an enlarged space for collecting the gas.

2. The method of claim 1, wherein the intermediate portion extends along a first side of the electrode assembly, and wherein the adhering of the contacting edges to one another along the adhered interface is such that a complete perimeter of the pouch-shaped case encircling the electrode assembly in a first plane is closed, the complete perimeter being defined by a combination of the intermediate portion extending along the first side of the electrode assembly and the adhered interface extending along the other sides of the electrode assembly other than the first side.

3. The method of claim 2, wherein the pouch-shaped case defines a first cross sectional area within the first plane when the intermediate portion in the initial contracted configuration, and wherein the intermediate portion is configured such that the pouch-shaped case defines a second cross sectional area within the first plane when the intermediate portion is in the expanded configuration, the second cross sectional area being larger than the first cross sectional area.

4. The method of claim 2, wherein the pouch-shaped case has a planar, quadrangular structure defining the complete perimeter, such that the complete perimeter is defined by the adhered interface along three sides of the quadrangular structure and by the fold along a fourth side of the quadrangular structure.

5. The method of claim 1, wherein the pouch-shaped case comprises a case main body, in which the electrode assembly is received, with the gas pocket being positioned to one side of the case main body, and wherein the step of contracting the gas pocket into the initial configuration comprises bending the gas pocket into tight contact with the case main body.

6. The method of claim 5, wherein bending the gas pocket into tight contact with the case main body comprises bending the gas pocket multiple times into tight contact with the case main body.

7. The method of claim 5, wherein bending the gas pocket into tight contact with the case main body comprises bending the gas pocket into a bellows structure that is in tight contact with the case main body.

8. The method of claim 7, wherein bending the gas pocket into the bellows structure comprises attaching portions of the bellows structure to each other via an adhesive.

9. The method of claim 5, wherein the case main body includes opposing upper and lower surfaces joined together by side surfaces that project transversely to the upper and lower surfaces and extend around a perimeter of the upper and lower surfaces, and wherein bending the gas pocket into tight contact with the case main body comprises bending the gas pocket into tight contact with at least one of the side surfaces of the case main body.

10. The method of claim 9, wherein the gas pocket is connected to the case main body along one of the side surfaces at an intermediate location between the upper and lower surfaces.

11. The method of claim 9, wherein the gas pocket is connected to the case main body along an edge where a first one of the side surfaces meets either the upper surface or the lower surface.

12. The method of claim 5, wherein the case main body includes opposing upper and lower surfaces joined together by side surfaces that project transversely to the upper and lower surfaces and extend around a perimeter of the upper and lower surfaces, and wherein bending the gas pocket into tight contact with the case main body comprises bending the gas pocket into tight contact with the upper surface or the lower surface of the case main body.

13. The method of claim 12, wherein the gas pocket is connected to the case main body along an edge where a first one of the side surfaces meets either the upper surface or the lower surface of the case main body into which the gas pocket is bent into tight contact.

14. The method of claim 1, further comprising contracting a second gas pocket towards the electrode assembly, the second gas pocket being arranged at an opposite side of the pouch-shaped case from the gas pocket enveloped by the intermediate portion.

15. The method of claim 1, wherein the adhering of the contacting edges to one another comprises adhering the contacting edges of the upper and lower portions to one another by thermal welding.

16. A method of forming a battery module, comprising: combining a plurality of pouch-shaped secondary batteries, each of the plurality of pouch-shaped secondary batteries being formed by the method of claim 1.

17. A method of forming a battery pack, comprising: combining a plurality of battery modules, each of the plurality of battery modules being formed by the method of claim 16.

Description

DESCRIPTION OF DRAWINGS

[0026] FIGS. 1 to 4 are views showing a pouch-shaped secondary battery having a hidden-type gas pocket according to a first embodiment of the present invention, wherein

[0027] FIG. 1 is a perspective view,

[0028] FIG. 2 is a sectional view taken along line A-A of FIG. 1,

[0029] FIG. 3 is front views showing the operation of the gas pocket, and

[0030] FIG. 4 is sectional views taken along lines B-B, C-C, and D-D of FIG. 3;

[0031] FIGS. 5 and 6 are views showing a pouch-shaped secondary battery having a hidden-type gas pocket according to a second embodiment of the present invention, wherein

[0032] FIG. 5 is a cross-sectional view, and

[0033] FIG. 6 is sectional views of principal parts showing the operation of the gas pocket;

[0034] FIG. 7 is a cross-sectional view showing a pouch-shaped secondary battery having a hidden-type gas pocket according to a third embodiment of the present invention;

[0035] FIG. 8 is a cross-sectional view showing a pouch-shaped secondary battery having a hidden-type gas pocket according to a fourth embodiment of the present invention;

[0036] FIG. 9 is a cross-sectional view showing a pouch-shaped secondary battery having a hidden-type gas pocket according to a fifth embodiment of the present invention; and

[0037] FIG. 10 is a cross-sectional view showing a pouch-shaped secondary battery having a hidden-type gas pocket according to a sixth embodiment of the present invention.

BEST MODE

[0038] Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

[0039] FIGS. 1 to 4 are views showing a pouch-shaped secondary battery having a hidden-type gas pocket according to a first embodiment of the present invention, wherein FIG. 1 is a perspective view, FIG. 2 is a sectional view taken along line A-A of FIG. 1, FIG. 3 is front views showing the operation of the gas pocket, and FIG. 4 is sectional views taken along lines B-B, C-C, and D-D of FIG. 3.

[0040] As shown in FIGS. 1 to 4, the pouch-shaped secondary battery having the hidden-type gas pocket according to the first embodiment of the present invention includes an electrode assembly 10 and a pouch-shaped case 20 configured to receive the electrode assembly 10. In addition, the secondary battery is configured such that electrode leads 15 are exposed out of the pouch-shaped case 20.

[0041] Here, the electrode assembly 10 is a power-generating element configured to have a structure including a positive electrode, a negative electrode, and a separator interposed between the two electrodes. The electrode assembly 10 may be constructed using a well-known electrode assembly 10, and therefore a detailed description thereof will be omitted.

[0042] The pouch-shaped case 20 may be made of a laminate sheet configured to cover the outside of the electrode assembly 10 in a sealed state. Preferably, the laminate sheet is made of a metal material, such as aluminum.

[0043] The structure in which the electrode assembly 10 is sealed using the pouch-shaped case 20 may be variously constructed. In this embodiment, the pouch-shaped case 20 has a quadrangular sealing structure, since the electrode assembly 10 generally has a quadrangular planar structure.

[0044] This pouch-shaped case 20 is configured to have a structure in which an approximately middle portion thereof is folded, the electrode assembly 10 is located therebetween, and the other open three perimetric surfaces thereof are sealed except for the folded portion. Consequently, the pouch-shaped case 20 covers the upper surface and the lower surface of the electrode assembly 10 in the state in which the electrode assembly 10 is located therein, and the four perimetric surfaces of the pouch-shaped case, which constitute a quadrangular plane, include a single surface 22 that is folded (hereinafter, also referred to as a ‘folded surface’) and three surfaces 24 and 25 that are attached by sealing (hereinafter, also referred to as ‘sealed surfaces’).

[0045] Here, the sealed surfaces 24 and 25 may be portions that are sealed by adhering the overlapping portions of the laminate sheet constituting the pouch-shaped case 20 closely to each other by thermal welding.

[0046] In particular, a gas pocket 30 configured to collect gas generated from the electrode assembly 10 due to various causes is provided at the folded surface 22 of the pouch-shaped case 20. The gas pocket 30 will be described hereinafter in detail with reference to FIGS. 2 to 4.

[0047] Meanwhile, FIG. 1 illustrates the structure in which the electrode leads 15 are installed at opposite ends of the pouch-shaped case 20 so as to be exposed. However, the direction in which the electrode leads 15 are exposed and the number of electrode leads 15 may be variously changed depending on the embodiment conditions. For example, both the electrode leads 15 may be exposed at one end of the pouch-shaped case 20.

[0048] Now, the gas pocket 30 will be described below in detail with reference to FIGS. 2 to 4.

[0049] In this embodiment, the gas pocket 30 is provided at the folded surface 22 of the pouch-shaped case 20. The gas pocket 30 is configured such that the gas pocket 30 is maintained in a folded state at the side surface of the pouch-shaped case 20 and such that, when gas is generated in the pouch-shaped case 20, the gas pocket 30 is unfolded to form a space configured to collect the gas.

[0050] Referring to FIG. 2 and the like, the folded structure of the gas pocket 30 is configured to have a structure in which the gas pocket 30 is provided at the folded surface 22 of the pouch-shaped case 20 connected to a case main body 21, in which the electrode assembly 10 is mounted, in which the gas pocket 30 is formed so as to be bent multiple times, like a rolled structure, in the state in which the folded surface 22 is in tight contact in a double-folded state, and in which the gas pocket 30 is in tight contact with the side surface of the case main body 21 in this state.

[0051] Referring to the figures showing the present embodiment, the gas pocket 30 is configured to have a structure in which the gas pocket 30 is bent two or three times from the middle portion of the side surface of the case main body 21 and is then in tight contact with the side surface of the case main body 21.

[0052] For reference, in all the figures showing the embodiment of the present invention, the folded structure of the gas pocket 30 is somewhat widened. However, the gas pocket 30 is shown as described above in order to clearly show the folded structure thereof. Consequently, it is desirable to understand that the folded portions of the gas pocket 20 are assembled in the state of being in tight contact with each other or with the case main body 21.

[0053] The gas pocket 30 may be configured such that the pouch-shaped case 20 is bent in the state of being simply in tight contact in a double-folded structure and is then in tight contact with the side surface of the case main body 21. As needed, however, the overlapping portions, among the portions constituting the gas pocket 30, may be sealed at low strength, and may then be brought into tight contact with the side surface of the case main body 21. At this time, the sealing strength of the gas pocket 30 may be lower than the sealing strength of the other three sealed surfaces 24 and 25 by a predetermined level such that, when gas is generated in the pouch-shaped case, the sealed portion of the gas pocket 30 is widened to collect the gas.

[0054] The process of collecting the gas generated in the pouch-shaped case using the gas pocket 30 will be described with reference to FIGS. 3 and 4.

[0055] FIGS. 3(a) and 4(a) show the state of the gas pocket 30 in the normal state, i.e. when no gas is generated. The gas pocket 30 is in tight contact with the side surface of the case main body 21 in an initially assembled state, i.e. in a folded state. At this time, the gas pocket 30 occupies only the external volume corresponding to the size of the laminate sheet that is bent multiple times and is then in tight contact, whereby the overall size of the battery is scarcely increased.

[0056] When gas is generated in the battery in the state in which the gas pocket 30 is folded as described above, as shown in FIGS. 3(b) and 4(b), the gas is introduced into the gas pocket 30, whereby the folded gas pocket 30 starts to be unfolded. In the figures, the state in which the gas pocket 30 is unfolded in a straight line is illustrated for the sake of convenience. However, the gas pocket 30 may be unfolded in various shapes depending on several conditions. For example, the gas pocket 30 may expand while being unfolded from the entrance thereof, or the bent portion of the gas pocket 30 may be unfolded later.

[0057] Subsequently, when gas is continuously generated in the battery, the gas pocket 30 continuously swells. When the gas pocket 30 fully swells, as shown in FIGS. 3(c) and 4(c), the gas pocket 30 expands at the side surface of the battery to form a maximum gas collection space S.

[0058] The maximum gas collection space S in the gas pocket 30 may be appropriately set depending on embodiment conditions. By the provision of the gas pocket 30, it is possible to minimize the deformation of the remaining portion of the battery, excluding the portion of the battery at which the gas pocket is located, when gas is generated in the battery. In particular, it is possible to sufficiently secure the gas collection space, whereby it is possible to prevent explosion of the battery.

[0059] Hereinafter, various embodiments of the gas pocket according to the present invention will be described. For reference, components of the following embodiments that are identical or similar to the components of the first embodiment are denoted by the same reference numerals, a duplicate description thereof will be omitted if possible, and a description will be given based on components of the following embodiments that are different from the components of the first embodiment.

[0060] FIGS. 5 and 6 are views showing a pouch-shaped secondary battery having a hidden-type gas pocket according to a second embodiment of the present invention, wherein FIG. 5 is a cross-sectional view and FIG. 6 is sectional views of principal parts showing the operation of the gas pocket.

[0061] In the first embodiment of the present invention previously described, the gas pocket 30 is provided only at the folded portion of the pouch-shaped case 20, i.e. the folded surface 22. In the second embodiment of the present invention, however, the construction in which the gas pocket 30 may also be formed at the sealed portion of the pouch-shaped case 20, i.e. the sealed surface 24, is shown.

[0062] That is, referring to FIGS. 5 and 6, the gas pocket 30 according to the second embodiment of the present invention may be provided at opposite sides of the pouch-shaped case 20. At this time, since the one side surface of the pouch-shaped case 20 is the folded surface 22 and the other side surface of the pouch-shaped case 20 is the sealed surface 24, a gas pocket 31 at the folded surface 22 may be configured as in the first embodiment, which was previously described, and a gas pocket 32 at the sealed surface 24 may be configured such that only the ends of the double-folded portions of the gas pocket are joined by sealing and the remainder of the double-folded portions of the gas pocket are folded in the state of being in tight contact with each other in order to constitute the gas pocket 30.

[0063] Here, it may be considered that the sealed surface 24, at which the gas pocket 32 is formed, is formed so as to have a smaller width of the sealing attachment surface than the other sealed surfaces 25 (see FIG. 1), at which no gas pocket 30 is formed. This serves to enlarge the gas collection space of the gas pocket 32 while the sealing area thereof is minimized.

[0064] FIGS. 6(a), 6(b), and 6(c) sequentially show the folded and assembled state of the gas pocket 32, the state in which the gas pocket 32 starts to be unfolded, and the maximum gas collection state of the gas pocket 32.

[0065] In the structure in which the gas pocket 32 is also formed at the sealed surface 24 of the pouch-shaped case 20, as described above, the gas pocket 30 may not be formed at the folded surface 22 of the pouch-shaped case 20, and the gas pocket 32 may be formed at only the sealed surface 24 of the pouch-shaped case 20. In addition, in the case in which the pouch-shaped case 20 is constituted by two laminate sheets and thus all surfaces of the pouch-shaped case are attached to each other by sealing without being folded, the gas pocket 32 shown in FIG. 6(a) may be provided at at least one sealed surface of the pouch-shaped case.

[0066] FIG. 7 is a cross-sectional view showing a pouch-shaped secondary battery having a hidden-type gas pocket according to a third embodiment of the present invention. Unlike the previously described first and second embodiments of the present invention, in each of which the gas pocket 30 starts to be formed from the middle portion of the side surface of the battery, this embodiment is configured to have a structure in which a gas pocket 30 starts to be formed at the corner at which the side surface of the pouch-shaped case 20 meets another surface (the upper surface or the lower surface) of the pouch-shaped case and is then folded so as to cover the side surface of the battery.

[0067] The gas pocket 30 (31a and 32a) may be formed at one of the opposite side surfaces of the battery.

[0068] The other components of this embodiment may be configured so as to be identical or similar to the components of the embodiments that were previously described, and therefore a duplicate description thereof will be omitted.

[0069] FIG. 8 is a cross-sectional view showing a pouch-shaped secondary battery having a hidden-type gas pocket according to a fourth embodiment of the present invention. This embodiment is similar in construction to the third embodiment, except that, in the case in which sealed surfaces 24 are formed at both opposite sides of the battery, a gas pocket 32a is provided at each of the sealed surfaces 24.

[0070] In addition, the opposite gas pockets 32a start to be formed from opposite sides in the diagonal direction.

[0071] FIG. 9 is a cross-sectional view showing a pouch-shaped secondary battery having a hidden-type gas pocket according to a fifth embodiment of the present invention. Unlike the embodiments previously described, a gas pocket 30 is formed as the result of being bent toward the upper surface or the lower surface of the battery, rather than toward the side surface of the battery.

[0072] In this embodiment, the gas pocket 30 (33 and 34) may be formed at only one of the opposite sides of the battery.

[0073] FIG. 10 is a cross-sectional view showing a pouch-shaped secondary battery having a hidden-type gas pocket according to a sixth embodiment of the present invention. This embodiment shows the construction in which a gas pocket 30 is formed at the side surface of the battery so as to have a bellows structure.

[0074] In this embodiment, a gas pocket 35 having the same structure may be formed at the sealed surface of the battery, or the gas pocket 35 may be formed at opposite sides of the battery.

[0075] In addition, since the gas pocket 35 is formed so as to have a bellows structure, bellows parts constituting the bellows structure may be attached to each other via an adhesive member such that the gas pocket 35 is stably fixed in tight contact with the side surface of the battery before gas is generated.

[0076] Meanwhile, a battery module may be configured to include one or more pouch-shaped secondary batteries described above. The battery module is configured to include at least one pouch-shaped secondary battery cell. A plurality of pouch-shaped secondary battery cells may be combined in order to constitute the battery module. In addition, a plurality of battery modules may be combined in order to manufacture a battery pack.

[0077] The technical ideas described with reference to the above-described embodiments of the present invention may be embodied independently or in a combined state. In addition, although the present invention has been described with reference to the embodiments disclosed in the drawings and the detailed description of the invention, the embodiments are merely illustrative. Those skilled in the art to which the present invention pertains will appreciate that various modifications and other equivalent embodiments can be devised based on the embodiments described above. Therefore, the technical protection scope of the present invention is to be defined by the appended claims.