Pouch-shaped secondary battery including heat transfer member connected to metal layer of laminate sheet

Abstract

Disclosed herein is a pouch-shaped secondary battery including a laminate sheet including an outer coating layer, a metal layer, and an inner adhesive layer, an electrode assembly, an electrolytic solution, and a heat transfer member connecting the electrode assembly to the metal layer of the laminate sheet, wherein the laminate sheet extends around the electrode assembly, the electrolytic solution, and the heat transfer member.

Claims

1. A pouch-shaped secondary battery, comprising: a laminate sheet comprising an outer coating layer, a metal layer, and an inner adhesive layer; an electrode assembly; an electrolytic solution; and a heat transfer member contacting a non-coated surface of an outermost electrode of the electrode assembly and the metal layer of the laminate sheet, the heat transfer member comprising a main body defining a planar surface and a protrusion extending perpendicularly from the planar surface, wherein the outer coating layer and the metal layer of the laminate sheet each extend around the electrode assembly, the electrolytic solution, and the heat transfer member.

2. The pouch-shaped secondary battery according to claim 1, wherein the heat transfer member is attached to the laminate sheet.

3. The pouch-shaped secondary battery according to claim 1, wherein the heat transfer member is made of a metal that exhibits thermal conductivity.

4. The pouch-shaped secondary battery according to claim 1, wherein the heat transfer member is made of at least one selected from a group consisting of: aluminum (Al), copper (Cu), silver (Ag), gold (Au), nickel (Ni), tungsten (W), carbon (C), and iron (Fe).

5. The pouch-shaped secondary battery according to claim 1, wherein the electrode assembly is at least one selected from a group consisting of: a stacked type electrode assembly, a stacked/folded type electrode assembly, and a laminated/stacked type electrode assembly.

6. The pouch-shaped secondary battery according to claim 5, wherein outermost electrode is a first outermost electrode at a first end of the electrode assembly, the electrode assembly has a second outermost electrode at a second end of the electrode assembly opposite the first end, and the first outermost electrode and the second outermost electrode have a same polarity.

7. The pouch-shaped secondary battery according to claim 5, wherein outermost electrodes of the electrode assembly have different polarities.

8. The pouch-shaped secondary battery according to claim 1, wherein the protrusion extends through the inner adhesive layer of the laminate sheet.

9. The pouch-shaped secondary battery according to claim 8, wherein the protrusion comprises a plurality of individual protrusions arranged along the main body of the heat transfer member at uniform intervals.

10. The pouch-shaped secondary battery according to claim 8, wherein a height of the protrusion is 100% to 120% of a thickness of the inner adhesive layer of the laminate sheet.

11. The pouch-shaped secondary battery according to claim 8, wherein the protrusion has a height ranging from 20 μm to 140 μm.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a side sectional view showing an electrode assembly according to an embodiment of the present invention.

(2) FIG. 2 is a partial exploded perspective view showing a laminate sheet, a heat transfer member, and an electrode according to an embodiment of the present invention.

(3) FIG. 3 is a partial side sectional view of the laminate sheet, the heat transfer member, and the electrode shown in FIG. 2.

(4) FIG. 4 is a partial exploded perspective view showing a laminate sheet, heat transfer members, and an electrode according to another embodiment of the present invention.

(5) FIG. 5 is a partial side sectional view of the laminate sheet, the heat transfer members, and the electrode shown in FIG. 4.

BEST MODE

(6) Now, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings such that the preferred embodiments of the present invention can be easily implemented by a person having ordinary skill in the art to which the present invention pertains. In describing the principle of operation of the preferred embodiments of the present invention in detail, however, a detailed description of known functions and configurations incorporated herein will be omitted when the same may obscure the subject matter of the present invention.

(7) Wherever possible, the same reference numbers will be used throughout the drawings to refer to parts that perform similar functions or operations. Meanwhile, in the case in which one part is ‘connected’ to another part in the following description of the present invention, not only may the one part be directly connected to the another part, but also, the one part may be indirectly connected to the another part via a further part. In addition, that a certain element is ‘included’ means that other elements are not excluded, but may be further included unless mentioned otherwise.

(8) Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

(9) FIG. 1 is a side sectional view schematically showing an electrode assembly that is used in a pouch-shaped secondary battery according to the present invention.

(10) Referring to FIG. 1, the electrode assembly, denoted by reference numeral 100, is a stacked type electrode assembly configured to have a structure in which positive electrodes, each of which is configured such that a positive electrode active material 101 is coated on one surface or both surfaces of a positive electrode current collector 102, and negative electrodes, each of which is configured such that a negative electrode active material 103 is coated on one surface or both surfaces of a negative electrode current collector 104, are stacked in the state in which separators 110 are interposed respectively between the positive electrodes and the negative electrodes.

(11) The uppermost electrode of the electrode assembly 100 is a negative electrode, and the lowermost electrode of the electrode assembly 100 is a positive electrode. Alternatively, the outermost electrodes of the electrode assembly 100 may be electrodes having the same polarity, for example, positive electrodes or negative electrodes.

(12) The uppermost electrode of the electrode assembly 100 is a single-sided negative electrode, which is configured such that a negative electrode active material 103 is coated only on the inner surface of a negative electrode current collector 104, and the lowermost electrode of the electrode assembly 100 is a single-sided positive electrode, which is configured such that a positive electrode active material 101 is coated only on the inner surface of a positive electrode current collector 102. Electrodes of the electrode assembly 100 other than the outermost electrodes are double-sided electrodes, each of which is configured such that an electrode active material is coated on both surfaces of an electrode current collector.

(13) Since the electrode current collector, which is made of a metal material, is located at the outermost side of the electrode assembly that faces a heat transfer member, as described above, thermal energy from the electrode assembly may rapidly move toward a pouch-shaped battery case via the heat transfer member.

(14) Alternatively, in the case in which non-coated electrodes having no electrode active material coated thereon are used as the outermost electrodes, a laminated/stacked type electrode assembly or a stacked/folded type electrode assembly may be used instead of the stacked type electrode assembly 100.

(15) FIG. 2 is a partial exploded perspective view schematically showing a laminate sheet, a heat transfer member, and an electrode according to an embodiment of the present invention, and FIG. 3 is a side sectional view schematically showing the state in which the laminate sheet, the heat transfer member, and the electrode shown in FIG. 2 are coupled to each other.

(16) Referring to FIGS. 2 and 3, the laminate sheet, denoted by reference numeral 210, is configured to have a layered structure in which an outer coating layer 201, a metal layer 202, and an inner adhesive layer 203 are sequentially stacked. The inner surface of the laminate sheet 210 faces the heat transfer member, denoted by reference numeral 220. A flat type main body 221 of the heat transfer member 220 is located between the inner adhesive layer 203 of the laminate sheet 210 and the electrode, denoted by reference numeral 234. Protrusions 222 of the heat transfer member 220 contact the metal layer 202 of the laminate sheet 210 through the inner adhesive layer 203.

(17) Each of the protrusions 222 is shown as being configured to have a rectangular parallelepiped structure. Alternatively, the tip of each of the protrusions 222 that is adjacent to the metal layer may be configured to have a hemispherical structure, each of the protrusions 222 may be generally configured to have a triangular pyramidal structure, or each of the protrusions 222 may be configured to have a linear structure. Preferably, however, the surface of each of the protrusions 222 that contacts the metal layer of the laminate sheet is as large as possible in order to improve heat dissipation efficiency.

(18) The height h2 of each of the protrusions 222 is shown as being the same as the thickness h1 of the inner adhesive layer 203. Alternatively, the height h2 of each of the protrusions 222 may be 100% to 120% of the thickness h1 of the inner adhesive layer 203.

(19) Each of the protrusions 222 protrudes perpendicularly from the plane of the flat type main body 221. The protrusions 222 are located so as to be spaced apart from each other by the same distance.

(20) Consequently, thermal energy from the electrode assembly may move from the outermost electrode to the metal layer of the laminate sheet via the heat transfer member, whereby the thermal energy may uniformly and rapidly move from the entirety of the outermost electrode.

(21) FIG. 4 is a partial exploded perspective view showing a laminate sheet, heat transfer members, and an electrode according to another embodiment of the present invention, and FIG. 5 is a partial side sectional view schematically showing the laminate sheet, the heat transfer members, and the electrode of FIG. 4.

(22) Referring to FIGS. 4 and 5, the laminate sheet, denoted by reference numeral 310, is configured to have a layered structure in which an outer coating layer 301, a metal layer 302, and an inner adhesive layer 303 are sequentially stacked.

(23) The heat transfer members, denoted by reference numeral 332, are attached to the upper surface of the electrode, denoted by reference numeral 334, so as to protrude perpendicularly from the upper surface of the electrode. In the case in which a combination 330 of the electrode 334 and the heat transfer members 332 is received in a battery case, the heat transfer members 332 contact the metal layer 302 of the laminate sheet 310, which constitutes the battery case, through the inner adhesive layer 303 of the laminate sheet 310.

(24) The shape and the height of each of the heat transfer members 332 may be the same as the shape and the height of each of the protrusions 222 of the heat transfer member 220, and therefore a description thereof will be omitted.

(25) In the case in which the combination of the electrode and the heat transfer members is provided, as described above, it is possible to conveniently manufacture an electrode assembly. Also, in the case in which the heat transfer members 332 are used, it is possible to increase the capacity of a battery in proportion to a decrease in the thickness of the flat type main body of the heat transfer member 220, compared to the case in which the heat transfer member 220 is used.

(26) That is, the pouch-shaped secondary battery according to the present invention is configured to have a structure in which the heat transfer member is provided in the battery case. Consequently, it is possible to easily discharge thermal energy from the secondary battery, whereby it is possible to improve the safety of the secondary battery.

(27) Hereinafter, the present invention will be described with reference to the following examples. These examples are provided only for illustration of the present invention and should not be construed as limiting the scope of the present invention.

Measurement of Thermal Conductivity

Experimental Example

(28) In order to check the difference in thermal conductivity between general conductive adhesives and heat transfer members according to the present invention, seven kinds of conductive adhesive currently available on the market were prepared as Comparative Examples 1 to 7 and five kinds of heat transfer member according to the present invention were prepared as Examples 1 to 5 as described below, and the thermal conductivity of the conductive adhesives and the heat transfer members was measured. The thermal conductivity of the conductive adhesives and the heat transfer members was measured at a temperature of 25° C. using a thermal conductivity measurement instrument (Model TC-30 manufactured by Mathis Company). In addition, the thermal conductivity of the conductive adhesives and the heat transfer members was measured according to ASTM C 518. Meanwhile, it is possible to measure the thermal conductivity of the conductive adhesives and the heat transfer members using an instrument capable of simultaneously measuring the thermal conductivity of solids, liquids, paste, etc., in addition to the above instrument.

(29) The manufacturers of the conductive adhesives and the base materials used in Comparative Examples 1 to 7 are shown in Table 1 below.

(30) TABLE-US-00001 TABLE 1 Manufacturer Base material Comparative Example 1 Aremco Aluminum Comparative Example 2 Duralco Aluminum Comparative Example 3 Aremco Silver Comparative Example 4 Duralco Silver Comparative Example 5 Aremco Nickel Comparative Example 6 Duralco Nickel Comparative Example 7 Duralco Carbon

(31) The results of measurement of the thermal conductivity of the heat transfer members according to Examples 1 to 5 and the conductive adhesives according to Comparative Examples 1 to 7 are shown in Table 2 below.

(32) TABLE-US-00002 TABLE 2 Thermal conductivity Base material (W/m .Math. K) Aluminum Example 1 235 Comparative Example 1 1.2 Comparative Example 2 6.3 Copper Example 2 400 Silver Example 3 430 Comparative Example 3 9.1 Comparative Example 4 7.2 Nickel Example 4 91 Comparative Example 5 2.6 Comparative Example 6 2.2 Carbon Example 5 140 Comparative Example 7 8.7

(33) Referring to Table 2 above, it can be seen that, even in the case in which the conductive adhesives and the heat transfer members are manufactured using the same base material, the thermal conductivity of the conductive adhesives is much lower than that of the heat transfer members.

(34) For example, when comparing Example 1 and Comparative Example 1, in each of which aluminum was used as the base material, it can be seen that the thermal conductivity of Example 1 is about 196 times as high as that of Comparative Example 1.

(35) In the case in which a pouch-shaped secondary battery is configured to have a structure in which a conductive adhesive is applied to an electrode assembly and a laminate sheet therebetween such that a metal layer of the laminate sheet is connected to the electrode assembly via the conductive adhesive, therefore, it can be seen that it is not easy to rapidly discharge the thermal energy generated in the pouch-shaped secondary battery out of a battery case due to the low thermal conductivity of the conductive adhesive.

(36) Those skilled in the art to which the present invention pertains will appreciate that various applications and modifications are possible based on the above description, without departing from the scope of the present invention.

DESCRIPTION OF REFERENCE NUMERALS

(37) 100: Electrode assembly 101: Positive electrode active material 102: Positive electrode current collector 103: Negative electrode active material 104: Negative electrode current collector 110: Separator 201, 301: Outer coating layers 202, 302: Metal layers 203, 303: Inner adhesive layers 210, 310: Laminate sheets 220, 332: Heat transfer members 221: Flat type main body 222: Protrusions 234, 334: Electrodes 330: Combination of electrode and heat transfer member h1: Thickness of inner adhesive layer h2: Height of each protrusion

INDUSTRIAL APPLICABILITY

(38) As is apparent from the above description, a pouch-shaped secondary battery according to the present invention is configured to have a structure including a heat transfer member for connecting an electrode assembly mounted in a battery case to a metal layer of a laminate sheet constituting the battery case. Consequently, it is possible to minimize an increase in the overall thickness of the secondary battery and to prevent a decrease in the capacity of a battery cell constituting the secondary battery.

(39) In addition, it is possible to rapidly discharge the thermal energy generated in the secondary battery out of the battery case, whereby it is possible to prevent a thermal runaway phenomenon caused as the result of abnormal use of the secondary battery. Consequently, it is possible to maximally prevent a reduction in the lifespan of the secondary battery due to deterioration of the battery cell, whereby it is possible to provide a secondary battery having improved lifespan characteristics and improved safety.