Battery cell heat transfer test method and battery cell ignition heater for heat transfer test

Abstract

The heater for igniting a battery cell for a thermal transfer test and the thermal transfer test method according to an embodiment of the present invention can prevent side rupture when a battery cell is ignited for a thermal transfer test, thereby preventing errors in the thermal transfer test.

Description

[Technical Field]

[0001] The present invention relates to a method for testing the thermal transition of a battery cell and a heater for igniting a battery cell (cylindrical trigger cell) for the thermal transition test. [Background technology]

[0002] Unlike primary batteries, which cannot be recharged, secondary batteries are batteries that can be charged and discharged, and are used not only in portable devices but also in electric vehicles (EVs) and hybrid electric vehicles (HEVs), which are powered by electrical sources.

[0003] Currently widely used types of secondary batteries include lithium-ion batteries, lithium polymer batteries, nickel-cadmium batteries, nickel-metal hydride batteries, and nickel-zinc batteries. The operating voltage of such a unit secondary battery cell, i.e., a unit battery cell, is approximately 2.5V to 4.6V. Therefore, if a higher output voltage is required, a battery pack is constructed by connecting multiple battery cells in series. Alternatively, a battery pack may be constructed by connecting multiple battery cells in parallel depending on the required charge / discharge capacity of the battery pack. Therefore, the number of battery cells included in a battery pack may be variously set depending on the required output voltage or charge / discharge capacity.

[0004] When a battery pack is constructed by connecting a number of battery cells in series / parallel, a common method is to first construct a battery module consisting of at least one battery cell, preferably a number of battery cells, and then use at least one such battery module to construct the battery pack by adding other components. Here, a battery module refers to a component in which a number of battery cells are connected in series or parallel, and a battery pack refers to a component in which a number of battery modules are connected in series or parallel to increase capacity, output, etc.

[0005] However, if such a battery module or pack is overcharged, the battery module may swell, causing an explosion or fire. Such an explosion or fire can pose a greater risk, even resulting in loss of life.

[0006] As the battery market grows, stronger safety measures are being required. International certification is also now requiring thermal propagation (TP) tests. Traditionally, TP tests for cylindrical cells have been performed by heating the sides of the cylindrical cell to ignite the cell. However, this traditional method of igniting cylindrical cells can cause side rupture when the cylindrical cell ignites.

[0007] According to the internationally certified ISO 6469-1 standard, normal ignition of the trigger cell is required during the thermal transition (TP) test, and normal ignition is only recognized when the top cap of the cell is opened. If side rupture occurs during cell ignition, normal ignition is not recognized. This has led to the need to develop a thermal transition test method and a new heater that can promote ignition of cylindrical cells without side rupture. Summary of the Invention [Problem to be solved by the invention]

[0008] SUMMARY OF THE INVENTION An object of the present invention is to provide a method for heat transfer testing that prevents side rupture when a cylindrical cell for heat transfer testing is ignited, and a heater for igniting a cylindrical trigger cell for heat transfer testing. [Means for solving the problem]

[0009] According to one aspect of the present invention, a heater for igniting a battery cell for a thermal transfer test includes a heating unit disposed on a bottom surface of a battery cell to heat the bottom surface of the battery cell, and a connecting unit connected to a heater wire at the heating unit.

[0010] The heating portion is circular.

[0011] Furthermore, the heating portion covers at least a portion of the bottom surface of the battery cell.

[0012] The heating unit also includes a heating member for heating the bottom surface of the battery cell, and a heat-resistant sheet disposed on one surface of the heating member.

[0013] Furthermore, the heating element includes a heating metal.

[0014] The heating metal may also be inconel.

[0015] Furthermore, the heat-resistant sheets are disposed on the upper and lower surfaces of the heating member, respectively.

[0016] The heat-resistant sheet may be a mica sheet.

[0017] Furthermore, the heating part is attached to the battery cell through a polyimide (PI) tape.

[0018] The heater further includes a first temperature sensor for measuring the temperature of the heater.

[0019] The battery further includes a second temperature sensor for measuring the temperature of the battery cell.

[0020] The battery cell may also be a cylindrical battery cell.

[0021] A method for testing the thermal transition of a battery cell according to one aspect of the present invention includes the steps of: placing a heater on a bottom surface of a battery cell to heat the bottom surface of the battery cell; and causing the battery cell to ignite due to the heating of the bottom surface of the battery cell.

[0022] In addition, the method for testing the thermal transition of a battery cell according to an aspect of the present invention may further include, after the step of igniting the battery cell, opening an upper cap of the battery cell. [Effects of the Invention]

[0023] A method for testing a thermal transition of a battery cell and a heater for igniting a battery cell according to an embodiment of the present invention can prevent side rupture when igniting a battery cell for a thermal transition test, thereby preventing errors in the thermal transition test. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 2 is a diagram illustrating the inside of a cylindrical battery cell. [Figure 2] FIG. 1 is a diagram illustrating a heater for ignition of a battery cell (cylindrical trigger cell) for a thermal transition test according to an embodiment of the present invention. [Figure 3] FIG. 3 is a side view of the heater shown in FIG. 2. [Figure 4] FIG. 3 is a diagram showing the shape of the heater shown in FIG. 2. [Figure 5] 1 is a diagram showing an example in which a heater according to an embodiment of the present invention is coupled to a battery cell (cylindrical trigger cell); [Figure 6] This is a photo of the battery cell (cylindrical trigger cell) after the test. [Figure 7] FIG. 6 is a photograph showing the upper and lower parts of a battery cell (cylindrical trigger cell), FIG. 7(a) is a photograph showing the upper part of the battery cell, and FIG. 7(b) is a photograph showing the lower part of the battery cell. [Figure 8] 1 is a graph illustrating the results of a heat transfer test on a battery cell (cylindrical trigger cell). DETAILED DESCRIPTION OF THE INVENTION

[0025] The advantages and features of the present invention, as well as methods for achieving them, will become more apparent from the following detailed description of the embodiments in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, and may be embodied in various different forms. These embodiments are provided solely to ensure that the disclosure of the present invention is complete and to fully convey the scope of the invention to those skilled in the art. The present invention is defined solely by the scope of the claims. Therefore, in some embodiments, well-known process steps, well-known device structures, and well-known techniques are not specifically described to avoid ambiguity. The same reference numerals refer to the same elements throughout the specification.

[0026] In the drawings, thicknesses of various layers and regions may be exaggerated to clearly illustrate them. Similar parts are designated by the same reference numerals throughout the specification. When a layer, film, region, plate, or other part is described as being "on" another part, this includes not only when it is "directly on" the other part, but also when there is another part between them. Conversely, when a part is described as being "directly on" the other part, it means that there is no other part between them. Furthermore, when a layer, film, region, plate, or other part is described as being "under" the other part, this includes not only when it is "directly under" the other part, but also when there is another part between them. Conversely, when a part is described as being "directly under" the other part, it means that there is no other part between them.

[0027] Before describing a method for testing the thermal transition of a battery cell and a heater for igniting the battery cell for the thermal transition test according to an embodiment of the present invention, a battery cell will be described first.

[0028] Battery cells can be classified into rectangular, cylindrical, pouch, and other types depending on the shape of the case.

[0029] FIG. 1 is a diagram illustrating the inside of a cylindrical battery cell 100.

[0030] The cylindrical battery cell 100 includes a jelly-roll-shaped electrode assembly 110 and a battery case 120 for housing the electrode assembly 110. An upper insulating member 150 may be disposed on the upper end of the electrode assembly 110, and a lower insulating member 160 may be disposed on the lower end of the electrode assembly 110.

[0031] The electrode assembly 110 has a jelly-roll structure in which a positive electrode 111, a negative electrode 113, and a separator 112 are wound up and interposed therebetween, and a center pin 140 can be inserted into the center thereof.

[0032] The cylindrical battery cell 100 may be formed by housing the electrode assembly 110 in a battery case 120, injecting an electrolyte into the battery case 120, and then attaching a cap assembly 130 to the upper end of the battery case 120. The battery case 120 is cylindrical, and the jelly-roll-shaped electrode assembly 110 is housed in the cylindrical battery case 120, thereby implementing a cylindrical secondary battery.

[0033] The battery case 120 may include a bottom portion 121 disposed on the bottom, a beading portion 122, and a clamp portion 123.

[0034] The beading portion 122 is for stable connection of the cap assembly 130 and is formed along the circumferential direction on the upper portion of the outer periphery of the battery case 120, and may be formed in a concave shape on the outer periphery of the battery case 120 toward the center of the electrode assembly 110. The beading portion 122 may prevent the electrode assembly 110 from moving.

[0035] The clamping portion 123 may be disposed on the upper portion of the beading portion 122 and may be formed to circumferentially wrap around the edge portion of the cap assembly 130. The clamping portion 123 may ensure stable coupling of the cap assembly 130.

[0036] The cap assembly 130 may include an upper cap 131 that forms a positive electrode terminal, a cap plate 132 to which a positive electrode tab 134 extending upward in the electrode assembly 110 is connected, and an airtight gasket 133.

[0037] The gasket 133 is attached to the upper inner surface of the clamping portion 123 and the beading portion 122 to increase the sealing force between the cap assembly 130 and the battery case 120 .

[0038] As previously mentioned, the positive electrode tab 134 may extend upwardly from the electrode assembly 110. Specifically, it may extend from the positive electrode 111 of the electrode assembly 110.

[0039] The positive electrode tab 134 is connected to the cap plate 132, and the upper cap 131 can function as a positive electrode terminal. An opening 151 is formed in the upper insulating member 150, and the positive electrode tab 134 can pass through the opening 151 and be connected to the cap plate 132.

[0040] The center pin 140 generally includes a metal material and has a cylindrical structure formed by bending a plate material into a round shape to provide a predetermined strength. In addition to self-heating, the center pin 140 can also fix and support the electrode assembly 110 and function as a passage for releasing gas generated by internal reactions during charging, discharging, and operation.

[0041] The electrolyte solution injected into the battery case 120 is a non-aqueous electrolyte solution containing a lithium salt, and the non-aqueous electrolyte solution containing a lithium salt is composed of a non-aqueous electrolyte solution and a lithium salt. Examples of the non-aqueous electrolyte solution include, but are not limited to, a non-aqueous organic solvent, an organic solid electrolyte, and an inorganic solid electrolyte.

[0042] Such a cylindrical battery cell 100 may be configured so that a metal plate can be welded to the electrode terminals exposed to the outside of the cylindrical battery cell 100 in order to electrically connect them to the electrode terminals of other battery cells or to a battery circuit.

[0043] A plurality of such cylindrical battery cells 100 can form a battery module or a battery pack.

[0044] In the thermal transition (TP) test of a cylindrical battery cell 100, a method of heating the side of the cylindrical cell to ignite the cylindrical cell has been used in the past. However, this conventional cylindrical cell ignition method results in side rupture of the cylindrical cell when the cylindrical cell ignites.

[0045] A preferred embodiment of the present invention provides a thermal transition test method that can advance ignition of a cylindrical cell without side rupture, and a new heater for use therein.

[0046] A heater for igniting a battery cell (cylindrical trigger cell) for a heat transfer test according to an embodiment of the present invention and a heat transfer test method using the same will now be described in detail.

[0047] First, a heater 200 for igniting a battery cell (cylindrical trigger cell) for a heat transfer test according to an embodiment of the present invention will be described with reference to the drawings.

[0048] FIG. 2 is a diagram illustrating a heater 200 for igniting a battery cell for a thermal transition test according to one embodiment of the present invention, FIG. 3 is a diagram showing a side view of the heater 200 shown in FIG. 2, and FIG. 4 is a diagram (plan view) showing the shape of the heater 200 shown in FIG. 2.

[0049] The heater (hereinafter referred to as "heater") 200 for igniting a battery cell (cylindrical trigger cell) for a thermal transition test according to one embodiment of the present invention can prevent side rupture when a battery cell 100 (cylindrical trigger cell) for a thermal transition test is ignited.

[0050] The battery cell 100 (or cylindrical trigger cell, hereinafter referred to as the battery cell 100) for the thermal transition test is a cylindrical battery cell and may include an electrode assembly 110 and a cylindrical battery case 120 that houses the electrode assembly 110.

[0051] Meanwhile, a safety vent may be provided inside the battery case 120, for example, under the upper cap 131, to burst and release gas when pressure inside the battery case 120 increases.

[0052] In this embodiment, the heater 200 is disposed below the battery cell 100 (cylindrical trigger cell) for the thermal transition test and can heat the lower part of the battery cell 100 based on electricity supplied through a heater wire connected to the heater 200. Then, the battery cell 100 in which the heater 200 is disposed can be ignited, and the upper cap 131 of the battery cell 100 can be opened. For example, the heater 200 can be connected to a heater wire having a thickness of about 1 mm and a length of about 50 mm. In addition, the heater 200 can apply heat to the center of the lower part of the battery cell 100 (cylindrical trigger cell) based on electricity supplied through the heater wire.

[0053] More specifically, in conventional cylindrical cell ignition methods, a conventional heater is attached to the side of the cylindrical cell, resulting in side rupture near the heater attachment surface. This side rupture occurs when the outermost separator near the heater attachment surface is damaged, causing a localized short circuit on the side of the cylindrical can. In light of this, heater 100 according to an embodiment of the present invention, unlike conventional heaters, heats the center of the bottom of the cell, where the gap between the cylindrical can and the electrode is located, damaging the inner separator rather than the cell surface, thereby causing ignition.

[0054] To this end, the heater 200 may include a heating portion 210, a connecting portion 220, and a temperature sensor 230, as shown in FIG.

[0055] The heating unit 210 is disposed on the bottom surface of the battery cell 100 (cylindrical trigger cell) and can apply heat to the bottom surface of the battery cell 100.

[0056] 3 and 4, the heating unit 210 may include a heating member 211 and a heat-resistant sheet 212. The heating member 211 may generate heat by receiving electricity through a heating wire. In this embodiment, the heating member 211 may include a first portion 211a and second portions 211b and 211c.

[0057] The first portion 211a has a circular shape with an open top, and both ends located at the open top may be connected to the second portions 211b and 211c, respectively. That is, the left end of both ends located at the open top of the first portion 211a may be connected to the left side 211b of the second portions 211b and 211c, and the right end of both ends located at the open top of the first portion 211a may be connected to the right side 211c of the second portions 211b and 211c. A first temperature sensor 231 may be disposed in the center of the interior of the first portion 211a. That is, the first portion 211a of the heating member 211 may be disposed so as to surround the first temperature sensor 231.

[0058] The second portions 211b, 211c may surround the first portion 211a and include a left side portion 211b and a right side portion 211c that are separated from each other. The left side portion 211b and the right side portion 211c may have a generally semicircular arc shape as shown.

[0059] The left side portion 211b of the second portions 211b, 211c may have an upper end connected to the left end portion of the first portion 211a and may be configured to surround the left side portion of the first portion 211a. The lower end of the left side portion 211b of the second portions 211b, 211c may be connected to the left connecting portion 220.

[0060] The right side portion 211c of the second portions 211b, 211c may have an upper end connected to the right end portion of the first portion 211a and may be configured to surround the right side of the first portion 211a. The lower end of the right side portion 211c of the second portions 211b, 211c may be connected to the right coupling portion 220.

[0061] The heating element 211 is a heating metal, which may be, for example, inconel. The thickness of the heating element 211 may be, for example, about 0.1 mm, but the thickness may vary.

[0062] In this embodiment, the heating unit 210 has a circular shape and may be coupled to the battery cell 100 so as to cover a portion of the bottom surface of the battery cell 100 .

[0063] The heating unit 210 has a circular shape with an empty space in the center, and can be attached to the bottom surface of the battery cell 100. The first temperature sensor 131 can be attached to the empty space in the center of the heating unit 210. For example, the heating unit 210 can have a diameter of about 16 mm, but the size can be changed.

[0064] The heat-resistant sheet 212 is disposed on at least one side of the heating member 211 and can be disposed between the heating member 211 and the bottom surface of the battery cell 100 .

[0065] In this embodiment, the heat-resistant sheets 212 may be disposed on the upper and lower surfaces of the heating member 211, respectively.

[0066] The heat-resistant sheet 212 is made of a mica sheet and may have a thickness of approximately 0.3 mm or 0.5 mm, but this may be varied. As shown in Fig. 4, the heat-resistant sheet 212 may cover the entire heating element 211, or may extend to the connecting portion 220 side to cover not only the heating element 211 but also the connecting portion 220.

[0067] As described above, the heating unit 210 including the heating member 211 and the heat-resistant sheet 212 can be manufactured by pressing the heating member 211 with the two heat-resistant sheets 212 .

[0068] The heating unit 210 is attached to the lower surface of the battery cell 100 using a polyimide (PI) tape, and the thickness of the heating unit 210 may be, for example, about 1 mm.

[0069] The connecting parts 220 may be connected to a heater wire at one end of the heating member 211. Specifically, of the two connecting parts 220, the left connecting part 220 may extend in one direction from a lower end of the left part 211b of the second parts 211b and 211c to be connected to the heater wire, and the right connecting part 220 may extend in one direction from a lower end of the right part 221c of the second parts 211b and 211c to be connected to the heater wire.

[0070] Therefore, the connecting portion 220 can connect the heating member 211 and the heater wire.

[0071] The two connecting portions 220 extend parallel to the heating member 211 in the same direction on the same plane, and can receive electricity from the respective heater wires.

[0072] The temperature sensor 230 can measure the temperatures of the battery cell 100 and the heater 200 during a thermal transition test.

[0073] To this end, the temperature sensor 230 may include a first temperature sensor 231 that measures the temperature of the heater 200 and a second temperature sensor 232 that measures the temperature of the battery cell 100 .

[0074] The first temperature sensor 231 is disposed in the empty space at the center of the heating unit 210, and can measure the temperature change of the heating unit 210 (heater 200) during the thermal transition test.

[0075] The second temperature sensor 232 is disposed on the outer periphery of the battery cell 100 (see FIG. 5) and is capable of measuring the temperature change of the battery cell 100 during the thermal transition test.

[0076] Next, a method for testing the heat transfer of the battery cell 100 using the above-described battery cell ignition heater 200 will be described.

[0077] A method for testing the thermal transition of a battery cell 100 according to an embodiment of the present invention includes the steps of: placing a heater 200 on the bottom surface of the battery cell 100 to heat the bottom surface of the battery cell 100; and igniting the battery cell 100 by heating the bottom surface of the battery cell 100, and may further include the step of opening the upper cap 131 of the battery cell 100 after the step of igniting the battery cell.

[0078] FIG. 5 is a diagram showing an example in which a heater 200 for igniting a battery cell according to an embodiment of the present invention is coupled to a battery cell 100. As shown in FIG.

[0079] Referring to FIG. 5, the heating unit 210 may be disposed on the bottom surface of the battery cell 100 and may cover a portion of the bottom surface of the battery cell 100 .

[0080] In order to measure the temperature of the heater 200 during the thermal transition test, the first temperature sensor 231 may be disposed in an empty space in the center of the heating unit 210 disposed on the bottom surface of the battery cell 100 .

[0081] Additionally, a second temperature sensor 232 may be attached to the side of the battery cell 100 to measure the temperature of the battery cell 100 during the thermal transition test.

[0082] The connector 220 can then be connected to a heater wire.

[0083] Thereafter, when the thermal transition test is started, the heating unit 210 receives electricity from the heater wire through the connection unit 220 and heats the lower part of the battery cell 100. Then, the battery cell 100 is continuously heated by the heating unit 210 and ignites, which causes the upper cap 131 of the battery cell 100 to open.

[0084] In this way, the heater 200 can induce normal ignition of the battery cell 100, which meets the international certification ISO6469-1 standard.

[0085] Meanwhile, photographs of the battery cell 100 after the test are shown in FIGS.

[0086] FIG. 6 is a photograph of the battery cell 100 after the test, FIG. 7(a) is a photograph showing the upper part of the battery cell 100 after the test, and FIG. 7(b) is a photograph showing the lower part of the battery cell 100 after the test.

[0087] As shown in FIGS. 6 and 7, the side and bottom surfaces of the battery cell 100 after the test were not damaged, and it can be seen that the upper cap 131 of the battery cell 100 was released due to the fire.

[0088] FIG. 8 is a graph illustrating the results of a thermal transition test of the battery cell 100. In FIG. 8, the X-axis represents time s, and the Y-axis represents temperature (° C.).

[0089] The orange line represents the temperature change of the heater 200 measured by the first temperature sensor 231, and the blue line represents the temperature change of the battery cell 100 measured by the second temperature sensor 232.

[0090] In this test, the heater 200 was heated from 0° C. and maintained at approximately 600 to 700° C., and a current of 12 A was applied to the heater 200 .

[0091] As shown in FIG. 8, the ignition temperature of the battery cell 100 was approximately 103° C., and the time it took to ignite was approximately 2 minutes and 57 seconds.

[0092] The examples of the present invention are intended to illustrate the technical ideas, and are not intended to limit the scope of the technical ideas of the embodiments of the present invention. The scope of protection of the embodiments of the present invention should be interpreted according to the claims below, and all technical ideas within the equivalent range should be interpreted as being included in the scope of rights of the embodiments of the present invention. [Explanation of symbols]

[0093] 100 battery cells 200 Heater 210 Heating section 220 Connection part 230 Temperature Sensor

Claims

1. a heating unit disposed on a bottom surface of the battery cell for heating the bottom surface of the battery cell; a connecting portion that connects the heating portion to a heater wire; Including a heater for ignition of battery cells for heat transfer testing.

2. The heater for igniting a battery cell for a thermal transition test according to claim 1 , wherein the heating portion is circular.

3. The heater for igniting a battery cell for a thermal transfer test according to claim 1 , wherein the heating portion covers at least a part of a bottom surface of the battery cell.

4. The heating unit is a heating member for heating the bottom surface of the battery cell; a heat-resistant sheet disposed on one side of the heating member; The battery cell ignition heater for heat transfer testing according to claim 1, comprising:

5. The heater for igniting battery cells for heat transfer testing according to claim 4 , wherein the heating element includes a heating metal.

6. 6. The battery cell ignition heater for heat transfer testing according to claim 5, wherein the heating metal is inconel.

7. The heater for igniting battery cells for a heat transfer test according to claim 4 , wherein the heat-resistant sheets are respectively disposed on the upper and lower surfaces of the heating member.

8. 5. The heater for igniting battery cells for heat transfer testing according to claim 4, wherein the heat-resistant sheet is a mica sheet.

9. The heater for igniting a battery cell for a heat transfer test according to claim 1 , wherein the heating part is attached to the battery cell through a polyimide (PI) tape.

10. 10. The battery cell ignition heater for heat transfer testing of claim 1, further comprising a first temperature sensor for measuring the temperature of said battery cell ignition heater.

11. 11. The battery cell ignition heater for heat transfer testing according to claim 10, further comprising a second temperature sensor for measuring the temperature of the battery cell.

12. 2. The heater for igniting battery cells for heat transfer testing according to claim 1, wherein the battery cells are cylindrical battery cells.

13. a step of disposing a heater on a bottom surface of the battery cell to heat the bottom surface of the battery cell; the battery cell ignites due to bottom heating of the battery cell; A method for testing the thermal transition of a battery cell, comprising:

14. 14. The method for testing the thermal transition of a battery cell according to claim 13, further comprising the step of opening a top cap of the battery cell after the step of igniting the battery cell.

15. 14. The method for testing the thermal transition of a battery cell according to claim 13, wherein the battery cell is a cylindrical battery cell.

Images