Thermal propagation test method for battery cell and heater for igniting battery cell for thermal propagation test

Abstract

A heater for igniting a battery cell for a thermal propagation test and a thermal propagation test method according to an embodiment of the present invention can prevent side rupture during ignition of a battery cell for a thermal propagation test, thereby preventing errors in the thermal propagation test.

Description

Thermal transfer test method for battery cells and battery cell ignition heater for thermal transfer test

[0001] The present invention relates to a method for testing heat transfer of a battery cell and a heater for igniting a battery cell (cylindrical trigger cell) for heat transfer testing.

[0002] Secondary batteries, unlike primary batteries that cannot be recharged, are batteries that can be charged and discharged. They are used not only in portable devices but also in electric vehicles (EVs) and hybrid electric vehicles (HEVs) that are driven by electrical power sources.

[0003]

[0004] 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 these unit secondary battery cells, i.e., unit battery cells, is approximately 2.5 V to 4.6 V. Therefore, when a higher output voltage is required, multiple battery cells are connected in series to form a battery pack. Furthermore, depending on the charge / discharge capacity required for the battery pack, multiple battery cells are connected in parallel to form a battery pack. Therefore, the number of battery cells included in the battery pack can be set in various ways depending on the required output voltage or charge / discharge capacity.

[0005]

[0006] When configuring a battery pack by connecting multiple battery cells in series or parallel, it is common to first configure a battery module comprising at least one battery cell, preferably multiple battery cells, and then use at least one such battery module and add other components to configure the battery pack. Here, a battery module refers to a component in which multiple battery cells are connected in series or parallel, and a battery pack refers to a component in which multiple battery modules are connected in series or parallel to increase capacity and output, etc.

[0007]

[0008] However, in the case of overcharging, etc., in these battery modules and packs, swelling of the battery module may cause an explosion or fire, and such explosion or fire may cause greater danger, even leading to casualties.

[0009]

[0010] As the battery market grows, the need for enhanced safety is growing. International certifications are also increasingly requiring thermal propagation (TP) testing. Conventional methods for thermal propagation (TP) testing of cylindrical cells involve heating the side of the cell to ignite it. However, this conventional ignition method results in side rupture of the cylindrical cell when ignited.

[0011] According to the international standard ISO6469-1, normal ignition of a trigger cell is required for thermal transfer (TP) testing, and the cell's top cap must be opened for this to be recognized as normal. However, if side rupture occurs during cell ignition, normal ignition is not recognized. Therefore, there is a need to develop a new thermal transfer test method and heater that can ignite a cylindrical cell without side rupture.

[0012] The present invention aims to provide a heat transfer test method for preventing side rupture during ignition of a cylindrical cell for a heat transfer test and a heater for igniting a cylindrical trigger cell for a heat transfer test.

[0013] A battery cell ignition heater for a heat transfer test according to one embodiment of the present invention is characterized by including: a heating unit arranged on the bottom surface of a battery cell to heat the bottom surface of the battery cell; and a connecting unit connected to a heater wire in the heating unit.

[0014] Additionally, the heating part may be formed in a circular shape.

[0015] Additionally, the heating unit covers at least a portion of the bottom surface of the battery cell.

[0016] In addition, the heating unit 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.

[0017] Additionally, the heating member is made of a heating metal.

[0018] Additionally, the heating metal may be Inconel.

[0019] Additionally, the heat-resistant sheets are respectively placed on the upper and lower surfaces of the heating member.

[0020] Additionally, the heat-resistant sheet may be a mica sheet.

[0021] Additionally, the heating unit is attached to the battery cell via a polyimide (PI) tape.

[0022] Additionally, it further includes a first temperature sensor for measuring the temperature of the heater.

[0023] Additionally, it further includes a second temperature sensor for measuring the temperature of the battery cell.

[0024] Additionally, the battery cell may be a cylindrical battery cell.

[0025]

[0026] A method for testing heat transfer of a battery cell according to one embodiment of the present invention includes a step of heating the bottom surface of the battery cell by placing a heater on the bottom surface of the battery cell; and a step of causing the battery cell to ignite by heating the bottom surface of the battery cell.

[0027] In addition, the method for testing heat transfer of a battery cell according to one embodiment of the present invention further includes a step of opening the upper cap of the battery cell after the battery cell ignition step.

[0028] A method for testing heat transfer of a battery cell and a heater for igniting a battery cell according to one embodiment of the present invention can prevent errors in a heat transfer test by preventing side rupture when a battery cell is ignited for a heat transfer test.

[0029] Figure 1 is a drawing showing the inside of a cylindrical battery cell.

[0030] FIG. 2 is a drawing for explaining a heater for ignition of a battery cell (cylindrical trigger cell) for a heat transfer test according to one embodiment of the present invention.

[0031] Figure 3 is a drawing showing a side view of the heater shown in Figure 2.

[0032] Figure 4 is a drawing showing the shape of the heater shown in Figure 2,

[0033] FIG. 5 is a drawing showing an example in which a heater according to one embodiment of the present invention is coupled to a battery cell (cylindrical trigger cell).

[0034] Figure 6 is a photograph of a battery cell (cylindrical trigger cell) after the test.

[0035] Figure 7 is a photograph showing the upper and lower parts of the battery cell (cylindrical trigger cell) in Figure 6. Figure 7(a) is a photograph showing the upper part of the battery cell, and Figure 7(b) is a photograph showing the lower part of the battery cell.

[0036] Figure 8 is a graph showing the results of a heat transfer test of a battery cell (cylindrical trigger cell).

[0037] The advantages and features of the present invention, and the methods for achieving them, will become clearer with reference to the embodiments described in detail below together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms. These embodiments are provided only to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. Accordingly, in some embodiments, well-known process steps, well-known device structures, and well-known techniques are not specifically described to avoid ambiguity in the interpretation of the present invention. Like reference numerals refer to like elements throughout the specification.

[0038]

[0039] In order to clearly represent multiple layers and regions in the drawings, the thickness may be enlarged. Similar parts are designated by the same drawing reference numerals throughout the specification. When an element such as a layer, film, region, or plate is said to be "over" another element, this includes not only the case where it is "directly over" that element but also the case where there are other elements in between. Conversely, when an element is said to be "directly over" another element, this means that there are no other elements in between. Furthermore, when an element such as a layer, film, region, or plate is said to be "under" another element, this includes not only the case where it is "directly under" that element but also the case where there are other elements in between. Conversely, when an element is said to be "directly under" another element, this means that there are no other elements in between.

[0040]

[0041] Before describing a method for testing heat transfer of a battery cell according to one embodiment of the present invention and a heater for igniting a battery cell for heat transfer testing, a battery cell will first be described.

[0042] Battery cells can be classified into square, cylindrical, and pouch types depending on the shape of the case.

[0043] Figure 1 is a drawing showing the inside of a cylindrical battery cell (100).

[0044] A cylindrical battery cell (100) may include a jelly roll-shaped electrode assembly (110) and a battery case (120) for storing the electrode assembly (110). An upper insulating member (150) may be placed on the upper side of the electrode assembly (110), and a lower insulating member (160) may be placed on the lower side of the electrode assembly (110).

[0045]

[0046] The electrode assembly (110) has a jelly roll-shaped structure in which a positive electrode (111), a negative electrode (113), and a separator (112) are interposed between them and wound, and a center pin (140) can be inserted into the center thereof.

[0047]

[0048] A cylindrical battery cell (100) can be formed by housing an electrode assembly (110) in a battery case (120), injecting an electrolyte into the battery case (120), and then joining a cap assembly (130) to the top of the battery case (120). The battery case (120) is cylindrical, and a jelly roll-shaped electrode assembly (110) can be housed in the cylindrical battery case (120) to implement a cylindrical secondary battery.

[0049]

[0050] The battery case (120) may include a bottom portion (121) placed on the floor, a beading portion (122), and a clamping portion (123).

[0051] The above beading portion (122) is for stable bonding of the cap assembly (130), and can be formed along the circumferential direction on the upper part of the outer surface of the battery case (120), or can be formed by recessing in the center direction of the electrode assembly (110) on the outer surface of the battery case (120). The beading portion (122) can prevent movement of the electrode assembly (110).

[0052]

[0053] The clamping portion (123) may be positioned on top of the beading portion (122) and formed to wrap around the edge portion of the cap assembly (130) along the circumferential direction. The clamping portion (123) may facilitate stable bonding of the cap assembly (130).

[0054]

[0055] The cap assembly (130) may include a top cap (131) forming a positive terminal, a cap plate (132) to which a positive tab (134) extending upward from the electrode assembly (110) is connected, and a gasket (133) for maintaining confidentiality.

[0056]

[0057] A gasket (133) can be mounted on 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).

[0058]

[0059] As described above, the positive electrode tab (134) may extend upward from the electrode assembly (110). Specifically, it may extend from the positive electrode (111) of the electrode assembly (110).

[0060]

[0061] These positive electrode tabs (134) are connected to the cap plate (132), so that 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 tabs (134) can pass through the opening (151) and be connected to the cap plate (132).

[0062]

[0063] The center pin (140) typically comprises a metal material to impart a certain strength and is formed into a cylindrical structure formed by bending a plate. 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 gases generated by internal reactions during charging, discharging, and operation.

[0064]

[0065] The electrolyte injected into the battery case (120) may be a non-aqueous electrolyte containing a lithium salt, and the non-aqueous electrolyte containing a lithium salt is composed of a non-aqueous electrolyte and a lithium salt. Non-aqueous electrolytes include, but are not limited to, non-aqueous organic solvents, organic solid electrolytes, and inorganic solid electrolytes.

[0066]

[0067] In such a cylindrical battery cell (100), a metal plate may be welded to an electrode terminal exposed to the outside of the cylindrical battery cell (100) to electrically connect it to an electrode terminal of another battery cell or a battery circuit.

[0068]

[0069] A plurality of such cylindrical battery cells (100) can constitute a battery module or battery pack.

[0070]

[0071] When conducting a thermal transfer (TP) test of a cylindrical battery cell (100), a method of igniting the cylindrical cell by heating the side of the cylindrical cell has been used in the past, but the conventional cylindrical cell ignition method causes side rupture of the cylindrical cell when the cylindrical cell is ignited.

[0072] A preferred embodiment of the present invention is to provide a heat transfer test method capable of igniting a cylindrical cell without causing side rupture, and a novel heater used therein.

[0073]

[0074] A heater for ignition of a battery cell (cylindrical trigger cell) for a heat transfer test according to one embodiment of the present invention and a heat transfer test method using the same are described in detail.

[0075]

[0076] First, a heater (200) for ignition of a battery cell (cylindrical trigger cell) for a heat transfer test according to one embodiment of the present invention will be described with reference to the drawings.

[0077]

[0078] FIG. 2 is a drawing for explaining a heater (200) for ignition of a battery cell for a heat transfer test according to one embodiment of the present invention, FIG. 3 is a drawing showing a side view of the heater (200) shown in FIG. 2, and FIG. 4 is a drawing (plan view) showing the shape of the heater (200) shown in FIG. 2.

[0079]

[0080] A heater (hereinafter referred to as “heater”) (200) for ignition of a battery cell (cylindrical trigger cell) for a heat transfer test according to one embodiment of the present invention can prevent side rupture when igniting a battery cell (100) (cylindrical trigger cell) for a heat transfer test.

[0081] A battery cell (100) for a heat transfer test (or a cylindrical trigger cell, hereinafter collectively referred to as a battery cell (100)) may be a cylindrical battery cell and may include an electrode assembly (110) and a cylindrical battery case (120) that accommodates the electrode assembly (110).

[0082] Meanwhile, a safety vent may be provided inside the battery case (120), for example, at the bottom of the top cap (131), to discharge gas by bursting due to pressure increase inside the battery case (120).

[0083]

[0084] In this embodiment, the heater (200) can be placed at the bottom of the battery cell (100) (cylindrical trigger cell) for a heat transfer test, and can heat the bottom 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 placed can be ignited, and the top cap (131) of the battery cell (100) can be opened. For example, the heater (200) can have a thickness of about 1 mm and can be connected to a heater wire having a length of about 50 mm. In addition, the heater (200) can apply heat to the lower center of the battery cell (100) (cylindrical trigger cell) based on electricity supplied through the heater wire.

[0085]

[0086] To explain in more detail, the conventional cylindrical cell ignition method attaches the conventional heater to the side of the cylindrical cell, so that side rupture occurs near the heater attachment surface. Such side rupture is caused by a local short occurring on the side of the cylindrical can as the outermost separator close to the heater attachment surface is damaged. In consideration of this, the heater (100) according to one embodiment of the present invention, unlike the conventional heater, heats the center of the bottom surface of the cell where there is a gap between the cylindrical can and the electrode, thereby damaging the inner separator rather than the surface of the cell and causing ignition.

[0087]

[0088] For this purpose, the heater (200) may include a heating unit (210), a connecting unit (220), and a temperature sensor (230), as illustrated in FIG. 2.

[0089] The heating unit (210) can be placed 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).

[0090]

[0091] Specifically, the heating unit (210) may include a heating member (211) and a heat-resistant sheet (212), as illustrated in FIGS. 3 and 4. The heating member (211) may generate heat by receiving electricity through a heating wire. In the present embodiment, the heating member (211) may include a first portion (211a) and a second portion (211b, 211c).

[0092] The first part (211a) may be formed in a circular shape with an open top, and both ends located at the open top may be connected to the second parts (211b, 211c), respectively. That is, the left end of the both ends located at the open top of the first part (211a) may be connected to the left end (211b) of the second parts (211b, 211c), and the right end of the both ends located at the open top of the first part (211a) may be connected to the right end (211c) of the second parts (211b, 211c). A first temperature sensor (231) may be arranged at the inner center of the first part (211a). That is, the first part (211a) of the heating member (211) may be arranged to surround the first temperature sensor (231).

[0093]

[0094] The second portion (211b, 211c) may be formed in a form that surrounds the first portion (211a) and may include a left portion (211b) and a right portion (211c) that are separated from each other. The left portion (211b) and the right portion (211c) may be formed in an approximately semicircular arc shape as illustrated.

[0095] Among the second parts (211b, 211c), the left part (211b) may be configured such that its upper end is connected to the left end of the first part (211a) and surrounds the left part of the first part (211a). The lower end of the left part (211b) among the second parts (211b, 211c) may be connected to the left connection part (220).

[0096]

[0097] Among the second parts (211b, 211c), the right part (211c) may be configured such that its upper end is connected to the right end of the first part (211a) and surrounds the right part of the first part (211a). The lower end of the right part (211c) among the second parts (211b, 211c) may be connected to the right connection part (220).

[0098]

[0099] The heating member (211) may be a heating metal, and the heating metal may be, for example, Inconel. The thickness of the heating member (211) may be, for example, about 0.1 mm, but the thickness may be changed.

[0100]

[0101] In this embodiment, the heating unit (210) is formed in a circular shape and can be coupled to the battery cell (100) so as to cover a portion of the bottom surface of the battery cell (100).

[0102] The heating unit (210) may be formed in a circular shape with a hollow space in the center and may be attached to the bottom surface of the battery cell (100). A first temperature sensor (131) may be mounted in the hollow space in the center of the heating unit (210). For example, the heating unit (210) may have a diameter of approximately 16 mm, but the size may be changed.

[0103]

[0104] The heat-resistant sheet (212) can be placed on at least one surface of the heating member (211) and can be placed between the heating member (211) and the bottom surface of the battery cell (100).

[0105] In this embodiment, the heat-resistant sheet (212) can be placed on the upper and lower surfaces of the heating member (211), respectively.

[0106] The heat-resistant sheet (212) may be composed of a mica sheet and may have a thickness of about 0.3 mm or 0.5 mm, but may vary. The heat-resistant sheet (212) may cover the entire heating element (211) as shown in FIG. 4, and may extend toward the connecting portion (220) to cover not only the heating element (211) but also the connecting portion (220).

[0107] In this way, a heating member (210) including a heating member (211) and a heat-resistant sheet (212) can be manufactured through a process of pressing the heating member (211) into two heat-resistant sheets (212).

[0108] In addition, the heating unit (210) can be attached to the lower surface of the battery cell (100) via a polyimide (PI) tape, and the thickness of the heating unit (210) can be, for example, about 1 mm.

[0109]

[0110] The above connecting portion (220) can be connected to a heater wire at one end of the heating member (211). Specifically, among the two connecting portions (220), the left connecting portion (220) can be connected to the heater wire by extending in one direction from the lower end of the left portion (211b) among the second portions (211b, 211c), and the right connecting portion (220) among the two connecting portions (220) can be connected to the heater wire by extending in one direction from the lower end of the right portion (211c) among the second portions (211b, 211c).

[0111] Therefore, the connecting portion (220) can connect the heating member (211) and the heater wire.

[0112] The two connecting portions (220) can extend parallel to each other in the same direction on the same plane as the heating member (211) and can receive electricity from each heater wire.

[0113]

[0114] The above temperature sensor (230) can measure the temperature of the battery cell (100) and heater (200) during a heat transfer test.

[0115] 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).

[0116]

[0117] The first temperature sensor (231) can be placed in the central empty space of the heating unit (210) and can measure the temperature change of the heating unit (210) (heater (200)) during a heat transfer test.

[0118] The second temperature sensor (232) can be placed on the outer surface of the battery cell (100) (see FIG. 5) and can measure the temperature change of the battery cell (100) during a heat transfer test.

[0119]

[0120] Next, a method for testing the heat transfer of a battery cell (100) using the aforementioned battery cell ignition heater (200) will be described.

[0121]

[0122] A method for testing heat transfer of a battery cell (100) according to an embodiment of the present invention may include a step of arranging a heater (200) on the bottom surface of the battery cell (100) to heat the bottom surface of the battery cell (100); and a step of igniting the battery cell (100) by heating the bottom surface of the battery cell (100); and may further include a step of opening the top cap (131) of the battery cell (100) after the battery cell ignition step.

[0123]

[0124] FIG. 5 is a drawing showing an example in which a heater (200) for igniting a battery cell according to one embodiment of the present invention is coupled to a battery cell (100).

[0125] Referring to FIG. 5, the heating unit (210) is placed on the bottom surface of the battery cell (100) and can cover a portion of the bottom surface of the battery cell (100).

[0126]

[0127] And, in order to measure the temperature of the heater (200) during the heat transfer test, the first temperature sensor (231) can be placed in the central empty space of the heating part (210) placed on the bottom surface of the battery cell (100).

[0128] Additionally, in order to measure the temperature of the battery cell (100) during the heat transfer test, a second temperature sensor (232) may be mounted on the side of the battery cell (100).

[0129]

[0130] And, the connecting portion (220) can be connected to a heater wire.

[0131] Thereafter, when the heat transfer test begins, the heating unit (210) receives electricity from the heater wire through the connection unit (220) to heat the lower portion of the battery cell (100). Then, the battery cell (100) is continuously heated through the heating unit (210) and ignites, thereby opening the upper cap (131) of the battery cell (100).

[0132] In this way, the heater (200) can cause normal ignition of a battery cell (100) that meets the international certification ISO6469-1 standard.

[0133]

[0134] Meanwhile, photographs of the battery cell (100) after the test are shown in FIGS. 6 and 7.

[0135] Fig. 6 is a photograph of a battery cell (100) after a test, Fig. 7(a) is a photograph showing the upper part of a battery cell (100) after a test, and Fig. 7(b) is a photograph showing the lower part of a battery cell (100) after a test.

[0136]

[0137] As shown in FIGS. 6 and 7, the side and bottom surfaces of the battery cell (100) were not damaged after the test, and it can be seen that the top cap (131) of the battery cell (100) was opened due to ignition.

[0138]

[0139] Fig. 8 is a graph showing the results of a thermal transfer test of a battery cell (100). In Fig. 8, the X-axis represents time (s) and the Y-axis represents temperature (℃).

[0140] And, 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).

[0141] In this test, the heater (200) was heated from 0°C to approximately 600 to 700°C, and a current of 12A was applied to the heater (200).

[0142] As shown in Fig. 8, the ignition temperature of the battery cell (100) was approximately 103°C, and the time taken for ignition was approximately 2 minutes and 57 seconds.

[0143]

[0144] The embodiments of the present invention are intended to illustrate the technical concepts, and the scope of the technical concepts of the embodiments of the present invention is not limited by these embodiments. The scope of protection of the embodiments of the present invention should be interpreted by the following claims, and all technical concepts within the scope equivalent thereto should be construed as being included within the scope of the embodiments of the present invention.

[0145]

[0146] < Explanation of symbols >

[0147] 100: Battery cell

[0148] 200: Heater

[0149] 210: Heating section

[0150] 220: Connection

[0151] 230: Temperature sensor

Claims

1. A heating unit arranged on the bottom surface of the battery cell to heat the bottom surface of the battery cell; and A connecting portion connected to the heater wire in the above heating portion; A heater for ignition of battery cells for heat transfer tests including .

2. In paragraph 1, The above heating part is a heater for igniting a battery cell for heat transfer testing, which is formed in a circular shape.

3. In paragraph 1, A heater for igniting a battery cell for a heat transfer test, wherein the heating unit covers at least a portion of the bottom surface of the battery cell.

4. In paragraph 1, The above heating part A heating member for heating the bottom surface of the above battery cell; and A heat-resistant sheet arranged on one side of the above heating member; A heater for igniting a battery cell for heat transfer testing, comprising:

5. In paragraph 4, The above heating element is a heater for igniting a battery cell for a heat transfer test, made of a heating metal.

6. In paragraph 5, A heater for ignition of a battery cell for heat transfer testing, wherein the above heating metal is Inconel.

7. In paragraph 4, A heater for igniting a battery cell for a heat transfer test, wherein the heat-resistant sheets are respectively placed on the upper and lower surfaces of the heating member.

8. In paragraph 4, The above heat-resistant sheet is a mica sheet, a heater for igniting a battery cell for heat transfer testing.

9. In paragraph 1, The above heating unit is a battery cell ignition heater for heat transfer testing, which is attached to the battery cell via a polyimide (PI) tape.

10. In paragraph 1, A heater for igniting a battery cell for a heat transfer test, further comprising a first temperature sensor for measuring the temperature of the heater.

11. In paragraph 10, A battery cell ignition heater for a heat transfer test further comprising a second temperature sensor for measuring the temperature of the battery cell.

12. In paragraph 1, The above battery cell is a cylindrical battery cell, and is a heater for ignition of the battery cell for heat transfer testing.

13. A step of heating the bottom surface of the battery cell by placing a heater on the bottom surface of the battery cell; and A step in which the battery cell ignites by heating the bottom surface of the battery cell; A method for testing heat transfer of a battery cell including a battery cell.

14. In paragraph 13, A method for testing thermal transfer of a battery cell further comprising a step of opening the top cap of the battery cell after the battery cell ignition step.

15. In paragraph 13, The above battery cell is a cylindrical battery cell, and the method for testing the heat transfer of the battery cell.

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