Testing device for secondary battery and testing method for secondary battery

Abstract

To provide a testing device of a secondary battery and a testing method of the secondary battery capable of stably performing a highly reliable test.SOLUTION: A nail member that can be stuck into a housing of a secondary battery housed in a pack case from the outside of the pack case includes a conductive tip and an insulating portion continuing to a rear end side of the tip, at least a part of the tip is exposed from the insulating portion, and a length of a portion of the tip exposed from the insulating portion is 1 mm or more and 20 mm or less.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present technology relates to a testing device and a testing method for a secondary battery. [Background technology]

[0002] A nail penetration test for forcibly generating an electrical short circuit inside a lithium ion battery has been known. In such a nail penetration test, it has also been known to use a combination of an insulating member such as a ceramic member and a metal member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-114506 [Non-patent literature]

[0004] [Non-Patent Document 1] Masayasu Arakawa and Takefumi Isobe (2017), Issues in Nail Penetration Testing of Lithium-ion Batteries, NTT Facilities Research Institute Report No. 28, pp. 43-46 [Non-patent document 2] Maeda, Kiyotaka and Takahashi, Masashi (2017), Study on Alternative Test Methods for Forced Internal Short Circuit Test of Automotive Lithium-ion Batteries, JARI Research Journal, pp.1-4 Summary of the Invention [Problem to be solved by the invention]

[0005] When conducting a test to induce thermal runaway by inserting a nail into a secondary battery from outside the battery pack case, there is a demand for a highly reliable test that can be performed stably. However, there is still room for improvement in conventional test devices and methods.

[0006] The test apparatus and test method described in the above-mentioned Patent Document 1 and Non-Patent Document 1 and Non-Patent Document 2 evaluate the resistance to internal short circuits or the state of a secondary battery when an internal short circuit occurs, but do not evaluate the safety of a secondary battery by causing thermal runaway by inserting a nail member into the secondary battery from outside the pack case. As such, the test apparatus and test method described in the above-mentioned Patent Document 1 and Non-Patent Document 1 and Non-Patent Document 2 have different assumptions and configurations from the technology described in this specification.

[0007] An object of the present technology is to provide a testing device and a testing method for a secondary battery that can stably perform a highly reliable test. [Means for solving the problem]

[0008] The present technology provides the following secondary battery testing device and secondary battery testing method.

[0009] [1] A testing device for a secondary battery, comprising a nail member that can be inserted into the housing of a secondary battery stored in a pack case from outside the pack case, the nail member including a conductive tip portion and an insulating portion connected to the rear end side of the tip portion, at least a portion of the tip portion being exposed from the insulating portion, and the length of the portion of the tip portion exposed from the insulating portion being 1 mm or more and 20 mm or less.

[0010] [2] The secondary battery testing device according to [1], wherein the nail member further includes a metal portion provided on the rear end side of the insulating portion.

[0011] [3] The secondary battery testing device according to [1] or [2], wherein the tip of the nail member has a pointed shape, and the tip angle of the pointed shape is 20° or more and 60° or less.

[0012] [4] The secondary battery testing device according to any one of [1] to [3], wherein the nail member has a length of 50 mm or more and 300 mm or less.

[0013] [5] A method for testing a secondary battery, comprising the steps of: preparing a nail member including a conductive tip portion and an insulating portion connected to the rear end side of the tip portion; and piercing the nail member into the housing of a secondary battery stored in a pack case from outside the pack case, thereby causing thermal runaway in the secondary battery.

[0014] [6] The method for testing a secondary battery according to [5], wherein the nail member is thrust into the casing of the secondary battery at a speed of 0.1 mm / sec or more and 10 mm / sec or less.

[0015] [7] A method for testing a secondary battery described in [5] or [6], wherein the pressing load of the nail member is measured while the nail member is being inserted into the housing of the secondary battery, and the breakage of the nail member is detected based on a reduction in the pressing load. [Effects of the Invention]

[0016] According to the present technology, it is possible to provide a secondary battery testing device and a secondary battery testing method that are capable of stably carrying out highly reliable tests. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 2 is a perspective view showing the configuration of a battery cell included in a test specimen. [Figure 2] FIG. 10 is a cross-sectional view showing a nail member that can be inserted into a specimen. [Figure 3] FIG. 10 is a schematic diagram showing a state in which a nail penetration test is performed from the outside of the battery pack case. [Figure 4] FIG. 1 is a perspective view showing a guide jig to be installed on a specimen. [Figure 5] FIG. 10 is a diagram (part 1) showing a modified example of the guide jig. [Figure 6] FIG. 10 is a diagram (part 2) showing a modified example of the guide jig. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, embodiments of the present technology will be described. Note that the same or corresponding parts are denoted by the same reference characters, and description thereof may not be repeated.

[0019] In the embodiments described below, when numbers, amounts, etc. are mentioned, the scope of the present technology is not necessarily limited to those numbers, amounts, etc., unless otherwise specified. Furthermore, in the following embodiments, each component is not necessarily essential to the present technology, unless otherwise specified. Furthermore, the present technology is not necessarily limited to those that achieve all of the effects and advantages mentioned in the present embodiments.

[0020] In this specification, the terms "comprise," "include," and "have" are open-ended. That is, when a certain feature is included, other features may or may not be included.

[0021] Furthermore, when geometric terms and terms expressing positional and directional relationships are used in this specification, such as "parallel," "orthogonal," "45° diagonal," "coaxial," and "along," these terms allow for manufacturing errors and slight variations. When terms expressing relative positional relationships, such as "upper side" and "lower side," are used in this specification, these terms are used to indicate relative positional relationships in a single state, and the relative positional relationships can be reversed or rotated to any angle depending on the installation direction of each mechanism (for example, by turning the entire mechanism upside down).

[0022] In this specification, "battery" is not limited to lithium-ion batteries and may include other batteries such as nickel-metal hydride batteries and sodium-ion batteries. In this specification, "battery cells" are not necessarily limited to prismatic ones and may include cells of other shapes, such as cylindrical, pouch, and blade types. Furthermore, "battery cells" can be installed in hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and battery electric vehicles (BEVs). However, the use of "battery cells" is not limited to in-vehicle use.

[0023] FIG. 1 is a perspective view showing the configuration of a battery cell included in a test specimen. As shown in FIG. 1, a battery cell 10 (secondary battery) has a flat-surfaced rectangular parallelepiped appearance. The battery cell 10 includes an electrode terminal 11 and a rectangular housing 12. The electrode terminal 11 includes a positive terminal 11A and a negative terminal 11B. The housing 12 includes a pair of main surfaces 12A (long side surfaces) facing each other in the Y direction, a pair of side surfaces 12B (short side surfaces) facing each other in the X direction, a top surface 12C, and a bottom surface (not shown in FIG. 1) facing the top surface 12C in the Z direction.

[0024] The electrode terminal 11 is provided on an upper surface 12C of the housing 12. An electrode body and an electrolyte (not shown) are contained in the housing 12. The electrode body may be a wound type electrode body or a laminated type electrode body.

[0025] The thickness direction of the battery cell 10 is the Y direction, the height direction of the battery cell 10 is the Z direction, and the width direction of the battery cell 10 is the X direction. In the state of the battery pack, the multiple battery cells 10 are arranged in the Y direction so that the main surfaces 12A of the casings 12 of adjacent battery cells 10 face each other.

[0026] Fig. 2 is a cross-sectional view showing a nail member 100 that can be inserted into a battery cell 10, which is a test specimen. As shown in Fig. 2, the nail member 100 includes a conductive tip portion 110, an insulating portion 120, and a metal portion 130. The metal portion 130 does not necessarily have to be provided.

[0027] The tip portion 110 is made of a metal material such as iron, nickel, or titanium, or an alloy thereof. The insulating portion 120 is made of an insulating material such as ceramic. The insulating portion 120 is provided so as to be continuous with the rear end side of the tip portion 110.

[0028] The metal portion 130 is made of, for example, iron. The metal portion 130 is provided on the rear end side of the insulating portion 120. The metal portion 130 can reinforce the insulating portion 120. In the example of FIG. 2, the metal portion 130 has a bottomed cylindrical shape and is fitted onto the outer periphery of the insulating portion 120, but the form of the metal portion 130 is not limited to this.

[0029] 2, a part of the tip portion 110 is exposed from the insulating portion 120. The tip portion 110 has a pointed shape. The tip portion 110 and the insulating portion 120 that form the tip side of the nail member 100 have a tapered shape.

[0030] The length (L1) of the exposed portion of the tip portion 110 is about 1.0 mm or more, more preferably about 2.0 mm or more, and even more preferably about 3.0 mm or more. The length (L1) of the exposed portion of the tip portion 110 is about 20 mm or less, more preferably about 13 mm or less, and even more preferably about 6.0 mm or less.

[0031] When the nail member 100 is inserted into the main surface 12A of the casing 12 of the battery cell 10, the length (L1) of the exposed portion of the tip 110 is preferably at least half the thickness of the casing 12. The tip angle (θ) of the pointed shape of the tip 110 is preferably between 20° and 60°. The length (L2) of the tapered shape formed by the tip 110 and the insulating portion 120 is preferably between 30 mm and 300 mm, more preferably between 20 mm and 10 mm, and even more preferably between 10 mm and 10 mm. The total length (L) of the nail member 100 is preferably between 50 mm and 300 mm, and the diameter (D) of the nail member 100 is preferably between 1 mm and 10 mm.

[0032] However, the dimensions (length, diameter, angle, etc.) of the nail member 100 are not limited to the above values, and can be changed as appropriate depending on the size of the specimen, etc.

[0033] Fig. 3 is a schematic diagram showing how a nail penetration test is performed using the nail member 100. In the example of Fig. 3, a plurality of battery cells 10 are stacked in the Y direction.

[0034] As shown in FIG. 3, the nail member 100 can be inserted into the housing 12 of the battery cell 10 housed inside the pack case 200 from outside the pack case 200.

[0035] 3, the pack case 200 includes a top surface 210, a side surface 220, and a bottom surface 230. The nail member 100 may be inserted into the pack case 200 from the top surface 210 side or from the bottom surface 230 side.

[0036] Fixing jigs 300 are provided on both sides of the pack case 200. The side surfaces 220 of the pack case 200 are fixed to the fixing jigs 300 via bolts 300A. This holds the battery pack in a fixed state, making it possible to perform nail penetration tests from the top surface 210 and bottom surface 230 of the pack case 200. However, the manner in which the pack case 200 is fixed is not limited to the example shown in FIG. 3. The position and direction in which the nail members 100 are inserted are also not limited to those shown in FIG. 3; for example, the nail members 100 may be inserted into the pack case 200 through existing openings in the pack case 200 (such as openings for installing connectors) and pierced into the battery cells 10.

[0037] In the nail penetration test of this embodiment, a nail member 100 is pierced into the casing 12 of the battery cell 10 from outside the pack case 200, causing thermal runaway in the battery cell 10. The safety of the battery pack can be evaluated based on the behavior of the battery pack at this time (for example, whether or not the battery cells 10 adjacent to the battery cell 10 that has gone into thermal runaway catch fire).

[0038] The nail member 100 can be thrust into the casing 12 of the battery cell 10 at a speed of, for example, about 0.1 mm / sec or more and 10 mm / sec or less. The thrusting of the nail member 100 may be stopped immediately after thermal runaway occurs in the battery cell 10. The pressing load of the nail member 100 may be measured while the nail member 100 is thrust into the casing 12 of the battery cell 10, and breaking of the nail member may be detected based on a reduction in the pressing load.

[0039] 3, a guide jig 400 (guide member) is used to guide the nail member 100. The guide jig 400 is placed on the outer surface of the pack case 200. The guide jig 400 is made of an insulating material.

[0040] The guide jig 400 may be made of, for example, POM (polyacetal) resin having a heat resistance temperature of about 110°C, PBT (polybutylene terephthalate) resin having a heat resistance temperature of about 60°C or more and 140°C or less, or PEEK (polyether ether ketone) resin having a heat resistance temperature of about 260°C.

[0041] 4 is a perspective view showing the guide jig 400. As shown in FIG. 4, the guide jig 400 includes a hole 410, a protrusion 420, and a recess 430.

[0042] The hole 410 penetrates the guide jig 400. The nail member 100 to be thrust into the specimen is inserted into the hole 410. The hole 410 can guide the nail member 100. It is preferable that the inner diameter of the hole 410 is larger than the diameter (D) of the nail member 100 by approximately 0.01 mm or more and 2.0 mm or less. It is preferable that the depth of the hole 410 (height of the guide jig 400) is approximately 5 mm or more and 50 mm or less.

[0043] By forming protrusions 420 and recesses 430 that correspond to the shape of the mounting surface of the specimen on which guide jig 400 is placed, the adhesion between guide jig 400 and the specimen is improved, and guide jig 400 can be placed stably, even if the specimen has unevenness.

[0044] The nail member 100 may be inserted into the pack case 200 and the battery cell 10 with the guide jig 400 fixed to the pack case 200 of the battery pack being tested. The nail member 100 may be inserted into the pack case 200 and the battery cell 10 with the periphery of the adhesive surface between the guide jig 400 and the pack case 200 covered with a heat-resistant material. The nail member 100 may also be inserted into the pack case 200 and the battery cell 10 with the hole 410 covered with a heat-resistant material.

[0045] For example, double-sided tape or adhesive can be used to fix the guide jig 400. For example, heat-resistant tape made of aluminum, polyimide, or the like can be used as the heat-resistant material.

[0046] Next, modified examples of the guide jig 400 will be described using Figures 5 and 6. In both the examples of Figures 5 and 6, the guide jig 400 is provided inside the pack case 200. In both the examples of Figures 5 and 6, end plates 20 are provided at the ends of stacks made up of multiple battery cells 10 arranged in the Y direction. In both the examples of Figures 5 and 6, the nail members 100 pass through holes 410, 20A provided in the guide jig 400 and end plates 20, respectively, along the Y direction, and are thrust into the battery cells 10.

[0047] 5 and 6, the surface 440 of the guide jig 400 extends parallel to the inner surface of the pack case 200. It is preferable that there is a gap of about several millimeters between the surface 440 of the guide jig 400 and the inner surface of the pack case 200.

[0048] In the example of Fig. 5, the surface 440 of the guide jig 400 and the inner surface of the pack case 200 both extend along the XZ plane. In the example of Fig. 6, the surface 440 of the guide jig 400 and the inner surface of the pack case 200 both incline obliquely with respect to the XZ plane. That is, the surface 440 of the guide jig 400 is also formed obliquely to match the inclination of the inner surface of the pack case 200. However, the surface 440 of the guide jig 400 does not necessarily have to be parallel to the inner surface of the pack case 200.

[0049] The manner in which the guide jig 400 is installed is not limited to the examples shown in Figures 4 to 6. For example, the guide jig 400 may be installed so that a portion of the guide jig 400 reaches from the outside to the inside of the pack case 200.

[0050] If the electrode body of the battery cell 10 is a wound electrode body, it is preferable to pierce the nail member 100 from a direction approximately perpendicular to the winding axis. If the electrode body of the battery cell 10 is a stacked electrode body, it is preferable to pierce the nail member 100 from a direction approximately perpendicular to the stacking direction.

[0051] According to the nail member 100 of this embodiment, the portion connected to the conductive tip portion 110 is made of the insulating portion 120, so that when a nail penetration test is performed from outside the pack case 200, even if the nail member 100 and the pack case 200 come into contact with each other, electrical conduction between the nail member 100 and the pack case 200 can be avoided. Therefore, it is possible to prevent the pack case 200 from being charged during the nail penetration test.

[0052] Furthermore, for example, in the case of a battery pack mounted on a vehicle, it may be necessary to measure the insulation of the battery pack (pack case 200) during a nail penetration test in order to evaluate safety in the event of a collision. As described above, by configuring the portion connected to the conductive tip portion 110 as the insulating portion 120, the insulation resistance of the battery pack can be accurately measured even when the nail member 100 and the pack case 200 come into contact with each other.

[0053] Furthermore, by configuring the rear end of the insulating part 120 with the metal part 130, the strength of the nail member 100 can be improved and damage (breakage) of the nail member 100 during a nail penetration test can be suppressed. Note that, as described above, electrical conduction between the nail member 100 and the pack case 200 can be avoided by insulating the surface of the metal part 130 or by forming the metal part 130 only in an area that does not come into contact with the pack case 200 during a nail penetration test.

[0054] As described above, the nail member 100 according to the present embodiment makes it possible to stably carry out a highly reliable nail penetration test. The nail member 100 may be used alone without using the guide jig 400.

[0055] The guide jig 400 according to this embodiment facilitates alignment of the nail member 100 with the specimen (the portion to be pierced) when performing a nail penetration test using the nail member 100. As a result, it is possible to prevent the nail member 100 from being damaged by being pierced into an unintended location or at an unintended angle (a non-perpendicular angle). As a result, it is possible to reliably cause thermal runaway in the battery cell 10 as intended during the nail penetration test.

[0056] Furthermore, by providing the guide jig 400, it is possible to prevent ejected matter (gas, etc.) from being ejected from the battery cell 10 during a nail penetration test from leaking outside the pack case 200.

[0057] As described above, the guide jig 400 according to this embodiment makes it possible to stably carry out a highly reliable nail penetration test. The nail member used in combination with the guide jig 400 is not limited to the above-mentioned nail member 100. For example, a nail member made entirely of a metal member may be combined with the guide jig 400 to carry out a nail penetration test.

[0058] Although the embodiments of the present technology have been described above, the embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present technology is defined by the claims, and it is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0059] 10 battery cell, 11 electrode terminal, 11A positive terminal, 11B negative terminal, 12 housing, 12A main surface, 12B side, 12C top surface, 20 end plate, 20A hole portion, 100 nail member, 110 tip portion, 120 insulating portion, 130 metal portion, 200 pack case, 210 top surface, 220 side, 230 bottom surface, 300 fixing jig, 300A bolt, 400 guide jig, 410 hole portion, 420 protrusion portion, 430 recess portion, 440 surface.

Claims

1. a nail member that can be inserted from the outside of the pack case into a housing of a secondary battery housed in the pack case; The nail member includes a conductive tip portion and an insulating portion connected to a rear end side of the tip portion, At least a portion of the tip is exposed from the insulating portion, The length of the portion of the tip portion exposed from the insulating portion is 1 mm or more and 20 mm or less.

2. The secondary battery testing device according to claim 1 , wherein the nail member further includes a metal portion provided on a rear end side of the insulating portion.

3. 3. The secondary battery testing device according to claim 1, wherein the tip of the nail member has a pointed shape, and the pointed shape has a tip angle of 20 degrees or more and 60 degrees or less.

4. 3. The secondary battery testing device according to claim 1, wherein the nail member has a length of 50 mm or more and 300 mm or less.

5. preparing a nail member including a conductive tip portion and an insulating portion connected to a rear end side of the tip portion; and a step of piercing the nail member into a housing of a secondary battery housed in a pack case from outside the pack case to cause thermal runaway in the secondary battery.

6. The method for testing a secondary battery according to claim 5 , wherein the nail member is thrust into the casing of the secondary battery at a speed of 0.1 mm / sec or more and 10 mm / sec or less.

7. 7. The secondary battery testing method according to claim 5, further comprising measuring a pressing load of the nail member while piercing the nail member into the housing of the secondary battery, and detecting that the nail member has broken based on a reduction in the pressing load.

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