Battery terminal structure

Abstract

This invention provides a battery terminal structure that maintains or improves sealing performance, leak resistance, and / or characteristic changes using a structure that has not been used conventionally. [Solution] A battery terminal structure comprising electrode terminals 520, 530 of one or both polarities installed on the outer casing 510 of a battery 500 via a gasket 400, wherein the electrode terminals have an internal terminal 200 that contacts the electrolyte in the outer casing and an external terminal 300 that does not contact the electrolyte, and the internal terminal and the external terminal are sealed to the outer casing by screw fastening.

Description

【Technical Field】 【0001】 The present invention relates to the structure of electrode terminals of one or both polarities installed via a gasket on an outer can of a battery. 【Background Art】 【0002】 In recent years, secondary batteries such as lithium-ion batteries have been widely used. Conventionally, an external terminal constituting an electrode terminal of a battery is generally connected to an internal terminal constituting the same electrode terminal by caulking or welding, where a special-shaped metal block having a male screw groove is used. Note that the external terminal is a component that does not contact the electrolytic solution, and the internal terminal is a component that contacts the electrolytic solution inside the outer can. 【0003】 In the prior art of Patent Document 1, in the positive electrode terminal 9, a shaft portion 9b constituting the positive electrode terminal is caulked and fixed to an insulating gasket 17, a sealing plate 4, an insulating plate 16, and a connection plate 8a of a positive electrode lead 8, which are also members constituting the positive electrode terminal. Thereby, the positive electrode terminal 9 is electrically connected to a positive electrode current collector tab 5a via the positive electrode lead 8 and a current collecting portion 8c. On the other hand, in the negative electrode terminal 11, a shaft portion 11b constituting the negative electrode terminal is caulked and fixed to an insulating gasket 17, a sealing plate 4, an insulating plate 16, and a connection plate 10a of a negative electrode lead 10, which are also members constituting the negative electrode terminal. Thereby, the negative electrode terminal 11 is electrically connected to a negative electrode current collector tab 6a via the negative electrode lead 10 and a current collecting portion 10c. 【Prior Art Documents】 【Patent Documents】 【0004】 【Patent Document 1】 Japanese Unexamined Patent Application Publication No. 2023-026188 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0005】 In the crimping method described above, the precision of the components themselves significantly affects the sealing performance at the electrodes. In the welding method, measures were needed to minimize the thermal impact on the gasket around the electrode terminals during welding. Furthermore, welding is often required when assembling battery packs, but the terminal components are made of aluminum or copper, which have poor weldability, and there was a possibility of thermal damage to the gaskets during welding. 【0006】 Therefore, the present invention aims to provide a battery terminal structure that maintains or improves sealing performance, leakage resistance, and / or characteristic changes using a structure that has not been used in the past, in order to address the conventional problems described above. [Means for solving the problem] 【0007】 As a result of various studies, the inventors have found that the above objective can be achieved by the present invention described below. 【0008】 In other words, the terminal structure of the battery according to the present invention is A structure for one or both polarity electrode terminals installed on the battery casing via a gasket, The electrode terminal has an internal terminal that contacts the electrolyte inside the outer casing and an external terminal that does not contact the electrolyte. The internal terminals and the external terminals are sealed to the outer casing by screw fastening. 【0009】 According to the battery terminal structure of the present invention, the internal and external terminals are screwed to the outer casing, resulting in a configuration where the internal and external terminals are threaded together. This allows for not only dimensional control but also control of the crimping force of the gasket by tightening the screws, thus providing tolerance for component precision. Furthermore, this configuration eliminates the thermal impact on the gasket that occurs when the internal and external terminals are fixed by welding, ensuring stable sealing performance. In addition, it becomes possible to install the external terminals after seam welding of the outer casing, preventing a decrease in the gasket's resilience due to thermal creeping. Thus, sealing performance, leak resistance, and / or characteristic changes can be maintained or improved with a structure that has not been used conventionally. 【0010】 The internal terminal side may have a male screw structure, the external terminal side may have a female screw structure, and the internal terminal and the external terminal may be screwed together. This structure, with a male screw structure on the internal terminal side and a female screw structure on the external terminal side, minimizes dead space inside the battery. By installing a disc terminal that acts as a washer below the screw-type external terminal, damage caused by friction between the gasket and the terminal due to rotation can be prevented. Furthermore, by installing screws on the outside of the female-screwed external terminal, it becomes possible to secure the cells together using a nut structure. 【0011】 A metal structure acting as a washer may be interposed between the external terminal and the gasket. This allows for the prevention of damage caused by friction between the gasket and the terminal due to rotation, by installing a metal structure such as a disc terminal that acts as a washer below the external terminal when the internal and external terminals are screwed together. 【0012】 The aforementioned external terminal is, It has a hollow bolt structure, When electrically connecting multiple batteries, a connecting plate for electrically connecting the external terminals of one battery to the external terminals of another battery may be connectable by tightening nuts. This allows for the placement of connecting plates, such as busbars, between external terminals and, consequently, between electrodes, enabling power transfer between batteries and even power extraction from batteries. Furthermore, the use of nuts simplifies installation. 【0013】 The aforementioned battery has electrode terminals of both polarities, Different metallic materials are used for the internal terminals of the electrode terminals of both polarities. The same metallic material may be used for the external terminals of both polarity electrode terminals. As a result, the external terminals do not come into contact with the electrolyte (wetted), and welding between dissimilar metals is not required. This makes it possible to construct both electrode terminals from the same metal. For example, if electrical and thermal conductivity is important, copper-based materials can be used for the external terminals, while aluminum alloys can be used when weight reduction is a priority. On the other hand, for the internal terminals of the bipolar electrode terminals that come into contact with the electrolyte, different metal materials can be used in appropriate places, depending on the power generation aspect. [Effects of the Invention] 【0014】 The battery terminal structure according to the present invention is a structure that has not been used conventionally, and can maintain or improve sealing performance, leakage resistance, and / or characteristic changes. [Brief explanation of the drawing] 【0015】 [Figure 1] This is a schematic perspective view showing an example of the appearance of a single battery cell. [Figure 2] Figure (A) shows a schematic half-cross section of the sealing portion of the electrode terminals in a conventional battery cell, and Figure (B) shows a plan view of the welded portion of the busbar at the electrode terminals. [Figure 3] Figure (A) shows a schematic half-cross section of the sealing portion of the electrode terminals in a conventional battery cell, and Figure (B) shows a plan view of the busbar connection portion at the electrode terminals. [Figure 4]It is a schematic semi - cross - sectional side view of a sealing part of an electrode terminal in a battery cell according to an embodiment of the present invention (Figure (A)) and a plan view of a welding part of a bus bar in the electrode terminal (Figure (B)). [Figure 5] It is a schematic semi - cross - sectional side view of a sealing part of an electrode terminal in a battery cell according to the same embodiment (Figure (A)) and a plan view of a connection part of a bus bar in the electrode terminal (Figure (B)). 【Embodiments for Carrying Out the Invention】 【0016】 Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to these embodiments. not limited thereto. 【0017】 FIG. 1 shows an external view of a single battery (hereinafter also referred to as a cell) according to an embodiment of the present invention. In this embodiment, for example, a lithium - ion battery is used as the battery 500. The cell 500 in FIG. 1 has a non - polarized exterior can 510, a positive electrode terminal 520, and a negative electrode terminal 530. The positive electrode terminal 520 is insulated by an insulating plate 542, and the negative electrode terminal 530 is insulated by an insulating plate 543 (the insulating plates 542 and 543 are also collectively referred to as the insulating plate 540), and is insulated from the exterior can 510. The exterior can houses an electrode body, a separator, an electrolytic solution, etc. not shown. In the exterior can in which these are housed, the exterior can and a sealing body not shown that closes the opening of the exterior can are sealed by welding such as laser welding or by mechanical crimping such as caulking. 【0018】 As will be described in detail later, this embodiment relates to the structure of bipolar electrode terminals 520 and 530 installed on the exterior can 510 of the battery 500 via a gasket 400. The electrode terminals have an internal terminal that contacts the electrolytic solution in the exterior can 510 and an external terminal that does not contact the electrolytic solution, which will be described later. Further, these internal terminals and external terminals are screwed to the exterior can 510 for sealing. For example, the internal terminal and the external terminal are configured to be screwed together. 【0019】 In this embodiment, the configuration in which the internal and external terminals are screwed to the outer can 510, or the configuration in which the internal and external terminals are screwed together, allows for control of not only dimensional accuracy but also the crimping force of the gasket by the screw tightening torque, thus allowing for tolerance of component precision. Furthermore, with the above configuration, there is no thermal effect on the gasket that occurs when the internal and external terminals are fixed by welding, ensuring stable sealing performance. In addition, it is possible to install the external terminals after seam welding of the outer can, thus avoiding a decrease in the gasket's resilience due to creeping caused by heat. 【0020】 Furthermore, in this embodiment, the internal terminal has a male screw structure, and the external terminal has a female screw structure, with the internal and external terminals screwing together. By making the internal terminal a male screw structure and the external terminal a female screw structure, it is possible to minimize dead space inside the battery, and by installing a disc terminal that acts as a washer below the screw-type external terminal, damage caused by friction between the gasket and the terminal due to rotation can be prevented. In addition, by installing screws on the outside of the female-screwed external terminal, it becomes possible to fix the cells together using a nut structure. 【0021】 In this embodiment, the external terminals do not come into contact with the electrolyte (wetted), and welding between dissimilar metals is not required. Therefore, it is possible to construct both electrode terminals 520 and 530 from the same metal. When electrical and thermal conductivity is important, copper-based materials can be used for the external terminals, and when weight reduction is important, aluminum alloy materials can be used. On the other hand, for the internal terminals of the bipolar electrode terminals 520 and 530 that come into contact with the electrolyte, different metal materials are used in appropriate places, starting from the power generation side. [Examples] 【0022】 A comparative experiment was conducted using a prismatic lithium-ion battery with a capacity of 45Ah, consisting of cell 500 shown in Figure 1, in which NCM (811) lithium-ion battery NCM powder was used for the positive electrode terminal 520 and artificial graphite for the negative electrode terminal 530, and a non-polar aluminum alloy outer casing 510. The experiment aimed to compare the sealing performance due to differences in terminal structure. After the comparative experimental cell underwent a predetermined formation process, it was stored in a fully charged state at 60°C and 90%RH to check its performance and changes in leakage. The charge and discharge conditions were as follows. Charging conditions: 0.5CA (22.5A) constant current +4.2VCV charging 0.02CA (0.9A) cut @25℃ Discharge conditions: 0.5CA (22.5A) constant current, 2.75V cutoff @ 25℃ 【0023】 In the comparative experiment, two types of batteries were used: a single cell and a battery pack with 600 aluminum alloy connecting plates (hereinafter also referred to as busbars) attached by laser welding or screw fastening. Each specification was tested with n=6 cells, and n=2 cells were extracted every 15 days to check the discharge capacity. Since 15 days of storage at 60°C and 90% RH is a condition used for accelerated testing equivalent to one year at room temperature (20°C), the characteristics were checked at 25°C every 15 days and continued until after 45 days. Note that n indicates the number of test samples and is commonly used as the n number among those skilled in the art. 【0024】 <Conventional Example 1.> The following describes the terminal structures used in the comparative experiment. Unless otherwise specified, the following description refers to the positive electrode terminal 520. In the terminal structure of the rectangular lithium-ion battery of Conventional Example 1, as shown in Figure 2, the projection of the internal terminal 200, which has a flange portion and a protruding structure, is inserted into the central hole of the external terminal 300 through the central hole of the current collector tab 100, gasket 400, and sealing plate (not shown). After this, while holding down the peripheral part of the external terminal 300, the projection of the internal terminal 200 is crushed to a specified size using a rotary riveting machine and the gasket 400 is crimped, and the positive or negative electrode of the electrode body (not shown) is connected to the current collector tab 100 in the sealing body of this crimped terminal structure. After this, this terminal is inserted into the outer casing 510 and seam-welded with a laser (laser-welded part LZ1). Furthermore, sealing bodies were fabricated and compared using three types of components: one with the thickness dimensions of the internal terminal 200, external terminal 300, and gasket 400 set to the center value of the standard, one to the upper limit, and one to the lower limit. Here, a pure aluminum-based material was used for the positive terminal 520, and a pure copper material was used for the negative terminal 530. The busbar 600 had a hole larger than the outer diameter of the crimped portion, and was fixed to the outer diameter portion of the external terminal 300 by laser welding the inner diameter side of the said hole. 【0025】 <Conventional Example 2.> In a rectangular lithium-ion battery, as shown in Figure 3, an external terminal 300 having a flange portion and a bolt-shaped outer threaded portion 370 projecting longitudinally from there, and a cylindrical projection projecting on the opposite side, is inserted into a gasket 400, a sealing plate (not shown), a current collector tab 100 with a hole in the center, a retaining plate (not shown) with a hole in the center, and the central hole of the internal terminal 200. Then, with the external terminal 300 and the retaining plate sandwiched together, the outer circumference of the cylindrical projection and the outer circumference of the hole in the retaining plate are laser-welded to form a sealing body for the terminal, and the positive or negative electrode of the electrode body (not shown) is connected to the current collector tab 100. After this, this terminal is seam-welded to the outer casing 510 with a laser (laser-welded section LZ2). Here, a pure aluminum-based material is used for the positive electrode terminal 520, and a pure copper material is used for the negative electrode terminal 530. Furthermore, a busbar 600 with an inner diameter hole into which an external terminal 300 having a bolt structure on its outer circumference can be inserted is inserted, and the busbar 600 is fixed to the terminal by tightening a nut to a specified torque. 【0026】 <Example 1 of the present invention.> In a rectangular lithium-ion battery, as shown in Figure 4, an internal terminal 200 having a semi-threaded projection structure with the outer circumference 250 of the tip half threaded with a male screw was inserted into the central hole of the current collector tab 100, gasket 400, and sealing plate (not shown). After this, an external terminal 300, with the inner circumference 350 of the concave portion threaded with a female screw, was tightened to a specified torque on the internal terminal 200 to form a sealing body (not shown), and the positive or negative electrode of the electrode body (not shown) was connected to the current collector tab 100. After this, the electrode body was inserted into the outer casing 510, and the terminal was seam-welded to the outer casing 510 with a laser (laser-welded section LZ3). A pure aluminum-based material was used for the positive electrode terminal 520, and a pure copper material was used for the negative electrode terminal 530. Furthermore, a busbar 600 with an inner diameter hole into which the external terminal 300 can be inserted was inserted, and the inner diameter side of the hole was fixed to the outer diameter portion of the external terminal 300 by laser welding. 【0027】 <Example 2 of the present invention.> In a rectangular lithium-ion battery, as shown in Figure 5, an internal terminal 200 having a semi-threaded projection structure with the outer circumference 250 of the front half threaded with a male screw was inserted into the central hole of a metal disc MC, an example of a metal structure acting as a current collector tab 100, gasket 400, sealing plate (not shown), and washer. After this, an external terminal 300, with the inner circumference 350 of the concave portion threaded with a female screw, was tightened to a specified torque to form a sealing body (not shown), and the positive or negative electrode of the electrode body (not shown) was connected to the current collector tab 100. After this, the electrode body was inserted into the outer casing 510, and the terminal was seam-welded to the outer casing 510 using a laser. For the external terminal 300, both electrodes 520 and 530 were made of aluminum alloy, and for the internal terminal 200, the terminal components including other metal discs were made of pure aluminum for the positive electrode 520 and pure copper for the negative electrode 530. Furthermore, a busbar 600 with an inner diameter hole into which an external terminal 300 having a hollow bolt structure can be inserted was inserted, and the external terminal 300 was secured by tightening a nut 950 to a specified torque on its outer diameter portion. 【0028】 <Example 3 of the present invention.> In the rectangular lithium-ion battery, as shown in Figure 5, the structure is basically the same as in Conventional Example 2. However, the electrode body was inserted into the outer casing 510 and seam-welded with a laser before tightening the external terminals 300, and then the external terminals 300 were tightened to a specified torque. In addition, a busbar 600 with an inner diameter hole into which the external terminals 300, which have a hollow bolt structure, can be inserted was inserted, and the terminals were fixed by tightening nuts to a specified torque. 【0029】 [Table 1] 【0030】 [Table 2] 【0031】 [Table 3] 【0032】 [Evaluation test results] Table 1 shows the stacked dimensions that affect sealing performance due to dimensional variations in three types of sealing bodies using conventional example 1, where the thickness dimensions of the internal terminal 200, external terminal 300, and gasket 400 are set to the center value of the standard, the upper limit value, and the lower limit value. Although the difference in stacked dimensions is at most 0.15 mm, this value exceeds 10% of the gasket thickness and cannot necessarily be considered small. 【0033】 Table 2 shows the leakage rate when stored at 60°C and 90% RH. Leakage occurred at the upper and lower limits of the above variation in Conventional Example 1. It was also confirmed that the leakage resistance performance deteriorated in the specification where the busbar was laser welded. 【0034】 Table 3 shows the changes in properties after storage. In Conventional Example 1, the deterioration of properties due to storage was significant and the results were highly variable. Although stable results were obtained with the cell of this embodiment, it was confirmed that the sealing performance deteriorated when the BUS bar was welded by laser welding. In this embodiment, it is possible to suppress the thermal effects on the gasket, and an improvement in sealing performance can be expected. 【0035】 The present invention is not limited to the embodiments described above, and various additions, modifications, or deletions are possible without departing from the spirit of the invention. Therefore, such additions, modifications, or deletions are also included within the scope of the present invention. [Explanation of Symbols] 【0036】 100 Current collection tabs 200 Internal terminal 300 External terminals 400 Gasket 500 batteries (cells) 510 Outer can 520 Positive electrode (electrode terminal) 530 Negative electrode (electrode terminal) 540, 542, 543 Insulating boards 600 Busbar (Connecting Plate) LZ1, LZ2, LZ3 Laser Welded Sections MC Metal Disc (Metal Structure)

Claims

[Claim 1] A structure for one or both polarity electrode terminals installed on the battery casing via a gasket, The electrode terminal has an internal terminal that contacts the electrolyte inside the outer casing and an external terminal that does not contact the electrolyte. The internal terminal and the external terminal are sealed to the outer casing by screw fastening. Battery terminal structure. [Claim 2] The terminal structure of the battery according to claim 1, The internal terminal side has a male screw structure, and the external terminal side has a female screw structure, and the internal terminal and the external terminal are screwed together. Battery terminal structure. [Claim 3] The terminal structure of the battery according to claim 1, A metal structure acting as a washer is interposed between the external terminal and the gasket. Battery terminal structure. [Claim 4] The terminal structure of the battery according to claim 1, The aforementioned external terminal is, It has a hollow bolt structure, When electrically connecting multiple batteries, a connecting plate for electrically connecting the external terminals of one battery to the external terminals of another battery is connectable by tightening a nut. Battery terminal structure. [Claim 5] The terminal structure of the battery according to claim 1, The aforementioned battery has electrode terminals of both polarities, Different metallic materials are used for the internal terminals of the electrode terminals of both polarities. The same metallic material is used for the external terminals of both polarity electrode terminals. Battery terminal structure.

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