Electricity storage device and method for manufacturing the same

Abstract

To improve the anchor effect and sealing properties of an insulating resin material against the uneven surface formed in a seal portion of a connection portion that connects a current collecting terminal and an insulating resin material of a case member, thereby shortening a pressure holding and cooling time when molding the insulating resin material, and thereby improving productivity.SOLUTION: A power storage device 10 includes a current collecting terminal 3, a case member 4 having a terminal insertion hole 41, and an insulating resin member 5 connecting the current collecting terminal to a hole outer edge portion 411 and a hole surrounding portion 412 of the terminal insertion hole, the current collecting terminal and the case member have sealing portions 31T, 41T that ensure airtightness inside the case at connection portions 3T, 4T connected to the insulating resin member, the sealing portions are roughened surfaces 3S, 4S, the insulating resin member has a thermoplastic resin material NJ containing a high molecular weight substance KB having a molecular weight of 10,000 or more and a low molecular weight substance TB having a molecular weight of 500 to 5000, the low molecular weight substance is contained in the thermoplastic resin material at 5 to 15 wt.% and is unevenly distributed toward the roughened surface.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The disclosed technique relates to an electricity storage device and a method for manufacturing an electricity storage device. [Background technology]

[0002] For example, Patent Document 1 discloses a sealed storage battery in which an insulating resin member is integrally molded (insert molded) with a current collector terminal and a case member so as to fill the gap between the current collector terminal and the terminal insertion hole of the case member. It also discloses that a roughened surface is formed on at least a portion of the contact portion of the current collector terminal and the case member that contacts the insulating resin member, thereby enhancing the anchoring effect of the insulating resin member on the roughened, uneven surface. The insulating resin member is a resin material that has heat resistance, moldability, insulating properties, sealing properties, and resistance to electrolyte, and PPS resin (polyphenylene sulfide resin) is exemplified. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-86813 Summary of the Invention [Problem to be solved by the invention]

[0004] However, insulating resin members such as the PPS resin generally contain a large amount of high-molecular-weight materials with a molecular weight of 10,000 or more. These high-molecular-weight materials have a large molecular size in the molten state, making them difficult to penetrate into the narrow gaps between the convex portions of the roughened, uneven surface. This creates a problem: the molten resin of the insulating resin member cannot sufficiently penetrate into the gaps of the roughened, uneven surface during molding, preventing the insulating resin member from enhancing its anchoring effect on the uneven surface. Furthermore, the inability of the molten resin of the insulating resin member to sufficiently penetrate the gaps of the roughened, uneven surface creates cavities in the gaps, reducing the sealing ability of the insulating resin member at the contact points between the current collecting terminal and the case member.

[0005] Furthermore, the molecular size of the high molecular weight insulating resin material is large in the molten state, making it difficult for it to penetrate into the narrow gaps in the uneven surface that has been roughened during molding, so after the molten resin has been injected into the cavity of the mold, it is necessary to spend time holding the pressure and cooling the resin to force it into the gaps in the uneven surface.This results in the problem of long holding and cooling times, which reduces productivity.

[0006] The presently disclosed technology has been made in consideration of these problems, and the first problem to be solved is to improve the anchoring effect and sealing performance of the insulating resin member against the roughened uneven surface in an electricity storage device in which a roughened surface is formed on the sealing portion of the connection portion where the insulating resin member of the current collecting terminal and the case member are connected. The second problem is to improve productivity by shortening the dwell and cooling time when the insulating resin member is integrally molded (insert molding) with the current collecting terminal and the case member. [Means for solving the problem]

[0007] (1) One aspect of the disclosed technique for solving the above problem is an electricity storage device comprising: a current collecting terminal; a case member having a terminal insertion hole through which the current collecting terminal is inserted; and an insulating resin member into which the current collecting terminal and the case member are insert-molded so as to connect the hole insertion portion of the current collecting terminal with the hole outer edge portion and hole periphery portion of the terminal insertion hole; the current collecting terminal and the case member have sealing portions at their connection portions with the insulating resin member that ensure airtightness inside the case; each of the sealing portions has a roughened surface with an uneven surface formed thereon; the insulating resin member has a thermoplastic resin material containing a high molecular weight substance having a molecular weight of 10,000 or more and a low molecular weight substance having a molecular weight of 500 to 5,000; the low molecular weight substance is contained in the thermoplastic resin material in an amount of 5 to 15 wt % and is unevenly distributed toward the roughened surface.

[0008] (2) The electricity storage device according to (1) is preferably such that the uneven surface is formed to have an arithmetic mean roughness of 30 to 500 nm, and the amount of low-molecular-weight materials having a molecular weight of 500 to 1500 is increased in a resin surface layer portion close to the uneven surface compared to an inner resin layer portion away from the uneven surface.

[0009] (3) A manufacturing method of the electricity storage device described in (1) or (2) is preferably a manufacturing method of an electricity storage device including a resin injection step of using a molding die in which the collector terminal and the case member are inserted to injection-mold the insulating resin member, and filling gaps between convex portions on the uneven surface with the insulating resin member until the injection of the molten insulating resin member into the cavity of the molding die is completed. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is an exploded perspective view of one mode (this example) of an electricity storage device according to the present embodiment. [Figure 2] 2 is a cross-sectional view taken along the line AA in FIG. 1. [Figure 3] FIG. 3 is an enlarged cross-sectional view of part B shown in FIG. [Figure 4] FIG. 4 is an integrated molecular weight distribution curve showing the proportion of each molecular weight to the entire resin in the thermoplastic resin material of the insulating resin member of the present embodiment and the thermoplastic resin material of the insulating resin member of the comparative example shown in FIG. [Figure 5] 4 is a differential molecular weight distribution curve diagram showing the distribution state of each molecular weight in the thermoplastic resin material of the insulating resin member of the present embodiment and the thermoplastic resin material of the insulating resin member of the comparative example shown in FIG. 3. FIG. [Figure 6] 6 is a schematic cross-sectional view showing the positional relationship between high molecular weight molecules and low molecular weight molecules in the thermoplastic resin material of the insulating resin member of this embodiment shown in FIGS. 4 and 5 in the resin surface layer portion of the roughened surface shown in FIG. 3. [Figure 7] 6 is a schematic cross-sectional view showing the positional relationship between high molecular weight molecules and low molecular weight molecules in the thermoplastic resin material of the insulating resin member of the comparative example shown in FIGS. 4 and 5 in the resin surface layer portion of the roughened surface shown in FIG. 3. [Figure 8] FIG. 10 is a cross-sectional view of a molding die used in a method for manufacturing an electricity storage device according to this other embodiment in a closed state. [Figure 9] FIG. 9 is a flowchart of a method for manufacturing the electricity storage device using the molding die shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] <Description of this energy storage device> Next, one aspect (this example) of the electricity storage device 10 according to the embodiment of the disclosed technology will be described in detail with reference to the drawings. Fig. 1 shows an exploded perspective view of one aspect (this example) of the electricity storage device according to the embodiment. Fig. 2 shows a cross-sectional view taken along line AA in Fig. 1. Fig. 3 shows an enlarged cross-sectional view of part B in Fig. 2.

[0012] As shown in Figures 1 to 3, one form (this embodiment) of an electricity storage device 10 according to an embodiment of the disclosed technology includes a collector terminal 3, a case member 4 having a terminal insertion hole 41 through which the collector terminal 3 is inserted, and an insulating resin member 5 into which the collector terminal 3 and the case member 4 are insert-molded so as to connect the hole insertion portion 31 of the collector terminal 3 to the hole outer edge portion 411 and hole surrounding portion 412 of the terminal insertion hole 41.

[0013] Here, the present electricity storage device 10 includes an electrode assembly 1, a case body 2 having an opening 21 and accommodating the electrode assembly 1, a current collecting terminal 3 electrically connected to the electrode assembly 1, a case cover (corresponding to a "case member") 4 having a terminal insertion hole 41, which holds the current collecting terminal 3 inserted into the terminal insertion hole 41 and the electrode assembly 1 via the current collecting terminal 3, and which seals the opening 21 of the case body 2, and an insulating resin member 5 into which the current collecting terminal 3 and the case member 4 are insert-molded so as to connect the hole insertion portion 31 of the current collecting terminal 3 to the hole outer edge portion 411 and hole periphery portion 412 of the terminal insertion hole 41. However, the present electricity storage device 10 is not necessarily limited to the above configuration. For example, the terminal insertion hole 41 may be formed in the case body 2.

[0014] Here, the electricity storage device 10 refers to any electricity storage device capable of extracting electrical energy, and includes, for example, primary batteries, secondary batteries, and electric double layer capacitors. The electrode assembly 1 is a known electrode assembly in which a positive electrode body having a positive electrode active material layer and a negative electrode body having a negative electrode active material layer are stacked with a separator interposed therebetween. The case body 2 is a bottomed cylindrical body with an opening 21 formed at the upper end, and is made of, for example, aluminum or an aluminum alloy. The current collector terminal 3 is composed of a positive electrode current collector terminal 3a connected to the positive electrode side of the electrode assembly 1 and a negative electrode current collector terminal 3b connected to the negative electrode side. The positive electrode current collector terminal 3a is made of, for example, aluminum or an aluminum alloy, and the negative electrode current collector terminal 3b is made of, for example, copper or a copper alloy. The case lid (case member) 4 is formed as a flat plate-shaped lid made of, for example, aluminum or an aluminum alloy. The case cover (case member) 4 is formed with a terminal insertion hole 41 through which the current collector terminal 3 is inserted, a known safety valve 42, and a liquid injection hole 43 through which the electrolyte is injected. The insulating resin member 5 is made of a thermoplastic resin material NJ that has heat resistance, formability, insulating properties, sealing properties, resistance to the electrolyte, and the like. Here, PPS resin (polyphenylene sulfide resin) is used as the thermoplastic resin material NJ, but this is not a limitation. The insulating resin member 5 may contain a reinforcing material such as glass fiber, an elastomer, or the like within the thermoplastic resin material NJ.

[0015] 3, the current collecting terminal 3 and the case member 4 are provided with seal portions 31T and 41T at connection portions 3T and 4T where they are connected to the insulating resin member 5, respectively, to ensure airtightness within the case. The seal portion 31T of the current collecting terminal 3 is formed in an annular shape around the entire circumference of the insertion hole portion 31, and the seal portion 41T of the case member 4 is formed in an annular shape around the hole surrounding portion 412 along the terminal insertion hole 41. The current collecting terminal 3 is provided with an external connection portion 32 bent at a right angle to the insertion hole portion 31, and the case member 4 side of the external connection portion 32 is connected to the insulating resin member 5. The seal portions 31T and 41T are roughened surfaces 3S and 4S on which uneven surfaces 31S and 41S are formed, respectively. The uneven surfaces 31S and 41S are formed to have an arithmetic mean roughness of, for example, 30 to 500 nm. 3, P indicates a resin inner layer (core layer) that is spaced a distance d1 from the connecting portions 3T, 4T of 500 μm or more, and Q indicates a resin surface layer (skin layer) that is spaced a distance d2 from the connecting portions 3T, 4T of about 10 to 20 μm. The uneven surfaces 31S, 41S with an arithmetic mean roughness of 30 to 500 nm can be formed by, for example, irradiating the surfaces of the connecting portions 3T, 4T with a pulsed laser beam traveling in a certain direction to emit a fine mist of metal vapor, which then accumulates and solidifies in a forest-like pattern.

[0016] FIG. 4 shows an integrated molecular weight distribution curve representing the proportion of each molecular weight to the total resin content of the thermoplastic resin material of the insulating resin member of this embodiment shown in FIG. 3 and the thermoplastic resin material of the insulating resin member of the comparative example. FIG. 5 shows a differential molecular weight distribution curve representing the distribution state of each molecular weight of the thermoplastic resin material of the insulating resin member of this embodiment shown in FIG. 3 and the thermoplastic resin material of the insulating resin member of the comparative example. FIG. 6 shows a schematic cross-sectional view illustrating the positional relationship between high molecular weight and low molecular weight components in the thermoplastic resin material of the insulating resin member of this embodiment shown in FIGS. 4 and 5 at the resin surface layer of the roughened surface shown in FIG. 3. FIG. 7 shows a schematic cross-sectional view illustrating the positional relationship between high molecular weight and low molecular weight components in the thermoplastic resin material of the insulating resin member of the comparative example shown in FIGS. 4 and 5 at the resin surface layer of the roughened surface shown in FIG. 3.

[0017] The integrated molecular weight distribution curve shown in Figure 4 and the differential molecular weight distribution curve shown in Figure 5 can be determined by gel permeation chromatography (GPC) using the following procedure. First, a resin sample is dissolved in a solvent to prepare a sample solution. Next, the sample solution is passed through a column filled with porous granular gel having fine pores. The molecular size in the passed solution is detected by a detector, and a chromatogram is obtained showing the detection intensity of the molecular size versus detection time. Next, the detection time is converted to molecular weight using a calibration curve based on a standard substance with a known relationship between detection time and molecular weight. Then, molecular weight (logarithmic value) is plotted on the horizontal axis and concentration fraction on the vertical axis. The integrated molecular weight distribution curve shown in Figure 4 is completed by sequentially integrating the plotted concentration fractions and plotting the molecular weight (logarithmic value) on the horizontal axis and the integrated value of the concentration fraction on the vertical axis. Since the "integrated value of concentration fraction" corresponds to the "percentage of the total resin," the vertical axis in Figure 4 is labeled "percentage of the total resin (wt%)."

[0018] Next, the slope of the curve (differential value) for each molecular weight is determined for the integral molecular weight distribution curve shown in Figure 4. The differential molecular weight distribution curve shown in Figure 5 is completed by plotting molecular weight (logarithmic value) on the horizontal axis and differential value on the vertical axis. Therefore, the vertical axis of the differential molecular weight distribution curve is "dW / d(LogM)" (the value obtained by differentiating the concentration fraction by the logarithmic value of the molecular weight), and because this is proportional to the "concentration fraction," it is displayed here as the "concentration index." Specifically, a high-temperature GPC apparatus (apparatus no. GPC-H-2, Polymer Laboratories PL-GPC220), a detector (Refractive Index Detector (RI)), a column (Shodex UT-G (guard column)), and a solvent (1-chloronaphthalene (Fujifilm Wako Pure Chemical Industries)) were used. The sample solution was filtered through a 0.5 μm filter and then 0.2 mL was injected into the column heated to 210 °C at a flow rate of 0.7 mL / min. The integrated molecular weight distribution curve shown in Figure 4 and the differential molecular weight distribution curve shown in Figure 5 can be automatically generated using the application software provided with the high-temperature GPC apparatus (apparatus no. GPC-H-2, Polymer Laboratories PL-GPC220).

[0019] The integral molecular weight distribution curve 5W shown in FIG. 4 represents the molecular weight ratio of the thermoplastic resin material NJ of the insulating resin member 5 of this example to the entire resin, while the integral molecular weight distribution curve 5CW represents the molecular weight ratio of the thermoplastic resin material NJ of the insulating resin member 5C of the comparative example to the entire resin. X1 on the horizontal axis represents a molecular weight of 500, and X3 represents a molecular weight of 5000. The thermoplastic resin material NJ of the insulating resin member 5 of this example contains approximately 10% by weight of low-molecular-weight components TB with a molecular weight of 500 to 5000, and approximately 77% by weight of high-molecular-weight components KB with a molecular weight of 10,000 or more. In contrast, the thermoplastic resin material NJ of the insulating resin member 5C of the comparative example contains approximately 3% by weight of low-molecular-weight components TB3 with a molecular weight of 1,000 to 5,000, and approximately 78% by weight of high-molecular-weight components KB with a molecular weight of 10,000 or more. Therefore, the thermoplastic resin material NJ of the insulating resin member 5 of this embodiment and the thermoplastic resin material NJ of the insulating resin member 5C of the comparative example are similar in that they contain just under 80% by weight of high molecular weight substances KB with a molecular weight of 10,000 or more, but they differ significantly in the proportions of low molecular weight substances TB and TB3 with a molecular weight of 5,000 or less in the overall resin.They are also significantly different in that low molecular weight substances with a molecular weight of 1,000 or less are contained in the thermoplastic resin material NJ of the insulating resin member 5 of this embodiment, but not in the thermoplastic resin material NJ of the insulating resin member 5C of the comparative example.

[0020] Here, the low molecular weight substance TB having a molecular weight of 500 to 5,000 has a smaller molecular size in the molten state and has high fluidity and wettability in the molten state compared to the high molecular weight substance KB having a molecular weight of 10,000 or more, and therefore has the tendency to gather on the roughened surfaces 3S and 4S during molding.

[0021] Therefore, as shown in FIG. 6 , during molding of the thermoplastic resin material NJ of the insulating resin member 5 of this embodiment, low-molecular-weight substances TB having a molecular weight of 500 to 5,000 are liberated from high-molecular-weight substances KB having a molecular weight of 10,000 or more due to the fountain flow of the molten resin. These substances are concentrated in the resin surface layer (skin layer) Q adjacent to the roughened surfaces 3S and 4S, and are relatively easily able to penetrate into the narrow gaps SK between the convex portions 311S and 411S of the roughened uneven surfaces 31S and 41S. As a result, the resin containing the low-molecular-weight substances TB having a molecular weight of 500 to 5,000 fills the narrow gaps SK between the convex and concave surfaces 31S and 41S, enhancing the anchoring effect of the insulating resin member 5 to the convex and concave surfaces 31S and 41S. Furthermore, filling the narrow gaps SK between the convex and concave surfaces 31S and 41S with the resin containing the low-molecular-weight substances TB reduces the likelihood of voids forming in the gaps SK, improving the sealing performance of the insulating resin member 5.

[0022] In contrast, the thermoplastic resin material NJ of the comparative insulating resin member 5C contains only about 3% by weight of low-molecular-weight substance TB3 having a molecular weight of 1,000 to 5,000. Therefore, as shown in Fig. 7, even if the low-molecular-weight substance TB3 having a molecular weight of 1,000 to 5,000 is liberated from the high-molecular-weight substance KB having a molecular weight of 10,000 or more due to the fountain flow of the molten resin during molding, only a small amount of it collects in the resin surface layer (skin layer) Q adjacent to the roughened surfaces 31S, 41S, and does not easily penetrate into the narrow gaps SK between the convex portions 311S, 411S of the roughened uneven surfaces 31S, 41S. As a result, there are portions where the low-molecular-weight substance TB3 having a molecular weight of 1,000 to 5,000 is not filled in the narrow gaps SK between the uneven surfaces 31S, 41S, and the anchoring effect of the insulating resin member 5 to the uneven surfaces 31S, 41S is reduced. Furthermore, since the low-molecular-weight substance TB3 is not filled in the narrow gaps SK between the uneven surfaces 31S and 41S, voids KD are generated in the gaps SK, and the sealing performance of the insulating resin member 5C is also reduced.

[0023] On the other hand, if the low molecular weight substance TB having a molecular weight of 500 to 5000 is excessively increased, for example, if it is contained in an amount of about 20% by weight of the entire resin material in the thermoplastic resin material NJ of the insulating resin member 5, the heat resistance and the like will be reduced, making it difficult to maintain the characteristic values required for the electricity storage device 10. Therefore, it is preferable that the content of the low molecular weight substance TB having a molecular weight of 500 to 5000 in the entire resin material in the thermoplastic resin material NJ of the insulating resin member 5 does not exceed 15% by weight.

[0024] From the above, it has been found that in the energy storage device 10 of this embodiment, the insulating resin member 5 has a thermoplastic resin material NJ containing a high molecular weight material KB having a molecular weight of 10,000 or more and a low molecular weight material TB having a molecular weight of 500 to 5,000, and that the low molecular weight material TB is contained in the thermoplastic resin material NJ at 5 to 15% by weight and is preferably concentrated near the roughened surfaces 3S and 4S.

[0025] 5 shows a differential molecular weight distribution curve 5AZ representing the molecular weight concentration index of the thermoplastic resin material NJ in the resin inner layer portion P of the insulating resin member 5 of this example, a differential molecular weight distribution curve 5BZ representing the molecular weight concentration index of the thermoplastic resin material NJ in the resin surface layer portion Q of the insulating resin member 5 of this example, and a differential molecular weight distribution curve 5CZ representing the molecular weight concentration index of the thermoplastic resin material NJ in the resin surface layer portion Q of the insulating resin member 5C of the comparative example. X1 on the horizontal axis represents a molecular weight of 500, X2 represents a molecular weight of 1500, X3 represents a molecular weight of 5000, X4 represents a molecular weight of 10000, and X5 represents a molecular weight of 200000.

[0026] 5, the thermoplastic resin material NJ of the insulating resin member 5 of this embodiment and the thermoplastic resin material NJ of the insulating resin member 5C of the comparative example have a concentration index of about 35 at a molecular weight of 5000, which is almost the same. However, the thermoplastic resin material NJ of the insulating resin member 5 of this embodiment has a concentration index of about 15 at a molecular weight of 1500, while the thermoplastic resin material NJ of the insulating resin member 5C of the comparative example has a concentration index of about 5 at a molecular weight of 1500, so there is a significant difference in concentration index in the molecular weight range of 1500 or less. In particular, the thermoplastic resin material NJ of the insulating resin member 5 of this embodiment has an increased amount of second low-molecular-weight components TB2 having a molecular weight of 500 to 1500 in the resin surface layer portion Q compared to the resin inner layer portion P, and the concentration index of the low-molecular-weight components TB at a molecular weight of 500 to 1500 is maintained at a high level of about 13 to 17. In contrast, in the thermoplastic resin material NJ of the insulating resin member 5C of the comparative example, the concentration index of the low-molecular-weight substance TB3 in the resin surface layer portion Q also decreases from a concentration index of 3 (molecular weight 1500) to a concentration index of 0 (molecular weight 1000).

[0027] Therefore, as shown in Fig. 6, in the thermoplastic resin material NJ of the insulating resin member 5 of this embodiment, the second low-molecular-weight substance TB2 having a smaller molecular weight of 500 to 1500 is concentrated in the resin surface layer (skin layer) Q adjacent to the roughened surfaces 3S and 4S, and easily penetrates into the very narrow gaps SK between the convex portions 311S and 411S of the uneven surfaces 31S and 41S, which have an arithmetic mean roughness of 30 to 500 nm. As a result, the resin containing the second low-molecular-weight substance TB2 having a molecular weight of 500 to 1500 fills the narrow gaps SK between the uneven surfaces 31S and 41S, further enhancing the anchoring effect of the insulating resin member 5 to the uneven surfaces 31S and 41S. Furthermore, by filling the narrow gaps SK between the uneven surfaces 31S and 41S with the resin containing the second low-molecular-weight substance TB2, voids are less likely to form in the gaps SK, further improving the sealing performance of the insulating resin member 5.

[0028] In contrast, in the thermoplastic resin material NJ of the insulating resin member 5C of the comparative example, the concentration index of the low-molecular-weight substance TB3 in the resin surface layer portion Q is reduced from a concentration index of 3 for a molecular weight of 1500 to a concentration index of 0 for a molecular weight of 1000. Therefore, as shown in Fig. 7, only a small amount of resin containing low-molecular-weight substance TB3 of a molecular weight of 1500 or less is collected in the resin surface layer portion (skin layer) Q, and some of the resin is not filled in the narrow gaps SK between the convex portions 311S, 411S of the uneven surfaces 31S, 41S, reducing the anchoring effect of the insulating resin member 5 on the uneven surfaces 31S, 41S. Furthermore, because the low-molecular-weight substance TB3 is not filled in the narrow gaps SK between the uneven surfaces 31S, 41S, voids KD are formed in the gaps SK, reducing the sealing performance of the insulating resin member 5C.

[0029] From the above, it has been found that in the electricity storage device 10B of this example, the uneven surfaces 31S, 41S of the roughened surfaces 3S, 4S are formed to have an arithmetic mean roughness of 30 to 500 nm, and that the second low-molecular-weight material TB2 having a molecular weight of 500 to 1500 is more preferably contained in the resin surface layer portion Q adjacent to the uneven surfaces 31S, 41S than in the resin inner layer portion P away from the uneven surfaces 31S, 41S. That is, it has been found that it is more preferable that the low-molecular-weight material TB contains a larger amount of the second low-molecular-weight material TB2 having a molecular weight of 500 to 1500 in the resin surface layer portion Q adjacent to the uneven surfaces 31S, 41S than the first low-molecular-weight material TB1 having a molecular weight of 500 to 5000 in the resin inner layer portion P away from the uneven surfaces 31S, 41S.

[0030] Therefore, according to this embodiment, in the energy storage devices 10 and 10B in which roughened surfaces 3S and 4S are formed on the sealing portions 31T and 41T of the connection portions 3T and 4T that connect the collector terminal 3 and the insulating resin member 5 of the case member 4, the anchor effect and sealing property of the insulating resin member 5 against the roughened uneven surfaces 31S and 41S can be improved.

[0031] <Description of the method for manufacturing the present electricity storage device> Next, a method for manufacturing an electricity storage device according to another embodiment of the disclosed technique will be described in detail with reference to the drawings. Fig. 8 shows a cross-sectional view of a mold in a closed state used in the method for manufacturing an electricity storage device according to this embodiment. Fig. 9 shows a flowchart of the method for manufacturing this electricity storage device using the mold shown in Fig. 8.

[0032] As shown in Figures 6, 8 and 9, the manufacturing method for the present electricity storage device is a manufacturing method for the above-mentioned electricity storage devices 10, 10B, and includes a resin injection step S2 in which a molding die 6 is used to insert the collector terminal 3 and the case member 4 into and injection-mold the insulating resin member 5, and in which, with the molding die 6 in a closed state, the insulating resin member 5 fills the gaps SK between the convex portions 311S, 411S on the uneven surfaces 31S, 41S until the molten insulating resin member 5 is completely injected into the cavity 61 of the molding die 6.

[0033] 8, the molding die 6 includes a fixed die 62 and a movable die 63, each having a cavity 61 into which the current collector terminal 3 and the case member 4 can be inserted to injection mold the insulating resin member 5 when the die is closed. The fixed die 62 and the movable die 63 are provided with pipes 621 and 631 for heating and cooling the die temperature. The movable die 63 also includes a slide die 632 that moves between an advanced position where it presses the bent portion of the current collector terminal 3 and a retracted position where it can insert and remove the current collector terminal 3.

[0034] As shown in FIG. 9 , the manufacturing method for the electricity storage devices 10 and 10B includes a parts setting step S1 of setting the current collecting terminal 3 and the case member 4 in the molding die 6, a resin injection step S2 of injecting a molten insulating resin member 5 into the cavity 61 of the molding die 6, a pressure holding and cooling step S3 of applying internal pressure to the molten insulating resin member 5 while cooling it to a temperature at which it can be released from the molding die, and a demolding step S4 of opening the fixed die 62 and the movable die 63 and removing the insert-molded insulating resin member 5, the current collecting terminal 3 and the case member 4 from the molding die 6.

[0035] This method for manufacturing an electricity storage device includes a resin injection step S2 in which the gaps SK between the convex portions 311S, 411S of the uneven surfaces 31S, 41S are filled with the insulating resin member 5 before the injection of the molten insulating resin member 5 into the cavity 61 of the molding die 6 is completed. Therefore, when the insulating resin member 5 is integrally molded (insert molded) with the current collector terminal 3 and the case member 4, it is not necessary to cause the molten resin to enter the gaps SK between the uneven surfaces 31S, 41S while maintaining pressure and cooling after the injection of the molten resin of the insulating resin member 5 into the cavity 61 of the molding die 6 is completed. This makes it possible to shorten the time required for maintaining pressure and cooling after the injection of the molten resin, thereby improving productivity. Furthermore, by the time the molten resin is completely injected into the cavity 61 of the molding die 6, the gap SK between the uneven surfaces 31S, 41S is filled with the insulating resin member 5. Therefore, even if the pressure holding and cooling time after the injection of the molten resin is shortened, the anchoring effect of the insulating resin member 5 on the uneven surfaces 31S, 41S can be enhanced, and the sealing properties of the insulating resin member 5 can be improved.

[0036] Therefore, according to this manufacturing method for an electricity storage device, in electricity storage devices 10, 10B in which roughened surfaces 3S, 4S are formed on sealing portions 31T, 41T of connection portions 3T, 4T of the collector terminal 3 and the case member 4 that connect with the insulating resin member 5, the anchor effect and sealing properties of the insulating resin member 5 with respect to the roughened uneven surfaces 31S, 41S are improved, and the pressure holding and cooling time when the insulating resin member 5 is integrally molded (insert molded) with the collector terminal 3 and the case member 4 is shortened, thereby improving productivity.

[0037] The present embodiment described in detail above is merely an example and does not limit the disclosed technology in any way. Therefore, the disclosed technology can be improved and modified in various ways without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0038] 3 Current collector terminal 3S, 4S roughened surface 3T, 4T connection part 4 Case parts, case lid 5. Insulating resin material 6 Molding mold 10, 10B Energy storage device 31 Hole insertion part 31S, 41S uneven surface 31T, 41T seal part 41 Terminal insertion hole 61 Cavity 311S, 411S convex part 411 Hole outer edge 412 Hole Surrounding Area KB polymer NJ thermoplastic resin material P Resin inner layer Q Resin surface layer S2 Resin injection process SK Gap TB, TB1, TB2 low molecular weight

Claims

1. A current collecting terminal; a case member having a terminal insertion hole through which the current collecting terminal is inserted; an insulating resin member into which the current collecting terminal and the case member are insert-molded so as to connect the hole insertion portion of the current collecting terminal to the hole outer edge portion and hole periphery portion of the terminal insertion hole, the current collecting terminal and the case member are provided with a seal portion at a connection portion where the current collecting terminal and the case member are connected to the insulating resin member, the seal portion ensuring airtightness inside the case; The sealing portions are roughened surfaces on which concave and convex surfaces are formed, the insulating resin member comprises a thermoplastic resin material containing a high molecular weight substance having a molecular weight of 10,000 or more and a low molecular weight substance having a molecular weight of 500 to 5,000; The low molecular weight material is contained in the thermoplastic resin material in an amount of 5 to 15% by weight and is unevenly distributed near the roughened surface. Energy storage device.

2. The electricity storage device according to claim 1 , The uneven surface is formed to have an arithmetic mean roughness of 30 to 500 nm, In a resin surface layer portion close to the uneven surface, the amount of low molecular weight substances having a molecular weight of 500 to 1500 is increased compared to an inner resin layer portion away from the uneven surface. Energy storage device.

3. A method for manufacturing the electricity storage device according to claim 1 or 2, comprising: a molding die for injection-molding the insulating resin member by inserting the current collecting terminal and the case member; a resin injection step of filling gaps between convex portions on the uneven surface with the insulating resin material before the injection of the molten insulating resin material into the cavity of the molding die is completed; A method for manufacturing an electricity storage device.

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