JP6347102B2 - Method for manufacturing power storage device - Google Patents

Description

The present invention is a lithium ion secondary battery, lithium ion capacitor, a method of manufacturing a power storage device such as an electric double layer capacitor or an electrolytic capacitor.

  In a capacitor such as an electric double layer capacitor or an electrolytic capacitor in which a capacitor element is impregnated with an electrolytic solution, the electrolytic solution in the capacitor element flows out of the capacitor element and stays in the case. Moreover, in such a capacitor, a gas release mechanism that releases gas accumulated in the case when it is driven is installed, and this gas release mechanism includes a safety valve having gas permeability. Further, not only the capacitor but also a lithium ion secondary battery and a lithium ion capacitor are similarly provided with a gas release mechanism for releasing the gas remaining in the case.

  With regard to a capacitor provided with this safety valve, it is known that a Y-shaped protrusion is provided on a sealing plate that closes an outer case, and that an electrolyte does not contact an external terminal when the safety valve is activated (for example, Patent Documents) 1).

In addition, when the cap is fused to the resin case with ultrasonic waves, the electrolytic solution flowing out from the polarizable electrode of the capacitor element is blocked by a blocking wall provided on the cap side, and the fused portion is contaminated by the electrolytic solution. It is known to prevent (for example, Patent Document 2).

Japanese Utility Model Publication No. 55-129447 JP 2011-100998 A

  By the way, as a power storage device, for example, a safety valve of a capacitor is provided on a sealing plate that seals the case. In such a capacitor, since the safety valve is on the upper side in a normal mounting form, the electrolytic solution moves to the bottom side of the case. For this reason, even if electrolyte solution is kept away from the safety valve and the electrolyte solution has fluidity, the gas release function is not hindered by such electrolyte solution.

  However, when such a capacitor is arranged with the sealing plate with the safety valve facing downward, the electrolyte approaches the safety valve. The capacitor is ideally mounted with the safety valve on the upper side, but such an ideal package is not always maintained. Depending on the mounting environment, it is unavoidable to place the case horizontally or tilted. In such an arrangement, the fluid electrolyte solution may approach the safety valve, and the gas discharge function may be impaired due to the adhesion of the electrolyte solution.

  Even if the safety valve is separated from the electrolyte, if there is vibration, the fluid electrolyte will spring up from the bottom of the case, and the electrolyte attached to the inner wall of the case will reach the safety valve. May be damaged.

  A gas release mechanism such as a safety valve includes a gas permeation path and a valve function unit. When the electrolyte enters the gas permeation path, the gas permeation path is blocked by the electrolyte. Moreover, if electrolyte solution adheres to a valve function part, the gas pressure in a case cannot act directly on a valve function part. If the valve function part is covered with the electrolyte solution, the valve function due to the deterioration of gas permeability is reduced, and the gas release function such as the amount of gas release decreases and the valve opens due to the pressure increase. .

  In addition, in order to extend the life of the capacitor, an electrolyte may be enclosed in the case more than necessary. In such a case, the electrolytic solution having fluidity flows in the case.

Then, the objective of this invention exists in the prevention of the fall of the gas discharge | release function by the electrolyte solution of an electrical storage device in view of the said subject.

  In order to achieve the above object, a method for producing an electricity storage device according to the present invention is the production of an electricity storage device in which an electricity storage element impregnated with an electrolyte is housed in a case and the case is sealed with a sealing member having a gas release mechanism. A method of controlling the amount of electrolyte in the electricity storage element to an amount of electrolyte in which the amount of excess electrolyte flowing out from the electricity storage element is within a predetermined range after applying vibration with the electricity storage device in an inclined arrangement and leaving it for a predetermined time By doing so, adhesion of the excess electrolyte solution to a gas discharge | release mechanism is suppressed.

In the method for manufacturing the electricity storage device, the electricity storage device is disposed in an inclined range including 30 degrees, imparts a vibration of 5 [Hz] to 200 [Hz], and is left for 24 hours or more. The amount of the electrolyte flowing out may be controlled to be less than 1 [gram].
In the method for manufacturing the electricity storage device, the excess electrolyte that adheres to the gas release mechanism may be 1 [milligram] or less.
In the method for manufacturing the electricity storage device, the weight of the electrolyte impregnated in the electricity storage element is defined as the weight of the electrolyte, the weight of the electricity storage element before impregnation with the electrolyte is defined as the element weight, and the controlled electrolyte is supplied to the energy storage element. The mounting rate may be set in a range of electrolyte weight / element weight = 0.70 to 0.85.

  The method for manufacturing an electricity storage device may include a step of removing a predetermined amount of the electrolyte from the electricity storage element after impregnating the electricity storage element with the electrolyte.

  According to the present invention, the following effects can be obtained.

  (1) Since the electrolytic solution flowing out of the capacitor element and staying in the case is suppressed, it is possible to prevent the gas release function due to the adhesion of the electrolytic solution from being impaired.

  (2) Capacitors can be freely arranged such as laterally and obliquely arranged, and the function of the gas releasing mechanism due to the electrolyte staying in the case can be prevented from being deteriorated.

Other objects, features, and advantages of the present invention will become clearer with reference to the accompanying drawings and each embodiment.

It is a flowchart which shows an example of the manufacturing method of the electrical storage device which concerns on one embodiment. It is a figure which shows an example of the measuring method of an excess electrolyte solution. It is a figure which shows an example of an electrolyte solution suction device. It is a figure which shows the test method of a capacitor | condenser. It is a figure which shows the electrolyte solution adhesion condition of a safety valve. It is a figure which shows the change characteristic of an electrostatic capacitance.

[One embodiment]

  FIG. 1 shows an example of a manufacturing process of an electricity storage device according to an embodiment of the present invention. This manufacturing process is an example of a method for manufacturing an electricity storage device. The electric storage device according to this manufacturing process is, for example, an electric double layer capacitor, and may be another electric storage device such as an electrolytic capacitor, a lithium ion secondary battery, or a lithium ion capacitor.

  This manufacturing process includes a capacitor element formation step (S1), a first element weight measurement step (S2), an electrolyte impregnation step (S3), a second element weight measurement step (S4), and an excess electrolyte suction step (S5). ), A third element weight measurement step (S6), an electrolyte amount determination step (S7), and a case storage / sealing step (S8).

  In the capacitor element forming step (S1), a capacitor element that is an example of a power storage element is formed. In this forming step, winding is performed with a separator interposed between the electrode foils on the anode side and the cathode side.

  In the element weight measuring step (S2), the element weight of the capacitor element obtained in the capacitor element forming step is measured. This element weight is the weight of the capacitor element before impregnation with the electrolytic solution. The capacitor element weight Wref after impregnation with the electrolytic solution is set with respect to this weight. A set value: Wref ± ΔW is determined using the element weight Wref as a median value and a reference value assuming an allowable range ± ΔW. The allowable range ± ΔW may be assumed to be a variation that does not cause inconvenience.

  After the determination of the set value, in the electrolytic solution impregnation step (S3), the capacitor element is impregnated with the electrolytic solution.

  In the element weight measuring step (S4), the element weight of the capacitor element that has undergone the electrolytic solution impregnation step is measured. This element weight is the weight of the capacitor element after impregnating the electrolytic solution, and is a value obtained by adding the weight of the impregnating electrolyte to the weight of the capacitor element before impregnating the electrolytic solution.

  In the electrolytic solution suction step (S5), the electrolytic solution is sucked from the capacitor element impregnated with the electrolytic solution, and an excessive amount of electrolytic solution is removed from the capacitor element.

Assuming that the element weight before impregnation with the electrolyte solution is W1 and the element weight after the electrolyte solution impregnation is W2, the amount of electrolyte impregnation Wa from these element weights W1 and W2 is:
W2-W1 = Wa (1)
It becomes. Therefore, if the expected amount of impregnation is defined as Wf with respect to the amount of impregnation of electrolyte Wa, the amount of removed electrolyte ΔW sucked in S5 is
ΔW = Wa−Wf (2)
It becomes. This removed electrolytic solution amount ΔW is an ideal amount of electrolytic solution sucked from the capacitor.

  In the element weight measurement step (S6), the element weight after the electrolytic solution is removed with the electrolytic solution suction amount is measured. This element weight is defined as W3.

  In the electrolytic solution amount determining step (S7), the amount of impregnated electrolytic solution in the capacitor element is determined. It is determined whether or not the element weight W3 obtained in the element weight measurement step (S6) is out of the set value Wref ± ΔW by comparison with the set value Wref ± ΔW (S71).

  Therefore, in S72, Wref−ΔW ≦ W3 is determined. If Wref−ΔW ≦ W3 (NO in S72), the amount of the impregnating electrolyte is small, so the capacitor element is impregnated with the electrolyte again (S3), and the process proceeds to S7 through S4, S5, and S6.

  If Wref−ΔW ≦ W3 (YES in S72), the process proceeds to S73. In S73, it is determined whether or not W3 ≦ Wref + ΔW (S73). If W3 ≦ Wref + ΔW (NO in S73), the amount of impregnated electrolyte is excessive, so the electrolyte is sucked again from the capacitor element (S5), and the process proceeds to S7 via S6.

  If Wref−ΔW ≦ W3 ≦ Wref + ΔW, the element weight of the capacitor element impregnated with the electrolytic solution is within the range of the set value Wref ± ΔW and is appropriate.

  In the case storage / sealing step (S8), the capacitor element in which the amount of impregnation of the electrolyte is controlled to an appropriate value is stored in the case, and the case is sealed with a sealing member. Thereby, the capacitor is completed.

  According to such a manufacturing process, for example, the amount of the electrolyte solution in the capacitor element is controlled to be less than 1.0 [g]. By controlling the amount of excess electrolyte, it is possible to control the amount of electrolyte in the capacitor element to an appropriate amount, and to suppress the flowing excess electrolyte from flowing out of the capacitor element and staying in the case. it can.

  FIG. 2 shows a method for measuring the excess electrolyte of the capacitor. This surplus electrolyte solution measuring method is a method in which the surplus electrolyte solution 4 is collected from the capacitor 2 and the amount of the electrolyte solution is measured.

  In the capacitor 2 used for this measurement method, a capacitor element 6 impregnated with an electrolytic solution 4 is housed in a case 8, and the case 8 is sealed with a sealing member 10. The sealing member 10 includes a gas release mechanism 12. The gas release mechanism 12 includes a gas release hole 14 in the sealing member 10, and a safety valve 16 is installed in the gas release hole 14. The safety valve 16 is made of a gas permeable material and discharges the gas in the case 8.

  The capacitor 2 is installed at an inclination angle θ with the sealing member 10 facing down. The electrolytic solution 4 impregnated in the capacitor element 6 has fluidity, and the excess electrolytic solution 4 stays in the case 8. In this case, the capacitor 2 is maintained such that the safety valve 16 in the sealing member 10 is located above the center position of the sealing member 10 so as to be away from the excess electrolyte solution 4, for example.

  As a method for measuring the excess electrolyte solution 4 of the capacitor 2, the inclination angle θ is set to be 30 [°]. Vibration is applied to the capacitor 2 maintained in this state. The vibration frequency f has a lower limit frequency fmin of, for example, 5 [Hz] and an upper limit frequency fmax of, for example, 200 [Hz], and gives vibration in this frequency range. The capacitor 2 is given 20 [G] as gravity. In this state, it is left at a constant environmental temperature, for example, 60 [° C.], and this standing time is set to a predetermined time, for example, 24 [hour].

  An electrolytic solution discharge hole 18 is formed in the case 8 of the capacitor 2 left under such conditions. A discharge pipe 20 is attached to the electrolyte discharge hole 18, and excess electrolyte 4 that has flowed out of the case 8 from the case 8 through the discharge pipe 20 is collected in the measurement container 22. The electrolyte solution 4 stored in the measurement container 22 is measured with a weighing meter 24. This measured value is the surplus electrolyte amount. The amount of the electrolytic solution is obtained by weight, but the volume is obtained from this weight and the specific gravity of the electrolytic solution 4.

  FIG. 3 shows an example of the electrolyte solution suction device. The electrolytic solution 4 impregnated in the capacitor element 6 is placed in the suction device 28 and sucked, and the amount of the electrolytic solution in the capacitor element 6 is controlled to an appropriate amount.

  The suction device 28 includes a placement unit 30 and a suction unit 32. A capacitor element 6 impregnated with the electrolytic solution 4 is installed on the mounting portion 30. A suction part 32 is attached to the bottom side of the mounting part 30. The electrolytic solution 4 is sucked into the suction portion 32 from each capacitor element 6 on the mounting portion 30, and the electrolytic solution 4 is discharged from the capacitor element 6. Thereby, the amount of the electrolyte contained in the capacitor element 6 can be controlled to an appropriate amount.

<Features and effects of one embodiment>

  (1) In the above embodiment, the weight of the electrolytic solution 4 impregnated in the capacitor element 6 is set as the electrolytic solution weight, and the weight of the unimpregnated capacitor element 6 in the electrolytic solution 4 is set as the element weight. The weight of the unimpregnated element is measured, the electrolyte solution 4 is impregnated based on the mounting rate, and the excess is removed.

  In the capacitor element 6, the heavier the element weight, the longer the electrodes and separators, and the more electrolyte solution can be held in the capacitor element 6. That is, the amount of electrolyte solution that can be held is small when the element weight is light. When the capacitor element 6 is manufactured, the weight of the element varies, and the amount of electrolyte after impregnation varies from capacitor element 6 to capacitor element 6. If the amount of the electrolytic solution contained in the capacitor element 6 is different, the amount of the electrolytic solution that can be removed is also different. Therefore, in the manufacturing process, the amount of electrolyte can be managed by the mounting rate obtained by dividing the amount of electrolyte by the element weight. That is, the mounting rate may be applied to the above-described calculation standard for the planned impregnation amount (Wf).

  Specifically, when the weight of the electrolytic solution impregnated in the power storage element is the weight of the electrolytic solution, and the weight of the power storage element before impregnation of the electrolytic solution is the element weight, the mounting ratio of the electrolytic solution to the power storage element is Weight / element weight = 0.70 to 0.85 is preferable.

  (2) In order to make the amount of excess electrolyte less than 1.0 [g] as an example, the mounting rate of the electrolyte may be controlled. Moreover, in order to make the excess electrolyte solution adhering to the gas release mechanism 1 [milligram] or less, the mounting rate of the electrolyte solution may be similarly controlled. In this case, the outflow of the electrolyte solution 4 can be suppressed by setting to a predetermined mounting rate.

  (3) The amount of impregnation of the electrolytic solution 4 of the capacitor element 6 can be controlled to an appropriate value by such treatment. As a result, even when the capacitor 2 is placed horizontally or inclined, the electrolytic solution 4 flowing out from the capacitor element 6 can be prevented from reaching the safety valve 16 that is a gas release mechanism. It is possible to prevent inconveniences such as a decrease in the gas release function due to clogging and adhesion of the electrolytic solution 4.

  (4) Since the electrolyte 4 flowing in the case 8 is reduced even when intense vibration is applied at the time of engine start-up, which is mounted on a vehicle device with vibration, the electrolyte 4 can be prevented from jumping up. The electrolytic solution 4 can be prevented from adhering to the safety valve 16.

  (5) Concerning the amount of electrolyte impregnated in the capacitor element 6, the capacitor 2 is disposed obliquely (for example, with a 30 ° gradient), and the vibration frequency is, for example, 5 [Hz] to 200 [Hz], gravity 20 [G ], The excess amount of electrolyte after 24 hours is set to 1.0 [g] or less, for example. In this case, the safety valve 16 is installed on the upper side of the sealing member 10 when placed horizontally, and the amount of the electrolytic solution to be removed may be in the range of 2 [g] to 8 [g]. If it does in this way, adhesion of electrolyte solution to safety valve 16 can be controlled, and electrolyte solution which adheres to a safety valve can be controlled below 1 [milligram].

  (6) The electrolytic solution 4 is removed as described in the above embodiment by setting a reference value for the weight of the element including the electrolytic solution 4, specifying the excess electrolytic solution 4 from the weight after the impregnation with the electrolytic solution, Control to quantitative.

  (7) By controlling the amount of surplus electrolyte in this way, it is possible to avoid the influence of the electrolyte 4 adhering to the safety valve 16 and to maintain the gas permeation function. it can.

<Test method and results>

  FIG. 4 is a diagram illustrating a capacitor testing method. This test method inspects the situation where the electrolyte contained in the capacitor adheres to the capacitor gas release mechanism.

  The capacitor 2 described above is used as the test capacitor. The capacitor 2 has a height of φ45 mm and 135 mm. The manufacturing process of the capacitor 2 includes impregnation with the electrolyte solution 4, removal of the electrolyte solution 4, case sealing, caulking, and aging.

  As shown in FIG. 4A, the capacitor element 6 is impregnated with the electrolytic solution 4. FIG. 4B shows the capacitor element 6 after impregnation with the electrolytic solution. As shown in FIG. 4C, the excess electrolytic solution 4 is removed from the capacitor element 6, and the removal amount of the electrolytic solution 4 is taken as an example: a: 0 [g], b: -2 [g], c : -4 [g], d: -5 [g], e: -6 [g], f: -8 [g]. In this case, the removal amount of the electrolytic solution 4 is varied, and the mounting rate of the electrolytic solution is taken as an example, a: 0.90, b: 0.86, c: 0.80, d0.77, e: 0.75, f: A plurality of capacitors including the capacitor element 6 set to 0.70 are created.

  Each capacitor element 6 is enclosed in a case 8 and the case 8 is sealed with a sealing member 10. In this case, the case 8 is caulked for sealing. 4D shows the capacitor 2 after crimping. A caulking portion 34 is formed in the case 8.

  As shown to E of FIG. 4, the case 8 of the capacitor | condenser 2 is laterally caulked and the aging process for a predetermined time is performed. F of FIG. 4 shows the capacitor 2 after aging. The case 8 is formed with a plurality of caulking portions 34 in a band shape by the lateral caulking described above.

  G in FIG. 4 shows an arrangement state of one capacitor 2. In this experiment, each capacitor 2 was maintained at an inclination angle θ from the reference plane 36, and the inclination angle θ was left at θ = 30 [°], for example. As an example, the ambient temperature of the capacitor 2 was set to 60 [° C.]. The safety valve 16 is disposed on the upper side of the sealing plate of the capacitor 2 in the same manner as the capacitor shown in FIG.

  A vibration test was performed on each capacitor 2 that was allowed to stand in such an environment. In this vibration test, the lower limit frequency fmin, for example, 5 [Hz] is changed within the range of the upper limit frequency fmax, for example, 200 [Hz], a gravity of 20 [G] is applied, and left for a fixed time, for example, 24 [hour]. Thereby, the test results shown in FIGS. 5 and 6 were obtained.

  FIG. 5 shows the state of electrolyte solution adhesion of the safety valve 16. The safety valve 16 is taken out from each capacitor 2 after the test, and the adhesion state of the electrolytic solution to the safety valve is observed. Moreover, the adhesion amount of the electrolyte solution to the safety valve 16 was measured, respectively. In addition, the amount of surplus electrolyte solution flowing out from the capacitor element of each capacitor 2 after the test was measured, and the mounting rate of the electrolyte solution on the capacitor element was also described.

  In a and b, the amount of the electrolyte 4 attached to the safety valve 16 is large. Such an adhesion amount reduces the gas release function of the safety valve 16. In particular, the electrolyte solution 4 has adhered to the gas permeation site that is recessed in the center of the safety valve 16.

  In c, the mounting ratio of the electrolytic solution is low, the amount of the electrolytic solution 4 attached to the safety valve 16 is small, and the electrolytic solution 4 is also hardly attached to the gas permeation portion of the safety valve 16, which is favorable. In d, e, and f, the mounting rate of the electrolytic solution is low, and the electrolytic solution 4 hardly adheres.

  FIG. 6 shows a change characteristic of the capacitance. In addition, the measurement conditions are 2.5 [V] voltage application and 70 degree environment. As can be seen from FIG. 6, no significant difference is observed in the rate of change in the capacitance with respect to the amount of the electrolytic solution 4. However, although not shown in the figure, in a capacitor having an electrolytic solution mounting rate of less than 0.70, performance deterioration such as capacitance due to dry-up occurs when used for a long time.

  The amount of the electrolytic solution removed from the capacitor element 6 is adjusted according to the size of the capacitor element 6. In the case of a winding type capacitor (about φ20 to φ100 [mm]), the removal amount and the excess electrolyte amount may be in the ranges described above. The size of the safety valve 16 formed by φ also changes. The safety valve 16 is, for example, about φ2 to φ10 [mm]. Further, although the amount of excess electrolyte flowing out from the capacitor element depends on the size of the capacitor element 6, the amount of the electrolyte solution mounted on the capacitor element 6 is set to a certain range as described above. If the surplus electrolyte amount is 1.0 [g] or more, the adhesion region and the adhesion amount to the safety valve 16 are large, and the gas permeation function of the safety valve 16 is reduced.

  In addition, the amount of electrolyte solution impregnated in the capacitor element 6 and its state are such that the electrolyte solution 4 does not flow out of the capacitor element 6 even when vibrations are applied, and the electrolyte solution 4 has an electric capacity such as capacitance. It is necessary to be included in the capacitor element 6 to such an extent that the mechanical characteristics can be maintained. According to the above test results, the amount of reduction of the electrolyte solution 4 does not affect the change in capacitance, and the amount of reduction that prevents deterioration of the function of the safety valve 16 maintains the capacitance as a highly reliable value. It has been confirmed that

[Other Embodiments]

  In the above embodiment, a reference value is set for the element weight of the capacitor element 6, but this reference value may be a theoretical value, and the measured value is comprehensively determined, and an appropriate statistical value or measured value is determined. It may be.

As described above, the most preferable embodiment of the present invention has been described. The present invention is not limited to the above description. Various modifications and changes can be made by those skilled in the art based on the gist of the invention described in the claims or disclosed in the embodiments for carrying out the invention. It goes without saying that such modifications and changes are included in the scope of the present invention.

According to the electricity storage device of the present invention and the manufacturing method thereof, the electrolyte solution impregnated in the electricity storage element can be controlled to an appropriate value. It is possible to prevent the electrolyte from adhering to the safety valve of the release mechanism, to prevent the gas release function from being lowered due to the adhesion, and to provide a highly reliable power storage device such as a capacitor.

2 Capacitor 4 Electrolyte 6 Capacitor Element 8 Case 10 Sealing Member 12 Gas Release Mechanism 14 Gas Release Hole 16 Safety Valve 18 Electrolyte Discharge Hole 20 Discharge Pipe 22 Measuring Container 24 Weighing Meter 28 Suction Device 30 Placement Unit 32 Suction Unit 34 Clamping Part 36 Reference plane

Claims (5)

An electricity storage device impregnated with an electrolytic solution is housed in a case, and the case is a method for producing an electricity storage device sealed with a sealing member having a gas release mechanism,
By applying vibration to the electricity storage device in an inclined arrangement and leaving it for a predetermined period of time, the amount of excess electrolyte flowing out from the electricity storage element is controlled to an amount of electrolyte in a predetermined range, thereby controlling the amount of electrolyte in the electricity storage element. The manufacturing method of the electrical storage device characterized by suppressing attachment of the excess electrolyte solution to a discharge | release mechanism. The electricity storage device is inclined in an inclination range including 30 degrees, applied with a vibration of 5 Hz to 200 Hz, left for 24 hours or longer, and the amount of electrolyte flowing out of the electricity storage element is 1 [ The method of manufacturing an electricity storage device according to claim 1, wherein the storage device is controlled to be less than [gram]. 3. The method for manufacturing an electricity storage device according to claim 1, wherein an excess electrolytic solution adhering to the gas release mechanism is 1 [milligram] or less. The weight of the electrolytic solution impregnated in the electric storage element is defined as the weight of the electrolytic solution, the weight of the electric storage element before impregnation with the electrolytic solution is defined as the element weight, and the mounting rate of the controlled electrolytic solution in the electric storage element is expressed as electrolyte weight / The method for manufacturing an electricity storage device according to any one of claims 1 to 3, wherein the element weight is set in a range of 0.70 to 0.85. Removing a predetermined amount of the electrolytic solution from the electrical storage element after impregnating the electrical storage element with the electrolytic solution;
Method for producing a device according to any of claims 1 to 4, characterized in that it comprises a.

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