JPH06176767A - Inspection in assembly line of spiral battery - Google Patents

Abstract

PURPOSE:To easily perform inspection of a spiral battery on an assembly line, and to surely discriminate shortage of the amount of electrolyte at high sensitivity. CONSTITUTION:Layered materials of a positive electrode 2 in the form of a thin sheet, a separator 3, and a negative electrode 4, is spiraled into a cylindrical form, while lead tubs 6, 7 are connected to the positive electrode 2 and the negative electrode 4, respectively, and an electrode set parts 1 is thus provided. The electrode set parts 1 is fitted in a bottomed cylindrical battery case 11 made of metal. After either lead tub 6 or 7 is connected to the battery case 11, a predetermined amount of electrolyte is injected into the battery case 11. After a predetermined period of time elapses since injection of the electrolyte into the battery case 11, a measurement electrode 12 is abutted on a predetermined part of the separator 3, by which the electrolyte is absorbed, to measure the impedance between the separator 3 and the positive electrode lead tub or the negative electrode lead tub by a.c. method. The measured value is compared with a reference, and it is judged whether a product in the middle of assembly is good or defective.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a manufacturing technique of a spiral type battery having a spiral structure electrode set component represented by a cylindrical lithium battery, and more particularly, to an electrolytic solution obtained by loading an electrode set component in a battery case. The present invention relates to a method of indirectly inspecting whether or not a predetermined amount of electrolytic solution is correctly injected in a step after the injection of.

[0002]

2. Description of the Related Art Many cylindrical lithium batteries, cylindrical nickel-cadmium batteries and the like employ an internal structure (referred to as a spiral battery) as shown in FIG. The electrode set component 1 which is the object of the present invention is mainly composed of a thin sheet-shaped positive electrode 2, a separator 3 and a negative electrode 4 which are alternately opposed to each other and spirally wound into a cylindrical shape. The insulating disk 5 is applied to one end of the cylindrical body, and the positive electrode 2 and the negative electrode 4 are provided.
Lead tabs 6 and 7 respectively connected to the above are drawn out to both ends of the cylindrical body. A thin cylindrical portion 5a is integrally formed at the center of the insulating disk 5, and the cylindrical portion 5a is formed.
a is inserted into the lower end side of the center hole 1a of the electrode setting component 1. The lead tab 6 drawn out to the lower end side of the electrode set component 1 is bent to the lower surface side of the insulating disk 5, and its tip portion 6a (formed in a circular shape) is arranged concentrically with the central hole 1a and the tubular portion 5a. Thus, the lower end of the center hole 1a is closed by the lead tab tip portion 6a.

The leading end side of the lead tab 7 that is pulled out to the upper end side of the electrode setting component 1 is connected to the lid setting component 8. The lid set component 8 includes a terminal plate 9 made of metal and a sealing gasket 10 combined with the outer periphery thereof, as well as the terminal plate 9
A safety valve mechanism (not shown) that is integrally incorporated inside is provided.

This type of spiral type battery is assembled through the following steps. Bottomed cylindrical metal battery case 11
The electrode set component 1 is housed inside. At that time, the insulating disk 5 is turned down. Then, the lead tab tip portion 6a applied to the lower surface center of the insulating disk 5 contacts the center portion of the inner bottom surface of the battery case 11, but the lead tab tip portion 6a is spot welded to the bottom surface of the battery case 11 in the next step. .

After that, a predetermined amount of the electrolytic solution is injected into the battery case 11, and the lid setting component 8 closes the opening of the battery case 11 to proceed to the sealing step.

[0006]

SUMMARY OF THE INVENTION In the assembly line for spiral type batteries having the above-mentioned structure, the mechanism for injecting the electrolytic solution into the battery case causes a malfunction for some reason, and the specified amount of the electrolytic solution is not correctly injected. Sometimes. It is not a problem if a little more than the prescribed amount of electrolyte is injected, but if the amount of electrolyte injected is insufficient, the discharge performance will be significantly reduced, and such products must be treated as defective products.

Therefore, in some conventional methods, the weight of the assembly immediately before entering the liquid injection stage is measured, and the weight of the assembly that comes out of the liquid injection stage is measured, and the weight is injected from the difference between the two measured values. In addition, an inspection method is adopted in which the amount (weight) of the electrolyte solution is calculated and an insufficient amount of the solution is detected.

There are the following problems in applying this inspection method to a high-speed automated assembly line. Since the weight of the injected electrolyte is considerably smaller than the total weight of the assembly, it is necessary to measure the weight with a high degree of accuracy. It is very difficult to realize a mechanism for accurate weight measurement. Such a measuring mechanism must be provided in two places, and the cost will increase. In addition, the data measured one after another at two locations must be processed accurately, and two data on the same assembly must be calculated without being confused with other data. There will be a cost.

The internal resistance is measured as a final inspection of the battery which has been assembled for the time being. Since the internal resistance of a battery having a remarkably small amount of electrolyte is considerably high, defective products can be found by the final inspection.
However, in the internal resistance inspection, it is not possible to reliably discriminate a battery having an electrolyte deficiency of less than 50%. From the viewpoint of the overall discharge characteristics, even a battery with an electrolyte deficiency of about 20% must be considered as a defective product, but an internal resistance test passes if this amount of deficiency is insufficient. Furthermore, even if a defective product with insufficient electrolyte is found in the final inspection, it is difficult to replenish the product with electrolyte.

The present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to be easily implemented on an assembly line of a spiral type battery, and to ensure a high sensitivity with respect to a shortage of an electrolyte solution. It is to provide an inspection method capable of making a discrimination.

[0011]

Therefore, in the present invention, a laminate of a thin sheet-shaped positive electrode, a separator and a negative electrode is spirally wound into a cylindrical shape and lead tabs are connected to the positive electrode and the negative electrode, respectively. A spiral-type battery assembly line in which an electrode set component is loaded in a bottomed cylindrical metal battery case, one of the lead tabs is connected to the battery case, and then a predetermined amount of electrolyte is injected into the battery case. In, after injecting the electrolytic solution into the battery case for a predetermined time, applying a measurement electrode to a predetermined portion of the separator that has absorbed the electrolytic solution, the separator and the positive electrode lead tab or the negative electrode lead tab. The impedance between the
The measured value is compared with the reference value and the
I decided to judge the defect.

[0012]

When the separator sufficiently absorbs the electrolytic solution, the impedance between the separator and one of the lead tabs is low, and when the amount of the electrolytic solution is small, the impedance is high. The correlation between the electrolytic solution and the impedance remarkably appears from the low level of the insufficient state.

[0013]

EXAMPLE An example of an embodiment of the inspection method of the present invention is shown in FIG.
Is shown in. As described above, the electrode set component 1 is loaded into the battery case 11, and the positive electrode lead tab 6 is attached to the case 11.
Spot welding is carried out at the center of the inner bottom surface of, and then a predetermined amount of electrolytic solution is injected into the case 11. Thereafter, the separator 3 is left for a certain period of time to allow the separator 3 to sufficiently absorb the electrolytic solution, and then the inspection of the present invention is carried out.

In conducting the inspection, first, the thin measuring electrode 1
2 is inserted into the center hole 1a of the electrode set component 1 to a predetermined depth, and the electrode portion at the tip thereof is brought into contact with the separator 3 exposed at the innermost circumference of the center hole 1a. Further, the other measurement electrode 13 is connected to the battery case 11. The measurement electrodes 12 and 13 are connected to the impedance measuring unit 14, and the impedance between the electrodes 12 and 13 (the impedance between the separator 3 and the positive electrode 2) is measured by the AC method. The measured data is transferred to the comparison unit 15 and compared with a reference value. If the impedance is less than or equal to the reference value, it is determined as a good product, and if the impedance exceeds the reference value, it is determined as a defective product.

FIG. 3 shows a specific example of the correlation between the impedance and the amount of electrolytic solution in the inspection method of the present invention. This example is a test result of a CR2 / 38 type lithium battery, and the impedance measurement (AC method under the condition of 1 KHz and 1 mA) is performed in the above-described form by injecting the electrolytic solution and leaving it for 30 minutes. The regular amount of electrolyte injected in this battery is 1.8 grams, but the correlation between the amount of electrolyte and impedance is very remarkable. In particular, a substantially linear change characteristic can be obtained over a wide range on the electrolyte-deficient side, and the rate of change is sufficiently large, so that a slight lack of the liquid amount can be detected with high sensitivity. For example, if the impedance shown by the dotted line in FIG. 3 is used as the determination reference value, it is possible to detect a liquid amount shortage of about 10%.

The impedance between the measurement electrode 12 applied to the separator 3 and the negative electrode lead tab 7 (or terminal plate 9) side may be measured, but the battery case 11
It is easier to measure the side as one pole.

[0017]

As described in detail above, in the present invention, by measuring the impedance between the separator absorbing the electrolytic solution and the positive electrode lead tab or the negative electrode lead tab in the latter stage of the liquid injection step by the AC method, Indirectly,
Insufficient injection amount of electrolyte can be detected with extremely high sensitivity. This operation of impedance measurement is much simpler than the conventional system that weighs highly accurately at two points and calculates the liquid injection amount, and can be easily performed even in a high-speed automated assembly line. With this method, even a very small amount of liquid can be surely detected, and since the inspection is performed before the sealing step, the process of replenishing the electrolyte with the insufficient liquid amount with the electrolytic solution is simple.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a spiral type battery which is an object of the present invention.

FIG. 2 is a schematic view showing an example of an embodiment of the inspection method of the present invention.

FIG. 3 is a graph showing a specific example of the correlation between the amount of electrolytic solution and impedance in the inspection method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electrode set component 1a Center hole 2 Positive electrode 3 Separator 4 Negative electrode 5 Insulating disk 5a Cylindrical part 6 Lead tab 6a Tip part 7 Lead tab 8 Lid set component 9 Terminal plate 10 Sealing gasket 11 Battery case 12 Measuring electrode 13 Measuring electrode 14 Impedance measuring part 15 Comparison section

Claims (3)

[Claims] 1. An electrode set component comprising a thin sheet-shaped positive electrode, a separator, and a negative electrode, which are spirally wound into a cylindrical shape, and a lead tab is connected to each of the positive electrode and the negative electrode. In a spiral type battery assembly line in which a metal battery case is loaded and one of the lead tabs is connected to the battery case, and then a predetermined amount of the electrolytic solution is injected into the battery case, the electrolytic solution is added to the battery case. After a lapse of a predetermined time after injecting, the impedance between the separator and the positive electrode lead tab or the negative electrode lead tab is measured by applying the measurement electrode to a predetermined portion of the separator that has absorbed the electrolytic solution, and the impedance is measured by an AC method. Then, the measured value is compared with a reference value to judge the good or defective of the intermediate product, and the spiral type battery is assembled. Inspection method in line. 2. The method for inspecting in a spiral battery assembly line according to claim 1, wherein the impedance between the measurement electrode and the battery case to which the lead tab is connected is measured. 3. The measurement electrode is inserted into a center hole of the electrode set component loaded in the battery case to a predetermined depth, and the measurement electrode is applied to the separator arranged on the innermost periphery of the center hole. The method for inspecting a spiral battery assembly line according to claim 1, wherein the impedance measurement is performed.