JPH07147165A - Method for detecting abnormality of lithium battery - Google Patents

Abstract

PURPOSE:To improve abnormality detecting precision by cooling a standard battery and a battery to be detected, measuring the battery voltages, and comparing them to each other to detect an abnormality. CONSTITUTION:Fifty pieces of normal lithium batteries are cooled to -20 deg.C with a low temperature thermostatic oven or by constant cooling air blowing, an open circuit voltage VO and a close circuit voltage VC by connecting a resistor RL of 20A are measured. The dispersion range of these voltages is set as standard open circuit and close circuit voltage ranges. A lithium battery to be detected is similarly measured for voltage under the same condition, and this is compared with the respective standard voltage ranges. When the voltages VO, VC of the battery to be detected are consequently out of the standard voltage ranges, the battery to be detected is judged abnormal. Thus, even a slight internal short circuit of about an internal short circuit resistance of 50kOMEGA can be detected, and reliability on quality in which the performance is never deteriorated over a long period can be improved. Also, the productivity is never lost since the detection can be performed without extension of aging period.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting an abnormality in a lithium battery.

[0002]

2. Description of the Related Art In a lithium battery, an alkali metal such as lithium and a lithium aluminum alloy is used as a negative electrode active material, and an organic electrolyte in which an alkali metal salt is dissolved in a non-aqueous organic solvent is used as an electrolytic solution. As this lithium battery, for example, a spiral lithium battery as shown in FIG. 5 is known. This battery is mainly composed of a cylindrical battery case 10 having an open top, a power generating element 20 housed in the battery case 10, a positive electrode terminal plate 30 also serving as a lid of the battery case 10, and a sealing gasket 40. The positive electrode lead plate 100 is connected to the positive electrode terminal plate 30 by welding or the like and is also connected to the positive electrode 60, and the negative electrode lead plate 110 is connected to the battery case 10 by welding or the like and is also connected to the negative electrode 70. Then, the organic electrolytic solution 90 is injected into the battery case 10, and the battery case 10 is sealed by the positive electrode terminal plate 30 and the gasket 40.

By the way, in the lithium battery as described above, in order to detect an internal short circuit, a defective internal connection and other abnormalities, during the aging for a predetermined period (about one week) performed after the lithium battery is assembled or after the aging is completed. The open circuit voltage and the closed circuit voltage are measured, and a lithium battery whose voltage is out of a predetermined voltage range is determined to be a battery in which an abnormality has occurred. For example, 50
The voltage of each normal lithium battery is measured, and the variation range of the measured voltage is set as the reference voltage range. Next, the battery voltage of the lithium battery for detection is measured, and if the measured battery voltage is outside the reference voltage range, it is determined that the lithium battery for detection is an abnormal battery, and the reference voltage range If it is within the range, it is determined to be a normal battery.

The reference voltage range and the voltage of the lithium battery to be detected are measured at room temperature.

[0005]

However, in the above-described method for detecting an abnormality of a lithium battery at room temperature, an abnormality of a high resistance internal short circuit of about 50 kΩ can be detected only for an aging period of about one week. There was a problem that I could not.

That is, a lithium battery in which an internal short circuit having a low resistance of up to about 30 kΩ has occurred has a lower open circuit voltage and a considerably lower closed circuit voltage than a normal lithium battery. it can.

However, as described above, 50 kΩ
A lithium battery with a high resistance internal short circuit cannot be reliably detected because the open-circuit voltage and closed-circuit voltage do not decrease significantly compared to a normal lithium battery within a aging period of about one week. Of.

Therefore, the aging period should be at least 20.
If it is extended to one day, the open circuit voltage and the closed circuit voltage significantly decrease, so that the above abnormality can be detected.

However, if the aging period is set to 20 days, the number of production days and the production cost are increased and the storage space of the battery is also increased as compared with the case where the aging period which is usually performed is about 7 days, so that the productivity is increased. Cannot be adopted because it will significantly decrease.

Further, as shown in FIG. 5 mentioned above, for example,
Although the welding of the positive electrode lead plate 100 and the negative electrode lead plate 110 to the connection part (battery case 10 and positive electrode terminal plate 30) is insufficient, the contact resistance of the welded part is kept at a low level which is almost equal to that of a normal product at room temperature. As for a lithium battery with a poor internal connection, the open circuit voltage and closed circuit voltage do not drop significantly as compared to a normal lithium battery because the connection resistance of the welded part at room temperature is almost the same as that of a normal product. However, there was a problem that it could not be detected reliably.

The present invention has been made in view of the above-mentioned problems, and an object thereof is to provide a lithium battery abnormality detection method capable of improving the accuracy of lithium battery abnormality detection.

[0012]

In order to achieve the above object, the present invention measures the variation range of each battery voltage of a plurality of normal lithium batteries as a reference voltage range and determines the battery voltage of a lithium battery to be detected. A method for detecting an abnormality of a lithium battery for measuring, wherein the measured battery voltage is outside the reference voltage range, the abnormality detection method of the lithium battery, wherein the reference voltage range and the lithium for detection are The battery voltage of the battery is measured by cooling the normal lithium battery and the lithium battery for detection.

Here, it is preferable that the cooling is performed in a temperature range of -40 ° C. or higher and lower than 5 ° C.

[0014]

The reference voltage range and the battery voltage of the lithium battery to be detected are measured by cooling the normal lithium battery and the lithium battery to be detected. The voltage of a lithium battery in which an abnormality such as a short circuit or a defective internal connection has occurred is significantly lower than the voltage of a normal battery. Therefore, since the lithium battery having a low measured battery voltage can be regarded as having the abnormality, the lithium battery having the abnormality can be detected based on the measured battery voltage.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

Since the basic structure of the lithium battery according to the present invention is common to that of the conventional lithium battery shown in FIG. 5, the common parts are denoted by the same reference numerals and detailed description thereof will be omitted.

In the present embodiment, the abnormality detection of the lithium battery is performed by the following method.

First, 50 lithium batteries determined to be normal in advance are placed in a low temperature constant temperature bath or cooled to -20 ° C. by blowing cooling air to them. Next, the open circuit voltage and the closed circuit voltage of each cooled lithium battery are measured. Then, the variation range of the measured open circuit voltage and closed circuit voltage of the normal lithium battery is set as the reference open circuit voltage range and the reference closed circuit voltage range, respectively. Next, the lithium battery for detection is placed in a constant temperature bath similar to the above, and the open circuit voltage and the closed circuit voltage of the lithium battery for detection measured in the same manner as above are compared with the reference open circuit voltage range and the reference closed circuit voltage range, respectively. , It is determined that the lithium battery for detection outside the voltage range of at least one of the reference open circuit voltage range and the reference closed circuit voltage range has an abnormality.

Here, in order to show the effect of this embodiment, an experiment conducted based on the above-mentioned abnormality detecting method will be shown below.

Table 1 shows each sample of a lithium battery for detection and a normal lithium battery which can be regarded as artificially generating an abnormality. 1 to
Reference numeral 3 is a lithium battery for detection, which is obtained by connecting external resistors of 50 kΩ, 30 kΩ, and 10 kΩ to a normal lithium battery to make an external short circuit, and then 5 days have passed. A normal lithium battery to which this external resistance is connected can be regarded as an internal short circuit having an internal resistance corresponding to the external resistance value. In addition, sample NO. Four
5 is a lithium battery for detection, which is, as shown in FIG. 5 described above, a battery in which the negative electrode lead plate 110 is only brought into contact with the battery case 10 without welding to an originally normal lithium battery. . By contacting and connecting the negative electrode lead plate 110 to the battery case 10, an internal connection failure state was created in the lithium battery. Furthermore, sample NO. 5 is a normal lithium battery with no abnormality.
Here, the lithium battery used as a sample is the CR of the spiral type manganese dioxide lithium battery shown in FIG.
14 ・ H type, the number of each sample is 5
It is 0.

[0021]

[Table 1] FIG. 1 shows the open circuit voltage V measured for each of the above sample batteries.
It is the graph which shows the variation characteristic of o, (a) is the graph which measured the sample battery of the former normal temperature state,
(B) is the graph which measured the sample battery cooled to -20 degreeC of a present Example. In the conventional abnormality detection method of FIG. 1 (50 kΩ short circuit), sample NO. 2 (30 kΩ short circuit) and NO. Sample No. 4 is the open circuit voltage variation range of 4 (negative connection of the negative electrode lead plate 110).
O. Sample No. 5 because it wraps with that of 5 (normal). With reference to the open circuit voltage variation range of 5 (normal) as the reference open circuit voltage range, the sample NO. Abnormality detection of 1, 2, and 4 cannot be reliably performed. On the other hand, FIG. 1 (b)
In the abnormality detection method of this embodiment, the sample No. 1-4
The open circuit voltage variation range of the sample NO. Since it does not wrap with that of 5 (normal), sample NO. 1-5
It is possible to reliably detect abnormalities. The cooling at -20 ° C was performed for 1 day, and the open circuit voltage Vo was measured. Figure 3
Sample No. 1 to 3 show open circuit voltage measuring circuits.

FIG. 2 is a graph showing the variation characteristics of the closed-circuit voltage measured for each of the sample batteries, (a) is a graph of the conventional sample battery at room temperature, and (b) is the graph. It is a graph which measured the sample battery cooled to -20 degreeC of the Example. In the conventional abnormality detection method of FIG. 1 (50 kΩ short circuit) and NO. No. 4 (connection failure of the negative electrode lead plate 110) has a closed circuit voltage variation range of sample NO. Sample No. 5 because it wraps with that of 5 (normal). With reference to the closed circuit voltage variation range of 5 (normal) as the reference closed circuit voltage range, the sample NO. It is not possible to reliably detect the abnormalities 1 and 4. On the other hand, in the abnormality detection method of this embodiment shown in FIG. The closed-circuit voltage variation range of 1 to 4 is sample NO. Since it does not wrap with that of 5 (normal), sample NO. It is possible to reliably detect the abnormalities 1 to 5. It should be noted that the cooling at -20 ° C. was performed for 1 day, and the external load resistance 20Ω was connected and conducted for 0.4 seconds to conduct the closed circuit voltage V.
The measurement of c was performed. FIG. 4 shows sample NO. 1 to 3 show circuits for measuring a closed circuit voltage.

Table 2 shows the number of abnormality-occurring batteries detected based on the measurement of the open circuit voltage Vo of FIG. 1 and the closed circuit voltage Vc of FIG. 2. In the conventional abnormality detecting method, the sample No. 18 for 1 (50kΩ short circuit), N
O. With respect to 4 (poor connection of negative electrode lead plate 110), only 8 could be detected. On the other hand, in the abnormality detection method of this embodiment, the sample No. All 1 to 4 abnormalities could be detected.

[0024]

[Table 2] From the above results, the abnormality detection method of the present invention can detect a slight internal short-circuit having an internal short-circuit resistance of about 50 kΩ. Can be shipped. Further, since the above detection can be performed without extending the aging period, productivity is not impaired. Furthermore, since a defective internal connection can be detected, only lithium batteries having high discharge performance can be shipped.

In this embodiment, the cooling temperature is set to -20.
Although it is set to be ° C, a temperature range of -40 ° C or higher and lower than 5 ° C is preferable. This is because when the temperature is lower than −40 ° C., the organic electrolytic solution 90 causes a decrease in its conductivity and an increase in viscosity and the performance as a battery is impaired, and when the temperature is higher than 5 ° C., the temperature becomes room temperature. This is because the anomaly detection capability is impaired because of the proximity.

[0026]

As described in detail above, according to the present invention, the reference voltage range and the battery voltage of the lithium battery for detection are measured by cooling the reference lithium battery and the lithium battery for detection. As a result, the voltage of the lithium battery in which not only the low resistance but also the high resistance internal short circuit, defective internal connection, and low contact resistance abnormality occurs remarkably lower than the voltage of the normal battery. Therefore, since the lithium battery having a low measured battery voltage can be regarded as having the abnormality, the lithium battery having the abnormality can be detected based on the measured battery voltage. Therefore, the abnormality detection accuracy of the lithium battery can be improved, and thus, the life of the lithium battery can be extended and the quality such as discharge stability and the reliability can be improved.

[Brief description of drawings]

FIG. 1 is a graph showing a graph showing variations in open circuit voltage according to the related art and the present invention, in which (a) is a conventional graph and (b) is a graph according to the present invention.

2A and 2B are graphs showing graphs showing variations in closed-circuit voltage according to the related art and the present invention, in which FIG. 2A is a conventional graph and FIG. 2B is a graph according to the present invention.

FIG. 3 is an open circuit voltage measuring circuit according to the present invention.

FIG. 4 is an open circuit voltage measuring circuit according to the present invention.

FIG. 5 is a vertical cross-sectional view of a conventional spiral type lithium battery according to the present invention.

[Explanation of symbols]

 10 Battery Case 20 Power Generation Element 30 Positive Electrode Terminal Plate 40 Sealing Gasket 50 Separator 60 Positive Electrode 70 Negative Electrode 80 Insulation Plate 90 Organic Electrolyte 100 Positive Electrode Lead Plate 110 Negative Lead Plate

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuhiro Ishiguro 5-36-1 Shimbashi, Minato-ku, Tokyo Fuji Electric Chemical Co., Ltd. (72) Masaaki Suzuki 5-36-11 Shinbashi, Minato-ku, Tokyo Fuji Electrochemical Co., Ltd.

Claims (2)

[Claims] 1. A battery voltage of a lithium battery to be detected is measured while measuring a variation range of each battery voltage of a plurality of normal lithium batteries as a reference voltage range, and the measured battery voltage is outside the reference voltage range. Is a method of detecting an abnormality of the lithium battery to be detected, the measurement of the battery voltage of the reference voltage range and the lithium battery to be detected, the normal lithium battery and the A method of detecting an abnormality in a lithium battery, which is performed by cooling a lithium battery to be detected. 2. The method for detecting an abnormality in a lithium battery according to claim 1, wherein the cooling is performed in a temperature range of −40 ° C. or higher and lower than 5 ° C.