JPH09161817A - Method of inspecting quality of lithium primary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely eliminate, as defective, an abnormal product which does not reveal an abnormality until a certain period later after the assembling. SOLUTION: A battery is assembled, and thereafter, 1-5% of the electric capacity of this battery is temporarily discharged. This battery is then aged, and at a point of time when a prescribed inspection period (for example, within three weeks) passed from the temporary discharge, whether the open circuit voltage of the battery is within a prescribed standard voltage range or not is judged, and whether the close circuit voltage of the battery is a prescribed standard voltage or more is also judged. Thus, an abnormal product by moisture inclusion can be judged by the close circuit voltage inspection, and abnormal products other than it can be judged by the open circuit voltage inspection.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a quality inspection method for a lithium primary battery, which is suitable for application in the manufacturing process of a lithium primary battery.

[0002]

2. Description of the Related Art Conventionally, when inspecting the quality of a lithium primary battery, after assembling the battery, the temperature is set to room temperature or high temperature (60
A method of carrying out aging at about (° C.) For 2 to 4 weeks, measuring the voltage or internal resistance of the battery, and comparing the measured value with a reference value to judge acceptability is widely adopted.

[0003]

However, this allows removal of defective products having internal short-circuit or external short-circuit immediately after assembly of the battery or defective products with poor sealing condition, but after a certain period of time has passed since the battery was assembled. Abnormal products that show abnormalities for the first time (for example, water and trace amounts of impurities such as iron, copper, zinc powder, etc. are mixed in, causing a chemical change inside the battery, and the negative electrode surface is oxidized when a certain period of time has passed after the battery was assembled. Or an abnormality such as an internal short circuit) cannot always be excluded as a defective product.

Therefore, there is a possibility that defective products that cannot sufficiently satisfy the required performance level may be mixed in the batteries to be shipped, and batteries to be shipped in a multi-rectangular form (such as large spiral lithium primary batteries) ), There is a problem that a battery which is in an over-discharged state during use due to mixing of defective products operates a safety valve, which may lead to damage of the device due to ejection of an electrolytic solution.

In view of the above circumstances, it is an object of the present invention to provide a quality inspection method for a lithium primary battery, which is capable of surely removing an abnormal product that does not appear abnormal after a certain period of time has passed since the battery was assembled. And

[0006]

That is, the quality inspection method for a lithium primary battery according to the present invention is to assemble a battery, then temporarily discharge 1 to 5% of the electric capacity of the battery, and then age the battery. When a predetermined inspection period (for example, within 3 weeks) has passed from the temporary discharge, it is determined whether the open circuit voltage of the battery is within a predetermined reference open circuit voltage range, and the closed circuit voltage of the battery is determined. Is configured to determine whether is equal to or higher than a predetermined reference closed circuit voltage.

Regarding the order of measuring the voltage, it is desirable to measure the closed circuit voltage after measuring the open circuit voltage in order to avoid the influence of the fluctuation of the closed circuit voltage.

Here, the temporary discharge amount is 1 to 5% of the electric capacity.
The reason is limited to the following reasons. That is, when the temporary discharge amount is less than 1% of the electric capacity, the difference between the good product and the defective product does not clearly appear in the voltage recovery after the temporary discharge, and conversely, the temporary discharge amount is 5% of the electric capacity. If it exceeds, the capacity loss becomes large and the discharge performance deteriorates. Furthermore, if the temporary discharge amount exceeds 8% of the electric capacity, in addition to the performance deterioration due to the capacity loss, the voltage after temporary discharge is good or bad. This is because it is stable and the difference between a good product and a defective product is unclear.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. The quality inspection method for a lithium primary battery according to the present invention is performed in the following procedure.

First, a battery is assembled, and then 1 to 5% of the electric capacity of the battery is temporarily discharged. Then, the reaction actually occurs inside the battery.

Next, this battery is aged.
At this time, since there is a difference in how the battery voltage recovers depending on the presence or absence of an abnormality inside the battery, the following two types of inspection (open circuit voltage inspection and closed circuit voltage inspection) are performed when the predetermined inspection period elapses from the temporary discharge. To do.

First, in order to exclude defective products other than defective products due to water contamination as defective products, the open circuit voltage of this battery is within a predetermined reference open circuit voltage range (for example, 3.22 to 3.35).
V) is determined. That is, the open circuit voltage of a normal product falls within this reference open circuit voltage range, whereas the open circuit voltage of abnormal products other than the abnormal product due to water contamination falls outside the reference open circuit voltage range. Can be eliminated.

Next, in order to exclude an abnormal product due to water contamination as a defective product, it is determined whether or not the closed circuit voltage of this battery is equal to or higher than a predetermined reference closed circuit voltage (for example, 3.14V). That is, a normal product maintains a closed circuit voltage equal to or higher than the reference closed circuit voltage, whereas an abnormal product due to water contamination has a closed circuit voltage lower than the reference closed circuit voltage. it can.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a graph showing a voltage transition when the temporary discharge amount is 0.5% of the electric capacity, and FIG. 2 is a graph showing a voltage transition when the temporary discharge amount is 1.5% of the electric capacity.
Is a graph showing the voltage transition when the temporary discharge amount is 3% of the electric capacity, FIG. 4 is a graph showing the voltage transition when the temporary discharge amount is 8% of the electric capacity, and FIG. 5 is the temporary discharge amount and the discharge. FIG. 6 is a graph showing the relationship with the performance, and FIG. 6 is a graph showing the transition of the closed circuit voltage of the abnormal water-mixed product and the normal product when the temporary discharge amount is set to 1.5% of the electric capacity.

<Example 1> CR14H (diameter 25.5 m
After assembling a lithium manganese dioxide battery (m, height 50 mm), 1.5% of the electric capacity was temporarily discharged, and the open circuit voltage and closed circuit voltage (40 Ω, 40 Ω of each battery) were maintained for 3 weeks.
After 0.2 seconds) was measured. The measurement was performed the day after discharge (first time), one week after discharge (second time), two weeks after discharge (third time), and three weeks after discharge (fourth time). It was decided that the voltage would recover by -10 mV or more from the previous measurement. The results are shown in FIGS. 2 and 6, respectively.

As is clear from FIG. 2, impurities such as copper powder, iron powder, and zinc powder are mixed in the positive electrode side with respect to the graph (solid line) showing the average voltage transition of non-defective products, which causes an internal short circuit. A clear difference was observed in the degree of voltage recovery between the reached defective product (B) and the defective product (C, D) having holes in the separator.

Further, as is apparent from FIG. 6, the defective product (A) in which the sealing was insufficient and water was mixed in from the outside had a low closed circuit voltage, and a clear difference from the non-defective product was recognized.

<Embodiment 2> The amount of temporary discharge is 3% of the electric capacity.
A voltage test was performed in the same manner as in Example 1 except for the above. The result is shown in FIG.

As is clear from FIG. 3, impurities such as copper powder, iron powder, and zinc powder are mixed in the positive electrode side with respect to the graph (solid line) showing the average voltage transition of non-defective products, which causes an internal short circuit. A clear difference was observed in the degree of voltage recovery between the reached defective product (B) and the defective product (C, D) having holes in the separator.

Regarding the closed circuit voltage, as in the first embodiment,
A clear difference was observed between the defective product (A) in which the sealing was insufficient and water was mixed in from the outside and the non-defective product.

<Comparative Example 1> A temporary discharge amount of 0.
A voltage test was performed in the same manner as in Example 1 except that the content was 5%. The result is shown in FIG.

As is apparent from FIG. 1, in contrast to the graph (solid line) showing the average voltage transition of non-defective products, the defective products (C, D) with holes in the separator show a difference in the degree of voltage recovery. However, there was almost no difference in voltage recovery between the defective product (A) in which water was mixed from the outside due to insufficient sealing and the defective product (B) in which copper powder was mixed as an impurity on the positive electrode side.

<Comparative Example 2> The amount of temporary discharge is 8% of the electric capacity.
A voltage test was performed in the same manner as in Example 1 except for the above. FIG. 4 shows the results.

As is clear from FIG. 4, in contrast to the graph (solid line) showing the average voltage transition of non-defective products, defective products (A) in which water was mixed from the outside due to insufficient sealing and copper powder on the positive electrode side No clear difference was found in the degree of voltage recovery between the defective product (B) in which impurities such as the above were mixed and the defective product (C, D) in which the separator had holes. On the other hand, regarding the closed circuit voltage, a defective product (B) in which impurities such as copper powder were mixed into the positive electrode side
However, since it took a considerable time after the temporary discharge until a clear difference from the voltage of the non-defective product was recognized, it was impossible to make a strict determination.

Further, in order to see the influence of the temporary discharge amount on the discharge performance, the discharge performance is obtained when the temporary discharge amount is 5% and 10% of the electric capacity, and 100 is obtained when the temporary discharge is not performed.
Expressed as an index. The result is shown in FIG. FIG.
As is clear from the above, when the amount of temporary discharge exceeds 5% of the electric capacity, the discharge performance is significantly deteriorated and the practicality becomes poor.

[0026]

As described above, according to the present invention, a battery is assembled and then 1 to 5% of the electric capacity of the battery is assembled.
Is temporarily discharged, then the battery is aged, and when the predetermined inspection period (for example, within 3 weeks) has passed from the temporary discharge, is the open circuit voltage of the battery within the predetermined reference open circuit voltage range? Since it is configured to determine whether or not the closed circuit voltage of the battery is equal to or higher than a predetermined reference closed circuit voltage, a reaction actually occurs inside the battery due to temporary discharge, and an internal abnormality occurs. Since it causes a difference in the degree of voltage recovery, it is possible to determine pass / fail by the closed-circuit voltage inspection for abnormal products due to water contamination, and it is possible to determine pass / fail by the open-circuit voltage inspection for other abnormal products. It is possible to reliably exclude defective products that appear abnormal only after a certain period of time has passed since the assembly. As a result, even when the battery is shipped in a multi-rectangular form, there is no risk of equipment damage due to the operation of the safety valve due to the over discharge of the battery during use and the accompanying electrolyte discharge due to the mixing of defective products, A battery with high reliability can be supplied.

[Brief description of the drawings]

FIG. 1 is a graph showing a voltage transition when a temporary discharge amount is 0.5% of an electric capacity.

FIG. 2 is a graph showing a voltage transition when the amount of temporary discharge is 1.5% of the electric capacity.

FIG. 3 is a graph showing a voltage transition when the amount of temporary discharge is 3% of the electric capacity.

FIG. 4 is a graph showing a voltage transition when a temporary discharge amount is 8% of an electric capacity.

FIG. 5 is a graph showing a relationship between a temporary discharge amount and discharge performance.

FIG. 6 is a graph showing changes in closed circuit voltage of a water-mixed abnormal product and a normal product when the amount of temporary discharge is set to 1.5% of the electric capacity.

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

Claims (2)

[Claims] 1. A battery is assembled, and then 1 to 5% of the electric capacity of the battery is temporarily discharged. Then, the battery is aged. When a predetermined inspection period has elapsed from the temporary discharge, the battery is discharged. Of the lithium primary battery configured so as to determine whether or not the open circuit voltage of the battery is within a predetermined reference open circuit voltage range, and whether or not the closed circuit voltage of the battery is equal to or higher than a predetermined reference closed circuit voltage. Quality inspection method. 2. The quality inspection method for a lithium primary battery according to claim 1, wherein the inspection period is within 3 weeks.