JP2014154441A - Method for inspecting nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for inspecting nonaqueous electrolyte secondary batteries, in which the time required for inspecting presence/absence of a fine short-circuit can be shortened by further achieving optimization of classification conditions of lots to be inspected.SOLUTION: A method for inspecting nonaqueous electrolyte secondary batteries includes a step of measuring characteristic values (battery voltages V1, V2 and cell temperatures T1, T2) of nonaqueous electrolyte secondary batteries, before and after a normal temperature aging step (STEP-3). The nonaqueous electrolyte secondary batteries are grouped on the basis of the measured characteristic values (on the basis of a self discharge amount ΔV calculated from the battery voltages V1, V2 and the cell temperatures T1, T2) to form lots to be inspected, and presence/absence of an internal short-circuit in each nonaqueous electrolyte secondary battery is inspected for each lot to be inspected on the basis of the self discharge amount ΔV.

Description

  The present invention relates to a technique for an inspection method for a nonaqueous electrolyte secondary battery, and more particularly to a technique for accurately inspecting a defect such as a micro short circuit inside the battery.

  Conventionally, various techniques for inspecting the presence or absence of a micro short-circuit in a non-aqueous electrolyte secondary battery have been studied. For example, the technique is disclosed in Patent Document 1 shown below and is publicly known.

  In the prior art disclosed in Patent Document 1, a plurality of non-aqueous electrolyte secondary batteries to be inspected together have the same production lot to form an inspection target lot, and the self-discharge amount (voltage) for each inspection target lot. Inspection accuracy is improved by inspecting variation in the amount of descent).

JP 2011-18482 A

  However, as in the prior art disclosed in Patent Document 1, it is considered that non-aqueous electrolyte secondary batteries having common battery characteristics cannot be bundled simply by grouping inspection target lots in production lots. In order to improve the accuracy, a lot of self-discharge time is still required, and there is still room for further shortening of the time required for the inspection for the presence of internal short circuit.

  The present invention has been made in view of such a current problem, and further optimizes the stratification conditions of the lot to be inspected to improve the inspection accuracy and reduce the time required for inspection for the presence of internal short circuits. It aims at providing the inspection method of the nonaqueous electrolyte secondary battery which enables shortening.

  The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

  That is, in claim 1, before and after the aging step of leaving the nonaqueous electrolyte secondary battery at a predetermined temperature for a predetermined time, the battery voltage of the nonaqueous electrolyte secondary battery is measured, and the aging step in the aging step is performed. A non-aqueous electrolyte secondary battery inspection method for calculating a self-discharge amount of a non-aqueous electrolyte secondary battery and inspecting the presence or absence of an internal short circuit in the non-aqueous electrolyte secondary battery based on the self-discharge amount, Before and after the aging process, comprising a step of measuring the characteristic value of the non-aqueous electrolyte secondary battery, grouping the non-aqueous electrolyte secondary battery based on the measured characteristic value to generate a lot to be inspected, and the inspection For each target lot, the presence or absence of an internal short circuit in the nonaqueous electrolyte secondary battery is inspected based on the self-discharge amount.

  In the present invention, the characteristic value is a cell temperature of the non-aqueous electrolyte secondary battery.

  In the present invention, the characteristic value is a battery voltage of the non-aqueous electrolyte secondary battery.

  As effects of the present invention, the following effects can be obtained.

  According to the first to third aspects, it is possible to suppress the variation of the self-discharge amount as a comparison factor for determining the presence or absence of the internal short circuit as compared with the conventional case, and the internal short circuit while improving the inspection accuracy. It is possible to reduce the time required to determine whether or not there is any.

The figure which shows the nonaqueous electrolyte secondary battery which is the application object of the test | inspection method which concerns on this invention, (a) The perspective schematic diagram which shows the cell which comprises a nonaqueous electrolyte secondary battery, (b) The perspective view of a nonaqueous electrolyte secondary battery Pattern diagram. The flowchart which shows the outline of the flow of the manufacturing process of a nonaqueous electrolyte secondary battery. The flowchart which shows the flow of the test | inspection method of the nonaqueous electrolyte secondary battery which concerns on 1st embodiment of this invention. Explanatory drawing of the time required for the judgment of the presence or absence of the internal short circuit in the test | inspection method of the nonaqueous electrolyte secondary battery which concerns on 1st embodiment of this invention. The flowchart which shows the flow of the test | inspection method of the nonaqueous electrolyte secondary battery which concerns on 2nd embodiment of this invention. Explanatory drawing of the test | inspection method of the nonaqueous electrolyte secondary battery which concerns on 2nd embodiment of this invention, (a) Explanatory drawing of conditions according to a layer, (b) Explanatory drawing of the time required for judgment of the presence or absence of an internal short circuit. The flowchart which shows the flow of the test | inspection method of the conventional nonaqueous electrolyte secondary battery. Explanatory drawing of the time required for judgment of the presence or absence of the internal short circuit in the test | inspection method of the conventional nonaqueous electrolyte secondary battery.

Next, embodiments of the invention will be described.
First, an overall configuration of a nonaqueous electrolyte secondary battery, which is an application mode of an inspection method according to an embodiment of the present invention, will be described with reference to FIG.
In the following description, the nonaqueous electrolyte secondary battery is simply referred to as a secondary battery.

  As shown in FIG. 1, a cell 1 constituting a secondary battery 10 to which an inspection method according to the present invention is applied includes a bottomed rectangular tube-shaped case body 21 having one surface (upper surface) opened, and a flat plate shape. In addition, the battery case 2 including the lid body 22 that closes the opening of the case main body 21 is configured to accommodate the electrode body 3 together with the electrolytic solution.

The battery case 2 is configured as a rectangular case in which an opening of a case body 21 formed in a rectangular parallelepiped bottomed rectangular tube shape with one surface (upper surface) opened is closed with a flat lid body 22. .
A positive electrode terminal 4a is provided at one end in the longitudinal direction of the lid 22 (left end in FIG. 1), and a negative electrode terminal 4b is provided at the other longitudinal end of the lid 22 (right end in FIG. 1). .

  The electrode body 3 is formed by laminating a positive electrode 31, a negative electrode 32, and a separator 33 such that the separator 33 is interposed between the positive electrode 31 and the negative electrode 32, and winding the laminated positive electrode 31, negative electrode 32, and separator 33. It is configured by flattening.

When the cell body 1 is configured by accommodating the electrode body 3 and the electrolyte in the battery case 2, first, the positive electrode terminal 4 a and the negative electrode terminal 4 b of the lid body 22 are respectively connected to the positive electrode 31 and the negative electrode 32 of the electrode body 3. Then, the electrode body 3 is assembled to the lid body 22 to form a lid body sub-assembly.
Thereafter, the electrode body 3 and the electrolytic solution are accommodated in the case body 21, the lid body 22 is fitted into the opening of the case body 21, and the lid body 22 and the case body 21 are sealed by welding (ie, The cell 1 is configured by sealing).

  And the secondary battery 10 which is the application aspect of the test | inspection method which concerns on one Embodiment of this invention laminates | stacks several cell 1 * ... in a thickness direction, and each cell by a bus bar (not shown). 1 ···· are electrically connected in series.

Next, a schematic procedure from the initial charge to the shipment of the secondary battery will be described with reference to FIGS.
In contrast to the secondary battery 10 (see FIGS. 1A and 1B) in which the electrolyte is injected into the battery case 2 containing the electrode body 3 and sealed, the cells 1. As shown in FIG. 1, first, charging (conditioning) is performed (STEP-1).
Next, the voltage V1 of the secondary battery 10 at the time after the initial charging is performed is measured (STEP-2).
Note that the secondary battery 10 after the initial charge may be left in a predetermined high temperature atmosphere for a certain period (so-called high temperature aging) before measuring the voltage V1.

Next, room temperature aging is performed by leaving the secondary battery 10 at room temperature for a certain period (STEP-3).
Here, “normal temperature” is a temperature of about 25 ° C.

Next, the voltage V2 of the secondary battery 10 at the time when normal temperature aging is completed is measured (STEP-4).
The secondary battery 10 is shipped after confirmation of the presence or absence of internal short circuit (STEP-5), confirmation of electric capacity (STEP-6), confirmation of internal resistance value (STEP-7), and the like.

In the inspection method for the secondary battery 10 according to the embodiment of the present invention, the non-defective product / defective product determination in the confirmation of the presence or absence of the internal short circuit (STEP-5) is the voltage difference between the voltage V1 and the voltage V2 (= V1− The determination is made based on the self-discharge amount ΔV which is V2).
The inspection method according to an embodiment of the present invention is characterized by stratification conditions used for forming an inspection lot for making a determination based on the self-discharge amount ΔV.

  Next, a method for inspecting a secondary battery according to an embodiment of the present invention will be described with reference to FIGS.

First, the secondary battery inspection method according to the first embodiment of the present invention will be described.
As shown in FIG. 7, in the conventional secondary battery inspection method, the secondary battery production lot is adopted as the stratification condition for generating the inspection target lot in the determination of the presence or absence of micro short-circuit (STEP-5). It is configured (STEP-5-31).
And it is set as the structure which determines the presence or absence of a micro short circuit for every inspection object lot which produced | generated the production lot as the stratification condition (STEP-5-32).

  On the other hand, as shown in FIG. 3, in the secondary battery inspection method according to the first embodiment of the present invention, a layer for generating a lot to be inspected for determining whether or not there is a micro short circuit (STEP-5). As another condition, the self-discharge amount ΔV of the secondary battery is adopted (STEP-5-11).

  Note that the secondary battery is composed of a plurality of cells, and when the secondary battery includes a plurality of restraining jigs, the self-discharge amount ΔV is calculated in units of the restraining jigs.

  And it is set as the structure which determines the presence or absence of a micro short circuit for every inspection object lot produced | generated as the stratification conditions by the self-discharge amount (DELTA) V of a secondary battery (STEP-5-12).

  Moreover, in the inspection method of the secondary battery which concerns on 1st embodiment of this invention, it is set as the structure which maintains the cell temperature of a secondary battery in the range of standard temperature +/- 3 degreeC in normal temperature aging (STEP-3). .

Here, an example of generating a lot to be inspected using the self-discharge amount ΔV of the secondary battery as the stratification condition will be described.
First, the average value of the self-discharge amount ΔV of each secondary battery to be inspected and the standard deviation σ in the normal distribution of the self-discharge amount ΔV are calculated.
And it is set as the structure which calculates inspection object lot with each secondary battery which has settled in the range of +/- 3 (sigma) with respect to the average value of self-discharge amount (DELTA) V of each secondary battery.
In the present embodiment, the configuration in which the inspection target lot is generated by wrapping the average value of the self-discharge amount ΔV of the plurality of secondary batteries within the range of ± 3σ in the normal distribution is illustrated. A configuration may be adopted in which a lot to be inspected is generated by enclosing the self-discharge amount ΔV of the plurality of secondary batteries from the median within a predetermined range.

  Then, the inspection target lot of the secondary battery is generated by enclosing the average value of the self discharge amount ΔV within the range of ± 3σ in the normal distribution, and the self discharge amount ΔV for each inspection target lot. Are compared to determine the presence or absence of a micro short circuit.

Here, with reference to FIG. 4 and FIG. 8, a description will be given of the determination status of the presence or absence of a short-circuit when the inspection target lot is generated based on the self-discharge amount ΔV of the secondary battery.
As shown in FIG. 8, a self-discharge result (a group indicated by an arrow Y1 in FIG. 8) when a non-defective secondary battery is self-discharged, and a defective secondary battery with an internal short circuit is self-discharged Comparing the self-discharge results (indicated by arrow X1 in FIG. 8), it can be seen that the secondary battery having an internal short circuit tends to have a larger self-discharge amount ΔV.

  Since the measurement results of the self-discharge amount ΔV vary, the non-defective product self-discharge amount ΔV (shown by the arrow X2 in FIG. 8) and the non-defective product self-discharge amount ΔV (shown by the arrow Y2 in FIG. 8). In order to ascertain the amount of deviation, the self-discharge days are required to be about 17 days when the inspection target lot is generated from the manufacturing lot of the secondary battery.

On the other hand, as shown in FIG. 4, when the inspection target lot is generated based on the self-discharge amount ΔV of the secondary battery, the measurement results of the self-discharge amount ΔV (indicated by arrows X1 and Y1 in FIG. 4) vary. Can be suppressed.
For example, when a lot to be inspected for a secondary battery is generated by enclosing the average value of the self-discharge amount ΔV within the range of ± 3σ in the normal distribution, the variation in the self-discharge amount ΔV in the non-defective product is generated. The number of days of self-discharge required to determine the amount of deviation between what is indicated by arrow X2 in FIG. 4 and the variation in self-discharge amount ΔV (indicated by arrow Y2 in FIG. 4) between defective products is about 3 days. Was confirmed.

  That is, as in the secondary battery inspection method according to the first embodiment of the present invention, by determining the stratification condition for generating the inspection target lot based on the measurement result of the self-discharge amount ΔV, The time required for the inspection for the presence of an internal short circuit can be greatly reduced as compared with the conventional case.

  Further, as in the secondary battery inspection method according to the first embodiment of the present invention, when the stratification condition for generating the inspection target lot is determined based on the measurement result of the self-discharge amount ΔV, the self-discharge amount ΔV ( That is, since the battery voltages V1 and V2) are characteristic values that are originally measured, it is possible to generate a lot to be inspected without increasing the number of measurement steps, which is advantageous.

  As in the secondary battery inspection method according to the first embodiment of the present invention, the stratification condition for generating the inspection target lot is determined based on the measurement result of the self-discharge amount ΔV, and the stratification condition is further defined. By taking into account the production lot of the secondary battery, the variation in the self-discharge amount ΔV can be further suppressed, and the inspection time can be further shortened.

  That is, the inspection method of the nonaqueous electrolyte secondary battery according to the first embodiment of the present invention measures the battery voltages V1 and V2 of the nonaqueous electrolyte secondary battery before and after the room temperature aging process (STEP-3). Then, the self-discharge amount ΔV of the nonaqueous electrolyte secondary battery in the normal temperature aging process (STEP-3) is calculated, and the presence or absence of an internal short circuit in the nonaqueous electrolyte secondary battery is inspected based on the self-discharge amount ΔV. Before and after the room temperature aging step (STEP-3), the step of measuring the characteristic value of the nonaqueous electrolyte secondary battery (in this embodiment, the battery voltage V1 · V2) (in this embodiment (STEP-2)) and (STEP-4)) and grouping the nonaqueous electrolyte secondary batteries based on the measured characteristic values (in this embodiment, based on the self-discharge amount ΔV calculated by the measured battery voltages V1 and V2). An inspection target lot generated Te, for each inspection target lot is for inspecting the presence or absence of internal short circuit in the nonaqueous electrolyte secondary battery based on the self-discharge quantity [Delta] V.

  In the inspection method for a nonaqueous electrolyte secondary battery according to the first embodiment of the present invention, the characteristic value is set to battery voltages V1 and V2 of the nonaqueous electrolyte secondary battery.

  With such a configuration, it is possible to suppress the variation of the self-discharge amount ΔV, which is a comparison factor for determining the presence or absence of an internal short circuit, as compared with the conventional case, and the presence or absence of the internal short circuit is improved while improving the inspection accuracy. The time required for determination can be shortened.

Next, a secondary battery inspection method according to the second embodiment of the present invention will be described.
As shown in FIG. 5, in the secondary battery inspection method according to the second embodiment of the present invention, as a stratification condition for generating a lot to be inspected in the determination of the presence or absence of a micro short circuit (STEP-5), the cell It is set as the structure which employ | adopts temperature T1 * T2 (STEP-5-23).
And it is set as the structure which determines the presence or absence of a micro short circuit based on the inspection object lot produced | generated using cell temperature T1 * T2 as a stratification condition (STEP-5-24).

  Moreover, in the secondary battery inspection method according to the second embodiment of the present invention, in order to know the cell temperatures T1 and T2 which are the stratified conditions for generating the inspection target lot, normal temperature aging (STEP-3) ) Before the measurement of the voltage V1 (STEP-2), the step of measuring the cell temperature T1 (STEP-5-21), and after the normal temperature aging (STEP-3), the measurement of the voltage V2 (STEP-) 4) measuring the cell temperature T2 (STEP-5-22).

  Moreover, in the inspection method of the secondary battery which concerns on 2nd embodiment of this invention, it is set as the structure which maintains the cell temperature of a secondary battery in the range of +/- 3 degreeC in normal temperature aging (STEP-3).

Here, an example of generating an inspection target lot using the cell temperatures T1 and T2 as stratification conditions will be described with reference to FIG.
If the measurement results of the cell temperatures T1 and T2 of each secondary battery to be inspected are represented on the graph with the horizontal axis as T1 and the vertical axis as T2, it can be expressed as shown in FIG.
The battery lots in which the values of the cell temperatures T1 and T2 fall within a predetermined range set in advance are collected to generate one inspection target lot.
In addition, cell temperature T1 * T2 of each secondary battery is calculated | required by calculating the average value of the temperature of the some cell with which each secondary battery is each provided.

For example, in FIG. 6A, for 20 secondary batteries, a total of four lots to be inspected, with one battery lot having cell temperatures T1 and T2 in the range of ± 1 ° C. The case where (inspection lots 1 to 4) are generated is illustrated.
And it is set as the structure which determines the presence or absence of a micro short circuit by comparing self discharge amount (DELTA) V for every lot to be examined finally produced | generated based on cell temperature T1 * T2.

Here, with reference to FIG. 6B and FIG. 8, description will be given of the determination status of the presence or absence of a micro short-circuit when the inspection target lot is generated based on the cell temperatures T1 and T2.
As shown in FIG. 8, when the inspection target lot is generated from the production lot of the secondary battery as in the prior art, the variation in the self-discharge amount ΔV in the non-defective product (a group indicated by the arrow Y1 in FIG. 8) and the defective product In order to determine the deviation amount of the self-discharge amount ΔV (indicated by the arrow X1 in FIG. 8), the self-discharge days are required to be about 17 days.

On the other hand, as shown in FIG. 6B, when a lot to be inspected is generated based on the cell temperatures T1 and T2, the measurement result of the self-discharge amount ΔV (indicated by arrows X1 and Y1 in FIG. 6B) ) Can be suppressed.
For example, when a lot to be inspected is generated by covering secondary batteries whose cell temperatures T1 and T2 are within a range of ± 1 ° C., variations in the self-discharge amount ΔV among the non-defective products (arrows in FIG. 6B) It can be confirmed that the number of days of self-discharge required to determine the amount of deviation between the difference in self-discharge amount ΔV in the defective product (indicated by arrow X2 in FIG. 6B) is about 7 days. It was.

  That is, as in the secondary battery inspection method according to the second embodiment of the present invention, the secondary battery is determined by determining the stratification conditions for generating the inspection target lot based on the measurement results of the cell temperatures T1 and T2. It is possible to significantly reduce the time required for the inspection for the presence or absence of an internal short circuit as compared with the prior art.

  Further, in the secondary battery inspection method according to the second embodiment of the present invention, the stratification condition is determined based on the measurement results of the cell temperatures T1 and T2. For example, the average temperature of the cells during normal temperature aging The calculated value may be used as the stratification condition, and the inspection target lot may be generated with each secondary battery whose calculated average temperature is within a predetermined range (for example, within ± 1 ° C.).

  As in the secondary battery inspection method according to the second embodiment of the present invention, the stratification condition for generating the inspection target lot is determined based on the measurement results of the cell temperatures T1 and T2, and the stratification condition is further determined. As a result, by taking into account the production lot of the secondary battery, the variation in the self-discharge amount ΔV can be further suppressed, and the inspection time can be further shortened.

  That is, the nonaqueous electrolyte secondary battery inspection method according to the second embodiment of the present invention measures the battery voltages V1 and V2 of the nonaqueous electrolyte secondary battery before and after the room temperature aging process (STEP-3). Then, the self-discharge amount ΔV of the nonaqueous electrolyte secondary battery in the normal temperature aging process (STEP-3) is calculated, and the presence or absence of an internal short circuit in the nonaqueous electrolyte secondary battery is inspected based on the self-discharge amount ΔV. Then, before and after the room temperature aging step (STEP-3), steps ((STEP-5-21) and (STEP-5-21) for measuring characteristic values of the non-aqueous electrolyte secondary battery (in this embodiment, cell temperatures T1 and T2) -5-22)), grouping the non-aqueous electrolyte secondary batteries based on the measured cell temperatures T1 and T2, and generating a lot to be inspected. For each lot to be inspected, non-water based on the self-discharge amount ΔV It is intended to inspect the presence or absence of internal short circuit in the solution electrolyte secondary battery.

  In the inspection method for a non-aqueous electrolyte secondary battery according to the second embodiment of the present invention, the characteristic value is set to the cell temperatures T1 and T2 of the non-aqueous electrolyte secondary battery.

  With such a configuration, it is possible to suppress the variation of the self-discharge amount ΔV, which is a comparison factor for determining the presence or absence of an internal short circuit, as compared with the conventional case, and the presence or absence of the internal short circuit is improved while improving the inspection accuracy. The time required for determination can be shortened.

1 cell 10 secondary battery (non-aqueous electrolyte secondary battery)
V1 battery voltage (before room temperature aging)
V2 battery voltage (after normal temperature aging)
ΔV Self-discharge amount T1 Cell temperature (before normal temperature aging)
T2 cell temperature (after normal temperature aging)

Claims (3)

Before and after the aging process in which the nonaqueous electrolyte secondary battery is left at a predetermined temperature for a predetermined time, the battery voltage of the nonaqueous electrolyte secondary battery is measured, and the self-charge of the nonaqueous electrolyte secondary battery in the aging process is measured. A method for inspecting a non-aqueous electrolyte secondary battery that calculates a discharge amount and inspects for the presence or absence of an internal short circuit in the non-aqueous electrolyte secondary battery based on the self-discharge amount,
Before and after the aging step, comprising measuring a characteristic value of the non-aqueous electrolyte secondary battery,
Based on the measured characteristic value, the non-aqueous electrolyte secondary batteries are grouped to generate a lot to be inspected, and for each lot to be inspected, an internal short circuit in the non-aqueous electrolyte secondary battery is based on the self-discharge amount. Check for presence,
An inspection method for a nonaqueous electrolyte secondary battery. The characteristic value is
The cell temperature of the non-aqueous electrolyte secondary battery,
The inspection method for a nonaqueous electrolyte secondary battery according to claim 1. The characteristic value is
The battery voltage of the non-aqueous electrolyte secondary battery,
The inspection method for a nonaqueous electrolyte secondary battery according to claim 1.

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