JP2018055878A - Manufacturing method of battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a battery capable of shortening the time required for a short-circuiting detection step of detecting the presence/absence of internal short-circuiting in the battery.SOLUTION: A manufacturing method of a battery 1 includes a charge step S2, an aging step S3, a voltage regulation step S4 and a short-circuiting detection step S5. The battery 1 has a property that, when the battery is left in a terminal open state after the voltage regulation step S4, a battery voltage Ve gradually rises, achieves a peak after the lapse of a peak achievement time TP, and then gradually decreases. The short-circuiting detection step S5 is a step for detecting the presence/absence of internal short-circuiting in the battery 1 on the basis of a level of a voltage rising amount ΔV with a third battery voltage V3 defined as a reference after the lapse of (TP/40 to TP/15) from the end of the voltage regulation step S4 while leaving the battery 1 in the terminal open state.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a battery manufacturing method including a short-circuit detection step for detecting whether or not an internal short circuit is present in a battery.

  In the process of manufacturing a battery such as a lithium ion secondary battery, it is known to perform a short circuit inspection to determine whether an internal short circuit has occurred in the battery. Specifically, after the battery is initially charged and left at high temperature for aging, the battery is forcibly discharged to adjust the battery voltage to a predetermined value. Then, a short circuit detection process is performed. Specifically, the battery is discharged with its terminals open (self-discharged), and the voltage drop amount ΔVp is obtained. When this voltage drop amount ΔVp is larger than the reference drop amount ΔVq (ΔVp> ΔVq), it is determined that an internal short circuit has occurred in the battery. For example, Patent Document 1 discloses that an inspection for the presence of an internal short circuit is performed in the battery manufacturing process (see FIG. 2 of Patent Document 1).

JP 2014-134395 A

  However, immediately after adjusting the battery voltage by lowering the battery voltage, the battery voltage naturally rises. Therefore, when detecting the presence or absence of an internal short circuit based on the voltage drop amount ΔVp as described above, the battery voltage rises. The voltage drop amount ΔVp is obtained from the decrease in the battery voltage after the increase in the battery voltage has stopped. For this reason, it took a long time to perform self-discharge, and a long time was required for the short-circuit detection process.

  This invention is made | formed in view of this present condition, Comprising: It aims at providing the manufacturing method of the battery which can shorten the time concerning the short circuit detection process which detects whether the battery has an internal short circuit.

  One aspect of the present invention for solving the above problems includes a charging step of initially charging a battery, an aging step of leaving the battery at a temperature of 40 to 85 ° C. after the charging step, and a battery of the battery A voltage adjustment step of adjusting the voltage to a second battery voltage V2 lower than the first battery voltage V1 immediately after the aging step; and a short-circuit detection step of detecting the presence or absence of an internal short circuit of the battery after the voltage adjustment step; When the battery is left in a terminal open state after the voltage adjustment step, the battery voltage gradually rises from the end of the voltage adjustment step, and the end. It has a characteristic that it reaches a peak after elapse of the peak arrival time TP from time and then gradually decreases, and the short-circuit detection step leaves the battery in a state where the terminal is opened after the voltage adjustment step. Adjustment It is a step of detecting the presence or absence of an internal short circuit of the battery based on the amount of voltage increase ΔV with respect to the third battery voltage V3 after the lapse of (TP / 40 to TP / 15) from the end of the above. It is a manufacturing method of a battery.

In the battery manufacturing method described above, the third battery voltage V3 after the lapse of (TP / 40 to TP / 15) from the end of the voltage adjustment process is used as a reference in the short-circuit detection process performed after the voltage adjustment process for reducing the battery voltage. Based on the amount of voltage increase ΔV, it is detected whether or not the battery has an internal short circuit.
As a result of investigation by the present inventor, it was found that the above-mentioned voltage increase ΔV is large in a battery in which an internal short circuit occurs, and the voltage increase ΔV is small in a battery without an internal short circuit. Therefore, it is possible to detect whether or not the battery has an internal short circuit based on the amount of voltage increase ΔV.
Moreover, conventionally, the voltage drop amount ΔVp is measured after waiting for the increase in the battery voltage after voltage adjustment to stop, whereas in the above-described battery manufacturing method, the battery voltage after voltage adjustment is increasing. The presence or absence of an internal short circuit is detected on the basis of the voltage increase amount ΔV measured. For this reason, the time required for the short circuit detection step can be shortened.

  In the “charging process”, for example, it is preferable to initially charge the battery at a voltage equal to or higher than the battery voltage corresponding to SOC 60%. This is because the higher the value of the battery voltage after charging, the easier the aging of the battery proceeds in the subsequent aging process. On the other hand, the higher the value of the battery voltage after charging, the longer the time taken for the charging process. Therefore, it is preferable to set the value of the battery voltage in the charging process in consideration of these.

  In the “aging step”, for example, it is preferable to perform aging in which the battery is left for 8 to 48 hours. This standing time is preferably set in consideration of the value of the battery voltage of the battery after charging in the charging process, the temperature at which the aging process is performed, and the like. Moreover, the aging process may be performed in a state where the terminal of the battery is open, or may be performed in a state where a power source is connected to the battery and maintained at a constant voltage.

  In the “voltage adjustment step”, only the discharge is performed to adjust the battery voltage from the first battery voltage V1 to the second battery voltage V2, and the battery voltage is changed to the first by discharging together with the discharge and finally discharging. It is also possible to adjust from the battery voltage V1 to the second battery voltage V2. For example, after forcibly discharging the first battery voltage V1 to the fifth battery voltage V5 lower than the first battery voltage V1, the battery is charged from the fifth battery voltage V5 to the sixth battery voltage V6 higher than the second battery voltage V2. Thereafter, a method of forcibly discharging from the sixth battery voltage V6 to the second battery voltage V2 can be mentioned. The second battery voltage V2 is preferably a battery voltage corresponding to an SOC within a range of 10 to 60% SOC, for example.

  As a specific method of “detecting the presence or absence of an internal short circuit of the battery based on the amount of the voltage increase ΔV” in the “short circuit detection step”, for example, the voltage increase ΔV of the inspected battery is a predetermined standard. A method of determining that an internal short circuit has occurred in the battery when the amount of increase ΔVr is larger (ΔV> ΔVr) is mentioned. Also, whether the voltage increase ΔV of the inspected battery is compared with, for example, the average value or the median value of the voltage increase ΔV obtained from a plurality of batteries of the same production lot as this battery, and whether or not an internal short circuit has occurred in the battery. There is also a method of determining whether or not.

  In the battery manufacturing method described above, the voltage increase amount ΔV is a battery manufacturing method that is a voltage increase amount when (TP / 5 to TP) has elapsed since the end of the voltage adjustment step. Is preferred.

The voltage increase amount ΔV is preferably measured after a certain period from the end of the voltage adjustment step. On the other hand, if the period from the end of the voltage adjustment process is too long, in a battery having an internal short circuit, the battery voltage rises and reaches a peak, and then the battery voltage greatly decreases. For this reason, the voltage difference between the voltage increase amount ΔV of the battery having the internal short circuit and the voltage increase amount ΔV of the battery without the internal short circuit tends to be small, and it is difficult to detect the presence or absence of the internal short circuit based on the voltage increase amount ΔV. Become.
On the other hand, in the above-described battery manufacturing method, the voltage increase amount ΔV is the voltage increase amount when (TP / 5 to TP) has elapsed since the end of the voltage adjustment step. Thus, a battery in which an internal short circuit has occurred can be detected more reliably.

It is a perspective view of the battery which concerns on embodiment. It is a longitudinal cross-sectional view of the battery which concerns on embodiment. It is a flowchart which shows the manufacturing process of the battery which concerns on embodiment. It is a graph which shows the relationship between the elapsed time Ta from the time of completion | finish of a voltage adjustment process, and the battery voltage Ve about an example of the defective battery in which the internal short circuit has arisen, and the non-defective average battery without an internal short circuit. For each of the defective and non-defective batteries shown in FIG. 4, the voltage change with reference to the elapsed time Ta from the end of the voltage adjustment process and 3.25 hr from the end of the voltage adjustment process as a reference (= 0 mV) It is a graph which shows the relationship with quantity (DELTA) Va. For each of the defective and non-defective batteries shown in FIG. 4, the voltage change based on the elapsed time Ta from the end of the voltage adjustment process and 5.08 hr from the end of the voltage adjustment process as a reference (= 0 mV) It is a graph which shows the relationship with quantity (DELTA) Vb. For each of the defective and non-defective batteries shown in FIG. 4, the voltage change with reference to the elapsed time Ta from the end of the voltage adjustment process and 72.0 hours after the end of the voltage adjustment process (= 0 mV) It is a graph which shows the relationship with quantity (DELTA) Vc.

  Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show a perspective view and a longitudinal sectional view of a battery 1 according to this embodiment. In the following description, the battery thickness direction BH, the battery lateral direction CH, and the battery vertical direction DH of the battery 1 are defined as the directions shown in FIGS. 1 and 2. The battery 1 is a rectangular and sealed lithium ion secondary battery mounted on a vehicle such as a hybrid car, a plug-in hybrid car, or an electric car. The battery 1 includes a battery case 10, an electrode body 20 accommodated therein, a positive terminal member 50 and a negative terminal member 60 supported by the battery case 10, and the like. In addition, a non-aqueous electrolyte 19 is accommodated in the battery case 10, and a part thereof is impregnated in the electrode body 20.

  Among these, the battery case 10 has a rectangular parallelepiped box shape and is made of metal (in this embodiment, aluminum). The battery case 10 is composed of a bottomed rectangular tube-shaped case main body member 11 that is open only on the upper side, and a rectangular plate-shaped case lid member 13 that is welded in a form that closes the opening of the case main body member 11. The A positive terminal member 50 made of aluminum is fixed to the case lid member 13 while being insulated from the case lid member 13. The positive electrode terminal member 50 is connected to the positive electrode plate 21 of the electrode body 20 in the battery case 10 to be conductive, and extends through the case lid member 13 to the outside of the battery. Further, a negative electrode terminal member 60 made of copper is fixed to the case lid member 13 while being insulated from the case lid member 13. The negative electrode terminal member 60 is connected to and conductive with the negative electrode plate 31 of the electrode body 20 in the battery case 10, and extends through the case lid member 13 to the outside of the battery.

  The electrode body 20 has a flat shape and is accommodated in the battery case 10 in a laid-down state. Between the electrode body 20 and the battery case 10, a bag-shaped insulating film enclosure 17 made of an insulating film is disposed. The electrode body 20 is formed by laminating a belt-like positive electrode plate 21 and a belt-like negative electrode plate 31 with a pair of strip-like separators 41 and 41 wound around each other and compressed in a flat shape. The positive electrode plate 21 is provided with a positive electrode active material layer in a band shape at predetermined positions on both main surfaces of a positive electrode current collector foil made of a band-shaped aluminum foil. This positive electrode active material layer is composed of a positive electrode active material (lithium transition metal composite oxide in this embodiment), a conductive material (acetylene black in this embodiment), and a binder (polyvinylidene fluoride in this embodiment). Moreover, the negative electrode plate 31 is provided with a negative electrode active material layer at a predetermined position on both main surfaces of a negative electrode current collector foil made of a strip-shaped copper foil. This negative electrode active material layer is composed of a negative electrode active material (graphite in this embodiment), a binder (styrene butadiene rubber in this embodiment), and a thickener (carboxymethyl cellulose in this embodiment). The separator 41 is a porous film made of a resin and has a strip shape and a film shape.

  Next, a method for manufacturing the battery 1 will be described (see FIG. 3). First, in the “assembly process S1”, the battery 1 is assembled. Specifically, the positive electrode plate 21 and the negative electrode plate 31 are overlapped with each other via a pair of separators 41 and 41 and wound into a flat shape to form the electrode body 20. Next, the case lid member 13 is prepared, and the positive electrode terminal member 50 and the negative electrode terminal member 60 are fixed thereto (see FIGS. 1 and 2). Thereafter, the positive electrode terminal member 50 and the negative electrode terminal member 60 are welded to the positive electrode plate 21 and the negative electrode plate 31 of the electrode body 20, respectively. Next, the electrode body 20 is covered with the insulating film enclosure 17 and inserted into the case main body member 11, and the opening of the case main body member 11 is closed with the case lid member 13. The case body member 11 and the case lid member 13 are welded to form the battery case 10. Thereafter, the nonaqueous electrolytic solution 19 is injected into the battery case 10 through the injection hole 13 h and impregnated in the electrode body 20. Thereafter, the injection hole 13 h is sealed with the sealing member 15.

Next, the battery 1 is restrained prior to performing the “charging step S2”. Specifically, the wide side surface of the battery case 10 is sandwiched in the battery thickness direction BH by a pair of plate-shaped pressing jigs, and the battery 1 is restrained while being pressed in the battery thickness direction BH. In the present embodiment, the “charging process S2” to the “short circuit detecting process S5” described below are performed in a state where the battery 1 is restrained in this manner.
After the battery 1 is restrained, the battery 1 is initially charged in “charging step S2”. Specifically, a charging / discharging device is connected to the battery 1 and the battery is initially charged to a voltage Ve = 4.1 V (SOC 100%) by constant current and constant voltage (CCCV) charging at room temperature (25 ± 5 ° C.). To do. In the present embodiment, the battery voltage Ve is maintained at 4.1 V until the battery voltage Ve reaches 4.1 V with a constant current of 1 C until the battery voltage Ve reaches 1.0 A.

  Next, in the “aging step S3”, the battery 1 is left at high temperature for aging. Specifically, the battery 1 after initial charging is aged by leaving it open for 20 hours at a temperature of 40 to 85 ° C. (63 ° C. in this embodiment) with the terminals open. If this aging process S3 is performed, the battery voltage Ve will fall very slightly (SOC will fall). In the present embodiment, the battery voltage Ve (first battery voltage V1) immediately after the aging step S3 is about 4.1 V (SOC is about 99%).

  Next, in the “voltage adjustment step S4”, the battery voltage Ve of the battery 1 is set to a second battery voltage V2 (mainly lower than the first battery voltage V1 immediately after the aging step S3 (about 4.1 V in this embodiment)). In the embodiment, it is adjusted to 2.8V). Specifically, a charging / discharging device is connected to the battery 1, and the first battery voltage V1 = about 4.1V is discharged from the first battery voltage V1 = about 4.1V by constant current constant voltage (CCCV) discharge at room temperature (25 ± 5 ° C.) The battery is forcibly discharged to a voltage V2 = 2.8V. In the present embodiment, the battery voltage Ve was maintained at 2.8V until the discharge current value reached 1.0 A after discharging at a constant current of 1 C until the battery voltage Ve reached 2.8V.

Subsequently, in the “short circuit detection step S5”, the battery 1 is left with the terminals opened (self-discharged), the voltage increase amount ΔV is acquired, and the presence or absence of the internal short circuit of the battery 1 is detected.
As described above, when the battery 1 is left with the terminal open after the voltage adjustment step S4 for reducing the battery voltage, the battery voltage Ve gradually increases from the end of the voltage adjustment step S4 and reaches a peak. It gradually decreases (see FIG. 4). FIG. 4 shows an example of the battery 1 in which an internal short circuit has occurred and an average battery 1 without an internal short circuit, the elapsed time Ta (hr) from the end of the voltage adjustment step S4 and the battery voltage Ve ( V). The time (peak arrival time) TP from the end of the voltage adjustment step S4 until the battery voltage Ve reaches a peak is TP = 93.3 hr on average in the non-defective battery 1 without an internal short circuit.

  In the short-circuit detection step S5, after the voltage adjustment step S4, the battery 1 is left in a state where the terminals are opened, and from the end of the voltage adjustment step S4 (TP / 40 to TP / 15: 2.33 in the present embodiment). The third battery voltage V3 is set to the third battery voltage V4 after the lapse of the voltage adjustment step S4 (TP / 5 to TP: 18.7 to 93.3 hours in this embodiment) after the lapse of .about.6.22 hr). Each is measured (see FIG. 5).

  Specifically, the battery 1 is left with the terminals open in an environment of 20 ° C., and the third battery voltage V3 is measured after 3.25 hours from the end of the voltage adjustment step S4 as shown in FIG. The fourth battery voltage V4 was measured after 48.0 hours had elapsed from the end of the voltage adjustment step S4. And the voltage increase amount (DELTA) V = V4-V3 of the said battery 1 was computed. In FIG. 5, for each of the defective and non-defective batteries shown in FIG. 4, the elapsed time Ta (hr) from the end of the voltage adjustment step S4 and 3.25 hours have elapsed from the end of the voltage adjustment step S4. The relationship with the voltage change amount ΔVa (mV) with the time point as the reference (= 0 mV) is shown.

Then, the obtained voltage increase amount ΔV of the battery 1 is compared with a predetermined reference increase amount ΔVr (in this embodiment, ΔVr = 25.4 mV), and the voltage increase amount ΔV is larger than the reference increase amount ΔVr. When (ΔV> ΔVr), the battery 1 is determined as a defective product in which an internal short circuit has occurred, and the battery 1 is removed. For example, in the battery 1 in which an internal short circuit occurs, as shown in FIG. 5, the voltage increase amount ΔV = 26.6 mV and ΔV> ΔVr, and therefore, it is determined as a defective product.
On the other hand, when the voltage increase amount ΔV of the battery 1 is smaller than the reference increase amount ΔVr (ΔV ≦ ΔVr), the battery 1 is determined to be a good product without an internal short circuit. As shown in FIG. 5, the average battery 1 of the non-defective product is determined as non-defective because the voltage increase amount ΔV = 24.3 mV and ΔV ≦ ΔVr.
After finishing short circuit detection process S5, the restraining jig | tool which restrains the battery 1 is removed, and the restraint-like body of the battery 1 is cancelled | released. Thus, the battery 1 is completed.

Here, in the present embodiment, as described above, in the short circuit detection step S5, the third battery voltage V3 and the fourth battery voltage V4 are measured while the battery voltage Ve is increasing to obtain the voltage increase amount ΔV, and this voltage The presence or absence of an internal short circuit of the battery 1 was detected based on the amount of increase ΔV.
On the other hand, as a comparative example (see FIG. 7), in the short-circuit detection step S5, in the process in which the battery voltage Ve rises and reaches a peak, the seventh battery voltage V7 and the eighth battery voltage V8 are gradually reduced. A case where the voltage drop amount ΔVp = V7−V8 is obtained by measurement and the presence or absence of an internal short circuit of the battery 1 is detected based on the amount of the voltage drop amount ΔVp will be described. FIG. 7 shows an elapsed time Ta (hr) from the end of the voltage adjustment step S4 and 3.0 days from the end of the voltage adjustment step S4 for each of the defective and non-defective batteries shown in FIG. 72.0 hr) shows the relationship with the voltage change amount ΔVc (mV) with the elapsed time as a reference (= 0 mV).

In this comparative example, the seventh battery voltage V7 is passed after 3.0 days (72 hours) from the end of the voltage adjustment step S4, and the eighth battery voltage is passed after 10.0 days (240 hours) from the end of the voltage adjustment step S4. V8 is measured, and a voltage drop amount ΔVp = V7−V8 is calculated.
When the acquired voltage drop amount ΔVp of the battery 1 is larger than a predetermined reference drop amount ΔVq (ΔVq = 1.4 mV in this comparative example) (ΔVp> ΔVq), the battery 1 is internally short-circuited. It is determined that the product is defective. For example, in the battery 1 in which an internal short circuit has occurred, the voltage drop amount ΔVp = 2.2 mV (in FIG. 7, the voltage change amount ΔVc = −2.2 mV) and ΔVp> ΔVq, and therefore, it is determined as a defective product. The
On the other hand, when the voltage drop amount ΔVp of the battery 1 is smaller than the reference drop amount ΔVq (ΔVp ≦ ΔVq), the battery 1 is determined to be a good product without an internal short circuit. In the non-defective battery 1, the voltage drop amount ΔVp = 0.6 mV (in FIG. 7, the voltage change amount ΔVc = −0.6 mV) and ΔVp ≦ ΔVr.

Thus, the presence or absence of the internal short circuit of the battery 1 can also be detected by acquiring the voltage drop amount ΔVp in the short circuit detection step S5. However, in this comparative example, in order to measure the seventh battery voltage V7 and the eighth battery voltage V8 and obtain the voltage drop amount ΔVp, 10 days (240 hours) from the end of the voltage adjustment step S4 are necessary, Short circuit detection process S5 becomes long.
On the other hand, in the above embodiment, the third battery voltage V3 and the fourth battery voltage V4 are measured and the voltage increase amount ΔV is acquired in two days (48.0 hr) from the end of the voltage adjustment step S4. It ’s enough. Therefore, in the said embodiment, it turns out that the time concerning short circuit detection process S5 can be shortened significantly compared with a comparative example.

In addition, in this comparative example, the voltage drop ΔVp = 2.2 mV in the battery 1 in which the internal short circuit occurs, and the voltage drop ΔVp = 0.6 mV in the non-defective battery 1, The voltage difference between the battery 1 and the defective battery 1 is 2.2−0.6 = 1.6 mV (see FIG. 7).
On the other hand, in the above embodiment, the voltage increase ΔV = 26.6 mV in the battery 1 in which the internal short circuit occurs, and the voltage increase ΔV = 24.3 mV in the non-defective battery 1. The voltage difference between the battery 1 and the defective battery 1 is 26.6 to 24.3 = 2.3 mV (see FIG. 5). Therefore, in the said embodiment, it turns out that the defective battery 1 which the internal short circuit has produced can be detected more reliably compared with the comparative example.

  In the short circuit detection step S5 of the above embodiment, as described above, the third battery voltage V3 is measured after 3.25 hours from the end of the voltage adjustment step S4. However, the measurement timing of the third battery voltage V3 is: It can be appropriately changed within the range of (TP / 40 to TP / 15: 2.33 to 6.22 hr in this embodiment) from the end of the voltage adjustment step S4. Further, the measurement timing of the fourth battery voltage V4 can be appropriately changed within the range of (TP / 5 to TP: 18.7 to 93.3 hr in the present embodiment) from the end of the voltage adjustment step S4.

  FIG. 6 shows the elapsed time Ta (hr) from the end of the voltage adjustment step S4 and the time point when 5.08 hr has elapsed from the end of the voltage adjustment step S4 for each of the defective and non-defective batteries shown in FIG. A relationship with a voltage change amount ΔVb (mV) as a reference (= 0 mV) is shown. The measurement timing of the third battery voltage V3 is set after 5.08 hr from the end of the voltage adjustment step S4, and the measurement timing of the fourth battery voltage V4 is set after 48.0 hr after the end of the voltage adjustment step S4. In this case, the reference increase amount ΔVr is set to ΔVr = 14.6 mV, for example.

When the acquired voltage increase amount ΔV of the battery 1 is larger than the reference increase amount ΔVr (ΔV> ΔVr), the battery 1 is determined as a defective product in which an internal short circuit has occurred. For example, in the battery 1 in which an internal short circuit has occurred, as shown in FIG. 6, the voltage increase amount ΔV = 14.9 mV and ΔV> ΔVr, and therefore, it is determined as a defective product.
On the other hand, when the voltage increase amount ΔV is smaller than the reference increase amount ΔVr (ΔV ≦ ΔVr), the battery 1 is determined to be a good product without an internal short circuit. As shown in FIG. 6, the average battery 1 of the non-defective product is determined as non-defective because the voltage increase ΔV = 14.3 mV and ΔV ≦ ΔVr.

As described above, in the manufacturing method of the battery 1, in the short circuit detection step S5 performed after the voltage adjustment step S4 for reducing the battery voltage, (TP / 40 to TP / 15) after the end of the voltage adjustment step S4. Whether or not the battery 1 has an internal short circuit is detected based on the amount of voltage increase ΔV with respect to the third battery voltage V3. As described above, in the battery 1 in which the internal short circuit occurs, the voltage increase amount ΔV is large as described above, and in the battery 1 without the internal short circuit, the voltage increase amount ΔV is small. Therefore, whether or not the battery 1 has an internal short circuit can be detected based on the amount of voltage increase ΔV.
Moreover, in the past, the voltage drop amount ΔVp was measured after waiting for the increase in the battery voltage Ve after voltage adjustment to stop, whereas in the manufacturing method of the battery 1, the increase in the battery voltage Ve after voltage adjustment was measured. The presence / absence of an internal short circuit is detected based on the voltage increase amount ΔV measured in the inside. For this reason, the time required for the short circuit detection step S5 can be shortened.

  Furthermore, in the manufacturing method of the battery 1, the voltage increase amount ΔV is the voltage increase amount when (TP / 5 to TP) has elapsed from the end of the voltage adjustment step S4. The voltage increase amount ΔV is preferably measured after taking a certain period of time from the end of the voltage adjustment step S4. On the other hand, if the period from the end of the voltage adjustment step S4 is too long, in the battery 1 having the internal short circuit, after the battery voltage Ve rises and reaches a peak, the battery voltage Ve greatly decreases. For this reason, the voltage difference between the voltage increase amount ΔV of the battery 1 having an internal short circuit and the voltage increase amount ΔV of the battery 1 having no internal short circuit tends to be small, and the presence or absence of the internal short circuit is detected based on the voltage increase amount ΔV. It becomes difficult to do. On the other hand, in the manufacturing method of the battery 1, since the voltage increase amount ΔV is the voltage increase amount when (TP / 5 to TP) has elapsed from the end of the voltage adjustment step S4, it is based on the voltage increase amount ΔV. Thus, the battery 1 in which an internal short circuit has occurred can be detected more reliably.

In the above, the present invention has been described with reference to the embodiment. However, the present invention is not limited to the above-described embodiment, and it is needless to say that the present invention can be appropriately modified and applied without departing from the gist thereof.
For example, in the embodiment, when the voltage increase amount ΔV of the inspected battery 1 is larger than a predetermined reference increase amount ΔVr (ΔV> ΔVr), it is determined that an internal short circuit has occurred in the battery 1, It is not limited to this. For example, an average value Δm of the voltage increase amount ΔV is obtained from the battery group of the same production lot, and further, ΔV−Δm, which is a voltage difference between the voltage increase amount ΔV of the inspected battery 1 and the average value Δm, is obtained. When this voltage difference (ΔV−Δm) is larger than a predetermined reference voltage difference ΔVs (ΔV−Δm> ΔVs), it can be determined that an internal short circuit has occurred in the battery 1.
Moreover, in embodiment, although charging process S2 to short circuit detection process S5 was performed in the state which restrained the battery 1, these processes S2-S5 can also be performed without restraining the battery 1. FIG.

DESCRIPTION OF SYMBOLS 1 Battery S1 Assembly process S2 Charging process S3 Aging process S4 Voltage adjustment process S5 Short circuit detection process Ta Elapsed time TP Peak arrival time Ve Battery voltage V1 1st battery voltage V2 2nd battery voltage V3 3rd battery voltage V4 4th battery voltage (DELTA) V Voltage increase ΔVr Reference increase

Claims (1)

A charging process for charging the battery for the first time;
After the charging step, an aging step of leaving the battery at a temperature of 40 to 85 ° C;
A voltage adjustment step of adjusting the battery voltage of the battery to a second battery voltage V2 lower than the first battery voltage V1 immediately after the aging step;
After the voltage adjustment step, a short circuit detection step for detecting the presence or absence of an internal short circuit of the battery, and a battery manufacturing method comprising:
The battery
When the battery is left open after the voltage adjustment step, the battery voltage gradually increases from the end of the voltage adjustment step, reaches a peak after the peak arrival time TP from the end, and then gradually. Has the property of deteriorating,
The short circuit detection step
After the voltage adjustment step, the battery is left with the terminals open, and a voltage based on the third battery voltage V3 after (TP / 40 to TP / 15) has elapsed since the end of the voltage adjustment step. A battery manufacturing method, which is a step of detecting the presence or absence of an internal short circuit of the battery based on the amount of increase ΔV.

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