JP6693393B2 - Battery manufacturing method - Google Patents

Description

  The present invention relates to a battery manufacturing method including an IV resistance inspection step of acquiring an IV resistance value Ra of a battery and determining the quality of the battery based on the IV resistance value Ra.

  BACKGROUND ART In the process of manufacturing a battery such as a lithium ion secondary battery, the internal resistance of the battery is inspected. Specifically, after the assembled battery is initially charged, the battery is left to stand until the battery voltage becomes stable. After that, the IV resistance value Ra of the battery is acquired, and when the IV resistance value Ra is larger than the reference resistance value Rs (Ra> Rs), the battery is determined as a defective product. As a related conventional technique, there is Patent Document 1.

JP, 2014-185927, A

  However, the decrease in the battery voltage after the initial charging becomes smaller as time passes, but it takes, for example, several days until the battery voltage becomes stable. Therefore, there is a problem that it takes a long time to perform the IV resistance test (measurement of the IV resistance value Ra) after the battery voltage becomes stable after the completion of the initial charge.

  On the other hand, if the IV resistance value Ra is measured early after the initial charge, the time from the end of the initial charge to the measurement of the IV resistance value Ra can be shortened. However, as described above, since the battery voltage drops largely after the initial charge (the voltage drop amount per unit time is large), if the measurement timing of the IV resistance value Ra deviates from the reference timing for some reason, The measured IV resistance value Ra changes greatly (as will be described later, for example, when the measurement timing of the IV resistance value Ra is shifted from the reference timing by 8 minutes, the IV resistance value Ra differs by 44.4%. End). Therefore, it is difficult to properly measure the IV resistance value Ra.

  The present invention has been made in view of the above circumstances, and is capable of shortening the period from the end of the initial charging step to measuring the IV resistance value Ra and manufacturing the battery capable of appropriately measuring the IV resistance value Ra. The purpose is to provide a method.

One embodiment of the present invention for solving the above problems comprises an electrode body in which a positive electrode plate and a negative electrode plate are stacked via a separator, and an electrolytic solution impregnated in the electrode body, and the negative electrode active material of the negative electrode plate. The layer is a method for producing a battery, which has a facing portion that faces the positive electrode active material layer of the positive electrode plate and a non-facing portion that does not face the positive electrode active material layer, and is a room temperature (25 ± 5 ° C. ) in the lower, the initial charging step of the initial charge of the battery to the first battery voltage V1, subsequent to the first charging step, a discharge step of discharging the battery to the second battery voltage V2, subsequent to the discharging process A recharging step of recharging the battery to a third battery voltage V3 (V2 <V3 <V1) lower than the first battery voltage V1 at room temperature (25 ± 5 ° C.), and after the recharging step , The IV resistance value Ra of the battery is acquired, and based on this IV resistance value Ra Then, it is a manufacturing method of the battery provided with the IV resistance inspection process which determines the quality of the said battery.

  In the battery manufacturing method described above, the IV resistance inspection step is performed after the discharging step and the recharging step are performed after the initial charging step. By doing so, the decrease in the battery voltage (both terminals open voltage) after the recharging process is lower than the decrease in the battery voltage after the initial charging process when the IV resistance inspection process is performed after the initial charging process. Get smaller. For this reason, even if the measurement timing of the IV resistance value Ra deviates from the reference timing for some reason, the difference in the acquired IV resistance value Ra is smaller than that in the case where the IV resistance inspection step is performed subsequent to the initial charging step. Can be made smaller. Therefore, it is not necessary to strictly manage the measurement timing of the IV resistance value Ra, and the IV resistance value Ra can be appropriately measured. In addition, in the battery manufacturing method described above, since the decrease in the battery voltage after the recharging step is small, it is not necessary to leave the battery for a long time until the battery voltage becomes stable. Therefore, the period from the end of the initial charging process to the measurement of the IV resistance value Ra can be shortened.

  The reason why the decrease in the battery voltage after the recharging step is smaller than the decrease in the battery voltage after the initial charging step when the IV resistance inspection step is performed after the initial charging step is considered to be as follows. That is, it is assumed that the battery is initially charged to the third battery voltage V3 from the beginning when the IV resistance inspection process is performed after the initial charging process. Then, the battery voltage after the initial charging process drops significantly for a long time. This is because ions that are responsible for electrical conduction, such as lithium ions inserted into the facing portion of the negative electrode active material layer by initial charging, gradually diffuse into the non-facing portion of the negative electrode active material layer after initial charging. Then, as the ions escape from the front facing portion of the negative electrode active material layer, the negative electrode potential of the negative electrode plate increases, and the battery voltage, which is the difference between the positive electrode potential and the negative electrode potential, appears to decrease correspondingly. In this way, when the IV resistance inspection process is performed after the initial charging process, if the battery voltage after the initial charging process (after charging to the third battery voltage V3 before the IV resistance inspection) drops significantly for a long time. Conceivable.

  On the other hand, in the battery manufacturing method described above, the battery is initially charged to the first battery voltage V1 (V1> V3) higher than the third battery voltage V3 in the initial charging step. Therefore, as compared with the above case in which the battery is charged to the third battery voltage V3 in the initial charging step, many ions are once inserted in the facing portion of the negative electrode active material layer, and accordingly, the non-facing portion is also charged. Many ions diffuse. Then, in this state, the discharging step and the recharging step are performed to adjust the battery voltage to the third battery voltage V3. Therefore, at the end of the recharging step, more ions are generated than at the end of the initial charging step in the above case. Exists in the non-face-to-face section. Therefore, compared to after the initial charging process in the above-mentioned case, the diffusion of ions from the facing portion to the non-facing portion after the recharging step is suppressed, and the negative electrode potential is accordingly increased and the battery voltage is lowered. Is suppressed. Thus, it is considered that the decrease in the battery voltage after the recharging process (after charging to the third battery voltage V3 before the IV resistance inspection) is smaller than in the case where the IV resistance inspection process is performed subsequent to the initial charging process. ..

  As a specific method of “determining the quality of the battery based on the IV resistance value Ra” in the IV resistance inspection step, for example, the IV resistance value Ra of the inspected battery is set to a predetermined reference resistance value Rs. If it is larger than (Ra> Rs), the battery may be determined to be defective. Further, for example, a reference resistance value Rs is determined from the IV resistance value Ra obtained in the same manner for a plurality of batteries in the same manufacturing lot as this battery, and when the reference resistance value Rs is larger than the reference resistance value Rs, the battery is determined as a defective product. The method is also included.

  In addition, as a specific method for obtaining the “IV resistance value Ra”, the battery is discharged at a predetermined current (current value I), and the battery voltage Va after Ta seconds and the battery voltage after Tb seconds after the start of the discharge. A method of measuring Vb and calculating IV resistance Ra by Ra = (Va−Vb) / I can be mentioned.

  As the “electrode body” of the battery, for example, a wound type electrode body in which a strip-shaped positive electrode plate and a strip-shaped negative electrode plate are alternately stacked with a pair of strip-shaped separators and wound around an axis in a cylindrical or flat shape. Is mentioned. Further, a laminated electrode body in which a plurality of positive electrode plates and a plurality of negative electrode plates each having a predetermined shape (for example, rectangular shape) are alternately laminated with a separator interposed is also included.

  Furthermore, in the above-mentioned battery manufacturing method, the initial charging step and the recharging step charge the battery by constant current constant voltage (CCCV) charging, and the discharging step discharges constant current (CC). Therefore, it is preferable that the battery is manufactured by discharging the battery.

It is a perspective view of the battery which concerns on embodiment. It is a longitudinal section of a battery concerning an embodiment. It is a perspective view of the electrode body which concerns on embodiment. FIG. 3 is a development view of an electrode body showing a state in which a positive electrode plate and a negative electrode plate are stacked on each other with a separator interposed therebetween according to the embodiment. 5 is a flowchart showing a manufacturing process of the battery according to the embodiment. 9 is a graph showing the relationship between the elapsed time Te from the start of the initial charging process and the battery voltage Ve according to the embodiment. 9 is a graph showing a relationship between the elapsed time Te from the start of the initial charging process and the battery voltage Ve according to the comparative example.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 and 2 are a perspective view and a vertical sectional view of a battery 1 according to this embodiment. 3 and 4 are a perspective view and a developed view of the electrode body 20 that constitutes the battery 1. In the following description, the battery thickness direction BH, the battery horizontal direction CH, and the battery vertical direction DH of the battery 1 are described as the directions shown in FIGS. 1 and 2.
The battery 1 is a square and sealed lithium-ion secondary battery mounted in a vehicle such as a hybrid car, a plug-in hybrid car, an electric vehicle, or the like. The battery 1 includes a battery case 10, an electrode body 20 housed inside the battery case 10, a positive electrode terminal member 50 and a negative electrode terminal member 60 supported by the battery case 10. Further, the electrolytic solution 17 is contained in the battery case 10, and a part of the electrolytic solution 17 is impregnated in the electrode body 20.

  Of these, the battery case 10 has a rectangular parallelepiped box shape and is made of metal (aluminum in the present embodiment). The battery case 10 is composed of a bottomed rectangular tubular case body member 11 that is open only on the upper side, and a rectangular plate-shaped case lid member 13 welded to close the opening of the case body member 11. It A positive electrode terminal member 50 made of aluminum is fixed to the case lid member 13 in a state of being insulated from the case lid member 13. The positive electrode terminal member 50 is connected to the positive electrode exposed portion 21m of the positive electrode plate 21 of the electrode body 20 in the battery case 10 so as to be conductive, and extends through the case cover 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 the negative electrode exposed portion 31m of the negative electrode plate 31 of the electrode body 20 in the battery case 10 so as to be conductive, and extends through the case cover member 13 to the outside of the battery.

  The electrode body 20 (see FIGS. 3 and 4) has a flat shape and is accommodated in the battery case 10 in a state of being laid sideways. A bag-shaped insulating film surrounding body 19 made of an insulating film is arranged between the electrode body 20 and the battery case 10. The electrode body 20 includes a strip-shaped positive electrode plate 21 and a strip-shaped negative electrode plate 31, which are stacked on each other via a pair of separators 41 and 41 made of a resin-made porous film and wound around the axis AX to have a flat shape. It is compressed into.

  The positive electrode plate 21 is provided with a positive electrode active material layer 23 in a band shape at predetermined positions on both main surfaces of a positive electrode current collector foil 22 made of a band-shaped aluminum foil. The positive electrode active material layer 23 includes 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). One end of the positive electrode plate 21 in the width direction (upper end in FIG. 4) does not have the positive electrode active material layer 23 in the thickness direction, and the positive electrode current collector foil 22 is exposed in the thickness direction. The exposed part is 21 m. The positive electrode exposed portion 21m is welded to the positive electrode terminal member 50 described above.

  The negative electrode plate 31 has a negative electrode active material layer 33 provided in a strip shape at predetermined positions on both main surfaces of a negative electrode current collector foil 32 made of a strip copper foil. The negative electrode active material layer 33 includes a negative electrode active material (graphite in this embodiment), a binder (styrene-butadiene rubber in this embodiment), and a thickener (carbomethylmethylcellulose in this embodiment). The other end portion (lower end portion in FIG. 4) of the negative electrode plate 31 in the width direction EH (upper and lower direction in FIG. 4) does not have the negative electrode active material layer 33 in the thickness direction, so The foil 32 is a negative electrode exposed portion 31m exposed in the thickness direction. The negative electrode exposed portion 31m is welded to the negative electrode terminal member 60 described above.

  The negative electrode active material layer 33 is formed to be larger in the width direction EH than the positive electrode active material layer 23 of the positive electrode plate 21. In the state where the negative electrode plate 31 is superposed on the positive electrode plate 21 via the separator 41, both ends of the negative electrode active material layer 33 in the width direction EH are not directly facing the positive electrode active material layer 23. 33b. On the other hand, a portion of the negative electrode active material layer 33 between the non-facing portions 33b and 33b is a facing portion 33a that faces the positive electrode active material layer 23.

  Next, a method for manufacturing the battery 1 will be described (see FIG. 5). First, in the "assembly step S1", the battery 1 is assembled. Specifically, the positive electrode plate 21 and the negative electrode plate 31 are wound on top of each other with the pair of separators 41, 41 interposed therebetween, and compressed into a flat shape to form the electrode body 20 (see FIGS. 4 and 3). Next, the case lid member 13 is prepared, and the positive electrode terminal member 50 and the negative electrode terminal member 60 are fixedly mounted on the case lid member 13 (see FIGS. 1 and 2). Then, 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 surrounding body 19, these are inserted into the case body member 11, and the opening of the case body member 11 is closed with the case lid member 13. Then, the case body member 11 and the case lid member 13 are welded together to form the battery case 10. After that, the electrolytic solution 17 is injected into the battery case 10 through the injection hole 13h to impregnate the inside of the electrode body 20. After that, the sealing member 15 seals the liquid injection hole 13h.

  Next, in the "initial charging step S2", the battery 1 is initially charged. Note that FIG. 6 shows the relationship between the elapsed time Te from the start of the initial charging step S2 and the battery voltage Ve. Specifically, by connecting a charging / discharging device to the battery 1 and charging the battery 1 at a room temperature (25 ± 5 ° C.) with constant current / constant voltage (CCCV), the first battery voltage V1 = 3.55V. To charge. In the present embodiment, after charging the battery voltage Ve with the constant current of 5C until the first battery voltage V1 = 3.55V, the first battery voltage V1 = 3.55V until the charging current value reaches 0.25C. Maintained. The state of charge of the battery 1 at the first battery voltage V1 = 3.55V is SOC 30%.

  Subsequently, in the "discharge step S3", the battery 1 is discharged. Specifically, by using a charging / discharging device connected to the battery 1, the battery voltage Ve becomes the second battery voltage V2 = 3.30V (V2 <V1) at a constant current of 5C by constant current (CC) discharge. Until the battery 1 is discharged. The state of charge of the battery 1 at the second battery voltage V2 = 3.30V is SOC 5%.

  Then, in the "recharging step S4", the battery 1 is charged again. Specifically, using a charging / discharging device connected to the battery 1, at room temperature (25 ± 5 ° C.), the third battery voltage V3 lower than the first battery voltage V1 by constant current constant voltage (CCCV) charging. = Recharge Battery 1 to 3.43V (V2 <V3 <V1). In the present embodiment, after charging the battery voltage Ve with the constant current of 5C until the third battery voltage V3 = 3.43V, the third battery voltage V3 = 3.43V until the charging current value reaches 0.25C. Maintained.

  Subsequently, in the "IV resistance inspection step S5", the IV resistance value Ra of the battery 1 is acquired, and the quality of the battery 1 is determined based on the IV resistance value Ra. Specifically, at the time T (2) at which 2 minutes have elapsed from the end of the recharging step S4 (= the start time To of the IV resistance inspection step S5), the battery 1 is charged with a predetermined current value I (in the present embodiment, I = 3.5 C), and Ta voltage (Ta = 0.0 seconds in this embodiment) and battery voltage Va and Tb seconds (Tb = 4.0 seconds in this embodiment) after the start of this discharge. After that, the battery voltage Vb was measured, and the IV resistance value Ra (2) was calculated by Ra = (Va−Vb) / I. When the IV resistance value Ra (2) is larger than a predetermined reference resistance value Rs (Ra (2)> Rs), the battery 1 is determined to be defective and the battery 1 is removed. On the other hand, when the measured IV resistance value Ra (2) is smaller than the reference resistance value Rs (Ra (2) ≦ Rs), the battery 1 is determined as a good product.

  After the IV resistance inspection step S5, various other inspections are performed on the battery 1. Thus, the battery 1 is completed.

(Examples and comparative examples)
Next, the results of tests conducted to verify the effects of the present invention will be described. As Example 1, the battery 1 was manufactured by the manufacturing method of the above-described embodiment. In the method for manufacturing the battery 1 of the embodiment, as described above, in the initial charging step S2, the battery 1 is charged to the first battery voltage V1 = 3.55V with a constant current of 5 C in the CCCV charging (see also Table 1). ). Then, in the discharging step S3, the battery 1 was discharged by CC discharge to a second battery voltage V2 = 3.30V at a constant current of 5C. Then, in the recharge step S4, the CCCV charge was used to recharge the battery 1 to a third battery voltage V3 = 3.43 V at a constant current of 5 C, and then the IV resistance inspection step S5 was performed.

  Further, as Example 2, in the initial charging step S2, the battery 1 was charged by CCCV charging with a constant current of 2.5 C to the first battery voltage V1 = 3.60 V. Then, in the discharging step S3, the battery 1 was discharged by CC discharge to a second battery voltage V2 = 3.40V at a constant current of 2.5C. Then, in the recharging step S4, the CCCV charging was used to recharge the battery 1 to a third battery voltage V3 = 3.43 V at a constant current of 2.5 C, and then the IV resistance inspection step S5 was performed. Other than that, the battery 1 was manufactured in the same manner as in the embodiment.

  Also, as Example 3, in the initial charging step S2, the battery 1 was charged by CCCV charging with a constant current of 5 C to the first battery voltage V1 = 3.60 V. Then, in the discharging step S3, the battery 1 was discharged by CC discharge to a second battery voltage V2 = 3.40V at a constant current of 2.5C. Then, in the recharging step S4, the CCCV charging was used to recharge the battery 1 to a third battery voltage V3 = 3.43 V at a constant current of 2.5 C, and then the IV resistance inspection step S5 was performed. Other than that, the battery 1 was manufactured in the same manner as in the embodiment.

  Further, as Example 4, in the initial charging step S2, the battery 1 was charged by CCCV charging with a constant current of 5C to the first battery voltage V1 = 3.55V. Then, in the discharging step S3, the battery 1 was discharged by CC discharge to a second battery voltage V2 = 3.40V at a constant current of 5C. Then, in the recharge step S4, the CCCV charge was used to recharge the battery 1 to a third battery voltage V3 = 3.43 V at a constant current of 5 C, and then the IV resistance inspection step S5 was performed. Other than that, the battery 1 was manufactured in the same manner as in the embodiment.

  On the other hand, as a comparative example, Battery 1 was manufactured by the following manufacturing method. That is, in the comparative example, after performing the assembling step S1 as in the embodiment, in the initial charging step S2, CCCV charging was performed at a constant current of 5 C to obtain 3.43 V (third battery voltage V3 in each of Examples 1 to 4). Same as the above), battery 1 was first charged. After that, without performing the discharging step S3 and the recharging step S4, the IV resistance inspection step S5 similar to the embodiment was performed following the initial charging step S2. Note that FIG. 7 shows the relationship between the elapsed time Te from the start of the initial charging step S2 and the battery voltage Ve for this comparative example.

  In addition, in Examples 1 to 4 and Comparative Example, in the IV resistance inspection step S5, as in the embodiment, at a time T (2) when 2 minutes have elapsed from the start time To of the IV resistance inspection step S5, the IV resistance value Ra is increased. In addition to the measurement of (2), the IV resistance value Ra (10) was also measured at time T (10) 10 minutes after the start To of the IV resistance inspection step S5. Furthermore, the rate of resistance change Rh = (| Ra (10) −Ra (2) | / Ra (2)) × 100 (%) between the IV resistance value Ra (2) and the IV resistance value Ra (10) was calculated. .. These results are also shown in Table 1.

  As is clear from Table 1, in the comparative example, the resistance change rate Rh was large and was 44.4%. In other words, in the comparative example, the measurement timing of the IV resistance value Ra is delayed from the time T (2) to the time T (10) by 8 minutes, and the measured IV resistance value Ra is 44.4%. It shows that they are different. Therefore, if the measurement timing of the IV resistance value Ra is missed, the quality of the battery 1 cannot be properly determined.

  On the other hand, in Examples 1 to 4, the resistance change rate Rh was significantly smaller than that in Comparative Example, and was 6.5% or less (0.6% in Example 1, 6.5% in Example 2, and No. 3 is 4.1%, and in Example 4 is 2.9%). That is, in Examples 1 to 4, even if the measurement timing of the IV resistance value Ra was delayed from time T (2) to time T (10) by 8 minutes, the difference in the measured IV resistance value Ra was 6.5. % Or less. Therefore, the quality of the battery 1 can be appropriately determined without strictly managing the measurement timing of the IV resistance value Ra.

  The reason for producing such a result is considered to be as follows. That is, in the comparative example, the battery voltage Ve (both terminals open circuit voltage) after the initial charging step S2 greatly decreases for a long time. This is because the lithium ions inserted into the facing portion 33a of the negative electrode active material layer 33 by the initial charging gradually diffuse into the non-facing portions 33b and 33b of the negative electrode active material layer 33 after the initial charging. Then, as lithium ions escape from the facing portion 33a of the negative electrode active material layer 33, the negative electrode potential of the negative electrode plate 31 increases, and the battery voltage Ve, which is the difference between the positive electrode potential and the negative electrode potential, appears to decrease correspondingly. .. In this way, in the battery 1 of the comparative example, the battery voltage Ve after the initial charging step S2 (after charging to 3.43 V before the IV resistance test) is greatly reduced for a long time. Therefore, it is considered that the measured IV resistance value Ra greatly differs only when the measurement timing of the IV resistance value Ra is delayed from the time T (2) to the time T (10) by 8 minutes.

  On the other hand, in Examples 1 to 4, once in the initial charging step S2, initial charging is performed to the first battery voltage V1 (3.55V or 3.60V) higher than the third battery voltage V3 = 3.43V. Therefore, as compared with the comparative example in which the third battery voltage V3 = 3.43 V is charged in the initial charging step S2, a large amount of lithium ions are once inserted into the facing portion 33a of the negative electrode active material layer 33, which is accompanied by this. As a result, many lithium ions diffuse into the non-facing portion 33b. Then, in this state, the discharging step S3 and the recharging step S4 are performed to adjust the battery voltage Ve to the third battery voltage V3 = 3.43V, so at the end of the recharging step S4 (= the IV resistance inspection step S5 At the start time To), more lithium ions are present in the non-facing portion 33b than at the end of the initial charging step S2 (= start time To of the IV resistance inspection step S5) in the comparative example.

  Therefore, compared to after the initial charging step S2 of the comparative example, the diffusion of lithium ions from the facing portion 33a to the non-facing portion 33b after the recharging step S4 is suppressed, and the negative electrode potential increases accordingly. It is possible to prevent the battery voltage Ve from decreasing. Thus, as compared with the comparative example in which the discharge step S3 and the recharge step S4 are not provided and the IV resistance inspection step S5 is performed after the initial charge step S2, after the recharge step S4 (3.43V before the IV resistance inspection). (After charging up to), the decrease in the battery voltage Ve becomes small. Therefore, it is considered that even if the measurement timing of the IV resistance value Ra is delayed from the time T (2) to the time T (10) by 8 minutes, the measured IV resistance value Ra does not differ much.

  The reason why the resistance change rate Rh was larger in Example 2 than in Example 1 is considered to be due to the following reason. That is, the first battery voltage V1 = 3.60V in the initial charging step S2 of the second embodiment is higher than the first battery voltage V1 = 3.55V of the first embodiment, and the third battery voltage before the IV resistance inspection step S5. The voltage difference with V3 = 3.43V is larger in Example 2 (3.60-3.43 = 0.17V) than in Example 1 (3.55-3.43 = 0.12V). .. In this way, when the voltage difference between the first battery voltage V1 and the third battery voltage V3 is too large, the change in the battery voltage Ve after adjusting to the third battery voltage V3 becomes large. Therefore, it is considered that the resistance change rate Rh in Example 2 was larger than that in Example 1.

  The reason why the resistance change rate Rh was smaller in Example 3 than in Example 2 is considered to be due to the following reasons. That is, since the charging current value = 5C in the initial charging step S2 of Example 3 is larger than the charging current value = 2.5C of Example 2, the battery voltage Ve measured at the end of the initial charging step S2 is shown in Table 1. As shown in, even if the first battery voltage V1 is equal to 3.60 V, the actual battery voltage is lower in the third embodiment than in the second embodiment. Therefore, the voltage difference between the third battery voltage V3 before the IV resistance inspection step S5 and 3.43 V is smaller in the third embodiment than in the second embodiment. As described above, in the third embodiment, since the voltage difference between the first battery voltage V1 and the third battery voltage V3 is not too large as in the second embodiment, the change in the battery voltage Ve after adjusting to the third battery voltage V3 is small. .. As a result, it is considered that the resistance change rate Rh of Example 3 was smaller than that of Example 2.

The reason why the resistance change rate Rh was smaller in Example 4 than in Example 3 is considered to be as follows. That is, the first battery voltage V1 = 3.55V in the initial charging step S2 of the fourth embodiment is lower than the first battery voltage V1 = 3.60V of the third embodiment, and the third battery voltage before the IV resistance inspection step S5. The voltage difference with V3 = 3.43V is smaller in Example 4 (3.55-3.43 = 0.12V) than in Example 3 (3.60-3.43 = 0.17V). .. As described above, in the fourth embodiment, since the voltage difference between the first battery voltage V1 and the third battery voltage V3 is not too large, the change in the battery voltage Ve after adjusting to the third battery voltage V3 is small. As a result, it is considered that the resistance change rate Rh of Example 4 was smaller than that of Example 3.
From the results of Examples 1 to 4, when the voltage difference between the first battery voltage V1 and the third battery voltage V3 is too large, the resistance change rate Rh increases, so the voltage difference from the third battery voltage V3 is considered. Then, it is preferable to set the value of the first battery voltage V1.

On the other hand, it is considered that the reason why the resistance change rate Rh was larger in Example 4 than in Example 1 is as follows. The second battery voltage V2 = 3.40V in the discharging step S3 of the fourth embodiment is higher than the second battery voltage V2 = 3.30V of the first embodiment, and the third battery voltage V3 = 3 before the IV resistance inspection step S5. The difference from 0.43V is too small (only 0.03V). Therefore, in Example 4, it is difficult to obtain the effect of once reducing the battery voltage Ve in the discharging step S3, and it is considered that the rate of resistance change Rh in Example 4 was larger than that in Example 1.
From the results of Examples 1 and 4, if the voltage difference between the second battery voltage V2 and the third battery voltage V3 is too small, the rate of change in resistance Rh increases, so the voltage difference from the third battery voltage V3 is taken into consideration. It is preferable to set the value of the second battery voltage V2.

  As described above, in the manufacturing method of the battery 1, after the initial charging step S2, the discharging step S3 and the recharging step S4 are performed, and then the IV resistance inspection step S5 is performed. By doing so, the decrease in the battery voltage Ve after the recharging step S4 is caused by the battery voltage after the initial charging step S2 in the case where the IV resistance inspection step S5 is performed after the initial charging step S2 (the above-described comparative example). It becomes smaller than the decrease in Ve. For this reason, even if the measurement timing of the IV resistance value Ra deviates from the reference timing for some reason, the difference in the IV resistance values Ra obtained is subjected to the IV resistance inspection step S5 subsequent to the initial charging step S2. It can be made smaller than (Comparative example). Therefore, it is not necessary to strictly manage the measurement timing of the IV resistance value Ra, and the IV resistance value Ra can be appropriately measured. In addition, in the method of manufacturing the battery 1, since the decrease in the battery voltage Ve after the recharging step S4 is small, it is not necessary to leave the battery 1 for a long time until the battery voltage Ve becomes stable. Therefore, the period from the end of the initial charging step S2 to the measurement of the IV resistance value Ra can be shortened.

  Although the present invention has been described above according to the embodiments, it goes without saying that the present invention is not limited to the above-described embodiments and can be appropriately modified and applied without departing from the scope of the invention.

DESCRIPTION OF SYMBOLS 1 Battery 10 Battery case 20 Electrode body 21 Positive electrode plate 23 Positive electrode active material layer 31 Negative electrode plate 33 Negative electrode active material layer 33a (Negative electrode active material layer) facing portion 33b (Negative electrode active material layer) non-facing portion 41 Separator S1 Assembly step S2 Initial charging step S3 Discharging step S4 Recharging step S5 IV resistance inspection step Ve Battery voltage V1 First battery voltage V2 Second battery voltage V3 Third battery voltage Ra, Ra (2), Ra (10) IV resistance value

Claims (1)

An electrode body in which a positive electrode plate and a negative electrode plate are stacked via a separator, and an electrolytic solution impregnated in the electrode body are provided,
The negative electrode active material layer of the negative electrode plate is a method for producing a battery, which includes a facing portion that faces the positive electrode active material layer of the positive electrode plate and a non-facing portion that does not face the positive electrode active material layer. ,
An initial charging step of initially charging the battery to a first battery voltage V1 at room temperature (25 ± 5 ° C.) ;
Following the initial charging step , a discharging step of discharging the battery to a second battery voltage V2,
Following the discharging step , a recharging step of recharging the battery to a third battery voltage V3 (V2 <V3 <V1) lower than the first battery voltage V1 at room temperature (25 ± 5 ° C.) ,
After the recharging step, the IV resistance value Ra of the battery is acquired, and an IV resistance inspection step of judging whether the battery is good or bad based on the IV resistance value Ra.

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