Manufacturing method of non-aqueous electrolyte secondary battery

Abstract

This invention provides a method for manufacturing a non-aqueous electrolyte secondary battery that suppresses the amount of high-pressure gas used. [Solution] A manufacturing method for a non-aqueous electrolyte secondary battery, comprising inserting an electrode body, constructed by laminating a positive electrode plate and a negative electrode plate with a separator in between, into a case, and then injecting an electrolyte to impregnate the electrode body, wherein the manufacturing method includes a pressurization step in which the inside of the cell into which the electrode body has been inserted and the electrolyte has been injected is subjected to a high-pressure state to pressurize the cell, and the pressurization step ends when the integral value obtained by integrating the pressurizing force over the pressurizing time from the start of pressurization reaches or exceeds a target value of the integral value that indicates a good state of electrolyte impregnation of the electrode body.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a non-aqueous electrolyte secondary battery in which an electrode body formed by laminating a positive electrode plate and a negative electrode plate with a separator interposed therebetween is inserted into a case, and then a non-aqueous electrolyte is injected and impregnated into the electrode body.

Background Art

[0002] A non-aqueous electrolyte secondary battery such as a lithium-ion secondary battery includes an electrode body in which a positive electrode, a negative electrode, and a separator are laminated, and a case that houses the electrode body. The non-aqueous electrolyte secondary battery is configured by impregnating the electrode body with a non-aqueous electrolyte in a state where the electrode body is housed in the case.

[0003] As a manufacturing method for impregnating the electrode body housed in the case with an electrolyte, there is a manufacturing method as described in Patent Document 1. In Patent Document 1, after the electrode body is housed in the case, the pressure is reduced to a low pressure lower than the normal pressure and held for a certain period of time, and the pressure is increased to a high pressure higher than the normal pressure and held for a certain period of time are repeated to impregnate the electrode body with the electrolyte.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Incidentally, in order to impregnate the electrode body with electrolyte, a pressurized environment is created by injecting a high-pressure gas such as nitrogen gas while the cell containing the electrode body is placed inside the chamber. A large amount of high-pressure gas is consumed when pressurizing to create the pressurized environment. Therefore, if the supply of high-pressure gas exceeds the supply capacity of the gas supply equipment during mass production of non-aqueous electrolyte secondary batteries of the same type, there is a risk of insufficient pressure being applied inside the chamber. In such cases, the impregnation of the electrode body with electrolyte will be insufficient. [Means for solving the problem]

[0006] A method for manufacturing a non-aqueous electrolyte secondary battery to solve the above problems is a method for manufacturing a non-aqueous electrolyte secondary battery which involves inserting an electrode body, which is constructed by stacking a positive electrode plate and a negative electrode plate with a separator in between, into a case, and then pouring an electrolyte into the electrode body to impregnate it, and the method comprises a pressurization step in which a pressurization process is performed by making the inside of the case, into which the electrode body has been inserted and the electrolyte has been poured, into a high-pressure state, thereby pressurizing the electrode body with the electrolyte, and the pressurization step is terminated when the integral value obtained by integrating the pressurizing force over the pressurizing time from the start of pressurization becomes equal to or greater than a target value of the integral value in which the impregnation state of the electrolyte into the electrode body is good.

[0007] The above configuration is based on the finding that, in the pressure impregnation process, if the integral value obtained by integrating the pressure force with the pressure time is approximately the same, the state of electrolyte impregnation in the electrode body will be approximately the same even if the pressure and pressure time are changed. As an example, when the impregnation state is good with the first pressure and first pressure time, the integral value obtained by integrating the first pressure force with the first pressure time is set as the target value. In this case, by making the second pressure force smaller than the first pressure and the second pressure time longer than the first pressure time, the integral value can be made to be greater than or equal to the target value, thereby improving the impregnation state. Through such adjustments, in mass production equipment, it becomes possible to impregnate the electrode body with electrolyte by creating a high-pressure state in the pressurized tank using an amount of high-pressure gas corresponding to the supply capacity of the high-pressure gas supply equipment that supplies high-pressure gas.

[0008] In the above method for manufacturing a non-aqueous electrolyte secondary battery, it is preferable to set the pressurization time so that it is equal to or greater than the target value within a range less than or equal to the set pressurization pressure. With the above configuration, for example, when the pressurization force is set to a second pressurization pressure that is smaller than the first pressurization pressure, the pressurization time is set to a second pressurization time that is longer than the first pressurization time. This makes it possible to suppress the amount of high-pressure gas used to fill the pressurization tank.

[0009] In the above method for manufacturing a non-aqueous electrolyte secondary battery, it is preferable that the pressurization process is performed only once in the pressurization impregnation step. With this configuration, by performing the pressurization process only once, the amount of high-pressure gas used to fill the pressurized tank can be reduced compared to when it is performed multiple times.

[0010] In the above method for manufacturing a non-aqueous electrolyte secondary battery, it is preferable that the pressurization process is performed multiple times in the pressurization impregnation step. With this configuration, the integral value can be brought closer to the target value in stages.

[0011] In the above method for manufacturing a non-aqueous electrolyte secondary battery, the set pressure is preferably 0.4 MPa or less. With the above configuration, it is possible to suppress the addition of gas boosting equipment such as booster tanks and buffer tanks in the high-pressure gas supply equipment.

[0012] In the above method for manufacturing a non-aqueous electrolyte secondary battery, it is preferable that the pressurizing impregnation step adjusts the pressurizing pressure and pressurizing time so that the integral value approaches the target value when the integral value is greater than or equal to the target value. According to the above configuration, when the integral value is large relative to the target value, the pressurizing pressure and pressurizing time are adjusted so that the integral value approaches the target value. For example, the pressurizing force is reduced and / or the pressurizing time is shortened. This makes it possible to suppress the amount of high-pressure gas injected into the pressurizing tank.

[0013] In the above method for manufacturing a non-aqueous electrolyte secondary battery, it is preferable that the electrolyte be injected under vacuum. With this configuration, the differential pressure between the pressure applied during electrolyte injection and the pressure applied during pressurization becomes large, which can promote the impregnation of the electrolyte.

Advantages of the Invention

[0014] According to the present invention, it is possible to provide a method for manufacturing a non-aqueous electrolyte secondary battery that enables suppression of the amount of high-pressure gas used.

Brief Description of the Drawings

[0015] [Figure 1] FIG. 1 is a perspective view of a non-aqueous electrolyte secondary battery. [Figure 2] FIG. 2 is a perspective view of an electrode body. [Figure 3] FIG. 3 is a side view of a non-aqueous electrolyte secondary battery. [Figure 4] FIG. 4 is a process diagram for explaining the process of pressure-impregnating an electrode body with an electrolyte. [Figure 5] FIG. 5 is a diagram for explaining the definitions of the applied pressure, the pressurization time, the pressure holding time, and the integral value. [Figure 6] FIG. 6 is a diagram for explaining a plurality of examples in which the applied pressure and the pressurization time are made different while making the integral value obtained by integrating the applied pressure with respect to the pressurization time from the start of pressurization the same. [Figure 7] FIG. 7 is a diagram showing the relationships among the integral value obtained by integrating the applied pressure with respect to the pressurization time from the start of pressurization, the pressurization time, the applied pressure, the number of pressurizations, the pressure holding time, the pressurization flow rate, the amount of high-pressure gas used, and the impregnation state. [Figure 8] FIG. 8(a) is a diagram showing the relationship between the pressurization time and the applied pressure of Sample 2, FIG. 8(b) is a diagram showing the relationship between the pressurization time and the applied pressure of Sample 3, and FIG. 8(c) is a diagram showing the relationship between the pressurization time and the applied pressure of Sample 4. [Figure 9] FIG. 9 is a diagram for explaining a high-pressure gas supply facility. [Figure 10] FIG. 10 is a process diagram for explaining the details of the pressure-impregnation process. [Figure 11] FIG. 11 is a process diagram for explaining another example of the pressure-impregnation process.

Embodiments for Carrying Out the Invention

[0016] Hereinafter, a non-aqueous electrolyte secondary battery to which the present invention is applied will be described with reference to the drawings. 〔Overall Configuration〕 As shown in FIGS. 1 and 2, the non-aqueous electrolyte secondary battery 1 (hereinafter, also simply referred to as "secondary battery 1") is a lithium-ion secondary battery and is a cell battery. The non-aqueous electrolyte secondary battery 1 includes an electrode body 10 in which a positive electrode plate 3, a negative electrode plate 4, and a separator 5 are integrated, and a case 20 that houses the electrode body 10. And the secondary battery 1 of the present embodiment has a configuration as a lithium-ion secondary battery in which the electrode body 10 in the case 20 is impregnated with a non-aqueous electrolyte (not shown).

[0017] In the secondary battery 1, the positive electrode plate 3, the negative electrode plate 4, and the separator 5 have a sheet-like outer shape and are laminated. And by winding the laminate of these positive electrode plate 3, negative electrode plate 4, and separator 5, an electrode body 10 is configured in which the positive and negative electrodes and the separator 5 are alternately arranged in the radial direction with the separator 5 sandwiched between the positive electrode plate 3 and the negative electrode plate 4.

[0018] The case 20 includes a flat substantially rectangular box-shaped case body 21 and a lid member 22 that closes the open end 21x of the case body 21. The electrode body 10 has a flat outer shape corresponding to the box shape of the case 20. ]

[0019] (Electrode Sheet and Electrode Body) The positive electrode plate 3 and the negative electrode plate 4 are each configured as an electrode sheet 35. The positive electrode plate 3 and the negative electrode plate 4 each include a current collector foil 31 having a sheet-like outer shape and an electrode active material layer 32 laminated on the current collector foil 31. Specifically, the electrode sheet 35P for the positive electrode plate 3 includes a current collector foil 31P as a base material made of aluminum or the like, and a positive electrode active material layer 32P containing a lithium transition metal oxide that is a positive electrode active material laminated on the current collector foil 31P. The electrode sheet 35N for the negative electrode plate 4 includes a current collector foil 31N as a base material made of copper or the like, and a negative electrode active material layer 32N laminated on the current collector foil 31N.

[0020] Furthermore, these positive and negative electrode sheets 35P and 35N are each shaped into strips. The electrode body 10 is a wound body in which the positive and negative electrode sheets 35P and 35N, which are stacked with a separator 5 in between, are wound around a winding axis 10x that extends in the width direction (left-right direction in Figure 2) of its strip shape.

[0021] In Figure 2, the separator 5 and each electrode sheet 35 are wound in such a way that the electrode sheet 35P constituting the positive electrode plate 3 is wound inward. However, this figure is just one example of the structure of the electrode body 10, and in some cases, the separator 5 and each electrode sheet 35 may be wound in such a way that the electrode sheet 35N constituting the negative electrode plate 4 is wound inward.

[0022] The lid member 22 of the case 20 is provided with a positive electrode terminal 38P and a negative electrode terminal 38N that protrude to the outside of the case 20. Furthermore, each electrode sheet 35 has an uncoated portion 39 on the current collector foil 31 where the electrode active material layer 32 is not formed. The secondary battery 1 uses these uncoated portions 39 to electrically connect the electrode sheet 35P and the positive electrode terminal 38P that constitute the positive electrode plate 3, and to electrically connect the electrode sheet 35N and the negative electrode terminal 38N that constitute the negative electrode plate 4.

[0023] As shown in Figure 3, the electrode body 10 is inserted and housed in the case 20 with its winding axis 10x aligned along the longitudinal direction (left-right direction in Figure 1) of the lid member 22, which is a long, roughly rectangular plate. Furthermore, in this state, the unpainted portion 39P (see Figure 2) of the electrode sheet 35P constituting the positive electrode plate 3 and the positive electrode terminal 38P are connected via a connecting member 40P. Similarly, the unpainted portion 39N (see Figure 2) of the electrode sheet 35N constituting the negative electrode plate 4 and the negative electrode terminal 38N are connected via a connecting member 40N.

[0024] An electrolyte 45 is injected into the case 20. Specifically, the electrolyte 45 of the secondary battery 1, which has the configuration of a lithium-ion secondary battery, is made by dissolving a lithium salt, which acts as a support salt, in an organic solvent. The electrolyte 45 is injected using an injection hole (not shown) provided in the lid member 22. The electrolyte 45 then impregnates the electrode body 10, which is sealed inside the case 20, into the secondary battery 1.

[0025] As shown in Figure 4, in order to impregnate the electrode body 10 inside the case 20 with the electrolyte 45, the secondary battery 1 is placed in the pressure adjustment chamber before the electrolyte 45 is impregnated into the electrode body 10 inside the case 20 (step S1). Next, the pressure adjustment chamber in which the secondary battery 1 is placed is evacuated. Specifically, the pressure adjustment chamber is reduced to below atmospheric pressure, thereby placing the secondary battery 1 in a reduced-pressure environment. Next, in this reduced-pressure environment, the electrolyte 45 is poured into the case 20 of the secondary battery 1 (step S2). After the completion of the pouring process in step S2, the pressure adjustment chamber is pressurized by injecting a high-pressure gas such as nitrogen (N2) gas. After this, the pressurized state is maintained for a predetermined time to pressurize and impregnate the electrode body 10 with the electrolyte 45 (step S3). Once the electrode body 10 is impregnated with the electrolyte 45, the pressure adjustment chamber is opened to atmospheric pressure. Furthermore, after this, the process of opening the pressure adjustment chamber to atmospheric pressure and then injecting high-pressure gas back into the pressure adjustment chamber to pressurize it may be repeated once or multiple times.

[0026] In a secondary battery 1 impregnated with electrolyte 45, the internal resistance decreases as the electrolyte 45 penetrates the electrode body 10 further. By measuring the internal resistance of the secondary battery 1, it is possible to determine whether the electrolyte 45 has sufficiently penetrated the electrode body 10 housed in the case 20. The internal resistance is measured, for example, by an AC-IR measuring device. The AC-IR measuring device applies a measurement current with a predetermined frequency (e.g., 1 kHz) to the positive terminal 38P and negative terminal 38N of the secondary battery 1, and the internal resistance of the secondary battery 1 can be determined from the voltage value of the AC voltmeter. When the measured internal resistance value stabilizes (when the fluctuation range of the internal resistance becomes below a threshold), it can be determined that the electrolyte 45 has been sufficiently penetrated. Alternatively, it may be determined that the electrolyte 45 has been sufficiently penetrated when the magnitude of the internal resistance value becomes below a threshold.

[0027] (Regarding the integral value obtained by integrating the applied force with respect to the applied time) As described above, in the secondary battery 1, high-pressure gas is injected into the pressure adjustment chamber to impregnate the electrode body 10 with electrolyte 45. This embodiment is based on the finding that if the integral value obtained by integrating the pressurizing force by the high-pressure gas over the pressurizing time from the start of pressurization is approximately the same, the impregnation state of the electrolyte 45 in the electrode body 10 will be approximately the same even if the pressurizing force and pressurizing time are changed.

[0028] As shown in Figure 5, when the horizontal axis represents the pressurization time (total time) from the start of pressurization and the vertical axis represents the applied pressure, the integral value here is the integral value (area) of the function (pressurization characteristic line 50) that shows the change in applied pressure over time. The integral value is also the sum of the applied pressure per unit time.

[0029] For example, Figure 6 shows the relationship between pressurization time and pressurization time when pressurization is performed once. Pressurization characteristic line 51 shows the case where the pressurization pressure is 0.8 MPa and the pressurization time is held for 250 seconds. Pressurization characteristic line 52 shows the case where the pressurization pressure is 0.4 MPa and the pressurization time is held for 500 seconds. Pressurization characteristic line 53 shows the case where the pressurization pressure is 0.2 MPa and the pressurization time is held for 1000 seconds. In all cases of pressurization characteristic lines 51 to 53, the same electrode body 10 and electrolyte 45 are used to keep the conditions the same, while the pressurization pressure and pressurization time in the pressurization impregnation process are changed.

[0030] In all cases of the pressurization characteristic curves 51 to 53, the integral values ​​are the same or nearly the same, indicating that the impregnation state is good in all cases. Furthermore, it can be confirmed that if the number of pressurization cycles is the same (1 cycle in this case), lowering the pressurization force increases the pressurization time, and increasing the pressurization force shortens the pressurization time.

[0031] Figure 7 shows the relationship between the integral value, the pressurizing time from the start of pressurizing, the applied pressure, the number of pressurizing cycles, the pressurizing holding time at which the pressurizing force becomes constant, the pressurizing flow rate from the start of pressurizing, the amount of high-pressure gas used during the pressurizing time, and the impregnation state.

[0032] Sample 1 has an integral value of 231, with a pressurization time (total time) of 11 minutes, a pressurizing force of 0.4 MPa, and one pressurization cycle. The pressurization holding time was 500 seconds, and the pressurization flow rate was 12 Pa·m³. 3 Setting it to / s results in a high-pressure gas usage of 18L. In this case, the impregnation state is good (○). The impregnation state is considered good (○) when the change in internal resistance measured by the AC-IR measuring device described above is below the threshold and the state is stable.

[0033] Sample 2 has an integral value of 207, which is almost the same as Sample 1. Sample 2 uses a pressurized flow rate of 467 Pa·m 3 By setting the pressure to / s and increasing it compared to Sample 1, the pressurization time was shortened to 9 minutes, and the pressurization holding time was set to 500 seconds. In this case, the amount of high-pressure gas used was 18L. The impregnation state is good (〇). Figure 8(a) shows the pressurization characteristic curve that shows the relationship between the pressurized pressure and the pressurization time for Sample 2.

[0034] Sample 3 uses an integral value of 162, which is smaller than that of Sample 1. Furthermore, the pressurization time is shortened to 7 minutes compared to Sample 1, and the number of pressurization cycles is increased to 30, significantly more than in Samples 1 and 2. Additionally, the pressurization holding time is 3 seconds, and the pressurized flow rate is 700 Pa·m. 3 The pressure is / s. In this case, the amount of high-pressure gas used is 945L. In this case as well, the impregnation state is good (○). In sample 3, the amount of high-pressure gas used is significantly higher compared to samples 1 and 2, although the impregnation state is good (○), due to factors such as increasing the pressurizing force to 0.8MPa compared to 0.4MPa in samples 1 and 2, and significantly increasing the number of pressurizing cycles to 30 compared to 1 in samples 1 and 2. Figure 8(b) shows the pressurizing characteristic curve for sample 3, which shows the relationship between pressurizing force and pressurizing time.

[0035] Sample 4 uses an integral value of 192, a pressurization time of 12 minutes, a pressurizing force of 0.4 MPa, and 4 pressurization cycles. Additionally, the pressurization holding time is 60 seconds, and the pressurization flow rate is 12 Pa·m³. 3 By setting the pressure rate to / s, the amount of high-pressure gas used is set to 70L. In this case as well, the impregnation state is good (○). Figure 8(c) shows the pressure characteristic curve that illustrates the relationship between the pressure applied and the pressurizing time for sample 4.

[0036] Sample 5 has an integral value of 195, which is almost the same as Sample 4. Compared to Sample 4, Sample 5 had the number of pressurization cycles increased from 4 to 7, and the pressurization holding time shortened to 3 seconds. The amount of high-pressure gas used increased from 70L to 123L due to the increased number of pressurization cycles. In this case as well, the impregnation state is good (〇).

[0037] Sample 6 uses an integral value of 140, a pressurization time of 10 minutes, a pressurizing force of 0.4 MPa, and 5 pressurization cycles. Additionally, the pressurization holding time is 3 seconds, and the pressurization flow rate is 12 Pa·m³. 3 By setting it to / s, the amount of high-pressure gas used is assumed to be 88L. In Sample 6, the integral value is too low, and the impregnation state is poor (×).

[0038] Sample 7 has an integral value of 144, which is almost the same as Sample 6's integral value of 140. In Sample 7, the number of pressurization cycles was reduced from 5 to 4. Even in Sample 7, the integral value is too low, and the impregnation state is poor (×).

[0039] According to samples 1-5, if the integral value is 162 or higher than that of sample 3, it can be confirmed that the impregnation state is good (〇). Furthermore, the comparison of Sample 4 with respect to Sample 5, and Samples 1 and 2 with respect to Samples 4 and 5, confirms that reducing the number of pressurization cycles reduces the amount of high-pressure gas used. Additionally, as seen in Samples 1 and 2, limiting pressurization to a single cycle significantly reduces high-pressure gas usage compared to multiple cycles.

[0040] Furthermore, increasing the pressurized flow rate shortens the time from the start of pressurization until the pressurized force stabilizes. As a result, it can be confirmed that the pressurization time for the entire pressurized impregnation process can be shortened. (High-pressure gas supply equipment that supplies high-pressure gas) Figure 9 is a diagram illustrating a high-pressure gas supply equipment 60 for supplying high-pressure N2 gas.

[0041] The high-pressure gas supply equipment 60 comprises a gas generator 61, a booster 62, a buffer tank 63, and a pressurized tank 64. The gas generator 61 generates N2 gas for use as pressurized gas. The booster 62 increases the pressure of the N2 gas generated by the gas generator 61 to produce high-pressure gas. The buffer tank 63 temporarily stores the high-pressure gas. The pressurized tank 64 houses the secondary battery 1 that is subjected to pressure impregnation treatment, and is supplied with gas.

[0042] The gas generator 61 generates N2 gas and supplies it to the booster 62 at a pressure of 0.5 MPa. The booster 62 increases the pressure of the N2 gas to 0.95 MPa and supplies it to the pressurized tank 64 through the buffer tank 63. The pressurized tank 64 is configured as a pressure adjustment chamber where a secondary battery 1 is placed to pressurize and impregnate the electrode body 10 with electrolyte 45. The pressurized tank 64 is supplied with N2 gas from the gas generator 61 and adjusted to a predetermined pressure.

[0043] For example, to set the pressurization force in the pressurization tank 64 to 0.8 MPa, approximately 32 L of high-pressure gas needs to be supplied from the buffer tank 63. However, if the pressurization force is set to approximately 0.4 MPa, the amount of high-pressure gas supplied from the buffer tank 63 can be reduced to approximately 18 L. Furthermore, if the pressurization force in the pressurization tank 64 is set to approximately 0.2 MPa, the amount of high-pressure gas supplied from the buffer tank 63 can be reduced to approximately 11 L. In this way, the lower the pressurization force in the pressurization tank 64 is set, the more high-pressure gas can be consumed.

[0044] In the high-pressure gas supply equipment 60, when impregnating the electrode body 10 with electrolyte 45 under pressure, if the pressurization force is set to 0.5 MPa or higher, the amount of high-pressure gas used will increase, which may necessitate the addition of a booster 62 and a buffer tank 63, for example. Also, the pressurized tank 64 may need to be modified from a commercially available product to improve its pressure resistance. For this reason, it is preferable to suppress the amount of high-pressure gas used when impregnating the electrode body 10 with electrolyte 45 under high pressure. For example, by setting the amount of high-pressure gas used to less than 0.5 MPa, preferably 0.4 MPa or less, the addition of booster 62 and buffer tank 63 and the modification of pressurized tank 64 can be suppressed. Samples 1, 2, 4, and 5 have a pressurization force of 0.4 MPa, which is lower than that of sample 3 with a pressurization force of 0.8 MPa, so the amount of high-pressure gas used can be suppressed (see Figure 7).

[0045] (Pressure impregnation process) In the mass production process of secondary battery 1, a target integral value is set. First, the target value is calculated by measuring the pressurizing force at predetermined elapsed times from the start of pressurization using a data logger and calculating the integral value. At the same time, the internal resistance of secondary battery 1 is measured and the integral value at which the impregnation state of the electrolyte 45 in the electrode body 10 is good is calculated. Based on this integral value, a target value for the integral value is set. Then, from the viewpoint of production efficiency and production costs due to the amount of high-pressure gas used, the pressurizing force, pressurizing flow rate, pressurizing time, etc. are set to be equal to or greater than the set target value.

[0046] Here, the control device that controls the process of pressurizing the electrode body 10 with electrolyte 45 includes a memory that stores a program for managing the pressurized impregnation process, and a control unit that performs calculations according to the program. The control device can set the pressure applied, the flow rate, the pressurizing time, etc. for pressurized impregnation, as well as a target value for the integral value, etc. It is also connected to an AC-IR measuring device, and the internal resistance is input to determine whether the impregnation state is satisfactory or not.

[0047] From the viewpoint of suppressing an increase in the amount of high-pressure gas used, the target value of the integral should be as small as possible among the integral values ​​that result in good impregnation of the electrode body 10 with the electrolyte 45. For example, the control device sets the target value based on the integral value of 162 in sample 3, which has the smallest integral value among samples 1 to 5. The target value may be, for example, 162, which is the integral value of sample 3, or it may be a higher value (for example, 200). However, from the viewpoint of suppressing an increase in the amount of high-pressure gas used, a target value close to 162 in sample 3 is preferable.

[0048] The control device also measures the elapsed time since the start of pressurization. It also controls the opening of valves that control the supply of N2 gas from the gas generator 61 to the pressurized tank 64, and valves that control the supply of high-pressure N2 gas from the buffer tank 63 to the pressurized tank 64. Furthermore, the control device is equipped with a data logger to monitor and record real-time data such as the pressurized pressure. It then calculates the integral value of the secondary battery 1 in which the electrolyte 45 is pressurized and impregnated into the electrode body 10.

[0049] (Example 1) First, we will explain the case where the number of pressurization cycles that have the greatest effect in reducing the amount of high-pressure N2 gas used is set to 1 (see Samples 1 and 2). In this case, as shown in Figure 10, the secondary battery 1 is placed in the pressurizing tank 64 of the pressure adjustment chamber, and in a reduced-pressure environment, the electrolyte 45 is poured into the case 20 of the secondary battery 1, and then the pressurizing process to impregnate the electrode body 10 with the electrolyte 45 is started (step S11). That is, the supply of gas to the pressurizing tank 64 is started at the set pressurizing flow rate. Specifically, gas is supplied to the pressurizing tank 64 at the set pressurizing flow rate to pressurize the case 20 into a high-pressure state. The control device then calculates the integral value in real time or at predetermined intervals (step S13). As an example, the integral value is calculated as follows (see Figure 8(a)).

[0050] Integral value A = Applied pressure P × (Pressure holding time Tm + Pressurization time Tp) ÷ 2 The control device then determines whether the calculated integral value is equal to or greater than the target value (step S13). If the calculated integral value is equal to or greater than the target value, the control device terminates the pressurized impregnation process. If the calculated integral value is less than the target value, the process from step S11 is repeated. In this way, by performing the pressurized process only once, the amount of high-pressure gas used to fill the pressurized tank 64 can be reduced compared to when the pressurized impregnation process is performed multiple times.

[0051] Furthermore, the control device may measure the internal resistance of the secondary battery 1 and determine the impregnation state of the electrolyte 45 when the calculated integral value is equal to or greater than the target value. If the impregnation state is good, the process may be terminated. If the impregnation state is poor, the process may be terminated, indicating that the secondary battery 1 is defective.

[0052] (Example 2) Next, we will explain the case where the pressurization is performed a predetermined number of times (see Samples 4 and 5). In this case, the applied pressure, pressurization flow rate, and pressurization time are set for each pressurization process. Here, the conditions for each pressurization process may be the same or different, but here we will explain them as being the same.

[0053] Then, as shown in Figure 11, the secondary battery 1 is placed in the pressurized tank 64 of the pressure adjustment chamber, and in a reduced pressure environment, the electrolyte 45 is poured into the case 20 of the secondary battery 1, and then the first pressurization process is started to impregnate the electrode body 10 with the electrolyte 45 for the first time. Specifically, high-pressure gas is supplied to the pressurized tank 64 at a set pressurized flow rate, and the inside of the case 20 is pressurized at a set pressure for a set pressurization time. Next, the control device releases to atmospheric pressure when the set pressurization time has elapsed (step S21). Next, the control device calculates the first integral value (A1) (step S22). As an example, the integral value is calculated as follows (see Figure 8(c)).

[0054] First integral value A1 = applied pressure P1 × (pressure holding time Tm1 + pressurization time Tp2 (from pressurization start to completion of release to atmosphere)) ÷ 2 Next, the control device determines whether the integral value (A1) of the first pressurization treatment is equal to or greater than the target value (step S23). If the integral value (A1) of the first pressurization treatment is equal to or greater than the target value, the control device terminates the pressurization impregnation treatment. If the calculated integral value (A1) is less than the target value, the control device performs a second pressurization treatment (step S24) and calculates the integral value (A2) of the second pressurization treatment (step S25).

[0055] Second integral value A2 = applied pressure P2 × (pressure holding time Tm2 + pressurization time Tp2 (from pressurization start to completion of release to atmosphere)) ÷ 2 The control device then adds the integral value of the second pressurizing process (A2) to the integral value of the first pressurizing process (A1) (step S26). The control device determines whether the added integral value (A1+A2) is equal to or greater than the target value (step S27). If the added integral value (A1+A2) is equal to or greater than the target value, the control device terminates the pressurized impregnation process. If the added integral value (A1+A2) is less than the target value, the control device performs a third pressurizing process and calculates the integral value of the third pressurizing process (A3).

[0056] Third integral value A3 = applied pressure P3 × (pressure holding time Tm3 + pressurization time Tp3 (from pressurization start to completion of release to atmosphere)) ÷ 2 Next, the control device adds the integral value (A3) from the third pressurization treatment to the integral value (A1+A2) from the previous treatment. The control device determines whether the added integral value (A1+A2+A3) is equal to or greater than the target value. If the added integral value (A1+A2+A3) is equal to or greater than the target value, the control device terminates the pressurization impregnation treatment. If the added integral value (A1+A2+A3) is less than the target value, the fourth pressurization treatment is performed. In this way, the control device repeats the process from step S24 to step S27 until the sum of the integral values ​​is equal to or greater than the target value. This allows the integral value to gradually approach the target value during the pressurization impregnation process.

[0057] Furthermore, the control device may measure the internal resistance of the secondary battery 1 and determine the impregnation state of the electrolyte 45 when the calculated integral value is equal to or greater than the target value. If the impregnation state is good, the process may be terminated. If the impregnation state is poor, the process may be terminated, indicating that the secondary battery 1 is defective.

[0058] By the way, as in (Example 2), if the conditions for each pressurization process are the same, it is conceivable that the sum of the integral values ​​may significantly exceed the target value. In such cases, when the difference from the target value deviates by more than a predetermined value, the control device may adjust the pressurization time or reduce the pressurization pressure in the next pressurization impregnation process of the secondary battery 1 to be manufactured so that the integral value approaches the target value. For example, suppose that in the pressurization impregnation process of the secondary battery 1, four pressurization processes are performed and the sum of the integral values ​​exceeds the target value, and at that time, the difference between the sum of the integral values ​​and the target value deviates by more than a predetermined value.

[0059] In such cases, in the subsequent pressurization process of the secondary battery 1 to be manufactured, the pressurization time in the fourth pressurization treatment may be shortened compared to the previous pressurization times. Furthermore, the pressurizing force in the fourth pressurization treatment may be lower than the previous pressurizing force. This allows the difference between the sum of the integral values ​​and the target value to be kept below a predetermined value. Such adjustments can further reduce the amount of high-pressure gas used.

[0060] (Effects of the embodiment) (1) In the above pressurized impregnation process, when the impregnation state is good with the pressurizing time and pressure of sample 3, which has the smallest integrated value, the target value is set to a value based on the integrated value obtained by integrating the pressurizing pressure (first pressurizing pressure) of sample 3 with the pressurizing time (first pressurizing time) (see Figure 7). In this embodiment, the pressurizing pressure (second pressurizing pressure) is made smaller than the pressurizing pressure (first pressurizing pressure) of sample 3, as in samples 1, 2, 4, and 5, and the pressurizing time (second pressurizing time) is made longer than the pressurizing time (first pressurizing time) of sample 3, as in samples 1, 2, 4, and 5, so that the integrated value is equal to or greater than the target value. As a result, in this embodiment, the impregnation state of the electrolyte 45 in the electrode body 10 can be made good while suppressing an increase in the pressurized flow rate.

[0061] Through such adjustments, in the mass production equipment, the amount of high-pressure gas used corresponds to the supply capacity of the high-pressure gas supply equipment 60 that supplies the high-pressure gas, allowing the inside of the pressurized tank 64 to be kept under high pressure and impregnated with the electrolyte 45 into the electrode body 10.

[0062] (2) The pressurization time (second pressurization time) is set to be equal to or greater than the target value within a range below the set pressurization pressure (second pressurization pressure). For example, the pressurization pressure (second pressurization pressure) is set to 0.4 MPa or less, which reduces the amount of gas pressurization equipment such as the booster 62 and buffer tank 63, and then the pressurization time (second pressurization time) is set to be equal to or greater than the target value (Samples 1, 2, 4, 5). This reduces the amount of high-pressure gas used to fill the pressurization tank 64.

[0063] (3) By performing the pressurization treatment only once, as in Samples 1 and 2, the amount of high-pressure gas used to fill the pressurized tank 64 can be reduced compared to when the pressurization impregnation treatment is performed multiple times, as in Samples 4 and 5.

[0064] (4) In the pressure impregnation process, if the pressure treatment is performed multiple times, as in samples 4 and 5, the integral value can be brought closer to the target value in stages. (5) In the high-pressure gas supply equipment 60, if the set pressurization force is 0.4 MPa or less, as in samples 1, 2, 4, and 5, the addition of gas pressurization equipment such as the booster 62 and buffer tank 63 can be suppressed. In addition, modifications to the pressurizing tank 64 to improve its pressure resistance from a commercially available product can be suppressed.

[0065] (6) If the integral value is large compared to the target value, the pressurizing force and pressurizing time are adjusted to bring the integral value closer to the target value. For example, the pressurizing force is reduced and / or the pressurizing time is shortened. This reduces the amount of high-pressure N2 gas used to inject into the pressurizing tank 64.

[0066] (7) By injecting the electrolyte 45 under vacuum, the differential pressure with that under pressure can be increased. This promotes the impregnation of the electrode body 10 with the electrolyte 45. (modified version) The above embodiment can be implemented with the following modifications. The above embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0067] • The electrolyte solution may be injected at atmospheric pressure rather than in a vacuum environment. If the integral value exceeds a threshold value set to be greater than the target value, in the next pressurization and impregnation process of secondary battery 1, adjustment processing may be performed to shorten the pressurization time or reduce the pressurized pressure so that the integral value approaches the target value.

[0068] Even if the integral value deviates from the target value by a predetermined amount or more, in the next step of secondary battery 1, the pressurization time may be shortened or the adjustment process to reduce the pressurization pressure may be omitted to bring the integral value closer to the target value.

[0069] • Instead of setting an upper limit for the applied pressure, the applied pressure, pressurization time, and number of pressurization cycles may be adjusted simply to exceed the target value. The high-pressure gas may be an inert gas other than N2 gas, or it may be air.

[0070] The secondary battery 1 may be installed in automated transport machines, special vehicles for cargo handling, electric vehicles, hybrid vehicles, etc., as well as in computers and other electronic devices, or it may constitute a system other than those mentioned above. For example, it may be installed in mobile bodies such as ships and aircraft, or it may be part of a power supply system that supplies electricity from a power plant to buildings and homes where the secondary battery is installed via substations, etc. [Explanation of symbols]

[0071] 1…Secondary battery 3…Positive plate 4… Negative plate 5... Separator 10...Electrode body 10x…winding shaft 20...cases 21…Case body 21x…Open end 22... Lid component 31...Current collector foil 32...electrode active material layer 35… Electrode sheet 38N…Negative terminal 38P…Positive terminal 39…Unpainted section 45...Electrolyte 50-53... Pressure characteristic curve 60... High-pressure gas supply equipment 61... Gas generator 62... Booster 63... Buffer Tank 64… Pressurized tank

Claims

1. A method for manufacturing a non-aqueous electrolyte secondary battery, comprising inserting an electrode body, which is constructed by stacking a positive electrode plate and a negative electrode plate with a separator in between, into a case, and then pouring an electrolyte solution to impregnate the electrode body, The process includes a pressurization step in which the electrode body is inserted into the case, the electrolyte is poured into the case, and the inside of the case is subjected to a high-pressure state to perform a pressurization treatment, thereby pressurizing the electrode body with the electrolyte, The pressurized impregnation process is terminated when the integral value obtained by integrating the pressurizing force over the pressurizing time from the start of pressurizing reaches or exceeds a target value of the integral value that indicates a good impregnation state of the electrolyte in the electrode body. A method for manufacturing a non-aqueous electrolyte secondary battery.

2. The pressurizing time is set so that the pressure is greater than or equal to the target value, within a range less than or equal to the set pressurizing force. A method for manufacturing a non-aqueous electrolyte secondary battery according to claim 1.

3. In the aforementioned pressure impregnation process, the number of times the pressure treatment is applied is one. A method for manufacturing a non-aqueous electrolyte secondary battery according to claim 1 or 2.

4. In the aforementioned pressure impregnation process, the number of times the pressure treatment is applied is multiple. A method for manufacturing a non-aqueous electrolyte secondary battery according to claim 1 or 2.

5. The set pressure is 0.4 MPa or less. A method for manufacturing a non-aqueous electrolyte secondary battery according to claim 2.

6. The pressurized impregnation process adjusts the pressurizing force and pressurizing time so that the integral value approaches the target value when the integral value is greater than or equal to the target value. A method for manufacturing a non-aqueous electrolyte secondary battery according to claim 4.

7. The electrolyte is injected under vacuum. A method for manufacturing a non-aqueous electrolyte secondary battery according to claim 1.

Images