JP5734806B2 - Container evaluation apparatus, evaluation method, and secondary battery manufacturing method - Google Patents

Description

  The present invention relates to a container evaluation device, an evaluation method, and a method for manufacturing a secondary battery using the same.

  As a pressure vessel pressure test apparatus, for example, an apparatus that repeatedly supplies a predetermined vibration pattern is disclosed. (Patent Document 1). In recent years, automobiles using secondary batteries such as Li-ion batteries have been used. Even in such a secondary battery, the endurance test of the cell container storing the cell is performed to evaluate the performance of the cell container.

JP-A-10-123023

  In the pressure resistance test apparatus described in Patent Document 1, an excitation pattern is added by a hydraulic servo valve. When a pressure resistance test of a cell container is performed using such a pressure strength test apparatus, there are the following problems.

  Oil used as a pressure medium will contaminate the surrounding environment. For example, the secondary battery is manufactured and evaluated in an environment where the surrounding environment is controlled, such as a dry room or a clean room. Therefore, when oil is used as the pressure medium, the pressure medium leaks out to the surroundings when the cell is deteriorated and destroyed during the durability test or when the workpiece is removed. In addition, the evaluation is performed such that the pressure medium circulates in the pipe. However, when a part of the electrode is taken into the pressure medium after a long period of use, the waste liquid treatment also becomes a problem.

  Furthermore, the pressure medium leaks when the container is attached and detached, and the pressure is reduced. Therefore, it is necessary to replenish the pressure medium regularly, and the maintenance frequency of the equipment increases. Thus, when oil is used as a pressure medium, there is a problem that it cannot be easily evaluated.

  The present invention has been made in view of the above problems, and provides an evaluation device, an evaluation method, and a method for manufacturing a secondary battery using the same, which can easily carry out a durability test of a container. With the goal.

  An evaluation apparatus according to an aspect of the present invention is an evaluation apparatus for evaluating a container used in a secondary battery, and includes a gas supply unit that supplies pressurized gas, and a space between the gas supply unit and the container. An air servo valve disposed in the gas flow path, a control means for controlling the air servo valve to adjust the pressure of the container, and disposed between the air servo valve and the container And an opening / closing valve and a first pressure sensor for measuring the pressure of the container in a state in which the opening / closing valve is closed. In this configuration, since gas is used as the pressure medium, the evaluation can be easily performed.

  The evaluation apparatus may further include a manifold that distributes the gas supplied from the gas supply unit via the air servo valve to the plurality of containers, and the on-off valve and the first pressure sensor include the plurality of May be provided for each of the containers. Since a plurality of containers can be evaluated at a time, the evaluation can be performed efficiently.

  The evaluation apparatus further includes a second pressure sensor for measuring the pressure of the manifold, and the control means controls the air servo valve based on the pressure detected by the second pressure sensor. The pressurization and decompression of the container may be repeatedly performed. Thereby, pressure control can be performed correctly and the reliability of evaluation can be improved.

  In the evaluation apparatus, temperature control means for controlling the temperature of the container may be provided. Thereby, since the temperature of the container under evaluation can be adjusted, the reliability of evaluation can be improved.

  The evaluation apparatus may further include a drying unit that dries the gas supplied from the gas supply unit to the container. Thereby, the dew condensation in piping can be prevented.

  In the evaluation apparatus, the drying means may be a refrigeration dryer. Thereby, the dew condensation in piping can be prevented simply.

  An evaluation method according to an aspect of the present invention is an evaluation method for evaluating a container used in a secondary battery, the step of supplying pressurized gas from a gas supply means to an air servo valve, and the air servo Adjusting the pressure of the gas supplied from the gas supply means to the container by controlling the valve; and closing the on-off valve provided between the air servo valve and the container; And a step of measuring the pressure of the container with the on-off valve closed, and a step of evaluating the container based on a measurement result of the pressure of the container. In this configuration, since gas is used as the pressure medium, the evaluation can be easily performed.

  In the above evaluation method, the gas from the air servo valve is distributed to the plurality of containers by a manifold provided between the gas supply means and the air servo valve, and each of the plurality of the containers is distributed. The respective pressures of the plurality of containers may be measured in a state where the on-off valve provided for the container is closed. Since a plurality of containers can be evaluated at a time, the evaluation can be performed efficiently.

  In the above evaluation method, the container may be repeatedly pressurized and depressurized by controlling the air servo valve based on the pressure measurement result of the manifold. Thereby, pressure control can be performed correctly and the reliability of evaluation can be improved.

  In the above evaluation method, the air servo valve may adjust the pressure of the container while the temperature of the container is controlled. Thereby, since the temperature of the container under evaluation can be adjusted, the reliability of evaluation can be improved.

  In the above evaluation method, the gas supplied from the gas supply means to the air servo valve may be dried. Thereby, the dew condensation in piping can be prevented.

  The manufacturing method of the secondary battery includes a step of performing pass / fail determination of the container by the evaluation method, and a step of manufacturing a secondary battery using the container determined to be the non-defective product. is there. Thereby, productivity can be improved.

  ADVANTAGE OF THE INVENTION According to this invention, the evaluation apparatus which can evaluate a container simply, an evaluation method, and the manufacturing method of a secondary battery using the same can be provided.

It is a figure which shows the whole structure of the evaluation apparatus which concerns on this Embodiment. It is a figure which shows the air servo valve of an air direct acting system. It is a figure which shows the pressurization system air servo valve. It is a figure which shows typically the pressure waveform used for the evaluation apparatus concerning this Embodiment. It is a graph which shows the relationship between a waveform amplitude and the frequency | count of destruction. It is a figure which shows the connection of the cell container in the evaluation apparatus concerning this Embodiment. It is a graph which shows the temperature characteristic of the intensity | strength of aluminum. It is a graph which shows the temperature dependence of a cell pressure. It is a flowchart which shows the evaluation method concerning this Embodiment. It is a figure which shows an example of the pressure waveform at the time of an endurance test. It is a figure which shows an example of the pressure waveform at the time of a leak test.

  Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments. In addition, for clarity of explanation, the following description and drawings are simplified as appropriate.

Embodiment 1 FIG.
First, the evaluation apparatus according to the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a diagram showing the overall configuration of the evaluation apparatus. The evaluation device includes a distribution board 10, a compressor 11, a dryer 12, an air tank 13, a manifold 14, a filter 15, a regulator 16, an on-off valve 17, a control device 18, an air servo valve 21, an exhaust valve 22, a pressure sensor 23, and a manifold 24. And an on-off valve 25, a pressure sensor 26, and a thermostatic bath 30. In addition, although the following description demonstrates the example which used air as a pressure medium, you may use other gas, such as nitrogen, as a pressure medium, for example.

  The evaluation device evaluates durability when the cell container 27 is pressurized with gas. As shown in FIG. 1, a plurality of cell containers 27 that are workpieces are attached to the evaluation apparatus. That is, the cell container 27 to be evaluated is connected to the piping of the evaluation device. The evaluation device tests the pressure strength of the cell container 27 when the pressure is repeatedly applied. In this way, the durability test is performed on the cell container 27 which is a sealed container of the secondary battery. The evaluation device performs an endurance test on the cell container 27 of a secondary battery such as a Li ion battery, and evaluates the cell container 27 based on the test result. And in the evaluation apparatus, the cell of a lithium ion battery is enclosed in the cell container 27 determined to be non-defective. Thereby, a secondary battery can be manufactured with high productivity.

  The distribution board 10 supplies power to the compressor 11 and the control device 18. Of course, the distribution board 10 may supply power to other valves and sensors. The compressor 11 compresses air by the power supplied from the distribution board 10. The air pressurized by the compressor 11 is dried by the dryer 12 and supplied to the air tank 13 serving as a buffer. The compressed air pulsates in the air tank 13 and is supplied to the manifold 14. Five lines of pipes are connected to the manifold 14. That is, the air from the air tank 13 is branched into five systems. Here, the five piping lines have the same configuration.

  The compressed air branched by the manifold 14 passes through the filter 15 to remove dust in the air. The air that has passed through the filter 15 becomes a constant pressure by the regulator 16. The regulator 16 prevents an abnormal pressure increase of the gas and prevents the piping in the evaluation apparatus from being broken. An on-off valve 17 is provided on the downstream side of the regulator 16 so that gas can be shut off. An air servo valve 21 is provided on the downstream side of the on-off valve 17. That is, the air servo valve 21 is provided in the flow path from the compressor 11 to the cell container 27. The air servo valve 21 adjusts the output pressure by an electrical control signal from the control device 18. The control device 18 outputs a control signal corresponding to a desired pressure waveform to the air servo valve 21. The air servo valve 21 controls the output pressure according to the control signal. An exhaust valve 22 is provided downstream of the air servo valve 21. The exhaust valve 22 is provided to perform forced exhaust during an emergency stop or the like.

  A manifold 24 is provided downstream of the exhaust valve 22. Air whose pressure is controlled by the air servo valve 21 is distributed to six piping lines by the manifold 24. Accordingly, by distributing air between the first-stage manifold 14 and the second-stage manifold 24, a total of 30 cell containers 27 can be evaluated at a time. A cell container 27 is connected to each piping line branched by the manifold 24 via an opening / closing valve 25. The six piping lines branched by the manifold 24 have the same configuration.

  A pressure sensor 26 for measuring the pressure in each cell container 27 is attached to the downstream side of the on-off valve 25. The pressure sensor 26 is disposed between the cell container 27 and the on-off valve 25. The pressure sensor 26 is provided for each cell container 27 so that the pressure of each cell container 27 can be measured. Therefore, the same number of pressure sensors 26 and open / close valves 25 as the cell containers 27 (30 in FIG. 1) are provided. Thus, by providing a plurality of pressure sensors 26 and on-off valves 25, a large number of evaluations can be performed at one time, and an efficient test can be performed. Thereby, the test time can be shortened. Further, since the pressure sensor 26 is disposed on the downstream side of the on-off valve 25, the pressure in the cell container 27 in a state where the on-off valve 25 is closed can be measured.

  The manifold 24 is provided with a pressure sensor 23. The pressure sensor 23 measures the pressure in the manifold 24 before branching to the piping toward the cell container 27. The control device 18 controls each device described above. For example, the control device 18 controls the output pressure of the air servo valve 21 according to the pressure detected by the pressure sensor 23. Furthermore, the opening / closing of the opening / closing valve 17 and the opening / closing valve 25 is controlled.

  The control device 18 controls the air servo valve 21 by opening the on-off valve 25. Therefore, the control device 18 performs feedback control of the air servo valve 21 based on the pressure value detected by the pressure sensor 23. Thereby, it can control so that the cell container 27 may become a predetermined pressure. Further, the cell container 27 and the pressure sensor 26 are housed in a constant temperature bath 30. The thermostat 30 is a temperature control means for controlling the temperature of the cell container 27. Specifically, the thermostat 30 is provided with a temperature sensor, a heater, a temperature controller, and the like, and the thermostat 30 controls the temperature so as to be constant at the temperature set by the control device 18. Thereby, an endurance test can be performed in the state where a plurality of cell containers 27 are maintained at the same temperature. Further, a temperature sensor may be attached to each cell container 27 and the test temperature of each cell container 27 may be measured.

  In the present embodiment, the air servo valve 21 is used to control the pressure of the cell container 27. Furthermore, since air pressurization by an air direct acting system is used, pressure responsiveness can be improved. Here, the air direct acting method used in the present embodiment will be described in comparison with the pressurizer method. FIG. 2 is a diagram schematically showing the configuration of the air direct acting system. FIG. 3 is a diagram schematically showing a configuration of a pressurizer system as a comparative example, and shows an example in which a pressurizer system used in a hydraulic shaker or the like is used for an endurance test. In FIGS. 2 and 3, a part of the configuration shown in FIG. 1 is omitted. The configuration between the filter 15 and the air servo valve 21 is the same as that shown in FIG.

  In the air direct acting type air servo valve 21, the air supplied from the compressor 11 passes through the air servo valve 21 and is supplied to the cell container 27 (not shown in FIG. 2). That is, the air servo valve 21 communicates with the cell container 27, and air from the compressor 11 is supplied to the cell container 27 via the air servo valve 21. When the control device 18 inputs a command value to the air servo valve 21, the air servo valve 21 supplies an air pressure corresponding to the command value to the cell container 27. Thus, in the air direct acting system, the air compressor 11 and the cell container 27 communicate with each other via the air servo valve 21. The air pressure generated by the air servo valve 21 as a command value is directly supplied to the cell container 27.

  On the other hand, in the pressurizer system as a comparative example, air from the air servo valve 21 is supplied to the air cylinder 40 as shown in FIG. When the control device 18 inputs a command value to the air servo valve 21, the air servo valve 21 supplies an air pressure corresponding to the command value to the air cylinder 40. The air cylinder 40 operates according to the air from the air servo valve 21. Then, the pressure of the pressurizer 41 is changed by the operation of the air cylinder 40. The pressurizer 41 changes the pressure in the cell container 27 (not shown in FIG. 3).

  Thus, when the air direct acting system is used, other actuators such as a pressurizer are not required. As a result, it is possible to prevent a delay as in the pressurizer system. Therefore, overshoot due to control delay can be suppressed, and test accuracy can be increased. That is, a desired pressure waveform can be generated with high accuracy, and the pressure of the cell container 27 can be controlled with good responsiveness. Furthermore, since the pressurizer 41, the air cylinder 40, etc. are unnecessary, it can be set as a simple structure with few components. Therefore, the reliability as equipment can be increased and the cost of the pair can be reduced.

  Next, an example of a pressure waveform of an endurance test using the air servo valve 21 will be described with reference to FIG. FIG. 4 is a diagram showing an example of a pressure waveform, and shows a pressure waveform for determining whether or not the cell container 27 is broken. In FIG. 4, the horizontal axis is time, and the vertical axis is pressure.

First, pressurization and decompression are performed a specified number of times (period A). For example, the air servo valve 21 pressurizes the cell container 27 from the first pressure to the second pressure, and then reduces the pressure from the second pressure to the first pressure. With this pressure increase / decrease as one cycle, the air servo valve 21 repeats pressure increase / decrease for a specified number of times. As a pressure waveform for performing pressurization and decompression, for example, a triangular wave, a square wave, and a trapezoidal wave can be used.
After performing the specified number of pressurizations and decompressions, perform a leak test. Specifically, first, the cell container 27 is pressurized to a predetermined pressure (period B). When the cell container 27 reaches a predetermined pressure, the on-off valve 25 is closed (boundary between the period B and the period C). Thereby, the on-off valve 25 seals each cell container 27. That is, the cell container 27 is disconnected from the air servo valve 21 and cannot exchange pressure. Then, the pressure sensor 26 measures the pressure fluctuation of the cell container 27 (period C) by leaving the on-off valve 25 closed for a certain period of time. That is, the amount of air leakage after the on-off valve 25 is closed is measured. Then, in the period C, the cell container 27 whose pressure is equal to or lower than the threshold value is determined as a defective product.

  For example, when the cell container 27 is destroyed by an endurance test in which pressurization and depressurization are repeated, the amount of air leakage increases. That is, in the broken cell container 27, since air leaks from the broken portion, the pressure drop of the cell container 27 increases. Therefore, the control device 18 compares the pressure after being left for a certain period of time with a preset threshold value. If the pressure is equal to or lower than the threshold value, it is determined that the cell container 27 is destroyed. If the pressure is higher than the threshold value, it is determined that the cell container 27 is not destroyed. Thus, by closing the on-off valve 25, it is possible to determine whether or not confidentiality before destruction is maintained. Of course, the measurement result of the pressure sensor 26 may be constantly monitored, and the on-off valve 25 may be closed when the pressure becomes less than the threshold value.

  The cell container 27 whose pressure has become equal to or lower than the threshold value due to the leak ends the test with the on-off valve 25 kept closed. The cell container 27 whose pressure after being allowed to stand for a certain time is higher than the threshold value moves to the next test step when the period C ends. That is, when the period C ends, the on-off valve 25 is opened and the pressurization and depressurization are repeated again. For example, the same durability test is performed using different pressure waveforms or the same pressure waveform. FIG. 5 shows a plot of the relationship between the amplitude at the time of destruction and the number of destroyed parts after all the tests are completed. In FIG. 5, it is a graph which shows a test result, the horizontal axis shows the amplitude of a waveform, and the vertical axis | shaft has shown the number of the cell containers 27 which destroyed. Since it determines based on the pressure of the state which sealed the cell container 27, it can be determined whether it destroyed more correctly.

  Thus, the air servo valve 21 repeatedly performs pressurization and pressure reduction. And it is determined whether it was destroyed by the pressure fluctuation when the cell container 27 was sealed. By doing in this way, durability of the cell container 27 can be tested easily. For example, when oil or the like is used as a pressure medium as in the prior art, it is necessary to accumulate liquid in the cell container 27 or detect oil adhering to the cell container 27 by visible light in order to detect the presence or absence of destruction. Arise. However, the test can be easily performed by using a gas such as air as a pressure medium as in the present embodiment. For example, it is possible to prevent contamination of a dry room or a clean room where the battery is manufactured or evaluated. In addition, when water is used as the pressure medium, lithium and water, which are secondary battery materials, are likely to react with each other, and therefore work must be performed while paying attention to ignition and smoke generation. However, by using a gas such as air as in the present embodiment, the test can be performed easily and safely.

  Further, when a liquid such as oil or water is used as the pressure medium, the pressure medium needs to be periodically replenished due to the leakage of the pressure medium that occurs when the workpiece is attached or detached. However, in the present embodiment, since the compressed air is supplied using the compressor 11, it is not necessary to replenish the pressure medium. Thereby, an endurance test can be performed more simply. Furthermore, the actual usage environment of the secondary battery is in the air. That is, the deterioration of the secondary battery cell is caused by the pressure fluctuation inside the cell container 27 due to the temperature difference between day / year and the pressure fluctuation accompanying the charging / discharging of the battery. The influence of gas can be evaluated as in the actual use environment. Therefore, the durability test can be performed more accurately.

  Moreover, since the air servo by the air direct acting system is used, a desired pressure waveform can be generated with high accuracy. For example, when pressure control is performed by connecting a pipe to each of the compressor 11 serving as the high pressure generation source and the vacuum pump serving as the decompression generation source and switching the valves, it becomes difficult to obtain a desired waveform. Specifically, when the trapezoidal wave is generated, the end portion becomes loose, and the pressure waveform to be obtained is different. Further, when switching between the high pressure side and the decompression side, distortion and noise components are generated in the waveform. In addition, the route switching portion is likely to cause troubles that make the route complicated, and has low reliability. Like the evaluation apparatus according to the present embodiment, a desired pressure waveform can be generated reliably and easily by controlling with a direct acting air servo.

  Pressurization and decompression can be performed in a short time, and the test time can be shortened. For example, in the durability test, the pressure increase / decrease may be repeated thousands to tens of thousands of times. In the method of switching between the high pressure side and the low pressure side that the inventor made as a prototype, one cycle takes about several tens of seconds, but when a linear motion type air servo is used as in this embodiment, one cycle takes several seconds. It can be shortened to the extent. Thereby, since the test time can be shortened, the durability test can be carried out several times. Therefore, the development period of the secondary battery cell can be shortened.

  Furthermore, among the servo systems using air, there is a classification based on the pressurization system, and due to the difference due to these structures, the characteristics of the test apparatus such as durability, performance, delay time from input, etc. are different. In this embodiment, since pressure control is performed by a servo using an air direct acting system, the reliability of the test can be improved. Moreover, the presence or absence of destruction of the cell container 27 is detected by detecting a pressure change due to leakage in a state where the cell container 27 is sealed. This eliminates the need for an optical sensor or a liquid level sensor for detecting oil or the like. Therefore, the durability test can be easily performed.

  In the present embodiment, the manifold 24 is used to distribute the gas to the plurality of cell containers 27. That is, a plurality of cell containers 27 are connected to each servo system in a cluster shape, and each cell container 27 can be sealed with an on-off valve 25 provided between the air servo valve 21 and the cell container 27. Thereby, the endurance test of the plurality of cell containers 27 can be performed at a time. The configuration for this will be described with reference to FIG. FIG. 6 is a diagram schematically showing the configuration of one servo system. FIG. 6 shows a 6-channel piping line connected to one manifold 24.

  A manifold 24 is connected to the air servo valve 21. The manifold 24 distributes the air from the air servo valve 21 to the plurality of cell containers 27. Here, six cell containers 27 are connected to one manifold 24. Further, as described above, the open / close valve 25 is provided between each cell container 27 and the manifold 24. Further, a pressure sensor 26 is provided between the on-off valve 25 and the cell container 27. For this reason, the number of on-off valves 25 and pressure sensors 26 is the same as the number of cell containers 27. Thereby, each on-off valve 25 can be sealed independently, and the pressure of each on-off valve 25 can be measured independently. Further, an exhaust valve 22 is provided in the pipe between the manifold 24 and the air servo valve 21 for performing forced exhaust during an emergency stop or the like.

  The number of air servo valves 21 can be reduced by sharing the air servo valves 21 for pressure control with respect to the plurality of cell containers 27. That is, since it is not necessary to provide the air servo valve 21 for each cell container 27, an increase in cost can be suppressed even when the number of the cell containers 27 is increased.

  Further, an opening / closing valve 25 is provided for each cell container 27. When a certain cell container 27 is broken, the on-off valve 25 corresponding to the broken cell container 27 is closed. Thereby, the cell container 27 in which the destruction has occurred can be separated, and the durability test can be continued. That is, in FIG. 6, even when one cell container 27 is broken, the durability test for the remaining five cell containers 27 can be continued. Therefore, the durability test can be performed more efficiently.

  Furthermore, a pressure sensor 23 is also provided in the manifold 24. Based on the pressure sensor 23, the control device 18 performs feedback control on the output pressure of the air servo valve 21. By doing in this way, even if a defect occurs in a specific cell container 27 and the on-off valve 25 is maintained in the closed state, the durability test can be continued. Furthermore, since control is not performed based on the pressure of a specific cell container 27, a pressure waveform can be accurately generated even when the specific cell container 27 is broken or the like.

  In the present embodiment, the cell container 27 is disposed in the thermostatic bath 30. By doing so, the durability test can be carried out in an environment in which the temperature around the cell is controlled. For example, the member used for the cell container 27 is aluminum or the like, and mechanical strength such as proof stress and tensile strength depends on temperature (see FIG. 7). Furthermore, as shown in FIG. 8, the pressure inside the cell container 27 varies depending on the surrounding pressure. Therefore, in the present embodiment, the cell container 27 is disposed in the thermostat 30 to manage the temperature of the durability test. In addition, a reference temperature is determined and evaluated. Thereby, evaluation can be performed in a state in which a variation factor depending on temperature is eliminated. Therefore, a highly reliable test can be performed.

  Furthermore, it is also possible to set the temperature conditions such as assumed cold regions and subtropics and evaluate in this environment. By doing so, it is possible to investigate the influence of the temperature condition on the life and durability of the battery cell. Highly reliable test data can be obtained by evaluating with a test pattern considering the measurement environment based on the results of these tests.

  In the present embodiment, the air from the compressor 11 is dried by the dryer 12. By using the dryer 12 as a drying means, condensation in the piping can be prevented. Usually, the moisture compressed by the air compressed by the compressor 11 increases. During compression, the temperature rises due to adiabatic compression, but in the process of traveling through the piping, there is a risk that the temperature will drop and condensation will occur. If dew condensation occurs, there is a risk that rust will be generated or a mechanical part will be defective. Therefore, in the present embodiment, a dryer 12 is provided on the downstream side of the compressor 11 to dry the air. By doing so, it is possible to prevent dew condensation in the piping.

  Examples of the type of the dryer 12 include a refrigeration dryer, an adsorption dryer, and a hollow fiber membrane dryer, and it is preferable to use a refrigeration dryer that forcibly cools compressed air to remove moisture. The reason is that, in the case of an adsorption dryer, dry air having a lower dew point can be produced, but the cost becomes high. Further, in the hollow fiber membrane type dryer, water vapor is removed by utilizing the fact that moisture permeation is remarkably faster than oxygen and nitrogen. In the hollow fiber membrane type dryer, air loss occurs as purge air, so a large capacity compressor 11 is required. When the large-capacity compressor 11 is used, not only in terms of energy, but also the noise and vibration amount are large, and the influence on the worker is large. For the above reasons, it is preferable to use a refrigeration dryer.

  It is preferable to remove moisture before it is cooled and condensed while air heated to high temperature due to compression in the compressor 11 is propagating through the pipe. For this reason, it is preferable to install the dryer 12 between the compressor 11 and the air tank 13. Moreover, since it is not necessary to purge the inside of the piping with an inert gas such as Ar or Ne by drying the air, it is possible to suppress an increase in the scale of the facility. Therefore, cost can be reduced and maintainability can be improved. When nitrogen or the like is used as the pressure medium, dry nitrogen may be used without using the dryer 12.

  Thus, in the durability test apparatus according to the present embodiment, the cell container 27 can be evaluated with high accuracy. And by designing the cell container 27 using this evaluation result, it is possible to shorten the product development period and to prevent market troubles.

  For example, in a lithium ion secondary battery, gas is generated by repeated charge and discharge, and the pressure in the cell container is increased. Further, since the gas inside the cell container 27 changes depending on the ambient temperature, the cell container 27 is used in the market while repeating pressurization / decompression. Generally, a secondary battery for consumer use assumes a service life of about 2 to 3 years. On the other hand, in the secondary battery for automobiles, 10 years is set as the target of the service life, and it continues to be used for several times as long as the secondary battery for consumer use. Furthermore, since it is exposed to a severe outdoor environment, higher reliability is required than a secondary battery for consumer use.

  On the other hand, the welded part of a sealed can called a seal part has many technical problems due to the occurrence of underfill, voids and the like. For this reason, the design of the cell container 27 is advanced through trial and error while taking these into consideration. Therefore, it is desirable to evaluate the durability against pressure fluctuations in the cell as the design proceeds. In this embodiment, since the air servo system is used, the pressure inside the cell can be controlled with high accuracy. And durability of the cell container 27 can be evaluated with high precision by repeating pressurization and pressure reduction. Taking this evaluation result into consideration, the reliability can be improved by feeding back to the product design. For example, as a result of an endurance test, a portion where damage is likely to occur can be improved by changing the design and strengthening the pressure resistance.

  Next, the evaluation method according to the present embodiment will be described with reference to FIGS. FIG. 9 is a flowchart showing the evaluation method. FIG. 10 is a diagram showing a pressure waveform of pressure increase / decrease for one cycle. FIG. 11 is a diagram showing pressure fluctuation when the on-off valve 25 is opened. 10 and 11, the horizontal axis indicates time, and the vertical axis indicates pressure. Here, as shown in FIG. 10, an example using a trapezoidal wave as a pressure waveform will be described. The control device 18 controls the air servo valve 21 to control the pressure as shown in FIGS. 10 and 11.

  When the durability test is started, first, the control device 18 controls each valve (step S1). Here, the open / close valve 25 connected to the cell container 27 to be tested is opened, and the exhaust valve 22 is closed. Of course, the regulator 16 keeps the piping at a constant pressure. Next, the control apparatus 18 outputs the target temperature with respect to the thermostat 30 (step S2). Thereby, the temperature of the thermostat 30 is heated or cooled. And it is confirmed whether the thermostat 30 reached | attained target temperature (step S3). If the target temperature has not been reached (No in step S3), the thermostat 30 is heated or cooled until the target temperature is reached. When the thermostat 30 has reached the target temperature (Yes in step S3), it is confirmed whether or not the time that has reached the target temperature has reached the temperature stabilization time (step S4). That is, it is confirmed whether or not the temperature stabilization time has elapsed since the target temperature was reached. If the time that has reached the target temperature has not reached the temperature stabilization time (No in step S4), the system waits at the target temperature until the temperature stabilization time is reached.

  When the time when the target temperature is reached becomes the temperature stabilization time (Yes in step S4), it is determined that the temperature of the thermostatic bath 30 is sufficiently stabilized, and pressurization to the pressure P1 is started (step S5). In addition, as shown in FIG. 10, P1 is a lower limit value of the pressure in the trapezoidal wave. That is, the air servo valve 21 is controlled to adjust the pressure in the cell container 27 and the manifold 24. Then, it is confirmed whether or not the measured value of the pressure sensor 26 has reached the pressure P1 (step S6). If the measured value of the pressure sensor 26 has not reached the pressure P1 (No in step S6), the air servo valve 21 continues to pressurize the cell container 27 until the pressure P1 is reached. If the pressure P1 has been reached (Yes in step S6), it is confirmed whether or not the pressure has reached time T1 (step S7). As shown in FIG. 10, the time T1 indicates the set time in one cycle, and specifically indicates the time for starting pressurization from the pressure P1. When the time from the start of one cycle has not reached time T1 (No in step S7), the air servo valve 21 is controlled so that the cell container 27 remains at the pressure P1 until the time T1 is reached.

  When the time T1 is reached (Yes in step S7), pressurization up to the pressure P2 is started (step S8). In addition, as shown in FIG. 10, P2 is the upper limit of the pressure in a trapezoidal wave. And the control apparatus 18 confirms whether it reached | attained to time T2 (step S9). As shown in FIG. 10, the time T2 indicates a set time in one cycle. Specifically, the time T2 indicates a time until the pressure P2 is reached. Of course, in step S9, it may be confirmed whether or not the pressure of the pressure sensor 23 has reached the pressure P2 instead of confirming that the time T2 has been reached. If the time has not reached time T2, since the pressure P2 has not been reached, pressurization to pressure P2 is continued until time T2 is reached (No in step S9). When the time T2 is reached (Yes in step S9), the pressure P2 is maintained, and it is confirmed whether or not the time T3 has been reached (step S10). The time T3 indicates a set time in one cycle, and specifically indicates a time for starting the pressure reduction from the pressure P2 to the pressure P1.

  If the time T3 has not been reached (No in step S10), the pressure P2 is maintained until the time T3 is reached. When the time T3 is reached (Yes in step S10), pressure reduction to the pressure P1 is started (step S11). Then, it is confirmed whether or not the time T4 has been reached (step S12). The time T3 indicates the set time during one cycle, and specifically indicates the end time of one cycle. Of course, in step S12, instead of confirming that the time T4 has been reached, it may be confirmed whether or not the pressure of the pressure sensor 23 has reached the pressure P1. If the time T4 has not been reached (No in step S12), since the pressure P1 has not been reached, the air servo valve 21 continues to reduce the pressure P1 until the time T4 is reached. If the time T4 has been reached (Yes in step S12), one cycle of pressure increase / decrease is terminated, and the process proceeds to the next step 13.

  As described above, such pressure control is performed by the control device 18 controlling the air servo valve 21 based on the preset pressures P1 and P2 and the times T1 to T4. The user may input arbitrary values as the pressures P1 and P2 and the times T1 to T4, or may be stored in advance in a memory or the like.

  When the pressurization / decompression of one cycle is completed, the control device 18 increments the number of cycles and determines whether or not the number of cycles has reached the number of leak tests (step S13). The number of leak tests is a value indicating the number of cycles in which the leak test is performed, and is preset in the control device 18. For example, when the leak test is performed every 1000 cycles out of the total cycle count 10,000, the leak test count is set to 1000, 2000, 3000,.

  If the number of leak tests has not been reached (No in step S13), it is determined whether or not the number of cycles has ended (step S14). That is, it is determined whether or not the pressure increase / decrease has been repeated a predetermined number of times. In the above case, it is determined whether or not the number of cycles has reached 10,000. When the number of cycles reaches 10,000 (Yes in step S14), the process proceeds to step S15 to end the durability test. The number of cycles to end the durability test may be preset in the control device 18 or may be input by the user.

  When the endurance test ends, the pressure is reduced to 0 (atmospheric pressure) (step S15), and the opening and closing of each valve is controlled (step S16). For example, in order to remove the cell container 27 from the manifold 24, the pressure is set to 0 (atmospheric pressure) and the on-off valve 25 is closed. Thereby, the cell container 27 which has completed the durability test can be removed.

  In step S14, when the number of cycles has not ended (No in step S14), the process returns to step S5. Then, the next one cycle of pressure increase / decrease is performed in the same manner.

  When the pressure increase / decrease cycle shown in steps S5 to S12 is repeated and the number of leak tests is reached (Yes in step S13), the leak test is started. When starting a leak test, it is confirmed whether time has reached time T11 (step S17). As shown in FIG. 11, the time T11 is a set time at the time of leak measurement, and specifically indicates a time for starting pressurization from the pressure P11 to the pressure P12. Moreover, the pressure P11 is defined based on the pressure waveform of the pressure increasing / decreasing cycle. When the pressure waveform is a trapezoidal wave as shown in FIG. 10, the pressure P11 is equal to the pressure P1. When the pressure waveform is a square wave, a triangular wave, or a sine wave, the pressure P11 is, for example, the center value of the pressure waveform.

  When the time T11 has not been reached (No in step S17), the pressure P11 is maintained until the time T11 is reached. When the time T11 is reached (Yes in step S17), pressurization from the pressure P11 to the pressure P12 is started (step S18). Thereby, the cell container 27 is pressurized. The pressure P12 may be set in advance in the control device 18, or the user may input an arbitrary value. Then, it is confirmed whether or not the time has reached T12 (step S19). As shown in FIG. 11, the time T12 is a set time at the time of measuring the leak amount, and specifically shows the time to reach the pressure P12. Of course, in step S19, instead of confirming that the time T12 has been reached, it may be confirmed whether or not the pressure of the pressure sensor 23 has reached P12. When the time T12 has not been reached, since the pressure P12 has not been reached, pressurization is performed until the time T12 is reached. Thereby, the pressure of the cell container 27 becomes the pressure P12. When time T12 is reached, the process proceeds to the next step S20.

  Next, it is confirmed whether or not the time has reached time T13 (step S20). If the time T13 has not been reached (No in step S20), the pressure P12 is maintained until the time T13 is reached. When time T13 is reached (Yes in step S20), the on-off valve 25 is closed (step S21).

  Then, the initial pressure data of each cell container 27 is acquired by the plurality of pressure sensors 26 (step S22). The initial pressure data here is substantially equal to the pressure P12. Then, the leak measurement test is started, and the pressure data of each cell container 27 is acquired (step S23). Then, a differential pressure between the initial pressure data and the current pressure data is calculated and compared with the threshold value P13 (step S24). Here, when the differential pressure becomes equal to or less than the threshold value P13, the cell container 27 is stored as a defective product. The on-off valve 25 of the cell container 27 determined to be defective may be closed.

  Next, it is confirmed whether or not the time T14 has been reached (step S25). Time T14 indicates the leak test end time. Between time T13 and time T14, the on-off valve 25 is closed, and the pressure sensor 26 measures the pressure. The pressure measured by the pressure sensor 26 is accumulated by the control device 18, for example. If the time T14 has not been reached (No in step S25), the process returns to step S24, and the differential pressure is subsequently compared with the threshold value P13. That is, the pressure data is acquired until the time T14 is reached, and the comparison between the differential pressure and the threshold value P13 is continued. Thereby, the cell container 27 destroyed by the durability test can be detected. That is, the control device 18 determines pass / fail of the cell container 27 based on pressure data from the pressure sensor 26. The cell container 27 in which the differential pressure does not become the threshold value P13 or less by the time T14 is determined as a non-defective product, and the cell container 27 that has become the threshold value P13 or less is determined as a defective product.

  When time T14 is reached, each valve is controlled (step S26). Here, the on-off valve 25 for the good cell container 27 is opened. As a result, the non-defective cell container 27 is connected to the air servo valve 21 again. Moreover, it is not necessary to open the on-off valve 25 for the cell container 27 determined to be defective. Then, the air servo valve 21 starts depressurization to the pressure P11 (step S27). It is confirmed whether or not the time T15 has been reached (step S28). When the time T15 has not been reached (No in step S28), since the pressure reduction to the pressure P11 is not completed, the pressure is reduced until the time T15 is reached, and the cell container 27 is set to the pressure P11.

  When the time T15 is reached (Yes in step S28), it is determined whether or not the number of cycles has been completed (step S29) as in step S14. If the number of cycles has not ended (No in step S29), the process returns to step S5, and the next trapezoidal wave pressure increasing / decreasing cycle (steps S5 to S13) is performed. Since the procedure after returning to step S5 is the same as that described above, the description thereof is omitted. On the other hand, when the number of cycles is completed (No in step S29), the process proceeds to step S15. And a test is complete | finished through step S15 and step S16 similarly to the above.

  In this way, the leak test is performed by repeating the pressurization and depressurization a predetermined number of times. By doing in this way, durability of the cell container 27 can be evaluated. Then, a secondary battery is manufactured using only the cell container 27 determined to be a non-defective product. For example, a positive electrode, a negative electrode, a separator, an electrolyte, and the like are disposed in the cell container 27 and sealed by welding or the like. By doing in this way, since only the cell container 27 with excellent pressure resistance is used, the productivity of the secondary battery can be improved.

  Further, the plurality of air servo valves 21 shown in FIG. 1 may generate different pressure waveforms. Of course, a plurality of air servo valves 21 may generate the same pressure waveform. Furthermore, the number of cell containers 27 connected to one air servo valve 21 is not particularly limited. Further, the number of cell containers 27 connected to each air servo valve 21 may be different. As the pressure sensor 23 and the pressure sensor 26, for example, a diaphragm type pressure gauge can be used. Furthermore, the pressure sensor 23 and the pressure sensor 26 may measure a differential pressure from a predetermined closed space.

DESCRIPTION OF SYMBOLS 10 Distribution board 11 Compressor 12 Dryer 13 Air tank 14 Manifold 15 Filter 16 Regulator 17 On-off valve 18 Control device 21 Air servo valve 22 Exhaust valve 23 Pressure sensor 24 Manifold 25 On-off valve 26 Pressure sensor 27 Cell container 30 Constant temperature bath 40 Air cylinder 41 Pressurizer

Claims (8)

An evaluation apparatus for evaluating a container used for a secondary battery,
Gas supply means for supplying pressurized gas;
An air servo valve disposed in the gas flow path between the gas supply means and the container;
Control means for controlling the air servo valve in order to adjust the pressure of the container;
An on-off valve disposed between the air servo valve and the container;
A first pressure sensor for measuring the pressure of the container with the on-off valve closed;
A manifold for distributing the gas supplied from the gas supply means via the air servo valve to the plurality of containers;
A second pressure sensor for measuring the pressure of the manifold;
With
The on-off valve and the first pressure sensor are provided for each of the plurality of the containers;
An evaluation apparatus that repeatedly pressurizes and depressurizes the container by the control means controlling the air servo valve based on the pressure detected by the second pressure sensor . The evaluation apparatus according to claim 1 , further comprising temperature control means for controlling the temperature of the container. Evaluation apparatus according to claim 1 or 2 further comprising a drying means for drying the gas supplied to the container from the gas supply means. The evaluation apparatus according to claim 3 , wherein the drying means is a refrigeration dryer. An evaluation method for evaluating a container used for a secondary battery,
Supplying pressurized gas from the gas supply means to the air servo valve;
Adjusting the pressure of the gas supplied from the gas supply means to the container by controlling the air servo valve;
Closing an on-off valve provided between the air servo valve and the container;
Measuring the pressure of the container with the on-off valve closed;
Evaluating the container based on a measurement result of the pressure of the container ; and
Distributing the gas from the air servo valve to the plurality of containers by a manifold provided between the gas supply means and the air servo valve,
With the on-off valves provided for each of the plurality of containers closed, measure the pressure of each of the plurality of containers,
An evaluation method in which pressurization and depressurization of the container are repeatedly performed by controlling the air servo valve based on a measurement result of the pressure of the manifold . The evaluation method according to claim 5 , wherein the air servo valve adjusts the pressure of the container while the temperature of the container is controlled. The evaluation method according to claim 5 or 6 , wherein the gas supplied from the gas supply means to the air servo valve is dried. A step of determining pass / fail of the container by the evaluation method according to any one of claims 5 to 7 ,
Producing a secondary battery using the container determined to be non-defective in the quality determination .