Battery negative pressure formation method and apparatus

Abstract

The application relates to the technical field of batteries, and provides a battery negative pressure formation method, which comprises the following steps: S1, connecting a battery to be formed, a trace gas measuring device and a negative pressure source in sequence through pipelines; S2, charging the battery, the battery generating gas, starting the negative pressure source, and the gas generated by the battery being sucked into the pipeline; S3, the trace gas measuring device measuring the gas generation amount and the gas generation rate of the gas passing through the trace gas measuring device; S4, calculating the negative pressure gas extraction time according to the gas generation amount and the gas generation rate measured by the trace gas measuring device and in combination with the negative pressure of the negative pressure source; and S5, setting the working time length of the negative pressure source according to the gas extraction time. The application also provides a battery negative pressure formation device. The trace gas measuring device is introduced into the battery negative pressure formation process, the trace gas measuring device is used to obtain the gas amount of the gas released by the battery, the gas extraction time of the battery negative pressure formation can be calculated, and therefore the production efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a battery negative pressure formation method and device. BACKGROUND

[0002] Battery formation refers to the first charging process of the battery after the battery is injected with liquid. This process can activate the active material in the battery, activate the battery, and generate a solid electrolyte interface (SEI) film on the negative side of the battery during the formation process, which can prevent further occurrence of side reactions.

[0003] The current lithium battery formation process is generally carried out in a high-temperature, low-dew-point environment. During the formation process, a certain amount of gas is generated as the chemical reaction inside the battery proceeds. If the gas is not promptly removed, the accumulation of gas will cause the battery shell to swell, the formation to be poor, and even the battery to be scrapped, which has a high potential risk.

[0004] The existing process has the following problems:

[0005] (1) Currently, a negative pressure source and a pipeline arranged between the negative pressure source and the battery injection hole are mainly used to directly remove the gas generated inside the battery by extracting the gas, and the negative pressure remains constant during the entire negative pressure formation process. In the existing battery negative pressure formation operation, the negative pressure extraction time is estimated according to experience. In order to ensure that the gas can be completely extracted, a relatively long negative pressure extraction time is set, which is usually longer than the actual extraction time. At the same time, the gas generation rate of the battery formation is not a constant process, which results in low negative pressure formation efficiency and prolongs the process time. If the formation gas generation amount can be accurately measured, it will help to optimize the formation process, reduce the formation cycle, and improve the production efficiency. However, due to the black box characteristics of the battery, the gas generation amount during the formation stage cannot be accurately predicted, and currently only a relatively long negative pressure extraction time can be set according to experience, which also results in a long negative pressure extraction process time, prolongs the process time, and reduces the production efficiency.

[0006] (2) The negative pressure extraction process may also extract the electrolyte, causing the electrolyte to be dispersed in the pipeline and enter the vacuum source, thereby causing the electrolyte to be lost and increasing the production cost. In addition, the electrolyte dispersed in the pipeline is prone to crystallization and blockage of the gas extraction pipeline, and even damage to the negative pressure source equipment. Currently, a gas-liquid separation device is generally used to filter the extracted electrolyte, but this method cannot avoid the extraction of the electrolyte.

[0007] (3)In addition, the whole system works under negative pressure condition, and in actual operation, gas leakage in the negative pressure system caused by poor sealing of the pipeline and joint is difficult to avoid. However, only accurate quantitative detection of the gas leakage of the system can ensure accurate measurement of the formation gas. The prior art generally uses a negative pressure gauge to monitor the negative pressure in the system, but the use of the negative pressure gauge can only qualitatively monitor whether there is gas leakage in the system according to the pressure change, and cannot accurately detect the leakage amount of the gas. Therefore, the formation gas amount cannot be accurately measured. SUMMARY

[0008] The purpose of the present application is to provide a battery negative pressure formation method and device, which can at least solve some of the defects in the prior art.

[0009] To achieve the above purpose, the embodiments of the present application provide the following technical solutions: a battery negative pressure formation method, comprising the following steps:

[0010] S1, using a pipeline to sequentially communicate a battery to be formed, a trace gas measuring device and a negative pressure source,

[0011] S2, charging the battery, the battery generating gas, starting the negative pressure source, and the negative pressure source sucking the gas generated by the battery into the pipeline,

[0012] S3, the trace gas measuring device measuring the gas amount passing through it,

[0013] S4, calculating the negative pressure gas extraction time according to the gas amount measured by the trace gas measuring device and combining the negative pressure of the negative pressure source,

[0014] S5, setting the working time length of the negative pressure source according to the gas extraction time.

[0015] Further, the trace gas measuring device obtains the dynamic gas generation amount of the battery, and outputs an instantaneous flow according to the gas generation dynamics, the instantaneous flow showing the peak value and the valley value of the battery gas generation rate.

[0016] Further, the control system receives and analyzes the instantaneous flow, and controls the negative pressure source to adjust the negative pressure in real time.

[0017] Further, when the pipeline leaks, the trace gas measuring device and the negative pressure source are used to measure the leakage flow.

[0018] Further, a first valve is arranged on the pipeline between the battery and the trace gas measuring device, the first valve is closed, the negative pressure source is opened, there is a pressure difference between the gas inlet end and the gas outlet end of the trace gas measuring device, and the trace gas measuring device can measure the leakage gas flow.

[0019] Further, a liquid conductivity sensor is arranged near the pipe close to the battery, and the liquid conductivity sensor is used to monitor whether the electrolyte in the battery is extracted.

[0020] Further, when the liquid conductivity sensor detects that the conductivity is higher than a threshold value, a feedback signal is fed to the control system, and the control system controls the negative pressure source to adjust the negative pressure in real time.

[0021] Further, the priority of the control system in controlling the negative pressure source according to the liquid conductivity sensor is higher than the priority of the control system in controlling the negative pressure source according to the instantaneous flow rate.

[0022] Further, the micro gas measurement device uses the bubble method to measure the micro gas flow rate.

[0023] The embodiment of the present application provides another technical solution: a battery negative pressure formation device, comprising a negative pressure source and a micro gas measurement device, the gas inlet end of the micro gas measurement device is connected to a battery to be formed through a pipe, and the gas outlet end of the micro gas measurement device is connected to the negative pressure source through a pipe.

[0024] Compared with the prior art, the present application has the following beneficial effects:

[0025] 1. The micro gas measurement device is introduced into the battery negative pressure formation process, and the micro gas measurement device can obtain the gas volume of the gas released by the battery in real time, that is, the gas extraction time of the battery negative pressure formation can be calculated, thereby improving the production efficiency.

[0026] 2. According to the real-time obtained gas production rate, the control system can dynamically adjust the size of the negative pressure in real time, and when the gas production rate is in a slow stage, the control system will increase the size of the negative pressure, so that the negative pressure source can continuously maintain the optimal negative pressure size in the whole gas extraction process, thereby shortening the process time and improving the production efficiency, and at the same time, the pressure size can be maintained within the upper and lower threshold values allowed by the process, thereby reducing the probability of misextracting the electrolyte.

[0027] 3. The micro gas measurement device measures the volume of the gas flowing through the gas based on the pressure difference between the gas inlet end and the gas outlet end. The cooperation of the micro gas measurement device and the negative pressure source can accurately measure the system leakage and the leakage rate, which can be used as a leakage background value, thereby improving the accuracy of the gas volume of the battery output gas measured by the micro gas measurement device.

[0028] 4. The liquid conductivity sensor can be used to measure the misextracted electrolyte, and if the control system is used, the negative pressure size can be automatically and real-time adjusted, thereby reducing the negative pressure gas extraction rate, ensuring that the electrolyte will not be extracted, and avoiding the problem of electrolyte crystallization in the pipe. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 A schematic diagram of a battery negative pressure formation device provided by an embodiment of the present application;

[0030] Figure 2 A schematic diagram of a trace gas measuring device of a battery negative pressure formation device provided by an embodiment of the present application;

[0031] Figure 3 A side view schematic diagram of a trace gas measuring device of a battery negative pressure formation device provided by an embodiment of the present application;

[0032] Figure 4 A schematic diagram of a cumulative gas production flow in a formation process of a battery negative pressure formation device provided by an embodiment of the present application;

[0033] Figure 5 A schematic diagram of an instantaneous gas production flow in a formation process of a battery negative pressure formation device provided by an embodiment of the present application. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of the present application.

[0035] Please refer to Figure 1 The present application provides a battery negative pressure formation device, which specifically comprises a negative pressure source and a trace gas measuring device. The gas inlet end of the trace gas measuring device is connected to the battery to be formed through a pipeline, and the gas outlet end of the trace gas measuring device is connected to the negative pressure source through a pipeline. The data of the existing gas production and the pumping time are statistically analyzed, and a calculation model of the gas production and the pumping time is obtained through software analysis. The trace gas measuring device is introduced into the battery negative pressure formation process, and the real-time gas production of the battery is measured by using the trace gas measuring device. According to the calculation model of the gas production and the pumping time, the pumping time of the battery negative pressure formation can be calculated and predicted in real time. Meanwhile, the control system can adjust the negative pressure of the negative pressure source in real time according to the real-time gas production of the battery, so as to improve the production efficiency. The trace gas measuring device is used to measure the gas production in the present embodiment, so that the specific pumping time can be calculated, and the working time of the negative pressure source is set according to the pumping time, so that the pumping time of the battery to be formed can be set.

[0036] Please refer to Figure 1 、 Figure 4 and Figure 5The micro gas measuring device acquires the dynamic gas production of the battery, i.e. the cumulative flow, and outputs a gas instantaneous flow curve according to the gas production dynamics, which shows the change trend of the battery gas production rate. During the formation process of the battery, the amount of gas produced is not constant, and the gas production varies at different process stages.

[0037] Referring to Figure 1 , Figure 2 and Figure 3 , the micro gas measuring device measures the micro gas flow by the bubble method. The micro gas measuring device measures the volume flow of the flowing gas based on the pressure difference between the gas inlet end and the gas outlet end, and the bubble method can accurately measure the gas volume produced by the battery. Preferably, the micro gas measuring device includes a V-shaped tube body ( Figure 2), the pipe body includes a first section 1, a second section 2 and a third section 3 connected with the first section 1, the third section 3 is vertically arranged, the connection of the first section 1 and the second section 2 is a gas outlet, and the second section 2 is vertically arranged. The angle between the first section 1 and the second section 2 is controlled to be between 25° and 75°, which can ensure that the liquid medium in the first section 1 can be smoothly pressed to the second section 2 due to the gas inlet pressure, and a gas bubble is formed at the gas outlet. If the angle is too large, the liquid medium flow resistance is too large, which leads to uneven flow rate, and further leads to uneven rate and size of the gas bubble. If the angle is too small, the generated gas bubble is difficult to cross the gas outlet into the second section 2, which also leads to inaccurate measurement. An imaging sensor 4 is used to calculate the size and volume of the gas bubble, the fixed range of the sensor on the vertical plane of the gas outlet is between -5 and +5 mm, so that the volume of the gas bubble can be better controlled, and the measurement accuracy is improved. The sensor is fixed on the vertical plane near the gas outlet, and the transmission signal of the sensor needs to be calibrated and adjusted according to the shape and position of the gas outlet by a software algorithm to ensure that the gas bubble and the size are accurately detected, and the range should be between -5 and +5 mm. The third section 3 has a gas inlet end, and the vertically arranged gas inlet end 30 is designed to facilitate the gas to enter the micro gas measurement device. Preferably, the second section 2 has a gas outlet end 20 connected to a negative pressure source; the intersection line of the first section 1 and the second section 2 at the upper end is the gas outlet, and the shape of the gas outlet is one of linear, zigzag, hyperbolic and parabolic, and the shape of the gas outlet will affect the size of the gas bubble. The flowing gas enters the pipe body from the gas inlet end 30, and the liquid at the gas inlet end 30 is pressed to the gas outlet end 20; due to the small flow rate of the gas, the liquid column pressure generated by the liquid level rise at the gas outlet end 20 is greater than the pressure generated by the flowing gas entering the pipe body, so that the gas is squeezed into the liquid; when the gas passes through the gas outlet and enters the liquid, a local low-pressure area is formed, which causes the surrounding liquid to move to the low-pressure area, forming a flow vortex. The vortex makes the gas-liquid interface membrane bulge, and accumulates to a certain volume (usually more than half a sphere), and then the opening is closed under the action of surface tension, thereby forming a gas bubble. The size of the gas bubble is affected by the angle between the first section 1 and the second section 2 and the shape of the gas outlet. Under the condition that the angle between the first section 1 and the second section 2 and the shape of the gas outlet are fixed, the size of the generated gas bubble is also constant. The gas bubble enters the second section 2 from the gas outlet and rises until the liquid surface breaks. When the gas bubble is formed at the gas outlet, the sensor 4 can be used to measure the gas bubble. The sensor 4 can be an imaging sensor, which calculates the volume by the size of the gas bubble. The sensor 4 can also be an optical, ultrasonic or electromagnetic sensor, which measures the number of gas bubbles to accumulate the volume and further obtains the instantaneous flow rate. Preferably, the sensor is an optical sensor.

[0038] Please refer to Figure 1, the control system receives and analyzes the instantaneous flow rate of the generated gas, and the control system can adjust the negative pressure of the negative pressure source in real time according to the instantaneous flow rate. When the instantaneous flow rate is obtained, the instantaneous flow rate is also real-time, and the control system can realize the automatic dynamic adjustment of the battery negative pressure formation. The negative pressure will no longer be a constant value and can be adjusted in real time. When the gas production of the same batch of batteries is significantly different, the formation efficiency can be kept at the highest state. For example, when the gas production rate is in the fast stage, the negative pressure is too high, and the control system will reduce the negative pressure. The negative pressure can be adjusted and reduced, and the electrolyte can also be prevented from being extracted too much. When the gas production rate gradually slows down, the negative pressure can be appropriately increased to speed up the gas extraction process, so that the negative pressure source can maintain the optimal negative pressure during the entire gas extraction process, thereby shortening the process time and improving the production efficiency. Negative pressure formation is a common formation process. The negative pressure source is used to adjust the gas pressure in the battery, and the negative pressure vacuum system is used to extract the gas generated during the battery formation process from the liquid injection port of the battery. The gas generated during the formation process can be discharged in time to ensure the stability and consistency of the SEI film, and the electrolyte infiltration effect can also be accelerated. At present, the process time is relatively long, which depends on different battery sizes and capacities, and can be from several hours to several dozen hours. Because the battery gas production can only be calculated based on the experience data obtained in the early laboratory stage, there is still a difference with the actual production process. In order to ensure that the expected effect of fully discharging the gas is achieved, the process time is generally designed to be longer. After real-time monitoring of the battery gas production during the negative pressure formation process, the gas extraction negative pressure is dynamically adjusted, which can effectively optimize the negative pressure formation time and improve the production efficiency.

[0039] Please refer to Figure 1 When the pipeline leaks, the trace gas measuring device and the negative pressure source can be used to measure the leakage flow. In the prior art, a negative pressure gauge is generally connected in the pipeline to evaluate the pipeline leakage by the pressure drop in a certain time. However, this method cannot accurately obtain the pipeline leakage, which may lead to the leakage gas being included in the gas production when measuring the gas production, resulting in inaccurate data. The combination of the trace gas measuring device and the negative pressure source can accurately measure the leakage flow, which can be used as a leakage background value to improve the accuracy of the battery gas production measured by the trace gas measuring device.

[0040] Please refer to Figure 1 A first valve a is arranged on the pipeline between the battery and the trace gas measuring device A. When the first valve a is closed and the negative pressure source B is opened, there is a pressure difference between the gas inlet end and the gas outlet end of the trace gas measuring device A, and the trace gas measuring device A can measure the leakage gas flow. After the negative pressure source B is started, a uniform negative pressure is formed in the entire pipeline, and the negative pressure is preferably between-20 and-100 kPa. For example Figure 1, the left side of the negative pressure source B is the first negative pressure port c1, and the negative pressure is provided for the gas inlet end of the trace gas measuring device A, the right side of the negative pressure source B is the second negative pressure port c2, and the negative pressure is provided for the gas outlet end of the trace gas measuring device A, at this time, the first valve a is closed, when there is a leakage in the pipeline, it will cause the pressure difference between the gas inlet end and the gas outlet end of the trace gas measuring device A, and the pressure difference can generate bubbles in the trace gas measuring device A, and the trace gas measuring device A can measure the leakage gas flow, so as to obtain the leakage background value. Preferably, it further comprises a tee joint and a second valve b, wherein the three ports of the tee joint are respectively connected with the first valve a, the second valve b and the gas inlet end of the trace gas measuring device A, the first valve a is opened, the second valve b is closed, and the battery is controlled to be charged and discharged to be formed. Specifically, when the pipeline system is leak hunting, the first valve a needs to be closed and the second valve b needs to be opened. After connecting the battery for formation process, the first valve a needs to be opened and the second valve b needs to be closed. At this time, the battery starts to produce gas, which causes the pressure of the gas inlet end of the trace gas measuring device A to be too high, so that there is a pressure difference between the gas inlet end and the gas outlet end of the trace gas measuring device A, and the trace gas measuring device A can measure the gas flow, and the leakage background value is deducted, that is, the gas production amount in the formation process of the battery under negative pressure condition is obtained. Preferably, the first valve a can be arranged at the position close to the battery in the pipeline, or can be directly connected with the battery, so as to avoid that when the pipeline between the battery and the first valve a leaks, it cannot be detected.

[0041] Please refer to Figure 1 A liquid conductivity sensor is arranged at the position close to the battery in the pipeline, and whether the electrolyte in the battery is extracted is monitored by the liquid conductivity sensor. Preferably, when the liquid conductivity sensor detects that the conductivity is higher than the set threshold value, the control system is fed back with a signal, and the control system controls the negative pressure source B to adjust the negative pressure in real time. When the electrolyte leaks from the battery due to the too high negative pressure, since the electrolyte is a high-conductivity liquid, the liquid conductivity sensor detects that the conductivity is higher than the threshold value at this time, and feeds back a signal to the control system, so as to adjust the size of the air extraction negative pressure, thereby reducing the negative pressure air extraction rate, ensuring that the electrolyte will not be extracted, and avoiding the problem of electrolyte crystallization in the pipeline. The control system can automatically adjust the size of the negative pressure, thereby ensuring that the electrolyte will not be extracted.

[0042] Please refer to Figure 1, the priority of the control system according to the liquid conductivity sensor to control the negative pressure source B is greater than the priority of the control system according to the instantaneous flow to control the negative pressure source B. By defining the control priority, when the magnitude of the negative pressure controlled according to the liquid conductivity sensor conflicts with the magnitude of the negative pressure controlled according to the instantaneous flow, for example, when the time node gas production is high, the negative pressure needs to be increased, but after increasing, the electrolyte is extracted, at this time, the negative pressure should be reduced according to the priority to ensure that the electrolyte is not lost. According to the priority, the gas extraction of the method is more reasonable and reliable, and the efficiency of the negative pressure formation operation is higher.

[0043] Please refer to Figure 1 The embodiment of the application provides a battery negative pressure formation method for the device. The method comprises the following steps: S1, connecting a to-be-formed battery, a trace gas measuring device and a negative pressure source in sequence through a pipeline; S2, charging the battery, the battery generates gas, the negative pressure source is started, and the negative pressure source sucks the gas generated by the battery into the pipeline; S3, the trace gas measuring device measures the gas amount of the gas passing through the trace gas measuring device; S4, calculating a negative pressure gas extraction time according to the gas amount measured by the trace gas measuring device and in combination with the negative pressure of the negative pressure source; and S5, setting the working time length of the negative pressure source according to the gas extraction time. The trace gas measuring device is introduced into the battery negative pressure formation process, the gas amount of the gas released by the battery is obtained by using the trace gas measuring device, the gas extraction time of the battery negative pressure formation is calculated, and therefore the production efficiency is improved. Specifically, in the existing battery negative pressure formation operation, the negative pressure gas extraction time is usually estimated according to experience, and a relatively long negative pressure gas extraction time is set to ensure that the gas can be completely extracted, and therefore the production efficiency is reduced. The embodiment ingeniously uses the trace gas measuring device to measure the gas amount of the gas, so that the specific gas extraction time can be calculated, and the working time length of the negative pressure source is set according to the gas extraction time, so that the gas extraction time of the to-be-formed battery in this batch can be set.

[0044] Although the embodiments of the application have been shown and described, it can be understood by those skilled in the art that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and spirits of the application, and the scope of the application is defined by the appended claims and their equivalents.

Claims

1. A battery negative voltage formation method, characterized by, The method comprises the following steps: S1, connecting a battery to be formed, a trace gas measuring device and a negative pressure source in sequence through a pipeline, S2, charging the battery, the battery generating gas, starting the negative pressure source, and the negative pressure source sucking the gas generated by the battery into the pipeline, S3, the trace gas measuring device measuring the amount of gas passing through it, S4, calculating the negative pressure gas extraction time according to the amount of gas measured by the trace gas measuring device and in combination with the negative pressure of the negative pressure source, S5, setting the working time of the negative pressure source according to the gas extraction time, The trace gas measuring device obtains the dynamic gas generation amount of the battery and outputs instantaneous flow according to the dynamic gas generation, and the instantaneous flow shows the peak and valley values of the battery gas generation rate, The control system receives and analyzes the instantaneous flow, and controls the negative pressure source to adjust the negative pressure in real time, A liquid conductivity sensor is arranged near the battery in the pipeline to monitor whether the electrolyte in the battery is extracted, and when the liquid conductivity sensor detects that the conductivity is higher than the threshold value, a feedback signal is fed back to the control system, the control system controls the negative pressure source to adjust the negative pressure in real time, and the priority of the control system to control the negative pressure source according to the liquid conductivity sensor is higher than the priority of the control system to control the negative pressure source according to the instantaneous flow.

2. The battery negative voltage formation method of claim 1, wherein: When the pipeline leaks, the trace gas measuring device and the negative pressure source are used to measure the leakage flow.

3. The battery negative voltage formation method of claim 2, wherein: A first valve is arranged on the pipeline between the battery and the trace gas measuring device, the first valve is closed, the negative pressure source is opened, there is a pressure difference between the gas inlet end and the gas outlet end of the trace gas measuring device, and the trace gas measuring device can measure the leakage gas flow.

4. The battery negative voltage formation method of claim 1, wherein: The trace gas measuring device uses the bubble method to measure the trace gas flow.

5. A battery negative voltage formation apparatus, characterized by: The method comprises the following steps: S1, connecting a battery to be formed, a trace gas measuring device and a negative pressure source in sequence through a pipeline, S2, charging the battery, the battery generating gas, starting the negative pressure source, and the negative pressure source sucking the gas generated by the battery into the pipeline, S3, the trace gas measuring device measuring the amount of gas passing through it, S4, calculating the negative pressure gas extraction time according to the amount of gas measured by the trace gas measuring device and in combination with the negative pressure of the negative pressure source, S5, setting the working time of the negative pressure source according to the gas extraction time, The trace gas measuring device obtains the dynamic gas generation amount of the battery and outputs instantaneous flow according to the dynamic gas generation, and the instantaneous flow shows the peak and valley values of the battery gas generation rate, The control system receives and analyzes the instantaneous flow, and controls the negative pressure source to adjust the negative pressure in real time, A liquid conductivity sensor is arranged near the battery in the pipeline to monitor whether the electrolyte in the battery is extracted, and when the liquid conductivity sensor detects that the conductivity is higher than the threshold value, a feedback signal is fed back to the control system, the control system controls the negative pressure source to adjust the negative pressure in real time, and the priority of the control system to control the negative pressure source according to the liquid conductivity sensor is higher than the priority of the control system to control the negative pressure source according to the instantaneous flow. When the pipeline leaks, the trace gas measuring device and the negative pressure source are used to measure the leakage flow. A first valve is arranged on the pipeline between the battery and the trace gas measuring device, the first valve is closed, the negative pressure source is opened, there is a pressure difference between the gas inlet end and the gas outlet end of the trace gas measuring device, and the trace gas measuring device can measure the leakage gas flow. The trace gas measuring device uses the bubble method to measure the trace gas flow.

Images