Device and method for measuring water content of battery cell

Abstract

The invention provides equipment and a method for measuring the water content of a battery cell, which can be applied to the technical field of battery cell manufacturing and detection. The device comprises a first space and a laser detector. The first space is used for being in airtight communication with the interior of a to-be-detected battery cell and can be vacuumized to a first target vacuum degree, so that moisture of the to-be-detected battery cell is gasified and overflows into the to-be-detected battery cell; the laser detector is used for emitting laser with target wavelength and incident light intensity to the gas in the first space and measuring the transmission light intensity of the laser after being absorbed by the gas with the target light path; wherein the target wavelength is a moisture characteristic absorption wavelength, and the incident light intensity, the transmission light intensity and the target optical path are used for calculating the moisture content of the to-be-measured battery cell based on the characteristic absorption characteristic of moisture. The device and the method for measuring the water content of the battery cell provided by the invention can realize lossless, rapid and high-sensitivity water content measurement.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of battery cell manufacturing and detection, and in particular to a battery cell moisture content measuring device and method. BACKGROUND

[0002] With the vigorous development of new energy vehicles, electronic devices, energy storage industries and other fields, battery cells as the core components have also been widely researched and applied, and various types of battery cell production capacity have rapidly expanded. In the production and use of battery cells, the moisture content has an important influence on the performance and life of the battery cells, and too high or too low moisture content can cause problems such as capacity attenuation, internal resistance increase, and unstable electrochemical reaction of the battery cells, thereby affecting the safety and reliability of the battery cells and increasing the overall risk of the power system. In order to ensure normal power supply of the battery cells and stable operation of the power equipment, the moisture content of the battery cells usually needs to be controlled within a reasonable range. In related technologies, the detection of the moisture content of the battery cells mostly has problems such as destructiveness, non-real-time, low efficiency, and high cost, and the traditional battery cell moisture content detection method has become a bottleneck restricting the further improvement of the production efficiency and yield of the battery cells. SUMMARY

[0003] In view of the above problems, the present application provides a battery cell moisture content measuring device and method, which aims to quickly, non-destructively and highly sensitively detect the moisture content of the battery cells.

[0004] According to a first aspect of the present application, a battery cell moisture content measuring device is provided, comprising: a first space for airtight communication with the inside of a battery cell to be measured, which can be vacuumed to a first target vacuum degree so that the moisture of the battery cell to be measured is gasified and then overflowed into the first space; and a laser detector for emitting laser of a target wavelength and an incident light intensity to the gas in the first space, and measuring the transmitted light intensity after the laser passes through the gas with a target optical path; wherein the target wavelength is a moisture characteristic absorption wavelength, and the incident light intensity, the transmitted light intensity and the target optical path are used to calculate the moisture content of the battery cell to be measured based on the characteristic absorption characteristics of the moisture.

[0005] According to an embodiment of the present application, the first space is also used to place the battery cell to be measured, which can be vacuumed to the first target vacuum degree so that the moisture of the battery cell to be measured placed therein is gasified and then overflowed.

[0006] According to an embodiment of the present application, the first space includes an electric core test cabin and a gas absorption pool, a sealing door is arranged between the electric core test cabin and the gas absorption pool, the gas absorption pool is in airtight communication or isolation with the electric core test cabin through opening and closing of the sealing door; the electric core test cabin is used for placing a to-be-tested electric core, and can be vacuumized to a first target vacuum degree, so that moisture in the to-be-tested electric core placed therein is gasified and overflowed; the gas absorption pool can be vacuumized to a second target vacuum degree, and the second target vacuum degree is higher than the first target vacuum degree; and a laser detector is used for emitting laser of a target wavelength and an incident light intensity to gas in the gas absorption pool.

[0007] According to an embodiment of the present application, the first target vacuum degree is 100-500 Pa.

[0008] According to an embodiment of the present application, the volume of the gas absorption pool is ≤0.2 L.

[0009] According to an embodiment of the present application, the second target vacuum degree is ≤0.001 Pa, and an absolute value of a change amount of the water content data within a predetermined time under the condition that the sealing door is closed is ≤30 ppm.

[0010] According to an embodiment of the present application, the electric core test cabin is provided with a sealing door used for placing the to-be-tested electric core, the sealing door is sealed through a rubber sealing ring with a metal support, and the outgassing rate of the electric core test cabin is ≤1.3*10 -5 L / s.

[0011] The second aspect of the present application provides an electric core water content measurement method, including: increasing the vacuum degree of the inside of a to-be-tested electric core and a first space to a first target vacuum degree, so that moisture in the to-be-tested electric core is gasified and overflowed into the first space, wherein the inside of the to-be-tested electric core is in airtight communication with the first space; emitting laser of a target wavelength and an incident light intensity to gas in the first space, measuring the transmission light intensity of the laser after gas absorption of a target optical path, wherein the target wavelength is a characteristic absorption wavelength of moisture; and obtaining the water content of the to-be-tested electric core based on the characteristic absorption characteristics of the moisture according to the incident light intensity, the transmission light intensity and the target optical path.

[0012] According to an embodiment of the present application, the increasing of the vacuum degree of the inside of the to-be-tested electric core and the first space to the first target vacuum degree includes: placing the to-be-tested electric core in a sealed first space; and increasing the vacuum degree of the first space to the first target vacuum degree.

[0013] According to the embodiment of the present application, the first space includes a sealed battery cell test cabin and a gas absorption pool, and the method comprises: placing the battery cell to be tested in the battery cell test cabin, vacuumizing the battery cell test cabin to a first target vacuum degree, so that the moisture in the battery cell overflows into the battery cell test cabin; mixing the gas in the battery cell test cabin with the gas absorption pool; the vacuum degree of the gas absorption pool is pre-raised to a second target vacuum degree, wherein the second target vacuum degree is lower than the first target vacuum degree; emitting laser of a target wavelength and an incident light intensity to the gas of the gas absorption pool, measuring the transmission light intensity of the gas after the laser passes through the target optical path; and obtaining the water content of the battery cell to be tested based on the characteristic absorption characteristics of the moisture according to the incident light intensity, the transmission light intensity and the target optical path.

[0014] The battery cell water content measurement device and method provided by the present application places the whole battery cell in a sealed test cabin, uses low vacuum to promote the natural gasification of the internal moisture of the battery cell, and detects the water vapor content by laser. The measurement process does not need to damage the structure of the battery cell, and the battery cell remains intact after measurement, reducing the measurement loss and additional cost; the laser spectrum absorption response time is millisecond level, realizing rapid and real-time monitoring of the water content of the battery cell; a long reflection optical path is designed in a limited space, which is combined with a high vacuum background environment to significantly enhance the detection capability of the weak moisture signal, realizing high-sensitivity water content measurement. The non-destructive, rapid and high-sensitivity battery cell water content measurement device and method provided by the present application effectively solves the problems of traditional battery cell water content measurement methods in terms of destructiveness, efficiency, cost and coverage. BRIEF DESCRIPTION OF DRAWINGS

[0015] The above content and other purposes, features and advantages of the present application will be more clearly understood through the following description of the embodiments of the present application with reference to the accompanying drawings, in which:

[0016] Figure 1 The structure diagram of a battery cell water content measurement device according to an embodiment of the present application is schematically shown;

[0017] Figure 2 The structure diagram of a second battery cell water content measurement device according to an embodiment of the present application is schematically shown;

[0018] Figure 3 The structure diagram of an automatic system of a battery cell water content measurement device according to an embodiment of the present application is schematically shown;

[0019] Figure 4 The measurement result diagram of a battery cell water content according to an embodiment of the present application is schematically shown; and

[0020] Figure 5 The measurement result diagram of a battery cell water content according to an embodiment of the present application is schematically shown.

[0021] In the figure, 1, the battery to be tested; 14, the air hole; 2, the conveyor belt; 3-5, the sealing door; 6, the battery test cabin; 7-8, the vacuum pump; 9, the gas absorption cell; 10, the laser detector; 11, the host computer; 12-13, the vacuum pump pipeline valve; 20, the first space; 30, the laser. DETAILED DESCRIPTION

[0022] Hereinafter, embodiments of the present application will be described with reference to the accompanying drawings. It should be understood, however, that the description is merely illustrative of the present application and in no way limits the scope of the present application. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the present application. However, it will be apparent to one skilled in the art that one or more embodiments of the present application can be practiced without these specific details. In other instances, well-known structures and functions have been omitted or simply referenced in order not to obscure an aspect of the present application.

[0023] The terms used herein are merely used to describe specific embodiments and are not intended to limit the present application. The terms "include" and "have" and the like used herein indicate the presence of the described features, steps, operations, and / or components but do not preclude the presence or addition of one or more other features, steps, operations, or components.

[0024] All terms used herein, including technical and scientific terms, have the same meanings as those generally understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having meanings consistent with the context of the present description, and should not be interpreted in an idealized or excessively formal manner.

[0025] In the case of using expressions similar to "at least one of A, B, and C, etc.", it should generally be interpreted to include at least one of the items enumerated, but not limited to the items enumerated (e.g., "a system having at least one of A, B, and C" should include a system having A alone, a system having B alone, a system having C alone, a system having A and B together, a system having A and C together, a system having B and C together, and / or a system having A, B, and C together, etc.).

[0026] In the process of manufacturing battery cells, the moisture content has a critical impact on the performance thereof. Before the process of filling electrolyte, the residual moisture in the electrode and the separator is generally removed thoroughly through a baking process. In order to ensure the quality of the battery cell, the moisture content of the battery cell after baking must be detected, and the qualified individual is screened out, so as to improve the safety and comprehensive performance of the battery cell. Since the moisture content of the qualified battery cell is extremely low, the sensitivity of the detection method is required to be high.

[0027] Currently, the industry mainly uses Karl Fischer coulometry method to detect the water content of the baked battery cell. The method generally includes the following steps: placing the battery cell to be tested in an inert gas protection environment, mixing and stirring with the electrolyte after sampling, extracting the moisture, and then titrating and analyzing, and calculating the water content according to the amount of electricity consumed in the electrolysis process. However, this method not only has complicated operation steps and takes a long time, but more importantly, it can cause irreversible damage to the battery cell, resulting in rising process costs, so it is difficult to achieve comprehensive and accurate detection of each battery cell. Other methods such as the weighing method and the insulation resistance value detection method cannot meet the precise measurement requirements due to their own sensitivity limitations, and therefore are generally only used for rough verification. Based on this, the present application aims to provide a battery cell water content detection device and method that can simplify the process and be fast and sensitive.

[0028] Embodiments of the present application provide a battery cell water content measurement device, comprising: a first space and a laser detector.

[0029] Figure 1 The structure of a battery cell water content measurement device according to an embodiment of the present application is schematically shown.

[0030] As shown in Figure 1 , the first space 20 is used to communicate with the inside of the battery cell to be tested 1 through the vent hole 14, and the first space 20 can be vacuumed to a first target vacuum degree so that the moisture of the battery cell to be tested 1 is vaporized and overflowed into the first space 20; the laser detector is used to emit laser 30 with a target wavelength and a target light intensity (incident light intensity) to the gas in the first space 20, and measure the transmitted light intensity absorbed by the gas after the laser passes through the target optical path. The vent hole 14 may, for example, be a liquid injection hole of the battery cell. The first space 20 can be in airtight communication with the vent hole 14 of the battery cell to be tested 1 through a gas pipe, realizing communication with the inside of the battery cell to be tested 1.

[0031] The laser will attenuate after passing through the medium, and different media have their own specific absorption wavelengths.

[0032] In the present embodiment, the target wavelength is the characteristic absorption wavelength of moisture, and the measured incident light intensity, transmitted light intensity and target optical path are used to calculate the water content of the battery cell to be tested based on the characteristic absorption characteristics of moisture. The measurement principle is based on the Beer-Lambert law, and the calculation formula is as follows:

[0033] (1)

[0034] wherein is the incident light intensity, i.e. the light intensity emitted by the laser; is the transmitted light intensity, i.e. the intensity of the light remaining after passing through the sample to be tested; is the absorbance, which is the logarithm of the ratio of incident light intensity to transmitted light intensity; is the molar absorption coefficient (unit: L·mol - ¹·cm - ¹), which is a constant that measures the ability of a specific substance to absorb light at a specific wavelength. The larger the value, the stronger the corresponding substance's ability to absorb light. is the concentration of the light-absorbing substance. For the gas molecules to be measured in this application, the unit is mol / L. is the optical path, which is the distance the light travels in the light-absorbing substance. The unit is centimeters. , the intensity of the incident light , the intensity of the transmitted light , the molar absorption coefficient of water , the optical path , the corresponding water molecule concentration

[0035] In this embodiment, a first space in airtight communication with the interior of the battery to be measured is created and vacuumed, causing the residual water in the battery to naturally vaporize and overflow into the space under pressure difference. The amount of water vapor absorbed by the laser at a specific wavelength is measured using laser absorption spectroscopy, allowing direct calculation of the water molecule concentration. This method directly and highly sensitively measures water content, overcoming the low sensitivity and inaccuracy of indirect methods such as weighing and insulation resistance. More importantly, this method does not require the destruction of the battery structure, allowing for full inspection of each battery and avoiding sample waste and subsequent processing costs. This method lays the foundation for rapid and real-time battery water content detection.

[0036] In some preferred embodiments of the present application, the first space is also used to place the battery to be measured, which can be vacuumed to a first target vacuum degree to allow the water in the battery to be placed therein to vaporize and overflow.

[0037] Figure 2 The structure diagram of a second battery water content measurement device according to an embodiment of the present application is schematically shown.

[0038] As shown in Figure 2 , the battery to be measured 1 can be placed entirely in the first space 20 that can be vacuumed, ensuring that the water in the battery can be quickly and fully released into the first space 20, avoiding the absorption of water from the outside of the battery to be measured 1 into the first space 20 due to poor airtightness at the vent hole 14, thereby ensuring the efficiency and accuracy of the measurement.

[0039] Figure 3 The structure diagram of an automated system of a battery water content measurement device according to an embodiment of the present application is schematically shown.

[0040] In some preferred embodiments of the present application, as Figure 3As shown, the first space includes a cell testing chamber 6 and a gas absorption cell 9. The cell testing chamber 6 is used to place the cell under test, and it can be evacuated to a first target vacuum level so that the moisture in the cell under test placed therein will vaporize and overflow. The gas absorption cell 9 can be evacuated to a second target vacuum level, which is higher than the first target vacuum level. A sealing door 5 is provided between the cell testing chamber 6 and the gas absorption cell 9. The gas absorption cell 9 can be airtightly connected to or isolated from the cell testing chamber 6 by opening and closing the sealing door 5. The laser detector 10 is used to emit laser light of the target wavelength and incident light intensity into the gas in the gas absorption cell 9.

[0041] The battery cell under test is isolated in the gas testing environment and placed separately in the cell testing chamber 6. This is to prevent excessive accumulation of moisture, which may be present in the cell or the environment, in the gas absorption cell 9 after multiple measurements, thus affecting the baseline value of the moisture content measurement. The independent gas absorption cell can be evacuated to a higher secondary target vacuum level, reducing the background moisture value of the measuring equipment. After a measurement is completed, the gas absorption cell 9 can be isolated and purified to prepare for the next measurement without waiting for the entire system to reach a high vacuum.

[0042] During the measurement process, according to the law of mixed gases, the product of the pressure and volume after mixing is equal to the sum of the products of the pressure and volume of the cell test chamber and the gas absorption pool before mixing. Based on this, the gas pressure during the measurement can be estimated.

[0043] This embodiment employs an isolated design between the cell testing chamber and the gas absorption cell to prevent excessive accumulation of moisture, which may be present in the cell or environment, in the gas absorption cell after multiple measurements, thus affecting the baseline value for moisture content measurement. This avoids measurement errors caused by residual moisture inside the equipment and simultaneously achieves efficient circulation and long-term stability of the moisture content measurement equipment.

[0044] In the embodiments of this application, the first target vacuum degree is 100-500 Pascals.

[0045] like Figure 3 As shown, vacuum pump 7 is used to evacuate the cell testing chamber 6 until the first target vacuum level is reached. Under low vacuum conditions, the boiling point of water can be approximately calculated using the Antoné equation:

[0046] (2)

[0047] in It is the boiling point temperature. , and All are constants. The pressure is atmospheric pressure. According to the formula, the boiling point of water under a low vacuum state of 100-500 Pa is close to 0 degrees, and the water in the battery cell will rapidly boil and be converted into gas. In some preferred embodiments, the volume of the battery cell test chamber is less than 2L, and after the battery cell is placed in the chamber, a conventional vacuum pump (with a pumping speed of 5-10 L / s) can quickly pump the chamber to the first target vacuum degree in 20-30 seconds. In some embodiments, the first target vacuum degree can be 200, 300, 400, or any value between 100-500.

[0048] In this embodiment, the first target vacuum degree is set to a low boiling point of water, which can promote the rapid gasification of residual moisture in the battery cell. At the same time, the time to pump to the first target vacuum degree is controllable, achieving a balance between rapid moisture release and equipment cost and pumping efficiency.

[0049] In the embodiments of the present application, the volume of the gas absorption cell is less than or equal to 0.2L.

[0050] The gas absorption cell 9 provides and maintains the optical path and working environment required for the laser detector 10 to work. When using a specific wavelength laser absorption method to detect low water content, the selected gas absorption cell 9 constructs the longest possible optical path in the smallest possible space size by building a reflective light path. Preferably, the space size in the gas absorption cell 9 can be controlled to be below 0.2L, and under this space size, the optical path of the laser can reach 12m.

[0051] In this embodiment, the volume of the gas absorption cell is set to be less than or equal to 0.2L, which means that the gas absorption cell can be pumped to a high vacuum state more quickly, reducing the equipment preparation time and further improving the detection speed. At the same time, after mixing with the gas in the battery test chamber, a high water vapor concentration can be maintained, which is beneficial to improve the measurement signal strength.

[0052] In the embodiments of the present application, the second target vacuum degree is less than or equal to 0.001 Pa, and the absolute value of the change in water content data in the gas absorption cell within a predetermined time after the sealing door 5 is closed is less than or equal to 30ppm.

[0053] The second target vacuum degree of the gas absorption cell is set to be less than or equal to 0.001 Pa, and in such a high vacuum state, the water content is extremely small, which can maximize the interference of environmental moisture on the measurement accuracy and ensure extremely low background moisture. The second target vacuum degree can also be set to a smaller value, such as 0.0005, 0.0002, or 0.0001 Pa. Preferably, a small molecular pump with a pumping speed greater than 20L / s can maintain the high vacuum state of the gas absorption cell for a long time.

[0054] In the case of the closed sealing door, the water content data needs to set a changing reference to determine whether the gas absorption cell has reached a usable state. Preferably, the water content data can be set to change by no more than 30 ppm within 5 minutes. The change in water content data can also be no more than 20, 10 ppm.

[0055] The embodiment ensures the high sensitivity and reliability of the measurement system, and provides a guarantee for obtaining accurate and repeatable measurement results.

[0056] In the embodiment of the application, the battery test chamber is provided with a sealing door for placing the battery to be tested. The sealing door is sealed by a rubber sealing ring with a metal bracket. The leak rate of the battery test chamber is less than or equal to 1.3x10 -5 L / s.

[0057] The battery starts to be measured as soon as it enters the battery test chamber. It needs to quickly reach the required vacuum condition for testing, so it is necessary to ensure that the battery test chamber has good airtightness. Preferably, the leak rate of the test chamber should be no more than 1.3x10 -5 L / s to avoid external gas interference and cause serious interference to the measurement results.

[0058] Based on the above battery water content measurement device, the application also provides a battery water content measurement method, comprising the following steps S10, S20 and S30.

[0059] Step S10: The vacuum degree of the inside of the battery to be tested and the first space is raised to a first target vacuum degree, so that the moisture in the battery to be tested is gasified and overflowed into the first space, wherein the inside of the battery to be tested is airtight with the first space.

[0060] Step S20: Emit laser of target wavelength and incident light intensity to the gas in the first space, measure the transmitted light intensity after the laser passes through the target optical path, wherein the target wavelength is the characteristic absorption wavelength of moisture.

[0061] Step S30: Obtain the water content of the battery to be tested based on the characteristic absorption characteristics of moisture according to the incident light intensity, the transmitted light intensity and the target optical path.

[0062] In the preferred embodiment of the application, the above step S10 further comprises steps S11 and S12.

[0063] Step S11: Place the battery to be tested in the sealed first space.

[0064] Step S12: Raise the vacuum degree of the first space to a first target vacuum degree.

[0065] In a preferred embodiment of this application, the first space may include a sealed cell testing chamber and a gas absorption pool, and the above step S10 further includes steps S13, S14 and S15.

[0066] Step S13: Place the cell to be tested in the cell testing chamber and evacuate the chamber to the first target vacuum level so that the moisture in the cell can overflow into the cell testing chamber.

[0067] Step S14: Mix the gas in the cell testing chamber with the gas absorption cell.

[0068] Step S15: The vacuum level of the gas absorption cell is pre-raised to a second target vacuum level, wherein the second target vacuum level is lower than the first target vacuum level.

[0069] The above step S20 also includes:

[0070] Step S21: Emit a laser with the target wavelength and incident light intensity into the gas in the gas absorption cell, and measure the intensity of the transmitted light after the laser is absorbed by the gas through the target optical path.

[0071] In some preferred embodiments of this application, the above-described battery cell moisture content measuring device and method can be used in an automated system for measuring battery cell moisture content. The following will use this system as an example to better illustrate the measurement process of the battery cell moisture content measuring device and method provided in this application.

[0072] like Figure 3 As shown, the automated system includes: a battery cell under test 1; a conveyor belt 2; sealed doors 3, 4, and 5; a battery cell testing chamber 6; vacuum pumps 7 and 8; a gas absorption tank 9; a laser detector 10; a host computer 11; and vacuum pump pipeline valves 12 and 13.

[0073] The measurement system is connected to the baking device or an inert gas-protected glove box via conveyor belt 2, allowing the baked battery cell 1 to enter the measurement system through the protective gas, thus preventing moisture in the external atmosphere from affecting the measurement of the battery cell's moisture content. Conveyor belt 2 transports the battery cells to different locations, allowing qualified battery cells to be transferred to the next process device, or returning unqualified battery cells to the baking equipment for re-baking.

[0074] Sealing doors 3, 4, and 5 isolate different compartments, ensuring their internal sealed environment remains undisturbed. Sealing doors typically achieve maximum airtightness through rubber sealing rings with metal supports.

[0075] The vacuum pump 7 of the cell testing chamber evacuates the cell testing chamber 6 from the ambient atmospheric pressure of 100,000 Pascals to the first target vacuum level. With the volume of the cell testing chamber 6 set to no more than 2L, a vacuum pump with a pumping speed of 5~10L / s can evacuate the cell testing chamber 6 to the first target vacuum level in 20~30 seconds.

[0076] The gas absorption cell 9 is vacuumed to a second target vacuum degree by the gas absorption cell vacuum pump 8, usually a small molecular pump with a pumping speed greater than 20 L / s, which can maintain the high vacuum state of the gas absorption cell for a long time.

[0077] The molar absorption coefficient of water and the wavelength of the laser have a nonlinear relationship. A specific wavelength has better sensitivity for water content measurement. The laser can obtain a larger water molar absorption coefficient near the wavelength of 1450 nm. Within a certain range, the larger the wavelength of the laser, the weaker the penetration and the easier it is to saturate, and the smaller the measurement range. The smaller the wavelength, the stronger the penetration and the larger the range, but the corresponding absorption coefficient is small and the measurement sensitivity is low. Considering the characteristics of high temperature and extremely low humidity of the battery and the engineering cost, the preferred wavelength of the laser used in this embodiment is 1368 nm. A laser detector 10 (such as a collimator) is arranged at the end of the optical path to receive the laser and measure it. This detection structure can accurately measure water molecules in the environment, and the measurement sensitivity can reach one part in a million, with a response speed of milliseconds.

[0078] The vacuum pump pipe valves 12 and 13 are closed after the battery test chamber 6 and the gas absorption cell 9 are pumped to the first target vacuum degree and the second target vacuum degree, respectively, to prevent the water molecules to be measured from being pumped away from the environment to be measured.

[0079] The host computer 11 is connected to the laser detector 10 and is responsible for receiving, processing, displaying, and recording the battery water content data measured by the laser detector 10 to determine whether the battery is qualified for baking.

[0080] The process of automatically measuring the water content of the battery includes the following steps S100-S600.

[0081] Step S100: Start the vacuum pump 8, open the vacuum pump valve 13, and pump the vacuum degree in the gas absorption cell 9 to less than or equal to 0.001 Pa, and ensure that the absolute value of the change in the water content data read within 5 minutes is less than or equal to 30 ppm.

[0082] Step S200: Open the sealing door 3, place the battery to be measured 1 on the conveyor belt 2, and convey it to the battery test chamber 6 and close the sealing door 3.

[0083] Step S300: Start the vacuum pump 7, open the vacuum pump valve 12, and pump the vacuum degree in the battery test chamber 6 to 100-500 Pa.

[0084] Step S400: Close the vacuum pump valves 12 and 13, and open the sealing door 5 to convert the water in the battery into gas.

[0085] Step S500: Read the water content (ppm) reading displayed on the laser detector 10. Determine whether the cell's water content is qualified based on the standard that "the absolute value of the water content change within 90 seconds is less than or equal to 100 ppm".

[0086] Figure 4 The diagram illustrates the measurement results of the water content of a battery cell conforming to an embodiment of this application.

[0087] like Figure 4 As shown, the water content changed by approximately 15 ppm within 90 seconds, indicating that the water content of the battery cell was within acceptable limits after baking.

[0088] Figure 5 The diagram illustrates the measurement results of water content in a non-standard battery cell according to an embodiment of this application.

[0089] like Figure 5 As shown, the measured water content change was approximately 240 ppm within 90 seconds, indicating that the water content of the battery cell was substandard after baking.

[0090] Step S600: After measurement, close the sealing door 5, open the vacuum pump valve 13, extract any residual moisture from the gas absorption tank 9, and transfer the qualified battery cells to the next stage via the conveyor belt 2 and sealing door 4. Unqualified battery cells return to the drying stage via the sealing door 3 for re-drying, then return to step S100 for the next measurement until the moisture content is within acceptable limits.

[0091] This application provides a device and method for measuring the moisture content of battery cells, utilizing the principle of moisture evaporation in low vacuum and laser spectral detection technology. Its advantages include: enabling non-destructive full inspection of battery cells, reducing testing time from hours to minutes, and achieving non-destructive, rapid, and highly sensitive moisture content measurement through long optical path and high vacuum design. This overcomes the limitations of traditional measurement methods in terms of efficiency, cost, and coverage, providing technical support for improving the quality and efficiency of battery cell production and testing processes and for precise quality control.

[0092] Those skilled in the art will understand that the features described in the various embodiments of this application can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in this application. In particular, the features described in the various embodiments of this application can be combined and / or combined in various ways without departing from the spirit and teachings of this application. All such combinations and / or combinations fall within the scope of this application.

Claims

1. A device for measuring the moisture content of battery cells, characterized in that, include: The first space is used to be in airtight communication with the inside of the battery cell under test. It can be evacuated to the first target vacuum level so that the moisture in the battery cell under test will vaporize and overflow into it. as well as A laser detector is used to emit a laser with a target wavelength and incident light intensity into the gas in the first space, and to measure the transmitted light intensity after the laser is absorbed by the gas through the target optical path; wherein, the target wavelength is the characteristic absorption wavelength of water, and the incident light intensity, transmitted light intensity, and target optical path are used to calculate the water content of the battery cell under test based on the characteristic absorption characteristics of water.

2. The device according to claim 1, characterized in that, The first space is also used to place the battery cell under test, which can be evacuated to a first target vacuum level so that the moisture in the battery cell under test placed therein will vaporize and overflow.

3. The device according to claim 2, characterized in that, The first space includes a cell testing chamber and a gas absorption pool. A sealed door is provided between the cell testing chamber and the gas absorption pool. The gas absorption pool is airtightly connected to or isolated from the cell testing chamber by opening and closing the sealed door. The cell testing chamber is used to place the cell under test. It can be evacuated to a first target vacuum level so that the moisture in the cell under test placed therein will vaporize and overflow. The gas absorption cell can be evacuated to a second target vacuum level, which is higher than the first target vacuum level. The laser detector is used to emit laser light of the target wavelength and incident light intensity into the gas in the gas absorption cell.

4. The device according to claim 3, characterized in that, The first target vacuum level is 100-500 Pascals.

5. The device according to claim 3, characterized in that, The volume of the gas absorption cell is ≤0.2L.

6. The device according to claim 3, characterized in that, The second target vacuum degree is ≤0.001 Pascal, and the absolute value of the change in water content data in the gas absorption cell within a predetermined time is ≤30 ppm when the sealed door is closed.

7. The device according to claim 3, characterized in that, The cell testing chamber is equipped with a sealed door for placing the cell under test. The sealed door is sealed by a rubber sealing ring with a metal support. The leakage rate of the cell testing chamber is ≤1.3×10⁻⁶. -5 L / s.

8. A method for measuring the water content of a battery cell, characterized in that, The method includes: The vacuum level inside the battery cell under test and the first space is increased to the first target vacuum level, so that the moisture in the battery cell under test is vaporized and overflows into the first space, wherein the inside of the battery cell under test is in airtight communication with the first space. A laser with a target wavelength and incident light intensity is emitted into the gas in the first space, and the intensity of the transmitted light after the laser is absorbed by the gas through the target optical path is measured, wherein the target wavelength is the characteristic absorption wavelength of water. The water content of the battery cell under test is obtained based on the incident light intensity, transmitted light intensity, and target optical path, according to the characteristic absorption characteristics of water.

9. The method according to claim 8, characterized in that, Raising the vacuum level inside the battery cell under test and the first space to the first target vacuum level includes: The battery cell to be tested is placed in a sealed first space; Increase the vacuum level of the first space to the first target vacuum level.

10. The method according to claim 8, characterized in that, The first space includes a sealed cell testing chamber and a gas absorption pool, and the method includes: The cell to be tested is placed in the cell testing chamber, and a vacuum is drawn to bring the vacuum level of the cell testing chamber to the first target vacuum level, so that the moisture in the cell overflows into the cell testing chamber. The gas in the cell testing chamber is mixed with the gas in the gas absorption cell; the vacuum level of the gas absorption cell is pre-raised to a second target vacuum level, wherein the second target vacuum level is lower than the first target vacuum level. A laser with a target wavelength and incident light intensity is emitted into the gas in the gas absorption cell, and the intensity of the transmitted light after the laser is absorbed by the gas through the target optical path is measured. The water content of the battery cell under test is obtained based on the incident light intensity, transmitted light intensity, and target optical path, according to the characteristic absorption characteristics of water.

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