Device system and method for on-line detection of baking moisture of battery cell

Abstract

The invention provides a device system and method for on-line detection of battery cell baking moisture, and the method comprises the following steps: (1) placing a battery cell in a baking furnace, filling a furnace chamber with replacement gas through a gas inlet in the baking process, and then storing the replacement gas in a gas storage surge tank through a gas collection pipeline; (2) after the air pressure is stable, performing dew point measurement on the replacement gas in the gas storage surge tank through a dew point meter, and outputting a dew point value to a central control panel for data storage; (3) after the measurement is completed, emptying the replacement gas in the gas storage surge tank through an exhaust valve; and (4) repeating the steps (1)-(3) for at least three times, carrying out data processing on the dew point value obtained each time by using a central control panel, outputting a moisture volatilization curve to determine the baking effect, and carrying out online detection and alarm. According to the method provided by the invention, online monitoring of the water overflow rate and the water content during baking of the cavity can be carried out in real time, measurement errors caused by personnel testing are avoided, and large-scale popularization and application are facilitated.

Description

Technical Field

[0001] This invention belongs to the field of battery manufacturing technology, and relates to a method for online detection of moisture content during battery cell baking, and more particularly to a device system and method for online detection of moisture content during battery cell baking. Background Technology

[0002] During the manufacturing process of lithium-ion batteries, due to environmental control and material characteristics, the positive and negative electrode plates and separators will inevitably carry a certain amount of moisture. However, due to the electrochemical reaction characteristics of the battery cell itself, the battery cell with high moisture content will undergo side reactions, resulting in phenomena such as gas expansion and even black spot lithium deposition, which in turn leads to problems such as decreased cell capacity, increased internal resistance, and poor cycle performance.

[0003] To address these issues, technicians typically add an electrode or separator baking process during cell manufacturing, or bake the entire cell after assembly to remove moisture. To verify thorough drying, a moisture sample is taken from each baking oven and tested offline using a Karl Fischer meter. However, this is a destructive test; while it directly measures the moisture content, it cannot represent the overall moisture level of the entire batch of cells, nor can it monitor moisture changes across the entire batch in real-time. Summary of the Invention

[0004] The purpose of this invention is to provide a device system and method for online detection of moisture content during battery cell baking. The method can monitor the rate of moisture overflow and water content during cavity baking in real time, avoiding measurement errors caused by human testing, and is conducive to large-scale application.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a device system for online detection of moisture content during battery cell baking, the device system comprising a baking oven, a gas storage and pressure stabilizing tank, and a central control panel connected in sequence.

[0007] The baking oven is equipped with an air inlet, and the baking oven and the gas storage and pressure stabilizing tank are connected by a gas collection pipeline.

[0008] The gas storage and pressure stabilizing tank is equipped with a dew point meter and an exhaust valve, and the dew point meter is electrically connected to the central control panel.

[0009] The device system provided by this invention connects the baking oven and the gas storage and pressure stabilizing tank through a gas collection pipeline, enabling real-time and periodic gas collection. A dew point meter is installed on the gas storage and pressure stabilizing tank to measure the dew point value of the gas in real time during the baking process. After converting it into a moisture value, the baking effect can be determined. This achieves online monitoring of the rate of moisture overflow and water content during cavity baking, avoiding measurement errors caused by manual testing. The entire device system has a simple structure, low maintenance cost, and is easy to operate, which is conducive to large-scale promotion and application.

[0010] Preferably, the oven cavity airtightness of the baking oven satisfies the following condition: leakage rate ≤ 5 Pa·L / s.

[0011] Preferably, the pressure-bearing capacity of the gas collection pipeline is ≥1.1MPa, and the air tightness requirement is ≤5Pa / min.

[0012] Preferably, the dew point meter has a range of -80℃ to -20℃ and a detection accuracy of 0.5-2ppm.

[0013] Preferably, the exhaust valve has the functions of automatic exhaust and air blowing for cleaning.

[0014] In a second aspect, the present invention provides a method for online detection of moisture content during battery cell baking using the apparatus system described in the first aspect, the method comprising the following steps:

[0015] (1) Place the battery cell in the baking oven and fill the oven cavity with replacement gas through the air inlet during the baking process. Then, store the replacement gas in the gas storage and pressure stabilizing tank through the gas collection pipeline.

[0016] (2) After the gas pressure stabilizes, the dew point of the replacement gas in the gas storage and pressure stabilizing tank is measured by a dew point meter, and the dew point value is output to the central control panel for data storage.

[0017] (3) After the measurement is completed, the replacement gas in the gas storage and pressure stabilizing tank is emptied through the exhaust valve.

[0018] (4) Repeat steps (1)-(3) at least 3 times, use the central control panel to process the dew point value obtained each time, output the moisture evaporation curve to determine the baking effect and perform online detection and alarm.

[0019] This invention performs real-time periodic gas collection on the battery cells during the baking process. Since there is a direct conversion relationship between dew point value and moisture value, the baking effect can be determined by real-time monitoring of the dew point value change of the replacement gas, and online detection and alarm can be performed. This online detection method is significantly different from the traditional offline sampling detection method. The detection results can represent the moisture level of the entire batch of battery cells, with higher measurement accuracy, improving production efficiency and product quality.

[0020] Preferably, the battery cells in step (1) are sampled and calibrated for moisture content before being placed in the baking oven to obtain the average moisture content T and average weight G of the battery cells before baking.

[0021] Preferably, step (1) involves evacuating the oven cavity before baking begins.

[0022] Preferably, the replacement gas in step (1) includes high-purity nitrogen, and the purity of the high-purity nitrogen is ≥5N and the water content is ≤1ppm.

[0023] Preferably, the time for the air pressure to stabilize in step (2) is 5-15 minutes.

[0024] Preferably, the time for dew point measurement in step (2) is ≥5 min.

[0025] Preferably, in step (3), after the replacement gas is emptied, the gas storage pressure stabilizing tank is also cleaned by blowing air to ensure that the water vapor in the tank is completely removed.

[0026] Preferably, the repetition interval in step (4) is 5-480 min.

[0027] Preferably, the data processing in step (4) includes: converting the dew point value obtained each time into a moisture value H, and calculating the remaining moisture value D of the battery cell after baking by combining the average moisture value T of the battery cell before baking and the average weight G of the battery cell before baking. The calculation formula is as follows:

[0028] D = T - (H1 + H2 + ... + H) n ) / G

[0029] In the above formula, H1 is the moisture value corresponding to the first dew point value, H2 is the moisture value corresponding to the second dew point value, and H... n Let n be the moisture value corresponding to the nth dew point value, where n ≥ 3 and n is a positive integer.

[0030] Preferably, the method for converting the dew point value obtained each time into a moisture value H is performed with reference to a dew point-moisture conversion table.

[0031] Preferably, the baking effect in step (4) is determined based on the stabilization of the moisture evaporation curve.

[0032] Preferably, the online detection and alarm in step (4) are based on the remaining moisture content of the battery cell after baking.

[0033] As a preferred technical solution of the second aspect of the present invention, the method includes the following steps:

[0034] (1) The battery cells are sampled and calibrated to obtain the average moisture value T and average weight G of the battery cells before baking. The battery cells are placed in the baking oven and the oven cavity is evacuated. Then, during the baking process, high-purity nitrogen gas with a purity ≥5N and a water content ≤1ppm is introduced into the oven cavity through the gas inlet as a replacement gas. The replacement gas is then stored in the gas storage and pressure stabilizing tank through the gas collection pipeline.

[0035] (2) After the gas pressure stabilizes for 5-15 minutes, use a dew point meter to measure the dew point of the replacement gas in the gas storage and pressure stabilizing tank for more than 5 minutes, and output the dew point value to the central control panel for data storage.

[0036] (3) After the measurement is completed, the replacement gas in the gas storage and pressure stabilizing tank is emptied through the exhaust valve, and then the gas storage and pressure stabilizing tank is cleaned by blowing air to ensure that the water vapor in the tank is completely removed.

[0037] (4) Repeat steps (1)-(3) at least 3 times, and use the central control panel to process the dew point value obtained each time. Specifically, this includes: referring to the dew point-moisture comparison table, converting the dew point value obtained each time into a moisture value H, and combining the average moisture value T of the battery cell before baking and the average weight G of the battery cell before baking to calculate the remaining moisture value D of the battery cell after baking. The calculation formula is as follows:

[0038] D = T - (H1 + H2 + ... + H) n ) / G

[0039] In the above formula, H1 is the moisture value corresponding to the first dew point value, H2 is the moisture value corresponding to the second dew point value, and H... n Let n be the moisture value corresponding to the nth dew point value, where n ≥ 3 and n is a positive integer.

[0040] The output moisture evaporation curve is used as the basis for determining the baking effect when the moisture evaporation curve tends to be stable, and the remaining moisture value of the battery cell after baking is used as the basis for online detection and alarm.

[0041] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] (1) The device system provided by the present invention connects the baking oven and the gas storage and pressure stabilizing tank through the gas collection pipeline, which can collect gas periodically in real time. A dew point meter is set on the gas storage and pressure stabilizing tank to measure the dew point value of the gas in real time during the baking process. After converting it into a moisture value, the baking effect can be determined. The online monitoring of the moisture overflow rate and water content of the cavity baking is realized, avoiding the measurement error caused by personnel testing. The whole device system has a simple structure, low maintenance cost, and convenient operation, which is conducive to large-scale promotion and application.

[0044] (2) The present invention performs real-time periodic gas collection of the battery cells during the baking process. Since there is a direct conversion relationship between dew point value and moisture value, the baking effect can be determined by real-time monitoring of the dew point value change of the replacement gas and online detection and alarm can be performed. This online detection method is significantly different from the traditional offline sampling detection method. The detection result can represent the moisture level of the entire batch of battery cells, with higher measurement accuracy, which improves production efficiency and product quality. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the device system for online detection of moisture content during battery cell baking provided by the present invention;

[0046] Figure 2 This is the curve showing the change in water content from a single evaporation as a function of baking time, obtained in Example 1.

[0047] Figure 3 This is the curve showing the change of dew point with baking time obtained in Example 1.

[0048] The components are: 1-baking oven; 2-gas storage and pressure stabilizing tank; 3-central control panel; 4-air inlet; 5-gas collection pipeline; 6-dew point meter; 7-exhaust valve. Detailed Implementation

[0049] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0050] To achieve online monitoring of the rate of moisture overflow and water content during cell baking, this invention provides a device system for online detection of moisture during cell baking, such as... Figure 1 As shown, the device system includes a baking oven 1, a gas storage and pressure stabilizing tank 2, and a central control panel 3 connected in sequence.

[0051] The baking oven 1 is equipped with an air inlet 4, and the baking oven 1 and the gas storage and pressure stabilizing tank 2 are connected by a gas collection pipeline 5.

[0052] The gas storage and pressure stabilizing tank 2 is equipped with a dew point meter 6 and an exhaust valve 7, and the dew point meter 6 is electrically connected to the central control panel 3.

[0053] The device system provided by this invention connects the baking oven 1 and the gas storage and pressure stabilizing tank 2 through the gas collection pipeline 5, which can collect gas periodically in real time. A dew point meter 6 is installed on the gas storage and pressure stabilizing tank 2 to measure the dew point value of the gas in real time during the baking process. After converting it into a moisture value, the baking effect can be determined. This realizes online monitoring of the moisture overflow rate and water content of the cavity baking, avoiding measurement errors caused by personnel testing. The whole device system has a simple structure, low maintenance cost, and convenient operation, which is conducive to large-scale promotion and application.

[0054] In some embodiments, the airtightness of the oven cavity of the baking oven 1 satisfies the following condition: leakage rate ≤ 5 Pa·L / s, for example, it can be 0.5 Pa·L / s, 1 Pa·L / s, 1.5 Pa·L / s, 2 Pa·L / s, 2.5 Pa·L / s, 3 Pa·L / s, 3.5 Pa·L / s, 4 Pa·L / s, 4.5 Pa·L / s or 5 Pa·L / s, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0055] In some embodiments, the pressure-bearing capacity of the gas collecting pipeline 5 is ≥1.1MPa, that is, to ensure that the gas collecting pipeline 5 can withstand sufficient pressure under high vacuum. For example, it can be 1.1MPa, 1.2MPa, 1.3MPa, 1.4MPa, 1.5MPa, 1.6MPa, 1.7MPa, 1.8MPa, 1.9MPa or 2.0MPa. The airtightness requirement is ≤5Pa / min to ensure pressure stability during pressure stabilization and testing, and to reduce interference. For example, it can be 0.5Pa / min, 1Pa / min, 1.5Pa / min, 2Pa / min, 2.5Pa / min, 3Pa / min, 3.5Pa / min, 4Pa / min, 4.5Pa / min or 5Pa / min, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0056] In some embodiments, the dew point meter 6 has a measuring range of -80°C to -20°C, for example, it can be -80°C, -75°C, -70°C, -65°C, -60°C, -55°C, -50°C, -45°C, -40°C, -35°C, -30°C, -25°C, or -20°C, and the detection accuracy is 0.5-2ppm, for example, it can be 0.5ppm, 0.6ppm, 0.7ppm, 0.8ppm, 0.9ppm, 1ppm, 1.1ppm, 1.2ppm, 1.3ppm, 1.4ppm, 1.5ppm, 1.6ppm, 1.7ppm, 1.8ppm, 1.9ppm, or 2ppm, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0057] In some embodiments, the exhaust valve 7 has the functions of automatic exhaust and air blowing cleaning.

[0058] The present invention also provides a method for online detection of moisture content during battery cell baking using the above-mentioned device system, the method comprising the following steps:

[0059] (1) Place the battery cell in the baking oven 1, and during the baking process, fill the oven cavity with replacement gas through the air inlet 4, and then store the replacement gas in the gas storage and pressure stabilizing tank 2 through the gas collection pipeline 5.

[0060] (2) After the gas pressure stabilizes, the dew point of the replacement gas in the gas storage and pressure stabilizing tank 2 is measured by the dew point meter 6, and the dew point value is output to the central control panel 3 for data storage.

[0061] (3) After the measurement is completed, the replacement gas in the gas storage and pressure stabilizing tank 2 is emptied through the exhaust valve 7.

[0062] (4) Repeat steps (1)-(3) at least 3 times, use the central control panel 3 to process the dew point value obtained each time, output the moisture evaporation curve to determine the baking effect and perform online detection and alarm.

[0063] This invention performs real-time periodic gas collection on the battery cells during the baking process. Since there is a direct conversion relationship between dew point value and moisture value, the baking effect can be determined by real-time monitoring of the dew point value change of the replacement gas, and online detection and alarm can be performed. This online detection method is significantly different from the traditional offline sampling detection method. The detection results can represent the moisture level of the entire batch of battery cells, with higher measurement accuracy, improving production efficiency and product quality.

[0064] In some embodiments, the battery cells in step (1) are sampled and calibrated for moisture content before being placed in the baking oven 1 to obtain the average moisture content T and average weight G of the battery cells before baking.

[0065] In some embodiments, step (1) involves evacuating the oven cavity of the baking oven 1 before baking begins to avoid interference from outside air with the test results.

[0066] In some embodiments, the replacement gas in step (1) includes high-purity nitrogen, and the purity of the high-purity nitrogen is ≥5N, for example, it can be 5N, 5.5N, 6N, 6.5N, 7N, 7.5N or 8N, and the water content is ≤1ppm, for example, it can be 0.1ppm, 0.2ppm, 0.3ppm, 0.4ppm, 0.5ppm, 0.6ppm, 0.7ppm, 0.8ppm, 0.9ppm or 1ppm, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0067] In some embodiments, the time for the air pressure to stabilize in step (2) is 5-15 minutes, for example, it can be 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes or 15 minutes, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0068] The present invention allows for dew point measurement after the air pressure has stabilized for a period of time, which can fully ensure the accuracy of the detection.

[0069] In some embodiments, the time for dew point measurement in step (2) is ≥5 min, for example, it can be 5 min, 5.5 min, 6 min, 6.5 min, 7 min, 7.5 min, 8 min, 8.5 min, 9 min, 9.5 min or 10 min, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0070] In some embodiments, step (3) involves blowing air into the gas storage pressure tank 2 after the replacement gas is emptied to ensure that the water vapor inside the tank is completely removed.

[0071] In some embodiments, the repetition interval in step (4) is 5-480 min, for example, it can be 5 min, 50 min, 100 min, 150 min, 200 min, 250 min, 300 min, 350 min, 400 min, 450 min or 480 min, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0072] In some embodiments, the data processing in step (4) includes: converting the dew point value obtained each time into a moisture value H, and calculating the remaining moisture value D of the battery cell after baking by combining the average moisture value T of the battery cell before baking and the average weight G of the battery cell before baking. The calculation formula is as follows:

[0073] D = T - (H1 + H2 + ... + H) n ) / G

[0074] In the above formula, H1 is the moisture value corresponding to the first dew point value, H2 is the moisture value corresponding to the second dew point value, and H... n This is the moisture value corresponding to the nth dew point value, where n ≥ 3 and n is a positive integer. For example, n can be 3, 4, 5, 6, 7, 8, 9 or 10, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0075] In some embodiments, the method for converting each obtained dew point value into a moisture value H is performed with reference to a dew point-moisture conversion table (see Table 1 below).

[0076] Table 1

[0077]

[0078]

[0079] For example, after baking every 2 hours, the replacement gas is collected, and the volume of the gas storage and pressure stabilizing tank 2 is V = 20m³. 3 After stabilizing the pressure, the measured dew point value was -50℃. Referring to the dew point-moisture conversion table, the corresponding moisture value H = 0.06171 g / m³. 3 Therefore, the water content of the gas in the gas storage and pressure stabilizing tank 2 is H×V=0.06171g / m³. 3 ×20m 3 =1.23g; If the total baking time is 8 hours, with 4 gas collection cycles, and the moisture value is calculated each time using the same method, the total moisture value is H1+H2+H3+H4. Therefore, the remaining moisture value of the battery cell after baking is: D=T-(H1+H2+H3+H4) / G / 10 6 .

[0080] In some embodiments, the determination of the baking effect in step (4) is based on the stabilization of the moisture evaporation curve.

[0081] In some embodiments, the online detection and alarm in step (4) are based on the remaining moisture content of the battery cell after baking.

[0082] Example 1

[0083] This embodiment provides a device system and method for online detection of moisture content during battery cell baking, such as... Figure 1 As shown, the device system includes a baking oven 1, a gas storage and pressure stabilizing tank 2, and a central control panel 3 connected in sequence. The baking oven 1 is equipped with an air inlet 4, and the baking oven 1 and the gas storage and pressure stabilizing tank 2 are connected via a gas collection pipeline 5. The gas storage and pressure stabilizing tank 2 is equipped with a dew point meter 6 and an exhaust valve 7, and the dew point meter 6 is electrically connected to the central control panel 3.

[0084] In this embodiment, the oven cavity airtightness of the baking oven 1 meets the following requirements: leakage rate ≤ 5 Pa·L / s; the pressure bearing capacity of the gas collecting pipeline 5 is ≥ 1.1 MPa, and the airtightness requirement is ≤ 5 Pa / min; the dew point meter 6 has a range of -80℃ to -20℃ and a detection accuracy of 1 ppm; the exhaust valve 7 has automatic exhaust and air blowing cleaning functions. The hardware requirements for data processing of the central control panel 3 are: industrial control computer CPU I7 10th generation; graphics card RTX 3060; 16G memory for data interconnection between the host computer and the slave computer and the MES system.

[0085] The method for online detection of moisture content during battery cell baking using the above-described device system in this embodiment specifically includes the following steps:

[0086] (1) The battery cells are sampled and calibrated to obtain the average moisture value T and average weight G of the battery cells before baking. The battery cells are placed in the baking oven 1 and the oven cavity is evacuated. Then, during the baking process, high-purity nitrogen gas with a purity of 5N and a water content of 0.8ppm is introduced into the oven cavity through the air inlet 4 as a replacement gas. Then, the replacement gas is stored in the gas storage and pressure stabilizing tank 2 through the gas collection pipeline 5.

[0087] (2) After the gas pressure stabilizes for 10 minutes, the dew point of the replacement gas in the gas storage and pressure stabilizing tank 2 is measured for 8 minutes using the dew point meter 6, and the dew point value is output to the central control panel 3 for data storage.

[0088] (3) After the measurement is completed, the replacement gas in the gas storage and pressure stabilizing tank 2 is emptied through the exhaust valve 7, and then the gas storage and pressure stabilizing tank 2 is cleaned by blowing air to ensure that the water vapor in the tank is completely removed.

[0089] (4) Repeat steps (1)-(3) a total of 18 times. Use the central control panel 3 to process the dew point value obtained each time. Specifically, refer to the dew point-moisture comparison table (see Table 1 above) to convert the dew point value obtained each time into a moisture value H. Combine the average moisture value T of the battery cell before baking and the average weight G of the battery cell before baking to calculate the remaining moisture value D of the battery cell after baking. The calculation formula is as follows:

[0090] D = T - (H1 + H2 + ... + H) 18 ) / G

[0091] In the above formula, H1 is the moisture value corresponding to the first dew point value, H2 is the moisture value corresponding to the second dew point value, and H... 18 This is the moisture value corresponding to the dew point value obtained in the 18th test.

[0092] The output moisture evaporation curve is used as the basis for determining the baking effect when the moisture evaporation curve tends to be stable, and the remaining moisture value of the battery cell after baking is used as the basis for online detection and alarm.

[0093] Figure 2 This is the curve showing the change in water content during a single evaporation as a function of baking time, obtained in this embodiment.

[0094] Depend on Figure 2 It can be seen that the moisture evaporation curve gradually stabilizes after 300 minutes, therefore the baking time can be set at 7 hours, with an evaporation rate ≤ 0.033 g / m³. 3 It can be considered that the moisture has been basically baked through.

[0095] Figure 3 This is the curve showing the change of dew point with baking time obtained in this embodiment.

[0096] Depend on Figure 3It can be seen that the moisture is completely baked after 400 minutes, so the baking standard can be set after the dew point is ≤-55℃.

[0097] Therefore, the device system provided by this invention connects the baking oven and the gas storage and pressure stabilizing tank through a gas collection pipeline, enabling real-time and periodic gas collection. A dew point meter is installed on the gas storage and pressure stabilizing tank to measure the dew point value of the gas in real time during the baking process. After converting it into a moisture value, the baking effect can be determined. This achieves online monitoring of the rate of moisture overflow and water content during cavity baking, avoiding measurement errors caused by manual testing. The entire device system has a simple structure, low maintenance cost, and convenient operation, which is conducive to large-scale promotion and application.

[0098] Furthermore, this invention performs real-time periodic gas collection on the battery cells during the baking process. Since there is a direct conversion relationship between dew point value and moisture value, the baking effect can be determined by real-time monitoring of the dew point value change of the replacement gas, and online detection and alarm can be performed. This online detection method is significantly different from the traditional offline sampling detection method. The detection results can represent the moisture level of the entire batch of battery cells, with higher measurement accuracy, improving production efficiency and product quality.

[0099] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A device system for online detection of moisture content during battery cell baking, characterized in that, The device system includes a baking oven, a gas storage and pressure stabilizing tank, and a central control panel connected in sequence. The baking oven is equipped with an air inlet, and the baking oven and the gas storage and pressure stabilizing tank are connected by a gas collection pipeline. The gas storage and pressure stabilizing tank is equipped with a dew point meter and an exhaust valve, and the dew point meter is electrically connected to the central control panel.

2. The device system according to claim 1, characterized in that, The oven cavity airtightness of the baking oven meets the following requirement: leakage rate ≤ 5 Pa·L / s; The pressure-bearing capacity of the gas collection pipeline is ≥1.1MPa, and the air tightness requirement is ≤5Pa / min; The dew point meter has a measuring range of -80℃ to -20℃ and a detection accuracy of 0.5-2ppm. The exhaust valve has the functions of automatic exhaust and air blowing for cleaning.

3. A method for online detection of moisture content during battery cell baking using the device system described in claim 1 or 2, characterized in that, The method includes the following steps: (1) Place the battery cell in the baking oven and fill the oven cavity with replacement gas through the air inlet during the baking process. Then, store the replacement gas in the gas storage and pressure stabilizing tank through the gas collection pipeline. (2) After the gas pressure stabilizes, the dew point of the replacement gas in the gas storage and pressure stabilizing tank is measured by a dew point meter, and the dew point value is output to the central control panel for data storage. (3) After the measurement is completed, the replacement gas in the gas storage and pressure stabilizing tank is emptied through the exhaust valve; (4) Repeat steps (1)-(3) at least 3 times, use the central control panel to process the dew point value obtained each time, output the moisture evaporation curve to determine the baking effect and perform online detection and alarm.

4. The method according to claim 3, characterized in that, In step (1), the battery cells are sampled and calibrated for moisture content before being placed in the baking oven to obtain the average moisture content T and average weight G of the battery cells before baking. Step (1) Vacuum the oven cavity before baking begins.

5. The method according to claim 4, characterized in that, The replacement gas in step (1) includes high-purity nitrogen, and the purity of the high-purity nitrogen is ≥5N and the water content is ≤1ppm.

6. The method according to claim 5, characterized in that, The time for the air pressure to stabilize in step (2) is 5-15 minutes; The time for dew point measurement in step (2) is ≥5 min.

7. The method according to claim 6, characterized in that, Step (3) After the replacement gas is emptied, the gas storage pressure stabilizing tank is also cleaned by blowing air to ensure that the water vapor in the tank is completely removed.

8. The method according to claim 7, characterized in that, The repetition interval in step (4) is 5-480 min; The data processing in step (4) includes: converting the dew point value obtained each time into a moisture value H, and calculating the remaining moisture value D of the battery cell after baking by combining the average moisture value T of the battery cell before baking and the average weight G of the battery cell before baking. The calculation formula is as follows: D=T-(H1+H2+…+H n ) / G In the above formula, H1 is the moisture value corresponding to the first dew point value, H2 is the moisture value corresponding to the second dew point value, and H... n Let n be the moisture value corresponding to the nth dew point value, where n ≥ 3 and n is a positive integer; The method for converting the dew point value obtained each time into the moisture value H is to refer to the dew point-moisture conversion table.

9. The method according to claim 8, characterized in that, The baking effect described in step (4) is determined based on the stabilization of the moisture evaporation curve; The online detection and alarm in step (4) are based on the remaining moisture content of the battery cell after baking.

10. The method according to any one of claims 3-9, characterized in that, The method includes the following steps: (1) Sample and calibrate the cell to obtain the average moisture value T and average weight G of the cell before baking. Place the cell in the baking oven and evacuate the oven cavity. Then, during the baking process, fill the oven cavity with high-purity nitrogen gas with a purity ≥5N and a water content ≤1ppm as the replacement gas through the gas inlet. Then, store the replacement gas in the gas storage and pressure stabilizing tank through the gas collection pipeline. (2) After the gas pressure stabilizes for 5-15 minutes, use a dew point meter to measure the dew point of the replacement gas in the gas storage and pressure stabilizing tank for more than 5 minutes, and output the dew point value to the central control panel for data storage. (3) After the measurement is completed, the replacement gas in the gas storage and pressure stabilizing tank is emptied through the exhaust valve, and then the gas storage and pressure stabilizing tank is cleaned by blowing air to ensure that the water vapor in the tank is completely removed. (4) Repeat steps (1)-(3) at least 3 times, and use the central control panel to process the dew point value obtained each time. Specifically, this includes: referring to the dew point-moisture comparison table, converting the dew point value obtained each time into a moisture value H, and combining the average moisture value T of the battery cell before baking and the average weight G of the battery cell before baking to calculate the remaining moisture value D of the battery cell after baking. The calculation formula is as follows: D=T-(H1+H2+…+H n ) / G In the above formula, H1 is the moisture value corresponding to the first dew point value, H2 is the moisture value corresponding to the second dew point value, and H... n Let n be the moisture value corresponding to the nth dew point value, where n ≥ 3 and n is a positive integer; The output moisture evaporation curve is used as the basis for determining the baking effect when the moisture evaporation curve tends to be stable, and the remaining moisture value of the battery cell after baking is used as the basis for online detection and alarm.

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