Real-time monitoring method for water content of pole piece / battery cell and baking system

Abstract

The invention discloses a real-time monitoring method for the water content of a pole piece / battery cell and a baking system, and belongs to the technical field of pole piece / battery cell production. Comprising the following steps: firstly, according to the initial vacuum degree P0, the vacuum degree P1, the gas free volume V, the baking temperature T, the total mass N before baking and the molar gas constant R, obtaining the moisture content W1 of the baked pole piece / battery cell at the current moment in the baking process; and obtaining the real-time water content W of the pole piece / battery cell according to the initial water content W0 and the baked water content W1. According to the real-time monitoring method for the water content of the pole piece / battery cell, the real-time water content of the pole piece / battery cell in the vacuum baking process can be calculated, and the baking system realizes real-time monitoring on the water content of the pole piece / battery cell in the vacuum baking process, so that the baking process of the pole piece / battery cell is controlled, the limitation of post detection is avoided, and the reliability of the baking process is improved. The reject ratio of the pole piece / battery cell in the baking process is reduced, the production efficiency is improved, the baking precision and efficiency of the pole piece / battery cell are remarkably improved, and reliable technical support is provided for the battery manufacturing industry.

Description

Technical Field

[0001] The invention belongs to the technical field of pole piece / battery core production, and specifically relates to a real-time monitoring method for the water content of a pole piece / battery core and a baking system. Background Art

[0002] Lithium batteries often get hot during use. If there is moisture inside the lithium battery, long-term heating will increase the heat of the battery itself, causing the internal moisture to evaporate and the air to expand violently, causing the battery to expand outwards, and in severe cases, the battery will explode.

[0003] In the production process of lithium-ion batteries, the baking process of pole pieces / cells is a crucial link. At present, the baking of pole pieces / cells is carried out in a vacuum manner. The prepared pole pieces / cells are placed in a vacuum environment for heating, and the boiling point of water is lowered in a vacuum state to accelerate the evaporation of water. The water vapor is discharged by vacuuming to remove the moisture inside the pole pieces / cells. The vacuum oven is specially developed and manufactured for the baking process of lithium batteries. It allows lithium batteries to be dried in a vacuum state with fast drying speed and low pollution. The goal of the baking process is to effectively reduce the moisture content inside the pole pieces / cells to ensure that the battery can subsequently show excellent performance, high safety and long cycle life. Effective control of moisture content is crucial to prevent internal short circuits in batteries, improve electrochemical stability and extend service life.

[0004] Traditionally, the execution of this process relies on "post-testing" the moisture content of the electrode / cell after baking, that is, after the baking process is completed, the residual moisture inside the electrode / cell needs to be quantitatively evaluated by precise testing equipment to ensure that it meets the established quality standards. However, this traditional "post-testing" method has gradually revealed its inherent limitations in practice: since the test is carried out after baking, it is impossible to obtain the moisture change information during the baking process in real time, resulting in the inability to adjust the baking parameters such as temperature, time or wind speed according to real-time data to achieve more precise moisture control; when it is found that the moisture content of the electrode / cell after baking exceeds the standard, rework must be carried out, which not only increases production costs, but also prolongs the production cycle and reduces overall production efficiency; the lack of real-time data support during the baking process makes it difficult for manufacturers to optimize the baking process and improve product quality. The dynamic relationship between baking conditions and moisture content cannot be accurately analyzed, which limits the space for process improvement; in the "post-testing" mode, once unqualified electrode / cells are detected, it means that the baking resources and time invested previously may be lost, resulting in unnecessary waste of resources.

[0005] In summary, the current "post-test" method in the baking process has many limitations in practical application and is difficult to meet the modern manufacturing industry's requirements for efficient, accurate, and traceable production. Therefore, a method is proposed that can monitor the moisture content of the electrode / cell in real time during the baking process. Summary of the invention

[0006] The purpose of the present invention is to provide a real-time monitoring method for the moisture content of the electrode / battery cell and a baking system to address the above-mentioned deficiencies, thereby realizing real-time monitoring of the moisture content of the electrode / battery cell during vacuum baking, thereby controlling the baking process of the electrode / battery cell, reducing the unqualified rate of the electrode / battery cell during baking, and improving production efficiency.

[0007] A real-time monitoring method for the water content of a pole piece / battery core, comprising:

[0008] Get the initial vacuum degree P in the vacuum oven 0 and the vacuum degree P in the vacuum baking oven at the current moment during the baking process 1 Steps;

[0009] Obtaining the gas free volume in the vacuum oven △ Steps of V;

[0010] The step of obtaining a baking temperature T in the vacuum baking oven;

[0011] Obtain the initial water content W of the electrode / cell 0 And the step of determining the total mass N of the pole piece / cell before baking;

[0012] According to the initial vacuum degree P 0 , vacuum degree P 1 , gas free volume △ V, baking temperature T, total mass N before baking and molar gas constant R to obtain the moisture content W baked out in the electrode / cell at the current moment during the baking process 1 Steps;

[0013] According to the initial water content W 0 And the moisture content W after baking 1 The step of obtaining the real-time water content W of the electrode / cell.

[0014] Furthermore, the cumulative change of the vacuum degree in the vacuum baking oven at the current moment during the baking process ∑ △ P step, wherein the cumulative change in vacuum degree ∑ △ P represents the cumulative change in the vacuum degree obtained by evacuating the vacuum oven multiple times and then baking before the current moment;

[0015] Obtaining the gas free volume in the vacuum oven △ Steps of V;

[0016] The step of obtaining a baking temperature T in the vacuum baking oven;

[0017] Obtain the initial water content W of the electrode / cell 0 And the step of determining the total mass N of the pole piece / cell before baking;

[0018] According to the cumulative change of vacuum degree ∑ △ P, gas free volume △ V, baking temperature T, total mass N before baking and molar gas constant R to obtain the cumulative moisture content W' baked in the electrode / cell at the current moment during the baking process;

[0019] According to the initial water content W 0 And the step of obtaining the real-time moisture content W of the electrode sheet / battery core by using the baked cumulative moisture content W'.

[0020] Further, the free volume of gas in the vacuum oven is obtained. △ The steps of V also include:

[0021] Get the internal volume V of the vacuum oven 0 , the total volume of the electrode / cell is V 1 , the volume V of the loading device for the electrode / cell 2 and through the internal volume V 0 The total volume V of the electrode / cell 1 and the volume V of the loading device for the electrode / cell 2 The difference is obtained.

[0022] Further, the initial water content W of the electrode / cell is obtained. 0 The steps also include:

[0023] The moisture content of the disassembled electrode / battery cell is measured using a moisture meter, and the average of the measured moisture contents of multiple electrode / battery cells is taken to represent the initial moisture content W of the electrode / battery cell. 0 .

[0024] Furthermore, the moisture content W of the electrode / cell baked out at the current moment during the baking process is obtained. 1 The steps further include:

[0025] Through the vacuum degree P 1 and initial vacuum degree P 0 The difference between the two values ​​is used to obtain the moisture content W of the baked product according to the ideal gas state equation. 1 .

[0026] Furthermore, the step of obtaining the cumulative moisture content W' baked in the electrode piece / cell at the current moment during the baking process further includes:

[0027] Cumulative change of vacuum degree ∑ △ P, according to the ideal gas state equation, the accumulated moisture content W' is obtained.

[0028] Furthermore, during the baking process, the baking temperature T in the vacuum baking oven is kept constant.

[0029] A baking system for real-time monitoring of the moisture content of an electrode sheet / battery core comprises a vacuum oven, a vacuum degree control device and a data processing unit, wherein the data processing unit is used to execute the above-mentioned real-time monitoring method.

[0030] Furthermore, the baking system further comprises: a display unit, which displays the water content of the electrode / cell in real time during the baking process.

[0031] Furthermore, the baking system further comprises: a heating unit and a temperature control device, wherein the temperature control device controls the heating unit during the baking process so that the baking temperature T in the vacuum baking oven remains constant.

[0032] Furthermore, the baking system also includes: a data input unit.

[0033] Furthermore, the data processing unit records the vacuum degree change data of the vacuum baking oven and the water content change data of the electrode / battery cell.

[0034] The beneficial effects of the present invention are:

[0035] The present invention discloses a real-time monitoring method for the water content of a pole piece / battery core and a baking system, which belongs to the technical field of pole piece / battery core production. 0 , vacuum degree P 1 , gas free volume △ V, baking temperature T, total mass N before baking and molar gas constant R to obtain the moisture content W baked out in the electrode / cell at the current moment during the baking process 1 , and then according to the initial water content W 0 And the moisture content W after baking 1The step of obtaining the real-time moisture content W of the pole piece / battery cell. The real-time monitoring method of the moisture content of the pole piece / battery cell of the present invention can calculate the real-time moisture content of the pole piece / battery cell during vacuum baking. The baking system realizes the real-time monitoring of the moisture content of the pole piece / battery cell during vacuum baking, thereby controlling the baking process of the pole piece / battery cell, avoiding the limitation of post-detection, reducing the unqualified rate of the pole piece / battery cell during baking, improving production efficiency, significantly improving the accuracy and efficiency of baking of the pole piece / battery cell, and providing reliable technical support for the battery manufacturing industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a flow chart of the real-time monitoring method of the present invention;

[0037] Figure 2 It is a curve diagram of vacuum degree variation during vacuum baking of the present invention;

[0038] Figure 3 It is the system block diagram of the baking system. DETAILED DESCRIPTION

[0039] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0040] It should be understood that the terms used herein are only for the purpose of describing specific example embodiments and are not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "one", "an" and "said" as used herein may also be meant to include plural forms. The terms "include", "comprise", "contain", and "have" are inclusive and therefore specify the existence of stated features, steps, operations, elements and / or parts, but do not exclude the existence or addition of one or more other features, steps, operations, elements, parts and / or combinations thereof. The method steps, processes, and operations described herein are not interpreted as necessarily requiring them to be performed in the specific order described or illustrated, unless the execution order is clearly indicated. It should also be understood that additional or alternative steps may be used.

[0041] The word “exemplary” is used exclusively herein to mean “serving as an example, example, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0042] For ease of description, spatial relative terms may be used in the text to describe the relationship of one element or feature relative to another element or feature as shown in the figure, such as "inside", "outside", "inner side", "outer side", "below", "below", "above", "above", etc. Such spatial relative terms include different orientations of the device in use or operation in addition to the orientation depicted in the figure. For example, if the device in the figure is turned over, the element described as "below other elements or features" or "below other elements or features" will then be oriented as "above other elements or features" or "above other elements or features". Therefore, the example term "below..." can include both upper and lower orientations. The device can be oriented otherwise (rotated 90 degrees or in other directions) and the spatial relative descriptors used in the text are interpreted accordingly.

[0043] In addition, in order to better illustrate the present disclosure, numerous specific details are given in the following specific embodiments. It should be understood by those skilled in the art that the present disclosure can also be implemented without certain specific details. In some examples, methods, means, components and circuits well known to those skilled in the art are not described in detail in order to highlight the subject matter of the present disclosure.

[0044] The ideal gas state equation, also known as the ideal gas law or the universal gas law, is a state equation that describes the relationship between pressure, volume, and temperature of an ideal gas in equilibrium. It is based on the Boyle-Maliott law, Charles' law, Gay-Lussac's law, and other laws, and was proposed by French scientist Clapeyron.

[0045] The ideal gas state equation can be expressed as PV = nRT, where P is pressure (Pa), V is gas volume (m 3 ), T is the temperature (K), n is the amount of substance in the gas (mol), and R is the molar gas constant (also called the universal gas constant) (J / (mol.K)).

[0046] Embodiment 1:

[0047] In this embodiment, the example of vacuum baking of the electrode sheet / battery cell is used for explanation, and the air in the oven is not evacuated during the baking process of the electrode sheet / battery cell.

[0048] A real-time monitoring method for the water content of a pole piece / battery core, comprising:

[0049] Get the initial vacuum degree P in the vacuum oven 0 and the vacuum degree P in the vacuum baking oven at the current moment during the baking process 1step; the step of obtaining the gas free volume △V in the vacuum baking oven; the step of obtaining the baking temperature T in the vacuum baking oven; the step of obtaining the initial water content W of the electrode / cell 0 and the step of determining the total mass N of the electrode / cell before baking; and determining the total mass N of the electrode / cell before baking according to the initial vacuum degree P 0 , vacuum degree P 1 , gas free volume △V, baking temperature T, total mass N before baking and molar gas constant R to obtain the moisture content W baked out in the electrode / cell at the current moment during the baking process 1 According to the initial water content W 0 And the moisture content W after baking 1 The step of obtaining the real-time water content W of the electrode / cell is specifically:

[0050] First, before placing the electrode piece / battery cell in the oven for baking, the water content of the electrode piece / battery cell is measured to obtain the initial water content of the electrode piece / battery cell, W 0 The moisture content of the electrode / cell is measured using a moisture meter, which can detect the moisture content of various organic and inorganic solids, liquids, gases and other samples. According to the measurement principle, it can be divided into two categories: physical measurement method and chemical measurement method. Commonly used physical measurement methods include weight loss method, distillation stratification method, gas chromatography analysis method, etc., and chemical measurement methods mainly include Karl Fischer method, toluene method, etc. The International Organization for Standardization has set the Karl Fischer method as the international standard for measuring trace moisture, and our country has also set this method as the national standard for measuring trace moisture.

[0051] Then, put the electrode / cell into the oven. Before baking the electrode / cell, first establish the ideal gas state equation in the oven, as follows:

[0052] According to the initial vacuum degree, gas volume, amount of substance in the initial gas, molar gas constant and temperature in the oven, the ideal gas state equation in the oven before baking is established:

[0053] P 0 ×Δ V = n 0 ×R ×T (1)

[0054] Where: P 0 is the initial vacuum degree in the oven, unit is P a (N / m 2 );△V is the free volume of gas in the baking oven, unit is m 3 ;n 0 is the amount of substance in the initial gas, in mol; R is the molar gas constant, which is 8.31 J / (mol·K); T is the temperature in the baking oven, in K.

[0055] Then, the electrode / cell in the oven is baked, and the ideal gas state equation in the oven during the baking process is established.

[0056] The details are as follows:

[0057] According to the vacuum degree, gas volume, amount of gas substance in the baking process, molar gas constant and temperature in the baking process, the ideal gas state equation in the baking oven before baking is established:

[0058] P 1 ×ΔV=n 1 ×R×T(2)

[0059] Where: P 1 It is the vacuum degree in the oven at the current moment during the baking process, the unit is P a (N / m 2 );△V is the free volume of gas in the baking oven, unit is m 3 ;n 1 is the amount of substance in the oven gas at the current moment during the baking process, in mol; R is the molar gas constant, which is 8.31 J / (mol·K); T is the temperature in the baking oven, in K.

[0060] During the baking process, the vacuum degree in the oven changes continuously, so the vacuum degree in the oven before and after baking is different. The initial vacuum degree in the oven is represented by P in formula (1). 0 In formula (2), the vacuum degree in the oven at the current moment during the baking process is expressed as P 1 Indicated by; During the baking process, the moisture in the electrode / cell is continuously baked out and becomes water vapor to enter the baking oven, so the amount of substance in the gas in the oven changes continuously during the baking process. Therefore, the amount of substance in the initial gas in formula (1) is expressed by n 0 In formula (2), the amount of substance in the oven gas at the current moment during the baking process is expressed by n 1 Indicated by; since the baking temperature is kept constant during the vacuum baking of the electrode / cell, that is, the temperature in the oven remains unchanged during the baking process, the temperature in the baking oven in formula (1) and formula (2) is the same, represented by T; the molar gas constant is a constant itself, and its value remains unchanged during the baking process. The molar gas constant in formula (1) and formula (2) is the same, represented by R.

[0061] The calculation of the free volume of gas in the baking oven is as follows:

[0062] Calculate the gas volume in the oven based on the oven's internal volume, the pole piece / cell volume, and the pole piece / cell loader volume:

[0063] Δ V = VV 0 -VV1 -V 2 (3)

[0064] Where: V 0 is the internal volume of the oven, in m 3 ; V 1 is the total volume of the electrode / cell, in m 3 ; V 2 The volume of the electrode / cell loading device, in m 3 During the baking process, the internal volume V of the baking oven 0 , the total volume of the electrode / cell V 1 and the volume V of the electrode / cell loading device 2 is constant, so the free volume △V of the gas in the baking oven is constant during the baking process of the electrode / cell, so the free volume △V of the gas in equation (1) and equation (2) is the same and is expressed by △V.

[0065] Specifically, in S3, the baked moisture content equation is established as follows:

[0066] According to the amount of substance in the initial gas, the amount of substance in the gas during baking, the initial mass of the electrode / cell and the molar mass of water, the moisture content equation of the baked product is established:

[0067] WW 1 1= (n 1 -n 0 )× 18 / N (4)

[0068] Where: n 0 is the amount of substance in the initial gas, in mol; n 1 is the amount of substance in the gas in the oven at the current moment during the baking process, in mol; N is the total mass of the electrode / cell before baking, in kg.

[0069] In formula (4), the moisture content of the baked product is calculated based on the amount of change in the amount of substance in the gas in the oven. This is because the amount of change in the amount of substance in the gas in the oven is caused by the change in the moisture in the electrode piece / battery cell from liquid to gaseous water vapor after the electrode piece / battery cell is baked. When the moisture changes from liquid to gaseous water vapor, the amount of substance will not change. Therefore, the amount of change in the amount of substance in the gas is the amount of change in the amount of substance in the baked product, that is, n 1 -n 0 . Among them, the molar mass of water is 18g / mol.

[0070] Then, the relationship between the baked moisture content and the change in vacuum degree is established as follows:

[0071] The baked moisture content W is established based on the ideal gas state equation in the oven before baking, the ideal gas state equation in the oven during baking, and the moisture content equation of the baked product. 1 and vacuum degree change P 1 -P 0 The relationship between the baked water content W is obtained. 1 :

[0072] Substituting equation (2) - equation (1) to obtain the change in the amount of water n 1 -n 0 and vacuum degree change P 1 -P 0 The relationship between

[0073]

[0074] Where: P 1 -P 0 is the change of vacuum degree during baking,

[0075] Substituting formula (5) into formula (4), we can obtain:

[0076]

[0077] Substituting formula (3) into formula (6), we can get the moisture content W of the baked product. 1 The change of vacuum degree P 1 -P 0 The relationship between

[0078]

[0079] Where P 1 -P 0 is the change in vacuum degree in the oven, the initial vacuum degree P 0 and the vacuum degree P in the oven at the current moment during the baking process 1 can be measured by instruments (such as vacuum gauge); the internal volume V of the baking oven 0 , the total volume of the electrode / cell V 1 , the volume V of the electrode / cell loading device 2 All can be measured and calculated; the temperature T in the baking oven can be measured by a temperature measuring instrument. When the measured temperature is Celsius C, Celsius must be converted to Kelvin K, that is, K = C + 273.15. If the baking temperature is 100°C, it is 373.15K when converted to Kelvin; the total mass N of the electrode / cell before baking can be measured by an instrument; the molar gas constant R = 8.31 J / (mol·K), and the molar gas constant is converted to the gas constant of water vapor 461.6 J / (kg·K). Therefore, the measured P 0 , P1 、V 0 、V 1 、V 2 Substituting , T, into formula (7), we can get the moisture content of the electrode / cell baked out at the current moment during the baking process. It can be seen that the moisture content of the electrode / cell baked out at the current moment during the baking process is only related to the change in the vacuum degree in the oven (P 1 -P 0 ) related.

[0080] Finally, the real-time moisture content of the electrode / cell during the baking process can be obtained based on the initial moisture content of the electrode / cell and the moisture content obtained after baking, as follows:

[0081] The initial water content of the electrode / cell W 0 Subtract the baked moisture content W 1 Get the real-time water content of the electrode / cell.

[0082]

[0083] It can be seen that the initial vacuum degree, the internal volume of the baking oven, the total volume of the electrode / cell, the volume of the electrode / cell loading device, the gas constant of water vapor, the total mass of the electrode / cell before baking, and the temperature in the baking oven are all fixed during the baking process. The only thing that changes is the vacuum degree P in the oven. 1 , that is, the change in vacuum degree in the oven P 1 -P 0 It changes all the time, so the real-time moisture content of the electrode / battery cell changes with the vacuum degree in the oven. By only getting the vacuum degree in the oven at the current moment, the real-time moisture content of the electrode / battery cell can be obtained, so as to realize real-time monitoring of the moisture content of the electrode / battery cell during the baking process, thereby controlling the baking process of the electrode / battery cell, avoiding the limitations of post-detection, reducing the unqualified rate of the electrode / battery cell during baking, and improving production efficiency.

[0084] Embodiment 2:

[0085] In the actual operation process of vacuum baking, it is usually not carried out for a single electrode / cell, but in batches, that is, the electrode / cell is vacuum baked in batches, and the vacuum degree in the oven changes during the baking process, so the oven needs to be evacuated several times, as shown in the attached Figure 2 As shown in the figure, a stable vacuum degree is maintained in the oven to maintain efficient drying effect and the original performance of the electrode / cell. When baking batches of electrode / cells, the calculation process of the real-time moisture content of the electrode / cell is as shown in the attached figure. Figure 1Therefore, in this embodiment, when multiple pole pieces / cells are vacuum-baked, and the oven is evacuated multiple times during the baking of the pole pieces / cells, an example is used for explanation.

[0086] A real-time monitoring method for the moisture content of a pole piece / battery core comprises obtaining the cumulative change of the vacuum degree in the vacuum baking box at the current moment during the baking process ∑ △ P step, wherein the cumulative change in vacuum degree ∑ △ P represents the cumulative change in the vacuum degree obtained by evacuating the vacuum oven multiple times and then baking before the current moment; the free volume of gas in the vacuum oven is obtained. △ V step; obtaining the baking temperature T in the vacuum baking oven; obtaining the initial water content W of the electrode / cell 0 and the step of determining the total mass N of the electrode / cell before baking; and determining the cumulative change in vacuum degree ∑ △ P, gas free volume △ V, baking temperature T, total mass N before baking and molar gas constant R to obtain the cumulative moisture content W' baked out in the electrode / cell at the current moment during the baking process; according to the initial moisture content W 0 And the step of obtaining the real-time moisture content W of the electrode / cell from the baked cumulative moisture content W'. The specific derivation process is:

[0087] First, test the moisture content W of the batch of pole pieces / cells before baking 0 , select several electrodes / cells from the batch of electrodes / cells for measurement, disassemble the selected electrodes / cells normally, and then use a moisture meter to measure the moisture content of the disassembled electrodes / cells. The average value of the measured moisture content of several electrodes / cells represents the initial moisture content W of this batch of electrodes / cells. 0 . Since the electrode / battery cell moisture content test is destructive, after obtaining the initial moisture content, the remaining electrode / battery cells are placed in an oven for preheating, and then the electrode / battery cells are vacuum-baked. Since the oven needs to be evacuated multiple times during the baking process, the vacuum degree in the oven changes multiple times. According to the real-time monitoring method of Example 1, the real-time moisture content of the batch electrode / battery cells during vacuum baking can be derived by the same logic. The specific process is as follows:

[0088] To solve the moisture content of the baked product at the current time t', it is assumed that the oven has been evacuated n times before this time point. For example, Figure 2 As shown, the initial vacuum degree in the oven is P 0 After baking for a period of time, the vacuum degree in the oven is P 1 When the oven is evacuated, the vacuum degree in the oven is P 2After baking for a period of time, the vacuum degree in the oven is P 3 When the oven is evacuated, the vacuum is pumped out until the vacuum degree in the oven reaches P 2n , when baking to the current time t', the vacuum degree in the oven is P'. According to formula (7) in Example 1, the change of the moisture content baked in the oven changes with the change of the vacuum degree in the oven. Therefore, when solving the moisture content baked at the current time t', it can be divided into solving the change of the vacuum degree in the oven from P to P. 0 Change to P 1 , P 2 Change to P 3 , ..., P 2n Change to P', that is, the change in the vacuum degree in the oven after each vacuum pumping to the change in the vacuum degree in the oven after a period of baking (before the next vacuum pumping), the moisture content that has been baked corresponding to each change in vacuum degree, and then summing them up to get the moisture content that has been baked at the current moment t'.

[0089] The vacuum degree in the oven is from P 0 Change to P 1 When the moisture content of the baked product in the oven is 1, the vacuum degree in the oven, the gas volume, the amount of the gas substance in the baking process, the molar gas constant and the temperature can be used to establish the moisture content of the baked product in the oven. 0 and P 1 Ideal gas state equation,

[0090] P 0 ×ΔV=n 0 ×R×T

[0091] P 1 ×ΔV=n 1 ×R×T

[0092] And, W 1 =(n 2 -n 1 )×18 / N

[0093] Combining the above three equations, we can get the vacuum degree in the oven from P 0 Change to P 1 At this time, the moisture content baked out in the oven is:

[0094]

[0095] Similarly, the vacuum degree in the oven changes from P 2 Change to P 3 At this time, the moisture content baked out in the oven is:

[0096]

[0097] ..., the vacuum degree in the oven is from P 2n Variation P', moisture content baked in the oven:

[0098]

[0099] Then the above W 1 , W 2 ,……,W n Sum them up and get the moisture content of the baked product at the current time t':

[0100]

[0101] In the above formula, ∑△P=(P 1 -P 0 )+(P 3 -P 2 )……+(P'-P 2n ) is the cumulative change in the vacuum degree obtained after multiple vacuum drying in the vacuum drying oven, that is, the sum of the changes in the vacuum degree in the oven after each vacuum drying to the vacuum degree in the oven after a period of baking (before the next vacuum drying); N is the total mass of all the pole pieces / cells baked in the batch before baking;

[0102] ΔV=V 0 -V 1 -V 2

[0103] Among them, V 0 Internal volume of the oven, V 1 V is the total volume of all the pole pieces / cells baked in the batch, 2 is the volume of all the electrode / cell loading equipment in the oven. Finally, the initial moisture content of the electrode / cell W 0 Subtract the moisture content W' that has been baked out at the current moment to obtain the real-time moisture content of the electrode / cell at the current moment t'.

[0104]

[0105] Embodiment three:

[0106] A baking system for real-time monitoring of the moisture content of the electrode / battery core can calculate and monitor the moisture content of the electrode / battery core in real time during the baking process. Figure 3The system block diagram of the baking system is shown. The baking system includes a vacuum oven, a vacuum control device, a display unit, a heating unit, a temperature control device, a data input unit and a data processing unit. The baking process of the electrode / battery cell can be automated and intelligently monitored and managed through collaborative work. Among them, the vacuum oven can be made of high thermal insulation material, and is equipped with evenly distributed heating elements inside to ensure that the electrode / battery cell is evenly heated during the baking process. The vacuum oven is designed with a sealed door to cooperate with the use of a vacuum pump; the vacuum control device is connected to the oven to extract the air in the oven at the initial stage or a specific stage of baking, to create a low-oxygen or vacuum environment, to accelerate the evaporation and discharge of moisture in the electrode / battery cell, and to maintain efficient drying effects and the original performance of the electrode / battery cell; the heating unit is used to heat the vacuum oven and increase the temperature in the vacuum oven. The temperature control device can use a PID control algorithm to accurately control the heating unit during the baking process so that the baking temperature T in the vacuum baking oven remains constant to avoid temperature changes that damage the electrode / battery cell or cause poor baking effects; the data processing unit The data processing unit is the core of the system, integrating a high-performance processor and dedicated software. The data processing unit is used to execute the real-time monitoring method of the moisture content of the electrode piece / battery cell in Example 1 and Example 2, so as to monitor the real-time moisture content of the electrode piece / battery cell during the baking process. When the real-time moisture content of the electrode piece / battery cell reaches the set value, an alarm is immediately triggered to stop the baking of the electrode piece / battery cell. The data processing unit can also record and store data of the entire baking process, such as vacuum degree change data and electrode piece / battery cell moisture content change data, to provide a basis for subsequent analysis and optimization; the display unit is used to display the moisture content of the electrode piece / battery cell in real time during the baking process.

[0107] The operation process of the above baking system is as follows: in the preparation stage, the electrode / battery cell to be baked is placed in the vacuum oven and the sealing door is closed; parameter setting: input the target baking temperature, time, vacuum degree and the set value of the moisture content of the electrode / battery cell through the interface of the data input unit; start baking: after confirming that all settings are correct, start the system, the vacuum degree control device, the heating unit and the temperature control device start working, the vacuum oven starts to heat up, and the data processing unit starts the monitoring and calculation program simultaneously. During the baking process, the data processing unit continuously collects and processes data, and the display unit displays the moisture content and baking status of the electrode / battery cell in real time. If necessary, the baking parameters can be adjusted manually or automatically according to the monitoring results; after the baking is completed, when the electrode / battery cell reaches the preset moisture content value after baking, the system automatically stops heating and vacuum extraction, and sends a completion signal. At this time, the electrode / battery cell can be safely taken out for subsequent processing; data analysis: after the baking is completed, the data processing unit will automatically generate a report, including a baking curve, a moisture content change chart, etc., for technical personnel to analyze and use.

[0108] The baking system provided in this embodiment realizes real-time monitoring of the moisture content of the electrode / battery cell during the vacuum baking process through integrated design and intelligent management, thereby controlling the baking process of the electrode / battery cell, avoiding the limitations of post-detection, reducing the failure rate of the electrode / battery cell during baking, and improving production efficiency. It significantly improves the accuracy and efficiency of electrode / battery cell baking, and provides reliable technical support for the battery manufacturing industry.

[0109] All technical features in this embodiment can be freely combined according to actual needs. The above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be covered by the scope of the claims of the present invention. The technology, shape, and structural parts not described in detail in the present invention are all well-known technologies.

[0110] The above embodiments are preferred implementation schemes of the present invention. In addition, other implementation schemes are also included. Any obvious replacement without departing from the concept of the present technical scheme is within the protection scope of the present invention.

Claims

1. A real-time monitoring method for the water content of a pole piece / battery core, characterized in that: include The step of obtaining an initial vacuum degree P0 in the vacuum baking oven and a vacuum degree P1 in the vacuum baking oven at a current moment during the baking process; Obtaining the gas free volume in the vacuum oven △ Steps of V; The step of obtaining a baking temperature T in the vacuum baking oven; The step of obtaining the initial water content W0 of the electrode piece / battery core and the total mass N of the electrode piece / battery core before baking; According to the initial vacuum degree P0, vacuum degree P1, gas free volume △ V, baking temperature T, total mass N before baking and molar gas constant R to obtain the moisture content W1 baked in the electrode / cell at the current moment during the baking process; The step of obtaining the real-time moisture content W of the electrode sheet / battery cell according to the initial moisture content W0 and the baked moisture content W1.

2. A real-time monitoring method for the water content of a pole piece / battery core, characterized in that: include Get the cumulative change of vacuum degree in the vacuum baking oven at the current moment during baking △ P step, wherein the cumulative change in vacuum degree ∑ △ P represents the cumulative change in the vacuum degree obtained by evacuating the vacuum oven multiple times and then baking before the current moment; Obtaining the gas free volume in the vacuum oven △ Steps of V; The step of obtaining a baking temperature T in the vacuum baking oven; The step of obtaining the initial water content W0 of the electrode piece / battery core and the total mass N of the electrode piece / battery core before baking; According to the cumulative change of vacuum degree ∑ △ P, gas free volume △ V, baking temperature T, total mass N before baking and molar gas constant R to obtain the cumulative moisture content W' baked out in the electrode piece / battery cell at the current moment during the baking process; The step of obtaining the real-time moisture content W of the electrode sheet / cell according to the initial moisture content W0 and the accumulated moisture content W' obtained by baking.

3. The real-time monitoring method of the water content of the electrode piece / battery core according to claim 1 or 2, characterized in that: Obtaining the gas free volume in the vacuum oven △ The steps of V also include: The internal volume V0 of the vacuum baking oven, the total volume V1 of the electrode piece / battery cell, and the volume V2 of the loading container of the electrode piece / battery cell are obtained, and the internal volume V0 is obtained by the difference between the total volume V1 of the electrode piece / battery cell and the volume V2 of the loading container of the electrode piece / battery cell.

4. The real-time monitoring method of the water content of the electrode piece / battery core according to claim 1 or 2, characterized in that: The step of obtaining the initial water content W0 of the electrode / cell also includes: The moisture content of the disassembled pole piece / battery cell is measured using a moisture meter, and the average value of the measured moisture contents of multiple pole pieces / battery cells is taken to represent the initial moisture content W0 of the pole piece / battery cell.

5. The real-time monitoring method of the water content of the electrode piece / battery core according to claim 1 is characterized in that: The step of obtaining the moisture content W1 baked out in the electrode piece / battery cell at the current moment during the baking process further includes: The moisture content W1 of the baked product is obtained by the difference between the vacuum degree P1 and the initial vacuum degree P0 according to the ideal gas state equation.

6. The real-time monitoring method of the water content of the electrode piece / battery core according to claim 2 is characterized in that: The step of obtaining the cumulative moisture content W' baked in the electrode piece / cell at the current moment during the baking process further includes: Cumulative change of vacuum degree ∑ △ P, according to the ideal gas state equation, the accumulated moisture content W' is obtained.

7. The real-time monitoring method of the water content of the electrode piece / battery core according to claim 1 or 2, characterized in that: During the baking process, the baking temperature T in the vacuum baking oven is kept constant.

8. A baking system for real-time monitoring of moisture content of an electrode sheet / battery cell, comprising a vacuum oven, a vacuum degree control device and a data processing unit, wherein the data processing unit is used to execute the real-time monitoring method according to any one of claims 1 to 7.

9. The baking system according to claim 8, characterized in that: The baking system further comprises: a display unit, which displays the water content of the electrode / cell in real time during the baking process.

10. The baking system according to claim 8, characterized in that: The baking system further comprises: a heating unit and a temperature control device, wherein the temperature control device controls the heating unit during the baking process so that the baking temperature T in the vacuum baking box remains constant.

11. The baking system according to claim 8, characterized in that: The baking system further comprises: a data input unit.

12. The baking system according to claim 8, characterized in that: The data processing unit records the vacuum degree change data of the vacuum baking oven and the water content change data of the pole piece / battery core.

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