Lithium battery vacuum baking device and method

Abstract

A lithium battery vacuum baking device and method, relating to the field of battery technology. The lithium battery vacuum baking method comprises obtaining a time-based baking pressure function of the lithium battery, and determining the highest step pressure of each step according to the baking pressure function, wherein the highest step pressure of the current step is greater than the highest step pressure of the next step, and the lowest step pressure of the current step is equal to the lowest step pressure of the next step; entering the first step to bake the lithium battery; judging whether the step baking stop condition is met according to whether the baking time required for the pressure to rise to the highest step pressure of the current step is greater than the preset time, if the baking time is greater than the preset time, the current step baking ends, and enters the next step until all the preset steps are executed. The above-mentioned lithium battery vacuum baking method can improve the baking consistency, baking efficiency and vacuum pump life, and reduce production energy consumption.

Description

Technical Field

[0001] The present invention relates to the field of battery technology, and in particular to a lithium battery vacuum baking device and method. Background Art

[0002] In the production process of lithium batteries, there are many factors that affect the performance of lithium batteries, such as material type, positive and negative electrode compaction density, moisture, coating surface density and electrolyte dosage. Among them, moisture has a very large impact on the performance of lithium batteries and is a factor that must be strictly controlled. Excessive moisture can not only lead to the decomposition of lithium salts in the electrolyte, but also have a certain degree of corrosion and damage to the positive and negative electrode materials and pole pieces, and it is also easy to reduce the cycle performance and safety performance of lithium batteries.

[0003] There are two main types of existing lithium battery baking processes. One is a baking process that maintains a continuous high vacuum state, and the other is a process that inserts a short period of dry gas for replacement under a continuous high vacuum state. The latter has a certain efficiency improvement over the former, but it does not match the battery baking characteristics, and the baking efficiency is not particularly ideal. This is mainly manifested in that when the water content of the battery is high in the early stage, the pressure rise rate in the baking chamber is high, and the vacuum pressure range is small, and the vacuum pump needs to be started frequently for vacuum extraction. In the later stage of baking, when the water content of the battery is low, the maximum vacuum pressure takes a long time, resulting in inefficient baking. Summary of the invention

[0004] The object of the present invention is to provide a lithium battery vacuum baking device and method, which can improve the baking consistency, baking efficiency and vacuum pump life, and reduce production energy consumption.

[0005] The embodiment of the present invention is achieved as follows:

[0006] An embodiment of the present invention provides a lithium battery vacuum baking method, comprising: obtaining a time-based baking pressure function of the lithium battery, and determining a maximum step pressure of each step according to the baking pressure function, wherein the maximum step pressure of the current step is greater than the maximum step pressure of the next step, and the minimum step pressure of the current step is equal to the minimum step pressure of the next step; entering the first step to bake the lithium battery; judging whether a step baking stop condition is met according to whether the baking time required for the pressure to rise to the maximum step pressure of the current step is greater than a preset time, if the baking time is greater than the preset time, the baking of the current step is ended, and entering the next step until all the preset steps are executed.

[0007] Optionally, entering the first step and baking the lithium battery includes: entering the first step, placing the lithium battery in the cavity of the baking device for baking; judging whether the step baking stop condition is met based on whether the baking time required for the pressure to rise to the highest step pressure of the current step is greater than a preset time; if the baking time is greater than the preset time, the current step baking ends, including: obtaining the baking time required for the pressure in the cavity to rise to the highest step pressure of the current step; if the baking time is less than or equal to the preset time, reducing the pressure in the cavity to the lowest step pressure of the current step, and baking the lithium battery again; if the baking time is greater than the preset time, the current step baking ends, and entering the next step or ending the baking.

[0008] Optionally, the pressure in the cavity is reduced to the minimum step pressure of the current step, and the lithium battery is baked again, including: introducing dry gas into the cavity until the pressure in the cavity reaches the preset dry pressure of the current step; extracting the mixed gas after a preset time until the pressure in the cavity drops to the minimum step pressure of the current step; and baking the lithium battery again in the current step.

[0009] Optionally, after the current step of baking is completed, entering the next step includes: introducing dry gas into the cavity until the pressure in the cavity reaches a preset drying pressure for the next step; extracting the mixed gas after a preset time until the pressure in the cavity drops to the minimum step pressure for the next step; and baking the lithium battery in the next step.

[0010] Optionally, after the current step of baking is completed, the method further includes: extracting the mixed gas in the cavity until the pressure in the cavity drops to the minimum step pressure of the current step; and taking out the baked lithium battery.

[0011] Optionally, obtaining a baking pressure function of a lithium battery, and determining a maximum step pressure of each step according to the baking pressure function, wherein the maximum step pressure of a current step is greater than the maximum step pressure of a next step, and the minimum step pressure of the current step is equal to the minimum step pressure of the next step, comprises: collecting pressure data of each baking moment from the lowest step pressure to the highest step pressure during the baking process of the lithium battery; obtaining a baking pressure function according to the correspondence between the pressure data and the baking moment by a computer; and determining a maximum step pressure of each step according to the baking pressure function, wherein the maximum step pressure of the current step is greater than the maximum step pressure of the next step, and the minimum step pressure of the current step is equal to the minimum step pressure of the next step.

[0012] Optionally, the execution time of the current step and the next step are both within a preset range.

[0013] An embodiment of the present invention also provides a lithium battery vacuum baking device, comprising a cavity, a control component and a baking component electrically connected to the control component, the cavity is used to accommodate the lithium battery, the control component can control the baking component to bake the lithium battery in multiple steps, wherein the highest step pressure of the current step is greater than the highest step pressure of the next step, and the lowest step pressure of the current step is equal to the lowest step pressure of the next step.

[0014] Optionally, a vacuum component electrically connected to the control component is also included, and the vacuum component is used to extract the mixed gas in the cavity to reduce the pressure in the cavity to the minimum working step pressure.

[0015] Optionally, it also includes an inflation component electrically connected to the control component, and the inflation component is used to add dry gas into the cavity so that the pressure in the cavity reaches a preset drying pressure.

[0016] The beneficial effects of the embodiments of the present invention include:

[0017] The embodiment of the present invention provides a lithium battery vacuum baking method, comprising: obtaining a time-based baking pressure function of the lithium battery, and determining the highest step pressure of each step according to the baking pressure function, wherein the highest step pressure of the current step is greater than the highest step pressure of the next step, and the lowest step pressure of the current step is equal to the lowest step pressure of the next step; entering the first step to bake the lithium battery; judging whether the step baking stop condition is met according to whether the baking time required for the pressure to rise to the highest step pressure of the current step is greater than the preset time, if the baking time is greater than the preset time, the current step baking is ended, and the next step is entered until all the preset steps are executed. The above-mentioned lithium battery vacuum baking method controls the baking process of the lithium battery from the aspect of the rate of pressure rise, and takes the baking time required for the pressure to rise to the highest step pressure of the current step greater than the preset time as the step baking cut-off signal, which can improve the baking consistency, baking efficiency and vacuum pump life, and reduce production energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 One of the flow charts of the lithium battery vacuum baking method provided by an embodiment of the present invention;

[0020] Figure 2 is a baking pressure curve in the prior art;

[0021] Figure 3 A pressure tracking curve provided by an embodiment of the present invention;

[0022] Figure 4 Flow chart 2 of the lithium battery vacuum baking method provided by an embodiment of the present invention;

[0023] Figure 5 Flow chart 3 of the lithium battery vacuum baking method provided by an embodiment of the present invention;

[0024] Figure 6 Flow chart 4 of the lithium battery vacuum baking method provided by an embodiment of the present invention;

[0025] Figure 7 Flow chart 5 of the lithium battery vacuum baking method provided by an embodiment of the present invention;

[0026] Figure 8 Flow chart six of the lithium battery vacuum baking method provided by an embodiment of the present invention;

[0027] Fig. 9 A schematic diagram of the structure of a lithium battery vacuum baking device provided in an embodiment of the present invention.

[0028] Icon: 100- lithium battery vacuum baking device; 110- cavity; 120- control component; 130- baking component; 140- vacuum component; 150- inflation component. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0030] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0032] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0033] In addition, the terms "horizontal", "vertical" and the like do not mean that the components are required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0034] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be a connection between two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] Please refer to Figure 1 The present application embodiment provides a lithium battery vacuum baking method, comprising:

[0036] S100: Obtain a time-based baking pressure function of the lithium battery, and determine the maximum step pressure of each step according to the baking pressure function, wherein the maximum step pressure of the current step is greater than the maximum step pressure of the next step, and the minimum step pressure of the current step is equal to the minimum step pressure of the next step.

[0037] The baking pressure function can be an existing function or a function derived from previous lithium battery baking data; the baking pressure function is a time-based function, and the pressure changes over time. Figure 2 , Figure 2 It is a baking pressure curve in the prior art, wherein the horizontal axis is time in seconds, and the vertical axis is pressure in Pa. Through this curve, the baking pressure function of the lithium battery can be obtained.

[0038] The baking process of lithium batteries is divided into multiple steps, and each step is performed in sequence. It can be understood that as each step is performed in sequence, the water content in the lithium battery gradually decreases, and the rate of pressure rise during the baking process will gradually slow down. The baking pressure function can be used to obtain the pressure rise rate during the baking process of the lithium battery, and according to the pressure rise rate, the maximum step pressure of each step is determined based on the total execution time of each step within the preset range. Given that the minimum step pressure of each step is the same, the maximum working pressure of each step determines the pressure rise range of the step, and the range is related to time and pressure rise rate. Therefore, the baking process of lithium batteries is controlled from the perspective of the rate of pressure rise to achieve faster baking efficiency.

[0039] S200: Enter the first process step to bake the lithium battery.

[0040] After determining the highest pressure of each process step, you can enter the first process step to bake the lithium battery. Figure 3 , Figure 3 The pressure tracking curve provided by the embodiment of the present invention. It can be understood that when executing the first step, the water content of the battery is the highest and the pressure rise rate during baking is the fastest. Therefore, setting the highest step pressure in the first step to the highest value can extend the baking time of the step, thereby achieving the purpose of reducing the number of starts and stops of the vacuum pump and improving the use efficiency of the vacuum pump.

[0041] After the first step is completed, the water content of the lithium battery decreases. If the pressure control range set in the first step is still used, the drying time of the subsequent steps will be extended and the efficiency will be reduced. Therefore, the maximum step pressure of the subsequent steps is reduced successively to achieve faster baking efficiency.

[0042] S300: Determine whether the step baking stop condition is met based on whether the baking time required for the pressure to rise to the highest step pressure of the current step is greater than the preset time. If the baking time is greater than the preset time, the current step baking ends and enters the next step until all preset steps are executed.

[0043] In order to ensure the consistency of battery baking, each step no longer uses a fixed time as the cutoff signal, but determines whether the current step needs to be stopped based on whether the baking time required for the pressure to rise to the highest step pressure of the current step is greater than the preset time. The pressure rise from the lowest step pressure to the highest step pressure during the baking process is defined as a cycle. After a cycle, it is necessary to determine whether the current step needs to be stopped. If the baking time of the cycle is greater than the preset time, it means that it is difficult to efficiently bake the lithium battery within the current pressure range, and it is necessary to end the current step and enter the next step; if the baking time of the cycle is less than or equal to the preset time, it means that the lithium battery can still be efficiently baked within the current pressure range, and it is necessary to stay in the current step and bake the next cycle. Repeat the above process until all the steps are completed, and the baking of the lithium battery can be ended.

[0044] It should be noted that, in actual applications, the number of preset steps can be set according to requirements. For example, Figure 3 As shown, the baking process of the lithium battery is divided into five preset steps, namely the first step, the second step, the third step, the fourth step and the end step. The highest step pressure of each step is 145Pa, 120Pa, 100Pa, 80Pa and 60Pa respectively, and the lowest step pressure is 30Pa.

[0045] To sum up, the above-mentioned lithium battery vacuum baking method controls the baking process of the lithium battery from the perspective of the rate of pressure rise, and uses the baking time required for the pressure to rise to the highest step pressure of the current step to be greater than the preset time as the step baking cutoff signal, which can improve the baking consistency, baking efficiency and vacuum pump life, and reduce production energy consumption.

[0046] Please refer to Figure 4 Optionally, in an achievable manner of an embodiment of the present invention, obtaining a baking pressure function of a lithium battery includes:

[0047] S110: Collecting pressure data at each baking moment from the lowest step pressure to the highest step pressure during the lithium battery baking process.

[0048] S120: using a computer to obtain a baking pressure function according to the corresponding relationship between the pressure data and the baking time.

[0049] S130: Determine the highest step pressure of each step according to the baking pressure function, wherein the highest step pressure of the current step is greater than the highest step pressure of the next step, and the lowest step pressure of the current step is equal to the lowest step pressure of the next step.

[0050] In the experiment or production process, the time-pressure data of lithium battery baking is collected, and the data is analyzed by computer to obtain the time-based baking pressure function of lithium battery. The operation is simple, and the obtained baking pressure function is highly consistent with the actual baking process of lithium battery. The highest step pressure of each process determined by this function is more consistent with the actual baking situation of lithium battery, which can further improve the baking efficiency and baking consistency of lithium battery.

[0051] Please refer to Figure 5 Optionally, in one achievable manner of the embodiment of the present invention, entering the first step of baking the lithium battery includes:

[0052] S210: Entering the first process step, placing the lithium battery in the cavity of the baking device for baking.

[0053] Whether the baking time required for the pressure to rise to the highest step pressure of the current step is greater than the preset time is determined to determine whether the step baking stop condition is met. If the baking time is greater than the preset time, the current step baking ends including:

[0054] S310: Obtain the baking time required for the pressure in the cavity to rise to the highest step pressure of the current step.

[0055] S320: If the baking time is less than or equal to the preset time, the pressure in the cavity is reduced to the minimum step pressure of the current step, and the lithium battery is baked again; if the baking time is greater than the preset time, the current step baking is completed, and the next step or baking is ended.

[0056] The lithium battery is placed in the cavity of the baking device for baking, and the cavity has strong sealing performance, and the baking effect is better. At the same time, the baking process of the lithium battery can be controlled by controlling the pressure rise rate in the cavity, which is easier to achieve.

[0057] After comparing the baking time with the preset time, there are three possible subsequent operations according to the comparison result, namely, one of continuing the current step, entering the next step and ending the baking.

[0058] Please refer to Figure 6 If the current process step is to be continued, optionally, in one achievable manner of an embodiment of the present invention, the pressure in the cavity is reduced to the minimum process step pressure of the current process step, and the lithium battery is baked again, including:

[0059] S321: Drying gas is introduced into the cavity until the pressure in the cavity reaches the preset drying pressure of the current step.

[0060] S322: After a preset time, the mixed gas is extracted until the pressure in the cavity drops to the minimum step pressure of the current step.

[0061] S323: Bake the lithium battery again in the current process step.

[0062] Each process step has a corresponding preset drying pressure. After a cycle, dry gas is introduced into the cavity until the preset drying pressure of the current process step is reached. After the dry gas is mixed with water vapor in the cavity for a certain period of time, the mixed gas in the cavity is extracted to reduce the pressure in the cavity to the minimum process step pressure of the current process step, and the next cycle of lithium battery baking is carried out under the current process step. By introducing dry gas between two cycles to take out the water vapor in the cavity, the baking efficiency and baking effect can be further improved.

[0063] Please refer to Figure 7 If the process is to proceed to the next step, optionally, in one achievable manner of the embodiment of the present invention, the current step of baking is completed, and the process of proceeding to the next step includes:

[0064] S324: Drying gas is introduced into the cavity until the pressure in the cavity reaches a preset drying pressure for the next step.

[0065] S325: After a preset time, the mixed gas is extracted until the pressure in the cavity drops to the minimum step pressure of the next step.

[0066] S326: In the next step, the lithium battery is baked.

[0067] After one process step is executed, dry gas is introduced into the cavity until the preset drying pressure of the next process step is reached. After the dry gas is mixed with water vapor in the cavity for a certain period of time, the mixed gas in the cavity is extracted to reduce the pressure in the cavity to the minimum process step pressure of the next process step, and the lithium battery is baked in the next process step. By introducing dry gas between two process steps to remove water vapor in the cavity, the baking efficiency and baking effect can be further improved.

[0068] Please refer to Figure 8 If the baking is to be terminated, optionally, in an achievable manner of the embodiment of the present invention, the current step of baking is terminated, and after the baking is terminated, the method further includes:

[0069] S327: Extract the mixed gas in the cavity until the pressure in the cavity drops to the minimum step pressure of the current step.

[0070] S328: Take out the baked lithium battery.

[0071] Optionally, in one implementable manner of the embodiment of the present invention, the execution time of the current step and the next step are both within a preset range to improve the efficiency and consistency of baking.

[0072] It should be noted that the preset range is a time period, and the execution time of each step is within the time period.

[0073] Please refer to Fig. 9 This embodiment also provides a lithium battery vacuum baking device 100, including a cavity 110, a control component 120 and a baking component 130 electrically connected to the control component 120, the cavity 110 is used to accommodate lithium batteries, the control component 120 can control the baking component 130 to bake the lithium batteries in multiple steps, wherein the highest step pressure of the current step is greater than the highest step pressure of the next step, and the lowest step pressure of the current step is equal to the lowest step pressure of the next step. The above-mentioned lithium battery vacuum baking device 100 can control the highest step pressure of each step, so that the highest step pressure of each step is reduced in turn, thereby improving baking efficiency and baking consistency.

[0074] Optionally, in an achievable manner, an embodiment of the present invention further includes a vacuum component 140 electrically connected to the control component 120, and the vacuum component 140 is used to extract the mixed gas in the cavity 110 to reduce the pressure in the cavity 110 to the minimum step pressure. With this arrangement, multiple cycles of drying can be performed in one step, and the pressure in the cavity 110 can also meet the minimum step pressure of the next step when switching the step.

[0075] Optionally, in an achievable manner, the embodiment of the present invention further includes an inflation component 150 electrically connected to the control component 120, and the inflation component 150 is used to add dry gas into the cavity so that the pressure in the cavity 110 reaches a preset drying pressure. Inflation and drying are performed between two cycles of the same process step and between two adjacent process steps, and then suction is performed in conjunction with the vacuum component to remove water vapor in the cavity and improve baking efficiency.

[0076] It should be noted that, in this embodiment, the structures of the control component 120, the baking component 130, the vacuum component 140 and the inflation component 150 are not limited, as long as they can achieve their corresponding functions.

[0077] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A lithium battery vacuum baking method, characterized in that: include: Obtaining a time-based baking pressure function of the lithium battery, and determining the highest step pressure of each step according to the baking pressure function, wherein the highest step pressure of the current step is greater than the highest step pressure of the next step, and the lowest step pressure of the current step is equal to the lowest step pressure of the next step; Entering the first step, placing the lithium battery in the cavity of a baking device for baking; Obtaining the baking time required for the pressure in the cavity to rise to the highest step pressure of the current step; If the baking time is less than or equal to the preset time, the pressure in the cavity is reduced to the minimum step pressure of the current step, and the lithium battery is baked again; If the baking time is greater than the preset time, the baking in the current step is finished, and the next step is entered or the baking is finished.

2. The lithium battery vacuum baking method according to claim 1, characterized in that: The step of reducing the pressure in the cavity to the minimum step pressure of the current step and baking the lithium battery again comprises: Introducing drying gas into the cavity until the pressure in the cavity reaches a preset drying pressure of the current step; After a preset time, the mixed gas is extracted until the pressure in the cavity drops to the minimum step pressure of the current step; The lithium battery is baked again in the current process step.

3. The lithium battery vacuum baking method according to claim 1, characterized in that: The current step of baking is completed, and entering the next step includes: Introducing drying gas into the cavity until the pressure in the cavity reaches a preset drying pressure for the next step; After a preset time, the mixed gas is extracted until the pressure in the cavity drops to the minimum step pressure of the next step; In the next step, the lithium battery is baked.

4. The lithium battery vacuum baking method according to claim 1, characterized in that: The current step of baking is completed, and after the baking is completed, the method further includes: Extracting the mixed gas in the cavity until the pressure in the cavity drops to the minimum step pressure of the current step; The baked lithium battery is taken out.

5. The lithium battery vacuum baking method according to claim 1, characterized in that: The step of obtaining a baking pressure function of the lithium battery and determining the highest step pressure of each step according to the baking pressure function, wherein the highest step pressure of the current step is greater than the highest step pressure of the next step, and the lowest step pressure of the current step is equal to the lowest step pressure of the next step, comprises: Collect the pressure data at each baking moment from the lowest step pressure to the highest step pressure during the lithium battery baking process; A baking pressure function is obtained by using a computer according to the corresponding relationship between the pressure data and the baking time.

6. The lithium battery vacuum baking method according to claim 1, characterized in that: The execution time of the current step and the next step are both within a preset range.

7. A lithium battery vacuum baking device, characterized in that: The invention comprises a cavity, a control component and a baking component electrically connected to the control component, wherein the cavity is used to accommodate a lithium battery, and the control component can control the baking component to bake the lithium battery in multiple steps, wherein the highest step pressure of the step is determined according to a time-based baking pressure function of the lithium battery, the highest step pressure of the current step is greater than the highest step pressure of the next step, and the lowest step pressure of the current step is equal to the lowest step pressure of the next step; Obtain the baking time required for the pressure in the cavity to rise to the highest step pressure of the current step; if the baking time is less than or equal to the preset time, reduce the pressure in the cavity to the lowest step pressure of the current step, and bake the lithium battery again; if the baking time is greater than the preset time, the current step baking is ended, and the next step is entered or the baking is ended.

8. The lithium battery vacuum baking device according to claim 7, characterized in that: It also includes a vacuum component electrically connected to the control component, and the vacuum component is used to extract the mixed gas in the cavity to reduce the pressure in the cavity to the minimum working step pressure.

9. The lithium battery vacuum baking device according to claim 8, characterized in that: It also includes an inflation component electrically connected to the control component, and the inflation component is used to add dry gas into the cavity so that the pressure in the cavity reaches a preset drying pressure.

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