Lithium-manganese battery production process and lithium-manganese battery

Abstract

The invention discloses a lithium-manganese battery production process and a lithium-manganese battery, the lithium-manganese battery production process sequentially comprises the steps of preparing a positive plate and a negative plate, assembling a naked battery cell, loading the naked battery cell into a shell, sealing a top side, performing vacuum liquid injection, performing vacuum pre-sealing, performing pre-discharging, performing aging storage, performing secondary sealing, performing edge cutting and performing edge folding, and the pre-discharging step comprises the step of obtaining the thickness of the positive plate; determining the number of pre-discharge times of the lithium-manganese battery according to the thickness of the pole piece; according to the number of times of pre-discharging, performing pre-discharging operation on the lithium-manganese battery in the pre-discharging step; wherein the environment temperature of the pre-discharge operation of the lithium-manganese battery is 5-50 DEG C, and only one-time two-sealing step is carried out in the production process of the lithium-manganese battery. And the subsequent storage and use stability of the battery can be effectively improved.

Description

Technical Field

[0001] The present application relates to but is not limited to the field of lithium manganese battery production, and in particular to a lithium manganese battery production process and a lithium manganese battery. Background Art

[0002] At present, the production steps of lithium-manganese batteries include preparing bare cells, shelling bare cells, top and side sealing, liquid injection, vacuum pre-sealing, pre-discharging and side sealing trimming. Among them, the pre-discharging step is mainly used to remove the adsorbed water and crystal water in the positive electrode. If the adsorbed water and crystal water cannot be effectively removed in the pre-discharging step, during the storage or use of lithium-manganese batteries, lithium will be embedded in the positive electrode, react with water, produce gas, soften or bulge the battery, and greatly increase the internal resistance of the battery, seriously affecting the battery capacity. Summary of the invention

[0003] The embodiments of the present application provide a lithium manganese battery production process and a lithium manganese battery, which can effectively improve the pre-discharge effect, thereby improving the subsequent storage and use stability of the battery.

[0004] In the first aspect, the embodiment of the present application provides a lithium manganese battery production process, which includes the steps of preparing positive and negative electrode sheets, assembling bare cells, shelling bare cells, top and side sealing, vacuum liquid injection, vacuum pre-sealing, pre-discharging, aging storage, secondary sealing, trimming, and folding, characterized in that:

[0005] Obtain the thickness of the positive electrode;

[0006] Determining the pre-discharge times of the lithium manganese battery according to the thickness of the electrode sheet;

[0007] According to the pre-discharge times, performing a pre-discharge operation on the lithium manganese battery in the pre-discharge step;

[0008] Among them, the second sealing step is only performed once in the lithium manganese battery production process.

[0009] According to the lithium manganese battery production process of the first aspect of the present application, there are at least the following beneficial effects: the greater the thickness of the positive electrode sheet, the more adsorbed water and crystal water there are in the positive electrode sheet and the more difficult it is to remove them. Therefore, the thickness of the positive electrode sheet can be obtained, and the number of times the lithium manganese battery is discharged in the pre-discharge step can be determined according to the thickness of the electrode sheet. Then, according to the number of pre-discharges, the lithium manganese battery is discharged in the pre-discharge step to effectively remove the adsorbed water and crystal water in the positive electrode sheet. In the process of removing the adsorbed water and crystal water, gas will be released. Therefore, after the pre-discharge operation, a second sealing step is performed to discharge the gas, and only a second sealing step is performed once to avoid the situation where the battery yield rate decreases due to multiple packaging.

[0010] According to some embodiments of the first aspect of the present application, the pre-discharging operation includes:

[0011] Obtaining the pre-discharge amount of the lithium manganese battery;

[0012] When the pre-discharge amount reaches a preset threshold, the pre-discharge operation is stopped.

[0013] According to some embodiments of the first aspect of the present application, the preset threshold is 1%-8% of the rated capacity of the lithium manganese battery.

[0014] According to some embodiments of the first aspect of the present application, the pressure of the lithium manganese battery performing the pre-discharge operation is 0.2 MPa-2 MPa.

[0015] According to some embodiments of the first aspect of the present application, the aging storage temperature is 40° C.-60° C., and the storage time is 12 hours to 72 hours.

[0016] According to some embodiments of the first aspect of the present application, after the pre-discharge amount reaches a preset threshold and the pre-discharge operation is stopped, the method further includes:

[0017] The lithium manganese battery is subjected to an aging storage step.

[0018] In a second aspect, an embodiment of the present application further provides a lithium manganese battery produced by the lithium manganese battery production process described in the first aspect.

[0019] Other features and advantages of the present application will be described in the following description, and partly become apparent from the description, or understood by practicing the present application. The purpose and other advantages of the present application can be realized and obtained by the structures specifically pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings are used to provide a further understanding of the technical solution of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the technical solution of the present invention and do not constitute a limitation on the technical solution of the present invention.

[0021] Figure 1 A flow chart of the pre-discharge step in the lithium manganese battery production process provided in the embodiment of the present application;

[0022] Figure 2 A flow chart of a lithium manganese battery production process provided in an embodiment of the present application;

[0023] Figure 3 A specific flow chart of the improved pre-discharge operation according to the embodiment of the present application. DETAILED DESCRIPTION

[0024] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0025] In the description of the present application, it should be understood that descriptions involving orientation, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0026] In the description of this application, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed", etc. are understood to exclude the number itself, and "above", "below", "within", etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0027] In the description of this application, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in this application based on the specific content of the technical solution.

[0028] Reference Figure 1 , Figure 1 The flowchart of the pre-discharge step in the lithium manganese battery production process provided in the embodiment of the present application includes but is not limited to the following steps:

[0029] Step S100, obtaining the thickness of the positive electrode sheet;

[0030] Step S200, determining the pre-discharge times of the lithium manganese battery according to the thickness of the electrode sheet;

[0031] Step S300, performing a pre-discharge operation on the lithium manganese battery in a pre-discharge step according to the pre-discharge times;

[0032] It is understandable that if Figure 2 As shown, Figure 2The flowchart of the lithium manganese battery production process includes the steps of preparing positive and negative electrode sheets, assembling bare cells, shelling bare cells, top and side sealing, vacuum injection, vacuum pre-sealing, pre-discharging, aging storage, secondary sealing, trimming, and folding, wherein the step of assembling bare cells includes alternately stacking or winding the prepared positive and negative electrode sheets with the diaphragm and leading the positive and negative electrodes through the pole ears. Shelling bare cells includes placing the assembled bare cells into a soft packaging shell, which protects the cells, isolates the external environment, and connects the external circuit. The top and side sealing step includes sealing the top and sides of the shell to ensure the stability of the internal environment of the cells and prevent electrolyte leakage. The vacuum injection step includes injecting an appropriate amount of electrolyte into the cells under a vacuum environment. The vacuum pre-sealing step includes preliminarily sealing the battery under a vacuum environment to reduce bubbles and moisture in the electrolyte and improve the stability and safety of the battery. The pre-discharge step includes discharging the battery with a small current to activate the chemical reaction inside the battery and remove the adsorbed water and crystal water in the positive electrode sheet. The aging step involves placing the battery in a static state to stabilize the battery performance and reduce performance fluctuations during subsequent use. The second sealing step involves removing the gas generated in the pre-discharge step and then performing a final sealing treatment on the battery to ensure that the electrolyte will not leak due to external factors during use. The trimming step involves trimming the edges of the battery casing to remove excess material and make the battery look neater. The folding step involves folding or flattening the edges of the battery casing inward to enhance the strength and sealing of the casing.

[0033] It is understandable that the greater the thickness of the positive electrode sheet, the more adsorbed water and crystal water there are in the positive electrode sheet and the more difficult it is to remove them. Therefore, the thickness of the positive electrode sheet can be obtained, and the number of times the lithium manganese battery is discharged in the pre-discharge step can be determined according to the thickness of the electrode sheet. Then, according to the number of pre-discharges, the lithium manganese battery is pre-discharged in the pre-discharge step to effectively remove the adsorbed water and crystal water in the positive electrode sheet. Among them, the number of pre-discharges is the number of times the lithium manganese battery is pre-discharged in the pre-discharge step.

[0034] It should be noted that when the thickness of the positive electrode sheet reaches the first thickness threshold, the pre-discharge number is 1; when the thickness of the positive electrode sheet reaches the second thickness threshold, the pre-discharge number is 1 or 2; when the thickness of the positive electrode sheet reaches the third thickness threshold, the pre-discharge number is 2; when the thickness of the positive electrode sheet reaches the fourth thickness threshold, the pre-discharge number is 2 or 3. Among them, the first thickness threshold can be 0.1 to 0.3 mm, the second thickness threshold can be 0.31 to 0.5 mm, the third thickness threshold can be 0.51 to 0.7 mm, and the fourth thickness threshold can be 0.71 to 0.9 mm.

[0035] It should be noted that the greater the thickness of the positive electrode sheet, the more adsorbed water and crystal water there are in the positive electrode sheet, and the longer the pre-discharge time is required. If the lithium-manganese battery is in a single pre-discharge operation for too long, the lithium ions will not be fully embedded in the deep layer of the positive electrode sheet, and the adsorbed water and crystal water in the deep layer of the positive electrode sheet will not be reacted, reducing the storage stability of the lithium-manganese battery. If the lithium-manganese battery is in a single pre-discharge operation for too long, the aging process of the battery will be accelerated and the battery life will be reduced. Therefore, the number of pre-discharges in the pre-discharge step can be determined according to the electrode area and electrode thickness of the positive electrode sheet. Through multiple pre-discharges and aging storage, the adsorbed water and crystal water in the deep layer of the positive electrode sheet can be fully consumed, thereby improving the storage stability of the battery and reducing the phenomenon of battery flatulence, bulging, and increased internal resistance.

[0036] It should be noted that during the pre-discharge operation of the lithium-manganese battery, part of the lithium will be embedded in the positive electrode sheet, which will then react with adsorbed water and crystal water to produce gas. The second sealing step can discharge the gas inside the lithium-manganese battery, but the second sealing step requires the battery pack to be re-cut and sealed, resulting in increased consumption of the packaging film, increased exposure of the battery cell, and decreased battery performance. Therefore, the second sealing step is only performed once in the lithium-manganese battery production process. For example, if two pre-discharge operations are required in the pre-discharge step, then the second sealing step will be performed after the two pre-discharge operations. Similarly, if three pre-discharge operations are required in the pre-discharge step, then the second sealing step will be performed after the three pre-discharge operations.

[0037] It should be noted that during the pre-discharge process, a solid electrolyte interphase membrane is formed on the surface of the positive electrode sheet and the negative electrode sheet. The solid electrolyte interphase membrane can reduce the reaction between the electrode and the electrolyte, thereby improving the cycle life and stability of the battery. Heating and pressurizing can increase the generation rate of the solid electrolyte interphase membrane, and heating and pressurizing can accelerate the reaction rate of adsorbed water and crystallized water. Therefore, the pressure of the lithium manganese battery for pre-discharge operation is 0.2 MPa-2 MPa, and the temperature of the lithium manganese battery for pre-discharge operation is 5°C-50°C, which accelerates the reaction rate of adsorbed water and crystallized water and increases the generation rate of the solid electrolyte interphase membrane. By accelerating the reaction rate of adsorbed water and crystallized water, the pre-discharge time can be reduced and the production efficiency of lithium manganese batteries can be improved. By accelerating the generation rate of the solid electrolyte interphase membrane, the reaction between the electrode and the electrolyte can be further reduced. Pressurizing during the pre-discharge operation can make the positive electrode, separator, and negative electrode fit tightly, and expel the gas generated by the pre-discharge into the air bag, making the pre-discharge more uniform, and the lithium ions released by the negative electrode are evenly embedded in the positive electrode, improving the pre-discharge effect. Pressurizing during the pre-discharge operation can reduce the battery thickness and improve the consistency of the battery thickness.

[0038] Specifically, in some embodiments, the pressure of the lithium manganese battery during the pre-discharge operation is 0.35 MPa-0.4 MPa, and the temperature of the lithium manganese battery during the pre-discharge operation is 25° C.-50° C.

[0039] It should be noted that the pre-discharge operation in the present application can be performed by constant resistance pre-discharge, constant current pre-discharge, short circuit pre-discharge, or immersion pre-discharge, and the present application does not make any specific limitation.

[0040] It should be noted that after the pre-discharge operation of the lithium manganese battery stops, the reaction inside the lithium manganese battery is still slowly proceeding. At this time, if other operations are performed, the lithium manganese battery may be damaged. Therefore, an aging storage step can be performed after each pre-discharge operation to improve the stability of the lithium manganese battery.

[0041] It should be noted that in the aging storage step, the aging storage temperature and time will affect the yield of the lithium manganese battery. Therefore, the aging storage temperature can be 40-60°C, and the aging storage time can be 12 hours to 72 hours. For example, when the aging storage temperature is 40°C, the aging storage time can be 72 hours; when the aging storage temperature is 60°C, the aging storage time can be 12 hours.

[0042] Reference Figure 3 , Figure 3 The specific flow chart of the pre-discharge operation improved by the embodiment of the present application includes but is not limited to the following steps:

[0043] Step S400, obtaining the pre-discharge amount of the lithium manganese battery;

[0044] Step S500: When the pre-discharge amount reaches a preset threshold, the pre-discharge operation is stopped.

[0045] It is understandable that if the discharge amount is too much during the pre-discharge operation, it will lead to low capacity of the lithium manganese battery and reduce the service life of the battery. Therefore, the pre-discharge amount of the lithium manganese battery can be obtained during the pre-discharge operation of the lithium manganese battery. When the pre-discharge amount reaches a preset threshold, the pre-discharge operation is stopped to avoid low capacity of the lithium manganese battery. Among them, if multiple pre-discharge operations are required in the pre-discharge step, the pre-discharge amount of each pre-discharge operation is calculated separately.

[0046] It should be noted that the preset threshold value can be 1%-8% of the rated capacity of the lithium manganese battery. In addition, the preset threshold value can also be determined according to the thickness of the positive electrode sheet and the number of pre-discharges. For example, if the thickness of the positive electrode sheet is 0.3 mm and the number of pre-discharges is 1, the preset threshold value is 6% of the rated capacity of the lithium manganese battery; if the thickness of the positive electrode sheet is 0.6 mm and the number of pre-discharges is 2, the preset threshold value for the first pre-discharge is 4% of the rated capacity of the lithium manganese battery, and the preset threshold value for the second pre-discharge is 3% of the rated capacity of the lithium manganese battery; if the thickness of the positive electrode sheet is 0.8 mm and the number of pre-discharges is 3, the preset threshold value for the first pre-discharge is 3%, the preset threshold value for the second pre-discharge is 3%, and the preset threshold value for the third pre-discharge is 2%. Among them, if multiple pre-discharge operations are performed in the pre-discharge step, the total discharge amount of the multiple pre-discharge operations shall not exceed 8% of the rated capacity.

[0047] The embodiments of the present application are described in detail above in conjunction with the accompanying drawings, but the present application is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in the relevant technical field without departing from the purpose of the present application.

Claims

1. A lithium manganese battery production process, comprising the steps of preparing positive and negative electrode sheets, assembling bare cells, casing bare cells, top and side sealing, vacuum liquid injection, vacuum pre-sealing, pre-discharging, aging storage, secondary sealing, trimming, and folding, characterized in that: Obtain the thickness of the positive electrode; Determining the pre-discharge times of the lithium manganese battery according to the thickness of the electrode sheet; According to the pre-discharge times, performing a pre-discharge operation on the lithium manganese battery in the pre-discharge step; The ambient temperature of the lithium manganese battery for the pre-discharge operation is 5° C.-50° C. and the second sealing step is performed only once in the lithium manganese battery production process.

2. The manganese battery production process according to claim 1, characterized in that: The pre-discharge operation includes: Obtaining the pre-discharge amount of the lithium manganese battery; When the pre-discharge amount reaches a preset threshold, the pre-discharge operation is stopped.

3. The manganese battery production process according to claim 2, characterized in that: The preset threshold is 1%-8% of the rated capacity of the lithium manganese battery.

4. The manganese battery production process according to claim 1, characterized in that: The pressure of the lithium manganese battery during the pre-discharge operation is 0.2 MPa-2 MPa.

5. The manganese battery production process according to claim 1, characterized in that: The aging storage temperature is 40°C-60°C, and the storage time is 12 hours to 72 hours.

6. The manganese battery production process according to claim 1, characterized in that: After the pre-discharge amount reaches a preset threshold and the pre-discharge operation is stopped, the method further includes: The lithium manganese battery is subjected to an aging storage step.

7. A lithium manganese battery, characterized in that: The lithium manganese battery is made by the lithium manganese battery production process according to any one of claims 1 to 6.

Images