Lithium Manganese Battery Production Process and Lithium Manganese Battery

Abstract

The present application discloses a production process of a lithium manganese battery and a lithium manganese battery, which sequentially include the steps of preparing positive and negative electrode plates, assembling a bare battery cell, housing the bare battery cell, top and side sealing, vacuum liquid injection, vacuum pre-sealing, pre-discharging, aging storage, secondary sealing, trimming, and flanging. The pre-discharging step includes: obtaining the electrode plate thickness of the positive electrode plate; determining the number of pre-discharging times of the lithium manganese battery according to the electrode plate thickness; performing a pre-discharging operation on the lithium manganese battery within the pre-discharging step according to the number of pre-discharging times; wherein, the ambient temperature for the lithium manganese battery to perform the pre-discharging operation is 5°C - 50°C and only one secondary sealing step is performed in the production process of the lithium manganese battery. It can effectively improve the subsequent storage and use stability of the battery.

Description

Technical Field

[0001] This application relates to, but is not limited to, the field of lithium manganese battery production, and particularly relates to a production process of lithium manganese batteries and lithium manganese batteries. Background Art

[0002] Currently, the production steps of lithium manganese batteries successively include preparing bare battery cores, casing the bare battery cores, top and side sealing, injecting electrolyte, vacuum pre-sealing, pre-discharging, and side sealing and trimming. Among them, the pre-discharging step is mainly used to remove the adsorbed water and crystal water existing in the positive electrode sheet. If the adsorbed water and crystal water cannot be effectively removed in the pre-discharging step, during the storage or use of the lithium manganese battery, lithium embeds into the positive electrode and reacts with water to generate gas, causing the battery to become soft or bulge, and the internal resistance of the battery increases significantly, seriously affecting the battery capacity. Summary of the Invention

[0003] The embodiments of this application provide a production process of lithium manganese batteries and lithium manganese batteries, which can effectively improve the pre-discharging effect and further improve the subsequent storage and use stability of the batteries.

[0004] In a first aspect, the embodiments of this application provide a production process of lithium manganese batteries, which successively includes the steps of preparing positive and negative electrode sheets, assembling bare battery cores, casing the bare battery cores, top and side sealing, vacuum injecting electrolyte, vacuum pre-sealing, pre-discharging, aging storage, secondary sealing, trimming, and flanging, and is characterized in that:

[0005] Obtain the electrode sheet thickness of the positive electrode sheet;

[0006] Determine the number of pre-discharging times of the lithium manganese battery according to the electrode sheet thickness;

[0007] Perform a pre-discharging operation on the lithium manganese battery within the pre-discharging step according to the number of pre-discharging times;

[0008] Among them, only one secondary sealing step is performed in the production process of the lithium manganese battery.

[0009] According to the production process of lithium manganese batteries in the first aspect embodiments of this application, it has at least the following beneficial effects: the greater the thickness of the positive electrode sheet, the more and more difficult it is to remove the adsorbed water and crystal water existing in the positive electrode sheet. Therefore, the electrode sheet thickness of the positive electrode sheet can be obtained, the number of discharging times of the lithium manganese battery in the pre-discharging step can be determined according to the electrode sheet thickness, and then the lithium manganese battery can be discharged within the pre-discharging step according to the number of pre-discharging times, effectively removing the adsorbed water and crystal water existing in the positive electrode sheet. During the process of removing the adsorbed water and crystal water, gas will be released. Therefore, after the pre-discharging operation, one secondary sealing step can be performed to discharge the gas, and only performing one secondary sealing step can avoid the situation that the battery yield decreases due to multiple encapsulations.

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

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

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

[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 for the lithium manganese battery to perform the pre-discharge operation is 0.2 MPa - 2 MPa.

[0015] According to some embodiments of the first aspect of the present application, the temperature of the aging storage 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 step of stopping the pre-discharge operation when the pre-discharge amount reaches the preset threshold, it further includes:

[0017] Performing an aging storage step on the lithium manganese battery.

[0018] In a second aspect, an embodiment of the present application further provides a lithium manganese battery prepared 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 subsequent description, and some of them will become obvious from the description, or be understood by implementing the present application. The objectives and other advantages of the present application can be achieved and obtained through the structures specifically pointed out in the description, claims, and drawings. Description of the Drawings

[0020] The drawings are used to provide a further understanding of the technical solutions of the present invention, and constitute a part of the description. They are used together with the embodiments of the present invention to explain the technical solutions of the present invention, and do not constitute a limitation to the technical solutions of the present invention.

[0021] Figure 1 It is a flowchart of the pre-discharge step in the lithium manganese battery production process provided by the embodiment of the present application;

[0022] Figure 2 It is a flowchart of the lithium manganese battery production process provided by the embodiment of the present application;

[0023] Figure 3 It is a specific flowchart of the pre-discharge operation provided by the embodiment of the present application. Detailed Embodiments

[0024] Embodiments of the present application will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application and should not be construed as a limitation of the present application.

[0025] In the description of the present application, it should be understood that with regard to the orientation description, such as up, down, front, back, left, right, etc., the orientation or positional relationship indicated is based on the orientation or positional relationship shown in the accompanying drawings. This is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying 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 construed as a limitation of the present application.

[0026] In the description of the present application, the meaning of "several" is one or more, the meaning of "multiple" is two or more, "greater than", "less than", "exceeding", etc. are understood not to include the original number, and "above", "below", "within", etc. are understood to include the original number. If there is a description of "first" and "second", it is only for the purpose of distinguishing technical features and should not be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or the sequence relationship of the indicated technical features.

[0027] In the description of the present application, unless otherwise clearly defined, words such as "set", "installed", "connected", etc. should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above words in the present application in combination with the specific content of the technical solution.

[0028] Refer to Figure 1 , Figure 1 , which is a flowchart of the pre-discharge step in the lithium-manganese battery production process provided for the embodiments of the present application, including but not limited to the following steps:

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

[0030] Step S200, determine the number of pre-discharges of the lithium-manganese battery according to the electrode sheet thickness;

[0031] Step S300, perform a pre-discharge operation on the lithium-manganese battery within the pre-discharge step according to the number of pre-discharges;

[0032] It can be understood that as Figure 2 shown, Figure 2It is a flowchart of the production process of lithium manganese batteries. The production process of lithium manganese batteries successively includes the steps of preparing positive and negative electrode plates, assembling bare battery cores, enclosing the bare battery cores in a case, top and side sealing, vacuum injecting electrolyte, vacuum pre-sealing, pre-discharging, aging storage, secondary sealing, trimming the edges, and folding the edges. Among them, the step of assembling the bare battery core includes alternately stacking or winding the prepared positive and negative electrode plates and the separator and leading out the positive and negative electrodes through the tab. Enclosing the bare battery core in a case includes placing the assembled bare battery core into a soft packaging case, and the case serves to protect the battery core, isolate the external environment, and connect to the external circuit. The top and side sealing step includes sealing the top and side of the case to ensure the stability of the internal environment of the battery core and prevent the leakage of the electrolyte. The vacuum injecting electrolyte step includes injecting an appropriate amount of electrolyte into the battery core in a vacuum environment. The vacuum pre-sealing step includes preliminarily sealing the battery in a vacuum environment to reduce the bubbles and moisture in the electrolyte and improve the stability and safety of the battery. The pre-discharging 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 existing in the positive electrode plate. The aging step includes leaving the battery static to make the battery performance tend to be stable and reduce the performance fluctuations during subsequent use. The secondary sealing step includes removing the gas generated in the pre-discharging step and then performing a final sealing treatment on the battery to ensure that the electrolyte will not leak due to external factors during the use of the battery. The trimming the edges step includes trimming the edges of the battery case to remove the excess material and make the appearance of the battery neater. The folding the edges step includes folding or flattening the edges of the battery case inward to enhance the strength and sealing performance of the case.

[0033] It can be understood that the greater the thickness of the positive electrode plate, the more and the more difficult it is to remove the adsorbed water and crystal water existing in the positive electrode plate. Therefore, the thickness of the positive electrode plate can be obtained, and according to the thickness of the electrode plate, the number of discharges of the lithium manganese battery in the pre-discharging step is determined, and then according to the number of pre-discharges, the pre-discharging operation is performed on the lithium manganese battery in the pre-discharging step to effectively remove the adsorbed water and crystal water existing in the positive electrode plate. Among them, the number of pre-discharges is the number of pre-discharging operations performed on the lithium manganese battery in the pre-discharging step.

[0034] It should be noted that when the thickness of the positive electrode plate reaches the first thickness threshold, the number of pre-discharges is 1 time; when the thickness of the positive electrode plate reaches the second thickness threshold, the number of pre-discharges is 1 time or 2 times; when the thickness of the positive electrode plate reaches the third thickness threshold, the number of pre-discharges is 2 times; when the thickness of the positive electrode plate reaches the fourth thickness threshold, the number of pre-discharges is 2 times or 3 times. 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 plate, the more adsorbed water and crystal water exist in the positive electrode plate, and the longer the time required for pre-discharge. If the time for a single pre-discharge operation of the lithium-manganese battery is too long, lithium ions cannot be fully embedded into the deep layer of the positive electrode plate, and thus the adsorbed water and crystal water in the deep layer of the positive electrode plate cannot be reacted, reducing the storage stability of the lithium-manganese battery. If the time for a single pre-discharge operation of the lithium-manganese battery is too long, it will accelerate the aging process of the battery and reduce the battery life. Therefore, the number of pre-discharge operations in the pre-discharge step can be determined according to the plate area and plate thickness of the positive electrode plate. Through multiple pre-discharge operations and aging storage, the adsorbed water and crystal water in the deep layer of the positive electrode plate can be fully consumed, thereby improving the storage stability of the battery and reducing the phenomena of battery swelling, bulging, and increased internal resistance.

[0036] It should be noted that during the pre-discharge operation of the lithium-manganese battery, some lithium is embedded into the positive electrode plate, and then reacts with adsorbed water and crystal water to generate gas. The second sealing step can discharge the gas inside the lithium-manganese battery. However, the second sealing step requires the battery pack to be re-opened and sealed, resulting in increased consumption of the packaging film and increased exposure times of the battery core, and the performance of the battery deteriorates. Therefore, only one second sealing step is carried out in the production process of the lithium-manganese battery. For example, if two pre-discharge operations are required in the pre-discharge step, then the second sealing step will be carried out 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 carried out after the three pre-discharge operations.

[0037] It should be noted that during the pre-discharge process, a solid electrolyte interphase film is formed on the surfaces of the positive electrode plate and the negative electrode plate. The solid electrolyte interphase film can reduce the reaction between the electrode and the electrolyte, thereby improving the cycle life and stability of the battery. Heating and pressurization can increase the formation rate of the solid electrolyte interphase film, and heating and pressurization can also accelerate the reaction rate of adsorbed water and crystal water. Therefore, the pressure for the pre-discharge operation of the lithium-manganese battery is 0.2 MPa - 2 MPa, and the temperature for the pre-discharge operation of the lithium-manganese battery is 5°C - 50°C, to accelerate the reaction rate of adsorbed water and crystal water and increase the formation rate of the solid electrolyte interphase film. By accelerating the reaction rate of adsorbed water and crystal water, the pre-discharge time can be reduced and the production efficiency of the lithium-manganese battery can be improved. By accelerating the formation rate of the solid electrolyte interphase film, the reaction between the electrode and the electrolyte can be further reduced. Pressurization during the pre-discharge operation can make the positive electrode, separator, and negative electrode fit tightly, squeeze the gas generated during pre-discharge into the airbag, make the pre-discharge more uniform, and the lithium ions released by the negative electrode are evenly embedded into the positive electrode, improving the pre-discharge effect. Pressurization during the pre-discharge operation can reduce the battery thickness and improve the battery thickness consistency.

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

[0039] It should be noted that in this application, the pre-discharge operation can be carried out by means of constant resistance pre-discharge, or constant current pre-discharge, or short-circuit pre-discharge, or immersion pre-discharge, and this application does not make specific limitations.

[0040] It should be noted that after the lithium manganese battery stops the pre-discharge operation, the reaction inside the lithium manganese battery still proceeds slowly. At this time, if other operations are carried out, it may cause damage to the lithium manganese battery. Therefore, an aging storage step can be carried out 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, both the temperature and time of aging storage will affect the yield rate of the lithium manganese battery. Therefore, the temperature of aging storage can be 40 - 60°C, and the time of aging storage can be 12 hours to 72 hours. For example, when the temperature of aging storage is 40°C, the time of aging storage can be 72 hours; when the temperature of aging storage is 60°C, the time of aging storage can be 12 hours.

[0042] Refer to Figure 3 , Figure 3 which is the specific flowchart of the pre-discharge operation provided by the embodiments of this application, including but not limited to the following steps:

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

[0044] Step S500, when the pre-discharge amount reaches the preset threshold, stop the pre-discharge operation.

[0045] It can be understood that if there is too much discharge amount during the pre-discharge operation, it will cause the lithium manganese battery to have low capacity 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 the preset threshold, stop the pre-discharge operation 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 amounts of each pre-discharge operation are calculated separately.

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

[0047] The embodiments of the present application have been described in detail above with reference to the accompanying drawings. However, the present application is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present application within the scope of knowledge possessed by those of ordinary skill in the art.

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; Among them, the ambient temperature of the lithium manganese battery for the pre-discharge operation is 5°C-50°C and only one second sealing step is performed in the lithium manganese battery production process. When the electrode thickness reaches the first thickness threshold, the pre-discharge number is 1 time; when the electrode thickness reaches the second thickness threshold, the pre-discharge number is 1 time or 2 times; when the electrode thickness reaches the third thickness threshold, the pre-discharge number is 2 times; when the electrode thickness reaches the fourth thickness threshold, the pre-discharge number is 2 times or 3 times. The first thickness threshold is 0.1 to 0.3 mm, the second thickness threshold is 0.31 to 0.5 mm, the third thickness threshold is 0.51 to 0.7 mm, and the fourth thickness threshold is 0.71 to 0.9 mm.

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 2, 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.

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