Aluminum-shell lithium battery with diaphragms coated on two sides

Abstract

The aluminum shell lithium battery comprises a positive plate, a negative plate and the diaphragm, the diaphragm comprises a base membrane and a ceramic layer, the ceramic layer is coated on one side of the base membrane, the diaphragm further comprises a first PVDF (polyvinylidene fluoride) layer and a second PVDF layer, the first PVDF layer is coated on the other side of the base membrane, and the second PVDF layer is coated on one side, far away from the base membrane, of the ceramic layer. According to the utility model, the diaphragm is coated on both sides, the pole piece and the diaphragm are bonded under the condition of cold and hot pressing, the roll core is hardened and is not easy to deform, the roll core is not punched open after liquid injection and is in a bonding state all the time, the roll core is not deformed and is not easy to wrinkle when the negative pole piece rebounds, the reject ratio of the thickness of the battery core is reduced, the processing loss is reduced, and the production cost is reduced; contact short circuit of positive and negative plates caused by diaphragm shrinkage can be reduced, the winding short circuit rate is improved, and the service life is prolonged.

Description

Technical Field

[0001] The utility model relates to the technical field of lithium batteries, in particular to an aluminum shell lithium battery using a double-sided coated diaphragm. Background Art

[0002] With the rapid development of the lithium battery industry, lithium-ion batteries have become a hot topic in the current lithium battery industry with their advantages of high energy density, small size, and light weight. Lithium-ion batteries are referred to as lithium batteries, which usually include positive electrodes, negative electrodes, and separators. The separator is located between the positive and negative electrodes. The positive electrode, separator, and negative electrode are wound to form a lithium battery core, and an aluminum shell is provided outside the core to protect the core.

[0003] Among them, the above-mentioned diaphragm is mainly used to isolate the positive and negative electrodes and prevent the electrons in the battery from passing freely, allowing the ions in the electrolyte to pass freely between the positive and negative electrodes; and the existing diaphragm usually includes a base film and a ceramic layer. The ceramic layer is coated on one side of the base film. Since the ceramic layer has no viscosity, the electrode sheet and the diaphragm are in a free relaxation state. During the use of the battery cell, the negative electrode sheet is prone to rebound and produce negative electrode wrinkles, and the winding core is easily expanded and deformed, resulting in poor battery cell thickness. Utility Model Content

[0004] 1. Technical issues to be resolved

[0005] In view of the deficiencies in the prior art, the utility model provides an aluminum shell lithium battery using a double-sided coated diaphragm, which can solve the above technical problems.

[0006] (II) Technical solution

[0007] In order to solve the above technical problems, the utility model provides the following technical solutions: an aluminum shell lithium battery using a double-sided coated diaphragm, comprising a positive electrode sheet, a negative electrode sheet and a diaphragm, the diaphragm comprising a base film and a ceramic layer, the ceramic layer is coated on one side of the base film, the diaphragm also comprises a first PVDF layer and a second PVDF layer, the first PVDF layer is coated on the other side of the base film, and the second PVDF layer is coated on the side of the ceramic layer away from the base film.

[0008] Preferably, the separator is bonded to the negative electrode sheet via a first PVDF layer, and the separator is bonded to the positive electrode sheet via a second PVDF layer.

[0009] Preferably, the base film is a PE film.

[0010] Preferably, the thickness of the base film is 7 μm.

[0011] Preferably, the thickness of the ceramic layer is 3 μm.

[0012] Preferably, the thickness of both the first PVDF layer and the second PVDF layer is 1 μm.

[0013] (III) Beneficial effects

[0014] Compared with the prior art, the utility model provides an aluminum shell lithium battery using a double-sided coated diaphragm, which has the following beneficial effects: the utility model adds a first PVDF layer and a second PVDF layer on the basis of the existing diaphragm, and uses the PVDF layer to bond the electrode sheet and the diaphragm, thereby increasing the viscosity between the diaphragm and the electrode sheet and increasing the hardness of the winding core. It can also better avoid the expansion and deformation of the winding core when the negative electrode sheet rebounds, improve the negative electrode wrinkles, and thus improve the thickness defect rate of the battery cell; in addition, the PVDF layer has excellent corrosion resistance, chemical stability, mechanical properties, etc., so that the winding core is not easily soaked by the electrolyte during the injection process to maintain the bonding state; through the above-mentioned method, the utility model can reduce the short circuit of the positive and negative electrode sheets caused by the shrinkage of the diaphragm, improve the winding short circuit rate, increase the hardness of the winding core, and better maintain the consistency of the battery cell thickness. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a cross-sectional view of an aluminum shell lithium battery using a double-sided coated diaphragm according to the utility model;

[0016] Figure 2 It is a structural schematic diagram of the diaphragm of the utility model.

[0017] The numbers in the figure are: 1 positive electrode sheet, 2 negative electrode sheet, 3 diaphragm, 31 base film, 32 ceramic layer, 33 first PVDF layer, 34 second PVDF layer, 4 aluminum shell, 5 cover plate, 6 positive electrode ear. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0019] The utility model provides an aluminum shell lithium battery using a double-sided coated diaphragm, comprising a positive electrode sheet 1, a negative electrode sheet 2 and a diaphragm 3, wherein the diaphragm 3 comprises a base film 31 and a ceramic layer 32, wherein the ceramic layer 32 is coated on one side of the base film 31. In addition, the diaphragm 3 of the utility model further comprises a first PVDF layer 33 and a second PVDF layer 34, wherein the first PVDF layer 33 is coated on the other side of the base film 31, and the second PVDF layer 34 is coated on the side of the ceramic layer 32 away from the base film 31.

[0020] PVDF, or polyvinylidene fluoride, is a high-performance polymer material with good corrosion resistance, chemical stability, thermal stability, mechanical properties, temperature resistance, wear resistance, adhesion, etc. The utility model bonds the pole pieces (positive pole piece 1, negative pole piece 2) and the diaphragm 3 through the PVDF layer (first PVDF layer 33, second PVDF layer 34), specifically: the diaphragm 3 is bonded to the positive pole piece 1 through the second PVDF layer 34, and the diaphragm 3 is bonded to the negative pole piece 2 through the first PVDF layer 33.

[0021] Specifically, the positive electrode sheet 1, the diaphragm 3, the negative electrode sheet 2, and the diaphragm 3 can be wound by an automatic winding machine to form a roll core of the lithium battery; further, the wound roll core is subjected to existing processes such as hot pressing, cold pressing, or hot and cold pressing to make the PVDF layer bond the electrode sheet and the diaphragm, making the roll core hard and not easy to deform.

[0022] Specifically, the base film 31 is a PE film, the base film 31 may have a thickness of 7 μm, the ceramic layer 32 may have a thickness of 3 μm, and the first PVDF layer 33 and the second PVDF layer 34 may have a thickness of 1 μm, so that the overall thickness of the separator 3 is 12 μm.

[0023] In addition, the lithium battery of the present invention may further include an aluminum shell 4 to protect the winding core; a cover plate 5 may be provided at the top of the lithium battery; and the lithium battery of the present invention may further include a positive electrode ear 6.

[0024] Compared with the prior art, the utility model provides an aluminum shell lithium battery using a double-sided coated diaphragm, which has the following beneficial effects: the utility model adds a first PVDF layer and a second PVDF layer on the basis of the existing diaphragm, and uses the PVDF layer to bond the electrode sheet and the diaphragm, thereby increasing the viscosity between the diaphragm and the electrode sheet and increasing the hardness of the winding core. The diaphragm has good electronic insulation and ionic conductivity, and can better avoid the expansion and deformation of the winding core when the negative electrode sheet rebounds, improve the negative electrode wrinkles, and thus improve the thickness defect rate of the battery cell; in addition, the PVDF layer has excellent corrosion resistance, chemical stability, mechanical properties, etc., so that the winding core is not easily soaked by the electrolyte during the injection process to maintain the bonding state; through the above-mentioned method, the utility model can reduce the short circuit of the positive and negative electrode sheets caused by the shrinkage of the diaphragm, improve the winding short circuit rate, increase the hardness of the winding core, better maintain the consistency of the battery cell thickness, reduce process losses, reduce production costs, and extend the service life of the lithium battery.

[0025] It should be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0026] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An aluminum shell lithium battery using a double-sided coated diaphragm, comprising a positive electrode sheet, a negative electrode sheet and a diaphragm, wherein the diaphragm comprises a base film and a ceramic layer, wherein the ceramic layer is coated on one side of the base film, characterized in that: The diaphragm further includes a first PVDF layer and a second PVDF layer. The first PVDF layer is coated on the other side of the base film, and the second PVDF layer is coated on a side of the ceramic layer away from the base film.

2. The aluminum shell lithium battery using a double-sided coated diaphragm according to claim 1, characterized in that: The separator is bonded to the negative electrode sheet through the first PVDF layer, and the separator is bonded to the positive electrode sheet through the second PVDF layer.

3. The aluminum shell lithium battery using a double-sided coated diaphragm according to claim 1, characterized in that: The base film is a PE film.

4. The aluminum shell lithium battery using a double-sided coated diaphragm according to claim 1, characterized in that: The base film has a thickness of 7 μm.

5. The aluminum shell lithium battery using a double-sided coated diaphragm according to claim 1, characterized in that: The thickness of the ceramic layer is 3 μm.

6. The aluminum shell lithium battery using a double-sided coated diaphragm according to claim 1, characterized in that: The thickness of the first PVDF layer and the second PVDF layer are both 1 μm.

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