Preparation method of high-energy-density laminated battery cell and laminated battery cell

Abstract

The invention discloses a preparation method of a high-energy-density laminated battery cell, which comprises the following operation steps: S1, dividing the total layer number of a battery cell lamination into two parts, each part comprising 2n parts of positive plates, adjusting the position of a battery cell tab, and setting the battery cell tab to be close to the side edge; s2, axially overturning one part by 180 degrees along the length direction of the battery cell, and then combining the part with the other part, so that the tabs of the two parts are close to the left side and the right side of the battery cell respectively; and S3, rubberizing and fixing the two parts of battery cells, respectively carrying out tab pre-welding, and finally, respectively welding the two parts of tabs by using foldable connecting sheets of which the tabs are led out from the middle, so as to obtain the high-energy-density laminated battery cell. The invention also provides the laminated cell prepared by the method. The laminated battery cell structure is adjusted to be layered, steric hindrance is effectively reduced, and meanwhile, under the condition that the size of the battery cell is not changed, the reserved position of an empty foil area is reduced, active material loads are increased, and energy density is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a method for preparing a high energy density laminated battery cell and a laminated battery cell. Background Art

[0002] The capacity of laminated cells is generally increased by increasing the number of electrode layers, thick coating and other processes to increase the active material load inside a single cell. However, due to the compaction density of the material itself, the thickness of the electrode cannot be further compressed, and the cell volume increases with the increase in capacity requirements, making it difficult to increase the energy density. At the same time, too thick electrode sheets and too many laminated layers will increase the requirements for the electrode ear welding of the cell. Thick electrode sheets and multi-layered cells need to reserve a longer empty foil area to avoid the difficulty of electrode ear welding caused by the steric hindrance of the electrode sheets. At the same time, the increase of the empty foil area and the reduction of the material area size will lead to a decrease in the cell capacity and energy density, which puts a test on the design of the cell structure. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a method for preparing a high energy density laminated battery cell and a laminated battery cell, which effectively reduces spatial steric hindrance by adjusting the laminated battery cell structure to a layered type. At the same time, without changing the volume of the battery cell, the reserved space in the empty foil area is reduced to increase the active material load to achieve energy density improvement.

[0004] The technical solution provided by the present invention is as follows: A method for preparing a high energy density laminated battery cell comprises the following steps: S1. Divide the total number of battery cell stacking layers into two, each of which contains 2n positive electrode sheets and adjust the position of the battery cell tabs to be close to the side; S2, after turning one part 180 degrees along the length direction of the battery cell, combine it with the other part so that the two parts of the tabs are close to the left and right sides of the battery cell respectively; S3. Fix the two parts of the battery cell with glue, pre-weld the pole ears respectively, and finally use the foldable connecting piece that leads out the pole ears in the middle to weld the two parts of the pole ears respectively, so as to obtain a high energy density laminated battery cell.

[0005] Preferably, in step S1, it is necessary to ensure that at least one side of the outermost electrode sheet is a negative electrode sheet.

[0006] Preferably, the two bare cells used for combination in step S2, one contains 2n+1 layers of negative electrodes, and the other contains 2n layers of negative electrodes.

[0007] Preferably, in the welding process of the foldable connecting sheet and the pole tab in step S3, the welding size of the foldable connecting sheet and the laminated battery cell is controlled so as to fix the position of the middle pole tab.

[0008] A laminated battery core is prepared by the above-mentioned method for preparing a high-energy density laminated battery core.

[0009] The present invention has the following advantages over the prior art: The preparation method of the high energy density laminated battery cell of the present invention reduces the number of laminated layers by half so that the steric hindrance of the pole ear position is also reduced to half of the normal laminated structure, and the reserved size of the foil position can also be reduced accordingly. The reserved size of the outermost foil becomes 1 / 4 of the total thickness of the battery cell pole sheet, the thickness of the covered positive electrode sheet becomes n*(x*2+a), the thickness of the covered negative electrode sheet becomes (n+1)*(y*2+b)-y, and the reserved size of the foil becomes 2nx+(2n+1)y+na+(n+1)b. The reduced part of the reserved size of the foil can be used to increase the coating area of ​​the material zone, realize more active material load & capacity growth, and realize the improvement of energy density when the total volume of the battery cell remains unchanged. Compared with the normal laminated structure, the present invention can save the reserved size of the foil as follows: [4nx+(4n+1)y+2na+(2n+1)b]-[2nx+(2n+1)y+na+(n+1)b]=2nx+2xy+na+nb. This part of the space can be increased to the coating length of the material area, thereby increasing the total capacity and energy density of the battery cell by [(2nx+2xy+na+nb) / C1]%. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0011] Figure 1 It is a structural schematic diagram of each process step of the method for preparing a high energy density laminated battery cell in an embodiment of the present invention; Figure 2 A diagram comparing the structural schematic diagram of the laminated battery core in the embodiment of the present invention and the structural schematic diagram of the existing laminated battery core; Figure 3 It is a comparison diagram of the structural cross-sectional diagram of the laminated battery core in the embodiment of the present invention and the existing laminated structural cross-sectional diagram. DETAILED DESCRIPTION

[0012] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention are clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention.

[0013] like Figure 1-3 As shown, an embodiment of the present invention provides a method for preparing a high energy density laminated battery cell, comprising the following steps: S1. Divide the total number of battery cell stacking layers into two, each of which contains 2n positive electrode sheets and adjust the position of the battery cell tabs to be close to the side; S2, after turning one part 180 degrees along the length direction of the battery cell, combine it with the other part so that the two parts of the tabs are close to the left and right sides of the battery cell respectively; S3. Fix the two parts of the battery cell with glue, pre-weld the pole ears respectively, and finally use the foldable connecting piece that leads out the pole ears in the middle to weld the two parts of the pole ears respectively, so as to obtain a high energy density laminated battery cell.

[0014] In this embodiment, in step S1, it is necessary to ensure that at least one side of the outermost electrode sheet is a negative electrode sheet.

[0015] In this embodiment, the two bare cells used for combination in step S2 include one containing 2n+1 layers of negative electrodes and the other containing 2n layers of negative electrodes.

[0016] In this embodiment, during the welding process of the foldable connecting sheet and the tab in step S3, the welding dimensions of the foldable connecting sheet and the laminated battery cell are controlled so as to fix the position of the middle tab.

[0017] A laminated battery core is prepared by adopting the above-mentioned method for preparing a high energy density laminated battery core.

[0018] In this embodiment, it is assumed that the number of positive electrode layers of the battery cell is 4n, the total number of negative electrode layers is 4n+1, the single-sided thickness of the positive electrode material area is x, the single-sided thickness of the negative electrode material area is y, the positive electrode foil thickness is a, the negative electrode foil thickness is b, the length of the positive electrode sheet area is C1, and the width is C2.

[0019] For the existing laminated structure, the positive / negative pole tabs are located in fixed positions. The outermost empty foil needs to be close to the innermost empty foil and fixed for the pole tab welding. The steric hindrance caused by the thickness increases with the number of laminated layers. The reserved size of the outermost pole foil is at least half of the total pole thickness of the battery cell. The single-sided thickness of the positive pole is x*2+a. Half the thickness of the battery cell includes 4n / 2=2n layers of positive pole, so the thickness of the covered positive pole is 2n*(x*2+a); the single-sided thickness of the negative pole is y*2 +b, half the thickness of the battery cell contains at most 2n+1 layers of negative electrode sheets. The outermost negative electrode material area does not produce steric hindrance, and this part of the thickness needs to be subtracted, so the thickness of the covered negative electrode sheet is (2n+1)*(y*2+b)-y. Therefore, the reserved size of the electrode foil material of the laminated battery cell structure of this embodiment is the sum of the thickness of the covered positive / negative electrode sheets, which is 2n*(x*2+a)+(2n+1)*(y*2+b)-y=4nx+(4n+1)y+2na+(2n+1)b.

[0020] The preparation method of the high energy density laminated battery cell of this embodiment reduces the number of laminated layers by half so that the steric hindrance of the pole ear position is also reduced to half of the normal laminated structure. The reserved size of the foil position can also be reduced accordingly. The reserved size of the outermost foil becomes 1 / 4 of the total thickness of the battery cell pole sheet, the thickness of the covered positive electrode sheet becomes n*(x*2+a), the thickness of the covered negative electrode sheet becomes (n+1)*(y*2+b)-y, and the reserved size of the foil becomes 2nx+(2n+1)y+na+(n+1)b. The reduced part of the reserved size of the foil can be used to increase the coating area of ​​the material zone, realize more active material load & capacity growth, and realize the improvement of energy density when the total volume of the battery cell remains unchanged. Compared with the normal laminated structure, the present invention can save the reserved size of the foil as follows: [4nx+(4n+1)y+2na+(2n+1)b]-[2nx+(2n+1)y+na+(n+1)b]=2nx+2xy+na+nb. This part of the space can be increased to the coating length of the material area, thereby increasing the total capacity and energy density of the battery cell by [(2nx+2xy+na+nb) / C1]%.

[0021] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a high energy density laminated battery cell, characterized in that: The steps are as follows: S1. Divide the total number of battery cell stacking layers into two, each of which contains 2n positive electrode sheets and adjust the position of the battery cell tabs to be close to the side; S2, after turning one part 180 degrees along the length direction of the battery cell, combine it with the other part so that the two parts of the tabs are close to the left and right sides of the battery cell respectively; S3. Fix the two parts of the battery cell with glue, pre-weld the pole ears respectively, and finally use the foldable connecting piece that leads out the pole ears in the middle to weld the two parts of the pole ears respectively, so as to obtain a high energy density laminated battery cell.

2. The method for preparing a high energy density laminated battery cell according to claim 1, characterized in that: In step S1, it is necessary to ensure that at least one side of the outermost electrode sheet is a negative electrode sheet.

3. The method for preparing a high energy density laminated battery cell according to claim 1, characterized in that: The two bare cells used for combination in step S2 include one containing 2n+1 layers of negative electrodes and the other containing 2n layers of negative electrodes.

4. The method for preparing a high energy density laminated battery cell according to claim 1, characterized in that: During the welding process of the foldable connecting sheet and the tab in step S3, the welding dimensions of the foldable connecting sheet and the laminated battery cell are controlled so as to fix the position of the middle tab.

5. A laminated battery cell, characterized in that: The high energy density laminated battery cell is prepared by the preparation method of the high energy density laminated battery cell according to claim 1.

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