CN102683742A - Lithium ion battery cell and preparation method thereof - Google Patents

Abstract

The invention belongs to the technical field of lithium ion batteries, and particularly relates to a lithium ion battery cell which comprises a positive plate and a negative plate which are mutually stacked, wherein the number of the positive plate and the negative plate is at least two, the difference between the number of the positive plate and the number of the negative plate is 1, the lithium ion battery cell further comprises a wound first diaphragm and a wound second diaphragm, the positive plate is arranged on the same side of the first diaphragm, the negative plate is arranged on the same side of the second diaphragm, and the first diaphragm and the second diaphragm are alternately spaced between the adjacent positive plate and the adjacent negative plate in the direction from the innermost circle to the outermost circle of the battery cell. Compared with the prior art, the multi-layer pole pieces are connected in parallel, so that the internal impedance of the battery cell is reduced, the polarization is reduced, and the discharge platform is improved; the parallel connection of the pole pieces improves the high-rate charge and discharge capacity of the battery core; the battery cell has the advantages that the pole pieces are stacked together, the internal structure is uniform, and the stress is uniformly distributed, so that the battery cell is not easy to deform. In addition, the invention also discloses a preparation method of the battery cell.

Description

A kind of lithium ion cell and preparation method thereof

technical field

The invention belongs to the technical field of lithium ion batteries, in particular to a lithium ion battery cell and a preparation method thereof.

Background technique

As the most representative energy storage device in the field of new energy, lithium-ion batteries occupy an irreplaceable position in the fields of mobile electronics, power batteries and energy storage power stations. Especially in the field of power batteries, there are higher requirements for the high rate charge and discharge performance of batteries.

At present, there are two main methods of cell preparation: winding method and lamination method. Relatively speaking, the winding method is more efficient, but the internal structure of the cell rolled out by the winding method is not uniform, and the stress on different positions of the cell is also different, which causes some thick cells and easy thickness rebound. The battery cell is easily deformed during charging and discharging. Moreover, the battery prepared by winding method also has the disadvantage of relatively large internal resistance. The advantage of the lamination method is that the parallel stacking method makes the internal resistance of the battery cells smaller, the discharge platform is higher, and the internal force is uniform, and the battery prepared by the lamination method has a better high-rate charge and discharge capacity, which is suitable for application In the field of power batteries. However, in the process of preparing batteries by stacking, electrode units need to be prepared to complete the stacking, the process is cumbersome and complicated, and the efficiency is not high.

For example, the Chinese patent application with the application patent number CN200880120848.0 records that a lithium-ion battery cell is prepared by stacking and winding a two-part battery and a full battery. Specifically, this method is to heat-synthesize the positive electrode sheet, separator, and negative electrode sheet into two sub-batteries and full battery units, and then place each unit on a separate separator and heat-seal it, and wind it into a cell assembly. The process of this method is relatively complicated, and thermal compounding needs to be carried out twice, and the battery unit must be prepared first, so the efficiency is low. Moreover, due to the two-time heat recombination, the alignment accuracy between the pole piece and the diaphragm, and between the pole pieces is not easy to control.

In view of this, it is necessary to provide a lithium ion battery preparation method that can reduce the internal resistance of the battery cell, improve the deformation of the battery cell, ensure production efficiency and simplify the process, and the lithium ion battery prepared by this method ion cell.

Contents of the invention

One of the objectives of the present invention is to provide a lithium-ion battery cell for the deficiencies of the prior art, which combines the advantages of the winding method and the lamination method, and overcomes the shortcomings of the winding method and the lamination method , with small internal resistance and good high rate charge and discharge capacity, uniform internal force, not easy to deform.

In order to achieve the above object, the present invention adopts the following technical scheme: a lithium-ion battery cell, including a positive electrode sheet and a negative electrode sheet stacked on each other, the number of the positive electrode sheets is at least two, and the number of the negative electrode sheets is At least two pieces, and the number of positive pole pieces and the number of negative pole pieces differ by 1 piece, so that the positive and negative poles can be stacked in sequence; each positive pole piece is provided with a positive pole lug, and each negative pole piece is provided with Negative pole tabs, two adjacent positive pole tabs are welded and connected, two adjacent negative pole tabs are welded and connected, and the wound first diaphragm and the wound second diaphragm are also included. Each positive pole piece is arranged on the On the same side of the first diaphragm, each negative electrode sheet is arranged on the same side of the second diaphragm, in the direction from the innermost ring to the outermost ring of the battery core, the first diaphragm and the The second separators are alternately spaced between the adjacent positive electrode sheets and the negative electrode sheets.

As an improvement of the lithium ion battery cell of the present invention, the length of the first diaphragm and the length of the second diaphragm are both 0.1-2mm larger than the length of the negative electrode sheet, and the width of the first diaphragm and the length of the The width of the second separator is 0.1-2mm larger than the width of the negative electrode sheet; the length of the negative electrode sheet is 0.1-2mm larger than the length of the positive electrode sheet, and the width of the negative electrode sheet is larger than the width of the positive electrode sheet 0.1-2mm, to prevent the contact between the positive electrode and the negative electrode, and prevent the occurrence of lithium precipitation, so as to ensure the safety of the battery.

As an improvement of the lithium-ion battery cell of the present invention, each positive electrode sheet is fixedly arranged on the first separator by heat sealing to ensure that the positive electrode sheet and the first separator do not slide each other; each negative electrode sheet is heat-sealed. It is fixedly arranged on the second diaphragm to ensure that the negative electrode sheet and the second diaphragm do not slide against each other. At the same time, it can also improve the hardness of the battery.

As an improvement of the lithium-ion battery cell of the present invention, the end of the first diaphragm and the end of the second diaphragm are both pasted with glue.

As an improvement of the lithium ion battery cell of the present invention, the positive electrode tab and the negative electrode tab are located on both sides of the front end of the battery cell.

Compared with the prior art, the present invention has the following advantages: First, the parallel connection of multi-layer pole pieces reduces the internal impedance of the cell, reduces the polarization, improves the discharge platform, and is closer to the real discharge platform of the material itself.

Second, the parallel connection of pole pieces improves the high rate charge and discharge capability of the battery cell.

Thirdly, since the pole pieces of the battery cell of the present invention are stacked together, the internal structure is uniform, and the stress is uniformly distributed, so deformation is not easy to occur.

Another object of the present invention is to provide a preparation method of a lithium-ion battery, comprising the following steps: in the first step, at least two positive pole pieces with positive pole tabs are arranged at intervals on one side of the first diaphragm, and At least two negative electrode sheets with negative electrode tabs are arranged at intervals on one side of the second separator, and the number of positive electrode sheets is different from the number of negative electrode sheets by one piece, and the extra piece corresponds to a blank separator, and the rest The positive electrode piece and the negative electrode piece are set in one-to-one correspondence; that is to say, the starting position of the first diaphragm is not placed with the pole piece (positive electrode piece or negative electrode piece), while the starting position of the second diaphragm is placed with the pole piece (positive electrode piece or negative electrode piece). negative plate).

Among them, the diaphragm (the first diaphragm and the second diaphragm) is composed of a polymer with ion conductivity, the positive electrode sheet is made by coating the positive electrode material on the surface of the positive electrode current collector, and the negative electrode sheet is made by coating the negative electrode material on the surface of the positive electrode current collector. Manufactured on the surface of the negative electrode collector, the separator must have sufficient length and width to wrap all the pole pieces to prevent direct contact between the positive electrode piece and the negative electrode piece. It should exceed the corresponding positive plate by 0.1-2mm to ensure the safety of the battery.

The distance between the positive electrode sheets arranged at intervals on the first separator increases sequentially from the initial end of the winding, and the distance between the negative electrode sheets arranged at intervals on the second separator increases sequentially from the initial end of the winding, so as to ensure that the electrode good alignment between slices).

In the second step, the first diaphragm provided with the positive electrode sheet and the second diaphragm provided with the negative electrode sheet are aligned, and the first diaphragm and the second diaphragm are separately arranged on both sides of the positive electrode sheet or the negative electrode sheet.

The third step is to start winding from one end of the blank separator, so that the positive electrode sheet and the negative electrode sheet are stacked in sequence, and then the positive electrode tab is welded and connected, and the negative electrode tab is welded and connected to obtain a lithium ion battery. Among them, the parallel welding of the tabs can reduce the internal resistance and increase the discharge rate of the battery.

In order to further improve the stability between the positive electrode sheet, the first separator, the negative electrode sheet and the second separator, after stacking the positive electrode sheet, the first separator, the negative electrode sheet and the second separator in a certain order, it is necessary to perform heat sealing at a certain temperature, The temperature range of heat sealing is 20-200°C to ensure that the pole piece and the diaphragm do not slide relative to each other.

Among them, after the winding is completed, the uppermost and lowermost pole pieces of the battery can be either double-sided coated positive pole pieces or double-sided coated negative pole pieces, or single-side coated positive electrode current collectors or The negative electrode collector coated on one side is preferably a positive electrode collector coated on one side or a negative electrode collector coated on one side, because this can prevent waste of active materials and increase the energy density of the battery. More preferably, both the uppermost layer and the lowermost electrode sheet of the battery cell are negative electrode collectors coated on one side, because this can also save costs.

As an improvement of the preparation method of the lithium-ion battery cell of the present invention, in the first step, each positive electrode sheet is fixed on the first separator by heat sealing, and each negative electrode sheet is fixed on the second separator by heat sealing. The separator prevents sliding between the positive electrode sheet and the first separator, and prevents sliding between the negative electrode sheet and the second separator, thereby improving the safety performance of the battery.

As an improvement of the preparation method of the lithium-ion battery cell of the present invention, in the first step, the positive tabs of adjacent positive plates are alternately arranged left and right; the negative tabs of adjacent negative plates are alternately arranged left and right to ensure the same polarity The alignment of the ears is good for welding.

As an improvement of the preparation method of the lithium-ion battery cell of the present invention, after the third step of winding is completed, glue is pasted on the end of the first diaphragm and the end of the second diaphragm, and the first diaphragm and the second diaphragm are The two diaphragms are fixed on the electric core.

As an improvement of the preparation method of the lithium-ion battery cell of the present invention, after the third step of winding is completed, the positive electrode tabs are all located on one side of the front end of the battery core, and the negative electrode tabs are all located on the front end of the battery cell. The other side of the front end of the core is convenient for welding the positive pole lug and the negative pole lug, and it is convenient for external electrical appliances.

Compared with the prior art, the preparation method of the present invention is compared with the existing stacking method, because there is no need to manufacture a large number of battery cells (two sub-cells or full cells), so the process is simplified and the efficiency is higher. Moreover, the prepared battery has both the advantages of the battery prepared by the winding method and the laminated method, and has not only small internal resistance, but also small deformation.

Description of drawings

The present invention and its beneficial technical effects will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

FIG. 1 is a schematic diagram of the arrangement structure of the positive electrode sheet on the first separator in Example 1 of the present invention.

FIG. 2 is a schematic diagram of the arrangement structure of the negative electrode sheet on the second separator in Example 1 of the present invention.

FIG. 3 is a schematic structural view of the battery cell in Example 1 of the present invention when it is wound.

FIG. 4 is a schematic structural view of the battery cell according to Embodiment 1 of the present invention.

FIG. 5 is a schematic diagram of the arrangement structure of the positive electrode sheet on the first separator according to Example 2 of the present invention.

FIG. 6 is a schematic diagram of the arrangement structure of the negative electrode sheet on the second separator according to Example 2 of the present invention.

FIG. 7 is a schematic structural view of the battery cell according to Example 2 of the present invention when it is wound.

FIG. 8 is a schematic structural view of a battery cell according to Embodiment 2 of the present invention.

Detailed ways

The present invention and its beneficial effects are described in detail below in conjunction with specific embodiments, however, the embodiments of the present invention are not limited thereto.

Embodiment 1: the preparation method of a kind of lithium ion cell provided by the present invention comprises the following steps: the first step, in the present embodiment, the number of sheets of positive electrode sheet 1 is less than the number of sheets of negative electrode sheet 3, and the number of sheets of positive electrode sheet The number of sheets 1 is at least 2, and each positive electrode sheet 1 is provided with a positive electrode tab 11 , and each negative electrode sheet 3 is provided with a negative electrode tab 31 . As shown in FIGS. 1 and 2 , the positive electrode sheet 1 with positive electrode tabs 11 is fixed on one side of the first separator 2 by heat sealing at intervals, wherein the initial position of the first separator 2 does not place the positive electrode sheet 1 . The negative electrode sheet 3 with the negative electrode tabs 31 left is fixed on one side of the second separator 4 by heat sealing at intervals, wherein the initial position of the second separator 4 is placed with the negative electrode sheet 3 . The rest of the positive electrode sheets 1 and the negative electrode sheets 3 are provided in one-to-one correspondence. In the length direction of the first diaphragm 2, starting from the initial position, the spacing between adjacent positive electrode sheets 1 gradually increases; in the length direction of the second diaphragm 4, starting from the initial position, the adjacent negative electrode sheets 3 The distance between them gradually increases. The positive pole lugs 11 of adjacent positive pole sheets 1 are arranged alternately left and right; The positive electrode lug 11 on the positive electrode sheet 1 adjacent to the left and right of the sheet 1 is arranged on the left side, and the same is true for the negative electrode sheet 3 . Moreover, for the positive electrode sheet 1 and the negative electrode sheet 3 that are oppositely arranged, the positive electrode tabs 11 and the negative electrode tabs 31 are alternately arranged.

In the second step, as shown in Figure 3, the first diaphragm 2 provided with the positive electrode sheet 1 and the second diaphragm 4 provided with the negative electrode sheet 3 are aligned and placed, that is, the positive electrode sheet 1 and the negative electrode at the rest of the position except the initial position The sheets 3 are aligned, and the first separator 2 and the second separator 4 are separately arranged on both sides of the negative electrode sheet 3 , that is, the first separator 2 is located between the positive electrode sheet 1 and the negative electrode sheet 3 .

The third step is to start winding from the blank end of the first separator 2, so that the negative electrode sheet 3 at the starting position of the second separator 4 is stacked on the positive electrode sheet 1 on the side of the first separator 2, and continue winding in this direction , and then fix the positive electrode sheet 1, the first separator 2, the negative electrode sheet 3 and the second separator 4 together by means of heat sealing. Mutual sliding between the diaphragm 2 and the second diaphragm 4 ensures the safety of the battery and at the same time enhances the hardness of the battery. After the winding is completed, paste the glue 5 on the end of the first diaphragm 2 and the end of the second diaphragm 4. At this time, the positive pole tab 11 is on one side of the battery core, and the negative pole tab 31 is located on the other side of the battery core. side, and then weld the positive tab 11 and the negative tab 31 to obtain a lithium-ion cell.

The schematic diagram of the structure of the lithium-ion cell obtained by the above method is shown in Figure 4, including positive electrode sheets 1 and negative electrode sheets 3 stacked on each other, and the number of positive electrode sheets 1 is one less than the number of negative electrode sheets 3, and the positive electrode sheets 1 are all provided with a positive electrode tab 11, and the negative electrode sheets 3 are all provided with a negative electrode tab 31, the positive electrode tab 11 is welded and connected, and the negative electrode tab 31 is welded and connected, and also includes a wound first diaphragm 2 and a wound second diaphragm 4. The positive electrode sheets 1 are all arranged on the same side of the first separator 2, and the negative electrode sheets 3 are all arranged on the same side of the second separator 4. In the direction from the innermost ring to the outermost ring of the cell, the first separator 2 and the second separator 4 are alternately spaced between adjacent positive electrode sheets 1 and negative electrode sheets 3 . The positive pole tab 11 and the negative pole tab 31 are located on both sides of the front end of the cell. The front end of the cell refers to the end where the tab protrudes.

The uppermost and lowermost pole pieces of the cell are negative pole pieces 3, which can be negative pole pieces 3 coated with negative material on both sides, or negative pole pieces 3 coated with negative material on one side. The side not coated with the negative electrode material is located on the outermost side. In addition, the positive tabs 11 are located on one side of the cell, and the negative tabs 31 are located on the other side of the cell.

The end of the first diaphragm 2 and the end of the second diaphragm 4 are pasted with glue 5 . Of course, the first separator 2 and the second separator 4 can also be fixed on the outermost end of the cell by thermal fusion.

In addition, in order to prevent lithium precipitation and the direct contact between the positive electrode sheet 1 and the negative electrode sheet 3, the length of the first diaphragm 2 and the length of the second diaphragm 4 are both 0.1-2 mm larger than the length of the negative electrode sheet 3, and the width of the first diaphragm 2 and the second diaphragm 4 are larger than the length of the negative electrode sheet 3. The width of two separators 4 is 0.1-2mm larger than the width of negative electrode sheet 3; the length of negative electrode sheet 3 is 0.1-2mm larger than the length of positive electrode sheet 1, and the width of negative electrode sheet 3 is larger than the width of positive electrode sheet 1.

Embodiment 2: the preparation method of a kind of lithium-ion cell provided by the present invention comprises the following steps: the first step, in the present embodiment, the number of sheets of positive electrode sheet 1 is one more than the sheet number of negative electrode sheet 3, and negative electrode sheet The number of sheets 3 is at least two, each positive electrode sheet 1 is provided with a positive electrode tab 11 , and each negative electrode sheet 3 is provided with a negative electrode tab 31 . As shown in FIGS. 5 and 6 , the positive electrode sheet 1 with positive electrode tabs 11 is fixed on one side of the first separator 2 by heat sealing at intervals, wherein the positive electrode sheet 1 is placed at the initial position of the first separator 2 . The negative electrode sheet 3 with the negative electrode tabs 31 left is fixed on one side of the second separator 4 by heat sealing at intervals, wherein the initial position of the second separator 4 does not place the negative electrode sheet 3 . The rest of the positive electrode sheets 1 and the negative electrode sheets 3 are provided in one-to-one correspondence. In the length direction of the first diaphragm 2, starting from the initial position, the spacing between adjacent positive electrode sheets 1 gradually increases; in the length direction of the second diaphragm 4, starting from the initial position, the adjacent negative electrode sheets 3 The distance between them gradually increases. The positive pole lugs 11 of adjacent positive pole sheets 1 are arranged alternately left and right; The positive electrode lug 11 on the positive electrode sheet 1 adjacent to the left and right of the sheet 1 is arranged on the left side, and the same is true for the negative electrode sheet 3 . Moreover, for the positive electrode sheet 1 and the negative electrode sheet 3 that are oppositely arranged, the positive electrode tabs 11 and the negative electrode tabs 31 are alternately arranged.

In the second step, as shown in Figure 7, the first diaphragm 2 provided with the positive electrode sheet 1 and the second diaphragm 4 provided with the negative electrode sheet 3 are aligned and placed, that is, except the initial position, the positive electrode sheet 1 and the negative electrode at the remaining positions The sheets 3 are aligned, and the first separator 2 and the second separator 4 are separately arranged on both sides of the positive electrode sheet 1 , that is, the second separator 4 is located between the positive electrode sheet 1 and the negative electrode sheet 3 .

The third step is to start winding from the blank end of the second separator 4, so that the positive electrode sheet 1 at the starting position of the first separator 2 is stacked on the negative electrode sheet 3 on the side of the second separator 4, and continue winding in this direction , and then fix the positive electrode sheet 1, the first separator 2, the negative electrode sheet 3 and the second separator 4 together by means of heat sealing. Mutual sliding between the diaphragm 2 and the second diaphragm 4 ensures the safety of the battery and at the same time enhances the hardness of the battery. After the winding is completed, paste the glue 5 on the end of the first diaphragm 2 and the end of the second diaphragm 4. At this time, the positive pole tab 11 is on one side of the battery core, and the negative pole tab 31 is located on the other side of the battery core. side, and then weld the positive tab 11 and the negative tab 31 to obtain a lithium-ion cell.

The schematic diagram of the structure of the lithium-ion cell obtained by the above method is shown in Figure 8, including positive electrode sheets 1 and negative electrode sheets 3 stacked on each other, the number of positive electrode sheets 1 is one more than the number of negative electrode sheets 3, and the number of positive electrode sheets 1 Both are provided with positive pole tabs 11, and the negative pole sheets 3 are all provided with negative pole tabs 31, the positive pole tabs 11 are welded and connected, the negative pole tabs 31 are welded and connected, and also include the wound first diaphragm 2 and the wound second diaphragm 4 , the positive electrode sheets 1 are all arranged on the same side of the first separator 2, and the negative electrode sheets 3 are all arranged on the same side of the second separator 4. In the direction from the innermost ring to the outermost ring of the cell, the first separator 2 and the The second separator 4 is alternately spaced between the adjacent positive electrode sheets 1 and negative electrode sheets 3 , and the positive electrode tabs 11 and the negative electrode tabs 31 are located on both sides of the front end of the cell. The front end of the cell refers to the end where the tab protrudes.

Both the uppermost and the lowermost pole pieces of the cell are positive pole pieces 1, and the positive pole piece 1 can be a positive pole piece 1 coated with a positive electrode material on both sides, or a positive pole piece 1 coated with a positive pole material on one side. Its side that is not coated with the positive electrode material is located on the outermost side. In addition, the positive tabs 11 are located on one side of the cell, and the negative tabs 31 are located on the other side of the cell.

The end of the first diaphragm 2 and the end of the second diaphragm 4 are pasted with glue 5 . Of course, the first separator 2 and the second separator 4 can also be fixed on the outermost end of the cell by thermal fusion.

In addition, in order to prevent lithium precipitation and the direct contact between the positive electrode sheet 1 and the negative electrode sheet 3, the length of the first diaphragm 2 and the length of the second diaphragm 4 are both 0.1-2 mm larger than the length of the negative electrode sheet 3, and the width of the first diaphragm 2 and the second diaphragm 4 are larger than the length of the negative electrode sheet 3. The width of two separators 4 is 0.1-2mm larger than the width of negative electrode sheet 3; the length of negative electrode sheet 3 is 0.1-2mm larger than the length of positive electrode sheet 1, and the width of negative electrode sheet 3 is larger than the width of positive electrode sheet 1.

According to the disclosure and teaching of the above specification, those skilled in the art to which the present invention pertains can also make appropriate changes and modifications to the above embodiment. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present invention should also fall within the protection scope of the claims of the present invention. In addition, although some specific terms are used in this specification, these terms are only for convenience of description and do not constitute any limitation to the present invention.

Claims (10)

1. A lithium-ion cell, comprising a positive electrode sheet and a negative electrode sheet which are stacked with each other, the number of the positive electrode sheets is at least two, the number of the negative electrode sheets is at least two, and the number of the positive electrode sheets is at least two. The difference between the number of sheets and the number of the negative electrode sheets is 1 sheet, each positive electrode sheet is provided with a positive electrode tab, and each negative electrode sheet is provided with a negative electrode tab, and the adjacent two positive electrode tabs are welded and connected, and the adjacent Two pieces of negative electrode lugs are welded and connected, and it is characterized in that: it also includes a wound first diaphragm and a wound second diaphragm, each positive electrode sheet is arranged on the same side of the first diaphragm, and each negative electrode sheet is arranged on the same side of the first diaphragm. On the same side of the second diaphragm, in the direction from the innermost circle to the outermost circle of the battery core, the first diaphragm and the second diaphragm are alternately arranged on the adjacent positive electrode sheets and between the negative electrode sheet. 2. The lithium ion battery cell according to claim 1, characterized in that: the length of the first diaphragm and the length of the second diaphragm are both 0.1-2mm larger than the length of the negative electrode sheet, and the first Both the width of the separator and the width of the second separator are 0.1-2mm larger than the width of the negative electrode sheet; The width of the positive plate is 0.1-2mm larger. 3 . The lithium-ion battery cell according to claim 1 , wherein each positive electrode sheet is fixed to the first separator by heat sealing; each negative electrode sheet is fixed to the second separator by heat sealing. 4 . 4. The lithium-ion battery cell according to claim 1, characterized in that: the ends of the first separator and the second separator are both pasted with glue. 5 . The lithium ion battery cell according to claim 1 , wherein the positive electrode tab and the negative electrode tab are located on both sides of the front end of the battery cell. 6. A preparation method for a lithium ion battery cell, comprising the following steps: In the first step, at least two positive electrode sheets with positive electrode tabs are arranged at intervals on one side of the first diaphragm, and at least two negative electrode sheets with negative electrode tabs are arranged at intervals on one side of the second diaphragm, And the number of the positive electrode sheets is different from the number of the negative electrode sheets by one sheet, the extra sheet corresponds to a blank diaphragm, and the remaining positive electrode sheets and the negative electrode sheets are set in one-to-one correspondence; In the second step, the first diaphragm provided with the positive electrode sheet and the second diaphragm provided with the negative electrode sheet are aligned and placed, and the first diaphragm and the second diaphragm are separately arranged on both sides of the positive electrode sheet or the negative electrode sheet; The third step is to start winding from one end of the blank separator, so that the positive electrode sheet and the negative electrode sheet are stacked in sequence, and then the positive electrode tab is welded and connected, and the negative electrode tab is welded and connected to obtain a lithium ion battery. 7. The preparation method of the lithium-ion cell according to claim 6, characterized in that: in the first step, each positive electrode sheet is fixed to the first separator by heat sealing, and each negative electrode sheet is fixed to the first diaphragm by heat sealing. the second diaphragm. 8. The method for preparing a lithium-ion cell according to claim 6, characterized in that: in the first step, the positive tabs of adjacent positive plates are arranged alternately left and right; the negative tabs of adjacent negative plates are alternately arranged left and right. 9 . The method for preparing a lithium ion battery cell according to claim 6 , characterized in that: after the third step of winding is completed, glue is pasted on the end of the first separator and the end of the second separator. 10 . 10. The preparation method of lithium-ion batteries according to claim 6, characterized in that: after the third step of winding is completed, each piece of positive pole tab is located on one side of the front end of the battery core, and each piece of negative pole tab is They are all located on the other side of the front end of the battery core.

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