Laminated symmetrical battery assembly structure and method thereof

Abstract

The invention provides a laminated symmetrical battery assembly structure which is arranged in an aluminum plastic film, the laminated symmetrical battery assembly structure comprises a symmetrical battery cell body, the symmetrical battery cell body comprises a first diaphragm, an isolation diaphragm and a second diaphragm which are sequentially laminated, and the first diaphragm and the second diaphragm are arranged in an aligned manner. The laminated symmetrical battery assembly structure further comprises a conductive assembly which comprises a first conductive sheet, a second conductive sheet, a first tab and a second tab, the first conducting strip is attached to the face, away from the isolation diaphragm, of the first diaphragm, the second conducting strip is attached to the face, away from the isolation diaphragm, of the second diaphragm, the first tab is welded to the first conducting strip, and the second tab is welded to the second conducting strip. And the first tab and the second tab are both positioned on the outer side of the aluminum plastic film.

Description

Technical Field

[0001] The present disclosure relates to the field of electrochemical devices, and in particular to a laminated symmetrical battery assembly structure and a method thereof. Background Art

[0002] As an important means of evaluating material impedance, symmetrical batteries provide data support for the rapid screening of material systems. At the same time, by obtaining the impedance of positive or negative electrode materials, it can provide support for analyzing the contribution ratio of positive and negative electrodes in the whole battery. In addition, symmetrical batteries can be assembled with positive and negative electrodes separately for easy distinction. Symmetrical batteries are usually stacked or button-type. The internal resistance of stacked batteries is smaller than that of button-type batteries, and the relative electrochemical analysis results are accurate.

[0003] However, the assembly of a stacked symmetrical battery is usually composed of two identical diaphragms, with an isolation membrane in the middle and electrolyte on the outside, and then packaged with an aluminum-plastic film. The pole ears are welded on the empty foil area of ​​the diaphragm. Before welding the pole ears, it is necessary to ensure that there is empty foil on the diaphragm. However, when analyzing the local electrical performance of the battery cell, there is usually no empty foil on the diaphragm. For this reason, it is necessary to wipe off the active material on the diaphragm to expose the empty foil. The positive electrode diaphragm is usually wiped with NMP to remove the active material, and the negative electrode diaphragm is usually wiped with deionized water to remove the active material. However, these substances will inevitably enter the diaphragm during the wiping process and cause irreversible damage. For example, water will destroy the SEI film on the negative electrode diaphragm, and NMP will affect the discharge specific capacity and median voltage of the positive electrode diaphragm, thereby reducing the cycle performance of the stacked symmetrical battery, which will lead to inaccurate cell impedance test results. Summary of the invention

[0004] The purpose of the present disclosure is to overcome the deficiencies in the prior art and to provide a laminated symmetrical battery assembly structure and method thereof that does not require diaphragm wiping and improves the accuracy of cell impedance test results.

[0005] The purpose of this disclosure is achieved through the following technical solutions:

[0006] A laminated symmetrical battery assembly structure is arranged in an aluminum-plastic film, the laminated symmetrical battery assembly structure comprises a symmetrical battery cell, the symmetrical battery cell comprises a first diaphragm, an isolation diaphragm and a second diaphragm stacked in sequence, the first diaphragm and the second diaphragm are arranged in alignment;

[0007] The stacked symmetrical battery assembly structure also includes a conductive component, which includes a first conductive sheet, a second conductive sheet, a first pole tab and a second pole tab. The first conductive sheet is attached to a side of the first diaphragm facing away from the isolation diaphragm, and the second conductive sheet is attached to a side of the second diaphragm facing away from the isolation diaphragm. The first pole tab is welded to the first conductive sheet, and the second pole tab is welded to the second conductive sheet. The first pole tab and the second pole tab are both located on the outside of the aluminum-plastic film.

[0008] In one embodiment, a projected area of ​​the first diaphragm overlaps with a projected area of ​​the second diaphragm.

[0009] In one embodiment, the symmetrical battery cell further includes an insulating sheet, which is disposed between the first diaphragm and the isolation diaphragm, and has a hollow window.

[0010] In one embodiment, the projected area of ​​the first conductive sheet is greater than or equal to the projected area of ​​the first membrane sheet;

[0011] The projected area of ​​the second conductive sheet is greater than or equal to the projected area of ​​the second membrane sheet.

[0012] In one embodiment, the projection area of ​​the isolation membrane is larger than the projection area of ​​the hollow window.

[0013] In one embodiment, the projected area of ​​the insulating sheet is larger than the projected area of ​​the first conductive sheet;

[0014] A projected area of ​​the insulating sheet is larger than a projected area of ​​the second conductive sheet.

[0015] In one embodiment, the first membrane includes a first foil layer, a first active material layer and a second active material layer, the first active material layer is bonded to one side of the first foil layer, and the second active material layer is bonded to the other side of the first foil layer.

[0016] In one embodiment, the second membrane includes a second foil layer, a third active material layer and a fourth active material layer, the third active material layer is bonded to one side of the second foil layer, and the fourth active material layer is bonded to the other side of the second foil layer.

[0017] In one embodiment, a first pole tab installation area is formed on the first conductive sheet, and the first pole tab is welded on the first pole tab installation area.

[0018] In one embodiment, a second pole tab installation area is formed on the second conductive sheet, and the second pole tab is welded on the second pole tab installation area.

[0019] A laminated symmetrical battery assembly method, used to assemble the laminated symmetrical battery assembly structure described in any of the above embodiments and prepare a laminated symmetrical battery;

[0020] The stacked symmetrical battery assembly method comprises the following steps:

[0021] Obtaining a first aluminum-plastic film, a second aluminum-plastic film, a first film, an isolation film, a second film, a first conductive sheet, and a second conductive sheet;

[0022] Performing a tab welding process on the first conductive sheet and the second conductive sheet, so that a first tab is formed on the first conductive sheet and a second tab is formed on the second conductive sheet;

[0023] Punching the first aluminum-plastic film and the second aluminum-plastic film so that the first aluminum-plastic film is formed with a first positioning groove and the second aluminum-plastic film is formed with a second positioning groove;

[0024] The first conductive sheet, the first diaphragm and the isolation diaphragm which have been subjected to the tab welding process are sequentially placed and stacked in the first positioning groove of the first aluminum-plastic diaphragm to obtain a first assembly;

[0025] The second conductive sheet and the second diaphragm after the tab welding process are sequentially placed and stacked in the second positioning groove of the second aluminum-plastic diaphragm to obtain a second assembly;

[0026] The first assembly and the second assembly are subjected to liquid injection packaging treatment to obtain a laminated symmetrical battery.

[0027] Compared with the prior art, the present invention has at least the following advantages:

[0028] By providing a first conductive sheet and a second conductive sheet, and by arranging the first pole ear on the first conductive sheet and the second pole ear on the second conductive sheet, it is unnecessary to wipe the first diaphragm and the second diaphragm, thereby avoiding the situation where NMP and water cause irreversible damage to the first diaphragm and the second diaphragm. Furthermore, by aligning the first diaphragm and the second diaphragm, the electrochemical reaction areas of the first diaphragm and the second diaphragm overlap when the cell impedance test is performed after the laminated symmetrical battery assembly structure is encapsulated in an aluminum-plastic film, thereby effectively improving the accuracy of the cell impedance test result of the laminated symmetrical battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 This is a schematic diagram of the structure of a symmetrical stacked battery assembly structure after being encapsulated in an aluminum-plastic film in an embodiment;

[0031] Figure 2 for Figure 1 The schematic diagram of the structure of the stacked symmetrical battery assembly structure after explosion is shown;

[0032] Figure 3 for Figure 1 A structural cross-sectional view of a symmetrical battery assembly structure shown;

[0033] Figure 4 for Figure 2 A partial structural diagram of a symmetrical battery assembly structure shown;

[0034] Figure 5 for Figure 2 A partial structural diagram of a symmetrical battery assembly structure shown;

[0035] Figure 6 is a flow chart of a method for assembling a laminated symmetrical battery in one embodiment;

[0036] Figure 7 The impedance test result data distribution diagram for verification example 1;

[0037] Figure 8 The impedance test result data distribution diagram of verification example 2;

[0038] Fig. 9 The impedance test result data distribution diagram of verification example 3;

[0039] Fig.10 The impedance test result data distribution diagram of Example 1;

[0040] Fig.11 The impedance test result data distribution diagram of Example 2;

[0041] Fig.12 This is a real picture of the stacked symmetrical battery assembly structure after being encapsulated in aluminum-plastic film. DETAILED DESCRIPTION

[0042] In order to facilitate the understanding of the present disclosure, the present disclosure will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present disclosure are given in the drawings. However, the present disclosure can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present disclosure more thoroughly and comprehensively understood.

[0043] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present disclosure. The terms used herein in the specification of the present disclosure are only for the purpose of describing specific embodiments and are not intended to limit the present disclosure. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0045] The present disclosure provides a laminated symmetrical battery assembly structure arranged in an aluminum-plastic film, the laminated symmetrical battery assembly structure includes a symmetrical battery body, the symmetrical battery body includes a first diaphragm, an isolation diaphragm and a second diaphragm stacked in sequence, and the first diaphragm is aligned with the second diaphragm. The laminated symmetrical battery assembly structure also includes a conductive component, the conductive component includes a first conductive sheet, a second conductive sheet, a first pole tab and a second pole tab, the first conductive sheet is attached to a side of the first diaphragm away from the isolation diaphragm, the second conductive sheet is attached to a side of the second diaphragm away from the isolation diaphragm, the first pole tab is welded on the first conductive sheet, the second pole tab is welded on the second conductive sheet, and the first pole tab and the second pole tab are both located outside the aluminum-plastic film.

[0046] See also Figures 1 to 3 In order to better understand the laminated symmetrical battery assembly structure 10 disclosed in the present invention, the laminated symmetrical battery assembly structure 10 is further explained below:

[0047] A laminated symmetrical battery assembly structure 10 of one embodiment is arranged in an aluminum-plastic film 20, and the laminated symmetrical battery assembly structure 10 includes a symmetrical battery cell 100, and the symmetrical battery cell 100 includes a first diaphragm 110, an isolation diaphragm 120 and a second diaphragm 130 stacked in sequence, and the first diaphragm 110 and the second diaphragm 130 are aligned. The laminated symmetrical battery assembly structure 10 also includes a conductive component 200, which includes a first conductive sheet 210, a second conductive sheet 220, a first pole ear 230 and a second pole ear 240. The first conductive sheet 210 is bonded to a side of the first diaphragm 110 that is away from the isolation diaphragm 120, and the second conductive sheet 220 is bonded to a side of the second diaphragm 130 that is away from the isolation diaphragm 120. The first pole ear 230 is welded to the first conductive sheet 210, and the second pole ear 240 is welded to the second conductive sheet 220. The first pole ear 230 and the second pole ear 240 are both located on the outside of the aluminum-plastic film 20.

[0048] In this embodiment, by providing a first conductive sheet 210 and a second conductive sheet 220, and by providing a first pole ear 230 on the first conductive sheet 210, and a second pole ear 240 on the second conductive sheet 220, there is no need to wipe the first diaphragm 110 and the second diaphragm 130, thereby avoiding the situation where NMP and water cause irreversible damage to the first diaphragm 110 and the second diaphragm 130. Furthermore, by aligning the first diaphragm 110 and the second diaphragm 130, the electrochemical reaction areas of the first diaphragm 110 and the second diaphragm 130 overlap when the cell impedance test is performed after the laminated symmetrical battery assembly structure 10 is encapsulated in the aluminum-plastic film 20, thereby effectively improving the accuracy of the cell impedance test result of the laminated symmetrical battery.

[0049] It should be noted that the first diaphragm 110 and the second diaphragm 130 are both positive electrode diaphragms or negative electrode diaphragms, and can be any area in the cell diaphragm to analyze abnormal areas of the cell.

[0050] It should be noted that the first conductive sheet 210 and the second conductive sheet 220 are metal copper sheets or metal aluminum sheets.

[0051] like Figure 2 and Figure 3 As shown, in one embodiment, the projection area of ​​the first diaphragm 110 overlaps with the projection area of ​​the second diaphragm 130. It can be understood that the projection area of ​​the first diaphragm 110 is consistent with the projection area of ​​the second diaphragm 130, that is, the size of the first diaphragm 110 and the second diaphragm 130 is consistent, and the first diaphragm 110 and the second diaphragm 130 are aligned and arranged so that the electrochemical reaction areas of the first diaphragm 110 and the second diaphragm 130 overlap, so that the accuracy of the impedance test results of the first diaphragm 110 and the second diaphragm 130 can be improved, thereby improving the accuracy of the impedance test results of the battery cell of the laminated symmetrical battery.

[0052] like Figure 2 and Figure 3As shown, in one embodiment, the symmetrical battery cell 100 further includes an insulating sheet 140 , and the insulating sheet 140 is disposed between the first diaphragm 110 and the isolation diaphragm 120 . The insulating sheet 140 is provided with a hollow window 1402 . It should be noted that, since the laminated symmetrical battery is assembled in a stacking manner, the first diaphragm 110 and the second diaphragm 130 are prone to displacement when the laminated battery assembly structure is packaged in the aluminum-plastic film 20, resulting in a decrease in the accuracy of the cell impedance test results. Therefore, in this embodiment, the insulating sheet 140 is arranged between the first diaphragm 110 and the isolation diaphragm 120, and a hollow window 1402 is opened on the insulating sheet 140, so that ions can only pass through the hollow window 1402, that is, the area of ​​the hollow window 1402 is controlled to control the effective reaction area corresponding to the first diaphragm 110 and the second diaphragm 130, ensuring that the effective reaction areas of the first diaphragm 110 and the second diaphragm 130 overlap, thereby improving the accuracy of the cell impedance test results of the laminated symmetrical battery.

[0053] like Figure 2 and Figure 3 As shown, in one embodiment, the projected area of ​​the first conductive sheet 210 is greater than or equal to the projected area of ​​the first diaphragm 110. The projected area of ​​the second conductive sheet 220 is greater than or equal to the projected area of ​​the second diaphragm 130. It can be understood that the projected area of ​​the first conductive sheet 210 is greater than or equal to the projected area of ​​the first diaphragm 110, so that the conductive surface can be covered on the first diaphragm 110. Similarly, the projected area of ​​the second conductive sheet 220 is greater than or equal to the projected area of ​​the second diaphragm 130, so that the conductive surface can be covered on the second diaphragm 130. Further, by connecting the first conductive sheet 210 and the second conductive sheet 220 to external electricity, an electrochemical reaction occurs on the first diaphragm 110 and the second diaphragm 130, so that the impedance test of the first diaphragm 110 and the second diaphragm 130 can be performed.

[0054] like Figure 2 and Figure 3 As shown, in one embodiment, the projection area of ​​the isolation diaphragm 120 is larger than the projection area of ​​the hollow window 1402. It can be understood that the projection area of ​​the isolation diaphragm 120 is larger than the projection area of ​​the hollow window 1402, which can avoid the short circuit caused by the contact between the first diaphragm 110 and the second diaphragm 130, thereby improving the safety of the laminated symmetrical battery assembly structure 10.

[0055] like Figure 2 and Figure 3As shown, in one embodiment, the projected area of ​​the insulating sheet 140 is larger than the projected area of ​​the first conductive sheet 210. The projected area of ​​the insulating sheet 140 is larger than the projected area of ​​the second conductive sheet 220. It can be understood that the projected area of ​​the insulating sheet 140 is larger than the projected area of ​​the first conductive sheet 210 and the projected area of ​​the second conductive sheet 220, respectively. Since the projected area of ​​the first conductive sheet 210 is larger than or equal to the projected area of ​​the first diaphragm 110, and the projected area of ​​the second conductive sheet 220 is larger than or equal to the projected area of ​​the second diaphragm 130, the projected area of ​​the insulating sheet 140 is larger than the projected areas of the first conductive sheet 210, the first diaphragm 110, the second conductive sheet 220 and the second diaphragm 130, respectively, thereby avoiding the short circuit caused by the contact between the first diaphragm 110 and the second diaphragm 130, and further improving the safety of the laminated symmetrical battery assembly structure 10.

[0056] like Figure 3 As shown, in one embodiment, the first diaphragm 110 includes a first foil layer 1110, a first active material layer 1120 and a second active material layer 1130, the first active material layer 1120 is bonded to one side of the first foil layer 1110, and the second active material layer 1130 is bonded to the other side of the first foil layer 1110. It can be understood that since the first diaphragm 110 is disassembled from any area of ​​the positive electrode sheet or the negative electrode sheet of the battery cell, both sides of the first foil layer 1110 are coated with the first active material layer 1120 and the second active material layer 1130 regardless of the positive electrode or the negative electrode.

[0057] like Figure 3 As shown, in one embodiment, the second diaphragm 130 includes a second foil layer 1310, a third active material layer 1320 and a fourth active material layer 1330, the third active material layer 1320 is bonded to one side of the second foil layer 1310, and the fourth active material layer 1330 is bonded to the other side of the second foil layer 1310. It can be understood that since the second diaphragm 130 is disassembled from any area of ​​the positive electrode sheet or the negative electrode sheet of the battery cell, the third active material layer 1320 and the fourth active material layer 1330 are coated on both sides of the second foil layer 1310 regardless of the positive electrode or the negative electrode.

[0058] like Figure 1 , Figure 2 and Figure 4As shown, in one embodiment, a first pole lug installation area 2102 is provided on the first conductive sheet 210, and the first pole lug 230 is welded on the first pole lug installation area 2102. It should be noted that by leaving the first pole lug installation area 2102 on the first conductive sheet 210, it is convenient to weld the first pole lug 230 on the first conductive sheet 210, and then the first diaphragm 110 is electrically connected to the external circuit through the first pole lug 230 and the first conductive sheet 210, without the need to wipe the first diaphragm 110 additionally, thereby improving the accuracy of the cell impedance test results of the laminated symmetrical battery.

[0059] like Figure 1 , Figure 2 and Figure 5 As shown, in one embodiment, a second pole lug installation area 2202 is provided on the second conductive sheet 220, and the second pole lug 240 is welded on the second pole lug installation area 2202. It should be noted that by leaving the second pole lug installation area 2202 on the second conductive sheet 220, it is convenient to weld the second pole lug 240 on the second conductive sheet 220, and then the second diaphragm 130 is electrically connected to the external circuit through the second pole lug 240 and the second conductive sheet 220, without the need to wipe the second diaphragm 130 additionally, thereby improving the accuracy of the cell impedance test result.

[0060] The present disclosure also provides a laminated symmetrical battery assembly method for assembling the laminated symmetrical battery assembly structure described in any of the above embodiments and preparing a laminated symmetrical battery;

[0061] The stacked symmetrical battery assembly method comprises the following steps: obtaining a first aluminum-plastic film, a second aluminum-plastic film, a first film, an isolation film, a second film, a first conductive sheet and a second conductive sheet; performing a tab welding process on the first conductive sheet and the second conductive sheet so that a first tab is formed on the first conductive sheet and a second tab is formed on the second conductive sheet; performing a stamping process on the first aluminum-plastic film and the second aluminum-plastic film so that a first positioning groove is formed on the first aluminum-plastic film and a second positioning groove is formed on the second aluminum-plastic film; placing the first conductive sheet, the first film and the isolation film after the tab welding process in the first positioning groove of the first aluminum-plastic film in sequence and stacking them to obtain a first assembly; placing the second conductive sheet and the second film after the tab welding process in the second positioning groove of the second aluminum-plastic film in sequence and stacking them to obtain a second assembly; performing a liquid injection packaging process on the first assembly and the second assembly to obtain a stacked symmetrical battery.

[0062] See also Figure 6 In order to better understand the symmetrical stacking battery assembly method disclosed in the present invention, the symmetrical stacking battery assembly method is further explained below:

[0063] The symmetrical stacked battery assembly method of one embodiment comprises the following steps:

[0064] S100, obtaining a first aluminum-plastic film, a second aluminum-plastic film, a first film, an isolation film, a second film, a first conductive sheet, and a second conductive sheet.

[0065] In this embodiment, since the projection areas of the first diaphragm and the second diaphragm overlap, the projection area of ​​the first conductive sheet is greater than or equal to the projection area of ​​the first diaphragm, the projection area of ​​the second conductive sheet is greater than or equal to the projection area of ​​the second diaphragm, the projection area of ​​the isolation diaphragm is respectively greater than the projection area of ​​the first conductive sheet and the projection area of ​​the second conductive sheet, and the first conductive sheet and the second conductive sheet are ready-made products, the first diaphragm and the second diaphragm are cut on the battery cell of the battery to be tested according to the size of the first conductive sheet and the second conductive sheet, and the isolation diaphragm is made according to the size of the first conductive sheet and the second conductive sheet, so that the conductive surface can cover the diaphragm, and at the same time avoid the first diaphragm and the second diaphragm directly contacting each other to cause a short circuit, thereby improving the accuracy of the cell impedance test results of the laminated symmetrical battery and the safety of the laminated symmetrical battery. Furthermore, the first aluminum-plastic diaphragm and the second aluminum-plastic diaphragm are used for packaging and rapid positioning, thereby improving the assembly efficiency of the laminated symmetrical battery.

[0066] S200 , performing a tab welding process on the first conductive sheet and the second conductive sheet, so that a first tab is formed on the first conductive sheet and a second tab is formed on the second conductive sheet.

[0067] In this embodiment, a first pole lug installation area is provided on the first conductive sheet, so that the first pole lug can be welded on the first conductive sheet. Similarly, a second pole lug installation area is provided on the second conductive sheet, so that the second pole lug can be welded on the second conductive sheet. There is no need to wipe the first membrane sheet and the second membrane sheet to leave blanks. The first pole lug on the first conductive sheet and the second pole lug on the second conductive sheet are used to connect the external circuit to perform a cell impedance test on the laminated symmetrical battery. Furthermore, by providing the first pole lug installation area and the second pole lug installation area, the convenience of pole lug welding is improved, and the pole lugs are quickly positioned and welded, thereby effectively improving the assembly efficiency of the laminated symmetrical battery.

[0068] S300, punching the first aluminum-plastic film and the second aluminum-plastic film to form a first positioning groove on the first aluminum-plastic film and a second positioning groove on the second aluminum-plastic film.

[0069] In this embodiment, the first positioning groove and the second positioning groove are respectively formed by punching in the first aluminum-plastic film and the second aluminum-plastic film, and the first positioning groove and the second positioning groove are both inverted trapezoidal grooves, and the bottom area of ​​the first positioning groove overlaps with the projected area of ​​the first conductive sheet, and the bottom area of ​​the second positioning groove overlaps with the projected area of ​​the second conductive sheet, so that the first conductive sheet and the second conductive sheet can be quickly positioned and installed on the first aluminum-plastic film and the second aluminum-plastic film respectively. Further, the top area of ​​the first positioning groove, the top area of ​​the second positioning groove and the projected area of ​​the isolation diaphragm overlap, so that the isolation diaphragm can be quickly installed and positioned, and the first diaphragm and the second diaphragm can be prevented from directly contacting each other and causing a short circuit.

[0070] Furthermore, in one embodiment, the specific steps of stamping the first aluminum-plastic film and the second aluminum-plastic film are as follows:

[0071] The first aluminum-plastic film and the second aluminum-plastic film are punched by a punching machine.

[0072] It can be understood that the first aluminum-plastic film and the second aluminum-plastic film are respectively extruded by a die of a punching machine, so that a first positioning groove is formed on the first aluminum-plastic film and a second positioning groove is formed on the second aluminum-plastic film. The die of the punching machine is an inverted trapezoidal die, the bottom area of ​​the inverted trapezoidal die overlaps with the projected area of ​​the first conductive sheet welded with the first pole ear, and the top area of ​​the inverted trapezoidal die overlaps with the projected area of ​​the isolation diaphragm, so that the first conductive sheet and the second conductive sheet can be quickly positioned and installed on the first aluminum-plastic diaphragm and the second aluminum-plastic diaphragm, respectively. Furthermore, since the projected area of ​​the first conductive sheet is greater than or equal to the projected area of ​​the first diaphragm, the first diaphragm can be quickly positioned and installed in the first positioning groove, while the conductive surface of the first conductive sheet always covers the first diaphragm, and the isolation diaphragm always covers the first diaphragm; similarly, the projected area of ​​the second conductive sheet is greater than or equal to the projected area of ​​the second diaphragm, and the second diaphragm can be quickly positioned and installed in the second positioning groove, while the conductive surface of the second conductive sheet always covers the second diaphragm, and the isolation diaphragm always covers the second diaphragm, so that the accuracy of the cell impedance test results of the stacked symmetrical battery can be improved while improving the safety of the stacked symmetrical battery.

[0073] Furthermore, the pressure value of the punching machine is 0.1-0.2 MPa. It is understandable that the punching force is between 0.1 and 0.2 MPa, which can ensure that the first aluminum-plastic film and the second aluminum-plastic film are respectively formed with the first positioning groove and the second positioning groove, thereby reducing the difficulty of assembling the laminated symmetrical battery and improving the accuracy of the cell impedance test result of the laminated symmetrical battery.

[0074] S400, placing and stacking the first conductive sheet, the first diaphragm and the isolation diaphragm after the tab welding process in the first positioning groove of the first aluminum-plastic diaphragm in sequence to obtain a first assembly.

[0075] In this embodiment, since the first positioning groove is an inverted trapezoidal groove, and the groove bottom area of ​​the first positioning groove overlaps with the projected area of ​​the first conductive sheet welded with the first pole ear, the first conductive sheet can be reliably and quickly installed in the first positioning groove, and the projected area of ​​the first conductive sheet is greater than or equal to the projected area of ​​the first diaphragm, so that the first diaphragm can be quickly installed in the first positioning groove while the conductive surface of the first conductive sheet always covers the first diaphragm, and then the isolation diaphragm is placed in the first positioning groove, and the projected area of ​​the isolation diaphragm overlaps with the groove top area of ​​the first positioning groove, so that the isolation diaphragm can be quickly positioned and installed in the first positioning groove while the isolation diaphragm always covers the first diaphragm, thereby improving the assembly efficiency of the stacked symmetrical battery and the safety of the stacked symmetrical battery.

[0076] S500, placing and stacking the second conductive sheet and the second diaphragm after the tab welding process in the second positioning groove of the second aluminum-plastic diaphragm in sequence to obtain a second assembly.

[0077] In this embodiment, since the second positioning groove is an inverted trapezoidal groove, and the bottom area of ​​the second positioning groove overlaps with the projected area of ​​the second conductive sheet welded with the second pole ear, the second conductive sheet can be reliably and quickly installed in the second positioning groove, and the projected area of ​​the second conductive sheet is greater than or equal to the projected area of ​​the second diaphragm, so that the second diaphragm can be quickly installed in the second positioning groove while the conductive surface of the second conductive sheet always covers the second diaphragm, and then when the first assembly and the second assembly are packaged, the other end of the isolation diaphragm will be placed in the second positioning groove, and the projected area of ​​the isolation diaphragm overlaps with the top area of ​​the second positioning groove, so that the first assembly and the second assembly can be quickly positioned and assembled, and the isolation diaphragm always covers the second diaphragm, thereby improving the assembly efficiency of the stacked symmetrical battery and the safety of the stacked symmetrical battery.

[0078] S600, performing liquid injection packaging processing on the first assembly and the second assembly to obtain a laminated symmetrical battery.

[0079] In this embodiment, after aligning one side of the first assembly with the opening with the one side of the second assembly with the opening, the isolation diaphragm is placed in the second positioning groove, so that the first assembly and the second assembly can be quickly aligned and the side edges can be sealed, and then the unsealed area on the top surface of the battery stacked by the laminate is injected with liquid, and the top surface of the laminated symmetrical battery is sealed after the injection, and the first pole ear and the second pole ear are located on the outside of the aluminum-plastic film to form a laminated symmetrical battery. The laminated symmetrical battery is subjected to EIS test, i.e., cell impedance test, by an electrochemical workstation. Since the first diaphragm and the second diaphragm are symmetrically arranged, i.e., the effective area of ​​the electrochemical reaction overlaps, it is possible to determine whether the analysis area of ​​the battery cell to be tested is abnormal based on whether the data of the first diaphragm and the second diaphragm are consistent, so that the cell impedance test result of the laminated symmetrical battery is more accurate.

[0080] In one embodiment, step S100 specifically includes:

[0081] First, a first aluminum-plastic film, a second aluminum-plastic film, a first conductive sheet, a second conductive sheet and an isolation film are obtained;

[0082] Then, the cell membrane of the battery to be tested is cut according to the sizes of the first conductive sheet and the second conductive sheet to obtain the first membrane and the second membrane.

[0083] It should be noted that the aluminum-plastic film is a ready-made product. The first aluminum-plastic film sheet and the second aluminum-plastic film sheet are cut from the aluminum-plastic film. The first conductive sheet and the second conductive sheet are also ready-made products, specifically metal copper sheets or metal aluminum sheets, to achieve the conductive effect. The isolation diaphragm is cut from the diaphragm tape to ensure that the projected area of ​​the isolation diaphragm is larger than the area of ​​the first conductive sheet and the second conductive sheet, so as to avoid the first diaphragm and the second diaphragm directly contacting each other and causing a short circuit. Furthermore, the cell diaphragm of the battery to be tested is cut by a cutting machine, so that the first diaphragm and the second diaphragm of the same area can be accurately cut. Furthermore, the cutting pressure value of the cutting machine is 0.1~0.2MPa, which ensures that the cell diaphragm can be cut. Further, in this embodiment, the projection areas of the first conductive sheet and the second conductive sheet overlap, that is, the projection areas of the first diaphragm and the second diaphragm overlap, but because they are assembled by stacking, the first diaphragm and the first conductive sheet are prone to displacement; similarly, the second diaphragm and the second conductive sheet are also prone to displacement, for this reason, the projection area of ​​the first conductive sheet is larger than the first diaphragm, even if there is a displacement, the first conductive sheet can always cover the first diaphragm; similarly, the projection area of ​​the second conductive sheet is larger than the second diaphragm, even if there is a displacement, the second conductive sheet can always cover the second diaphragm, to ensure that the conductive surface always covers the diaphragm, to ensure that the electron transmission area on the first diaphragm and the second diaphragm overlap, thereby improving the accuracy of the cell impedance test results of the stacked symmetrical battery. Further, the length difference between the first conductive sheet and the first diaphragm is 5mm~10mm, and the width difference between the first conductive sheet and the first diaphragm is 5mm~10mm. Similarly, the length difference between the second conductive sheet and the second membrane is 5mm to 10mm, and the width difference between the second conductive sheet and the second membrane is 5mm to 10mm. Even if there is a deviation, the conductive surface is always covered on the membrane, ensuring that the electron transmission area on the first membrane and the second membrane overlaps, thereby improving the accuracy of the cell impedance test results of the stacked symmetrical battery.

[0084] Furthermore, since the first diaphragm and the second diaphragm are obtained by cutting the diaphragms in the battery cell with a cutting machine, and the projection areas of the first conductive sheet and the second conductive sheet overlap, the working parameters of the cutting machine are the actual length value of the first conductive sheet minus 5mm to 10mm, and the actual width value of the actual length value of the first conductive sheet minus 5mm to 10mm. Therefore, in this embodiment, the length and width of the first conductive sheet are detected to simultaneously obtain the working parameters of the cutting machine, so as to ensure that the first diaphragm is covered by the first conductive sheet, the second diaphragm is covered by the second conductive sheet, and the electron transmission areas on the first diaphragm and the second diaphragm overlap, thereby improving the accuracy of the cell impedance test results of the laminated symmetrical battery.

[0085] Furthermore, the length and width of the first conductive sheet are detected to simultaneously obtain the working parameters of the cutter, including: firstly, a database of length values ​​of multiple first conductive sheets, width values ​​of multiple first conductive sheets and working parameters of multiple cutters is established in one-to-one correspondence; then, the length value and width value of the first conductive sheet to be detected are detected to obtain the actual length value and actual width value of the first conductive sheet; then, the target working parameters of the cutter are retrieved according to the actual length value and actual width value of the first conductive sheet, thereby improving the applicability of the cutter. Furthermore, the cell membrane of the battery to be tested is cut according to the target working parameters of the cutter to ensure that the first membrane is always covered by the first conductive sheet, and the second membrane is always covered by the second conductive sheet, so that the electron transmission areas on the first membrane and the second membrane always overlap, thereby further improving the accuracy of the cell impedance test results of the laminated symmetrical battery.

[0086] Further, the step of detecting the length and width of the first conductive sheet is specifically as follows: measuring the length and width of the first conductive sheet by a rangefinder to obtain the actual length value and the actual width value of the first conductive sheet. The measurement by the rangefinder can ensure the accuracy of the measurement, so as to ensure that the first membrane is always covered by the first conductive sheet, and the second membrane is always covered by the second conductive sheet, so that the electron transmission area on the first membrane and the second membrane always overlaps, thereby improving the accuracy of the cell impedance test results of the laminated symmetrical battery. Further, the length and width of multiple sites of the first conductive sheet are measured by a rangefinder to obtain multiple actual length values ​​and multiple actual width values ​​of the first conductive sheet, and then the multiple actual length values ​​and the multiple actual width values ​​are averaged to obtain the actual length average value and the actual width average value of the first conductive sheet, thereby improving the data detection accuracy of the length and width of the first conductive sheet, thereby ensuring that the first membrane is always covered by the first conductive sheet, and the second membrane is always covered by the second conductive sheet, so that the electron transmission area on the first membrane and the second membrane always overlaps, further improving the accuracy of the cell impedance test results of the laminated symmetrical battery.

[0087] It can be understood that since the first positioning groove and the second positioning groove are inverted trapezoidal grooves, after the first assembly and the second assembly are encapsulated and filled with liquid, the first diaphragm and the second diaphragm are not well limited and fixed when they are respectively positioned and installed in the first positioning groove and the second positioning groove, and the first diaphragm and the second diaphragm are easily offset, that is, the first diaphragm and the second diaphragm cannot be aligned, resulting in the electrochemical reaction effective area of ​​the first diaphragm and the second diaphragm not overlapping, making the cell impedance test result of the laminated symmetrical battery deviated and inaccurate. Therefore, in one embodiment, the shape of the first diaphragm is any one of polygonal, circular, star-shaped or irregular, and the shape of the second diaphragm is any one of rectangular, circular, star-shaped or irregular. By setting any one of polygonal, circular, star-shaped or irregular shapes, the first diaphragm can be confined in the first positioning groove when installed in the first positioning groove. Similarly, the second diaphragm can be confined in the second positioning groove when installed in the second positioning groove, and the projection areas of the first diaphragm and the second diaphragm overlap, so that the electrochemical effective areas of the first diaphragm and the second diaphragm can overlap, thereby improving the accuracy of the cell impedance test results of the stacked symmetrical battery.

[0088] Furthermore, in another embodiment, step S400 is: placing and stacking the first conductive sheet, the first diaphragm, the insulating sheet and the isolation diaphragm after the tab welding process in the first positioning groove of the first aluminum-plastic diaphragm in sequence to obtain a first assembly.

[0089] It should be noted that the projection area of ​​the isolation diaphragm is larger than the projection area of ​​the hollow window of the insulating sheet. The hollow window of the insulating sheet is set so that the effective electrochemical reaction area of ​​the first diaphragm is the projection area of ​​the hollow window. Regardless of whether the first diaphragm and the second diaphragm are offset, the effective electrochemical reaction area of ​​the first diaphragm always overlaps and is consistent with the effective electrochemical reaction area of ​​the second diaphragm. This can improve the accuracy of the cell impedance test results of the stacked symmetrical battery, while simplifying the difficulty of assembling the stacked symmetrical battery and improving the test pass rate of the stacked battery.

[0090] Furthermore, the shape of the hollow window of the insulating sheet is any one of a circular, polygonal or irregular shape. Specifically, by die-cutting the central area of ​​the insulating sheet and cutting according to the shape of the mold, it is ensured that the first diaphragm and the second diaphragm have consistent electrochemical effective reaction areas, so that the accuracy of the impedance test results of the stacked symmetrical battery is effectively improved.

[0091] In one embodiment, the insulating sheet is any one of a PP film, a PE film, a HDPE film and a PET film. It is understood that the above-mentioned film can isolate the electrolyte and ions, allowing the electrolyte and ions to shuttle through the hollow window, ensuring that the electrochemical effective area of ​​the first film and the second film is consistent.

[0092] In one embodiment, the isolation diaphragm is any one of a PP / PE wet-process diaphragm, a PP / PE dry-process single-drawn diaphragm, and a PP / PE dry-process double-drawn diaphragm. It is understood that the above isolation diaphragm can prevent the first diaphragm from directly contacting the second diaphragm, while allowing ions to pass through the isolation diaphragm to ensure that the electrochemical reaction in the laminated symmetrical battery proceeds normally.

[0093] In order to verify the influence of the laminated symmetrical battery assembly method disclosed in the present invention on the consistency of the cell impedance test results of the battery to be tested.

[0094] Verification Example 1:

[0095] Two 34145 battery cells without abnormalities were used. After the battery cells were charged to 50% SOC, the negative electrode sheets of the battery cells were cut off. A traditional stacking method was used, i.e. a first diaphragm, an isolation diaphragm and a second diaphragm. The first diaphragm and the second diaphragm were wiped and the pole ears were welded to obtain a symmetrical battery body. The symmetrical battery body was placed in an aluminum-plastic film for liquid injection packaging to obtain a stacked symmetrical battery.

[0096] Verification Example 2:

[0097] Two 34145 battery cells without abnormalities are used, and the negative electrode sheets of the battery cells are cut after the battery cells are charged to 50% SOC, and the negative electrodes of the two battery cells are cut off according to the size of the first conductive sheet; a first diaphragm and a second diaphragm are obtained; the first conductive sheet and the second conductive sheet are respectively subjected to pole ear welding processing; the first aluminum-plastic diaphragm and the second aluminum-plastic diaphragm are subjected to stamping processing; the first conductive sheet, the first diaphragm, the insulating sheet and the isolation diaphragm after the pole ear welding processing are sequentially placed and stacked in the first positioning groove of the first aluminum-plastic diaphragm to obtain a first assembly; the second conductive sheet and the second diaphragm after the pole ear welding processing are sequentially placed and stacked in the second positioning groove of the second aluminum-plastic diaphragm to obtain a second assembly; the first assembly and the second assembly are subjected to liquid injection packaging processing to obtain a laminated symmetrical battery.

[0098] Verification Example 3:

[0099] Two 34145 battery cells without abnormalities are used, and the negative electrode sheets of the battery cells are cut after the battery cells are charged to 50% SOC, and the negative electrodes of the two battery cells are cut off according to the size of the first conductive sheet; a first diaphragm and a second diaphragm are obtained; the first conductive sheet and the second conductive sheet are respectively subjected to pole ear welding processing; the first aluminum-plastic diaphragm and the second aluminum-plastic diaphragm are subjected to stamping processing; the first conductive sheet, the first diaphragm and the isolation diaphragm after the pole ear welding processing are sequentially placed and stacked in the first positioning groove of the first aluminum-plastic diaphragm to obtain a first assembly; the second conductive sheet and the second diaphragm after the pole ear welding processing are sequentially placed and stacked in the second positioning groove of the second aluminum-plastic diaphragm to obtain a second assembly; the first assembly and the second assembly are subjected to liquid injection packaging processing to obtain a laminated symmetrical battery.

[0100] The EIS test was performed on the laminated symmetrical cells of Verification Examples 1, 2 and 3, with a scanning frequency of 0.1 to 10000 Hz and an amplitude of 10 mv / s. The test results are as follows: Figures 7 to 9 .

[0101] Depend on Figure 7 It can be seen that the measurement data consistency of Verification Example 1 is poor, and since the effective areas of the first diaphragm and the second diaphragm are larger and the impedance values ​​are smaller, this indicates that the first diaphragm and the second diaphragm are difficult to align after assembly, resulting in poor consistency in data measurement.

[0102] Depend on Figure 8 It can be seen that the measurement data of Verification Example 2 has good consistency, which shows that the use of the laminated symmetrical battery assembly structure and assembly method disclosed in the present invention can improve the accuracy of the impedance test results of the battery cell.

[0103] Depend on Fig. 9 It can be seen that Verification Example 3 lacks an insulating sheet and a hollow window, which makes the effective areas of the first diaphragm and the second diaphragm inconsistent, resulting in the measurement data consistency of Verification Example 3 being relatively general. This shows that the addition of an insulating sheet can significantly improve the accuracy of the cell impedance test results of the stacked symmetrical battery.

[0104] Examples are listed below, but it should be noted that the following examples do not exhaust all possible situations, and the materials used in the following examples can be obtained from commercial channels unless otherwise specified.

[0105] Example 1

[0106] After the 34145 battery cell to be tested is charged to 50% SOC, the negative electrodes of the two battery cells are cut off according to the size of the first conductive sheet; the first diaphragm is obtained; the first conductive sheet and the second conductive sheet are respectively subjected to tab welding processing; the first aluminum-plastic diaphragm and the second aluminum-plastic diaphragm are stamped; the first conductive sheet, the first diaphragm, the insulating sheet and the isolation diaphragm after the tab welding processing are sequentially placed and stacked in the first positioning groove of the first aluminum-plastic diaphragm to obtain a first assembly; the second conductive sheet and the second diaphragm after the tab welding processing are sequentially placed and stacked in the second positioning groove of the second aluminum-plastic diaphragm to obtain a second assembly; the first assembly and the second assembly are subjected to liquid injection packaging processing to obtain a laminated symmetrical battery.

[0107] Example 2

[0108] After the 34145 battery cell to be tested is charged to 100% SOC, the negative electrodes of the two battery cells are cut off according to the size of the first conductive sheet; the first diaphragm is obtained; the first conductive sheet and the second conductive sheet are respectively subjected to pole ear welding processing; the first aluminum-plastic diaphragm and the second aluminum-plastic diaphragm are stamped; the first conductive sheet, the first diaphragm, the insulating sheet and the isolation diaphragm after the pole ear welding processing are sequentially placed and stacked in the first positioning groove of the first aluminum-plastic diaphragm to obtain a first assembly; the second conductive sheet and the second diaphragm after the pole ear welding processing are sequentially placed and stacked in the second positioning groove of the second aluminum-plastic diaphragm to obtain a second assembly; the first assembly and the second assembly are subjected to liquid injection packaging processing to obtain a laminated symmetrical battery.

[0109] The laminated symmetrical cells of Example 1 and Example 2 were subjected to EIS test with a scanning frequency of 0.1 to 10000 Hz and an amplitude of 10 mv / s. The test results are as follows: Fig.10 and Fig.11 .

[0110] Depend on Fig.10 It can be seen that the measurement data of Example 1 has good consistency, which means that the two 34145 cells to be tested have good consistency and no abnormalities.

[0111] Fig.11 It can be seen that the measurement data of Example 2 are inconsistent and have large deviations, which indicates that there are abnormalities in the two 34145 battery cells to be tested, so as to facilitate the subsequent electrochemical composition analysis and detection of the abnormal areas, which is helpful for the research and development of battery cells.

[0112] It can be seen that the use of the laminated symmetrical battery assembly structure and assembly method disclosed in the present invention can improve the accuracy of the impedance test results of the battery cell, and the assembly difficulty is relatively low, and it is particularly suitable for the battery cell research and development process.

[0113] Compared with the prior art, the present invention has at least the following advantages:

[0114] By providing a first conductive sheet and a second conductive sheet, and by arranging the first pole ear on the first conductive sheet and the second pole ear on the second conductive sheet, it is unnecessary to wipe the first diaphragm and the second diaphragm, thereby avoiding the situation where NMP and water cause irreversible damage to the first diaphragm and the second diaphragm. Furthermore, by aligning the first diaphragm and the second diaphragm, the electrochemical reaction areas of the first diaphragm and the second diaphragm are consistent when the cell impedance test is performed after the stacked symmetrical battery assembly structure is encapsulated in an aluminum-plastic film, thereby effectively improving the accuracy of the cell impedance test result of the stacked symmetrical battery.

[0115] The above-mentioned embodiments only express several implementation methods of the present disclosure, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the disclosed patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present disclosure, and these all belong to the protection scope of the present disclosure. Therefore, the protection scope of the disclosed patent shall be subject to the attached claims.

Claims

1. A laminated symmetrical battery assembly structure, arranged in an aluminum-plastic film, the laminated symmetrical battery assembly structure comprises a symmetrical battery cell, the symmetrical battery cell comprises a first diaphragm, an isolation diaphragm and a second diaphragm stacked in sequence, the first diaphragm and the second diaphragm are arranged in alignment, characterized in that: Also included is a conductive component; The conductive component includes a first conductive sheet, a second conductive sheet, a first pole tab and a second pole tab. The first conductive sheet is in contact with a side of the first diaphragm facing away from the isolation diaphragm, and the second conductive sheet is in contact with a side of the second diaphragm facing away from the isolation diaphragm. The first pole tab is welded to the first conductive sheet, and the second pole tab is welded to the second conductive sheet. Both the first pole tab and the second pole tab are located on the outside of the aluminum-plastic film.

2. The laminated symmetrical battery assembly structure according to claim 1, characterized in that: The projection area of ​​the first diaphragm overlaps with the projection area of ​​the second diaphragm.

3. The laminated symmetrical battery assembly structure according to claim 1, characterized in that: The symmetrical battery cell also includes an insulating sheet, which is arranged between the first diaphragm and the isolation diaphragm, and has a hollow window.

4. The laminated symmetrical battery assembly structure according to claim 1, characterized in that: The projected area of ​​the first conductive sheet is greater than or equal to the projected area of ​​the first membrane sheet; The projected area of ​​the second conductive sheet is greater than or equal to the projected area of ​​the second membrane sheet.

5. The laminated symmetrical battery assembly structure according to claim 3, characterized in that: The projection area of ​​the isolation membrane is larger than the projection area of ​​the hollow window.

6. The laminated symmetrical battery assembly structure according to claim 3, characterized in that: The projected area of ​​the insulating sheet is larger than the projected area of ​​the first conductive sheet; A projected area of ​​the insulating sheet is larger than a projected area of ​​the second conductive sheet.

7. The symmetrical laminated battery assembly structure according to claim 1, characterized in that: The first membrane sheet includes a first foil layer, a first active material layer and a second active material layer. The first active material layer is bonded to one side of the first foil layer, and the second active material layer is bonded to the other side of the first foil layer.

8. The laminated symmetrical battery assembly structure according to claim 1, characterized in that: The second membrane includes a second foil layer, a third active material layer and a fourth active material layer. The third active material layer is bonded to one side of the second foil layer, and the fourth active material layer is bonded to the other side of the second foil layer.

9. The laminated symmetrical battery assembly structure according to claim 1, characterized in that: A first tab installation area is provided on the first conductive sheet, and the first tab is welded on the first tab installation area; and / or, A second pole tab installation area is formed on the second conductive sheet, and the second pole tab is welded on the second pole tab installation area.

10. A method for assembling a symmetrical laminated battery, characterized in that: Used to assemble the laminated symmetrical battery assembly structure according to any one of claims 1 to 9 and prepare a laminated symmetrical battery; The stacked symmetrical battery assembly method comprises the following steps: Obtaining a first aluminum-plastic film, a second aluminum-plastic film, a first film, an isolation film, a second film, a first conductive sheet, and a second conductive sheet; Performing a tab welding process on the first conductive sheet and the second conductive sheet, so that a first tab is formed on the first conductive sheet and a second tab is formed on the second conductive sheet; Punching the first aluminum-plastic film and the second aluminum-plastic film so that the first aluminum-plastic film is formed with a first positioning groove and the second aluminum-plastic film is formed with a second positioning groove; The first conductive sheet, the first diaphragm and the isolation diaphragm which have been subjected to the tab welding process are sequentially placed and stacked in the first positioning groove of the first aluminum-plastic diaphragm to obtain a first assembly; The second conductive sheet and the second diaphragm after the tab welding process are sequentially placed and stacked in the second positioning groove of the second aluminum-plastic diaphragm to obtain a second assembly; The first assembly and the second assembly are subjected to liquid injection packaging treatment to obtain a laminated symmetrical battery.

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