Series cell and lithium ion battery

Abstract

The utility model discloses a series battery cell, and relates to the technical field of lithium ion batteries. The series battery cell comprises a first battery cell, a first packaging film, a second battery cell and a second packaging film, the first battery cell comprises a first pole piece group and a first tab; the first packaging film wraps the first pole piece group, and the first tab is exposed out of the first packaging film; the second battery cell comprises a second pole piece group stacked with the first pole piece group, and a second pole lug electrically connected with the first pole lug; and the second packaging film and the first packaging film are arranged in a stacking manner and wrap the second pole piece group, the first pole piece group and the first packaging film, so that the first battery cell and the second battery cell are wrapped and packaged into a whole, and the packaging reliability of the series battery cells is improved. Therefore, when the series battery cells are impacted or vibrated by the outside, the relative position between the first battery cell and the second battery cell is not easy to deviate, so that the impact resistance of the lithium ion battery is improved. The utility model also discloses a lithium ion battery.

Description

Technical Field

[0001] The utility model relates to the technical field of lithium ion batteries, in particular to a series-connected battery cell and a lithium ion battery. Background Art

[0002] Lithium-ion batteries are a commonly used rechargeable battery that is widely used in electric vehicles, mobile devices, energy storage systems, etc. For lithium-ion batteries with high voltage requirements, two or more cells are usually connected in series to increase the output voltage of the battery.

[0003] However, lithium-ion batteries with cells connected in series also have some problems. For example, during use, lithium-ion batteries with cells connected in series may be subject to various external shocks and vibrations, such as falling, collisions, vibrations, etc. These shocks and vibrations may cause the relative positions of the cells to shift, affecting the connection status between the cells, thereby affecting the performance and safety of the battery. For example, the shift between the cells may increase the resistance between the cells, reducing the output power of the battery; or cause a short circuit between the cells, causing safety accidents such as overheating, fire, and explosion of the battery.

[0004] Therefore, it is very important to improve the packaging reliability of series-connected cells to enhance the impact resistance of lithium-ion batteries. Utility Model Content

[0005] The utility model provides a series-connected battery cell, which can improve the packaging reliability of the series-connected battery cell and enhance the impact resistance of the lithium-ion battery.

[0006] In order to achieve the above-mentioned purpose, the utility model adopts the following technical solutions:

[0007] A series-connected battery cell, comprising:

[0008] A first battery cell, comprising a first electrode group and a first electrode tab;

[0009] A first packaging film covers the first pole piece group, and the first pole ear is exposed from the first packaging film;

[0010] A second battery cell, comprising a second pole piece group stacked with the first pole piece group, and a second pole lug electrically connected to the first pole lug;

[0011] The second packaging film is stacked with the first packaging film and covers the second pole piece group, the first pole piece group and the first packaging film.

[0012] In some embodiments, the first packaging film is configured with a first recess, which can accommodate the first pole piece group; the second packaging film is configured with a second recess, which can accommodate the second pole piece group and the first pole piece group coated with the first packaging film.

[0013] In some embodiments, the first packaging film is a polypropylene film; and / or the second packaging film is an aluminum-plastic film.

[0014] In some embodiments, adhesive glue is provided between the first pole piece group and the first packaging film;

[0015] And / or, an adhesive is provided between the first packaging film and the second packaging film;

[0016] And / or, an adhesive is provided between the first packaging film and the second pole piece group;

[0017] And / or, an adhesive is provided between the second pole piece group and the second packaging film.

[0018] In some embodiments, the first electrode tab includes a first positive electrode tab and a first negative electrode tab, the second electrode tab includes a second positive electrode tab and a second negative electrode tab, and the first negative electrode tab is connected to the second positive electrode tab.

[0019] In some embodiments, the first negative electrode tab is welded to the second positive electrode tab.

[0020] In some embodiments, a welding area between the first negative electrode tab and the second positive electrode tab is greater than 40% of an area of ​​the first negative electrode tab or the second positive electrode tab.

[0021] In some embodiments, the first positive electrode tab and the first negative electrode tab, and the second positive electrode tab and the second negative electrode tab are all provided with tab glue.

[0022] In some embodiments, the first packaging film forms a first liquid injection bag, which is connected to the first pit; the second packaging film forms a second liquid injection bag, which is connected to the second pit; the first liquid injection bag and the second liquid injection bag are not connected to each other.

[0023] The present invention also provides a lithium-ion battery in an embodiment. The lithium-ion battery includes the series-connected battery cells as described in the above embodiment.

[0024] In the technical solution of the utility model, the first packaging film encapsulates the first pole piece group of the first battery cell, and the second packaging film encapsulates the first pole piece group and the second pole piece group that have been encapsulated by the first packaging film to form a whole, thereby improving the packaging reliability of the series-connected battery cells. In this way, when the series-connected battery cells of the utility model are subjected to external impact or vibration, the relative position between the first battery cell and the second battery cell will not be easily offset, thereby improving the impact resistance of the lithium-ion battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic structural diagram of a first battery cell in an expanded state of a first packaging film in an embodiment of the utility model;

[0026] Figure 2 It is a schematic structural diagram of a first battery cell in a first packaging film packaging state in one embodiment of the utility model;

[0027] Figure 3 It is a schematic structural diagram of a second battery cell in an expanded state of a second packaging film in an embodiment of the utility model;

[0028] Figure 4 It is a schematic structural diagram of the series-connected cells in an embodiment of the utility model when the second packaging film is unfolded;

[0029] Figure 5 It is a schematic structural diagram of the series-connected battery cells in a second packaging film packaging state in one embodiment of the utility model.

[0030] Description of Figure Numbers

[0031] Label name Label name 100 First battery 200 Second battery 10 The first pole piece group 20 The second pole piece group 1 First pole 2 Second pole 3 The first packaging film 4 Second packaging film 31 The first pit 41 The second pit 11 The first positive ear 12 First negative terminal 21 Second positive ear 22 The second negative terminal 5 Ear glue 32 First fluid bag 42 Second injection bag

[0032] The realization of the purpose, functional features and advantages of the utility model will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0033] In the present invention, the terms "disposed", "provided with", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, elements, or components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] The orientation or position relationship indicated by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. are based on the orientation or position relationship shown in the drawings and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0035] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0036] In addition, some of the above terms may be used to express other meanings in addition to indicating orientation or positional relationship. For example, the term "on" may also be used to express a certain dependency or connection relationship in some cases. For those skilled in the art, the specific meanings of these terms in this utility model can be understood according to specific circumstances.

[0037] In order to make the purpose, technical solution and advantages of the utility model more clear, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model and are not used to limit the utility model.

[0038] See also Figures 1 to 5 , Figure 1 The structure of the first battery cell 100 is shown in the unfolded state of the first packaging film 3; Figure 2 The structure of the first battery cell 100 in a packaging state of the first packaging film 3 is shown; Figure 3 The structure of the second battery cell 200 is shown in the unfolded state of the second packaging film 4; Figure 4 The structure of the series-connected cells in the unfolded state of the second packaging film 4 is shown; Figure 5 The structure of the series-connected cells in a packaging state with the second packaging film 4 is shown.

[0039] The embodiment of the utility model provides a series-connected battery cell, which includes a first battery cell 100, a first packaging film 3, a second battery cell 200 and a second packaging film 4. The first battery cell 100 includes a first pole piece group 10 and a first pole ear 1; the first packaging film 3 covers the first pole piece group 10, and the first pole ear 1 is exposed from the first packaging film 3; the second battery cell 200 includes a second pole piece group 20 stacked with the first pole piece group 10, and a second pole ear 2 electrically connected to the first pole ear 1; the second packaging film 4 is stacked with the first packaging film 3, and covers the second pole piece group 20, the first pole piece group 10 and the first packaging film 3.

[0040] like Figure 1 As shown, in the present embodiment, the first battery cell 100 includes a first electrode sheet group 10 and a first electrode tab 1, and the first electrode tab 1 is connected to the first electrode sheet group 10. The first battery cell 100 may be a wound battery cell or a stacked battery cell. Exemplarily, the first electrode sheet group 10 includes a positive electrode sheet, a separator and a negative electrode sheet. The positive electrode sheet, the separator and the negative electrode sheet are stacked in sequence and then wound to form the first electrode sheet group 10 of the wound battery cell. Alternatively, the first electrode sheet group 10 includes a plurality of positive electrode sheets, separators and negative electrode sheets, and the plurality of positive electrode sheets, separators and negative electrode sheets are stacked in sequence to form the first electrode sheet group 10 of the stacked battery cell. The first packaging film 3 of the present embodiment has an upper packaging film and a lower packaging film connected to each other. Before packaging, the upper packaging film and the lower packaging film are in an unfolded state, and the first electrode sheet group 10 is placed on the lower packaging film. As shown Figure 2 As shown, after the first pole piece group 10 is placed on the lower packaging film, the upper packaging film and the lower packaging film are folded in half, and the side edges of the packaging film are sealed to cover the first pole piece group 10. The first packaging film 3 can be a polypropylene film or an aluminum-plastic film.

[0041] like Figure 3 As shown, in the present embodiment, the second battery cell 200 includes a second electrode group 20 and a second electrode tab 2, and the second battery cell 200 can be a wound battery cell or a stacked battery cell. Exemplarily, the second electrode group 20 includes a positive electrode sheet, a separator and a negative electrode sheet. The positive electrode sheet, the separator and the negative electrode sheet are stacked in sequence and then wound to form the second electrode group 20 of the wound battery cell. Alternatively, the second electrode group 20 includes a plurality of positive electrode sheets, separators and negative electrode sheets, and the plurality of positive electrode sheets, separators and negative electrode sheets are stacked in sequence to form the second electrode group 20 of the stacked battery cell. The second packaging film 4 of the present embodiment has an upper packaging film and a lower packaging film connected to each other. Before packaging, the upper packaging film and the lower packaging film are in an unfolded state, and the second electrode group 20 is placed on the lower packaging film. As shown Figure 4 As shown, after the second electrode assembly 20 is placed on the lower packaging film, the first battery cell 100 covered with the first packaging film 3 is stacked on the second battery cell 200. Then, as shown in FIG. Figure 5As shown, the upper packaging film and the lower packaging film of the second packaging film 4 are folded in half, and the side edges of the second packaging film 4 are sealed, so that the second battery cell 200 and the first battery cell 100 coated with the first packaging film 3 are coated together, so that the first battery cell 100 and the second battery cell 200 coated with the first packaging film 3 are packaged into a whole, thereby improving the packaging reliability of the series battery cells. In this way, when subjected to external shock or vibration, the relative position between the first battery cell 100 and the second battery cell 200 will not easily shift, thereby improving the impact resistance of the lithium-ion battery. In this embodiment, the second pole ear 2 is electrically connected to the first pole ear 1 to achieve the series connection of the second battery cell 200 and the first battery cell 100. The second packaging film 4 of this embodiment can be a polypropylene film or an aluminum-plastic film.

[0042] In some embodiments, the first packaging film 3 is configured with a first pit 31 , which can accommodate the first pole piece group 10 ; the second packaging film 4 is configured with a second pit 41 , which can accommodate the second pole piece group 20 and the first pole piece group 10 coated with the first packaging film 3 .

[0043] like Figure 1 As shown, a first pit 31 is formed on the first packaging film 3, and the first pit 31 is used to place the first pole piece group 10. Exemplarily, the first pit 31 is formed by a punching molding process, and the first packaging film 3 is deformed by a punching mold, so as to form the first pit 31 on the first packaging film 3. The depth of the first pit 31 is not less than the thickness of the first pole piece group 10, so that the first pole piece group 10 is placed in the first pit 31. Optionally, the first pit 31 can be formed on one of the upper packaging film and the lower packaging film of the first packaging film 3, or can be formed on the upper packaging film and the lower packaging film of the first packaging film 3 at the same time, and the first pit 31 is formed by folding the upper packaging film and the lower packaging film in half.

[0044] like Figure 3 and Figure 4 As shown, a second pit 41 is formed on the second packaging film 4, and the second pit 41 is used to place the second pole piece group 20 and the first pole piece group 10 covering the first packaging film 3. Exemplarily, the second pit 41 is formed by a punching molding process, and the second packaging film 4 is deformed by a punching mold, so as to form the second pit 41 on the second packaging film 4. The depth of the second pit 41 is not less than the thickness of the first pole piece group 10 and the second pole piece group 20 superimposed, so as to place the first pole piece group 10 and the second pole piece group 20 in the second pit 41. Optionally, the second pit 41 can be formed on one of the upper packaging film and the lower packaging film of the second packaging film 4, or can be formed on the upper packaging film and the lower packaging film of the second packaging film 4 at the same time, and the second pit 41 is formed by folding the upper packaging film and the lower packaging film in half.

[0045] In some embodiments, the first packaging film 3 is a polypropylene film; and / or the second packaging film 4 is an aluminum-plastic film.

[0046] In this embodiment, the first packaging film 3 is a polypropylene film, and the second packaging film 4 is an aluminum-plastic film, which includes a polypropylene layer, an aluminum foil layer, and a nylon layer distributed from the inside to the outside. Since the innermost layers of the first packaging film 3 and the second packaging film 4 are made of the same material, during heat sealing, the polypropylene layers of the first packaging film 3 and the second packaging film 4 are melted together, and the bonding is tighter and stronger, thereby improving the reliability of the packaging.

[0047] In some embodiments, adhesive is provided between the first electrode assembly 10 and the first packaging film 3;

[0048] And / or, an adhesive is provided between the first packaging film 3 and the second packaging film 4;

[0049] And / or, an adhesive is provided between the first packaging film 3 and the second electrode assembly 20;

[0050] And / or, an adhesive is provided between the second electrode assembly 20 and the second packaging film 4 .

[0051] In this embodiment, an adhesive is provided between the first electrode group 10 and the first packaging film 3, so that the first electrode group 10 is bonded to the first packaging film 3 to stabilize the position of the first electrode group 10 in the first packaging film 3; an adhesive is provided between the first packaging film 3 and the second packaging film 4, so that the first electrode group 10 covering the first packaging film 3 is bonded to the second packaging film 4 to stabilize the position of the first electrode group 10 in the second packaging film 4; an adhesive is provided between the first packaging film 3 and the second electrode group 20, so that the first electrode group 10 covering the first packaging film 3 is bonded to the second electrode group 20 to stabilize the position of the first electrode group 10 stacked on the second electrode group 20; an adhesive is provided between the second electrode group 20 and the second packaging film 4, so that the second electrode group 20 is bonded to the second packaging film 4 to stabilize the position of the second electrode group 20 in the second packaging film 4.

[0052] In this embodiment, the adhesive is a double-sided hot melt adhesive. During heat sealing, the double-sided hot melt adhesive bonds the first electrode group 10, the first packaging film 3, the second electrode group 20 and the second packaging film 4 into a whole to prevent the position of the battery cells from shifting, thereby improving the reliability of the packaging.

[0053] In some embodiments, the first electrode tab 1 includes a first positive electrode tab 11 and a first negative electrode tab 12 , the second electrode tab 2 includes a second positive electrode tab 21 and a second negative electrode tab 22 , and the first negative electrode tab 12 is connected to the second positive electrode tab 21 .

[0054] like Figure 1As shown, the first positive electrode tab 11 and the first negative electrode tab 12 extend from the positive electrode sheet and the negative electrode sheet of the first electrode sheet group 10 respectively, wherein the first positive electrode tab 11 is arranged close to the side of the first electrode sheet group 10. Figure 3 As shown, the second positive electrode tab 21 and the second negative electrode tab 22 extend from the positive electrode sheet and the negative electrode sheet of the second electrode sheet assembly 20 respectively, wherein the second negative electrode tab 22 is arranged close to the side of the second electrode sheet assembly 20. Figure 4 As shown, the first negative electrode tab 12 is connected to the second positive electrode tab 21, so that the first battery cell 100 and the second battery cell 200 are connected in series. Exemplarily, the first negative electrode tab 12 is welded to the second positive electrode tab 21, and the first negative electrode tab 12 can be welded to the second positive electrode tab 21 by ultrasonic welding.

[0055] In some embodiments, the welding area between the first negative electrode ear 12 and the second positive electrode ear 21 is greater than 40% of the area of ​​the first negative electrode ear 12 or the second positive electrode ear 21. In this embodiment, the first negative electrode ear 12 and the second positive electrode ear 21 are stacked, wherein the overlapping area of ​​the two is the welding area, and the area of ​​the welding area is greater than 40% of the area of ​​the first negative electrode ear 12 or the second positive electrode ear 21, thereby ensuring the welding strength.

[0056] In some embodiments, the first positive electrode tab 11 and the first negative electrode tab 12 , the second positive electrode tab 21 and the second negative electrode tab 22 are all provided with tab glue 5 .

[0057] In this embodiment, the tab glue 5 is used to bond the tab to the first packaging film 3 or the second packaging film 4, so as to firmly bond the tab. For example, the first positive tab 11 and the first negative tab 12 are bonded to the first packaging film 3 through the tab glue 5, and the second positive tab 21 and the second negative tab 22 are bonded to the second packaging film 4 through the tab glue 5.

[0058] In some embodiments, the first packaging film 3 forms a first liquid injection bag 32, which is connected to the first pit 31; the second packaging film 4 forms a second liquid injection bag 42, which is connected to the second pit 41; the first liquid injection bag 32 and the second liquid injection bag 42 are not connected to each other.

[0059] like Figure 2 As shown, in this embodiment, a first liquid injection bag 32 is formed on one side of the first packaging film 3, and the first liquid injection bag 32 is connected to the first pit 31, and the electrolyte is injected from the first liquid injection bag 32 into the first pit 31. Figure 5 As shown, a second liquid injection bag 42 is formed on one side of the second packaging film 4, and the second liquid injection bag 42 is connected to the second pit 41, and the electrolyte is injected into the second pit 41 from the second liquid injection bag 42. The first liquid injection bag 32 and the second liquid injection bag 42 are not connected to each other, so that the electrolyte in the first pit 31 and the electrolyte in the second pit 41 do not affect each other.

[0060] The present invention also provides a lithium-ion battery in an embodiment. The lithium-ion battery includes the series-connected battery cells described in the above embodiment.

[0061] The specific structure of the series-connected battery cell refers to the above embodiment. Since the lithium-ion battery adopts all the technical solutions of all the above embodiments, it at least has all the technical effects brought by the technical solutions of the above embodiments, which will not be described one by one here.

[0062] The above is only a specific implementation of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A series-connected battery cell, characterized in that: include: A first battery cell, comprising a first electrode group and a first electrode tab; A first packaging film covers the first pole piece group, and the first pole ear is exposed from the first packaging film; A second battery cell, comprising a second pole piece group stacked with the first pole piece group, and a second pole lug electrically connected to the first pole lug; The second packaging film is stacked with the first packaging film and covers the second pole piece group, the first pole piece group and the first packaging film.

2. The series-connected battery cell according to claim 1, characterized in that: The first packaging film is configured with a first recess, which can accommodate the first pole piece group; the second packaging film is configured with a second recess, which can accommodate the second pole piece group and the first pole piece group coated with the first packaging film.

3. The series-connected battery cell according to claim 1 or 2, characterized in that: The first packaging film is a polypropylene film; and / or the second packaging film is an aluminum-plastic film.

4. The series-connected battery cell according to claim 1, characterized in that: An adhesive is provided between the first pole piece group and the first packaging film; And / or, an adhesive is provided between the first packaging film and the second packaging film; And / or, an adhesive is provided between the first packaging film and the second pole piece group; And / or, an adhesive is provided between the second pole piece group and the second packaging film.

5. The series-connected battery cell according to claim 1, characterized in that: The first electrode tab includes a first positive electrode tab and a first negative electrode tab, the second electrode tab includes a second positive electrode tab and a second negative electrode tab, and the first negative electrode tab is connected to the second positive electrode tab.

6. The series-connected battery cell according to claim 5, characterized in that: The first negative electrode tab is welded to the second positive electrode tab.

7. The series-connected battery cell according to claim 6, characterized in that: The welding area between the first negative electrode tab and the second positive electrode tab is greater than 40% of the area of ​​the first negative electrode tab or the second positive electrode tab.

8. The series-connected battery cell according to claim 5, characterized in that: The first positive electrode tab and the first negative electrode tab, and the second positive electrode tab and the second negative electrode tab are all provided with tab glue.

9. The series-connected battery cell according to claim 2, characterized in that: The first packaging film forms a first liquid injection bag, which is connected to the first pit; the second packaging film forms a second liquid injection bag, which is connected to the second pit; the first liquid injection bag and the second liquid injection bag are not connected to each other.

10. A lithium ion battery, characterized in that: Comprising the series-connected battery cell as claimed in any one of claims 1 to 9.

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