Battery structure

Abstract

The utility model belongs to the technical field of batteries, and particularly relates to a battery structure which comprises a first battery cell and a second battery cell which are electrically connected side by side, the first battery cell and the second battery cell are respectively provided with a first electrode and a second electrode which are opposite in polarity, and one side, facing the second battery cell, of the first battery cell is provided with a first foil electrically connected to the first electrode. One side, facing the first battery cell, of the second battery cell is provided with a second foil sheet electrically connected to the second electrode, and the first foil sheet and the second foil sheet are separated by a partition plate. The battery structure is high in reliability, and the safety of the battery structure can be effectively improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of batteries, and particularly relates to a battery structure. Background Art

[0002] Lithium-ion batteries are widely used in power fields such as electric vehicles, as well as consumer fields such as mobile phones, watches, tablets, and notebooks due to their advantages such as high specific energy, strong endurance, long cycle life, wide operating range, short charging time, and ability to discharge at high currents. As lithium-ion batteries gradually develop towards areas such as fast charging and high energy density, the safety issues brought by battery cells have gradually become a focus of attention. In the existing technology, there are currently no effective improvement measures in the industry. When lithium cobalt oxide and electrolytes with higher voltage systems are used, not only will the cost increase, but the existing voltage system is approaching a bottleneck, which will make the development of lithium cobalt oxide with higher voltage systems more difficult. Moreover, due to the demand for fast charging, the solvent ratio cannot be adjusted much, that is, the development of safety additives is also in a bottleneck. It can be seen that how to make the battery structure have sufficient safety has become one of the important difficulties in battery structure design. To this end, it is urgent to propose a new technical solution to solve the above problems. Utility Model Content

[0003] The purpose of the present invention is to provide a battery structure to address the deficiencies of the prior art, which can effectively optimize the battery structure and improve the safety of the battery structure.

[0004] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0005] A battery structure includes a first battery cell and a second battery cell electrically connected side by side, wherein the first battery cell and the second battery cell each have a first electrode and a second electrode with opposite polarities, the first battery cell having a first foil electrically connected to the first electrode on the side facing the second battery cell, and the second battery cell having a second foil electrically connected to the second electrode on the side facing the first battery cell, and the first foil and the second foil are separated by a partition.

[0006] As an improvement to the battery structure of the present invention, the first battery cell and the second battery cell have the same rated capacity, and the first battery cell and the second battery cell are connected in series using three electrodes or in parallel using two electrodes to complete external connection.

[0007] As an improvement to the battery structure of the present invention, the melting point of the separator is at least 105°C to 130°C.

[0008] As an improvement to the battery structure of the present invention, the thickness of the separator is no more than 25 μm.

[0009] As an improvement to the battery structure of the present invention, the first foil and the second foil are both insulated and connected to the partition, and the material of the partition is an insulating material. In order to improve the compactness of the assembly, there is no gap between the first foil and the second foil and the partition.

[0010] As an improvement to the battery structure of the present invention, the first battery cell, the partition and the second battery cell are all installed in a packaging film, and the first battery cell, the partition and the second battery cell are all fixed to the inner wall of the packaging film, and the inner wall and outer wall of the packaging film are both made of insulating material.

[0011] As an improvement to the battery structure of the present invention, the outer layer of the first battery cell is covered by the first foil, which is the empty foil area of ​​the first electrode of the first battery cell; the outer layer of the second battery cell is covered by the second foil, which is the empty foil area of ​​the second electrode of the second battery cell.

[0012] As an improvement to the battery structure of the present invention, at least one of the first battery cell and the second battery cell is a wound battery cell, and the area where the wound battery cell contacts the separator is the end area of ​​the wound battery cell.

[0013] As an improvement of the battery structure of the present invention, at least one of the first battery cell and the second battery cell is a Z-type laminated battery cell, and the area where the Z-type laminated battery cell contacts the separator is the empty foil area of ​​the Z-type laminated battery cell.

[0014] As an improvement to the battery structure of the present invention, the first battery cell and the second battery cell are stacked along the thickness direction of the battery structure, and at least part of the electrodes of the two battery cells are aligned or staggered.

[0015] As an improvement to the battery structure of the present invention, the first battery cell and the second battery cell are fixed together by a positioning belt.

[0016] As an improvement to the battery structure of the present invention, the positioning tape is a sticky adhesive tape or a plastic fixing tape with two ends closed and connected.

[0017] As an improvement to the battery structure of the present invention, the first battery cell and the second battery cell are both lithium-ion batteries, sodium-ion batteries or magnesium-ion batteries.

[0018] The beneficial effects of the present invention are as follows: the present invention comprises a first battery cell and a second battery cell which are electrically connected side by side, the first battery cell and the second battery cell both having a first electrode and a second electrode with opposite polarities, a first foil electrically connected to the first electrode on a side of the first battery cell facing the second battery cell, a second foil electrically connected to the second electrode on a side of the second battery cell facing the first battery cell, and the first foil and the second foil are separated by a partition, wherein 1) the thermal shock requirement for battery cell safety in the national standard GB31241 requires that the battery cell should not catch fire or explode at a specific high temperature for 1 hour, and the battery cell failure principle in this test is that the battery cell fails due to internal short circuit and heat accumulation, and compared with the defect of severe thermal runaway caused by the existing battery structure, the structure of the present invention is improved by making the first foil and the second foil The foils are separated by partitions, which can first realize the short circuit of the first foil and the second foil outside the battery cell under a preset high-temperature environment, thereby quickly losing the power inside the battery cell. Since the heat generated in this process is mainly on the surface of the battery cell, the battery cell effectively controls the thermal runaway by quickly dissipating heat on the surface; 2) Compared with the existing means of improving high-temperature thermal shock by using a higher-system positive electrode or electrolyte, which requires repeated verification of the system, the present invention mainly involves structural changes and does not involve changes in the system or materials, so that the original development system is retained, thereby effectively reducing the development difficulty and effectively controlling the production cost and time; 3) By effectively optimizing the structure of the battery, the safety of the battery structure of the present invention can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is one of the structural diagrams of Example 1 of the present utility model.

[0020] Figure 2 This is the second structural diagram of Example 1 of the present utility model.

[0021] Figure 3 This is an assembly diagram of Example 1 of the present utility model.

[0022] Figure 4 This is a structural diagram of Example 2 of the present utility model.

[0023] Among them: 1. first battery cell; 1a. first foil; 2. second battery cell; 2a. second foil; 3. first electrode; 4. second electrode; 5. separator; 6. packaging film; 61. first packaging film; 62. second packaging film; T, thickness direction of the battery structure. DETAILED DESCRIPTION

[0024] If certain terms are used to refer to specific components in the specification and claims, those skilled in the art will understand that manufacturers may use different terms to refer to the same component. This specification and claims do not distinguish components based on differences in name, but rather on differences in their functionality. Throughout the specification and claims, the term "including" is an open-ended term and should be interpreted as meaning "including, but not limited to."

[0025] In this utility model, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integral connection; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on specific circumstances.

[0026] The following is combined with Figures 1 to 4 The present invention is further described in detail with reference to the following specific embodiments, but is not intended to limit the present invention.

[0027] Example 1

[0028] A battery structure, see Figures 1 to 3 , including a first battery cell 1 and a second battery cell 2 electrically connected side by side, the first battery cell 1 and the second battery cell 2 both having a first electrode 3 and a second electrode 4 with opposite polarities, wherein the first battery cell 1 and the second battery cell 2 are connected in parallel, the first electrodes 3 of the first battery cell 1 and the second battery cell 2 are electrically connected, the second electrodes 4 of the first battery cell 1 and the second battery cell 2 are electrically connected, and the side of the first battery cell 1 facing the second battery cell 2 has a first foil 1a electrically connected to the first electrode 3, the side of the second battery cell 2 facing the first battery cell 1 has a second foil 2a electrically connected to the second electrode 4, the first foil 1a and the second foil 2a are separated by a partition 5, and the first foil 1a and the second foil 2a are both insulated and connected to the partition 5.

[0029] In the battery structure, one of the first electrode 3 and the second electrode 4 is the positive electrode, and the other is the negative electrode. The foil connected to the positive electrode is aluminum foil, and the foil connected to the negative electrode is copper foil. One of the first electrode 3 and the second electrode 4 is the positive tab, and the other is the negative tab. The first battery cell 1 and the second battery cell 2 are connected in parallel by internally connecting two tabs of the same polarity to complete the external connection. The position of the tabs of the first battery cell 1 and the second battery cell 2 and the spacing between the tabs can be adjusted as needed. The tabs of the first battery cell 1 and the second battery cell 2 partially overlap to achieve conductivity between the two battery cells.

[0030] Preferably, the rated capacity of the first battery cell 1 and the second battery cell 2 is the same, and the capacity designs of the two battery cells are completely consistent, which can ensure the battery cell grouping.

[0031] Preferably, the first battery cell 1 and the second battery cell 2 are stacked along the thickness direction T of the battery structure, and electrodes of the two battery cells with the same polarity are aligned along the thickness direction T of the battery structure.

[0032] Preferably, the outer layer of the first battery cell 1 is covered by a first foil 1a, and the outer layer of the second battery cell 2 is covered by a second foil 2a. Furthermore, the first battery cell 1 and the second battery cell 2 are both wound battery cells, and the area where each wound battery cell contacts the separator 5 is the end region of the wound battery cell. The contact between the end region and the separator 5 can effectively improve the stability and safety of the battery structure.

[0033] Specifically, the outermost layer of the first battery cell 1 is terminated by an aluminum foil connected to the positive electrode. The aluminum foil is part of the positive electrode sheet, and the outer layer of the first battery cell 1 is covered with aluminum foil. The outermost layer of the second battery cell 2 is terminated by a copper foil connected to the negative electrode. The copper foil is part of the negative electrode sheet, and the outer layer of the second battery cell 2 is covered with copper foil. This ensures that the bare foil positions corresponding to both sides of the separator 5 are bare cells. Among them, such a structural design avoids the situation where the first battery cell 1 and the second battery cell 2 cannot quickly achieve short-circuit contact on the outside when a thermal runaway anomaly occurs in the battery structure, thereby failing to effectively control thermal runaway. In addition, the number of layers of the tabs of the first battery cell 1 and the second battery cell 2 in the wound battery cell can be adjusted as needed.

[0034] In order to ensure that the first battery cell 1 and the second battery cell 2 have sufficient safety during normal operation and that the first battery cell 1 and the second battery cell 2 are externally conductive when the battery structure is in thermal runaway, that is, to ensure that the structure of the separator 5 is intact when the battery cell is in normal operation (the temperature of the battery cell is generally below 60°C), and to ensure that the external short circuit effect can be achieved when the internal abnormal conduction of the battery cell produces thermal runaway, the melting point of the separator 5 can be at least 105°C to 110°C, 110°C to 115°C, 115°C to 120°C, 120°C to 125°C or 125°C to 130°C, wherein the separator 5 can be transformed from solid to liquid at around 130°C. Preferably, the melting point of the separator 5 can be 108°C, 113°C, 118°C, 123°C or 128°C.

[0035] Preferably, the thickness of the separator 5 is not greater than 25 μm, and the thickness of the separator 5 can be at least 15 μm to 18 μm, 18 μm to 22 μm, or 22 μm to 25 μm. The material of the separator 5 can be a single layer of modified low-melting-point polypropylene, and the separator 5 has no stickiness. In the battery structure, it is necessary to ensure that the first foil 1a of the first battery cell 1 and the second foil 2a of the second battery cell 2 can be in complete contact when the separator 5 melts and disappears. In addition, the material modification method destroys the regularity of the polypropylene molecular chain, thereby reducing the crystallization ability of the molecular chain, so that the melting point temperature of the polymer can be controlled between 105°C and 130°C. In this way, it can be ensured that the contact point between the first foil 1a of the first battery cell 1 and the second foil 2a of the second battery cell 2 can be manufactured below 130°C.

[0036] Preferably, the first battery cell 1, the partition 5 and the second battery cell 2 are all installed in the packaging film 6, and at least part of the first battery cell 1, the partition 5 and the second battery cell 2 can be bonded to the inner wall of the packaging film 6 by adhesive, and the left and right sides of the partition 5 and the inner wall of the packaging film 6 can be fused and packaged under appropriate high temperature conditions, wherein the structures of the first battery cell 1 and the second battery cell 2 can be exactly the same or different, but the two battery cells have the same rated capacity. Specifically, the packaging film 6 can be formed by heat-sealing a first packaging film 61 and a second packaging film 62. The first packaging film 61 and the second packaging film 62 are both aluminum-plastic films. The position of each battery cell can be limited by the two aluminum-plastic films. The contact surface between each aluminum-plastic film and the battery cell can be fixed by solid glue or liquid glue. In addition, the pit depths of the first packaging film 61 and the second packaging film 62 are consistent, but the air bag lengths of the first packaging film 61 and the second packaging film 62 are designed differently. This is mainly to achieve targeted and effective monitoring of liquid injection and liquid retention in the subsequent sample preparation process to ensure the quality of each battery cell. In addition, after the battery packaging is completed, the first packaging film 61 and the second packaging film 62 can be adjusted to a structure with basically the same size.

[0037] After the battery is assembled, in a battery thermal shock test at 130°C (a test simulating thermal runaway caused by abnormal internal conduction of the battery cell), since the melting point of the partition 5 separating the first battery cell 1 and the second battery cell 2 is not greater than 130°C, that is, the partition 5 begins to change from solid to liquid at around 130°C. At the same time, since the partition 5 is relatively thin, holes can be quickly generated at around 130°C, thereby causing the first foil 1a of the first battery cell 1 and the second foil 2a of the second battery cell 2 to contact, resulting in an external short circuit and a rapid loss of power inside the two battery cells. The heat generated is mainly on the surface of the two battery cells, and the thermal runaway is effectively controlled through rapid heat dissipation of the surface layer. That is, this battery structure has high safety and is extremely safe during normal operation (the temperature of the battery cell is generally below 60°C).

[0038] Example 2

[0039] The difference from Example 1 is that, see Figure 4 The first cell 1 and the second cell 2 are connected in series, with some of the electrodes of the two cells staggered. The first cell 1 and the second cell 2 are connected in series using three internal tabs to complete the external connection. The middle tab of the three tabs is composed of two tabs of different polarity connected in series.

[0040] After the battery is assembled, in a battery thermal shock test at 130°C (a test simulating thermal runaway caused by abnormal internal conduction of the battery cell), since the melting point of the partition 5 separating the first battery cell 1 and the second battery cell 2 is not greater than 130°C, that is, the partition 5 begins to change from solid to liquid at around 130°C. At the same time, since the partition 5 is relatively thin, holes can be quickly generated at around 130°C, thereby causing the first foil 1a of the first battery cell 1 and the second foil 2a of the second battery cell 2 to contact, resulting in an external short circuit and a rapid loss of power inside the two battery cells. The heat generated is mainly on the surface of the two battery cells, and the thermal runaway is effectively controlled through rapid heat dissipation of the surface layer. That is, this battery structure has high safety and is extremely safe during normal operation (the temperature of the battery cell is generally below 60°C).

[0041] The other structures of this embodiment are the same as those of embodiment 1 and will not be described again here.

[0042] Example 3

[0043] Different from Example 1 or 2, at least one of the first battery cell 1 and the second battery cell 2 is a Z-type laminated battery cell, the outermost layer of the Z-type laminated battery cell does not need to be foil-wrapped, and the area where the Z-type laminated battery cell contacts the partition 5 is the empty foil area of ​​the Z-type laminated battery cell. At least one of the first battery cell 1 and the second battery cell 2 uses a Z-type laminated battery cell to obtain a battery structure with high safety that is the same as that of Example 1 or 2.

[0044] The other structures of this embodiment are the same as those of embodiment 1 or 2 and will not be described again here.

[0045] Example 4

[0046] Different from Examples 1 to 3, the first battery cell 1 and the second battery cell 2 can also be fixed together by a positioning tape, wherein the positioning tape can be a sticky tape or a plastic fixing tape with closed connections at both ends, so as to effectively improve the assembly firmness of the first battery cell 1 and the second battery cell 2.

[0047] The other structures of this embodiment are the same as those of embodiments 1 to 3 and will not be described again here.

[0048] Clearly, while maintaining the original design, the present invention overcomes the obstacles of rising material costs and system design limitations. By optimizing the specific structure of the two series / parallel cells, the failure mode in the 130°C thermal shock test is controlled, thereby controlling thermal runaway and achieving the desired cost and efficiency control. Furthermore, the separator of the present invention effectively separates the heat-generating surfaces of the first and second cells, so that the heat of the cells is primarily on the surface of the cells, and the rapid heat dissipation from the surface effectively controls thermal runaway.

[0049] Based on the disclosure and teachings of the above description, those skilled in the art will be able to make changes and modifications to the above embodiments. Therefore, the utility model is not limited to the specific embodiments described above. Any obvious improvements, substitutions, or modifications made by those skilled in the art based on the present utility model fall within the scope of protection of the present utility model. In addition, although certain specific terms are used in this description, these terms are for convenience only and do not constitute any limitation on the present utility model.

Claims

1. A battery structure, characterized in that: include: A first battery cell (1) and a second battery cell (2) electrically connected side by side, wherein the first battery cell (1) and the second battery cell (2) both have a first electrode (3) and a second electrode (4) with opposite polarities; The first battery cell (1) has a first foil (1a) electrically connected to the first electrode (3) on one side facing the second battery cell (2), and the second battery cell (2) has a second foil (2a) electrically connected to the second electrode (4) on one side facing the first battery cell (1); The first foil (1a) and the second foil (2a) are separated by a partition (5).

2. The battery structure according to claim 1, characterized in that: The first battery cell (1) and the second battery cell (2) have the same rated capacity; the first battery cell (1) and the second battery cell (2) are connected in series by three electrodes in series or in parallel by two electrodes in parallel to complete external connection.

3. The battery structure according to claim 1, characterized in that: The melting point of the separator (5) is at least 105°C to 130°C.

4. The battery structure according to any one of claims 1 to 3, characterized in that: The thickness of the separator (5) is not greater than 25 μm.

5. The battery structure according to any one of claims 1 to 3, characterized in that: The first battery cell (1), the partition (5) and the second battery cell (2) are all installed in a packaging film (6), and the first battery cell (1), the partition (5) and the second battery cell (2) are all fixed to the inner wall of the packaging film (6).

6. The battery structure according to any one of claims 1 to 3, characterized in that: The outer surface layer of the first battery core (1) is covered by the first foil (1a), and the outer surface layer of the second battery core (2) is covered by the second foil (2a).

7. The battery structure according to any one of claims 1 to 3, characterized in that: At least one of the first battery cell (1) and the second battery cell (2) is a wound battery cell, and the area where the wound battery cell contacts the separator (5) is the end area of ​​the wound battery cell.

8. The battery structure according to any one of claims 1 to 3, characterized in that: At least one of the first battery core (1) and the second battery core (2) is a Z-type laminated battery core, and the area where the Z-type laminated battery core contacts the separator (5) is an empty foil area of ​​the Z-type laminated battery core.

9. The battery structure according to any one of claims 1 to 3, characterized in that: The first battery cell (1) and the second battery cell (2) are stacked along the thickness direction of the battery structure, and at least part of the electrodes of the two battery cells are aligned or staggered.

10. The battery structure according to any one of claims 1 to 3, characterized in that: The first foil (1a) and the second foil (2a) are both insulated and connected to the partition (5).

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