Laminated battery cell, battery and electric equipment
By specially making ceramic coatings of different densities on the lithium battery separator, the overlapping areas with high heat-proof shrinkage capabilities and the over-the-counter areas with low heat-proof shrinkage capabilities are ensured, and the problem of short circuit and explosion caused by shrinking the lithium battery separator under high temperature conditions is solved, and the safety performance of the battery is improved.
Patent Information
- Application Number
- CN202421245695.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-03
- Publication Date
- 2025-04-15
- Estimated Expiration
- 2034-06-03
AI Technical Summary
Existing lithium battery separators are prone to shrink under high temperature conditions, resulting in the membrane losing its isolation effect, which may cause short circuits and explosions of lithium batteries.
A laminated cell separator is designed. By specially made ceramic coatings of different densities on the separator, the areas that completely overlap with the positive electrode sheet and the negative electrode sheet have high heat-proof shrinkage capabilities, and the areas beyond the edge of the electrode sheet have low heat-proof shrinkage capabilities, so that the membrane is more likely to experience heat shrinkage under high temperature conditions and avoid large-scale short circuits.
With this design, the battery can slowly release energy under high temperature conditions, avoiding thermal runaway and explosion, significantly improving the battery's safety performance.
Smart Images
Figure CN222763123U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of batteries, in particular to a laminated battery core, a battery and an electrical device. Background Art
[0002] With the continuous advancement of modern technology, electronic devices are widely used. Currently, electronic devices basically use lithium batteries to store electrical energy and power electronic devices. As the energy density of batteries increases, the safety performance of batteries is constantly challenged. How to ensure the safety performance of batteries while increasing the energy density of batteries is very important.
[0003] In the structure of lithium batteries, the diaphragm is one of the key internal components. The performance of the diaphragm determines the interface structure and internal resistance of the battery, directly affecting the battery's capacity, cycle and safety performance. A diaphragm with excellent performance plays an important role in improving the overall performance of the battery. The diaphragm design in the prior art is often immature. When the lithium battery is used for a long time, the temperature inside the lithium battery rises significantly, and the diaphragm shrinks when the temperature is high, causing the diaphragm to lose its insulation effect, resulting in a short circuit in the lithium battery, which may cause the lithium battery to explode. Utility Model Content
[0004] In view of this, the purpose of the utility model is to provide a stacked battery cell, a battery and an electrical device, so as to at least solve the problem in the prior art that the diaphragm shrinks due to high temperature, thereby causing the diaphragm to lose its insulating effect, resulting in the lithium battery being prone to short circuit, which may further cause the lithium battery to explode.
[0005] The utility model solves the above technical problems through the following technical means:
[0006] In a first aspect, the utility model provides a stacked battery cell, comprising a positive electrode sheet and a negative electrode sheet, and a separator stacked between the positive electrode sheet and the negative electrode sheet, wherein the separator comprises a first region that completely overlaps with the positive electrode sheet and / or the negative electrode sheet, and a second region that extends beyond the edge of the positive electrode sheet and / or the negative electrode sheet, and the heat shrinkage resistance of the second region is less than that of the first region.
[0007] In combination with the first aspect, in some embodiments, along the stacking direction, the heat shrinkage resistance of the second region of the diaphragm is smaller than that of the first region; and / or, parallel to the pole piece direction, the heat shrinkage resistance of the second region of the diaphragm is smaller than that of the first region.
[0008] In combination with the first aspect, in some embodiments, the diaphragm includes an insulating base layer, the front and back surfaces of the insulating base layer are coated with a first coating at positions corresponding to the first region, and at most one surface of the insulating base layer is coated with a second coating at a position corresponding to the second region.
[0009] In combination with the first aspect, in some embodiments, the heat shrinkage resistance of the second coating layer is less than the heat shrinkage resistance of the first coating layer.
[0010] In combination with the first aspect, in some embodiments, both the first coating and the second coating are ceramic coatings, and the density of the first coating is greater than the density of the second coating.
[0011] In combination with the first aspect, in some embodiments, the insulating base layer has only one surface facing the positive electrode plate and is coated with the second coating at a position corresponding to the second region; or, the insulating base layer has only one surface facing the negative electrode plate and is coated with the second coating at a position corresponding to the second region; or, the diaphragm is composed only of the insulating base layer in the second region.
[0012] The laminated battery cell of the utility model adopts a special diaphragm, and sets the heat shrinkage resistance of the second area beyond the edge of the positive electrode sheet and / or the negative electrode sheet to be less than the heat shrinkage resistance of the first area completely overlapping with the positive electrode sheet and / or the negative electrode sheet, so that the second area is more likely to produce heat shrinkage. When the battery encounters high temperature or generates a lot of heat itself, the diaphragm of the second area beyond the positive and negative electrode sheets will shrink thermally, so that the positive and negative electrode sheets will be slightly in contact and short-circuited, and the battery power will drop more slowly, releasing energy evenly, while the diaphragm of the first area overlapping with the positive and negative electrode sheets will not shrink, preventing the positive and negative electrode sheets from contacting and short-circuiting over a large area, avoiding large current discharge, and rapidly increasing temperature. Therefore, when the laminated battery cell of the utility model is assembled into a battery for use, it can slowly release energy, the temperature will not be too high, and there will be no thermal runaway, fire or explosion, which effectively improves the safety performance of the battery.
[0013] In a second aspect, the utility model further provides a battery, comprising the laminated battery cell described in the first aspect.
[0014] In a third aspect, the utility model further provides an electrical device, comprising the laminated battery cell described in the first aspect or the battery described in the second aspect.
[0015] The beneficial effects of the second and third aspects are substantially the same as those of the first aspect and will not be elaborated herein. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 is a schematic structural diagram of a laminated battery cell of Example 1;
[0017] Figure 2 is a schematic diagram of the structure of the diaphragm;
[0018] Among them, there are a positive electrode sheet 1 , a negative electrode sheet 2 , a separator 3 , an insulating base layer 31 , a first region 301 , a second region 302 , a first coating 41 , and a second coating 42 . DETAILED DESCRIPTION
[0019] The following describes the implementation of the present invention through specific embodiments. Those skilled in the art can understand the advantages and effects of the present invention from the contents disclosed in this specification. It should be noted that the illustrations provided in the following embodiments are only for exemplary descriptions, and they are only schematic diagrams, not physical diagrams, and cannot be understood as limitations on the present invention. In order to better illustrate the embodiments of the present invention, some parts in the figures may be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the figures may be omitted.
[0020] The same or similar numbers in the figures of the embodiments of the present invention correspond to the same or similar parts. In the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "back", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the figures, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, the terms describing the positional relationship in the figures are only used for illustrative purposes and cannot be understood as limitations on the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.
[0021] The diaphragm design in the prior art is often not mature enough. When the lithium battery is used for a long time, the temperature inside the lithium battery rises significantly, and the diaphragm will shrink when the temperature is high, so that the diaphragm loses its insulation effect, causing the lithium battery to be prone to short circuit, which may cause the lithium battery to explode. To this end, the present application proposes a laminated battery cell, with a diaphragm with a special size coating customized so that the diaphragm in the overlapping area with the positive and negative electrodes has a strong ability to prevent thermal shrinkage, while the part beyond the pole piece is prone to thermal shrinkage. When the battery encounters high temperature or generates a lot of heat by itself, the part beyond the pole piece will shrink thermally, causing the pole piece to slightly contact and short-circuit, and the battery power will drop relatively slowly, releasing energy evenly, while the diaphragm overlapping the pole piece remains uncontracted, preventing the pole piece from contacting and short-circuiting over a large area, avoiding large current discharge, and rapidly increasing temperature. Therefore, the battery releases energy slowly, the temperature will not be too high, there will be no thermal runaway, fire or explosion, and the battery safety can be effectively improved.
[0022] For details, please refer to Example 1-2.
[0023] Example 1
[0024] Please refer to Figure 1 and Figure 2 The laminated battery cell of this embodiment includes a positive electrode sheet 1 and a negative electrode sheet 2, and a separator 3 stacked between the positive electrode sheet 1 and the negative electrode sheet 2. The separator 3 includes a first area 301 that completely overlaps with the positive electrode sheet 1 and / or the negative electrode sheet 2, and a second area 302 that exceeds the edge of the positive electrode sheet 1 and / or the negative electrode sheet 2. The heat shrinkage resistance of the second area 302 is less than that of the first area 301.
[0025] In a laminated battery cell, the size of the negative electrode sheet 2 is generally larger than that of the positive electrode sheet 1 (e.g. Figure 1 As shown), in this case, the first region 301 of the diaphragm is the diaphragm region that completely overlaps with the negative electrode sheet 2, and the region that exceeds the edge of the negative electrode sheet 2 is the second region 302 of the diaphragm. Of course, there are other special laminated cells. For example, the size of the positive electrode sheet 1 is the same as the size of the negative electrode sheet 2. In this case, the first region 301 of the diaphragm is the diaphragm region that completely overlaps with both the positive electrode sheet 1 and the negative electrode sheet 2, and the region that exceeds both the positive electrode sheet 1 and the negative electrode sheet 2 is the second region 302 of the diaphragm; in another case, the size of the positive electrode sheet 1 is larger than the size of the negative electrode sheet 2. In this case, the first region 301 of the diaphragm is the diaphragm region that completely overlaps with the positive electrode sheet 1, and the region that exceeds the edge of the positive electrode sheet 1 is the second region 302 of the diaphragm.
[0026] In this embodiment, the negative electrode sheet 2, the diaphragm 3 and the positive electrode sheet 1 in the stacked battery cell are generally arranged in a cycle and stacked in a preset order of diaphragm 3, electrode sheet, diaphragm 3, electrode sheet, diaphragm 3, electrode sheet..., and the polarities of two adjacent electrode sheets are opposite, for example, diaphragm 3, positive electrode sheet 1, diaphragm 3, negative electrode sheet 2, diaphragm 3, positive electrode sheet 1..., or diaphragm 3, negative electrode sheet 2, diaphragm 3, positive electrode sheet 1, diaphragm 3, negative electrode sheet 2... are arranged in a cycle and stacked in a preset order.
[0027] In this embodiment, the heat-resistant shrinkage capability of the second region 302 is smaller than that of the first region 301. This means that the heat-resistant shrinkage capability of the second region 302 of the diaphragm 3 is smaller than that of the first region 301 along the stacking direction; or the heat-resistant shrinkage capability of the second region 302 of the diaphragm 3 is smaller than that of the first region 301 in the direction parallel to the pole piece; or the heat-resistant shrinkage capability of the second region 302 of the diaphragm 3 is smaller than that of the first region 301 regardless of whether it is along the stacking direction or parallel to the pole piece direction.
[0028] In this embodiment, the heat shrinkage capacity refers to the rate of change of the membrane's own dimensions under certain temperature conditions and within a certain period of time. The calculation formula is: T = (L1-L2) * 100% / L1; wherein T is the heat shrinkage rate of the membrane, in %; L1 is the length of the membrane before heating, in mm; L2 is the length of the membrane after heating, in mm. The length mentioned here can be the length of the membrane in the horizontal direction X, or the dimension of the membrane in the longitudinal direction Y, as long as L1 and L2 correspond, that is, if L1 is the length of the membrane before heating in the horizontal direction X, L2 must be the length of the membrane after heating in the horizontal direction X, and if L1 is the length of the membrane before heating in the longitudinal direction Y, L2 must be the length of the membrane after heating in the longitudinal direction Y.
[0029] It should be noted that the heat-shrinkage resistance of the second region 302 is smaller than that of the first region 301. This not only includes that the heat-shrinkage resistance of any region in the second region 302 is smaller than that of any region in the first region 301, but also includes that the heat-shrinkage resistance of some regions in the second region 302 is smaller than that of some regions in the first region 301. However, the overall heat-shrinkage resistance of the second region 302 of the diaphragm 3 is smaller than the overall heat-shrinkage resistance of the first region 301.
[0030] In this embodiment, the diaphragm 3 includes an insulating base layer 31 , the front and back surfaces of the insulating base layer 31 are coated with a first coating 41 at positions corresponding to the first region 301 , and at most one surface of the insulating base layer 31 is coated with a second coating 42 at positions corresponding to the second region 302 .
[0031] The insulating base layer 31 can be any of the existing diaphragms, which are generally thin film structures with a front side and a back side. The first coating layer 41 is a coating applied on the insulating base layer 31 that can effectively enhance the heat shrinkage resistance of the corresponding part of the insulating base layer 31. In order to more effectively enhance the heat shrinkage resistance of the diaphragm in the first region 301, the first coating layer 41 is applied on both the front and back sides of the diaphragm in the first region 301. The heat shrinkage resistance of the second coating layer 42 is less than that of the first coating layer 41. In this embodiment, the insulating base layer 31 can be selected to have only one surface facing the positive electrode plate 1 coated with the second coating layer 42 at the position corresponding to the second region 302; the insulating base layer 31 can also be selected to have only one surface facing the negative electrode plate 2 coated with the second coating layer 42 at the position corresponding to the second region 302; or the diaphragm 3 can be composed of only the insulating base layer 31 in the second region 302, and there is no second coating on both the front and back sides.
[0032] In this embodiment, the first coating 41 and the second coating 42 are both ceramic coatings, and the density of the first coating 41 is greater than the density of the second coating 42 , and the heat shrinkage resistance of the second coating 42 must also be less than that of the first coating 41 .
[0033] The laminated battery cell of this embodiment adopts a special diaphragm, and sets the heat shrinkage resistance of the second area 302 beyond the edge of the positive pole piece 1 and / or the negative pole piece 2 to be less than the heat shrinkage resistance of the first area 301 completely overlapping with the positive pole piece 1 and / or the negative pole piece 2, so that the second area 302 is more likely to produce heat shrinkage. When the battery encounters high temperature or generates a lot of heat itself, the diaphragm beyond the second area 302 of the positive and negative pole pieces will shrink, so that the positive and negative pole pieces will be slightly in contact and short-circuited, and the battery power will drop more slowly, releasing energy evenly, while the diaphragm of the first area 301 overlapping with the positive and negative pole pieces will not shrink, preventing the positive and negative pole pieces from contacting and short-circuiting over a large area, avoiding large current discharge, and rapidly increasing temperature. Therefore, when the laminated battery cell of the utility model is assembled into a battery for use, it can slowly release energy, the temperature will not be too high, and there will be no thermal runaway, fire or explosion, which effectively improves the safety performance of the battery.
[0034] Example 2
[0035] This embodiment discloses a battery, which includes the laminated battery cell described in the above embodiment 1. Other undescribed structures such as tabs, shell, electrolyte, etc. are the same as those of existing conventional laminated battery cells, and the specific configuration will not be repeated here.
[0036] When the battery of this embodiment encounters high temperature or generates a large amount of heat itself, it can slowly release energy, the temperature will not be too high, and there will be no thermal runaway, fire or explosion, which effectively improves the safety performance of the battery.
[0037] Example 3
[0038] This embodiment discloses an electric device, which includes the laminated battery cell described in Embodiment 1 or the battery of Embodiment 2. The electric device of this embodiment can be, but is not limited to, a mobile phone, a tablet, a laptop computer, an electric toy, a battery car, an electric car, a ship, etc.
[0039] The above embodiments are only used to illustrate the technical solution of the utility model and are not intended to limit it. Although the utility model is described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the utility model can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the utility model, which should be included in the scope of the claims of the utility model. The technology, shape, and structure that are not described in detail in the utility model are all well-known technologies.
Claims
1. A laminated battery cell, comprising a positive electrode sheet and a negative electrode sheet, and a separator stacked between the positive electrode sheet and the negative electrode sheet, characterized in that: The separator includes a first region completely overlapping with the positive electrode sheet and / or the negative electrode sheet, and a second region extending beyond the edge of the positive electrode sheet and / or the negative electrode sheet, wherein the heat shrinkage resistance of the second region is less than that of the first region.
2. The laminated battery cell according to claim 1, characterized in that: Along the lamination direction, the heat shrinkage resistance of the second region of the diaphragm is smaller than that of the first region; And / or, parallel to the pole piece direction, the heat shrinkage resistance of the second region of the diaphragm is smaller than the heat shrinkage resistance of the first region.
3. The laminated battery cell according to claim 1, characterized in that: The diaphragm includes an insulating base layer, the front and back surfaces of the insulating base layer are coated with a first coating at positions corresponding to the first region, and at most one surface of the insulating base layer is coated with a second coating at a position corresponding to the second region.
4. The laminated battery cell according to claim 3, characterized in that: The heat shrinkage resistance of the second coating layer is smaller than that of the first coating layer.
5. The laminated battery cell according to claim 4, characterized in that: The first coating and the second coating are both ceramic coatings, and the density of the first coating is greater than that of the second coating.
6. The laminated battery cell according to claim 5, characterized in that: The insulating base layer has only one surface facing the positive electrode sheet coated with a second coating at a position corresponding to the second region; Alternatively, the insulating base layer has only one surface facing the negative electrode plate coated with the second coating at a position corresponding to the second region; Alternatively, the diaphragm consists only of the insulating base layer in the second region.
7. A battery, characterized in that: The battery comprises a laminated battery cell as described in any one of claims 1 to 6.
8. An electrical device, characterized in that: The electrical equipment comprises the laminated battery cell according to any one of claims 1 to 6 or the battery according to claim 7.