Battery cell, battery pack and electric equipment

Abstract

The utility model relates to the technical field of batteries, in particular to a battery cell, a battery pack and electric equipment. The battery cell comprises a first enhanced infiltration sticking layer and / or a second enhanced infiltration sticking layer and a laminated pole group, the surfaces of the laminated pole group comprise a first diaphragm surface and a second diaphragm surface which are opposite to each other, a bottom surface and a top surface which are opposite to each other, and a first side surface and a second side surface which are opposite to each other; the bottom surface is provided with a first enhanced infiltration layer, and the first side surface and / or the second side surface are / is provided with a second enhanced infiltration layer. The battery cell disclosed by the utility model has excellent liquid absorption and liquid retention capabilities, and is beneficial to improving the electrochemical performance and the safety performance of the battery cell.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, and in particular to a battery core, a battery pack and electrical equipment. Background Art

[0002] Compared with other shells, aluminum shell lithium-ion batteries are widely used because of their good heat dissipation performance, high mechanical strength, light weight, good safety, simple process and low cost.

[0003] In order to improve the single cell energy density of the battery cell, a high-density, high-area-density material system will be selected. However, the high-density, high-area-density design has a direct negative impact on the efficiency of the injection process, especially the poor wettability of the pole pieces inside the pole group. The electrolyte is prone to increased liquid loss during the injection process, and large-area lithium deposition or black spots caused by poor wetting are prone to occur in the pre-charging process.

[0004] The usual way to improve the wettability of the battery cell electrode is to add materials with good liquid absorption and retention during the slurry mixing process; however, this material usually has poor conductivity, and after adding it, it will reduce the proportion of active substances, affecting battery performance. Another conventional method is to add a coating on the surface of the diaphragm to increase the liquid retention capacity of the diaphragm; however, it usually increases the margin of the battery cell group, thereby affecting assembly, and increases the internal impedance of the battery cell, affecting the internal capacity of the battery cell. The battery cell Mylar film is a polyester polymer Mylar insulating film with a thickness of 50 to 200 μm. Generally, a smooth insulating film is coated on the outside of the battery cell. Its function is: in the shelling process, in order to solve the problem that the stacked battery cell or the wound battery cell is easily scratched by the battery shell (aluminum shell, steel shell); and the insulating film can also reduce the micro-short circuit between the edge burrs of the battery cell and the metal shell (aluminum shell, steel shell) of the battery, so it is widely used in battery cell design. Due to the smooth inner wall of the Mylar film, the electrolyte accumulated at the bottom of the battery cell shell is difficult to effectively reach more interfaces of the laminated electrode group, reducing the wetting area between each layer of the electrode and the electrolyte.

[0005] In view of this, the present utility model is proposed. Utility Model Content

[0006] One purpose of the utility model is to provide a battery core to solve the technical problem that the existing battery core has poor liquid absorption and liquid retention performance. The battery core in the utility model has excellent liquid absorption and liquid retention performance, which is conducive to improving the electrochemical performance and safety performance of the battery core.

[0007] In order to achieve the above-mentioned purpose of the utility model, the following technical solutions are adopted:

[0008] A battery cell comprises a first reinforced wetting layer and / or a second reinforced wetting layer, and a laminated electrode group;

[0009] The surface of the laminated electrode group includes: an opposite first diaphragm surface and a second diaphragm surface, an opposite bottom surface and a top surface, and an opposite first side surface and a second side surface;

[0010] The first reinforcing wetting layer is disposed on the bottom surface, and the second reinforcing wetting layer is disposed on the first side surface and / or the second side surface.

[0011] In one embodiment, the first reinforced impregnated layer and the second reinforced impregnated layer independently include: a polyester fiber layer and a polymethyl methacrylate layer disposed on one side surface of the polyester fiber layer, and the polymethyl methacrylate layer is located between the laminated pole group and the polyester fiber layer.

[0012] In one embodiment, the polyester fiber layer is selected from a polybutylene terephthalate fiber layer, a polytrimethylene terephthalate fiber layer, or a laminate of a polybutylene terephthalate fiber layer and a polytrimethylene terephthalate fiber layer.

[0013] In one embodiment, the thickness of the first enhanced wetting layer is 300-900 μm.

[0014] In one embodiment, the thickness of the second enhanced wetting layer is 300-900 μm.

[0015] In one embodiment, the surface density of the polymethyl methacrylate layer is 0.2 to 0.6 mg / cm 2 .

[0016] In one embodiment, the polymethyl methacrylate layer has a thickness of 10 to 50 μm.

[0017] In one embodiment, the battery cell is further provided with an insulating coating film, and the insulating coating film is used to cover the laminated electrode group provided with the first enhanced wetting layer and the second enhanced wetting layer.

[0018] A battery pack comprises the battery cell.

[0019] An electrical device comprises the battery pack.

[0020] Compared with the prior art, the beneficial effects of the utility model are:

[0021] The battery cell of the present invention is advantageous in that the electrolyte is transported to more interfaces of the laminated electrode group by providing the first enhanced wetting layer and the second enhanced wetting layer, thereby increasing the contact area between the laminated electrode group and the electrolyte, thereby improving the electrolyte wetting ability of the electrode group and improving the electrochemical performance and safety performance of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the specific implementation methods of the utility model or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 It is a schematic diagram of the structure of the battery cell in the utility model;

[0024] Figure 2 This is a front view of the battery cell in the utility model;

[0025] Figure 3 It is a schematic diagram of the structure of the first enhanced wetting layer or the second enhanced wetting layer in the utility model.

[0026] Reference numerals:

[0027] 1-positive electrode ear, 2-negative electrode ear, 3-laminated electrode group, 301-first diaphragm surface, 302-bottom surface, 303-first side surface, 4-second reinforced impregnation layer, 5-first reinforced impregnation layer, 6-polymethyl methacrylate layer, 7-polyester fiber layer. DETAILED DESCRIPTION

[0028] In the description of the present utility model, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the utility model product is usually placed when in use, which are only for the convenience of describing the present utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as a limitation on the present utility model. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0029] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] In one aspect, the utility model relates to a battery core, comprising a first enhanced wetting layer and / or a second enhanced wetting layer, and a laminated electrode group;

[0031] The surface of the laminated electrode group includes: an opposite first diaphragm surface and a second diaphragm surface, an opposite bottom surface and a top surface, and an opposite first side surface and a second side surface;

[0032] The first reinforcing wetting layer is disposed on the bottom surface, and the second reinforcing wetting layer is disposed on the first side surface and / or the second side surface.

[0033] The battery cell of the utility model does not occupy too much internal space of the battery cell shell by providing the first enhanced wetting layer and the second enhanced wetting layer at appropriate positions of the laminated electrode group. The electrolyte accumulated at the bottom of the battery cell due to gravity can be transported to more interfaces of the laminated electrode group, thereby increasing the contact area between the laminated electrode group and the electrolyte, thereby improving the electrolyte wetting ability of the electrode group, which is beneficial to improving the electrochemical performance and safety performance of the battery cell.

[0034] In one embodiment, the first reinforced impregnated layer and the second reinforced impregnated layer each independently include: a polyester fiber layer, and a polymethyl methacrylate (PMMA) layer disposed on one surface of the polyester fiber layer, and the polymethyl methacrylate layer is located between the laminated pole group and the polyester fiber layer.

[0035] In one embodiment, the laminated electrode group includes a plurality of laminated body units, each of which includes a separator, a negative electrode sheet, a separator, a positive electrode sheet and a separator arranged in sequence. In one embodiment, the separator, the negative electrode sheet, the separator, the positive electrode sheet and the separator layer are sequentially stacked to form a laminated body unit, and a plurality of laminated body units are stacked to obtain a laminated electrode group.

[0036] In one embodiment, the separator is made of conventional materials, such as PE (polyethylene), PP (polypropylene), etc. The negative electrode sheet includes a negative electrode current collector and a negative electrode material layer disposed on at least one side of the negative electrode current collector, and the negative electrode current collector includes copper foil. The positive electrode sheet ensures a positive electrode current collector and a positive electrode material layer disposed on at least one side of the positive electrode current collector, and the positive electrode current collector includes aluminum foil. Both the positive electrode sheet and the negative electrode sheet are prepared according to conventional methods.

[0037] In one embodiment, the polyester fiber layer is selected from a polybutylene terephthalate (PBT) fiber layer, a polytrimethylene terephthalate (PTT) fiber layer, or a laminate of a polybutylene terephthalate fiber layer and a polytrimethylene terephthalate fiber layer.

[0038] In one embodiment, the polyester fiber is a synthetic fiber layer spun from a polymer in which each link in a macromolecular chain is connected by an ester group to form a fiber. The electrolyte at the bottom of the battery cell is "extracted" to the upper part of the electrode group through the fiber capillary gap of the polyester fiber layer. Because the polyester fiber layer is an excellent insulator, it can effectively eliminate the burrs on the edge of the battery cell and the micro-short-circuit channel of the battery metal shell (aluminum shell, steel shell), and improve the risk of poor voltage at the edge of the battery cell. The melting point of polyester fiber is about 255°C, and the glass transition temperature is about 70°C, so it can effectively reduce the side spray failure phenomenon of MEB and VDA model square batteries during heat propagation.

[0039] In one embodiment, polymethyl methacrylate has a relatively high viscosity and strength due to its relatively large side chains. The tensile and impact resistance of PMMA is 7 to 18 times higher than that of ordinary glass, and the melting point is relatively high, thereby effectively reducing the occurrence of thermal runaway (side spray phenomenon) of the narrow surface of the laminated battery cell.

[0040] In one embodiment, the thickness of the first enhanced wetting layer is 300-900 μm, including but not limited to 300 μm, 350 μm, 400 μm, 500 μm, 600 μm, 700 μm, 800 μm, 850 μm or 900 μm.

[0041] In one embodiment, the thickness of the second enhanced wetting layer is 300-900 μm, including but not limited to 300 μm, 350 μm, 400 μm, 500 μm, 600 μm, 700 μm, 800 μm, 850 μm or 900 μm.

[0042] In one embodiment, the surface density of the polymethyl methacrylate layer is 0.2 to 0.6 mg / cm 2 Including but not limited to 0.2mg / cm 2 , 0.3mg / cm 2 , 0.4mg / cm 2 , 0.5mg / cm 2 or 0.6mg / cm 2 wait.

[0043] In one embodiment, the thickness of the polymethyl methacrylate layer is 10 to 50 μm, for example, 10 μm, 20 μm, 30 μm, 40 μm or 50 μm.

[0044] In one embodiment, the battery cell is further provided with an insulating coating film, and the insulating coating film is used to cover the laminated electrode group provided with the first enhanced wetting layer and the second enhanced wetting layer.

[0045] In one embodiment, the battery cell is further provided with a positive electrode tab and a negative electrode tab.

[0046] In one embodiment, the battery cell is further provided with an electrolyte.

[0047] In a preferred embodiment, the method for preparing a battery cell comprises the following steps:

[0048] (a) According to conventional methods, a separator, a negative electrode sheet, a separator, a positive electrode sheet and a separator are sequentially laminated to obtain a plurality of laminate units, and the plurality of laminate units are stacked to obtain a laminated electrode group.

[0049] (b) preparing a first reinforcing impregnated layer and a second reinforcing impregnated layer, respectively comprising: coating PMMA on a single surface of a fiber layer having a thickness of 300 to 900 μm by a spraying process, with a surface density of 0.2 to 0.6 mg / cm 2 .

[0050] There is no particular order in which step (a) and step (b) are performed.

[0051] (c) Then cover the outside with an insulating coating film.

[0052] (d) The positive and negative electrode ears are then prepared by ultrasonic welding of the electrode ears.

[0053] (e) Then the cover plate laser welding, shell insertion and peripheral welding, liquid injection and chemical forming processes are carried out.

[0054] In another aspect, the utility model relates to a battery pack, comprising the battery core, and the battery pack has excellent liquid absorption and retention capabilities and excellent electrochemical performance.

[0055] In another aspect, the utility model relates to an electric device, including the battery pack, and the electric device includes an electric car and the like.

[0056] The following is further explained in conjunction with specific embodiments.

[0057] Example 1

[0058] A battery cell, see Figure 1 and Figure 2 , including a laminated pole group 3, a first reinforced wetting layer 5 and a second reinforced wetting layer 4.

[0059] The laminated electrode group 3 includes a plurality of laminated body units, each of which includes a separator, a negative electrode sheet, a separator, a positive electrode sheet and a separator arranged in sequence.

[0060] The surface of the laminated electrode group 3 includes: an opposite first diaphragm surface 301 and a second diaphragm surface, an opposite bottom surface 302 and a top surface, and an opposite first side surface 303 and a second side surface.

[0061] The first reinforcing wetting layer 5 is disposed on the bottom surface 302 , and the second reinforcing wetting layer 4 is disposed on the first side surface 303 .

[0062] The first reinforced impregnated patch 5 and the second reinforced impregnated patch 4 each independently include: a polyester fiber layer 7 and a polymethyl methacrylate layer 6 disposed on one side surface of the polyester fiber layer 7, see Figure 3 The polymethyl methacrylate layer 6 is located between the laminated electrode group 3 and the polyester fiber layer 7. The polyester fiber layer 7 is a PBT fiber layer with a thickness of 900 μm. The surface density of the polymethyl methacrylate layer 6 is 0.2 mg / cm 2 .

[0063] A method for preparing a battery cell, comprising:

[0064] (1) The first reinforcing impregnation layer 5 and the second reinforcing impregnation layer 4 are prepared, respectively, including: coating PMMA on one side of a 900 μm thick PBT fiber layer by spraying, with a surface density of 0.2 mg / cm 2 .

[0065] (2) After hot pressing the laminated electrode group 3 prepared in the lamination process, the first enhanced impregnation layer 5 is pasted on the bottom surface 302 of the laminated electrode group 3, and the second enhanced impregnation layer 4 is pasted on the first side surface 303 of the laminated electrode group 3; and then the outside is coated with an insulating coating film.

[0066] (3) The positive electrode ear 1 and the negative electrode ear 2 are prepared by ultrasonic welding of the electrode ears.

[0067] (4) Then the cover plate laser welding, shell insertion and peripheral welding, liquid injection and chemical forming processes are carried out.

[0068] Example 2

[0069] A battery core, wherein the thickness of the polyester fiber layer 7 is 300 μm, and the surface density of the polymethyl methacrylate layer 6 is 0.6 mg / cm 2 , other conditions are the same as in Example 1.

[0070] A method for preparing a battery cell, comprising:

[0071] (1) The first reinforcing impregnation layer 5 and the second reinforcing impregnation layer 4 are prepared, respectively, including: coating PMMA on one side of a 300 μm thick PBT fiber layer by a spraying process, with a surface density of 0.6 mg / cm 2 .

[0072] (2) After hot pressing the laminated electrode group 3 prepared in the lamination process, the first enhanced impregnation layer 5 is pasted on the bottom surface 302 of the laminated electrode group 3, and the second enhanced impregnation layer 4 is pasted on the first side surface 303 of the laminated electrode group 3; and then the outside is coated with an insulating coating film.

[0073] (3) The positive electrode ear 1 and the negative electrode ear 2 are prepared by ultrasonic welding of the electrode ears.

[0074] (4) Then the cover plate laser welding, shell insertion and peripheral welding, liquid injection and chemical forming processes are carried out.

[0075] Example 3

[0076] A battery core, except that the polyester fiber layer 7 is a PTT fiber layer, other conditions are the same as those of Example 1.

[0077] A method for preparing a battery cell, comprising:

[0078] (1) The first reinforcing impregnation layer 5 and the second reinforcing impregnation layer 4 are prepared, respectively, including: coating PMMA on one side of a 300 μm thick PTT fiber layer by a spraying process, with a surface density of 0.6 mg / cm 2 .

[0079] (2) After hot pressing the laminated electrode group 3 prepared in the lamination process, the first enhanced impregnation layer 5 is pasted on the bottom surface 302 of the laminated electrode group 3, and the second enhanced impregnation layer 4 is pasted on the first side surface 303 of the laminated electrode group 3; and then the outside is coated with an insulating coating film.

[0080] (3) The positive electrode ear 1 and the negative electrode ear 2 are prepared by ultrasonic welding of the electrode ears.

[0081] (4) Then the cover plate laser welding, shell insertion and peripheral welding, liquid injection and chemical forming processes are carried out.

[0082] Example 4

[0083] A battery core, wherein the thickness of the polyester fiber layer 7 is 600 μm, and the surface density of the polymethyl methacrylate layer 6 is 0.4 mg / cm 2 , other conditions are the same as in Example 1.

[0084] A method for preparing a battery cell, comprising:

[0085] (1) The first reinforcing impregnation layer 5 and the second reinforcing impregnation layer 4 are prepared, respectively, including: coating PMMA on one side of a 600 μm thick PTT fiber layer by a spraying process, with a surface density of 0.4 mg / cm 2 .

[0086] (2) After hot pressing the laminated electrode group 3 prepared in the lamination process, the first enhanced impregnation layer 5 is pasted on the bottom surface 302 of the laminated electrode group 3, and the second enhanced impregnation layer 4 is pasted on the first side surface 303 of the laminated electrode group 3; and then the outside is coated with an insulating coating film.

[0087] (3) The positive electrode ear 1 and the negative electrode ear 2 are prepared by ultrasonic welding of the electrode ears.

[0088] (4) Then the cover plate laser welding, shell insertion and peripheral welding, liquid injection and chemical forming processes are carried out.

[0089] Example 5

[0090] A battery core, except that the polyester fiber layer 7 is a PTT fiber layer, in the first reinforcing impregnation layer 5, the thickness of the polyester fiber layer 7 is 400 μm, and the surface density of the polymethyl methacrylate layer 6 is 0.6 mg / cm 2 In the second reinforcing impregnation layer 4, the thickness of the polyester fiber layer 7 is 700 μm, and the surface density of the polymethyl methacrylate layer 6 is 0.5 mg / cm 2 , other conditions are the same as in Example 1.

[0091] The preparation method of the battery cell in this embodiment is the same as that in Embodiment 1 except for the difference in the thickness of the polyester fiber layer 7 and the surface density of the polymethyl methacrylate layer 6 .

[0092] Example 6

[0093] A battery core, except that the polyester fiber layer 7 is a PTT fiber layer, in the first reinforcing impregnation layer 5, the thickness of the polyester fiber layer 7 is 300 μm, and the surface density of the polymethyl methacrylate layer 6 is 0.4 mg / cm 2 In the second reinforcing impregnation layer 4, the thickness of the polyester fiber layer 7 is 800 μm, and the surface density of the polymethyl methacrylate layer 6 is 0.6 mg / cm 2 , other conditions are the same as in Example 1.

[0094] The preparation method of the battery cell in this embodiment is the same as that in Embodiment 1 except for the difference in the thickness of the polyester fiber layer 7 and the surface density of the polymethyl methacrylate layer 6 .

[0095] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model, rather than to limit it. Although the utility model has been described in detail with reference to the above embodiments, ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the utility model.

Claims

1. A battery cell, characterized in that: It includes a first enhanced wetting layer and / or a second enhanced wetting layer, and a laminated pole group; The surface of the laminated electrode group includes: an opposite first diaphragm surface and a second diaphragm surface, an opposite bottom surface and a top surface, and an opposite first side surface and a second side surface; The first reinforcing wetting layer is disposed on the bottom surface, and the second reinforcing wetting layer is disposed on the first side surface and / or the second side surface.

2. The battery cell according to claim 1, characterized in that: The first reinforced impregnated layer and the second reinforced impregnated layer each independently include: a polyester fiber layer and a polymethyl methacrylate layer disposed on one side surface of the polyester fiber layer, and the polymethyl methacrylate layer is located between the laminated pole group and the polyester fiber layer.

3. The battery cell according to claim 2, characterized in that: The polyester fiber layer is selected from a polybutylene terephthalate fiber layer, a polytrimethylene terephthalate fiber layer, or a laminate of a polybutylene terephthalate fiber layer and a polytrimethylene terephthalate fiber layer.

4. The battery cell according to claim 1, characterized in that: The thickness of the first reinforcing wettable layer is 300-900 μm.

5. The battery cell according to claim 1, characterized in that: The thickness of the second enhanced infiltration layer is 300-900 μm.

6. The battery cell according to claim 2, characterized in that: The surface density of the polymethyl methacrylate layer is 0.2 to 0.6 mg / cm 2 .

7. The battery cell according to claim 2, characterized in that: The thickness of the polymethyl methacrylate layer is 10 to 50 μm.

8. The battery cell according to claim 1, characterized in that: The battery core is also provided with an insulating coating film, and the insulating coating film is used to cover the laminated electrode group provided with the first enhanced wetting layer and the second enhanced wetting layer.

9. A battery pack, characterized in that: A battery cell comprising the battery cell according to any one of claims 1 to 8.

10. An electrical device, characterized in that: A battery pack comprising the battery pack of claim 9.

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