Battery assembly, battery cell, and electric device

Abstract

This disclosure relates to the field of new energy technology, specifically to a battery module, a battery cell, and an electrical device. The battery module includes a separator, a positive electrode active material layer disposed on one side of the separator along its thickness direction, and a negative electrode active material layer disposed on the other side of the separator along its thickness direction. A positive electrode conductive portion is disposed at the edge of the positive electrode active material layer, located between the separator and the positive electrode active material layer; a negative electrode conductive portion is disposed at the edge of the negative electrode active material layer, located between the separator and the negative electrode active material layer; the positive and negative electrode conductive portions are arranged opposite each other along the horizontal direction of the separator's extension surface; the positive electrode conductive portion includes a first conductive metal, and the negative electrode conductive portion includes a second conductive metal. The positive and negative electrode conductive portions of this disclosure serve as tab welding areas, enabling the active material to be directly coated onto the separator, reducing the use of positive and negative current collectors, saving costs, and increasing energy density.

Description

Technical Field

[0001] This disclosure relates to the field of new energy technology, specifically to a battery module, a battery cell, and an electrical device. Background Technology

[0002] With the continuous expansion of energy storage business demands and the ongoing development of energy storage technology, the energy density and cost requirements for energy storage batteries are constantly increasing. Compared with power batteries, energy storage batteries have relatively lower requirements for fast charging capabilities. Based on these requirements, using thinner and lighter separators to replace metal current collectors can significantly improve energy density and reduce costs; however, how to design the connection between the active material layer and the battery tabs is a problem that urgently needs to be solved. Utility Model Content

[0003] In view of this, this disclosure aims to provide a battery module, a battery cell, and an electrical device to solve the problem of insufficient battery energy density in the prior art.

[0004] To solve the above-mentioned technical problems, this disclosure is implemented as follows:

[0005] The first aspect of this disclosure provides a battery assembly, the battery assembly including a separator, a positive electrode active material layer disposed on one side of the separator along the thickness direction, and a negative electrode active material layer disposed on the other side of the separator along the thickness direction.

[0006] Wherein, a positive electrode conductive part is provided at the edge end of the positive electrode active material layer, and the positive electrode conductive part is located between the separator and the positive electrode active material layer; a negative electrode conductive part is provided at the edge end of the negative electrode active material layer, and the negative electrode conductive part is located between the separator and the negative electrode active material layer;

[0007] The positive conductive portion and the negative conductive portion are arranged opposite each other along the horizontal direction of the extension surface of the diaphragm;

[0008] The positive electrode conductive part includes a first conductive metal, and the negative electrode conductive part includes a second conductive metal.

[0009] Optionally, the thickness of the positive electrode active material layer is 100–200 μm; and / or, the thickness of the negative electrode active material layer is 80–140 μm.

[0010] Optionally, the thickness of the positive electrode conductive portion is 2 to 20 μm; the intersection length between the positive electrode conductive portion and the positive electrode active material layer is 2 to 5 mm.

[0011] Optionally, the thickness of the negative electrode conductive part is 2 to 20 μm; the intersection length between the negative electrode conductive part and the negative electrode active material layer is 3 to 6 mm.

[0012] Optionally, the first conductive metal includes aluminum; the second conductive metal includes copper.

[0013] Optionally, the diaphragm includes a base membrane and an adhesive layer disposed on at least one surface of the base membrane along its thickness direction; the thickness of the diaphragm is 5–20 μm; and the thickness of the adhesive layer is 1–3 μm.

[0014] Optionally, the base film comprises at least one of polyethylene, polypropylene, aramid, polyimide, and polyacrylonitrile; and / or, the adhesive layer comprises at least one of polymethyl methacrylate, polyvinylidene fluoride, polymethyl methacrylate, aramid, polyacrylic acid, and polytetrafluoroethylene.

[0015] Optionally, the intersection length between the positive conductive part and the diaphragm is 3 to 10 mm; and / or, the intersection length between the negative conductive part and the diaphragm is 4 to 10 mm.

[0016] The second part of this disclosure provides a battery cell that includes the battery assembly described above.

[0017] The third part of this disclosure provides an electrical device that includes the aforementioned battery cell.

[0018] The beneficial technical effects of this disclosure through the above technical solution are as follows:

[0019] The present invention discloses a negative electrode conductive portion disposed at the edge of the negative electrode active material layer, the negative electrode conductive portion being located between the separator and the negative electrode active material layer; the positive electrode conductive portion and the negative electrode conductive portion are disposed opposite to each other along the horizontal direction of the separator. The positive electrode conductive portion and the negative electrode conductive portion of the present invention serve as tab welding areas, enabling the active material to be directly coated onto the separator, thereby reducing the use of positive and negative electrode current collectors, saving costs, and increasing energy density.

[0020] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0021] The accompanying drawings are provided to further understand the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof.

[0022] Figure 1 The diagram shown is a schematic of the battery assembly of this disclosure.

[0023] Figure 2 The diagram shown is a schematic diagram of the stacked assembly of the battery cell disclosed in this invention.

[0024] Figure 3 The diagram shown is a schematic of the Z-shaped assembly of the battery cell disclosed in this invention.

[0025] Explanation of reference numerals in the attached figures

[0026] 1 Positive electrode active material layer

[0027] 2. Negative electrode active material layer

[0028] 3 diaphragms

[0029] 4 Positive conductive part

[0030] 5 Negative conductive part Detailed Implementation

[0031] This application discloses a battery module, a battery cell, and an electrical device. Those skilled in the art can refer to the content herein to appropriately improve the process parameters to achieve the desired results. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this disclosure. The methods and applications of this disclosure have been described through preferred embodiments. Those skilled in the art can clearly modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit, and scope of this disclosure to implement and apply the technology of this disclosure.

[0032] In the description of this disclosure, the list of items connected by the term "at least one of" or other similar terms may mean any combination of the listed items. For example, if items A and B are listed, then the phrase "at least one of A and B" means only A; only B; or A and B. In another instance, if items A, B, and C are listed, then the phrase "at least one of A, B, and C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C. Item A may contain a single element or multiple elements. Item B may contain a single element or multiple elements. Item C may contain a single element or multiple elements.

[0033] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges or individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0034] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0035] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0036] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0037] To address the problem of insufficient battery energy density in existing technologies, this disclosure adopts the following technical solution:

[0038] The first aspect of this disclosure provides a battery assembly, such as Figure 1 As shown, the battery assembly includes a separator, a positive electrode active material layer disposed on one side of the separator along the thickness direction, and a negative electrode active material layer disposed on the other side of the separator along the thickness direction.

[0039] Wherein, a positive electrode conductive part is provided at the edge end of the positive electrode active material layer, and the positive electrode conductive part is located between the separator and the positive electrode active material layer; a negative electrode conductive part is provided at the edge end of the negative electrode active material layer, and the negative electrode conductive part is located between the separator and the negative electrode active material layer;

[0040] The positive conductive portion and the negative conductive portion are arranged opposite each other along the horizontal direction of the extension surface of the diaphragm;

[0041] The positive electrode conductive part includes a first conductive metal, and the negative electrode conductive part includes a second conductive metal.

[0042] The present invention discloses a negative electrode conductive portion disposed at the edge of the negative electrode active material layer, the negative electrode conductive portion being located between the separator and the negative electrode active material layer; the positive electrode conductive portion and the negative electrode conductive portion are disposed opposite each other along the horizontal direction of the extension surface of the separator. The positive electrode conductive portion and the negative electrode conductive portion of the present invention serve as tab welding areas, enabling the active material to be directly coated onto the separator, thereby reducing the use of positive and negative electrode current collectors, saving costs, and increasing energy density.

[0043] Unless otherwise specified, the positive and negative conductive parts in this disclosure can be provided by electroplating or by bonding metal foil with adhesive.

[0044] According to this disclosure, a suitable thickness of the positive electrode active material layer can balance energy density and kinetic performance. In this disclosure, the thickness of the positive electrode active material layer can be 100–200 μm. Exemplarily, the thickness of the positive electrode active material layer can be any value selected from 100 μm, 120 μm, 140 μm, 160 μm, 180 μm, and 200 μm, or any value within the range formed by any pair of the aforementioned values.

[0045] According to this disclosure, a suitable thickness of the negative electrode active material layer can balance energy density and kinetic performance. In this disclosure, the thickness of the negative electrode active material layer can be 80–140 μm. For example, the thickness of the negative electrode active material layer can be any value selected from 80 μm, 100 μm, 120 μm, and 140 μm, or any value within the range formed by any two of the above values.

[0046] According to this disclosure, when the thickness of the positive electrode conductive portion is too small, its current-carrying capacity is insufficient; when the thickness of the positive electrode conductive portion exceeds the upper limit, the current-carrying capacity is sufficient, and increasing the thickness will reduce the energy density and increase the cost; when the intersection length between the positive electrode conductive portion and the negative electrode active material layer is too small, the contact resistance between the positive electrode conductive portion and the active material layer is too large, which is not conducive to electron transport; when the intersection length between the positive electrode conductive portion and the negative electrode active material layer is too large, the intersection region will affect ion transport. In this disclosure, the thickness of the positive electrode conductive portion can be 2 to 20 μm; the intersection length between the positive electrode conductive portion and the positive electrode active material layer can be 2 to 5 mm. For example, the thickness of the positive electrode conductive portion can be any value among 2μm, 5μm, 8μm, 12μm, 15μm and 20μm or any value within the range of any two of the above values; the intersection length between the positive electrode conductive portion and the positive electrode active material layer can be any value among 1μm, 2μm, 3μm, 4μm and 5μm or any value within the range of any two of the above values.

[0047] According to this disclosure, when the thickness of the negative electrode conductive portion is too small, its current-carrying capacity is insufficient; when the thickness of the negative electrode conductive portion exceeds the upper limit, the current-carrying capacity is sufficient, and increasing the thickness will reduce the energy density and increase the cost; when the intersection length between the negative electrode conductive portion and the negative electrode active material layer is too small, the contact resistance between the negative electrode conductive portion and the active material layer is too large, which is not conducive to electron transport; when the intersection length between the negative electrode conductive portion and the negative electrode active material layer is too large, the intersection region will affect ion transport. In this disclosure, the thickness of the negative electrode conductive portion can be 2 to 20 μm; the intersection length between the negative electrode conductive portion and the negative electrode active material layer can be 3 to 6 mm. For example, the thickness of the negative electrode conductive portion can be any value among 2μm, 5μm, 8μm, 12μm, 15μm and 20μm or any value within the range of any two of the above values; the intersection length between the negative electrode conductive portion and the negative electrode active material layer can be any value among 3μm, 4μm, 5μm and 6μm or any value within the range of any two of the above values.

[0048] For example, the first conductive metal includes aluminum; the second conductive metal includes copper.

[0049] In some embodiments of this disclosure, the separator includes a base film and an adhesive layer disposed on at least one surface of the base film along its thickness direction; optionally, the thickness of the separator is 5–20 μm; the thickness of the adhesive layer is 1–3 μm. Exemplarily, the thickness of the separator can be any value selected from 5 μm, 10 μm, 12 μm, 15 μm, and 20 μm, or any value within the range formed by any two of the above values; the thickness of the adhesive layer can be any value selected from 1 μm, 1.5 μm, 2 μm, 2.5 μm, and 3 μm, or any value within the range formed by any two of the above values.

[0050] For example, the base film includes at least one of polyethylene, polypropylene, aramid, polyimide and polyacrylonitrile.

[0051] For example, the adhesive layer includes at least one of polymethyl methacrylate, polyvinylidene fluoride, polymethyl methacrylate, aramid, polyacrylic acid, and polytetrafluoroethylene.

[0052] In some embodiments of this disclosure, the intersection length between the positive conductive portion and the separator is 3–10 mm; and / or, the intersection length between the negative conductive portion and the separator is 4–10 mm. Exemplarily, the intersection length between the positive conductive portion and the separator can be any value from 3 μm, 5 μm, 7 μm, 9 μm, and 10 μm, or any value within the range formed by any two of the above values; the intersection length between the negative conductive portion and the separator can be any value from 4 μm, 6 μm, 8 μm, and 10 μm, or any value within the range formed by any two of the above values.

[0053] In one embodiment of this disclosure, the positive electrode active material layer comprises positive electrode active material particles, the resistivity of which is 5 to 50 Ω·cm; a carbon coating layer is disposed on the surface of the positive electrode active material particles, or the positive electrode active material particles are doped with a metal element; the metal element includes at least one of Group IVB, Group VB and Group VIIB elements.

[0054] For example, the metallic element includes at least one of titanium, manganese, and vanadium.

[0055] In some embodiments of this disclosure, the positive electrode active material layer further includes a lithium replenishing agent, a first binder, and a first conductive agent; optionally, based on the total mass of the positive electrode active material layer, the content of the lithium replenishing agent is 1-5 wt%, the content of the first binder is 1.5-2.5 wt%, and the content of the first conductive agent is 1.5-2.5 wt%; optionally, the positive electrode active material particles include at least one of lithium iron phosphate, lithium manganese iron phosphate, and lithium nickel cobalt manganese oxide; optionally, the lithium replenishing agent includes at least one of lithium ferrite, lithium nickel oxide, and lithium oxalate; optionally, the first binder includes at least one of polyvinylidene fluoride, polyacrylic acid, and polyacrylate; optionally, the first conductive agent includes at least one of conductive carbon black, Ketjen black, carbon nanotubes, and graphene.

[0056] In some embodiments of this disclosure, the negative electrode active material layer includes a negative electrode material, a negative electrode dispersant, a second binder, and a second conductive agent; optionally, based on the total mass of the negative electrode active material layer, the content of the negative electrode dispersant is 0.05–2 wt%, the content of the second binder is 1.5–2.5 wt%, and the content of the second conductive agent is 1.5–2.5 wt%; optionally, the negative electrode dispersant includes at least one of carboxymethyl cellulose salt, polyvinylpyrrolidone, polyvinyl alcohol, polyethylene glycol, and polyacrylonitrile; optionally, the second binder includes at least one of polyvinylidene fluoride, polyacrylic acid, styrene-butadiene rubber, and polyacrylate; optionally, the second conductive agent includes at least one of conductive carbon black, Ketjen black, carbon nanotubes, and graphene.

[0057] In some embodiments of this disclosure, the negative electrode active material layer further includes an auxiliary agent; the auxiliary agent includes a hydroxyl-containing compound and / or a carbonyl-containing compound; optionally, the hydroxyl-containing compound includes at least one selected from ethylene glycol, 1,3-butanediol, propylene glycol, and glycerol; optionally, the carbonyl-containing compound includes at least one selected from N-methylpyrrolidone, diethyl carbonate, ethylene carbonate, and propylene carbonate; optionally, the content of the auxiliary agent is 0.05–3 wt% based on the total mass of the negative electrode active material layer.

[0058] The second part of this disclosure provides a battery cell comprising the battery assembly described above. Figure 2 and Figure 3 As shown, the battery cell of the present invention can be assembled using a stacked assembly or a Z-shaped assembly.

[0059] The third part of this disclosure provides an electrical device that includes the aforementioned battery cell.

[0060] The present disclosure is further described in detail below through examples. All raw materials used in the examples are commercially available.

[0061] Example 1

[0062] Lithium iron phosphate, lithium ferrite, polyvinylidene fluoride (PVDF), conductive carbon black (SP), and other components were mixed evenly in a stirred tank at a ratio of 94:2:2:2 to prepare a positive electrode slurry.

[0063] Graphite, styrene-butadiene rubber (SBR), sodium carboxymethyl cellulose (CMC), and SP were mixed evenly in a stirred tank at a ratio of 95:2:1.5:1.5 to prepare the negative electrode slurry.

[0064] A layer of copper is electroplated on one side of a 12μm thick PE separator as the negative conductive part, and the thickness of the electroplated copper layer is 10μm; on the other side of the separator, an aluminum foil is bonded with an adhesive as the positive conductive part, and the thickness of the aluminum foil is 15μm.

[0065] The negative electrode slurry is coated on one side of the separator, and the intersection length between the active material coating area and the negative electrode conductive part is controlled to be 4μm. After drying in an oven, the thickness of the negative electrode active material layer is 100μm.

[0066] The positive electrode slurry is coated on the surface opposite to the negative electrode active layer of the separator, and the intersection length between the active material coating area and the positive electrode conductive part is controlled to be 3μm; after drying in an oven, the thickness of the positive electrode active material layer is 180μm.

[0067] The prepared electrode rolls are slit and die-cut to suitable sizes, and then assembled into battery cells in a stacked manner.

[0068] Ethylene carbonate, methyl ethyl carbonate, and diethyl carbonate were mixed in a volume ratio of 1:1:1 to obtain a mixed organic solvent. Then, fully dried lithium salt LiPF6 was dissolved in the mixed organic solvent at a ratio of 1.2 mol / L to prepare an electrolyte.

[0069] The battery is formed by injecting it into the cell.

[0070] Comparative Example 1

[0071] Lithium iron phosphate, lithium ferrite, PVDF, and SP were mixed evenly in a stirred tank at a ratio of 94:2:2:2 to prepare a positive electrode slurry.

[0072] Graphite, SBR, CMC and SP were mixed evenly in a stirred tank at a ratio of 95:2:1.5:1.5 to prepare the negative electrode slurry.

[0073] The negative electrode slurry was uniformly coated on both sides of a 4.5μm copper foil. After drying in an oven, the thickness of the negative electrode active material layer was 200μm.

[0074] The positive electrode slurry was coated on both sides of a carbon-coated aluminum foil (the aluminum foil was 15 μm thick, and a carbon coating layer with a thickness of 1 μm was provided on both sides of the aluminum foil surface). After drying in an oven, the thickness of the positive electrode active material layer was 360 μm.

[0075] The prepared electrode rolls are slit and die-cut to suitable sizes, and then assembled with PE separators in a stacked manner to form battery cells.

[0076] Ethylene carbonate, methyl ethyl carbonate, and diethyl carbonate were mixed in a volume ratio of 1:1:1 to obtain a mixed organic solvent. Then, fully dried lithium salt LiPF6 was dissolved in the mixed organic solvent at a ratio of 1.2 mol / L to prepare an electrolyte.

[0077] The battery is formed by injecting it into the cell.

[0078] Test Example 1

[0079] The batteries prepared in the examples and comparative examples were subjected to performance tests, and the test results are shown in Table 1.

[0080] The method for testing gravimetric energy density is as follows:

[0081] (1) Weigh the battery using an electronic balance;

[0082] (2) Place the battery in a 25°C incubator for 6 hours to reach temperature equilibrium;

[0083] (3) Charge at a constant current rate of 0.33C to 3.65V, then charge at a constant voltage rate to 0.05C;

[0084] (4) Let it sit for 30 minutes;

[0085] (5) Discharge to 2.5V at a constant current rate of 0.33C;

[0086] The ratio of the energy value of the discharged battery in step (5) to the weight value of the battery in step (1) is the battery's gravimetric energy density.

[0087] The method for testing volumetric energy density is as follows:

[0088] (1) Use vernier calipers to measure the length, width and height of the battery;

[0089] (2) Place the battery in a 25°C incubator for 6 hours to reach temperature equilibrium;

[0090] (3) Charge at a constant current rate of 0.33C to 3.65V, then charge at a constant voltage rate to 0.05C;

[0091] (4) Let it sit for 30 minutes;

[0092] (5) Discharge to 2.5V at a constant current rate of 0.33C;

[0093] The ratio of the energy value of the discharged battery in step (5) to the battery volume value calculated in step (1) is the battery volumetric energy density.

[0094] The test method for ambient temperature cycling is as follows:

[0095] (1) Place the battery in a 25℃ incubator for 6 hours to reach temperature equilibrium;

[0096] (2) Charge to 3.65V at a constant power rate of 0.25P;

[0097] (3) Let it sit for 10 minutes;

[0098] (4) Discharge at a constant power rate of 0.25P to 2.5V, and record the capacity at this time as C1;

[0099] (5) Let it sit for 10 minutes;

[0100] (6) Repeat steps (2) to (5), and record the discharge capacity of each step as C. n ;

[0101] (7) Calculate C n The minimum number of cycles when / C1≤80% is the cycle life of the battery.

[0102] Table 1

[0103]

[0104] As can be seen from Table 1, the electrode of this disclosure significantly reduces the weight of the battery by reducing the use of metal current collectors, thereby increasing the weight energy density of the battery; at the same time, the space used by reducing the metal current collectors can be used to place more active materials, thereby increasing the volumetric energy density of the battery; and at a rate of 0.25P, it has little impact on the room temperature cycle life of the battery.

[0105] The above description is only a preferred embodiment of this disclosure. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principles of this disclosure, and these improvements and modifications should also be considered within the scope of protection of this disclosure.

Claims

1. A battery assembly, comprising: The battery assembly includes a separator, a positive electrode active material layer disposed on one side of the separator along the thickness direction, and a negative electrode active material layer disposed on the other side of the separator along the thickness direction. Wherein, a positive electrode conductive part is provided at the edge end of the positive electrode active material layer, and the positive electrode conductive part is located between the separator and the positive electrode active material layer; a negative electrode conductive part is provided at the edge end of the negative electrode active material layer, and the negative electrode conductive part is located between the separator and the negative electrode active material layer; The positive conductive portion and the negative conductive portion are arranged opposite each other along the horizontal direction of the extension surface of the diaphragm; The positive electrode conductive part includes a first conductive metal, and the negative electrode conductive part includes a second conductive metal.

2. The battery assembly of claim 1, wherein, The thickness of the positive electrode active material layer is 100–200 μm; and / or, The thickness of the negative electrode active material layer is 80–140 μm.

3. The battery assembly of claim 1 or 2, wherein, The thickness of the positive electrode conductive part is 2 to 20 μm; the intersection length between the positive electrode conductive part and the positive electrode active material layer is 2 to 5 mm.

4. The battery assembly of claim 1 or 2, wherein, The thickness of the negative electrode conductive part is 2 to 20 μm; the intersection length between the negative electrode conductive part and the negative electrode active material layer is 3 to 6 mm.

5. The battery assembly according to claim 1, characterized in that, The first conductive metal includes aluminum; The second conductive metal includes copper.

6. The battery assembly of claim 1, wherein, The diaphragm includes a base membrane and an adhesive layer disposed on at least one surface of the base membrane along its thickness direction; The thickness of the diaphragm is 5–20 μm; The thickness of the adhesive layer is 1–3 μm.

7. The battery assembly of claim 6, wherein, The base film comprises at least one of polyethylene, polypropylene, aramid, polyimide, and polyacrylonitrile; and / or, The adhesive layer includes at least one of polymethyl methacrylate, polyvinylidene fluoride, polymethyl methacrylate, aramid, polyacrylic acid, and polytetrafluoroethylene.

8. The battery assembly of claim 1, wherein, The intersection length between the positive conductive part and the diaphragm is 3-10 mm; and / or, The intersection length between the negative electrode conductive part and the diaphragm is 4 to 10 mm.

9. An electric cell characterized by The battery cell includes the battery assembly described in any one of claims 1 to 8.

10. An electric device, characterized by The electrical equipment includes the battery cell as described in claim 9.

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