Pole piece structure, battery and electric device

Abstract

The utility model belongs to the technical field of secondary batteries, and particularly relates to a pole piece structure which comprises a composite current collector and conducting layers, the conducting layers are positioned on two opposite surfaces of the composite current collector, the elongation percentage of the conducting layers is smaller than that of the composite current collector, and the composite current collector comprises a first metal layer, a polymer layer and a second metal layer which are sequentially overlapped. The pole piece is high in structural safety, can effectively prevent the composite current collector of the pole piece from being influenced by the stress effect in the cold pressing process, and further solves the problems that the metal layer of the composite current collector cracks and falls off and the like. In addition, the utility model also discloses a battery and an electric device.

Description

Technical Field

[0001] The utility model belongs to the technical field of secondary batteries, and in particular relates to a pole piece structure, a battery and an electrical device. Background Art

[0002] Lithium-ion batteries have been widely used in energy storage, 3C, new energy vehicles and other fields due to their advantages such as high energy density, stable discharge, long cycle life, low self-discharge rate, high platform voltage and good safety performance. However, in the manufacturing process of the battery pole piece, the pole piece usually needs to be cold pressed. During this process, the pole piece often cracks due to the stress on the current collector, which makes the different material layers of the pole piece fall off. At present, how to make the pole piece structure have sufficient safety has become one of the 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] One of the purposes of the utility model is to provide a pole piece structure to address the deficiencies of the prior art, which has high structural safety and can effectively prevent the pole piece from being cracked or wrinkled due to the stress on the composite current collector during the cold pressing process.

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

[0005] A pole piece structure comprises a composite current collector and a conductive layer, wherein the conductive layer is located on two opposite sides of the composite current collector, the elongation of the conductive layer is smaller than the elongation of the composite current collector, and the composite current collector comprises a first metal layer, a polymer layer and a second metal layer stacked in sequence.

[0006] As an improvement of the pole piece structure of the present invention, the thickness of the first metal layer and the thickness of the second metal layer are respectively smaller than the thickness of the polymer layer.

[0007] As an improvement of the pole piece structure of the utility model, the elongation rate of the conductive layer is 45% to 95% of the elongation rate of the composite current collector.

[0008] As an improvement of the pole piece structure of the utility model, the elongation rate of the conductive layer is 0.6% to 0.8%.

[0009] As an improvement of the pole piece structure of the utility model, the thickness of the conductive layer is 0.5 μm to 5 μm.

[0010] As an improvement of the pole piece structure of the utility model, the resistivity of the conductive layer is not greater than 3Ω·m.

[0011] As an improvement of the pole piece structure of the utility model, an active material layer is arranged on the surface of the conductive layer away from the composite current collector, and the thickness of the conductive layer is not greater than the thickness of the active material layer.

[0012] As an improvement of the pole piece structure of the utility model, the conductive layer contains carbon-based conductive particles.

[0013] As an improvement of the pole piece structure of the utility model, the carbon-based conductive particles are one or more of graphene, carbon nanotubes or conductive carbon black. Among them, the average particle size of graphene can be 0.24μm to 0.34μm, the average particle size of carbon nanotubes can be 10nm-20nm, and the average particle size of conductive carbon black can be 10nm-30nm.

[0014] As an improvement of the pole piece structure of the utility model, the active material layer has active particles, and the particle size ratio of the carbon-based conductive particles to the active particles is not greater than 0.2.

[0015] As an improvement of the pole piece structure of the utility model, the active particles are LiCoO 2 、LiNiO 2 、LiVO 2 、LiCrO 2 、LiMn 2 O 4 、LiCoMnO 4 , Li 2 NiMn 3 O 8 、LiNi 0.5 Mn 1.5 O 4 、LiCoPO 4 、LiMnPO 4 、LiFePO 4 、LiNiPO 4 、LiCoFSO 4 , CuS 2 , FeS 2 、MoS 2 、NiS、TiS 2 One or more of the above particles.

[0016] The second purpose of the utility model is to provide a battery, comprising the above-mentioned pole piece structure.

[0017] The third object of the present utility model is to provide an electrical device comprising the battery as described above.

[0018] The beneficial effect of the utility model is that the pole piece structure of the utility model includes a composite current collector and a conductive layer, the conductive layer is located on two opposite sides of the composite current collector, the elongation of the conductive layer is less than the elongation of the composite current collector, and the composite current collector includes a first metal layer, a polymer layer and a second metal layer stacked in sequence, wherein, since the elongation of the conductive layer and the elongation of the composite current collector are adapted to the cold pressing environment, the conductive layer can reduce the stress on the composite current collector during the cold pressing process, and the stress acts on the conductive layer in the pole piece without significantly affecting the polymer layer and the metal layer, thereby improving the dislocation phenomenon caused by the mismatch of ductility between the polymer layer and the metal layer, thereby improving and overcoming the problem of cracking and falling off of the metal layer of the composite current collector, and improving the safety and conductivity of the pole piece. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic structural diagram of Example 1 of the utility model.

[0020] Wherein: 1. composite current collector; 2. conductive layer; 3. active material layer; 11. first metal layer; 12. second metal layer; 13. polymer layer. DETAILED DESCRIPTION

[0021] If certain words are used in the specification and claims to refer to specific components, those skilled in the art should understand that the manufacturer may use different nouns to refer to the same component. This specification and claims do not use differences in names as a way to distinguish components, but use differences in the functions of components as the criteria for distinction. As mentioned throughout the specification and claims, "including" is an open term, so it should be interpreted as "including but not limited to". "Approximately" means that within an acceptable error range, those skilled in the art can solve technical problems within a certain error range and basically achieve technical effects. In this application, the terms "first", "second", etc. are only used to distinguish different components and cannot be understood as indicating or implying relative importance.

[0022] In the description of the present invention, it should be understood that the terms "upper", "lower", "top", "side", "front", "back", "left", "right", "horizontal", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and 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 orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0023] In the utility model, unless otherwise clearly specified and limited, the terms "install", "connect", "connect", "fix" and the like 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 an indirect connection 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 utility model can be understood according to the specific circumstances.

[0024] The following is combined with Figure 1 The utility model is further described in detail with specific embodiments, but is not intended to limit the utility model.

[0025] Example 1

[0026] A pole piece structure, see Figure 1 , including a composite current collector 1 and a conductive layer 2, wherein the conductive layer 2 is located on two opposite sides of the composite current collector 1, the elongation of the conductive layer 2 is less than the elongation of the composite current collector 1, and the composite current collector 1 includes a first metal layer 11, a polymer layer 13 and a second metal layer 12 stacked in sequence.

[0027] Within the elastic limit, the ratio of the stress to the material to the corresponding strain is called the elastic modulus of the material. In the cold pressing environment, the stress acts on the conductive layer 2 in the pole piece without affecting the polymer layer 13 with a low elastic modulus. This effectively improves the misalignment phenomenon caused by the mismatch in ductility between the polymer layer 13 and each metal layer, thereby overcoming the cracking and falling off problems of the first metal layer 11 and the second metal layer 12 of the composite current collector 1. In addition, the conductive layer 2 has good conductivity, thereby improving the safety and conductivity of the pole piece.

[0028] Preferably, the thickness of the first metal layer 11 and the thickness of the second metal layer 12 are respectively smaller than the thickness of the polymer layer 13, wherein the polymer layer 13 can be a high molecular insulating material, and the thickness of the first metal layer 11 and the thickness of the second metal layer 12 can be respectively smaller than the thickness of the conductive layer 2, thereby reducing the influence of cold pressure stress on the first metal layer 11 and the second metal layer 12.

[0029] Preferably, the elongation of the conductive layer 2 is 45% to 55%, 55% to 65%, 65% to 75%, 75% to 85% or 85% to 95% of the elongation of the composite current collector 1, wherein one conductive layer 2 covers the first metal layer 11 and the other conductive layer 2 covers the second metal layer 12, and the first metal layer 11 and the second metal layer 12 may be aluminum layers.

[0030] Preferably, the elongation of the conductive layer 2 is 0.6% to 0.8%. Within this range, the conductive layer 2 is not easily affected by cold compression stress.

[0031] Preferably, the thickness of the conductive layer 2 is 0.5μm to 1.5μm, 1.5μm to 2.5μm, 2.5μm to 3.5μm, 3.5μm to 4.5μm or 4.5μm to 5.5μm, and the resistivity of the conductive layer 2 is not greater than 3Ω·m. Within this range, the conductivity of the conductive layer 2 and the elastic modulus of the conductive layer 2 are best matched.

[0032] Preferably, an active material layer 3 is disposed on a surface of the conductive layer 2 away from the composite current collector 1 , and the thickness of the conductive layer 2 is not greater than the thickness of the active material layer 3 .

[0033] Specifically, the conductive layer 2 contains carbon-based conductive particles, which may be one or more of graphene, carbon nanotubes, or conductive carbon black. The average particle size of graphene may be 0.24 μm to 0.34 μm, the average particle size of carbon nanotubes may be 10 nm to 20 nm, and the average particle size of conductive carbon black may be 10 nm to 30 nm.

[0034] Preferably, the active material layer 3 has active particles, and the particle size ratio of the carbon-based conductive particles to the active particles is not greater than 0.2. Within this range, the energy density of the manufactured battery can be maintained at a high level, and the force distribution of the composite current collector during cold pressing can be improved.

[0035] Specifically, the electrode structure is a positive electrode, and the active particles of the active material layer 3 can be LiCoO 2 、LiNiO 2 、LiVO 2 、LiCrO 2 、LiMn 2 O 4 、LiCoMnO 4 , Li 2 NiMn 3 O 8 、LiNi 0.5 Mn 1.5 O 4 、LiCoPO 4 、LiMnPO 4 、LiFePO 4 、LiNiPO 4 、LiCoFSO 4 , CuS 2 , FeS 2 、MoS 2 、NiS、TiS 2 One or more of the above particles.

[0036] Example 2

[0037] Different from the first embodiment, in the present embodiment, a channel is provided in the polymer layer 13 , and a conductive material connecting the first metal layer 11 and the second metal layer 12 is filled in the channel to make the first metal layer 11 and the second metal layer 12 conductive.

[0038] The other structures of this embodiment are the same as those of Embodiment 1 and will not be described again here.

[0039] Example 3

[0040] A battery comprises the electrode structure of any one of the batteries of embodiments 1 to 2. The battery may be a lithium ion battery, a sodium ion battery, a magnesium ion battery, etc.

[0041] Example 4

[0042] An electrical device, including the battery of Example 3, wherein the electrical device can be a vehicle, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, an electric tool, etc. The vehicle can be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc.; the spacecraft includes an airplane, a rocket, a space shuttle and a spacecraft, etc.; the electric toy includes a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy and an electric airplane toy, etc.; the electric tool includes a metal cutting electric tool, a grinding electric tool, an assembly electric tool and a railway electric tool, such as an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, an impact drill, a concrete vibrator and an electric planer, etc. The embodiments of the present application do not impose any special restrictions on the above-mentioned electrical devices.

Claims

1. A pole piece structure, Features: It comprises a composite current collector (1) and a conductive layer (2), wherein the conductive layer (2) is located on two opposite sides of the composite current collector (1); The elongation of the conductive layer (2) is less than the elongation of the composite current collector (1); The composite current collector (1) comprises a first metal layer (11), a polymer layer (13) and a second metal layer (12) stacked in sequence.

2. The pole piece structure according to claim 1, Features: The thickness of the first metal layer (11) and the thickness of the second metal layer (12) are respectively smaller than the thickness of the polymer layer (13).

3. The pole piece structure according to claim 1, Features: The elongation of the conductive layer (2) is 0.6% to 0.8%.

4. The pole piece structure according to claim 1, Features: The thickness of the conductive layer (2) is 0.5 μm to 5 μm.

5. The pole piece structure according to claim 1, Features: The resistivity of the conductive layer (2) is not greater than 3Ω·m.

6. The pole piece structure according to any one of claims 1 to 5, Features: An active material layer (3) is arranged on a surface of the conductive layer (2) away from the composite current collector (1), and the thickness of the conductive layer (2) is not greater than the thickness of the active material layer (3).

7. The pole piece structure according to claim 6, Features: The conductive layer (2) contains carbon-based conductive particles.

8. The pole piece structure according to claim 7, Features: The active material layer (3) comprises active particles, and the particle size ratio of the carbon-based conductive particles to the active particles is not greater than 0.

2.

9. A battery, Features: Comprising the pole piece structure as claimed in any one of claims 1 to 8.

10. An electrical device, Features: Comprising the battery as claimed in claim 9.

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