Battery pole piece and battery

Abstract

The utility model provides a composite foil. The composite foil comprises a polymer supporting layer, a first metal conducting layer and a second metal conducting layer, wherein the polymer supporting layer is provided with a first surface and a second surface which are oppositely arranged; the first metal layer is located on the first surface of the polymer supporting layer; the second metal layer is located on the second surface of the polymer supporting layer; the first metal conductive layer is constructed into a copper foil; the second metal conductive layer is made of aluminum foil. According to the battery disclosed by the utility model, the low-melting-point polymer supporting layer is arranged in the composite current collector, and when the temperature of the battery is too high and is higher than the melting point of the low-melting-point polymer supporting layer, the low-melting-point polymer supporting layer is melted, so that a fault contact point of the copper-aluminum current collector is wrapped by a high polymer material, and the current collector has a function of blocking electron transmission; and the needling safety performance of the battery cell is greatly improved, and the lithium battery only smokes without firing.

Description

Technical Field

[0001] The present invention relates to the field of lithium-ion batteries, and in particular to a composite foil, a pole piece and a battery. Background Art

[0002] Lithium-ion batteries, due to their high specific energy, stable performance, low self-discharge rate, and environmental friendliness, are widely used in a variety of products, from consumer electronics such as mobile phones and laptops to transportation vehicles such as electric vehicles. However, as lithium-ion batteries gain widespread use, their safety concerns are becoming increasingly prominent. In recent years, safety incidents caused by thermal runaway of lithium-ion batteries have been frequently reported. Most of these incidents are caused by sharp objects puncturing the battery casing. Due to the insufficient strength of the battery's current collector, this puncture easily compromises the safety of the lithium-ion battery and can lead to safety issues. Utility Model Content

[0003] The present invention aims to provide a composite foil, an electrode sheet, and a battery to address the technical problem of insufficient current collector strength in existing batteries, which is prone to safety accidents. The present invention provides a composite foil, comprising: a polymer support layer, a first metal conductive layer, and a second metal conductive layer; wherein the polymer support layer has a first surface and a second surface disposed opposite each other; the first metal layer is located on the first surface of the polymer support layer; the second metal layer is located on the second surface of the polymer support layer; the first metal conductive layer is constructed as copper foil; and the second metal conductive layer is constructed as aluminum foil.

[0004] Furthermore, the thickness of the polymer support layer is H1, wherein 4.5 μm≤H1≤10 μm.

[0005] Furthermore, the thickness of the first metal conductive layer is H2, wherein 1 μm≤H2≤10 μm.

[0006] Furthermore, the thickness of the second metal conductive layer is H3, wherein 1 μm≤H2≤15 μm.

[0007] Furthermore, the polymer support layer is made of PP or PET material.

[0008] Furthermore, the first metal conductive layer is connected to the polymer support layer by nano-riveting.

[0009] Furthermore, the second metal conductive layer is connected to the polymer support layer through a three-dimensional conductive repair method.

[0010] On the other hand, the present invention provides a battery electrode, comprising the composite foil, wherein the surface of the first metal layer away from the polymer support layer is coated with a positive electrode material, and the surface of the second metal layer away from the polymer support layer is coated with a negative electrode material.

[0011] On the other hand, the present invention also provides a battery comprising the above-mentioned battery electrode.

[0012] The battery of the utility model arranges a low-melting-point polymer support layer inside the composite current collector. When the battery temperature is too high and higher than the melting point of the low-melting-point polymer support, the low-melting-point polymer support layer melts, causing the polymer material to wrap the copper-aluminum current collector fault contact points. The current collector has the function of blocking electron transmission, greatly improving the acupuncture safety performance of the battery cell, and ensuring that the lithium battery only smokes but does not catch fire. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a schematic structural diagram of the composite foil of the present utility model;

[0014] Figure 2 A schematic diagram of a battery electrode made of the composite foil of the present invention;

[0015] Figure 3 This is a schematic diagram of a battery electrode made of the composite foil material of the present invention being used in a battery. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0017] like Figure 1-3 As shown, a schematic diagram of a composite foil and a battery electrode provided by an embodiment of the present invention, a composite foil, comprising: a polymer support layer 20, a first metal conductive layer 21, and a second metal conductive layer 22; wherein the polymer support layer 20 has a first surface and a second surface arranged opposite to each other; the first metal conductive layer 21 is located on the first surface of the polymer support layer 20; the second metal conductive layer 22 is located on the second surface of the polymer support layer 20; the first metal conductive layer 21 is constructed as copper foil; the second metal conductive layer 22 is constructed as aluminum foil.

[0018] The thickness of the polymer support layer 20 can be adjusted as needed, for example, it can be 4.5μm to 10μm. If the polymer support layer 20 is too thin, it will easily lead to a decrease in various indicators such as the strength of the polymer support layer. If the polymer support layer 20 is too thick, it will easily lead to an increase in the weight and thickness of the lithium battery, thereby indirectly reducing the energy density of the lithium battery. The polymer support layer 20 is made of a polymer material, such as PP, PI, PET, or PVDF. When the composite foil in this embodiment is used in a lithium battery, when the lithium battery is punctured, heat accumulates, and the polymer support layer 20 is more likely to melt, thereby cutting off the current circuit and preventing further thermal effects of the lithium battery, thereby preventing fire and combustion.

[0019] The thickness of the first metal conductive layer 21 can be adjusted as needed, for example, from 1μm to 10μm. A first metal conductive layer 21 that is too thick will increase the production cost of the battery, while a first metal conductive layer that is too thin will easily be punctured, which will affect battery performance. The first metal conductive layer 21 is made of copper foil and is connected to the polymer support layer by nano-riveting. A positive electrode material 23 is coated on a surface of the first metal conductive layer away from the polymer support layer. The positive electrode material mainly includes a main material such as lithium nickel cobalt manganese oxide and lithium iron phosphate, a conductive agent, and a binder.

[0020] The thickness of the second metal conductive layer 22 can be adjusted as needed, for example, it can be 1μm to 15μm. If the second metal conductive layer is too thick, it will increase the production cost of the battery. If the second metal conductive layer 22 is too thin, it will be easily punctured, resulting in a decrease in battery performance. The second metal conductive layer 22 is made of aluminum foil and is connected to the polymer support layer through a three-dimensional conductive repair method. A negative electrode material 24 is coated on a surface of the second metal conductive layer 22 away from the polymer support layer 20. The negative electrode material mainly includes graphite, a conductive agent, and a binder.

[0021] The following combination Figure 1-Figure 3 , describes in detail how the composite foil in the embodiment of the utility model is made into battery pole pieces and the steps of making corresponding batteries.

[0022] Step S1: Select a polymer material as the base material of the polymer support layer 20, such as PP or PET, and use an integrated nano-riveting method to plate copper foil on the surface of the polymer support layer, and plate aluminum foil on the other surface of the polymer support layer 20; of course, optionally, three-dimensional conductive repair can also be used, that is, a layer of copper foil is plated on the surface of the polymer support layer, and a layer of aluminum foil is plated on the other surface of the polymer support layer; in the process of electroplating copper foil and aluminum foil, ensure that the layer thickness of copper foil and aluminum foil is uniform, thereby forming a composite foil material with stable performance.

[0023] Step S2: Treat the surface of the composite foil, coat the negative electrode material on the side of the copper foil away from the polymer support layer, and coat the positive electrode material on the side of the aluminum foil away from the polymer support layer; then die-cut the composite foil into pole pieces according to the specific size of the battery to form stackable composite foil pole pieces.

[0024] Step S3: According to the design of the lithium battery cell, the composite foil electrode sheets and the diaphragm 30 are stacked into a bare battery cell, and the composite foil electrode sheets are connected at different positions to extend the copper foil to form the negative electrode ears and the aluminum foil to form the positive electrode ears; the stacking order of the composite foil electrode sheets is positive electrode material-diaphragm-negative electrode material, ensuring that the positive electrode material and the negative electrode material correspond to each other on both sides of the diaphragm 30, until the bare battery cell stacking is completed.

[0025] Step S4: The bare composite foil cell is subjected to welding, packaging, liquid injection, chemical formation, secondary sealing and capacity division to obtain a finished cell.

[0026] The composite foil material of this utility model overcomes the functional limitations of traditional current collectors. The conductive layer cracks and delaminates under stress at the short-circuit point, or melts instantly when a high short-circuit current is generated, quickly severing the short-circuit current loop. The support layer melts and contracts at the short-circuit point due to heat, causing a partial collapse of the current collector structure. This interrupts the short-circuit current loop before thermal runaway occurs, significantly improving the battery cell's needle puncture safety. When a steel needle pierces a copper-aluminum composite foil battery, a short-circuit channel forms between the positive and negative electrodes, generating heat. Once the temperature of the copper-aluminum composite foil electrode reaches a set temperature range, the polymer support layer, made of a polymer with a low melting point, melts first, causing the copper-aluminum current collector wrapped by the polymer support layer to break contact, thereby blocking current flow. This battery incorporates a low-melting-point polymer support layer within the composite current collector. When the battery temperature is excessively high and exceeds the melting point of the low-melting-point polymer support layer, the low-melting-point polymer support layer melts, causing the polymer material to break contact at the copper-aluminum current collector, effectively blocking electron transmission. This significantly improves the battery cell's needle puncture safety, ensuring that the lithium battery only smokes but does not catch fire.

[0027] The above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention and are not intended to limit the implementation methods of the present invention. A person skilled in the art will be able to make other variations or modifications based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A battery pole piece, characterized in that: include: A polymer support layer, a first metal conductive layer, and a second metal conductive layer; wherein the polymer support layer has a first surface and a second surface arranged opposite to each other; the first metal conductive layer is located on the first surface of the polymer support layer; the second metal conductive layer is located on the second surface of the polymer support layer; the first metal conductive layer is constructed as copper foil; the second metal conductive layer is constructed as aluminum foil; the surface of the first metal conductive layer away from the polymer support layer is coated with a positive electrode material, and the surface of the second metal conductive layer away from the polymer support layer is coated with a negative electrode material; the first metal conductive layer is connected to the polymer support layer by nano-riveting; the second metal conductive layer is connected to the polymer support layer by three-dimensional conductive repair.

2. The battery electrode according to claim 1, wherein: The thickness of the polymer support layer is H1, wherein 4.5 μm≤H1≤10 μm.

3. The battery electrode according to claim 1, wherein: The thickness of the first metal conductive layer is H2, wherein 1 μm≤H2≤10 μm.

4. The battery electrode according to claim 1, wherein: The thickness of the second metal conductive layer is H3, wherein 1 μm≤H2≤15 μm.

5. The battery electrode according to claim 1, wherein: The polymer support layer is made of PP or PET material.

6. A battery, characterized in that: Comprising the battery pole piece according to any one of claims 1-5.

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