A high needle penetration rate of nickel-containing ternary lithium battery

Abstract

The utility model discloses a kind of high needle puncture pass rate's nickel-containing ternary lithium battery, including electric core, shell and electrolyte, electric core includes composite copper foil, composite aluminum foil, diaphragm, positive electrode coating and negative electrode coating;Diaphragm is located between composite copper foil and composite copper foil, and negative electrode coating is coated on composite copper foil;Positive electrode coating is coated on composite aluminum foil;Composite copper foil includes first high molecular base film and copper plating layer, and copper plating layer is respectively equipped on the both sides of first high molecular base film;The composite aluminum foil includes second high molecular base film and aluminum plating layer, and aluminum plating layer is respectively equipped on the both sides of second high molecular base film.The composite copper foil and composite aluminum foil with intermediate layer as high molecular film respectively coat positive electrode material and negative electrode material, by diaphragm winding into electric core, puncture body puncture instant puncture point temperature climbs to make composite copper foil, composite aluminum foil and puncture body form physical isolation zone, block the heat runaway departure condition, improve the needle puncture pass rate of electric core, improve the security of battery.

Description

Technical Field

[0001] This utility model belongs to the field of lithium battery testing, specifically relating to a nickel-containing ternary lithium battery with high needle penetration pass rate. Background Technology

[0002] With the global energy policy trend towards a strong transition to renewable energy, lithium batteries, as key energy storage and power devices, have received widespread and high attention. Currently, the market demand for lithium battery energy density is increasing daily, and to achieve this goal, the nickel content in cathode materials is constantly being increased. When using nickel-containing ternary materials, the cells face a significant risk of failure in nail penetration tests.

[0003] When a battery cell is punctured by a needle, an internal short circuit occurs immediately, generating a large amount of heat rapidly within a short period. Nickel-containing ternary materials have insufficient tolerance to high temperatures. Under such high temperatures, the stability of the ternary material is disrupted, rapidly undergoing a phase transition, and the previously stable structure undergoes severe changes. This structural change causes the high-nickel material to release oxygen, which in turn triggers a series of uncontrollable side reactions. These side reactions release even more heat, causing the cell temperature to rise sharply, forming a positive feedback loop that greatly exacerbates the risk of thermal runaway, posing a significant threat to the safety of lithium batteries. Once thermal runaway occurs, lithium batteries may experience serious consequences such as fires and explosions, potentially causing catastrophic impacts on both user safety and the surrounding environment in practical applications. Utility Model Content

[0004] This invention addresses the shortcomings of the prior art by providing a nickel-containing ternary lithium battery with high needle penetration rate. It utilizes composite copper foil or composite aluminum foil with a polymer film as the intermediate layer. After needle penetration, the polymer film melts and shrinks, forming a physical isolation zone between the battery cell and the puncture site, effectively suppressing short circuits.

[0005] The technical solution adopted in this utility model is as follows: A nickel-containing ternary lithium battery with high needle penetration rate includes a cell, a casing, and an electrolyte. The cell includes a composite copper foil, a composite aluminum foil, a separator, a positive electrode coating, and a negative electrode coating. The separator is located between the composite copper foil and the composite aluminum foil, and the negative electrode coating is applied to the end face of the composite copper foil facing the separator. The positive electrode coating is applied to the end face of the composite aluminum foil facing the separator. The composite copper foil includes a first polymer base film and a copper plating layer, with copper plating layers respectively provided on both sides of the first polymer base film. The composite aluminum foil includes a second polymer base film and an aluminum plating layer, with aluminum plating layers respectively provided on both sides of the second polymer base film. At the moment of puncture, the local current density surges to 10^3 times that of normal operating conditions. The Joule heating effect causes the temperature at the puncture point to rise at a rate of >50℃ / s to the critical point of 120-150℃. The first and second polymer base films melt and shrink at high temperatures. The shrinkage of the first and second polymer base films causes the composite copper foil and composite aluminum foil to shrink, forming a physical isolation zone of >200μm between them and the puncture body. This causes the short-circuit resistance to jump from the milliohm level to the kilohm level, effectively suppressing the short-circuit current to below 10mA / cm². The entire process can cut off the continuous heat generation path within 300ms, making it impossible to achieve the thermal runaway triggering conditions. Without affecting the high energy density of the battery cell, the needle penetration rate of the battery cell is significantly improved.

[0006] As a preferred embodiment of this utility model, the thickness of the first polymer base film is 4-8 μm; the thickness of the second polymer base film is 4-8 μm; the thickness of the copper plating layer is 1-2 μm; and the thickness of the aluminum plating layer is 1-2 μm.

[0007] As a preferred embodiment of the present invention, the first polymer base film and the second polymer base film are PE film, PET film or PP film.

[0008] This invention uses composite copper foil and composite aluminum foil with a polymer film as the middle layer to coat the positive electrode material and negative electrode material respectively to form a current collector. Then, it is wound into a battery cell through a separator. The temperature rises at the puncture point at the moment of puncture by the puncture body, which forms a physical isolation zone between the composite copper foil, composite aluminum foil and puncture body, blocking the conditions for thermal runaway, improving the needle penetration rate of the battery cell and enhancing the safety of the battery. Attached Figure Description

[0009] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0010] Figure 1 This is a schematic diagram of the needle-puncture battery cell disconnection according to this utility model. Detailed Implementation

[0011] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0012] Example: A nickel-containing ternary lithium battery with high needle penetration rate includes a cell, a casing, and an electrolyte. The cell includes a composite copper foil 1, a composite aluminum foil 2, a separator 3, a positive electrode coating 4, and a negative electrode coating 5. The separator 3 is located between the composite copper foil 1 and the composite aluminum foil 2, and the negative electrode coating 5 is coated on the end face of the composite copper foil 1 facing the separator 3. The positive electrode coating 4 is coated on the end face of the composite aluminum foil 2 facing the separator 3.

[0013] The composite copper foil 1 includes a first polymer base film 11 and a copper plating layer 12. The copper plating layer 12 is provided on both sides of the first polymer base film 11. The thickness of the first polymer base film 11 is 4-8 μm, preferably 4 μm, 5 μm, 6 μm, 7 μm, or 8 μm, and the first polymer base film 11 is a PE film, PET film, or PP film. The thickness of the copper plating layer 12 is 1-2 μm, preferably 1 μm or 2 μm.

[0014] The composite aluminum foil 2 comprises a second polymer base film 21 and an aluminum-plated layer 22, with the aluminum-plated layer 22 disposed on both sides of the second polymer base film 21. The thickness of the second polymer base film 21 is 4-8 μm, preferably 4 μm, 5 μm, 6 μm, 7 μm, or 8 μm, and the second polymer base film 21 is a PE film, PET film, or PP film; the thickness of the aluminum-plated layer 22 is 1-2 μm, preferably 1 μm or 2 μm.

[0015] At the moment of insertion of the puncture body 6, as Figure 1 As shown, the local current density surges to 10^3 times that of normal operating conditions. The Joule heating effect causes the temperature at the puncture point to rise to the critical point of 120-150℃ at a rate of >50℃ / s. The first polymer base film 11 and the second polymer base film 21 melt and shrink at high temperature. The shrinkage of the first polymer base film 11 and the second polymer base film 21 causes the composite copper foil and composite aluminum foil to shrink, forming a physical isolation zone of >200μm between them and the puncture body. This causes the short-circuit resistance to jump from the milliohm level to the kilohm level, effectively suppressing the short-circuit current to below 10mA / cm². The entire process can cut off the continuous heat generation path within 300ms, making it impossible to achieve the thermal runaway triggering conditions. Without affecting the high energy density of the battery cell, the needle penetration rate of the battery cell is significantly improved.

[0016] The following experimental examples and comparative examples verify the effectiveness of the proposed solution in improving the acupuncture pass rate.

[0017] Prepare positive and negative electrode slurries: ① Select nickel-cobalt-manganese ternary single crystal material (LiNixCoyMn1-x-yO2). To ensure the energy density of the cell, the proportion of X is less than 0.6. The negative electrode uses a conventional silicon-oxygen + graphite combination with cell raw materials such as SP and PVDF, and is made into a slurry in a certain proportion.

[0018] Preparation of positive and negative electrodes: ① The positive electrode slurry is coated onto a composite aluminum foil, and the polymer film of the composite aluminum foil is a PE film to prepare electrode A; the positive electrode slurry is coated onto a traditional aluminum foil to prepare electrode C. ② The negative electrode slurry is coated onto a composite copper foil, the polymer film of which is a PE film, to prepare electrode B; the negative electrode slurry is coated onto a traditional copper foil to prepare electrode D.

[0019] Battery cell trial production Option 1: Electrode A is wound together with electrode B and a separator to form a battery cell. The separator is an alumina-coated separator. Then, it is installed in the housing to form an experimental cylindrical battery cell. Electrolyte is injected, and an experimental lithium-ion battery is obtained through formation and aging processes.

[0020] Option 2: Electrode C is wound together with electrode D and separator to form a battery cell. The separator is an alumina-coated separator. Then, it is installed in the housing to form a comparative cylindrical battery cell. Electrolyte is injected, and a comparative lithium-ion battery is obtained through formation and aging processes.

[0021] The experimental lithium-ion batteries and the control lithium-ion batteries were subjected to nail penetration tests, and the results are shown in the table below: In this specification, the terms "an embodiment," "example," "specific example," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0022] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. A nickel-containing ternary lithium battery with high needle penetration rate, comprising a cell, a casing, and an electrolyte, characterized in that: The battery cell includes a composite copper foil (1), a composite aluminum foil (2), a separator (3), a positive electrode coating (4), and a negative electrode coating (5); the separator (3) is located between the composite copper foil (1) and the composite aluminum foil (2), and the negative electrode coating (5) is coated on the end face of the composite copper foil (1) facing the separator (3); the positive electrode coating (4) is coated on the end face of the composite aluminum foil (2) facing the separator (3); the composite copper foil (1) includes a first polymer base film (11) and a copper plating layer (12), and copper plating layers (12) are respectively provided on both sides of the first polymer base film (11); the composite aluminum foil (2) includes a second polymer base film (21) and an aluminum plating layer (22), and aluminum plating layers (22) are respectively provided on both sides of the second polymer base film (21).

2. The nickel-containing ternary lithium battery with high needle penetration rate according to claim 1, characterized in that: The thickness of the first polymer base film (11) is 4-8 μm; the thickness of the second polymer base film (21) is 4-8 μm; the thickness of the copper plating layer (12) is 1-2 μm; and the thickness of the aluminum plating layer (22) is 1-2 μm.

3. The nickel-containing ternary lithium battery with high needle penetration rate according to claim 2, characterized in that: The first polymer base film (11) and the second polymer base film (21) are PE film, PET film or PP film.

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