A battery cell with a fusible micropore array structure

Abstract

This utility model discloses a battery cell with a fusible micropore array structure, including a positive aluminum foil and a negative copper foil. Both the positive and negative aluminum foils have micropore arrays extending through their thickness direction. These micropore arrays form weakened regions along the current conduction path. When the current is overloaded, the weakened regions can melt due to Joule heat accumulation, thus cutting off the current. Therefore, auxiliary designs such as a gradient decreasing density distribution along the electrode tab axis on the positive aluminum foil and negative copper foil enable the weakened regions to melt due to Joule heat accumulation when the current is overloaded, thereby cutting off the energy supply from the internal current conduction path of the cell. This structural intervention solves the problems of slow response, sacrificed battery performance, and inability to fundamentally prevent the spread of thermal runaway in existing technologies, achieving rapid protection in the initial stage of thermal runaway and improving battery safety.

Description

Technical Field

[0001] This utility model relates to the field of battery cell technology, and in particular to a battery cell with a fusible micropore array structure. Background Technology

[0002] With the rapid development of the new energy industry, lithium-ion batteries have been widely used in electric vehicles, energy storage equipment and other fields due to their advantages such as high energy density and good cycle performance. At present, battery safety is a key factor restricting its further development. Among them, thermal runaway is one of the most serious safety hazards. In the existing technology, the measures commonly used to prevent battery thermal runaway include setting up protection circuits (such as BMS battery management system) on the outside of the battery, using flame-retardant electrolyte, and adding temperature-sensitive materials inside the cell. These solutions mostly achieve safety protection by monitoring external battery parameters (such as voltage and temperature) or improving the flame-retardant performance of electrolyte / separator. The core idea is to delay the occurrence of thermal runaway through external intervention or passive defense.

[0003] However, existing technologies have significant limitations: the response speed of external protection circuits is limited by the accuracy of sensor monitoring and signal transmission delay, making it difficult to respond to extreme situations such as sudden short circuits within milliseconds; while flame-retardant electrolytes can reduce the risk of combustion, they sacrifice the electrochemical performance of the battery; the trigger threshold of temperature-sensitive materials is difficult to accurately match the critical temperature of thermal runaway under different operating conditions, and protection may fail due to material aging; in addition, none of the above solutions address the structural design of the current conduction path inside the cell, making it impossible to actively cut off the energy supply in the initial stage of thermal runaway (when the current surges abnormally), and thus difficult to prevent the spread of thermal runaway from the root. Utility Model Content

[0004] This utility model aims to at least partially solve one of the technical problems in the related art.

[0005] Therefore, the purpose of this utility model is to propose a battery cell with a fusible micropore array structure. A micropore array penetrating the thickness direction is set on the positive aluminum foil and negative copper foil of the battery to form a weakening region. When the current is overloaded, the weakening region melts due to the accumulation of Joule heat to cut off the current. Starting from the design of the current conduction path structure inside the cell, the energy supply is actively cut off in the initial stage of thermal runaway, which solves the problems of slow response, sacrifice of battery performance and inability to prevent the spread of thermal runaway in the prior art.

[0006] To achieve the above objectives, this utility model proposes a battery cell with a fusible micropore array structure, including a positive aluminum foil and a negative copper foil. Both the positive aluminum foil and the negative copper foil are provided with a micropore array that extends through their thickness direction. The micropore array forms a weakened region on the current conduction path. When the current is overloaded, the weakened region can melt due to the accumulation of Joule heat to cut off the current.

[0007] This invention relates to a battery cell with a fusible micropore array structure. A micropore array penetrating the thickness direction is formed on the positive aluminum foil and negative copper foil of the battery, creating a weakened region along the current conduction path. The micropore array's structural design, including optimization of parameters such as pore size, pore density, tapered pore structure, and cross-sectional area reduction rate, along with auxiliary designs such as micropores on the active coatings of the positive aluminum foil and negative copper foil that match the micropore array's position, low-melting-point metal filling the micropores, plasma passivation treatment of the micropore array's pore edges, and a gradient decreasing density distribution of the micropore array along the electrode tab axis on the positive aluminum foil and negative copper foil, ensures that the weakened region melts due to Joule heat accumulation during current overload, thus cutting off the current. This actively cuts off the energy supply from the internal current conduction path of the cell. By intervening at the structural source, this invention solves the problems of slow response, sacrificed battery performance, and inability to fundamentally prevent the spread of thermal runaway in existing technologies, achieving rapid protection in the initial stage of thermal runaway and improving battery safety.

[0008] In addition, the battery cell with a fusible micropore array structure proposed above according to this utility model may also have the following additional technical features:

[0009] Specifically, the pore size of the micropore array is 10–200 μm.

[0010] Specifically, the pore density of the micropore array is 100 to 500 pores / cm².

[0011] Specifically, the micropores in the micropore array have a conical pore structure, and the cross-sections of the positive aluminum foil and the negative copper foil are funnel-shaped.

[0012] Specifically, the cross-sectional area reduction rate of the weakened region is 30% to 70%.

[0013] Specifically, the active coatings of the positive electrode aluminum foil and the negative electrode copper foil are respectively provided with micropores that match the positions of the micropore array, forming a three-level fusing layer, and the micropores are filled with low melting point metal.

[0014] Specifically, the edges of the micropore array are subjected to plasma passivation treatment.

[0015] Specifically, the distribution density of the micropore array on the positive aluminum foil and the negative copper foil decreases gradually along the electrode lug axis.

[0016] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0017] The above and / or additional aspects and advantages of this utility model will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, in which:

[0018] Figure 1 This is a schematic diagram of a battery cell with a fusible micropore array structure according to the present invention.

[0019] As shown in the figure:

[0020] 1. Positive electrode aluminum foil; 2. Negative electrode copper foil; 3. Micropore array. Detailed Implementation

[0021] The embodiments of this utility model are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this utility model, and should not be construed as limiting this utility model. Rather, the embodiments of this utility model include all variations, modifications, and equivalents falling within the spirit and scope of the appended claims.

[0022] The following description, in conjunction with the accompanying drawings, describes a battery cell with a fusible micropore array structure according to an embodiment of the present invention.

[0023] like Figure 1 As shown, the battery cell with a fusible micropore array structure in this embodiment of the present invention may include a positive aluminum foil 1 and a negative copper foil 2. Both the positive aluminum foil 1 and the negative copper foil 2 are provided with a micropore array 3 that extends through their thickness direction. The micropore array 3 forms a weakened region on the current conduction path. When the current is overloaded, the weakened region can melt due to the accumulation of Joule heat to cut off the current.

[0024] It should be noted that the positive aluminum foil 1 and negative copper foil 2 described in this embodiment are key current collectors of the battery cell. Their surfaces are pretreated to enhance the bonding force with the active material. The micropore array 3 is positioned to avoid the edge sealing area of ​​the electrode sheet, ensuring that the battery cell's encapsulation and sealing are not affected. At the same time, the distribution positions of the micropore array 3 on the positive and negative electrode foils are staggered to avoid the direct correspondence between the positive and negative electrodes, which could lead to a short circuit. Through this structural design, the current conduction efficiency during normal operation can be guaranteed, and the battery cell can quickly respond and achieve fuse protection in abnormal situations.

[0025] Furthermore, the pore size of the micropore array 3 is 10–200 μm.

[0026] It should be noted that the aperture range described in this embodiment is determined based on the current density requirements of different types of cells, such as cylindrical, square, and pouch cells. For cells with high discharge rate requirements, a smaller aperture of 10 to 50 μm can be selected to reduce the impact on normal current conduction. For energy-type cells, a larger aperture of 100 to 200 μm can be selected to enhance the fusing sensitivity. Furthermore, the aperture of the micropores on the same cell can be designed differently according to the current distribution characteristics of different regions, so that the fusing characteristics of the weakened area are more matched with the actual current carrying capacity.

[0027] Furthermore, the pore density of the micropore array 3 is 100–500 pores / cm².

[0028] It should be noted that the pore density range described in this embodiment was determined after comprehensively considering the mechanical strength of the current collector and the weakening effect. A high density distribution of 300 to 500 pores / cm² is used in the high current region near the electrode tab to enhance the melting response speed in this region. In the low current region at the edge of the electrode, a low density distribution of 100 to 200 pores / cm² is used to ensure the overall structural stability of the electrode. The pores are arranged in an equilateral triangle to make the current distribution more uniform and avoid false melting caused by local current concentration.

[0029] Furthermore, the micropores in the micropore array 3 are conical, and the cross-sections of the positive electrode aluminum foil 1 and the negative electrode copper foil 2 are funnel-shaped.

[0030] It should be noted that the conical hole structure described in this embodiment has its large end facing the active coating side and its small end facing the inside of the current collector. This design can reduce the risk of blockage when the active material is filled. At the same time, the conical structure causes the current to converge at the small end when the current passes through, which enhances the accumulation efficiency of Joule heat and accelerates the melting process. Furthermore, the ratio of the diameter of the large end to the small end of the conical hole is controlled between 1.5 and 3:1, which can ensure melting sensitivity without excessively weakening the mechanical strength of the current collector.

[0031] Furthermore, the cross-sectional area reduction rate of the weakened region is 30% to 70%.

[0032] It should be noted that the cross-sectional area reduction rate described in this embodiment refers to the ratio of the effective conductive area of ​​the micro-hole array region to the conductive area of ​​the region without micro-holes. For power cells, the reduction rate is controlled at 30% to 50% to meet the requirements of high current conduction, while for energy cells it is controlled at 50% to 70% to improve the reliability of fusing. By precisely controlling the reduction rate, the weakened area can maintain stable conduction under normal operating current, and fusing can be achieved within 10 to 100 milliseconds under overload conditions of 1.5 to 3 times the rated current.

[0033] Furthermore, both the active coating of the positive electrode aluminum foil 1 and the active coating of the negative electrode copper foil 2 are provided with micropores that match the position of the micropore array 3, forming a three-level fusing layer, and the micropores are filled with low melting point metal.

[0034] It should be noted that the three-level fusing layer described in this embodiment is the active coating microporous layer, the current collector microporous layer, and the filling low-melting-point metal layer. The low-melting-point metal is a bismuth-tin alloy with a melting point of 80-150℃. When the cell temperature rises abnormally, the low-melting-point metal melts first to form an insulating barrier layer. Combined with the material decomposition at the micropores of the active coating and the melting of the current collector, a multi-layer protection mechanism is formed. The diameter of the micropores on the active coating is 5-10 μm larger than the diameter of the corresponding micropores on the current collector, ensuring that the low-melting-point metal can be smoothly filled into the micropores of the current collector to achieve good contact.

[0035] Furthermore, the edges of the micropore array 3 are subjected to plasma passivation treatment.

[0036] It should be noted that the plasma passivation treatment described in this embodiment uses a mixture of argon and oxygen to form an oxide passivation layer with a thickness of 0.5 to 2 μm at the edge of the hole. This passivation layer can reduce burrs and stress concentration at the edge of the hole, reduce hole edge corrosion caused by electrochemical reactions during normal charging and discharging, and avoid local overheating caused by tip discharge effect, making the melting characteristics of the micro-hole array 3 more stable and extending the cycle life of the battery cell.

[0037] Furthermore, the distribution density of the micropore array 3 on the positive electrode aluminum foil 1 and the negative electrode copper foil 2 decreases gradually along the electrode lug axis.

[0038] It should be noted that the gradient decrease described in this embodiment refers to the change in micropore density from the tab connection to the end of the electrode at a rate of 50 to 100 pores / cm² per centimeter. This design matches the distribution law of the current in the cell gradually decreasing from the tab to the end, so that the weakening degree of each region of the electrode is consistent with the actual current carrying capacity, avoiding the problems of accidental melting in non-high current regions and untimely melting in high current regions. The transition region of the gradient change adopts a smooth curve transition to reduce the uneven current distribution caused by structural abrupt changes.

[0039] In summary, the battery cell with a fusible micropore array structure of this utility model embodiment has a micropore array 3 extending through the thickness direction on the positive aluminum foil 1 and the negative copper foil 2 of the battery, forming a weakened region on the current conduction path. The structural design of the micropore array 3, including optimization of parameters such as pore size, pore density, conical pore structure, and cross-sectional area reduction rate, as well as auxiliary designs such as micropores on the active coatings of the positive aluminum foil 1 and the negative copper foil 2 corresponding to the positions of the micropore array 3, low-melting-point metal filling the micropores, plasma passivation treatment of the pore edges of the micropore array 3, and a gradient decreasing density distribution of the micropore array 3 along the electrode tab axis on the positive aluminum foil 1 and the negative copper foil 2, allows the weakened region to melt due to Joule heat accumulation during current overload, thus cutting off the current. This actively cuts off the energy supply from the current conduction path inside the cell. Through this structural intervention, the problems of slow response, sacrificed battery performance, and inability to fundamentally prevent the spread of thermal runaway in existing solutions in the background art are solved, achieving rapid protection in the initial stage of thermal runaway and improving battery safety.

[0040] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A battery cell with a fusible micropore array structure, characterized in that, It includes a positive aluminum foil (1) and a negative copper foil (2). Both the positive aluminum foil (1) and the negative copper foil (2) are provided with a micropore array (3) that runs through their thickness direction. The micropore array (3) forms a weakened region on the current conduction path. When the current is overloaded, the weakened region can melt due to the accumulation of Joule heat to cut off the current.

2. The battery cell with a fusible micropore array structure according to claim 1, characterized in that, The pore size of the micropore array (3) is 10-200 μm.

3. The battery cell with a fusible micropore array structure according to claim 1, characterized in that, The pore density of the micropore array (3) is 100 to 500 pores / cm².

4. The battery cell with a fusible micropore array structure according to claim 1, characterized in that, The micropores of the micropore array (3) are conical, and the cross-sections of the positive aluminum foil (1) and the negative copper foil (2) are funnel-shaped.

5. The battery cell with a fusible micropore array structure according to claim 1, characterized in that, The cross-sectional area reduction rate of the weakened region is 30% to 70%.

6. The battery cell with a fusible micropore array structure according to claim 1, characterized in that, The active coatings of the positive electrode aluminum foil (1) and the negative electrode copper foil (2) are respectively provided with micropores that match the positions of the micropore array (3) to form a three-level fusing layer, and the micropores are filled with low melting point metal.

7. The battery cell with a fusible micropore array structure according to claim 1, characterized in that, The edges of the micropore array (3) are plasma passivated.

8. The battery cell with a fusible micropore array structure according to claim 1, characterized in that, The distribution density of the micropore array (3) on the positive electrode aluminum foil (1) and the negative electrode copper foil (2) decreases gradually along the electrode lug axis.

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