Lithium battery positive and negative electrode composite metal foil current collector structure

Abstract

The utility model discloses a lithium battery positive and negative electrode composite metal foil current collector structure which comprises a composite metal foil which comprises a first outer metal layer, a second outer metal layer and an inner polymer film layer fixedly clamped between the first outer metal layer and the second outer metal layer. Fuse structures are arranged on the first outer metal layer and the second outer metal layer at intervals, the fuse structures divide the first outer metal layer and the second outer metal layer into external connection areas, isolation areas, current collecting areas and fuses, and the external connection areas are used for collecting current in the current collecting areas and are connected with battery terminals. According to the lithium battery positive and negative electrode composite metal foil current collector structure, the short-circuit current threshold value when internal short circuit happens to the two electrode plates can be reduced, the short-circuit area is isolated outside a loop, and meanwhile damage to the positive electrode and the negative electrode caused by external short circuit is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of lithium batteries, in particular to a positive and negative composite metal foil current collector structure of a lithium battery. Background Art

[0002] Existing data show that the use of composite metal foil as the positive and negative current collectors of lithium batteries has a significant effect on improving the safety of lithium batteries. The principle is that when the positive and negative electrodes of the lithium battery are short-circuited, the polymer material in the composite copper foil melts and causes the two poles to be short-circuited, which greatly reduces the exothermic reaction.

[0003] When the battery is at the end of discharge or a large needle is inserted, the short-circuit current is not enough to melt the polymer material at the damaged part, resulting in the continuous occurrence of short-circuit reaction, and the heat accumulation will inevitably cause thermal runaway. In addition, the composite metal foil has no obvious protective effect against external short circuits. Utility Model Content

[0004] In view of this, the utility model proposes a lithium battery positive and negative composite metal foil current collector structure to reduce the short-circuit current threshold when an internal short circuit occurs in the two poles, isolate the short-circuit area outside the loop, and reduce the damage caused by external short circuit to the positive and negative electrodes.

[0005] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0006] A lithium battery positive and negative electrode composite metal foil current collector structure comprises a composite metal foil, wherein the composite metal foil comprises a first outer metal layer, a second outer metal layer and an inner polymer film layer fixedly clamped between the first outer metal layer and the second outer metal layer, wherein the first outer metal layer and the second outer metal layer are both arranged at intervals and provided with a fuse structure, wherein the fuse structure separates the first outer metal layer and the second outer metal layer into an external connection area, an isolation area, a current collecting area and a fuse, wherein the external connection area is used to aggregate the current in each current collecting area and is connected to a battery terminal.

[0007] To better implement the above technical solution, optionally, the fuse structure is a hollow T-shaped structure, the first outer metal layer and the second outer metal layer form an external connection area above the fuse structure, a collecting area is surrounded by adjacent hollow T-shaped structures, a fuse is formed between the ends of adjacent hollow T-shaped structures, and an isolation area is formed in each hollow T-shaped structure.

[0008] Optionally, the first outer metal layer and the second outer metal layer are a single-layer structure or a multi-layer structure.

[0009] Optionally, the thickness of the first outer metal layer and the second outer metal layer is 0.5-5 μm.

[0010] Optionally, the inner polymer film layer is polypropylene or polyester.

[0011] Optionally, the thickness of the inner polymer film layer is 1 to 10 μm.

[0012] Optionally, the position where the inner polymer film layer and the hollow T-shaped structure are vertically opposite is an open structure.

[0013] Beneficial effects of the utility model:

[0014] The utility model discloses a lithium battery positive and negative electrode composite metal foil current collector structure. A fuse structure is prepared on a first outer metal layer, a second outer metal layer and an inner polymer film layer. When a metal needle pierces, a short circuit occurs at the two poles of the lithium battery. The fuse structure closest to the short circuit position will be blown first to isolate the short circuit area, thereby greatly reducing the heat release caused by the short circuit. When an external short circuit occurs in the lithium battery, the fuse structure connecting the external connection area and the current collector area will be blown, so that the current collector area is completely disconnected from the external connection area, which can greatly reduce the battery voltage and greatly improve the safety of the lithium battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a first three-dimensional schematic diagram of a lithium battery positive and negative electrode composite metal foil current collector structure according to an embodiment of the utility model;

[0016] Figure 2 This is a second three-dimensional schematic diagram of a lithium battery positive and negative electrode composite metal foil current collector structure according to an embodiment of the utility model;

[0017] Figure 3 Schematic diagram of the current collector state when a short circuit occurs inside the battery in the embodiment;

[0018] Figure 4 Schematic diagram of the current collector state when a short circuit occurs outside the battery in the embodiment;

[0019] Reference numerals:

[0020] A first outer metal layer 11 , an inner polymer film layer 12 , a second outer metal layer 13 , an external connection area 21 , an isolation area 22 , a current collecting area 23 , a fuse 24 , and a puncture damage area 30 . DETAILED DESCRIPTION

[0021] The technical solution of the utility model is described in detail below in conjunction with the accompanying drawings and specific embodiments, wherein the same components are represented by the same reference numerals.

[0022] See also Figures 1 to 4 The utility model embodiment discloses a lithium battery positive and negative electrode composite metal foil current collector structure, including a composite metal foil and a fuse structure.

[0023] like Figure 1and Figure 2 As shown, the composite metal foil includes a first outer metal layer 11, a second outer metal layer 13 and an inner polymer film layer 12 fixedly clamped between the first outer metal layer 11 and the second outer metal layer 13. The first outer metal layer 11, the inner polymer film layer 12 and the second outer metal layer 13 are stacked into an integrated structure.

[0024] Specifically, the first outer metal layer 11 and the second outer metal layer 13 are made of copper or aluminum, are single-layer or multi-layer structures, and have a thickness of 0.5 to 5 μm.

[0025] The inner polymer film layer 12 is made of polypropylene or polyester, and has a thickness of 1 to 10 μm.

[0026] like Figure 1 and Figure 2 As shown, the first outer metal layer 11 and the second outer metal layer 13 are both arranged at intervals and provided with fuse structures, which separate the first outer metal layer 11 and the second outer metal layer 13 into an external connection area 21, an isolation area 22, a current collecting area 23 and a fuse 24. The external connection area 21 is used to aggregate the current in each current collecting area 23 and connect it to the battery terminal.

[0027] Among them, the fuse structure is a hollow T-shaped structure, the first outer metal layer 11 and the second outer metal layer 13 form an external connection area 21 above the fuse structure, the adjacent hollow T-shaped structures form a collecting area 23, a fuse 24 is formed between the ends of the adjacent hollow T-shaped structures, and an isolation area 22 is formed in each hollow T-shaped structure.

[0028] In an optional embodiment of the utility model, the fuse structure may also be a hollow hammer structure, and the length of the fuse 24 is 1 to 5 mm, and the width is 0.5 to 5 mm, which can be adjusted according to actual use conditions.

[0029] like Figure 1 As shown, in an optional embodiment of the utility model, the hollow T-shaped structure can be prepared by an etching process. Specifically, the first outer metal layer 11 and the second outer metal layer 13 are etched to form a hollow T-shaped structure, and the integrity of the inner polymer film layer 12 can be retained. The fuse structure is prepared by etching, and the mechanical properties of the composite metal foil are basically retained.

[0030] like Figure 2As shown, in an optional embodiment of the utility model, the hollow T-shaped structure is prepared by a laser cutting process, and the position where the inner polymer film layer 12 and the hollow T-shaped structure are directly opposite to each other is an open structure. Specifically, the first outer metal layer 11, the inner polymer film layer 12, and the second outer metal layer 13 are removed as a whole by ultraviolet picosecond laser cutting to achieve the purpose of prefabricating the "fuse 24" structure. This method has a simple process, is easy to ensure processing accuracy, and is easy to automate and continuously produce.

[0031] See also Figure 3 When a needle-puncture damage area 30 occurs inside the battery, a short circuit occurs at the two poles of the battery. Since the internal resistance of the battery is extremely small, the short-circuit current increases rapidly and passes quickly through the needle-puncture damage area 30, generating a large amount of heat. If there is no "fuse 24" structure, the positive feedback of this thermal effect may cause thermal runaway. However, when the positive and negative electrode current collectors with a prefabricated "fuse 24" structure are used, the "fuse 24" structure will be overloaded when a large current passes through it. The fuse 24 that blows first will quickly isolate the damaged area and block the connection between the positive and negative electrodes, thereby greatly reducing the short-circuit current.

[0032] like Figure 4 As shown, when an external short circuit occurs in the battery, the instantaneous large current between the positive and negative electrodes will cause local overheating, thereby causing leakage, explosion, and spontaneous combustion of a battery cell, and triggering a chain reaction, resulting in more battery damage and thermal runaway. For the positive and negative electrode current collectors with a prefabricated "fuse 24" structure, when a short circuit occurs, the current from the current collecting area 23 to the external connection area 21 increases rapidly, and the fuse 24 that blows first will quickly isolate the current collecting area 23 and the external connection area 21, thereby reducing the battery voltage to less than 20%, which can avoid thermal runaway.

[0033] The utility model discloses a lithium battery positive and negative electrode composite metal foil current collector structure. A fuse structure is prepared on a first outer metal layer 11, a second outer metal layer 13 and an inner polymer film layer 12. When a metal needle is inserted, a short circuit occurs at the two poles of the lithium battery. The "fuse 24" structure closest to the short circuit position will be blown first to isolate the short circuit area, thereby greatly reducing the heat release caused by the short circuit. When an external short circuit occurs in the lithium battery, the "fuse 24" structure connecting the external connection area 21 and the current collector area 23 will be blown, so that the current collector area is completely disconnected from the external connection area 21, which can greatly reduce the battery voltage and greatly improve the safety of the lithium battery.

[0034] The technical solution of the utility model is described in detail above in combination with specific embodiments, and the described specific embodiments are used to help understand the concept of the utility model. Derivations and variations made by those skilled in the art based on the specific embodiments of the utility model also fall within the protection scope of the utility model.

Claims

1. A lithium battery positive and negative electrode composite metal foil current collector structure, characterized in that: The composite metal foil comprises a first outer metal layer (11), a second outer metal layer (13) and an inner polymer film layer (12) fixedly clamped between the first outer metal layer (11) and the second outer metal layer (13); the first outer metal layer (11) and the second outer metal layer (13) are both arranged at intervals and provided with fuse structures; the fuse structure separates the first outer metal layer (11) and the second outer metal layer (13) into an external connection area (21), an isolation area (22), a current collecting area (23) and a fuse (24); the external connection area (21) is used to collect the current in each current collecting area (23) and connect to a battery terminal.

2. A lithium battery positive and negative electrode composite metal foil current collector structure according to claim 1, characterized in that: The fuse structure is a hollow T-shaped structure, the first outer metal layer (11) and the second outer metal layer (13) form an external connection area (21) above the fuse structure, a current collecting area (23) is formed between adjacent hollow T-shaped structures, a fuse (24) is formed between the ends of adjacent hollow T-shaped structures, and an isolation area (22) is formed inside each hollow T-shaped structure.

3. A lithium battery positive and negative electrode composite metal foil current collector structure according to claim 1, characterized in that: The first outer metal layer (11) and the second outer metal layer (13) are single-layer structures or multi-layer structures.

4. A lithium battery positive and negative electrode composite metal foil current collector structure according to claim 3, characterized in that: The thickness of the first outer metal layer (11) and the second outer metal layer (13) is 0.5 to 5 μm.

5. A lithium battery positive and negative electrode composite metal foil current collector structure according to claim 1, characterized in that: The inner polymer film layer (12) is polypropylene or polyester.

6. A lithium battery positive and negative electrode composite metal foil current collector structure according to claim 5, characterized in that: The thickness of the inner polymer film layer (12) is 1 to 10 μm.

7. A lithium battery positive and negative electrode composite metal foil current collector structure according to claim 1, characterized in that: The position where the inner polymer film layer (12) and the hollow T-shaped structure face each other vertically is an open structure.

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