Positive and negative pole piece structure of lithium ion battery and battery

Abstract

The utility model relates to the technical field of battery manufacturing, in particular to a lithium ion battery positive and negative pole piece structure and a battery. According to the utility model, the internal resistance of the battery can be effectively reduced by about 35%-60%, so that the 1C discharge capacity of the battery is improved by 20%-50% on the original basis, and the 1C cycle performance of the battery is improved by 10% on the original basis. The solar cell comprises a current collector, an active material layer, an empty foil area and the like, according to the positive pole piece and the negative pole piece, two surfaces of a current collector are coated with active material layers with specific sizes in an extrusion coating mode, an empty foil area with a certain size is reserved in the relative middle position of the whole pole piece by changing an existing coating mode, and the empty foil areas reserved by the positive pole piece and the negative pole piece are different and have certain dislocation difference. Therefore, the internal resistance of the battery can be effectively reduced by about 35%-60%, the 1C discharge capacity of the battery is improved by 20%-50% on the original basis, and the 1C cycle performance of the battery is improved by 10% on the original basis.

Description

Technical Field

[0001] The utility model relates to the technical field of battery manufacturing, in particular to a lithium ion battery positive and negative electrode sheet structure and a battery. Background Art

[0002] Lithium-ion battery is a kind of energy storage device. Since its birth in the 1990s, its application has extended to every corner of our lives. With the advancement of science and technology and the rapid development and application of smart phones, tablet computers, notebooks, two-wheeled vehicles, and portable energy storage, new requirements have been put forward for the performance of lithium-ion batteries, requiring higher capacity and better cycle performance under the same volume conditions, and meeting fast charging and discharging (charging performance 1-5C, discharging performance 1-10C). In the existing pole piece design structure, the pole ear is usually welded to the empty foil area at both ends of the current collector aluminum foil or copper foil. This design makes it necessary for electron transmission to cross a longer distance from the pole piece end to the pole ear end or from the pole ear end to the pole piece end during the charging and discharging process when the electrode piece exceeds 1m, thereby increasing the battery ohmic resistance, reducing the battery charging and discharging efficiency, and the battery capacity cannot be fully utilized. The charging and discharging cycle performance of currents above 0.8C will be affected, and the battery temperature rise will also increase. Excessive temperature rise will affect the battery cycle performance. Therefore, it is necessary to develop a new design solution to solve the deficiencies in the existing technology. Utility Model Content

[0003] In view of this, the utility model provides a lithium-ion battery positive and negative electrode sheet structure and a battery, which can effectively reduce the internal resistance of the battery by about 35%-60%, so that the battery 1C discharge capacity is increased by 20%-50% on the original basis and the battery 1C cycle performance is improved by 10% on the original basis.

[0004] The technical solution is: a lithium-ion battery positive and negative electrode sheet structure and a battery, composed of positive and negative electrode sheets and tabs, the electrode sheets contain a current collector and an active material layer coated on the surface of the current collector; and empty foil areas of a certain size range are left vacant on two surfaces of the relatively middle part of the current collector by extrusion coating, and strict size range control is performed, the positive and negative electrode tabs are welded to the empty foil areas respectively, the CPP lower root alloy is connected to the current collector by spot welding, laser welding, and ultrasonic welding, and the CPP upper root alloy is connected to the external protection circuit (protection plate, wire, etc.).

[0005] Furthermore, the positive electrode current collector is aluminum alloy or coated aluminum alloy.

[0006] Furthermore, the negative electrode sheet current collector is a copper alloy, a coated copper alloy, or a composite current collector.

[0007] Furthermore, the active material layer is a positive electrode active material layer or a negative electrode active material layer.

[0008] Furthermore, the positive electrode of the tab metal alloy is an aluminum alloy, and the negative electrode is a combination of nickel or copper-plated nickel alloy and CPP insulating glue, collectively referred to as tabs.

[0009] The beneficial effects are as follows: the positive and negative electrode sheets in the utility model are coated with active material layers of specific sizes on the two surfaces of the current collector by extrusion coating, and by changing the existing coating method, a certain size of empty foil area is reserved in the relative middle position of the entire electrode sheet. The empty foil areas reserved by the positive and negative electrode sheets are different, and there is a certain misalignment difference, so as to ensure that the negative electrode active material layer can 100% cover the positive electrode active material layer. At the same time, the welding position of the pole ear is adjusted to the position of the empty foil area, and the positive and negative electrode sheets and the diaphragm are stacked and wound in sequence to form a battery, which can effectively reduce the internal resistance of the battery by about 35%-60%, so that the 1C discharge capacity of the battery is increased by 20%-50% on the original basis, and the capacity attenuation rate of the battery 1C cycle performance is increased by 10% on the original basis. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a schematic diagram of the top view of the positive electrode sheet of the utility model.

[0011] Figure 2 It is a schematic diagram of the cross-sectional structure of the positive electrode sheet of the utility model.

[0012] Figure 3 It is a schematic diagram of the top view of the negative electrode sheet of the utility model.

[0013] Figure 4 It is a schematic diagram of the cross-sectional structure of the negative electrode sheet of the utility model.

[0014] Figure 5 This is a comparison chart of the battery internal resistance of the utility model solution and the conventional structure solution.

[0015] Figure 6 This is a comparison chart of the battery 1C rate of the utility model solution and the conventional structure solution.

[0016] Figure numbers: 1_current collector, 2_active material layer, 3_CPP, 4_ear metal alloy, W1 / W2_ear welding empty foil area. DETAILED DESCRIPTION

[0017] The utility model is further described below in conjunction with the accompanying drawings and embodiments.

[0018] Embodiment 1: A lithium-ion battery positive and negative electrode structure and a battery, such as Figure 1-Figure 4As shown, it includes a current collector 1, an active material layer 2, CPP3, a tab metal alloy 4 and a tab welding empty foil area W1 / W2. In the utility model, the positive and negative electrode sheets are coated with an active material layer 2 of a certain size and surface density on both surfaces of the current collector 1 along the thickness direction; the current collector 1 is provided with empty foil areas W1 and W2 at a relatively middle position, wherein the size range of the positive electrode sheet W1 is 30-120mm, and the size range of W2 is 40-160mm. In addition, the size range of the negative electrode sheet W1 is 10-40mm, and the size range of W2 is 20-140mm. The empty foil area W1 / W2 is welded to the tab CPP3 (thickness size range is 0.15-0.25mm, length size range is 10-20mm, width size range is 4-7mm) and the tab metal alloy 4 (width size range is 4-20mm), and the above size ranges are preferably selected according to actual conditions.

[0019] The positive and negative electrodes are combined with a diaphragm, an aluminum-plastic film, and an electrolyte to make a battery. This technical solution can effectively improve the battery's charge and discharge efficiency, reduce the battery's internal resistance, increase the battery's high-current charge and discharge life, reduce the temperature change on the battery's surface, and improve the battery's low-temperature discharge performance.

[0020] In the present invention, the current collector 1 is a positive electrode current collector or a negative electrode current collector; the active material layer 2 is a positive electrode active material layer or a negative electrode active material layer; the tab is a general term for CPP3 and a tab metal alloy 4, wherein the positive electrode current collector is an aluminum alloy, a coated aluminum alloy, and has a thickness of 12-16um, and the negative electrode current collector is a copper alloy, a coated copper alloy, or a composite current collector, and has a thickness of 4.5-8um; the positive electrode tab is an aluminum alloy and CPP, and the negative electrode tab is copper, copper-plated nickel, and CPP; the single-sided surface density of the positive electrode active material layer is The active material is a metal compound containing lithium and sodium, such as lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium iron phosphate, lithium manganese oxide, lithium iron manganese phosphate, sodium oxide, etc. and matching PVDF, PAA, SP, CNTs, etc. The single-sided surface density of the negative electrode active material layer is 6.5-11.5 mg / cm3. The active material is mainly carbon material or silicon material, such as graphite, hard carbon, silicon-carbon alloy, etc. and matching CMC, SP, SBR, modified PAA.

[0021] In the utility model, the pole ear comprises CPP3 and a pole ear metal alloy 4. The pole ear metal alloy 4 at the lower root of CPP is connected to the current collector by spot welding, laser welding or ultrasonic welding, and the pole ear metal alloy 4 at the upper root of CPP is connected to an external protection circuit (protection plate, wire, etc.).

[0022] The battery composed of the positive and negative electrode sheets combined with the diaphragm, the aluminum-plastic film and the electrolyte of the utility model can reduce the internal resistance of the battery.

[0023] In the present invention, soft-pack lithium ion 126280-10000 is also tested in the same production environment, wherein the first scheme is a soft-pack lithium ion battery with the pole ear in the middle of the pole piece, and the second scheme is a soft-pack lithium ion battery with a conventional structure (the pole ear is at the head of the pole piece). The surface density of the two sets of pole pieces is the same as that of other designs. The results show that the scheme of the present invention is more effective. Figure 5-6 shown.

[0024] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A lithium-ion battery positive and negative electrode sheet structure and a battery, characterized in that: It includes positive and negative electrode sheets and tabs. The sheet includes a current collector and an active material layer coated on the surface of the current collector. Empty foil areas of a certain size range are left on the two surfaces of the relatively middle part of the current collector by extrusion coating, and the size range is strictly controlled. The positive and negative electrode tabs are welded respectively in the empty foil areas. The alloy at the lower root of CPP is connected to the current collector by spot welding, laser welding, and ultrasonic welding. The alloy at the upper root of CPP is connected to the external protection circuit, protection plate and wire.

2. A lithium-ion battery positive and negative electrode sheet structure and battery according to claim 1, characterized in that: The active material layer is a positive electrode active material layer or a negative electrode active material layer.

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