Dry-type filling process for positive and negative current collectors of lithium ion battery

Abstract

The invention discloses a lithium ion battery positive and negative current collector dry-type filling process, and relates to the technical field of lithium ion batteries, and the process comprises the following steps: 1, filling an active substance; the method comprises the following steps: firstly, preparing foamed positive and negative current collectors and dry active substances; placing the foamed positive and negative current collectors in positive and negative material filling equipment; active matters are fully embedded into the inner cavity of the current collector in a mechanical vibration or ultrasonic vibration mode; 2, preliminary rolling is carried out; and after filling is completed, rolling the foamed positive and negative electrode current collector. The original positive and negative active matters adhered to a foil type positive and negative current collector are changed into an embedded foaming type positive and negative current collector, so that the specific surface area is increased, the positive and negative active matters are fully contacted with the foaming type positive and negative current collector, the use amount of a conductive agent is reduced or canceled, the use amount of a binder is reduced, and the energy consumption is reduced; tedious steps such as early-stage stirring and the production cost are reduced.

Description

Technical Field

[0002] The present invention relates to the technical field of lithium-ion batteries, and more specifically, to a dry filling process for the positive and negative current collectors of lithium-ion batteries. Background Art

[0003] A lithium-ion battery is a secondary battery (rechargeable battery) that mainly operates by the movement of lithium ions between the positive and negative electrodes. During the charge and discharge process, Li+ intercalates and deintercalates between the two electrodes: during charging, Li+ deintercalates from the positive electrode, passes through the electrolyte, and intercalates into the negative electrode, making the negative electrode in a lithium-rich state; during discharging, the opposite occurs.

[0004] In the prior art, the positive and negative current collectors of lithium-ion batteries are generally made of foil materials, and the slurries for the positive and negative electrodes need to prepare a binder solution in advance. Among them, the binder solution is added with the positive and negative active materials and their conductive agents and stirred to prepare the positive and negative slurries. Then, the slurries are coated on the surface of the foil material by a coater, and finally dried and rolled, and then enter the next process. This process flow not only takes a long time, but also requires a large amount of material energy consumption. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a dry filling process for the positive and negative current collectors of lithium-ion batteries.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] A dry filling process for the positive and negative current collectors of lithium-ion batteries, comprising the following steps: Step 1: Filling of active materials First, prepare a foamed positive and negative current collector and dry active materials; place the foamed positive and negative current collector in a positive and negative material filling device; through mechanical vibration or ultrasonic vibration, make the active materials fully embed into the inner cavity of the current collector; Step 2: Preliminary rolling After the filling is completed, perform a preliminary rolling operation to make the surface positive and negative active materials closely fit with the outer surface of the foamed positive and negative current collector, and under the external pressure, remove the gas between the positive and negative active materials, reduce the gap between the active material particles, and make the active materials tightly embed into the inner cavity of the foamed positive and negative current collector; Step 3: Spraying and drying of the binder After the preliminary rolling is completed, clean the surface of the positive and negative electrode plates to remove possible impurities and dust, and then use a spraying device to evenly spray a layer of binder solution on the surface of the preliminarily rolled positive and negative electrode plates; after spraying, send the electrode plates into a drying device for drying treatment; the surface active materials are firmly bonded to the current collector; Step 4: Secondary rolling After drying is completed, the electrode sheets are sent to a roller press for secondary rolling to increase the compaction density of the active material and make the thickness and surface flatness of the electrode sheets meet the process requirements.

[0008] Preferably, the filling device can utilize mechanical vibration or ultrasonic vibration; during the vibration process, the dried active material will be fully filled into the cavities of the foamed positive and negative current collectors.

[0009] Preferably, the mechanical vibration can be controlled at 40 - 80 Hz, and the vibration time is 0.5 - 5 minutes; the ultrasonic vibration frequency is adjusted to 40 - 80 Hz, and the vibration time is 0.5 - 5 minutes.

[0010] Preferably, in step two, after confirming that the filling is completed, a preliminary rolling operation is carried out. The foamed positive and negative current collectors filled with the active material are sent into a roller press, and an external pressure is applied through the roller press to make the positive and negative active materials fully contact the inner cavities of the foamed positive and negative current collectors. As the pressure increases, the positive and negative active materials will be more tightly embedded into the inner cavities of the foamed positive and negative current collectors.

[0011] Preferably, during the rolling process, the rolling pressure and speed should be strictly controlled. The pressure is set at 5 - 50 MPa, and the rolling speed is maintained at 0.1 - 1 m / min.

[0012] Preferably, in step four, the pressure of the secondary rolling is adjusted to 10 - 100 MPa, and the rolling speed is 0.1 - 0.5 m / min.

[0013] Compared with the prior art, the present invention has the following beneficial effects: In the present invention, by changing the original positive and negative active materials from adhering to the foil - type positive and negative current collectors to being embedded in the foamed positive and negative current collectors, the specific surface area is increased, the positive and negative active materials are fully in contact with the foamed positive and negative current collectors, the amount of conductive agent used is reduced or eliminated, the amount of binder used is reduced, and the cumbersome steps such as pre - stirring and production costs are reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic flow chart of the dry filling process for the positive and negative current collectors of a lithium - ion battery proposed by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0015] Refer to Figure 1 。

[0016] Example 1 further illustrates the dry filling process for the positive and negative current collectors of the lithium - ion battery proposed by the present invention.

[0017] The dry filling process for the positive and negative current collectors of a lithium - ion battery includes the following steps: Step 1: Filling of active materials First, prepare a foamed current collector and dry active materials; place the foamed current collector in a material filling device; and through mechanical vibration or ultrasonic vibration, fully embed the active materials into the inner cavity of the current collector. Step 2: Preliminary rolling After the filling is completed, perform a preliminary rolling operation to closely fit the surface positive and negative active materials to the outer surface of the foamed positive and negative current collectors, and under an external pressure, remove the gas between the positive and negative active materials, reduce the gap between the active material particles, and tightly embed the active materials into the inner cavity of the foamed positive and negative current collectors. Step 3: Spraying and drying of binder After the preliminary rolling is completed, clean the surfaces of the positive and negative electrode plates to remove any possible impurities and dust, and then evenly spray a layer of binder solution on the surfaces of the preliminary rolled positive and negative electrode plates using a spraying device; after the spraying is completed, send the electrode plates into a drying device for drying treatment; the surface active materials are firmly bonded to the current collector. Step 4: Secondary rolling After the drying is completed, send the electrode plates into a rolling press for secondary rolling to increase the compaction density of the active materials and make the thickness and surface flatness of the electrode plates meet the process requirements.

[0018] It should be noted that the filling device can use mechanical vibration or ultrasonic vibration; during the vibration process, the dry active materials will be fully filled into the cavities of the foamed positive and negative current collectors. Using a foamed current collector to replace the foil, the active materials are changed from the original adhesion type to the existing embedded type. The specific surface area of the current collector is increased, and the content of the binder and conductive agent in the active materials is reduced. The materials and time required for preparing the slurry in the early stage are cancelled, the process of preparing the electrode plates in the early stage is reduced, the cost is saved, and the energy consumption is reduced.

[0019] The mechanical vibration can be controlled at 40 - 80 Hz, and the vibration time is 0.5 - 5 minutes; the ultrasonic vibration frequency is adjusted to 40 - 80 Hz, and the vibration time is 0.5 - 5 minutes.

[0020] In Step 2, after confirming the completion of filling, perform a preliminary rolling operation. Send the foamed positive and negative current collectors filled with active materials into a rolling press, and apply an external pressure through the rolling press to make the positive and negative active materials in full contact with the inner cavities of the foamed positive and negative current collectors. As the pressure increases, the positive and negative active materials will be more tightly embedded into the inner cavities of the foamed positive and negative current collectors.

[0021] During the rolling process, it is necessary to strictly control the rolling pressure and speed. The pressure is set at 5 - 50 MPa. The purpose of the preliminary rolling is: 1. To expel the gas between the active substances in the inner cavity, so that the active substances are tightly combined with each other and with the current collector; 2. To prevent the active substances on the surface of the current collector from falling off, preparing for the subsequent spraying of the binder solution. Therefore, the preliminary rolling pressure does not need to be too large, aiming to prevent the surface active substances from falling off. The rolling speed is maintained at 0.1 - 1 m / min.

[0022] In Step 4, the pressure of the secondary rolling is adjusted to 10 - 100 MPa, and the rolling speed is 0.1 - 0.5 m / min. The purpose of the secondary rolling is to increase the compaction density of the active substances and make the electrode sheet meet the process requirements.

[0023] Working principle: Step 1: Filling of active substances. First, prepare the foamed positive and negative current collectors and dry active substances. Place the foamed positive and negative current collectors in the positive and negative material filling equipment. Through mechanical vibration or ultrasonic vibration, make the active substances fully embed into the inner cavity of the current collector. Step 2: Preliminary rolling. After the filling is completed, perform the preliminary rolling operation to make the surface positive and negative active substances closely fit with the outer surface of the foamed positive and negative current collectors, and expel the gas between the positive and negative active substances under the external pressure, reducing the gap between the active substance particles and making the active substances tightly embed into the inner cavity of the foamed positive and negative current collectors. Step 3: Spraying and drying of the binder. After the preliminary rolling is completed, clean the surfaces of the positive and negative electrode sheets to remove possible impurities and dust. Then, use the spraying equipment to evenly spray a layer of binder solution on the surfaces of the preliminarily rolled positive and negative electrode sheets. After spraying, send the electrode sheets into the drying equipment for drying treatment. The surface active substances are firmly bonded to the current collector. Step 4: Secondary rolling. After the drying is completed, send the electrode sheets into the rolling machine for secondary rolling to increase the compaction density of the active substances and make the thickness and surface flatness of the electrode sheets meet the process requirements.

[0024] The above is only the preferred embodiment of the present invention. The protection scope of the present invention is not limited to the above embodiments. All technical solutions within the concept of the present invention belong to the protection scope of the present invention. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and refinements should also be regarded as within the protection scope of the present invention.

Claims

1. Dry filling process for the current collectors of the positive and negative electrodes of a lithium-ion battery, characterized in that, It includes the following steps: Step 1: Filling of active materials. First, prepare the foamed positive and negative current collectors and dry active materials; place the foamed positive and negative current collectors in the positive and negative material filling equipment; through mechanical vibration or ultrasonic vibration, make the active materials fully embed into the inner cavity of the current collector. Step 2: Preliminary rolling. After filling is completed, perform preliminary rolling operation to make the surface positive and negative active materials closely fit with the outer surface of the foamed positive and negative current collectors, and under the condition of external pressure, remove the gas between the positive and negative active materials, reduce the gap between the active material particles, and make the active materials tightly embed into the inner cavity of the foamed positive and negative current collectors. Step 3: Spraying and drying of binder. After preliminary rolling is completed, clean the surfaces of the positive and negative electrode plates to remove possible impurities and dust, and then use spraying equipment to evenly spray a layer of binder solution on the surfaces of the positive and negative electrode plates after preliminary rolling; after spraying is completed, send the electrode plates into the drying equipment for drying treatment; the surface active materials are firmly bonded to the current collector. Step 4: Secondary rolling. After drying is completed, send the electrode plates into the rolling machine for secondary rolling to increase the compaction density of the active materials and make the thickness and surface flatness of the electrode plates meet the process requirements.

2. The dry filling process for the positive and negative electrode current collectors of a lithium-ion battery according to claim 1, wherein The foamed current collector is used to replace the foil current collector, and the active materials are changed from the original adhesion type to the embedded type.

3. The filling equipment according to claim 2 can use mechanical vibration or ultrasonic vibration; during the vibration process, the dry active materials will be fully filled into the cavities of the foamed positive and negative current collectors.

4. The dry filling process of the positive and negative electrode current collectors of the lithium-ion battery according to claim 3, characterized in that, The mechanical vibration can be controlled at 40 - 80 Hz, and the vibration time is 0.5 - 5 minutes; the ultrasonic vibration frequency is adjusted to 40 - 80 Hz, and the vibration time is 0.5 - 5 minutes.

5. The dry filling process of the positive and negative electrode current collectors of a lithium-ion battery according to claim 3, characterized in that, In Step 2, after confirming that filling is completed, perform preliminary rolling operation, send the foamed positive and negative current collectors filled with active materials into the rolling machine, and apply external pressure through the rolling machine to change the surface active materials of the current collector from a loose state to a dense state, so that the active material particles are in close contact with each other and between the active material particles and the current collector, and the surface active materials will not fall off when shaken. Make the positive and negative active materials fully contact with the inner cavity of the foamed positive and negative current collectors. As the pressure increases, the positive and negative active materials will more closely embed into the inner cavity of the foamed positive and negative current collectors.

6. The dry filling process of the positive and negative electrode current collectors of the lithium ion battery according to claim 4, characterized in that, During the rolling process, strictly control the rolling pressure and speed. The pressure is set at 5 - 50 MPa, and the rolling speed is maintained at 0.1 - 1 m / min.

7. The dry filling process of the positive and negative electrode current collectors of the lithium-ion battery according to claim 5, characterized in that, In Step 4, the pressure of secondary rolling is adjusted to 10 - 100 MPa, and the rolling speed is 0.1 - 0.5 m / min.

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