Lithium battery negative electrode coating production device

Abstract

The utility model discloses a lithium battery negative electrode coating production device which comprises a negative electrode drying oven arranged on the discharging side of a coating die head in a connected mode, and a drying channel arranged in a penetrating mode is arranged in the negative electrode drying oven. The negative pole piece drying device is characterized in that an external magnetic field device is arranged on the feeding side of the negative pole drying oven, the external magnetic field device is provided with a conveying channel through which a negative pole piece is conveyed and penetrates, the conveying channel and the drying channel are arranged in an opposite and penetrating mode, and the magnetic field direction of the external magnetic field device is arranged in the thickness direction of the negative pole piece. The graphite cathode has the advantages that the interlayer arrangement of the graphite cathode can be improved, the rate capability and the cycle performance of the battery can be improved, and the like.

Description

Technical Field

[0001] The utility model relates to the technical field of lithium battery production, in particular to a lithium battery negative electrode coating production device. Background Art

[0002] With the increasing demand for electronic products such as electric vehicles and portable electronic devices, the requirements for batteries tend to be high energy density, fast charging and discharging, and high safety. In the field of power batteries, graphite is the most mature and currently the most widely used negative electrode material. Graphite as a negative electrode material is specifically arranged in layers of crystals, with a single layer extending infinitely, and receives the positive electrode Li during the charging process. + Embedded in graphite layers, Li + After being deintercalated from the interlayer and solvated, it reaches the positive electrode, realizing the negative electrode charge and discharge cycle. During the electrochemical reaction, one of the main factors affecting the battery rate charge and discharge is Li + The diffusion rate of the negative electrode layer and the diffusion rate of the negative electrode lithium insertion reaction and deinsertion. + Diffusion in the electrolyte is fast, diffusion between graphite layers and Li + The reaction from the surface of graphite particles to the center of the body is slow, and the biggest influence on the kinetics is Li + Lithium is inserted between graphite layers, especially in the face of society's demand for high energy density, in the case of thick electrode coating, Li + Diffusion between thick electrode graphite layers is the main factor restricting battery rate discharge. + During the negative electrode reaction, it is mainly affected by the tortuosity of the graphite layered arrangement structure channel. Since the interlayer arrangement of the graphite negative electrode is anisotropic and disordered, the tortuosity between the graphite layers is large, which affects the Li + Lithium insertion efficiency. Utility Model Content

[0003] In view of the above-mentioned deficiencies of the prior art, the technical problem to be solved by the present invention is: how to provide a lithium battery negative electrode coating production device that can improve the interlayer arrangement of the graphite negative electrode and is conducive to improving the battery rate performance and cycle performance.

[0004] In order to solve the above technical problems, the utility model adopts the following technical solutions:

[0005] A lithium battery negative electrode coating production device, comprising a negative electrode oven connected to the discharge side of a coating die head, wherein the negative electrode oven has a drying channel arranged through it; it is characterized in that an external magnetic field device is arranged on the feed side of the negative electrode oven, the external magnetic field device has a conveying channel for conveying negative electrode pole pieces through it, the conveying channel is arranged to be opposite to the drying channel, and the magnetic field direction of the external magnetic field device is arranged along the thickness direction of the negative electrode pole piece.

[0006] In this way, after the negative electrode material graphite is discharged from the coating die head, it is evenly coated on the negative electrode copper foil. At this time, the negative electrode material graphite is in a solution state. Based on the intrinsic anti-magnetism of graphite, since the feed side of the negative electrode oven is provided with an external magnetic field device, and the magnetic field direction of the external magnetic field device is set along the thickness direction of the negative electrode sheet, that is, the magnetic field direction is perpendicular to the coating surface, due to the spin factor of the delocalized electrons outside the carbon atomic structure, the electrons are subjected to the external Lorentz force under the action of the magnetic field, combined with their own gravity and Brownian motion, after being baked in the oven, the layered structure of the graphite tends to be arranged vertically with the membrane and slowly solidifies. Under this condition, the Li + In the intercalation and deintercalation efficiency, the Li + The tortuosity in the diffusion process reduces the diffusion kinetics resistance and improves the battery's fast charge, rate discharge and cycle performance.

[0007] Furthermore, the external magnetic field device includes two groups of magnets which are arranged vertically opposite to each other and have the same magnetic pole direction, and the gap between the two groups of magnets forms the conveying channel.

[0008] Furthermore, the magnet is a permanent magnet.

[0009] Furthermore, a plurality of external magnetic field devices are provided along the extension direction of the conveying channel.

[0010] Furthermore, the magnetic field strength of the multiple external magnetic field devices gradually increases along the conveying direction of the negative pole piece.

[0011] Since the negative electrode material graphite just coated is in a solution state, applying a relatively small magnetic field strength can improve the layered structure of the graphite. As the negative electrode material graphite continues to solidify, a relatively large magnetic field strength needs to be applied to ensure that the layered structure of the graphite is more stable.

[0012] Furthermore, the magnetic field strength of the external magnetic field device is 50-150 mT.

[0013] Furthermore, a plurality of the external magnetic field devices are extended and arranged outside the negative electrode oven and at the front section of the negative electrode oven.

[0014] In summary, the utility model has the following advantages:

[0015] 1. Install a multi-level permanent magnetic field in the cathode oven to improve the orientation of graphite molecules and effectively reduce Li + The diffusion efficiency from the surface of graphite particles to the body center is reduced, and the Li + The tortuosity of the channel improves the battery rate characteristics;

[0016] 2. Improve battery cycle life and battery safety. The directional arrangement of graphite layered structure is beneficial to Li + Reaction efficiency on graphite electrode, avoiding Li + The accumulation on the electrode surface reduces battery capacity attenuation and reduces the risk of analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the structure of this embodiment.

[0018] Figure 2 Schematic diagram of the force on the negative electrode graphite.

[0019] Figure 3 Schematic diagram of the graphite layer structure of the negative electrode graphite in a magnetic field. DETAILED DESCRIPTION

[0020] The utility model is further described in detail below in conjunction with the embodiments.

[0021] When implementing: Figure 1 As shown, a lithium battery negative electrode coating production device includes a negative electrode oven 1 connected to the discharge side of the coating die head, and the negative electrode oven 1 has a drying channel arranged through it; the feed side of the negative electrode oven 1 is provided with an external magnetic field device 2, and the external magnetic field device 2 has a conveying channel for the negative electrode pole piece to be conveyed through, and the conveying channel is arranged to be opposite to the drying channel, and the magnetic field direction of the external magnetic field device 2 is arranged along the thickness direction of the negative electrode pole piece.

[0022] The external magnetic field device 2 includes two groups of magnets arranged vertically opposite to each other and having the same magnetic pole direction, and the magnets are permanent magnets; the gap between the two groups of magnets forms the conveying channel. Multiple external magnetic field devices 2 are arranged along the extension direction of the conveying channel, and the magnetic field strength of the multiple external magnetic field devices 2 gradually increases along the conveying direction of the negative pole piece.

[0023] In this embodiment, the magnetic field strength of the external magnetic field device 2 is 50-150 mT.

[0024] According to Sepioni's experiment, graphite has strong paramagnetism when the temperature is below 20K. When the temperature rises to 50K-290K, it shows strong diamagnetic properties and the diamagnetic properties weaken very slowly. Based on this feature, multiple external magnetic field devices are set on the feed side of the negative electrode oven. After the negative electrode sheet is coated, a strong magnetic field is applied to the negative electrode graphite. Due to the diamagnetic properties of graphite, under the action of the external magnetic field, the outermost delocalized electrons on the carbon atomic structure are subjected to the Lorentz force F or F' of the magnetic field, such as Figure 2As shown, under the action of gravity and Brownian motion, the solvent-state graphite is arranged in a direction parallel to the external magnetic field, and is solidified by baking in an oven, thereby achieving the purpose of directionally changing the arrangement orientation of the graphite layers.

[0025] By applying an external magnetic field perpendicular to the coating surface, under the action of the magnetic field, the theoretical graphite layered structure is perpendicular to the coating surface. Figure 3 As shown, Figure 3 The following are schematic diagrams of the layered structure of negative electrode graphite in the case of no magnetic field, 150mT vertical magnetic field and 100mT transverse magnetic field. Under these conditions, the Li + In the intercalation and deintercalation efficiency, the Li + The tortuosity in the diffusion process reduces the diffusion kinetics resistance and improves the battery's fast charge, rate discharge and cycle performance.

[0026] In this way, after the negative electrode material graphite is discharged from the coating die head, it is evenly coated on the negative electrode copper foil. At this time, the negative electrode material graphite is in a solution state. Based on the intrinsic anti-magnetism of graphite, since the feed side of the negative electrode oven is provided with an external magnetic field device, and the magnetic field direction of the external magnetic field device is set along the thickness direction of the negative electrode sheet, that is, the magnetic field direction is perpendicular to the coating surface, due to the spin factor of the delocalized electrons outside the carbon atomic structure, the electrons are subjected to the external Lorentz force under the action of the magnetic field, combined with their own gravity and Brownian motion, after being baked in the oven, the layered structure of the graphite tends to be arranged vertically with the membrane and slowly solidifies. Under this condition, the Li + In the intercalation and deintercalation efficiency, the Li + The tortuosity in the diffusion process reduces the diffusion kinetics resistance and improves the battery's fast charge, rate discharge and cycle performance.

[0027] In this embodiment, a plurality of the external magnetic field devices 2 are extended and arranged outside the negative electrode oven 1 and at the front section of the negative electrode oven 1. In this way, the negative electrode material graphite can better maintain a layered structure during the curing process.

[0028] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A lithium battery negative electrode coating production device, comprising a negative electrode oven (1) connected to the discharge side of a coating die head, wherein the negative electrode oven (1) has a drying channel extending therethrough; It is characterized in that An external magnetic field device (2) is provided on the feed side of the negative electrode drying oven (1), and the external magnetic field device (2) has a conveying channel for conveying the negative electrode pole piece through, the conveying channel is arranged to be opposite to and through the drying channel, and the magnetic field direction of the external magnetic field device (2) is arranged along the thickness direction of the negative electrode pole piece.

2. The lithium battery negative electrode coating production device according to claim 1, It is characterized in that The external magnetic field device (2) comprises two groups of magnets which are arranged vertically opposite to each other and have the same magnetic pole direction, and the gap between the two groups of magnets forms the conveying channel.

3. The lithium battery negative electrode coating production device according to claim 2, It is characterized in that The magnet is a permanent magnet.

4. The lithium battery negative electrode coating production device according to any one of claims 1 to 3, It is characterized in that A plurality of external magnetic field devices (2) are arranged along the extension direction of the transport channel.

5. The lithium battery negative electrode coating production device according to claim 4, It is characterized in that The magnetic field strength of the plurality of external magnetic field devices (2) gradually increases along the conveying direction of the negative pole piece.

6. The lithium battery negative electrode coating production device according to claim 5, It is characterized in that The magnetic field strength of the external magnetic field device (2) is 50-150 mT.

7. The lithium battery negative electrode coating production device according to claim 4, It is characterized in that The plurality of external magnetic field devices (2) are extended and arranged outside the negative electrode oven (1) and at the front section of the negative electrode oven (1).

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