Dry powder coating equipment for pole piece

Abstract

Dry coating equipment for pole pieces comprises a heating roller, a first powder coating device, a second powder coating device, a first heating device and a second heating device, the first powder coating device is arranged on one side of a current collector and used for feeding first mixture powder, and the second powder coating device is arranged on the other side of the current collector and used for feeding second mixture powder. The feeder is used for feeding second mixture powder; the first heating device is arranged on the inner wall of the heating roller and used for heating the first mixture powder; the second heating device is arranged on one side of the outer wall of the heating roller and used for heating the second mixture powder; one side of the current collector is provided with a first conductive adhesive, and the other side of the current collector is provided with a second conductive adhesive. The utility model has the advantages that the coating process is simple, the electrode layer and the current collector are firmly bonded, and the synchronous double-sided coating of the electrode can be realized.

Description

Technical Field

[0001] The utility model relates to the technical field of lithium battery manufacturing, in particular to dry powder coating equipment for pole pieces. Background Art

[0002] Most of the existing coating of lithium-ion electrodes adopts wet coating, which is to mix the active materials of lithium-ion batteries with corresponding organic solvents, and then apply them to the substrate by direct coating or extrusion coating. This method requires a long baking device to bake the coated electrodes to remove the organic solvent and moisture in the electrode active material. If the baked organic solvent is not recycled and directly discharged into the air, it will cause air pollution. If it is recycled, it will increase the cost of users.

[0003] Therefore, a dry powder coating method was proposed. Dry coating does not require organic solvents, so the baking and drying process can be omitted, which can greatly reduce the production cost of the electrode. The existing dry powder coating method is generally divided into two modes. One is to first make the electrode active material into a film, and then hot press the prepared film on the substrate to make a positive electrode or a negative electrode. For example, Chinese patent document CN 115621410 B discloses a dry electrode sheet preparation method, an electrode sheet and its use. The preparation method includes the following steps in sequence: (1) mixing the raw electrode active material, the conductive agent and the polymer resin uniformly to obtain a mixture A; (2) kneading the mixture A by shearing to obtain a viscous mixture B; (3) kneading the mixture B again through an open mill, and the mixture B is completely wrapped on a single roller surface of the open mill, and then the sheet wrapped with the roller is cut open, and after cutting the edges, it is thinned and cooled by roller pressing to obtain a dry electrode film C; (4) The dry electrode film C obtained in step (3) is hot-pressed and compounded on both sides of the current collector foil to obtain a dry electrode sheet. This is a dry powder coating method. The disadvantages of this dry powder coating method are that the coating process is complicated, the electrode film and the current collector are not firmly bonded, and synchronous double-sided coating cannot be achieved.

[0004] The other method is to pre-coat a conductive glue on one side of the current collector, and then feed the pre-mixed positive electrode mixture or negative electrode mixture to the current collector with the conductive glue through a powder coating device, and adhere the positive electrode mixture or negative electrode mixture to the current collector by hot pressing to form an electrode. For example, a dry powder thermal composite transfer coating method and system disclosed in Chinese patent document CN107681111 A belongs to this type of dry powder coating method. The defect of this dry powder coating method is that it cannot achieve synchronous double-sided coating. Utility Model Content

[0005] In order to solve the above problems, the utility model provides a dry powder coating device which has a simple coating process, firmly bonds the electrode layer to the current collector, and can realize simultaneous double-sided coating of the electrode sheet.

[0006] The technical solution of the utility model is: to provide a dry coating device, including a heating roller of a predetermined diameter, a first powder coating device, a second powder coating device, a first heating device and a second heating device, wherein the first powder coating device is arranged on one side of the coating entrance of the collector and the heating roller, and is used to feed the first mixture powder, and the second powder coating device is arranged on the other side of the coating entrance of the collector and the heating roller, and is used to feed the second mixture powder; the first heating device is arranged on the inner wall of the heating roller, and is used to heat the first mixture powder; the second heating device is arranged on one side of the outer wall of the heating roller, and is used to heat the second mixture powder; a first conductive glue is arranged on one side of the collector, and a second conductive glue is arranged on the other side of the collector.

[0007] As an improvement to the present invention, the predetermined diameter is selected between greater than or equal to 1 meter and less than or equal to 3 meters.

[0008] As an improvement to the present invention, the second heating device includes a plurality of heating rollers, which are arranged coaxially with the heating roller on the outside of the heating roller, and a rotating flexible belt is provided on the outer cover of the heating roller. The rotating flexible belt is pressed on the second mixture powder and transfers the heat emitted by the heating roller to the second mixture powder.

[0009] As an improvement to the present invention, the second heating device includes a plurality of guide rollers, wherein the guide rollers are arranged coaxially with the heating roller on the outside of the heating roller, the guide roller outer shell is provided with a rotating flexible belt, and heating plates are provided between the rotating flexible belts. The rotating flexible belts are pressed on the second mixture powder and transfer the heat emitted by the heating plates to the second mixture powder.

[0010] As an improvement to the present utility model, the first heating device is a plurality of electric heating rods embedded on the inner wall of the heating roller.

[0011] As an improvement to the utility model, a self-cleaning coating is provided on the outer wall of the heating roller.

[0012] As an improvement to the present invention, the self-cleaning coating is a polytetrafluoroethylene coating.

[0013] The dry powder coating device of the utility model adopts a heating roller with a predetermined diameter, a first powder coating device, a second powder coating device, a first heating device and a second heating device. The first powder coating device is arranged on one side of the coating entrance of the collector and the heating roller, and is used to feed the first mixture powder. The second powder coating device is arranged on the other side of the coating entrance of the collector and the heating roller, and is used to feed the second mixture powder. The first heating device is arranged on the inner wall of the heating roller, and is used to heat the first mixture powder. The second heating device is arranged on one side of the outer wall of the heating roller, and is used to heat the second mixture powder. The first conductive glue is arranged on one side of the collector, and the second conductive glue is arranged on the other side of the collector. In this way, the utility model has the advantages of simple coating process, firm bonding between the electrode layer and the collector, and synchronous double-sided coating of the electrode can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a structural schematic diagram of an embodiment of the utility model.

[0015] Figure 2 It is a structural schematic diagram of another embodiment of the utility model. DETAILED DESCRIPTION

[0016] See also Figure 1 , Figure 1 Disclosed is a first embodiment of a dry coating device, comprising a heating roller 1 of a predetermined diameter, a first powder coating device 2, a second powder coating device 3, a first heating device 4 and a second heating device 5, wherein the first powder coating device 2 is arranged on one side of a coating entrance of a collector 11 and the heating roller 1, for feeding a first mixture powder 12, and the second powder coating device 3 is arranged on the other side of a coating entrance of the collector 11 and the heating roller 1, for feeding a second mixture powder 13; the first heating device 4 is arranged on the inner wall of the heating roller 1, for heating the first mixture powder 12; the second heating device 5 is arranged on the outer wall side of the heating roller 1, for heating the second mixture powder 13; a first conductive glue is arranged on one side of the collector 11, and a second conductive glue is arranged on the other side of the collector.

[0017] In this embodiment, the current collector can be copper foil or aluminum foil. The first conductive glue and the second conductive glue have the same composition (hereinafter the same), and the first conductive glue and the second conductive glue are mainly composed of a resin matrix, conductive particles, dispersing additives and additives. The resin matrix is ​​commonly used for epoxy resin, silicone resin, polyimide resin, phenolic resin, polyurethane or acrylic resin. After curing, these resin matrices form the molecular skeleton structure of the conductive glue, provide mechanical properties and bonding performance guarantees, and enable the conductive particles to form channels; the conductive particles in the utility model can be gold, silver, copper, aluminum, zinc, iron, nickel powder and / or graphite and some conductive compounds; the thermal curing temperature of the conductive glue can be selected between 30°C and 180°C; preferably, the thermal curing temperature of the conductive glue can be selected between 55°C and 180°C.

[0018] The predetermined diameter of the heating roller is set so that when the heating roller is rotated at a predetermined speed, the first mixture powder and the second mixture powder are fully solidified into one body, and adhered to the first conductive glue and the second conductive glue on both sides of the collector to form the first electrode layer and the second electrode layer respectively; that is, the diameter of the heating roller is determined by the rotation speed of the heating roller, the melting and solidification time of the first mixture powder (including the first conductive glue) and the second mixture powder (including the second conductive glue) and the coating angle of the collector. The faster the rotation speed of the heating roller, the larger the diameter of the heating roller; the longer the melting and solidification time of the first mixture powder (including the first conductive glue) and the second mixture powder (including the second conductive glue), the larger the diameter of the heating roller; the larger the coating angle of the collector, the better. In this embodiment, the coating angle of the collector is preferably selected between 330-340 degrees. The general requirement is that when the first electrode layer and the second electrode layer are formed on both sides of the collector and leave the heating roller, the first electrode layer and the second electrode layer must be fully solidified.

[0019] Preferably, the predetermined diameter is selected between greater than or equal to 1 meter and less than or equal to 3 meters.

[0020] Preferably, the second heating device 5 includes a plurality of heating rollers 51, which are arranged on the outside of the heating roller 1 concentrically with the heating roller 1, and a rotating flexible belt 52 is provided on the outer cover of the heating roller 51. The rotating flexible belt 52 is pressed on the second mixture powder and transfers the heat generated by the heating roller to the second mixture powder.

[0021] Preferably, the first heating device 4 is a plurality of electric heating rods embedded on the inner wall of the heating roller 1 .

[0022] Preferably, a self-cleaning coating is provided on the outer wall of the heating roller 1; the self-cleaning coating includes but is not limited to a polytetrafluoroethylene coating.

[0023] See also Figure 2 , Figure 2 Disclosed is a second embodiment of a dry coating device, wherein the second heating device 5 includes a plurality of guide rollers 53, wherein the guide rollers 53 are arranged on the outside of the heating roller 1 concentrically with the heating roller 1, and a rotating flexible belt 52 is provided on the outer cover of the guide roller 53, and a heating plate 54 is provided between the rotating flexible belts 52, and the rotating flexible belt 52 is pressed on the second mixture powder and transfers the heat emitted by the heating plate to the second mixture powder.

[0024] In this embodiment, the current collector can be copper foil or aluminum foil. The first conductive glue and the second conductive glue have the same composition (hereinafter the same), and the first conductive glue and the second conductive glue are mainly composed of a resin matrix, conductive particles, dispersing additives and additives. The resin matrix is ​​commonly used for epoxy resin, silicone resin, polyimide resin, phenolic resin, polyurethane or acrylic resin. After curing, these resin matrices form the molecular skeleton structure of the conductive glue, provide mechanical properties and bonding performance guarantees, and enable the conductive particles to form channels; the conductive particles in the utility model can be gold, silver, copper, aluminum, zinc, iron, nickel powder and / or graphite and some conductive compounds; the thermal curing temperature of the conductive glue can be selected between 30°C and 180°C; preferably, the thermal curing temperature of the conductive glue can be selected between 55°C and 180°C.

[0025] The predetermined diameter of the heating roller is set so that when the heating roller is rotated at a predetermined speed, the first mixture powder and the second mixture powder are fully solidified into one body, and adhered to the first conductive glue and the second conductive glue on both sides of the collector to form the first electrode layer and the second electrode layer respectively; that is, the diameter of the heating roller is determined by the rotation speed of the heating roller, the melting and solidification time of the first mixture powder (including the first conductive glue) and the second mixture powder (including the second conductive glue) and the coating angle of the collector. The faster the rotation speed of the heating roller, the larger the diameter of the heating roller; the longer the melting and solidification time of the first mixture powder (including the first conductive glue) and the second mixture powder (including the second conductive glue), the larger the diameter of the heating roller; the larger the coating angle of the collector, the better. In this embodiment, the coating angle of the collector is preferably selected between 330-340 degrees. The general requirement is that when the first electrode layer and the second electrode layer are formed on both sides of the collector and leave the heating roller, the first electrode layer and the second electrode layer must be fully solidified.

[0026] Preferably, the predetermined diameter is selected between greater than or equal to 1 meter and less than or equal to 3 meters.

[0027] Preferably, the second heating device 5 includes a plurality of heating rollers 51, which are arranged on the outside of the heating roller 1 concentrically with the heating roller 1, and a rotating flexible belt 52 is provided on the outer cover of the heating roller 51. The rotating flexible belt 52 is pressed on the second mixture powder and transfers the heat generated by the heating roller to the second mixture powder.

[0028] Preferably, the first heating device 4 is a plurality of electric heating rods embedded on the inner wall of the heating roller 1 .

[0029] Preferably, a self-cleaning coating is provided on the outer wall of the heating roller 1; the self-cleaning coating includes but is not limited to a polytetrafluoroethylene coating.

[0030] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes within the technical scope disclosed by the present invention according to the technical scheme and the utility model concept of the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A dry coating device, characterized in that: The invention comprises a heating roller (1) of a predetermined diameter, a first powder coating device (2), a second powder coating device (3), a first heating device (4) and a second heating device (5), wherein the first powder coating device (2) is arranged on one side of a coating entrance of a current collector (11) and the heating roller (1) for feeding a first mixture powder, and the second powder coating device (3) is arranged on the other side of a coating entrance of the current collector (11) and the heating roller (1) for feeding a second mixture powder; the first heating device (4) is arranged on the inner wall of the heating roller (1) for heating the first mixture powder; the second heating device (5) is arranged on the outer wall of the heating roller (1) for heating the second mixture powder; a first conductive glue is arranged on one side of the current collector, and a second conductive glue is arranged on the other side of the current collector.

2. The dry coating equipment for pole pieces according to claim 1, characterized in that: The predetermined diameter is selected between greater than or equal to 1 meter and less than or equal to 3 meters.

3. The dry coating equipment for pole pieces according to claim 1 or 2, characterized in that: The second heating device (5) comprises a plurality of heating rollers (51), wherein the heating rollers (51) are arranged coaxially with the heating roller (1) on the outside of the heating roller (1), and the heating roller (51) is provided with a rotating flexible belt (52) on its outer cover, wherein the rotating flexible belt (52) is pressed against the second mixture powder and transfers the heat generated by the heating rollers to the second mixture powder.

4. The dry coating equipment for pole pieces according to claim 1 or 2, characterized in that: The second heating device (5) comprises a plurality of guide rollers (53), wherein the guide rollers (53) are arranged coaxially with the heating roller (1) on the outside of the heating roller (1), and a rotating flexible belt (52) is provided on the outer cover of the guide roller (53), and heating plates (54) are provided between the rotating flexible belts (52). The rotating flexible belts (52) are pressed against the second mixture powder and transfer the heat generated by the heating plates to the second mixture powder.

5. The dry coating equipment for pole pieces according to claim 1 or 2, characterized in that: The current collector (11) is copper foil or aluminum foil.

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