Dry-method pole piece preparation device

Abstract

The utility model provides a dry-method pole piece preparation device. The dry-method pole piece preparation device comprises a current collector conveying mechanism, an electrode film rolling mechanism and a lithium supplementing mechanism, the current collector conveying mechanism is used for conveying a current collector; the electrode film rolling mechanisms are arranged on the two sides of the conveying direction of the current collector, and the electrode film rolling mechanisms are used for conveying dry-state electrode films and covering the two sides of the current collector with the conveyed dry-state electrode films; the lithium supplementing mechanisms are arranged on the two sides of the conveying direction of the current collector and located on the downstream of the electrode film rolling mechanism, and the lithium supplementing mechanisms are used for covering the surface of the dry-state electrode film with the conveyed lithium strip. According to the dry-method pole piece preparation device disclosed by the utility model, metal lithium can be compounded on the surface of a dry-state electrode film to make up the loss of active lithium, so that the charge-discharge efficiency and the cycle life of a dry-method electrode lithium battery can be improved.

Description

Technical Field

[0001] The utility model relates to the technical field of pole piece preparation, in particular to a dry pole piece preparation device. Background Art

[0002] In the current lithium battery manufacturing, the electrode segment mainly adopts the wet process, that is, the active material, conductive agent, adhesive and other materials are mixed in a solvent in a certain proportion, and then coated on the surface of the current collector according to the designed surface density and rolled. In the traditional wet process, the positive electrode mainly uses NMP (N-methylpyrrolidone) solvent, which is toxic and unfriendly to the environment. In addition, in the traditional wet process, the coating drying and solvent recovery stages require a lot of manpower, equipment and energy costs, which increases the production cost of lithium batteries and reduces the production efficiency of lithium batteries.

[0003] Different from the wet process, the dry process does not require solvents. The active material of the electrode material is directly mixed with the conductive agent and the binder to form a membrane, and then rolled onto the metal current collector to form an electrode. Compared with the wet process, the dry electrode manufacturing technology does not require a large amount of factory floor space to dry the solvent, greatly reducing the capital and manpower expenditures required by the factory. At the same time, it is more environmentally friendly and more suitable for large-scale production.

[0004] At present, the most widely used binders in the preparation of dry electrodes are polymers such as PTFE, PEO, PE, and PVDF. Among them, the most promising dry binder is PTFE, which has the following advantages: 1. Large polymer molecular weight, which can form longer fibrils; 2. Strong inertness and corrosion resistance, long cycle life; 3. Good mechanical properties and easy fiberization. However, when PTFE is used as a binder for lithium batteries, it will react with active lithium during the charge and discharge process of lithium batteries, consuming the active lithium deintercalated by the positive electrode, resulting in low charge and discharge efficiency and poor cycle performance of lithium batteries. Utility Model Content

[0005] In view of this, the utility model aims to provide a dry electrode preparation device to compensate for the loss of active lithium and improve the charge and discharge efficiency and cycle life of dry electrode lithium batteries.

[0006] In order to achieve the above object, the technical solution of the utility model is implemented as follows:

[0007] A dry-process electrode preparation device, comprising a current collector conveying mechanism, an electrode film rolling mechanism and a lithium replenishing mechanism;

[0008] The current collector conveying mechanism is used to convey the current collector;

[0009] The electrode film rolling mechanism is arranged on both sides of the current collector conveying direction, and the electrode film rolling mechanism is used to convey the dry electrode film and laminate the conveyed dry electrode film to both sides of the current collector;

[0010] The lithium replenishing mechanism is arranged on both sides of the current collector conveying direction and is located downstream of the electrode film rolling mechanism. The lithium replenishing mechanism is used to laminate the conveyed lithium belt onto the surface of the dry electrode film.

[0011] Furthermore, the current collector conveying mechanism includes a current collector unwinding roller and a current collector winding roller which are arranged at intervals.

[0012] Furthermore, the electrode film rolling mechanism includes two groups of rolling assemblies arranged relative to each other, each of the two groups of rolling assemblies includes a plurality of rollers arranged side by side, the adjacent rollers move synchronously in opposite directions, and the rollers in the two groups of rolling assemblies close to the current collector are used to laminate the transported dry electrode film onto the current collector.

[0013] Furthermore, a feeding port for electrode powder is provided above a pair of the pressing rollers in each group of the rolling assemblies, which are away from the current collector; a heating element for heating the roller surface is provided in the pair of pressing rollers, and the pair of pressing rollers rotate at different speeds.

[0014] Furthermore, the diameters of the plurality of pressing rollers in the rolling assembly are the same; or, along the direction pointing to the current collector, the diameters of the plurality of pressing rollers in the rolling assembly are gradually reduced.

[0015] Furthermore, the diameter of each of the pressing rollers is between 100 mm and 1000 mm.

[0016] Furthermore, the lithium replenishing mechanism includes a lithium ribbon unwinding roller, a lithium ribbon transfer roller and a lithium ribbon winding roller arranged at intervals, and the two lithium ribbon transfer rollers located on both sides of the current collector move synchronously in opposite directions; the lithium ribbon transported by the lithium ribbon unwinding roller is wound around the lithium ribbon transfer roller, and the lithium ribbon is rolled by the two lithium ribbon transfer rollers to be compounded on the surface of the dry electrode film.

[0017] Furthermore, the diameter of the lithium belt transfer roller is between 100 mm and 300 mm.

[0018] Furthermore, the lithium strip includes an auxiliary film and metallic lithium composited on the auxiliary film.

[0019] Furthermore, the auxiliary film includes one of PET film, PP film, PE film, stainless steel foil, copper foil and aluminum foil.

[0020] Compared with the prior art, the utility model has the following advantages:

[0021] The dry electrode preparation device described in the utility model can compound metallic lithium on the surface of the dry electrode film through the lithium replenishing mechanism set in the dry electrode preparation process to compensate for the loss of active lithium, thereby improving the charge and discharge efficiency and cycle life of the dry electrode lithium battery.

[0022] In addition, the current collector unwinding roller and current collector winding roller are provided to facilitate the transportation of the current collector. The two sets of rolling assemblies provided can facilitate the preparation of dry electrode films on both sides of the current collector transportation direction, and are conducive to the simultaneous lamination of electrode films on both sides of the current collector. Moreover, the two pressing rollers close to the current collector are used to laminate the transported dry electrode film onto the current collector, so that the rolling and lamination of the electrode film can share a pair of pressing rollers, which is conducive to saving the number of pressing rollers.

[0023] In addition, the feed port is provided to facilitate the addition of electrode powder. The diameters of multiple rollers are the same, or the diameters of multiple rollers are gradually reduced in the direction pointing to the current collector, which is conducive to ensuring the calendering effect of the electrode film. The lithium belt unwinding roller, lithium belt transfer roller and lithium belt winding roller are provided to facilitate the transportation of lithium belt and the composite lithium metal on the surface of the dry electrode film. The setting of the diameter of the lithium belt transfer roller is conducive to ensuring the lamination effect of metal lithium and dry electrode film. The lithium belt includes an auxiliary membrane and metal lithium, which is conducive to the transportation of the lithium belt and the smooth progress of the lithium replenishment process. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation on the present invention. In the accompanying drawings:

[0025] Figure 1 This is a structural principle diagram of a dry-process electrode preparation device according to an embodiment of the utility model;

[0026] Description of reference numerals:

[0027] 1. Current collector unwinding roller; 2. Current collector winding roller; 3. Feeding port; 4. First pressure roller; 5. Second pressure roller; 6. Third pressure roller; 7. Fourth pressure roller; 8. Fifth pressure roller; 91. Lithium ribbon unwinding roller; 92. Lithium ribbon transfer roller; 93. Lithium ribbon winding roller; 10. Current collector; 20. Lithium ribbon. DETAILED DESCRIPTION

[0028] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0029] In the description of the present invention, it should be noted that if there are terms such as "upper", "lower", "inner", "outer" and the like indicating orientation or positional relationship, they are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, if there are terms such as "first" and "second", they are also used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0030] In addition, in the description of the present invention, unless otherwise clearly defined, the terms "installation", "connection", "connection" and "connector" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood in combination with specific circumstances.

[0031] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0032] This embodiment relates to a dry electrode preparation device, which can compensate for the loss of active lithium, thereby improving the charge and discharge efficiency and cycle life of the dry electrode lithium battery.

[0033] In terms of overall structure, the dry electrode preparation device of this embodiment is as follows: Figure 1 As shown, the dry electrode preparation device mainly includes a current collector conveying mechanism, an electrode film rolling mechanism and a lithium replenishing mechanism. Among them, the current collector conveying mechanism is used to convey the current collector 10. The electrode film rolling mechanism is arranged on both sides of the current collector conveying direction, and the electrode film rolling mechanism is used to convey the dry electrode film and laminate the conveyed dry electrode film to both sides of the current collector 10. The lithium replenishing mechanism is arranged on both sides of the current collector conveying direction and is located downstream of the electrode film rolling mechanism. The lithium replenishing mechanism is used to laminate the conveyed lithium belt 20 to the surface of the dry electrode film.

[0034] At this time, through the set current collector conveying mechanism, electrode membrane rolling mechanism and lithium replenishing mechanism, during the preparation of dry electrode sheets, the surface of the dry electrode membrane can be composited with metallic lithium to compensate for the loss of active lithium, thereby improving the charge and discharge efficiency and cycle life of the dry electrode lithium battery.

[0035] Specifically, continue to see Figure 1 As shown, in this embodiment, the current collector conveying mechanism includes a current collector unwinding roller 1 and a current collector winding roller 2 which are arranged at intervals, so as to facilitate the conveyance of the current collector 10 .

[0036] The electrode film rolling mechanism of this embodiment includes two sets of rolling assemblies arranged opposite to each other. The two sets of rolling assemblies are arranged on both sides of the current collector conveying direction, and both sets of rolling assemblies include a plurality of rollers arranged side by side, and the adjacent rollers move synchronously in opposite directions, and the rollers in the two sets of rolling assemblies close to the current collector 10 are used to laminate the conveyed dry electrode film onto the current collector 10.

[0037] At this time, the two sets of roller pressing assemblies can facilitate the preparation of dry electrode films on both sides of the current collector conveying direction, and facilitate the simultaneous lamination of electrode films on both sides of the current collector 10. In addition, the two pressing rollers close to the current collector 10 are used to laminate the conveyed dry electrode film onto the current collector 10, so that the rolling and lamination of the electrode film can share a pair of pressing rollers, which is conducive to saving the number of pressing rollers.

[0038] Specifically, the plurality of rollers in each group of roller pressing assemblies include a first roller 4, a second roller 5, a third roller 6, a fourth roller 7 and a fifth roller 8, respectively, and the first roller 4, the second roller 5, the third roller 6, the fourth roller 7 and the fifth roller 8 are sequentially arranged side by side in a direction pointing to the current collector 10. The two fifth rollers 8 are used to laminate the transported dry electrode film onto the current collector 10.

[0039] Still viewing Figure 1 As shown, in this embodiment, a feeding port 3 for electrode powder is provided above a pair of rollers on the side away from the current collector 10 in each group of roller pressing assemblies, so that the addition of electrode powder is convenient and the preparation of dry electrode film is smooth. Moreover, a pair of rollers on the side away from the current collector 10, that is, the first roller 4 and the second roller 5, are provided with a heating element for heating the roller surface, and the heating element can be, for example, a heating wire embedded in the first roller 4 and the second roller 5, or a cavity is provided in the first roller 4 and the second roller 5, and the cavity is used to accommodate heating oil or hot water, etc., so that the roller surface of the first roller 4 and the second roller 5 can be heated.

[0040] Moreover, in this embodiment, a pair of rollers away from the current collector 10, namely the first roller 4 and the second roller 5, rotate at different speeds, which can help improve the preparation quality of the dry-process electrode. In specific implementation, the speed ratio between the two is preferably between 1.001 and 5.000.

[0041] As a preferred embodiment, in this embodiment, in order to ensure the calendering effect of the electrode film, the diameters of the multiple rollers in the rolling assembly are between 100 mm and 1000 mm. In specific implementation, the diameter of the roller can be set to 100 mm, 200 mm, 300 mm, 400 mm, 500 mm, 600 mm, 700 mm, 800 mm, 900 mm or 1000 mm, for example. Moreover, in order to further ensure the calendering effect of the electrode film, the diameters of the multiple rollers in each rolling assembly can be the same, or, in the direction pointing to the current collector 10, the diameters of the multiple rollers in the rolling assembly are gradually reduced.

[0042] The lithium replenishment mechanism of this embodiment includes a lithium ribbon unwinding roller 91, a lithium ribbon transfer roller 92 and a lithium ribbon winding roller 93 arranged at intervals, and the two lithium ribbon transfer rollers 92 located on both sides of the current collector 10 move synchronously in opposite directions. The lithium ribbon 20 conveyed by the lithium ribbon unwinding roller 91 is wound on the lithium ribbon transfer roller 92. At this time, the lithium ribbon 20 is rolled and compounded on the surface of the dry electrode film by the rolling of the two lithium ribbon transfer rollers 92, so as to replenish the lithium on the surface of the dry electrode film on both sides. The arrangement of the lithium ribbon unwinding roller 91, the lithium ribbon transfer roller 92 and the lithium ribbon winding roller 93 can facilitate the conveyance of the lithium ribbon 20 and the smooth progress of the lithium replenishment process.

[0043] As a preferred implementation, in this embodiment, the diameter of the lithium ribbon transfer roller 92 is between 100 mm and 300 mm. In specific implementation, the diameter of the lithium ribbon transfer roller 92 can be set to 100 mm, 150 mm, 200 mm, 250 mm or 300 mm, for example.

[0044] In this embodiment, as a preferred embodiment, the lithium ribbon 20 includes an auxiliary film and metal lithium compounded on the auxiliary film. After the lithium ribbon 20 conveyed by the lithium ribbon unwinding roller 91 is rolled and compounded on the surface of the dry electrode film by the lithium ribbon transfer roller 92, the auxiliary film is rolled up by the lithium ribbon winding roller 93. And as a further preferred embodiment, the auxiliary film of this embodiment includes one of PET film, PP film, PE film, stainless steel foil, copper foil, and aluminum foil.

[0045] It should be noted that, in addition to the above-mentioned structure, the lithium ribbon 20 of this embodiment may also be made of pure metallic lithium, which is also feasible.

[0046] The dry electrode preparation device of this embodiment, when used, firstly mix the electrode active material, conductive agent, binder, other additives, etc. evenly to obtain a mixture. Then, the mixture is preliminarily fiberized, and the fiberization degree is controlled at about 10% to obtain the above-mentioned electrode powder. In order to achieve the fiberization effect, the mixing equipment is selected from one or more of a stirring mixer, a jet mill, a twin-screw extruder, and an open mill.

[0047] The prepared electrode powder is added between the first pressing roller 4 and the second pressing roller 5 through the feeding port 3. The powder material is rolled into a thick film with a certain strength under the pressure and shear force of the first pressing roller 4 and the second pressing roller 5. The strength of the film is related to the fiberization degree of the binder. The higher the fiberization degree, the greater the film strength. Increasing the calendering temperature and the calendering speed difference can increase the fiberization degree of the binder. Therefore, the first pressing roller 4 and the second pressing roller 5 can be heated. The heating temperature is preferably 100℃~200℃. At the same time, the calendering speed ratio of the first pressing roller 4 and the second pressing roller 5 is increased. The first pressing roller 4 is a slow roller and the second pressing roller 5 is a fast roller. The speed ratio of the two is preferably between 1.001 and 5.000.

[0048] Under the action of the calendering speed ratio, the calendered membrane, i.e., the dry electrode membrane, will be transferred to the surface of the fast roller, that is, the membrane calendered on the first roller 4 and the second roller 5 is transferred to the second roller 5, and so on. During the calendering process of the second roller 5 and the third roller 6, the membrane is transferred to the third roller 6, during the calendering process of the third roller 6 and the fourth roller 7, the membrane is transferred to the fourth roller 7, and during the calendering process of the fourth roller 7 and the fifth roller 8, the membrane is transferred to the fifth roller 8. The membrane gradually becomes thinner during the calendering transfer process. By adjusting the parameters such as the calendering roller gap, calendering pressure, and calendering speed ratio, the membrane finally reaches the required design thickness and surface density. After the dry electrode membrane is simultaneously transferred to the fifth roller 8, the current collector unwinding roller 1 begins to unwind, and the dry electrode membrane is laminated to both sides of the laminated current collector 10 under pressure to complete the dry electrode preparation.

[0049] Next, the dry electrode moves downward under the traction of the winding roller. At the same time, the two lithium tape unwinding rollers 91 start to unwind. The lithium tape 20 and the dry electrode enter between the two lithium tape transfer rollers 92 at the same time. The lithium tape transfer roller 92 first presses the lithium tape 20 and the dry electrode tightly under the action of the servo cylinder, and then adjusts the roller gap and pressure to laminate the lithium tape 20 onto the surface of the dry electrode, completing the lithium replenishment of the dry electrode.

[0050] The dry electrode preparation device of this embodiment can compensate for the loss of active lithium by adding a lithium replenishing mechanism during the dry electrode preparation process to coat the surface of the dry electrode film with metallic lithium, thereby improving the charge and discharge efficiency and cycle life of the dry electrode lithium battery.

[0051] 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, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A dry electrode preparation device, characterized in that: It includes a current collector conveying mechanism, an electrode film rolling mechanism and a lithium replenishing mechanism; The current collector conveying mechanism is used to convey the current collector; The electrode film rolling mechanism is arranged on both sides of the current collector conveying direction, and the electrode film rolling mechanism is used to convey the dry electrode film and laminate the conveyed dry electrode film to both sides of the current collector; The lithium replenishing mechanism is arranged on both sides of the current collector conveying direction and is located downstream of the electrode film rolling mechanism. The lithium replenishing mechanism is used to laminate the conveyed lithium belt onto the surface of the dry electrode film.

2. The dry electrode preparation device according to claim 1, characterized in that: The current collector conveying mechanism comprises a current collector unwinding roller and a current collector winding roller which are arranged at intervals.

3. The dry electrode preparation device according to claim 1, characterized in that: The electrode film rolling mechanism includes two groups of rolling assemblies arranged relatively to each other, each of the two groups of rolling assemblies includes a plurality of rollers arranged side by side, the adjacent rollers move synchronously in opposite directions, and the rollers in the two groups of rolling assemblies close to the current collector are used to laminate the transported dry electrode film onto the current collector.

4. The dry electrode preparation device according to claim 3, characterized in that: A feeding port for electrode powder is provided above a pair of the pressing rollers on a side away from the current collector in each group of the rolling assemblies; The pair of pressure rollers are provided with a heating element for heating the roller surfaces, and the pair of pressure rollers rotate at different speeds.

5. The dry electrode preparation device according to claim 3, characterized in that: The diameters of the plurality of rollers in the roller pressing assembly are the same; or, Along the direction pointing to the current collector, the diameters of the plurality of pressing rollers in the rolling assembly are gradually reduced.

6. The dry electrode preparation device according to claim 3, characterized in that: The diameter of each pressing roller is between 100 mm and 1000 mm.

7. The dry electrode preparation device according to any one of claims 1 to 6, characterized in that: The lithium replenishing mechanism comprises a lithium ribbon unwinding roller, a lithium ribbon transfer roller and a lithium ribbon winding roller arranged at intervals, and the two lithium ribbon transfer rollers located on both sides of the current collector move synchronously in opposite directions; The lithium ribbon conveyed by the lithium ribbon unwinding roller is wound on the lithium ribbon transfer roller, and the lithium ribbon is rolled by two lithium ribbon transfer rollers to be compounded on the surface of the dry electrode film.

8. The dry electrode preparation device according to claim 7, characterized in that: The diameter of the lithium belt transfer roller is between 100 mm and 300 mm.

9. The dry electrode preparation device according to claim 7, characterized in that: The lithium ribbon includes an auxiliary film and metal lithium composited on the auxiliary film.

10. The dry electrode preparation device according to claim 9, characterized in that: The auxiliary film comprises one of PET film, PP film, PE film, stainless steel foil, copper foil and aluminum foil.

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