Electrode film and pole piece forming device

Abstract

The utility model provides a pole piece forming device. The pole piece forming device comprises a material conveying belt, and a demolding layer pasting device, a material distributing device, a material heating device, a first-stage stamping device, a second-stage stamping device, a hot stamping device and a heating demolding device which are sequentially arranged in the direction of the material conveying belt. The device is further provided with a mold conveying assembly which comprises an electrode film mold, a mold conveying belt, a mold containing device and a mold recycling device. According to the pole piece forming device provided by the scheme, the uniformity of the electrode film and the electrical performance of the pole piece are remarkably improved, meanwhile, continuous production is realized, and the pole piece forming device has the characteristics of high efficiency, stability and low cost and is suitable for large-scale industrial application.

Description

TECHNICAL FIELD

[0001] The utility model relates to electrode membrane production equipment technical field, specifically including a kind of electrode film, pole piece forming device. BACKGROUND

[0002] The cost and performance of lithium-ion batteries (LIBs) depend largely on the manufacturing process of the electrodes. Currently, the electrode manufacturing of commercial LIBs usually adopts slurry-casting (SC) procedure, i.e. wet coating process, which limits the thickness of the electrode. To overcome this limitation, solvent-free (SF) procedure, i.e. dry manufacturing process, is a promising solution. SF process does not use solvent, and by dry homogenizing the binder with active material and conductive agent, it can manufacture thick electrodes without worrying about the uneven distribution of the binder, so it has been widely used. However, there are still some problems to be solved in the current production process.

[0003] When preparing electrodes by SF process, the conductive slurry (conductive additive, active material, binder) is usually first dry-mixed to form a fibrous mixture, then the fibrous mixture is rolled into a supportable film material by a roller and transferred to a bonding station, and the film material is rolled and bonded with the current collector to form an electrode sheet. The most critical point of this preparation method is to roll the mixture into a supportable film material by a roller and bond it with the current collector, so the quality of the film material and the tightness of the bonding with the current collector will greatly affect the quality of the electrode sheet. The common way to prepare the film material is to roll the mixture by a cylindrical roller, so that the polymer crystals slip along the shear direction (c-axis) (such as Figure 8 ), thereby forming a self-supporting film material. Although this rolling method is relatively simple, the fibrous mixture is easy to form cavities inside during the falling process, resulting in holes in the prepared film material, which further affects the uniformity of the film material and affects the performance of the film material. It may cause the film material to be too thick at the joint and prone to cracking and breaking. In addition, in actual operation, the factory equipment is often limited, and the equipment parameters need to be reset and adjusted every time the rolling is performed, which greatly reduces the efficiency. Therefore, how to solve the problem of easy breaking or over-thickness at the joint caused by multiple rolling and low production efficiency has become a hot spot of current research. SUMMARY

[0004] The utility model provides a kind of dry preparation method of electrode film for the problems in prior art, it is applicable to the electrode film preparation of 50um above thickness, solve the quality problem caused by electrode film thickness uneven when rolling, improve production efficiency simultaneously.

[0005] In a first aspect, the present application provides an electrode sheet forming device, comprising a material conveying belt, and a demolding layer pasting device, a material distributing device, a material heating device, a first-stage stamping device, a second-stage stamping device, a hot stamping device, and a heated demolding device arranged in sequence along the material conveying direction on the material conveying belt.

[0006] The electrode sheet forming device further comprises a mold conveying assembly, including an electrode film mold, a mold conveying belt, a mold placing device, and a mold recycling device. The mold placing device is used to place the electrode film mold on the material conveying belt before the material distributing device. The mold conveying belt is arranged on the two side edges of the material conveying belt and is parallel to or higher than the horizontal plane of the material conveying belt in the horizontal direction. The mold conveying belt is used to carry the electrode film mold through the material distributing device, the material heating device, and the first-stage stamping device in sequence. The mold recycling device is used to recycle the electrode film mold after the first-stage stamping.

[0007] The electrode sheet forming device further comprises a current collector unwinding device and an electrode sheet winding device. The unwinding device is used to unwind the current collector to be combined with the electrode film passing through the hot stamping device. The electrode sheet winding device is used to wind the electrode sheet demolded from the hot stamping device.

[0008] The type of demolding layer pasting device is not limited, and the skilled person can select different pasting devices to paste the demolding layer to the surface of the material conveying belt according to the requirements.

[0009] As a further solution, the thickness of the demolding layer is selected from 0.1 μm to 20 μm.

[0010] As a further solution, the demolding layer comprises a carrier layer and a glue layer arranged on any one side of the carrier layer.

[0011] As a further solution, the material of the carrier layer is not limited in principle, and the skilled person can select substances including but not limited to one or more of polyethylene, polypropylene, and polycarbonate.

[0012] As a further solution, the material of the glue layer is not limited in principle, and the skilled person can select substances including but not limited to one of polyacrylate glue and polyurethane glue.

[0013] As a further solution, when the mold conveying belt is higher than the material conveying belt in the horizontal direction, the height is selected from 0.5 to 1 mm.

[0014] As a further solution, the material distributing device comprises a material distributing port and a material tank. The material tank is fixedly connected with the material distributing port, and the material distributing port can distribute the material according to the preset weight.

[0015] As a further solution, the primary stamping device comprises a primary stamping base and a primary stamping head, the primary stamping head is fixedly connected with the primary stamping base, the primary stamping head protrudes from the primary stamping base, the shape of the primary stamping head is matched with the electrode film mold, and the primary stamping head is used for primary stamping of the material in the electrode film mold.

[0016] As some examples, the electrode film mold comprises a primary electrode film grid, the primary electrode film grid is communicated with the front and back of the electrode mold, and the width of the primary electrode film grid is matched with the material conveying belt, the primary stamping head is matched with the primary electrode film grid, and the size of the primary stamping head is smaller than the size of the primary electrode film grid by 0.8mm-1.2mm.

[0017] As a further solution, the primary stamping head is divided into primary stamping blocks by longitudinally and transversely distributed grooves, the electrode film mold comprises a tab part and a partition part, the tab part and the partition part are longitudinally and transversely staggered, and the primary electrode film grid is divided into electrode film grids, the electrode film grids are matched with the primary stamping blocks, and the size of the primary stamping blocks is smaller than the size of the electrode film grids by 0.8mm-1.2mm.

[0018] As a further solution, the primary stamping base is further provided with a positioning convex column matched with the electrode film mold.

[0019] As a further solution, the electrode mold is further provided with a positioning hole matched with the positioning convex column on the primary stamping device, the existence of the positioning hole helps to match the positioning convex column on the primary stamping device, and realizes accurate pairing of the electrode film grid and the primary stamping block.

[0020] As a further solution, the number of the positioning holes is greater than or equal to 2.

[0021] As a further preferred solution, the number of the positioning holes is selected from 4-8.

[0022] The secondary stamping device comprises a secondary stamping base and a secondary stamping head, the secondary stamping head is fixedly connected with the secondary stamping base, and the secondary stamping head protrudes from the secondary stamping base as a whole.

[0023] The electrode film mold is further provided with a positioning part, the positioning part is arranged on the left side and the right side of the electrode film mold.

[0024] The mold conveying belt is provided with positioning cards, the positioning cards appear in pairs to form a clamping groove matched with the positioning part of the electrode film mold, and the positioning part is clamped in the clamping groove formed by the positioning cards, so as to realize fixation of the electrode film mold on the mold conveying belt.

[0025] As a further solution, the electrode film mold is further provided with a placing handle, the placing handle is arranged on the left side and the right side of the electrode film mold respectively, and the number of the placing handles is greater than or equal to 2.

[0026] As a further preferred solution, the number of said placement handles is selected from 2-4.

[0027] Said mold placement device comprises a placement holding arm cooperating with the placement handle of the electrode film mold and a first support base detachably connected with the placement holding arm.

[0028] As a further solution, said mold recycling device comprises a recycling clamping arm cooperating with the placement handle of the electrode film mold and a second support base detachably connected with the recycling clamping arm.

[0029] As a further solution, said current collector unwinding device comprises a current collector roll for unwinding the current collector, a first roller pair, and a second roller pair for guiding the current collector and the electrode film after being compounded by the hot stamping device into the heating demolding device.

[0030] As a further solution, said electrode piece winding device comprises an electrode piece roll and a third roller pair for guiding the electrode piece through the heating demolding device, and the electrode piece roll is used for winding the electrode piece.

[0031] As a further solution, said electrode piece roll is provided with a current collector foil detector for detecting the current collector foil.

[0032] As a further solution, said electrode piece forming device is further provided with a controller for receiving instructions from technicians and controlling the operation of the electrode piece forming device.

[0033] Advantages:

[0034] Compared with the prior art, the utility model has at least the following advantages:

[0035] (1) The pre-set weight partitioning and limiting reduce the requirement for uniformity of feeding. The feeding form can be powder or dough-like material, and the feeding mode includes screw extrusion, air pressure or push rod extrusion, powder blowing, etc., all of which can be applied. The material is quantitatively fed according to weight in each material compartment, which further ensures the consistency of the prepared electrode piece and improves the stability of product quality.

[0036] (2) The combination of primary stamping and secondary stamping is adopted. The primary stamping makes the material slide and flatten within the limiting range, prevents local hardening of the material, avoids high stress concentration on the material surface, and reduces the risk of material rupture or irreversible change. The secondary stamping further makes the material slide and thin, eliminates the peripheral protrusion problem caused by the primary stamping, and finally obtains an electrode film with good uniformity and high consistency.

[0037] (3) Through the hot stamping composite, first use stamping composite to make the current collector and solid-state electrode film each other micro deformation, then through the hot stamping composite to make the electrode film in the binder and the current collector bonding, realize the electrode film and the current collector better combination. This process optimizes the resistance and cycle performance of the electrode sheet, improves the electrical performance of the electrode sheet.

[0038] (4) Through the setting of the release layer, effectively solve the problem of the electrode film and the conveying belt bonding and separation, avoid the electrode film damage or the conveying belt wear caused by bonding, prolong the service life of the equipment, improve the production efficiency.

[0039] (5) The whole process is continuous and simple, can realize continuous production, improve the production efficiency, reduce the production cost, suitable for large-scale industrial production. BRIEF DESCRIPTION OF DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0041] Figure 1 It is a schematic diagram of the electrode sheet forming device;

[0042] Figure 2 It is a top view of the electrode sheet forming device;

[0043] Figure 3 It is a schematic diagram of the electrode film mold;

[0044] Figure 4 It is a schematic diagram of the electrode film mold placed on the mold conveying belt.

[0045] Figure 5 It is a schematic diagram of the first stage stamping device;

[0046] Figure 6 It is a schematic diagram of the second stage stamping device;

[0047] Figure 7 It is a schematic diagram of the electrode sheet forming process;

[0048] Figure 8 It is a schematic diagram of the slip deformation of polymer crystal under shear action;

[0049] Figure 9 It is a schematic diagram of the slice waste;

[0050] Figure 10 It is a schematic diagram of the cloth device structure;

[0051] Figure 11 InFigure 11 a is a mold placing device 173, Figure 11 b is a mold recycling device 174.

[0052] Wherein, 11-material conveying belt; 12-mold release layer pasting device; 13-distributing device; 131-distributing port; 132-material tank; 14-material heating device; 15-first stage stamping device; 151-first stage punch; 152-first stage stamping base; 153-positioning convex column; 16-second stage stamping device; 161-second stage punch; 162-second stage stamping base; 17-mold conveying assembly; 171-mold conveying belt; 1711-positioning card; 172-electrode film mold; 1721-electrode film grid; 1722-tab part; 1723-positioning part; 1724-positioning hole; 1725-placing handle; 1726-partition part; 173-mold placing device; 1731-placing clamping arm; 1732-first support base; 174-mold recycling device; 1741-recycling clamping arm; 1742-second support base; 21-current collector unwinding device; 211-current collector roll; 212-first roller pair; 213-second roller pair; 22-hot stamping device; 221-hot stamping punch; 222-hot stamping main body; 23-heating demolding device; 24-pole piece winding device; 241-pole piece roll; 242-third roller pair. DETAILED DESCRIPTION

[0053] For the convenience of understanding, the utility model will be described more fully below, and the embodiments of the utility model are given, but the scope of the utility model is not limited by this.

[0054] The following is the explanation of terms or words, and unless otherwise defined, all technical and scientific terms used herein have the meanings commonly understood by one of ordinary skill in the art to which the utility model belongs.

[0055] In this article, the word "material" refers to the raw material used to prepare the electrode film, which can include both directly mixed raw materials and mixed fiberized materials.

[0056] In this article, "fiberized material" refers to the electrode material after fiberization treatment in the process of dry electrode preparation.

[0057] In this article, the word "partition distribution" means that according to the specifications of the pole piece slice, the material of the preset quality is put into the center position of each pole piece slice area.

[0058] In this article, the word "hot stamping" refers to the process of combining the pole piece and the electrode film together through stamping and hot pressing in the pole piece processing process.

[0059] In this article, the word "punching composite" refers to the process of combining the current sheet and electrode film together by mechanical punching during the processing of the current sheet.

[0060] In this article, the word "hot pressing composite" refers to the process of combining the current sheet and electrode film under high temperature conditions by heating and pressure during the processing of the current sheet.

[0061] In a first aspect, as Figures 1-2 The present application provides a current sheet forming device, comprising a material conveying belt 11, and a demolding layer pasting device 12, a material distributing device 13, a material heating device 14, a first punching device 15, a second punching device 16, a hot punching device 22, and a heating demolding device 23 arranged in sequence along the material conveying direction on the material conveying belt 11.

[0062] The current sheet forming device is further provided with a mold conveying assembly 17, comprising an electrode film mold 172, a mold conveying belt 171, a mold placing device 173, and a mold recycling device 174. The mold placing device 173 is used to place the electrode film mold 172 on the material conveying belt 11 before the material distributing device 13. The mold conveying belt 171 is arranged on both sides of the material conveying belt 11 and is parallel to or higher than the horizontal plane of the material conveying belt 11 in the horizontal direction. The mold conveying belt 171 is used to carry the electrode film mold 172 to pass through the material distributing device 13, the material heating device 14, and the first punching device 15 in sequence. The mold recycling device 174 is used to recycle the electrode film mold 172 after the first punching.

[0063] The current sheet forming device is further provided with a current collector unwinding device 21 and a current sheet winding device 24. The unwinding device 21 is used to unwind the current collector to be combined with the electrode film passing through the hot punching device 22. The current sheet winding device 24 is used to wind the current sheet demolded from the hot punching device 22.

[0064] In this application, the demolding layer pasting device 12 can paste the demolding layer on the surface of the material conveying belt 11. The mold placing device 173 places the electrode film mold 172 on the material conveying belt 11 with the pasted demolding layer. The material distributing device 13 distributes the material into the electrode film mold 172 in a partitioned manner according to the preset weight. The electrode film mold 172 is used to limit the material. Then, the material heating device 14 heats the material. The material heating device 14 is arranged to improve the thermal plastic slipperiness of the material by temperature, so that the material is more uniformly distributed during the first punching.

[0065] After the heated material enters the working range of the punching device 15 for the first punching, the mold recycling device 174 recycles the electrode film mold 172. The second punching device 16 performs the second punching on the material after the first punching. After the punching is completed, the electrode film is obtained.

[0066] The current collector is applied to the surface of the prepared electrode film by the current collector unwinding device 21, and the electrode film and the current collector are hot-pressed together by the hot stamping device 22. Then, the electrode film is physically separated from the material conveyor belt 11 by the heating demolding device 23. The heating demolding device 23 with heating function improves production efficiency while achieving easy physical separation between the electrode film and the conveyor belt. After demolding, the electrode sheet winding device 24 winds it up to obtain a single-sided electrode sheet.

[0067] There are no restrictions on the 12 types of release layer pasting devices. Technicians can select different pasting devices to paste the release layer onto the surface of the material conveyor belt 11 according to their needs.

[0068] As examples, the thickness of the release layer is selected from 0.1μm to 20μm, including a carrier layer and an adhesive layer disposed on any side of the carrier layer. To avoid the release layer affecting the performance of the electrode, a material with a melting point higher than the hot-pressing composite temperature and lower than the upper limit of the tolerance temperature of each substance in the material, and whose shrinkage or decomposition residues do not react with the battery material or electrolyte, should be selected as the release layer. Therefore, the materials of the carrier layer and the adhesive layer in the release layer are not limited in principle, wherein the carrier layer can be selected from one or more of polyethylene, polypropylene, and polycarbonate; and the adhesive layer can be selected from polyacrylate adhesive and polyurethane adhesive.

[0069] As examples, when the mold conveyor belt 171 is horizontally higher than the material conveyor belt 11, the height is selected from 0.5-1mm.

[0070] As some examples, the fabric feeding device 13 includes a fabric feeding port 131 and a material tank 132, the material tank 132 and the fabric feeding port 132 being fixedly connected, and the fabric feeding port 131 can feed the material into sections according to a preset weight.

[0071] As some examples, such as Figure 5 The primary stamping device 15 includes a primary punch 151 and a primary stamping base 152. The primary stamping base 152 is fixedly connected to the primary punch 151. The primary punch 151 protrudes from the primary stamping base 152. The shape of the primary punch 151 matches the electrode film mold 172 and is used to perform primary stamping on the material in the electrode film mold 172.

[0072] As some examples, the electrode film mold 172 includes a primary electrode film grid that connects the front and back sides of the electrode mold 172 and whose width matches the material conveyor belt 11. The primary punch 151 matches the primary electrode film grid, and the size of the primary punch 151 is 0.8mm-1.2mm smaller than the size of the primary electrode film grid.

[0073] As some preferred examples, such as Figure 3 ,Figure 5 As shown, the primary punch 151 is divided into primary stamping blocks 1511 by the longitudinal and transverse grooves, the electrode film mold 172 includes tab portions 1722 and partition portions 1726, the tab portions 1722 and the partition portions 1726 are longitudinally and transversely staggered, dividing the primary electrode film grid into electrode film grids 1721, the electrode film grids 1721 cooperate with the primary stamping blocks 1511, and the size of the primary stamping blocks 1511 is 0.8mm-1.2mm smaller than the size of the electrode film grids 1721. The existence of the electrode film grids 1721 can realize the limiting of the material in the corresponding area, and cooperate with the distributing device 13 to control the consistency of the electrode film, so as to obtain an electrode film with high consistency and good uniformity; the electrode film grids 1721 cooperate with the primary stamping blocks 1511 on the primary stamping device 15, and the tab portions 1722 are arranged between the adjacent two rows of electrode film grids 1721, so as to reserve the tab space for the subsequent preparation of the electrode film tab.

[0074] As some examples, the primary stamping base 152 is further provided with positioning convex columns 153 cooperating with the electrode film mold 172.

[0075] As some examples, the electrode film mold 172 is further provided with positioning holes 1724 cooperating with the positioning convex columns 153 on the primary stamping device 15, and the existence of the positioning holes 1724 helps to cooperate with the positioning convex columns 153 on the primary stamping device 15, so as to realize the accurate pairing of the electrode film grids 1721 and the primary stamping blocks 1511.

[0076] As some examples, the number of the positioning holes 1724 is ≥2.

[0077] As some preferred examples, the number of the positioning holes 1724 is selected from 4-8.

[0078] As Figure 6 , the secondary stamping device 16 includes a secondary punch 161 and a secondary stamping base 162, the secondary stamping base 162 is fixedly connected with the secondary punch 161, and the secondary punch 161 is protruded from the secondary stamping base 162 as a whole, which helps to provide more uniform secondary stamping for the electrode film and remove the convex marks on the edges of the material after the primary stamping.

[0079] The electrode film mold 172 is further provided with positioning portions 1723 arranged on the left side and the right side of the electrode film mold 172.

[0080] As Figure 4As shown, the mold conveying belt 171 is provided with positioning cards 1711, which are arranged in pairs to form a card slot matched with the positioning part 1723 of the electrode film mold 172, and the positioning part 1723 is clamped in the card slot formed by the positioning card 1711, so as to fix the electrode film mold 172 on the mold conveying belt 171, avoid displacement of the electrode film mold 172 and loss of the limiting effect on the material, and improve the reliability and stability of the electrode tab forming device.

[0081] As some examples, the electrode film mold 172 is further provided with a placing handle 1725, which is arranged on the left side and the right side of the electrode film mold 172 respectively, and the number of the placing handle 1725 is greater than or equal to 2.

[0082] As some preferred examples, the number of the placing handle 1725 is selected from 2 to 4.

[0083] The mold placing device 173 includes a placing holding arm 1731 matched with the placing handle 1725 of the electrode film mold 172 and a first supporting base 1732, the placing holding arm 1731 can place the electrode film mold 172 on the material conveying belt 11 between the demolding layer pasting device 12 and the material distributing device 13, and the first supporting base 1732 is detachably connected with the placing holding arm 1731.

[0084] As some examples, the mold recycling device 174 includes a recycling clamping arm 1741 matched with the placing handle 1725 of the electrode film mold 172 and a second supporting base 1742, the recycling clamping arm 1741 can unload and recycle the electrode film mold 172 after the first stamping, and the second supporting base 1742 is detachably connected with the recycling clamping arm 1741.

[0085] As some examples, the current collector unwinding device 21 includes a current collector roll 211 for unwinding the current collector, a first roller pair 212 for covering the unwound current collector on the electrode film after the second stamping, and a second roller pair 213 for guiding the current collector and the electrode film after the hot stamping device 22 into the heating demolding device 23.

[0086] As some examples, the electrode tab winding device 24 includes an electrode tab roll 241 for winding the electrode tab and a third roller pair 242 for guiding the electrode tab through the heating demolding device 23.

[0087] As some examples, the electrode tab roll 241 is provided with a current collector foil detector for detecting the current collector foil.

[0088] As some examples, the pole piece forming device is further provided with a controller for receiving instructions of technicians and controlling operation of the pole piece forming device.

[0089] The pole piece forming device provided by the utility model adopts step-by-step operation, and step-by-step time and interval can be preset in the controller according to requirements.

[0090] The pole piece forming device comprises the following working procedures in the material conveying direction: a procedure in which the release layer pasting device 12 pastes a release layer, a procedure in which the mold placing device 173 places the electrode film mold 172, a material distributing procedure in which the material distributing device 13 distributes materials, a material heating procedure in which the material heating device 14 heats materials, a procedure in which the first-stage stamping device 15 stamps materials in a first stage, a procedure in which the mold recycling device 174 recycles the electrode film mold 172 after first-stage stamping, a procedure in which the second-stage stamping device 16 stamps materials in a second stage, a procedure in which the hot stamping device 22 hot-stamps the electrode film and the current collector, and a procedure in which the heated release device 23 heats and releases the primary pole piece.

[0091] The material is added to the material tank 132 of the material distributing device 13.

[0092] In one step time Δt n , the controller first controls the release layer pasting device 12 to paste a release layer on the material conveying belt 11.

[0093] In the next step time Δt n+1 , the mold placing device 173 places the electrode film mold 172 on the mold conveying belt 171 to which the release layer has been pasted, and the mold conveying belt 171 drives the electrode film mold 172 to travel synchronously with the material conveying belt 11.

[0094] In the next step time Δt n+2 , the material conveying belt 11 with the mold placing device 173 enters the partitioned material distribution position, and the material distributing device 13 distributes the preset material Mt n+2 (part of the material M distributed on the material conveying belt 11 by the material distributing device 13 in the step time Δt n+2 ) in the partitioned position on the mold conveying belt 171 to which the release layer has been pasted, and the electrode film mold 172 limits the material in the partitioned position.

[0095] In the next step time Δt n+3 , the material conveying belt 11 with the material Mt n+2 enters the working position of the material heating device 14, and the material heating device 14 starts to heat the material Mt n+2 , thereby enhancing the material Mtn+2 Slippage;

[0096] At the next step time Δt n+4 Inside, the material Mt, heated by the material heating device 14 n+2 The material is conveyed by the material conveyor belt 11 into the working position of the primary stamping device 15, and the stamping device 15 begins to press the heated material Mt. n+2 During the first-stage stamping process, the stamping pressure increases with the number of stamping cycles and remains constant after reaching the maximum pressure of the first stage.

[0097] At the next step time Δt n+5 Inside, the mold recycling device 174 recovers the electrode film mold 172 from the material conveyor belt 11, thus eliminating the need for the mold recycling device 174 to process the material Mt after the first-stage stamping. n+2 The limiting function;

[0098] At the next step time Δt n+6 Inside, the material conveyor belt 11 drives the material Mt, which is released from the limit after the first-stage stamping. n+2 The material enters the working position of the secondary stamping device 16, where it undergoes secondary stamping. After stamping, the material Mt... n+2 Forming an electrode film;

[0099] At the next step time Δt n+7 Inside, the material conveyor belt 11 drives the material Mt n+2 The current collector unwound from the current collector unwinding device 21 is combined with the current collector in the hot stamping device 22. The hot stamping device 22 performs hot stamping on the electrode film and the current collector to achieve electrode film Mt n+6 After hot stamping, the material Mt is combined with the current collector. n+2 It forms a primary electrode with the current collector.

[0100] At the next step time Δt n+8 Inside, the material conveyor belt 11 carries the primary electrode sheet into the working position of the heating and demolding device 23. The heating and demolding device 23 heats the primary electrode sheet and the corresponding material conveyor belt 11, causing the demolding layer to decompose, thereby achieving the separation of the primary electrode sheet from the material conveyor belt 11 and obtaining the electrode sheet.

[0101] Finally, the current collector unwinding device 21 connects the current collector with the electrode film Mt after the secondary stamping. n+6 The electrode is bonded together, and the electrode winding device 24 winds up the separated electrode on the material conveyor belt 11 to obtain an electrode roll.

[0102] At the same time, each process can be carried out synchronously at its respective working position within the same step time, thereby enabling continuous preparation of electrode sheets.

[0103] The pole piece prepared by the above steps is a single-sided pole piece. When a double-sided pole piece is needed, the single-sided pole piece winding tape of the single-sided pole piece is unwound from the current collector unwinding device 21, the switch is turned on, and the above operation is repeated to obtain a double-sided pole piece roll. The double-sided pole piece roll is cut to obtain a pole piece.

[0104] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, and do not represent all possible embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of the present application.

[0105] The chemical materials involved in the following examples and comparative examples are all prior art and are obtained by commercial purchase. The experimental devices, testing devices and the like involved in the following examples and comparative examples are all conventional devices in the art, and there is no special requirement or limitation.

[0106] Example 1

[0107] The material with a NCM ternary:CNT:PEFT:PVDF ratio of 84:1:10:5 is stirred and premixed for 1 h, and is subjected to fiberization treatment by air flow fiberization for 2 h. A 10 μm single-sided polycarbonate film containing polyacrylate glue is used as a release layer, the material conveying belt 11 is set to a step speed of 1 min / time, the heating temperature is 90°C, the first-stage punching rate is 100 times / min, and the first-stage punching pressure is increased from X1=0.2 Mpa to X=1000 Mpa according to the rule Xn+1=Xn+100, wherein n represents the n th punching, and the first-stage punching pressure is maintained at 1000 Mpa when n=7. The second-stage punching rate is 20 times / min, and the second-stage punching pressure is increased from Y1=300 Mpa to Y=3000 Mpa according to the rule Yq+1=Yq+300, wherein q represents the q th punching, and the second-stage punching pressure is maintained at 3000 Mpa when q=5. When hot punching, the impact composite pressure is 100 Mpa, the punching speed is selected from 40 times / min, when hot pressing, the hot pressing composite pressure is selected from 500 Mpa, the hot pressing temperature is selected from 100°C, the hot pressing time is selected from 30 s, when releasing, the release temperature is selected from 100°C, the release time is selected from 30 s, and after the release time ends, the temperature is quickly reduced to room temperature. n+1 n q+1 q

[0108] ​​​​The switch is turned on, and the release layer sticking device 12 sticks the single-sided polycarbonate film containing polyacrylate glue on the material conveying belt 11 at a step time of 1 min, the mold placing device 173 places the electrode film mold 172 on the mold conveying belt 17, the material distributing device 13 distributes the material into the electrode film mold 172, and then passes through the material heating device 14, the first-stage stamping device 15, the second-stage stamping device 16, the fluid unwinding device 21, the hot stamping device 22, the release device 23, and the electrode piece winding device 24. After 100 meters are wound, the stop button is pressed, the electrode piece winding device 24 stops winding after detecting the current collector light foil, and a single-sided electrode piece is obtained.

[0109] The single-sided electrode piece after winding is fed to the current collector unwinding device 21 and the tape is connected. The switch is turned on, and the above operation is repeated to complete the double-sided film preparation to obtain an electrode piece roll. The electrode piece roll is cut into slices to make a battery.

[0110] Example 2

[0111] The preparation method is the same as that in Example 1, except that the first-stage stamping speed is 49 times / min, the material conveying belt 11 advances at a speed of 3 min / time, and the equipment stops after all operations are completed until the material conveying belt 11 advances one step and then continues to work.

[0112] Example 3

[0113] The preparation method is the same as that in Example 1, except that during the second-stage stamping, the second-stage stamping pressure is maintained unchanged, and the second-stage stamping pressure is 3500 MPa.

[0114] Example 4

[0115] The preparation method is the same as that in Example 1, except that during the hot stamping, the impact composite pressure is 400 MPa.

[0116] Example 5

[0117] The preparation method is the same as that in Example 1, except that during the hot stamping, the hot stamping composite temperature is 180°C.

[0118] Example 6

[0119] The preparation method is the same as that in Example 1, except that the temperature during the release is selected from 180°C.

[0120] Comparative Example 1

[0121] The same material as in Example 1 is used, except that multiple roller pressing is used for film preparation. The main roller pressure is 3000 MPa, and the roller pressing is performed 13 times to obtain a single-sided electrode film with a thickness consistent with that in Example 1. After the two single-sided electrode films are prepared, the roller pressing is used to composite the current collector to obtain a double-sided electrode film. The film is cut into slices to make a battery.

[0122] Comparative Example 2

[0123] The preparation method is the same as Example 1, except that the secondary stamping is not performed.

[0124] Comparative Example 3

[0125] The preparation method is the same as Example 1, except that the mold is not used.

[0126] Comparative Example 4

[0127] The preparation method is the same as Example 1, except that the hot stamping is not performed.

[0128] Comparative Example 5

[0129] The preparation method is the same as Example 1, except that only 5 primary stampings are performed.

[0130] Comparative Example 6

[0131] The preparation method is the same as Example 1, except that the primary stamping pressure is fixed and maintained at 150 MPa.

[0132] Comparative Example 7

[0133] The preparation method is the same as Example 1, except that the secondary stamping rate is 200 times / min.

[0134] Comparative Example 8

[0135] The preparation method is the same as Example 1, except that the single-sided polycarbonate film containing polyacrylate glue is not pasted as a release layer.

[0136] Comparative Example 9

[0137] The preparation method is the same as Example 1, except that only 3 stampings are performed during the secondary stamping.

[0138] Comparative Example 10

[0139] The preparation method is the same as Example 1, except that the hot stamping is performed at a hot pressing composite pressure of 10 MPa.

[0140] Comparative Example 11

[0141] The preparation method is the same as Example 1, except that the release temperature is selected from 65°C.

[0142] Test Test

[0143] The ion impedance test equipment in the example is an Autolab Nova2.1 electrochemical workstation;

[0144] The sample battery cell made of the pole piece in the example has a design capacity of 800 mAh calculated according to the material active substance amount and the material gram capacity. The 1C cycle is to charge to 4.2 V by 0.8 A CC-CV and then discharge to 2.7 V by 0.8 A, and the capacity of each discharge is recorded. The capacity retention rate of each discharge capacity / initial discharge capacity is the 1C cycle capacity retention rate.

[0145] The test method for the 2C / 0.33C capacity ratio is that the capacity obtained by 0.8 A (i.e. 1C) CC-CV to 3.95 V and 1.6 A discharge to 2.7 V is the 2C capacity, the capacity obtained by 0.8 A (i.e. 1C) CC-CV to 3.95 V and 0.264 A (i.e. 0.33C) discharge to 2.7 V is the 0.33C capacity, and the 2C capacity / 0.33C capacity is the 2C / 0.33C capacity ratio.

[0146] The test results are shown in Table 1.

[0147] Table 1

[0148]

[0149] From Examples 1-6 and Comparative Examples 1-11, it can be observed that Examples 1-6 exhibit better ion impedance, 2C / 0.33C capacity ratio and 1C cycle 100 times capacity retention rate than Comparative Examples 1-11, and the single-sided electrode film thickness difference of Examples (≤3) is also better than that of the comparative examples (≥5), which indicates that the pole piece prepared by the present scheme can effectively avoid the phenomenon of electrode film internal cavity, cracking or unevenness, thereby optimizing the pole piece resistance, improving the capacity retention capability, and optimizing the cycle performance.

[0150] From Example 1 and Comparative Example 1, it can be observed that when the pole piece is prepared by multiple rolling, the ion impedance, 2C / 0.33C capacity ratio and 1C cycle 100 times capacity retention rate of Comparative Example 1 are all weaker than those of Example 1, which may be because, compared with the present scheme, the multiple rolling of Comparative Example 1 may exist uneven situation, thereby affecting the pole piece performance.

[0151] We further discuss the effect of primary stamping and secondary stamping on optimizing the present scheme. From Example 1 and Comparative Example 2, it can be observed that when no secondary stamping is performed, Comparative Example 2 has an uneven appearance and performance far inferior to that of Example 1, which indicates that primary stamping and secondary stamping are indispensable for optimizing the electrode film structure and obtaining a pole piece with good performance.

[0152] In Comparative Example 3, we discussed the role of the pole piece mold. The presence of the pole piece mold, on the basis of achieving the preliminary shaping of the electrode film, realized the consistency control of the thickness and performance of the pole piece. When the pole piece mold is not used, Comparative Example 3 shows an irregular appearance, and the single-sided electrode film thickness is lower than that of Example 1, and further affects the capacity retention ability of the pole piece.

[0153] Similarly, hot pressing is also an important step in this scheme. In Comparative Example 4, we only performed stamping without hot pressing when the composite electrode film was combined with the current collector. At this time, the current collector fell off. This may be because the hot pressing process helps to promote the adhesion of the adhesive in the electrode film and the current collector. Therefore, when hot pressing is not performed, the current collector falls off.

[0154] In Example 1, Comparative Examples 5-7, we discussed the influence of the first and second stamping conditions on the performance of the electrode film and even the pole piece. It can be observed that Comparative Examples 5-7 all show worse ion impedance, 2C / 0.33C capacity ratio, and cycle capacity retention rate than Example 1. This shows that the conditions of the first and second stamping (including stamping rate, stamping times, and stamping pressure) are also one of the factors affecting the electrode film and the pole piece. When the first stamping frequency is not selected from 10-1000 times / min, the first stamping pressure is not selected from 1-2000 Mpa, the second stamping frequency is not selected from 5-100 times / min, and the second stamping pressure is not selected from 50-8000 Mpa, the electrode film may appear uneven, thereby affecting the performance of the pole piece.

[0155] In Example 1, Comparative Example 8, we observed that the lack of release layer also affects the performance of the electrode film and the pole piece. Compared with Example 1, when the release layer is not set (Comparative Example 8), the material is pressed on the conveying table and is difficult to physically separate under the action of the first and second stamping. After forced separation, Comparative Example 8 exhibits a serious cracking phenomenon.

[0156] In Example 1, Comparative Examples 9-10, we discussed the influence of the hot stamping conditions on the performance of the pole piece when the composite electrode film is combined with the current collector by hot stamping. It can be observed that when the stamping composite times are 3 or the hot stamping composite pressure is 10 Mpa, the performance of the pole piece of Comparative Examples 9 and 10 is greatly affected. Comparative Example 10 directly shows the current collector falling off. This may be because too few stamping composite times (<5 times) and too low hot stamping composite pressure (<50 Mpa) cannot guarantee the full adhesion of the current collector and the electrode film.

[0157] Further, we also discussed the influence of the demolding temperature on the performance of the electrode, when the demolding temperature is selected from 65℃, the electrode prepared by Comparative Example 11 has adhesive film on the surface, which may be because the demolding temperature of 65℃ cannot achieve the complete pyrolysis of the adhesive film, thereby affecting the results of Comparative Example 11.

[0158] The frequency of stamping will affect the flow rate of the material in the electrode mold, and in turn affect the performance of the electrode film. From Examples 1-2, we can observe that when the primary stamping speed is selected from 100 times / min, Example 1 exhibits better ion impedance, capacity retention capability and cycle performance than Example 2, which may be because when the stamping frequency is selected from 50-200 times / min, the material is more evenly distributed in the electrode mold, thereby improving the performance of the electrode film and optimizing the electrode resistance, so Example 1 exhibits better performance.

[0159] When primary stamping and secondary stamping are performed, the stamping pressure is regularly increased from small to large, which helps to obtain an electrode film with better uniformity and mechanical strength, thereby optimizing the performance of the electrode, so in Examples 1, 3, we observe that Example 1 with a regular change of Y q+1 =2Y q , Y1=300Mpa and Y≤3000Mpa has better impedance and cycle performance than Example 3.

[0160] In this scheme, we realize the compounding of the current collector and the electrode film by hot stamping, so in Examples 1, 4-5, we further explore the conditions during hot stamping, and it can be observed that Example 1 exhibits better ion impedance, capacity retention capability and cycle performance than Examples 4, 5, which may be because stamping compounding can cause the current collector and the solid-state electrode film to deform slightly and thereby highly adhere, while hot pressing compounding can bond the binder in the electrode film with the current collector. When the impact compounding pressure is selected from 50-350Mpa and the hot pressing compounding temperature is selected from 90-150℃, it helps to optimize the mechanical properties of the electrode and further improve the bonding strength between the electrode film and the current collector on the basis of realizing the full combination of the electrode film and the current collector, thereby optimizing the performance of the electrode.

[0161] To realize the rapid physical separation of the electrode and the material conveying belt 11, this scheme is provided with a demolding layer, which rapidly decomposes under certain temperature conditions to realize the separation of the electrode and the material conveying belt 11, so in Examples 1, 6, we discuss the different performances of the electrode brought about by different demolding temperatures, and it can be observed that Example 1 exhibits better comprehensive performance than Example 6 under a demolding temperature of 135℃, which may be because when the temperature for heating the demolding layer is selected from 120-150℃, it can better protect the substances in the electrode film, thereby improving the performance of the electrode.

[0162] Any combination of the technical features in the above-described embodiments can be made, and for the sake of brevity, not all possible combinations are described, however, it is to be understood that the scope of protection includes all possible combinations of the technical features described herein. Although the embodiments of the present application have been shown and described above, it should be understood by those having ordinary skill in the art that such embodiments are presented by way of example only and not by way of limitation, and that modifications, substitutions, changes, and equivalents of the embodiments could occur to those skilled in the art in the range of the present application. Furthermore, those skilled in the art could combine and combine the features of different embodiments or examples described in the specification, or features of different embodiments or examples, without mutual contradiction.

Claims

1. A pole piece forming device, characterized by, The application relates to an electrode sheet forming device, which comprises a material conveying belt (11) and a demolding layer pasting device (12), a material distributing device (13), a material heating device (14), a first-stage stamping device (15), a second-stage stamping device (16), a hot stamping device (22) and a heated demolding device (23) arranged on the material conveying belt (11) in sequence along a material conveying direction. The electrode sheet forming device is further provided with a mold conveying assembly (17), which comprises an electrode film mold (172), a mold conveying belt (171), a mold placing device (173) and a mold recycling device (174); the mold placing device (173) is used for placing the electrode film mold (172) on the material conveying belt (11) in front of the material distributing device (13); the mold conveying belt (171) is located at the two side edges of the material conveying belt (11) and is parallel to or higher than the horizontal plane of the material conveying belt (11) in the horizontal direction; the mold conveying belt (171) is used for carrying the electrode film mold (172) to pass through the material distributing device (13), the material heating device (14) and the first-stage stamping device (15) in sequence; and the mold recycling device (174) is used for recycling the electrode film mold (172) after the first-stage stamping. The electrode sheet forming device is further provided with a current collector unwinding device (21) and an electrode sheet winding device (24); the current collector unwinding device (21) is used for unwinding the current collector and combining the current collector with the electrode film passing through the hot stamping device (22); and the electrode sheet winding device (24) is used for winding the electrode sheet after the demolding of the hot stamping device (22). The demolding layer has a thickness range of 0.1-20 microns.

2. The pole piece forming device of claim 1, wherein The demolding layer is composed of a carrier layer and a glue layer, and the glue layer is arranged on any one side of the carrier layer.

3. The pole piece forming device of claim 2, wherein, The material of the carrier layer can be selected from one or more of polyethylene, polypropylene and polycarbonate.

4. The pole piece forming apparatus of claim 3, wherein The material of the glue layer can be selected from one of polyacrylate glue and polyurethane glue.

5. The pole piece forming apparatus of claim 3, wherein When the mold conveying belt (171) is higher than the material conveying belt (11) in the horizontal direction, the height range is 0.5-1 mm.

6. The pole piece forming device of claim 1, wherein The material distributing device (13) comprises a material distributing port (131) and a material tank (132), and the material tank (132) is fixedly connected with the material distributing port (131).

7. The pole piece forming device of claim 1, wherein The first-stage stamping device (15) comprises a first-stage stamping head (151) and a first-stage stamping base (152), the first-stage stamping base (152) is fixedly connected with the first-stage stamping head (151), the first-stage stamping head (151) protrudes from the first-stage stamping base (152), the shape of the first-stage stamping head (151) is matched with the electrode film mold (172) and the first-stage stamping head (151) is used for carrying out first-stage stamping on the material in the electrode film mold (172).

8. The pole piece forming device of claim 1, wherein The electrode film mold (172) is provided with a first-stage electrode film grid communicating with the front and back surfaces, the width of the first-stage electrode film grid is matched with the material conveying belt (11); the first-stage stamping head (151) is matched with the first-stage electrode film grid, and the size of the first-stage stamping head (151) is smaller than the size of the first-stage electrode film grid by 0.8-1.2 mm. ​ 9. The pole piece forming device of claim 8, wherein, The primary punch (151) is divided into a plurality of primary stamping blocks (1511) by longitudinal and transverse grooves; the electrode film mold (172) comprises tab portions (1722) and partition portions (1726), the tab portions (1722) and the partition portions (1726) are staggered longitudinally and transversely, and divide a primary electrode film grid into a plurality of electrode film grids (1721), the electrode film grids (1721) are matched with the primary stamping blocks (1511), and the size of the primary stamping blocks (1511) is smaller than the size of the electrode film grids (1721) by 0.8-1.2 mm.

10. The pole piece forming device of claim 8, wherein The primary stamping base (152) is provided with positioning protrusions (153) matched with the electrode film mold (172).

11. The pole piece forming device of claim 1, wherein The electrode film mold (172) is provided with positioning holes (1724) matched with the positioning protrusions (153) of the primary stamping device (15).

12. The pole piece forming device of claim 11, wherein, The number of the positioning holes (1724) is not less than 2.

13. The pole piece forming device of claim 11, wherein, The number of the positioning holes (1724) is 4-8.

14. The pole piece forming device of claim 1, wherein, The secondary stamping device (16) comprises a secondary punch (161) and a secondary stamping base (162), the secondary stamping base (162) is fixedly connected with the secondary punch (161), and the secondary punch (161) protrudes from the secondary stamping base (162) as a whole.

15. The pole piece forming device of claim 1, wherein, The electrode film mold (172) is provided with positioning portions (1723) located on the left side and the right side of the electrode film mold (172).

16. The pole piece forming device of claim 1, wherein The mold conveying belt (171) is provided with positioning clamps (1711) appearing in pairs to form clamping grooves matched with the positioning portions (1723) of the electrode film mold (172), and the positioning portions (1723) are clamped in the clamping grooves formed by the positioning clamps (1711).

17. The pole piece forming device of claim 1, wherein, The electrode film mold (172) is provided with placing handles (1725) located on the left side and the right side of the electrode film mold (172) respectively, and the number of the placing handles (1725) is not less than 2.

18. The pole piece forming device of claim 17, wherein, The number of the placing handles (1725) is 2-4. The mold placing device (173) comprises placing holding arms (1731) matched with the placing handles (1725) of the electrode film mold (172) and a first supporting base (1732) detachably connected with the placing holding arms (1731).

19. The pole piece forming device of claim 1, wherein, The mold recycling device (174) comprises recycling clamping arms (1741) matched with the placing handles (1725) of the electrode film mold (172) and a second supporting base (1742) detachably connected with the recycling clamping arms (1741).

20. The pole piece forming device of claim 1, wherein, The current collector unwinding device (21) comprises a current collector roll (211), a first roller pair (212) and a second roller pair (213), the current collector roll (211) is used for unwinding the current collector, and the second roller pair (213) is used for guiding the current collector and the electrode film after being compounded by the hot stamping device (22) to enter the heating demolding device (23).

21. The pole piece forming device according to claim 1, said pole piece winding device (24) comprising a pole piece roll (241) and a third roller pair (242) for guiding the pole piece past the heated demolding device (23), the pole piece roll (241) for winding the pole piece.

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