Low-warping-rate single-sided pole piece and preparation method thereof, laminated battery cell and plane compacting and shaping mechanism

Abstract

The invention belongs to the technical field of batteries, and relates to a preparation method of a low-warping-rate single-sided pole piece, a laminated battery cell and a plane compacting and shaping mechanism. The invention discloses a preparation method of a low-warping-rate single-sided pole piece. The preparation method comprises the following steps: loading an active material on one side of a current collector and forming a coating region and a non-coating region to obtain a single-sided pole piece substrate with the coating region on one side; sequentially carrying out plane compaction and plane shaping on the single-sided pole piece base material to obtain a plane-shaped single-sided pole piece; the deformation of the single-sided pole piece base material in the shaping process is less than or equal to 10%, the single-sided pole piece subjected to plane shaping is a single-sided pole piece with a low warping rate, and the warping rate of the single-sided pole piece is less than or equal to 1.6%. The laminated battery cell prepared on the basis of the single-sided pole piece has relatively good stability and electrochemical performance.

Description

Technical Field

[0001] This invention belongs to the field of battery technology and relates to a single-sided electrode with low warpage and its preparation method, a stacked battery cell, and a planar compaction and shaping mechanism. Background Technology

[0002] With the rapid development of new energy vehicles and the increasing demand for lightweight power battery systems, higher requirements are being placed on the quality and energy density of power batteries. Currently, reducing the proportion of ineffective materials in the battery at the cell design level is a very effective approach. For batteries with stacked structure designs, replacing the outermost double-sided coated electrode with a single-sided coated electrode is also gradually becoming a design trend. However, during the rolling process, single-sided electrodes may exhibit significant curvature or torsional deformation due to the different stresses on both sides of the current collector, severely affecting the winding / stacking process and thus limiting their design and application range.

[0003] To address these issues, the industry has proposed several solutions, including non-rolling of single-sided coated positive electrode rolls, non-rolling of single-sided coated negative electrode rolls, coating the uncoated side of the current collector (copper or aluminum foil) with low-density materials (such as carbon black, polystyrene microspheres, or hollow silica spheres) before rolling, adding a support layer (inorganic oxide or polymer material) to the other side of the current collector before rolling, and first rolling to prepare a double-sided electrode sheet before removing the active material coating on its first surface. However, these solutions often sacrifice the energy density of the cell or pose significant cell safety risks, resulting in slow application. Therefore, a new technical solution is urgently needed that can effectively solve the warping / bending problem after single-sided electrode sheet compaction without sacrificing cell energy density or compromising safety, thereby improving the production efficiency and product quality of stacked batteries. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned problems in the prior art by proposing a method for preparing a single-sided electrode with low warpage. This method involves placing a single-sided electrode substrate loaded with active material in a planar compaction and shaping mechanism and sequentially performing planar compaction and planar shaping to obtain a planar shaped single-sided electrode. This single-sided electrode has low warpage, thereby improving the performance of stacked cells.

[0005] One objective of this invention is achieved through the following technical solution:

[0006] A method for preparing a single-sided electrode with low warpage includes: loading an active material onto one side of the current collector and forming a coated area and an uncoated area to obtain a single-sided electrode substrate with a coated area on one side;

[0007] The single-sided electrode substrate is sequentially subjected to planar compaction and planar shaping to obtain a single-sided electrode after planar shaping.

[0008] The deformation of the single-sided electrode substrate during the planar shaping process is ≤10%, and the single-sided electrode after planar shaping is a low-warpage single-sided electrode with a warpage of ≤1.0%.

[0009] Preferably, the planar compaction process includes: a planar compactor head compacting the single-sided electrode substrate in a direction perpendicular to the surface of the single-sided electrode substrate, wherein the length of the planar compactor head is greater than the width of the coating area of ​​the single-sided electrode substrate, thereby obtaining a single-sided electrode after planar compaction.

[0010] Further preferably, the compaction time of the plane is 1 to 10 seconds, and the pressure of the plane indenter is 50 to 500 MPa.

[0011] Further preferably, the planar compaction process includes: the single-sided electrode substrate is conveyed to the planar compaction platform of the planar compaction component by the conveying component and then paused; the driving component drives the planar pressure head to perform planar compaction in a direction parallel to the width of the single-sided electrode substrate, and the length of the planar pressure head is greater than the width of the coating area of ​​the single-sided electrode substrate; after the planar compaction is completed, the planar pressure head moves up to obtain the planar compacted single-sided electrode; after the planar pressure head is completely reset, the conveying component starts running again, driving the single-sided electrode to move; the planar compaction process and the single-sided electrode movement process are repeated.

[0012] More preferably, the compaction time of the plane is 2 to 5 seconds, and the pressure of the plane indenter is 50 to 150 MPa.

[0013] Further preferred, the width of the flat pressure head is 80-120mm.

[0014] In a further preferred embodiment, during continuous planar compaction, the distance between the edges of two adjacent single-pass compaction zones is 1–5 mm.

[0015] In a further preferred embodiment, during continuous planar compaction, the distance between the edges of two adjacent single-pass compaction zones is 2–3 mm.

[0016] Preferably, the planar compaction process and the planar shaping process are carried out in a planar compaction and shaping mechanism.

[0017] Preferably, the planar shaping process includes: the single-sided electrode sheet after planar compaction enters the shaping component, the shaping component includes at least two sets of continuous rolling mechanisms connected in series, each set of rolling mechanisms includes at least one heating roller that contacts the single-sided electrode sheet; the rolling mechanism is a double-roller and / or four-roller mechanism, and adjacent rolling mechanisms are staggered to keep at least one-quarter of the surface of the heating roller in contact with the single-sided electrode sheet, thereby obtaining the single-sided electrode sheet after planar shaping.

[0018] More preferably, the temperature of the heating roller in the roller pressing mechanism is 50-130°C.

[0019] More preferably, the temperature of the heating roller in the roller pressing mechanism is 110-130°C.

[0020] Further preferably, in the planar shaping process, the deformation of a single-sided electrode is ≤5%.

[0021] More preferably, during the planar shaping process, the deformation of a single-sided electrode is ≤2%.

[0022] Further preferably, the shaping component includes four sets of continuous rolling mechanisms connected in series, which sequentially include a first double-roller mechanism, a second double-roller mechanism, a first four-roller mechanism, and a second four-roller mechanism; wherein the first double-roller mechanism, the second double-roller mechanism, the first four-roller mechanism, and the second four-roller mechanism are staggered, so that the single-sided electrode sheet after planar compaction contacts one-quarter of the surface of the heating roller in the first double-roller mechanism, the single-sided electrode sheet contacts half of the surface of the heating roller in the second double-roller mechanism, the single-sided electrode sheet contacts half of the surface of the heating roller in the first four-roller mechanism, and the single-sided electrode sheet contacts half of the surface of the heating roller in the second four-roller mechanism.

[0023] More preferably, in the four sets of continuous rolling mechanisms connected in series, the deformation of a single-sided electrode sheet after passing through any one of the rolling mechanisms is less than 2%.

[0024] Preferably, the warpage of the single-sided electrode sheet after planar shaping is ≤1.0%.

[0025] Further preferably, the warpage of the single-sided electrode sheet after planar shaping is ≤0.5%.

[0026] Preferably, the current collector includes either aluminum foil or copper foil.

[0027] Further preferably, the current collector used in the negative electrode single-sided electrode is copper foil, and the current collector used in the positive electrode single-sided electrode is aluminum foil.

[0028] Preferably, the thickness of the coating area is 45–200 μm, the thickness of the current collector is 4.5–20 μm, and the thickness of the single-sided electrode after planar shaping is 35–150 μm.

[0029] Preferably, the planar shaping process further includes a cooling process, which includes: after the planar shaped single-sided electrode sheet leaves the shaping component, it is conveyed to the water-cooling roller of the cooling component for cooling, thus obtaining a planar shaped single-sided electrode sheet.

[0030] Further preferably, the single-sided electrode sheet after planar shaping maintains contact with at least one-quarter of the surface of the water-cooled roller.

[0031] Preferably, the compaction density of the single-sided electrode after planar compaction is 90-99% of the compaction density of the single-sided electrode after planar shaping.

[0032] Further optimization is that the compaction density of the single-sided electrode after planar compaction is 95-98.5% of the compaction density of the single-sided electrode after planar shaping.

[0033] Preferably, the single-sided electrode sheet after planar shaping includes a positive single-sided electrode sheet and a negative single-sided electrode sheet; the double-sided electrode sheet includes a positive double-sided electrode sheet and a negative double-sided electrode sheet.

[0034] Both sides of the double-sided electrode are loaded with active material, and it is made by the planar compaction and shaping step in the preparation method of single-sided electrode, or by the traditional rolling method; the traditional rolling method includes one or more of the following: hydraulic rolling mill rolling, gas-liquid booster pump pressurization, and pressurized electrode rolling mill.

[0035] Further optimization involves combining the single-sided electrode sheet after planar shaping with the double-sided electrode sheet to assemble a stacked cell, with the single-sided electrode sheet on the outermost side.

[0036] Further preferably, the compaction density of the single-sided positive electrode sheet is 90-99% of the compaction density of the double-sided positive electrode sheet;

[0037] The compaction density of the single-sided negative electrode sheet is 90-99% of the compaction density of the double-sided negative electrode sheet.

[0038] More preferably, the compaction density of the single-sided positive electrode sheet is 95-98.5% of the compaction density of the double-sided positive electrode sheet;

[0039] The compaction density of the single-sided negative electrode sheet is 95-98.5% of the compaction density of the double-sided negative electrode sheet.

[0040] Preferably, the method for preparing the single-sided electrode sheet includes: conveying the electrode sheet substrate sequentially from the unwinding component to the planar compaction component, the shaping component, the cooling component, and then to the winding component via a conveying component.

[0041] The second objective of this invention is achieved through the following technical solution:

[0042] A single-sided electrode with low warpage is prepared by the above-described method.

[0043] Preferably, the warpage of the low-warpage single-sided electrode is ≤1.0%.

[0044] Further preferably, the warpage of the low-warpage single-sided electrode is ≤0.5%.

[0045] The third objective of this invention is achieved through the following technical solution:

[0046] A laminated battery cell includes a central unit and two single-sided electrodes disposed on both sides thereof, the three being separated by a separator; the central unit includes a laminated structure of N double-sided electrodes and N-1 separators, with adjacent double-sided electrodes separated by separators and having opposite polarities;

[0047] The compaction density of the single-sided positive electrode sheet is 90-99% of the compaction density of the double-sided positive electrode sheet;

[0048] The compaction density of the single-sided negative electrode sheet is 90-99% of the compaction density of the double-sided negative electrode sheet.

[0049] In the middle and later stages of the manufacturing process of laminated cells, the cells are usually pressurized, with the single-sided electrodes on both sides experiencing the highest pressure. This invention adjusts the compaction density of the single-sided electrodes, which is beneficial for electrolyte wetting of the single-sided electrodes on both sides and for optimizing the electrode interface.

[0050] Preferably, the single-sided electrode includes a positive single-sided electrode and a negative single-sided electrode; the double-sided electrode includes a positive double-sided electrode and a negative double-sided electrode.

[0051] The compaction density of the positive single-sided electrode sheet is 90-99% of the compaction density of the positive double-sided electrode sheet; the compaction density of the negative single-sided electrode sheet is 90-99% of the compaction density of the negative double-sided electrode sheet.

[0052] Preferably, the single-sided electrode is prepared by the above-described method for preparing a single-sided electrode with low warpage.

[0053] Preferably, the double-sided electrode is prepared by the above-described method for preparing a single-sided electrode with low warpage.

[0054] Preferably, the double-sided electrode sheet is produced by a traditional rolling process;

[0055] The traditional rolling methods include one or more of the following: hydraulic rolling mill, pneumatic-hydraulic booster pump pressurization, and pressurized electrode rolling mill.

[0056] The fourth objective of this invention is achieved through the following technical solution:

[0057] A planar compaction and shaping mechanism includes, in sequence, an unwinding component, a first conveying component, a planar compaction component, a second conveying component, a shaping component, a cooling component, a third conveying component, and a winding component; the first conveying component, the second conveying component, and the third conveying component work simultaneously to drive the electrode sheet to move from the unwinding component to the winding component;

[0058] The planar compaction component includes a driving component, a planar compaction head, and a planar compaction platform;

[0059] The shaping component includes at least two sets of continuous rolling mechanisms connected in series, each set of rolling mechanisms including at least one heating roller that contacts the electrode; the rolling mechanism is a double-roller and / or four-roller mechanism, and adjacent rolling mechanisms are staggered to keep at least one-quarter of the surface of the heating roller in contact with the electrode.

[0060] Preferably, the operation of the planar compaction and shaping mechanism includes: the first conveying component conveys the electrode sheet from the unwinding component to the planar compaction platform of the planar compaction component and then pauses; the driving component drives the planar pressure head to press down and maintain pressure; after the planar compaction of the electrode sheet is completed, the planar pressure head moves up; after the planar pressure head is fully reset, the conveying component restarts, driving the electrode sheet to move towards the winding component; the planar compaction process and the electrode sheet movement process are repeated to continuously compact the electrode sheet to obtain a planar compacted electrode sheet;

[0061] After being compacted, the electrode sheet is conveyed to the shaping component via the second conveying component;

[0062] The electrode sheet maintains contact with one-quarter of the surface of the heating roller in each group of continuous rolling mechanisms in the shaping component;

[0063] After leaving the shaping component, the electrode sheet directly enters the cooling component, is cooled by the water-cooled roller, and is then conveyed by the third conveying component to the winding component for winding.

[0064] Preferably, the conveying component includes one or more of an active roller, a passive roller, and an auxiliary pulley system.

[0065] Preferably, the conveying components include a first conveying component, a second conveying component, and a third conveying component. The first conveying component is connected to an unwinding component and a planar compaction component. The second conveying component is connected to a planar compaction component and a shaping component. The third conveying component is connected to a cooling component and a winding component.

[0066] In a further preferred embodiment, the first conveying component pauses after conveying the electrode sheet from the unwinding component to the flat compaction platform of the flat compaction component to perform the flat compaction process. The driving component drives the flat pressure head to press down and maintain pressure. Subsequently, the flat pressure head moves up. After the flat pressure head is fully reset, the conveying component restarts, driving the electrode sheet to move towards the winding component. The flat compaction process and the electrode sheet movement process are repeated to continuously flat compact the electrode sheet, resulting in a flat compacted electrode sheet.

[0067] Furthermore, the process from the start of the downward pressure of the planar pressure head to its complete reset is the planar compaction process, during which the drive roller stops conveying.

[0068] In a further preferred embodiment, the planar pressure head compacts the single-sided electrode substrate in a direction perpendicular to the surface of the single-sided electrode substrate.

[0069] More preferably, the length of the planar indenter is less than the width of the electrode; the electrode surface includes a coated area and an uncoated area, wherein the coated area is the area after the slurry is applied and dried; and the length of the planar indenter is greater than the width of the coated area on the electrode surface.

[0070] Further preferably, the flat-compacted electrode sheet is conveyed to the shaping component via the second conveying component. The shaping component includes four sets of continuous rolling mechanisms connected in series, namely a first double-roller mechanism, a second double-roller mechanism, a first four-roller mechanism, and a second four-roller mechanism, and each of the four rolling mechanisms is equipped with a heating roller. The first double-roller mechanism, the second double-roller mechanism, the first four-roller mechanism, and the second four-roller mechanism are staggered, so that the single-sided electrode sheet contacts one-quarter of the surface of the heating roller in the first double-roller mechanism, one-half of the surface of the heating roller in the second double-roller mechanism, one-half of the surface of the heating roller in the first four-roller mechanism, and one-half of the surface of the heating roller in the second four-roller mechanism, thereby obtaining a flat-shaped electrode sheet.

[0071] In an even more preferred embodiment, after the flattened electrode sheet leaves the second four-roll mechanism, it directly enters the cooling component, is cooled by the water-cooled roller, and is then conveyed by the third conveying component to the winding component for winding.

[0072] Compared with the prior art, the present invention has the following beneficial effects:

[0073] 1. This invention involves placing a single-sided electrode substrate loaded with active material in a planar compaction and shaping mechanism to sequentially perform planar compaction and planar shaping to obtain a planar shaped single-sided electrode. This single-sided electrode has a low warpage rate. The single-sided electrode is combined with a double-sided electrode to form a stacked cell, thereby effectively improving battery performance.

[0074] 2. The single-sided electrode sheet prepared by the method of the present invention can replace the two double-sided electrodes on the outermost side of the battery cell, thereby reducing the weight of the battery cell and increasing the energy density.

[0075] 3. By adjusting the compaction density variation of the single-sided electrode in the planar compaction and shaping mechanism, this invention can effectively reduce the warpage, which is beneficial to the electrolyte wetting of the single-sided electrode on both sides of the stacked cell and the optimization of the electrode interface. This improves the uniformity of internal stress and current distribution in the cell and enhances the overall dynamic performance and structural stability of the cell. Attached Figure Description

[0076] Figure 1 This is a schematic diagram of the planar compaction and shaping mechanism used in this invention.

[0077] Figure 2 This is a schematic diagram of the appearance of the stacked battery cell of the present invention.

[0078] Figure 3 This is a schematic diagram of the stacked battery cell structure in Embodiment 2 of the present invention.

[0079] Figure 4 This is a schematic diagram of the stacked battery cell structure in Embodiment 3 of the present invention.

[0080] In the diagram, 10 is the outer shell; 11 is the diaphragm; 2 is the electrode sheet; 21 is the negative single-sided electrode sheet; 22 is the negative double-sided electrode sheet; 23 is the positive double-sided electrode sheet; 24 is the positive single-sided electrode sheet; 251 is the positive electrode tab; 252 is the negative electrode tab; 31 is the unwinding component; 32 is the passive roller; 33 is the active roller; 34 is the auxiliary pulley block; 351 is the drive component; 352 is the flat pressure head; 353 is the flat compaction platform; 361 is the ambient temperature roller; 362 is the heated roller; 371 is the water-cooled roller; and 38 is the winding component. Detailed Implementation

[0081] The technical solution of the present invention will be further described and illustrated below through specific embodiments. It should be understood that the specific embodiments described herein are only for the purpose of helping to understand the present invention and are not intended to limit the present invention.

[0082] Unless otherwise specified, the raw materials used in the embodiments of the present invention are all commonly used in the art, and the methods used in the embodiments are all conventional methods in the art.

[0083] In this article, a single-sided electrode refers to an electrode with a paste coating on only one side, while a double-sided electrode refers to an electrode with a paste coating on both sides.

[0084] In this article, positive electrode slurry / negative electrode slurry is referred to as positive electrode slurry or negative electrode slurry.

[0085] The preparation method of the positive electrode slurry includes: mixing lithium cobalt oxide, conductive carbon black Super P, carbon nanotubes (CNTs) and polyvinylidene fluoride (PVDF) in a mass ratio of 97.5:0.8:0.2:1.5, adding N-methylpyrrolidone solvent to prepare a positive electrode slurry with a solid content of 75 wt%; and then performing vacuum degassing treatment for 30 min under a negative pressure of -85 kPa before use.

[0086] The preparation method of the negative electrode slurry includes: mixing silicon-carbon negative electrode (silicon:carbon = 1:19), conductive carbon black Super P, vapor-grown carbon fiber VGCF and styrene-butadiene rubber SBR in a mass ratio of 95.5:1.5:0.5:2.5, adding deionized water solvent to prepare a negative electrode slurry with a solid content of 50wt%; and then performing vacuum degassing treatment for 30min under a negative pressure of -85kpa ​​before use.

[0087] In this paper, the current collector used for the negative single-sided / double-sided electrode is copper foil, and the current collector used for the positive single-sided / double-sided electrode is aluminum foil.

[0088] In this paper, planar compaction refers to the process of compressing coated and dried battery electrodes under certain temperature and pressure through two opposing planes to achieve a predetermined thickness and density. Single-pass planar compaction refers to a process where the electrode undergoes only one non-repeated planar compaction process in the same area. The edge distance between two adjacent single-pass compaction areas refers to the distance between the edges of the two indentations formed after two consecutive single-pass planar compaction processes.

[0089] In this paper, the planar compaction and shaping mechanism used in this invention is as follows: Figure 1 As shown, it includes, in sequence, an unwinding component, a first conveying component, a planar compaction component, a second conveying component, a shaping component, a cooling component, a third conveying component, and a winding component; the first conveying component, the second conveying component, and the third conveying component work simultaneously to drive the electrode sheet to move from the unwinding component to the winding component.

[0090] The first conveying component includes a first passive roller, a second passive roller, a double roller mechanism consisting of a combination of an active roller and a passive roller, and an auxiliary pulley group connected in sequence; the second conveying component is an auxiliary pulley group; and the third conveying component is a third passive roller.

[0091] The first conveying component pauses after conveying the electrode sheet from the unwinding component to the flat compaction platform of the flat compaction component. The driving component then drives the flat pressure head to press down and maintain pressure. After the flat compaction is completed, the flat pressure head moves up. After the flat pressure head is fully reset, the conveying component restarts, driving the electrode sheet to move towards the winding component. The flat compaction process and the electrode sheet movement process are repeated to continuously compact the electrode sheet, resulting in a flat compacted electrode sheet.

[0092] After being compacted, the electrode sheet is conveyed to the shaping component via the second conveying component. The shaping component includes four sets of roller pressing mechanisms connected in series. Each roller pressing mechanism has a heating roller that contacts the electrode sheet. The roller pressing mechanisms are, in sequence, a first double roller mechanism, a second double roller mechanism, a first four roller mechanism, and a second four roller mechanism. Adjacent roller pressing mechanisms are staggered, so that the electrode sheet keeps in contact with one-quarter of the surface of the heating roller in the first double roller mechanism, and keeps in contact with half of the surface of the heating rollers in the second double roller mechanism, the first four roller mechanism, and the second four roller mechanism.

[0093] After leaving the second and fourth roller mechanism, the electrode sheet directly enters the cooling unit, is cooled by the water-cooled roller, and is then conveyed by the third conveying unit to the winding unit for winding.

[0094] In this paper, the first conveying component includes a set of double roller mechanisms, which consist of an active roller and a passive roller. The gap between them can be adjusted by a gap mechanism. The clamping and releasing actions of the double rollers on the electrode are controlled by adjusting the gap. In the clamping state, the active roller drives the electrode to be conveyed to the planar compaction platform.

[0095] In this paper, the planar compaction and shaping mechanism used in this invention includes at least two sets of roller pressing mechanisms, and can be flexibly configured in various series; for example, four sets of roller pressing mechanisms include: a full double roller mechanism, a full four roller mechanism, or a combination of one double roller mechanism and three four roller mechanisms, or three double roller mechanisms and one four roller mechanism, or two double roller mechanisms and two four roller mechanisms.

[0096] In this paper, the heating roller of the planar compaction and shaping mechanism used in this invention has a diameter of 150 mm and a width of 800 mm.

[0097] In this paper, the cooling component of the planar compaction and shaping mechanism used in this invention is a water-cooled roller, or a combination of a water-cooled roller and a room-temperature roller.

[0098] In this document, the external schematic diagram of the stacked battery cell of the present invention is as follows: Figure 2 As shown, it includes a shell, a positive electrode tab, and a negative electrode tab; the positive electrode tab is electrically connected to all positive electrode plates, and the negative electrode tab is electrically connected to all negative electrode plates.

[0099] Unless otherwise specified in this article, a positive single-sided electrode sheet refers to a positive single-sided electrode sheet after planar shaping, and a negative single-sided electrode sheet refers to a negative single-sided electrode sheet after planar shaping; a positive double-sided electrode sheet refers to a positive double-sided electrode sheet after planar shaping or a positive double-sided electrode sheet obtained by traditional roll pressing, and a negative double-sided electrode sheet refers to a negative double-sided electrode sheet after planar shaping or a negative double-sided electrode sheet obtained by traditional roll pressing.

[0100] In this paper, the cumulative deformation of the same electrode during the planar compaction process and the planar shaping process is defined as 100%.

[0101] The plane compaction and shaping process includes the plane compaction process and the plane shaping process;

[0102] The deformation amount in the planar compaction process is the ratio of the thickness difference of the electrode before and after the planar compaction process to the total thickness difference before and after the planar compaction shaping.

[0103] The deformation amount in the planar shaping process is the ratio of the thickness difference of the electrode before and after the planar shaping process to the total thickness difference before and after the planar compaction shaping process.

[0104] Assuming the thickness difference before and after the planar compaction process is L1, and the thickness difference before and after the planar shaping process is L2, then the deformation amount of the planar compaction process is L1 / (L1+L2)*100%, and the deformation amount of the planar shaping process is L2 / (L1+L2)*100%. In this paper, if the deformation amount of the planar shaping process is increased, that is, if the degree of change in the compaction density of the electrode after planar shaping (such as D11-D1) increases, the warpage of the electrode will show an upward trend, but it can still be maintained at a low level.

[0105] The tests in this article include:

[0106] Warpage rate: Cut the electrode sample into a rectangular sample with a length of 100 mm and a width of 50 mm; lay the sample on a marble platform with the coating layer facing upwards, and measure the dimensions L1 and L2 of the sample along the length Y and width Z directions of the current collector in a naturally stretched state; use a steel ruler or glass plate to flatten the sample and measure the dimensions L3 and L4 of the sample along the length Y and width Z directions of the current collector; the warpage rate of the sample along the length Y direction of the current collector = (L3-L1) / L3*100%; the warpage rate of the sample along the width Z direction of the current collector = (L4-L2) / L4*100%.

[0107] Laminated battery cell yield: refers to the proportion of good-quality laminated battery cells out of the total number of laminated battery cells produced. Example 1

[0108] In this embodiment, the stacked cell sequentially includes a negative single-sided electrode, a separator, a central unit, a separator, and a positive single-sided electrode; the central unit includes a stacked structure of "positive double-sided electrode + separator + negative double-sided electrode + ... + positive double-sided electrode + separator + negative double-sided electrode", wherein there are 37 positive double-sided electrodes and 37 negative double-sided electrodes.

[0109] (1) Preparation of electrode substrate:

[0110] (1.1) Positive single-sided electrode substrate:

[0111] The positive electrode slurry is coated on one side of a current collector (aluminum foil with a thickness of 10μm) with a width of 544mm. The coated area of ​​the positive electrode slurry is located in the middle of the current collector with a width of 511mm. The uncoated areas on both sides are 16.5mm wide respectively. After drying at 130℃, it is centered and cut by a slitting device to obtain a positive electrode single-sided electrode substrate with a width of 272mm, including an uncoated area with a width of 16.5mm on one side.

[0112] (1.2) Positive double-sided electrode substrate:

[0113] The positive electrode slurry is coated on both sides of a current collector (aluminum foil with a thickness of 10 μm) with a width of 544 mm. The coated area of ​​the positive electrode slurry is located in the middle of the current collector with a width of 511 mm. The uncoated areas on both sides are 16.5 mm wide respectively. After drying at 130°C, it is centered and cut by a slitting device to obtain a positive electrode double-sided electrode substrate with a width of 272 mm, including an uncoated area with a width of 16.5 mm on one side. Its coating thickness is the same as the coating thickness of a single side of the positive electrode double-sided electrode.

[0114] (1.3) Negative electrode single-sided electrode substrate:

[0115] The negative electrode paste is coated on one side of a current collector (copper foil with a thickness of 6.5 μm) with a width of 549 mm. The coated area of ​​the negative electrode paste is located in the middle of the current collector, with a width of 522 mm. The uncoated areas on both sides are 13.5 mm wide respectively. After drying at 130°C, it is centered and cut by a slitting device to obtain a negative electrode single-sided electrode substrate with a width of 274.5 mm, including an uncoated area with a width of 13.5 mm on one side. Its coating thickness is the same as the coating thickness of a single side of a negative electrode double-sided electrode.

[0116] (1.4) Negative electrode double-sided electrode substrate:

[0117] The negative electrode paste is coated on one side of a current collector (copper foil with a thickness of 6.5 μm) with a width of 549 mm. The coated area of ​​the negative electrode paste is located in the middle of the current collector with a width of 522 mm. The uncoated areas on both sides are 13.5 mm wide respectively. After drying at 130°C, it is centered and cut by a slitting device to obtain a negative electrode single-sided electrode substrate with a width of 274.5 mm, including an uncoated area with a width of 13.5 mm on one side.

[0118] (2) Processing of electrode substrate:

[0119] (2.1) The positive electrode single-sided substrate is conveyed to the planar compaction platform of the planar compaction component via a conveying component for planar compaction. The planar compaction head compacts the single-sided electrode substrate in a direction perpendicular to the surface of the substrate. The length of the planar compaction head is greater than the width of the coating area of ​​the single-sided electrode substrate. The compaction pressure is 75 MPa, the width of the compaction area (compactor width) is 98.5 mm, the length of the compaction area is 258 mm, and the compaction time (from the start of the compaction head's downward pressure to its complete return to its original position) is 3 seconds. During continuous planar compaction, the distance between adjacent edges of the compaction areas of the previous and subsequent compaction stages is 3 mm. The compaction density D1 of the resulting positive electrode single-sided substrate after planar compaction is 3.80 g / cm³. 3 .

[0120] The compacted positive electrode sheet is conveyed to a shaping unit for planar shaping. The heating rollers in the shaping unit are heated to 130°C. The electrode sheet sequentially passes through a first double-roller mechanism (comprising heating and ambient temperature rollers), a second double-roller mechanism (comprising heating and ambient temperature rollers), a first four-roller mechanism (comprising ambient temperature rollers, heating rollers, ambient temperature rollers, and ambient temperature rollers), and a second four-roller mechanism (comprising ambient temperature rollers, heating rollers, ambient temperature rollers, and ambient temperature rollers). Adjacent roller mechanisms are staggered, ensuring the electrode sheet maintains contact with one-quarter of the surface of the heating rollers in the first double-roller mechanism and half of the surface of the heating rollers in the second double-roller, first four-roller, and second four-roller mechanisms. The contact time between the electrode sheet and each heating roller is 3 seconds (the same as the planar compaction time), achieving deformation amounts of 1%, 1%, 1.5%, and 1.5% sequentially. The total deformation of the electrode sheet during planar shaping is 5%. The compacted density D11 of the planar shaped electrode sheet is 3.99 g / cm³. 3 (D1 = 95.24% D11).

[0121] The sheet is then cooled by a cooling unit to obtain a planar shaped positive electrode sheet, which is then conveyed by a third conveying unit to a winding unit for winding. The average thickness of the planar shaped positive electrode sheet is 70 μm, and the thickness difference between individual sheets is ±2 μm.

[0122] In the above steps, the electrode thickness is monitored in real time by a thickness detection system to ensure that the electrode thickness fluctuation range is 70±2μm.

[0123] The warpage of the positive electrode single-sided sheet was tested and found to be 0.5%.

[0124] (2.2) The positive electrode double-sided substrate was subjected to planar compaction, planar shaping, and cooling according to the steps in (2.1). The difference was that the pressure of the planar compaction was adjusted to 150 MPa, and the compaction density D2 of the positive electrode double-sided substrate after planar compaction was 4.02 g / cm³. 3 The compaction density D21 of the positive electrode single-sided sheet after planar shaping is 4.20 g / cm³. 3 (D2=95.71%D21) (D11=95.0%D21).

[0125] In the above steps, the thickness of the electrode sheet is monitored in real time by a thickness detection system to ensure that the thickness fluctuation range of the electrode sheet is ±2μm, and the average thickness of the positive double-sided electrode sheet after planar shaping is 125μm.

[0126] (2.3) The negative electrode single-sided electrode substrate was subjected to planar compaction, planar shaping, and cooling according to the steps in (2.1). The compaction density D3 of the obtained planar compacted negative electrode single-sided electrode was 1.49 g / cm³. 3 The compaction density D31 of the electrode sheet after planar shaping is 1.55 g / cm³. 3(D3 = 96.13% D31).

[0127] In the above steps, the electrode thickness is monitored in real time by a thickness detection system to ensure that the electrode thickness fluctuation range is ±2μm, and the average thickness of the single-sided negative electrode after planar shaping is 62μm.

[0128] The warpage of the negative electrode single-sided sheet was tested and found to be 0.46%.

[0129] (2.4) The negative electrode double-sided substrate was subjected to planar compaction, planar shaping, and cooling according to the steps in (2.2). The compaction density D4 of the resulting planar compacted negative electrode double-sided substrate was 1.58 g / cm³. 3 The compaction density D41 of the electrode sheet after planar shaping is 1.65 g / cm³. 3 (D4=95.76%D41) (D31=93.94%D41).

[0130] In the above steps, the thickness of the electrode sheet is monitored in real time by a thickness detection system to ensure that the thickness fluctuation range of the electrode sheet is ±2μm, and the average thickness of the negative electrode double-sided electrode sheet after planar shaping is 113μm.

[0131] (3) Assembly of electrode sheets:

[0132] (3.1) The positive single-sided electrode sheet (hereinafter referred to as positive single-sided electrode sheet), the positive double-sided electrode sheet (hereinafter referred to as positive double-sided electrode sheet), the negative single-sided electrode sheet (hereinafter referred to as negative single-sided electrode sheet), and the negative double-sided electrode sheet (hereinafter referred to as negative double-sided electrode sheet) after planar shaping are cut, and the length cutting direction is parallel to the direction of planar compaction; the cutting size of the positive single-sided electrode sheet and the positive double-sided electrode sheet is 98mm×255.5mm (retaining the tabs 16.5mm×60mm); the cutting size of the negative single-sided electrode sheet and the negative double-sided electrode sheet is 100mm×261mm (retaining the tabs 13.5mm×60mm);

[0133] The electrodes were assembled into a stacked cell according to the target structure and the performance was tested. The results are shown in Table 1.

[0134] Example 2

[0135] In this embodiment, the stacked cell sequentially includes a negative single-sided electrode, a separator, a central unit, a separator, and a negative single-sided electrode; the central unit includes a stacked structure of "positive double-sided electrode + separator + negative double-sided electrode + ... + negative double-sided electrode + separator + positive double-sided electrode", wherein there are 37 positive double-sided electrodes and 36 negative double-sided electrodes.

[0136] The negative single-sided electrode, positive double-sided electrode, and negative double-sided electrode in Example 1 were used to assemble a stacked cell according to the target structure and the performance was tested. The results are shown in Table 1.

[0137] Example 3

[0138] In this embodiment, the stacked cell sequentially includes a positive single-sided electrode, a separator, a central unit, a separator, and a positive single-sided electrode; the central unit includes a stacked structure of "negative double-sided electrode + separator + positive double-sided electrode + ... + positive double-sided electrode + separator + negative double-sided electrode", wherein there are 36 positive double-sided electrodes and 37 negative double-sided electrodes.

[0139] The positive single-sided electrode, positive double-sided electrode, and negative double-sided electrode in Example 1 were used to assemble a stacked cell according to the target structure and the performance was tested. The results are shown in Table 1.

[0140] Example 4

[0141] In this embodiment, the stacked cell sequentially includes a positive single-sided electrode, a separator, a central unit, a separator, and a positive single-sided electrode; the central unit includes a stacked structure of "negative double-sided electrode + separator + positive double-sided electrode + ... + positive double-sided electrode + separator + negative double-sided electrode", wherein there are 36 positive double-sided electrodes and 37 negative double-sided electrodes.

[0142] Compared to Example 3, the difference lies in adjusting the planar pressure of the compaction and shaping component and the roller pressure. Specifically, during the planar shaping process, deformation amounts of 0.5%, 0.5%, 0.5%, and 0.5% are achieved sequentially, resulting in a total deformation of 2% for the electrode sheet during the planar shaping process. The resulting compacted electrode sheet has a compaction density D11 of 3.99 g / cm³. 3 The warpage rate of the positive single-sided electrode sheet after planar shaping in this embodiment was tested and found to be 0.42%. The positive double-sided electrode sheet and negative double-sided electrode sheet from Example 1 were assembled with the positive single-sided electrode sheet of this embodiment according to the target structure to form a stacked cell, and performance tests were performed. The results are shown in Table 1.

[0143] Example 5

[0144] In this embodiment, the stacked cell sequentially includes a positive single-sided electrode, a separator, a central unit, a separator, and a positive single-sided electrode; the central unit includes a stacked structure of "negative double-sided electrode + separator + positive double-sided electrode + ... + positive double-sided electrode + separator + negative double-sided electrode", wherein there are 36 positive double-sided electrodes and 37 negative double-sided electrodes.

[0145] Compared to Example 3, the difference lies in the processing of the electrode substrate: the positive electrode double-sided electrode substrate is compacted by conventional continuous rolling using a hydraulic double-roll press, resulting in a thickness of 125 μm and a compaction density D2 of 4.2 g / cm³.3 The negative electrode double-sided substrate was compacted using a conventional continuous roller press with a hydraulic double-roller press. The thickness after roller pressing was 113 μm; the compaction density D4 was 1.65 g / cm³. 3 .

[0146] Using the positive single-sided electrode sheet from Example 1, and the positive double-sided electrode sheet and negative double-sided electrode sheet from this example, a stacked cell was assembled according to the target structure and its performance was tested. The results are shown in Table 1.

[0147] Example 6

[0148] In this embodiment, the stacked cell sequentially includes a positive single-sided electrode, a separator, a central unit, a separator, and a positive single-sided electrode; the central unit includes a stacked structure of "negative double-sided electrode + separator + positive double-sided electrode + ... + positive double-sided electrode + separator + negative double-sided electrode", wherein there are 36 positive double-sided electrodes and 37 negative double-sided electrodes.

[0149] Compared with Example 3, the difference lies in the processing of the electrode substrate: the flat compacted positive single-sided electrode sheet is sequentially passed through a first double-roller mechanism composed of a heating roller and a room temperature roller, a second double-roller mechanism composed of a heating roller and a room temperature roller, a first four-roller mechanism composed of a room temperature roller, a heating roller, a room temperature roller, and a room temperature roller, and a second four-roller mechanism composed of a room temperature roller, a heating roller, a room temperature roller, and a room temperature roller. The adjacent roller pressing mechanisms are staggered, so that the electrode sheet is in contact with one-quarter of the surface of the heating roller in the first double-roller mechanism, the second double-roller mechanism, the first four-roller mechanism, and the second four-roller mechanism.

[0150] The warpage rate of the positive electrode single-sided sheet after planar shaping in this embodiment was tested and found to be 1.10%.

[0151] Using the positive double-sided electrode sheet and negative double-sided electrode sheet from Example 1, and the positive single-sided electrode sheet from this example, a stacked cell was assembled according to the target structure and its performance was tested. The results are shown in Table 1.

[0152] Example 7

[0153] In this embodiment, the stacked cell sequentially includes a positive single-sided electrode, a separator, a central unit, a separator, and a positive single-sided electrode; the central unit includes a stacked structure of "negative double-sided electrode + separator + positive double-sided electrode + ... + positive double-sided electrode + separator + negative double-sided electrode", wherein there are 36 positive double-sided electrodes and 37 negative double-sided electrodes.

[0154] Compared with Example 3, the difference lies in the processing of the electrode substrate: the flat compacted positive single-sided electrode is sequentially passed through the first double-roller mechanism, the second double-roller mechanism, the third double-roller mechanism and the fourth double-roller mechanism composed of heating rollers and room temperature rollers. The adjacent roller pressing mechanisms are staggered, so that the electrode keeps in contact with half of the surface of the heating rollers in the first double-roller mechanism, the second double-roller mechanism, the third double-roller mechanism and the fourth double-roller mechanism.

[0155] The warpage rate of the positive electrode single-sided sheet after planar shaping in this embodiment was tested and found to be 0.52%.

[0156] Using the positive double-sided electrode sheet and negative double-sided electrode sheet from Example 5, and the positive single-sided electrode sheet from this example, a stacked cell was assembled according to the target structure and its performance was tested. The results are shown in Table 1.

[0157] Example 8

[0158] Compared with Example 3, the difference is that in the processing of the positive electrode single-sided electrode substrate, the temperature of the heating roller in the shaping component is 110°C.

[0159] The warpage rate of the positive electrode single-sided sheet after planar shaping in this embodiment was tested and found to be 0.91%.

[0160] Using the positive double-sided electrode sheet and negative double-sided electrode sheet from Example 5, and the positive single-sided electrode sheet from this example, a stacked cell was assembled according to the target structure and its performance was tested. The results are shown in Table 1.

[0161] Example 9

[0162] Compared with Example 3, the difference is that in the processing of the positive electrode single-sided electrode substrate, the temperature of the heating roller in the shaping component is 80°C.

[0163] The warpage rate of the positive electrode single-sided sheet after planar shaping in this embodiment was tested and found to be 1.24%.

[0164] Using the positive double-sided electrode sheet and negative double-sided electrode sheet from Example 5, and the positive single-sided electrode sheet from this example, a stacked cell was assembled according to the target structure and its performance was tested. The results are shown in Table 1.

[0165] Example 10

[0166] Compared with implementation 3, the difference is that in the processing of the positive electrode single-sided electrode substrate, the temperature of the heating roller in the shaping component is 50°C.

[0167] The warpage rate of the positive electrode single-sided sheet after planar shaping in this embodiment was tested and found to be 1.57%.

[0168] Using the positive double-sided electrode sheet and negative double-sided electrode sheet from Example 5, and the positive single-sided electrode sheet from this example, a stacked cell was assembled according to the target structure and its performance was tested. The results are shown in Table 1.

[0169] Example 11

[0170] In this embodiment, the stacked cell sequentially includes a positive single-sided electrode, a separator, a central unit, a separator, and a positive single-sided electrode; the central unit includes a stacked structure of "negative double-sided electrode + separator + positive double-sided electrode + ... + positive double-sided electrode + separator + negative double-sided electrode", wherein there are 36 positive double-sided electrodes and 37 negative double-sided electrodes.

[0171] Compared with Example 3, the difference lies in (2.1) the processing of the electrode substrate: adjusting the pressure of the planar pressure head and the pressure of the roller in the planar compaction and shaping component, wherein, during the planar shaping process, deformation amounts of 3%, 3%, 2%, and 2% are achieved sequentially, and the deformation amount of the electrode during the planar shaping process is 10%. The compaction density D11 of the positive electrode single-sided sheet after planar shaping is 3.99 g / cm³. 3 .

[0172] The warpage rate of the positive electrode single-sided sheet after planar shaping in this embodiment was tested and found to be 0.71%.

[0173] Example 12

[0174] In this embodiment, the stacked cell sequentially includes a negative single-sided electrode, a separator, a central unit, a separator, and a negative single-sided electrode; the central unit includes a stacked structure of "positive double-sided electrode + separator + negative double-sided electrode + ... + negative double-sided electrode + separator + positive double-sided electrode", wherein there are 37 positive double-sided electrodes and 36 negative double-sided electrodes.

[0175] Compared with Example 2, the difference lies in (2.3) the processing of the electrode substrate: adjusting the pressure of the flat pressing head and the pressure of the roller pressing component of the flat compaction and shaping component, wherein, in the flat shaping process, the deformation amount is successively achieved as 3%, 3%, 2%, and 2%, and the deformation amount of the electrode during the flat shaping process is 10%. The compaction density D31 of the negative electrode single-sided electrode after flat shaping is 1.55 g / cm³. 3 .

[0176] The warpage rate of the negative electrode single-sided sheet after planar shaping in this embodiment was tested and found to be 0.80%.

[0177] Comparative Example 1

[0178] Compared with Example 3, the difference lies in the processing of the electrode substrate:

[0179] The positive electrode double-sided substrate was compacted using a conventional continuous rolling press with a hydraulic double-roller press, resulting in a thickness of 125 μm and a compaction density D21 of 4.2 g / cm³. 3 .

[0180] The negative electrode double-sided electrode substrate was compacted using a conventional continuous rolling press with a hydraulic twin-roll mill, resulting in a thickness of 113 μm and a compaction density D41 of 1.65 g / cm³. 3 .

[0181] The negative electrode single-sided electrode substrate was compacted using a conventional continuous roller press with a hydraulic double roller press, resulting in a thickness of 62 μm and a compaction density D13 of 1.55 g / cm³. 3 .

[0182] The warpage rate of the negative electrode single-sided sheet after conventional rolling in this comparative test was 44.8%.

[0183] The positive double-sided electrode, negative double-sided electrode, and negative single-sided electrode of this comparative example were assembled into a stacked cell according to the target structure and the performance was tested. The results are shown in Table 1.

[0184] Comparative Example 2

[0185] In this comparative example, the laminated cell includes, in sequence, a positive single-sided electrode, a separator, a central unit, a separator, and a positive single-sided electrode; the central unit includes a stacked structure of "negative double-sided electrode + separator + positive double-sided electrode + ... + positive double-sided electrode + separator + negative double-sided electrode", of which there are 36 positive double-sided electrodes and 37 negative double-sided electrodes.

[0186] Compared to Example 3, the difference lies in the processing of the electrode substrate: the positive electrode single-sided electrode substrate is compacted by conventional continuous rolling using a hydraulic double-roll press, resulting in a thickness of 70 μm and a compaction density D31 of 3.99 g / cm³. 3 .

[0187] The warpage rate of the positive electrode single-sided sheet after conventional rolling in this comparative test was 40.32%.

[0188] Using the positive double-sided electrode sheet and negative double-sided electrode sheet from Example 5, and the positive single-sided electrode sheet from this comparative example, a stacked cell was assembled according to the target structure and its performance was tested. The results are shown in Table 1.

[0189] Comparative Example 3

[0190] In this comparative example, the laminated cell includes, in sequence, a positive single-sided electrode, a separator, a central unit, a separator, and a positive single-sided electrode; the central unit includes a stacked structure of "negative double-sided electrode + separator + positive double-sided electrode + ... + positive double-sided electrode + separator + negative double-sided electrode", of which there are 36 positive double-sided electrodes and 37 negative double-sided electrodes.

[0191] Methods for preparing a single-sided positive electrode include:

[0192] The positive electrode slurry was coated on one side of a current collector (aluminum foil with a thickness of 10 μm) with a width of 544 mm and dried at 130 °C. Then, the support layer coating slurry (PVDF:boehmite mixture = 3:7) was coated on the back side of the current collector and dried at 130 °C to obtain a support layer with a thickness of 30 μm. The positive electrode single-sided electrode substrate was obtained by center cutting through a rolling and slitting device. The positive electrode single-sided electrode sheet was then obtained by cutting.

[0193] The warpage rate of the positive electrode single-sided sheet in this comparative example was 1.16%.

[0194] The positive single-sided electrode sheet of this comparative example, together with the positive double-sided electrode sheet and the negative double-sided electrode sheet of Example 5, were assembled into a stacked cell according to the target structure and the performance was tested. The results are shown in Table 1.

[0195] Comparative Example 4

[0196] In this comparative example, the laminated cell includes, in sequence, a negative single-sided electrode, a separator, a central unit, a separator, and a negative single-sided electrode; the central unit includes a stacked structure of "positive double-sided electrode + separator + negative double-sided electrode + ... + negative double-sided electrode + separator + positive double-sided electrode", of which there are 37 positive double-sided electrodes and 36 negative double-sided electrodes.

[0197] Methods for preparing negative single-sided electrode sheets include:

[0198] The negative electrode slurry was coated on one side of a current collector (copper foil with a thickness of 6.5 μm) with a width of 544 mm and dried at 130 °C. Then, the support layer coating slurry (SBR: boehmite mixture = 3:7) was coated on the back side of the current collector and dried at 130 °C to obtain a support layer with a thickness of 30 μm. The negative electrode single-sided electrode substrate was obtained by center cutting through a rolling and slitting device. The negative electrode single-sided electrode sheet was then obtained by cutting.

[0199] The warpage rate of the negative electrode single-sided sheet in this comparative test was 1.04%.

[0200] The negative single-sided electrode sheet of this comparative example, together with the positive double-sided electrode sheet and the negative double-sided electrode sheet of Example 5, were assembled into a stacked cell according to the target structure and the performance was tested. The results are shown in Table 1.

[0201] Comparative Example 5

[0202] In this comparative example, the laminated cell has a stacked structure of "negative double-sided electrode + separator + positive double-sided electrode + ... + positive double-sided electrode + separator + negative double-sided electrode", with 36 positive double-sided electrodes and 37 negative double-sided electrodes.

[0203] The positive and negative double-sided electrode sheets from Example 5 were assembled into a stacked cell according to the target structure and their performance was tested. The results are shown in Table 1.

[0204] Comparative Example 6

[0205] In this comparative example, the laminated cell has a stacked structure of "positive double-sided electrode + separator + negative double-sided electrode + ... + negative double-sided electrode + separator + positive double-sided electrode", with 37 positive double-sided electrodes and 36 negative double-sided electrodes.

[0206] The positive and negative double-sided electrode sheets from Example 5 were assembled into a stacked cell according to the target structure and their performance was tested. The results are shown in Table 1.

[0207] Table 1. Performance Data of Electrode and Laminated Cells

[0208]

[0209]

[0210] As shown in the table above, the present invention obtains a single-sided electrode sheet with low warpage by placing the single-sided electrode sheet substrate loaded with active material in a planar compaction and shaping mechanism and then sequentially compacting and shaping it in a planar manner. Without the need for a support layer, a single-sided electrode sheet with low warpage (after planar shaping) can be obtained. The single-sided electrode sheet is then combined with a double-sided electrode sheet to form a stacked cell, which significantly improves the battery qualification rate and energy density.

[0211] All aspects, embodiments, and features of this invention should be considered illustrative in all respects and not limiting of the invention; the scope of the invention is defined only by the claims. Other embodiments, modifications, and uses will become apparent to those skilled in the art without departing from the spirit and scope of the invention as claimed.

[0212] In the preparation method of this invention, the order of the steps is not limited to the listed order. For those skilled in the art, variations in the order of the steps without creative effort are also within the scope of protection of this invention. Furthermore, two or more steps or actions can be performed simultaneously.

[0213] Finally, it should be noted that the specific embodiments described herein are merely illustrative examples of the invention and are not intended to limit the implementation of the invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to replace them; it is neither necessary nor possible to exemplify all embodiments here. However, these obvious variations or modifications derived from the essential spirit of the invention still fall within the scope of protection of the invention, and interpreting them as any additional limitation would contradict the spirit of the invention.

Claims

1. A method for preparing a single-sided electrode with low warpage, characterized in that, include: By loading an active material onto one side of the current collector and forming a coated area and an uncoated area, a single-sided electrode substrate with a coated area on one side is obtained. The single-sided electrode substrate is sequentially subjected to planar compaction and planar shaping to obtain a single-sided electrode after planar shaping. The deformation of the single-sided electrode substrate during the planar shaping process is ≤10%, and the single-sided electrode after planar shaping is a low-warpage single-sided electrode with a warpage of ≤1.6%.

2. The method for preparing a low-warpage single-sided electrode according to claim 1, characterized in that, The planar compaction process includes: a planar compactor head compacts the single-sided electrode substrate in a direction perpendicular to the surface of the single-sided electrode substrate, the length of the planar compactor head being greater than the width of the coating area of ​​the single-sided electrode substrate, to obtain a single-sided electrode after planar compaction. The compaction time of the plane is 1 to 10 seconds, and the pressure of the plane indenter is 50 to 500 MPa.

3. The method for preparing a low-warpage single-sided electrode according to claim 1, characterized in that, The planar shaping process includes: the single-sided electrode sheet after planar compaction enters the shaping component, the shaping component includes at least two sets of continuous rolling mechanisms connected in series, each set of rolling mechanisms includes at least one heating roller that contacts the single-sided electrode sheet; the rolling mechanism is a double-roller and / or four-roller mechanism, and adjacent rolling mechanisms are staggered to keep at least one-quarter of the surface of the heating roller in contact with the single-sided electrode sheet, thereby obtaining the single-sided electrode sheet after planar shaping; The temperature of the heating roller in the roller pressing mechanism is 50-130℃.

4. The method for preparing a low-warpage single-sided electrode according to claim 3, characterized in that, The shaping component includes four sets of continuous rolling mechanisms connected in series, namely a first double-roller mechanism, a second double-roller mechanism, a first four-roller mechanism, and a second four-roller mechanism; wherein the first double-roller mechanism, the second double-roller mechanism, the first four-roller mechanism, and the second four-roller mechanism are staggered, so that the single-sided electrode sheet after planar compaction contacts one-quarter of the surface of the heating roller in the first double-roller mechanism, the single-sided electrode sheet contacts half of the surface of the heating roller in the second double-roller mechanism, the single-sided electrode sheet contacts half of the surface of the heating roller in the first four-roller mechanism, and the single-sided electrode sheet contacts half of the surface of the heating roller in the second four-roller mechanism. In the continuous rolling mechanism consisting of the four sets connected in series, the deformation of a single-sided electrode sheet after passing through any one of the rolling mechanisms is less than 2%.

5. The method for preparing a low-warpage single-sided electrode according to claim 1, characterized in that, The planar shaping process also includes a cooling process, which includes: after the planar shaped single-sided electrode sheet leaves the shaping component, it is conveyed to the water-cooling roller of the cooling component for cooling, and the planar shaped single-sided electrode sheet is kept in contact with at least one-quarter of the surface of the water-cooling roller to obtain a planar compacted and shaped single-sided electrode sheet.

6. The method for preparing a low-warpage single-sided electrode according to claim 1, characterized in that, The compaction density of the single-sided electrode after planar compaction is 90-99% of the compaction density of the single-sided electrode after planar shaping.

7. A single-sided electrode with low warpage, characterized in that, It is prepared by the method for preparing a single-sided electrode with low warpage as described in any one of claims 1 to 6.

8. A laminated battery cell, characterized in that, The laminated cell includes a central unit and two single-sided electrodes disposed on both sides thereof, the three being separated by a separator; the central unit includes a laminated structure of N double-sided electrodes and N-1 separators, with adjacent double-sided electrodes separated by separators and having opposite polarities; The single-sided electrode is the low-warpage single-sided electrode as described in claim 7; The polarities of the two single-sided electrodes are the same or opposite, and the polarities of the single-sided electrodes are opposite to those of the adjacent double-sided electrodes.

9. The laminated cell according to claim 8, characterized in that, The single-sided electrode includes a positive single-sided electrode and a negative single-sided electrode; the double-sided electrode includes a positive double-sided electrode and a negative double-sided electrode. The compaction density of the positive single-sided electrode sheet is 90-99% of the compaction density of the positive double-sided electrode sheet; the compaction density of the negative single-sided electrode sheet is 90-99% of the compaction density of the negative double-sided electrode sheet.

10. A planar compaction and shaping mechanism, characterized in that, It sequentially includes an unwinding component, a first conveying component, a planar compaction component, a second conveying component, a shaping component, a cooling component, a third conveying component, and a winding component; the first conveying component, the second conveying component, and the third conveying component work simultaneously to drive the electrode sheet to move from the unwinding component to the winding component; the planar compaction component includes a driving component, a planar pressure head, and a planar compaction platform; the shaping component includes at least two sets of continuous roller pressing mechanisms connected in series, each set of roller pressing mechanisms including at least one heating roller in contact with the electrode sheet; the roller pressing mechanism is a double-roller and / or four-roller mechanism, and adjacent roller pressing mechanisms are staggered to keep at least one-quarter of the surface of the electrode sheet in contact with the heating roller.

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