Manufacturing method of pole piece, pole piece and battery

Abstract

The invention relates to the field of battery production, particularly provides a manufacturing method of a pole piece, the pole piece and a battery, and aims to solve the problem that the warping problem of the existing pole piece is relatively serious. In order to achieve the purpose, the manufacturing method of the pole piece comprises the steps that the pole piece is introduced into a roller gap of a roller press, the front face of the pole piece makes contact with an upper pressing roller, the back face of the pole piece makes contact with a lower pressing roller, and primary rolling is conducted on the pole piece; and after the primary rolling is finished, introducing the pole piece into the roller gap of the roller press again, and enabling the back surface of the pole piece to be in contact with the upper pressing roller and the front surface of the pole piece to be in contact with the lower pressing roller, so as to perform secondary rolling on the pole piece. According to the method, the warping generated by the pole piece for the first time can be transferred in the reverse direction through two times of reverse rolling, and the two times of inward concave and outward convex are mutually counteracted, so that the flat pole piece is obtained. In addition, the completeness of the active particles can be better protected by the secondary rolling process, and the pole piece with more uniform pore size distribution is obtained, so that high charge-discharge energy efficiency and long cycle life are achieved.

Description

Technical Field

[0001] The present invention relates to the field of battery production, and specifically provides a method for manufacturing a pole piece, a pole piece and a battery. Background Art

[0002] As the energy storage industry is in a state of rapid internal competition and fierce homogeneity competition, energy storage systems and batteries are required to have larger capacity, lower cost, and longer life. By increasing the size of the battery cells, not only can the manufacturing efficiency be improved, but it will also have a positive driving effect on further exploring the energy density of the battery cells and reducing costs. Currently, many energy storage battery companies have launched large-capacity energy storage cells with a capacity of 320Ah+. This will effectively reduce the cost of electricity per kilowatt-hour of the energy storage system throughout its life cycle to meet the large-scale and highly economical application needs of energy storage.

[0003] At present, the energy storage cells released on the market are all showing a trend of becoming lighter and thinner. The cell lengths include L352, L500, L580, L684, L960 and other series, and the corresponding positive and negative electrodes are also getting longer and longer. However, the increase in the length of the electrode will also bring some process risks, among which the rolling warping problem is particularly serious, resulting in the inability of the CCD (charge coupled device) of the stacking equipment to accurately locate the four corners, and the coating area or blank area during the stacking process exceeds the design specifications, resulting in the risk of low capacity and lithium deposition in the cell, so effective methods are urgently needed to improve it.

[0004] Therefore, the art needs a new method for manufacturing a pole piece, a pole piece and a battery to improve the problem of pole piece warping. Summary of the invention

[0005] The present invention aims to solve the above technical problem, namely, to solve the problem that the existing pole piece warping problem is relatively serious.

[0006] On the one hand, the present invention provides a method for manufacturing an electrode sheet, characterized in that it includes: introducing the electrode sheet into the roller gap of a roller press, and making the front side of the electrode sheet contact the upper roller and the back side of the electrode sheet contact the lower roller, so as to roll the electrode sheet once; after the first rolling is completed, introducing the electrode sheet into the roller gap of the roller press again, and making the back side of the electrode sheet contact the upper roller and the front side of the electrode sheet contact the lower roller, so as to roll the electrode sheet for a second time.

[0007] Since the front of the pole piece contacts the upper roller and the back of the pole piece contacts the lower roller during the first rolling, and the second rolling is performed after the first rolling, the back of the pole piece contacts the upper roller and the front of the pole piece contacts the lower roller during the second rolling, and the warping of the pole piece generated in the first time can be transferred in the opposite direction through the second reverse rolling, and the two concave and convex shapes offset each other, thereby obtaining a flat pole piece. In addition, the secondary rolling process can better protect the integrity of the active particles and obtain a pole piece with a more uniform pore size distribution, thereby achieving high charge and discharge energy efficiency and cycle life.

[0008] In the optional technical scheme of the above-mentioned method for manufacturing the pole piece, the step of "rolling the pole piece once" further includes: rolling the pole piece to 1 / 2-3 / 4 of the target thickness; the step of "rolling the pole piece twice" further includes: rolling the pole piece to the target compaction density; wherein the target thickness = surface density / target compaction density.

[0009] After testing, it was found that the pole piece was rolled to 1 / 2-3 / 4 of the target thickness during the first rolling, and the pole piece was rolled to the target compaction density during the second rolling. The warping height of the pole piece and the pole ear was measured at both corners <1cm, and the porosity was ≥38%. The two concave and convex parts of this method offset each other to obtain a flat pole piece, and the two rollings can better obtain a pole piece with a more uniform pore size distribution.

[0010] In the optional technical scheme of the above-mentioned method for manufacturing the pole piece, the step of "introducing the pole piece into the roller gap of the roller press" includes: introducing the free end of the pole roll formed by winding the coated pole piece into the roller gap of the roller press; the manufacturing method also includes: after one rolling is completed, the pole piece is reversely rolled up to form a reverse roll; the step of "introducing the pole piece into the roller gap of the roller press again" includes: introducing the free end of the reverse roll into the roller gap of the roller press.

[0011] The coated pole coil is directly threaded into the roller press and rolled once, and then a reverse roll is formed and the free end of the reverse roll is introduced into the roller gap of the roller press. This can reduce the intermediate operation steps, facilitate secondary reverse rolling, and make the production process more continuous and efficient.

[0012] In an optional technical solution of the above-mentioned method for manufacturing a pole piece, the manufacturing method further comprises: after the secondary rolling is completed, die-cutting the pole piece to obtain a die-cut pole piece.

[0013] In the optional technical scheme of the above-mentioned method for manufacturing the pole piece, after the step of "die-cutting the pole piece to obtain a die-cut pole piece", the manufacturing method further includes: stacking the die-cut pole pieces to obtain a laminate; applying pressure to the top of the laminate, and heating the laminate.

[0014] By heating the stack, the coating material in the stack can be softened to make it more plastic. Since a relatively flat pole piece can be obtained after the second reverse rolling of the pole piece, the pole piece warping is already very slight. Therefore, by applying pressure to the top of the stack, even the stack can be better adjusted and restored to a flat state, reducing slight warping and unevenness, thereby eliminating or further reducing the warping of the pole piece.

[0015] In the optional technical solution of the above-mentioned pole piece manufacturing method, after the step of "applying pressure to the top of the laminate and heating the laminate", the manufacturing method further includes: after waiting for a preset time period, turning the laminate upside down; and applying pressure to the top of the flipped laminate.

[0016] Since the warping direction of the laminate is consistent, the top surface is pressed first to make a preliminary correction, and then the laminate is turned over and pressed, which can more thoroughly eliminate the warping and unevenness of the laminate and improve the overall flatness. In addition, by applying pressure on both sides, the heated and softened coating material can be more evenly attached to the foil. The coating material is evenly pressurized on both sides, which helps to improve its adhesion and uniformity, thereby enhancing the durability and quality of the coating.

[0017] In the optional technical solution of the above-mentioned method for manufacturing the pole piece, the preset time period ranges from 6 hours to 24 hours; the heating temperature of the stack ranges from 60°C to 150°C.

[0018] Within the above-mentioned preset time period and heating temperature range, the coating material in the laminate can be moderately softened to make it more plastic, thereby reducing or eliminating the slight warping and unevenness after the secondary rolling, and eliminating or further reducing the warping of the pole piece.

[0019] In an optional technical solution of the above-mentioned method for manufacturing a pole piece, a method of applying pressure to the top of the stack is: placing a counterweight block on the top of the stack and making the counterweight block cover the top.

[0020] Since the counterweight covers the entire top of the stack, it can evenly apply pressure to every possible warp position, so that all possible warp areas can be evenly corrected without leaving any dead angles, ensuring that all areas are equally flattened; it also makes the weight of the counterweight evenly distributed on the top of the stack, avoiding excessive or insufficient local pressure, ensuring that the stack is evenly compressed during the entire heating and cooling process, reducing internal stress and deformation. On the other hand, the counterweight pressurization operation is simple, does not require complex mechanical devices and control systems, and is easy to implement and manage.

[0021] In the optional technical solution of the above-mentioned method for manufacturing the pole piece, the step of "heating the stack" further includes: placing the stack in an oven for heating.

[0022] The oven can provide a uniform heating environment, ensuring that every part of the laminate receives consistent heat and improving the uniformity of the heating effect. In addition, the oven generally has a precise temperature control system that can accurately set and maintain the required heating temperature to ensure that the laminate softens at the optimal temperature.

[0023] On the other hand, the present invention further provides a pole piece, which is manufactured by the pole piece manufacturing method described in any of the above embodiments.

[0024] The pole piece made by the above method can effectively improve the warping problem and broaden the post-processing window. The surface particle structure of the pole piece is more complete and the pore size is more uniform, thereby achieving high charge and discharge energy efficiency and cycle life.

[0025] In another aspect, the present invention further provides a battery, comprising the above-mentioned electrode sheet. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings, in which:

[0027] Figure 1 It is a main flow chart of the method for manufacturing a pole piece of the present invention;

[0028] Figure 2 Schematic diagram of pole piece rolling of the present invention (I);

[0029] Figure 3 Schematic diagram of pole piece rolling of the present invention (II);

[0030] Figure 4 Schematic diagram of the warping of the four corners of the pole piece from the desktop of the present invention;

[0031] Figure 5 It is a schematic diagram of the pole pieces after rolling of Examples 1-2 of the present invention and the comparative example;

[0032] Figure 6 It is a possible logic diagram of the manufacturing method of the pole piece of the present invention. DETAILED DESCRIPTION

[0033] First of all, it should be noted that the following embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention. In order to better illustrate the present invention, numerous specific details are given in the following specific embodiments. It should be understood by those skilled in the art that the present invention can also be implemented without certain specific details.

[0034] It should be noted that in the description of the present invention, terms such as "upper" and "lower" indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings. This is only for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0035] Since the pressure acts on the electrode coating area during rolling, and the force is transmitted to the foil through the particles, the foil will also be stretched under pressure and its length will increase. However, since the blank areas on both sides do not contact the upper and lower rollers, the blank areas on both sides are not subjected to force and will not stretch, resulting in inconsistent stretching and deformation at different positions of the electrode, wrinkles at the edge of the coating, and warping of the electrode. As the energy density of the battery cell increases, the compaction density of the electrode increases, and the pressure during rolling also needs to be increased, and the degree of flexural deformation will become more serious.

[0036] In order to solve the existing problem of serious pole piece warping, the present invention provides a method for manufacturing a pole piece, such as Figure 1 As shown, the manufacturing method of the pole piece includes the following steps:

[0037] Step S100: introducing the pole piece into the roller gap of the roller press, and making the front side of the pole piece contact the upper roller and the back side of the pole piece contact the lower roller, so as to perform a roller pressing on the pole piece.

[0038] Step S200: After one rolling is completed, the electrode sheet is introduced into the roller gap of the roller press again, and the back side of the electrode sheet contacts the upper roller and the front side of the electrode sheet contacts the lower roller, so as to perform a second rolling on the electrode sheet.

[0039] The above-mentioned electrode is preferably a positive electrode. It can be understood that the above-mentioned front and back sides refer to two opposite sides in the thickness direction of the electrode. Figure 2 As shown, Figure 2 (a) is the schematic diagram of the first rolling. Figure 2 (b) is a schematic diagram of the second reverse rolling. During the first rolling, the front side of the pole piece contacts the upper roller and the back side contacts the lower roller. After the first rolling, the second rolling is performed. During the second rolling, the back side of the pole piece contacts the upper roller and the front side contacts the lower roller. The warping of the pole piece generated for the first time can be transferred in the opposite direction through the second reverse rolling. The two concave and convex parts offset each other, thereby obtaining a flat pole piece. Figure 2 (c) In addition, the secondary rolling process can better protect the integrity of the active particles and obtain a pole piece with a more uniform pore size distribution, thereby achieving high charge and discharge energy efficiency and cycle life.

[0040] During operation, the front end of the pole piece can be placed on the feed guide of the roller press, and ensure that the front side faces up and the back side faces down, and then the pole piece is guided into the roller gap between the upper roller and the lower roller to ensure that the front side contacts the upper roller and the back side contacts the lower roller. Furthermore, the guide roller system of the roller press can be used to ensure that the pole piece remains flat and in the correct position when entering the roller gap. After confirming that the pole piece enters the roller gap smoothly, the speed of the roller press can be increased for continuous rolling.

[0041] Possibly, refer to Figure 6, step S100 includes step S101: introducing the free end of the pole roll formed by winding the coated pole piece into the roller gap of the roller press, and making the front of the pole piece contact the upper pressure roller and the back of the pole piece contact the lower pressure roller, so as to roll the pole piece once. Step S101 includes step S102: after the first rolling is completed, the pole piece is reversely rolled to form a reverse roll. Step S200 includes: introducing the free end of the reverse roll into the roller gap of the roller press, and making the back of the pole piece contact the upper pressure roller and the front of the pole piece contact the lower pressure roller, so as to roll the pole piece for a second time.

[0042] like Figure 3 As shown, after the current collector is coated, a pole roll 4 will be formed, so that the free end of the pole roll 4 can be threaded in the roller press, so that the front of the pole piece contacts the upper pressure roller 2 and the back of the pole piece contacts the lower pressure roller 3. After the roller press is started, the reel that winds the pole roll will rotate forward to ensure normal unwinding. The free end of the pole roll that has been rolled once will be reversely rolled onto the reel for winding to form a reel 5. In this case, the reel for winding rotates in the opposite direction; after winding, the free end of the reel can be threaded in the roller press, so that the back of the pole piece contacts the upper pressure roller and the front of the pole piece contacts the lower pressure roller to ensure secondary rolling. The method of directly threading the coated pole roll in the roller press and rolling it once, then forming a reel and introducing the free end of the reel into the roller gap of the roller press can reduce the intermediate operation steps, facilitate secondary reverse rolling, and make the production process more continuous and efficient.

[0043] It should be noted that when performing secondary rolling, the upper and lower rollers used for rolling the pole piece for the first time can be used. If the roller press is a bidirectional roller press, the free end of the rewind can be directly passed through the roller gap without moving the rewind; or if the roller press is a unidirectional roller press, in this case, the pole roll can be moved to facilitate the introduction of the free end of the pole roll into the roller gap. However, this is not restrictive. For example, a pair of upper and lower rollers can be set up, and the upper and lower rollers are set downstream of the rewind, so that the free end of the rewind can be directly passed through the gap between the upper and lower rollers downstream. These adjustments do not deviate from the principles of the present invention and are within the scope of protection of the present invention.

[0044] As a possible implementation, in step S100, "rolling the pole piece once" can be specifically rolling the pole piece to 1 / 2-3 / 4 of the target thickness; in step S200, "rolling the pole piece twice" can be specifically rolling the pole piece to the target compaction density, wherein target thickness = surface density / target compaction density. It can be understood that surface density = active material mass of the pole piece / area of ​​the pole piece, and the unit can be g / m 2 ; Compacted density refers to the density of the electrode after compaction, and the unit can be g / cm 3Since the target compaction density is known, the target thickness can be obtained through the surface density.

[0045] As a possible implementation, after step S200, the method for manufacturing a pole piece of the present invention further includes step S300: after the secondary rolling is completed, die-cutting the pole piece to obtain a die-cut pole piece.

[0046] The present invention is further described in detail below in conjunction with specific embodiments, but the protection scope of the present invention is not limited to the described contents.

[0047] Example 1: The coated electrode sheet is passed through a roller press. During rolling, the front side of the electrode sheet contacts the upper roller for the first time, and the back side contacts the lower roller. The electrode sheet is rolled to 1 / 2 of the target thickness. The electrode sheet is then rolled back so that the back side of the electrode sheet contacts the upper roller and the front side contacts the lower roller. The electrode sheet is rolled a second time to the target compaction density. The electrode sheet is then die-cut to obtain a die-cut electrode sheet.

[0048] Example 2: The coated electrode sheet is threaded through a roller press, with the front side contacting the upper roller and the back side contacting the lower roller for the first time during rolling. The rolling is performed to 3 / 4 of the target thickness. The electrode sheet is then rewound so that the back side of the electrode sheet contacts the upper roller and the front side contacts the lower roller. The electrode sheet is rolled a second time to the target compaction density. The electrode sheet is then die-cut to obtain a die-cut electrode sheet.

[0049] Comparative Example: The only difference between the comparative example and Examples 1 and 2 is that the roller pressing is performed once to the target compaction density. Except for the above difference, the materials and roller pressing parameters used in this comparative example are strictly consistent with those of Examples 1 and 2.

[0050] The method for obtaining the warpage height of the electrode piece after die cutting of Example 1, Example 2 and the comparative example can be: placing the electrode piece after die cutting on a flat table, and measuring the warpage heights of the four corners, H1, H2, H3 and H4, with a ruler, such as Figure 4 . Figure 5 The digital photos of Example 1, Example 2 and Comparative Example after rolling are shown in FIG. Figure 5 (d) is a diagram of the pole piece of Example 1, 5(e) is a diagram of the pole piece of Example 2, and 5(f) is a diagram of the pole piece of the comparative example. From the observation of the pictures alone, the warping height of the pole pieces of Examples 1 and 2 is obviously smaller than the warping height of the pole piece of the comparative example.

[0051] The die-cut pole pieces of Example 1, Example 2 and the comparative example can be used as test objects, and the porosity test can be performed using the adsorption weighing method. The porosity test method can be:

[0052] 1) Cut the electrode to be tested into a rectangular electrode of 10cm*5cm and place it in a constant temperature box at 100℃ for 3h;

[0053] 2) Calculate the pole piece coating volume V1 and the foil volume V2 based on the pole piece thickness and the foil thickness;

[0054] 3) Place a volume of V3 of DMC (dimethyl carbonate) solution and an electrode in a sealed vacuum container, without contacting the electrode with the solvent, and evacuate to -0.08Mpa, and let stand for 10 minutes;

[0055] 4) After 20 minutes, break the vacuum, immerse the electrode completely in the solvent, and leave it in an inert atmosphere for 40 hours;

[0056] 5) Read the volume V4 of the electrode after it is immersed in the solvent volume;

[0057] 6) The porosity of the positive electrode sheet is calculated according to the formula (V1+V2+V3-V4) / V1*100%.

[0058] The following table shows the relevant test data of Example 1, Example 2 and Comparative Example:

[0059]

[0060] It can be seen from the above table that among the test objects, the warping height of the pole piece and the pole ear measured in Examples 1-2 is less than 1cm, and the porosity is ≥38%. In this method, the two concave and convex parts offset each other to obtain a flat pole piece, and the two rolling processes can better obtain a pole piece with a more uniform pore size distribution. The comparative example adopts a single rolling process, and the warping degree of the four corners is significantly deteriorated, which has a greater impact on the subsequent lamination process; and the corresponding pole piece porosity is only 32%, which is not conducive to lithium ion deintercalation during the cycle.

[0061] In summary, the above method does not require technical changes to the equipment and is easy to operate; it can effectively improve the warping problem of long pole pieces and broaden the processing window of subsequent processes; it can better protect the integrity of the particle structure on the surface of the pole piece and obtain a pole piece with a more uniform pore size, thereby achieving high charging and discharging energy efficiency and cycle life.

[0062] As a possible implementation method, refer to Figure 6 , after step S300, the method further includes:

[0063] Step S400: stacking the die-cut pole pieces to obtain laminated sheets.

[0064] It is understandable that when the die-cut pole pieces are stacked, the same side of each pole piece should face the same direction, for example, the front sides of all pole pieces face upward, or the back sides of all pole pieces face upward.

[0065] Step S500: applying pressure to the top of the laminate and heating the laminate.

[0066] By heating the stack, the coating material in the stack can be softened to make it more plastic. Since a relatively flat pole piece can be obtained after the second reverse rolling of the pole piece, the pole piece warping is already very slight. Therefore, by applying pressure to the top of the stack, even the stack can be better adjusted and restored to a flat state, reducing slight warping and unevenness, thereby eliminating or further reducing the warping of the pole piece.

[0067] As a possible implementation, the way to apply pressure to the top of the stack can be to place a counterweight on the top of the stack and cover the top. Among them, materials with high thermal conductivity, high temperature resistance and moderate weight, such as metal blocks, can be selected to ensure uniform heat transfer and stable pressure during the heating process. Since the counterweight covers the entire top of the stack, it can evenly apply pressure to each position where warping may exist, so that all areas where warping may exist can be evenly corrected without leaving any dead angles, ensuring that all areas receive the same flattening treatment; it also makes the weight of the counterweight evenly distributed on the top of the stack, which can avoid excessive or insufficient local pressure, ensure that the stack is evenly compressed during the entire heating and cooling process, and reduce internal stress and deformation. On the other hand, the counterweight pressurization operation is simple, does not require complex mechanical devices and control systems, and is easy to implement and manage.

[0068] As a possible implementation, the laminate is heated by placing the laminate in an oven. The oven can provide a uniform heating environment, ensuring that each part of the laminate receives consistent heat, thereby improving the uniformity of the heating effect. In addition, the oven is generally equipped with a precise temperature control system, which can accurately set and maintain the required heating temperature, ensuring that the laminate is softened at the optimal temperature.

[0069] It should be noted that, although the present invention is introduced by heating the laminate through an oven, this is not intended to limit the scope of protection of the present invention. As long as the laminate can be heated, the specific heating method can be adjusted, for example, infrared heating, hot plate heating, microwave heating, induction heating or convection heating, etc., these adjustments do not deviate from the principle of the present invention and are within the scope of protection of the present invention. In addition, although the present invention is introduced by taking the counterweight block as an example to apply pressure to the top of the laminate, this is not intended to limit the scope of protection of the present invention. For example, a hydraulic press can be used to apply pressure to the top of the laminate, or a heated pressing plate can be used to heat treat the top of the laminate, or a mechanical arm can be used to apply pressure to the top of the laminate, etc. These adjustments do not deviate from the principle of the present invention and are within the scope of protection of the present invention.

[0070] After the above method, the warping of the pole piece has been basically eliminated. However, in order to further ensure that the warping is completely eliminated, after step S500, the method for manufacturing the pole piece of the present invention further includes the following steps:

[0071] Step S600: After waiting for a preset period of time, the stack is turned upside down.

[0072] It can be understood that turning the stack upside down means turning the stack upside down as a whole, that is, the bottom of the stack is replaced by the top of the stack, and the top of the stack is replaced by the bottom of the stack.

[0073] Step S700: applying pressure to the top of the turned-over laminate.

[0074] Since the warping direction of the laminate is consistent, the top surface is pressed first to make a preliminary correction, and then the laminate is turned over and pressed, which can more thoroughly eliminate the warping and unevenness of the laminate and improve the overall flatness. In addition, by applying pressure on both sides, the heated and softened coating material can be more evenly attached to the foil. The coating material is evenly pressurized on both sides, which helps to improve its adhesion and uniformity, thereby enhancing the durability and quality of the coating.

[0075] Among them, the above-mentioned preset time period can be adjusted according to material characteristics, temperature and pressure conditions, etc. The coating layers and foils of different materials soften and solidify at different speeds when heated and pressed. If the material needs a long time to soften evenly, the preset time period should be extended accordingly. The pressure of heating and pressing directly affects the speed of softening and correction. If the temperature is high and the pressure is large, the preset time period can be shortened, otherwise it needs to be extended. According to the above factors, the reasonable range of the preset time period can be 6 to 24 hours, among which the preferred time is 12 hours. Its specific determination method can be verified by experiment. The laminate is experimented by selecting the material, heating temperature and pressure, and different preset time periods (for example, 6 hours, 12 hours, 18 hours, 24 hours) are set respectively to observe the effect of the laminate warping correction and the uniformity of the coating layer, and find the time point with the best effect. The heating temperature of the laminate of the present invention can be selected according to the thermal stability, softening point and decomposition temperature of the material used for the laminate, and the preferred heating temperature range is 60℃-150℃, for example, 100℃. Heating at 60°C can moderately soften the coating material in the laminate and enhance its plasticity. Heating at 100°C can significantly soften the coating material and make it more plastic. A high temperature of 150°C can greatly soften the coating material. Within the above preset time period and heating temperature range, the coating material in the laminate can be moderately softened to make it more plastic, which can reduce or eliminate the slight warping and unevenness after the secondary rolling, and eliminate or further reduce the warping of the pole piece.

[0076] The way of applying pressure in step S700 can be the same as the way of applying pressure in step S500 to improve efficiency. For example, after completing step S500, the laminate is turned upside down, and the laminate is continued to be placed in the oven, and a counterweight is placed on the top of the flipped laminate, and the counterweight covers the top of the flipped laminate, and then the oven is continued to heat. However, this is not restrictive. For example, since the laminate has residual heat, the heating step can be omitted. Alternatively, the laminate can be continued to be heated by infrared heating, hot plate heating, microwave heating, induction heating or convection heating, etc. These adjustments do not deviate from the principles of the present invention and are within the scope of protection of the present invention.

[0077] On the other hand, the present invention also provides a pole piece, which is made by the above-mentioned pole piece manufacturing method. Preferably, the pole piece made by the present invention is a positive pole piece. The pole piece made by the above-mentioned method can effectively improve the warping problem and widen the post-process processing window. The surface particle structure of the pole piece is more complete and the pore size is more uniform, thereby achieving high charge and discharge energy efficiency and cycle life.

[0078] On the other hand, the present invention further provides a battery, which includes the above-mentioned pole piece.

[0079] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A method for manufacturing a pole piece, characterized in that: include: The pole piece is introduced into the roller gap of the roller press, and the front side of the pole piece contacts the upper roller and the back side of the pole piece contacts the lower roller, so as to perform a roller pressing on the pole piece; After one rolling process is completed, the pole piece is introduced into the roller gap of the roller press again, and the back side of the pole piece contacts the upper roller and the front side of the pole piece contacts the lower roller, so as to perform a second rolling process on the pole piece.

2. The method for manufacturing a pole piece according to claim 1, characterized in that: The step of "rolling the pole piece once" further comprises: Roll the pole piece to 1 / 2-3 / 4 of the target thickness; The step of "secondary rolling of the pole piece" further includes: Rolling the pole piece to a target compaction density; Wherein, the target thickness=surface density / target compaction density.

3. The method for manufacturing a pole piece according to claim 1, characterized in that: The step of "introducing the pole piece into the roller gap of the roller press" includes: The free end of the pole roll formed by winding the coated pole piece is introduced into the roller gap of the roller press; The manufacturing method further comprises: After the first rolling is completed, the pole piece is reversely rolled to form a reverse roll; The step of "introducing the pole piece into the roller gap of the roller press again" includes: The free end of the reverse roll is introduced into the roll gap of the roller press.

4. The method for manufacturing a pole piece according to claim 1, characterized in that: The manufacturing method further comprises: After the secondary rolling is completed, the pole piece is die-cut to obtain a die-cut pole piece.

5. The method for manufacturing a pole piece according to claim 4, characterized in that: After the step of "die-cutting the pole piece to obtain a die-cut pole piece", the manufacturing method further comprises: Stacking the die-cut pole pieces to obtain laminated sheets; Pressure is applied to the top of the stack, and heat is applied to the stack.

6. The method for manufacturing a pole piece according to claim 5, characterized in that: After the step of "pressing the top of the laminate and heating the laminate", the manufacturing method further comprises: After waiting for a preset period of time, turning the stack upside down; Pressure is applied to the top of the turned-over laminate.

7. The method for manufacturing a pole piece according to claim 6, characterized in that: The preset time period ranges from 6 hours to 24 hours; The heating temperature of the laminate is in the range of 60°C to 150°C.

8. The method for manufacturing a pole piece according to claim 5 or 6, characterized in that: The top of the stack is pressed by: A counterweight is placed on top of the stack so that it covers the top.

9. The method for manufacturing a pole piece according to claim 5, characterized in that: The step of "heating the laminate" further comprises: The stack is placed in an oven for heating.

10. A pole piece, characterized in that: The pole piece is manufactured by the pole piece manufacturing method according to any one of claims 1 to 9.

11. A battery, characterized in that: The battery comprises the pole piece according to claim 10.

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