CN112993202A - Pole piece and preparation method and application thereof - Google Patents
Pole piece and preparation method and application thereof Download PDFInfo
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- CN112993202A CN112993202A CN202110284873.XA CN202110284873A CN112993202A CN 112993202 A CN112993202 A CN 112993202A CN 202110284873 A CN202110284873 A CN 202110284873A CN 112993202 A CN112993202 A CN 112993202A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/04—Processes of manufacture in general
- H01M4/0402—Methods of deposition of the material
- H01M4/0404—Methods of deposition of the material by coating on electrode collectors
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/04—Processes of manufacture in general
- H01M4/043—Processes of manufacture in general involving compressing or compaction
- H01M4/0435—Rolling or calendering
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/139—Processes of manufacture
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Abstract
The invention relates to a pole piece and a preparation method and application thereof. The preparation method of the pole piece comprises the following steps: respectively forming an active layer and two ceramic layers A on the surface of the pole piece, rolling, and then forming a ceramic layer B on the whole active layer; the active layer is positioned between the two ceramic layers A and is connected with the ceramic layers A; along the width direction of the pole piece, the distances between the two ends of the active layer and the corresponding ends of the pole piece are both larger than or equal to 50mm, and the width of the ceramic layer A is larger than or equal to 40 mm; the ceramic layer A and the ceramic layer B are respectively made of ceramic slurry A and ceramic slurry B; the solid content of the ceramic slurry A is greater than that of the ceramic slurry B. The preparation method is simple to operate, low in cost and suitable for industrial production, the thickness edge curl height of the pole piece prepared by the method is 3.2-7.7 mm, the breaking strength of the pole piece can reach 173-185 MPa, and the method has a wide application prospect.
Description
Technical Field
The invention relates to the field of batteries, in particular to a pole piece and a preparation method and application thereof.
Background
The secondary coating of the ceramic material on the surface of the positive electrode can enhance the protection of the positive electrode and play a role in preventing the contact short circuit of the positive electrode and the negative electrode when the diaphragm is decomposed at high temperature. However, the secondary coating can increase the impedance of the pole piece, so the coating thickness is as thin as possible, so the solid content of the ceramic slurry for secondary coating is generally low, and the phenomenon that the edge of the pole piece foil is seriously warped and curled to tear and break the strip is easily caused by a large amount of solvent evaporation in the drying process of a drying oven after the single-side secondary coating of the pole piece, particularly under the condition that the current positive pole piece design usually adopts a high-compaction design, the aluminum foil at the edge of an active substance after the pole piece is rolled is easily wrinkled to generate microcracks due to rolling damage, and the problems are more prominent.
At present, the method of increasing the width of the pole piece edge coated with active substances on two sides but not coated with ceramic slurry is generally adopted to solve the problem by cutting off the areas of the two side edges which are not coated with ceramic slurry after the secondary coating of the pole piece is completed. The greatest disadvantage of this method is the waste of active substances on both sides, which are known to be very expensive, which undoubtedly increases the costs. In addition, the method does not solve the problem of aluminum foil wrinkle at the edge of the active material after the pole piece is rolled before the ceramic slurry is coated, so that the risk of secondary coating belt breakage caused by rolling damage is still high.
Disclosure of Invention
Aiming at the problems, the invention provides the preparation method which is simple to operate and can effectively inhibit the curling of the pole piece when the ceramic slurry is coated.
The technical scheme is as follows:
a preparation method of a pole piece comprises the following steps:
respectively forming an active layer and two ceramic layers A on the surface of the pole piece, carrying out rolling treatment on the pole piece containing the active layer and the ceramic layers A, and then forming a ceramic layer B on the whole active layer;
the active layer is positioned between the two ceramic layers A and is connected with the ceramic layers A;
along the width direction of the pole piece, the distances between the two ends of the active layer and the corresponding ends of the pole piece are both larger than or equal to 50mm, and the width of the ceramic layer A is larger than or equal to 40 mm;
the ceramic layer A is made of ceramic slurry A, the ceramic layer B is made of ceramic slurry B, and the solid content of the ceramic slurry A is larger than that of the ceramic slurry B.
In one embodiment, the width of at least one ceramic layer A is more than or equal to 50mm along the width direction of the pole piece.
In one embodiment, the active layer is made of an active slurry, the solid content of the active slurry is 69% -73%; the solid content of the ceramic slurry A is 30-50%; the solid content of the ceramic slurry B is 5-15%.
In one embodiment, the thickness of the ceramic layer A is 50-80% of the thickness of the active layer; the thickness of the ceramic layer B is 5% -20% of that of the active layer.
In one embodiment, the ceramic slurry A comprises ceramic powder A and polymer A;
the ceramic powder A is selected from at least one of aluminum oxide, boehmite, titanium oxide, zirconium oxide, silicon oxide, soapstone, lithium iron phosphate and lithium manganese iron phosphate;
the polymer A is selected from at least one of polytetrafluoroethylene, polyvinylidene fluoride-hexafluoropropylene, polyacrylonitrile, polyethylene glycol, polymethyl acrylate and polyvinyl alcohol;
the mass ratio of the ceramic powder A to the polymer A is (88-95): (5-12).
In one embodiment, the ceramic slurry B comprises ceramic powder B and polymer B;
the ceramic powder B is selected from at least one of aluminum oxide, boehmite, titanium oxide, zirconium oxide, silicon oxide, soapstone, lithium iron phosphate and lithium manganese iron phosphate;
the polymer B is selected from at least one of polytetrafluoroethylene, polyvinylidene fluoride-hexafluoropropylene, polyacrylonitrile, polyethylene glycol, polymethyl acrylate and polyvinyl alcohol;
the mass ratio of the ceramic powder B to the polymer B is (0.8-1.2): (0.8 to 1.2).
In one embodiment, the particle size of the ceramic powder B is 20nm to 5000 nm.
In one embodiment, the active paste includes an active material, a conductive agent, and a binder;
the active material is selected from at least one of lithium-rich manganese base, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminate, lithium iron phosphate and lithium cobaltate;
the conductive agent is selected from at least one of carbon black, carbon nano tubes, conductive fibers, Ketjen black, graphene and conductive graphite;
at least one of polytetrafluoroethylene and polyvinylidene fluoride as the binder;
the mass ratio of the active substance, the conductive agent and the adhesive is (94-99), (0.5-3) to (0.5-3).
In one embodiment, the solvents used in the ceramic slurry a and the ceramic slurry B are independently selected from at least one of N-methylpyrrolidone, N-dimethylformamide, dimethylsulfoxide, isopropanol, t-butanol, benzene, toluene, and tetrahydrofuran.
In one embodiment, the active slurry, ceramic slurry a and ceramic slurry B are applied in a transfer batch coating.
In one embodiment, the roll diameter adopted by the rolling treatment is 50 cm-100 cm, and the rolling temperature is 20-100 ℃.
In one embodiment, after the ceramic layer B is formed, a step of removing the ceramic layer a is further included.
The invention also provides the pole piece prepared by the preparation method of the pole piece.
The invention also provides the application of the pole piece in automobiles and digital electronic products. The scheme is as follows:
a pole piece for a power supply of an automobile or an electronic product, the pole piece according to any one of the above embodiments.
Compared with the prior art, the invention has the following beneficial effects:
the preparation method of the pole piece provided by the invention comprises the steps of reserving a coating position, and coating an active layer, a ceramic layer A on two sides of the active layer and a ceramic layer B above the active layer on the specific position. The ceramic layer A with higher solid content is coated on the two sides of the active layer, so that on one hand, edge wrinkles and band breakage during rolling can be prevented, foil wrinkles after rolling can be eliminated, and the risk of band breakage during secondary coating, drying oven passing and winding can be reduced; on the other hand, compared with the traditional process, the ceramic slurry with low price is coated on the active substance to be cut off at two sides, so that the waste of the active substance can be reduced, and the cost is saved. Meanwhile, the ceramic layer B with lower solid content is coated on the active layer, so that the pole piece can be protected, and the short circuit caused by the contact of the anode and the cathode due to the high-temperature decomposition of the diaphragm can be prevented.
Drawings
FIG. 1 is a flow chart of the preparation of a pole piece in one embodiment of the present invention;
FIG. 2 is a schematic illustration of an intermediate of the pole piece in each of the preparation steps in one embodiment of the present invention;
FIG. 3 is a cross-sectional view of a pole piece intermediate coated with an active layer, a ceramic layer A and a ceramic layer B in accordance with an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to specific examples. The present invention may be embodied in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
It should be noted that in the description of the present invention, for the terms of orientation, there are terms such as "central", "lateral", "longitudinal", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise" and the like indicating the orientation and positional relationship based on the orientation or positional relationship shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and should not be construed as limiting the specific scope of the present invention.
In describing positional relationships, unless otherwise specified, when an element such as a layer, film or substrate is referred to as being "on" another layer, it can be directly on the other layer or intervening layers may also be present. Further, when a layer is referred to as being "under" another layer, it can be directly under, or one or more intervening layers may also be present. It will also be understood that when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present.
Where the terms "comprising," "having," and "including" are used herein, it is intended to cover a non-exclusive inclusion, as another element may be added, unless an explicit limitation is used, such as "only," "consisting of … …," etc.
Unless mentioned to the contrary, terms in the singular may include the plural and are not to be construed as being one in number.
Furthermore, the drawings are not 1:1 and the relative dimensions of the various elements in the figures are drawn for illustrative purposes only to facilitate understanding of the invention and are not necessarily drawn to scale, and are not to scale.
The invention provides the preparation method which is simple to operate and can effectively inhibit the curling of the pole piece when the ceramic slurry is coated.
The technical scheme is as follows:
a preparation method of a pole piece comprises the following steps:
respectively forming an active layer and two ceramic layers A on the surface of the pole piece, carrying out rolling treatment on the pole piece containing the active layer and the ceramic layers A, and then forming a ceramic layer B on the whole active layer;
the active layer is positioned between the two ceramic layers A and is connected with the ceramic layers A;
along the width direction of the pole piece, the distances between the two ends of the active layer and the corresponding ends of the pole piece are both larger than or equal to 50mm, and the width of the ceramic layer A is larger than or equal to 40 mm;
the ceramic layer A is made of ceramic slurry A, the ceramic layer B is made of ceramic slurry B, and the solid content of the ceramic slurry A is larger than that of the ceramic slurry B.
The preparation method of the pole piece provided by the invention comprises the steps of reserving a coating position, and coating an active layer, a ceramic layer A on two sides of the active layer and a ceramic layer B above the active layer on the specific position. The ceramic layer A with higher solid content is coated on the two sides of the active layer, so that on one hand, edge wrinkles and band breakage during rolling can be prevented, foil wrinkles after rolling can be eliminated, and the risk of band breakage during secondary coating, drying oven passing and winding can be reduced; on the other hand, compared with the traditional process, the ceramic slurry with low price is coated on the active substance to be cut off at two sides, so that the waste of the active substance can be reduced, and the cost is saved. Meanwhile, the ceramic layer B with lower solid content is coated on the active layer, so that the pole piece can be protected, and the short circuit caused by the contact of the anode and the cathode due to the high-temperature decomposition of the diaphragm can be prevented.
It can be understood that, in the present invention, the active slurry is applied to the surface of the pole piece and the ceramic slurry a is applied without any sequence, the active slurry may be applied to the surface of the pole piece first and then the ceramic slurry a is applied to the blank, or the ceramic slurry a may be applied to the reserved blank first and then the active slurry is applied to the surface between the two blanks.
Preferably, in the present invention, the active slurry, ceramic slurry a and ceramic slurry B are applied in a transfer batch coating manner. Does not need special ceramic coating equipment and has wide applicability.
Preferably, the roll diameter adopted by the rolling treatment is 50-100 cm, and the rolling temperature is 20-100 ℃. More preferably, the rolling is carried out by hot pressing at 90 ℃ and the roll diameter is 100 cm.
Preferably, after the ceramic layer B is formed, the method for preparing the electrode sheet further includes a step of removing the ceramic layer a.
In one preferred embodiment, the preparation process of the pole piece is shown in fig. 1:
firstly, coating active slurry on the surface of a pole piece, keeping the white on two sides to be more than or equal to 50mm, and drying to prepare an active layer;
coating the ceramic slurry A at the blank of the pole piece, wherein the coating width is more than or equal to 40mm, the position of the coated ceramic slurry A is closer to the direction of the active layer, drying and rolling;
coating the ceramic slurry B on the whole active layer and drying;
and finally, cutting off the ceramic layer A to obtain the pole piece with the ceramic coating coated on the active layer.
A schematic diagram of the pole piece intermediate obtained in each production step is shown in fig. 2, in which 101 denotes a pole piece, 102 denotes an active layer, 103 denotes a ceramic layer a, and 104 denotes a ceramic layer B.
In the present invention, the direction of travel of the pole piece is referred to as the longitudinal direction, and the direction perpendicular thereto is the width direction.
Fig. 3 is a cross-sectional view of a pole piece intermediate coated with an active layer, a ceramic layer a and a ceramic layer B in an embodiment of the present invention, wherein 201 denotes the pole piece, 202 denotes the active layer, 203 denotes the ceramic layer a, and 204 denotes the ceramic layer B.
In one embodiment, the width of the ceramic layer A is 40-90 mm.
In one embodiment, the width of at least one ceramic layer A is 50-90 mm. Therefore, the rolling stress can be buffered, and the degree of wrinkling of the edge of the rolled pole piece can be reduced.
In one preferable embodiment, the thickness of the ceramic layer a is 50% to 80% of the thickness of the active layer; the thickness of the ceramic layer B is 5% -20% of that of the active layer. The thickness of the ceramic layer A is 50% -80% of the thickness of the active layer, and the ceramic layer A is used for buffering rolling stress to reduce the degree of wrinkling after rolling; the ceramic layer B is thinner, so that the impedance can be prevented from being too large.
In one embodiment, the active layer is made of an active slurry, the solid content of the active slurry is 69% -73%; the solid content of the ceramic slurry A is 30-50%; the solid content of the ceramic slurry B is 5-15%. The coating thickness is related to the slurry solids content, the higher the solids content, the thicker the coating after drying.
The finished pole piece does not contain the ceramic layer A, and the ceramic layer A is cut off after the ceramic layer B is formed. The ceramic has wide selection range, and can effectively reduce the cost by reducing the thickness of the edge ceramic and using the ceramic material with low price under the condition of ensuring the feasible production.
In one embodiment, the ceramic slurry A comprises ceramic powder A and polymer A; the ceramic powder A is selected from at least one of aluminum oxide, boehmite, titanium oxide, zirconium oxide, silicon oxide, soapstone, lithium iron phosphate and lithium manganese iron phosphate; the polymer A is selected from at least one of polytetrafluoroethylene, polyvinylidene fluoride-hexafluoropropylene, polyacrylonitrile, polyethylene glycol, polymethyl acrylate and polyvinyl alcohol; the mass ratio of the ceramic powder A to the polymer A is (88-95): (5-12). The ceramic powder and the polymer have low cost and easily obtained raw materials, can prevent edge wrinkles and band breakage during rolling under the condition of reducing cost, eliminate folds of rolled foils and reduce the risk of band breakage during secondary coating, drying and rolling.
In one embodiment, the ceramic slurry B comprises ceramic powder B and polymer B;
the ceramic powder is selected from at least one of aluminum oxide, boehmite, titanium oxide, zirconium oxide, silicon oxide, soapstone, lithium iron phosphate and lithium manganese iron phosphate; the polymer B is selected from at least one of polytetrafluoroethylene, polyvinylidene fluoride-hexafluoropropylene, polyacrylonitrile, polyethylene glycol, polymethyl acrylate and polyvinyl alcohol; the mass ratio of the ceramic powder B to the polymer B is (0.8-1.2): (0.8 to 1.2). The ceramic powder and the polymer have low cost and easily obtained raw materials, can prevent edge wrinkles and band breakage during rolling under the condition of reducing cost, eliminate folds of rolled foils and reduce the risk of band breakage during secondary coating, drying and rolling.
Preferably, the granularity of the ceramic powder B is 20 nm-5000 nm. If the particles are too large, the coating may be scratched.
In one embodiment, the solvents used in the ceramic slurry a and the ceramic slurry B are independently selected from at least one of N-methylpyrrolidone, N-dimethylformamide, dimethylsulfoxide, isopropanol, t-butanol, benzene, toluene, and tetrahydrofuran.
In one embodiment, the active paste includes an active material, a conductive agent, and a binder; the mass ratio of the active substance, the conductive agent and the adhesive is (94-99), (0.5-3) to (0.5-3).
Preferably, when the positive pole piece is prepared, the active material is selected from at least one of lithium-rich manganese base, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminate, lithium iron phosphate and lithium cobalt oxide; the conductive agent is selected from at least one of carbon black, carbon nano tubes, conductive fibers, Ketjen black, graphene and conductive graphite; the adhesive is at least one of polytetrafluoroethylene and polyvinylidene fluoride. The positive pole piece prepared from the raw materials has better performance.
The invention also provides the pole piece prepared by the preparation method of the pole piece. Tests show that the edge curl height of the positive pole piece prepared by the preparation method of the pole piece is 3.2-7.7 mm, the breaking strength of the pole piece can reach 173-185 MPa, the method meets the requirements of the industry, has wide application prospect, and can be applied to lithium batteries and further applied to automobiles or digital electronic products.
The following are specific examples.
Unless otherwise specified, all starting materials are derived from commercially available products, and if not specified, contain no other components not specifically specified except for unavoidable impurities.
Example 1
This example provides a positive electrode active paste, which includes the following steps:
mixing nickel cobalt lithium manganate, a carbon nano tube and polyvinylidene fluoride according to a mass ratio of 98:1:1, adding the mixture into an N-methyl pyrrolidone solvent, and uniformly stirring to prepare positive active slurry with solid content of 70%.
Example 2
This example provides 2 ceramic slurries a of different solids contents:
(1) mixing alumina with the particle size of 200-3000 nm and polyvinylidene fluoride according to the mass ratio of 90:10, adding the mixture into N-methyl pyrrolidone, and uniformly stirring to prepare alumina-polyvinylidene fluoride-ceramic slurry A with the solid content of 30%.
(2) Mixing boehmite with the particle size of 200-3000 nm and polyvinylidene fluoride according to the mass ratio of 90:10, adding the mixture into N-methyl pyrrolidone, and uniformly stirring to prepare boehmite-polyvinylidene fluoride-ceramic slurry A with the solid content of 45%.
Example 3
This example provides 4 ceramic slurries B:
(1) mixing alumina with the granularity of 0.2-0.5 mu m and polyvinylidene fluoride according to the mass ratio of 50:50, adding the mixture into N-methyl pyrrolidone, and uniformly stirring to prepare alumina-polyvinylidene fluoride-ceramic slurry B with the solid content of 15%.
(2) Mixing fumed silica with the particle size of 20-50 nm and polyvinylidene fluoride according to the mass ratio of 50:50, adding the mixture into N-methyl pyrrolidone, and uniformly stirring to prepare fumed silica-polyvinylidene fluoride-ceramic slurry B with the solid content of 15%.
(3) Mixing alumina with the granularity of 0.2-0.5 mu m and polyvinyl alcohol according to the mass ratio of 50:50, adding the mixture into N-methyl pyrrolidone, and uniformly stirring to prepare alumina-polyvinyl alcohol-ceramic slurry B with the solid content of 15%.
(4) Boehmite with the particle size of 0.2-0.5 mu m and polyvinylidene fluoride are mixed according to the mass ratio of 50:50, added into N-methyl pyrrolidone and stirred uniformly to prepare boehmite-polyvinylidene fluoride-ceramic slurry B with the solid content of 5%.
Example 4
The embodiment provides a positive pole piece and a preparation method thereof. The preparation method comprises the following steps:
(1) the positive active slurry prepared in example 1 was coated on a 300mm (w) aluminum foil in the center by a transfer coater, the coating width was 200mm in the width direction of the electrode sheet, 50mm of white remained on each side, and the positive active layer was dried on one side to obtain a positive active layer with a thickness of 100 μm.
(2) The alumina-polyvinylidene fluoride-ceramic slurry A having a solid content of 30% prepared in example 2 was coated on the margin portions on both sides of the electrode sheet, the width of each side coated was 40mm in the width direction of the electrode sheet, and after the coating was completed, it was dried to obtain a ceramic layer A having a thickness of about 70 μm, and it was subjected to roll pressing by compacting at 3.5 g/cc.
(3) The alumina-polyvinylidene fluoride-ceramic slurry B having a solid content of 15% prepared in example 3 was coated on the surface of the positive electrode active layer with a coating width of 200mm, and dried at 120 ℃ to obtain a ceramic layer B having a thickness of 10 μm.
(4) And cutting off the ceramic layers A on two sides of the positive active layer to obtain the positive pole piece.
Example 5
The embodiment provides a positive pole piece and a preparation method thereof. The preparation method comprises the following steps:
(1) the positive active slurry prepared in example 1 was centrally coated on a 300mm (w) aluminum foil by using a transfer coater, the coating width was 160mm along the width direction of the electrode sheet, and 70mm of white remained on each of both sides, and the positive active layer having a thickness of 100 μm was obtained after single-side drying.
(2) The alumina-polyvinylidene fluoride-ceramic slurry A having a solid content of 30% prepared in example 2 was coated on the margin portions on both sides of the electrode sheet, the width of coating was 60mm on each side in the width direction of the electrode sheet, and after the coating was completed, it was dried to obtain a ceramic layer A having a thickness of about 60 μm, which was subjected to roll pressing by compacting at 3.5 g/cc.
(3) The alumina-polyvinylidene fluoride-ceramic slurry B having a solid content of 15% prepared in example 3 was coated on the surface of the positive electrode active layer to a coating width of 160mm, and dried at 120 ℃ to obtain a ceramic layer B having a thickness of 10 μm.
(4) And cutting off the ceramic layers A on two sides of the positive active layer to obtain the positive pole piece.
Example 6
The embodiment provides a positive pole piece and a preparation method thereof. The preparation method comprises the following steps:
(1) the positive active slurry prepared in example 1 was coated on a 300mm (w) aluminum foil in the center by a transfer coater, the coating width was 200mm in the width direction of the electrode sheet, 50mm of white remained on each side, and the positive active layer was dried on one side to obtain a positive active layer with a thickness of 100 μm.
(2) The alumina-polyvinylidene fluoride-ceramic slurry A having a solid content of 30% prepared in example 2 was coated on the margin portions on both sides of the electrode sheet, the width of each side coated was 40mm in the width direction of the electrode sheet, and after the coating was completed, it was dried to obtain a ceramic layer A having a thickness of about 70 μm, and it was subjected to roll pressing by compacting at 3.5 g/cc.
(3) The fumed silica-polyvinylidene fluoride-ceramic slurry B having a solid content of 15% prepared in example 3 was coated on the surface of the positive electrode active layer with a coating width of 200mm, and dried at 120 ℃ to obtain a ceramic layer B having a thickness of 10 μm.
(4) And cutting off the ceramic layers A on two sides of the positive active layer to obtain the positive pole piece.
Example 7
The embodiment provides a positive pole piece and a preparation method thereof. The preparation method comprises the following steps:
(1) the positive active slurry prepared in example 1 was coated on a 300mm (w) aluminum foil in the center by a transfer coater, the coating width was 200mm in the width direction of the electrode sheet, 50mm of white remained on each side, and the positive active layer was dried on one side to obtain a positive active layer with a thickness of 100 μm.
(2) The alumina-polyvinylidene fluoride-ceramic slurry A having a solid content of 30% prepared in example 2 was coated on the margin portions on both sides of the electrode sheet, the width of each side coated was 40mm in the width direction of the electrode sheet, and after the coating was completed, it was dried to obtain a ceramic layer A having a thickness of about 70 μm, and it was subjected to roll pressing by compacting at 3.5 g/cc.
(3) The alumina-polyvinyl alcohol-ceramic slurry B prepared in example 3, which had a solid content of 15%, was coated on the surface of the positive electrode active layer, with a coating width of 200mm, and dried at 120 ℃ to obtain a ceramic layer B having a thickness of 10 μm.
(4) And cutting off the ceramic layers A on two sides of the positive active layer to obtain the positive pole piece.
Example 8
The embodiment provides a positive pole piece and a preparation method thereof. The preparation method comprises the following steps:
(1) the positive active slurry prepared in example 1 was coated on a 300mm (w) aluminum foil in the center by a transfer coater, the coating width was 200mm in the width direction of the electrode sheet, 50mm of white remained on each side, and the positive active layer was dried on one side to obtain a positive active layer with a thickness of 100 μm.
(2) The alumina-polyvinylidene fluoride-ceramic slurry A having a solid content of 30% prepared in example 2 was coated on the margin portions on both sides of the electrode sheet, the width of each side coated was 40mm in the width direction of the electrode sheet, and after the coating was completed, it was dried to obtain a ceramic layer A having a thickness of about 70 μm, and it was subjected to roll pressing by compacting at 3.5 g/cc.
(3) The alumina-polyvinyl alcohol-ceramic slurry B prepared in example 3, which had a solid content of 15%, was coated on the surface of the positive electrode active layer, with a coating width of 200mm, and dried at 120 ℃ to obtain a ceramic layer B having a thickness of 10 μm.
(4) And cutting off the ceramic layers A on two sides of the positive active layer to obtain the positive pole piece.
Example 9
The embodiment provides a positive pole piece and a preparation method thereof. The preparation method comprises the following steps:
(1) the positive active slurry prepared in example 1 was coated on 300mm (w) aluminum foil in the center by a transfer coater, the coating width was 180mm along the width direction of the electrode sheet, and 60mm of white left on each side, and the positive active layer was dried on one side to obtain a positive active layer with a thickness of 100 μm.
(2) The boehmite-polyvinylidene fluoride-ceramic slurry A having a solid content of 45% prepared in example 2 was applied to the margins on both sides of the electrode sheet in the width direction of the electrode sheet with a width of 40mm on each side, and after completion of the application, dried to give a ceramic layer A having a thickness of about 70 μm, and subjected to roll pressing with compaction of 3.5 g/cc.
(3) Boehmite-polyvinylidene fluoride-ceramic slurry B having a solid content of 5% prepared in example 3 was coated on the surface of a positive electrode active layer to a coating width of 200mm, and dried at 120 ℃ to obtain a ceramic layer B having a thickness of 10 μm.
(4) And cutting off the ceramic layers A on two sides of the positive active layer to obtain the positive pole piece.
Comparative example 1
The comparative example provides a positive pole piece and a preparation method thereof.
(1) The positive electrode active slurry prepared in example 1 was centrally coated on a 300mm (w) aluminum foil with a coating width of 280mm by using a transfer coater, 10mm of white was left on each side, and the positive electrode active layer with a thickness of 100 μm was obtained after single-side drying.
(2) The alumina-polyvinylidene fluoride-ceramic slurry B having a solid content of 15% prepared in example 3 was coated on the surface of the positive electrode active layer, with a coating width of 200mm, and dried at 120 ℃ to obtain a ceramic layer B having a thickness of 10 μm.
(3) And cutting off the margins on two sides of the positive active layer to obtain the positive pole piece.
Comparative example 2
The comparative example provides a positive pole piece and a preparation method thereof.
(1) The positive electrode active slurry prepared in example 1 was centrally coated on a 300mm (w) aluminum foil with a coating width of 280mm by using a transfer coater, 10mm of white was left on each side, and the positive electrode active layer with a thickness of 100 μm was obtained after single-side drying.
(2) The alumina-polyvinylidene fluoride-ceramic slurry B having a solid content of 15% prepared in example 3 was coated on the surface of the positive electrode active layer with a coating width of 280mm, and dried at 120 ℃ to obtain a ceramic layer B having a thickness of 10 μm.
(3) And cutting off the margins on two sides of the positive active layer to obtain the positive pole piece.
Comparative example 3
The comparative example provides a positive pole piece and a preparation method thereof.
(1) The positive electrode active slurry prepared in example 1 was centrally coated on a 300mm (w) aluminum foil with a width of 200mm by using a transfer coater, 10mm of white was left on each side, and the positive electrode active layer was dried on one side to obtain a thickness of 100 μm.
(2) The alumina-polyvinylidene fluoride-ceramic slurry B having a solid content of 15% prepared in example 3 was coated on the surface of the positive electrode active layer, with a coating width of 200mm, and dried at 120 ℃ to obtain a ceramic layer B having a thickness of 10 μm.
(3) And cutting off the margins on two sides of the positive active layer to obtain the positive pole piece.
Comparative example 4
The comparative example provides a positive pole piece and a preparation method thereof.
(1) The positive active slurry prepared in example 1 was coated on 300mm (w) aluminum foil in the center by a transfer coater, the coating width was 240mm along the width direction of the electrode sheet, 30mm of white left on each side, and the positive active layer was dried on one side to obtain a positive active layer with a thickness of 100 μm.
(2) The alumina-polyvinylidene fluoride-ceramic slurry A having a solid content of 30% prepared in example 2 was coated on the margin portions on both sides of the electrode sheet, the width of each side coated was 20mm in the width direction of the electrode sheet, and after the coating was completed, it was dried to obtain a ceramic layer A having a thickness of about 70 μm, and it was subjected to roll pressing by compacting at 3.5 g/cc.
(3) The alumina-polyvinylidene fluoride-ceramic slurry B having a solid content of 15% prepared in example 3 was coated on the surface of the positive electrode active layer to a coating width of 240mm, and dried at 120 ℃ to obtain a ceramic layer B having a thickness of 10 μm.
(4) And cutting off the ceramic layers A on two sides of the positive active layer to obtain the positive pole piece.
Comparative example 5
The comparative example provides a positive pole piece and a preparation method thereof.
(1) The positive active slurry prepared in example 1 was coated on a 300mm (w) aluminum foil in the center by a transfer coater, the coating width was 200mm in the width direction of the electrode sheet, 50mm of white remained on each side, and the positive active layer was dried on one side to obtain a positive active layer with a thickness of 100 μm.
(2) The alumina-polyvinylidene fluoride-ceramic slurry A having a solid content of 30% prepared in example 2 was coated on the margin portions on both sides of the electrode sheet, the width of each side coated was 30mm in the width direction of the electrode sheet, and after the coating was completed, it was dried to obtain a ceramic layer A having a thickness of about 70 μm, and it was subjected to roll pressing by compacting at 3.5 g/cc.
(3) The alumina-polyvinylidene fluoride-ceramic slurry B having a solid content of 15% prepared in example 3 was coated on the surface of the positive electrode active layer with a coating width of 200mm, and dried at 120 ℃ to obtain a ceramic layer B having a thickness of 10 μm.
(4) And cutting off the ceramic layers A on two sides of the positive active layer to obtain the positive pole piece.
Comparative example 6
The embodiment provides a positive pole piece and a preparation method thereof. The preparation method comprises the following steps:
(1) the positive active slurry prepared in example 1 was coated on a 300mm (w) aluminum foil in the center by a transfer coater, the coating width was 200mm in the width direction of the electrode sheet, 50mm of white remained on each side, and the positive active layer was dried on one side to obtain a positive active layer with a thickness of 100 μm.
(2) The alumina-polyvinylidene fluoride-ceramic slurry B having a solid content of 15% prepared in example 3 was applied to the margins on both sides of the electrode sheet, and the width of each side was 40mm in the width direction of the electrode sheet, and after the application was completed, it was dried to obtain a ceramic layer A having a thickness of about 70 μm, and it was rolled by compacting at 3.5 g/cc.
(3) The alumina-polyvinylidene fluoride-ceramic slurry B having a solid content of 15% prepared in example 3 was coated on the surface of the positive electrode active layer with a coating width of 200mm, and dried at 120 ℃ to obtain a ceramic layer B having a thickness of 10 μm.
(4) And cutting off the ceramic layers A on two sides of the positive active layer to obtain the positive pole piece.
Testing
The pole pieces prepared in the examples 4-9 and the comparative examples 1-6 are evaluated, and the evaluation method comprises the following steps:
the curling height of the pole piece is as follows: after the pole piece is taken out of the oven, a right angle gauge is adopted to visually measure the curling height;
the breaking strength of the pole piece is as follows: the test was performed according to GB/T228.
The results are shown in Table 1:
TABLE 1
As can be seen from Table 1, according to the coating method of the pole piece provided by the invention, the edge curl height of the positive pole piece prepared in the embodiments 4 to 9 is 3.2mm to 7.7mm, and the breaking strength of the pole piece can reach 173MPa to 185 MPa.
Combining the results of comparative example 1, it can be seen that if the width of the ceramic coating is smaller than that of the positive active layer, although normal production can be achieved and the aluminum foil at the edge of the electrode plate is not warped, the active layer not coated with the ceramic layer needs to be cut off subsequently, which causes waste. Combining the results of comparative example 2, it can be seen that if the margin of the electrode sheet is small, the coating area of the positive electrode active layer is the same as that of the ceramic layer coated on the positive electrode active layer, and the electrode sheet is severely warped. It can be seen from the results of comparative example 3 that if the edge margin of the electrode sheet is large and no substance is applied, the electrode sheet is likely to wrinkle during rolling, and the edge is not rigid enough, and the edge is likely to curl when a ceramic coating is applied. Combining the results of comparative examples 4 and 5, it is clear that the edge coating width is too narrow, and the rolling damage is small, so that the tensile strength of the pole piece can be maintained, but the phenomenon of pole piece curling is still obvious. It can be seen from the results of comparative example 6 that at lower solids content of the edge-coated ceramic, the edge coating thickness is too thin and has limited effect on roll wrinkle reduction and secondary coating curl resistance.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. A preparation method of a pole piece is characterized by comprising the following steps:
respectively forming an active layer and two ceramic layers A on the surface of the pole piece, carrying out rolling treatment on the pole piece containing the active layer and the ceramic layers A, and then forming a ceramic layer B on the whole active layer;
the active layer is positioned between the two ceramic layers A and is connected with the ceramic layers A; along the width direction of the pole piece, the distances between the two ends of the active layer and the corresponding ends of the pole piece are both larger than or equal to 50mm, and the width of the ceramic layer A is larger than or equal to 40 mm;
the ceramic layer A is made of ceramic slurry A, the ceramic layer B is made of ceramic slurry B, and the solid content of the ceramic slurry A is larger than that of the ceramic slurry B.
2. The preparation method of the pole piece according to claim 1, wherein the thickness of the ceramic layer A is 50-80% of the thickness of the active layer; the thickness of the ceramic layer B is 5% -20% of that of the active layer.
3. The preparation method of the pole piece according to claim 2, wherein the active layer is made of active slurry, and the solid content of the active slurry is 69% -73%; the solid content of the ceramic slurry A is 30-50%; the solid content of the ceramic slurry B is 5-15%.
4. The method for preparing the pole piece according to any one of claims 1 to 3, wherein the ceramic slurry A comprises ceramic powder A and polymer A;
the ceramic powder A is selected from at least one of aluminum oxide, boehmite, titanium oxide, zirconium oxide, silicon oxide, soapstone, lithium iron phosphate and lithium manganese iron phosphate;
the polymer A is selected from at least one of polytetrafluoroethylene, polyvinylidene fluoride-hexafluoropropylene, polyacrylonitrile, polyethylene glycol, polymethyl acrylate and polyvinyl alcohol;
the mass ratio of the ceramic powder A to the polymer A is (88-95): (5-12).
5. The method for preparing the pole piece according to any one of claims 1 to 3, wherein the ceramic slurry B comprises a ceramic powder B and a polymer B;
the ceramic powder B is selected from at least one of aluminum oxide, boehmite, titanium oxide, zirconium oxide, silicon oxide, soapstone, lithium iron phosphate and lithium manganese iron phosphate;
the polymer B is selected from at least one of polytetrafluoroethylene, polyvinylidene fluoride-hexafluoropropylene, polyacrylonitrile, polyethylene glycol, polymethyl acrylate and polyvinyl alcohol;
the mass ratio of the ceramic powder B to the polymer B is (0.8-1.2): (0.8 to 1.2).
6. The method for preparing the pole piece according to claim 5, wherein the active slurry comprises an active substance, a conductive agent and a binder;
the active material is selected from at least one of lithium-rich manganese base, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminate, lithium iron phosphate and lithium cobaltate;
the conductive agent is selected from at least one of carbon black, carbon nano tubes, conductive fibers, Ketjen black, graphene and conductive graphite;
at least one of polytetrafluoroethylene and polyvinylidene fluoride as the binder;
the mass ratio of the active substance, the conductive agent and the adhesive is (94-99), (0.5-3) to (0.5-3).
7. The method for preparing the electrode plate according to claim 6, wherein the solvents used for the ceramic slurry A and the ceramic slurry B are respectively and independently selected from at least one of N-methylpyrrolidone, N-dimethylformamide, dimethyl sulfoxide, isopropanol, tert-butanol, benzene, toluene and tetrahydrofuran.
8. The method for preparing the pole piece according to claim 7, wherein the active slurry, the ceramic slurry A and the ceramic slurry B are applied by transfer type intermittent coating; and/or
After the ceramic layer B is formed, a step of removing the ceramic layer a is further included.
9. The pole piece prepared by the preparation method of any one of the pole pieces of claims 1 to 8.
10. An automobile or electronic product, characterized in that the pole piece used for the power supply is the pole piece according to claim 9.
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| CN105449159A (en) * | 2015-03-12 | 2016-03-30 | 万向A一二三系统有限公司 | Positive plate of lithium-ion battery with high safety performance and fabrication method of positive plate |
| US9343745B1 (en) * | 2013-02-07 | 2016-05-17 | A123 Systems Llc | Surface passivation of active material particles for use in electrochemical cells |
| CN109244362A (en) * | 2018-11-05 | 2019-01-18 | 宁德新能源科技有限公司 | Anode pole piece, electrochemical appliance and the electronic device comprising it |
| CN111584827A (en) * | 2020-05-29 | 2020-08-25 | 昆山宝创新能源科技有限公司 | Lithium battery negative pole piece and preparation method and application thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US9343745B1 (en) * | 2013-02-07 | 2016-05-17 | A123 Systems Llc | Surface passivation of active material particles for use in electrochemical cells |
| CN105449159A (en) * | 2015-03-12 | 2016-03-30 | 万向A一二三系统有限公司 | Positive plate of lithium-ion battery with high safety performance and fabrication method of positive plate |
| CN109244362A (en) * | 2018-11-05 | 2019-01-18 | 宁德新能源科技有限公司 | Anode pole piece, electrochemical appliance and the electronic device comprising it |
| CN111584827A (en) * | 2020-05-29 | 2020-08-25 | 昆山宝创新能源科技有限公司 | Lithium battery negative pole piece and preparation method and application thereof |
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