CN116072805A - Preparation method of battery pole piece and all-solid-state battery - Google Patents
Preparation method of battery pole piece and all-solid-state battery Download PDFInfo
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- CN116072805A CN116072805A CN202310314994.3A CN202310314994A CN116072805A CN 116072805 A CN116072805 A CN 116072805A CN 202310314994 A CN202310314994 A CN 202310314994A CN 116072805 A CN116072805 A CN 116072805A
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- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
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- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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- 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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- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
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Abstract
The invention provides a battery pole piece and a preparation method of an all-solid-state battery, and belongs to the technical field of lithium ion battery manufacturing. The preparation method of the battery pole piece comprises the following steps: mixing an active material, a sulfur-containing solid electrolyte, a halogen-containing binder, a conductive agent and a pole piece solvent to obtain pole piece slurry; coating the pole piece slurry on a current collector, and drying at 40-80 ℃ for 4-24 hours to obtain a prefabricated pole piece; and carrying out heat treatment on the prefabricated pole piece in a vacuum environment at 80-200 ℃ for 4-12 hours to obtain the battery pole piece. The prepared battery pole piece can ensure that the low porosity of the pole piece plays a good capacity performance, and can trigger the reaction of the halogen-containing binder and the sulfur-containing solid electrolyte.
Description
Technical Field
The invention belongs to the technical field of lithium ion battery manufacturing, and particularly relates to a battery pole piece and a preparation method of an all-solid-state battery.
Background
With the rapid development of lithium ion batteries, the lithium ion batteries are widely applied to various fields, in particular to new energy automobiles. With the rapid increase of sales of new energy automobiles, the demand of power batteries is increasing. However, according to the current use condition of the new energy electric automobile, two phenomena of anxiety appear: endurance mileage and safety in use. Since the liquid battery inevitably uses an organic electrolyte that is flammable and easily leaked, an all-solid battery in which a separator and an electrolyte in the liquid battery are replaced with a solid electrolyte membrane has been attracting attention.
Currently, all-solid batteries mainly include sulfide all-solid batteries, oxide all-solid batteries and polymer all-solid batteries; among them, sulfide all-solid-state batteries are distinguished by high ionic conductivity and excellent processing characteristics of sulfur-containing solid-state electrolytes. The existing sulfide all-solid-state preparation process mainly comprises a dry method and a wet method, wherein the wet method has higher industrialization potential due to high matching degree with the existing equipment and high production line. The wet process has the greatest advantage that an ultrathin electrolyte membrane can be prepared, and the full-solid battery is promoted to exert the advantage of high energy density.
The performance of the current all-solid-state battery is still limited, namely, the contact resistance of two solid-solid surfaces of an electrolyte membrane and a pole piece is large. Therefore, electrolyte membrane slurry can be directly coated on the positive and negative pole pieces through a wet process, the process not only can reduce interface impedance of the pole pieces and the electrolyte membrane, but also is convenient for controlling the thickness of the electrolyte membrane, and in addition, the subsequent assembly process can be simplified, so that the process is a current process means with comprehensive advantages. However, the prior art has great problems: when the electrolyte membrane slurry is directly coated on the positive electrode plate and the negative electrode plate, the solvent can permeate into the electrode plate layer, so that the binder in the electrode plate layer is swelled again and separated out, the uniform distribution of the binder in the electrode plate layer is damaged, components such as an active material are separated from a current collector, and the performance of the active material is seriously affected.
Disclosure of Invention
In order to solve the above problems, the present invention provides a method for preparing a battery pole piece, comprising:
mixing an active material, a sulfur-containing solid electrolyte, a halogen-containing binder, a conductive agent and a pole piece solvent to obtain pole piece slurry;
coating the pole piece slurry on a current collector, and drying for 4-24 hours at 40-80 ℃ to obtain a prefabricated pole piece;
and carrying out heat treatment on the prefabricated pole piece for 4-12 hours in a vacuum environment at 80-200 ℃ to obtain the battery pole piece.
Preferably, after the prefabricated pole piece is subjected to heat treatment in a vacuum environment at 80-200 ℃ for 4-12 hours to obtain the battery pole piece, the method further comprises the following steps:
and coating electrolyte membrane slurry on the surface of the battery pole piece, and then drying at 50-200 ℃ for 12-24 hours.
Preferably, the electrolyte membrane slurry includes a membrane electrolyte, a membrane binder, and a membrane solvent.
Preferably, the electrolyte membrane slurry is prepared by the following method:
and mixing the membrane electrolyte, the membrane binder and the membrane solvent at 500rpm-1000rpm for 30 minutes-180 minutes to prepare the electrolyte membrane slurry.
Preferably, the mass ratio of the membrane electrolyte to the membrane binder is (85-100): 5.
Preferably, the active material includes a positive electrode active material and a negative electrode active material;
mixing an active material, a sulfur-containing solid electrolyte, a halogen-containing binder, a conductive agent and a pole piece solvent to obtain pole piece slurry, wherein the pole piece slurry comprises the following components:
mixing the positive electrode active material, the sulfur-containing solid electrolyte, the halogen-containing binder, the conductive agent and the pole piece solvent to prepare positive electrode pole piece slurry; and/or
And mixing the negative electrode active material, the sulfur-containing solid electrolyte, the halogen-containing binder, the conductive agent and the pole piece solvent to prepare the negative electrode pole piece slurry.
Preferably, in the positive electrode sheet slurry, the charging ratio of the positive electrode active material to the sulfur-containing solid electrolyte to the halogen-containing binder to the conductive agent is (60-80): 15-25): 3-7: (3-7).
Preferably, in the anode plate slurry, the charging ratio of the anode active material to the sulfur-containing solid electrolyte to the halogen-containing binder to the conductive agent is (65-75): (25-22): (3-6): (3-6).
Preferably, the positive electrode active material is NCM811, NCM 523, NCM622, liFePO 4 At least one of (a) and (b);
the negative electrode active material is silicon carbon, graphite or LiCoO 2 At least one of (a) and (b);
the sulfur-containing solid electrolyte is LPSC651, LPS314, li 2 S-P 2 S 5 At least one of (a) and (b);
the conductive agent is at least one of VGCF, CNTs and Super P;
the halogen-containing binder is at least one of PVDF-CTFE, PVDF, PVDF-HFP and vinyl silicone oil;
the pole piece solvent is at least one of isobutyl isobutyrate, butyl butyrate, ethyl acetate, butyl acetate, benzyl acetate, toluene, xylene and paraxylene;
the membrane electrolyte is LPSC651, LPS314, li 2 S-P 2 S 5 At least one of (a) and (b);
the film binder is at least one of PVDF-CTFE, PVDF, PVDF-HFP and vinyl silicone oil;
the film solvent is at least one of isobutyl isobutyrate, butyl butyrate, ethyl acetate, butyl acetate, benzyl acetate, toluene, xylene and paraxylene.
In addition, in order to solve the above problems, the present invention also provides a method for preparing an all-solid-state battery, comprising:
cutting the battery pole piece prepared by the preparation method of the battery pole piece into a wafer; the wafer comprises a positive electrode wafer and a negative electrode wafer;
placing the positive electrode wafer in a mould, and pressing for 1 to 4 minutes under the pressure of 200 to 350 MPa;
and then placing the negative electrode wafer in the die, attaching the negative electrode wafer to the positive electrode wafer, and pressing for 1 to 4 minutes under the pressure of 200 to 350MPa to obtain the all-solid-state battery.
The invention provides a preparation method of a battery pole piece, which comprises the following steps: mixing an active material, a sulfur-containing solid electrolyte, a halogen-containing binder, a conductive agent and a pole piece solvent to obtain pole piece slurry; coating the pole piece slurry on a current collector, and drying for 4-24 hours at 40-80 ℃ to obtain a prefabricated pole piece; and carrying out heat treatment on the prefabricated pole piece for 4-12 hours in a vacuum environment at 80-200 ℃ to obtain the battery pole piece.
According to the preparation method of the battery pole piece, the prefabricated pole piece is obtained by drying treatment after pole piece slurry is obtained, and the battery pole piece is obtained by performing heat treatment on the prefabricated pole piece after drying treatment, wherein the drying treatment and the heat treatment processes are simple in operation and obvious in effect, the industrialization promotion of all solids is not affected, the process is convenient for controlling the thickness of an electrolyte membrane, an ultrathin electrolyte membrane layer is prepared, and the advantage of high energy density of an all-solid-state battery is fully exerted.
After the prefabricated pole piece is coated by a wet method, the drying temperature has great influence on the porosity of the pole piece and the dispersion of components. If the drying temperature of the prefabricated pole piece is too high, the pole piece porosity is increased, the binder floats up, and the like. Too low a temperature may result in incomplete volatilization of the solvent, which may increase the internal resistance of the electrode sheet and deteriorate the electrical properties of the electrode sheet. The dried positive and negative pole pieces are reheated to promote the binder and the sulfur-containing solid electrolyte to form a locking effect so as to inhibit the swelling of the binder in the electrode layer caused by the solvent penetrating into the electrode layer when the electrolyte membrane slurry is subsequently coated, thereby avoiding the influence on the properties of the positive and negative pole pieces.
Drawings
Fig. 1 is a schematic flow chart of a method for preparing a battery pole piece provided in this embodiment;
FIG. 2 is a schematic illustration of the reaction mechanism of a sulfur-containing solid electrolyte with a halogen-containing binder (PVDF-CTFE);
fig. 3 is a schematic view of the first-turn charge and discharge curves of all-solid batteries prepared in example 1 and comparative example 1;
fig. 4 is a schematic diagram of the first-turn charge and discharge curves of the prepared all-solid battery in example 2;
fig. 5 is a schematic diagram of the first-turn charge and discharge curves of the prepared all-solid battery in example 3.
The achievement of the objects, functional features and advantages of the present invention will be further described with reference to the accompanying drawings, in conjunction with the embodiments.
Detailed Description
The technical solutions of the present invention will be clearly and completely described in connection with the embodiments, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Unless defined otherwise hereinafter, all technical and scientific terms used in the detailed description of the invention are intended to be identical to what is commonly understood by one of ordinary skill in the art. While the following terms are believed to be well understood by those skilled in the art, the following definitions are set forth to better explain the present invention.
Furthermore, the terms first, second, third, (a), (b), (c), and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.
Unless defined otherwise or clearly indicated by context, all technical and scientific terms in this disclosure have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.
The technical solution of the present invention is further described in detail below with reference to specific embodiments, but the present invention is not limited thereto, and any modifications made by anyone within the scope of the claims of the present invention are still within the scope of the claims of the present invention.
Referring to fig. 1, the embodiment provides a method for preparing a battery pole piece, which includes:
step S100, mixing an active material, a sulfur-containing solid electrolyte, a halogen-containing binder, a conductive agent and a pole piece solvent to obtain pole piece slurry;
step S200, coating the pole piece slurry on a current collector, and drying for 4-24 hours at 40-80 ℃ to obtain a prefabricated pole piece;
and step S300, performing heat treatment on the prefabricated pole piece in a vacuum environment at 80-200 ℃ for 4-12 hours to obtain the battery pole piece.
The pole piece slurry comprises an active material, a sulfur-containing solid electrolyte, a halogen-containing binder, a conductive agent and a pole piece solvent, and is used for preparing a prefabricated pole piece. The prefabricated pole piece is subjected to first heating treatment during preparation, namely the drying treatment flow is to coat pole piece slurry on a current collector and dry the current collector for 4-24 hours at the temperature of 40-80 ℃ to obtain the prefabricated pole piece; further, the prefabricated pole piece after the drying treatment is subjected to the second heat treatment, namely the heat treatment, so that strong interaction occurs between the sulfur-containing solid electrolyte and the halogen-containing binder in the raw materials added during the preparation.
Referring to fig. 2, a schematic representation of the reaction mechanism of a sulfur-containing solid electrolyte with a halogen-containing binder is shown.
Therefore, the halogen-containing binder is locked by the sulfur-containing solid electrolyte, and when the electrolyte membrane is coated on the surfaces of the positive and negative electrode plates, and the solvent permeates into the electrode layers, the halogen-containing binder is locked by the sulfur-containing solid electrolyte, so that the binder in the electrode layers can not be dissolved in the solvent any more when electrolyte membrane slurry is coated on the surfaces of the dried positive and negative electrode plates.
The conditions for the first heating treatment, i.e., the drying treatment, are as follows:
(1) Temperature: 40-80 ℃;
(2) Time: 4 hours to 24 hours.
The conditions of the second heat treatment, namely the heat treatment, are as follows:
(1) Temperature: 80-200 ℃;
(2) Environmental conditions: a vacuum environment;
(3) Time: 4 hours to 12 hours.
In another preferred embodiment, the second heat treatment, i.e. the heat treatment, has a temperature condition in the range of 80 ℃ to 100 ℃.
When the temperature selection range of the heat treatment is 80-100 ℃, the adhesive in the electrode plate layer is still well and uniformly distributed in the original electrode layer, so that the original good adhesion between the active material components in the electrode layer and the current collector and the good adhesion between the components in the electrode layer are ensured, the electrolyte layer is coated on the surface of the positive/negative electrode plate, the electrode layer is ensured to have good mechanical properties, and the excellent electrochemical performance and safety of the battery are ensured.
In addition, the formed C-S bond enhances the interaction force of the binder and the sulfur-containing solid electrolyte, ensures the mechanical property of the pole piece, and improves the shock resistance of the battery pack, thereby improving the safety of the battery pack.
The heat treatment is carried out at a temperature of 80-100deg.C, and the principle of the heat treatment is as follows:
first, in the preparation of pole pieces, in principle, the lower the porosity of the pole piece is required, the better. Because in all-solid-state batteries, the surrounding active material cannot exert capacity properties due to the absence of ion and electron pathways at the pores present in the pole pieces. Therefore, extremely low porosity is required in preparing positive and negative electrode sheets of all-solid batteries. The positive and negative plates are prepared by adopting a wet process, the solvent is required to be removed by a drying process, and the drying process is closely related to the porosity of the plates.
According to research, if the temperature is too high, the solvent is volatilized rapidly, the solid component of the electrolyte layer cannot be self-stitched, a large number of pores can be formed, so that even the subsequent rolling compaction is low, and finally the volumetric energy density of the battery can be reduced; the energy density of the battery is also reduced because the active material at the pores cannot exert capacity properties. If the temperature is too low, the solvent cannot be completely volatilized, so that the internal resistance of the positive and negative electrode plates is increased, and the electrical performance of the electrode plates is deteriorated. Therefore, a moderate temperature is required to be selected when preparing the positive and negative electrode plates; the pole piece drying process after the solid-state battery optimization is that the pole piece is dried for a long time (12-36 hours) at 40-60 ℃, and the optimal condition is 50 ℃ for 24 hours.
However, experiments prove that the temperature of the halogen-containing binder (for example, PVDF-CTFE, vinylidene fluoride-chlorotrifluoroethylene copolymer) and the sulfur-containing solid electrolyte are required to be higher than 80 ℃, so that the temperature requirements of the two heating processes (the drying process for preparing the positive and negative electrode plates and the heat treatment process for the positive and negative electrode plates) are inconsistent, and contradiction occurs: on one hand, the temperature required by the pole piece preparation process is 40-60 ℃; on the other hand, the reaction between PVDF-CTFE and the sulfur-containing solid electrolyte needs to be higher than 80 ℃; while the upper temperature limit experienced between all components is 180 ℃.
According to the contradiction in the preparation process, there are two cases:
(1) If only the reaction between the halogen-containing binder and the sulfur-containing solid electrolyte is ensured, a one-step drying mode is adopted, and the temperature condition of 80 ℃ or more is directly adopted in the drying process, so that the porosity in the positive and negative electrode plates is extremely high, and the situation that the electrode plate electrical property is greatly degraded occurs.
(2) If only the electric performance of the pole piece is ensured, a one-step drying mode is adopted, the temperature condition of 40-60 ℃ is directly adopted in the drying process, the reaction of the halogen-containing binder and the sulfur-containing solid electrolyte can not occur, and the purpose of experimental design can not be achieved.
Therefore, in the method for manufacturing an all-solid battery provided in this embodiment, first, the preparation of the prefabricated electrode sheet is required, and in the manufacturing process, the drying process (first heat treatment) is required for the prefabricated electrode sheet; then, the dried prefabricated pole piece is subjected to heat treatment (second heat treatment). And carrying out heat treatment on the dried prefabricated pole piece, so that the low porosity of the pole piece can be ensured to exert good capacity performance, and the reaction of the halogen-containing binder and the sulfur-containing solid electrolyte can be triggered.
The invention is aimed at the prefabricated pole piece after the drying treatment process and then carries out the heat treatment process, wherein the heat treatment process has simple operation and obvious effect, does not influence the industrialized promotion of all solids, directly coats electrolyte slurry on the surfaces of the positive and negative poles to form an electrolyte membrane and the positive and negative poles into a whole, can reduce the impedance of two solid-solid interfaces of the pole piece and the electrolyte membrane, and simultaneously, the process is convenient for controlling the thickness of the electrolyte membrane, prepares an ultrathin electrolyte membrane layer and fully exerts the advantage of high energy density of the all-solid battery.
After the positive and negative plates are coated by the wet method, the drying temperature has great influence on the porosity of the plates and the dispersion of components. If the drying temperature of the prefabricated pole piece is too high, the pole piece porosity is increased, the binder floats up, and the like. The dried prefabricated pole piece is subjected to heating treatment to promote the binder and the sulfur-containing solid electrolyte to form a locking effect so as to inhibit the swelling of the binder in the electrode layer caused by the solvent penetrating into the electrode layer when the electrolyte membrane slurry is subsequently coated, thereby avoiding the influence on the attribute of the prefabricated pole piece.
Further, the step S300 is performed to heat treat the prefabricated pole piece in a vacuum environment at 80-200 ℃ for 4-12 hours, and after obtaining the battery pole piece, the method further includes:
and step S400, coating electrolyte membrane slurry on the surface of the battery pole piece, and then drying at 50-200 ℃ for 12-24 hours.
The coating process described above can be performed by a SQZ four-sided fabricator.
Further, the electrolyte membrane slurry includes a membrane electrolyte, a membrane binder, and a membrane solvent.
Further, the electrolyte membrane slurry is prepared by the following method:
and mixing the membrane electrolyte, the membrane binder and the membrane solvent at 500rpm-1000rpm for 30 minutes-180 minutes to prepare the electrolyte membrane slurry.
Above-mentioned, when mixing, the equipment that adopts can be the battle array ball mill, also can be other equipment of mixing thick liquid.
Further, the mass ratio of the membrane electrolyte to the membrane binder is (85-100): 5.
Further, the active materials include a positive electrode active material and a negative electrode active material;
step S100, mixing an active material, a sulfur-containing solid electrolyte, a halogen-containing binder, a conductive agent and a pole piece solvent to obtain pole piece slurry, wherein the step comprises the following steps:
mixing the positive electrode active material, the sulfur-containing solid electrolyte, the halogen-containing binder, the conductive agent and the pole piece solvent to prepare positive electrode pole piece slurry; and/or
And mixing the negative electrode active material, the sulfur-containing solid electrolyte, the halogen-containing binder, the conductive agent and the pole piece solvent to prepare the negative electrode pole piece slurry.
When the positive electrode plate slurry and/or the negative electrode plate slurry are prepared, slurry mixing of various components is needed, and the adopted equipment can be an array ball mill or other slurry mixing equipment.
Above, when preparing the positive pole piece slurry and/or the negative pole piece slurry, the preparation method may be: and (3) mixing the active material (positive electrode active material/negative electrode active material), the sulfur-containing solid electrolyte, the halogen-containing binder, the conductive agent and the pole piece solvent at the rotating speed of 200rpm-1000rpm for 5 minutes to 60 minutes to obtain positive electrode pole piece slurry and/or negative electrode pole piece slurry.
Further, in the positive electrode plate slurry, the charging proportion of the positive electrode active material, the sulfur-containing solid electrolyte, the halogen-containing binder and the conductive agent is (60-80): 15-25): 3-7.
Further, in the anode piece slurry, the anode active material, the sulfur-containing solid electrolyte, the halogen-containing binder and the conductive agent are mixed in a feeding ratio of (65-75): 25-22): 3-6: (3-6).
Further, the positive electrode active material is NCM811, NCM 523, NCM622, liFePO 4 At least one of (a) and (b);
the negative electrode active material is silicon carbon, graphite or LiCoO 2 At least one of (a) and (b);
the sulfur-containing solid electrolyte is LPSC651, LPS314, li 2 S-P 2 S 5 At least one of (a) and (b);
the conductive agent is at least one of VGCF, CNTs and Super P;
the halogen-containing binder is at least one of PVDF-CTFE, PVDF, PVDF-HFP and vinyl silicone oil;
the pole piece solvent is at least one of isobutyl isobutyrate, butyl butyrate, ethyl acetate, butyl acetate, benzyl acetate, toluene, xylene and paraxylene;
the membrane electrolyte is LPSC651, LPS314, li 2 S-P 2 S 5 At least one of (a) and (b);
the film binder is at least one of PVDF-CTFE, PVDF, PVDF-HFP and vinyl silicone oil;
the film solvent is at least one of isobutyl isobutyrate, butyl butyrate, ethyl acetate, butyl acetate, benzyl acetate, toluene, xylene and paraxylene.
As described above, in this embodiment, the adhesive is selected to be a halogen-containing adhesive, and may include PVDF-CTFE (vinylidene fluoride-chlorotrifluoroethylene copolymer), PVDF (polyvinylidene fluoride), PVDF-HFP (polyvinylidene fluoride-hexafluoropropylene copolymer), and vinyl silicone oil, and may be a vinylidene fluoride chlorotrifluoroethylene copolymer or the like, which is used as an adhesive, for example PVDF-CTFE, and has good adhesion and can be dissolved in a solvent having a small influence on the performance of the sulfur-containing solid electrolyte, so that the ionic conductivity of the sulfur-containing solid electrolyte is not adversely affected due to the introduction of the adhesive and the solvent, and the ionic conductivity of the sulfur-containing solid electrolyte is the most basic guarantee for the performance of the active material capacity.
In addition, the embodiment also provides a preparation method of the all-solid-state battery, which comprises the following steps:
step S10, cutting the battery pole piece prepared by the preparation method of the battery pole piece into a wafer; the wafer comprises a positive electrode wafer and a negative electrode wafer;
s20, placing the positive electrode wafer in a die, and pressing for 1 to 4 minutes under the pressure of 200 to 350 MPa;
and S30, placing the negative electrode wafer in the die, attaching the negative electrode wafer to the positive electrode wafer, and pressing for 1 to 4 minutes under the pressure of 200 to 350MPa to obtain the all-solid-state battery.
The size of the positive electrode wafer may be different from that of the negative electrode wafer. For example, the cutting size of the positive electrode wafer is 8mm, and the cutting size of the negative electrode wafer is 10mm.
In the pressing, the positive wafer was first placed in a mold, pressed for 2 minutes, and pressed with a pressure of 2.5T. Then, the negative electrode wafer was further added, and the mixture was pressed with a pressure of 2.5T for 2 minutes. The die holder was tightened with a 3N torque wrench, and then a charge and discharge test was performed at 45 c using a current of 0.2 mA.
The invention is further illustrated by the following specific examples, but it should be understood that these examples are for the purpose of illustration only and are not to be construed as limiting the invention in any way.
Example 1
1. Preparation of a positive electrode-electrode plate: (1) 2.94g of positive electrode active material NCM811, 0.84g of sulfur-containing solid electrolyte LPSC651, 0.21g of halogen-containing binder PVDF-CTFE and 0.21g of conductive agent VGCF are weighed out, and 3.78g of solvent isobutyl isobutyrate is added; (2) And (3) mixing slurry for 60min at a rotating speed of 1000rpm in a vibration ball mill, coating the slurry on an aluminum foil by using a 250um SQZ four-side preparation device, and drying at 50 ℃ for 24 hours to obtain the positive electrode-battery pole piece.
2. Preparation of a negative electrode-electrode plate: (1) Weighing 0.697g of anode active material Si/C-450, 0.185g of solid electrolyte LPSC651, 0.046g of binder PVDF-CTFE and 0.046g of conductive agent VGCF; (2) Mixing slurry for 60min at 1000rpm in a vibration ball mill, coating the slurry on a stainless steel foil by using a 200um SQZ four-side preparation device, and drying at 50 ℃ for 24 hours to obtain the cathode-battery pole piece.
3. Coating of electrolyte membrane slurry: (1) heat treatment: firstly, respectively placing the positive electrode-battery pole piece and the negative electrode-battery pole piece in a vacuum environment at 80 ℃ for 12 hours; (2) 2.0g of sulfur-containing solid electrolyte LPSC651 and 0.105g of halogen-containing binder PVDF-CTFE are weighed out, and 1.65g of isobutyl isobutyrate is added as a solvent; (3) Mixing slurry for 60min at 1000rpm in a vibration ball mill, coating the slurry on the positive electrode-battery pole piece and the negative electrode-battery pole piece after heat treatment by using a 200um SQZ four-side preparation device, and drying at 50 ℃ for 24 hours to obtain a coated positive electrode-battery pole piece (coated positive electrode piece) and a coated negative electrode-battery pole piece (coated negative electrode piece) respectively.
4. Assembly of all-solid-state battery: (1) The coated positive plate and the coated negative plate were cut into 8mm positive plates (positive-battery plates) and 10mm negative plates (negative-battery plates), respectively. (2) Firstly, placing and coating a positive electrode wafer in a mould, and pressing for 2 minutes by using the pressure of 2.5T; (3) adding a negative electrode wafer, and pressing for 2min by using the pressure of 2.5T; wherein, the mould frame is screwed by a torque wrench of 3N.
Example 2: in this example, only 3 (1) heat treatment steps are different from example 1.
The heat treatment step of 3 (1) in this embodiment is: the positive electrode plate and the negative electrode plate are placed in a vacuum environment at 100 ℃ for 12 hours.
The rest of the procedure and raw materials were the same as in example 1.
Example 3: in this example, only 3 (1) heat treatment steps are different from example 1.
The heat treatment step of 3 (1) in this embodiment is: the positive electrode plate and the negative electrode plate are placed in a vacuum environment at 150 ℃ for 12 hours.
The rest of the procedure and raw materials were the same as in example 1.
Comparative example 1: in this comparative example, only 3 (1) heat treatment steps were removed as compared with example 1.
In the comparative example, in step 3, the coated portion of the electrolyte membrane slurry, the prepared positive electrode-battery electrode sheet and negative electrode-battery electrode sheet were not subjected to heat treatment again before the slurry coating.
The rest of the procedure and raw materials were the same as in example 1.
Comparison experiment: the coated positive electrode sheet and the coated negative electrode sheet prepared in example 1-example 3 and comparative example 1, and the all-solid-state battery assembled from the coated positive electrode sheet and the coated negative electrode sheet were respectively subjected to the following experiments for comparison:
1. peel strength test:
(1) Test method and conditions: and (3) adopting a KT-PSA-1056 peeling force tester to test the peeling strength of the prepared coated positive plate and the coated negative plate.
(2) Test results:
TABLE 1 statistical Table of peel strength test results
As can be seen from the test results in table 1 above, the coated positive electrode sheet and the coated negative electrode sheet prepared in examples 1 to 3 using the preparation method provided in this example were higher in peel strength value in the peel strength test than those of comparative example 1 in which the heat treatment step was not separately performed, demonstrating that the method is advantageous in improving the adhesiveness of the active component to the current collector.
2. And (3) charge and discharge testing:
(1) Test method and conditions: the charge and discharge test was performed at 45℃with a current of 0.2 mA.
(2) Test results:
table 2, charge-discharge capacity statistics
Referring to fig. 3 to 5, wherein fig. 3 is a schematic view of first-turn charge and discharge curves of the all-solid batteries prepared in example 1 and comparative example 1; fig. 4 and 5 show charge and discharge curves of example 2 and example 3, respectively. Referring to fig. 1, the charge-discharge curves of comparative example 1 are compared with the charge-discharge curves of examples 1 to 3 of fig. 3 to 5, respectively, and as can be seen from the first-round charge-discharge curves, the capacity performance of the batteries of examples 1 to 3 is significantly better than that of the batteries of comparative examples, and as can be intuitively concluded by referring to the data in table 2 above, it is proved that the method ensures that the adhesiveness of the active component and the current collector ensures the capacity exertion of the active material, thereby improving the capacity of the battery.
In summary, the preparation method of the all-solid-state battery is aimed at carrying out the heat treatment process on the positive electrode plate and the negative electrode plate respectively after the drying treatment process, wherein the heat treatment process has simple operation and obvious effect, does not influence the industrialized promotion of the all-solid state, directly coats electrolyte slurry on the surfaces of the positive electrode and the negative electrode to form an electrolyte membrane and the positive electrode into a whole, can reduce the impedance of two solid-solid interfaces of the electrode plate and the electrolyte membrane, and simultaneously is convenient for controlling the thickness of the electrolyte membrane, preparing an ultrathin electrolyte membrane layer and fully playing the advantage of high energy density of the all-solid-state battery.
After the positive and negative plates are coated by the wet method, the drying temperature has great influence on the porosity of the plates and the dispersion of components. If the drying temperature of the initial pole piece is too high, the pole piece porosity is increased, the binder floats up, and the like. The dried positive and negative pole pieces are subjected to heating treatment to promote the binder and the sulfur-containing solid electrolyte to form a locking effect so as to inhibit the swelling of the binder in the electrode layer caused by the solvent penetrating into the electrode layer when the electrolyte membrane slurry is subsequently coated, thereby avoiding the influence on the properties of the positive and negative pole pieces.
While the preferred embodiments and examples of the present invention have been described, it should be noted that those skilled in the art may make various modifications and improvements without departing from the inventive concept, including but not limited to, adjustments of proportions, procedures, and amounts, which fall within the scope of the present invention. While the preferred embodiments and examples of the present invention have been described, it should be noted that those skilled in the art may make various modifications and improvements without departing from the inventive concept, including but not limited to, adjustments of proportions, procedures, and amounts, which fall within the scope of the present invention.
Claims (10)
1. The preparation method of the battery pole piece is characterized by comprising the following steps:
mixing an active material, a sulfur-containing solid electrolyte, a halogen-containing binder, a conductive agent and a pole piece solvent to obtain pole piece slurry;
coating the pole piece slurry on a current collector, and drying for 4-24 hours at 40-80 ℃ to obtain a prefabricated pole piece;
and carrying out heat treatment on the prefabricated pole piece for 4-12 hours in a vacuum environment at 80-200 ℃ to obtain the battery pole piece.
2. The method for preparing a battery pole piece according to claim 1, wherein the heat treatment of the prefabricated pole piece in a vacuum environment at 80-200 ℃ is carried out for 4-12 hours, and after the battery pole piece is obtained, the method further comprises:
and coating electrolyte membrane slurry on the surface of the battery pole piece, and then drying at 50-200 ℃ for 12-24 hours.
3. The method of manufacturing a battery pole piece of claim 2, wherein the electrolyte membrane slurry comprises a membrane electrolyte, a membrane binder, and a membrane solvent.
4. The method for preparing a battery pole piece according to claim 3, wherein the electrolyte membrane slurry is prepared by the following method:
and mixing the membrane electrolyte, the membrane binder and the membrane solvent at 500rpm-1000rpm for 30 minutes-180 minutes to prepare the electrolyte membrane slurry.
5. A method of manufacturing a battery pole piece as claimed in claim 3, wherein,
the mass ratio of the membrane electrolyte to the membrane binder is (85-100): 5.
6. A method of manufacturing a battery pole piece as claimed in claim 3, wherein,
the active materials include a positive electrode active material and a negative electrode active material;
mixing an active material, a sulfur-containing solid electrolyte, a halogen-containing binder, a conductive agent and a pole piece solvent to obtain pole piece slurry, wherein the pole piece slurry comprises the following components:
mixing the positive electrode active material, the sulfur-containing solid electrolyte, the halogen-containing binder, the conductive agent and the pole piece solvent to prepare positive electrode pole piece slurry; and/or
And mixing the negative electrode active material, the sulfur-containing solid electrolyte, the halogen-containing binder, the conductive agent and the pole piece solvent to prepare the negative electrode pole piece slurry.
7. The method for preparing a battery pole piece according to claim 6, wherein,
in the positive electrode plate slurry, the charging proportion of the positive electrode active material, the sulfur-containing solid electrolyte, the halogen-containing binder and the conductive agent is (60-80): (15-25): (3-7): (3-7).
8. The method of manufacturing a battery pole piece of claim 6, wherein the anode active material, the sulfur-containing solid electrolyte, the halogen-containing binder and the conductive agent are added in the anode pole piece slurry in a ratio of (65-75): (25-22): (3-6): (3-6).
9. The method for preparing a battery pole piece according to claim 6, wherein,
the positive electrode active material isNCM 811、NCM 523、NCM622、LiFePO 4 At least one of (a) and (b);
the negative electrode active material is silicon carbon, graphite or LiCoO 2 At least one of (a) and (b);
the sulfur-containing solid electrolyte is LPSC651, LPS314, li 2 S-P 2 S 5 At least one of (a) and (b);
the conductive agent is at least one of VGCF, CNTs and Super P;
the halogen-containing binder is at least one of PVDF-CTFE, PVDF, PVDF-HFP and vinyl silicone oil;
the pole piece solvent is at least one of isobutyl isobutyrate, butyl butyrate, ethyl acetate, butyl acetate, benzyl acetate, toluene, xylene and paraxylene;
the membrane electrolyte is LPSC651, LPS314, li 2 S-P 2 S 5 At least one of (a) and (b);
the film binder is at least one of PVDF-CTFE, PVDF, PVDF-HFP and vinyl silicone oil;
the film solvent is at least one of isobutyl isobutyrate, butyl butyrate, ethyl acetate, butyl acetate, benzyl acetate, toluene, xylene and paraxylene.
10. A method of manufacturing an all-solid-state battery, comprising:
cutting the battery pole piece prepared by the preparation method of the battery pole piece according to any one of claims 6-9 into a wafer; the wafer comprises a positive electrode wafer and a negative electrode wafer;
placing the positive electrode wafer in a mould, and pressing for 1 to 4 minutes under the pressure of 200 to 350 MPa;
and then placing the negative electrode wafer in the die, attaching the negative electrode wafer to the positive electrode wafer, and pressing for 1 to 4 minutes under the pressure of 200 to 350MPa to obtain the all-solid-state battery.
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| CN117936712A (en) * | 2024-03-21 | 2024-04-26 | 潍柴动力股份有限公司 | Method for improving compactness of positive pole piece of solid-state battery and solid-state battery |
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