CN118117033A - Active particulate matter for preparing pole piece, battery pole piece, preparation method and application - Google Patents

Active particulate matter for preparing pole piece, battery pole piece, preparation method and application Download PDF

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Publication number
CN118117033A
CN118117033A CN202410525194.0A CN202410525194A CN118117033A CN 118117033 A CN118117033 A CN 118117033A CN 202410525194 A CN202410525194 A CN 202410525194A CN 118117033 A CN118117033 A CN 118117033A
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pole piece
active material
particulate matter
negative electrode
positive electrode
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CN202410525194.0A
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CN118117033B (en
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刘蓉
刘青青
朱高龙
王建
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Sichuan New Energy Vehicle Innovation Center Co Ltd
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Sichuan New Energy Vehicle Innovation Center Co Ltd
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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
    • 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
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • 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
    • H01M10/058—Construction or manufacture
    • 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
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • 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
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Battery Electrode And Active Subsutance (AREA)
  • Secondary Cells (AREA)

Abstract

The invention discloses active particles for preparing a pole piece, a battery pole piece, a preparation method and application thereof, and relates to the technical field of lithium batteries. The method is a more scientific continuous grading method for the design of the raw materials (including active materials, solid electrolyte and conductive agents) for forming the active layer of the pole piece, defines the non-uniformity coefficient C u and the curvature coefficient C s of active particles, controls the value range of the non-uniformity coefficient C u and the curvature coefficient C s, fully considers the influence of small particles in a system, is beneficial to obtaining the pole piece with low porosity, and further improves the electrochemical performance of the battery.

Description

Active particulate matter for preparing pole piece, battery pole piece, preparation method and application
Technical Field
The invention relates to the technical field of lithium batteries, in particular to active particles for preparing a pole piece, a battery pole piece, a preparation method and application.
Background
The traditional lithium ion battery has the safety problem, the liquid electrolyte is inflammable and easy to leak, the solid electrolyte is adopted to replace the liquid electrolyte, the safety of the battery can be greatly improved, and the construction of proper ion and electron paths in the pole piece is particularly important for preparing the high-performance solid battery. The electron path is constructed by adding conductive agent, and the ion path is constructed by solid electrolyte. If the porosity of the electrode sheet is too high, an effective ion and electron transmission path cannot be formed between the active material and the active material, between the active material and the solid electrolyte particles, and between the active material and the conductive agent, so that the battery performance is low. Meanwhile, the electrolyte is solid, so that the electrolyte is not needed to be soaked in the solid-state battery, and the porosity of the pole piece can be further reduced to improve the volume energy density. Therefore, the porosity of the low-pole piece is a key to the performance of the all-solid-state battery.
In the prior art, materials with specific particle size ranges are synthesized, and the compaction density is ensured by a grading method. However, the current grading method cannot effectively reduce the porosity of the pole piece, so that the electrochemical performance of the pole piece needs to be improved.
In view of this, the present invention has been made.
Disclosure of Invention
The invention aims to provide active particles for preparing a pole piece, a battery pole piece, a preparation method and application thereof, and aims to obtain a compact pole piece with low porosity and improve the electrochemical performance of the pole piece.
The invention is realized in the following way:
In a first aspect, the present invention provides an active particulate for preparing a pole piece, the active particulate comprising an active material, a solid electrolyte and a conductive agent, the active material being a positive electrode active material or a negative electrode active material;
Defining a non-uniformity coefficient C u and a curvature coefficient C s, a non-uniformity coefficient C u=d60/d10 and a curvature coefficient C s= d30 2/（d60×d10 of the active particulate matter);
wherein d 10、d30、d60 is the particle diameter of which the particle content smaller than a certain particle diameter on the particle diameter accumulation curve is 10%, 30% and 60% respectively;
The active particulate matter satisfies: c u≥5,Cs has a value of 1 to 3.
In an alternative embodiment, the active particulate matter satisfies at least one of the following characteristics a-F:
Feature A: the active particulate matter satisfies: the value of C u is 5.5-6.5, and the value of C s is 1.2-2.9;
Feature B: when the active material is a positive electrode active material, the mass ratio of the positive electrode active material, the solid electrolyte and the conductive agent is (60-75): (3-15): (15-30);
Feature C: when the active material is a negative electrode active material, the mass ratio of the negative electrode active material, the solid electrolyte and the conductive agent is (60-80): (15-35): (1-5);
Feature D: the solid electrolyte is sulfide; at least one sulfide selected from L2S-P2S5、L2S-SiS2、LiI-L2S-SiS2、LiI-L2S-P2S5、LiI-LiBr-L2S-P2S5、LiI-L2S-P2O5、LiI-Li3PO4-P2S5、L7-xPS6-xClx;
feature E: the average particle diameter d 50 of the solid electrolyte is 600 nm-1200 nm;
characteristic F: the conductive agent is selected from at least one of conductive graphite, VGCF, CNTs and Super P.
In a second aspect, the present invention provides a method for preparing active particulate matter of the foregoing embodiment, comprising: the active material, the solid electrolyte and the conductive agent are mixed in proportion, so that the non-uniformity coefficient C u and the curvature coefficient C s of the prepared active particles meet the requirements.
In a third aspect, the present invention provides a battery pole piece comprising the active particulate matter of any one of the preceding embodiments.
In a fourth aspect, the present invention provides a method for preparing a battery pole piece, including: the pole piece is prepared by utilizing the active particulate matters in any one of the previous embodiments or the active particulate matters prepared by the preparation method in the previous embodiments.
In an alternative embodiment, the active particulate matter is mixed with a binder and a solvent to obtain a pole piece slurry, which is coated on a current collector, and then dried and rolled.
In an alternative embodiment, at least one of the following conditions is met:
condition one: when the active material is an anode active material, the solid content of the pole piece slurry is 45% -60%;
Condition II: when the active material is a positive electrode active material, the mass ratio of the positive electrode active material to the binder is (60-75): (0.5-4);
And (3) a third condition: when the active material is a negative electrode active material, the solid content of the pole piece slurry is 30% -60%;
Condition four: when the active material is a negative electrode active material, the mass ratio of the negative electrode active material to the binder is (60-80): (1-5);
Condition five: the binder is at least one selected from PVDF, SBR, CMC, silicone rubber and fluororubber;
Condition six: the drying temperature is 50-100 ℃, and the total drying time is 12-24 hours; when the drying time reaches one half to two thirds of the total drying time, rolling the pole piece, and continuously drying the pole piece after the rolling is finished;
condition seven: the rolling pressure is 600-1000 MPa, and the rolling time is 10-30 min;
Condition eight: in the rolling process, an ultrasonic field is introduced, the ultrasonic frequency is controlled to be 20 KHz-27 KHz, and the ultrasonic time is controlled to be 3 s-8 s.
In a fifth aspect, the present invention provides a method for manufacturing a secondary battery, comprising: the preparation method of any one of the previous embodiments is used for preparing the positive electrode plate and the negative electrode plate respectively, and the secondary battery is assembled by using the positive electrode plate and the negative electrode plate.
In a sixth aspect, the present invention provides a secondary battery prepared by the preparation method of the foregoing embodiment.
In a seventh aspect, the present invention provides an electric device comprising the secondary battery of the foregoing embodiment.
The invention has the following beneficial effects: the method is a more scientific continuous grading method for the design of the raw materials (including active materials, solid electrolyte and conductive agents) for forming the active layer of the pole piece, defines the non-uniformity coefficient C u and the curvature coefficient C s of active particles, controls the value range of the non-uniformity coefficient C u and the curvature coefficient C s, fully considers the influence of small particles in a system, is beneficial to obtaining the pole piece with low porosity, and further improves the electrochemical performance of the battery.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below. The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.
The embodiment of the invention provides a preparation method of a battery pole piece, which comprises the following steps:
s1, providing active particles meeting grading requirements
The active material, which may be a positive electrode active material or a negative electrode active material, is mixed with active particles having a particle diameter satisfying the requirements by using the active material, the solid electrolyte, and the conductive agent. When the active material is an anode active material, the prepared active particles are used for preparing an anode plate; when the active material is a negative electrode active material, the prepared active particles are used for preparing a negative electrode plate.
The specific kinds of the positive electrode active material and the negative electrode active material are not limited, and may be commonly used positive electrode active material and negative electrode active material of lithium batteries.
In some embodiments, the positive electrode active material is at least one selected from lithium cobaltate, lithium manganate, lithium nickel cobalt manganate, high nickel, lithium-rich manganese, lithium iron phosphate active material, may be any one or more of the above, and specifically may be NCM 811, NCM 523, NCM622, liFePO 4, etc., preferably, the positive electrode active material is NCM 811, which is easily available in raw materials and has excellent electrochemical properties. When in stage, NCM 811 can be one or more of large single crystal, small single crystal, large polycrystal and small polycrystal, and the average grain diameter d 50 has no specific requirement.
In some embodiments, the negative electrode active material is at least one selected from graphite, silicon carbon, silicon oxygen and elemental silicon, and may be any one or more of the above, and the average particle diameter d 50 is not particularly required.
The solid electrolyte may be a common sulfide solid electrolyte, and the specific kind is not limited. In some embodiments, the sulfide is at least one selected from L2S-P2S5、L2S-SiS2、LiI-L2S-SiS2、LiI-L2S-P2S5、LiI-LiBr-L2S-P2S5、LiI-L2S-P2O5、LiI-Li3PO4-P2S5、L7-xPS6-xClx（0.6≤x≤1.9,, preferably x=1), and may be any one or several of the above sulfides. Specifically, L 2S-P2S5 may be Li 7P3S11、Li3PS4、Li8P2S9 or the like. The above solid electrolytes are all commercial materials, and specific manufacturers and models are not limited.
In some embodiments, the solid-state electrolyte has an average particle diameter d 50 of 600nm to 1200nm, such as 600nm, 800nm, 1000nm, 1200nm, etc., preferably 600nm to 1000nm. The solid electrolyte belongs to the raw material of small particles, the particle size of the solid electrolyte is controlled within the range, and the particle size is too large and too small, so that the solid electrolyte is not beneficial to obtaining a compact pole piece with low porosity.
The specific kind of the conductive agent is not limited, and may be a conductive agent commonly used for lithium batteries. In some embodiments, the conductive agent is at least one selected from conductive graphite, VGCF (conductive carbon fiber), CNTs (carbon nanotubes), and Super P (conductive carbon black), and may be any one or more of the above.
When the active material is a positive electrode active material, the mass ratio of the positive electrode active material, the solid electrolyte and the conductive agent is (60-75): (3-15): (15-30), preferably (65-70): (5-10): (20-25); when the active material is a negative electrode active material, the mass ratio of the negative electrode active material, the solid electrolyte and the conductive agent is (60-80): (15-35): (1-5), preferably (65-75): (20-30): (2-5). The recycling performance and the multiplying power performance of the battery are further improved by adjusting and controlling the consumption of the active material, the solid electrolyte and the conductive agent. Specifically, the mass ratio of the positive electrode active material, the solid electrolyte, and the conductive agent may be 60:3:15, 65:5:20, 68:8:23, 70:10:25, 75:15:30, or the like. The mass ratio of the anode active material, the solid electrolyte, and the conductive agent may be 60:15:1, 65:20:2, 70:25:3, 75:30:5, 80:35:5, or the like.
In order to obtain the pole piece with low porosity, the inventor optimizes the grading mode of active particles, provides a mode combining theoretical design and practice, considers the influence of the smallest particle size particles (generally electrolyte) in a system, namely adopts a continuous grading method to design reasonable particle grading, and thus obtains the compact pole piece with low porosity. Specifically, the inventors defined the non-uniformity coefficient C u and the curvature coefficient C s, the non-uniformity coefficient C u=d60/d10, the curvature coefficient C s= d30 2/（d60×d10 of the active particulate matter; wherein d 10、d30、d60 is the particle diameter of which the particle content smaller than a certain particle diameter on the particle diameter accumulation curve is 10%, 30% and 60% respectively;
The particle diameter cumulative curve was obtained as follows: particle size distribution of each material (active material, solid electrolyte and conductive agent) is obtained by adopting a particle size test, and then the particle size distribution of each material is graded to obtain a particle size accumulation curve meeting Cu and Cs, so that the specific value of d 10、d30、d60 can be calculated.
The non-uniformity coefficient C u can reflect the uniformity of particle size distribution, and C u represents steep curve, d 60 is close to d 10, the particle size distribution is narrow, the particles are uniform, and the grading is poor; c u is large, the representative curve is slow, d 60 is far away from d 10, the particle size distribution is wide, the particles are uneven, the compaction is easy, and the grading is good. If C u is too large, the intermediate grain size may be lost, and the grading curve is required to be evaluated by combining the curvature coefficient.
The curvature coefficient C s reflects the continuity of the slope of the particle diameter cumulative curve, describing the overall shape of the curve.
From the above analysis, it was found that the poor gradation was caused by unreasonable C u、Cs, and the gradation effect was not exhibited. To obtain a low porosity pole piece, the control of the active particulate matter satisfies: c u≥5,Cs has a value of 1-3, and the comprehensive control of C u、Cs ensures that the particle size distribution of active particles is uneven but the continuity is good, so that the porosity of the pole piece can be further reduced. When Cs is less than 1, the content of fine particles after grading is more than 30%, and the curve is discontinuous; when Cs is more than 3, the content of fine particles after grading is less than 30%, and the curve is discontinuous.
Specifically, the value of C u may be 5.0, 5.3, 5.5, 5.8, 6.0, 6.3, 6.5, 6.8, 7.0, etc., and the value of C s may be 1.0, 1.2, 1.5, 1.8, 2.0, 2.3, 2.5, 2.9, 3.0, etc.
In a preferred embodiment, the active particulate matter satisfies: the value of C u is 5.5-6.5, the value of C s is 1.2-2.9, and the porosity of the pole piece is further reduced by optimizing the value of C u、Cs.
In the preparation of the active particulate matters in the embodiment of the invention, the particle size parameters of the active materials, the solid electrolyte and the conductive agent are tested to obtain d 10、d30、d60 of three raw materials respectively, then the non-uniformity coefficient C u and the curvature coefficient C s of the mixed active particulate matters are calculated, and if the non-uniformity coefficient C u and the curvature coefficient C s meet the requirements, the raw materials are uniformly mixed.
S2, preparing pole piece slurry
And mixing the active particles with a binder and a solvent to obtain pole piece slurry for standby.
In some embodiments, the binder is selected from at least one of PVDF (polyvinylidene fluoride), SBR (styrene butadiene rubber), CMC (sodium carboxymethyl cellulose), silicone rubber and fluororubber, and may be any one or several of the above, preferably PVDF.
Further, the amount of the binder is determined according to the amount of the active material, and the mass ratio of the positive electrode active material to the binder is (60-75): (0.5-4), the mass ratio of the anode active material to the binder is (60-80): (1-5) the amount of the binder in the above range enables the active material layer to adhere to the current collector better. Specifically, the mass ratio of the positive electrode active material to the binder may be 60:0.5, 65:1.0, 70:2.0, 75:4.0, etc., and the mass ratio of the negative electrode active material to the binder may be 60:1, 65:2, 70:3, 75:4, 80:5, etc. In general, the sum of the mass of the active material, the solid electrolyte, the conductive agent, and the binder is 100%.
Further, the solid content of the pole piece slurry for preparing the positive pole piece is 45% -60%, such as 45%, 50%, 55%, 60% and the like, preferably 50% -60% by regulating the dosage of the solvent, and the uniformity of material distribution is improved in the range. The kind of the solvent is not particularly limited but may be compatible with the system.
S3, coating, drying and rolling
And (3) coating the pole piece slurry on a current collector, and then drying and rolling to obtain the positive pole piece or the negative pole piece.
When preparing the positive electrode plate, the current collector is a common positive electrode current collector, such as aluminum foil, but not limited thereto; in preparing the negative electrode sheet, the current collector is selected from commonly used negative electrode current collectors, such as stainless steel foil, but not limited thereto.
When the pole piece slurry is coated, the pole piece slurry can be uniformly mixed on a vibration ball mill, and then the pole piece slurry is coated on a current collector in a glove box by adopting an SQZ four-side preparation device.
In some embodiments, after the pole piece slurry is coated, the drying temperature is controlled to be 50-100 ℃ and the total drying time is 12-24 hours, so that the solvent is fully removed, and a uniform active coating is formed. Specifically, the drying temperature may be 50 ℃, 60 ℃, 70 ℃, 80 ℃,90 ℃, 100 ℃, etc., and the total drying time may be 12 hours, 15 hours, 18 hours, 20 hours, 22 hours, 24 hours, etc.
After reasonable particle grading is set, when preparing a wet pole piece, the inventor improves the drying system of the pole piece in order to ensure the grading effect and further improve the compaction density of the pole piece due to the problems of slurry 'self-sedimentation', solvent volatilization and the like affecting particle arrangement: and when the drying time reaches one half to two thirds of the total drying time, rolling the polar plate, and continuously drying the polar plate after the rolling is finished. The inventor improves the drying system of the pole piece, and bubbles in the pole piece are easier to discharge by rolling the pole piece when the pole piece is not dried completely, so that the compaction density of the pole piece is improved.
Specifically, the degree of incomplete drying of the pole piece was evaluated: when the total drying time of the pole piece at a certain temperature is set to be M, the pole piece is preferably rolled at M/2-2M/3, and the pole piece is continuously dried after the rolling is finished. For example: and the total drying time of the pole piece at a certain temperature is 24 hours, when the pole piece is dried for 12-16 hours, the pole piece can be taken out for rolling, and then the pole piece is continuously dried for 24 hours.
In some embodiments, the rolling pressure is controlled to be 600-1000 MPa (preferably 600-800 MPa), the rolling time is 10-30 min, and the compactness of the pole piece is improved by regulating the rolling conditions. Specifically, the rolling pressure may be 600MPa, 700MPa, 800MPa, 900MPa, 1000MPa, or the like; the rolling time may be 10min, 20min, 30min, etc.
In some embodiments, during the rolling process, an ultrasonic field is introduced, the ultrasonic frequency is controlled to be 20 KHz-27 KHz, the ultrasonic time is controlled to be 3 s-8 s, the ultrasonic frequency is preferably within the range, if the frequency is too high, excessive heat can be generated, small particles can be filled in the interior through the ultrasonic action of a short time, and large particles are left on the surface.
When the pole pieces are rolled, on the premise that particles are rearranged due to no influence on grading, an extremely weak ultrasonic field is added, and small particles can be further filled in gaps better through weak vibration generated by the extremely weak ultrasonic field, so that the compaction density of the pole pieces is improved. In addition, the filling of the small particles inside and the structure of the large particles left on the surface are beneficial to the exertion of the rate performance of the battery.
The embodiment of the invention also provides a battery pole piece, which comprises the active particles, wherein the active particles are uniformly distributed on the current collector to form an anode active layer or a cathode active layer. The battery pole piece has the characteristics of low porosity and high compaction density.
The embodiment of the invention also provides a preparation method of the secondary battery, which comprises the following steps: the preparation method of the battery pole piece provided by the embodiment of the invention is used for respectively preparing the positive pole piece and the negative pole piece, and the positive pole piece and the negative pole piece are used for assembling the secondary battery, so that the positive pole piece and the negative pole piece have the characteristics of low porosity and high compaction density, and the rate performance and the cycle performance of the secondary battery are improved.
The embodiment of the invention also provides a secondary battery which is prepared by the preparation method of the secondary battery and has good multiplying power performance and cycle performance.
The embodiment of the invention also provides an electricity utilization device which comprises the secondary battery and can also comprise an electricity utilization device, wherein the secondary battery is used for supplying power to the electricity utilization device. The power utilization device can be an electric vehicle, a mobile phone, a camera and the like.
The features and capabilities of the present invention are described in further detail below in connection with the examples.
Example 1
The present embodiment provides a method for preparing a battery pole piece, in which the non-uniformity coefficient C u of the particle diameter cumulative distribution curve after the active particulate matter (positive electrode active material NCM811, solid electrolyte LPSC651 (Li 6PS5 Cl), conductive graphite) is graded is 5.69, the curvature coefficient C s is 1.23, the pole piece is subjected to a rolling process when completely dried, and an ultrasonic field is not added when the pole piece is rolled. The method comprises the following specific steps:
(1) Preparation of positive electrode plate
The positive electrode active material NCM811, solid electrolyte Li 6PS5 Cl, conductive graphite and binder PVDF (positive electrode active material: solid electrolyte: conductive agent: binder=68:8:22:2) were weighed, the solid content was adjusted to 52% by butyl butyrate, the mixture was homogenized at 1000rpm for 30min by using a pendulum ball mill, then the slurry was drawn on aluminum foil by using a 700 μm SQZ four-side preparer, finally the pole piece was dried at 50℃for 24h, and then rolled under 700MPa for a rolling time of 10 min.
Wherein, particle size distribution of the positive electrode active material: d 10=1.875μm、d30=2.75μm、d60 =4.034 μm;
Particle size distribution of solid electrolyte: d 10=0.8335μm、d30=0.9123μm、d60 =1.005 μm, and the average particle diameter d 50 of the solid electrolyte is 950nm;
particle size distribution of the conductive agent: d 10=11.38μm、d30=12.1μm、d60 =13.32 μm.
(2) Preparation of negative electrode sheet (Cu, cs of negative electrode is similar to positive electrode)
The negative electrode active material Si/C-450 (available from Bei Terui company under the model DXB 5), solid electrolyte Li 6PS5 Cl, conductive agent VGCF and binder PVDF (negative electrode active material: solid electrolyte: conductive agent: binder=70:25:2:3) were weighed, the solid content was adjusted to 43% by butyl butyrate, slurry was mixed at a rotation speed of 1000rpm for 30min by using a pendulum ball mill, then slurry doctor blade coating was performed on a stainless steel foil by using a 300 μm SQZ four-side preparer, finally the pole piece was dried at 50℃for 24 hours, and then 800 MPa rolling was performed for a rolling time of 10 min. The average particle diameter d 50 of the solid electrolyte used above was 800 nm.
Example 2
The only difference from example 1 is that: the non-uniformity coefficient C u of the particle diameter accumulation distribution curve after the active particulate matter grading of the positive electrode plate is 5.6921, and the curvature coefficient C s is 1.0376. Other parameters are consistent with the embodiment, namely the pole piece is subjected to a rolling procedure when being completely dried, and an ultrasonic field is not added when the pole piece is rolled.
Example 3
The only difference from example 1 is that: the non-uniformity coefficient C u of the particle diameter accumulation distribution curve after the active particulate matter grading of the positive electrode plate is 6.6438, and the curvature coefficient C s is 1.5162. Other parameters are consistent with the embodiment, namely the pole piece is subjected to a rolling procedure when being completely dried, and an ultrasonic field is not added when the pole piece is rolled.
Example 4
The only difference from example 1 is that: (1) The non-uniformity coefficient C u of the particle diameter accumulation distribution curve after the active particulate matter of the positive pole piece is graded is 6.0438, and the curvature coefficient C s is 1.5162; (2) The positive electrode (positive electrode and negative electrode are changed) pole piece is taken out for rolling after being dried for 12 hours, and is dried for 12 hours after rolling when the pole piece is rolled (an ultrasonic field is not added).
Example 5
The only difference from example 1 is that: (1) The non-uniformity coefficient C u of the particle diameter accumulation distribution curve after the active particulate matter of the positive pole piece is graded is 6.0438, and the curvature coefficient Cs is 1.5162; (2) And taking out the positive pole piece after drying for 12h for rolling, adding an ultrasonic field when the pole piece is rolled, wherein the ultrasonic frequency is 21KHz, the ultrasonic wave application time is 5s, and continuing to dry for 12h after rolling.
Comparative example 1
The only difference from example 1 is that: the non-uniformity coefficient C u of the particle diameter accumulation distribution curve after the active particulate matter grading of the positive electrode plate is 2.7770, and the curvature coefficient C s is 0.7745. Other parameters are consistent with the embodiment, namely the pole piece is subjected to a rolling procedure when being completely dried, and an ultrasonic field is not added when the pole piece is rolled.
Comparative example 2
The only difference from example 1 is that: the non-uniformity coefficient C u of the particle diameter accumulation distribution curve after the active particulate matter grading of the positive electrode plate is 8.0438, and the curvature coefficient C s is 0.6815. Other parameters are consistent with the embodiment, namely the pole piece is subjected to a rolling procedure when being completely dried, and an ultrasonic field is not added when the pole piece is rolled.
Comparative example 3
The only difference from example 1 is that: (1) The non-uniformity coefficient C u of the particle diameter accumulation distribution curve after the active particulate matter of the positive pole piece is graded is 2.7770, and the curvature coefficient C s is 0.7745; (2) And taking out the positive pole piece after drying for 12 hours, rolling, and continuing drying for 12 hours after rolling without adding an ultrasonic field).
Comparative example 4
The only difference from example 1 is that: (1) The non-uniformity coefficient C u of the particle diameter accumulation distribution curve after the active particulate matter of the positive pole piece is graded is 2.7770, and the curvature coefficient Cs is 0.7745; (2) And taking out the positive pole piece after drying for 12h for rolling, adding an ultrasonic field when the pole piece is rolled, wherein the ultrasonic frequency is 21KHz, the ultrasonic wave application time is 5s, and continuing to dry for 12h after rolling.
Test example 1
Test examples and comparative examples the porosity of the resulting pole pieces was measured and the electrochemical properties were measured and the results are shown in table 1.
The testing method comprises the following steps: (1) porosity test: and testing the porosity of the all-solid-state battery pole piece by adopting a full-automatic mercury porosimeter. (2) electrochemical performance test: and (3) performing rate cycle performance test on the assembled die battery, wherein a voltage window is 3.0-4.25V. The assembly flow of the die battery is as follows: cutting the prepared positive electrode or negative electrode into small discs with the diameter of 10mm, weighing 85mg of Li 6PS5 Cl In a glove box, pouring the small discs into a die, pressing for 1 time by adopting the pressure of 300MPa to form an electrolyte layer, then adding a positive plate or a negative plate at one end of the electrolyte layer, pressing for 1 time under the same condition, sequentially adding an In plate with the diameter of 10mm and a lithium plate with the diameter of 8mm at the other end of the electrolyte layer, sealing the die, and screwing a die frame by adopting a torque wrench with the diameter of 3.5N.
TABLE 1 porosity and electrochemical Properties of the cathode and anode
Examples 1-3 achieved lower porosity by reasonable grading, and example 5 achieved the lowest porosity by combining the process of adjusting the roll-in on this basis.
C u、Cs of comparative example 1 does not satisfy the preferred range, so the porosity of the electrode sheet is highest and the charge and discharge performance of the battery is worst; c u of comparative example 2 satisfies the preferable range, the particle size distribution is wide, but C s does not satisfy the preferable range, i.e., the overall shape of the gradation curve is discontinuous, resulting in higher porosity; in comparative examples 3 and 4, the pole piece density was improved by the addition of weak ultrasonic during rolling when the pole piece was not completely dried, but the porosity was still at a higher level due to the failure to achieve continuous grading. Therefore, the key to preparing a low porosity pole piece is reasonable grading.
The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. The active particulate matter for preparing the pole piece is characterized by comprising an active material, a solid electrolyte and a conductive agent, wherein the active material is a positive electrode active material or a negative electrode active material;
Defining a non-uniformity coefficient C u and a curvature coefficient C s, a non-uniformity coefficient C u=d60/d10, a curvature coefficient C s=d30 2/（d60×d10 of the active particulate matter;
wherein d 10、d30、d60 is the particle diameter of which the particle content smaller than a certain particle diameter on the particle diameter accumulation curve is 10%, 30% and 60% respectively;
The active particulate matter satisfies: c u≥5,Cs has a value of 1 to 3.
2. The active particulate matter of claim 1, wherein the active particulate matter meets at least one of the following characteristics a-F:
Feature A: the active particulate matter satisfies: the value of C u is 5.5-6.5, and the value of C s is 1.2-2.9;
feature B: when the active material is a positive electrode active material, the mass ratio of the positive electrode active material, the solid electrolyte and the conductive agent is (60-75): (3-15): (15-30);
feature C: when the active material is a negative electrode active material, the mass ratio of the negative electrode active material, the solid electrolyte and the conductive agent is (60-80): (15-35): (1-5);
Feature D: the solid electrolyte is sulfide; at least one sulfide selected from L2S-P2S5、L2S-SiS2、LiI-L2S-SiS2、LiI-L2S-P2S5、LiI-LiBr-L2S-P2S5、LiI-L2S-P2O5、LiI-Li3PO4-P2S5、L7-xPS6-xClx;
Feature E: the average particle diameter d 50 of the solid electrolyte is 600 nm-1200 nm;
Characteristic F: the conductive agent is at least one selected from conductive graphite, VGCF, CNTs and Super P.
3. A method of preparing the active particulate matter of claim 1 or 2, comprising: and mixing the active material, the solid electrolyte and the conductive agent in proportion to ensure that the non-uniformity coefficient C u and the curvature coefficient C s of the prepared active particles meet the requirements.
4. A battery pole piece comprising the active particulate matter of any one of claims 1-2.
5. The preparation method of the battery pole piece is characterized by comprising the following steps: a pole piece prepared from the active particulate matter according to any one of claims 1 to 2 or the active particulate matter prepared by the preparation method according to claim 3.
6. The method according to claim 5, wherein the active particulate matter is mixed with a binder and a solvent to obtain a pole piece slurry, and the pole piece slurry is coated on a current collector, and then dried and rolled.
7. The method of manufacturing according to claim 6, wherein at least one of the following conditions is satisfied:
condition one: when the active material is an anode active material, the solid content of the pole piece slurry is 45% -60%;
condition II: when the active material is a positive electrode active material, the mass ratio of the positive electrode active material to the binder is (60-75): (0.5-4);
And (3) a third condition: when the active material is a negative electrode active material, the solid content of the pole piece slurry is 30% -60%;
condition four: when the active material is a negative electrode active material, the mass ratio of the negative electrode active material to the binder is (60-80): (1-5);
Condition five: the binder is at least one selected from PVDF, SBR, CMC, silicone rubber and fluororubber;
Condition six: the drying temperature is 50-100 ℃, and the total drying time is 12-24 hours; when the drying time reaches one half to two thirds of the total drying time, rolling the pole piece, and continuously drying the pole piece after the rolling is finished;
condition seven: the rolling pressure is 600-1000 MPa, and the rolling time is 10-30 min;
Condition eight: in the rolling process, an ultrasonic field is introduced, the ultrasonic frequency is controlled to be 20 KHz-27 KHz, and the ultrasonic time is controlled to be 3 s-8 s.
8. A method of manufacturing a secondary battery, comprising: preparing a positive electrode sheet and a negative electrode sheet by the preparation method of any one of claims 5 to 7, respectively, and assembling a secondary battery by using the positive electrode sheet and the negative electrode sheet.
9. A secondary battery, characterized by being produced by the production method according to claim 8.
10. An electric device comprising the secondary battery according to claim 9.
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109659493A (en) * 2018-12-26 2019-04-19 国联汽车动力电池研究院有限责任公司 It is a kind of comprising solid electrolyte, low porosity cathode and application the cathode lithium battery
CN109776007A (en) * 2019-01-20 2019-05-21 北京工业大学 A kind of hand-stuff fancy grade matches the method for determination
CN115036466A (en) * 2022-06-02 2022-09-09 深圳市德方纳米科技股份有限公司 Multi-phosphate positive electrode material, preparation method thereof and secondary battery
CN117276465A (en) * 2023-11-02 2023-12-22 东莞新能源科技有限公司 Battery pole piece, secondary battery and device
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

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109659493A (en) * 2018-12-26 2019-04-19 国联汽车动力电池研究院有限责任公司 It is a kind of comprising solid electrolyte, low porosity cathode and application the cathode lithium battery
CN109776007A (en) * 2019-01-20 2019-05-21 北京工业大学 A kind of hand-stuff fancy grade matches the method for determination
CN115036466A (en) * 2022-06-02 2022-09-09 深圳市德方纳米科技股份有限公司 Multi-phosphate positive electrode material, preparation method thereof and secondary battery
CN117276465A (en) * 2023-11-02 2023-12-22 东莞新能源科技有限公司 Battery pole piece, secondary battery and device
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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