CN115295769A - Lithium ion battery positive plate, preparation method thereof and lithium ion battery - Google Patents

Lithium ion battery positive plate, preparation method thereof and lithium ion battery Download PDF

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Publication number
CN115295769A
CN115295769A CN202211058877.7A CN202211058877A CN115295769A CN 115295769 A CN115295769 A CN 115295769A CN 202211058877 A CN202211058877 A CN 202211058877A CN 115295769 A CN115295769 A CN 115295769A
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lithium
ion battery
positive electrode
lithium ion
solid electrolyte
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Inventor
蒋易晟
杜帅锋
王占洲
张昊阳
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Hengdian Group DMEGC Magnetics Co Ltd
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Hengdian Group DMEGC Magnetics 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
    • 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
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
    • 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
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • 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

Abstract

The invention provides a lithium ion battery positive plate, a preparation method thereof and a lithium ion battery, wherein the preparation method comprises the following steps: mixing the positive electrode conductive agent with the solid electrolyte, and then stirring at a high speed to obtain a mixed conductive agent; mixing the positive active substance with the solid electrolyte, then carrying out first-stage low-speed stirring, then mixing with the mixed conductive agent, and then carrying out second-stage low-speed stirring to obtain an intermediate mixture; and mixing the intermediate mixture with a binder and a solvent to obtain anode slurry, and then sequentially coating, baking and cold-pressing to obtain the lithium ion battery anode plate. According to the method, the solid electrolyte is respectively added into the positive active substance and the positive conductive agent, so that the conductivity of the positive material is improved, and the increase of the internal impedance of the battery cell in the discharging process is inhibited, so that the excessive rise of the temperature is inhibited, the sufficient release of the battery capacity is ensured, and the service life of the lithium ion battery is prolonged; the method has the advantages of simple operation, low cost of raw materials and process and wide application range.

Description

Lithium ion battery positive plate, preparation method thereof and lithium ion battery
Technical Field
The invention belongs to the technical field of lithium ion batteries, and relates to a lithium ion battery positive plate, a preparation method thereof and a lithium ion battery.
Background
In recent years, with the continuous development of lithium ion battery technology, the lithium ion battery has been widely applied to a plurality of fields such as digital code, electronic information, traffic, energy storage and the like. The conventional lithium ion battery mainly comprises a battery shell, a positive plate, a negative plate, a diaphragm, electrolyte and other components, wherein the positive plate and the negative plate are important factors influencing the performance of the lithium ion battery, and the electrode plate is usually formed by uniformly coating positive slurry and negative slurry on corresponding current collectors, so that the composition of the positive slurry and the negative slurry and the quality of a coating process can directly influence the comprehensive performance of the lithium ion battery.
Based on the structure and composition characteristics of the lithium ion battery, the positive electrode material is an extremely important factor influencing the battery performance, the positive electrode material is unstable in the charging and discharging process and is often accompanied with the phenomena of side reaction between the material surface and electrolyte, degradation of the crystal structure of the material, fragmentation of the electrode structure or falling of an active coating, and the like, so the positive electrode material needs to be improved, and the common improvement measures at present comprise doping, surface coating and the like; the solid electrolyte is used as an important modified material of the lithium ion battery, and has good application prospect in the preparation of the current all-solid-state lithium ion battery based on the higher ionic conductivity of the solid electrolyte.
CN 109273760A discloses an electrode plate of a lithium ion battery with a solid electrolyte layer and a coating method, wherein the coating method comprises the following steps: sequentially coating and drying active substance slurry for the lithium ion battery to obtain a base lithium ion battery electrode plate, and then carrying out secondary coating and drying on solid electrolyte slurry, namely coating the solid electrolyte slurry on the base lithium ion battery electrode plate to obtain the lithium ion battery electrode plate with a solid electrolyte layer; in the method, a solid electrolyte layer is formed separately to block the growth of SEI film and lithium dendrite, and the method does not aim at the improvement of active materials and has different effects brought by different improvement modes.
CN 111900394A discloses a coating structure of a lithium ion battery anode material, a preparation method and application thereof, wherein the preparation method comprises the following steps: coating an electronic conductive particle layer on the surface of the positive electrode material by a mechanical fusion method; and then coating the solid electrolyte layer on the surface of the electronic conductive particle layer by a liquid phase method to obtain the coating structure of the lithium ion battery anode material. The method adopts coating to modify the anode material, also forms a solid electrolyte layer, but does not use the solid electrolyte as a component of electrode slurry, and belongs to different improvement directions.
In summary, for the preparation of the positive plate of the lithium ion battery, according to the composition of the positive slurry and the characteristics of the solid electrolyte, a suitable improvement mode is selected to improve the conductivity of the positive material, inhibit the temperature rise of the lithium ion battery during discharging, and ensure the sufficient release of the battery capacity.
Disclosure of Invention
In order to solve the problems in the prior art, the invention aims to provide a lithium ion battery positive plate, a preparation method thereof and a lithium ion battery.
In order to achieve the purpose, the invention adopts the following technical scheme:
in one aspect, the invention provides a preparation method of a lithium ion battery positive plate, which comprises the following steps:
(1) Mixing the positive electrode conductive agent with the solid electrolyte, and then stirring at a high speed to obtain a mixed conductive agent;
(2) Mixing the positive active substance with the solid electrolyte, then carrying out first-stage low-speed stirring, then mixing with the mixed conductive agent obtained in the step (1), and then carrying out second-stage low-speed stirring to obtain an intermediate mixture;
(3) And (3) mixing the intermediate mixture obtained in the step (2) with a binder and a solvent to obtain anode slurry, and then sequentially coating, baking and cold-pressing the anode slurry to obtain the lithium ion battery anode piece.
According to the invention, for the preparation of the lithium ion battery positive plate, improvement is carried out by adding the solid electrolyte, the positive active substance and the positive conductive agent are respectively stirred and mixed, and then the positive slurry is prepared, wherein the addition of the solid electrolyte can effectively improve the conductivity of the positive material, so that the impedance in the battery cell is reduced, the internal temperature of the battery is not excessively increased in the discharging process, the discharging capacity and the service time of the battery are ensured, and the service life of the lithium ion battery is prolonged; the method has the advantages of simple operation, low cost of raw materials and process and wide application range.
The following technical solutions are preferred technical solutions of the present invention, but not limited to the technical solutions provided by the present invention, and technical objects and advantageous effects of the present invention can be better achieved and achieved by the following technical solutions.
As a preferred technical solution of the present invention, the positive electrode conductive agent in step (1) includes any one or a combination of at least two of conductive carbon black, carbon nanotubes or conductive graphite, and the combination is typically but not limited to: combinations of conductive carbon black and carbon nanotubes, combinations of carbon nanotubes and conductive graphite, combinations of conductive carbon black, carbon nanotubes and conductive graphite, and the like.
Preferably, the solid electrolyte in step (1) comprises any one of lithium lanthanum zirconium oxide, lithium lanthanum titanium oxide, lithium lanthanum zirconium tantalum oxide, lithium titanium aluminum phosphate or lithium germanium aluminum phosphate, or a combination of at least two thereof, as typical but non-limiting examples: a combination of lithium lanthanum zirconium oxide and lithium lanthanum titanium oxide, a combination of lithium lanthanum zirconium oxide and lithium lanthanum zirconium tantalum oxide, a combination of lithium lanthanum titanium oxide and titanium aluminum lithium phosphate, a combination of lithium lanthanum titanium oxide, lithium lanthanum zirconium tantalum oxide and germanium aluminum lithium phosphate, a combination of lanthanum zirconium oxide, lithium lanthanum titanium oxide and lithium lanthanum zirconium tantalum oxide, and the like.
Preferably, the solid electrolyte of step (1) has a particle size of 100 to 3000nm, such as 100nm, 500nm, 1000nm, 1500nm, 2000nm, 2500nm, 3000nm, and the like, but is not limited to the recited values, and other values not recited within the range of values are also applicable.
Preferably, the positive electrode conductive agent in the step (1) is added in an amount of 0.5 to 1.5wt%, for example, 0.5wt%, 0.8wt%, 1wt%, 1.2wt%, 1.5wt%, or the like, based on the positive electrode active material in the step (2), but is not limited to the recited values, and other values not recited in this range are also applicable.
Preferably, the solid electrolyte of step (1) is added in an amount of 0.05 to 0.3wt%, such as 0.05wt%, 0.1wt%, 0.15wt%, 0.2wt%, 0.25wt%, or 0.3wt%, etc., of the positive electrode active material of step (2), but not limited to the recited values, and other values not recited in this range of values are also applicable.
As a preferred embodiment of the present invention, the rotation speed of the high-speed stirring in the step (1) is 2000 to 4000r/min, for example, 2000r/min, 2500r/min, 3000r/min, 3500r/min or 4000r/min, but the rotation speed is not limited to the above-mentioned values, and other values not shown in the above-mentioned range are also applicable.
Preferably, the high speed stirring time in step (1) is 60-90 min, such as 60min, 65min, 70min, 75min, 80min, 85min or 90min, but not limited to the recited values, and other values not recited in the range of the values are also applicable.
Preferably, the mixed conductive agent obtained after the high-speed stirring in the step (1) is finished is vacuumized for standby.
In the invention, the reason why the positive electrode conductive agent and the solid electrolyte are required to be stored in vacuum after being mixed is that if water is absorbed in the preparation process of the positive electrode material, slurry is easy to form jelly, the processing performance and the battery performance are influenced, and therefore, the positive electrode material is required to be stored in vacuum during step-by-step operation.
As a preferred embodiment of the present invention, the positive electrode active material in step (2) includes any one or a combination of at least two of lithium nickel cobalt manganese oxide (NCM), lithium Nickel Cobalt Aluminate (NCA), lithium iron phosphate (LFP), and Lithium Manganese Oxide (LMO), and the combination is typically, but not limited to, the following: a combination of lithium nickel cobalt manganese oxide and lithium nickel cobalt aluminate, a combination of lithium nickel cobalt aluminate and lithium iron phosphate, a combination of lithium iron phosphate and lithium manganese oxide, a combination of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminate and lithium iron phosphate, and the like.
Preferably, the solid electrolyte in step (2) comprises any one of lithium lanthanum zirconium oxide, lithium lanthanum titanium oxide, lithium lanthanum zirconium tantalum oxide, lithium titanium aluminum phosphate or lithium germanium aluminum phosphate, or a combination of at least two thereof, as typical but non-limiting examples: a combination of lithium lanthanum zirconium oxide and lithium lanthanum titanium oxide, a combination of lithium lanthanum zirconium oxide and lithium lanthanum zirconium tantalum oxide, a combination of lithium lanthanum titanium oxide and titanium aluminum lithium phosphate, a combination of lithium lanthanum titanium oxide, lithium lanthanum zirconium tantalum oxide and germanium aluminum lithium phosphate, a combination of lanthanum zirconium oxide, lithium lanthanum titanium oxide and lithium lanthanum zirconium tantalum oxide, and the like.
Preferably, the solid electrolyte of step (2) has a particle size of 100 to 3000nm, such as 100nm, 500nm, 1000nm, 1500nm, 2000nm, 2500nm, 3000nm, and the like, but is not limited to the recited values, and other values not recited within the range of values are also applicable.
Preferably, the solid electrolyte of step (2) is added in an amount of 0.1 to 0.3wt%, such as 0.1wt%, 0.15wt%, 0.2wt%, 0.25wt%, or 0.3wt%, etc., of the positive electrode active material of step (2), but not limited to the recited values, and other non-recited values within this range are also applicable.
In the present invention, the amount of the solid electrolyte added is an important factor affecting the performance of the electrode sheet, and if the amount of the solid electrolyte added is too small, the conductivity cannot be sufficiently improved, and thus the temperature cannot be prevented from being excessively increased, and if the amount of the solid electrolyte added is too large, the adhesion during coating is too low, and problems such as swelling and foil breakage are easily caused.
As a preferred embodiment of the present invention, the rotation speed of the one-stage low-speed stirring in the step (2) is 100 to 500r/min, for example, 100r/min, 200r/min, 300r/min, 400r/min or 500r/min, but is not limited to the above-mentioned values, and other values not shown in the above-mentioned value range are also applicable.
Preferably, the low speed stirring time in step (2) is 30-60 min, such as 30min, 35min, 40min, 45min, 50min, 55min or 60min, but not limited to the recited values, and other values not recited in the range of the recited values are also applicable.
Preferably, the rotation speed of the two-stage low-speed stirring in the step (2) is 500-1500 r/min, such as 500r/min, 800r/min, 1000r/min, 1200r/min, 1350r/min or 1500r/min, but not limited to the recited values, and other values not recited in the numerical range are also applicable.
Preferably, the time of the two-stage low speed stirring in step (2) is 60-90 min, such as 60min, 65min, 70min, 75min, 80min, 85min or 90min, but not limited to the recited values, and other values not recited in the range of the values are also applicable.
In the invention, when the anode conductive agent and the anode active substance are respectively mixed with the solid electrolyte, the adopted stirring rates are different, the former adopts high-speed stirring mainly because the self characteristic of the anode conductive agent needs to stir the carbon nano tube into filaments at high speed to play the effect, and the latter adopts low-speed stirring because the powdered raw material needs to be stirred at low speed to avoid dust splashing, and the stirring rate can be improved during integral mixing because the powdered particles are not easy to splash after the solvent is added.
In a preferred embodiment of the present invention, the binder in step (3) comprises polyvinylidene fluoride (PVDF).
Preferably, the solvent of step (3) comprises N-methylpyrrolidone.
Preferably, the binder of step (3) is added in an amount of 0.5 to 1.5wt%, such as 0.5wt%, 0.8wt%, 1wt%, 1.2wt%, or 1.5wt%, etc., based on the positive electrode active material of step (2), but not limited to the recited values, and other values not recited in the range of values are also applicable.
Preferably, the solvent of step (3) is added in an amount of 10 to 15wt%, for example, 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, or 15wt%, etc., based on the positive electrode active material of step (2), but not limited to the recited values, and other values not recited in the range of the values are also applicable.
Preferably, the positive electrode slurry in the step (3) has a viscosity of 4000 to 7000 mPas, for example, 4000 mPas, 4500 mPas, 5000 mPas, 5500 mPas, 6000 mPas, 6500 mPas or 7000 mPas, but is not limited to the recited values, and other values not recited in the above range are also applicable.
As a preferable embodiment of the present invention, the positive electrode slurry in the step (3) is coated on a current collector.
Preferably, the current collector comprises an aluminum foil.
Preferably, the baking temperature in step (3) is 100 to 120 ℃, such as 100 ℃, 105 ℃, 110 ℃, 115 ℃ or 120 ℃, but not limited to the recited values, and other values not recited in the range of values are also applicable.
Preferably, the pressure of the cold pressing in step (3) is 25 to 45T, such as 25T, 30T, 35T, 40T or 45T, but not limited to the recited values, and other values not recited in the range of values are also applicable.
On the other hand, the invention provides the lithium ion battery positive plate obtained by the preparation method.
In addition, the invention also provides a lithium ion battery, and the lithium ion battery comprises the lithium ion battery positive plate.
Preferably, the lithium ion battery is formed by assembling a positive plate, a negative plate, a diaphragm and a shell, and then adding the electrolyte and sealing.
As a preferable technical scheme of the invention, the negative plate is obtained by sequentially coating, baking and cold pressing the negative slurry.
Preferably, the composition of the anode slurry includes an anode active material, an anode conductive agent, and a binder.
Preferably, the negative active material includes silicon carbon and/or graphite.
Compared with the prior art, the invention has the following beneficial effects:
(1) According to the method, the solid electrolyte is added into the positive active substance and the positive conductive agent respectively, so that the conductivity of the positive material is improved, the increase of the internal impedance of the battery cell in the discharging process is inhibited, the excessive rise of the temperature is inhibited, the temperature of the battery after discharging does not exceed 80 ℃, the sufficient release of the battery capacity is ensured, and the service life of the lithium ion battery is prolonged;
(2) The method has the advantages of simple operation, low cost of raw materials and process and wide application range.
Detailed Description
In order to better explain the present invention and to facilitate the understanding of the technical solutions of the present invention, the present invention is further described in detail below. However, the following examples are only simple examples of the present invention and do not represent or limit the scope of the present invention, which is defined by the claims.
The invention provides a lithium ion battery positive plate and a preparation method thereof, wherein the preparation method comprises the following steps:
(1) Mixing the positive electrode conductive agent with the solid electrolyte, and then stirring at a high speed to obtain a mixed conductive agent;
(2) Mixing the positive active substance with the solid electrolyte, then carrying out first-stage low-speed stirring, then mixing with the mixed conductive agent obtained in the step (1), and then carrying out second-stage low-speed stirring to obtain an intermediate mixture;
(3) And (3) mixing the intermediate mixture obtained in the step (2) with a binder and a solvent to obtain anode slurry, and then sequentially coating, baking and cold-pressing the anode slurry to obtain the lithium ion battery anode piece.
The following are typical but non-limiting examples of the invention:
example 1:
the embodiment provides a lithium ion battery positive plate and a preparation method thereof, wherein the preparation method comprises the following steps:
(1) Mixing a positive electrode conductive agent and a solid electrolyte, then stirring at a high speed, wherein the positive electrode conductive agent is conductive carbon black, the solid electrolyte is lithium lanthanum zirconium oxide, the average particle size of the solid electrolyte is 500nm, the adding amount of the positive electrode conductive agent accounts for 1.0wt% of the positive electrode active substance, the adding amount of the solid electrolyte accounts for 0.15wt% of the positive electrode active substance, the rotating speed of high-speed stirring is 3000r/min, the time is 75min, obtaining a mixed conductive agent, and vacuumizing for later use;
(2) Mixing an anode active substance and a solid electrolyte, and then carrying out first-stage low-speed stirring, wherein the anode active substance is nickel cobalt lithium manganate, the solid electrolyte is lithium lanthanum zirconium oxide, the average particle size of the lithium lanthanum zirconium oxide is 500nm, the addition amount of the solid electrolyte accounts for 0.15wt% of the anode active substance, the first-stage low-speed stirring rotation speed is 500r/min and the time is 45min, then mixing the mixture with the mixed conductive agent obtained in the step (1), and then carrying out second-stage low-speed stirring, the second-stage low-speed stirring rotation speed is 1000r/min and the time is 75min, so as to obtain an intermediate mixture;
(3) And (3) mixing the intermediate mixture obtained in the step (2) with a binder and a solvent, wherein the binder is polyvinylidene fluoride, the addition amount of the binder accounts for 1.0wt% of the positive electrode active substance, the solvent is N-methylpyrrolidone, the addition amount of the solvent accounts for 12wt% of the positive electrode active substance, positive electrode slurry is obtained, the viscosity of the positive electrode slurry is 5000mPa & s, then the positive electrode slurry is coated on an aluminum foil, and then baking and cold pressing are carried out, the baking temperature is 110 ℃, and the pressure of the cold pressing is 30T, so that the positive electrode sheet of the lithium ion battery is obtained.
Example 2:
the embodiment provides a lithium ion battery positive plate and a preparation method thereof, wherein the preparation method comprises the following steps:
(1) Mixing a positive electrode conductive agent and a solid electrolyte, and then stirring at a high speed, wherein the positive electrode conductive agent is a carbon nano tube, the solid electrolyte is lithium lanthanum titanium oxide, the average particle size of the solid electrolyte is 1000nm, the adding amount of the positive electrode conductive agent accounts for 0.5wt% of the positive electrode active substance, the adding amount of the solid electrolyte accounts for 0.1wt% of the positive electrode active substance, the rotating speed of high-speed stirring is 2000r/min, the time is 90min, so as to obtain a mixed conductive agent, and vacuumizing for later use;
(2) Mixing a positive active substance and a solid electrolyte, and then carrying out first-stage low-speed stirring, wherein the positive active substance is lithium nickel cobalt aluminate, the solid electrolyte is lithium lanthanum titanium oxide, the average particle size of the lithium lanthanum titanium oxide is 1000nm, the addition amount of the solid electrolyte accounts for 0.1wt% of the positive active substance, the rotation speed of the first-stage low-speed stirring is 200r/min, the time is 60min, then mixing the mixture with the mixed conductive agent obtained in the step (1), and then carrying out second-stage low-speed stirring, the rotation speed of the second-stage low-speed stirring is 600r/min, the time is 90min, so as to obtain an intermediate mixture;
(3) And (3) mixing the intermediate mixture obtained in the step (2) with a binder and a solvent, wherein the binder is polyvinylidene fluoride, the addition amount of the polyvinylidene fluoride accounts for 0.5wt% of the positive active material, the solvent is N-methyl pyrrolidone, the addition amount of the N-methyl pyrrolidone accounts for 15wt% of the positive active material, so as to obtain positive slurry, the viscosity of the positive slurry is 6000mPa & s, then coating the positive slurry on an aluminum foil, and then baking and cold pressing are carried out, the baking temperature is 100 ℃, and the pressure of the cold pressing is 45T, so as to obtain the positive plate of the lithium ion battery.
Example 3:
the embodiment provides a lithium ion battery positive plate and a preparation method thereof, wherein the preparation method comprises the following steps:
(1) Mixing a positive electrode conductive agent and a solid electrolyte, and then stirring at a high speed, wherein the positive electrode conductive agent is conductive graphite, the solid electrolyte is titanium aluminum lithium phosphate, the average particle size of the solid electrolyte is 2000nm, the adding amount of the positive electrode conductive agent accounts for 1.5wt% of a positive electrode active substance, the adding amount of the solid electrolyte accounts for 0.3wt% of the positive electrode active substance, the rotating speed of high-speed stirring is 4000r/min, the time is 60min, so as to obtain a mixed conductive agent, and vacuumizing for later use;
(2) Mixing an anode active substance and a solid electrolyte, and then carrying out first-stage low-speed stirring, wherein the anode active substance is lithium iron phosphate, the solid electrolyte is lithium aluminum titanium phosphate with the average particle size of 2000nm, the addition of the solid electrolyte accounts for 0.3wt% of the anode active substance, the first-stage low-speed stirring is carried out at the rotating speed of 400r/min for 30min, and then mixing with the mixed conductive agent obtained in the step (1) and carrying out second-stage low-speed stirring, the rotating speed of the second-stage low-speed stirring is 1500r/min for 60min, so as to obtain an intermediate mixture;
(3) And (3) mixing the intermediate mixture obtained in the step (2) with a binder and a solvent, wherein the binder is polyvinylidene fluoride, the addition amount of the binder accounts for 1.5wt% of the positive electrode active substance, the solvent is N-methylpyrrolidone, the addition amount of the solvent accounts for 10wt% of the positive electrode active substance, positive electrode slurry is obtained, the viscosity of the positive electrode slurry is 4000mPa & s, then the positive electrode slurry is coated on an aluminum foil, and then baking and cold pressing are carried out, the baking temperature is 120 ℃, and the pressure of the cold pressing is 25T, so that the positive electrode sheet of the lithium ion battery is obtained.
Example 4:
the embodiment provides a lithium ion battery positive plate and a preparation method thereof, wherein the preparation method comprises the following steps:
(1) Mixing a positive electrode conductive agent and a solid electrolyte, and then stirring at a high speed, wherein the positive electrode conductive agent comprises conductive carbon black and carbon nano tubes in a mass ratio of 1;
(2) Mixing an anode active substance and a solid electrolyte, and then carrying out first-stage low-speed stirring, wherein the anode active substance is lithium manganate, the solid electrolyte is lithium lanthanum zirconium tantalum oxide, the average particle size of the lithium lanthanum zirconium tantalum oxide is 200nm, the addition amount of the solid electrolyte accounts for 0.25wt% of the anode active substance, the first-stage low-speed stirring is carried out at the rotating speed of 200r/min for 50min, and then mixing with the mixed conductive agent obtained in the step (1) and then carrying out second-stage low-speed stirring, the second-stage low-speed stirring is carried out at the rotating speed of 1200r/min for 80min, so as to obtain an intermediate mixture;
(3) And (3) mixing the intermediate mixture obtained in the step (2) with a binder and a solvent, wherein the binder is polyvinylidene fluoride, the addition amount of the binder is 1.2wt% of the positive active material, the solvent is N-methyl pyrrolidone, the addition amount of the solvent is 11wt% of the positive active material, positive slurry is obtained, the viscosity of the positive slurry is 7000mPa & s, then the positive slurry is coated on an aluminum foil, baking and cold pressing are carried out, the baking temperature is 105 ℃, and the cold pressing pressure is 35T, so that the positive plate of the lithium ion battery is obtained.
Example 5:
the embodiment provides a lithium ion battery positive plate and a preparation method thereof, wherein the preparation method comprises the following steps:
(1) Mixing a positive electrode conductive agent and a solid electrolyte, then stirring at a high speed, wherein the positive electrode conductive agent is conductive graphite, the solid electrolyte is germanium aluminum lithium phosphate, the average particle size of the solid electrolyte is 1500nm, the adding amount of the positive electrode conductive agent accounts for 1.2wt% of a positive electrode active substance, the adding amount of the solid electrolyte accounts for 0.05wt% of the positive electrode active substance, the rotating speed of high-speed stirring is 3500r/min, the time is 80min, obtaining a mixed conductive agent, and vacuumizing for later use;
(2) Mixing a positive electrode active substance and a solid electrolyte, and then stirring at a low speed for the first time, wherein the positive electrode active substance is lithium nickel cobalt manganese oxide, the solid electrolyte is lithium lanthanum zirconium oxide with the average particle size of 2500nm, the adding amount of the solid electrolyte accounts for 0.15wt% of the positive electrode active substance, the rotating speed of the first-time low-speed stirring is 250r/min and the time is 40min, then mixing with the mixed conductive agent obtained in the step (1), and then stirring at a low speed for the second time, the rotating speed of the second-time low-speed stirring is 800r/min and the time is 70min, so as to obtain an intermediate mixture;
(3) And (3) mixing the intermediate mixture obtained in the step (2) with a binder and a solvent, wherein the binder is polyvinylidene fluoride, the addition amount of the polyvinylidene fluoride accounts for 0.8wt% of the positive active material, the solvent is N-methyl pyrrolidone, the addition amount of the N-methyl pyrrolidone accounts for 14wt% of the positive active material, so as to obtain positive slurry, the viscosity of the positive slurry is 5500mPa & s, then the positive slurry is coated on an aluminum foil, and then baking and cold pressing are carried out, the baking temperature is 115 ℃, and the pressure of the cold pressing is 40T, so as to obtain the positive plate of the lithium ion battery.
Example 6:
the present embodiment provides a lithium ion battery positive plate and a preparation method thereof, the preparation method refers to the method in embodiment 1, and only differs in that: the addition amount of the solid electrolyte in the step (2) accounts for 0.5wt% of the positive electrode active material.
Example 7:
the present embodiment provides a lithium ion battery positive plate and a preparation method thereof, the preparation method refers to the method in embodiment 2, and only differs in that: the stirring speed in the step (1) is 1000r/min.
Example 8:
the present embodiment provides a lithium ion battery positive plate and a preparation method thereof, the preparation method refers to the method in embodiment 1, and only differs in that: the rotating speed of the first-stage low-speed stirring in the step (2) is 1000r/min.
Comparative example 1:
the present comparative example provides a positive electrode sheet for a lithium ion battery and a method for preparing the same, which is the same as that of example 1 except that: in the steps (1) and (2), solid electrolyte is not added, but the positive active material and the positive conductive agent are directly stirred at a low speed.
The lithium ion battery positive electrode sheets prepared in examples 1 to 8 and comparative example 1 were used for assembling a lithium ion battery, the other structural components used were the same, the discharge performance test was performed after the lithium ion battery was fully charged, the discharge capacity and the final temperature after discharge were tested under two test conditions of discharge current 20A and discharge current 30A, and the results are shown in table 1.
Table 1 results of discharge performance test in examples 1 to 8 and comparative example 1
Figure BDA0003825862590000131
Figure BDA0003825862590000141
As can be seen from table 1, when the positive electrode sheets prepared by the methods of examples 1 to 5 are used for assembling a lithium ion battery, the lithium ion battery has high discharge capacity and good cycle performance, and can inhibit excessive temperature rise and prolong the service life; in example 6, the solid electrolyte is added in a relatively high amount, and although the solid electrolyte can also play a role in inhibiting temperature rise, the hardness of the electrode plate is too high, the adhesion is reduced, the material is easily dropped in the charging and discharging processes, and the cycle performance is affected; in example 7, since the stirring rate of the positive electrode conductive agent and the solid electrolyte was low, the carbon nanotubes could not be effectively dispersed into filaments and embedded in the positive electrode material, which affects the conductivity and discharge performance of the battery; in example 8, since the stirring rate when the positive electrode active material was mixed with the solid electrolyte was high, the powdery particles were easily sputtered, and light and heavy particles were layered, thereby affecting the dispersion effect of the solid electrolyte, affecting the improvement in the conductivity of the battery, and reducing the effect of suppressing the temperature increase;
in comparative example 1, the conductivity of the positive electrode material was weak, the internal impedance of the cell was large, and the temperature of the battery after discharge was high, which seriously affected the discharge capacity and the service life, because no solid electrolyte was added.
It can be seen from the above examples and comparative examples that the method of the present invention improves the conductivity of the positive electrode material by adding the solid electrolyte into the positive electrode active material and the positive electrode conductive agent, and inhibits the increase of the internal impedance of the battery cell during the discharging process, thereby inhibiting the excessive rise of the temperature, ensuring the sufficient release of the battery capacity and prolonging the service life of the lithium ion battery, wherein the battery temperature after the discharging does not exceed 80 ℃; the method has the advantages of simple operation, low cost of raw materials and process and wide application range.
The present invention is illustrated in detail by the examples described above, but the present invention is not limited to the details described above, i.e., it is not intended that the present invention be implemented by relying on the details described above. It will be apparent to those skilled in the art that any modifications to the present invention, equivalents of the method of the present invention and additions of ancillary steps, selection of specific means, etc., are within the scope and disclosure of the present invention.

Claims (10)

1. The preparation method of the lithium ion battery positive plate is characterized by comprising the following steps:
(1) Mixing the positive electrode conductive agent with the solid electrolyte, and then stirring at a high speed to obtain a mixed conductive agent;
(2) Mixing the positive active substance with the solid electrolyte, then carrying out first-stage low-speed stirring, then mixing with the mixed conductive agent obtained in the step (1), and then carrying out second-stage low-speed stirring to obtain an intermediate mixture;
(3) And (3) mixing the intermediate mixture obtained in the step (2) with a binder and a solvent to obtain positive electrode slurry, and then sequentially coating, baking and cold-pressing the positive electrode slurry to obtain the lithium ion battery positive plate.
2. The method according to claim 1, wherein the positive electrode conductive agent in step (1) comprises any one of or a combination of at least two of conductive carbon black, carbon nanotubes or conductive graphite;
preferably, the solid electrolyte in step (1) comprises any one of lithium lanthanum zirconium oxide, lithium lanthanum titanium oxide, lithium lanthanum zirconium tantalum oxide, lithium titanium aluminum phosphate or lithium germanium aluminum phosphate or a combination of at least two of the above;
preferably, the particle size of the solid electrolyte in the step (1) is 100-3000 nm;
preferably, the adding amount of the positive electrode conductive agent in the step (1) accounts for 0.5-1.5 wt% of the positive electrode active material in the step (2);
preferably, the solid electrolyte in the step (1) is added in an amount of 0.05 to 0.3wt% based on the positive electrode active material in the step (2).
3. The preparation method according to claim 1 or 2, characterized in that the rotation speed of the high-speed stirring in the step (1) is 2000-4000 r/min;
preferably, the high-speed stirring time in the step (1) is 60-90 min;
preferably, the mixed conductive agent obtained after the high-speed stirring in the step (1) is finished is vacuumized for standby.
4. The production method according to any one of claims 1 to 3, wherein the positive electrode active material in step (2) comprises any one of or a combination of at least two of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminate, lithium iron phosphate, or lithium manganese oxide;
preferably, the solid electrolyte in step (2) comprises any one of lithium lanthanum zirconium oxide, lithium lanthanum titanium oxide, lithium lanthanum zirconium tantalum oxide, lithium titanium aluminum phosphate or lithium germanium aluminum phosphate or a combination of at least two of the above;
preferably, the particle size of the solid electrolyte in the step (2) is 100-3000 nm;
preferably, the solid electrolyte added in the step (2) accounts for 0.1-0.3 wt% of the positive electrode active material in the step (2).
5. The process according to any one of claims 1 to 4, wherein the rotation speed of the one-stage low-speed stirring in the step (2) is 100 to 500r/min;
preferably, the time of the low-speed stirring in the step (2) is 30-60 min;
preferably, the rotation speed of the two-stage low-speed stirring in the step (2) is 500-1500 r/min;
preferably, the time of the two-stage low-speed stirring in the step (2) is 60-90 min.
6. The production method according to any one of claims 1 to 5, wherein the binder of step (3) comprises polyvinylidene fluoride;
preferably, the solvent of step (3) comprises N-methylpyrrolidone;
preferably, the addition amount of the binder in the step (3) accounts for 0.5-1.5 wt% of the positive electrode active material in the step (2);
preferably, the solvent in the step (3) is added in an amount of 10 to 15wt% of the positive active material in the step (2);
preferably, the viscosity of the positive electrode slurry in the step (3) is 4000 to 7000 mPas.
7. The production method according to any one of claims 1 to 6, wherein the positive electrode slurry of step (3) is coated on a current collector;
preferably, the current collector comprises an aluminum foil;
preferably, the baking temperature in the step (3) is 100-120 ℃;
preferably, the pressure of the cold pressing in the step (3) is 25-45T.
8. A lithium ion battery positive plate obtained by the preparation method according to any one of claims 1 to 7.
9. A lithium ion battery, characterized in that the lithium ion battery comprises the lithium ion battery positive electrode sheet according to claim 8;
preferably, the lithium ion battery is formed by assembling a positive plate, a negative plate, a diaphragm and a shell, and then adding the electrolyte and sealing.
10. The lithium ion battery of claim 9, wherein the negative electrode sheet is obtained by coating, baking and cold pressing a negative electrode slurry in sequence;
preferably, the composition of the anode slurry includes an anode active material, an anode conductive agent, and a binder.
CN202211058877.7A 2022-08-31 2022-08-31 Lithium ion battery positive plate, preparation method thereof and lithium ion battery Pending CN115295769A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117012957A (en) * 2023-10-08 2023-11-07 深圳市贝特瑞新能源技术研究院有限公司 Low-temperature-resistant lithium iron phosphate semi-solid battery, positive electrode slurry thereof and preparation method thereof

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117012957A (en) * 2023-10-08 2023-11-07 深圳市贝特瑞新能源技术研究院有限公司 Low-temperature-resistant lithium iron phosphate semi-solid battery, positive electrode slurry thereof and preparation method thereof
CN117012957B (en) * 2023-10-08 2024-01-19 深圳市贝特瑞新能源技术研究院有限公司 Low-temperature-resistant lithium iron phosphate semi-solid battery, positive electrode slurry thereof and preparation method thereof

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