CN117334840A - Negative electrode plate and preparation method and application thereof - Google Patents

Negative electrode plate and preparation method and application thereof Download PDF

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Publication number
CN117334840A
CN117334840A CN202210718975.2A CN202210718975A CN117334840A CN 117334840 A CN117334840 A CN 117334840A CN 202210718975 A CN202210718975 A CN 202210718975A CN 117334840 A CN117334840 A CN 117334840A
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negative electrode
silicon
slurry
conductive agent
mass fraction
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Inventor
杨宁宁
廖健淞
杨淋
李钧
郭小平
郑春红
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Tuomi Chengdu Applied Technology Research Institute Co ltd
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Tuomi Chengdu Applied Technology Research Institute 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
    • H01M4/134—Electrodes based on metals, Si or alloys
    • 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
    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • H01M4/0404—Methods of deposition of the material by coating on electrode collectors
    • 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
    • H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
    • 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
    • H01M4/621—Binders
    • 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
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative 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

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

Abstract

The invention provides a negative pole piece, a preparation method and application thereof, wherein the preparation method comprises the following steps: mixing a silicon nanowire with a first solvent, sequentially adding a first conductive agent, an adhesive, a second conductive agent and a thickening agent to obtain negative electrode slurry, and coating the negative electrode slurry on the surface of a current collector to obtain a negative electrode plate; the total mass fraction of the solid raw materials of the cathode slurry is 100wt%, and the addition amount of the silicon nanowires is 60-85 wt%. The negative electrode plate obtained by the preparation method provided by the invention can effectively inhibit the volume expansion of silicon in the lithium removal and intercalation process, so that the battery has excellent multiplying power charge and discharge performance, cycle performance and safety performance, and meanwhile, the preparation process of the negative electrode plate is simple, low in cost and environment-friendly.

Description

Negative electrode plate and preparation method and application thereof
Technical Field
The invention belongs to the technical field of lithium battery production and manufacturing, and particularly relates to a negative electrode plate, a preparation method and application thereof.
Background
Lithium ion batteries have been widely used in portable electronic products and electric vehicles due to their excellent cost, manufacturing process and multi-cycle stability. At present, commercial lithium ion batteries mainly adopt graphite anode materials with specific capacity of 372mAh/g, and the development of the prior art is close to the theoretical value, and the potential for further developing the graphite anode materials is limited, so that the development of miniaturization of portable electronic equipment and the wide requirements of electric automobiles on high-specific energy and high-power density lithium ion batteries can not be met.
The theoretical specific capacity of silicon is 4200mAh/g, which is ten times or more than that of graphite, and the silicon resource reserves are rich, so that the silicon is considered as one of ideal candidate materials for developing new generation high specific energy and high power density lithium ion battery anode materials. However, silicon can vary in volume by up to 400% during the battery charge and discharge cycles, resulting in poor initial efficiency and cycle performance.
CN105609749a discloses a silicon nanowire and its application, a chemical etching process employing an etchant that preferentially etches and removes other phases from a multiphase silicon alloy over the silicon phase, resulting in a silicon nanowire. According to the silicon nanowire: super-P carbon black conductive agent: PVDF binder mass ratio 8:1:1, uniformly mixing, pulping by using N-methyl pyrrolidone as a solvent, and baking at 120 ℃ for 12 hours to obtain the lithium ion battery cathode, wherein the initial discharge capacity is 2510mAh/g at the highest, and the maximum capacity retention rate is 50% after 50 times of circulation, so that the volume expansion of silicon in the lithium removal and intercalation process can not be effectively relieved.
CN103000865a discloses a method for preparing carbon fiber-silicon nanowire anode material, which comprises: (1) preparation of a silicon nanowire anode material: firstly, plating a gold film with the thickness of 5-10 nm on the surface of a silicon wafer by vacuum evaporation; introducing argon/hydrogen mixed gas into a tube furnace, then placing a silicon wafer after gold plating, heating the tube furnace to 700-800 ℃, preserving heat for 3-4 hours, then cooling to 450-550 ℃, introducing silane gas, and cooling to room temperature along with the furnace for 1.5-2.5 hours to obtain a layer of silicon nanowire; (2) Ball milling method for preparing carbon fiber-silicon nanowire composite material: and (3) preparing the silicon nanowire and the carbon nanofiber obtained in the step (1) according to the molar ratio of 1:1, and then placing the mixture and the polyurethane ball in a three-dimensional mixing tank for mixing to obtain the carbon fiber-silicon nanowire composite material. The capacity retention rate of the anode material prepared by the method can reach about 80% after 50 circles of circulation, but the initial discharge capacity of the anode material is only 1700mAh/g, and the preparation process is complex.
CN114388748A discloses a silicon-carbon negative electrode slurry and a preparation process thereof, wherein the slurry comprises a silicon-carbon negative electrode active material, a conductive agent, an adhesive, a thickener and a solvent, the silicon-carbon negative electrode active material comprises a silicon-based negative electrode and a graphite negative electrode, and the preparation process comprises the preparation of dot-shaped conductive slurry, silicon-based conductive slurry, primary negative electrode slurry and silicon-carbon negative electrode slurry. According to the preparation process, the silicon-based negative electrode and the linear conductive agent are mixed, so that the linear conductive agent is uniformly wrapped on the surface of the silicon-based negative electrode, the volume expansion effect of the silicon-based negative electrode is effectively relieved by wrapping the linear conductive agent, but the initial capacity and the cycle performance of the negative electrode plate prepared by adopting the negative electrode slurry are not illustrated.
Therefore, how to effectively relieve the volume expansion of the silicon material in the circulation process is important to improve the rate charge-discharge performance, the circulation performance and the safety performance of the battery.
Disclosure of Invention
Aiming at the defects existing in the prior art, the invention aims to provide the negative electrode plate, the preparation method and the application thereof, and the negative electrode plate obtained by adopting the preparation method provided by the invention can effectively inhibit the volume expansion of silicon in the lithium removal and intercalation process, so that the battery has excellent multiplying power charge and discharge performance, cycle performance and safety performance, and meanwhile, the preparation process of the negative electrode plate is simple, the cost is low, and the battery is environment-friendly.
To achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a method for preparing a negative electrode sheet, the method comprising:
mixing a silicon nanowire with a first solvent, sequentially adding a first conductive agent, an adhesive, a second conductive agent and a thickening agent to obtain negative electrode slurry, and coating the negative electrode slurry on the surface of a current collector to obtain a negative electrode plate;
the amount of the silicon nanowire added is 60 to 85wt% based on 100wt% of the total mass fraction of the solid raw material of the negative electrode slurry, and may be, for example, 60wt%, 62wt%, 64wt%, 66wt%, 68wt%, 70wt%, 72wt%, 74wt%, 76wt%, 78wt%, 80wt%, 82wt%, or 85wt%, but is not limited to the recited values, and other non-recited values within the range of the recited values are equally applicable.
The invention firstly disperses the silicon nano wires in the first solvent, then sequentially adds the first conductive agent, the adhesive glue solution, the second conductive agent and the thickening agent, and the invention ensures good conductivity among the silicon nano wires because the first conductive agent and the silicon nano wires are uniformly mixed to form a conductive link network, the adhesive ensures that the silicon nano wires and the first conductive agent are stably combined, the second conductive agent is added to further enhance the conductivity of the electrode plate, the thickening agent maintains the slurry at a certain viscosity, and the slurry is convenient to be coated on the copper foil to prepare the negative electrode plate.
Meanwhile, the invention limits the adding amount of the silicon nanowire to 60-85 wt%, and when the adding amount of the silicon nanowire is lower than 60wt%, the capacity of a pole piece per unit weight is reduced, because the content of the active substance silicon nanowire is low; when the addition amount of the silicon nanowire is higher than 85wt%, the cycle performance of the negative plate of the silicon nanowire is reduced, because the content of the silicon nanowire is increased, the content of conductive carbon and adhesive is reduced, the conductivity of the plate is reduced, and the silicon nanowire is separated from the silicon nanowire to crack. According to the invention, the silicon nanowire is only used as an active substance of the negative electrode plate, and other active substances such as carbon materials are not required to be added, so that the effects of improving the multiplying power charge-discharge performance, the cycle performance and the safety performance of the battery can be achieved.
In addition, the solid raw material of the anode slurry in the present invention refers to a raw material in a solid form, and illustratively, when the silicon nanowire, the first conductive agent, the binder, the second conductive agent, and the thickener all participate in the formulation of the anode slurry in a solid form of powder or the like, the total mass of the solid raw material refers to the total mass of the silicon nanowire, the first conductive agent, the binder, the second conductive agent, and the thickener; when the silicon nanowire, the first conductive agent and the thickener participate in the preparation of the anode slurry in a solid form, and the binder is prepared into a binder glue solution, and the second conductive agent is prepared into a second conductive agent slurry to participate in the preparation of the anode slurry, the total mass of the solid raw materials refers to the total mass of the silicon nanowire, the first conductive agent, the binder in the binder glue solution, the second conductive agent in the second conductive agent slurry and the thickener.
According to the invention, the silicon nanowire is used as an active substance, and the first conductive agent, the adhesive, the second conductive agent and the thickening agent are sequentially added after the silicon nanowire is dispersed, so that the synergistic effect of regulating the addition of the silicon nanowire to be 60-85 wt% can effectively inhibit the volume expansion of silicon in the lithium deintercalation process, thereby improving the multiplying power charge-discharge performance, the cycle performance and the safety performance of the battery at the same time, and meanwhile, the preparation process of the negative electrode plate is simple, low in cost and environment-friendly.
As a preferable technical scheme of the invention, the preparation process of the silicon nanowire comprises the following steps:
and (3) performing primary evaporation on a silicon source to obtain silicon vapor, performing secondary evaporation on an aluminum source to obtain aluminum vapor, and then introducing the silicon vapor into the aluminum vapor to react to obtain the silicon nanowire.
According to the method, aluminum with a low melting point and reducibility is used as a control agent for growth of the silicon nanowire in the preparation process of the silicon nanowire, and plays a role in catalysis, the silicon nanowire starts to grow when silicon vapor and aluminum vapor meet, and the silicon nanowire with excellent structural cycle stability can be obtained, because aluminum liquid drops (nanoscale) in a furnace are dissolved in the aluminum liquid drops when the silicon vapor meets the aluminum liquid drops, and the silicon nanowire with a long silicon atom is continuously separated out, and the silicon nanowire grows uniformly and has few impurities under a certain temperature condition; meanwhile, the preparation method of the silicon nanowire provided by the invention has low requirements on the purity of raw materials and is controllable in cost; and the preparation method has simple and reliable working procedures and is convenient for large-scale mass production.
When the silicon nanowire obtained by the method is used for the active material of the negative electrode plate, the initial discharge specific capacity and the cyclic capacity retention rate of the battery can be further improved due to the excellent structural cyclic stability of the silicon nanowire.
The purity of the silicon source is preferably not less than 95%, and may be, for example, 95%,95.5%,96%,96.5%,97%,97.5%,98%,98.5%,99%,99.5%,99.9%, etc., but is not limited to the above-mentioned values, and other values not shown in the above-mentioned ranges are equally applicable.
Preferably, the silicon source comprises any one or a combination of at least two of silicon powder, silicon block, silicon dioxide or silicon oxide.
The temperature of the primary evaporation is preferably 1600 to 2000 ℃, and may be 1600 ℃,1650 ℃,1700 ℃,1750 ℃,1800 ℃,1850 ℃,1900 ℃,2000 ℃, or the like, for example, but is not limited to the recited values, and other non-recited values within the above-recited ranges are equally applicable.
As a preferred technical scheme of the invention, the aluminum source comprises any one or a combination of at least two of aluminum plates, aluminum powder or aluminum wires.
Preferably, the surface of the aluminum source contains a plating layer.
Preferably, the material of the plating layer comprises gold and/or silver.
The temperature of the secondary evaporation is preferably 500 to 800 ℃, and may be 500 to 520 ℃,550 ℃,580 ℃,600 ℃,630 ℃,650 ℃,670 ℃,700 ℃,730 ℃,50 ℃,780 ℃,800 ℃, or the like, for example, but not limited to the values listed, and other values not listed in the above-mentioned numerical ranges are equally applicable.
Preferably, the secondary evaporation is performed in an argon atmosphere.
Preferably, the silicon vapor is introduced into the aluminum vapor at a rate of 2 to 5g/min, for example, 2g/min,2.2g/min,2.4g/min,2.6g/min,2.8g/min,3g/min,3.2g/min,3.4g/min,3.6g/min,3.8g/min,4g/min,4.2g/min,4.4g/min,4.6g/min,4.8g/min,5g/min, etc., but not limited to the recited values, and other non-recited values within the above range are equally applicable.
The invention limits the speed of introducing silicon vapor into aluminum vapor to be 2-5g/min, and if the speed is higher than 5g/min, the diameter of the silicon nanowire is thicker and the length is shorter; if it is less than 2g/min, the silicon nanowire is thin and short in length.
The reaction temperature is preferably 500 to 800 ℃, and may be 500 ℃,520 ℃,550 ℃,580 ℃,600 ℃,630 ℃,650 ℃,670 ℃,700 ℃,730 ℃,50 ℃,780 ℃,800 ℃, or the like, for example, but is not limited to the recited values, and other non-recited values within the above-recited ranges are equally applicable.
Preferably, the reaction time is 1 to 5 hours, for example, 1h,1.2h,1.5h,1.8h,2h,2.3h,2.5h,2.7h,3h,3.2h,3.5h,3.8h,4h,4.2h,4.5h,4.7h,5h, etc., but not limited to the recited values, other non-recited values within the above range are equally applicable.
Preferably, the silicon nanowires have a diameter < 200nm and a length > 100 μm.
According to the invention, the speed of introducing silicon vapor into aluminum vapor is regulated, the size of the silicon nanowire is regulated, and when the silicon nanowire with the diameter smaller than 200nm and the length larger than 100 mu m is used as an active substance of a negative electrode plate, the silicon nanowire is favorable for further improving the cycle stability, the multiplying power charge-discharge performance and the safety performance of a battery, because the silicon nanowire is not cracked and crushed in the lithium intercalation and deintercalation process when the diameter of the silicon nanowire is smaller than 200nm, the integrity of the silicon nanowire can be maintained, the length of the silicon nanowire is larger than 100 mu m, a better intercommunication network can be formed between the silicon wires, and the capacity exertion and the cycle performance improvement are facilitated.
As a preferred embodiment of the present invention, the first solvent includes water and/or ethanol.
Preferably, the mixing time of the silicon nanowire and the first solvent is 10 to 60min, for example, 10min, 15min, 20min, 25min, 30min, 35min, 40min, 45min, 50min, 55min or 60min, but not limited to the recited values, and other non-recited values within the range of values are equally applicable.
Preferably, the silicon nanowires and the first solvent are mixed under milling conditions.
The invention puts the silicon nanowire into a mortar, and adds a first solvent for grinding and mixing uniformly.
Preferably, the first conductive agent, the binder, the second conductive agent, and the thickener are sequentially added under stirring.
The method sequentially adds a first conductive agent, an adhesive, a second conductive agent and a thickening agent into the uniformly ground silicon nanowire while stirring.
Preferably, the stirring speed is 100 to 300rpm/min, for example, 100rpm/min, 120rpm/min, 150rpm/min, 180rpm/min, 200rpm/min, 220rpm/min, 250rpm/min, 280rpm/min or 300rpm/min, but the stirring speed is not limited to the recited values, and other non-recited values within the range of the values are equally applicable.
Preferably, after the first conductive agent, the adhesive, the second conductive agent, and the thickener are sequentially added, stirring is continued for 30 to 120 minutes, for example, 30 minutes, 40 minutes, 50 minutes, 60 minutes, 70 minutes, 80 minutes, 90 minutes, 100 minutes, 110 minutes, or 120 minutes, but the present invention is not limited to the listed values, and other non-listed values within the range of values are equally applicable.
In a preferred embodiment of the present invention, the amount of the first conductive agent added is 1 to 15wt% based on 100wt% of the total mass fraction of the solid raw material of the negative electrode slurry, and may be, for example, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 11wt%, 12wt%, 13wt%, 14wt% or 15wt%, but is not limited to the above-mentioned values, and other values not mentioned in the above-mentioned value range are equally applicable.
Preferably, the binder is added in an amount of 5 to 20wt% based on 100wt% of the total mass fraction of the solid raw material of the negative electrode slurry, and may be, for example, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt% or 20wt%, but is not limited to the recited values, and other non-recited values within the range of values are equally applicable.
The second conductive agent is preferably added in an amount of 0.5 to 5wt% based on 100wt% of the total mass fraction of the solid raw material of the negative electrode slurry, and may be, for example, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, or 5wt%, but is not limited to the recited values, and other non-recited values within the range of the values are equally applicable.
Preferably, the thickener is added in an amount of 2 to 8wt% based on 100wt% of the total mass fraction of the solid raw material of the negative electrode slurry, for example, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt% or 8wt%, but the thickener is not limited to the recited values, and other non-recited values within the range of the recited values are equally applicable.
In the invention, the formula of the negative electrode plate preferably comprises: 60-85 wt% of silicon nanowire, 1-15 wt% of first conductive agent, 5-20 wt% of adhesive, 0.5-5 wt% of second conductive agent and 2-8 wt% of thickener; the silicon nanowire with excellent structural circulation stability is used as an active substance, the content of each component in the negative electrode slurry is regulated and controlled within the range, the volume expansion of silicon in the charge-discharge process can be better inhibited, and the circulation performance and the multiplying power charge-discharge performance of the battery are further improved.
As a preferred technical solution of the present invention, the first conductive agent includes any one or a combination of at least two of conductive carbon black, acetylene black, carbon fiber or conductive graphene.
Preferably, the adhesive is mixed with a second solvent to prepare an adhesive glue solution, and after the silicon nanowires and the first solvent are mixed, the first conductive agent, the adhesive glue solution, the second conductive agent and the thickener are sequentially added to obtain the negative electrode slurry.
Preferably, the solids content of the adhesive glue is 4 to 6wt%, for example, 4wt%, 4.2wt%, 4.4wt%, 4.6wt%, 5wt%, 5.2wt%, 5.4wt%, 5.6wt%, 5.8wt% or 6wt%, but is not limited to the recited values, and other non-recited values within the range of values are equally applicable.
Preferably, the binder comprises any one or a combination of at least two of styrene butadiene rubber, polyethylene glycol or polyvinyl acetate.
Preferably, the second solvent comprises water and/or ethanol.
Preferably, the second conductive agent is dispersed in a third solvent to form second conductive agent slurry, and after the silicon nanowire and the first solvent are mixed, the first conductive agent, the adhesive glue solution, the second conductive agent slurry and the thickener are sequentially added to obtain the negative electrode slurry.
In the invention, the first conductive agent participates in the preparation of the anode slurry in a powder state, and the second conductive agent participates in the preparation of the anode slurry in a slurry state, because the second conductive agent is difficult to disperse, and the slurry can be mixed more uniformly by pre-dispersing.
Preferably, the solid content of the second conductive agent slurry is 0.2 to 0.6wt%, for example, 0.2wt%, 0.25wt%, 0.3wt%, 0.35wt%, 0.4wt%, 0.45wt%, 0.5wt%, 0.55wt% or 0.6wt%, but not limited to the recited values, and other non-recited values within the range of values are equally applicable.
Preferably, the second conductive agent includes carbon nanotubes.
Preferably, the thickener comprises any one or a combination of at least two of sodium carboxymethyl cellulose, hydroxypropyl cellulose, hydroxyethyl cellulose, hydroxypropyl methylcellulose or polyvinylpyrrolidone.
The viscosity of the negative electrode slurry is preferably 1000 to 3000cp, and may be 1000cp, 1200cp, 1500cp, 1800cp, 2000cp, 2200cp, 2500cp, 2800cp or 3000cp, for example, but the present invention is not limited to the listed values, and other values not listed in the range of values are equally applicable.
The solid content of the negative electrode slurry is preferably 6 to 8wt%, and may be, for example, 6wt%, 6.2wt%, 6.4wt%, 6.6wt%, 6.8wt%, 7wt%, 7.2wt%, 7.4wt%, 7.6wt%, 7.8wt%, or 8wt%, but is not limited to the recited values, and other non-recited values within the range of values are equally applicable.
As a preferred technical scheme of the present invention, the preparation method further comprises:
and coating the negative electrode slurry on the surface of the current collector, and then drying to form a slurry coating on the surface of the current collector to obtain the negative electrode plate.
The temperature of the drying treatment is preferably 70 to 90 ℃, and may be, for example, 70 ℃, 75 ℃,80 ℃, 85 ℃, or 90 ℃, but is not limited to the values listed, and other values not listed in the range are equally applicable.
Preferably, the drying time is 60 to 240min, for example, 60min, 80min, 100min, 120min, 140min, 160min, 180min, 200min, 220min or 240min, but not limited to the recited values, and other non-recited values within the range are equally applicable.
Preferably, the thickness of the slurry coating is 150 to 250 μm, for example, 150 μm, 170 μm, 190 μm, 200 μm, 220 μm, 240 μm or 250 μm, but is not limited to the recited values, and other non-recited values within the range of values are equally applicable.
Preferably, after the slurry coating is formed on the surface of the current collector, rolling and cutting are sequentially performed to obtain the negative electrode plate.
In a second aspect, the invention provides a negative electrode plate, which comprises a current collector and a slurry coating on the surface of the current collector, wherein the negative electrode plate is prepared by the preparation method in the first aspect.
In a preferred embodiment of the present invention, the mass fraction of the silicon nanowires in the slurry coating layer is 60 to 85wt% based on 100wt% of the total mass of the slurry coating layer, and may be, for example, 60wt%, 62wt%, 64wt%, 66wt%, 68wt%, 70wt%, 72wt%, 74wt%, 76wt%, 78wt%, 80wt%, 82wt% or 85wt%, but not limited to the recited values, and other non-recited values within the range of the values are equally applicable.
Preferably, the mass fraction of the first conductive agent in the slurry coating layer is 1 to 15wt% based on 100wt% of the total mass of the slurry coating layer, and may be, for example, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 11wt%, 12wt%, 13wt%, 14wt% or 15wt%, but is not limited to the recited values, and other non-recited values within the range of values are equally applicable.
Preferably, the mass fraction of the binder in the slurry coating is 5 to 20wt%, for example, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt% or 20wt%, based on the total mass of the slurry coating, but is not limited to the recited values, and other non-recited values within the range of values are equally applicable.
Preferably, the mass fraction of the second conductive agent in the slurry coating layer is 0.5 to 5wt% based on 100wt% of the total mass of the slurry coating layer, and may be, for example, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt% or 5wt%, but is not limited to the recited values, and other non-recited values within the range of values are equally applicable.
Preferably, the mass fraction of the thickener in the slurry coating is 2 to 8wt%, for example, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt% or 8wt%, based on the total mass of the slurry coating is 100wt%, but is not limited to the recited values, and other non-recited values within the range of values are equally applicable.
In a third aspect, the present invention provides a lithium ion battery, which includes the negative electrode tab according to the second aspect.
Compared with the prior art, the invention has the beneficial effects that:
(1) The negative electrode plate obtained by the preparation method provided by the invention can effectively inhibit the volume expansion of silicon in the lithium removal process, so that the battery has excellent multiplying power charge-discharge performance, cycle performance and safety performance, wherein the initial discharge specific capacity is higher than 3200mAh/g, the discharge specific capacity of the battery is still higher than 2750mAh/g after 100 cycles of charge-discharge cycle, and the capacity retention rate is higher than 85%.
(2) The preparation process of the negative electrode plate provided by the invention is simple and reliable, has low cost, and can be compatible with the existing mass production process; and the solvent is nontoxic, the equipment does not need explosion-proof facilities, and the environment is friendly.
Drawings
Fig. 1 is a flowchart of a preparation process of the negative electrode sheet provided in examples 1 to 6 of the present invention.
Fig. 2 is a scanning electron microscope image of the silicon nanowire provided in example 1 of the present invention at 20kV magnification.
Fig. 3 is a scanning electron microscope image of the silicon nanowire provided in example 1 of the present invention with a magnification of 20kV after 100 cycles of charge and discharge.
Fig. 4 is a cycle stability chart of a battery assembled by using the negative electrode tab provided in example 1 of the present invention.
Detailed Description
The technical scheme of the invention is further described by the following specific embodiments. It will be apparent to those skilled in the art that the examples are merely to aid in understanding the invention and are not to be construed as a specific limitation thereof.
Example 1
The embodiment provides a preparation method of a negative electrode plate, as shown in fig. 1, the preparation method includes:
(1) 3kg of silicon dioxide with purity of 98% is heated to 1800 ℃ for one-time evaporation to obtain silicon dioxide vapor; heating an aluminum plate with a silver coating on the surface to 700 ℃ and performing secondary evaporation in an argon atmosphere to obtain aluminum vapor; then, introducing silicon dioxide vapor into aluminum vapor at a speed of 2g/min, and reacting for 3 hours at 750 ℃ to obtain silicon nanowires, as shown in figure 2;
(2) Mixing and grinding 80wt% of the silicon nanowire obtained in the step (1) with water for 40min, sequentially adding 7wt% of conductive carbon black (SP) at a stirring speed of 200rpm/min, and stirring for 80min to obtain a cathode slurry with 7wt% of solid content and 2000cp viscosity, wherein the styrene-butadiene rubber solution has a solid content of 5.6wt% (the addition amount of the styrene-butadiene rubber solution is 7wt% based on the mass fraction of the styrene-butadiene rubber) and the carbon nanotube slurry has a solid content of 0.4wt% (the addition amount of the carbon nanotube slurry is 3wt% based on the mass fraction of the carbon nanotube);
(3) And (3) coating the negative electrode slurry prepared in the step (2) on the surface of a copper foil by adopting a 200 mu m high-height scraping rod, drying the copper foil in an oven at 80 ℃ for 120min, and then sequentially rolling and cutting to obtain a negative electrode plate.
The mass fraction of the conductive carbon black, the styrene-butadiene rubber, the carbon nanotube and the sodium carboxymethyl cellulose in this example was 100wt% based on the total mass fraction of the solid raw materials of the negative electrode slurry.
Example 2
The embodiment provides a preparation method of a negative electrode plate, as shown in fig. 1, the preparation method includes:
(1) Heating 2kg of silicon powder with purity of 95% to 2000 ℃ for one-time evaporation to obtain silicon vapor; heating an aluminum block with a gold plating layer on the surface to 800 ℃ and performing secondary evaporation in an argon atmosphere to obtain aluminum vapor; then introducing silicon vapor into aluminum vapor at a speed of 5g/min, and reacting at 800 ℃ for 1h to obtain silicon nanowires;
(2) Mixing and grinding the silicon nanowire with the mass fraction of 60wt% obtained in the step (1) with water for 10min, sequentially adding conductive carbon black (SP) with the mass fraction of 15wt% and styrene-butadiene rubber solution with the solid content of 5.6wt% (the addition amount of the styrene-butadiene rubber solution is 15wt% based on the mass fraction of the styrene-butadiene rubber) at the stirring speed of 300rpm/min, and continuously stirring for 30min to obtain carbon nanotube slurry with the solid content of 7wt% and the viscosity of 3000cp (the addition amount of the carbon nanotube slurry is 5wt% based on the mass fraction of the carbon nanotube);
(3) And (3) coating the negative electrode slurry prepared in the step (2) on the surface of a copper foil by adopting a 200 mu m high-height scraping rod, drying the copper foil in a 70 ℃ oven for 240min, and then sequentially rolling and cutting to obtain a negative electrode plate.
The mass fraction of the conductive carbon black, the styrene-butadiene rubber, the carbon nanotube and the sodium carboxymethyl cellulose in this example was 100wt% based on the total mass fraction of the solid raw materials of the negative electrode slurry.
Example 3
The embodiment provides a preparation method of a negative electrode plate, as shown in fig. 1, the preparation method includes:
(1) Heating 1kg of silicon powder with the purity of 96% and 2kg of silicon dioxide with the purity of 96% to 1700 ℃ for one-time evaporation to obtain silicon vapor; heating an aluminum plate with a silver coating on the surface to 600 ℃, and performing secondary evaporation under argon atmosphere to obtain aluminum vapor; then introducing silicon vapor into aluminum vapor at a speed of 3g/min, and reacting at 600 ℃ for 2 hours to obtain silicon nanowires;
(2) Mixing and grinding the silicon nanowire with the mass fraction of 65wt% obtained in the step (1) with water for 20min, sequentially adding 12wt% of acetylene black and 5.6wt% of styrene-butadiene rubber solution (the addition amount of the styrene-butadiene rubber solution is 14wt% based on the mass fraction of the styrene-butadiene rubber) at a stirring speed of 200rpm/min, and continuously stirring for 100min to obtain carbon nanotube slurry with the solid content of 6wt% and the viscosity of 2000cp, wherein the carbon nanotube slurry with the solid content of 0.4wt% is the addition amount of the carbon nanotube slurry is 4wt% based on the mass fraction of the carbon nanotube;
(3) And (3) coating the negative electrode slurry prepared in the step (2) on the surface of a copper foil by adopting a 200 mu m high-height scraping rod, drying the copper foil in a 90 ℃ oven for 60min, and then sequentially rolling and cutting the copper foil to obtain a negative electrode plate.
In this example, the mass fraction of acetylene black, styrene-butadiene rubber, carbon nanotubes and sodium carboxymethylcellulose was 100wt% based on the total mass fraction of the solid raw materials of the negative electrode slurry.
Example 4
The embodiment provides a preparation method of a negative electrode plate, as shown in fig. 1, the preparation method includes:
(1) Heating 2.1kg of silicon blocks with purity of 97.2% to 1600 ℃ for one-time evaporation to obtain silicon vapor; heating an aluminum plate with a gold coating on the surface to 500 ℃ and performing secondary evaporation in an argon atmosphere to obtain aluminum vapor; then introducing silicon vapor into aluminum vapor at a speed of 3g/min, and reacting for 5 hours at 500 ℃ to obtain silicon nanowires;
(2) Mixing and grinding the silicon nanowire with the mass fraction of 70wt% obtained in the step (1) with water for 60min, sequentially adding conductive carbon black (SP) with the mass fraction of 10wt% and polyethylene glycol glue solution with the solid content of 5.6wt% (the addition amount of the polyethylene glycol glue solution is 9wt% based on the mass fraction of polyethylene glycol) and carbon nano tube slurry with the solid content of 0.4wt% (the addition amount of the carbon nano tube slurry is 3wt% based on the mass fraction of carbon nano tubes) at the stirring speed of 100rpm/min, and continuously stirring for 120min to obtain sodium carboxymethyl cellulose with the solid content of 8wt% and the viscosity of 1000 cp;
(3) And (3) coating the negative electrode slurry prepared in the step (2) on the surface of a copper foil by adopting a 200 mu m high-height scraping rod, drying the copper foil in an oven at 80 ℃ for 120min, and then sequentially rolling and cutting to obtain a negative electrode plate.
The mass fraction of the conductive carbon black, polyethylene glycol, carbon nanotubes and sodium carboxymethylcellulose in this example was based on 100wt% of the total mass fraction of the solid raw material of the negative electrode slurry.
Example 5
The embodiment provides a preparation method of a negative electrode plate, as shown in fig. 1, the preparation method includes:
(1) Heating 1.5kg of silicon powder with the purity of 98.1% and 1kg of silicon dioxide with the purity of 98% to 1850 ℃ for primary evaporation to obtain silicon vapor; heating an aluminum plate with a gold coating on the surface to 650 ℃, and performing secondary evaporation under argon atmosphere to obtain aluminum vapor; then introducing silicon vapor into aluminum vapor at a speed of 4g/min, and reacting at 650 ℃ for 2.5h to obtain silicon nanowires;
(2) Mixing and grinding the silicon nanowire with the mass fraction of 85wt% obtained in the step (1) with water for 50min, sequentially adding conductive carbon black (SP) with the mass fraction of 1wt% and styrene-butadiene rubber solution with the solid content of 5.6wt% (the addition amount of the styrene-butadiene rubber solution is calculated by the mass fraction of the styrene-butadiene rubber, the mass fraction of the styrene-butadiene rubber is 8 wt%) and carbon nanotube slurry with the solid content of 0.4wt% (the addition amount of the carbon nanotube slurry is calculated by the mass fraction of the carbon nanotube, the mass fraction of the carbon nanotube is 4 wt%), and polyvinylpyrrolidone with the mass fraction of 2 wt%), and continuously stirring for 80min to obtain cathode slurry with the solid content of 7wt% and the viscosity of 2000 cp;
(3) And (3) coating the negative electrode slurry prepared in the step (2) on the surface of a copper foil by adopting a 200 mu m high-height scraping rod, drying the copper foil in an oven at 80 ℃ for 120min, and then sequentially rolling and cutting to obtain a negative electrode plate.
The mass fraction of the conductive carbon black, the styrene-butadiene rubber, the carbon nanotube and the polyvinylpyrrolidone in the embodiment is 100wt% based on the total mass fraction of the solid raw materials of the negative electrode slurry.
Example 6
The embodiment provides a preparation method of a negative electrode plate, as shown in fig. 1, the preparation method includes:
(1) 3kg of silicon dioxide with purity of 98% is heated to 1800 ℃ for one-time evaporation to obtain silicon dioxide vapor; heating an aluminum plate with a silver coating on the surface to 700 ℃ and performing secondary evaporation in an argon atmosphere to obtain aluminum vapor; then introducing silicon dioxide vapor into aluminum vapor at a speed of 2g/min, and reacting for 3 hours at 750 ℃ to obtain silicon nanowires;
(2) Mixing and grinding the silicon nanowire with the mass fraction of 78wt% obtained in the step (1) with water for 50min, sequentially adding conductive carbon black (SP) with the mass fraction of 5wt% and styrene-butadiene rubber solution with the solid content of 5.6wt% (the addition amount of the styrene-butadiene rubber solution is 10wt% based on the mass fraction of the styrene-butadiene rubber) at a stirring speed of 200rpm/min, and continuously stirring for 80min to obtain carbon nanotube slurry with the solid content of 7wt% and the viscosity of 2500cp (the addition amount of the carbon nanotube slurry is 3wt% based on the mass fraction of the carbon nanotube);
(3) And (3) coating the negative electrode slurry prepared in the step (2) on the surface of a copper foil by adopting a 200 mu m high-height scraping rod, drying the copper foil in an oven at 80 ℃ for 120min, and then sequentially rolling and cutting to obtain a negative electrode plate.
The mass fraction of the conductive carbon black, the styrene-butadiene rubber, the carbon nanotube and the sodium carboxymethyl cellulose in this example was 100wt% based on the total mass fraction of the solid raw materials of the negative electrode slurry.
Comparative example 1
This comparative example is different from example 1 in that acetylene black, styrene-butadiene rubber solution, carbon nanotube slurry and sodium carboxymethyl cellulose are simultaneously added in step (2), and the remaining process parameters and operation conditions are the same as example 1.
Comparative example 2
The present comparative example is different from example 1 in that the mass fraction of the silicon nanowire in step (2) is 55wt% and the reduced mass of the silicon nanowire is distributed to the conductive carbon black, styrene-butadiene rubber, carbon nanotube and sodium carboxymethyl cellulose in the formulation ratio, and the remaining process parameters and operation steps are the same as example 1.
Comparative example 3
The comparative example is different from example 1 in that the mass fraction of the silicon nanowire in step (2) is 90wt%, the mass of the silicon nanowire added is equal to the total amount of the conductive carbon black, the styrene-butadiene rubber, the carbon nanotube and the sodium carboxymethyl cellulose reduced in the formulation proportion, and the remaining process parameters and the operation steps are the same as example 1.
The negative electrode tabs prepared in examples 1-6 and comparative examples 1-3 were assembled into CR2032 coin cells: lithium sheets were used as counter electrodes, lelgard2400 was used as separator, and 1mol/L lithium hexafluorophosphate/ethyl carbonate+dimethyl carbonate (volume ratio 3:7) was used as electrolyte.
And (3) adopting a Xinwei BTS battery detection system to perform constant current charge and discharge test, and using 0.1C current to perform charge and discharge test on half batteries, wherein the test temperature is 25 ℃.
The results of performance tests of the batteries assembled with the negative electrode tabs of examples 1 to 6 and comparative examples 1 to 3 are shown in table 1.
TABLE 1
From the data analysis of table 1:
(1) The assembled batteries of the negative electrode tabs prepared in examples 1-6 are shown in the data in table 1: the initial specific discharge capacity is higher than 3200mAh/g, the specific discharge capacity of the battery is still higher than 2750mAh/g after 100 circles of charge and discharge cycles, and the capacity retention rate is also higher than 85%; and can be derived from fig. 3: the silicon nanowire prepared in the embodiment 1 can still keep the nanowire structure after being circularly charged and discharged for 100 circles, which proves that the nanowire obtained by the preparation method has high structural stability; meanwhile, the battery assembled by the negative electrode plate obtained by the preparation method provided by the invention has excellent cycle stability as further proved by the figure 4. Therefore, the negative electrode plate obtained by the preparation method provided by the invention can effectively inhibit the volume expansion of silicon in the lithium removal and intercalation process, so that the battery can have excellent multiplying power charge and discharge performance, cycle performance and safety performance.
(2) The battery assembled with the negative electrode sheet prepared in comparative example 1 has a first discharge specific capacity lower than that of example 1, and its discharge specific capacity is only 1250mAh/g after 50 cycles of charge and discharge, its capacity retention rate has been reduced to 50%, whereas the discharge specific capacity of example 1 after 100 cycles of charge and discharge is 2781mAh/g, the capacity retention rate can still reach 85.3%, i.e., the battery cycle performance of comparative example 1 is far lower than that of example 1, because of the simultaneous addition of the first conductive agent, binder cement, second conductive agent and thickener in comparative example 1, resulting in poor conductivity of the obtained negative electrode sheet.
(3) The battery assembled by the negative electrode sheet prepared in comparative example 2 has a lower specific capacity for initial discharge, a specific capacity for discharge after 100 cycles of charge and discharge and a lower capacity retention rate than those of example 1, and the battery assembled by the negative electrode sheet prepared in comparative example 3 has a lower specific capacity for initial discharge than those of example, and has a specific capacity for discharge of only 1360mAh/g after 50 cycles of charge and discharge, the capacity retention rate of which is reduced to 80%, whereas the specific capacity for discharge of example 1 after 100 cycles of charge and discharge is 2781mAh/g, the capacity retention rate still can reach 85.3%, i.e., the overall performance of the batteries of comparative example 2 and comparative example 3 is far lower than that of example 1, because the addition amount of silicon nanowires in comparative example 2 is too low and the addition amount of silicon nanowires in comparative example 3 is too high; therefore, the addition amount of the silicon nanowire is regulated and controlled to be within a proper range, so that the electrochemical performance of the negative electrode plate can be effectively improved, and the electrochemical performance of the battery is further improved.
The applicant declares that the above is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be apparent to those skilled in the art that any changes or substitutions that are easily conceivable within the technical scope of the present invention disclosed by the present invention fall within the scope of the present invention and the disclosure.

Claims (10)

1. The preparation method of the negative electrode plate is characterized by comprising the following steps:
mixing a silicon nanowire with a first solvent, sequentially adding a first conductive agent, an adhesive, a second conductive agent and a thickening agent to obtain negative electrode slurry, and coating the negative electrode slurry on the surface of a current collector to obtain a negative electrode plate;
the total mass fraction of the solid raw materials of the cathode slurry is 100wt%, and the addition amount of the silicon nanowires is 60-85 wt%.
2. The method of claim 1, wherein the process of preparing the silicon nanowires comprises:
evaporating a silicon source for the first time to obtain silicon vapor, evaporating an aluminum source for the second time to obtain aluminum vapor, and then introducing the silicon vapor into the aluminum vapor for reaction to obtain the silicon nanowire;
preferably, the purity of the silicon source is greater than or equal to 95%;
preferably, the silicon source comprises any one or a combination of at least two of silicon powder, silicon block, silicon dioxide or silicon oxide;
preferably, the temperature of the primary evaporation is 1600-2000 ℃.
3. The method of claim 2, wherein the aluminum source comprises any one or a combination of at least two of aluminum plate, aluminum powder, or aluminum wire;
preferably, the surface of the aluminum source contains a plating layer;
preferably, the material of the plating layer comprises gold and/or silver;
preferably, the temperature of the secondary evaporation is 500-800 ℃;
preferably, the secondary evaporation is performed in an argon atmosphere;
preferably, the silicon vapor is introduced into the aluminum vapor at a rate of 2 to 5 g/min;
preferably, the temperature of the reaction is 500-800 ℃;
preferably, the reaction time is 1 to 5 hours;
preferably, the silicon nanowires have a diameter < 200nm and a length > 100 μm.
4. A method of preparation according to any one of claims 1 to 3, wherein the first solvent comprises water and/or ethanol;
preferably, the mixing time of the silicon nanowire and the first solvent is 10-60 min;
preferably, the silicon nanowires and the first solvent are mixed under milling conditions;
preferably, the first conductive agent, the adhesive, the second conductive agent and the thickener are sequentially added under stirring;
preferably, the stirring speed is 100-300 rpm/min;
preferably, after the first conductive agent, the adhesive, the second conductive agent and the thickener are sequentially added, stirring is continued for 30 to 120 minutes.
5. The production method according to any one of claims 1 to 4, wherein the addition amount of the first conductive agent is 1 to 15% by weight based on 100% by weight of the total mass fraction of the solid raw material of the negative electrode slurry;
preferably, the total mass fraction of the solid raw materials of the negative electrode slurry is 100wt%, and the addition amount of the binder is 5-20 wt%;
preferably, the addition amount of the second conductive agent is 0.5 to 5wt% based on 100wt% of the total mass fraction of the solid raw material of the negative electrode slurry;
preferably, the thickener is added in an amount of 2 to 8wt% based on 100wt% of the total mass fraction of the solid raw material of the negative electrode slurry.
6. The method of any one of claims 1 to 5, wherein the first conductive agent comprises any one or a combination of at least two of conductive carbon black, acetylene black, carbon fiber, or conductive graphene;
preferably, the adhesive is mixed with a second solvent to prepare an adhesive glue solution, and after the silicon nanowires are mixed with the first solvent, the first conductive agent, the adhesive glue solution, the second conductive agent and the thickener are sequentially added to obtain the negative electrode slurry;
preferably, the solid content of the adhesive glue solution is 4-6wt%;
preferably, the binder comprises any one or a combination of at least two of styrene butadiene rubber, polyethylene glycol or polyvinyl acetate;
preferably, the second solvent comprises water and/or ethanol;
preferably, the second conductive agent is dispersed in a third solvent to form second conductive agent slurry, and after the silicon nanowire and the first solvent are mixed, the first conductive agent, the adhesive glue solution, the second conductive agent slurry and the thickener are sequentially added to obtain the negative electrode slurry;
preferably, the solid content of the second conductive agent slurry is 0.2 to 0.6wt%;
preferably, the second conductive agent includes carbon nanotubes;
preferably, the thickener comprises any one or a combination of at least two of sodium carboxymethyl cellulose, hydroxypropyl cellulose, hydroxyethyl cellulose, hydroxypropyl methylcellulose or polyvinylpyrrolidone;
preferably, the viscosity of the negative electrode slurry is 1000-3000 cp;
preferably, the solid content of the negative electrode slurry is 6 to 8wt%.
7. The method of any one of claims 1-6, further comprising:
coating the negative electrode slurry on the surface of the current collector, and then drying to form a slurry coating on the surface of the current collector to obtain the negative electrode plate;
preferably, the temperature of the drying treatment is 70-90 ℃;
preferably, the drying treatment time is 60-240 min;
preferably, the thickness of the slurry coating is 150-250 μm;
preferably, after the slurry coating is formed on the surface of the current collector, rolling and cutting are sequentially performed to obtain the negative electrode plate.
8. A negative electrode sheet, characterized in that the negative electrode sheet comprises a current collector and a slurry coating on the surface of the current collector, and the negative electrode sheet is prepared by the preparation method of any one of claims 1 to 7.
9. The negative electrode piece according to claim 8, wherein the mass fraction of the silicon nanowires in the slurry coating is 60-85 wt% with the total mass of the slurry coating being 100 wt%;
preferably, the mass fraction of the first conductive agent in the slurry coating is 1-15 wt% based on 100wt% of the total mass of the slurry coating;
preferably, the mass fraction of the binder in the slurry coating is 5-20 wt% based on 100wt% of the total mass of the slurry coating;
preferably, the mass fraction of the second conductive agent in the slurry coating is 0.5-5 wt% based on 100wt% of the total mass of the slurry coating;
preferably, the mass fraction of the thickener in the slurry coating is 2 to 8wt% based on the total mass of the slurry coating being 100 wt%.
10. A lithium ion battery comprising the negative electrode tab of claim 8 or 9.
CN202210718975.2A 2022-06-23 2022-06-23 Negative electrode plate and preparation method and application thereof Pending CN117334840A (en)

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