CN109088070B - Lithium ion battery and preparation method thereof - Google Patents

Lithium ion battery and preparation method thereof Download PDF

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CN109088070B
CN109088070B CN201810790776.6A CN201810790776A CN109088070B CN 109088070 B CN109088070 B CN 109088070B CN 201810790776 A CN201810790776 A CN 201810790776A CN 109088070 B CN109088070 B CN 109088070B
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copper
aluminum
wires
lithium ion
plastic composite
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CN109088070A (en
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高回春
张誉
阮乐祥
宫宝昌
袁中直
刘金成
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Eve Energy Co Ltd
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Eve Energy 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
    • H01M4/64—Carriers or collectors
    • H01M4/70—Carriers or collectors characterised by shape or form
    • H01M4/72—Grids
    • H01M4/74—Meshes or woven material; Expanded metal
    • H01M4/747—Woven material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
    • 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
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/661—Metal or alloys, e.g. alloy coatings
    • 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
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/665—Composites
    • H01M4/667—Composites in the form of layers, e.g. coatings
    • 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
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

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  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
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Abstract

A preparation method of a lithium ion battery comprises the steps of weaving a fine soft copper wire and a first polymer fiber wire into a copper-plastic composite mesh, depositing copper metal on the copper-plastic composite mesh by adopting a physical vapor deposition process to obtain a composite copper foil, and coating negative electrode slurry on the composite copper foil to obtain a negative electrode sheet; weaving the fine and soft aluminum wires and the second high polymer fiber wires into an aluminum-plastic composite mesh cloth, depositing aluminum metal on the aluminum-plastic composite mesh cloth by adopting a physical vapor deposition process to obtain a composite aluminum foil, and coating the positive electrode slurry on the composite aluminum foil to obtain a positive plate; and then winding the negative plate, the insulating diaphragm and the positive plate to obtain an electric core, and performing shell entering, liquid injection, formation and capacity grading operations on the electric core to obtain the lithium ion battery.

Description

Lithium ion battery and preparation method thereof
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to a lithium ion battery and a preparation method thereof.
Background
Lithium ion batteries are batteries using a nonaqueous electrolyte solution and using lithium metal or a lithium alloy as a negative electrode material. Lithium ion batteries have the advantages of high energy density, high working voltage, long cycle life, low self-discharge, no memory effect, good safety performance and the like, are widely applied to power supplies of mobile phones, computers, video cameras, cameras and the like, and have important roles in the fields of electric automobile technology, energy storage batteries of large power plants, UPS power supplies, medical instrument power supplies and the like. With the increasing prosperity of electronic consumer products, the market demand for lithium ion batteries is rapidly increased, and the performance requirements for lithium ion batteries are higher and higher. The energy density refers to the amount of energy stored in a certain space or mass, the battery energy density refers to the electric energy released by the average unit volume or mass of the battery, and the battery energy density is the battery capacity × the discharge plateau/battery weight.
The base material used by the negative electrode in the current lithium ion battery is copper foil which is formed by adopting an electroplating or extrusion mode, the thickness of the copper foil is 6 um-12 um, and the surface density of the copper foil is 54g/m2～108g/m2The weight of the copper foil is only second to that of the anode and cathode powder in the lithium ion battery, and is approximately 6-20%. The base material used for the anode is aluminum foil which is formed by adopting a rolling way, the thickness of the aluminum foil is 10 um-16 um, and the surface density of the aluminum foil is 27g/m2～43.2g/m2The weight of the aluminum foil accounts for about 5% to 10% of the weight of the lithium ion battery, and particularly, the weight of the aluminum foil is very large in a large-sized power battery.
In the field of digital or power batteries, copper foils and aluminum foils belong to auxiliary materials in the whole lithium ion battery, and the copper foils and the aluminum foils mainly play a role in conducting electrons. However, in the present day in which energy density is highly pursued, the weight occupied by the copper foil and the aluminum foil is a great obstacle to the improvement of the energy density of the lithium ion battery. By reducing the weight of the auxiliary materials, the energy density of the lithium ion battery is improved.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide a lithium ion battery and a preparation method thereof, and the lithium ion battery with higher energy density and better cycle stability can be prepared.
The purpose of the invention is realized by the following technical scheme:
the preparation method of the lithium ion battery comprises the following steps:
providing a thin and soft copper wire and a first polymer fiber wire;
weaving the fine soft copper wires and the first polymer fiber wires into a copper-plastic composite mesh, taking copper metal as a target material and the copper-plastic composite mesh as a base material, and depositing the copper metal on the copper-plastic composite mesh by adopting a physical vapor deposition process to obtain a composite copper foil;
coating the negative electrode slurry on the composite copper foil, and performing drying, cold pressing, stripping and slicing operations to obtain a negative electrode sheet;
providing a fine and soft aluminum filament and a second high polymer fiber filament;
weaving the fine and soft aluminum wires and the second high polymer fiber wires into an aluminum-plastic composite mesh cloth, taking aluminum metal as a target material and the aluminum-plastic composite mesh cloth as a base material, and depositing the aluminum metal on the aluminum-plastic composite mesh cloth by adopting a physical vapor deposition process to obtain a composite aluminum foil;
coating the positive electrode slurry on the composite aluminum foil, and performing drying, cold pressing, slitting and slicing operations to obtain a positive electrode plate;
winding the negative plate, the insulating diaphragm and the positive plate to obtain a battery core;
and placing the battery core in a shell, injecting electrolyte, and performing formation and grading operation to obtain the lithium ion battery.
In one embodiment, the first polymer fiber is polyethylene terephthalate fiber, polyamide fiber, polyimide fiber, polyvinylidene fluoride fiber, or aramid fiber.
In one embodiment, the weaving mode of the copper-plastic composite mesh cloth adopts a plain weaving mode.
In one embodiment, in the plain weaving mode of the copper-plastic composite mesh cloth, the warp yarns are all first polymer fiber yarns, and the weft yarns are a plurality of fine soft copper wires and a plurality of first polymer fiber yarns alternately arranged at intervals.
In one embodiment, the weaving mode of the aluminum-plastic composite mesh cloth adopts a plain weaving mode.
In one embodiment, in the plain weaving manner of the aluminum-plastic composite mesh cloth, the warp yarns are all the second polymer fiber yarns, and the weft yarns are a plurality of fine soft aluminum yarns and a plurality of second polymer fiber yarns alternately arranged at intervals.
In one embodiment, the length direction of the negative plate is the same as that of the thin soft copper wire.
In one embodiment, the length direction of the positive plate is the same as the length direction of the thin and soft aluminum wires.
In one embodiment, the length direction of the insulating separator is the same as the length direction of the negative electrode sheet and the length direction of the positive electrode sheet.
A lithium ion battery is prepared by the preparation method of the lithium ion battery.
According to the preparation method of the lithium ion battery, the fine soft copper wires and the first high polymer fibers are woven into the copper-plastic composite mesh cloth, the copper metal is deposited on the copper-plastic composite mesh cloth by adopting a physical vapor deposition process to obtain a composite copper foil, and the negative electrode slurry is coated on the composite copper foil to obtain a negative electrode sheet; weaving the fine and soft aluminum wires and the second high polymer fiber wires into an aluminum-plastic composite mesh cloth, depositing aluminum metal on the aluminum-plastic composite mesh cloth by adopting a physical vapor deposition process to obtain a composite aluminum foil, and coating the positive electrode slurry on the composite aluminum foil to obtain a positive plate; and then winding the negative plate, the insulating diaphragm and the positive plate to obtain an electric core, and performing shell entering, liquid injection, formation and capacity grading operations on the electric core to obtain the lithium ion battery.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
Fig. 1 is a flow chart illustrating steps of a method for manufacturing a lithium ion battery according to an embodiment of the present invention;
fig. 2 is a schematic plan view of a copper-plastic composite mesh of a lithium ion battery according to an embodiment of the present invention.
Detailed Description
To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and the like as used herein are for illustrative purposes only and do not represent the only embodiments.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
Referring to fig. 1, a flow chart of steps of a method for manufacturing a lithium ion battery according to an embodiment includes the following steps:
s110, providing a fine soft copper wire and a first polymer fiber.
The copper-plastic composite mesh cloth can be obtained by providing the thin and soft copper wires and the first high polymer fibers, and is favorable for subsequent weaving, the copper-plastic composite mesh cloth is moderate in hardness and high in flexibility, is not easy to break in the weaving process, and is convenient to bend or wind in the subsequent using process, so that the subsequent preparation of the lithium ion battery with better performance is facilitated.
In order to improve the flexibility of the copper-plastic composite mesh cloth, for example, the wire diameter of the thin and soft copper wire is 0.08 mm-0.6 mm. The method has the advantages that the wire diameter of the fine soft copper wire has a great influence on the flexibility of the prepared copper-plastic composite mesh cloth, when the wire diameter of the fine soft copper wire is too large, the hardness of the fine soft copper wire is too large, the weaving difficulty of the copper-plastic composite mesh cloth is easily increased, and meanwhile, the thickness and the weight of the subsequently woven copper-plastic composite mesh cloth are increased, so that the preparation of the lithium ion battery with higher energy density is influenced; however, if the wire diameter of the fine soft copper wire is too small, the fine soft copper wire may be excessively stretched and broken in the process of weaving the copper-plastic composite mesh cloth, so that through multiple experimental analysis and verification, the copper-plastic composite mesh cloth more suitable for the lithium ion battery can be obtained by weaving the fine soft copper wire with the wire diameter of 0.08mm to 0.6mm, for example, the wire diameter of the fine soft copper wire is 0.1mm to 0.5mm, and thus, the lithium ion battery with better performance is obtained by subsequent preparation.
In one embodiment, the first polymer fiber is polyethylene terephthalate fiber, polyamide fiber, polyimide fiber, polyvinylidene fluoride fiber, or aramid fiber.
In order to improve the mechanical property and the chemical corrosion resistance of the woven copper-plastic composite mesh cloth, for example, the first polymer fiber yarns are polyethylene terephthalate fiber yarns. It is understood that polyethylene terephthalate, abbreviated as Polyester (PET), is obtained by the exchange of dimethyl terephthalate with ethylene glycol or by the esterification of terephthalic acid with ethylene glycol, first of all by synthesis of bishydroxyethyl terephthalate, and then by polycondensation. The polyethylene terephthalate has excellent physical and mechanical properties and electrical properties, and even at high temperature and high frequency, the electrical properties are still good, and in addition, the polyethylene terephthalate has ester bonds, is resistant to organic electrolytes, and has excellent weather resistance. So, adopt polyethylene glycol terephthalate cellosilk to weave copper and mould compound screen cloth, can make the compound screen cloth of copper moulding that obtains have good physical and mechanical properties, for example, have good mechanical properties, impact strength is 4 ~ 7 times of other films, folding endurance and antifriction are good, the organic electrolyte of lithium ion battery inside very resistant simultaneously, thereby it is better to be favorable to follow-up preparation to obtain folding endurance and resistant organic electrolyte, and more frivolous compound copper foil, and then do benefit to follow-up preparation and obtain the lithium ion battery that the performance is more excellent. For another example, the first polymer fiber yarn is a polyamide fiber yarn, and it can be understood that polyamide is commonly called polyamide, is a generic name of thermoplastic resin containing repeated amide groups on a molecular main chain, and has good mechanical strength and self-lubricating property, and a copper-plastic composite mesh fabric woven by using the polyamide fiber yarn has good comprehensive properties including mechanical properties, heat resistance, abrasion resistance, chemical resistance and self-lubricating property. For another example, the first polymer fiber yarn is a polyimide fiber yarn, and it can be understood that the polyimide fiber yarn has the characteristics of good chemical corrosion resistance, high strength and high modulus, large specific surface area and the like, so that the mechanical strength and the organic electrolyte resistance of the woven copper-plastic composite mesh fabric can be better. If the first polymer fiber is polyvinylidene fluoride fiber, the polyvinylidene fluoride fiber has excellent chemical corrosion resistance and wear resistance and high impact strength, so that the organic electrolyte resistance of the copper-plastic composite mesh cloth obtained by weaving can be realized, the impact strength is better, and the subsequent preparation is facilitated to obtain the composite copper foil with better performance. For another example, the first polymer fiber yarn is an aramid fiber yarn, and it can be understood that aramid fiber is also called benzenedicarboxamide, which is a novel high-tech synthetic fiber, and has excellent properties of ultra-high strength, high modulus, high temperature resistance, acid and alkali resistance, light weight, aging resistance, long life cycle, etc., so that the copper-plastic composite mesh fabric woven by the aramid fiber yarn can have the characteristics of good acid and alkali resistance, especially light weight. The weight of the polyethylene terephthalate fiber yarn, the polyamide fiber yarn, the polyimide fiber yarn, the polyvinylidene fluoride fiber yarn and the aramid fiber yarn is smaller than that of a metal material, and the polyethylene terephthalate fiber yarn, the polyamide fiber yarn, the polyimide fiber yarn, the polyvinylidene fluoride fiber yarn and the aramid fiber yarn are used as preparation raw materials of the lithium ion battery, so that the weight of the prepared lithium ion battery is greatly reduced, the energy density of the lithium ion battery can be further improved, and the preparation cost is reduced.
S120, weaving the fine soft copper wires and the first polymer fiber wires into a copper-plastic composite mesh, taking copper metal as a target material, taking the copper-plastic composite mesh as a base material, and depositing the copper metal on the copper-plastic composite mesh by adopting a physical vapor deposition process to obtain the composite copper foil.
The copper-plastic composite mesh cloth woven by the thin soft copper wires and the first high polymer fibers is used as a base material, copper metal is used as a target material, and the copper metal is deposited on the copper-plastic composite mesh cloth by adopting a physical vapor deposition process, so that the composite copper foil can be obtained.
In one embodiment, the weaving mode of the copper-plastic composite mesh cloth adopts a plain weaving mode.
It can be understood that the way of weaving the copper wires into the net is more than one, meshes with different shapes and net diameters can be obtained by adopting different weaving ways, and the mobility and the weight of the composite copper foil prepared by lithium ions in the subsequent process can be influenced to a certain extent. For example, the fine soft copper wires and the first polymer fibers are woven into the copper-plastic composite mesh cloth in a plain weave manner. It is understood that the plain weave is a weave in which each warp yarn crosses over each weft yarn, the warp yarns are as thick as the weft yarns, and the warp yarns and the weft yarns form an angle of 90 degrees. So, can make the precision of the compound screen cloth of copper moulding of weaving more even stable, and have good surface smoothness, do benefit to follow-up better deposit copper metal, if again, the mesh number scope of the compound screen cloth of copper moulding is 50 ~ 100 meshes, the aperture scope of the compound screen cloth of copper moulding is 0.2mm ~ 2mm, so, the migration rate that more is favorable to the lithium ion in the lithium ion battery that follow-up preparation obtained is higher, and then is favorable to improving lithium ion battery's capacity and energy density.
Referring to fig. 2, in order to improve the stretch-proof and bending-resistant properties of the copper-plastic composite mesh cloth, for example, the warp threads of the copper-plastic composite mesh cloth 10 obtained by plain weaving are all the first polymer fiber threads 100, and the weft threads are a plurality of fine soft copper wires 200 and a plurality of first polymer fiber threads 100 alternately arranged at intervals. The first polymer fiber 100 has the characteristics of good mechanical property, high impact resistance, strong organic electrolyte resistance and light weight, so that the warp yarns are the first polymer fiber 100, the copper-plastic composite mesh fabric 10 has better mechanical property, in the subsequent use process, the tensile strength and the bending resistance are better, and especially the weight of the copper-plastic composite mesh fabric 10 can be reduced, so that the weight of the composite copper foil obtained by subsequent preparation can be reduced, and it can be understood that the battery energy density refers to the electric energy released by the average unit volume or mass of the battery, and by reducing the weight of the prepared lithium ion electron auxiliary material, the lithium ion battery with smaller weight can be prepared, and the energy density of the lithium ion battery can be further improved; further, the tram silk of compound screen cloth 10 is many thin soft copper wires 200 and many first polymer fiber 100 intervals in turn setting up, can understand, the compliance of thin soft copper wire 200 is higher, easily buckle, so, set up many thin soft copper wires 200 and many first polymer fiber 100 intervals in turn and weave compound screen cloth 10 is moulded to the copper as the tram silk, can satisfy the compound screen cloth 10 of copper moulding and have good compliance and resistant bending nature in, still possess good metallic property, change the shaping, when subsequently preparing into the negative pole piece, can more be applicable to practical application. It should be further noted that a plurality of fine soft copper wires 200 and a plurality of first polymer fiber wires 100 are alternately arranged at intervals to serve as weft wires, and then the first polymer fiber wires 100 cross each weft wire up and down to form a 90-degree weaving mode, so that the copper-plastic composite mesh cloth 10 with more uniform meshes, higher stability and good surface flatness can be obtained by weaving, and further, the copper metal is more favorably deposited on the copper-plastic composite mesh cloth 10 in the follow-up process, and a composite copper foil with better performance is obtained.
To obtain better conductivity and adhesionThe composite copper foil uses copper metal as a target material, uses the copper-plastic composite mesh cloth as a base material, and adopts a physical vapor deposition process to deposit the copper metal on the copper-plastic composite mesh cloth to obtain the composite copper foil. It is understood that the pvd process is a process of vaporizing a solid or liquid material source surface into gaseous atoms, molecules or partially ionized ions by a physical method under vacuum, and depositing a thin film having a certain specific function on a substrate surface by a low pressure gas or plasma process, and the pvd process can deposit not only a metal film, an alloy film, but also a compound, a ceramic, a semiconductor, a polymer film, etc. For example, the physical vapor deposition process is a vacuum evaporation method. It is understood that vacuum evaporation means that metal, metal alloy or compound is evaporated under vacuum condition and then deposited on the surface of the substrate, and the evaporation method is commonly used as resistance heating, high frequency induction heating, electron beam, laser beam or ion beam high energy bombardment plating material, so that metal, metal alloy or compound is evaporated into gas phase and then deposited on the surface of the substrate to form a film. For example, in this embodiment, the aluminum metal is deposited on the aluminum-plastic composite mesh cloth by a vacuum evaporation method, which specifically includes the following steps: s121, carrying out ultrasonic cleaning on the copper-plastic composite mesh cloth; s122, charging copper metal into a furnace in a vacuum evaporation plating machine; s123, adjusting the vacuum degree of the vacuum chamber to 3 x 10-3Pa～6×10-3Pa; s124, performing vacuum evaporation operation; and S125, cooling and taking out the composite copper foil. For example, the copper-plastic composite mesh cloth is subjected to ultrasonic cleaning at the working temperature of 45-65 ℃ and the cleaning frequency of 28-45 KHz; for another example, the evaporation distance is 9 cm-17 cm, the evaporation current is 350A-450A, and the evaporation voltage is 2V-9V; for another example, the evaporation time is 20min to 30 min; therefore, the obtained composite copper foil has better conductivity and adhesive force, uniform and compact plating layer structure, good oxidation resistance, particularly more light and thin composite copper foil, is favorable for subsequent better adhesion with negative electrode slurry, obtains a negative electrode sheet with stronger cohesiveness and higher stability, and is further favorable for subsequent preparation to obtain a lithium ion battery with higher energy density.
To obtain energyThe high-performance composite copper foil with higher electron mobility and lighter weight can be obtained, for example, the physical vapor deposition process is a magnetron sputtering mode, the copper metal is deposited on the copper-plastic composite mesh cloth in the magnetron sputtering mode, and the composite copper foil with better performance can be obtained. It can be understood that magnetron sputtering utilizes the characteristic that ions with charges have certain kinetic energy after being accelerated in an electric field, and leads the ions to a substance to be sputtered (sputtering target material) to be used as a target electrode (cathode). Under the condition of proper ion energy, the incident ions collide with atoms on the surface of the target to sputter the atoms on the surface of the target, and the sputtered atoms have certain kinetic energy and fly along a certain direction to be jetted to the substrate and deposited on the substrate, so that the formation of the thin film is realized. In the magnetron sputtering process, argon gas is generally firstly input into a vacuum chamber, and electrons collide with argon atoms in the process of flying to a substrate under the action of an electric field E so as to ionize the argon atoms to generate argon ions and new electrons. The argon ions are accelerated to fly to the cathode target under the action of a magnetic field and an electric field, and bombard the surface of the target at high energy, so that the target is sputtered. In this embodiment, argon gas is introduced into the vacuum chamber, the copper-plastic composite mesh is used as a substrate, copper metal is sputtered onto the copper-plastic composite mesh in a magnetron sputtering manner, and the copper metal is deposited on the copper-plastic composite mesh to form the composite copper foil. In order to obtain a composite copper foil with better performance, for example, the copper content of the copper metal is more than 99.5%, so that the deposition rate of the copper metal on the composite copper foil can be improved, and the composite copper foil with higher copper content and better continuity is formed; for example, the thickness of the composite copper foil is 2-5 μm, so that the prepared composite copper foil is lighter, thinner and softer, and is convenient for later winding and the like, and the weight of the composite copper foil can be reduced, so that the negative electrode sheet with smaller weight is prepared, and the energy density of the prepared lithium ion battery is improved. And for another example, sputtering copper metal onto the copper-plastic composite mesh cloth by adopting sputtering power of 40-100W to obtain the composite copper foil. It can be understood that the influence of the sputtering power on the formed thin film structure is large, and the kinetic energy of the sputtered particles is small when the sputtering power is smallThe probability of surface diffusion migration and recrystallization is small, and the film grain size is small. With the increase of the sputtering power, the sputtering rate is increased, that is, under the same sputtering time condition, the number of sputtered particles under high power is more, the probability of direct collision nucleation among the particles is increased, in addition, the energy of the sputtered particles is increased, the diffusion rate of the sputtered particles on the substrate is increased due to high energy, the particles are combined with each other to form grains with larger size, the compactness of the film is improved, and the crystal structure is further optimized. However, if the sputtering power is too large, the structure of the copper-plastic composite mesh cloth is easily damaged, so that the formation of the thin film is affected, or the thickness uniformity of the thin film is affected, so that through multiple experimental analysis, the sputtering power of 40W-100W is adopted to sputter copper metal onto the copper-plastic composite mesh cloth, so that more copper metal can be fixed on the copper-plastic composite mesh cloth, and a composite copper foil with better compactness is formed. In order to prepare the composite copper foil with larger capacity and better cycling stability, for example, when copper metal is sputtered on the copper-plastic composite mesh cloth, the sputtering time is 2-4 h, for example, the pressure of argon is 0.4-1.0 Pa during sputtering, the flow rate of argon is 35-60 sccm, and for example, the vacuum degree of a vacuum chamber is 1.0 multiplied by 10-5Pa～1.0×10-4Pa, the composite copper foil obtained by sputtering can thus be made to have a larger capacity and better cycle stability.
In order to obtain a high-performance composite copper foil which can make the electron mobility higher and lighter, the surface density of copper metal in the composite copper foil is 15g/m2～30g/m2. It can be understood that the battery energy density refers to the electric energy released by the average unit volume or mass of the battery, and the weight of the copper foil of the existing lithium ion battery accounts for a larger proportion in the lithium ion battery, which is only next to the positive and negative electrode powder materials, and is approximately 6% -20%, so that the weight of the battery is larger, and the energy density of the lithium ion battery is reduced. Thus, in order to reduce the weight of the battery, the areal density of copper metal in the composite copper foil in this example was 15g/m2～30g/m2Thus, under the condition of not influencing the good performance of the lithium ion battery,the weight of the lithium ion battery is further reduced, and the energy density of the lithium ion battery is further improved. For example, the areal density of copper metal in the composite copper foil is 17g/m2～25g/m2Thus, the energy density of the prepared lithium ion battery can be higher.
And S130, coating the negative electrode slurry on the composite copper foil, and performing drying, cold pressing, stripping and slicing operations to obtain the negative electrode plate.
The negative pole slurry is coated on the composite copper foil, and the negative pole piece of the lithium ion battery can be obtained through drying, cold pressing, stripping and slicing operations.
In order to improve the adhesion between the negative electrode slurry and the composite copper foil and make the negative electrode slurry not easy to fall off, for example, the composite copper foil is subjected to pre-etching operation, which specifically comprises the following steps: the surface of the composite copper foil is subjected to rust removal operation, and the composite copper foil is soaked in oxalic acid solution for pre-corrosion treatment. It can be understood that the composite copper foil is exposed in the air, and oil stains or rusts are easily present on the surface of the composite copper foil, so that the adhesion tightness of the composite copper foil and the negative electrode slurry is affected, and even the negative electrode slurry is easily peeled off. In order to improve the adhesion between the composite copper foil and the negative electrode slurry, the composite copper foil is soaked in oxalic acid solution for pre-corrosion treatment, so that the roughness of the surface of the composite copper foil can be improved. For example, the composite copper foil is soaked in oxalic acid solution for 2-8 min, if the oxalic acid solution has a mass concentration of 5-10%, and if the pre-corrosion treatment temperature is controlled to be 40-80 ℃, so that the pre-corrosion effect of the composite copper foil is better, meanwhile, the surface roughness of the composite copper foil is higher, the specific surface area is increased, and after the negative electrode slurry is coated, the adhesion between the surface of the composite copper foil and the negative electrode slurry is stronger, so that the negative electrode plate is prevented from being locally or even largely dropped in the subsequent cold pressing, strip dividing and slicing operation processes, and the qualification rate of the prepared lithium ion battery is improved.
In order to improve the conductivity of the negative plate, for example, the negative electrode slurry comprises a negative electrode active material, a pore-forming agent, a conductive agent, a binder and a solvent, wherein the mass ratio of the negative electrode active material, the pore-forming agent, the conductive agent, the binder and the solvent is (90-96): (2-6): (2-4): (3-6): (75-90), mixing and stirring the negative electrode active material, the pore-forming agent, the conductive agent, the adhesive and the solvent to obtain negative electrode slurry. And coating the negative electrode slurry on the composite copper foil, and performing drying, cold pressing, stripping and slicing operations to obtain the negative electrode plate. It can be understood that the performance of the electrode slurry has an important influence on the performance of the lithium ion battery, the more uniformly the components in the electrode slurry are dispersed, the better the processability of the electrode sheet is, the more uniformly the impedance distribution at each part of the electrode sheet is, and the more the function of the active material can be exerted during charging and discharging, so that the performance of the lithium ion battery is better. For example, a dispersant is further added during the mixing and stirring of the negative electrode active material, the pore-forming agent, the conductive agent, the binder and the solvent, thus, the components in the mixed system can be mixed more uniformly, the problem of agglomeration or caking is avoided, for example, the dispersant is at least one of carboxymethyl cellulose and sodium hexametaphosphate, so that the negative electrode active material, the pore-forming agent, the conductive agent, the binder and the solvent can be dispersed more uniformly, so as to obtain the cathode slurry with more uniformly dispersed components after mixing and stirring, for example, the stirring speed of 650-900 r/min is adopted, and stirring the negative active material, the pore-forming agent, the conductive agent, the adhesive and the solvent, so that the subsequent preparation is facilitated to obtain the lithium ion battery with better performance. For another example, the negative electrode active material is at least one of artificial graphite, natural graphite, hard carbon, silicon carbon, graphene, and lithium titanate. It can be understood that the negative active material is an important component of the lithium ion battery, and directly influences key indexes of the battery, such as energy density, cycle life and safety performance. In order to improve the capacity and cycle durability of the lithium ion battery, for example, the negative active material is lithium titanate, which has the characteristics of high safety, high stability, long service life and environmental friendliness, and the lithium titanate is used as the negative active material of the lithium ion battery, so that the prepared lithium ion battery has higher safety performance, higher stability and more cycle times; for another example, the negative active material is silicon carbon, and it can be understood that the nano silicon powder has the characteristics of high purity, small particle size, uniform distribution, large specific surface area, high surface activity, low apparent density and the like, and is non-toxic and tasteless, so that the capacity of the lithium ion battery can be improved, and the energy density of the lithium ion battery can be further improved.
After the negative electrode slurry is coated on the composite copper foil, drying, cold pressing, slitting and slicing operations are required to obtain the negative electrode sheet. It can be understood that in the process of coating the negative electrode slurry on the composite copper foil, if the ambient humidity is high, the negative electrode slurry is easy to absorb moisture in the environment, so that the viscosity of the negative electrode slurry is gradually increased, the fluidity and the uniform state of the negative electrode slurry are damaged, the coating surface density of the negative electrode slurry is unstable, the coating appearance is rough, the internal resistance of a pole piece is high, or the cohesiveness of the pole piece coating is poor, the material is easy to fall in the subsequent operation process, and the performance of the lithium ion battery is affected; for example, the humidity of the negative electrode slurry is controlled within the range of 0% to 8% relative humidity during the coating process, so that the effect of coating the negative electrode slurry on the composite copper foil can be better. For another example, the drying operation is performed at a temperature of 40 ℃ to 120 ℃. For another example, the cold pressing speed of 7-45 m/min, the cold pressing pressure of 3-70 MP and the cold pressing gap of 60-1.0 mm are adopted to carry out cold pressing operation on the negative plate, so that the porosity of the negative plate can be improved, the formed pores are more uniform, and the charging capacity and the cycle capacity of the lithium ion battery are greatly improved under the condition of ensuring the durability of the negative plate. And then the negative pole pieces are subjected to slitting and cutting operation, so that the negative pole pieces with the required specifications can be obtained.
In this embodiment, the length direction of the negative electrode sheet is the same as the length direction of the fine soft copper wire. It can be understood that when the copper-plastic composite mesh cloth is woven by the fine soft copper wires and the first polymer fibers in a plain weave manner, the weft wires are a plurality of fine soft copper wires and a plurality of first polymer fibers alternately arranged at intervals, copper metal is deposited on the copper-plastic composite mesh cloth to obtain a composite copper foil, then negative slurry is coated on the composite copper foil for drying, cold pressing, splitting and slicing to obtain a negative plate, wherein the length direction of the negative plate is the same as that of the fine soft copper wires, so that the fine soft copper wires can better enhance the mechanical property of the negative plate, the stability and the bending resistance of the negative plate are stronger, particularly the rigidity of the fine soft copper wires can play a good role in supporting the inside of the negative plate, the overall structure of the negative plate is more stable, and the negative plate can be wound to obtain a battery core in the subsequent operation, the mechanical property of the battery cell is better, and the lithium ion battery with stronger stability is obtained by subsequent preparation.
And S140, providing the fine and soft aluminum filaments and the second high polymer filaments.
The thin and soft aluminum wires and the second high-molecular fiber wires can be beneficial to subsequent weaving to obtain the aluminum-plastic composite mesh cloth, so that the lithium-embedded capacity of aluminum is small, the electrochemical stability can be kept, the aluminum-plastic composite mesh cloth is suitable for serving as a positive current collector of a lithium ion battery, the thin and soft aluminum wires are stronger in flexibility than conventional aluminum materials, are not easy to break in the weaving process, and are convenient to bend or wind in the subsequent using process, and therefore the efficiency of subsequent preparation of the lithium ion battery is improved. In order to further improve the flexibility and the bending resistance of the woven aluminum-plastic composite mesh cloth, a second high polymer fiber yarn with stronger flexibility is also provided, for example, the second high polymer fiber yarn is a polyethylene terephthalate fiber yarn or a polyimide fiber yarn. It is understood that polyethylene terephthalate has excellent physical and mechanical properties and electrical properties, and the electrical properties are good even at high temperatures and high frequencies, and further, polyethylene terephthalate has ester bonds, is resistant to organic electrolytes, and is excellent in weather resistance. So, adopt the polyethylene glycol terephthalate cellosilk as the material of follow-up compound screen cloth of weaving aluminium-plastic, more enough make the compound screen cloth of aluminium-plastic who weaves the obtaining have good mechanical properties, folding endurance and antifriction, the organic electrolyte of lithium ion battery inside very resistant simultaneously to be favorable to follow-up preparation to obtain folding endurance and resistant organic electrolyte better, and more frivolous compound aluminium foil, and then do benefit to follow-up preparation and obtain the lithium ion battery that the performance is more excellent. The polyimide fiber has the characteristics of good chemical corrosion resistance, high strength and modulus, large specific surface area and the like, so that the mechanical strength and the organic electrolyte resistance of the woven aluminum-plastic composite mesh cloth are better.
S150, weaving the fine soft aluminum wires and the second high polymer fibers into an aluminum-plastic composite mesh, taking aluminum metal as a target material and the aluminum-plastic composite mesh as a base material, and depositing the aluminum metal on the aluminum-plastic composite mesh by adopting a physical vapor deposition process to obtain the composite aluminum foil.
It can be understood that the working principle of the lithium ion battery is that the chemical energy is converted into an electrochemical device of the electric energy, a medium is needed to transmit the electric energy converted from the chemical energy, so that the electric conducting material is needed, and meanwhile, in the process of preparing the lithium ion battery, procedures such as winding, laminating and the like are needed.
The aluminum-plastic composite mesh cloth woven by the fine soft aluminum wires and the second high polymer fibers is used as a base material, aluminum metal is used as a target material, and the aluminum metal is deposited on the aluminum-plastic composite mesh cloth by adopting a physical vapor deposition process, so that the composite aluminum foil can be obtained. In order to obtain the aluminum-plastic composite mesh cloth with better tensile resistance and bending resistance, for example, the aluminum-plastic composite mesh cloth is woven by a plain weave method. It can be understood that plain weave means that every warp silk crosses from top to bottom at every woof, and warp silk and woof are the same thickness, and warp and woof become the weaving mode at 90 degrees angles, so, can make the precision of the compound screen cloth of plastic-aluminum woven more even stable, and have good surface smoothness, do benefit to follow-up better deposit aluminium metal. Furthermore, in the plain weaving mode of the aluminum-plastic composite mesh cloth, the warp yarns are all second high polymer fiber yarns, and the weft yarns are a plurality of thin and soft aluminum yarns and a plurality of second high polymer fiber yarns alternately arranged at intervals. It can be understood that the second polymer fiber yarns are excellent in mechanical property, folding resistance and friction resistance and good in flexibility, and the second polymer fiber yarns are used as warp yarns for weaving the aluminum-plastic composite mesh fabric, so that the woven aluminum-plastic composite mesh fabric is stronger in flexibility and more resistant to stretching and bending. The plurality of fine and soft aluminum wires and the plurality of second polymer fibers are alternately arranged at intervals to be used as the weft wires for weaving the aluminum-plastic composite mesh cloth, and the rigidity of the fine and soft aluminum wires and the plasticity of the second polymer fibers can be combined, so that the aluminum-plastic composite mesh cloth is more moderate in hardness and can have higher applicability in subsequent winding and other processes, such as easier forming, for example, after being prepared into a battery cell, the aluminum-plastic composite mesh cloth can have a better supporting effect, and further the stability inside the lithium ion battery is improved; so, set up many soft aluminium silks of fineness and many second polymer fiber silk interval in turn as the woof, pass second polymer fiber silk crisscross about every woof again, become the weaving mode at 90 degrees angles, can weave and obtain the mesh more even, the aluminium-plastic composite mesh cloth that stability is higher and have good surface smoothness, and then more be favorable to follow-up with the aluminium metal deposit on the aluminium-plastic composite mesh cloth, obtain the better compound aluminium foil of performance, so, can reduce the migration impedance of lithium ion, more do benefit to and improve the migration rate of lithium ion in lithium ion battery inside, change the absorption electrolyte simultaneously, improve lithium ion battery's capacity, and then can prepare the lithium ion battery that obtains energy density is higher and circulation stability is higher.
To obtain better conductivity and adhesionAnd the good composite aluminum foil is prepared by using aluminum metal as a target material and the aluminum-plastic composite mesh cloth as a base material and depositing the aluminum metal on the aluminum-plastic composite mesh cloth by adopting a physical vapor deposition process. In order to obtain a composite aluminum foil with better quality, for example, the aluminum content of the aluminum metal is greater than 98%, so that the deposition rate of the aluminum metal on the composite aluminum foil can be improved, and the composite aluminum foil with higher aluminum content and better continuity can be formed. For another example, the physical vapor deposition process is a magnetron sputtering method, aluminum metal is used as a target material, the aluminum-plastic composite mesh fabric is used as a base material, and the aluminum metal is sputtered onto the aluminum-plastic composite mesh fabric to obtain the composite aluminum foil with excellent conductivity, or for another example, the aluminum metal is sputtered onto the composite aluminum foil by adopting a sputtering power of 50W to 100W to obtain the composite aluminum foil. It can be understood that the influence of the sputtering power on the formed film structure is large, when the sputtering power is small, the kinetic energy of the sputtered particles is small, the probability of surface diffusion migration and recrystallization is small, and the grain size of the film is small. With the increase of the sputtering power, the sputtering rate is increased, that is, under the same sputtering time condition, the number of sputtered particles under high power is more, the probability of direct collision nucleation among the particles is increased, in addition, the energy of the sputtered particles is increased, the diffusion rate of the sputtered particles on the substrate is increased due to high energy, the particles are combined with each other to form grains with larger size, the compactness of the film is improved, and the crystal structure is further optimized. However, if the sputtering power is too high, the structure of the composite aluminum foil is easily damaged, and the formation of the thin film is further affected, or the thickness uniformity of the thin film is affected, so that the aluminum metal is sputtered onto the composite aluminum foil by using the sputtering power of 50W to 100W, and the composite aluminum foil with higher compactness and better conductivity can be obtained. Further, for example, the sputtering time is 2 to 4 hours, the pressure is adjusted to 0.5 to 1.8Pa, the flow rate of argon is 30 to 45sccm, and the vacuum degree of the vacuum chamber is 1.5X 10-5Pa～2.0×10-4Pa, so that the composite aluminum foil obtained by sputtering has larger capacity and better cycle stability.
And S160, coating the positive electrode slurry on the composite aluminum foil, and performing drying, cold pressing, slitting and slicing operations to obtain the positive electrode plate.
The positive plate of the lithium ion battery can be obtained by coating the positive slurry on the composite aluminum foil and performing the operations of drying, cold pressing, slitting and slicing.
In order to improve the conductive performance of the positive electrode sheet, for example, the positive electrode slurry is prepared by mixing and stirring a positive electrode active material, a pore-forming agent, a conductive agent, a binder and a solvent. For another example, the positive electrode active material is at least one of lithium carbonate, lithium hydroxide, lithium acetate, lithium citrate, lithium oxalate, cobaltosic oxide, cobalt hydroxide, cobalt nitrate, cobalt acetate, aluminum nitrate, aluminum oxide, and aluminum sulfate. It can be understood that the positive electrode material is an important component of the lithium ion battery, and directly influences parameters such as the capacity and the cycle performance of the lithium ion battery. For example, the positive electrode active material is lithium hydroxide, and it can be understood that lithium hydroxide has the advantages of good stability and consistency as the positive electrode active material, the water-melting property and the decomposition temperature of lithium hydroxide are high, and carbon monoxide is not released in the sintering process and redox reaction does not occur, so that the prepared positive electrode plate has better stability and consistency. For another example, the pore-forming agent is at least one of ammonium bicarbonate, oxalic acid, ammonium oxalate, ammonium carbonate and ammonium nitrate, and it can be understood that the pore-forming agent can decompose the positive electrode slurry in the heating process to generate a large amount of bubbles, so that the positive electrode sheet of the lithium ion battery has higher porosity, and at the same time, the bonding strength between the positive electrode slurry and the composite aluminum foil can be ensured, for example, the pore-forming agent is a mixture of ammonium bicarbonate, oxalic acid, ammonium oxalate, ammonium carbonate and ammonium nitrate, wherein the mass ratio of the ammonium bicarbonate, the oxalic acid, the ammonium oxalate, the ammonium carbonate and the ammonium nitrate is (2-13): (3-8): (4-12): (6-18): (2-11), so, can further improve the porosity of positive plate, can strengthen the positive electrode thick liquids simultaneously with the bonding strength between the compound aluminium foil. In order to improve the conductivity of the positive plate, form a good conductive network in the positive plate by the positive slurry, reduce the weight of the positive plate, and improve the high-current charge-discharge performance of the lithium ion battery, for example, the conductive agent is at least one of carbon fiber, acetylene black, and carbon nanotubes, so that the migration efficiency of lithium ions in the positive material can be improved, the charge-discharge efficiency of the positive plate can be improved, and the energy density of the prepared lithium ion battery can be further improved.
In order to improve the stronger adhesion of the positive electrode slurry coated on the composite copper foil and simultaneously enable a positive electrode plate obtained by subsequent preparation to be softer, the performance of the electrolyte is better, and the cycle performance is better, a binder is also added in the process of preparing the positive electrode slurry, wherein the binder is at least one of styrene-butadiene rubber and sodium carboxymethylcellulose, polyvinylidene fluoride and polyacrylic acid. Therefore, the prepared anode slurry has higher performance, can be bonded more closely after being coated on the composite copper foil, and further enables the prepared anode plate to better pass through electrolyte, and has higher cycle performance.
In the process of preparing the cathode slurry, the pore-forming agent and the binder may be added into the solvent to be mixed and stirred, for example, the stirring speed is 160 rpm to 420 rpm, so that the pore-forming agent and the binder can be sufficiently dissolved in the solvent; and then adding the conductive agent and the positive active material into the solvent, and continuously mixing and stirring, for example, the stirring speed is 200-400 rpm, so that the positive active material, the pore-forming agent, the conductive agent, the adhesive and the solvent can be fully and uniformly mixed to obtain positive slurry with more uniform texture, and the positive slurry is beneficial to being more smooth after being subsequently coated on the composite aluminum foil and is not easy to have the problems of band breakage or fault. For example, the solvent is at least one of ethanol, ethylene glycol, propanol, isopropanol, acetone, N-methylpyrrolidone, and deionized water. Therefore, the positive electrode active material, the pore-forming agent, the conductive agent and the adhesive can be better dissolved in the solvent, and the positive electrode slurry with better performance is obtained.
And coating the positive electrode slurry on the composite aluminum foil, and then performing drying, cold pressing, slitting and slicing operations to obtain the positive electrode plate. For example, in the process of coating, the environmental humidity is controlled within the range of 0% to 9% relative humidity, so that the problems that the positive electrode slurry absorbs moisture in the environment during coating, the viscosity is increased, the fluidity of the positive electrode slurry is affected, the surface density of the positive electrode slurry is not stable enough after coating, or the appearance is rough can be avoided. For another example, the positive electrode slurry is dried at a temperature of 50 to 80 ℃. For another example, the cold pressing speed of 7-45 m/min, the cold pressing pressure of 5-40 MP and the cold pressing gap of 45-80 mu m are adopted for cold pressing operation, so that the porosity of the positive plate can be improved, the pore size of the formed composite aluminum foil is more uniform, and the charging capacity and the cycle capacity of the lithium ion battery are greatly improved. And (3) carrying out splitting and slicing operations on the dried and cold-pressed positive plate, firstly cutting the positive plate into large positive plates, and then cutting the positive plates into the positive plates with the required specifications.
In this embodiment, the longitudinal direction of the positive electrode sheet is the same as the longitudinal direction of the fine and soft aluminum wire. It can be understood that the aluminum-plastic composite mesh cloth obtained by the plain weave method is characterized in that the weft yarns are alternately arranged at intervals of a plurality of fine soft aluminum yarns and a plurality of second polymer fibers, the composite aluminum foil is deposited by aluminum metal and the aluminum-plastic composite mesh cloth is obtained, and the positive plate is coated by positive slurry and is obtained on the aluminum-plastic composite mesh cloth, so that the length direction of the positive plate is the same as that of the fine soft aluminum yarns, the positive plate can have better mechanical property, and the bending property is better in the subsequent winding operation.
S170, winding the negative plate, the insulating diaphragm and the positive plate to obtain the battery cell.
The preparation of the battery core is an important process in the manufacturing process of the lithium ion battery, and the battery core of the lithium ion battery can be obtained by winding the negative plate, the insulating diaphragm and the positive plate, so that the subsequent preparation of the lithium ion battery is facilitated. For example, the insulating diaphragm is a polyolefin porous membrane with high strength and a thinned film, it can be understood that the performance of the diaphragm determines the interface structure, internal resistance and the like of the battery, the characteristics of the battery, such as capacity, cycle, safety performance and the like, are directly influenced, the diaphragm with excellent performance has an important effect on improving the comprehensive performance of the battery, the polyolefin porous membrane has good insulativity and ion transmittance, and is excellent in electrolyte corrosion resistance, so that the prepared battery core has more excellent performance, and the subsequent preparation of the lithium ion battery with higher energy density is facilitated.
In particular, in the present embodiment, the longitudinal direction of the insulating separator is the same as the longitudinal direction of the negative electrode sheet and the longitudinal direction of the positive electrode sheet. It can be understood that the length direction of the negative plate is the same as the length direction of the fine soft copper wire, and the length direction of the positive plate is the same as the length direction of the fine soft aluminum wire, so that the length direction of the insulating diaphragm is the same as the length direction of the fine soft copper wire and the length direction of the fine soft aluminum wire, and in the process of winding the negative plate, the insulating diaphragm and the positive plate to obtain the battery cell, the battery cell is wound along the length directions of the fine soft copper wire and the fine soft aluminum wire, so that a battery cell with a more stable structure can be obtained, because the inherent rigidity of the metal wire can play a good supporting role for the battery cell and is more favorable for the battery cell molding, because the battery cell has a winding and bending structure, the acting force applied to the battery cell in the radial direction is smaller, and only the polymer fiber wire is adopted, so that, the cost and the quality can be greatly reduced, however, the extrusion acting force applied to the copper-plastic composite mesh cloth in the axial direction (transverse direction or weft direction) is large, when pure metal wires are used as weft wires, the problem of high bending difficulty is easy to occur, namely, the rigidity is overlarge, the bending winding resistance is large, the diaphragm or a coating can be pressed to deform or be damaged, if pure polymer fiber wires are used as weft wires, the loose state is easy to recover after winding and bending, namely, the state stability is poor, but when the copper-plastic composite mesh cloth is woven in a plain weave mode; in the plain weaving mode of the copper-plastic composite screen cloth, the warp yarns are all first high polymer fiber yarns, and the weft yarns are a plurality of fine soft copper wires and a plurality of first high polymer fiber yarns which are alternately arranged at intervals; the weaving mode of the aluminum-plastic composite mesh cloth adopts a plain weaving mode; in the plain weaving mode of the aluminum-plastic composite mesh cloth, the warp yarns are all second high polymer fiber yarns, and the weft yarns are a plurality of fine soft aluminum yarns and a plurality of second high polymer fiber yarns which are alternately arranged at intervals; the length direction of the negative plate is the same as that of the thin soft copper wire; the length direction of the positive plate is the same as that of the thin and soft aluminum wires; the length direction of the insulating diaphragm is the same as that of the negative pole piece and that of the positive pole piece, so that smooth winding and bending operation can be ensured, good state stability can be realized, and the weft of the pole piece cannot be extruded and broken in the hot pressing process of subsequent aging operation.
And S180, placing the battery core in a shell, injecting electrolyte, and performing formation and grading operation to obtain the lithium ion battery.
The lithium ion battery can be obtained by arranging the battery core in the shell, injecting electrolyte, and then carrying out formation and grading operations. For example, the battery core is placed in a steel shell and electrolyte is injected, so that a lithium ion battery with excellent performance can be prepared in the subsequent process. In order to obtain a lithium ion battery with higher energy density, as another example, the electrolyte is prepared by mixing electrolyte lithium salt, an organic solvent and an additive, for example, the electrolyte lithium salt is at least one of LiPF6, LiClO4 and LiAsF 6; for another example, the organic solvent is at least one of propylene carbonate, butylene carbonate, diethyl carbonate, dimethyl carbonate, tetrahydrofuran, gamma-butyrolactone, methyl formate and methyl acetate; for another example, the additive is at least one of vinylene carbonate and vinyl vinylene acid; thus, the lithium ion battery with better performance can be prepared.
It can be understood that a lithium ion battery just manufactured needs to be charged and discharged with a small current for the first time, because the electrode material is not in the best applicable state after the battery is manufactured, or the physical properties are not appropriate, such as too large particles, loose contact and the like, or the phase itself is not proper, such as a metal oxide negative electrode of some alloy mechanisms, needs to be charged and discharged for the first time to activate the metal oxide negative electrode. Therefore, after the battery core is arranged in the shell and the electrolyte is injected into the shell, formation operation is needed to be carried out so as to activate the lithium ion battery by carrying out first charge and discharge on the lithium ion battery. In order to enable the properties and the composition of an SEI film formed after the lithium ion battery is charged for the first time to be more stable and ensure the stability of the electrochemical performance of the battery, the lithium ion battery is sequentially subjected to formation and capacity grading operation, and the high-energy-density lithium ion battery can be obtained. For example, the lithium ion battery is formed at a high temperature, so that the SEI structure is favorably recombined to form a loose and porous film, and the prepared lithium ion battery has higher energy density and more accurate and stable voltage.
According to the preparation method of the lithium ion battery, the fine soft copper wires and the first high polymer fibers are woven into the copper-plastic composite mesh cloth, the copper metal is deposited on the copper-plastic composite mesh cloth by adopting a physical vapor deposition process to obtain a composite copper foil, and the negative electrode slurry is coated on the composite copper foil to obtain a negative electrode sheet; weaving the fine and soft aluminum wires and the second high polymer fiber wires into an aluminum-plastic composite mesh cloth, depositing aluminum metal on the aluminum-plastic composite mesh cloth by adopting a physical vapor deposition process to obtain a composite aluminum foil, and coating the positive electrode slurry on the composite aluminum foil to obtain a positive plate; and then winding the negative plate, the insulating diaphragm and the positive plate to obtain an electric core, and performing shell entering, liquid injection, formation and capacity grading operations on the electric core to obtain the lithium ion battery.
The following is a detailed description of the embodiments.
Example 1
(1) Providing a fine soft copper wire and a polyethylene terephthalate fiber wire;
(2) weaving fine soft copper wires and polyethylene glycol terephthalate fiber yarns into a copper-plastic composite mesh cloth with the mesh number of 80 meshes by adopting a plain weaving mode, wherein the warp yarns are all polyethylene glycol terephthalate fiber yarns, and the weft yarns are a plurality of fine soft copper wires and a plurality of polyethylene glycol terephthalate fiber yarns which are alternately arranged at intervals; with copper metalTaking the copper-plastic composite mesh as a base material as a target material, carrying out ultrasonic cleaning on the copper-plastic composite mesh, and depositing copper metal on the copper-plastic composite mesh in a vacuum evaporation way, wherein the vacuum degree is 3 multiplied by 10-3Pa, the evaporation distance is 9cm, the evaporation current is 350A, the evaporation voltage is 2V, and the evaporation time is 20min to obtain a composite copper foil;
(3) coating the negative electrode slurry on a composite copper foil, drying, cold pressing, stripping and slicing to obtain a negative electrode plate;
(4) providing fine and soft aluminum filaments and polyethylene terephthalate fiber filaments;
(5) weaving fine and soft aluminum wires and polyethylene glycol terephthalate fiber wires into an 80-mesh aluminum-plastic composite mesh cloth in a plain weaving mode, wherein the warp wires are all polyethylene glycol terephthalate fiber wires, and the weft wires are a plurality of fine and soft aluminum wires and a plurality of polyethylene glycol terephthalate fiber wires which are alternately arranged at intervals; taking aluminum metal as a target material and aluminum-plastic composite mesh cloth as a base material, carrying out ultrasonic cleaning on the aluminum-plastic composite mesh cloth, and depositing the aluminum metal on the aluminum-plastic composite mesh cloth by adopting a magnetron sputtering mode to obtain a composite aluminum foil;
(6) coating the positive electrode slurry on a composite aluminum foil, and performing drying, cold pressing, slitting and slicing operations to obtain a positive plate;
(7) winding the negative plate, the polyolefin porous membrane and the positive plate to obtain a battery cell;
(8) and (3) placing the battery cell in a steel shell, injecting electrolyte, and performing formation and grading operation to obtain the lithium ion battery of the embodiment 1.
Example 2
(1) Providing fine soft copper wires and polyamide fiber wires;
(2) weaving fine soft copper wires and polyamide fiber wires into a copper-plastic composite mesh cloth with the mesh number of 90 meshes by adopting a plain weaving mode, wherein the warp wires are all polyamide fiber wires, and the weft wires are a plurality of fine soft copper wires and a plurality of polyamide fiber wires which are alternately arranged at intervals; copper metal is used as a target material, copper-plastic composite mesh cloth is used as a base material, the copper-plastic composite mesh cloth is subjected to ultrasonic cleaning, and then the copper metal is deposited on the copper-plastic composite mesh cloth in a vacuum evaporation modeOn a net cloth with a vacuum degree of 4X 10-3Pa, the evaporation distance is 10cm, the evaporation current is 350A, the evaporation voltage is 3V, and the evaporation time is 25min to obtain a composite copper foil;
(3) coating the negative electrode slurry on a composite copper foil, drying, cold pressing, stripping and slicing to obtain a negative electrode plate;
(4) providing fine and soft aluminum wires and polyimide fiber wires;
(5) weaving fine and soft aluminum wires and polyimide fiber wires into 90-mesh aluminum-plastic composite mesh cloth in a plain weaving mode, wherein the warp wires are all polyimide fiber wires, and the weft wires are a plurality of fine and soft aluminum wires and a plurality of polyimide fiber wires which are alternately arranged at intervals; taking aluminum metal as a target material and aluminum-plastic composite mesh cloth as a base material, carrying out ultrasonic cleaning on the aluminum-plastic composite mesh cloth, and depositing the aluminum metal on the aluminum-plastic composite mesh cloth by adopting a magnetron sputtering mode to obtain a composite aluminum foil;
(6) coating the positive electrode slurry on a composite aluminum foil, and performing drying, cold pressing, slitting and slicing operations to obtain a positive plate;
(7) winding the negative plate, the polyolefin porous membrane and the positive plate to obtain a battery cell;
(8) and (3) placing the battery cell in a steel shell, injecting electrolyte, and performing formation and grading operation to obtain the lithium ion battery of the embodiment 2.
Example 3
(1) Providing a fine soft copper wire and a polyvinylidene fluoride fiber wire;
(2) weaving fine and soft copper wires and polyvinylidene fluoride fiber wires into a copper-plastic composite mesh cloth with the mesh number of 100 by adopting a plain weaving mode, wherein the warp wires are polyvinylidene fluoride fiber wires, and the weft wires are a plurality of fine and soft copper wires and a plurality of polyvinylidene fluoride fiber wires which are alternately arranged at intervals; copper metal is used as a target material, copper-plastic composite mesh cloth is used as a base material, the copper metal is deposited on the copper-plastic composite mesh cloth in a magnetron sputtering mode after the copper-plastic composite mesh cloth is subjected to ultrasonic cleaning, wherein the sputtering power is 50W, the air pressure of argon during sputtering is 0.6Pa, the flow rate of argon is 40sccm, and the vacuum degree is 2.0 x 10-5Pa, sputtering for 3h to obtain a composite copper foil;
(3) coating the negative electrode slurry on a composite copper foil, drying, cold pressing, stripping and slicing to obtain a negative electrode plate;
(4) providing fine and soft aluminum filaments and polyethylene terephthalate fiber filaments;
(5) weaving fine and soft aluminum wires and polyethylene glycol terephthalate fiber wires into an aluminum-plastic composite mesh cloth with the mesh number of 100 meshes by adopting a plain weaving mode, wherein the warp wires are all polyethylene glycol terephthalate fiber wires, and the weft wires are a plurality of fine and soft aluminum wires and a plurality of polyethylene glycol terephthalate fiber wires which are alternately arranged at intervals; taking aluminum metal as a target material and aluminum-plastic composite mesh cloth as a base material, carrying out ultrasonic cleaning on the aluminum-plastic composite mesh cloth, and depositing the aluminum metal on the aluminum-plastic composite mesh cloth by adopting a magnetron sputtering mode to obtain a composite aluminum foil;
(6) coating the positive electrode slurry on a composite aluminum foil, and performing drying, cold pressing, slitting and slicing operations to obtain a positive plate;
(7) winding the negative plate, the polyolefin porous membrane and the positive plate to obtain a battery cell;
(8) and (3) placing the battery cell in a steel shell, injecting electrolyte, and performing formation and grading operation to obtain the lithium ion battery of the embodiment 3.
Through experimental analysis, the lithium ion batteries prepared in the embodiments 1 to 3 have higher battery capacity, higher charge and discharge efficiency, better cycle stability and safety, and particularly lighter weight than the existing lithium ion battery, which is only 60% of the existing lithium ion battery, and the energy density is greatly improved. In particular, the lithium ion battery of example 3 has the highest energy density, because the preparation process and the preparation raw materials are more optimized while the process parameters are adjusted, for example, a plain weaving method is adopted to weave fine and soft copper wires and polyvinylidene fluoride fibers into a copper-plastic composite mesh, wherein the warp filaments are polyvinylidene fluoride fiber filaments, the weft filaments are a plurality of fine soft copper wires and a plurality of polyvinylidene fluoride fiber filaments which are alternately arranged at intervals, simultaneously combines the shaping of the polymer fiber yarns and the metal rigidity of the copper wires, prepares the copper-plastic composite mesh cloth with more uniform meshes, higher stability and good surface evenness, is beneficial to better depositing copper metal subsequently to obtain composite copper foil with better conductivity, meanwhile, the net structure is more favorable for absorbing electrolyte and more efficiently transferring lithium ions inside the lithium ion battery, so that the energy density of the lithium ion battery is improved. If the negative pole piece, polyolefin porous membrane and positive plate are coiled to obtain the in-process of electric core, the length direction of negative pole piece is the same with the length direction of positive plate, the length direction of negative pole piece is the same with the length direction of thin soft copper wire, the length direction of positive plate is the same with the length direction of thin soft aluminum wire, so, can obtain the more stable electric core of structure, this is because the inherent rigidity of metal silk itself can play good supporting role to electric core, more be favorable to the electric core shaping simultaneously, and then it is bigger to do benefit to follow-up preparation and obtained the capacity, charge-discharge efficiency is higher, and circulation stability and security are better, especially weight is lighter, the lithium ion battery that energy density is higher.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (6)

1. A preparation method of a lithium ion battery is characterized by comprising the following steps:
providing a thin and soft copper wire and a first polymer fiber wire;
weaving the fine soft copper wires and the first high polymer fiber wires into a copper-plastic composite mesh cloth in a plain weaving mode, wherein the warp wires are the first high polymer fiber wires, and the weft wires are a plurality of fine soft copper wires and a plurality of first high polymer fiber wires which are alternately arranged at intervals; depositing copper metal on the copper-plastic composite mesh cloth by using a physical vapor deposition process by using copper metal as a target and the copper-plastic composite mesh cloth as a base material to obtain a composite copper foil;
coating the negative electrode slurry on the composite copper foil, and performing drying, cold pressing, stripping and slicing operations to obtain a negative electrode sheet;
providing a fine and soft aluminum filament and a second high polymer fiber filament;
weaving the fine and soft aluminum wires and the second high polymer fiber wires into an aluminum-plastic composite mesh cloth in a plain weaving mode, wherein the warp wires are the second high polymer fiber wires, and the weft wires are a plurality of fine and soft aluminum wires and a plurality of second high polymer fiber wires which are alternately arranged at intervals; taking aluminum metal as a target material, taking the aluminum-plastic composite mesh cloth as a base material, and depositing the aluminum metal on the aluminum-plastic composite mesh cloth by adopting a physical vapor deposition process to obtain a composite aluminum foil;
coating the positive electrode slurry on the composite aluminum foil, and performing drying, cold pressing, slitting and slicing operations to obtain a positive electrode plate;
winding the negative plate, the insulating diaphragm and the positive plate to obtain a battery core;
and placing the battery core in a shell, injecting electrolyte, and performing formation and grading operation to obtain the lithium ion battery.
2. The method for preparing the lithium ion battery according to claim 1, wherein the first polymer fiber is polyethylene terephthalate fiber, polyamide fiber, polyimide fiber, polyvinylidene fluoride fiber, or aramid fiber.
3. The method according to claim 1, wherein the length direction of the negative electrode sheet is the same as the length direction of the fine soft copper wire.
4. The method according to claim 3, wherein the length direction of the positive electrode sheet is the same as the length direction of the fine soft aluminum wire.
5. The method according to claim 4, wherein a longitudinal direction of the insulating separator is the same as a longitudinal direction of the negative electrode sheet and a longitudinal direction of the positive electrode sheet.
6. A lithium ion battery prepared by the method for preparing a lithium ion battery according to any one of claims 1 to 5.
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