CN113422062A - Current collector, pole piece, battery and equipment - Google Patents

Current collector, pole piece, battery and equipment Download PDF

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Publication number
CN113422062A
CN113422062A CN202110511808.6A CN202110511808A CN113422062A CN 113422062 A CN113422062 A CN 113422062A CN 202110511808 A CN202110511808 A CN 202110511808A CN 113422062 A CN113422062 A CN 113422062A
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layer
current collector
battery
pole piece
supporting layer
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王发礼
吴军
刘升
王皓鹤
刘强
王广
邱申
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Linkdata New Energy Co Ltd
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Linkdata New 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
    • H01M4/66—Selection of materials
    • H01M4/665—Composites
    • H01M4/667—Composites in the form of layers, e.g. coatings
    • 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
    • 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
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • 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)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Composite Materials (AREA)
  • Cell Electrode Carriers And Collectors (AREA)

Abstract

The invention discloses a current collector, which comprises a supporting layer, a high polymer film with Young modulus of 5-30 Gpa and shrinkage rate of not more than 1% at 90 ℃ for 12 hours, and a first surface and a second surface which are opposite; and the conductive layer is arranged on the first surface and/or the second surface of the support layer. The current collector takes the high-molecular polymer film as a supporting layer, is light in weight, and is beneficial to reducing the weight of a battery, improving the energy density and improving the specific energy of the battery; the current collector is fused and shrunk at the moment of short circuit, and the polymer supporting layer rapidly forms a steric effect between the positive electrode and the negative electrode, so that the short circuit phenomenon is prevented from further occurring, and the safety of the battery is improved. The invention also discloses a pole piece, a battery and equipment based on the current collector.

Description

Current collector, pole piece, battery and equipment
Technical Field
The invention relates to the technical field of lithium batteries, in particular to a current collector, a pole piece, a battery and equipment.
Background
With the increasing demand of lithium batteries and the pursuit of high energy density of lithium ion batteries, the energy density of ternary high nickel batteries is high compared with batteries represented by lithium ion secondary batteries, but ternary high nickel battery cells are prone to explosion in extreme situations, such as nail penetration and needle punching, and a new material is needed to be found to improve the safety problem.
Aiming at the explosion defects of the extreme conditions, in the prior art, punching a current collector foil and using a PTC thermistor mode to inhibit the heat explosion, but the solution can affect the performance of the battery, and the inhibition effect on the heat explosion of the battery is not obvious.
Disclosure of Invention
One of the purposes of the invention is to overcome the defects in the prior art and provide a current collector which has uniform thickness, good conductivity and mechanical properties, no reactions such as explosion, ignition and fuming under extreme conditions such as battery needling and high temperature and high safety.
In order to achieve the technical effects, the technical scheme of the invention is as follows: a current collector, comprising:
the supporting layer is a high polymer film with the Young modulus of 5-30 GPa and the shrinkage rate of not more than 1% at 90 ℃ for 12 hours, and is provided with a first surface and a second surface which are opposite;
and the conducting layer is arranged on the first surface and/or the second surface of the supporting layer.
The conductive layer can be arranged on one surface of the conductive layer or on both surfaces of the conductive layer, and is preferably arranged on both surfaces of the conductive layer. Specifically, the young's modulus satisfied by the material of the support layer is, for example, 5Gpa, 8Gpa, 10Gpa, 12Gpa, 15Gpa, 18Gpa, 20Gpa, 22Gpa, 25Gpa, 27Gpa, or 30Gpa, or an interval value including any two of the above-mentioned values, and more preferably 6 to 10 Gpa. The shrinkage rate of the support layer material at 90 ℃ for 12h is, for example: 0.15%, 0.3%, 0.5%, 0.7%, 0.9%, or 1% of the above-mentioned values and intervals containing any two of the above-mentioned values, and more preferably 0.5% to 0.8%.
The preferable technical scheme is that the method further comprises the following steps: and the bonding layer is arranged between the supporting layer and the conductive layer, and the main composition of the bonding layer is solid oxide. The conducting layer is provided with a first surface and a second surface which are opposite in the thickness direction, the first surface of the conducting layer is provided with a supporting layer, and the second surface of the conducting layer is provided with an adhesive layer. The adhesive layer can promote the adhesive force between the polymer of supporting layer and the conducting layer, and the adhesive force promotion can reduce the risk of peeling off between conducting layer and the supporting layer, promotes the yield that electric core made, promotes the performance of electric core. The mass percentage of the solid oxide in the bonding layer is 80-100% based on 100% of the bonding layer. The solid oxide of the bonding layer includes metal oxide and non-metal oxide which are solid at normal temperature. The metal oxide is selected from alumina, titanium oxide, etc., and the non-metal oxide is selected from polyvinyl alcohol, resin, polyimide, polyacrylic acid, etc.
The preferable technical scheme is that the method further comprises the following steps: the anti-oxidation layer is arranged on the surface, opposite to the supporting layer, of the conductive layer; the main composition of the bonding layer is solid oxide. The conducting layer is provided with a first surface and a second surface which are opposite in the thickness direction, the first surface of the conducting layer is provided with a supporting layer, and the second surface of the conducting layer is provided with an anti-oxidation layer. Furthermore, an adhesive layer is arranged on the first surface of the conductive layer, and an anti-oxidation layer is arranged on the second surface of the conductive layer. The antioxidation layer can prevent the current collector from being oxidized in the actual use process of the battery, the possibility of peeling off the conducting layer due to the internal oxidation of the current collector exists, and the safety risks of thermal runaway and the like of the battery cell due to the peeled conducting layer can be avoided. The solid oxide of the antioxidation layer includes metal oxide and nonmetal oxide which are solid at normal temperature. The metal oxide is selected from alumina, titania, etc., and the non-metal oxide is selected from alkyl carbonate, lithium sulfide, etc.
The preferable technical proposal is that the high molecular polymer film is a single layer or a composite film with more than two layers; the high polymer material of the supporting layer is at least one selected from polyethylene terephthalate, polyimide, polypropylene, polyethylene and polyethylene naphthalate;
the conducting layer is a metal layer or mainly comprises metal; the metal of the conductive layer is at least one selected from aluminum, copper, tin and zinc.
The conductive layer is a metal layer, which means that the mass percent of the metal components of the conductive layer is 100% except inevitable impurities. The main composition of the conductive layer is metal, namely the mass percentage of the metal components in the conductive layer is 98-100% and does not include 100%, and further, the composition of the conductive layer also comprises oxides such as aluminum oxide, silicon dioxide and the like.
The preferable technical scheme is that the thickness of the supporting layer is 2-20 mu m, and the thickness of the conducting layer is 200-2500 nm. The thickness of the support layer is, for example, 2 μm, 5 μm, 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, or the like, or a range including any two of them, more preferably 4 to 12 μm, and still more preferably 6 to 8 μm; further, the thickness of the conductive layer is, for example, 200nm, 400nm, 700nm, 1000nm, 1400nm, 1800nm, 2000nm, 2200nm, 2500nm, or a range including any two of the foregoing, more preferably 300 to 2000nm, and still more preferably 500 to 1500 nm.
The preferable technical scheme is that the thickness of the bonding layer is 10-60 nm, and the solid oxide of the bonding layer is at least one selected from aluminum oxide and silicon dioxide. Specifically, the thickness of the adhesive layer is, for example, 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, or a range including any two of the foregoing, more preferably 20 to 60nm, and still more preferably 40 to 50 nm. Further, the solid oxide of the bonding layer is a composition of aluminum oxide and silicon dioxide, and the mass ratio of the aluminum oxide to the silicon dioxide is 1: (0.01 to 0.3), and more preferably 1: (0.05-0.1).
The preferable technical scheme is that the thickness of the antioxidation layer is 10-50 nm, and the solid oxide of the antioxidation layer is at least one selected from aluminum oxide and silicon dioxide. Specifically, the thickness of the adhesive layer is, for example, 10nm, 20nm, 30nm, 40nm, 50nm, or a range including any two of the foregoing values, more preferably 10 to 35nm, and still more preferably 20 to 30 nm. Further, the solid oxide of the antioxidation layer is aluminum oxide.
Preferably, the adhesive layer is attached to the surface of the support layer by evaporation or sputtering, and/or the conductive layer is attached to the surface of the adhesive layer by evaporation or sputtering. Furthermore, the anti-oxidation layer is attached to the surface of the conductive layer by evaporation or sputtering.
The invention also provides a pole piece, which comprises a current collector and an active material layer arranged on the current collector, wherein the current collector is the current collector.
The invention also provides a battery, which comprises a positive pole piece, a negative pole piece, a diaphragm and an electrolyte, wherein the positive pole piece and/or the negative pole piece comprise the current collector.
The fourth objective of the present invention is to provide an apparatus comprising the above battery. Further, the device is an electronic product or an electric vehicle.
The invention has the advantages and beneficial effects that:
the current collector takes the high-molecular polymer film as a supporting layer, is light in weight, and is beneficial to reducing the weight of a battery, improving the energy density and improving the specific energy of the battery;
the shrinkage rate is more than 1% at 90 ℃ for 12h, the peeling probability of the conducting layer on the surface of the supporting layer is increased in the manufacturing process of the battery cell, and the battery cell pole piece is failed;
the pole piece prepared by the current collector is used in a battery, the current collector is fused and shrunk at the moment of short circuit, and the polymer supporting layer rapidly forms a steric effect between a positive electrode and a negative electrode to prevent the further short circuit phenomenon, so that the battery does not undergo reactions such as explosion, ignition, fuming and the like under extreme conditions such as needling, high temperature and the like, and the safety performance of the battery and equipment comprising the battery is improved.
Drawings
Fig. 1 is a schematic structural view of a current collector of an embodiment;
fig. 2 is a schematic structural view of another embodiment current collector;
fig. 3 is a schematic structural view of another embodiment current collector;
FIG. 4 is a schematic structural diagram of a positive electrode tab according to another embodiment;
FIG. 5 is a graph of pin temperature, cell surface temperature, and voltage versus time for a battery pin test;
in the figure: 1. a support layer; 2. an adhesive layer; 3. a conductive layer; 4. an anti-oxidation layer; 5. a positive electrode active material layer.
Detailed Description
The following further describes embodiments of the present invention with reference to examples. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.
Young modulus testing method
Cutting a supporting layer sample into 15mm × 300mm, measuring the thickness h (mum) of the sample by using a thickness gauge, performing a tensile test at 25 +/-5 ℃ by using a tensile machine, enabling the sample between clamps to be 30mm long, performing the tensile test at the speed of 100mm/min, recording the load M (N) of the tensile test to break, and recording the stress strain curve by using the equipment displacement y (mm), wherein the stress epsilon is M/(15 × h) 1000, the strain eta is (y +30)/30, and taking an initial linear region curve, wherein the slope of the curve is Young modulus E.
Method for testing shrinkage rate of 12h at 90 DEG C
Cutting the support layer sample to obtain a sample with a width of 10cm and an unlimited length, storing the sample in an incubator at 90 ℃ for 12h, and recording the width N after storage, wherein the shrinkage rate B is (10-N)/N100%.
The metal material selection range of the conducting layer comprises aluminum alloy, titanium alloy, copper alloy and the like, optionally, the aluminum alloy is an alloy formed by adding one or more other elements into aluminum serving as a base body, such as aluminum-nickel alloy, and the ratio of aluminum to nickel in the alloy is 99.5: 0.5.
current collector
As shown in fig. 1, in an embodiment, the current collector includes a supporting layer 1, bonding layers 2 are disposed on a first surface and a second surface of the supporting layer 1 opposite to each other in a thickness direction, conductive layers 3 are disposed on surfaces of the two bonding layers 2 opposite to the supporting layer 1, respectively, and anti-oxidation layers 4 are disposed on surfaces of the two conductive layers 3 opposite to the bonding layers 2, respectively.
As shown in fig. 2, in another embodiment, the current collector includes a supporting layer 1, bonding layers 2 are disposed on a first surface and a second surface of the supporting layer 1 opposite to each other in the thickness direction, and conductive layers 3 are disposed on surfaces of the two bonding layers 2 opposite to the supporting layer 1, respectively.
As shown in fig. 3, in another embodiment, the current collector includes a supporting layer 1, wherein conductive layers 3 are disposed on a first surface and a second surface of the supporting layer 1 opposite to each other in the thickness direction, and oxidation resistant layers 4 are disposed on surfaces of the two conductive layers 3 opposite to the supporting layer 1, respectively.
Any one of the attachment processes of the conductive layer to the surface of the supporting layer and the conductive layer to the surface of the bonding layer may be mechanical rolling, pasting, vapor deposition, chemical plating, electroplating, and more preferably evaporation and sputtering. The adhesion process of the adhesion layer on the surface of the supporting layer and the antioxidation layer on the surface of the conductive layer can be selected from vapor deposition, electroplating, chemical plating and pasting, and further preferably evaporation and sputtering.
The vapor deposition is a process method in which a coating material (or called a coating material) is evaporated and gasified in a certain heating and evaporation manner under a vacuum condition, and particles fly to the surface of a substrate to condense and form a film. The evaporation is a vapor deposition technology which is used earlier and has wider application, and has the advantages of simple film forming method, high film purity and compactness, unique film structure and performance and the like; in the sputtering process, under the vacuum environment, proper inert gas is introduced as a medium, the inert gas is accelerated to impact the target, so that atoms on the surface of the target are impacted, and a coating film is formed on the surface of the substrate. Sputtering is commonly referred to as magnetron sputtering. Compared with the common evaporation plating, the sputtering has the advantages of strong bonding force between the electroplated layer and the base material, over 10 times higher adhesion force than the evaporation plating, compact and uniform electroplated layer, and the like.
Pole piece
As shown in fig. 4, in another embodiment, the positive electrode tab includes a current collector and a positive active material layer 5 disposed on the current collector. The positive active material may adopt active materials known in the art, and satisfy the functions of extracting lithium ions from the crystal lattice thereof and inserting lithium ions into the crystal lattice thereof during charging, such as positive ternary materials NCM, LFP, and the like. The positive active material includes, but is not limited to, a conductive agent and a binder. The positive pole piece can be prepared by adopting known technological methods such as slurry coating drying, dry powder hot rolling and the like.
When the negative electrode active material is used as a negative electrode current collector, the negative electrode active material disposed on the surface of the current collector may be any active material known in the art, such as a carbon negative electrode material (artificial graphite, natural graphite, mesocarbon microbeads, etc.), an alloy negative electrode material (tin-based alloy, silicon-based alloy, germanium-based alloy, aluminum-based alloy, antimony-based alloy, magnesium-based alloy, etc.), a tin-based negative electrode material (tin oxide, tin-based composite oxide), a lithium-containing transition metal nitride negative electrode material, carbon nanotubes, a nanoalloy material, and a nanoalloy material. The negative pole piece can be prepared by adopting known technological methods such as slurry coating drying, dry powder hot rolling and the like.
Battery with a battery cell
The battery comprises a positive pole piece, a negative pole piece, a diaphragm and electrolyte, wherein the positive pole piece comprises a current collector and a positive active material layer arranged on the current collector, and the negative pole piece comprises a current collector and a negative active material layer arranged on the current collector. The current collector in at least one of the positive pole piece and the negative pole piece is a current collector comprising a supporting layer and a conducting layer, and further comprises an adhesive layer or an anti-oxidation layer; furthermore, the current collector comprises an adhesion layer and an oxidation resistant layer. Preferably, the battery is a ternary lithium ion battery.
The separator of the battery is not particularly limited, and the coating layer may be selected according to the material of the separator, such as a polyester film (PET), a cellulose film, a polyimide film (PI), a polyamide film (PA), a spandex or aramid film, and the like, the type of the separator may be selected from a woven film, a nonwoven film (nonwoven fabric), a microporous film, a composite film, a separator paper, and a laminate film, and the layered structure of the separator may be selected from a single layer of polypropylene (PP), a single layer of Polyethylene (PE), a polypropylene (PP) + ceramic coating, a Polyethylene (PE) + ceramic coating, a double layer of polypropylene (PP)/Polyethylene (PE), a double layer of polypropylene (PP), and a triple layer of polypropylene (PP)/Polyethylene (PE)/polypropylene (PP).
The electrolyte mainly comprises an organic solvent and electrolyte salt and is a carrier for ion transmission in the battery. The organic solvent of the lithium ion ternary battery can be selected from Propylene Carbonate (PC), Ethylene Carbonate (EC), diethyl carbonate (DEC) and the like; the lithium salt may be selected from LiFP6、LiClO4And the like.
The device comprises a battery with the following structure, wherein a current collector in at least one of a positive pole piece and a negative pole piece of the battery is a current collector comprising a supporting layer and a conducting layer; further, the current collector also comprises an adhesive layer or an anti-oxidation layer; furthermore, the current collector comprises an adhesion layer and an oxidation resistant layer.
The device includes a device using a battery as a power source, and further preferably includes an electric automobile and an electronic product.
Unless defined otherwise, technical terms used in the following examples have the same meanings as commonly understood by one of ordinary skill in the art to which the present invention belongs.
Preparation of current collectors
Selecting a polymer film with a preset thickness and material, carrying out corona/plasma cleaning/ultrasonic cleaning on the polymer, and then cleaning and drying the polymer film by using deionized water to obtain a supporting layer;
placing the support layer in a vacuum chamber of a continuous winding device, and vacuumizing (to 10)-3～
10-7mbar); the method comprises the steps that a continuous winding vacuum device runs at a preset winding speed (5-200 m/min), an evaporation boat of the continuous winding vacuum device runs, the power (500-5000 kW) of the evaporation boat and a preset evaporation distance (8-25 cm) between an inner material and a polymer base film are adjusted, a layer of oxide is plated on the surface of a polymer to serve as a bonding layer, and a sample for completing the evaporation of the bonding layer is subjected to evaporation of a conducting layer and an anti-oxidation layer in sequence to obtain a current collector.
Preparation of positive pole piece
Using a current collector obtained by evaporation as a positive current collector, using a positive active material as ternary NCM, and mixing the positive active material (NCM), a conductive agent Carbon Nanotubes (CNTs), carbon black (SP) and a binder PVDF5130 according to a ratio of 96.5: 2: dissolving the positive electrode slurry in N-methyl pyrrolidone (NMP) according to the mass ratio of 1.5, wherein the solid content of the positive electrode slurry is 75 wt%, stirring to obtain slurry with the viscosity of about 3000mpa.s, uniformly mixing, coating, baking and rolling on a positive electrode current collector, wherein the temperature of the current collector subjected to rolling treatment is 70-120 ℃, and cutting to obtain the positive electrode piece. The nickel content of NCM is 88 wt%, and conductive agent binder is used for preparing the anode plate, and the surface density of the anode material is 170mg/m2The thickness after rolling was 110 μm, and the compacted density was 3.5 g/cc.
Preparation of negative pole piece
Mixing negative active material (graphite, silicon monoxide) and conductive agent to obtain single-arm carbon nanotube
(SWCNT), binder lithium carboxymethyl cellulose and modified polyacrylic acid (CMCLi + PAA), in a ratio of 96.9: 0.1: 1.5: kneading and stirring the mixture in deionized water according to the mass ratio of 1.5 to obtain slurry with the viscosity of 3000mpa.s, and coating the slurry on a copper foil with the thickness of 8 +/-4 mu m, and performing cold pressing and slicing to prepare the negative pole piece. The density of the negative electrode surface is 85 +/-5 mg/m2The thickness after rolling is 110 +/-5 mu m, the compaction density is 1.5 +/-0.2 g/cc, and the active substance is a silicon-carbon composite product (SiC)>10 wt%, cathode gram capacity>450mAh/g)。
Preparation of the Battery
Winding the positive and negative pole pieces and a double-sided coated ceramic diaphragm (the diaphragm is coated with a ceramic layer with a diameter of 2 mu m) according to preset process parameters, wherein the diaphragm coats a negative pole with a diameter of 2mm, and the negative pole coats a positive pole with a diameter of 1 mm; then welding tabs in the positive and negative electrode white areas after the winding of the battery cell is subjected to hot pressing, and then packaging the welded battery cell by an aluminum-plastic film;
baking the packaged battery cell at 90 ℃ to remove moisture, and mixing Ethyl Methyl Carbonate (EMC), Ethylene Carbonate (EC), DEC (diethyl carbonate), Propylene Carbonate (PC) and lithium salt in a compounding ratio of 50:20:20:10 to obtain lithium bis (fluorosulfonyl) imide (LiFSI) and hexafluoro-sulfonyl imide (LiFSI) with a lithium salt compounding ratio of 0.3M:0.8MLithium phosphate (LiPF)6) Electrolyte of complex lithium salt, according to liquid injection coefficient>Injecting liquid at 3.5 g/Ah;
and forming according to preset hot-pressing forming process parameters, placing at high temperature, carrying out secondary sealing, and carrying out capacity grading to prepare the soft package battery with the capacity of more than 191mAh/g and the capacity of 10wh of the positive electrode. Testing by a resistance meter to obtain the internal resistance of the battery to be 5.1m omega; the battery capacity was measured to be 2500mAH by the charge-discharge system.
The test method comprises the following steps:
1. conductive layer adhesion test of current collector
An ST-D200 testing machine (required to meet GB/T2792-2014 standard) and a standard mirror 304 peeling force test steel plate, wherein the roughness is 50 +/-25 nm, a product is cut into a sample with the width of 25mm and the length of 250mm, and three samples are prepared; the method comprises the steps of cleaning a steel plate by using alcohol dust-free cloth, bonding a product on the steel plate, rolling the steel plate back and forth for 2 times by using a 2kg manual pressing wheel, placing the steel plate for 20 minutes (the temperature is required to be 23 +/-2 ℃, and the humidity is 50% +/-5), placing the steel plate for 20 minutes, mounting the steel plate on a machine clamp, carrying out a 180-degree adhesive sticker peeling force tester, adjusting the testing speed of software to 10mm/min, then carrying out a peeling force test by clicking operation, and outputting the average peeling force after the testing is finished.
2. Current collector oxidation resistance test
And (3) packaging the electrolyte with EC: DEC: EMC 1:1:1 and the current collector in an aluminum-plastic film bag, putting the aluminum-plastic film bag in an oven at 85 ℃, taking out the current collector after 72 hours, and carrying out a peel strength test, wherein if the peel strength is more than 30N/m, the oxidation test is passed, and otherwise, the oxidation test is not passed.
3. Pole piece peel force test
An ST-D200 testing machine (required to meet GB/T2792-2014 standard) and a standard mirror 304 peeling force test steel plate, wherein the roughness is 50 +/-25 nm, the anode pole piece is cut into pieces with the width of 22mm and the length of 150mm, and three pieces of samples are prepared; the method comprises the steps of cleaning a steel plate by using alcohol dust-free cloth, bonding a product on the steel plate, rolling the steel plate back and forth for 2 times by using a 2kg manual pressing wheel, placing the steel plate for 20 minutes (the temperature is required to be 23 +/-2 ℃, and the humidity is 50% +/-5), placing the steel plate for 20 minutes, mounting the steel plate on a machine clamp, carrying out a 180-degree adhesive sticker peeling force tester, adjusting the testing speed of software to be 50mm/min, then carrying out a peeling force test by clicking operation, and outputting the average peeling force after the testing is finished.
4. Needle prick test
The prepared battery is subjected to a needling test according to 6.28 in national standard GBT-31485 plus 2015 safety requirement and test method for power storage batteries for electric automobiles, a high temperature resistant steel needle with the diameter of 8mm is used, the conical angle of the needle point is 45 degrees, the battery is vertically inserted into a 10wh soft package battery at the speed of 25mm/min, the steel needle is kept in the soft package battery, and the temperature rise and the voltage of the soft package battery are detected.
4.1 detection of temperature rise: and (4) respectively testing the temperature of the needle and the surface temperature of the battery by using a multi-channel thermometer.
4.2 detection of voltage: and connecting the positive electrode and the negative electrode of the battery to be needled to the measuring end of the internal resistance instrument, and performing battery voltage tracking test after needling.
And (3) testing results:
1. adhesion of conductive layer
The production process of current collectors No. 1-15 in Table 1 has common parameters: the thickness of the supporting layer is 10 mu m, the thickness of the bonding layer is 35nm, and the material of the bonding layer is Al2O3+SiO2(the mass ratio of aluminum oxide to silicon dioxide is 9:1), and the antioxidation layer is 50nm of Al2O3The conductive layer is made of aluminum. The supporting layer is made of PET (Young modulus 7Gpa, shrinkage rate 0.8% at 90 ℃ for 12 h), PI (Young modulus 10Gpa, shrinkage rate 0.1% at 90 ℃ for 12 h) and PP (Young modulus 5Gpa, shrinkage rate 1% at 90 ℃ for 12 h).
Based on current collector No. 1, current collector parameters No. 16 and 17 are distinguished as follows: the No. 16 current collector bonding layer is made of SiO2And the No. 17 current collector bonding layer is made of Al2O3(ii) a And the 18 current collector is a bonding layer blank sample, namely a bonding layer is not evaporated, and a conductive layer and an anti-oxidation layer are sequentially evaporated on the surface of the supporting layer. The current collector distinguishing parameters and the conductive layer adhesion detection results are shown in the following table 1:
TABLE 1
Figure BDA0003060571020000111
2. Oxidation resistance test
Based on the No. 1 current collector, the common parameters of the antioxidation layer in the production process of the current collector are as follows: the vacuum degree of the vacuum chamber of the continuous type winding equipment is 10-3MPa, the power of an evaporation boat is 3000kw, and the winding speed is 5 m/min; the current collector distinguishing parameters and the anti-oxidation layer peel strength detection results are shown in the following table 2:
TABLE 2
Current collector numbering Thickness of antioxidant layer (nm) Material of anti-oxidation layer Peel strength (N/m)
1 50 Al2O3 182
19 30 Al2O3 150
20 60 Al2O3 185
21 50 SiO2 24
22 — — 16
3. Peel force of pole piece
Selecting support layers with different Young modulus and shrinkage rates, and preparing a positive pole piece by taking a No. 7 current collector in a table 1 as a raw material; comparative example current collectors were numbered 1 ', 2 ', 3 ', and the results of the pole piece peel force test are shown in table 3 below:
TABLE 3
Figure BDA0003060571020000121
The adhesive force of the conducting layer is increased, and the stripping force of the pole piece is increased. The rolling procedure exists in the manufacturing process of the battery core, the extension rates of the support layer and the conductive layer are different, the larger the extension rate difference is, the larger the reduction range of the stripping force of the pole piece is.
4. Needle prick test
A battery was prepared using the current collector No. 7 in table 1 as the positive electrode current collector, and the temperature and voltage change of the battery were monitored, as shown in fig. 5, with the abscissa as time, the left-side ordinate as temperature, the right-side ordinate as voltage, the time point when the needle penetrated the battery was 31300ms on the abscissa, and the time point when the needle penetrated the battery was 468800ms on the abscissa. The full-power battery has no smoke and fire phenomena, the voltage is always maintained above 3.9V, the needle temperature is less than 35 ℃, and the battery surface temperature is less than 20 ℃.
The current collectors 1-22 are used as positive current collectors to prepare batteries, in a nail penetration test, the temperature of the batteries rises below 10 ℃, the temperature of a needle rises below 20 ℃, the voltage of the batteries is basically kept stable, and the batteries work normally.
5. Capacity retention after charge and discharge cycling of a battery comprising a current collector sample
The current collector No. 7 in the table 1 is used as a positive current collector to prepare a ternary battery, the positive current collector of the conventional current collector is an aluminum foil, and the negative electrode of the conventional current collector is a copper foil. The capacity retention after N charges and discharges (averaged in three parallel tests) is shown in table 4 below:
TABLE 4
Figure BDA0003060571020000122
Figure BDA0003060571020000131
The battery using the current collector sample of the embodiment as the positive current collector has a good cycle life, and compared with a conventional battery containing an aluminum foil positive current collector, the capacity retention rate is slightly improved after N times of charge and discharge cycles, which indicates that the reliability of the battery is better.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the technical principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims (11)

1. A current collector, comprising:
the supporting layer is a high polymer film with the Young modulus of 5-30 GPa and the shrinkage rate of not more than 1% at 90 ℃ for 12 hours, and is provided with a first surface and a second surface which are opposite;
and the conducting layer is arranged on the first surface and/or the second surface of the supporting layer.
2. The current collector of claim 1, further comprising:
and the bonding layer is arranged between the supporting layer and the conductive layer, and the main composition of the bonding layer is alloy and/or solid oxide.
3. The current collector of claim 1, further comprising: the anti-oxidation layer is arranged on the surface, opposite to the supporting layer, of the conductive layer; the main composition of the bonding layer is solid oxide.
4. The current collector of claim 1, wherein:
the high molecular polymer film is a single layer or a composite film with more than two layers; the high polymer material of the supporting layer is at least one selected from polyethylene terephthalate, polyimide, polypropylene, polyethylene and polyethylene naphthalate;
the conducting layer is a metal layer or mainly comprises metal; the metal of the conductive layer is at least one selected from aluminum, copper, tin and zinc.
5. The current collector of claim 1, wherein the support layer has a thickness of 2-20 μm and the conductive layer has a thickness of 200-2500 nm.
6. The current collector of claim 2, wherein the bonding layer has a thickness of 10-60 nm, and the solid oxide of the bonding layer is at least one selected from the group consisting of aluminum oxide and silicon dioxide.
7. The current collector of claim 3, wherein the thickness of the antioxidation layer is 10-50 nm, and the solid oxide of the antioxidation layer is at least one selected from the group consisting of aluminum oxide and silicon dioxide.
8. The current collector of claim 2, wherein the adhesion layer is attached to the surface of the support layer by evaporation or sputtering, and/or the conductive layer is attached to the surface of the adhesion layer by evaporation or sputtering.
9. A pole piece, comprising a current collector and an active material layer disposed on the current collector, wherein the current collector is the current collector of any one of claims 1 to 8.
10. A battery comprising a positive electrode plate, a negative electrode plate, a separator and an electrolyte, wherein the positive electrode plate and/or the negative electrode plate comprises the current collector of any one of claims 1 to 8.
11. A device comprising the battery of claim 10.
CN202110511808.6A 2021-05-11 2021-05-11 Current collector, pole piece, battery and equipment Pending CN113422062A (en)

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CN114361463A (en) * 2021-12-17 2022-04-15 合肥国轩高科动力能源有限公司 Preparation method of composite current collector
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CN114122410A (en) * 2021-11-18 2022-03-01 合肥国轩高科动力能源有限公司 Multilayer net-shaped current collector of lithium ion battery and manufacturing method thereof
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CN114497568A (en) * 2021-12-13 2022-05-13 上海兰钧新能源科技有限公司 Heat-shrinkable composite current collector and application thereof
CN114497568B (en) * 2021-12-13 2024-01-30 上海兰钧新能源科技有限公司 Heat-shrinkable composite current collector and application thereof
CN114361463A (en) * 2021-12-17 2022-04-15 合肥国轩高科动力能源有限公司 Preparation method of composite current collector
CN114300689A (en) * 2022-01-13 2022-04-08 华中科技大学 Current collector, lithium ion battery and preparation method of lithium ion battery
CN114613932A (en) * 2022-03-24 2022-06-10 深圳吉阳智能科技有限公司 Pole piece structure and battery
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WO2024000804A1 (en) * 2022-06-29 2024-01-04 扬州纳力新材料科技有限公司 High-weldability composite current collector and preparation method therefor
CN116247222A (en) * 2023-05-08 2023-06-09 宁德时代新能源科技股份有限公司 Current collector, pole piece, electrode assembly, battery monomer, battery and electric equipment

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