WO2020220732A1 - 负极集流体、负极极片、电化学装置及装置 - Google Patents
负极集流体、负极极片、电化学装置及装置 Download PDFInfo
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- WO2020220732A1 WO2020220732A1 PCT/CN2020/070453 CN2020070453W WO2020220732A1 WO 2020220732 A1 WO2020220732 A1 WO 2020220732A1 CN 2020070453 W CN2020070453 W CN 2020070453W WO 2020220732 A1 WO2020220732 A1 WO 2020220732A1
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- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/362—Composites
- H01M4/366—Composites as layered products
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- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
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- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
- H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
- H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
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- H01M4/66—Selection of materials
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- H01M4/00—Electrodes
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- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/64—Carriers or collectors
- H01M4/66—Selection of materials
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- H—ELECTRICITY
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- 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
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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
- 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
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- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
- H01M2004/027—Negative electrodes
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- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
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- 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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- 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
Definitions
- the application belongs to the technical field of electrochemical devices, and specifically relates to a negative electrode current collector, a negative electrode piece, an electrochemical device and a device.
- Secondary batteries represented by lithium-ion secondary batteries are widely used in electric vehicles and consumer electronic products due to their advantages of high energy density, high output power, long cycle life and low environmental pollution. With the continuous expansion of the application range of secondary batteries, people have put forward higher and higher requirements for the energy density of secondary batteries. Therefore, how to further increase the energy density of the secondary battery has become an urgent technical problem to be solved.
- the inventor has conducted a lot of research aimed at improving the traditional current collector so that it can reduce its own weight while having good electrical conductivity and current collection performance, thereby providing both high weight energy density and good integration Electrochemical device with electrochemical performance.
- the first aspect of the present application provides a negative electrode current collector, which includes a support layer and a conductive layer disposed on at least one of two opposite surfaces in the thickness direction of the support layer, wherein,
- the density of the support layer is less than the density of the conductive layer
- the thickness D 1 of the conductive layer satisfies 300 nm ⁇ D 1 ⁇ 2 ⁇ m, preferably 500 nm ⁇ D 11 ⁇ 1.5 ⁇ m;
- the sheet resistance growth rate T of the conductive layer is ⁇ 5%, preferably ⁇ 2.5%.
- a second aspect of the present application provides a negative electrode sheet, which includes a negative current collector and a negative active material layer disposed on the negative current collector, wherein the negative current collector is the negative current collector of the first aspect of the present application.
- the third aspect of the present application provides an electrochemical device, which includes a positive pole piece, a negative pole piece and an electrolyte, wherein the negative pole piece is the negative pole piece as in the second aspect of the present application.
- the fourth aspect of the present application provides a device including the electrochemical device as in the third aspect of the present application.
- the negative electrode current collector provided by the present application includes a support layer with a lower density and a conductive layer with a reduced thickness. Therefore, compared with the existing metal current collector, the weight of the negative electrode current collector is significantly reduced, thereby obtaining weight energy An electrochemical device with significantly improved density. Moreover, when the tensile strain of the negative electrode current collector is 1.5%, the sheet resistance growth rate of the conductive layer T ⁇ 5%, thereby preventing the resistance of the conductive layer with a smaller thickness from increasing sharply due to tensile deformation, thereby ensuring The negative electrode current collector can maintain good electrical conductivity and current collecting performance during further processing and use in the electrochemical device.
- the negative electrode current collector or negative electrode piece provided in the present application enables the electrochemical device using it to have low impedance and small negative electrode polarization, so that the electrochemical device has good electrochemical performance such as rate performance, cycle performance and kinetic performance. Therefore, by using the negative electrode current collector or negative electrode piece of the present application, the electrochemical device provided by the present application can simultaneously take into account a high weight energy density and good comprehensive electrochemical performance.
- the device of the present application includes the electrochemical device provided by the present application, and thus has at least the same advantages as the electrochemical device.
- Fig. 1 shows a schematic structural diagram of a negative electrode current collector provided in an embodiment of the present application.
- FIG. 2 shows a schematic structural diagram of a negative electrode current collector provided by another embodiment of the present application.
- FIG. 3 shows a schematic structural diagram of a negative electrode current collector provided by another embodiment of the present application.
- FIG. 4 shows a schematic structural diagram of a negative electrode current collector provided by another embodiment of the present application.
- FIG. 5 shows a schematic structural diagram of a negative electrode current collector provided by another embodiment of the present application.
- FIG. 6 shows a schematic structural diagram of a negative electrode current collector provided by another embodiment of the present application.
- FIG. 7 shows a schematic structural diagram of a negative electrode current collector provided by another embodiment of the present application.
- FIG. 8 shows a schematic structural diagram of a negative electrode current collector provided by another embodiment of the present application.
- FIG. 9 shows a schematic structural diagram of a negative electrode current collector provided by another embodiment of the present application.
- FIG. 10 shows a schematic structural diagram of a negative pole piece provided by an embodiment of the present application.
- FIG. 11 shows a schematic structural diagram of a negative pole piece provided by another embodiment of the present application.
- Fig. 12 is a schematic diagram of a secondary battery provided by an embodiment of the present application.
- FIG. 13 is a schematic diagram of a battery module provided by an embodiment of the present application.
- FIG. 14 is a schematic diagram of a battery pack provided by an embodiment of the present application.
- Fig. 15 is an exploded view of Fig. 14.
- Fig. 16 is a schematic diagram of a device provided by an embodiment of the present application.
- any lower limit may be combined with any upper limit to form an unspecified range; and any lower limit may be combined with other lower limits to form an unspecified range, and any upper limit may be combined with any other upper limit to form an unspecified range.
- every point or single value between the end points of the range is included in the range. Therefore, each point or single numerical value can be used as its own lower limit or upper limit in combination with any other point or single numerical value or in combination with other lower or upper limits to form an unspecified range.
- the first aspect of the present application provides a negative electrode current collector, which, compared with the traditional metal copper foil negative electrode current collector, can simultaneously take into account low weight and good electrical conductivity and current collection performance.
- Fig. 1 schematically shows a negative electrode current collector 10 as an example.
- the negative electrode current collector 10 includes a supporting layer 101 and a conductive layer 102 that are stacked, wherein the supporting layer 101 has a first surface 101a and a second surface 101b opposed to each other in its thickness direction, and the conductive layer 102 is laminated It is arranged on the first surface 101a and the second surface 101b of the support layer 101.
- FIG. 2 schematically shows the anode current collector 10 as another example.
- the negative electrode current collector 10 includes a supporting layer 101 and a conductive layer 102 that are stacked, wherein the supporting layer 101 has a first surface 101a and a second surface 101b opposite in the thickness direction thereof, and the conductive layer 102 is laminated It is arranged on the first surface 101 a of the supporting layer 101.
- the conductive layer 102 may also be laminated on the second surface 101b of the support layer 101.
- the density of the support layer 101 is less than the density of the conductive layer 102; the thickness D 1 of the conductive layer 102 satisfies 300 nm ⁇ D 1 ⁇ 2 ⁇ m.
- the negative electrode current collector 10 of the embodiment of the present application includes a support layer 101 with a lower density and a conductive layer 102 with a reduced thickness provided on at least one of the first surface 101a and the second surface 101b of the support layer 101. Therefore, the negative electrode The weight of the current collector 10 itself is significantly reduced, so that an electrochemical device with a significantly improved weight energy density can be obtained.
- the sheet resistance growth rate T of the conductive layer 102 is ⁇ 5%.
- the negative electrode current collector 10 is often stretched during the processing of the negative electrode piece and the use of the electrochemical device, such as rolling or expansion of the electrode piece, thereby generating tensile strain.
- the sheet resistance growth rate T of the conductive layer 102 is less than or equal to 5%, which can effectively prevent the resistance of the conductive layer 102 with a smaller thickness from increasing sharply due to tensile deformation. This ensures that the negative electrode current collector 10 can maintain good electrical conductivity and current collecting performance after further processing and during the use of the electrochemical device.
- Such a negative electrode current collector 10 enables the resulting electrochemical device to have low impedance and small negative electrode polarization, thereby having good electrochemical performance such as rate performance, cycle performance and kinetic performance.
- the use of the negative electrode current collector 10 of the present application can enable the electrochemical device to have both high weight energy density and good overall electrochemical performance.
- the sheet resistance growth rate T of the conductive layer 102 is less than or equal to 2.5%.
- the sheet resistance growth rate T of the conductive layer 102 can be measured by a method known in the art. As an example, take the negative electrode collector 10 was cut into a sample 20mm ⁇ 200mm, the central region of the test sample using the four probe method the sheet resistance of the recording is R 1; then using a tensile tester (Instron U.S. (an Instron) The company’s Instron 3365 tensile testing machine) stretches the central area of the sample and sets the initial position so that the central area of the sample with a length of 50mm is clamped between the clamps and stretched at a speed of 50mm/min.
- a tensile tester Instron U.S. (an Instron) The company’s Instron 3365 tensile testing machine
- An exemplary method of using the four-probe method to test the square resistance of the sample is as follows: using the RTS-9 double-electric four-probe tester, the test environment is: normal temperature 23 ⁇ 2° C., 0.1 MPa, and relative humidity ⁇ 65%. During the test, clean the surface of the sample, and then place it on the test bench horizontally; put down the four probes so that the probes are in good contact with the surface of the sample; then adjust the automatic test mode to calibrate the current range of the sample to a suitable current range Measure the sheet resistance, and collect 8 to 10 data points of the same sample as data measurement accuracy and error analysis. Finally, the average value is recorded as the sheet resistance value of the sample.
- the thickness D 2 of the support layer 101 satisfies 1 ⁇ m ⁇ D 2 ⁇ 20 ⁇ m.
- the thickness D 2 of the support layer 101 is suitable for making the support layer 101 have sufficient mechanical strength, is not prone to breakage during processing and use, has a good support and protection effect on the conductive layer 102, and ensures that the negative electrode current collector 10 is good
- the mechanical stability and working stability enable the negative electrode current collector 10 to have a relatively long service life.
- the support layer 101 with an appropriate thickness is also beneficial to make the electrochemical device have a smaller volume and weight, thereby increasing the energy density of the electrochemical device.
- the thickness D 2 of the support layer 101 may be ⁇ 20 ⁇ m, ⁇ 18 ⁇ m, ⁇ 15 ⁇ m, ⁇ 12 ⁇ m, ⁇ 10 ⁇ m, or ⁇ 8 ⁇ m, and the thickness D 2 of the support layer 101 may be ⁇ 1 ⁇ m, ⁇ 1.5 ⁇ m, ⁇ 2 ⁇ m, ⁇ 3 ⁇ m, ⁇ 4 ⁇ m, ⁇ 5 ⁇ m, ⁇ 6 ⁇ m, or ⁇ 7 ⁇ m.
- the overall weight of the negative electrode current collector 10 can be reduced as much as possible while ensuring that the negative electrode current collector 10 has good mechanical stability and working stability.
- the volume resistivity of the support layer 101 is greater than or equal to 1.0 ⁇ 10 -5 ⁇ m. Due to the large volume resistivity of the support layer 101, under abnormal conditions such as nail penetration, the short-circuit resistance of the electrochemical device when an internal short circuit occurs can be increased, thereby improving the safety performance of the electrochemical device.
- the volume resistivity of the support layer 101 is the volume resistivity at 20° C., which can be measured by methods known in the art.
- the test is carried out in a constant temperature, normal pressure and low humidity room (20°C, 0.1MPa, RH ⁇ 20%), and a sample of the wafer support layer 101 with a diameter of 20mm is prepared (the sample size can be adjusted according to the actual size of the test instrument),
- the test adopts the three-electrode surface resistivity method (GB T 1410-2006), and the insulation resistance tester (precision 10 ⁇ ) is used.
- the test method is as follows: Place the wafer sample between two electrodes, and apply a potential difference between the two electrodes, the current generated will be distributed in the body of the wafer sample and measured by a picoammeter or electrometer , In order to avoid the measurement error caused by including the surface leakage current in the measurement.
- the reading is the volume resistivity in ⁇ m.
- the elongation at break of the support layer 101 is greater than or equal to the elongation at break of the conductive layer 102. This can better prevent the negative electrode current collector 10 from breaking.
- the elongation at break of the support layer 101 is greater than or equal to 5%.
- the elongation at break of the support layer 101 is greater than or equal to 10%.
- the elongation at break can be measured using methods known in the art. As an example, take the support layer 101 and cut it into a 15mm ⁇ 200mm sample; use a tensile testing machine (such as Instron3365 tensile testing machine) under normal temperature and pressure (25°C, 0.1MPa) for tensile testing, and set the initial position to make the fixture The length of the sample between is 50mm, the tensile speed is 50mm/min, the device displacement y (mm) at the time of tensile fracture is recorded, and the elongation at break is calculated as (y/50) ⁇ 100%.
- the elongation at break of the conductive layer 102 can be conveniently measured by the same method.
- the Young's modulus E of the support layer 101 is greater than or equal to 4 GPa.
- the Young's modulus E of the support layer 101 is suitable to make it have appropriate rigidity, which can satisfy the support function of the support layer 101 to the conductive layer 102 and ensure the overall strength of the negative electrode current collector 10.
- the support layer 101 will not be excessively stretched or deformed.
- the support layer 101 with appropriate Young's modulus is not prone to breakage, and it is also beneficial to improve the firmness of the bonding between the support layer 101 and the conductive layer 102, so that it is not easy to detach, thereby ensuring that the negative electrode current collector 10 has a high mechanical performance. Stability and working stability.
- Such a negative electrode current collector 10 enables the resulting electrochemical device to have higher electrochemical performance, such as a longer cycle life.
- the Young's modulus E of the support layer 101 satisfies 4GPa ⁇ E ⁇ 20GPa. This makes the support layer 101 rigid and capable of withstanding deformation.
- the support layer 101 has flexibility for winding during further processing and use, which can better prevent the occurrence of tape breakage.
- a tensile testing machine such as Instron 3365 tensile force
- normal temperature and pressure 25
- the bonding strength F between the support layer 101 and the conductive layer 102 is ⁇ 100 N/m, more preferably ⁇ 400 N/m.
- the support layer 101 and the conductive layer 102 are firmly bonded, which can effectively exert the support function of the support layer 101 on the conductive layer 102, and ensure the working stability of the negative electrode current collector 10.
- the bonding strength F between the support layer 101 and the conductive layer 102 can be tested using methods known in the art.
- the negative current collector 10 with the conductive layer 102 disposed on one side of the support layer 101 is selected as the sample to be tested, and the width d is 0.02 m.
- the bonding strength between the layer 102 and the support layer 101 is F (N/m).
- the support layer 101 includes one or more of polymer materials. Since the density of the polymer material is significantly reduced, the weight of the negative electrode current collector 10 can be significantly reduced, thereby increasing the weight energy density of the electrochemical device.
- the polymer material may include polyamides, polyimides, polyesters, polyolefins, polyalkynes, siloxane polymers, polyethers, polyols, polysulfones, and One of carbohydrate polymers, amino acid polymers, polysulfur nitrides, aromatic ring polymers, aromatic heterocyclic polymers, epoxy resins, phenolic resins, their derivatives, their cross-linked products, and their copolymers Or multiple.
- Polyamides can be selected from polycaprolactam (commonly known as nylon 6), polyhexamethylene adipamide (commonly known as nylon 66), polyparaphenylene terephthalamide (PPTA), polyisophthalamide isophthalamide Amine (PMIA); polyesters can be selected from polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), poly Carbonate (PC); polyolefins can be selected from polyethylene (PE), polypropylene (PP), polypropylene (PPE), polyvinyl alcohol (PVA), polystyrene (PS), polyvinyl chloride (PVC) , Polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTEE), polystyrene sodium sulfonate (PSS); polyacetylenes such as polyacetylene; siloxane polymers such as silicone rubber; polyethers can be Selected from polyoxy
- the support layer 101 uses one or more of insulating polymer materials.
- the volume resistivity of the support layer 101 is relatively high, which can reach 1.0 ⁇ 10 9 ⁇ m or more, which can better improve the safety performance of the electrochemical device.
- the support layer 101 may include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polystyrene sulfonate One or more of sodium (PSS) and polyimide (PI).
- PET polyethylene terephthalate
- PBT polybutylene terephthalate
- PEN polyethylene naphthalate
- PSS polystyrene sulfonate
- PSS polystyrene sulfonate
- PSS polystyrene sulfonate
- the support layer 101 can have a predetermined volume resistivity, elongation at break and Young's modulus by adjusting the chemical composition, molecular weight and distribution, chain structure and chain construction, aggregated structure, phase structure, additives, etc. of the polymer material. , In order to achieve the purpose of improving the mechanical performance and electrochemical performance of electrochemical devices.
- the support layer 101 may further include additives.
- the volume resistivity, elongation at break, and Young's modulus can be adjusted by additives.
- the additives may include one or more of metallic materials and inorganic non-metallic materials.
- the metal material additive may be selected from one or more of aluminum, aluminum alloy, copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, iron, iron alloy, silver, and silver alloy.
- the inorganic non-metallic material additives can be selected from one or more of carbon-based materials, alumina, silicon dioxide, silicon nitride, silicon carbide, boron nitride, silicate and titanium oxide, and for example, glass materials, One or more of ceramic materials and ceramic composite materials.
- the carbon-based material can be selected from one or more of graphite, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
- the additive may be a carbon-based material coated with a metal material.
- a carbon-based material coated with a metal material For example, one or more of nickel-coated graphite powder and nickel-coated carbon fiber.
- the support layer 101 can be a single-layer structure as shown in FIGS. 1 and 2, or a composite layer structure with more than two layers, such as two layers, three layers, four layers, etc. .
- the negative electrode current collector 10 shown in FIG. 3 is an example of the supporting layer 101 including a composite layer structure.
- the supporting layer 101 is a composite layer structure formed by stacking a first sublayer 1011, a second sublayer 1012, and a third sublayer 1013.
- the support layer 101 of the composite layer structure has a first surface 101a and a second surface 101b opposite to each other, and the conductive layer 102 is stacked on the first surface 101a and the second surface 101b of the support layer 101.
- the conductive layer 102 may only be provided on the first surface 101a or the second surface 101b of the support layer 101.
- the materials of each sublayer may be the same or different.
- the thickness D 1 of the conductive layer 102 satisfies 300 nm ⁇ D 1 ⁇ 2 ⁇ m.
- the thickness of the conductive layer 102 is greatly reduced compared with the thickness of a traditional metal copper foil current collector, and the density of the support layer 101 is less than that of the conductive layer 102, so the weight energy density of the electrochemical device can be significantly improved.
- the conductive layer 102 with an appropriate thickness can also ensure that the negative electrode current collector 10 has good electrical conductivity and current collecting performance, so that the negative electrode current collector 10 has good mechanical stability and working stability and a higher service life to ensure electrochemistry.
- the device has good electrochemical performance.
- the thickness D 1 of the conductive layer 102 may be ⁇ 2 ⁇ m, ⁇ 1.8 ⁇ m, ⁇ 1.5 ⁇ m, ⁇ 1.2 ⁇ m, ⁇ 1 ⁇ m, or ⁇ 900 nm; the thickness D 1 of the conductive layer 102 may be ⁇ 800 nm, ⁇ 700 nm, ⁇ 600nm, ⁇ 500nm, ⁇ 450nm, ⁇ 400nm, ⁇ 350nm or ⁇ 300nm.
- the volume resistivity of the conductive layer 102 is 1.3 ⁇ 10 -8 ⁇ m to 1.3 ⁇ 10 -7 ⁇ m.
- the conductive layer 102 with appropriate volume resistivity enables the negative electrode current collector 10 to have good conductivity and current collection performance.
- the use of such a negative electrode current collector 10 enables the electrochemical device to have low impedance and reduced negative electrode polarization, so that the electrochemical device has higher rate performance and cycle performance.
- the volume resistivity of the conductive layer 102 is 1.3 ⁇ 10 -8 ⁇ m to 3.3 ⁇ 10 -8 ⁇ m, more preferably 1.65 ⁇ 10 -8 ⁇ m to 3.3 ⁇ 10 -8 ⁇ m.
- An exemplary method for testing the sheet resistance R S of the conductive layer 102 by using the four-probe method is as follows: Use the RTS-9 double-electric four-probe tester, and the test environment is: normal temperature 23 ⁇ 2°C, 0.1MPa, relative humidity ⁇ 65%.
- the conductive layer 102 includes a metal material.
- the metal material may include one or more of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, and preferably includes one of copper, copper alloy, nickel, nickel alloy, titanium and silver Or multiple.
- the weight percentage of the copper element in the copper alloy is preferably 90 wt% or more.
- the nickel alloy may include a nickel copper alloy.
- the conductive layer 102 is a metal conductive layer.
- the conductive layer 102 may further include one or more of a carbon-based conductive material and a conductive polymer material.
- the weight percentage of one or more of the carbon-based conductive material and the conductive polymer material in the conductive layer 102 is preferably 10 wt% or less.
- the carbon-based conductive material may include one or more of graphite, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
- the conductive polymer material may include one or more of polysulfur nitrides, aliphatic conjugated polymers, aromatic ring conjugated polymers, and aromatic heterocyclic conjugated polymers.
- the aliphatic conjugated polymer is, for example, polyacetylene; the aromatic ring conjugated polymer is, for example, polyphenylene, polynaphthalene, and the polyphenylene is, for example, polyparaphenylene;
- the aromatic heterocyclic conjugated polymer is, for example, polypyrrole, polyaniline, poly Thiophene, polypyridine.
- it can also be modified by doping to improve the conductivity of the conductive polymer material.
- the negative electrode current collector 10 may further optionally include a protective layer.
- the protective layer may be disposed between the conductive layer 102 and the supporting layer 101.
- the protective layer 103 may be disposed on the surface of the conductive layer 102 facing away from the support layer 101.
- a protective layer may be provided between the conductive layer 102 and the support layer 101 and the surface of the conductive layer 102 facing away from the support layer 101.
- the protective layer can protect the conductive layer 102 and prevent the conductive layer 102 from being damaged by chemical corrosion or mechanical damage.
- Such a negative electrode current collector 10 has high working stability and service life, which is beneficial to improving the electrochemical performance of the electrochemical device.
- the protective layer can also enhance the mechanical strength of the negative electrode current collector 10.
- the protective layer may include one or more of metal, metal oxide, and conductive carbon.
- the metal used for the protective layer may include one or more of nickel, chromium, nickel-based alloys, and copper-based alloys.
- the nickel-based alloy is an alloy formed by adding one or more other elements to pure nickel as a matrix, preferably a nickel-chromium alloy.
- Nickel-chromium alloy is an alloy formed by metallic nickel and metallic chromium.
- the weight ratio of nickel to chromium in the nickel-chromium alloy is 1:99 to 99:1, such as 9:1.
- the copper-based alloy is an alloy composed of pure copper and one or more other elements added as a matrix, preferably a nickel-copper alloy.
- the weight ratio of nickel to copper in the nickel-copper alloy is 1:99-99:1, such as 9:1.
- the metal oxide used for the protective layer may include one or more of aluminum oxide, cobalt oxide, chromium oxide, and nickel oxide.
- the conductive carbon used in the protective layer may include one or more of graphite, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers, and preferably includes carbon black , Carbon nanotubes, acetylene black and one or more of graphene.
- the protective layer is preferably metal or metal oxide, that is, a metal protective layer or a metal oxide protective layer is provided on the conductive layer 102.
- the metal protective layer and the metal oxide protective layer have high corrosion resistance, high hardness, large specific surface area, and high comprehensive performance.
- FIGS. 4 and 5 show some examples of the anode current collector 10 including the protective layer 103.
- the negative electrode current collector 10 includes a supporting layer 101, a conductive layer 102, and a protective layer 103 that are stacked.
- the support layer 101 has a first surface 101a and a second surface 101b opposite in its thickness direction.
- the conductive layer 102 is laminated and disposed on at least one of the first surface 101a and the second surface 101b of the support layer 101.
- the protective layer The layer 103 is arranged on the surface of the conductive layer 102 facing away from the support layer 101.
- a protective layer 103 (referred to as an upper protective layer for short) is provided on the surface of the conductive layer 102 facing away from the support layer 101 to protect the conductive layer 102 from chemical corrosion and mechanical damage.
- the metal protective layer or metal oxide protective layer can not only protect the conductive layer 102, but also improve the interface between the negative electrode current collector 10 and the negative electrode active material layer, and improve the bonding between the negative electrode current collector 10 and the negative electrode active material layer. strength.
- the upper protective layer is preferably a metal protective layer.
- the metal protective layer can reduce the interface resistance between the negative electrode current collector 10 and the negative electrode active material layer, thereby reducing the pole piece polarization and improving the electrochemical performance of the electrochemical device.
- FIGS. 6 and 7 show other examples of the anode current collector 10 including the protective layer 103.
- the negative electrode current collector 10 includes a supporting layer 101, a conductive layer 102, and a protective layer 103 that are stacked.
- the support layer 101 has a first surface 101a and a second surface 101b opposed to each other in its thickness direction.
- the conductive layer 102 is laminated on at least one of the first surface 101a and the second surface 101b of the support layer 101.
- the protective layer 103 The laminate is arranged between the conductive layer 102 and the support layer 101.
- a protective layer 103 (referred to as a lower protective layer for short) is provided between the conductive layer 102 and the support layer 101, and the two opposite surfaces of the lower protective layer are connected to the conductive layer 102 and the support layer 101 respectively, which is beneficial to improve the conductivity of the conductive layer 102. It supports and protects the conductive layer 102 and protects the conductive layer 102 from chemical corrosion and mechanical damage. In addition, the lower protection layer can also enhance the bonding strength between the support layer 101 and the conductive layer 102. Therefore, the lower protective layer is preferably a metal protective layer or a metal oxide protective layer.
- the negative electrode current collector 10 includes a supporting layer 101, a conductive layer 102, and a protective layer 103 that are stacked.
- the support layer 101 has a first surface 101a and a second surface 101b opposed to each other in its thickness direction.
- the conductive layer 102 is laminated on at least one of the first surface 101a and the second surface 101b of the support layer 101, and A protective layer 103 is provided between the conductive layer 102 and the supporting layer 101 and on the surface of the conductive layer 102 facing away from the supporting layer 101.
- the protective layer 103 is provided on both sides of the conductive layer 102 to more fully protect the conductive layer 102.
- the materials of the protective layers 103 on both sides of the conductive layer 102 can be the same or different, and the thicknesses can be the same or different.
- the thickness D 3 of the protective layer 103 satisfies 1 nm ⁇ D 3 ⁇ 200 nm, and D 3 ⁇ 0.1D 1 .
- the thickness D 3 of the protective layer 103 may be ⁇ 200nm, ⁇ 180nm, ⁇ 150nm, ⁇ 120nm, ⁇ 100nm, ⁇ 80nm, ⁇ 60nm, ⁇ 55nm, ⁇ 50nm, ⁇ 45nm, ⁇ 40nm, ⁇ 30nm, or ⁇ 20nm.
- the thickness D 3 of the protective layer 103 may be ⁇ 1 nm, ⁇ 2 nm, ⁇ 5 nm, ⁇ 8 nm, ⁇ 10 nm, ⁇ 12 nm, ⁇ 15 nm, or ⁇ 18 nm.
- 5nm ⁇ D 3 ⁇ 200nm Preferably 5nm ⁇ D 3 ⁇ 200nm, more preferably 10nm ⁇ D 3 ⁇ 200nm.
- the thickness of the protective layer 103 is suitable to enable it to effectively protect the conductive layer 102 while ensuring that the electrochemical device has a higher energy density.
- the thickness of the protective layer satisfies D a 1nm ⁇ D a ⁇ 200nm, and D a ⁇ 0.1D 1; thickness of the lower protective layer D b satisfies 1nm ⁇ D b ⁇ 200nm and D b ⁇ 0.1D 1 .
- the conductive layer can be formed on the support layer by at least one of mechanical rolling, bonding, vapor deposition, electroless plating, and electroplating. Among them, vapor deposition and electroplating are preferred, that is, the conductive layer is preferably a vapor deposited layer or electroplating. Floor. This can better realize the tight bonding between the conductive layer and the support layer.
- the conductive layer is formed on the support layer by a vapor deposition method.
- the conductive layer can have a lower sheet resistance growth rate when the tensile strain of the negative electrode collector is 1.5%, so as to improve the negative electrode collector.
- the electrochemical properties of the fluid are very important.
- the vapor deposition method is preferably a physical vapor deposition method.
- the physical vapor deposition method is preferably at least one of an evaporation method and a sputtering method; the evaporation method is preferably at least one of a vacuum evaporation method, a thermal evaporation method, and an electron beam evaporation method, and the sputtering method is preferably a magnetron sputtering method.
- the conductive layer can be formed by a vacuum evaporation method. Including: placing the support layer after surface cleaning treatment in a vacuum coating chamber, melting and evaporating the high-purity metal wire in the metal evaporation chamber at a high temperature of 1300°C ⁇ 2000°C, the evaporated metal passes through the cooling system in the vacuum coating chamber, and finally Deposited on the support layer to form a conductive layer.
- the protective layer can be formed on the conductive layer by at least one of a vapor deposition method, an in-situ formation method, and a coating method.
- the vapor deposition method may be the vapor deposition method as described above.
- the in-situ formation method is preferably an in-situ passivation method, that is, a method of forming a metal oxide passivation layer in situ on the metal surface.
- the coating method is preferably at least one of roll coating, extrusion coating, knife coating, and gravure coating.
- the protective layer is formed on the conductive layer by at least one of a vapor deposition method and an in-situ formation method. This is beneficial to make the conductive layer and the protective layer have a higher bonding strength, so as to better play the protective effect of the protective layer on the negative electrode current collector and ensure the working performance of the negative electrode current collector.
- the lower protective layer may be formed on the supporting layer first, and then the conductive layer is formed on the lower protective layer.
- the lower protective layer may be formed on the support layer by at least one of a vapor deposition method and a coating method, and the vapor deposition method is preferred. This is beneficial to make the lower protective layer and the support layer have a higher bonding strength.
- the conductive layer can be formed on the lower protective layer by at least one of mechanical rolling, bonding, vapor deposition, electroless plating, and electroplating, and vapor deposition and electroplating are preferred. This is beneficial to make the lower protective layer and the conductive layer have a higher bonding strength.
- the vapor deposition method and coating method may be the vapor deposition method and coating method as described above.
- the bonding strength F 1 between the conductive layer and the protective layer is ⁇ 100 N/m, more preferably ⁇ 400 N/m.
- the bonding strength F 2 between the protective layer and the supporting layer is ⁇ 100N/m, more preferably ⁇ 400N/m.
- Bonding strength between the conductive layer and the protective layer may be measured with reference to Test Method F bonding strength between the support layer and the conductive layer.
- a second aspect of the present application provides a negative electrode sheet, including a negative electrode current collector and a negative electrode active material layer that are stacked, wherein the negative electrode current collector is any one of the negative electrode current collectors of the first aspect of the application.
- the negative pole piece of the present application due to the negative electrode current collector of the present application, has a higher weight energy density and good comprehensive electrochemical performance than traditional negative pole pieces.
- FIG. 10 shows a negative pole piece 20 as an example.
- the negative electrode piece 20 includes a negative electrode current collector 10 and a negative electrode active material layer 201 that are stacked.
- the support layer 101 of the negative electrode current collector 10 has two opposite surfaces in its thickness direction, and the conductive layer 102 is laminated on the two surfaces of the support layer 101.
- the negative active material layer 201 is laminated and disposed on the surface of the conductive layer 102 of the negative current collector 10 facing away from the support layer 101.
- FIG. 11 shows a negative pole piece 20 as another example.
- the negative electrode piece 20 includes a negative electrode current collector 10 and a negative electrode active material layer 201 which are stacked.
- the support layer 101 of the negative current collector 10 has two opposite surfaces in the thickness direction thereof, and the conductive layer 102 is laminated on any one of the two surfaces of the support layer 101.
- the negative active material layer 201 is laminated on the surface of the conductive layer 102 facing away from the support layer 101.
- the anode active material layer 201 includes an anode active material.
- the negative electrode active material may be a negative electrode active material known in the art, capable of reversible intercalation/deintercalation of active ions.
- the negative electrode active material used in lithium ion secondary batteries may include metallic lithium, natural graphite, artificial graphite, mesophase micro-carbon spheres (MCMB), hard carbon, soft carbon, silicon, silicon-carbon composite, SiO , Li-Sn alloy, Li-Sn-O alloy, Sn, SnO, SnO2, spinel structure lithium titanate and one or more of Li-Al alloy.
- the negative active material layer 201 may further include a conductive agent.
- the conductive agent may include one or more of graphite, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
- the negative active material layer 201 may further include a binder.
- the binder may include styrene butadiene rubber (SBR), water-based acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer One or more of (EVA), polyvinyl alcohol (PVA) and polyvinyl butyral (PVB).
- the negative active material layer 201 may further include a thickener.
- the thickener may include sodium carboxymethyl cellulose (CMC-Na).
- the negative pole piece can be prepared according to conventional methods in the art. Generally, the negative electrode active material and optional conductive agent, binder and thickener are dispersed in a solvent.
- the solvent can be NMP or deionized water to form a uniform negative electrode slurry.
- the negative electrode slurry is coated on the negative electrode current collector After drying and other processes, the negative pole piece is obtained.
- a third aspect of the present application provides an electrochemical device.
- the electrochemical device includes a positive pole piece, a negative pole piece and an electrolyte, wherein the negative pole piece is any one of the negative pole pieces of the second aspect of the application.
- Examples of the electrochemical device include a battery, a battery module including the battery, and a battery pack including the battery.
- Examples of the battery may be a primary battery, a secondary battery, or the like.
- Specific examples of batteries include, but are not limited to, lithium ion secondary batteries, lithium primary batteries, sodium ion batteries, magnesium ion batteries, and the like.
- the electrochemical device of the present application adopts the negative pole piece according to the second aspect of the present application, so that it can have a higher weight energy density and good comprehensive electrochemical performance.
- the positive pole piece may include a positive current collector and a positive active material layer disposed on the positive current collector.
- the positive electrode current collector has two opposite surfaces in its thickness direction, and the positive electrode active material layer is laminated and disposed on either or both of the two opposite surfaces of the positive electrode current collector.
- the positive electrode current collector can be selected from metal foil, carbon-coated metal foil, and porous metal foil.
- the positive electrode current collector may include one or more of aluminum, aluminum alloy, copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy.
- the positive electrode active material layer includes a positive electrode active material, which can adopt a positive electrode active material known in the art, and can perform reversible intercalation/deintercalation of active ions.
- the positive active material for lithium ion secondary batteries may include lithium transition metal composite oxides, where the transition metal may be Mn, Fe, Ni, Co, Cr, Ti, Zn, V, Al, Zr, Ce, and Mg. One or more of.
- the lithium transition metal composite oxide can also be doped with elements with high electronegativity, such as one or more of S, F, Cl, and I. This enables the positive electrode active material to have higher structural stability and electrochemical performance.
- the cathode active material may include LiMn 2 O 4 , LiNiO 2 , LiCoO 2 , LiNi 1-y Co y O 2 (0 ⁇ y ⁇ 1), LiNi a Co b Al 1-ab O 2 (0 ⁇ a ⁇ 1, 0 ⁇ b ⁇ 1, 0 ⁇ a+b ⁇ 1), LiMn 1-mn Ni m Co n O 2 (0 ⁇ m ⁇ 1, 0 ⁇ n ⁇ 1, 0 ⁇ m+n ⁇ 1), LiMPO 4 (M may be one or more of Fe, Mn, and Co) and one or more of Li 3 V 2 (PO 4 ) 3 .
- the positive active material layer may further include a binder.
- the binder may include styrene butadiene rubber (SBR), water-based acrylic resin, sodium carboxymethyl cellulose (CMC-Na), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene- One or more of vinyl acetate copolymer (EVA), polyvinyl alcohol (PVA) and polyvinyl butyral (PVB).
- the positive active material layer may further include a conductive agent.
- the conductive agent may include one or more of graphite, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
- the positive pole piece can be prepared according to conventional methods in the art. Generally, the positive electrode active material, optional conductive agent and binder are dispersed in a solvent (such as N-methylpyrrolidone, referred to as NMP) to form a uniform positive electrode slurry, and the positive electrode slurry is coated on the positive electrode current collector After drying and other processes, the positive pole piece is obtained.
- a solvent such as N-methylpyrrolidone, referred to as NMP
- the electrolyte can be a solid electrolyte or a non-aqueous electrolyte.
- the electrolyte includes an organic solvent and an electrolyte salt.
- the organic solvent is used as a medium for transporting ions in the electrochemical reaction, and it can use organic solvents known in the art for electrochemical device electrolyte.
- the electrolyte salt serves as a source of ions, and electrolyte salts known in the art for use in electrolytic solutions of electrochemical devices can be used.
- organic solvents used in lithium ion secondary batteries may include ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate ( DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethylene propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF) , Methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), diethyl sulfone
- electrolyte salts used in lithium ion secondary batteries may include LiPF 6 (lithium hexafluorophosphate), LiBF 4 (lithium tetrafluoroborate), LiClO 4 (lithium perchlorate), LiAsF 6 (lithium hexafluoroarsenate), LiFSI (double Lithium fluorosulfonimide), LiTFSI (lithium bistrifluoromethanesulfonimide), LiTFS (lithium trifluoromethanesulfonate), LiDFOB (lithium difluorooxalate), LiBOB (lithium dioxalate), LiPO 2 One or more of F 2 (lithium difluorophosphate), LiDFOP (lithium difluorodioxalate phosphate) and LiTFOP (lithium tetrafluorooxalate phosphate).
- LiPF 6 lithium hexafluorophosphate
- LiBF 4 lithium tetrafluoroborate
- the electrolyte may also optionally include additives, where there is no specific restriction on the type of additives, and can be selected according to requirements.
- the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain properties of electrochemical devices, such as additives that improve overcharge performance of electrochemical devices, and additives that improve high-temperature performance of electrochemical devices. , Additives to improve the low temperature performance of electrochemical devices, etc.
- a separator is arranged between the positive pole piece and the negative pole piece to play a role of isolation.
- the isolation membrane may be a single-layer or multi-layer film containing one or more of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride.
- the electrochemical device may be a battery.
- the battery may include an outer package for packaging the positive pole piece, the negative pole piece and the electrolyte.
- the positive pole piece, the negative pole piece and the separator can be laminated or wound to form an electrode assembly with a laminated structure or an electrode assembly with a wound structure (also called a battery), and the electrode assembly is packaged in an outer package;
- the electrolyte can be an electrolyte, and the electrolyte is immersed in the electrode assembly.
- the number of electrode assemblies in the battery can be one or several, which can be adjusted according to requirements.
- the outer packaging of the battery may be a soft bag, such as a pouch type soft bag.
- the material of the soft bag can be plastic, for example, it can include one or more of polypropylene PP, polybutylene terephthalate PBT, polybutylene succinate PBS, and the like.
- the outer packaging of the battery can also be a hard shell, such as an aluminum shell.
- Fig. 12 shows a battery 5 with a square structure as an example.
- the batteries can be assembled into battery modules, and the number of batteries contained in the battery module can be multiple, and the specific number can be adjusted according to the application and capacity of the battery module.
- FIG. 13 shows the battery module 4 as an example.
- a plurality of batteries 5 may be arranged in sequence along the length direction of the battery module 4. Of course, it can also be arranged in any other manner. Furthermore, the plurality of batteries 5 can be fixed by fasteners.
- the battery module 4 may also optionally include a housing having an accommodation space, and a plurality of batteries 5 are accommodated in the accommodation space.
- the above-mentioned battery modules can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be adjusted according to the application and capacity of the battery pack.
- the battery pack 1 may include a battery box and a plurality of battery modules 4 provided in the battery box.
- the battery box includes an upper box body 2 and a lower box body 3.
- the upper box body 2 can be covered on the lower box body 3 and forms a closed space for accommodating the battery module 4.
- Multiple battery modules 4 can be arranged in the battery box in any manner.
- the fourth aspect of the present application provides a device including the electrochemical device of the third aspect of the present application.
- the electrochemical device can be used as a power source for the device or as an energy storage unit of the device.
- the device can be, but is not limited to, mobile devices (such as mobile phones, laptop computers, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf Vehicles, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.
- the device can select different electrochemical devices, such as batteries, battery modules, or battery packs, according to its usage requirements.
- Fig. 16 is a device as an example.
- the device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle.
- battery packs or battery modules can be used.
- the device may be a mobile phone, a tablet computer, a notebook computer, etc.
- the device is generally required to be thin and light, and a secondary battery can be used as a power source.
- a support layer of predetermined thickness Place the support layer after surface cleaning treatment in a vacuum coating chamber, and melt and evaporate the high-purity copper wire in the metal evaporation chamber at a high temperature of 1300°C ⁇ 2000°C. After the cooling system in the vacuum coating chamber, it is finally deposited on the two surfaces of the support layer to form a conductive layer.
- the negative electrode active material graphite, conductive carbon black, thickener sodium carboxymethyl cellulose (CMC-Na), and binder styrene butadiene rubber emulsion (SBR) are mixed in an appropriate amount at a weight ratio of 96.5:1.0:1.0:1.5.
- the ionized water is fully stirred and mixed to form a uniform negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and the negative electrode sheet is obtained after drying and other processes.
- the difference from the preparation method of the negative pole piece of the present application is that the negative electrode current collector adopts an 8 ⁇ m thick copper foil.
- the positive electrode active material LiNi 1/3 Co 1/3 Mn 1/3 O 2 (NCM333), conductive carbon black, and binder polyvinylidene fluoride (PVDF) are added to an appropriate amount of N in a weight ratio of 93:2:5.
- -Methylpyrrolidone (NMP) solvent is fully stirred and mixed to form a uniform positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and the positive electrode pieces are obtained after drying and other processes.
- Ethylene carbonate (EC) and ethyl methyl carbonate (EMC) with a volume ratio of 3:7 are uniformly mixed to obtain an organic solvent, and then 1 mol/L LiPF 6 is uniformly dissolved in the above organic solvent.
- the separator uses a PP/PE/PP composite film, which is located between the positive pole piece and the negative pole piece. Play the role of isolation, inject the above-mentioned electrolyte into the battery cell, and then go through the steps of sealing, standing, hot and cold pressing, and forming to obtain a lithium ion secondary battery.
- the volume resistivity of the support layer, the sheet resistance growth rate T of the conductive layer when the tensile strain of the negative electrode current collector is 1.5%, and the Young's modulus E of the support layer are respectively tested using the aforementioned test methods.
- the capacity retention rate (%) of the lithium ion secondary battery after 1,000 cycles of 1C/1C is equal to the discharge capacity of the 1,000th cycle/the discharge capacity of the first cycle ⁇ 100%.
- Lithium ion secondary battery 4C rate capacity retention rate (%) 4C rate discharge capacity/1C rate discharge capacity ⁇ 100%.
- the weight percentage of the negative electrode current collector is the weight of the negative electrode current collector per unit area divided by the weight of the conventional negative electrode current collector per unit area.
- the weight of the negative electrode current collector of the present application can be reduced to varying degrees, thereby increasing the weight energy density of the battery.
- the negative electrode current collector in Table 2 is provided with a protective layer on the basis of the negative electrode current collector 4.
- the composition of the copper alloy is 95 wt% copper and 5 wt% nickel.
- the overcurrent test method includes: cutting the positive electrode current collector into a width of 100mm, coating an active material layer of 80mm width at the center of the width direction and rolling it into a pole Cut the rolled pole pieces into strips of 100mm ⁇ 30mm along the width direction, and cut 5 pieces of each pole piece.
- the overcurrent test connect the uncoated conductive areas on both sides of the pole piece sample to the positive and negative terminals of the charging and discharging machine, and then set up the charging and discharging machine to pass a 10A current through the pole pieces, and keep the pole pieces without fuse for 1 hour. , Otherwise it is regarded as not passed. Five samples were tested in each group, and the test results are shown in Table 6.
- Negative pole piece number Negative current collector number Overcurrent test result Negative pole piece 31 Anode current collector 31 2/5 Negative pole piece 32 Anode current collector 32 4/5 Negative pole piece 33 Anode current collector 33 5/5 Negative pole piece 34 Anode current collector 34 5/5 Negative pole piece 35 Anode current collector 35 5/5 Negative pole piece 36 Anode current collector 36 5/5 Negative pole piece 37 Anode current collector 37 5/5 Compare negative pole piece Contrast negative current collector 0/5
- the sheet resistance growth rate T of the conductive layer is not more than 5%.
- the negative electrode piece using the negative electrode current collector can be rolled after rolling. Has good electrical conductivity. Otherwise, the electrical conductivity is poor, and it is of little practical value in battery products.
- the sheet resistance growth rate of the conductive layer T is 1.5%.
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Abstract
一种负极集流体(10)、负极极片(20)、电化学装置及装置,负极集流体(10)包括支撑层(101)以及设置于所述支撑层(101)自身厚度方向上相对的两个表面中的至少一者上的导电层(102);其中,所述支撑层(101)的密度小于所述导电层(102)的密度;所述导电层(102)的厚度D 1满足300nm≤D 1≤2μm,优选500nm≤D 1≤1.5μm;所述负极集流体(10)的拉伸应变为1.5%时,所述导电层(102)的方块电阻增长率T≤5%。
Description
相关申请的交叉引用
本申请要求享有于2019年04月28日提交的名称为“负极集流体、负极极片及电化学装置”的中国专利申请201910350620.0的优先权,该申请的全部内容通过引用并入本文中。
本申请属于电化学装置技术领域,具体涉及一种负极集流体、负极极片、电化学装置及装置。
以锂离子二次电池为代表的二次电池由于具备能量密度大、输出功率高、循环寿命长和环境污染小等优点,而被广泛应用于电动汽车以及消费类电子产品中。随着二次电池的应用范围不断扩大,人们对二次电池的能量密度也提出了越来越高的要求。因此,如何进一步提高二次电池的能量密度成为亟待解决的技术难题。
发明内容
本发明人发现现有的例如二次电池的电化学装置普遍采用具有较大厚度(例如18μm~30μm)和较高密度的金属集流体,以满足对于集流体的导电和集流性能的严苛要求,但是这样的金属集流体不利地降低了电池的能量密度。
本发明人进行了大量研究,旨在改善传统的集流体,以使得其在具有良好的导电和集流性能的同时,能减轻自身重量,从而提供同时兼顾较高的重量能量密度及良好的综合电化学性能的电化学装置。
因此,本申请的第一方面提供一种负极集流体,负极集流体包括支撑层以及设置于支撑层自身厚度方向上相对的两个表面中的至少一者上的导电层,其中,
支撑层的密度小于导电层的密度;
导电层的厚度D
1满足300nm≤D
1≤2μm,优选500nm≤D
11≤1.5μm;
负极集流体的拉伸应变为1.5%时,导电层的方块电阻增长率T≤5%,优选≤2.5%。
本申请的第二方面提供一种负极极片,其包括负极集流体以及设置于负极集流体上的负极活性材料层,其中负极集流体为如本申请第一方面的负极集流体。
本申请的第三方面提供一种电化学装置,其包括正极极片、负极极片和电解质,其中负极极片为如本申请第二方面的负极极片。
本申请的第四方面提供一种装置,其包括如本申请第三方面的电化学装置。
本申请所提供的负极集流体包含密度较小的支撑层和厚度减小的导电层,因此相较于现有的金属集流体来说,负极集流体自身的重量显著降低,从而能得到重量能量密度显著提高的电化学装置。并且,当负极集流体的拉伸应变为1.5%时,导电层的方块电阻增长率T≤5%,从而防止较小厚度的导电层因拉伸形变而导致的电阻急剧增大,由此保证负极集流体在经过进一步加工和在电化学装置的使用过程中,能够保持良好的导电和集流的性能。本申请提供的负极集流体或负极极片使得使用其的电化学装置具有低阻抗且负极极化小,从而使电化学装置兼具良好的倍率性能、循环性能和动力学性能等电化学性能。因此,采用本申请的负极集流体或负极极片,本申请提供的电化学装置能同时兼顾较高的重量能量密度及良好的综合电化学性能。
本申请的装置包括本申请提供的电化学装置,因而至少具有与所述电化学装置相同的优势。
为了更清楚地说明本申请实施例的技术方案,下面将对本申请实施例中所需要使用的附图作简单地介绍,对于本领域普通技术人员来讲,在不付出创造性劳动的前提下,还可以根据这些附图获得其他的附图。
图1示出了本申请一个实施例提供的负极集流体的结构示意图。
图2示出了本申请另一个实施例提供的负极集流体的结构示意图。
图3示出了本申请另一个实施例提供的负极集流体的结构示意图。
图4示出了本申请另一个实施例提供的负极集流体的结构示意图。
图5示出了本申请另一个实施例提供的负极集流体的结构示意图。
图6示出了本申请另一个实施例提供的负极集流体的结构示意图。
图7示出了本申请另一个实施例提供的负极集流体的结构示意图。
图8示出了本申请另一个实施例提供的负极集流体的结构示意图。
图9示出了本申请另一个实施例提供的负极集流体的结构示意图。
图10示出了本申请一个实施例提供的负极极片的结构示意图。
图11示出了本申请另一个实施例提供的负极极片的结构示意图。
图12是本申请一个实施例提供的二次电池的示意图。
图13是本申请一个实施例提供的电池模块的示意图。
图14是本申请一个实施例提供的电池包的示意图。
图15是图14的分解图。
图16是本申请一个实施例提供的装置的示意图。
为了使本申请的发明目的、技术方案和有益技术效果更加清晰,以下结合实施例对本申请进行进一步详细说明。应当理解的是,本说明书中描述的实施例仅仅是为了解释本申请,并非为了限定本申请。
为了简便,本文仅明确地公开了一些数值范围。然而,任意下限可以与任何上限组合形成未明确记载的范围;以及任意下限可以与其它下限组合形成未明确记载的范围,同样任意上限可以与任意其它上限组合形成未明确记载的范围。此外,尽管未明确记载,但是范围端点间的每个点或单个数值都包含在该范围内。因而,每个点或单个数值可以作为自身的下限或上限与任意其它点或单个数值组合或与其它下限或上限组合形成未明确记载的范围。
在本文的描述中,需要说明的是,除非另有说明,“以上”、“以下”为包含本数,“一种或多种”中“多种”的含义是两种以上。
本申请的上述发明内容并不意欲描述本申请中的每个公开的实施方式或每种实现方式。如下描述更具体地举例说明示例性实施方式。在整篇申请中的多处,通过一系列实施例提供了指导,这些实施例可以以各种组合形式使用。在各个实例中,列举仅作为代表性组,不应解释为穷举。
负极集流体
本申请的第一方面提供一种负极集流体,其与传统的金属铜箔负极集流体相比,可同时兼顾低重量以及良好的导电和集流的性能。
图1示意性地示出了作为一个示例的负极集流体10。如图1所示,负极集流体10包括层叠设置的支撑层101和导电层102,其中,支撑层101具有在其厚度方向上相对的第一表面101a和第二表面101b,导电层102层合设置于支撑层101的第一表面101a及第二表面101b上。
图2示意性地示出了作为另一个示例的负极集流体10。如图2所示,负极集流体10包括层叠设置的支撑层101和导电层102,其中,支撑层101具有在其厚度方向上相对的第一表面101a和第二表面101b,导电层102层合设置于支撑层101的第一表面101a上。当然,导电层102也可以是层合设置于支撑层101的第二表面101b上。
本申请的负极集流体10中,支撑层101的密度小于导电层102的密度;导电层102的厚度D
1满足300nm≤D
1≤2μm。
本申请实施例的负极集流体10包含密度较小的支撑层101和设置于支撑层101的第一表面101a和第二表面101b中的至少之一上的厚度减小的导电层102,因此负极集流体10自身的重量显著降低,从而能得到重量能量密度得到显著提高的电化学装置。
另外,当负极集流体10的拉伸应变为1.5%时,导电层102的方块电阻增长率T≤5%。负极集流体10在负极极片的加工及电化学装置的使用过程中,例如辊压或极片膨胀时,常常会被拉伸,从而产生拉伸应变。使负极集流体10在其拉伸应变为1.5%时导电层102的方块电阻增长率T≤5%,能够有效防止较小厚度的导电层102因拉伸形变而导致的电阻急剧增大,由此保证负极集流体10在经过进一步加工和在在电化学装置的使用过程中,能够保持良好的导电和集流的性能。这样的负极集流体10使得所得电化学装置具有低阻抗、且负极极化小,从而兼具良好的倍率性能、循环性能和动力学性能等电化学性能。
因此,采用本申请的负极集流体10能使电化学装置同时兼顾较高的重量能量密度及良好的综合电化学性能。
优选地,当负极集流体10的拉伸应变为1.5%时,导电层102的方块电阻增长率T≤2.5%。
负极集流体10的拉伸应变ε可以根据公式ε=ΔL/L×100%计算,其中,ΔL是负极集 流体10被拉伸产生的伸长量,L是负极集流体10的原长,即被拉伸之前的长度。
当负极集流体10的拉伸应变为1.5%时导电层102的方块电阻增长率T可以采用本领域已知的方法测定。作为示例,取负极集流体10裁剪成20mm×200mm的样品,采用四探针法测试样品的中心区域的方块电阻,记录为R
1;然后使用拉力试验机(如美国英斯特朗(Instron)公司的Instron 3365型拉力试验机)对样品的中心区域进行拉伸,设置初始位置,使样品的长度为50mm的中心区域夹持在夹具之间,以50mm/min速度进行拉伸,拉伸距离为样品原长的1.5%,即拉伸距离为0.75mm时停止;取下拉伸后的样品,测试样品经拉伸的中心区域的导电层102的方块电阻,记录为R
2;根据公式T=(R
2-R
1)/R
1×100%,计算得到负极集流体10的拉伸应变为1.5%时导电层102的方块电阻增长率T。
采用四探针法测试样品的方块电阻的示例性方法如下:使用RTS-9型双电测四探针测试仪,测试环境为:常温23±2℃,0.1MPa,相对湿度≤65%。测试时,将样品进行表面清洁,然后水平置于测试台上;将四探针放下,使探针与样品表面有良好接触;然后调节自动测试模式标定样品的电流量程,在合适的电流量程下进行方块电阻的测量,并采集相同样品的8至10个数据点作为数据测量准确性和误差分析。最后取平均值记录为样品的方块电阻值。
在一些实施例中,支撑层101的厚度D
2满足1μm≤D
2≤20μm。支撑层101的厚度D
2适于使得该支撑层101具有足够的机械强度,在加工及使用过程中不易发生断裂,对导电层102起到良好的支撑和保护作用,保证负极集流体10良好的机械稳定性和工作稳定性,使负极集流体10具有较高的使用寿命。具有适当厚度的支撑层101还有利于使电化学装置具有较小的体积及重量,从而提高电化学装置的能量密度。
在一些实施例中,支撑层101的厚度D
2可以为≤20μm、≤18μm、≤15μm、≤12μm、≤10μm、或≤8μm,支撑层101的厚度D
2可以为≥1μm、≥1.5μm、≥2μm、≥3μm、≥4μm、≥5μm、≥6μm、或≥7μm。优选1μm≤D
2≤15μm,进一步优选2μm≤D
2≤10μm,更优选2μm≤D
2≤6μm。
当支撑层101的厚度D
2满足上述要求时,能够在保证负极集流体10具有良好的机械稳定性和工作稳定性的同时,尽可能减小负极集流体10的总体重量。
在一些优选的实施例中,支撑层101的体积电阻率大于或等于1.0×10
-5Ω·m。由于支撑层101的体积电阻率较大,在穿钉等异常情况下,能够增大电化学装置发生内短路 时的短路电阻,从而提高电化学装置的安全性能。
在本文中,支撑层101的体积电阻率是在20℃时的体积电阻率,可以采用本领域已知的方法测定。作为示例,测试在恒温常压低湿度房下进行(20℃,0.1MPa,RH≤20%),制备直径为20mm的圆片支撑层101样品(样品尺寸可根据测试仪器的实际尺寸调整),测试采用三电极测表面电阻率法(GB T 1410-2006),使用绝缘电阻测试仪(精度10Ω)进行。测试方法如下:将圆片样品放置在两个电极之间,并在两个电极之间施加一个电位差,产生的电流将分布在圆片样品的体内,并由皮安计或静电计来测量,以避免因在测量中计入表面泄露电流而产生测量误差。读数即为体积电阻率,单位为Ω·m。
在一些实施例中,支撑层101的断裂伸长率大于或等于导电层102的断裂伸长率。这样能更好地防止负极集流体10发生断带。可选地,支撑层101的断裂伸长率大于或等于5%。优选地,支撑层101的断裂伸长率大于或等于10%。
断裂伸长率可以采用本领域已知的方法测定。作为一个示例,取支撑层101裁剪成15mm×200mm的样品;在常温常压(25℃、0.1MPa)下使用拉力试验机(如Instron3365型拉力试验机)进行拉伸测试,设置初始位置使夹具之间的样品长度为50mm,拉伸速度为50mm/min,记录拉伸断裂时的设备位移y(mm),最后计算断裂伸长率为(y/50)×100%。导电层102的断裂伸长率可以采用同样的方法方便地测定。
在一些优选的实施例中,支撑层101的杨氏模量E≥4GPa。支撑层101的杨氏模量E适于使得其具有适当的刚性,能满足支撑层101对导电层102的支撑作用,确保负极集流体10的整体强度。在负极集流体10的加工过程中,该支撑层101不会发生过大的延展或变形。具有适当杨氏模量的支撑层101不易发生断带,还有利于提高支撑层101和导电层102之间结合的牢固度,使其不易发生脱离,从而保证负极集流体10具有较高的机械稳定性和工作稳定性。这样的负极集流体10使所得电化学装置具有较高的电化学性能,如较长的循环寿命。
更优选地,支撑层101的杨氏模量E满足4GPa≤E≤20GPa。这使得支撑层101具有刚性的同时还具有一定的承受变形的能力。支撑层101在进一步加工及使用过程中具有进行卷绕的柔性,能更好地防止发生断带。
支撑层101的杨氏模量E可以采用本领域已知的方法测定。作为示例,取支撑层101裁剪成15mm×200mm的样品,用万分尺量取样品的厚度h(μm);在常温常压 (25℃、0.1MPa)下使用拉力试验机(如Instron 3365型拉力试验机)进行拉伸测试,设置初始位置使夹具之间的样品长度为50mm,拉伸速度为50mm/min,记录拉伸至断裂的载荷L(N),设备位移y(mm),则应力ε(GPa)=L/(15×h),应变η=y/50;绘制应力应变曲线,取初始线性区曲线,该曲线的斜率即为杨氏模量E。
优选地,支撑层101与导电层102之间的结合强度F≥100N/m,更优选≥400N/m。支撑层101与导电层102之间牢固结合,能有效地发挥支撑层101对导电层102的支撑作用,保证了负极集流体10的工作稳定性。
可以采用本领域已知的方法测试支撑层101与导电层102之间的结合强度F,例如选用导电层102设置于支撑层101一面上的负极集流体10为待测样品,宽度d为0.02m;在常温常压(25℃、0.1MPa)下,将3M双面胶均匀贴于不锈钢板上,再将待测样品均匀贴于双面胶上;使用拉力试验机(如Instron 3365型拉力试验机)将待测样品的导电层102与支撑层101以50mm/min进行180°连续剥离;根据拉力和位移的数据图,读取最大拉力x(N),根据F=x/d计算得到导电层102与支撑层101之间的结合强度F(N/m)。
在一些实施例中,支撑层101包含高分子材料中的一种或多种。由于高分子材料的密度明显减小,从而能明显减轻负极集流体10的重量,进而提高电化学装置的重量能量密度。
优选地,高分子材料可包括聚酰胺类、聚酰亚胺类、聚酯类、聚烯烃类、聚炔烃类、硅氧烷聚合物、聚醚类、聚醇类、聚砜类、多糖类聚合物、氨基酸类聚合物、聚氮化硫类、芳环聚合物、芳杂环聚合物、环氧树脂、酚醛树脂、其衍生物、其交联物和其共聚物中的一种或多种。
聚酰胺类可选自聚己内酰胺(俗称尼龙6)、聚己二酰己二胺(俗称尼龙66)、聚对苯二甲酰对苯二胺(PPTA)、聚间苯二甲酰间苯二胺(PMIA);聚酯类可选自聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚萘二甲酸乙二醇酯(PEN)、聚碳酸酯(PC);聚烯烃类可选自聚乙烯(PE)、聚丙烯(PP)、聚丙乙烯(PPE)、聚乙烯醇(PVA)、聚苯乙烯(PS)、聚氯乙烯(PVC)、聚偏氟乙烯(PVDF)、聚四氟乙烯(PTEE)、聚苯乙烯磺酸钠(PSS);聚炔烃类例如是聚乙炔;硅氧烷聚合物例如是硅橡胶;聚醚类可选自聚甲醛(POM)、聚苯醚(PPO)、聚苯硫醚(PPS);聚醇类可选自聚乙二醇(PEG);多糖类聚合物可选自纤维素、淀 粉;氨基酸类聚合物可选自蛋白质;芳环聚合物可选自聚苯,例如聚对苯撑;芳杂环聚合物可选自聚吡咯(PPy)、聚苯胺(PAN)、聚噻吩(PT)、聚吡啶(PPY);共聚物例如是丙烯腈-丁二烯-苯乙烯共聚物(ABS)。
在一些优选的实施例中,支撑层101采用绝缘高分子材料中的一种或多种。该支撑层101的体积电阻率较高,可以达到1.0×10
9Ω·m以上,能更好地提高电化学装置的安全性能。
优选地,支撑层101可包括聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚萘二甲酸乙二醇酯(PEN)、聚苯乙烯磺酸钠(PSS)及聚酰亚胺(PI)中的一种或多种。
可以通过调整高分子材料的化学组成、分子量及分布、链结构和链构筑、聚集态结构、相结构、添加剂等,使支撑层101具有预定的体积电阻率、断裂伸长率及杨氏模量,以达到改善电化学装置机械性能及电化学性能的目的。
在一些实施例中,支撑层101还可包含添加剂。通过添加剂能够调整其体积电阻率、断裂伸长率及杨氏模量等。添加剂可包括金属材料及无机非金属材料中的一种或多种。金属材料添加剂可选自铝、铝合金、铜、铜合金、镍、镍合金、钛、钛合金、铁、铁合金、银及银合金中的一种或多种。无机非金属材料添加剂可选自碳基材料、氧化铝、二氧化硅、氮化硅、碳化硅、氮化硼、硅酸盐及氧化钛中的一种或多种,再例如是玻璃材料、陶瓷材料及陶瓷复合材料中的一种或多种。碳基材料可选自石墨、超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的一种或多种。
在一些实施例中,添加剂可以是金属材料包覆的碳基材料。例如镍包覆的石墨粉及镍包覆的碳纤维中的一种或多种。
在本申请实施例的负极集流体10中,支撑层101可以是如图1和图2显示的单层结构,也可以是两层以上的复合层结构,如两层、三层、四层等。
图3所示的负极集流体10是包含复合层结构的支撑层101的一个示例。参照图3,支撑层101是由第一子层1011、第二子层1012及第三子层1013层叠设置形成的复合层结构。复合层结构的支撑层101具有相对的第一表面101a和第二表面101b,导电层102层叠设置在支撑层101的第一表面101a和第二表面101b上。当然,导电层102可以仅设置于支撑层101的第一表面101a或第二表面101b上。
当支撑层101为两层以上的复合层结构时,各子层的材料可以相同或不同。
在本申请实施例的负极集流体10中,导电层102的厚度D
1满足300nm≤D
1≤2μm。导电层102的厚度较传统的金属铜箔集流体的厚度大大减小,且支撑层101的密度小于导电层102的密度,因此可显著改善电化学装置的重量能量密度。具有适当厚度的导电层102还能够保证负极集流体10具有良好的导电和集流的性能,使负极集流体10具有良好的机械稳定性和工作稳定性及较高的使用寿命,以保证电化学装置具有良好的电化学性能。
在一些实施例中,导电层102的厚度D
1可以≤2μm、≤1.8μm、≤1.5μm、≤1.2μm、≤1μm或≤900nm;导电层102的厚度D
1可以≥800nm、≥700nm、≥600nm、≥500nm、≥450nm、≥400nm、≥350nm或≥300nm。优选500nm≤D
1≤1.5μm。这有利于使负极集流体10更好地兼顾较高的能量密度及导电性。
在一些优选的实施例中,导电层102的体积电阻率为1.3×10
-8Ω·m~1.3×10
-7Ω·m。具有适当体积电阻率的导电层102使得负极集流体10具有良好的导电和集流的性能。采用这样的负极集流体10使得电化学装置具有低阻抗,并具有减小的负极极化,从而使电化学装置具有较高的倍率性能及循环性能。优选地,导电层102的体积电阻率为1.3×10
-8Ω·m~3.3×10
-8Ω·m,更优选为1.65×10
-8Ω·m~3.3×10
-8Ω·m。
在本文中,导电层102的体积电阻率ρ为ρ=R
S×d,其中,ρ的单位为Ω·m;R
S为导电层102的方块电阻,单位为Ω;d为导电层102以m为单位的厚度。采用四探针法测试导电层102的方块电阻R
S的示例性方法如下:使用RTS-9型双电测四探针测试仪,测试环境为:常温23±2℃,0.1MPa,相对湿度≤65%。测试时,将正极集流体10样品进行表面清洁,然后水平置于测试台上;将四探针放下,使探针与样品的导电层102表面良好接触;然后调节自动测试模式标定样品的电流量程,在合适的电流量程下进行方块电阻的测量,并采集相同样品的8至10个数据点作为数据测量准确性和误差分析。最后取平均值记录为导电层102的方块电阻。
在一些实施例中,导电层102包括金属材料。金属材料可包括铜、铜合金、镍、镍合金、钛、钛合金、银及银合金中的一种或多种,优选包括铜、铜合金、镍、镍合金、钛及银中的一种或多种。铜合金中铜元素的重量百分含量优选为90wt%以上。镍合金可包括镍铜合金。
在一些实施例中,导电层102为金属导电层。
在另一些实施例中,导电层102中还可包括碳基导电材料及导电高分子材料中的一种或多种。碳基导电材料及导电高分子材料中的一种或多种在导电层102中的重量百分含量优选为10wt%以下。
碳基导电材料可包括石墨、超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯、碳纳米纤维中的一种或多种。
导电高分子材料可包括聚氮化硫类、脂肪族共轭聚合物、芳环共轭聚合物及芳杂环共轭聚合物中的一种或多种。脂肪族共轭聚合物例如是聚乙炔;芳环共轭聚合物例如是聚苯、聚萘,聚苯例如是聚对苯撑;芳杂环共轭聚合物例如是聚吡咯、聚苯胺、聚噻吩、聚吡啶。此外,还可以通过掺杂改性以提高导电高分子材料的电导率。
在一些实施例中,负极集流体10进一步可选地包括保护层。保护层可以设置于导电层102和支撑层101之间。或者,保护层103可以设置于导电层102背向支撑层101的表面。或者,可以在导电层102和支撑层101之间、以及导电层102背向支撑层101的表面均设置有保护层。保护层能保护导电层102,防止导电层102发生化学腐蚀或机械破坏等损害。这样的负极集流体10具有较高的工作稳定性及使用寿命,从而有利于改善电化学装置的电化学性能。此外,保护层还能增强负极集流体10的机械强度。
在一些实施例中,保护层可包括金属、金属氧化物及导电碳中的一种或多种。
用于保护层的金属可包括镍、铬、镍基合金及铜基合金中的一种或多种。镍基合金是以纯镍为基体加入一种或几种其他元素所构成的合金,优选为镍铬合金。镍铬合金是金属镍和金属铬形成的合金。可选的,镍铬合金中镍与铬的重量比为1:99~99:1,如9:1。铜基合金是以纯铜为基体加入一种或几种其他元素所构成的合金,优选为镍铜合金。可选的,镍铜合金中镍与铜的重量比为1:99~99:1,如9:1。
用于保护层的金属氧化物可包括氧化铝、氧化钴、氧化铬及氧化镍中的一种或多种。
用于保护层的导电碳可包括石墨、超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯、碳纳米纤维中的一种或多种,优选包括炭黑、碳纳米管、乙炔黑及石墨烯中的一种或多种。
在一些实施例中,保护层优选采用金属或金属氧化物,即在导电层102上设置金属保护层或金属氧化物保护层。金属保护层和金属氧化物保护层的耐腐蚀性能较高,且硬度高、比表面积大,具有较高的综合性能。
图4和图5示出包含保护层103的负极集流体10的一些示例。参照图4和图5,负极集流体10包括层叠设置的支撑层101、导电层102和保护层103。支撑层101具有在其厚度方向上相对的第一表面101a和第二表面101b,导电层102层合设置于支撑层101的第一表面101a及第二表面101b中的至少一者上,保护层103层合设置于导电层102的背向支撑层101的表面。
在导电层102的背向支撑层101的表面上设置保护层103(简称为上保护层),对导电层102起到防化学腐蚀、防机械破坏的保护作用。特别地,金属保护层或金属氧化物保护层既可以保护导电层102,还可以改善负极集流体10与负极活性材料层之间的界面,提高负极集流体10与负极活性材料层之间的结合强度。
进一步地,上保护层优选为金属保护层。金属保护层能降低负极集流体10与负极活性材料层之间的界面电阻,从而可降低极片极化,改善电化学装置的电化学性能。
图6和图7示出包含保护层103的负极集流体10的另一些示例。参照图6和图7,负极集流体10包括层叠设置的支撑层101、导电层102和保护层103。支撑层101具有在其厚度方向上相对的第一表面101a和第二表面101b,导电层102层叠设置于支撑层101的第一表面101a及第二表面101b中的至少一者上,保护层103层合设置于导电层102和支撑层101之间。
在导电层102和支撑层101之间设置保护层103(简称为下保护层),下保护层的相对的两个表面分别与导电层102和支撑层101连接,有利于提高对导电层102的支撑保护作用,同时对导电层102起到防化学腐蚀、防机械损害的保护作用。此外,下保护层还可以增强支撑层101与导电层102之间的结合强度。因此,下保护层优选金属保护层或金属氧化物保护层。
图8和图9示出包含保护层103的负极集流体10的又一些示例。参照图8和图9,负极集流体10包括层叠设置的支撑层101、导电层102和保护层103。支撑层101具有在其厚度方向上相对的第一表面101a和第二表面101b,导电层102层合设置于支撑层101的第一表面101a及第二表面101b中的至少一者上,并且在导电层102和支撑层101之间、以及导电层102背向支撑层101的表面上均设置有保护层103。
在导电层102的两侧均设置保护层103,能更加充分地保护导电层102。
可以理解的是,导电层102两侧的保护层103,其材料可以相同或不同,其厚度可以相同或不同。
在一些实施例中,优选地,保护层103的厚度D
3满足1nm≤D
3≤200nm、且D
3≤0.1D
1。例如,保护层103的厚度D
3可以≤200nm、≤180nm、≤150nm、≤120nm、≤100nm、≤80nm、≤60nm、≤55nm、≤50nm、≤45nm、≤40nm、≤30nm或≤20nm。进一步地,保护层103的厚度D
3可以≥1nm、≥2nm、≥5nm、≥8nm、≥10nm、≥12nm、≥15nm或≥18nm。优选5nm≤D
3≤200nm,更优选10nm≤D
3≤200nm。
保护层103的厚度适于使其起到有效保护导电层102的作用的同时,还能保证电化学装置具有较高的能量密度。
进一步地,当导电层102的两侧分别设置有上保护层和下保护层时,上保护层的厚度D
a满足1nm≤D
a≤200nm、且D
a≤0.1D
1;下保护层的厚度D
b满足1nm≤D
b≤200nm、且D
b≤0.1D
1。优选地,D
a>D
b。这有利于保护层103对导电层102起到良好的防化学腐蚀、防机械损害的保护作用,并且使电化学装置具有较高的重量能量密度。更优选地,0.5D
a≤D
b≤0.8D
a。这能够更好的发挥保护层103的作用,同时尽可能减小负极集流体10的重量。
导电层可以通过机械辊轧、粘结、气相沉积法、化学镀、电镀中的至少一种手段形成于支撑层上,其中优选气相沉积法、电镀法,即导电层优选为气相沉积层或电镀层。这样可以更好地实现导电层与支撑层之间的紧密结合。
例如,通过气相沉积法将导电层形成于支撑层上。这使得导电层与支撑层之间具有较高的结合强度,有利于提高负极集流体的机械稳定性、工作稳定性及使用寿命。通过合理调控气相沉积过程条件,如沉积温度、沉积速率、沉积室的气氛条件等,可以使负极集流体的拉伸应变为1.5%时导电层具有较低的方块电阻增长率,以改善负极集流体的电化学性能。
气相沉积法优选为物理气相沉积法。物理气相沉积法优选蒸发法及溅射法中的至少一种;蒸发法优选真空蒸镀法、热蒸发法及电子束蒸发法中的至少一种,溅射法优选磁控溅射法。
作为示例,可通过真空蒸镀法形成导电层。其中包括:将经过表面清洁处理的支撑层置于真空镀室内,以1300℃~2000℃的高温将金属蒸发室内的高纯金属丝熔化蒸发,蒸发后的金属经过真空镀室内的冷却系统,最后沉积于支撑层上,形成导电层。
保护层可以通过气相沉积法、原位形成法及涂布法中的至少一种手段形成于导电 层上。气相沉积法可以是如前文所述的气相沉积法。原位形成法优选原位钝化法,即在金属表面原位形成金属氧化物钝化层的方法。涂布法优选辊压涂布、挤压涂布、刮刀涂布及凹版涂布中的至少一种。
优选地,保护层通过气相沉积法及原位形成法中的至少一种手段形成于导电层上。这有利于使导电层与保护层之间具有较高的结合强度,从而更好地发挥保护层对负极集流体的保护作用,并保证负极集流体的工作性能。
当导电层与支撑层之间设置有保护层(即下保护层)时,还可以是先将下保护层形成于支撑层上,再将导电层形成于下保护层上。下保护层可以通过气相沉积法及涂布法中的至少一种手段形成于支撑层上,其中优选气相沉积法。这有利于使下保护层与支撑层之间具有较高的结合强度。导电层可以通过机械辊轧、粘结、气相沉积法、化学镀及电镀中的至少一种手段形成于下保护层上,其中优选气相沉积法、电镀法。这有利于使下保护层与导电层之间具有较高的结合强度。其中气相沉积法及涂布法可以是如前文所述的气相沉积法及涂布法。
在一些实施例中,优选地,导电层与保护层之间的结合强度F
1≥100N/m,更优选≥400N/m。
在一些实施例中,当保护层还与支撑层相连时,优选地,保护层与支撑层之间的结合强度F
2≥100N/m,更优选≥400N/m。
导电层与保护层之间的结合强度F
1及保护层与支撑层之间的结合强度F
2可以参照上述支撑层与导电层之间的结合强度F的测试方法进行测定。
负极极片
本申请第二方面提供一种负极极片,包括层叠设置的负极集流体及负极活性材料层,其中负极集流体为本申请第一方面的任意一种负极集流体。
本申请的负极极片,由于采用了本申请的负极集流体,与传统的负极极片相比,具有较高的重量能量密度及良好的综合电化学性能。
图10示出了作为一个示例的负极极片20。如图10所示,负极极片20包括层叠设置的负极集流体10及负极活性材料层201。负极集流体10的支撑层101具有在其厚度方向相对的两个表面,导电层102层合设置于支撑层101的两个表面上。负极活性材料层201层合设置于负极集流体10的导电层102的背向支撑层101的表面上。
图11示出了作为另一个示例的负极极片20。如图11所示,负极极片20包括层叠 设置的负极集流体10及负极活性材料层201。负极集流体10的支撑层101具有在其厚度方向相对的两个表面,导电层102层合设置于支撑层101的两个表面中的任意一者上。负极活性材料层201层合设置于导电层102的背向支撑层101的表面上。
负极活性材料层201包括负极活性材料。负极活性材料可以是本领域已知的负极活性材料,能够进行活性离子的可逆嵌入/脱嵌。例如用于锂离子二次电池的负极活性材料,可包括金属锂、天然石墨、人造石墨、中间相微碳球(简写为MCMB)、硬碳、软碳、硅、硅-碳复合物、SiO、Li-Sn合金、Li-Sn-O合金、Sn、SnO、SnO2、尖晶石结构的钛酸锂及Li-Al合金中的一种或多种。
在一些实施例中,负极活性材料层201还可包括导电剂。作为示例,导电剂可包括石墨、超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中一种或多种。
在一些实施例中,负极活性材料层201还可包括粘结剂。作为示例,粘结剂可包括丁苯橡胶(SBR)、水性丙烯酸树脂(water-based acrylic resin)、聚偏二氟乙烯(PVDF)、聚四氟乙烯(PTFE)、乙烯-醋酸乙烯酯共聚物(EVA)、聚乙烯醇(PVA)及聚乙烯醇缩丁醛(PVB)中的一种或多种。
在一些实施例中,负极活性材料层201还可包括增稠剂。增稠剂可包括羧甲基纤维素钠(CMC-Na)。
负极极片可按照本领域常规方法制备。通常将负极活性材料以及可选的导电剂、粘结剂及增稠剂分散于溶剂中,溶剂可以是NMP或去离子水,形成均匀的负极浆料,将负极浆料涂覆在负极集流体上,经烘干等工序后,得到负极极片。
电化学装置
本申请的第三方面提供一种电化学装置,电化学装置包括正极极片、负极极片和电解质,其中负极极片为本申请第二方面的任意一种负极极片。
电化学装置的实施例包括电池、包含所述电池的电池模块、包含所述电池的电池包。电池的实施例可以是一次电池、二次电池等。电池的具体实施例包括,但不限于,锂离子二次电池、锂一次电池、钠离子电池、镁离子电池等。
本申请的电化学装置采用根据本申请第二方面的负极极片,从而能够具有更高的重量能量密度及良好的综合电化学性能。
在一些实施例中,正极极片可包括正极集流体及设置于正极集流体上的正极活性 材料层。例如,正极集流体具有在自身厚度方向相对的两个表面,正极活性材料层层合设置于正极集流体相对的两个表面中的任意一者或两者上。
在一些实施例中,正极集流体可选自金属箔材、涂炭金属箔材及多孔金属箔材。正极集流体可包括铝、铝合金、铜、铜合金、镍、镍合金、钛、钛合金、银及银合金中的一种或多种。
正极活性材料层包括正极活性材料,其可采用本领域已知的正极活性材料,能够进行活性离子的可逆嵌入/脱嵌。例如用于锂离子二次电池的正极活性材料可包括锂过渡金属复合氧化物,其中过渡金属可以是Mn、Fe、Ni、Co、Cr、Ti、Zn、V、Al、Zr、Ce及Mg中的一种或多种。锂过渡金属复合氧化物中还可以掺杂电负性大的元素,如S、F、Cl及I中的一种或多种。这能使正极活性材料具有较高的结构稳定性和电化学性能。
作为示例,正极活性材料可包括LiMn
2O
4、LiNiO
2、LiCoO
2、LiNi
1-yCo
yO
2(0<y<1)、LiNi
aCo
bAl
1-a-bO
2(0<a<1,0<b<1,0<a+b<1)、LiMn
1-m-nNi
mCo
nO
2(0<m<1,0<n<1,0<m+n<1)、LiMPO
4(M可以为Fe、Mn、Co中的一种或多种)及Li
3V
2(PO
4)
3中的一种或多种。
在一些实施例中,正极活性材料层还可包括粘结剂。作为示例,粘结剂可包括丁苯橡胶(SBR)、水性丙烯酸树脂、羧甲基纤维素钠(CMC-Na)、聚偏二氟乙烯(PVDF)、聚四氟乙烯(PTFE)、乙烯-醋酸乙烯酯共聚物(EVA)、聚乙烯醇(PVA)及聚乙烯醇缩丁醛(PVB)中的一种或多种。
在一些实施例中,正极活性材料层还可包括导电剂。作为示例,导电剂可包括石墨、超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中一种或多种。
正极极片可按照本领域常规方法制备。通常将正极活性材料以及可选的导电剂及粘结剂分散于溶剂(例如N-甲基吡咯烷酮,简称为NMP)中,形成均匀的正极浆料,将正极浆料涂覆在正极集流体上,经烘干等工序后,得到正极极片。
在一些实施例中,电解质可采用固体电解质,也可以采用非水电解液。电解液包括有机溶剂和电解质盐。有机溶剂作为在电化学反应中传输离子的介质,其可采用本领域已知的用于电化学装置电解液的有机溶剂。电解质盐作为离子的供源,其可采用本领域已知的用于电化学装置电解液的电解质盐。
例如用于锂离子二次电池的有机溶剂可包括碳酸亚乙酯(EC)、碳酸亚丙酯(PC)、碳酸甲乙酯(EMC)、碳酸二乙酯(DEC)、碳酸二甲酯(DMC)、碳酸二丙酯(DPC)、碳酸甲丙酯(MPC)、碳酸乙丙酯(EPC)、碳酸亚丁酯(BC)、氟代碳酸亚乙酯(FEC)、甲酸甲酯(MF)、乙酸甲酯(MA)、乙酸乙酯(EA)、乙酸丙酯(PA)、丙酸甲酯(MP)、丙酸乙酯(EP)、丙酸丙酯(PP)、丁酸甲酯(MB)、丁酸乙酯(EB)、1,4-丁内酯(GBL)、环丁砜(SF)、二甲砜(MSM)、甲乙砜(EMS)、二乙砜(ESE)中的一种或多种,优选为两种以上。
例如用于锂离子二次电池的电解质盐可包括LiPF
6(六氟磷酸锂)、LiBF
4(四氟硼酸锂)、LiClO
4(高氯酸锂)、LiAsF
6(六氟砷酸锂)、LiFSI(双氟磺酰亚胺锂)、LiTFSI(双三氟甲磺酰亚胺锂)、LiTFS(三氟甲磺酸锂)、LiDFOB(二氟草酸硼酸锂)、LiBOB(二草酸硼酸锂)、LiPO
2F
2(二氟磷酸锂)、LiDFOP(二氟二草酸磷酸锂)及LiTFOP(四氟草酸磷酸锂)中的一种或多种。
电解液中还可选地包括添加剂,其中对添加剂的种类没有具体的限制,可根据需求进行选择。例如添加剂可以包括负极成膜添加剂,也可以包括正极成膜添加剂,还可以包括能够改善电化学装置某些性能的添加剂,例如改善电化学装置过充性能的添加剂、改善电化学装置高温性能的添加剂、改善电化学装置低温性能的添加剂等。
电化学装置采用电解液时,在正极极片和负极极片之间设置隔离膜,起到隔离的作用。对隔离膜没有特别的限制,可以选用任意公知的具有化学稳定性和机械稳定性的多孔结构隔离膜。隔离膜可以是包含玻璃纤维、无纺布、聚乙烯、聚丙烯及聚偏二氟乙烯中的一种或多种的单层或多层薄膜。
在一些实施例中,电化学装置可以是电池。电池可包括外包装,用于封装正极极片、负极极片和电解质。作为示例,正极极片、负极极片和隔离膜可经叠片或卷绕形成叠片结构的电极组件或卷绕结构的电极组件(也可称为电芯),电极组件封装在外包装内;电解质可采用电解液,电解液浸润于电极组件中。电池中电极组件的数量可以为一个或几个,可根据需求来调节。
在一些实施例中,电池的外包装可以是软包,例如袋式软包。软包的材质可以是塑料,如可包括聚丙烯PP、聚对苯二甲酸丁二醇酯PBT、聚丁二酸丁二醇酯PBS等中的一种或几种。电池的外包装也可以是硬壳,例如铝壳等。
本申请对电池的形状没有特别的限制,其可以是圆柱形、方形或其他任意的形状。如图12是作为一个示例的方形结构的电池5。
在一些实施例中,电池可以组装成电池模块,电池模块所含电池的数量可以为多 个,具体数量可根据电池模块的应用和容量来调节。
图13是作为一个示例的电池模块4。参照图13,在电池模块4中,多个电池5可以是沿电池模块4的长度方向依次排列设置。当然,也可以按照其他任意的方式进行排布。进一步可以通过紧固件将该多个电池5进行固定。
电池模块4还可选地包括具有容纳空间的壳体,多个电池5容纳于该容纳空间。
在一些实施例中,上述电池模块还可以组装成电池包,电池包所含电池模块的数量可以根据电池包的应用和容量进行调节。
图14和图15是作为一个示例的电池包1。参照图14和图15,在电池包1中可以包括电池箱和设置于电池箱中的多个电池模块4。电池箱包括上箱体2和下箱体3,上箱体2能够盖设于下箱体3,并形成用于容纳电池模块4的封闭空间。多个电池模块4可以按照任意的方式排布于电池箱中。
装置
本申请第四方面提供一种装置,所述装置包括本申请第三方面的电化学装置,所述电化学装置可以用作所述装置的电源,也可以作为所述装置的能量存储单元。所述装置可以但不限于是移动设备(例如手机、笔记本电脑等)、电动车辆(例如纯电动车、混合动力电动车、插电式混合动力电动车、电动自行车、电动踏板车、电动高尔夫球车、电动卡车等)、电气列车、船舶及卫星、储能系统等。所述装置可以根据其使用需求来选择不同的电化学装置,如电池、电池模块或电池包。
图16是作为一个示例的装置。该装置为纯电动车、混合动力电动车、或插电式混合动力电动车等。为了满足该装置对电化学装置高功率和高能量密度的需求,可采用电池包或电池模块。
作为另一个示例的装置可以是手机、平板电脑、笔记本电脑等。该装置通常要求轻薄化,可采用二次电池作为电源。
实施例
下述实施例更具体地描述了本申请公开的内容,这些实施例仅仅用于阐述性说明,因为在本申请公开内容的范围内进行各种修改和变化对本领域技术人员来说是明显的。除非另有声明,以下实施例中所报道的所有份、百分比、和比值都是基于重量计,而且实施例中使用的所有试剂都可商购获得或是按照常规方法进行合成获得,并且可直接使用而无需进一步处理,以及实施例中使用的仪器均可商购获得。
制备方法
负极集流体的制备
选取预定厚度的支撑层并进行表面清洁处理,将经过表面清洁处理的支撑层置于真空镀室内,以1300℃~2000℃的高温将金属蒸发室内的高纯铜丝熔化蒸发,蒸发后的金属经过真空镀室内的冷却系统,最后沉积于支撑层的两个表面,形成导电层。
负极极片的制备
将负极活性材料石墨、导电炭黑、增稠剂羧甲基纤维素钠(CMC-Na)、粘结剂丁苯橡胶乳液(SBR)按96.5:1.0:1.0:1.5的重量比在适量的去离子水中充分搅拌混合,使其形成均匀的负极浆料;将负极浆料涂覆于负极集流体上,经烘干等工序后,得到负极极片。
常规负极极片的制备
与本申请的负极极片的制备方法不同的是,负极集流体采用8μm厚的铜箔。
正极集流体的制备
采用厚度为12μm的铝箔。
常规正极极片的制备
将正极活性材料LiNi
1/3Co
1/3Mn
1/3O
2(NCM333)、导电炭黑、粘结剂聚偏二氟乙烯(PVDF)按93:2:5的重量比在适量的N-甲基吡咯烷酮(NMP)溶剂中充分搅拌混合,使其形成均匀的正极浆料;将正极浆料涂覆于正极集流体上,经烘干等工序后,得到正极极片。
电解液的制备
将体积比为3:7的碳酸亚乙酯(EC)和碳酸甲乙酯(EMC)混合均匀,得到有机溶剂,然后将1mol/L的LiPF
6均匀溶解在上述有机溶剂中。
锂离子二次电池的制备
将正极极片、隔离膜、负极极片依次层叠设置,然后卷绕成电芯并装入外包装中,隔离膜采用PP/PE/PP复合薄膜,其处于正极极片和负极极片之间起到隔离作用,将上述电解液注入到电芯中,之后经过密封、静置、热冷压、化成等工序,得到锂离子二次电池。
测试部分
1.负极集流体的测试
支撑层的体积电阻率、负极集流体的拉伸应变为1.5%时导电层的方块电阻增长率T、以及支撑层的杨氏模量E等分别采用前文所述的测试方法进行测试。
2.电池的性能测试
(1)循环性能测试
在45℃,将锂离子二次电池以1C的倍率恒流充电至4.2V,再恒压充电至电流小于等于0.05C,再以1C的倍率恒流放电至2.8V,此为一个充放电循环,此次的放电容量即为第1次循环的放电容量。将电池按照上述方法进行1000次充放电循环,记录第1000次循环的放电容量。
锂离子二次电池1C/1C循环1000次后的容量保持率(%)=第1000次循环的放电容量/第1次循环的放电容量×100%。
(2)倍率性能测试
在25℃,将锂离子二次电池以1C倍率恒流充电至4.2V,再恒压充电至电流≤0.05C,再以1C倍率恒流放电至3.0V,测试得到锂离子二次电池1C倍率放电容量。
在25℃,将锂离子二次电池以1C倍率恒流充电至4.2V,再恒压充电至电流≤0.05C,再以4C倍率恒流放电至3.0V,测试得到锂离子二次电池4C倍率放电容量。
锂离子二次电池4C倍率容量保持率(%)=4C倍率放电容量/1C倍率放电容量×100%。
测试结果
1.本申请负极集流体在改善电化学装置的重量能量密度方面的作用
表1
表1中,负极集流体重量百分数是单位面积负极集流体重量除以单位面积常规负极 集流体重量的百分数。
相较于传统的铜箔负极集流体,采用本申请的负极集流体的重量都得到不同程度的减轻,从而可提升电池的重量能量密度。
2.本申请的负极集流体对于电化学装置的电化学性能方面的作用
表2
表2中的负极集流体是在负极集流体4的基础上设置保护层。
表3
表4
由表4可知,采用本申请实施例负极集流体的电池的循环寿命及倍率性能良好,与采用常规负极集流体电池的循环性能及倍率性能相当。这说明采用本申请实施例的负极集流体不会对负极极片和电池的电化学性能有明显的不利影响。尤其是设置有保护层的负极集流体制成的电池,45℃、1C/1C循环1000次后的容量保持率及4C倍率容量保持率进一步获得提升,说明电池的可靠性更好。
3.负极集流体的拉伸电阻增长率对电化学装置的影响
表5
表5中,铜合金的成分为:铜95wt%,镍5wt%。
对表5中的正极集流体进行过流测试,过流测试的方法包括:将正极集流体剪裁成 100mm幅宽,在幅宽方向正中的位置涂布80mm宽的活性物质层并辊压制作成极片,将辊压后的极片沿幅宽方向剪裁成100mm×30mm的长条,每种极片剪裁5条。测试时,将极片样品两侧无涂膜的导电区分别连接到充放电机的正负极端,随后设置充放电机,使10A电流通过极片,保持1h极片不发生熔断即为通过测试,否则视为不通过。每组样品测试五个,测试结果示于表6。
表6
负极极片编号 | 负极集流体编号 | 过流测试结果 |
负极极片31 | 负极集流体31 | 2/5 |
负极极片32 | 负极集流体32 | 4/5 |
负极极片33 | 负极集流体33 | 5/5 |
负极极片34 | 负极集流体34 | 5/5 |
负极极片35 | 负极集流体35 | 5/5 |
负极极片36 | 负极集流体36 | 5/5 |
负极极片37 | 负极集流体37 | 5/5 |
对比负极极片 | 对比负极集流体 | 0/5 |
由表5和表6可知,负极集流体的拉伸应变为1.5%时导电层的方块电阻增长率T不大于5%,此时,采用该负极集流体的负极极片在辊压之后,可以具有较好的导电性能。否则导电性能较差,在电池产品中实用价值不大。优选的,负极集流体的拉伸应变为1.5%时导电层的方块电阻增长率T≤2.5%。
以上所述,仅为本申请的具体实施方式,但本申请的保护范围并不局限于此,任何熟悉本技术领域的技术人员在本申请揭露的技术范围内,可轻易想到各种等效的修改或替换,这些修改或替换都应涵盖在本申请的保护范围之内。因此,本申请的保护范围应以权利要求的保护范围为准。
Claims (14)
- 一种负极集流体,包括支撑层以及设置于所述支撑层自身厚度方向上相对的两个表面中的至少一者上的导电层,其中,所述支撑层的密度小于所述导电层的密度;所述导电层的厚度D 1满足300nm≤D 1≤2μm,优选500nm≤D 1≤1.5μm;所述负极集流体的拉伸应变为1.5%时,所述导电层的方块电阻增长率T≤5%,优选≤2.5%。
- 根据权利要求1所述的负极集流体,其中,所述导电层的体积电阻率为1.3×10 - 8Ω·m~1.3×10 -7Ω·m,优选为1.3×10 -8Ω·m~3.3×10 -8Ω·m,更优选为1.65×10 -8Ω·m~3.3×10 -8Ω·m。
- 根据权利要求1或2所述的负极集流体,其中,所述导电层包括金属材料,所述金属材料包括铜、铜合金、镍、镍合金、钛及银中的一种或多种。
- 根据权利要求1至3任一项所述的负极集流体,其中,所述负极集流体还包括保护层;所述保护层设置于所述导电层和所述支撑层之间,和/或,所述保护层设置于所述导电层背向所述支撑层的表面。
- 根据权利要求4所述的负极集流体,其中,所述保护层包含金属和金属氧化物材料中的一种或多种,优选包含镍、铬、镍基合金、铜基合金、氧化铝、氧化钴、氧化铬及氧化镍中的一种或多种。
- 根据权利要求4或5所述的负极集流体,其中,所述保护层的厚度D 3满足1nm≤D 3≤200nm、且D 3≤0.1D 1。
- 根据权利要求1至6任一项所述的负极集流体,其中,所述支撑层的厚度D 2满足1μm≤D 2≤20μm,优选2μm≤D 2≤10μm,更优选2μm≤D 2≤6μm。
- 根据权利要求1至7任一项所述的负极集流体,其中,所述支撑层包含高分子材料中的一种或多种;优选地,所述高分子材料选自聚酰胺、聚酰亚胺、聚对苯二甲酸乙二醇酯、聚对苯二甲酸丁二醇酯、聚萘二甲酸乙二醇酯、聚碳酸酯、聚乙烯、聚丙烯、聚丙乙烯、丙烯腈-丁二烯-苯乙烯共聚物、聚乙烯醇、聚苯乙烯、聚氯乙烯、聚偏氟乙烯、聚四氟 乙烯、聚苯乙烯磺酸钠、聚乙炔、硅橡胶、聚甲醛、聚苯醚、聚苯硫醚、聚乙二醇、聚氮化硫类高分子材料、聚苯、聚吡咯、聚苯胺、聚噻吩、聚吡啶、纤维素、淀粉、蛋白质、环氧树脂、酚醛树脂、其衍生物、其交联物及其共聚物中的一种或多种。
- 根据权利要求8所述的负极集流体,其中,所述支撑层还包含添加剂,所述添加剂包括金属材料及无机非金属材料中的一种或多种。
- 根据权利要求1至9任一项所述的负极集流体,其中,所述支撑层的断裂伸长率大于或等于所述导电层的断裂伸长率;和/或,所述支撑层的杨氏模量E≥4GPa,优选4GPa≤E≤20GPa。
- 根据权利要求1至10任一项所述的负极集流体,其中,所述导电层为气相沉积层或电镀层。
- 一种负极极片,包括负极集流体以及设置于所述负极集流体上的负极活性材料层,其中所述负极集流体为如权利要求1至11任一项所述的负极集流体。
- 一种电化学装置,包括正极极片、负极极片和电解质,其中所述负极极片为如权利要求12所述的负极极片。
- 一种装置,包括权利要求13所述的电化学装置。
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JP2020187929A (ja) * | 2019-05-15 | 2020-11-19 | 株式会社アルバック | リチウムイオン二次電池用負極の集電体 |
JP2020187932A (ja) * | 2019-05-15 | 2020-11-19 | 株式会社アルバック | リチウムイオン二次電池用負極の集電体の製造方法 |
CN111682218B (zh) * | 2020-05-14 | 2021-10-29 | 超威电源集团有限公司 | 一种增强型含炭材料的集流体及其制备方法 |
CN112510206A (zh) * | 2020-10-16 | 2021-03-16 | 江苏卓高新材料科技有限公司 | 一种集流体及具有该集流体的电池、物体 |
CN113066989A (zh) * | 2021-03-23 | 2021-07-02 | 珠海冠宇电池股份有限公司 | 一种集流体以及包含该集流体的极片和电化学装置 |
CN114695839A (zh) | 2021-03-29 | 2022-07-01 | 宁德新能源科技有限公司 | 电化学装置和电子装置 |
CN114335557B (zh) * | 2021-11-30 | 2023-07-14 | 蜂巢能源科技有限公司 | 复合箔材及制备方法、集流体和锂离子电池 |
CN114188545A (zh) * | 2021-12-07 | 2022-03-15 | 珠海冠宇电池股份有限公司 | 一种集流体和电池及电子设备 |
CN114284504B (zh) * | 2021-12-22 | 2023-11-28 | 上海恩捷新材料科技有限公司 | 复合集流体及其制备方法、其极片和电池 |
WO2023135818A1 (ja) * | 2022-01-17 | 2023-07-20 | Tdk株式会社 | 集電体、蓄電デバイス用電極およびリチウムイオン二次電池、ならびに集電体の製造方法 |
WO2023135817A1 (ja) * | 2022-01-17 | 2023-07-20 | Tdk株式会社 | 集電体、蓄電デバイス用電極およびリチウムイオン二次電池、ならびに集電体の製造方法 |
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