WO2023039902A1 - 一种电化学装置和电子装置 - Google Patents

一种电化学装置和电子装置 Download PDF

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Publication number
WO2023039902A1
WO2023039902A1 PCT/CN2021/119436 CN2021119436W WO2023039902A1 WO 2023039902 A1 WO2023039902 A1 WO 2023039902A1 CN 2021119436 W CN2021119436 W CN 2021119436W WO 2023039902 A1 WO2023039902 A1 WO 2023039902A1
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current collector
collector layer
layer
conductive
conductive terminal
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PCT/CN2021/119436
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English (en)
French (fr)
Inventor
魏红梅
胡乔舒
张益博
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宁德新能源科技有限公司
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Priority to PCT/CN2021/119436 priority Critical patent/WO2023039902A1/zh
Priority to CN202180018577.3A priority patent/CN115244732A/zh
Publication of WO2023039902A1 publication Critical patent/WO2023039902A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/61—Types of temperature control
    • H01M10/615—Heating or keeping warm
    • 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
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/63—Control systems
    • 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
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/65—Means for temperature control structurally associated with the cells
    • H01M10/654—Means for temperature control structurally associated with the cells located inside the innermost case of the cells, e.g. mandrels, electrodes or electrolytes
    • 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
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/65—Means for temperature control structurally associated with the cells
    • H01M10/657—Means for temperature control structurally associated with the cells by electric or electromagnetic means
    • H01M10/6571—Resistive heaters
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/665—Composites
    • H01M4/667—Composites in the form of layers, e.g. coatings
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to the field of electrochemistry, in particular to an electrochemical device and an electronic device.
  • lithium-ion batteries Due to its high energy density, long cycle life and no memory effect, lithium-ion batteries are widely used in wearable devices, smart phones, unmanned aerial vehicles, electric vehicles and large-scale energy storage equipment. The development potential of new green chemical power sources, but also put forward higher requirements on the performance of lithium-ion batteries.
  • the purpose of the present application is to provide an electrochemical device and an electronic device to improve the performance of the electrochemical device at low temperature.
  • the first aspect of the present application provides an electrochemical device, the electrochemical device includes a pole piece, the pole piece includes a current collector, and the current collector includes a first current collector layer, an intermediate layer, a second current collector layer, a first conductive terminal and The second conductive terminal, wherein the intermediate layer is located between the first current collector layer and the second current collector layer, the first conductive terminal and the second conductive terminal form an electrical connection with the intermediate layer, between the first conductive terminal and the second conductive terminal A resistor with a resistance value R that activates the resistor when the temperature falls below a set value.
  • the above pole piece is applied to an electrochemical device.
  • the first conductive terminal and the second conductive terminal are turned on and a current is passed through, The resistor is activated, and the intermediate layer heats the electrochemical device; when the temperature of the electrochemical device reaches the heating target temperature (for example, higher than 35°C), the first conductive terminal and the second conductive terminal are disconnected, and the resistor is in an inactive state.
  • the interlayer stops heating the electrochemical device.
  • the electrochemical device can realize rapid self-heating at low temperature, improve the kinetics of the electrochemical system, reduce the polarization, effectively reduce the energy density loss of the electrochemical device, and improve the phenomenon of lithium precipitation at the negative electrode, thereby improving the electrochemical device Performance at low temperature, such as charging performance, cycle performance, etc.
  • the activatable resistor is placed in the middle layer of the current collector, without adding other components and without losing the energy density of the electrochemical device, it can achieve more uniform and efficient heating of the electrochemical device, and further improve the electrochemical device. Safety performance in fast charging environment.
  • thermosensor may be used to monitor the temperature of the electrochemical device
  • a switch may be used to control the conduction and disconnection of the first conductive terminal and the second conductive terminal.
  • the present application has no special restrictions on the material, structure, and size of the first terminal and the second terminal, as long as a closed path can be formed to achieve the purpose of the present application.
  • the electrochemical device further includes a positive pole lug and a negative pole lug, an internal resistance with a resistance value R' is provided between the positive pole lug and the negative pole lug, and the first conductive terminal and the second conductive terminal The value of the resistance R between them satisfies 5 ⁇ R/R' ⁇ 1000.
  • the inventors of the present application found that by adjusting the resistance of the current collector within the above range, it is beneficial to improve the electrochemical performance of the electrochemical device.
  • the inventors of the present application found that when the resistance value of the resistance R between the first conductive terminal and the second conductive terminal is too small, when the first conductive terminal and the second conductive terminal are heated, the intermediate layer will The heating rate of the electrochemical device is slow, resulting in a large temperature difference across the electrochemical device, which cannot effectively improve the performance of the electrochemical device at low temperatures.
  • the resistance value of the resistor R between the first conductive terminal and the second conductive terminal is too large, the flow of current will be affected, and the heating rate of the intermediate layer to the electrochemical device will also be slowed down.
  • Regulating the resistance value of the resistance R between the first conductive terminal and the second conductive terminal within the above-mentioned range is beneficial to control the heating rate of the intermediate layer to the electrochemical device in an appropriate range, thereby effectively improving the performance of the electrochemical device at low temperature. lower performance.
  • the value of the resistance R between the first conductive terminal and the second conductive terminal is 200m ⁇ to 1500m ⁇ .
  • the value of the resistance R between the first conductive terminal and the second conductive terminal may be 200m ⁇ , 400m ⁇ , 500m ⁇ , 600m ⁇ , 800m ⁇ , 1000m ⁇ , 1200m ⁇ , 1400m ⁇ , 1500m ⁇ or any range therebetween.
  • the middle layer of the current collector includes a conductive part and an insulating part, the conductive part is electrically insulated from at least a part of the first current collector layer, and the conductive part is electrically insulated from at least a part of the second current collector layer .
  • the conductive part is electrically insulated from the first current collector layer, and the conductive part is electrically insulated from the second current collector layer, the first current collector layer and the second current collector layer are electrically connected in the internal circuit of the electrochemical device.
  • the conductive part when the conductive part is electrically insulated from at least a part of the first current collector layer, and the conductive part is electrically insulated from the second current collector layer, the conductive part is also electrically connected to at least a part of the first current collector layer, The first current collector layer and the second current collector layer are electrically insulated in the internal circuit of the electrochemical device; when the conductive part forms electrical insulation with at least a part of the first current collector layer, and the conductive part and the second current collector layer When at least one part forms electrical insulation, the conductive part also forms an electrical connection with at least a part of the first current collector layer, and the conductive part forms an electrical connection with at least a part of the second current collector layer, that is, the first current collector layer and the second current collector layer
  • the layers can be electrically connected through the conductive part.
  • the conductive part when the conductive part also forms an electrical connection with at least a part of the first current collector layer, and when the conductive part forms an electrical connection with at least a part of the second current collector layer, the polarities of the first current collector and the second current collector cannot be reversed .
  • the temperature of the electrochemical device is lower than the set value (for example, lower than 10°C)
  • the conductive part is fed with current to heat the electrochemical device, and its heating uniformity good.
  • the present application has no special limitation on the set value of the temperature, which can be set by personnel in the field according to actual needs.
  • the current collector satisfies one of the following conditions (i) to (iii): (i) the conductive part is electrically insulated from the first current collector layer, and the conductive part is electrically insulated from the second current collector.
  • the layer forms electrical insulation, the first conductive terminal and the second conductive terminal are connected to the conductive part, and the polarities of the first current collector layer and the second current collector layer are the same or opposite; (ii) the conductive part forms an electrical connection with the first current collector layer , and the conductive part is electrically insulated from the second current collector layer, the first conductive terminal is connected to the first current collector layer, the second conductive terminal is connected to the conductive part, the polarity of the first current collector layer and the second current collector layer are the same or On the contrary; (iii) the conductive part is electrically connected to the first current collector layer and the second current collector layer, the first conductive terminal is connected to the conductive part or the first current collector layer, and the second conductive terminal is connected to the conductive part or the second current collector layer
  • the fluid layer, the first current collector layer and the second current collector layer have the same polarity.
  • the insulating part includes a first insulating layer and a second insulating layer, the conductive part is located between the first insulating layer and the second insulating layer, and the first current collector layer is disposed on the first insulating layer away from the conductive part.
  • the second current collector layer is arranged on the surface of the second insulating layer away from the conductive part, so as to realize the electrical insulation between the conductive part and the first current collector layer and the second current collector layer, that is, the first collector
  • the fluid layer is electrically insulated from the second current collector layer, and the first conductive terminal and the second conductive terminal are connected to the conductive part.
  • the first current collector layer and the second current collector layer can be the positive electrode current collector layer or the negative electrode current collector layer at the same time, and one of the first current collector layer and the second current collector layer can be the positive electrode current collector layer and the other is the negative electrode current collector layer.
  • the thicknesses of the first insulating layer and the second insulating layer may be the same or different. Preferably, the thicknesses of the first insulating layer and the second insulating layer are the same.
  • the present application has no special limitation on the size of the area where the conductive part is distributed in the projection plane in the thickness direction of the current collector, as long as the purpose of the application can be achieved, for example, the area of the distribution area of the conductive part is less than or equal to the first current collector layer Or the area of the second current collector layer, when the distribution area of the conductive part is smaller than the area of the first current collector layer or the second current collector layer, the distribution area of the conductive part in the current collector can be selected according to the actual situation.
  • the insulating part wraps the conductive part, thereby realizing electrical insulation between the conductive part and the first current collector layer and the second current collector layer.
  • the first conductive terminal and the second conductive terminal are connected to the conductive part and protrude from the insulating part.
  • a set value for example, lower than 10° C.
  • the first current collector layer and the second current collector layer can be the positive electrode current collector layer or the negative electrode current collector layer at the same time, and one of the first current collector layer and the second current collector layer can be the positive electrode current collector layer, and the other One is the negative current collector layer.
  • the thickness of the insulating part on both sides of the conductive part is the same or different, preferably, the thickness of the insulating part on both sides of the conductive part is the same.
  • the first conductive terminal is connected to the conductive part or the first current collector layer
  • the second conductive terminal is connected to the conductive part
  • the polarities of the first current collector layer and the second current collector layer are the same or opposite.
  • the first conductive terminal is connected to the first current collector layer
  • the second conductive terminal is connected to the conductive part.
  • the first conductive terminal is connected to the conductive part or the second current collector layer
  • the second conductive terminal is connected to the conductive part
  • the polarities of the first current collector layer and the second current collector layer are the same or opposite.
  • the first conductive terminal is connected to the second current collector layer
  • the second conductive terminal is connected to the conductive part.
  • the first current collector layer and the second current collector layer can be the positive electrode current collector layer or the negative electrode current collector layer at the same time, and one of the first current collector layer and the second current collector layer can be the positive electrode current collector layer and the other is the negative electrode current collector layer.
  • the conductive part and the first current collector layer there is an electrical connection area between the conductive part and the first current collector layer, and between the conductive part and the second current collector layer, so as to realize the connection between the conductive part and the first current collector layer and the second current collector layer.
  • the electrical connection between them that is, the electrical connection between the first current collector layer and the second current collector layer can be realized through the conductive part.
  • the first conductive terminal is connected to the conductive part or the first current collector layer
  • the second conductive terminal is connected to the conductive part or the second current collector layer.
  • the first conductive terminal is connected to the first current collector layer
  • the second conductive terminal is connected to the second current collector layer.
  • the first conductive terminal and the second conductive terminal are turned on and the current is passed through, and the conductive part heats the electrochemical device, and the heating uniformity is relatively high. good.
  • the present application has no particular limitation on the manner of forming the electrical connection area between the conductive part and the first current collector layer and the second current collector layer, as long as the purpose of the present application can be achieved, for example, the first current collector and the second current collector
  • the current collector layer and the conductive part are locally welded and connected, and the welded connection area is an electrical connection area.
  • the present application has no special limitation on the size of the electrical connection region, as long as the purpose of the present application can be achieved.
  • the conductive part may include a plurality of conductive sub-regions, and each conductive sub-region is connected with a first conductive terminal and a second conductive terminal, and the arrangement of the conductive sub-regions can satisfy different heating conditions in different regions According to requirements, the size of each conductive sub-region can be the same or different, and can be selected and designed according to the actual situation.
  • the current collector includes a through hole, and the through hole penetrates through the first current collector layer, the second current collector layer and the intermediate layer.
  • the setting of the through hole can form an ion path connecting both sides of the first current collector layer and the second current collector layer, so as to improve the ion conduction capacity of the pole piece, thereby improving the electrochemical performance of the electrochemical device.
  • the current collector satisfies one of the following conditions (iv) to (v): (iv) the through holes are filled with conductive substances, the first current collector layer and the second current collector layer The polarities are the same; (v) the through holes are filled with electrically insulated ionic conductors, the polarities of the first current collector layer and the second current collector layer are different, and there is an electric current between the first current collector layer and the second current collector layer. Sexual insulation state.
  • the electrical connection between the first current collector layer and the second current collector layer can be realized through the conductive material in the through hole, so that between the first conductive terminal and the second current collector After the two conductive terminals are turned on, the conductive part is fed with current to heat the electrochemical device, which is beneficial to heat transfer during the heating process.
  • the first current collector layer and the second current collector layer can be positive electrode current collector layer or negative electrode current collector layer at the same time.
  • the conductive substance in the through hole is electrically insulated from the conductive part, that is, the through hole is set in the area where there is only the insulating part along the thickness direction of the intermediate layer, and the through hole does not penetrate the conductive part, so as to avoid affecting the normal operation of the electrochemical device by the conductive part .
  • conductive substances may include, but are not limited to, inorganic conductive materials and/or conductive polymer materials.
  • Inorganic conductive materials may include but not limited to carbon-based conductive materials and/or metal oxides.
  • carbon-based conductive materials may include but not limited to carbon black, graphite, graphene, carbon fibers, single-walled carbon nanotubes or multi-walled nanotubes.
  • the metal oxide may include but not limited to aluminum-doped zinc oxide, calcium-doped lanthanum chromate, tin dioxide, fluorine-doped tin dioxide, antimony-doped tin dioxide, fluorine-doped tin dioxide, indium oxide At least one of tin, silver-doped indium tin oxide, silver-doped alloy indium tin oxide, and the like.
  • the conductive polymer material may include but not limited to at least one of polyacetylene, polypyrrole, polythiophene, polyparaphenylene, polyphenylene acetylene, polyaniline and doped conductive polymer materials.
  • Dopants may include, but are not limited to, chlorine, iodine, bromine, iodine chloride, iodine bromide, iodine fluoride, phosphorus pentafluoride, hydrofluoric acid, hydrochloric acid, nitric acid, sulfuric acid, perchloric acid, molybdenum pentafluoride, At least one of tungsten pentafluoride, titanium tetrachloride, zirconium tetrachloride, ferric chloride and tin tetraiodide.
  • the electrical insulation between the first current collector layer and the second current collector layer can be formed, and the connection between the first current collector layer and the second current collector layer can be formed.
  • the ion pathways on both sides can improve the ion conductivity of the pole piece, thereby improving the electrochemical performance of the electrochemical device.
  • one of the first current collector layer and the second current collector layer is a positive electrode current collector layer and the other is a negative electrode current collector layer, and the first current collector layer may be a positive electrode current collector layer, and the second current collector layer may be a negative electrode current collector layer.
  • Fluid layer it is also possible that the first current collector layer is a negative electrode current collector layer, and the second current collector layer is a positive electrode current collector layer.
  • the material of the electrically insulating ion conductor there is no particular limitation on the material of the electrically insulating ion conductor, as long as the purpose of the present application can be achieved.
  • the electrically insulating ionic conductor can be a solid electrolyte material or a mixture of an inorganic material and a binder.
  • the present application has no special restrictions on the solid electrolyte material, as long as the purpose of the present application can be achieved, for example, it may include but not limited to polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), polyvinylidene fluoride (PVDF), polyvinylidene fluoride (PVDF), polyvinylidene fluoride At least one of acrylonitrile (PAN), polymethyl methacrylate (PMMA), polyphenylene oxide (PPO), polypropylene carbonate (PPC), polyethylene oxide (PEO) and derivatives thereof.
  • PVDF-HFP polyvinylidene fluoride-hexafluoropropylene
  • PVDF polyvinylidene fluoride
  • PVDF polyvinylidene fluoride
  • PVDF polyvinylidene fluoride
  • PAN acrylonitrile
  • PMMA polymethyl methacrylate
  • PPO polyphenylene oxide
  • PPC
  • This application has no special restrictions on inorganic materials, as long as the purpose of this application can be achieved, for example, it can include but not limited to HfO 2 , SrTiO 3 , SnO 2 , CeO 2 , MgO, NiO, CaO, BaO, ZnO, ZrO 2 , Y 2 O 3 , Al 2 O 3 , TiO 2 , SiO 2 , boehmite, magnesium hydroxide, aluminum hydroxide, lithium phosphate (Li 3 PO 4 ), lithium titanium phosphate (Li x1 Ti y1 (PO 4 ) 3 , where 0 ⁇ x1 ⁇ 2 and 0 ⁇ y1 ⁇ 3), lithium aluminum titanium phosphate (Li x2 Al y2 Ti z2 (PO 4 ) 3 , where 0 ⁇ x2 ⁇ 2, 0 ⁇ y2 ⁇ 1, and 0 ⁇ z2 ⁇ 3), Li 1+x3+y3 (Al,Ga) x3 (Ti,Ge) 2-x3
  • the present application is not particularly limited to the binder, as long as the purpose of the present application can be achieved, for example, may include but not limited to polyamide, polyurethane, ethylene-vinyl acetate copolymer (EVA), ethylene-vinyl alcohol copolymer (EVOH ), acrylate, sodium sea oxalate (SA), polyacrylic acid (PAA), PVA, carboxymethyl chitosan, gelatin, polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), polyvinylidene fluoride (PVDF) At least one of polyacrylonitrile (PAN), polymethylmethacrylate (PMMA), polyphenylene oxide (PPO), polypropylene carbonate (PPC) or polyethylene oxide (PEO) and its derivatives kind.
  • PAN polyacrylonitrile
  • PMMA polymethylmethacrylate
  • PPO polyphenylene oxide
  • PPC polypropylene carbonate
  • PEO polyethylene oxide
  • the present application has no special limitation on the shape and distribution of the through holes, as long as the purpose of the present application can be achieved, for example, the shape of the through holes may include but not limited to at least one of circular, oval, triangular, square or rectangular Type, the through holes are evenly distributed or unevenly distributed in the pole piece.
  • the present application has no special limitation on the pore diameter, density and area ratio of the through holes, as long as the purpose of the present application can be achieved, for example, the pore diameter is 20 ⁇ m to 3000 ⁇ m, and the density is about 1/cm 2 to about 100/cm 2 , based on the area of the intermediate layer, the total area of the through holes accounts for 0.1% to 30%.
  • the inventors of the present application have found that at least one of the aperture, density or area ratio of the through holes is within the above range, which can improve the ion conductivity of the pole piece and will not affect the electron conduction of the pole piece. ability, which is conducive to improving the performance of electrochemical devices.
  • the distance between adjacent vias may be the same or different.
  • the conductive part has a pattern on the projected surface in the thickness direction of the conductive part, and/or the thickness of the conductive part is 5 ⁇ m to 20 ⁇ m.
  • the present application has no particular limitation on the form of the pattern, as long as the purpose of the present application can be achieved.
  • the pattern can be a uniform pattern or an uneven pattern, and the shape of the pattern can include but not limited to square wave, zigzag, etc.
  • the thickness of the conductive portion may be 5 ⁇ m, 8 ⁇ m, 10 ⁇ m, 12 ⁇ m, 15 ⁇ m, 18 ⁇ m, 20 ⁇ m or any range therebetween.
  • the inventors of the present application found that when the thickness of the conductive part is too small (for example, less than 10 ⁇ m), its mechanical properties are reduced, which affects the structural stability of the pole piece.
  • the thickness of the conductive part is too large (for example greater than 25 ⁇ m)
  • the present application has no special restrictions on the material of the insulating part, as long as the purpose of the present application can be achieved, for example, it may include but not limited to polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate Ethylene glycol formate, polyether ether ketone, polyimide, polyamide, polyethylene glycol, polyamideimide, polycarbonate, cyclic polyolefin, polyphenylene sulfide, polyvinyl acetate, poly Tetrafluoroethylene, polymethylene naphthalene, polyvinylidene fluoride, polyethylene naphthalate, polypropylene carbonate, poly(vinylidene fluoride-hexafluoropropylene), poly(vinylidene fluoride-co- - at least one of chlorotrifluoroethylene), silicone, vinylon, polypropylene, polyethylene, polyvinyl chloride, polystyrene, polyether nitrile
  • the pole piece is a positive pole piece, a negative pole piece or a composite pole piece.
  • a composite pole piece refers to a pole piece in which one of the first current collector layer and the second current collector layer is a positive electrode current collector layer, and the other is a negative electrode current collector layer.
  • the first current collector layer is a positive electrode current collector layer
  • the second current collector layer is a negative electrode current collector layer
  • the first current collector layer is a negative electrode current collector layer
  • the second current collector layer is a positive electrode current collector layer. fluid layer.
  • the present application has no particular limitation on the materials of the first current collector layer, the second current collector layer, and the conductive part, as long as the purpose of the present application can be achieved.
  • the materials of the first current collector layer, the second current collector layer, and the conductive part can independently include but not limited to Ni, Ti, Cu, Ag, Au, Pt, Fe, Co, Cr, W, Mo, Al, Mg , K, Na, Ca, Sr, Ba, Si, Ge, Sb, Pb, In, Zn and alloys thereof.
  • the thicknesses are each independently 1 ⁇ m to 8 ⁇ m.
  • the preparation method of the intermediate layer there is no particular limitation on the preparation method of the intermediate layer, as long as the purpose of the present application can be achieved.
  • the preparation method may include but not limited to the following steps: using methods such as sputtering, vacuum deposition, ion plating or laser pulse deposition to respectively arrange a first conductive layer and a second conductive layer on the two surfaces of the insulating layer;
  • the insulating layer is combined with the first conductive layer and the second conductive layer by a heat fusion method to obtain the middle layer.
  • the insulating part includes a first insulating layer and a second insulating layer, the conductive part is located between the first insulating layer and the second insulating layer, the first current collector layer is arranged on the surface of the first insulating layer away from the conductive part, and the second The current collector layer is provided on the surface of the second insulating layer away from the conductive part" as an example, and its preparation method may include but not limited to the following steps: using a coating method to respectively arrange the first insulating layer on the two surfaces of the conductive part. layer and the second insulating layer, and the middle layer is obtained after drying.
  • the preparation method of the intermediate layer containing through holes there is no particular limitation on the preparation method of the intermediate layer containing through holes, as long as the purpose of the present application can be achieved.
  • it may include but not limited to the following steps: use laser drilling method to drill holes on the intermediate layer, and then use scrap coating method to fill the slurry containing conductive substances or electrically insulating ionic conductors into the through holes , and then dried and cleaned to obtain an intermediate layer containing through holes.
  • the pattern setting method of the conductive portion on the projected surface in the thickness direction there is no particular limitation on the pattern setting method of the conductive portion on the projected surface in the thickness direction, as long as the purpose of the present application can be achieved, for example, laser cutting method.
  • the preparation method of the pole piece there is no special limitation on the preparation method of the pole piece, as long as the purpose of this application can be achieved, for example, it may include but not limited to the following steps: by sputtering, vacuum deposition, ion plating, laser pulse
  • the first current collector layer and the second current collector layer are respectively provided on the two surfaces of the intermediate layer by methods such as a deposition method.
  • the surface of the first current collector layer and the second current collector layer away from the intermediate layer can also be provided with an active material layer.
  • the active material layer When the first current collector layer and the second current collector layer are positive electrode current collector layers, the active material layer The positive electrode active material is included in the active material layer, and when the first current collector layer and the second current collector layer are negative electrode current collector layers, the negative electrode active material is included in the active material layer.
  • the present application has no particular limitation on the positive electrode active material, as long as the purpose of the present application can be achieved, for example, it may include at least one of composite oxides of lithium and transition metal elements.
  • the present application has no particular limitation on the above-mentioned transition metal elements, as long as the purpose of the present application can be achieved, for example, at least one of nickel, manganese, cobalt or iron may be included.
  • the positive electrode active material may include lithium nickel cobalt manganese oxide (811, 622, 523, 111), lithium nickel cobalt aluminate, lithium iron phosphate, lithium-rich manganese-based materials, lithium cobalt oxide, lithium manganate, iron manganese phosphate At least one of lithium or lithium titanate.
  • the present application has no special restrictions on the negative electrode active material, as long as the purpose of the present application can be achieved, for example, it can include but not limited to natural graphite, artificial graphite, mesophase micro carbon spheres, hard carbon, soft carbon, silicon, silicon-carbon composite At least one of Li-Sn alloy, Li-Sn-O alloy, Sn, SnO, SnO 2 , lithiated TiO 2 -Li 4 Ti 5 O 12 with spinel structure, and Li-Al alloy.
  • the conductive agent can also be included in the active material layer.
  • the present application has no special limitation on the conductive agent, as long as the purpose of the application can be realized, for example, it can include but not limited to conductive carbon black (Super P), carbon nanotubes (CNTs), carbon fiber, flake graphite, Ketjen black, graphene, metal material or conductive polymer.
  • the aforementioned carbon nanotubes may include, but are not limited to, single-walled carbon nanotubes and/or multi-walled carbon nanotubes.
  • the aforementioned carbon fibers may include, but are not limited to, vapor grown carbon fibers (VGCF) and/or carbon nanofibers.
  • the above metal material may include but not limited to metal powder and/or metal fiber, specifically, the metal may include but not limited to at least one of copper, nickel, aluminum or silver.
  • the aforementioned conductive polymer may include but not limited to at least one of polyphenylene derivatives, polyaniline, polythiophene, polyacetylene or polypyrrole.
  • the active material layer may also include an active material layer binder, and the present application has no special limitation on the active material layer binder, as long as the purpose of the application can be achieved, for example, it may include but not limited to polyacrylic acid, Sodium polyacrylate, potassium polyacrylate, lithium polyacrylate, polyimide, polyvinyl alcohol, carboxymethyl cellulose, sodium carboxymethyl cellulose, polyimide, polyamideimide, styrene-butadiene rubber or poly at least one of vinylidene fluoride.
  • the pole piece may further include a conductive layer located between the first current collector layer or the second current collector layer and the active material layer.
  • a conductive layer located between the first current collector layer or the second current collector layer and the active material layer.
  • the present application has no particular limitation on the composition of the conductive layer, which may be a commonly used conductive layer in the field, for example may include but not limited to the above-mentioned conductive agent and the above-mentioned active material layer binder.
  • the electrochemical device of the present application also includes a separator, which is not particularly limited in the present application, as long as the purpose of the application can be achieved, such as but not limited to polyethylene (PE), polypropylene (PP), polytetrafluoroethylene Ethylene-based polyolefin (PO) separator, polyester film (such as polyethylene terephthalate (PET) film), cellulose film, polyimide film (PI), polyamide film (PA) , at least one of spandex or aramid film, woven film, non-woven film (non-woven fabric), microporous film, composite film, separator paper, rolled film or spun film, etc.
  • a separator which is not particularly limited in the present application, as long as the purpose of the application can be achieved, such as but not limited to polyethylene (PE), polypropylene (PP), polytetrafluoroethylene Ethylene-based polyolefin (PO) separator, polyester film (such as polyethylene terephthalate (PET)
  • the separator of the present application may have a porous structure, and the pore size is not particularly limited as long as the purpose of the present application can be achieved, for example, the pore size may be 0.01 ⁇ m to 1 ⁇ m.
  • the thickness of the isolation film is not particularly limited, as long as the purpose of the present application can be achieved, for example, the thickness may be 5 ⁇ m to 500 ⁇ m.
  • a separator may include a substrate layer and a surface treatment layer.
  • the substrate layer can be a non-woven fabric, film or composite film with a porous structure, and the material of the substrate layer can include but not limited to polyethylene, polypropylene, polyethylene terephthalate or polyimide, etc. at least one of .
  • a polypropylene porous film, a polyethylene porous film, a polypropylene non-woven fabric, a polyethylene non-woven fabric, or a polypropylene-polyethylene-polypropylene porous composite film may be used.
  • at least one surface of the substrate layer is provided with a surface treatment layer, and the surface treatment layer may be a polymer layer or an inorganic layer, or a layer formed by mixing a polymer and an inorganic material.
  • the polymer layer contains a polymer, and the polymer material may include but not limited to polypropylene, polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, At least one of polyvinylidene fluoride, poly(vinylidene fluoride-hexafluoropropylene), and the like.
  • the inorganic material layer can include but not limited to inorganic particles and binders, and the present application has no special limitation on inorganic particles, for example, it can include but not limited to ceramics, aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, hafnium oxide, oxide At least one of tin, cerium oxide, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, or barium sulfate.
  • the present application has no special restrictions on the binder in the inorganic layer, for example, it may include but not limited to polyvinylidene fluoride, copolymer of vinylidene fluoride-hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid , polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene or polyhexafluoropropylene.
  • the electrochemical device of the present application also includes an electrolyte, and the electrolyte of the present application may be one or more of gel electrolyte, solid electrolyte and electrolytic solution, and the electrolytic solution includes lithium salt and non-aqueous solvent.
  • lithium salts may include, but are not limited to, LiPF 6 , LiBF 4 , LiAsF 6 , LiClO 4 , LiB(C 6 H 5 ) 4 , LiCH 3 SO 3 , LiCF 3 SO 3 , LiN(SO 2 At least one of CF 3 ) 2 , LiC(SO 2 CF 3 ) 3 , LiSiF 6 , LiBOB or lithium difluoroborate, preferably LiPF 6 .
  • the above-mentioned non-aqueous solvent may be at least one of carbonate compounds, carboxylate compounds, ether compounds or other organic solvents.
  • the above-mentioned carbonate compound may include but not limited to at least one of chain carbonate compound, cyclic carbonate compound or fluorocarbonate compound.
  • Above-mentioned chain carbonate compound can include but not limited to dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethylene propyl carbonate (EPC) or at least one of methyl ethyl carbonate (MEC).
  • the cyclic carbonate compound may include, but is not limited to, at least one of ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), or vinylethylene carbonate (VEC).
  • Fluorocarbonate compounds may include, but are not limited to, fluoroethylene carbonate (FEC), 1,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate, 1,1,2-trifluoroethylene carbonate Ethylene carbonate, 1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2- At least one of difluoro-1-methylethylene carbonate, 1,1,2-trifluoro-2-methylethylene carbonate, or trifluoromethylethylene carbonate.
  • FEC fluoroethylene carbonate
  • 1,2-difluoroethylene carbonate 1,1-difluoroethylene carbonate
  • carboxylate compounds may include but are not limited to methyl formate, methyl acetate, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, ⁇ -butyl At least one of lactone, decanolactone, valerolactone, mevalonolactone or caprolactone.
  • the aforementioned ether compounds may include, but are not limited to, dibutyl ether, tetraglyme, diglyme, 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxy At least one of methoxyethane, 2-methyltetrahydrofuran or tetrahydrofuran.
  • the above-mentioned other organic solvents may include but not limited to dimethyl sulfoxide, 1,2-dioxolane, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, N-methyl-2- At least one of pyrrolidone, formamide, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate, trioctyl phosphate or phosphoric acid ester.
  • the electrochemical device of the present application is not particularly limited, and it may include any device that undergoes an electrochemical reaction.
  • the electrochemical device may include, but is not limited to, a lithium metal secondary battery, a lithium ion secondary battery (lithium ion battery), a lithium polymer secondary battery, or a lithium ion polymer secondary battery, and the like.
  • the preparation process of electrochemical devices is well known to those skilled in the art, and the present application is not particularly limited.
  • it may include but not limited to the following steps: stack the positive pole piece, separator and negative pole piece in order, and place the The electrode assembly with winding structure is obtained by winding, folding and other operations, the electrode assembly is put into the packaging case, the electrolyte is injected into the packaging case and sealed to obtain an electrochemical device; or, the positive electrode sheet, separator and negative electrode sheet Stack in order, and then fix the four corners of the entire laminated structure with adhesive tape to obtain the electrode assembly of the laminated structure, put the electrode assembly into the packaging case, inject the electrolyte into the packaging case and seal it, and obtain the electrochemical device.
  • anti-overcurrent elements, guide plates, etc. can also be placed in the packaging case as needed, so as to prevent pressure rise and overcharge and discharge inside the electrochemical device.
  • the material of the above-mentioned packaging shell may be the packaging material in any of the foregoing embodiments.
  • the second aspect of the present application provides an electronic device, comprising the electrochemical device described in any embodiment of the present application.
  • the electrochemical device provided by the present application has good performance at low temperature, so the electronic device provided by the present application also has good low temperature performance at low temperature.
  • the electronic device of the present application is not particularly limited, and it may be used in any electronic device known in the prior art.
  • electronic devices may include, but are not limited to: notebook computers, pen-based computers, mobile computers, e-book players, cellular phones, portable fax machines, portable copiers, portable printers, headsets, video recorders , LCD TVs, portable cleaners, portable CD players, mini discs, transceivers, electronic organizers, calculators, memory cards, portable tape recorders, radios, backup power supplies, motors, cars, motorcycles, power-assisted bicycles, bicycles, lighting Appliances, toys, game consoles, clocks, electric tools, flashlights, cameras and large batteries for household use, etc.
  • the application provides an electrochemical device and an electronic device.
  • the electrochemical device includes a pole piece, the pole piece includes a current collector, and the current collector includes a first current collector layer, an intermediate layer, a second current collector layer, a first conductive terminal and a second current collector.
  • the electrochemical device is heated; when the temperature of the electrochemical device reaches the target heating temperature (eg higher than 35°C), the first conductive terminal and the second conductive terminal are disconnected, and the intermediate layer stops heating the electrochemical device. Therefore, the electrochemical device can realize self-heating at low temperature, improve the lithium precipitation phenomenon of the negative electrode, and at the same time make the positive electrode active material and the negative electrode active material have a normal capacity, thereby improving the performance of the electrochemical device at low temperature, such as energy density, Specific capacity and cycle performance, etc.
  • the target heating temperature eg higher than 35°C
  • FIG. 1 is a schematic diagram of a current collector of a positive pole piece in some embodiments of the present application
  • Fig. 2 is the A-A cross-sectional schematic view of the current collector in Fig. 1;
  • Fig. 3 is a B-B schematic cross-sectional view of the current collector in Fig. 1;
  • Fig. 4 is a schematic cross-sectional view along the width direction of the current collector of the composite pole piece in some embodiments of the present application;
  • Fig. 5 is a schematic cross-sectional view along the width direction of the current collector of the positive pole piece in some embodiments of the present application;
  • Fig. 6 is a schematic cross-sectional view along the width direction of the current collector of the composite pole piece in some embodiments of the present application;
  • Fig. 7 is a schematic diagram of the current collector of the positive pole piece in some embodiments of the present application.
  • Fig. 8 is a C-C cross-sectional schematic diagram of the current collector in Fig. 7;
  • Fig. 9 is a D-D schematic cross-sectional view of the current collector in Fig. 7;
  • Fig. 10 is a schematic diagram of a current collector of a positive pole piece in some embodiments of the present application.
  • Figure 11 is a schematic cross-sectional view of the E-E direction of the current collector in Figure 10;
  • FIG. 12 is a schematic diagram of a current collector of a positive electrode sheet containing through holes in some embodiments of the present application.
  • Fig. 13 is a schematic cross-sectional view of the F-F direction of the current collector in Fig. 12;
  • Fig. 14 is a schematic cross-sectional view along the length direction of a current collector of a composite pole piece containing through holes in some embodiments of the present application;
  • Fig. 15 is a schematic structural diagram of a conductive portion with a pattern in some embodiments of the present application.
  • FIG. 16 is a schematic structural diagram of a patterned conductive portion in some embodiments of the present application.
  • a lithium-ion battery is used as an example of an electrochemical device to explain the present application, but the electrochemical device of the present application is not limited to the lithium-ion battery.
  • Figures 1 to 3 show positive current collectors 1a in some embodiments of the present application, wherein Figure 1 is a schematic view of the positive current collector 1 viewed along the thickness direction, and Figure 2 is a schematic cross-sectional view of the positive current collector 1 along the width direction, 3 is a schematic cross-sectional view of the positive electrode collector along the length direction.
  • the insulating part 51 includes a first insulating layer 511 and a second insulating layer 512, the conductive part 52 is located between the first insulating layer 511 and the second insulating layer 512, and the first current collector layer 10 is disposed on the first insulating layer 511 away from the conductive part.
  • the second current collector layer 20 is disposed on the surface of the second insulating layer 512 away from the conductive part 52, thereby realizing electrical insulation between the conductive part 52 and the first current collector layer 10 and the second current collector layer 20.
  • both the first current collector layer 10 and the second current collector layer 20 are positive electrode current collector layers.
  • the structure is similar to that shown in FIG. 2 , except that the first current collector layer 10 is a positive electrode current collector layer, and the second current collector layer 20 is a negative electrode current collector layer.
  • the first current collector layer and the second current collector layer can both be negative electrode current collector layers, or the first current collector layer is a negative electrode current collector layer, and the second current collector layer is a positive electrode current collector layer.
  • FIG. 5 shows a schematic cross-sectional view of the positive current collector in some embodiments of the present application along the width direction.
  • the insulating part 51 wraps the conductive part 52, so that the conductive part 52 is connected to the first current collector layer 10 and the second current collector layer 20. electrical insulation between.
  • the first conductive terminal 41 and the second conductive terminal 42 are connected to the conductive portion 52 and protrude from the insulating portion 51 . After the first conductive terminal 41 and the second conductive terminal 42 are conducted, a current is passed through, and the conductive part 52 heats the electrochemical device.
  • both the first current collector layer 10 and the second current collector layer 20 are positive electrode current collector layers. Alternatively, as shown in FIG.
  • the first current collector layer 10 is a positive electrode current collector layer
  • the second current collector layer 20 is a negative electrode current collector layer. It can be understood that the first current collector layer and the second current collector layer can both be negative electrode current collector layers, or the first current collector layer is a negative electrode current collector layer, and the second current collector layer is a positive electrode current collector layer.
  • FIG. 7 to 9 show the positive current collector 1b in some embodiments of the present application.
  • FIG. 7 is a schematic diagram of the positive current collector 1 viewed along the thickness direction
  • FIGS. 8 and 9 are views of different regions of the positive current collector 1 along the width direction. Sectional schematic.
  • the electrical connection between the layer 10 and the second current collector layer 20 that is, the electrical connection between the first current collector layer 10 and the second current collector layer 20 can be realized.
  • the first conductive terminal 41 is connected to the first current collector layer 10
  • the second conductive terminal 42 is connected to the second current collector layer 20 .
  • the role of the first current collector layer 10 and the second current collector layer 20 can be fully utilized during the charging and discharging process of the electrochemical device, thereby improving the electrochemical performance of the electrochemical device.
  • both the first current collector layer 10 and the second current collector layer 20 are positive electrode current collector layers.
  • first conductive terminal can be connected to the first current collector layer, and the second conductive terminal can be connected to the conductive part; or, the first conductive terminal can be connected to the conductive part, and the second conductive terminal can be connected to the second current collector layer; Moreover, both the first conductive terminal and the second conductive terminal are connected to the conductive part.
  • the first current collector layer and the second current collector layer may both be negative electrode current collector layers.
  • Figure 10 and Figure 11 show the positive electrode current collector 1c in some embodiments of the present application, wherein Figure 10 is a schematic view of the positive electrode current collector 1c viewed along the thickness direction, and Figure 11 is a schematic cross-sectional view of the positive electrode current collector 1c along the length direction.
  • the insulating part 51 wraps the conductive part 52 so as to achieve electrical insulation between the conductive part 52 and the first current collector layer 10 and the second current collector layer 20 .
  • the conductive portion 52 includes conductive sub-regions X and Y, both of which are connected to the first conductive terminal 41 and the second conductive terminal 42 , and the areas of the conductive sub-regions X and Y are the same.
  • both the first current collector layer 10 and the second current collector layer 20 are positive electrode current collector layers.
  • the area size of the conductive sub-regions X and Y can also be different, and the first current collector layer and the second current collector layer can also be negative electrode current collector layers; or, the first current collector layer is a positive electrode current collector layer, the second current collector layer is the negative electrode current collector layer; moreover, the first current collector layer is the negative electrode current collector layer, and the second current collector layer is the positive electrode current collector layer.
  • Figure 12 and Figure 13 show the positive electrode current collector 1d in some embodiments of the present application, wherein, Figure 12 is a schematic view of the positive electrode current collector 1d along the thickness direction, and Figure 13 is a schematic cross-sectional view of the positive electrode current collector 1d along the length direction.
  • the conductive portion 52 includes conductive sub-regions Z and W, and a through hole 60 is arranged between the conductive sub-regions Z and W.
  • the filling material in the through hole 60 is a conductive substance, and the first current collector can be realized through the conductive substance in the through hole 60.
  • first current collector layer 10 and the second current collector layer 20 are positive electrode current collector layers.
  • the conductive substance in the through hole 60 is electrically insulated from the conductive part 52, and the through hole 60 is set in the area where only the insulating part 51 is located along the thickness direction of the intermediate layer.
  • the through hole 60 does not penetrate the conductive part 52, so as to avoid affecting the conductive part 52. Heating effects on electrochemical devices.
  • the first current collector layer and the second current collector layer may also both be negative electrode current collector layers.
  • the through holes 60 are filled with electrically insulating ionic conductors, so that the first current collector layer 10 It is electrically insulated from the second current collector layer 20, and can form an ion path connecting both sides of the first current collector layer 10 and the second current collector layer 20, so as to improve the ion conductivity of the pole piece, thereby improving the performance of the electrochemical device. electrochemical performance.
  • the first current collector layer 10 is a positive electrode current collector layer
  • the second current collector layer 20 is a negative electrode current collector layer.
  • the first current collector layer can also be a negative electrode current collector layer
  • the second current collector layer can be a positive electrode current collector layer, or both the first current collector layer and the second current collector layer are positive electrode current collector layers, Furthermore, both the first current collector layer and the second current collector layer are negative electrode current collector layers.
  • Figure 15 and Figure 16 respectively show the conductive part of the intermediate layer in some embodiments of the present application
  • the first conductive part 31 has a pattern 70 on its thickness direction projected surface
  • the pattern and the distribution area of the conductive part 52 in Figure 15 The area of is smaller than the area of the pattern and the distribution area of the conductive part 52 in FIG. 16 . It can be understood that the size of the distribution area of the pattern can also be selected according to the actual situation.
  • the ambient temperature is T 0
  • the heating target temperature is T 1 (the minimum surface temperature of the lithium-ion battery reaches T 1 ) and the time required is t
  • the heating rate (T 1 -T 0 )/t.
  • Different positions on the surface of the lithium-ion battery are respectively pasted with temperature-sensing lines to detect the temperature at different positions during the heating process of the lithium-ion battery.
  • the surface temperature difference of the lithium-ion battery is between the highest surface temperature and the lowest temperature difference.
  • the ambient temperature is 15°C, charge with a constant current of 1C to 4.45V, then charge with a constant voltage of 4.45V, charge until the cut-off current is 0.025C, and the charging time is the full charge time at this temperature.
  • a Cu metal sheet (conductive part) with a resistance value of 800 m ⁇ between the first conductive terminal and the second conductive terminal with a pattern (pattern shape as shown in FIG. 15 ) was placed between two PET films (insulating part).
  • the first conductive terminal and the second conductive terminal are connected to the Cu metal sheet (as shown in FIG. 15 ) and protrude from the PET film.
  • the PET film is thermally fused to obtain the middle layer.
  • the thickness of the metal sheet is 5 ⁇ m
  • the thickness of the intermediate layer is 8 ⁇ m.
  • Al coatings with a thickness of 0.5 ⁇ m were respectively prepared on the two surfaces of the above-obtained intermediate layer by vacuum deposition to form a first current collector layer and a second current collector layer to obtain a composite positive current collector.
  • the positive active material lithium cobaltate (LiCoO 2 ), conductive carbon black (Super P), and polyvinylidene fluoride (PVDF) were mixed according to a weight ratio of 97.5:1.0:1.5, and N-methylpyrrolidone (NMP) was added as a solvent , prepared into a positive electrode slurry with a solid content of 75%, and stirred evenly.
  • the slurry was uniformly coated on one surface of the composite positive electrode current collector, wherein the content of the positive electrode active material was 180g/m 2 , and dried at 90°C to obtain a positive electrode sheet coated with the positive electrode active material on one side.
  • the compacted density of the positive electrode sheet is 4.1 g/cm 3 .
  • Cu coatings with a thickness of 0.5 ⁇ m were respectively prepared on the two surfaces of the intermediate layer obtained above by vacuum deposition to obtain a composite negative electrode current collector.
  • negative electrode slurry and stir evenly. The slurry was uniformly coated on one surface of the composite negative electrode current collector, wherein the content of the negative electrode active material was 95g/m 2 , and dried at 110°C to obtain a negative electrode sheet coated with the negative electrode active material on one side.
  • the composite negative electrode current collector Repeat the above steps on the other surface of the composite negative electrode current collector to obtain a negative electrode sheet coated with negative active materials on both sides. Then, after cold pressing, cutting into pieces, and slitting, they were dried under vacuum conditions at 85° C. for 4 hours to obtain negative electrode sheets with a size of 74 mm ⁇ 867 mm. Wherein, the compacted density of the negative electrode sheet is 1.7 g/cm 3 .
  • EC ethylene carbonate
  • EMC ethyl methyl carbonate
  • DEC diethyl carbonate
  • PE Polyethylene
  • the positive electrode sheet, separator, and negative electrode sheet were stacked in order so that the separator was in the middle, and the electrode assembly was obtained by winding.
  • the electrode assembly in an aluminum-plastic film packaging bag, inject electrolyte after drying, and obtain a lithium-ion battery through processes such as vacuum packaging, standing, chemical formation, degassing, and edge trimming.
  • the formation condition is to charge to 3.3V with a constant current of 0.02C, and then charge to 3.6V with a constant current of 0.1C.
  • the first conductive terminal and the second conductive terminal protrude from the packaging bag to connect with the power supply.
  • the aforementioned power source refers to a power source capable of supplying current.
  • Embodiment 2 to Embodiment 3 except that the area of the conductive part distribution area of the pattern on the projection surface of the metal sheet is adjusted so that the resistance between the two conductive terminals is as shown in Table 1, the rest are the same as Embodiment 1.
  • Example 4 except in ⁇ Preparation of the middle layer>, except that the ends of the conductive layer are respectively welded to the first current collector layer and the second current collector layer to form a current collector with the structure shown in Figures 7 to 9 Except, the others are the same as in Example 1.
  • Example 5 except in ⁇ Preparation of the middle layer>, two metal sheets are arranged between two thin films, wherein each metal sheet is connected with a first conductive terminal and a second conductive terminal, forming as shown in Figure 10 and Except for the current collector of the structure shown in FIG. 11, the rest is the same as that of Embodiment 1.
  • An Al coating with a thickness of 0.5 ⁇ m and a Cu coating with a thickness of 0.5 ⁇ m were respectively prepared on the two surfaces of the intermediate layer by vacuum deposition, and then the positive electrode slurry was coated on the Al coating, and the negative electrode slurry was coated on the Cu coating. On the coating, dry at 60°C to obtain a composite pole piece. Then, after cold pressing, cutting into pieces, and slitting, they were dried under vacuum conditions at 85°C for 4 hours to obtain composite pole pieces with a size of 74mm ⁇ 867mm. Wherein, the compacted density of the negative electrode sheet is 1.7 g/cm 3 .
  • PE polyethylene
  • the separator stack the composite pole piece, separator, and composite pole piece in order, so that the polarities of the adjacent surfaces of the two composite pole pieces are oppositely set, and the electrode assembly is obtained by winding .
  • the electrode assembly in an aluminum-plastic film packaging bag, inject electrolyte after drying, and obtain a lithium-ion battery through processes such as vacuum packaging, standing, chemical formation, degassing, and edge trimming.
  • the formation condition is to charge to 3.3V with a constant current of 0.02C, and then charge to 3.6V with a constant current of 0.1C.
  • the first conductive terminal and the second conductive terminal protrude from the packaging bag to connect with the power supply.
  • the aforementioned power source refers to a power source capable of supplying current.
  • Example 7 except adopting the laser drilling method to set a plurality of circular through holes on the positive pole piece and the negative pole piece, the conductive substance filled in the through holes is conductive carbon powder, the aperture of the through holes is 500 ⁇ m, and the hole density is 5 The number/cm 2 and the area ratio of the through holes are 1%, and the rest are the same as in the first embodiment.
  • Embodiment 8 is the same as Embodiment 10 except that the conductive carbon powder is replaced by an electrically insulating ion conductor Al 2 O 3 .
  • Embodiment 9 and Embodiment 10 except that the thickness of the metal layer is adjusted according to Table 1, the others are the same as Embodiment 1.
  • the thickness of the middle layer in Example 9 is 11 ⁇ m
  • the thickness of the middle layer in Example 10 is 18 ⁇ m.
  • Comparative Example 1 except that the middle layer adopts a PET film with a thickness of 8 ⁇ m, the rest is the same as that of Example 1.
  • a nickel sheet with a thickness of 5 ⁇ m is selected, and the projection surface of the nickel sheet has a pattern (the pattern shape is shown in Figure 15), and the resistance between the first conductive terminal connected to the nickel sheet and the second conductive terminal is 800m ⁇ , using PET film to encapsulate nickel sheet.
  • the first conductive terminal and the second conductive terminal protrude from the PET film, and the thickness of the packaged nickel sheet is 8 ⁇ m.
  • the electrochemical device provided by the present application can be provided with a conductive part in the current collector, while substantially not losing energy density, Achieve uniform heating of the electrochemical device, thereby increasing the overall heating rate of the electrochemical device, and significantly shortening the full charge time at 15°C, indicating that the electrochemical device provided by the application still has good charging performance and Higher energy density.
  • the full charge time and volumetric energy density of the electrochemical device at 15°C vary with the resistance between the first conductive terminal and the second conductive terminal and the thickness of the conductive part.
  • the resistance value and the thickness of the conductive part are within the scope of the present application, and the obtained electrochemical device has good charging performance and high energy density.

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Abstract

本申请提供了一种电化学装置和电子装置，电化学装置包括极片，极片包括集流体，集流体包括第一集流体层、中间层、第二集流体层、第一导电端子和第二导电端子，其中，中间层位于第一集流体层和第二集流体层之间，第一导电端子和第二导电端子与中间层形成电连接，第一导电端子与第二导电端子间具备电阻R，当温度低于设定值时，可激活电阻R。第一导电端子和第二导电端子导通后通入电流，中间层对电化学装置进行加热，从而使电化学装置能够在低温条件下实现快速的自加热，提升电化学体系动力学，降低极化，有效减少电化学装置的能量密度损失，并改善负极析锂的现象，进而改善电化学装置在低温下的性能，例如充电性能、循环性能等。

Description

一种电化学装置和电子装置 技术领域
本申请涉及电化学领域，特别是涉及一种电化学装置和电子装置。
背景技术
锂离子电池由于具有高能量密度、长循环寿命及无记忆效应等优点而被广泛应用于穿戴设备、智能手机、无人机、电动汽车及大型储能等设备等领域，已成为当今世界最具发展潜力的新型绿色化学电源，但也对锂离子电池的性能提出更高的要求。
在温度较低(例如低于10℃)的环境中，锂离子电池的动力学性能变差，充电时易导致负极出现析锂，同时，正极活性材料和负极活性材料的活性降低，导致锂离子电池的容量发挥受限、能量密度降低，从而导致锂离子电池的性能降低。在相关技术中，通常采用外部加热方式对锂离子电池进行加热以改善锂离子电池在低温下的性能，但加热过程升温速率慢，锂离子电池整体温差较大，对正极活性材料和负极活性材料影响较大，也会影响锂离子电池的循环、安全等性能；采用内置加热片也是一种常用的加热方式，但加热片的内置降低了锂离子电池的能量密度，其加热的不均匀性也使得锂离子电池存在一定的安全可靠性风险。
发明内容
本申请的目的在于提供一种电化学装置和电子装置，以提高电化学装置在低温下的性能。
本申请的第一方面提供了一种电化学装置，电化学装置包括极片，极片包括集流体，集流体包括第一集流体层、中间层、第二集流体层、第一导电端子和第二导电端子，其中，中间层位于第一集流体层和第二集流体层之间，第一导电端子和第二导电端子与中间层形成电连接，第一导电端子与第二导电端子间具有阻值为R的电阻，当温度低于设定值时，可激活电阻。具体地，将上述极片应用于电化学装置中，当电化学装置的温度低于设定值时(例如低于10℃)，第一导电端子和第二导电端子导通后通入电流，电阻被激活，中间层对电化学装置进行加热；当电化学装置的温度达到加热目标温度(例如高于35℃)时，第一导电端子和第二导电端子断开，电阻处于未激活状态，中间层停止对电化学装置加热。从而使电化学装置能够在低温条件下实现快速的自加热，提升电化学体系动力学，降低极化，有效减少电化学装置的能量密度损失，并改善负极析锂的现象，进而改善电化学装置 在低温下的性能，例如充电性能、循环性能等。此外，将可激活的电阻设置于集流体的中间层，在不增加其他组件、不损失电化学装置的能量密度的同时，能够实现对电化学装置更为均匀高效的加热，进一步改善电化学装置在快速充电环境下的安全性能。在本申请中，对电化学装置的温度监控方式，以及控制第一导电端子和第二导电端子导通和断开的方式不做具体限定，只要能实现本申请的目的即可，可以采用本领域已知的方式，例如，可以采用温度传感器监控电化学装置的温度，通过开关控制第一导电端子和第二导电端子导通和断开。
本申请对第一端子和第二端子的材质、结构、尺寸均没有特别限制，只要能够形成闭合通路，实现本申请目的即可。
在本申请的一些实施方案中，电化学装置还包括正极极耳和负极极耳，正极极耳和负极极耳之间具有阻值为R’的内阻，第一导电端子与第二导电端子间的电阻R的取值满足5≤R/R’≤1000。不限于任何理论，本申请的发明人发现，通过将集流体的电阻调控在上述范围内，有利于提高电化学装置的电化学性能。不限于任何理论，本申请的发明人发现，当第一导电端子与第二导电端子之间电阻R的阻值过小时，在第一导电端子和第二导电端子导通加热时，中间层对电化学装置的加热速率慢，导致电化学装置整体的温差较大，不能有效改善电化学装置在低温下的性能。当第一导电端子和第二导电端子之间电阻R的阻值过大时，影响电流的通过，也会使得中间层对电化学装置的加热速率慢。将第一导电端子与第二导电端子之间电阻R的阻值调控在上述范围内，有利于将中间层对电化学装置的加热速率控制在合适的范围内，从而有效改善电化学装置在低温下的性能。
在本申请的一些实施方案中，第一导电端子与第二导电端子之间的电阻R的取值为200mΩ至1500mΩ。例如，第一导电端子与第二导电端子之间的电阻R的取值可以为200mΩ、400mΩ、500mΩ、600mΩ、800mΩ、1000mΩ、1200mΩ、1400mΩ、1500mΩ或为其间的任意范围。
在本申请的一些实施方案中，集流体的中间层包括导电部和绝缘部，导电部与第一集流体层的至少一部分形成电绝缘，导电部与第二集流体层的至少一部分形成电绝缘。当导电部与第一集流体层形成电绝缘，并且导电部与第二集流体层之间形成电绝缘时，第一集流体层和第二集流体层在电化学装置的内电路中呈电绝缘状态；当导电部与第一集流体层的至少一部分形成电绝缘，并且导电部与第二集流体层的形成电绝缘时，导电部还与第一集流体层的至少一部分形成电连接，第一集流体层和第二集流体层在电化学装置的内电路 中呈电绝缘状态；当导电部与第一集流体层的至少一部分形成电绝缘，并且导电部与第二集流体层的至少一部分形成电绝缘时，导电部还与第一集流体层的至少一部分形成电连接，并且导电部与第二集流体层的至少一部分形成电连接，即第一集流体层和第二集流体层之间能够通过导电部实现电连接。其中，当导电部还与第一集流体层的至少一部分形成电连接，并且导电部与第二集流体层的至少一部分形成电连接时，第一集流体与第二集流体的极性不能相反。当电化学装置的温度低于设定值时(例如低于10℃)，第一导电端子和第二导电端子导通后，导电部通入电流，对电化学装置进行加热，其加热均匀性好。本申请对温度的设定值没有特别限制，可以是领域内人员根据实际需要设定。
在本申请的一些实施方案中，集流体满足以下条件(i)至(iii)中的其中一者：(i)导电部与第一集流体层形成电绝缘，并且导电部与第二集流体层形成电绝缘，第一导电端子和第二导电端子连接于导电部，第一集流体层和第二集流体层极性相同或相反；(ii)导电部与第一集流体层形成电连接，并且导电部与第二集流体层形成电绝缘，第一导电端子连接于第一集流体层，第二导电端子连接于导电部，第一集流体层和第二集流体层极性相同或相反；(iii)导电部与第一集流体层和第二集流体层形成电连接，第一导电端子连接于导电部或第一集流体层，第二导电端子连接于导电部或第二集流体层，第一集流体层和第二集流体层极性相同。
在本申请的一些实施方案中，绝缘部包括第一绝缘层和第二绝缘层，导电部位于第一绝缘层和第二绝缘层之间，第一集流体层设置在第一绝缘层远离导电部的表面上，第二集流体层设置在第二绝缘层远离导电部的表面上，从而实现导电部与第一集流体层和第二集流体层之间的电绝缘，也即第一集流体层和第二集流体层之间电绝缘，第一导电端子和第二导电端子连接于导电部。当电化学装置的温度低于设定值时(例如低于10℃)，第一导电端子和第二导电端子导通后，导电部通入电流，对电化学装置进行加热，其加热均匀性较好。其中，第一集流体层和第二集流体层可以同时为正极集流体层或者负极集流体层，也可以是第一集流体层和第二集流体层中的一个为正极集流体层另一个为负极集流体层。第一绝缘层和第二绝缘层的厚度可以相同或者不相同，优选地，第一绝缘层和第二绝缘层的厚度相同。本申请对导电部在集流体厚度方向的投影面中分布的区域的面积大小没有特别限制，只要能实现本申请的目的即可，例如导电部的分布区域的面积小于或等于第一集流体层或第二集流体层的面积，当导电部的分布区域的面积小于第一集流体层或第二集流体层的面积时，导电部在集流体中的分布区域可以根据实际情况进行选择。
在本申请的一些实施方案中，绝缘部将导电部包裹，从而实现导电部与第一集流体层 和第二集流体层之间的电绝缘。第一导电端子和第二导电端子连接于导电部，并从绝缘部伸出。当电化学装置的温度低于设定值时(例如低于10℃)，第一导电端子和第二导电端子导通后，导电部通入电流，对电化学装置进行加热。其中，第一集流体层和第二集流体层可以同时为正极集流体层或者负极集流体层，也可以是第一集流体层和第二集流体层中的一个为正极集流体层，另一个为负极集流体层。沿中间层厚度方向，导电部两侧的绝缘部厚度相同或者不相同，优选地，导电部两侧的绝缘部厚度相同。
在本申请的一些实施方案中，导电部与第一集流体层之间存在电连接区域，从而实现导电部与第一集流体层之间的电连接，第一集流体层和第二集流体层之间电绝缘。第一导电端子连接于导电部或第一集流体层，第二导电端子连接于导电部，第一集流体层和第二集流体层极性相同或相反。优选地，第一导电端子连接于第一集流体层，第二导电端子连接于导电部。可以理解的是，也可以是导电部与第二集流体层之间存在电连接区域，从而实现导电部与第二集流体层之间的电连接，第一集流体层和第二集流体层之间电绝缘。第一导电端子连接于导电部或第二集流体层，第二导电端子连接于导电部，第一集流体层和第二集流体层极性相同或相反。优选地，第一导电端子连接于第二集流体层，第二导电端子连接于导电部。当电化学装置的温度低于设定值时(例如低于10℃)，第一导电端子和第二导电端子导通后，导电部通入电流，对电化学装置进行加热，其加热均匀性较好。其中，第一集流体层和第二集流体层可以同时为正极集流体层或者负极集流体层，也可以是第一集流体层和第二集流体层中的一个为正极集流体层另一个为负极集流体层。
在本申请的一些实施方案中，导电部与第一集流体层、导电部与第二集流体层之间存在电连接区域，从而实现导电部与第一集流体层和第二集流体层之间的电连接，也即第一集流体层和第二集流体层之间能够通过导电部实现电连接。第一导电端子连接于导电部或第一集流体层，第二导电端子连接于导电部或第二集流体层。优选地，第一导电端子连接于第一集流体层，第二导电端子连接于第二集流体层。当电化学装置的温度低于设定值时(例如低于10℃)，第一导电端子和第二导电端子导通后通入电流，导电部对电化学装置进行加热，其加热均匀性较好。此外，在电化学装置充放电过程中有利于充分发挥第一集流体层和第二集流体层的作用，从而提高电化学装置的电化学性能。本申请对导电部与第一集流体层和第二集流体层之间的电连接区域形成的方式没有特别限制，只要能实现本申请的目的即可，例如，将第一集流体和第二集流体层与导电部进行局部焊接连接，焊接连接区域为电连接区域。本申请对电连接区域的面积大小没有特别限制，只要能实现本申请的目的即可。
在本申请的一些实施方案中，导电部可以包括多个导电子区域，每个导电子区域上均连接有第一导电端子和第二导电端子，导电子区域的设置可以满足不同区域的不同加热需求，每个导电子区域的面积大小可以相同或不相同，可以根据实际情况进行选择和设计。
在本申请的一些实施方案中，集流体包括通孔，通孔贯穿第一集流体层、第二集流体层和中间层。通孔的设置能够形成连通第一集流体层和第二集流体层两侧的离子通路，以改善极片的离子传导能力，进而提升电化学装置的电化学性能。
在本申请的一些实施方案中，集流体满足以下条件(iv)至(v)中的其中一者：(iv)通孔中填充有导电物质，第一集流体层和第二集流体层的极性相同；(v)通孔中填充有电性绝缘的离子导体，第一集流体层和第二集流体层的极性不同，第一集流体层和第二集流体层之间呈电性绝缘状态。
示例性地，当通孔中的填充物质为导电物质，通过通孔中的导电物质能够实现第一集流体层和第二集流体层之间的电连接，这样，在第一导电端子和第二导电端子导通后，导电部通入电流，对电化学装置进行加热，有利于加热过程中热量的传递。此外，在电化学装置充放电过程中有利于充分发挥第一集流体层和第二集流体层的作用，从而提高电化学装置的电化学性能。其中，第一集流体层和第二集流体层可以同时为正极集流体层或者负极集流体层。通孔中的导电物质与导电部之间电绝缘，也即通孔设置在沿中间层厚度方向只有绝缘部的区域，通孔并未贯穿导电部，避免影响导电部对电化学装置的正常工作。
在本申请中，对导电物质没有特别限制，只要能实现本申请的目的即可。例如，导电物质可以包括但不限于无机导电材料和/或导电高分子材料。无机导电材料可以包括但不限于碳系导电材料和/或金属氧化物，优选地，碳系导电材料可以包括但不限于炭黑、石墨、石墨烯、碳纤维、单壁碳纳米管或多壁纳米管中的至少一种，金属氧化物可以包括但不限于掺铝氧化锌、掺钙铬酸镧、二氧化锡、掺氟二氧化锡、掺锑二氧化锡、掺氟二氧化锡、氧化铟锡、掺银氧化铟锡、掺银合金氧化铟锡等中的至少一种。导电高分子材料可以包括但不限于聚乙炔、聚吡咯、聚噻吩、聚对苯、聚本乙炔、聚苯胺及其掺杂导电高分子材料中的至少一种。掺杂剂可以包括但不限于氯、碘、溴、氯化碘、溴化碘、氟化碘、五氟化磷、氢氟酸、盐酸、硝酸、硫酸、高氯酸、五氟化钼、五氟化钨、四氯化钛、四氯化锆、氯化铁、四碘化锡中的至少一种。
示例性地，当通孔中的填充有电性绝缘的离子导体，使得第一集流体层和第二集流体层之间电绝缘，并能够形成连通第一集流体层和第二集流体层两侧的离子通路，以改善极 片的离子传导能力，进而提升电化学装置的电化学性能。其中，第一集流体层和第二集流体层中的一个为正极集流体层另一个为负极集流体层，可以是第一集流体层为正极集流体层，第二集流体层为负极集流体层；也可以是第一集流体层为负极集流体层，第二集流体层为正极集流体层。
在本申请中，对电性绝缘的离子导体的材料没有特别限制，只要能实现本申请的目的即可。例如，电性绝缘的离子导体可以为固态电解质材料或者为无机材料与粘结剂的混合物。
本申请对固态电解质材料没有特别限制，只要能实现本申请的目的即可，例如，可以包括但不限于聚偏氟乙烯-六氟丙烯(PVDF-HFP)、聚偏氟乙烯(PVDF)、聚丙烯腈(PAN)、聚甲基丙烯酸甲酯(PMMA)、聚苯醚(PPO)、聚碳酸亚丙酯(PPC)、聚环氧乙烷(PEO)及其衍生物中的至少一种。
本申请对无机材料没有特别限制，只要能实现本申请的目的即可，例如，可以包括但不限于HfO 2、SrTiO 3、SnO 2、CeO 2、MgO、NiO、CaO、BaO、ZnO、ZrO 2、Y 2O 3、Al 2O 3、TiO 2、SiO 2、勃姆石，氢氧化镁、氢氧化铝、磷酸锂(Li 3PO 4)、锂钛磷酸盐(Li x1Ti y1(PO 4) 3，其中0<x1<2且0<y1<3)、锂铝钛磷酸盐(Li x2Al y2Ti z2(PO 4) 3，其中0<x2<2，0<y2<1，且0<z2<3)、Li 1+x3+y3(Al,Ga) x3(Ti,Ge) 2-x3Si y3P 3-y3O 12，其中0≤x3≤1且0≤y3≤1、锂镧钛酸盐(Li x4La y4TiO 3，其中0<x4<2且0<y4<3)、锂锗硫代磷酸盐(Li x5Ge y5P z5S w5，其中0<x5<4，0<y5<1，0<z5<1，且0<w5<5)、锂氮化物(Li x6N y6，其中0<x6<4，0<y6<2)、SiS 2玻璃(Li x7Si y7S z7，其中0≤x7<3，0<y7<2，且0<z7<4)、P 2S 5玻璃(Li x8P y8S z8，其中0≤x8<3，0<y8<3，且0<z8<7)、Li 2O、LiF、LiOH、Li 2CO 3、LiAlO 2、Li 2O-Al 2O 3-SiO 2-P 2O 5-TiO 2-GeO 2陶瓷或石榴石陶瓷(Li 3+x9La 3M 2O 12，其中0≤x9≤5，且M为Te、Nb、或Zr)中的至少一种。
本申请对粘结剂没有特别限制，只要能实现本申请的目的即可，例如，可以包括但不限于聚酰胺、聚胺酯、乙烯-醋酸乙烯共聚物(EVA)、乙烯-乙烯醇共聚物(EVOH)、丙烯酸酯、海草酸钠(SA)、聚丙烯酸(PAA)、PVA、羧甲基壳聚糖、明胶、聚偏氟乙烯-六氟丙烯(PVDF-HFP)、聚偏氟乙烯(PVDF)、聚丙烯腈(PAN)、聚甲基丙烯酸甲酯(PMMA)、聚苯醚(PPO)、聚碳酸亚丙酯(PPC)或聚环氧乙烷(PEO)及其衍生物中的至少一种。
本申请对通孔的形状和分布没有特别限制，只要能实现本申请的目的即可，例如，通孔的形状可以包括但不限于圆形、椭圆形、三角形、正方形或长方形等中的至少一种，通孔在极片中呈均匀分布或不均匀分布。
本申请对通孔的孔径、密度和面积占比没有特别限制，只要能实现本申请的目的即可，例如，孔径为20μm至3000μm，密度为约1个/cm 2至约100个/cm 2，基于中间层的面积，通孔总的面积占比为0.1％至30％。不限于任何理论，本申请的发明人发现，通孔的孔径、密度或面积占比中的至少一个在上述范围内，既能改善极片的离子传导能力，也不会影响极片的电子传导能力，从而有利于提高电化学装置的性能。相邻通孔之间的距离可以相同或不相同。
在本申请的一些实施方案中，导电部在所述导电部厚度方向投影面上具有图案，和/或导电部的厚度为5μm至20μm。本申请对图案的形式没有特别限制，只要能实现本申请的目的即可，例如，图案可以是均匀图案也可以是不均匀的图案，图案的形状可以包括但不限于方波形、锯齿形等。
例如，导电部的厚度可以为5μm、8μm、10μm、12μm、15μm、18μm、20μm或为其间的任意范围。不限于任何理论，本申请的发明人发现，当导电部的厚度过小时(例如小于10μm)，其力学性能降低，影响极片的结构稳定性。当导电部的厚度过大时(例如大于25μm)，导致极片的厚度过大，从而影响电化学装置的能量密度。将导电部的厚度调控在上述范围内，在保证中间层具有良好的加热性能的前提下，有利于提高电化学装置的能量密度。
本申请对绝缘部的材料没有特别限制，只要能实现本申请的目的即可，例如可以包括但不限于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、聚醚醚酮、聚酰亚胺、聚酰胺、聚乙二醇、聚酰胺酰亚胺、聚碳酸酯、环状聚烯烃、聚苯硫醚、聚乙酸乙烯酯、聚四氟乙烯，聚亚甲基萘、聚偏二氟乙烯，聚萘二甲酸亚乙酯、聚碳酸亚丙酯、聚(偏二氟乙烯-六氟丙烯)、聚(偏二氟乙烯-共-三氟氯乙烯)、有机硅、维尼纶、聚丙烯、聚乙烯、聚氯乙烯、聚苯乙烯、聚醚腈、聚氨酯、聚苯醚、聚酯、聚砜及其衍生物中的至少一种。
在本申请的一些实施方案中，极片为正极极片、负极极片或复合极片。在本申请中，复合极片是指第一集流体层和第二集流体层中的一个为正极集流体层，另一个为负极集流体层的极片。示例性地，可以是第一集流体层为正极集流体层，第二集流体层为负极集流体层；也可以是第一集流体层为负极集流体层，第二集流体层为正极集流体层。
本申请对第一集流体层、第二集流体层、导电部的材料没有特别限制，只要能实现本申请的目的即可。例如第一集流体层、第二集流体层、导电部的材料可以各自独立第包括 但不限于Ni、Ti、Cu、Ag、Au、Pt、Fe、Co、Cr、W、Mo、Al、Mg、K、Na、Ca、Sr、Ba、Si、Ge、Sb、Pb、In、Zn及其合金中的至少一种。在本申请中，对第一集流体层和第二集流体层的厚度没有特别限制，只要能够实现本申请目的即可，例如厚度各自独立地为1μm至8μm。
在本申请中，对中间层的制备方法没有特别限制，只要能实现本申请的目的即可。例如，以“中间层包括第一导电部和绝缘层，第一导电部包括第一导电层和第二导电层，绝缘层位于第一导电层和第二导电层之间”的中间层为例，其制备方法可以包括但不限于以下步骤：采用溅射法、真空沉积法、离子电镀法或激光脉冲沉积法等方法在绝缘层的两个表面分别设置第一导电层和第二导电层；或者通过热融合法将绝缘层与第一导电层和第二导电层进行复合得到中间层。以“绝缘部包括第一绝缘层和第二绝缘层，导电部位于第一绝缘层和第二绝缘层之间，第一集流体层设置在第一绝缘层远离导电部的表面上，第二集流体层设置在第二绝缘层远离导电部的表面上”的中间层为例，其制备方法可以包括但不限于以下步骤：采用涂覆法在导电部的两个表面上分别设置第一绝缘层和第二绝缘层，烘干处理后得到中间层。
在本申请中，对含有通孔的中间层的制备方法没有特别限制，只要能实现本申请的目的即可。例如，可以包括但不限于以下步骤：采用及激光打孔的方法在中间层上打孔，然后采用刮涂的方法，将含有导电物质或电性绝缘的离子导体的浆料填充到通孔内，然后烘干、清洗后得到含有通孔的中间层。
在本申请中，对导电部在其厚度方向投影面上的图案的设置方法没有特别限制，只要能实现本申请的目的即可，例如，激光切割法。
在本申请中，对极片的制备方法没有特别限制，只要能实现本申请的目的即可，例如，可以包括但不限于以下步骤：通过溅射法、真空沉积法、离子电镀法、激光脉冲沉积法等方法在中间层的两个表面分别设置第一集流体层和第二集流体层。
在本申请中，第一集流体层和第二集流体层远离中间层的表面还可以设置活性材料层，当第一集流体层和第二集流体层为正极集流体层时，活性材料层中包括正极活性材料，当第一集流体层和第二集流体层为负极集流体层时，活性材料层中包括负极活性材料。
本申请对正极活性材料没有特别限制，只要能够实现本申请目的即可，例如可以包括锂和过渡金属元素的复合氧化物中的至少一种。本申请对上述过渡金属元素没有特别限制， 只要能实现本申请的目的即可，例如可以包括镍、锰、钴或铁中的至少一种。具体的，正极活性材料可以包括镍钴锰酸锂(811、622、523、111)、镍钴铝酸锂、磷酸铁锂、富锂锰基材料、钴酸锂、锰酸锂、磷酸锰铁锂或钛酸锂中的至少一种。
本申请对负极活性材料没有特别限制，只要能实现本申请的目的即可，例如可以包括但不限于天然石墨、人造石墨、中间相微碳球、硬碳、软碳、硅、硅-碳复合物、Li-Sn合金、Li-Sn-O合金、Sn、SnO、SnO 2、尖晶石结构的锂化TiO 2-Li 4Ti 5O 12、Li-Al合金中的至少一种。
在本申请中，活性材料层中还可以包括导电剂，本申请对导电剂没有特别限制，只要能够实现本申请目的即可，例如可以包括但不限于导电炭黑(Super P)、碳纳米管(CNTs)、碳纤维、鳞片石墨、科琴黑、石墨烯、金属材料或导电聚合物中的至少一种。上述碳纳米管可以包括但不限于单壁碳纳米管和/或多壁碳纳米管。上述碳纤维可以包括但不限于气相生长碳纤维(VGCF)和/或纳米碳纤维。上述金属材料可以包括但不限于金属粉和/或金属纤维，具体地，金属可以包括但不限于铜、镍、铝或银中的至少一种。上述导电聚合物可以包括但不限于聚亚苯基衍生物、聚苯胺、聚噻吩、聚乙炔或聚吡咯中的至少一种。
在本申请中，活性材料层中还可以包括活性材料层粘结剂，本申请对活性材料层粘结剂没有特别限制，只要能够实现本申请目的即可，例如可以包括但不限于聚丙烯酸、聚丙烯酸钠、聚丙烯酸钾、聚丙烯酸锂、聚酰亚胺、聚乙烯醇、羧甲基纤维素、羧甲基纤维素钠、聚酰亚胺、聚酰胺酰亚胺、丁苯橡胶或聚偏氟乙烯中的至少一种。
任选地，极片还可以包括导电层，导电层位于第一集流体层或第二集流体层与活性材料层之间。本申请对导电层的组成没有特别限制，可以是本领域常用的导电层，例如可以包括但不限于上述导电剂和上述活性材料层粘结剂。
本申请的电化学装置还包括隔离膜，本申请对隔离膜没有特别限制，只要能够实现本申请目的即可，例如可以包括但不限于聚乙烯(PE)、聚丙烯(PP)、聚四氟乙烯为主的聚烯烃(PO)类隔膜、聚酯膜(例如聚对苯二甲酸二乙酯(PET)膜)、纤维素膜、聚酰亚胺膜(PI)、聚酰胺膜(PA)，氨纶或芳纶膜、织造膜、非织造膜(无纺布)、微孔膜、复合膜、隔膜纸、碾压膜或纺丝膜等中的至少一种。本申请的隔离膜可以具有多孔结构，孔径的尺寸没有特别限制，只要能实现本申请的目的即可，例如，孔径的尺寸可以为0.01μm至1μm。在本申请中，隔离膜的厚度没有特别限制，只要能实现本申请的目的即可，例如厚度可以为5μm至500μm。
例如，隔离膜可以包括基材层和表面处理层。基材层可以为具有多孔结构的无纺布、膜或复合膜，基材层的材料可以包括但不限于聚乙烯、聚丙烯、聚对苯二甲酸乙二醇酯或聚酰亚胺等中的至少一种。任选地，可以使用聚丙烯多孔膜、聚乙烯多孔膜、聚丙烯无纺布、聚乙烯无纺布或聚丙烯-聚乙烯-聚丙烯多孔复合膜。任选地，基材层的至少一个表面上设置有表面处理层，表面处理层可以是聚合物层或无机物层，也可以是混合聚合物与无机物所形成的层。
聚合物层中包含聚合物，聚合物的材料可以包括但不限于聚丙烯、聚酰胺、聚丙烯腈、丙烯酸酯聚合物、聚丙烯酸、聚丙烯酸盐、聚乙烯呲咯烷酮、聚乙烯醚、聚偏氟乙烯或聚(偏氟乙烯-六氟丙烯)等中的至少一种。无机物层可以包括但不限于无机颗粒和粘结剂，本申请对无机颗粒没有特别限制，例如，可以包括但不限于陶瓷、氧化铝、氧化硅、氧化镁、氧化钛、二氧化铪、氧化锡、二氧化铈、氧化镍、氧化锌、氧化钙、氧化锆、氧化钇、碳化硅、勃姆石、氢氧化铝、氢氧化镁、氢氧化钙或硫酸钡等中的至少一种。本申请对无机物层中的粘结剂没有特别限制，例如可以包括但不限于聚偏氟乙烯、偏氟乙烯-六氟丙烯的共聚物、聚酰胺、聚丙烯腈、聚丙烯酸酯、聚丙烯酸、聚丙烯酸盐、聚乙烯呲咯烷酮、聚乙烯醚、聚甲基丙烯酸甲酯、聚四氟乙烯或聚六氟丙烯中的至少一种。
本申请的电化学装置还包括电解质，本申请的电解质可以是凝胶电解质、固态电解质和电解液中的一种或多种，电解液包括锂盐和非水溶剂。在本申请一些实施方案中，锂盐可以包括但不限于LiPF 6、LiBF 4、LiAsF 6、LiClO 4、LiB(C 6H 5) 4、LiCH 3SO 3、LiCF 3SO 3、LiN(SO 2CF 3) 2、LiC(SO 2CF 3) 3、LiSiF 6、LiBOB或二氟硼酸锂中的至少一种，优选为LiPF 6。
上述非水溶剂可为碳酸酯化合物、羧酸酯化合物、醚化合物或其它有机溶剂中的至少一种。上述碳酸酯化合物可以包括但不限于链状碳酸酯化合物、环状碳酸酯化合物或氟代碳酸酯化合物中的至少一种。上述链状碳酸酯化合物可以包括但不限于碳酸二甲酯(DMC)、碳酸二乙酯(DEC)、碳酸二丙酯(DPC)、碳酸甲丙酯(MPC)、碳酸乙丙酯(EPC)或碳酸甲乙酯(MEC)中的至少一种。环状碳酸酯化合物可以包括但不限于碳酸乙烯酯(EC)、碳酸亚丙酯(PC)、碳酸亚丁酯(BC)或碳酸乙烯基亚乙酯(VEC)中的至少一种。氟代碳酸酯化合物可以包括但不限于氟代碳酸乙烯酯(FEC)、碳酸1,2-二氟亚乙酯、碳酸1,1-二氟亚乙酯、碳酸1,1,2-三氟亚乙酯、碳酸1,1,2,2-四氟亚乙酯、碳酸1-氟-2-甲基亚乙酯、碳酸1-氟-1-甲基亚乙酯、碳酸1,2-二氟-1-甲基亚乙酯、碳酸1,1,2-三氟-2-甲基亚乙酯或碳酸三氟甲基亚乙酯中的至少一种。上述羧酸酯化合物可以包括但不限于甲酸甲酯、乙酸甲酯、乙酸乙酯、乙酸正丙酯、乙酸叔丁酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、γ-丁内酯、 癸内酯、戊内酯、甲瓦龙酸内酯或己内酯中的至少一种。上述醚化合物可以包括但不限于二丁醚、四甘醇二甲醚、二甘醇二甲醚、1,2-二甲氧基乙烷、1,2-二乙氧基乙烷、乙氧基甲氧基乙烷、2-甲基四氢呋喃或四氢呋喃中的至少一种。上述其它有机溶剂可以包括但不限于二甲亚砜、1,2-二氧戊环、环丁砜、甲基环丁砜、1,3-二甲基-2-咪唑烷酮、N-甲基-2-吡咯烷酮、甲酰胺、二甲基甲酰胺、乙腈、磷酸三甲酯、磷酸三乙酯、磷酸三辛酯或磷酸酯中的至少一种。
本申请的电化学装置没有特别限制，其可以包括发生电化学反应的任何装置。在一些实施例中，电化学装置可以包括但不限于：锂金属二次电池、锂离子二次电池(锂离子电池)、锂聚合物二次电池或锂离子聚合物二次电池等。
电化学装置的制备过程为本领域技术人员所熟知的，本申请没有特别的限制，例如，可以包括但不限于以下步骤：将正极极片、隔膜和负极极片按顺序堆叠，并根据需要将其卷绕、折叠等操作得到卷绕结构的电极组件，将电极组件放入包装壳内，将电解液注入包装壳并封口，得到电化学装置；或者，将正极极片、隔膜和负极极片按顺序堆叠，然后用胶带将整个叠片结构的四个角固定好得到叠片结构的电极组件，将电极组件置入包装壳内，将电解液注入包装壳并封口，得到电化学装置。此外，也可以根据需要将防过电流元件、导板等置于包装壳中，从而防止电化学装置内部的压力上升、过充放电。其中，上述包装壳的材料可以是前述任一实施方案中的包装材料。
本申请的第二方面提供了一种电子装置，包含本申请任一实施方案中所述的电化学装置。本申请提供的电化学装置在低温下具有良好的性能，从而本申请提供的电子装置在低温下同样具有良好的低温性能。
本申请的电子装置没有特别限制，其可以是用于现有技术中已知的任何电子装置。在一些实施例中，电子装置可以包括但不限于：笔记本电脑、笔输入型计算机、移动电脑、电子书播放器、便携式电话、便携式传真机、便携式复印机、便携式打印机、头戴式立体声耳机、录像机、液晶电视、手提式清洁器、便携CD机、迷你光盘、收发机、电子记事本、计算器、存储卡、便携式录音机、收音机、备用电源、电机、汽车、摩托车、助力自行车、自行车、照明器具、玩具、游戏机、钟表、电动工具、闪光灯、照相机和家庭用大型蓄电池等。
本申请提供了一种电化学装置和电子装置，电化学装置包括极片，极片包括集流体，集流体包括第一集流体层、中间层、第二集流体层、第一导电端子和第二导电端子，其中， 中间层位于第一集流体层和第二集流体层之间，第一导电端子和第二导电端子与中间层形成电连接。将上述极片应用于电化学装置中，当电化学装置的温度低于设定值时(例如低于10℃)，第一导电端子和第二导电端子导通后通入电流，中间层对电化学装置进行加热；当电化学装置的温度达到目标加热温度时(例如高于35℃)时，第一导电端子和第二导电端子断开以，中间层停止对电化学装置加热。从而，电化学装置能够在低温条件下实现自加热，改善负极的析锂现象，同时使正极活性材料和负极活性材料克容量正常发挥，进而改善电化学装置在低温下的性能，例如能量密度、比容量和循环性能等。
附图说明
为了更清楚地说明本申请实施例和现有技术的技术方案，下面对实施例和现有技术中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请的一些实施例。
图1为本申请一些实施例中的正极极片的集流体的示意图；
图2为图1中的集流体的A-A向剖面示意图；
图3为图1中的集流体的B-B向剖面示意图；
图4为本申请一些实施例中的复合极片的集流体沿宽度方向的剖面示意图；
图5为本申请一些实施例中的正极极片的集流体沿宽度方向的剖面示意图；
图6为本申请一些实施例中的复合极片的集流体沿宽度方向的剖面示意图；
图7为本申请一些实施例中的正极极片的集流体的示意图；
图8为图7中的集流体的C-C向剖面示意图；
图9为图7中的集流体的D-D向剖面示意图；
图10为本申请一些实施例中的正极极片的集流体的示意图；
图11为图10中的集流体的E-E向剖面示意图；
图12为本申请一些实施例中的含有通孔的正极极片的集流体的示意图；
图13为图12中的集流体的F-F向剖面示意图；
图14为本申请一些实施例中的含有通孔的复合极片的集流体沿长度方向的剖面示意 图；
图15为本申请一些实施例中的具有图案的导电部的结构示意图；
图16为本申请一些实施例中的具有图案的导电部的结构示意图。
附图标记：10、第一集流体层，20、第二集流体层，31、第一电连接区域，32、第二电连接区域，41、第一导电端子，42、第二导电端子，51、绝缘部，511、第一绝缘层，512、第二绝缘层，52、导电部，60、通孔，70、图案。
具体实施方式
为使本申请的目的、技术方案、及优点更加清楚明白，以下参照附图并举实施例，对本申请进一步详细说明。显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员所获得的所有其他实施例，都属于本申请保护的范围。
需要说明的是，本申请的具体实施方式中，以锂离子电池作为电化学装置的例子来解释本申请，但是本申请的电化学装置并不仅限于锂离子电池。
图1至图3示出了本申请一些实施例中的正极集流体1a，其中，图1为正极集流体1沿厚度方向观察的示意图，图2为正极集流体1沿宽度方向的剖面示意图，图3为正极集流体沿长度方向的剖面示意图。绝缘部51包括第一绝缘层511和第二绝缘层512，导电部52位于第一绝缘层511和第二绝缘层512之间，第一集流体层10设置在第一绝缘层511远离导电部52的表面上，第二集流体层20设置在第二绝缘层512远离导电部52的表面上，从而实现导电部52与第一集流体层10和第二集流体层20之间的电绝缘。其中，第一集流体层10和第二集流体层20均为正极集流体层。本申请一些实施例中，参考图4，与图2所示结构相似，不同之处在于：第一集流体层10为正极集流体层，第二集流体层20为负极集流体层。当第一导电端子41和第二导电端子42导通后通入电流，导电部52对电化学装置进行加热，其加热均匀性较好。可以理解的是，第一集流体层和第二集流体层也可以均为负极集流体层，或者，第一集流体层为负极集流体层，第二集流体层为正极集流体层。
图5示出了本申请一些实施例中的正极集流体沿宽度方向的剖面示意图，绝缘部51将导电部52包裹，从而实现导电部52与第一集流体层10和第二集流体层20之间的电绝缘。第一导电端子41和第二导电端子42连接于导电部52，并从绝缘部51伸出。第一导 电端子41和第二导电端子42导通后通入电流，导电部52对电化学装置进行加热。其中，第一集流体层10和第二集流体层20均为正极集流体层。也可以如图6所示，第一集流体层10为正极集流体层，第二集流体层20为负极集流体层。可以理解的是，第一集流体层和第二集流体层也可以均为负极集流体层，或者，第一集流体层为负极集流体层，第二集流体层为正极集流体层。
图7至图9示出了本申请一些实施例中的正极集流体1b，图7为正极集流体1沿厚度方向观察的示意图，图8和图9为正极集流体1沿宽度方向不同区域的剖面示意图。导电部52与第一集流体层10之间存在第一电连接区域31、导电部52与第二集流体层20之间存在第二电连接区域32，从而实现导电部52与第一集流体层10和第二集流体层20之间的电连接，也即第一集流体层10和第二集流体层20之间能够实现电连接。第一导电端子41连接于第一集流体层10，第二导电端子42连接于第二集流体层20。这样，在第一导电端子41和第二导电端子42导通后通入电流，导电部52对电化学装置进行加热，其加热均匀性较好。此外，在电化学装置充放电过程中有利于充分发挥第一集流体层10和第二集流体层20的作用，从而提高电化学装置的电化学性能。其中，第一集流体层10和第二集流体层20均为正极集流体层。可以理解的是，第一导电端子可以连接于第一集流体层，第二导电端子连接于导电部；或者，第一导电端子连接于导电部，第二导电端子连接于第二集流体层；再者，第一导电端子和第二导电端子均连接于导电部。第一集流体层和第二集流体层也可以均为负极集流体层。
图10和图11示出了本申请一些实施例中的正极集流体1c，其中图10为正极集流体1c沿厚度方向观察的示意图，图11为正极集流体1c沿长度方向的剖面示意图。绝缘部51将导电部52包裹，从而实现导电部52与第一集流体层10和第二集流体层20之间的电绝缘。导电部52包括导电子区域X和Y，导电子区域X和Y均连接有第一导电端子41和第二导电端子42，导电子区域X和Y的面积大小相同。第一导电端子41和第二导电端子42导通后通入电流，导电子区域X和Y均可以对电化学装置进行加热，导电子区域X和Y的设置可以满足不同区域的不同加热需求。其中，第一集流体层10和第二集流体层20均为正极集流体层。可以理解的是，导电子区域X和Y的面积大小也可以不相同，第一集流体层和第二集流体层也可以均为负极集流体层；或者，第一集流体层为正极集流体层，第二集流体层为负极集流体层；再者，第一集流体层为负极集流体层，第二集流体层为正极集流体层。
图12和图13示出了本申请一些实施例中的正极集流体1d，其中，图12为正极集流 体1d沿厚度方向观察的示意图，图13为正极集流体1d沿长度方向的剖面示意图。导电部52包括导电子区域Z和W，通孔60设置在导电子区域Z和W之间，通孔60中的填充物质为导电物质，通过通孔60中的导电物质能够实现第一集流体层10和第二集流体层20之间的电连接，这样，在第一导电端子41和第二导电端子42导通后通入电流，导电部52对电化学装置进行加热，有利于加热过程中热量的传递。此外，在电化学装置充放电过程中有利于充分发挥第一集流体层10和第二集流体层20的作用，从而提高电化学装置的电化学性能。其中，第一集流体层10和第二集流体层20均为正极集流体层。此外，通孔60中的导电物质与导电部52之间电绝缘，通孔60设置在沿中间层厚度方向只有绝缘部51的区域，通孔60并未贯穿导电部52，避免影响导电部52对电化学装置的加热效果。可以理解的是，第一集流体层和第二集流体层也可以均为负极集流体层。
图14示出了本申请一些实施例中的含有通孔的复合极片的集流体沿长度方向的剖面示意图，通孔60中的填充有电性绝缘的离子导体，使得第一集流体层10和第二集流体层20之间电绝缘，并能够形成连通第一集流体层10和第二集流体层20两侧的离子通路，以改善极片的离子传导能力，进而提升电化学装置的电化学性能。其中，第一集流体层10为正极集流体层，第二集流体层20为负极集流体层。可以理解的是，也可以是第一集流体层为负极集流体层，第二集流体层为正极集流体层，或者，第一集流体层和第二集流体层均为正极集流体层，再者，第一集流体层和第二集流体层均为负极集流体层。
图15和图16分别示出了本申请一些实施例中的中间层的导电部，第一导电部31在其厚度方向投影面具有图案70，而且，图15中图案与导电部52的分布区域的面积小于图16中图案与导电部52的分布区域的面积。可以理解的是，该图案的分布区域大小也可以根据实际情况进行选择。
实施例
以下，举出实施例及对比例来对本申请的实施方式进行更具体地说明。各种的试验及评价按照下述的方法进行。另外，只要无特别说明，“份”、“％”为质量基准。
测试方法和设备：
加热速率测试：
环境温度为T 0，加热目标温度为T 1(锂离子电池表面最低温度达到T 1)所需时间为t，加热速率＝(T 1-T 0)/t。
表面温差测试：
锂离子电池表面不同位置(中部、头部(Tab下方)、尾部)分别贴感温线，检测锂离子电池加热过程不同位置的温度，锂离子电池的表面温差为表面最高温度与最低温度之间的差值。
15℃满充时间测试：
环境温度15℃，以1C恒流充电至4.45V，再以4.45V恒压充电，充电至截止电流为0.025C，充电时间为该温度下满充时间。
体积能量密度测试：
将锂离子电池在25℃下充电至4.45V后，采用0.2C放电至3V，得到锂离子电池放电容量(C)和平均电压平台(U)，再用激光测厚仪测试锂离子电池的长、宽、高，得到锂离子电池的体积(V)，其体积能量密度(ED)可通过如下公式计算得到：ED＝C×U/V。
实施例1
<中间层的制备>
将具有图案(图案形状如图15所示)的第一导电端子与第二导电端子间阻值为800mΩ的Cu金属片(导电部)设置于两片PET薄膜(绝缘部)之间。第一导电端子和第二导电端子连接在Cu金属片(如图15所示)，并从PET薄膜伸出。PET薄膜热融合后得到中间层。其中，金属片的厚度为5μm，中间层的厚度为8μm。
<正极极片的制备>
采用真空沉积法在上述得到的中间层的两个表面上分别制备厚度为0.5μm的Al镀层，形成第一集流体层和第二集流体层，得到复合正极集流体。将正极活性材料钴酸锂(LiCoO 2)、导电炭黑(Super P)、聚偏二氟乙烯(PVDF)按照重量比97.5∶1.0∶1.5进行混合，加入N-甲基吡咯烷酮(NMP)作为溶剂，调配成为固含量为75％的正极浆料，并搅拌均匀。将浆料均匀涂覆在复合正极集流体的一个表面上，其中正极活性材料的含量为180g/m 2，90℃条件下烘干，得到单面涂布正极活性材料的正极极片。在复合正极集流体的另一个表面上重复以上步骤，即得到双面涂布正极活性材料的正极极片。然后经过冷压、裁片、分切后，在85℃的真空条件下干燥4h，得到规格为74mm×867mm的正极极片。其中，正极极片的压实密度为4.1g/cm 3。
<负极极片的制备>
采用真空沉积法在上述得到的中间层的两个表面上分别制备厚度为0.5μm的Cu镀层，得到复合负极集流体。将负极活性材料石墨、导电炭黑(Super P)、丁苯橡胶(SBR)按照重量比96∶1.5∶2.5进行混合，加入去离子水(H 2O)作为溶剂，调配成为固含量为70％的负极浆料，并搅拌均匀。将浆料均匀涂覆在复合负极集流体的一个表面上，其中负极活性材料的含量为95g/m 2，110℃条件下烘干，得到单面涂布负极活性材料的负极极片。在复合负极集流体的另一个表面上重复以上步骤，即得到双面涂布负极活性材料的负极极片。然后经过冷压、裁片、分切后，在85℃的真空条件下干燥4h，得到规格为74mm×867mm的负极极片。其中，负极极片的压实密度为1.7g/cm 3。
<电解液的制备>
在干燥氩气气氛中，将有机溶剂碳酸乙烯酯(EC)、碳酸甲乙酯(EMC)和碳酸二乙酯(DEC)按照质量比EC∶EMC∶DEC＝30∶50∶20进行混合，然后向有机溶剂中加入锂盐六氟磷酸锂(LiPF 6)溶解并混合均匀，其中，锂盐在电解液中的浓度为1.15mol/L。
<锂离子电池的制备>
选用厚度为15μm的聚乙烯(PE)作为隔离膜，将正极极片、隔离膜、负极极片按照顺序叠好，使隔离膜处于正中间的位置，卷绕得到电极组件。将电极组件置于铝塑膜包装袋中，干燥后注入电解液，经过真空封装、静置、化成、脱气、切边等工序得到锂离子电池。其中，化成条件是以0.02C恒流充电到3.3V，再以0.1C恒流充电到3.6V。其中，第一导电端子及第二导电端子从包装袋伸出与电源连接。上述电源是指能够提供电流的电源。
实施例2至实施例3中，除了调整金属片投影面上具有的图案的导电部分布区域的面积使得两个导电端子之间的阻值如表1所示以外，其余与实施例1相同。
实施例4中，除了在<中间层的制备>中，除了将导电层端部分别与第一集流体层及第二集流体层进行焊接，形成如图7至图9所示结构的集流体以外，其余与实施例1相同。
实施例5中，除了在<中间层的制备>中，将两个金属片设置于两片薄膜之间，其中每个金属片连接有第一导电端子和第二导电端子，形成如图10和图11所示结构的集流体以外，其余与实施例1相同。
实施例6中，除了<复合极片的制备>和<锂离子电池的制备>采用以下步骤，其余与实 施例1相同：
<复合极片的制备>
采用真空沉积法在中间层的两个表面上分别制备厚度为0.5μm的Al镀层和厚度为0.5μm的Cu镀层，然后将正极浆料涂覆在Al镀层上，将负极浆料涂覆在Cu镀层上，60℃条件下烘干得到复合极片。然后经过冷压、裁片、分切后，在85℃的真空条件下干燥4h，得到规格为74mm×867mm的复合极片。其中，负极极片的压实密度为1.7g/cm 3。
<锂离子电池的制备>
选用厚度为15μm的聚乙烯(PE)作为隔离膜，将复合极片、隔离膜、复合极片按照顺序叠好，使两个复合极片相邻的表面极性相反设置，卷绕得到电极组件。将电极组件置于铝塑膜包装袋中，干燥后注入电解液，经过真空封装、静置、化成、脱气、切边等工序得到锂离子电池。其中，化成条件是以0.02C恒流充电到3.3V，再以0.1C恒流充电到3.6V。其中，第一导电端子及第二导电端子从包装袋伸出与电源连接。上述电源是指能够提供电流的电源。
实施例7中，除了在正极极片和负极极片上采用激光打孔法设置多个圆形通孔、通孔中填充的导电物质为导电碳粉、通孔的孔径为500μm、孔密度为5个/cm 2、通孔的面积占比为1％以外，其余与实施例1相同。
实施例8中，除了将导电碳粉替换为电性绝缘的离子导体Al 2O 3以外，其余与实施例10相同。
实施例9和实施例10中，除了按照表1调整金属层的厚度以外，其余与实施例1相同。其中，实施例9中间层厚度为11μm，实施例10中间层厚度为18μm。
对比例1中，除了中间层采用厚度为8μm的PET薄膜以外，其余与实施例1相同。
对比例2中，选择厚度为5μm的镍片，镍片的投影面上具有图案(图案形状如图15所示)，与镍片连接的第一导电端子和第二导电端子之间阻值为800mΩ，采用PET薄膜封装镍片。其中，第一导电端子和第二导电端子从PET薄膜中伸出，封装后的镍片厚度为8μm。在<锂离子电池制备>的步骤中，将正极极片、隔离膜、负极极片按照顺序叠好，使隔离膜处于正中间的位置，将上述镍片置于卷绕起点，卷绕得到电极组件，其余与对比例1相同。
实施例1至实施例10、对比例1至对比例2的制备参数及性能测试如表1所示：
表1
Figure PCTCN2021119436-appb-000001
注：“/”表示不存在对应的参数。
参考表1，从实施例1至实施10、对比例1和对比例2可以看出，本申请提供的电化学装置可以通过在集流体中导电部的设置，在基本不损失能量密度的同时，实现对电化学装置的均匀加热，从而提升电化学装置整体的加热速率，并显著缩短15℃条件下的满充时间，表明本申请提供的电化学装置在低温条件下仍具有良好的充电性能和较高的能量密度。电化学装置15℃的满充时间和体积能量密度随着第一导电端子和第二导电端子之间的阻值以及导电部厚度的变化而变化，当第一导电端子和第二导电端子之间的阻值、导电部厚度在本申请的范围内，得到的电化学装置具有良好的充电性能和较高的能量密度。
以上所述仅为本申请的较佳实施例，并不用以限制本申请，凡在本申请的精神和原则之内，所做的任何修改、等同替换、改进等，均应包含在本申请保护的范围之内。

Claims (10)

  1. 一种电化学装置，其包括极片，所述极片包括集流体，
    所述集流体包括第一集流体层、中间层、第二集流体层、第一导电端子和第二导电端子，
    其中，所述中间层位于所述第一集流体层和所述第二集流体层之间，
    所述第一导电端子和所述第二导电端子与所述中间层形成电连接，所述第一导电端子与所述第二导电端子间具有阻值为R的电阻，当电化学装置的温度低于设定值时，可激活所述电阻。
  2. 根据权利要求1所述的电化学装置，其中，所述电化学装置还包括正极极耳和负极极耳，所述正极极耳和所述负极极耳之间具有内阻，所述内阻阻值为R’，R的取值满足5≤R/R’≤1000。
  3. 根据权利要求1所述的电化学装置，其中，R的取值为200mΩ至1500mΩ。
  4. 根据权利要求1所述的电化学装置，其中，所述集流体的中间层包括导电部和绝缘部，所述导电部与所述第一集流体层的至少一部分形成电绝缘，所述导电部与所述第二集流体层的至少一部分形成电绝缘。
  5. 根据权利要求4所述的电化学装置，所述集流体满足以下条件(i)至(ii)中的其中一者：
    (i)所述导电部与所述第一集流体层形成电绝缘，并且所述导电部与所述第二集流体层形成电绝缘，所述第一导电端子和所述第二导电端子连接于所述导电部；
    (ii)所述导电部与所述第一集流体层形成电连接，并且所述导电部与所述第二集流体层形成电绝缘，所述第一导电端子连接于所述第一集流体层，所述第二导电端子连接于所述导电部；
    (iii)所述导电部与所述第一集流体层和所述第二集流体层形成电连接，所述第一导电端子连接于所述导电部或所述第一集流体层，所述第二导电端子连接于所述导电部或所述第二集流体层，所述第一集流体层和所述第二集流体层极性相同。
  6. 根据权利要求1所述的电化学装置，其中，所述集流体包括通孔，所述通孔贯穿所述第一集流体层、所述第二集流体层和所述中间层。
  7. 根据权利要求6所述的电化学装置，其中，所述集流体满足以下条件(iv)至(v)中的其中一者：
    (iv)所述通孔中填充有导电物质，所述第一集流体层和所述第二集流体层的极性相同；
    (v)所述通孔中填充有电性绝缘的离子导体，所述第一集流体层和所述第二集流体层的极性不同，所述第一集流体和所述第二集流体之间呈电性绝缘状态。
  8. 根据权利要求4所述的电化学装置，其中，所述导电部在所述集流体厚度方向投影面上具有图案，和/或导电部的厚度为5μm至20μm。
  9. 根据权利要求1至8中任一项所述的电化学装置，其中，所述极片为正极极片、负极极片或复合极片。
  10. 一种电子装置，其包括权利要求1至9中任一项所述的电化学装置。
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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013186079A1 (de) * 2012-06-15 2013-12-19 Robert Bosch Gmbh Vorrichtung und verfahren zum heizen einer batterie, batterie und kraftfahrzeug mit batterie
JP2016012494A (ja) * 2014-06-30 2016-01-21 三菱自動車工業株式会社 電池
CN110402519A (zh) * 2017-03-22 2019-11-01 通用汽车环球科技运作有限责任公司 自动加热蓄电池
CN112599785A (zh) * 2021-03-03 2021-04-02 浙江艾罗网络能源技术股份有限公司 一种锂离子电池自控温集流体及其制备方法、应用

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013186079A1 (de) * 2012-06-15 2013-12-19 Robert Bosch Gmbh Vorrichtung und verfahren zum heizen einer batterie, batterie und kraftfahrzeug mit batterie
JP2016012494A (ja) * 2014-06-30 2016-01-21 三菱自動車工業株式会社 電池
CN110402519A (zh) * 2017-03-22 2019-11-01 通用汽车环球科技运作有限责任公司 自动加热蓄电池
CN112599785A (zh) * 2021-03-03 2021-04-02 浙江艾罗网络能源技术股份有限公司 一种锂离子电池自控温集流体及其制备方法、应用

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