WO2024065404A1 - 电化学装置以及电子设备 - Google Patents

电化学装置以及电子设备 Download PDF

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WO2024065404A1
WO2024065404A1 PCT/CN2022/122643 CN2022122643W WO2024065404A1 WO 2024065404 A1 WO2024065404 A1 WO 2024065404A1 CN 2022122643 W CN2022122643 W CN 2022122643W WO 2024065404 A1 WO2024065404 A1 WO 2024065404A1
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Prior art keywords
carbon nanotube
current collector
active material
nanotube array
electrochemical device
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English (en)
French (fr)
Inventor
蔡晓生
张楠
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Ningde Amperex Technology Ltd
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Ningde Amperex Technology Ltd
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Priority to PCT/CN2022/122643 priority Critical patent/WO2024065404A1/zh
Priority to CN202280049747.9A priority patent/CN117999664A/zh
Publication of WO2024065404A1 publication Critical patent/WO2024065404A1/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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof

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  • the present application relates to the field of battery technology, and in particular to an electrochemical device and an electronic device.
  • High energy density batteries can be achieved through changes in the chemical system, battery structure design or system structure design; among them, the change of the chemical system can adopt high capacity/high voltage positive and negative electrode materials, such as high nickel ternary, high voltage LNMO, etc. for the positive electrode, and silicon negative electrode, lithium metal, etc. for the negative electrode; battery structure design can be achieved by increasing the density of the pole pieces, reducing the proportion of inactive substances, different winding/stacking methods, etc.; system structure design includes reducing the proportion of inactive substances inside the system, optimizing the series and parallel methods, model design, optimizing BMS and other aspects.
  • high capacity/high voltage positive and negative electrode materials such as high nickel ternary, high voltage LNMO, etc. for the positive electrode, and silicon negative electrode, lithium metal, etc. for the negative electrode
  • battery structure design can be achieved by increasing the density of the pole pieces, reducing the proportion of inactive substances, different winding/stacking methods, etc.
  • system structure design includes reducing the proportion of inactive substances inside the system
  • the above-mentioned battery structure design can improve energy density by reducing the proportion of active materials.
  • the industry adopts the thick electrode solution.
  • the proportion of the current collector inside the battery can be greatly reduced.
  • the battery can be made thinner and lighter, thereby improving the volume energy density and mass density of the battery; in addition, the reduction in the use of inactive material current collectors can reduce battery costs.
  • the reduction of copper and/or aluminum current collectors can reduce the overall carbon emissions of the battery, which is consistent with the national carbon neutrality development goal.
  • the increase in the thickness of the active material coating in the thick electrode causes the battery's kinetic performance to deteriorate.
  • the embodiments of the present application provide an electrochemical device and an electronic device, which can solve the problem of deterioration of battery kinetic performance due to increase in the thickness of active material coating in thick electrodes, and can improve the rate performance, cycle performance and energy density of the battery by improving the kinetic performance of the thick electrodes.
  • an embodiment of the present application provides an electrochemical device, comprising an electrode plate; the electrode plate comprises a current collector, a carbon nanotube array located on at least one side of the current collector, and an active material layer; the active material layer comprises an active material; the number of the carbon nanotube arrays is at least two, and the active material is located between at least two of the carbon nanotube arrays; the active material comprises a plurality of active material particles.
  • the thickness of the active material layer is H, and the length of the carbon nanotube array is h, satisfying: 0.7h ⁇ H ⁇ 1.3h, and 40 ⁇ m ⁇ H ⁇ 500 ⁇ m; wherein the length direction of the carbon nanotube array is perpendicular to the surface of the current collector, and the thickness direction of the active material layer is parallel to the length direction of the carbon nanotube array.
  • One of the multiple active material particles (active material particle one) is in contact with the current collector, and the contact position of the active material particle one with the current collector is regarded as the starting end.
  • another active material particle (active material particle two) is farthest away from the current collector.
  • the position on the active material particle two that is farthest away from the current collector and corresponding to the starting end is regarded as the ending end.
  • the distance between the starting end and the ending end is the thickness H of the active material layer.
  • the surface surrounded by the bottom ends of the carbon nanotube array is the first surface
  • the surface surrounded by the top ends of the carbon nanotube array is the second surface.
  • the distance between the first surface and the second surface is the length h of the carbon nanotube array described in this application.
  • the length direction of the carbon nanotube array refers to the extension direction from the bottom end of the carbon nanotube array toward the top end of the carbon nanotube array
  • the thickness direction of the active material layer refers to the extension direction from the starting end toward the tail end; further, the length direction of the carbon nanotube array is perpendicular to the surface of the current collector, and the thickness direction of the active material layer is parallel to the length direction of the carbon nanotube array.
  • the angle between the extension line of the carbon nanotube array in the length direction and the surface of the current collector is in the range of 60° to 90°, which can be regarded as perpendicular to the surface as described in the present application; and the angle formed by the intersection of the extension line of the active material in the thickness direction and the extension line of the carbon nanotube array in the length direction is in the range of 0° to 30°, which can be regarded as parallel as described in the present application.
  • the electrochemical device satisfies: 0.9h ⁇ H ⁇ 1.1h, and 40 ⁇ m ⁇ H ⁇ 200 ⁇ m.
  • the electrochemical device satisfies:
  • the mass of the carbon nanotube array refers to the total mass of the carbon nanotube array contained on the current collector
  • the mass of the membrane refers to the total mass of the electrode plate without the current collector
  • the thickness of the membrane refers to the thickness of the membrane on one side of the current collector.
  • the electrochemical device satisfies at least one of the following conditions:
  • the electrochemical device satisfies:
  • the average particle size of the active substance is D, satisfying: 5 ⁇ m ⁇ D ⁇ 30 ⁇ m;
  • the major diameter of the carbon nanotube array is m, satisfying: m ⁇ d(gap)/2;
  • Adjacent carbon nanotube arrays may be adjacent in the length direction of the current collector or in the width direction of the current collector; for example, in the length direction of the current collector, the spacing d (gap) between adjacent carbon nanotube arrays refers to the spacing between two carbon nanotube arrays in the transverse direction; in the width direction of the current collector, the spacing d (gap) between adjacent carbon nanotube arrays refers to the spacing between two carbon nanotube arrays in the longitudinal direction; similarly, in the same array, adjacent carbon nanotubes may be adjacent in the length direction of the current collector or in the width direction of the current collector. And, in the length direction of the current collector, the spacing between a carbon nanotube at one end of a carbon nanotube array and another corresponding carbon nanotube at the other end is the major diameter m of the carbon nanotube array described in the present application.
  • the electrochemical device satisfies at least one of the following conditions:
  • the average particle size of the active substance is D, satisfying: 5 ⁇ m ⁇ D ⁇ 15 ⁇ m;
  • the diameter of the carbon nanotubes in the carbon nanotube array is 5 nm to 500 nm.
  • the carbon nanotubes in the carbon nanotube array include at least one of single-walled carbon nanotubes or multi-walled carbon nanotubes;
  • the carbon nanotubes are multi-walled carbon nanotubes, and the diameter of the multi-walled carbon nanotubes is 50 nm to 500 nm.
  • the carbon nanotubes are multi-walled carbon nanotubes, and the diameter of the multi-walled carbon nanotubes is 100 nm to 200 nm.
  • an embodiment of the present application provides an electronic device comprising any of the electrochemical devices described above.
  • the present application arranges a plurality of carbon nanotube arrays in a distributed and aligned manner on the current collector, and fills active materials between different carbon nanotube arrays.
  • the carbon nanotube arrays with the above structure can provide a vertical conductive path, improve the problem of long electron conduction paths in thick electrodes, and accelerate electron conduction;
  • the carbon nanotubes in the above structure have high mechanical strength, which can alleviate the volume expansion problem during the charge and discharge process of the electrode, avoid the active material from falling off, and deteriorate the electrical performance; and the carbon nanotubes have high thermal conductivity, which can reduce the charge and discharge temperature rise and improve the thermal stability of the battery;
  • the blanking treatment between adjacent carbon nanotubes in the same array can accelerate the electrolyte infiltration during the manufacturing process, increase the overall porosity of the electrode, and help improve the ion transmission efficiency in the electrolyte.
  • FIG1 is a schematic diagram of the cross-sectional structure of an electrode plate in an embodiment of the present application.
  • FIG2 is a schematic diagram of a top view of the electrode plate in an embodiment of the present application.
  • FIG3 is a cross-sectional schematic diagram of the active material filled on the current collector in an embodiment of the present application.
  • FIG. 4 is a schematic diagram of a top view of a distributed carbon nanotube array that is not filled with active material in an embodiment of the present application.
  • lithium ions are charged and discharged based on the rocking chair working principle. That is, during the battery charging process, the cathode active material loses electrons, lithium ions escape from the lattice of the cathode material, and migrate to the negative electrode of the battery through the electrolyte and the diaphragm. The lithium ions are embedded in the negative electrode. At this time, the electrons also reach the negative electrode side through the external circuit, and the electrons obtained by the negative electrode combine with the embedded lithium ions to form a lithium-carbon intercalation compound. During discharge, the opposite process occurs.
  • the commonly used solution for electronic conductivity is to increase the amount of conductive agent used.
  • the conductive agent is changed from 0-dimensional acetylene black to one-dimensional carbon nanotubes or two-dimensional graphene conductive agents. Compared with zero-dimensional conductive agents, one-dimensional and two-dimensional conductive agents are helpful in improving the overall conductivity of the electrode, but because the conductive agent is scattered in the electrode, it cannot be well oriented to improve the conductivity of the electrode in the vertical direction, because the improvement effect is limited.
  • the commonly used solution for ionic conductivity is to increase the overall porosity of the pole piece or to manufacture a gap structure.
  • Increasing the porosity of the pole piece can increase the amount of electrolyte retained and improve the transmission of lithium ions in the electrolyte to a certain extent, but because the lithium ion transmission path is still tortuous, the improvement is limited.
  • the method of manufacturing a gap structure is one of the key means to improve the kinetics of thick electrodes. By manufacturing a gap structure, the lithium ion transmission path can be optimized, the tortuosity can be reduced, and the transmission capacity of lithium-ion batteries can be greatly improved.
  • the commonly used means of manufacturing gap structures include 3D printing technology and freeze-drying technology, which are technologies with slow production rates and far from industrialization. Similar technical problems also exist in sodium-ion batteries.
  • the present application proposes an electrochemical device and an electronic device.
  • the electrochemical device includes an electrode plate; the electrode plate includes a current collector, a carbon nanotube array located on at least one side of the current collector, and an active substance; the number of the carbon nanotube arrays is at least two, and the active substance is located between the two carbon nanotube arrays; the active substance includes a plurality of active substance particles.
  • the present application arranges multiple carbon nanotube arrays on the current collector, and the multiple carbon nanotube arrays are evenly distributed and aligned, and the alignment includes lateral alignment and longitudinal alignment. Active materials are filled between different carbon nanotube arrays instead of filling the active materials inside the carbon nanotube arrays. Active materials are filled in the gaps between different carbon nanotube arrays, and blank spaces are left between the carbon nanotubes in the array (blank spaces mean no filling).
  • the carbon nanotube array in the above structure can provide a vertical conductive path, directionally improve the conductivity of the electrode in the vertical direction, which is beneficial to improve the problem of long electron conduction path, and can accelerate electron conduction and improve electron conductivity;
  • the blank gaps between the carbon nanotubes in a single carbon nanotube array of the above structure can provide a vertical, low-tortuosity ion transmission path, greatly shorten the ion transmission distance, reduce the concentration polarization phenomenon during battery charging and discharging, and help improve ion conductivity.
  • the length marked at H in the figure is the thickness of the active material layer described in the present application
  • the length marked at h in the figure is the length of the carbon nanotube array described in the present application.
  • the thickness of the active material layer is H, and the length of the carbon nanotube array is h, satisfying: 0.7h ⁇ H ⁇ 1.3h, and 40 ⁇ m ⁇ H ⁇ 500 ⁇ m; wherein the length direction of the carbon nanotube array is perpendicular to the surface of the current collector, and the thickness direction of the active material layer is parallel to the length direction of the carbon nanotube array.
  • the thickness H of the active material layer is 40 ⁇ m, 80 ⁇ m, 100 ⁇ m, 200 ⁇ m, 300 ⁇ m, 500 ⁇ m, or a range consisting of any two of the above values.
  • a ratio H/h of a thickness H of the active material layer to a length h of the carbon nanotube array is 0.7, 0.8, 1.0, 1.2, 1.3 or a range consisting of any two of the above values.
  • the thickness H of the active material layer is 40 ⁇ m, 60 ⁇ m, 80 ⁇ m, 100 ⁇ m, 120 ⁇ m, 140 ⁇ m, 160 ⁇ m, 180 ⁇ m, 200 ⁇ m or a range consisting of any two of the above values.
  • the ratio H/h of the thickness H of the active material layer to the length h of the carbon nanotube array is 0.9, 0.95, 1.0, 1.05, 1.1 or a range consisting of any two of the above values.
  • the electrochemical device satisfies:
  • the area enclosed by the bottom of the carbon nanotubes in contact with the current collector is S 1
  • the area covered by the active material on the current collector is S 2
  • the ratio of S 1 to S 2 is 2:98, 4:96, 8:92, 10:90, 15:85, 20:80 or a range consisting of any two of the above values.
  • the ratio M of the mass of the carbon nanotube array to the mass of the membrane is 1%, 5%, 8%, 10%, 13%, 15% or a range consisting of any two of the above values.
  • the ratio M′ of the mass of the active substance to the mass of the membrane is 84%, 86%, 88%, 90%, 92%, 94%, 96%, 98%, 98.5% or a range consisting of any two of the above values.
  • the electrochemical device satisfies at least one of the following conditions:
  • the area enclosed by the bottom of the carbon nanotubes in contact with the current collector is S 1
  • the area covered by the active material on the current collector is S 2
  • the ratio of S 1 to S 2 is 5:95, 7:93, 9:91, 11:89, 13:87, 15:85 or a range consisting of any two of the above values.
  • the ratio M of the mass of the carbon nanotube array to the mass of the membrane is 2%, 4%, 6%, 8%, 10% or a range consisting of any two of the above values.
  • the ratio M′ of the mass of the active substance to the mass of the membrane is 89%, 91%, 93%, 95%, 97% or a range consisting of any two of the above values.
  • the length marked d (gap) in the figure is the spacing between adjacent carbon nanotube arrays in the length direction of the current collector as described in the present application
  • the length m marked in the figure is the major diameter of the carbon nanotube array as described in the present application
  • the length d marked in the figure is the distance between adjacent carbon nanotubes in the same array as described in the present application.
  • the electrochemical device satisfies:
  • the average particle size of the active substance is D, satisfying: 5 ⁇ m ⁇ D ⁇ 30 ⁇ m;
  • the major diameter of the carbon nanotube array is m, satisfying: m ⁇ d(gap)/2;
  • the average particle size D of the active material is 5 ⁇ m, 8 ⁇ m, 10 ⁇ m, 15 ⁇ m, 30 ⁇ m, or a range consisting of any two of the above values.
  • the spacing d (gap) between adjacent carbon nanotube arrays is 2D, 4D, 8D, 10D, 15D, 20D or a range consisting of any two of the above values.
  • the distance d between adjacent carbon nanotubes in the same array is 10 nm, 50 nm, 80 nm, 100 nm, 300 nm, 500 nm, or a range consisting of any two of the above values.
  • the electrochemical device satisfies at least one of the following conditions:
  • the average particle size of the active substance is D, satisfying: 5 ⁇ m ⁇ D ⁇ 15 ⁇ m;
  • the average particle size D of the active substance is 5 ⁇ m, 7 ⁇ m, 9 ⁇ m, 11 ⁇ m, 13 ⁇ m, 15 ⁇ m, or a range consisting of any two of the above values.
  • the spacing d (gap) between adjacent carbon nanotube arrays is 2D, 4D, 6D, 8D, 10D or a range consisting of any two of the above values.
  • the diameter of the carbon nanotubes in the carbon nanotube array is 5 nm to 500 nm.
  • the diameter of the carbon nanotubes in the carbon nanotube array is 5 nm, 20 nm, 80 nm, 120 nm, 150 nm, 200 nm, 400 nm, 500 nm, or a range consisting of any two of the above values.
  • the carbon nanotubes in the carbon nanotube array include at least one of single-walled carbon nanotubes or multi-walled carbon nanotubes;
  • the carbon nanotubes in the carbon nanotube array include multi-walled carbon nanotubes; in another example, the carbon nanotubes in the carbon nanotube array include multi-walled carbon nanotubes and single-walled carbon nanotubes; or in other examples, the carbon nanotubes in the carbon nanotube array include multi-walled carbon nanotubes and single-walled carbon nanotubes.
  • the carbon nanotubes are multi-walled carbon nanotubes, and the diameter of the multi-walled carbon nanotubes is 50 nm to 500 nm.
  • the diameter of the multi-walled carbon nanotube is 50 nm, 150 nm, 300 nm, 450 nm, 500 nm, or a range consisting of any two of the above values.
  • the carbon nanotubes are multi-walled carbon nanotubes, and the diameter of the multi-walled carbon nanotubes is 100 nm to 200 nm.
  • the diameter of the multi-walled carbon nanotube is 100 nm, 120 nm, 140 nm, 160 nm, 180 nm, 200 nm, or a range consisting of any two of the above values.
  • the carbon nanotube array is distributed on one side of the current collector; or, in another example, the carbon nanotube array is distributed on both sides of the current collector.
  • the distribution generally refers to uniform distribution, that is, the carbon nanotube array is uniformly distributed on one side or both sides of the current collector, which is selected according to actual conditions, and the present application does not limit this.
  • a primer layer is disposed on at least one surface of the current collector, the primer layer covers the surface of the current collector, and the primer layer includes at least one of a conductive carbon layer and a high adhesion layer.
  • a conductive carbon layer is provided on at least one surface of the current collector; or in another example, a conductive carbon layer and a high adhesion layer are provided on at least one surface of the current collector.
  • the bonding force between the conductive carbon layer and/or the high bonding layer and the current collector is F, and F ⁇ 3N/m; if the bonding force F ⁇ 3N, the interface bonding force between the active material layer and the current collector is poor, which will deteriorate the electronic impedance of the interface, thereby deteriorating the battery performance, and there is also a risk of the active material falling off the current collector.
  • the active material layer includes an active material.
  • the value range of the adhesion force F between the conductive carbon layer and/or the high adhesion layer and the current collector is: F ⁇ 5N/m.
  • any of the above electrochemical devices may be a lithium ion battery or a sodium ion battery.
  • the present application also provides an electronic device, including any one of the above electrochemical devices.
  • the electronic device of the present application can be used for, but not limited to, laptop computers, pen-input computers, mobile computers, e-book players, portable phones, portable fax machines, portable copiers, portable printers, head-mounted stereo headphones, video recorders, LCD televisions, portable cleaners, portable CD players, mini-discs, transceivers, electronic notepads, calculators, memory cards, portable recorders, radios, backup power supplies, motors, cars, motorcycles, power-assisted bicycles, bicycles, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, large household batteries and lithium-ion capacitors, etc.
  • the two-dimensional planar conductive substrate includes aluminum foil, copper foil, stainless steel foil, nickel foil, iron foil, gold foil, silver foil, platinum foil, titanium foil, zinc foil, manganese foil, carbon film, other composite metal foils, conductive polymer films or composite polymer-metal films.
  • the positive electrode active material includes at least one of NCM811, NCM622, NCM523, NCM111, NCA, lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, lithium iron manganese phosphate or lithium titanate.
  • the negative electrode active material includes at least one of graphite, pure silicon, hard carbon, silicon carbon or silicon oxide, tin, tin compound, lithium metal and other high expansion negative electrode materials, preferably pure silicon material.
  • the electrolyte of the lithium-ion battery is not particularly limited, and any electrolyte known in the art can be used, which can be any of a gel state, a solid state and a liquid state.
  • the liquid electrolyte includes a lithium salt and a non-aqueous solvent.
  • the lithium salt is not particularly limited, and any lithium salt known in the art can be used as long as the purpose of the present application can be achieved.
  • the lithium salt can include at least one of 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 CF 3 ) 2 , LiC(SO 2 CF 3 ) 3 or LiPO 2 F 2 , etc.
  • the lithium salt can be LiPF 6 .
  • the non-aqueous solvent is not particularly limited as long as the purpose of the present application can be achieved.
  • the non-aqueous solvent may include at least one of carbonate compounds, carboxylate compounds, ether compounds, nitrile compounds or other organic solvents.
  • the carbonate compound may include at least one of diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), ethyl methyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinyl ethylene carbonate (VEC), fluoroethylene carbonate (FEC), 1,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate, 1,1,2-trifluoroethylene carbonate, 1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2-difluoro-1-methylethylene carbonate, 1,1,2-trifluoro-2-methylethylene carbonate or trifluoromethylethylene carbonate, etc.
  • DEC diethyl carbonate
  • DMC dimethyl carbonate
  • DPC dipropyl carbon
  • the positive electrode active material lithium cobalt oxide (LiCoO 2 ), conductive carbon black (Super P), and polyvinylidene fluoride (PVDF) were mixed at a weight ratio of 97.5:1.0:1.5, and N-methylpyrrolidone (NMP) was added as a solvent to prepare a slurry with a solid content of 0.75, and stirred evenly.
  • NMP N-methylpyrrolidone
  • the slurry was evenly coated on the positive electrode current collector aluminum foil and dried at 90°C to obtain a positive electrode sheet. After coating, the sheet was cut into a specification of (980mm ⁇ 58mm) for standby use.
  • the single-sided coating of the positive electrode sheet is completed. Afterwards, these steps are also completed on the back of the sheet in a completely consistent manner to obtain a double-sided coated positive electrode sheet.
  • the negative electrode active material silicon, conductive carbon black (Super P), and adhesive were mixed in a weight ratio of 90:5:5, and deionized water (H 2 O) was added as a solvent to prepare a slurry with a solid content of 0.7, and stirred evenly.
  • the slurry was evenly coated on the negative electrode current collector copper foil and dried at 110°C to obtain the negative electrode sheet. After coating, the sheet was cut into (1000mm ⁇ 60mm) specifications for standby use.
  • the single-sided coating of the negative electrode sheet is completed. Afterwards, these steps are also completed on the back of the sheet in a completely consistent manner to obtain a negative electrode sheet with double-sided coating.
  • the film thickness is 50 ⁇ m, and other parameters are shown in Tables 1 to 4.
  • EC ethylene carbonate
  • EMC ethyl methyl carbonate
  • DEC diethyl carbonate
  • the isolation membrane substrate is 8 ⁇ m thick polyethylene (PE), and a 2 ⁇ m alumina ceramic layer is coated on both sides of the isolation membrane substrate. Finally, 2.5 mg of binder polyvinylidene fluoride (PVDF) is coated on both sides of the ceramic layer and dried.
  • PE polyethylene
  • PVDF binder polyvinylidene fluoride
  • the positive electrode tab and the negative electrode tab are laser welded to weld the positive electrode Al transfer tab and the negative electrode Ni transfer tab respectively, and the positive and negative tabs are in the same direction.
  • the separator is placed between the positive electrode sheet and the negative electrode sheet and then wound into a wound electrode assembly.
  • the wound electrode assembly is packaged, injected with liquid, and then formed.
  • the positive electrode active material lithium cobalt oxide (LiCoO 2 ), conductive carbon black (Super P), and polyvinylidene fluoride (PVDF) were mixed at a weight ratio of 97.5:1.0:1.5, and N-methylpyrrolidone (NMP) was added as a solvent to prepare a slurry with a solid content of 0.75, and stirred evenly.
  • NMP N-methylpyrrolidone
  • the slurry was evenly coated on the positive electrode current collector aluminum foil and dried at 90°C to obtain a positive electrode sheet. After coating, the sheet was cut into a specification of (980mm ⁇ 58mm) for standby use.
  • the single-sided coating of the positive electrode sheet is completed. Afterwards, these steps are also completed on the back of the sheet in a completely consistent manner to obtain a double-sided coated positive electrode sheet.
  • the single-sided coating of the negative electrode sheet is completed. Afterwards, these steps are also completed on the back of the sheet in a completely consistent manner to obtain a negative electrode sheet with double-sided coating.
  • EC ethylene carbonate
  • EMC ethyl methyl carbonate
  • DEC diethyl carbonate
  • the isolation membrane substrate is 8 ⁇ m thick polyethylene (PE), and a 2 ⁇ m alumina ceramic layer is coated on both sides of the isolation membrane substrate. Finally, 2.5 mg of binder polyvinylidene fluoride (PVDF) is coated on both sides of the ceramic layer and dried.
  • PE polyethylene
  • PVDF binder polyvinylidene fluoride
  • the positive electrode tab and the negative electrode tab are laser welded to weld the positive electrode Al transfer tab and the negative electrode Ni transfer tab respectively, and the positive and negative tabs are in the same direction.
  • the separator is placed between the positive electrode sheet and the negative electrode sheet and then wound into a wound electrode assembly.
  • the wound electrode assembly is packaged, injected with liquid, and then formed.
  • the carbon nanotubes are deposited at a designated position on the surface of the copper foil using a mask, that is, the portion to be deposited is exposed to the environment, and the portion not to be deposited is shielded.
  • the copper foil is placed in a reaction chamber, and then a carbon source and a catalytic source are simultaneously injected into the reaction chamber, wherein the catalytic source is selected as ferrocene and the carbon source is selected as methane, and the injection direction is co-injected at 600°C and 5 ⁇ 10 4 Pa pressure, and the injection direction is about 90° with the copper foil plane to ensure that the carbon nanotubes grow vertically on the copper foil surface.
  • the positive electrode active material lithium cobalt oxide (LiCoO 2 ), conductive carbon black (Super P), and polyvinylidene fluoride (PVDF) were mixed at a weight ratio of 97.5:1.0:1.5, and N-methylpyrrolidone (NMP) was added as a solvent to prepare a slurry with a solid content of 0.75, and stirred evenly.
  • NMP N-methylpyrrolidone
  • the slurry was evenly coated on the positive electrode current collector aluminum foil and dried at 90°C to obtain a positive electrode sheet. After coating, the sheet was cut into a specification of (980mm ⁇ 58mm) for standby use.
  • the single-sided coating of the positive electrode sheet is completed. Afterwards, these steps are also completed on the back of the sheet in a completely consistent manner to obtain a double-sided coated positive electrode sheet.
  • the membrane thickness is 50 ⁇ m, and other parameters are shown in Tables 1 to 4.
  • the single-sided coating of the negative electrode sheet is completed. Afterwards, these steps are also completed on the back of the sheet in a completely consistent manner to obtain a negative electrode sheet with double-sided coating.
  • EC ethylene carbonate
  • EMC ethyl methyl carbonate
  • DEC diethyl carbonate
  • the isolation membrane substrate is 8 ⁇ m thick polyethylene (PE), and a 2 ⁇ m alumina ceramic layer is coated on both sides of the isolation membrane substrate. Finally, 2.5 mg of binder polyvinylidene fluoride (PVDF) is coated on both sides of the ceramic layer and dried.
  • PE polyethylene
  • PVDF binder polyvinylidene fluoride
  • the positive electrode tab and the negative electrode tab are respectively welded by laser welding, and the positive electrode Al transfer tab and the negative electrode Ni transfer tab are welded, and the positive and negative tabs are in the same direction.
  • the separator is placed between the positive electrode sheet and the negative electrode sheet and then wound to obtain a wound electrode assembly structure.
  • the wound electrode assembly is packaged, injected with liquid, and then formed.
  • the positive electrode active material lithium cobalt oxide (LiCoO 2 ), conductive carbon black (Super P), and polyvinylidene fluoride (PVDF) were mixed at a weight ratio of 97.5:1.0:1.5, and N-methylpyrrolidone (NMP) was added as a solvent to prepare a slurry with a solid content of 0.75, and stirred evenly.
  • NMP N-methylpyrrolidone
  • the slurry was evenly coated on the positive electrode current collector aluminum foil and dried at 90°C to obtain a positive electrode sheet. After coating, the sheet was cut into a specification of (980mm ⁇ 58mm) for standby use.
  • the single-sided coating of the positive electrode sheet is completed. Afterwards, these steps are also completed on the back of the sheet in a completely consistent manner to obtain a double-sided coated positive electrode sheet.
  • a carbon tube with an array structure is grown on the surface of the copper foil current collector by chemical vapor deposition, with a length of 2 ⁇ m, as a primer.
  • the surface of the carbon tube current collector is plasma treated, and then the graphite slurry is transferred to the current collector by extrusion coating, and then dried and rolled to complete the electrode preparation. After completion, the pole piece is cut into (1000mm ⁇ 60mm) specifications for use.
  • the thickness of the membrane is 50 ⁇ m, and other parameters are shown in Tables 1 to 4.
  • the single-sided coating of the negative electrode sheet is completed. Afterwards, these steps are also completed on the back of the sheet in a completely consistent manner to obtain a negative electrode sheet with double-sided coating.
  • EC ethylene carbonate
  • EMC ethyl methyl carbonate
  • DEC diethyl carbonate
  • the isolation membrane substrate is 8 ⁇ m thick polyethylene (PE), and a 2 ⁇ m alumina ceramic layer is coated on both sides of the isolation membrane substrate. Finally, 2.5 mg of binder polyvinylidene fluoride (PVDF) is coated on both sides of the ceramic layer and dried.
  • PE polyethylene
  • PVDF binder polyvinylidene fluoride
  • the positive electrode tab and the negative electrode tab are laser welded to weld the positive electrode Al transfer tab and the negative electrode Ni transfer tab respectively, and the positive and negative tabs are in the same direction.
  • the separator is placed between the positive electrode sheet and the negative electrode sheet and then wound into a wound electrode assembly structure.
  • the wound electrode assembly is packaged, injected with liquid, and then formed.
  • the positive electrode active material lithium cobalt oxide (LiCoO 2 ), conductive carbon black (Super P), and polyvinylidene fluoride (PVDF) were mixed at a weight ratio of 97.5:1.0:1.5, and N-methylpyrrolidone (NMP) was added as a solvent to prepare a slurry with a solid content of 0.75, and stirred evenly.
  • NMP N-methylpyrrolidone
  • the slurry was evenly coated on the positive electrode current collector aluminum foil and dried at 90°C to obtain a positive electrode sheet. After coating, the sheet was cut into a specification of (980mm ⁇ 58mm) for standby use.
  • the single-sided coating of the positive electrode sheet is completed. Afterwards, these steps are also completed on the back of the sheet in a completely consistent manner to obtain a double-sided coated positive electrode sheet.
  • the thickness of the membrane is 50 ⁇ m, and other parameters are shown in Tables 1 to 4.
  • the single-sided coating of the negative electrode sheet is completed. Afterwards, these steps are also completed on the back of the sheet in a completely consistent manner to obtain a negative electrode sheet with double-sided coating.
  • EC ethylene carbonate
  • EMC ethyl methyl carbonate
  • DEC diethyl carbonate
  • the isolation membrane substrate is 8 ⁇ m thick polyethylene (PE), and a 2 ⁇ m alumina ceramic layer is coated on both sides of the isolation membrane substrate. Finally, 2.5 mg of binder polyvinylidene fluoride (PVDF) is coated on both sides of the ceramic layer and dried.
  • PE polyethylene
  • PVDF binder polyvinylidene fluoride
  • the positive electrode tab and the negative electrode tab are laser welded to weld the positive electrode Al transfer tab and the negative electrode Ni transfer tab respectively, and the positive and negative tabs are in the same direction.
  • the separator is placed between the positive electrode sheet and the negative electrode sheet and then wound into a wound electrode assembly.
  • the wound electrode assembly is packaged, injected with liquid, and then formed.
  • Examples 2 to 26 include most of the operating steps in Example 1. The difference from Example 1 is that various parameters in the negative electrode sheet preparation process are regulated to vary within a certain range. For details, see Tables 1 to 4.
  • the electrochemical device was charged from 3.0 to 4.45V at a charge rate of 0.1C at 25°C, and then discharged to 3.0V at a discharge rate of 0.1C, and the above steps were repeated twice. Then, the device was charged from 3.0 to 4.45V at a charge rate of 0.2C, and then discharged to 3.0V at a discharge rate of 0.2C, and the discharge capacity at this time was recorded as Q1. The device was charged from 3.0 to 4.45V at a charge rate of 0.2C, and then discharged to 3.0V at a discharge rate of 2C, and the discharge capacity at this time was recorded as Q2.
  • the discharge capacity retention rate of 2C/0.2C Q2/Q1 ⁇ 100%.
  • the electrochemical device was charged from 3.0 to 4.45 V at a charging rate of 0.5 C at 25°C, and then discharged to 3.0 V at a discharge rate of 0.2 C.
  • the discharge capacity this time was determined as the first discharge capacity.
  • the above charge and discharge cycle was repeated 200 times, and the discharge capacity of the 200th discharge was measured.
  • the capacity retention rate after 200 cycles 200th discharge capacity/first discharge capacity ⁇ 100%.
  • the electrochemical device was left at 25°C for 30 minutes, and charged at a constant current of 0.05C to a voltage of 4.45V, and then discharged at a rate of 0.05C to 3.00V, and the above charge/discharge steps were repeated for 3 cycles to complete the formation of the electrochemical device to be tested.
  • the electrochemical device was placed at 25°C for 30 minutes, and then charged at a constant current of 0.05C to a voltage of 4.45V, and then discharged at a rate of 0.05C to 3.00V, and the above charge/discharge steps were repeated for 3 cycles to complete the formation of the electrochemical device to be tested.
  • Examples 1-8 show that the carbon nanotube array can improve the electronic conductivity and lithium ion transport performance, reduce polarization and capacity attenuation, thereby improving the rate performance, cycle performance and energy density of the battery.
  • the carbon tube has high mechanical strength, which can alleviate the volume expansion problem during the cycle.
  • Example 1-4 adjusts the thickness of the active material, and it is found that the technical solution described in the present application also has technical advantages in improving the performance of thick electrodes, and the thicker the electrode, the higher the energy density.
  • Examples 5-6 show that the length of the carbon nanotube array is allowed to be slightly higher than the thickness of the active material within a certain range, and it helps to improve the cycle stability and improve the capacity retention rate.
  • the reduction in the size of the carbon nanotube array in Examples 7-8 helps to improve the energy density, but at this time the corresponding pole piece polarization is slightly larger, resulting in a slight reduction in energy density, and the overall energy density is within an acceptable range.
  • the bottom-coated carbon tubes can increase the contact between the membrane and the current collector and reduce the resistance, but have basically no improvement effect on the charge transfer impedance and ion transmission resistance inside the electrode.
  • Examples 1-4 can greatly improve the electron transfer impedance and concentration polarization by interlacing vertical carbon nanotube array structures in the membrane area and coating active materials between different carbon nanotube arrays, thereby improving the battery electrical performance.
  • the rate performance and cycle performance of the battery are related to the ion and electron conductivity.
  • the role of the carbon nanotube array is to provide a fast electron/ion channel, accelerate the electron/ion transmission, and reduce the electronic resistance and concentration polarization. If the length h of the carbon nanotube array is too short, only the part containing the carbon nanotubes will improve the ion and electron conductivity, and the other parts will still have polarization phenomenon, so the rate and cycle improvement effect is limited.
  • the carbon nanotube part that is higher than the thickness H of the active material layer will be bent and supported on the top of the active material layer, thereby extending the distance from the active material to the diaphragm, thus affecting the rate performance, and the volume space occupied by too many carbon tubes will also affect the performance of the volume energy density.
  • the carbon tube is too short, the binding force on the particle expansion is weak. On the contrary, longer carbon tubes have the effect of alleviating expansion and also help improve the cycle stability.
  • Examples 8-10 compared to Comparative Example 1, the coverage area and mass percentage of the carbon nanotube array are adjusted.
  • the advantages of carbon tubes namely the high electrical conductivity of the carbon tubes themselves and the vertical ion transmission path inside the carbon tube array, can be fully utilized to shorten the transmission distance, reduce concentration polarization, improve kinetics, and improve rate performance.
  • carbon tubes themselves do not provide capacity, and carbon tubes will occupy a part of the volume. Therefore, at the same size, the proportion of active substances in the pole piece containing carbon tubes will be reduced, and the output capacity will be small, so the energy density will be reduced; it can be seen that too many carbon tubes will lead to energy density loss, so it is necessary to balance the relationship between electrical performance and energy density. If there are no carbon tubes, the electronic impedance will be reduced, ion transmission will be blocked, and polarization will increase, which will affect the capacity, deteriorate the voltage platform, and also lead to a decrease in energy density.
  • Examples 11-21 adjust the particle size of the active material, the spacing between adjacent carbon nanotube arrays, the long diameter of the carbon nanotube array, and the spacing between adjacent carbon nanotubes. It can be seen that with the increase in the size of the active material particles, the migration path of ions inside the particles increases, the rate performance deteriorates slightly, but the interface decreases, the side reaction decreases, so the cycle performance is improved, and the ionic impedance increases, which will lead to a decrease in capacity and energy density loss.
  • Examples 18-19, 20-21 respectively change the long diameter m of the carbon nanotube array and the distance d between adjacent carbon nanotubes, which can accelerate ion transmission by expanding the path, thereby reducing concentration polarization, but it is worth noting that the larger the m, the more energy density will be lost, and the larger the d, the more it will affect the expansion and binding ability of the particles.

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Abstract

一种电化学装置以及电子设备，电化学装置包括电极极片；电极极片包括集流体、位于集流体至少一侧的碳纳米管阵列以及活性物质；活性物质位于碳纳米管阵列之间。上述结构的碳纳米管阵列可以提供垂直的导电路径，改善厚电极中的电子传导路径长的问题，加速电子传导；而且，碳纳米管阵列中的相邻碳纳米管之间留白，有利于提供垂直、曲折度低的离子传输路径，极大缩短离子传输距离，降低电池充放电过程中的浓差极化现象，有利于提高离子电导率，能够改善电池的动力学性能。

Description

电化学装置以及电子设备 技术领域
本申请涉及电池技术领域，尤其涉及一种电化学装置以及电子设备。
背景技术
随着近年来电动汽车和可移动电子设备的高速发展，人们对电池的能量密度的需求越来越高，期待着高能量密度的电池的出现。
高能量密度电池可以通过化学体系的改变、电池结构设计或者系统结构设计来实现；其中，化学体系的改变，可采用高容量/高电压的正负极材料，如正极采用高镍三元、高压LNMO等，负极采用硅负极、锂金属等；电池结构设计，可通过提高极片压密、降低非活性物质占比、不同卷绕/叠片方式等实现；系统结构设计，包括降低系统内部非活性物质占比，优化串并联方式、model设计、优化BMS等方面。
上述的电池结构设计可以通过降低活性物质占比的方式提高能量密度，基于此思路，工业界采取厚电极的方案。通过将电极做厚，可以极大程度降低电池内部集流体的占比，在相同容量的情况下，电池可以做的更薄、更轻，从而提高电池的体积能量密度和质量密度；另外，非活性物质集流体的使用减少，可以起到降低电池成本的作用。同时，铜和/或铝集流体的减少，可以降低电池的整体碳排放量，与国家碳中和的发展目标相一致。但是，厚电极中由于活性物质涂膜厚度的增加导致电池的动力学性能变差。
发明内容
本申请实施例提供一种电化学装置以及电子设备，能够解决厚电极中由于活性物质涂抹厚度的增加导致电池动力学性能变差的问题，通过提升厚电极的动力学性能进而能够提高电池的倍率性能、循环性能以及能量密度。
第一方面，本申请实施例提供了一种电化学装置，包括电极极片；所述电极极片包括集流体、位于所述集流体至少一侧的碳纳米管阵列和活性物质层；所述活性物质层包括活性物质；所述碳纳米管阵列的数量至少为两个，所述活性物质位于至少两个所述碳纳米管阵列之 间；所述活性物质包括多个活性物质颗粒。
在其中一些实施例中，所述活性物质层的厚度为H，所述碳纳米管阵列的长度为h，满足：0.7h≤H≤1.3h，且40μm≤H≤500μm；其中，所述碳纳米管阵列的长度方向与所述集流体的表面垂直，所述活性物质层的厚度方向与所述碳纳米管阵列的长度方向平行。
多个所述活性物质颗粒之一(活性物质颗粒一)与所述集流体接触，所述活性物质颗粒一与所述集流体的接触位置视为起始端，在所述碳纳米管阵列的长度方向，另一所述活性物质颗粒(活性物质颗粒二)背离所述集流体的位置最远，所述活性物质颗粒二上背离所述集流体最远端处且与所述起始端相对应的位置视为末尾端，所述起始端与所述末尾端之间的距离即为所述活性物质层的厚度H。
在所述碳纳米管阵列的长度方向，所述碳纳米管阵列底端端部围成的面为第一面，所述碳纳米管阵列顶端端部围成的面为第二面，所述第一面与所述第二面之间的间距即为本申请所述的碳纳米管阵列的长度h。
所述碳纳米管阵列的长度方向是指所述碳纳米管阵列的底端朝向所述碳纳米管阵列的顶端的延伸方向，所述活性物质层的厚度方向是指所述起始端朝向所述末尾端的延伸方向；进一步地，所述碳纳米管阵列的长度方向与所述集流体的表面垂直，所述活性物质层的厚度方向与所述碳纳米管阵列的长度方向平行。
需要说明的是，在本申请中，所述碳纳米管阵列长度方向上的延长线与所述集流体表面的夹角在60°至90°的范围内，都可以视为本申请所述的表面垂直；以及，所述活性物质厚度方向上的延长线与所述碳纳米管阵列长度方向上的延长线，两个延长线相交形成的夹角在0°至30°的范围内，都可以视为本申请所述的平行。
在其中一些实施例中，所述电化学装置满足：0.9h≤H≤1.1h，且40μm≤H≤200μm。
在其中一些实施例中，所述电化学装置满足：
(I)所述碳纳米管底部与所述集流体接触围成的面积为S 1，所述活性物质覆盖在所述集流体上的面积为S 2，S 1和S 2的比值为S 1/S 2，S 1/S 2的范围为2:98至20:80；
(II)所述碳纳米管阵列的质量与膜片的质量的比值为M，满足：1％≤M≤15％；
(III)所述活性物质的质量与膜片的质量的比值为M′，满足：84％≤M′≤98.5％。
需要说明的是，所述碳纳米管阵列的质量是指所述集流体上含有的碳纳米管阵列的总质量，所述的膜片的质量是指不含集流体的电极极片的总质量；所述膜片的厚度是指集流体单侧的膜片的厚度。
在其中一些实施例中，所述电化学装置满足以下条件中的至少一者：
(i)所述碳纳米管底部与所述集流体接触围成的面积为S 1，所述活性物质覆盖在所述集流体上的面积为S 2，S 1和S 2的比值为S 1/S 2，S 1/S 2的范围为5:95～15:85；
(ii)所述碳纳米管阵列的质量与膜片的质量的比值为M，满足：2％≤M≤10％；
(iii)所述活性物质的质量与膜片的质量的比值为M′，满足：89％≤M′≤97％。
在其中一些实施例中，所述电化学装置满足：
(A)所述活性物质的平均粒径为D，满足：5μm≤D≤30μm；
(B)相邻所述碳纳米管阵列之间的间距为d(gap)，满足：2D≤d(gap)≤20D；
(C)所述碳纳米管阵列的长径为m，满足：m≤d(gap)/2；
(D)同一阵列内相邻碳纳米管之间的距离为d，满足：d＜D，且10nm≤d≤500nm；
相邻所述碳纳米管阵列可以是在所述集流体的长度方向上相邻，也可以是在所述集流体的宽度方向上相邻；例如，在所述集流体的长度方向，相邻所述碳纳米管阵列之间的间距d(gap)是指横向的两个碳纳米管阵列之间的间距；在所述集流体的宽度方向，相邻所述碳纳米管阵列之间的间距d(gap)是指纵向的两个碳纳米管阵列之间的间距；类似地，同一阵列内，相邻的碳纳米管可以是在所述集流体的长度方向上相邻，也可以是在所述集流体的宽度方向上相邻。以及，在所述集流体的长度方向，一个所述碳纳米管阵列的一端端部的一个碳纳米管和另一端端部的与之对应的另一个碳纳米管之间的间距即为本申请所述的碳纳米管阵列的长径m。
在其中一些实施例中，所述电化学装置满足以下条件的至少一者：
(a)所述活性物质的平均粒径为D，满足：5μm≤D≤15μm；
(b)相邻所述碳纳米管阵列之间的距离为d(gap)，满足：2D≤d(gap)≤10D。
在其中一些实施例中，所述碳纳米管阵列中碳纳米管的管径为5nm至500nm。
在其中一些实施例中，所述碳纳米管阵列中的碳纳米管包括单壁碳纳米管或多壁碳纳米 管中的至少一种；
优选地，所述碳纳米管为多壁碳纳米管，所述多壁碳纳米管的管径为50nm至500nm。
在其中一些实施例中，所述碳纳米管为多壁碳纳米管，所述多壁碳纳米管的管径为100nm至200nm。
第二方面，本申请实施例提供了一种电子设备，包括上述任一项所述的电化学装置。
本申请的技术方案带来的有益效果至少包括：
(1)本申请通过在集流体上分布对齐设置多个碳纳米管阵列，且不同的碳纳米管阵列之间填充活性物质，上述结构的碳纳米管阵列可以提供垂直的导电路径，改善厚电极中的电子传导路径长的问题，加速电子传导；
(2)同一碳纳米管阵列中的相邻碳纳米管之间留白，利于提供垂直、曲折度低的离子传输路径，极大缩短离子传输距离，降低电池充放电过程中的浓差极化现象，利于提高离子电导率；
(3)上述结构中的碳纳米管具有高机械强度，可以缓解电极充放电过程中的体积膨胀问题，避免活性物质脱落，电性能恶化；以及，碳纳米管具有高导热性能，可以降低充放电温升，提高电池的热稳定性；
(4)同一阵列内相邻碳纳米管之间的留白处理可以加速制造过程中的电解液浸润，提高极片的整体孔隙率，利于改善离子在电解液中的传输效率。
附图说明
为了更清楚地说明本申请实施例或现有技术中的技术方案，下面将对实施例或现有技术描述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，对于本领域技术人员来讲，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为本申请实施例中电极极片的截面结构示意图；
图2为本申请实施例中电极极片的俯视结构示意图；
图3为本申请实施例中集流体上填充活性物质的截面示意图；
图4为本申请实施例中未填充活性物质的分布式碳纳米管阵列的俯视结构示意图。
具体实施方式
为了使本申请的目的、技术方案及优点更加清楚明白，以下结合附图及实施例，对本申请进行进一步详细说明。应当理解，此处所描述的具体实施例仅仅用以解释本申请，并不用于限定本申请。
在现有锂离子电池体系中，锂离子基于摇椅式工作原理进行充放电。即在电池充电过程中，阴极活性物质失去电子，锂离子从阴极材料的晶格中脱出，通过电解液、穿过隔膜迁移至电池的负极，锂离子嵌入负极，此时，电子通过外电路也到达负极侧，负极得到的电子与嵌入的锂离子结合形成锂碳层间化合物。放电时，发生相反的过程。由上述过程可见，锂离子在充放电过程中，靠近集流体侧的锂离子需要通过较长路径才能完成迁移，远离集流体的电子同样需要通过较长的传导路径。这种现象在厚电极中尤为突出，由于电极中活性物质涂膜厚度的增加，导致迁移路径更长，因此在厚电极中伴随着倍率性能变差，甚至存在析锂的问题。
为改善厚电极的动力学问题，通常通过电子和离子导电性两个方面进行优化。电子导电性方面通常采用的方案是增加导电剂的使用量，导电剂由0维乙炔黑变为一维碳纳米管或二维石墨烯导电剂，相比于零维导电剂，一维和二维导电剂在电极整体导电性提升方面有帮助，但由于导电剂在电极中呈现散乱分布，因此不能很好的定向提高电极垂直方向的导电性，因为改善效果有限。离子电导率方面通常采用的方案是提高极片的整体孔隙率或制造间隙结构。提高极片孔隙率可以增大电解液保有量，一定程度上改善锂离子在电解液传输情况，但由于锂离子传输路径依旧是曲折的，因此改善幅度有限。通过制造间隙结构的方式是改善厚电极动力学的关键手段之一。通过制造间隙结构，可以优化锂离子传输路径，减少曲折度，极大提高锂离子电池的传输能力。但常用制造间隙结构的手段有3D打印技术，冷冻干燥技术，这是技术的生产速率慢，工业化较远。相似的技术问题同样存在于钠离子电池中。
为了解决上述技术问题，本申请提出一种电化学装置以及电子设备。
一种电化学装置
所述电化学装置包括电极极片；所述电极极片包括集流体、位于所述集流体至少一侧的碳纳米管阵列以及活性物质；所述碳纳米管阵列的数量至少为两个，所述活性物质位于两个所述碳纳米管阵列之间；所述活性物质包括多个活性物质颗粒。
参阅图1和图2，本申请通过在集流体上设置多个碳纳米管阵列，多个所述碳纳米管阵列平均分布对齐，所述的对齐包括横向对齐和纵向对齐，不同的碳纳米管阵列之间填充活性物质，而非将活性物质填充在碳纳米管阵列的内部，通过在不同的碳纳米管阵列之间的间隙填充活性物质，阵列中的碳纳米管之间留白(留白即不进行填充)，上述结构中的碳纳米管阵列可以提供垂直的导电路径，定向提高电极垂直方向的导电性，利于改善电子传导路径长的问题，能够实现加速电子传导以及提高电子电导率；上述结构的单个碳纳米管阵列中碳纳米管之间的留白间隙，可以提供垂直、曲折度低的离子传输路径，极大缩短离子传输距离，降低电池充放电过程中的浓差极化现象，利于提高离子电导率。
参阅图3，图中标注的H处的长度即为本申请中所述活性物质层的厚度，图中标注的h处的长度即为本申请中所述碳纳米管阵列的长度。
在一些实施例中，所述活性物质层的厚度为H，所述碳纳米管阵列的长度为h，满足：0.7h≤H≤1.3h，且40μm≤H≤500μm；其中，所述碳纳米管阵列的长度方向与所述集流体的表面垂直，所述活性物质层的厚度方向与所述碳纳米管阵列的长度方向平行。
示例性地，所述活性物质层的厚度H为40μm、80μm、100μm、200μm、300μm、500μm或上述任意两个值组成的范围。
示例性地，所述活性物质层的厚度为H与所述碳纳米管阵列的长度h的比值H/h为0.7、0.8、1.0、1.2、1.3或上述任意两个值组成的范围。
优选地，所述活性物质层的厚度H为40μm、60μm、80μm、100μm、120μm、140μm、160μm、180μm、200μm或上述任意两个值组成的范围。
优选地，所述活性物质层的厚度为H与所述碳纳米管阵列的长度h的比值H/h为0.9、0.95、1.0、1.05、1.1或上述任意两个值组成的范围。
在一些实施例中，所述电化学装置满足：
(I)所述碳纳米管底部与所述集流体接触围成的面积为S 1，所述活性物质覆盖在所述 集流体上的面积为S 2，S 1和S 2的比值为2:98至20:80；
(II)所述碳纳米管阵列的质量与膜片的质量的比值为M，满足：1％≤M≤15％；
(III)所述活性物质的质量与膜片的质量的比值为M′，满足：84％≤M′≤98.5％。
示例性地，所述碳纳米管底部与所述集流体接触围成的面积为S 1，所述活性物质覆盖在所述集流体上的面积为S 2，S 1和S 2的比值为2:98、4:96、8:92、10:90、15:85、20:80或上述任意两个值组成的范围。
示例性地，所述碳纳米管阵列的质量与膜片的质量的比值M为1％、5％、8％、10％、13％、15％或上述任意两个值组成的范围。
示例性地，所述活性物质的质量与膜片的质量的比值M′为84％、86％、88％、90％、92％、94％、96％、98％、98.5％或上述任意两个值组成的范围。
优选地，所述电化学装置满足以下条件中的至少一者：
(i)所述碳纳米管底部与所述集流体接触围成的面积为S 1，所述活性物质覆盖在所述集流体上的面积为S 2，S 1和S 2的比值为5:95～15:85；
(ii)所述碳纳米管阵列的质量与膜片的质量的比值为M，满足：2％≤M≤10％；
(iii)所述活性物质的质量与膜片的质量的比值为M′，满足：89％≤M′≤97％。
示例性地，所述碳纳米管底部与所述集流体接触围成的面积为S 1，所述活性物质覆盖在所述集流体上的面积为S 2，S 1和S 2的比值为5:95、7:93、9:91、11:89、13:87、15:85或上述任意两个值组成的范围。
示例性地，所述碳纳米管阵列的质量与膜片的质量的比值M为2％、4％、6％、8％、10％或上述任意两个值组成的范围。
示例性地，所述活性物质的质量与膜片的质量的比值M′为89％、91％、93％、95％、97％或上述任意两个值组成的范围。
参阅图4，图中标注d(gap)的长度即为本申请所述的在所述集流体长度方向上，相邻碳纳米管阵列之间的间距，图中标注的m的长度即为本申请所述的碳纳米管阵列的长径，图中标注的d的长度即为本申请中所述的同一阵列内相邻碳纳米管之间的距离。
在一些实施例中，所述电化学装置满足：
(A)所述活性物质的平均粒径为D，满足：5μm≤D≤30μm；
(B)相邻所述碳纳米管阵列之间的间距为d(gap)，满足：2D≤d(gap)≤20D；
(C)所述碳纳米管阵列的长径为m，满足：m≤d(gap)/2；
(D)同一阵列内相邻碳纳米管之间的距离为d，满足：d＜D，且10nm≤d≤500nm。
示例性地，所述活性物质的平均粒径D为5μm、8μm、10μm、15μm、30μm或上述任意两个值组成的范围。
示例性地，相邻所述碳纳米管阵列之间的间距d(gap)为2D、4D、8D、10D、15D、20D或上述任意两个值组成的范围。
示例性地，同一阵列内相邻碳纳米管之间的距离d为10nm、50nm、80nm、100nm、300nm、500nm或上述任意两个值组成的范围。
优选地，所述电化学装置满足以下条件的至少一者：
(a)所述活性物质的平均粒径为D，满足：5μm≤D≤15μm；
(b)相邻所述碳纳米管阵列之间的距离为d(gap)，满足：2D≤d(gap)≤10D。
示例性地，所述活性物质的平均粒径D为5μm、7μm、9μm、11μm、13μm、15μm或上述任意两个值组成的范围。
示例性地，相邻所述碳纳米管阵列之间的间距d(gap)为2D、4D、6D、8D、10D或上述任意两个值组成的范围。
在一些实施例中，所述碳纳米管阵列中的碳纳米管的管径为5nm至500nm。
示例性地，所述碳纳米管阵列中的碳纳米管的管径为5nm、20nm、80nm、120nm、150nm、200nm、400nm、500nm或上述任意两个值组成的范围。
在一些实施例中，所述碳纳米管阵列中的碳纳米管包括单壁碳纳米管或多壁碳纳米管中的至少一种；
可选地，在一个示例中，所述碳纳米管阵列中的碳纳米管包括多壁碳纳米管；在另一个示例中，所述碳纳米管阵列中的碳纳米管包括多壁碳纳米管和单壁碳纳米管；或者在其他示例中，所述碳纳米管阵列中的碳纳米管包括多壁碳纳米管和单壁碳纳米管。
优选地，所述碳纳米管为多壁碳纳米管，所述多壁碳纳米管的管径为50nm至500nm。
示例性地，所述多壁碳纳米管的管径为50nm、150nm、300nm、450nm、500nm或上述任意两个值组成的范围。
更优选地，所述碳纳米管为多壁碳纳米管，所述多壁碳纳米管的管径为100nm至200nm。
示例性地，所述多壁碳纳米管的管径为100nm、120nm、140nm、160nm、180nm、200nm或上述任意两个值组成的范围。
可选地，在一个示例中，所述碳纳米管阵列分布在所述集流体的一侧；或者，在另一个示例中，所述碳纳米管阵列分布在所述集流体的两侧。所述的分布通常指均匀分布，即所述碳纳米管阵列均匀分布在所述集流体的一侧或者两侧，根据实际情况具体选择，本申请对此并不做限制。
在一些实施例中，所述集流体的至少一个表面上设有底涂层，所述底涂层覆盖在所述集流体的表面，所述底涂层包括导电碳层或高粘接层中的至少一种。
可选地，在一个示例中，所述集流体的至少一个表面上设有导电碳层；或者在另一个示例中，所述集流体的至少一个表面上设有导电炭层，还设有高粘接层。
可选地，所述导电碳层和/或所述高粘接层与所述集流体之间的粘接力为F，且F≥3N/m；如果粘接力F＜3N，则活性物质层和集流体之间的界面粘接力不好，会恶化界面的电子阻抗，从而恶化电池性能，另外，还会有活性物质从集流体上脱落的风险。其中，所述活性物质层包括活性物质。
优选地，所述导电碳层和/或所述高粘接层与所述集流体之间的粘接力F的取值范围为：F≥5N/m。
在一些实施例中，上述的任意一种电化学装置可以为锂离子电池或钠离子电池。
本申请实施例还提供了一种电子设备，包括如上的任意一种电化学装置。本申请的电子设备置可用于，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、家庭用大型蓄电池和锂离子电容器等。
以下将结合具体实施例对本申请作进一步详细的说明。
所述的二维平面导电基底(即集流体)包括铝箔、铜箔、不锈钢箔、镍箔、铁箔、金箔、银箔、铂箔、钛箔、锌箔、锰箔、碳膜、其他复合金属箔片、导电聚合物薄膜或复合聚合物-金属薄膜。
正极活性材料包括：NCM811、NCM622、NCM523、NCM111、NCA、磷酸铁锂、钴酸锂、锰酸锂、磷酸锰铁锂或钛酸锂中的至少一种。
负极活性材料包括：石墨、纯硅、硬碳、硅碳或硅氧化物、锡、锡化物、锂金属等高膨胀负极材料中的至少一种，优选纯硅材料。
锂离子电池的电解液没有特别限制，可以使用本领域公知的任何电解液，所述可以是凝胶态、固态和液态中的任一种。例如，所述液态电解液包括锂盐和非水溶剂。
所述锂盐没有特别限制，可以使用本领域公知的任何锂盐，只要能实现本申请的目的即可。例如，锂盐可以包括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或LiPO 2F 2等中的至少一种。例如，锂盐可选用LiPF 6。
所述非水溶剂没有特别限定，只要能实现本申请的目的即可。例如，非水溶剂可以包括碳酸酯化合物、羧酸酯化合物、醚化合物、腈化合物或其它有机溶剂等中的至少一种。
例如，碳酸酯化合物可以包括碳酸二乙酯(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)、碳酸甲乙酯(MEC)、碳酸亚乙酯(EC)、碳酸亚丙酯(PC)、碳酸亚丁酯(BC)、碳酸乙烯基亚乙酯(VEC)、碳酸氟代亚乙酯(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等中的至少一种。
【对比例1】
无碳纳米管阵列的极片
正极极片的制备
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0.75的浆料，并搅拌均匀。将浆料均匀涂覆在正极集流体铝箔上，90℃条件下烘干，得到正极极片。涂布完成后，将极片裁切成(980mm×58mm)的规格待用。
以上步骤完成后，即已完成正极极片的单面涂布。之后，以完全一致的方法，在该极片背面也完成这些步骤，即得到双面涂布完成的正极极片。
负极极片的制备
将负极活性材料硅、导电炭黑(Super P)、粘接剂按照重量比90:5:5进行混合，加入去离子水(H 2O)作为溶剂，调配成为固含量为0.7的浆料，并搅拌均匀。将浆料均匀涂覆在负极集流体铜箔上，110℃条件下烘干，得到负极极片。涂布完成后，将极片裁切成(1000mm×60mm)的规格待用。
以上步骤完成后，即已完成负极极片的单面涂布。之后，以完全一致的方法，在该极片背面也完成这些步骤，即得到双面涂布完成的负极极片。膜片厚度为50μm，其他参数见表1～4。
电解液的制备
在干燥氩气气氛中，首先将有机溶剂碳酸乙烯酯(EC)、碳酸甲乙酯(EMC)和碳酸二乙酯(DEC)以质量比EC:EMC:DEC＝30:50:20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，得到锂盐的浓度为1.15M的电解液。
隔离膜的制备
隔离膜基材为8μm厚的聚乙烯(PE)，在隔离膜基材的两侧各涂覆2μm氧化铝陶瓷层，最后在涂布了陶瓷层的两侧各涂覆2.5mg的粘结剂聚偏二氟乙烯(PVDF)，烘干。
电极组件的制备
将正极极耳和负极极耳分别通过激光焊接的方式，焊接正极Al转接极耳，和负极Ni转接极耳，且正负极耳方向相同。将隔离膜置于正极极片和负极极片之间然后卷绕成卷绕式电极组件。
电池的制备
将卷绕完成的电极组件进行封装、注液，化成即可。
【对比例2】
正极极片的制备
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0.75的浆料，并搅拌均匀。将浆料均匀涂覆在正极集流体铝箔上，90℃条件下烘干，得到正极极片。涂布完成后，将极片裁切成(980mm×58mm)的规格待用。
以上步骤完成后，即已完成正极极片的单面涂布。之后，以完全一致的方法，在该极片背面也完成这些步骤，即得到双面涂布完成的正极极片。
负极极片的制备
在集流体表面通过化学气相沉积的方式，在铜箔集流体表面生长出具有阵列结构的碳管，对含有碳纳米管阵列的集流体的表面进行等离子体预处理，接着将石墨浆料通过挤压涂布方式转移到集流体上，进行干燥压延，从而完成电极制备。完成后，将极片裁切成(1000mm×60mm)的规格待用。其中，活性物质层的厚度H和碳纳米管阵列的长度h的比例为H＝3h；且膜片厚度为50μm，其他参数见表1～4。
以上步骤完成后，即已完成负极极片的单面涂布。之后，以完全一致的方法，在该极片背面也完成这些步骤，即得到双面涂布完成的负极极片。
电解液的制备
在干燥氩气气氛中，首先将有机溶剂碳酸乙烯酯(EC)、碳酸甲乙酯(EMC)和碳酸二乙酯(DEC)以质量比EC:EMC:DEC＝30:50:20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，得到锂盐的浓度为1.15M的电解液。
隔离膜的制备
隔离膜基材为8μm厚的聚乙烯(PE)，在隔离膜基材的两侧各涂覆2μm氧化铝陶瓷层，最后在涂布了陶瓷层的两侧各涂覆2.5mg的粘结剂聚偏二氟乙烯(PVDF)，烘干。
电极组件的制备
将正极极耳和负极极耳分别通过激光焊接的方式，焊接正极Al转接极耳，和负极Ni转接极耳，且正负极耳方向相同。将隔离膜置于正极极片和负极极片之间然后卷绕成卷绕式 电极组件。
电池的制备
将卷绕完成的电极组件进行封装、注液，化成即可。
铜箔集流体表面生长出碳纳米管阵列的具体方法：
使用掩模版的方法在所述铜箔表面指定位置沉积碳纳米管，即需要沉积的部分暴露在环境中，无需沉积的部分进行遮蔽。将上述铜箔放置在反应腔室内，然后将碳源和催化源同时注入反应腔室内，其中，催化源选择为二茂铁，碳源选择为甲烷，在600℃、5×10 4Pa压力下、注入方向与铜箔平面形成大约90°的方向共注入，以保证碳纳米管在铜箔表面垂直生长。
【对比例3】
正极极片的制备
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0.75的浆料，并搅拌均匀。将浆料均匀涂覆在正极集流体铝箔上，90℃条件下烘干，得到正极极片。涂布完成后，将极片裁切成(980mm×58mm)的规格待用。
以上步骤完成后，即已完成正极极片的单面涂布。之后，以完全一致的方法，在该极片背面也完成这些步骤，即得到双面涂布完成的正极极片。
负极极片的制备
在集流体表面通过化学气相沉积的方式，在铜箔集流体表面生长出具有阵列结构的碳管，对含有碳纳米管阵列的集流体的表面进行等离子体处理，接着将石墨浆料通过挤压涂布方式转移到集流体上，进行干燥压延，从而完成电极制备。完成后，将极片裁切成(1000mm×60mm)的规格待用。其中，活性物质层的厚度H和碳纳米管阵列的长度h的比例为H＝0.3×h；
且膜片厚度为50μm，其他参数见表1～4。
以上步骤完成后，即已完成负极极片的单面涂布。之后，以完全一致的方法，在该极片背面也完成这些步骤，即得到双面涂布完成的负极极片。
电解液的制备
在干燥氩气气氛中，首先将有机溶剂碳酸乙烯酯(EC)、碳酸甲乙酯(EMC)和碳酸二乙酯(DEC)以质量比EC:EMC:DEC＝30:50:20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，得到锂盐的浓度为1.15M的电解液。
隔离膜的制备
隔离膜基材为8μm厚的聚乙烯(PE)，在隔离膜基材的两侧各涂覆2μm氧化铝陶瓷层，最后在涂布了陶瓷层的两侧各涂覆2.5mg的粘结剂聚偏二氟乙烯(PVDF)，烘干。
电极组件的制备
将正极极耳和负极极耳分别通过激光焊接的方式，焊接正极Al转接极耳，和负极Ni转接极耳，且正负极耳方向相同。将隔离膜置于正极极片和负极极片之间然后卷绕得到卷绕式电极组件结构。
电池的制备
将卷绕完成的电极组件进行封装、注液，化成即可。
【对比例4】
正极极片的制备
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0.75的浆料，并搅拌均匀。将浆料均匀涂覆在正极集流体铝箔上，90℃条件下烘干，得到正极极片。涂布完成后，将极片裁切成(980mm×58mm)的规格待用。
以上步骤完成后，即已完成正极极片的单面涂布。之后，以完全一致的方法，在该极片背面也完成这些步骤，即得到双面涂布完成的正极极片。
负极极片的制备
在集流体表面通过化学气相沉积的方式，在铜箔集流体表面生长出具有阵列结构的碳管，长度为2μm，作为底涂层。碳管集流体表面进行等离子体处理，接着将石墨浆料通过挤压涂布方式转移到集流体上，进行干燥压延，从而完成电极制备。完成后，将极片裁切成(1000mm×60mm)的规格待用。
膜片厚度为50μm，其他参数见表1～4。
以上步骤完成后，即已完成负极极片的单面涂布。之后，以完全一致的方法，在该极片背面也完成这些步骤，即得到双面涂布完成的负极极片。
电解液的制备
在干燥氩气气氛中，首先将有机溶剂碳酸乙烯酯(EC)、碳酸甲乙酯(EMC)和碳酸二乙酯(DEC)以质量比EC:EMC:DEC＝30:50:20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，得到锂盐的浓度为1.15M的电解液。
隔离膜的制备
隔离膜基材为8μm厚的聚乙烯(PE)，在隔离膜基材的两侧各涂覆2μm氧化铝陶瓷层，最后在涂布了陶瓷层的两侧各涂覆2.5mg的粘结剂聚偏二氟乙烯(PVDF)，烘干。
电极组件的制备
将正极极耳和负极极耳分别通过激光焊接的方式，焊接正极Al转接极耳，和负极Ni转接极耳，且正负极耳方向相同。将隔离膜置于正极极片和负极极片之间然后卷绕成卷绕式电极组件结构。
电池的制备
将卷绕完成的电极组件进行封装、注液，化成即可。
【实施例1】
正极极片的制备
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0.75的浆料，并搅拌均匀。将浆料均匀涂覆在正极集流体铝箔上，90℃条件下烘干，得到正极极片。涂布完成后，将极片裁切成(980mm×58mm)的规格待用。
以上步骤完成后，即已完成正极极片的单面涂布。之后，以完全一致的方法，在该极片背面也完成这些步骤，即得到双面涂布完成的正极极片。
负极极片的制备
在集流体表面通过化学气相沉积的方式，在铜箔集流体表面生长出具有阵列结构的碳管，对含有碳纳米管阵列的集流体的表面进行等离子体处理，接着将石墨浆料通过挤压涂布 方式转移到集流体上，进行干燥压延，从而完成电极制备。完成后，将极片裁切成(1000mm×60mm)的规格待用。
膜片厚度为50μm，其他参数见表1～4。
以上步骤完成后，即已完成负极极片的单面涂布。之后，以完全一致的方法，在该极片背面也完成这些步骤，即得到双面涂布完成的负极极片。
电解液的制备
在干燥氩气气氛中，首先将有机溶剂碳酸乙烯酯(EC)、碳酸甲乙酯(EMC)和碳酸二乙酯(DEC)以质量比EC:EMC:DEC＝30:50:20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，得到锂盐的浓度为1.15M的电解液。
隔离膜的制备
隔离膜基材为8μm厚的聚乙烯(PE)，在隔离膜基材的两侧各涂覆2μm氧化铝陶瓷层，最后在涂布了陶瓷层的两侧各涂覆2.5mg的粘结剂聚偏二氟乙烯(PVDF)，烘干。
电极组件的制备
将正极极耳和负极极耳分别通过激光焊接的方式，焊接正极Al转接极耳，和负极Ni转接极耳，且正负极耳方向相同。将隔离膜置于正极极片和负极极片之间然后卷绕成卷绕式电极组件。
电池的制备
将卷绕完成的电极组件进行封装、注液，化成即可。
【实施例2】～【实施例26】
实施例2～26包括实施例1中大部分的操作步骤，与实施例1不同的是，调控负极极片制备过程中的各项参数的在一定范围内变化，具体参见表1～4。
电池性能测试
(1)倍率性能测试
将电化学装置在25℃环境下，以0.1C的充电速率从3.0充电至4.45V，再以0.1C的放电速率放电至3.0V，重复两次上述步骤。然后以0.2C的充电速率从3.0充电至4.45V，再以 0.2C的放电速率放电至3.0V，并记录此时的放电容量为Q1。以0.2C的充电速率从3.0充电至4.45V，再以2C的放电速率放电至3.0V，并记录此时的放电容量为Q2。则2C/0.2C的放电容量保持率＝Q2/Q1×100％。
(2)容量保持率测试
将电化学装置在25℃环境下，以0.5C的充电速率从3.0充电至4.45V，再以0.2C的放电速率放电至3.0V，确定此次的放电容量为首次放电容量，重复上述充放电循环200次，测定第200次放电的放电容量，200圈容量保持率＝第200次放电容量/首次放电容量×100％。
(3)电池膨胀率测试
将电化学装置在25℃下静置30分钟，以0.05C充电速率恒流充电至电压4.45V，随后再以0.05C倍率将电化学装置放电至3.00V，重复上述充/放电步骤3个循环以完成待测的电化学装置的化成，通过厚度测量仪测试电池主体的厚度为THK1。然后以1C的倍率对电池在3-4.45V的电压范围内进行充放电循环500圈，并测试此时电池厚度为THK2。则500圈循环后电池膨胀率＝(THK2-THK1)/THK1×100％。
(4)能量密度测试(VED)
将电化学装置在25℃下静置30分钟，以0.05C充电速率恒流充电至电压4.45V，随后再以0.05C倍率将电化学装置放电至3.00V，重复上述充/放电步骤3个循环以完成待测的电化学装置的化成。完成电化学装置的化成后，以0.1C充电速率恒流充电至电压至4.45V，随后以0.1C放电倍率将电化学装置放电至3.00V，记录其放电容量，随后计算其0.1C放电时的能量密度：能量密度(Wh/L)＝放电容量(Wh)/电化学装置体积尺寸(L)。
对比例1～4和实施例1～26的测试结果参见表1～4。
表1
Figure PCTCN2022122643-appb-000001
Figure PCTCN2022122643-appb-000002
实施例1-8与对比例1相比，可以看出，碳纳米管阵列可以提高电子传导率和锂离子传输性能，降低极化和容量衰减，从而提高电池的倍率性能和循环性能和能量密度，此外，碳管具有高机械强度，可以缓解循环过程中的体积膨胀问题。实施例1-4调整活性物质的厚度，发现本申请所述技术方案在厚电极性能改善方面同样具有技术优势，且电极越厚，能量密度越高。实施例5-6与实施例3对比，说明允许一定范围内碳纳米管阵列的长度略高于活性物质的厚度，且有助于改善循环稳定性，提高容量保持率。实施例7-8相比于对比例2，一定程度上碳纳米管阵列的尺寸降低有助于提高能量密度，但此时对应的极片极化略大，导致能量密度略有降低，整体的能量密度在可接受范围内。对比例4中底涂碳管可增加膜片与集流体的接触，降低电阻，但对于电极内部的电荷转移阻抗和离子传输电阻基本无改善作用，相比于对比例4，实施例1-4通过在膜片区内穿插垂直碳纳米管阵列结构以及在不同的碳纳米管阵列之间涂布活性物质，可以极大程度改善电子转移阻抗，改善浓差极化，从而提高电池电性能。
可见，电池的倍率性能以及循环性能与离子、电子电导率有关，碳纳米管阵列的作用是可以提供快速的电子/离子通道，加快电子/离子传输，降低电子电阻和浓差极化。如果碳纳米管阵列的长度h太短，则仅含碳纳米管的部位，离子电子电导有改善，其他部分仍存在极 化现象，因此倍率和循环改善效果有限。如果碳纳米管阵列的长度h太长，则比活性物质层厚度H高的碳纳米管部分会被压弯，支撑在活性物质层的顶部，从而会延长离子从活性物质到隔膜的距离，因此会影响倍率性能，而且过多的碳管占据的体积空间，也会影响体积能量密度的发挥。膨胀方面，碳管太短，对颗粒膨胀的束缚力弱，反之，较长碳管，具有缓解膨胀的作用，也有助于循环稳定性的改善。
表2
Figure PCTCN2022122643-appb-000003
实施例8-10，相比于对比例1，调整了碳纳米管阵列的覆盖面积和质量百分比，通过调整碳管含量占比，可以充分发挥碳管优势，即碳管自身的高电导率和碳管阵列内部的垂直离子传输路径，缩短传输距离，降低浓差极化，改善动力学，提高倍率性能。但是，碳管本身不提供容量，且碳管会占据一部分体积，因此，在相同尺寸下，含碳管的极片里，活性物质的占比会降低，则输出容量少，因此能量密度会降低；可见，碳管数量过多，会导致能量密度损失，所以需平衡电性能和能量密度之间的关系。如果没有碳管，会造成电子阻抗降低，离子传输受阻，极化增大，从而影响容量发挥，恶化电压平台，也会导致能量密度降低。
表3
Figure PCTCN2022122643-appb-000004
Figure PCTCN2022122643-appb-000005
实施例11-21通过调整活性物质的颗粒尺寸、相邻碳纳米管阵列的间距、碳纳米管阵列的长径以及相邻碳纳米管之间的间距。可以看出，随着活性物质颗粒尺寸的增加，离子在颗粒内部迁移路径增大，倍率性能略有恶化，但界面减少，副反应减少，因此循环性能提升，同时离子阻抗增大，会导致容量降低，能量密度损失。d(gap)/D增大，导致与碳纳米管接触的活性物质颗粒减少，电子传导略有增加，同时通过碳纳米管阵列传递的离子需要横向传递到活性物质颗粒，导致传递路径增长，因此循环和倍率略有降低，但相比对比例1，电性能和能量密度还是有很大提升，主要归功于碳管的导离子和电子的能力。实施例18-19，20-21分别改变碳纳米管阵列的长径m和相邻碳纳米管之间的距离d，可以通过扩大通路来加速离子传输，从而起到降低浓差极化作用，但值得注意的是，m越大，会造成能量密度损失，d越大，会影响对颗粒的膨胀束缚能力。
表4
Figure PCTCN2022122643-appb-000006
Figure PCTCN2022122643-appb-000007
实施例22-23通过调整碳管类型、碳管管径、膜片粘接力F，可见，多壁碳管对应较大的碳管管径，一定程度下，碳管越厚，影响动力学，增加阻抗，但抗膨胀能力强，粘接好。碳管管径小，对应抗膨胀能力弱化，但动力学性能好。需在满足动力学、循环性能和能量密度下探索较优配比。但实施例效果均极大程度上优于对比例。
以上所述仅为本申请的较佳实施例而已，并不用以限制本申请，凡在本申请的精神和原则之内所作的任何修改、等同替换和改进等，均应包含在本申请的保护范围之内。

Claims (10)

  1. 一种电化学装置，其特征在于，包括电极极片；
    所述电极极片包括集流体、至少两个碳纳米管阵列以及活性物质层，所述活性物质层包括活性物质；
    所述碳纳米管阵列位于所述集流体的至少一侧；
    所述活性物质位于所述碳纳米管阵列之间。
  2. 根据权利要求1所述的电化学装置，其特征在于，所述活性物质层的厚度为H，所述碳纳米管阵列的长度为h，满足：0.7h≤H≤1.3h，且40μm≤H≤500μm；
    其中，所述碳纳米管阵列的长度方向与所述集流体的表面垂直，所述活性物质层的厚度方向与所述碳纳米管阵列的长度方向平行。
  3. 根据权利要求2所述的电化学装置，其特征在于，满足：0.9h≤H≤1.1h，且40μm≤H≤200μm。
  4. 根据权利要求1所述的电化学装置，其特征在于，满足以下条件中的至少一者：
    (I)所述碳纳米管阵列底部与所述集流体接触围成的面积为S 1，所述活性物质覆盖在所述集流体上的面积为S 2，S 1和S 2的比值为2:98至20:80；
    (II)所述碳纳米管阵列的质量与膜片的质量的比值为M，满足：1％≤M≤15％；
    (III)所述活性物质的质量与膜片的质量的比值为M′，满足：84％≤M′≤98.5％。
  5. 根据权利要求4所述的电化学装置，其特征在于，满足以下条件中的至少一者：
    (i)所述碳纳米管底部与所述集流体接触围成的面积为S 1，所述活性物质覆盖在所述集流体上的面积为S 2，S 1和S 2的比值为5:95～15:85；
    (ii)所述碳纳米管阵列的质量与膜片的质量的比值为M，满足：2％≤M≤10％；
    (iii)所述活性物质的质量与膜片的质量的比值为M′，满足：89％≤M′≤97％。
  6. 根据权利要求1所述的电化学装置，其特征在于，满足：
    (A)所述活性物质的平均粒径为D，满足：5μm≤D≤30μm；
    (B)相邻所述碳纳米管阵列之间的间距为d(gap)，满足：2D≤d(gap)≤20D；
    (C)所述碳纳米管阵列的长径为m，满足：m≤d(gap)/2；
    (D)同一阵列内相邻碳纳米管之间的距离为d，满足：d＜D，且10nm≤d≤500nm。
  7. 根据权利要求6所述的电化学装置，其特征在于，满足以下条件的至少一者：
    (a)所述活性物质的平均粒径为D，满足：5μm≤D≤15μm；
    (b)相邻所述碳纳米管阵列之间的距离为d(gap)，满足：2D≤d(gap)≤10D。
  8. 根据权利要求1所述的电化学装置，其特征在于，所述碳纳米管阵列中的碳纳米管包括单壁碳纳米管或多壁碳纳米管中的至少一种；
    优选地，所述碳纳米管为多壁碳纳米管，其管径为50nm至500nm。
  9. 根据权利要求8所述的电化学装置，其特征在于，所述碳纳米管为多壁碳纳米管，其管径为100nm至200nm。
  10. 一种电子设备，包括权利要求1至9中任一项所述的电化学装置。
PCT/CN2022/122643 2022-09-29 2022-09-29 电化学装置以及电子设备 Ceased WO2024065404A1 (zh)

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