WO2024065396A1 - 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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WO2024065396A1
WO2024065396A1 PCT/CN2022/122593 CN2022122593W WO2024065396A1 WO 2024065396 A1 WO2024065396 A1 WO 2024065396A1 CN 2022122593 W CN2022122593 W CN 2022122593W WO 2024065396 A1 WO2024065396 A1 WO 2024065396A1
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carbon nanotube
silicon
negative electrode
current collector
nanotube array
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French (fr)
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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/CN2022/122593 priority Critical patent/WO2024065396A1/zh
Priority to CN202280049748.3A priority patent/CN117642882B/zh
Publication of WO2024065396A1 publication Critical patent/WO2024065396A1/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
    • H01M4/134—Electrodes based on metals, Si or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/70—Carriers or collectors characterised by shape or form
    • 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 technical field of lithium-ion batteries, and in particular to an electrochemical device and an electronic device.
  • Silicon-based negative electrode materials have a gram capacity of up to 1500 to 4200 mAh/g and are regarded as the most promising next-generation lithium-ion negative electrode materials for achieving high-energy-density lithium batteries.
  • the low electrical conductivity of silicon >108 ⁇ .cm
  • its excessive volume expansion during charging and discharging with a volume expansion of about 300%) have, to a certain extent, hindered its further application; in addition, during the initial charging process, the formation of SEI requires the consumption of lithium, which results in a low initial efficiency of silicon-based negative electrode materials.
  • Lithium strip lithium replenishment is the most common and low-cost lithium replenishment technology, but lithium strip lithium replenishment has the problems of low lithium replenishment efficiency and high lithium replenishment heat, that is, there are safety hazards; there are mainly the following means to improve the expansion of silicon-based materials and enhance the cycle performance and rate performance of silicon-based materials: designing porous silicon-based materials, reducing the size of silicon materials, using oxide/polymer coating, using plastic adhesives, etc.; Among them, designing porous silicon-based materials and reducing the size of silicon materials can improve the rate performance to a certain extent, but as the cycle proceeds, the occurrence of side reactions and the growth of uncontrollable SEI film further limit the cycle stability of silicon materials; the use of oxide and polymer coating can avoid the coating of electrolyte and electrode materials, but due to its poor conductivity (>105 ⁇ .cm), it will increase the electrochemical impedance, and the coating layer is easily destroyed during the lithium insertion and extraction
  • the present application provides an electrochemical device and an electronic device, which can improve the problems of low initial efficiency and low lithium replenishment efficiency of silicon-based materials, and can improve the problem of deterioration of cycle performance caused by volume expansion of silicon-based materials during circulation. It can also improve the problem of poor conductivity of silicon-based materials, improve electron transfer impedance, reduce polarization, and increase capacity. At the same time, it is beneficial to improve ion transport inside silicon-based electrodes and further improve rate performance.
  • the present application provides an electrochemical device, comprising a negative electrode plate; the negative electrode plate comprises a carbon nanotube array, and a first negative electrode active material is provided in the carbon nanotube array.
  • the negative electrode plate also includes a current collector; the carbon nanotube array is located on the current collector; the carbon nanotube array includes carbon nanotubes; the first negative electrode active material is located between the carbon nanotubes; further, the outer tube wall of the carbon nanotube is in contact with the first negative electrode active material.
  • the carbon nanotubes in the carbon nanotube array have high conductivity, and there are uniform gaps between the carbon nanotubes arranged in the array, which can ensure rapid and uniform infiltration of the electrolyte.
  • the high-concentration lithium ions can be quickly transferred to the inside of the negative electrode plate along the uniform gaps, accelerating the uniform and rapid conduction of ions during the electrochemical reaction, avoiding the phenomenon of local lithium ion concentration unevenness, and causing lithium precipitation problems;
  • the first negative electrode active material is loaded on the surface of the outer tube wall of the carbon nanotube with an array structure, which is beneficial to increase the contact area between the current collector and the negative electrode active material, reduce electronic resistance, and increase conductivity.
  • the first negative electrode active material is a silicon-containing material; the silicon-containing material includes at least one of a silicon-carbon material, a silicon-oxygen material or a pure silicon material.
  • a silicon content greater than 80% can be regarded as a pure silicon material. Attaching the silicon-containing material to the surface of the outer tube wall of the carbon nanotube helps the silicon particles (including silicon-carbon particles, silicon-oxygen particles or pure silicon particles) to fully contact the carbon nanotubes and ensure an effective electron path.
  • the silicon-containing material also includes lithium.
  • the lithium element is formed by depositing the lithium supplement material after it contacts with uniformly distributed carbon nanotubes; specifically, after the lithium supplement material contacts with uniformly distributed carbon nanotubes, it can be uniformly and quickly absorbed and deposited into the interior of the silicon-containing material.
  • uniformly distributed carbon nanotubes are arranged on one side of the current collector, and the surface of the carbon nanotubes is loaded with silicon-containing materials; when supplementing lithium, firstly, the lithium supplement material contacts with uniformly distributed carbon nanotubes, and the safety hazards caused by local overheating caused by uneven deposition can be avoided.
  • the lithium supplement material is uniformly absorbed and deposited into the interior of the silicon-containing material.
  • the lithium precipitation problem caused by uneven lithium supplement can be avoided.
  • the carbon nanotubes with an array structure can play a role of uniform heat conduction, which can well reduce the temperature rise of lithium supplement. It can be seen that after combining lithium supplementation with the carbon nanotube array structure containing the first negative electrode active material, the problems of low lithium supplementation efficiency, high heat generation, and safety hazards can be improved, thereby improving the first effect.
  • the mass ratio of lithium to silicon is 5% to 30%.
  • controlling the mass ratio of lithium to silicon within a suitable range can make up for the lithium loss caused by the formation of SEI film at the negative electrode, thereby improving the first efficiency and cycle performance;
  • by selecting a suitable amount of lithium supplement a balance can be achieved between lithium supplement cost, lithium supplement efficiency/temperature rise, and electrical performance, which is conducive to large-scale production.
  • At least part of the surface of the silicon-containing material is provided with a conductive material; the conductive material includes at least one of a carbon material, a metal material or other conductive materials.
  • An appropriate conductive material is introduced to coat the surface of the silicon-containing material to further improve the conductivity of the silicon-containing material.
  • the carbon nanotube array is patterned on the current collector; or, the carbon nanotube array is fully covered on the current collector.
  • the fully covered distribution means that at least one side of the current collector is completely provided with the carbon nanotube array; the patterned distribution means that at least one side of the current collector is at least partially provided with the carbon nanotube array.
  • the negative electrode plate includes two or more carbon nanotube arrays arranged at intervals, and the average distance between the carbon nanotube arrays is M, which satisfies: d ⁇ M ⁇ 500 ⁇ m, preferably d ⁇ M ⁇ 50 ⁇ m.
  • the negative electrode plate satisfies at least one of the following conditions:
  • the projected area S1 enclosed by the top surface of the carbon nanotube array refers to the area obtained by horizontally extending the surface enclosed by the top of the carbon nanotube array (i.e., the upper top surface) to a horizontal plane in a direction perpendicular to the plane where the current collector is located, namely the projected area S1 ;
  • the projected area S2 enclosed by the lower bottom surface refers to the area obtained by horizontally extending the surface enclosed by the bottom of the carbon nanotube array (i.e., the lower bottom surface) to the same horizontal plane in a direction perpendicular to the plane where the current collector is located, namely the projected area S2 .
  • a region where the carbon nanotube array is located is selected for EDS spectrum analysis, and the mass content of silicon in the selected region is w, which satisfies: 60% ⁇ w ⁇ 95%; and for any two selected regions, the difference in the mass content of silicon is ⁇ w, which satisfies: ⁇ w ⁇ 20%;
  • the longitudinal section refers to the one obtained by performing cross-section processing on the film layer arranged on one side of the current collector in a direction perpendicular to the surface of the current collector.
  • the processing method can be ion polishing to obtain the cross-section.
  • the film layer includes the carbon nanotube array; the area usually refers to the area containing at least one carbon nanotube; the two arbitrarily selected areas refer to the two areas containing at least one different carbon nanotube.
  • the projected area enclosed by the carbon nanotube array refers to the area obtained by horizontally extending the surface enclosed by the carbon nanotube array to a horizontal plane, which is the projected area enclosed by the carbon nanotube array; wherein, the surface formed by encirclement may refer to the surface formed at any position of the carbon nanotube array, and the carbon nanotube array is in contact with the current collector; the current collector area of the selected area refers to the area corresponding to the selected area on the current collector.
  • the negative electrode plate satisfies at least one of the following conditions:
  • the electrolyte infiltration can further improve the electrolyte infiltration, accelerate ion conduction, and reduce concentration polarization; on the other hand, it can further buffer the volume expansion and ensure the integrity of the electrode morphology, without wrinkles, active material shedding and other problems during the charging and discharging process.
  • the negative electrode plate satisfies: (A) the average particle size of the negative electrode active material is D, satisfying: 5nm ⁇ D ⁇ 2 ⁇ m; (B) the spacing between adjacent carbon nanotubes is d, satisfying: 20nm ⁇ d ⁇ 5 ⁇ m; (C) the diameter of the carbon nanotube is p, satisfying: 5nm ⁇ p ⁇ 100nm; (D) the length of the carbon nanotube is H, satisfying: 5 ⁇ m ⁇ H ⁇ 80 ⁇ m.
  • Adjacent carbon nanotubes 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 between adjacent carbon nanotubes refers to the spacing between two carbon nanotubes arranged transversely along the length direction of the current collector; in the width direction of the current collector, the spacing d between adjacent carbon nanotubes refers to the spacing between two carbon nanotubes arranged longitudinally along the width direction of the current collector, and the spacing between two carbon nanotubes generally refers to the average spacing between the two carbon nanotubes.
  • the length direction of the carbon nanotube is perpendicular to the surface of the current collector.
  • the length direction of the carbon nanotube refers to the extension direction from the bottom end of the carbon nanotube toward the top end of the carbon nanotube. It should be noted that the angle between the extension line of the carbon nanotube 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 described in this application.
  • the negative electrode plate satisfies at least one of the following conditions:
  • the average particle size of the negative electrode active material is D, satisfying: 5nm ⁇ D ⁇ 500nm;
  • the length of the carbon nanotube is H, which satisfies: 5 ⁇ m ⁇ H ⁇ 40 ⁇ m
  • the lithium replenishment performance of the silicon-containing material can be improved, thereby improving the initial efficiency; on the other hand, the cycle performance can be improved.
  • the ratio of the distance d between adjacent carbon nanotubes to the average particle size D of the negative electrode active material satisfies: 2 ⁇ d/D ⁇ 5.
  • the lithium supplementation performance of the silicon material can be improved, and the initial efficiency and cycle electrical performance can be improved.
  • the ratio of the distance d between adjacent carbon nanotubes to the diameter p of the carbon nanotubes satisfies: 1nm ⁇ d/p ⁇ 250nm, so as to further improve the lithium replenishment performance of silicon materials and enhance the initial efficiency and cycle electrical performance.
  • the present application provides an electronic device comprising any of the electrochemical devices described above.
  • the present application arranges a carbon nanotube array on the current collector, and the outer wall surface of the carbon nanotubes in the carbon nanotube array contacts the silicon-containing material, which is beneficial to increase the contact area between the current collector and the silicon-containing material, reduce the electronic resistance, increase the conductivity, and ensure an effective electronic path; and lithium elements are deposited inside the silicon-containing material to improve the first efficiency; the surface of the silicon-containing material is coated with an appropriate conductive material to improve the conductivity of the silicon-containing material;
  • the uniformly arranged carbon nanotube structure in the present application can, on the one hand, play a role in uniform heat conduction, which greatly reduces the temperature rise of lithium replenishment, and on the other hand, can ensure the rapid and uniform infiltration of the electrolyte; after the lithium ions on the positive electrode side pass through the diaphragm, the high-concentration lithium ions can be quickly transferred to the inside of the negative electrode along the uniform gap, accelerating the uniform and rapid conduction of ions during the electrochemical reaction, avoiding the phenomenon of uneven local lithium ion concentration, which leads to lithium precipitation problems, and thus improving the first efficiency, rate performance and cycle performance of the battery;
  • the silicon-containing material is bound between the carbon nanotube arrays, which have high mechanical strength, and can limit the deformation of the pole piece and even the battery caused by the volume expansion of the silicon-containing material during the cycle process, effectively preventing poor interface contact; it can also avoid problems such as the active material falling off the current collector, poor contact between active material particles, and SEI thickening caused by particle rupture, thereby ensuring effective electron and ion conduction during the cycle process, avoiding the aggravation of side reactions, and improving the cycle performance;
  • the carbon nanotubes in the carbon nanotube array of the present application can quickly dissipate the heat inside the battery, which helps to reduce the temperature rise and avoid the accumulation of heat inside the battery, thereby improving the safety performance of the battery.
  • FIG1 is a partial enlarged view of a fully covered carbon nanotube array in an embodiment of the present application.
  • FIG2 is a partial enlarged view of a patterned carbon nanotube array in an embodiment of the present application.
  • FIG. 3 is a top view of a patterned carbon nanotube array in an embodiment of the present application.
  • Silicon-based negative electrode materials have a gram capacity of up to 1500 to 4200 mAh/g and are regarded as the most promising next-generation lithium-ion negative electrode materials for achieving high-energy-density lithium batteries.
  • the low electrical conductivity of silicon >108 ⁇ .cm
  • its excessive volume expansion during charging and discharging with a volume expansion of about 300%) have hindered its further application to a certain extent; in addition, during the initial charging process, the formation of SEI requires the consumption of lithium, which results in a low initial efficiency of the material.
  • the first effect of silicon-based materials is mainly improved by lithium replenishment technology.
  • Lithium strip lithium replenishment is the most common and low-cost lithium replenishment technology, but lithium strip lithium replenishment has the problems of low lithium replenishment efficiency and high heat generation, and there are safety hazards; there are mainly the following means to improve the expansion of silicon-based materials and enhance the cycle performance and rate performance of silicon-based materials: designing porous silicon-based materials, reducing the size of silicon materials, using oxide/polymer coating, using plastic adhesives, etc.; Among them, designing porous silicon-based materials and reducing the size of silicon materials can improve the rate performance to a certain extent, but as the cycle proceeds, the occurrence of side reactions and the growth of uncontrollable SEI film further limit the cycle stability of silicon materials; the use of oxide and polymer coating can avoid the coating of electrolyte and electrode materials, but due to its poor conductivity (>105 ⁇ .cm), it will increase the electrochemical impedance, and the coating layer is easily destroyed during the lithium insertion and extraction process, thereby reducing its cycle life; although the use of plastic adhesives can limit the problem of silicon volume
  • the present application proposes an electrochemical device and an electronic device.
  • the electrochemical device includes a negative electrode plate, which includes a current collector and a carbon nanotube array arranged on at least one side of the current collector, wherein a first negative electrode active material is arranged in the carbon nanotube array; the carbon nanotube array includes carbon nanotubes, the first negative electrode active material is located between the carbon nanotubes, and the outer tube wall of the carbon nanotube is in contact with the first negative electrode active material.
  • the present application provides a carbon nanotube array on one side of the current collector, and the carbon nanotube array has at least two arrangements, such as the fully covered carbon nanotube array shown in Figure 1, that is, at least one side of the current collector is covered with carbon nanotubes with an array structure; it can also be a patterned carbon nanotube array as shown in Figure 2 or 3, that is, at least one side of the current collector is provided with a plurality of carbon nanotube arrays, and the plurality of carbon nanotube arrays are patterned and arranged at a certain distance; further, the average distance between different carbon nanotube arrays is M (as shown in Figure 3), and M satisfies: d ⁇ M ⁇ 500 ⁇ m, preferably d ⁇ M ⁇ 50 ⁇ m, wherein d is the distance between adjacent carbon nanotubes.
  • the outer tube wall surface of the carbon nanotubes with an array arrangement structure is in contact with the first negative electrode active material, that is, the first negative electrode active material is in contact with the surface of the outer tube wall of the carbon nanotubes; by arranging carbon nanotubes with an array structure on the current collector, the carbon nanotubes have high conductivity, and there are uniform gaps between the carbon nanotubes in the array structure, which can ensure rapid and uniform infiltration of the electrolyte.
  • the high-concentration lithium ions can be quickly transferred to the inside of the negative electrode sheet along the uniform gap, accelerating the uniform and rapid conduction of ions in the electrochemical reaction process, avoiding the phenomenon of local lithium ion concentration unevenness, and causing lithium precipitation problems; at the same time, by loading the first negative electrode active material on the surface of the outer tube wall of the carbon nanotubes with an array structure, it is beneficial to increase the contact area between the current collector and the negative electrode active material, reduce electronic resistance, and increase conductivity.
  • the first negative electrode active material is a silicon-containing material; the silicon-containing material includes at least one of a silicon-carbon material, a silicon-oxygen material, or a pure silicon material.
  • the silicon-containing material is attached to the surface of the outer tube wall of the carbon nanotube, which helps the silicon particles (including silicon-carbon particles, silicon-oxygen particles, or pure silicon particles) in the silicon-containing material to fully contact the carbon nanotube to ensure an effective electron path.
  • the silicon-containing material also contains lithium elements; the lithium elements are deposited after the lithium supplement material contacts with uniformly distributed carbon nanotubes; specifically, after the lithium supplement material contacts with uniformly distributed carbon nanotubes, it can be uniformly and quickly absorbed and deposited into the interior of the silicon-containing material.
  • uniformly distributed carbon nanotubes are arranged on one side of the current collector, and the surface of the carbon nanotubes is loaded with silicon-containing materials; when supplementing lithium, firstly, the lithium supplement material contacts with uniformly distributed carbon nanotubes, and the safety hazards caused by local overheating caused by uneven deposition can be avoided at this time.
  • the lithium supplement material is uniformly absorbed and deposited into the interior of the silicon-containing material.
  • the lithium precipitation problem caused by uneven lithium supplement can be avoided.
  • the carbon nanotubes with an array structure can play a role of uniform heat conduction, which can well reduce the temperature rise of lithium supplement. It can be seen that after combining lithium supplementation with the carbon nanotube array structure containing the first negative electrode active material, the problems of low lithium supplementation efficiency, high heat generation, and safety hazards can be improved, thereby improving the first effect.
  • the mass ratio of lithium to silicon is 5% to 30%.
  • controlling the mass ratio of lithium to silicon within a suitable range can make up for the lithium loss caused by the formation of SEI film at the negative electrode, thereby improving the first efficiency and cycle performance;
  • by selecting a suitable amount of lithium supplementation a balance can be achieved between lithium supplementation cost, lithium supplementation efficiency/temperature rise, and electrical performance, which is conducive to large-scale production.
  • the mass ratio of the lithium element to the silicon element is 5%, 8%, 10%, 14%, 16%, 18%, 20%, 24%, 26%, 28%, 30% or a range consisting of any two of the above values.
  • the surface of the silicon-containing material is provided with a conductive material; the conductive material surrounds and covers or is doped on at least a portion of or even the entire surface of the silicon-containing material, and the conductive material includes at least one of a carbon material, a metal material, or other conductive materials. Appropriate conductive materials are introduced to cover the surface of the silicon-containing material to further improve the conductivity of the silicon-containing material.
  • the negative electrode plate satisfies at least one of the following conditions:
  • the projected area S1 enclosed by the top surface of the carbon nanotube array refers to the area obtained by horizontally extending the surface enclosed by the top of the carbon nanotube array (i.e., the upper top surface) to a horizontal plane in a direction perpendicular to the plane where the current collector is located, namely the projected area S1 ;
  • the projected area S2 enclosed by the lower bottom surface refers to the area obtained by horizontally extending the surface enclosed by the bottom of the carbon nanotube array (i.e., the lower bottom surface) to the same horizontal plane in a direction perpendicular to the plane where the current collector is located, namely the projected area S2 .
  • a region where the carbon nanotube array is located is selected for EDS spectrum analysis, and the mass content of silicon in the selected region is w, which satisfies: 60% ⁇ w ⁇ 95%; and for any two selected regions, the difference in the mass content of silicon is ⁇ w, which satisfies: ⁇ w ⁇ 20%;
  • the longitudinal section is obtained by performing section processing on the film layer arranged on one side of the current collector in a direction perpendicular to the surface of the current collector, and the processing method can be ion polishing to obtain the section;
  • the area usually refers to an area containing at least one carbon nanotube;
  • the two arbitrarily selected areas refer to the two areas containing at least one different carbon nanotube.
  • the projected area enclosed by the carbon nanotube array refers to the area obtained by horizontally extending the surface enclosed by the carbon nanotube array to a horizontal plane, which is the projected area enclosed by the carbon nanotube array; wherein, the surface formed by encirclement may refer to the surface formed at any position of the carbon nanotube array, and the carbon nanotube array is in contact with the current collector; the current collector area of the selected area refers to the area corresponding to the selected area on the current collector.
  • the ratio S1 / S2 of the projection area S1 enclosed by the top of the carbon nanotube array to the projection area S2 enclosed by the bottom thereof is 90%, 92%, 95%, 98%, 100%, 105%, 108%, 110% or a range consisting of any two of the above values.
  • the mass content w of silicon element in the selected region is 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or a range consisting of any two of the above values.
  • the difference ⁇ w between the mass contents of silicon elements in the plurality of regions is 0%, 1%, 5%, 8%, 10%, 15%, 20%, or a range consisting of any two of the above values.
  • the ratio S of the projected area enclosed by the carbon nanotube array to the current collector area of the selected region is 50%, 60%, 70%, 80%, 90%, 100% or a range consisting of any two of the above values.
  • the negative electrode plate satisfies at least one of the following conditions:
  • the electrolyte infiltration can be further improved, ion conduction can be accelerated, and concentration polarization can be reduced; on the other hand, the volume expansion can be further buffered to ensure the integrity of the electrode morphology, without wrinkles or active material shedding during the charging and discharging process.
  • the ratio S1 / S2 of the projection area S1 enclosed by the top of the carbon nanotube array to the projection area S2 enclosed by the bottom thereof is 95%, 97%, 98%, 100%, 102%, 104%, 105% or a range consisting of any two of the above values.
  • the mass content w of silicon element in the selected region is 80%, 83%, 85%, 88%, 90%, 93%, 95% or a range consisting of any two of the above values.
  • the difference ⁇ w between the mass contents of silicon elements in the plurality of regions is 0%, 1%, 3%, 5%, 7%, 9%, 10% or a range consisting of any two of the above values.
  • the ratio S of the projected area enclosed by the carbon nanotube array to the current collector area of the selected region is 70%, 75%, 80%, 85%, 90%, 95%, 100% or a range consisting of any two of the above values.
  • the negative electrode plate satisfies: (A) the average particle size of the negative electrode active material is D, satisfying: 5nm ⁇ D ⁇ 2 ⁇ m; (B) the spacing between adjacent carbon nanotubes is d, satisfying: 20nm ⁇ d ⁇ 5 ⁇ m; (C) the diameter of the carbon nanotube is p, satisfying: 5nm ⁇ p ⁇ 100nm; (D) the length of the carbon nanotube is H, satisfying: 5 ⁇ m ⁇ H ⁇ 80 ⁇ m.
  • Adjacent carbon nanotubes 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 between adjacent carbon nanotubes refers to the spacing between two carbon nanotubes arranged transversely along the length direction of the current collector (as shown in FIG. 3 ); in the width direction of the current collector, the spacing d between adjacent carbon nanotubes refers to the spacing between two carbon nanotubes arranged longitudinally along the width direction of the current collector, and the spacing between two carbon nanotubes generally refers to the spacing between corresponding positions at the middle positions of the two carbon nanotubes.
  • the length H of the carbon nanotube refers to the distance between the bottom end of the carbon nanotube and the top end thereof (as shown in FIG. 1 ).
  • the length direction of the carbon nanotube is perpendicular to the surface of the current collector.
  • the length direction of the carbon nanotube refers to the extension direction from the bottom end of the carbon nanotube toward the top end of the carbon nanotube. It should be noted that the angle between the extension line of the carbon nanotube 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 described in this application.
  • the average particle size D of the negative electrode active material is 5 nm, 50 nm, 100 nm, 500 nm, 1000 nm, 1500 nm, 2000 nm, or a range consisting of any two of the foregoing values.
  • the spacing d between adjacent carbon nanotubes is 20 nm, 40 nm, 60 nm, 80 nm, 100 nm, 400 nm, 600 nm, 800 nm, 1000 nm, 1500 nm, 2000 nm, 2500 nm, 3000 nm, 3500 nm, 4000 nm, 4500 nm, 5000 nm, or a range consisting of any two of the foregoing values.
  • the diameter p of the carbon nanotube is 5 nm, 10 nm, 15 nm, 20 nm, 35 nm, 50 nm, 70 nm, 85 nm, 90 nm, 100 nm, or a range consisting of any two of the above values.
  • the length H of the carbon nanotube is 5 ⁇ m, 10 ⁇ m, 15 ⁇ m, 20 ⁇ m, 25 ⁇ m, 30 ⁇ m, 35 ⁇ m, 40 ⁇ m, 45 ⁇ m, 50 ⁇ m, 60 ⁇ m, 80 ⁇ m or a range consisting of any two of the above values.
  • the negative electrode plate satisfies at least one of the following conditions:
  • the average particle size of the negative electrode active material is D, satisfying: 5nm ⁇ D ⁇ 500nm;
  • the length of the carbon nanotube is H, which satisfies: 5 ⁇ m ⁇ H ⁇ 40 ⁇ m
  • the lithium replenishment performance of the silicon-containing material can be improved, thereby improving the initial efficiency; on the other hand, the cycle performance can be improved.
  • the average particle size D of the negative electrode active material is 5 nm, 50 nm, 80 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, or a range consisting of any two of the foregoing values.
  • the spacing d between adjacent carbon nanotubes is 20 nm, 40 nm, 60 nm, 80 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm, or a range consisting of any two of the foregoing values.
  • the length H of the carbon nanotube is 5 ⁇ m, 10 ⁇ m, 15 ⁇ m, 20 ⁇ m, 25 ⁇ m, 30 ⁇ m, 35 ⁇ m, 40 ⁇ m, or a range consisting of any two of the above values.
  • the ratio d/D of the spacing d between adjacent carbon nanotubes to the average particle size D of the negative electrode active material is 2.1, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 9.9 or a range consisting of any two of the above values.
  • the ratio d/p of the spacing d between adjacent carbon nanotubes to the tube diameter p of the carbon nanotube is 0.2nm, 1nm, 5nm, 10nm, 20nm, 40nm, 80nm, 100nm, 160nm, 180nm, 200nm, 250nm, 300nm, 400nm, 500nm or a range consisting of any two of the above values.
  • the ratio of the spacing d between adjacent carbon nanotubes to the average particle size D of the negative electrode active material satisfies: 2 ⁇ d/D ⁇ 5. This is used to improve the lithium supplementation performance of silicon materials and enhance the initial efficiency and cycle electrical performance.
  • a ratio d/D of the spacing d between adjacent carbon nanotubes to the average particle size D of the negative electrode active material is 2, 2.5, 3, 3.5, 4, 4.5, 5 or a range consisting of any two of the above values.
  • the ratio of the spacing d between adjacent carbon nanotubes to the diameter p of the carbon nanotubes satisfies: 1nm ⁇ d/p ⁇ 250nm. This further improves the lithium replenishment performance of silicon materials and improves the initial efficiency and cycle electrical performance.
  • the ratio d/p of the spacing d between adjacent carbon nanotubes to the diameter p of the carbon nanotube is 1 nm, 5 nm, 10 nm, 30 nm, 60 nm, 80 nm, 100 nm, 150 nm, 200 nm, 250 nm or a range consisting of any two of the above values.
  • 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 film, iron film, gold film, silver film, platinum film, titanium film, zinc film, manganese film, carbon film, other composite metal films, 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, 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.
  • DEC diethyl carbonate
  • DMC dimethyl carbonate
  • DPC dipropyl carbonate
  • 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 negative electrode sheet is coated on one side. After that, these steps are also completed on the back side of the sheet in the same way to obtain a negative electrode sheet coated on both sides.
  • the film thickness is 10 ⁇ m.
  • the negative electrode sheet is supplemented with lithium using lithium tape. See Tables 1 to 3 for specific parameters.
  • 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, 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.
  • the wound electrode assembly can be packaged, injected with liquid, and 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 pole piece is cut into (1000mm ⁇ 60mm) specifications for standby use.
  • the thickness of the membrane is 10 ⁇ m, and the specific parameters are shown in Tables 1 to 3.
  • 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, 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.
  • the wound electrode assembly can be packaged, injected with liquid, and 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.
  • Carbon tubes with an array structure are grown on the surface of the current collector by chemical vapor deposition on the surface of the copper foil current collector, and then bombarded with inert atoms to form array-shaped conical carbon nanotube clusters. Then, the silicon-containing material is attached to the surface of the conical carbon nanotubes by vapor deposition, and then a layer of conductive material is wrapped on the outside of the silicon material by vapor deposition to complete the electrode preparation. After completion, the pole piece is cut into (1000mm ⁇ 60mm) specifications for standby use, and the above pole piece is replenished with lithium.
  • the membrane thickness is 10 ⁇ m, and the specific parameters are shown in Tables 1 to 3.
  • 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 battery can be packaged, injected with liquid and 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 structure.
  • the wound electrode assembly can be packaged, injected with liquid, and formed.
  • Examples 2 to 27 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 3.
  • Sample pretreatment - acid digestion Take an appropriate amount of sample into a digestion tank, add digestion reagent (3ml pure water + 3ml nitric acid + 5ml HF), shake the digestion tank, place the digestion tank in the acid removal instrument, heat and evaporate to an appropriate volume (180°C 120min), take out the digestion tank and rinse the edge with ultrapure water;
  • digestion reagent 3ml pure water + 3ml nitric acid + 5ml HF
  • Test 1 Preheating: turn on the voltage regulator, adjust the argon gas to 0.6MPa, turn on the instrument, and open the software; 2 Establish the method: use the calibration curve method to test, and select Li and silicon as the test elements; 3 Ignition; 4 Test: a) Use 1mg/L Mn single standard to align the torch and clean the injection system; b) Optical initialization, initialization value ⁇ 50step; c) Use the configured standard solution to draw the working curve in turn; d) Check whether the linearity of the curve is R2>0.999; e) Test the quality control sample to confirm the accuracy of the curve; f) Enter the sample information and test the sample; 5 Shut down; 6 Process the data; 7 Container cleaning.
  • the lithium strip Place the lithium strip on the surface of the electrode, press and let it stand for 12 hours. Use a temperature sensor to record the temperature change during the entire standing process.
  • the temperature rise of lithium supplementation maximum temperature - room temperature. Record the weight gain per unit area before and after 12 hours, which is the amount of lithium supplementation.
  • the lithium absorption rate lithium supplementation amount/time, unit mg/( cm2 ⁇ h).
  • the electrochemical device was charged from 3.0 to 4.45 V at a charging rate of 0.2 C at 25°C, and the capacity was recorded as the first charging capacity.
  • the device was then discharged to 3.0 V at a discharge rate of 0.2 C, and the capacity was recorded as the first discharge capacity.
  • the first effect (first discharge capacity/first charging capacity) ⁇ 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 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 battery After the battery is cycled 200 times according to the test method in (3), it is fully discharged, that is, discharged at 0.2C to 3.0V, and then the battery is disassembled and the electrode is removed.
  • Examples 1 to 7 can improve the utilization rate of lithium and thus improve the initial effect by combining lithium supplementation with a carbon nanotube array structure; and the carbon nanotube array structure can accelerate the absorption of lithium and increase the lithium absorption rate through the capillary force between carbon nanotubes. At the same time, due to the high thermal conductivity of carbon nanotubes, the heat generated during the lithium supplementation process can be quickly exported to the external environment, thereby greatly reducing the temperature rise of lithium supplementation. Compared with Comparative Example 2, Examples 1 to 7 can compensate for the lithium loss caused by the formation of SEI film at the negative electrode by lithium supplementation, thereby improving the initial effect and cycle performance.
  • Examples 1 to 4 achieve a balance between lithium supplementation cost, lithium supplementation efficiency/temperature rise, and electrical performance by optimizing different lithium supplementation amounts.
  • Example 5 can further reduce the lithium supplementation temperature rise and absorption rate by changing the lithium supplementation material, but the cost of lithium slurry is slightly higher.
  • Example 6 proves that, with respect to different negative electrode active materials, similar technical effects can be achieved by combining carbon nanotube arrays and lithium supplementation.
  • Example 7 demonstrates the feasibility of coating with different conductive layers. As can be seen from Table 1, it has similar technical effects, but the metal conductive layer has the risk of internal self-discharge caused by metal particles, resulting in a slight decrease in cycle performance.
  • Examples 8 to 17 have improved utilization of lithium supplementation and improved initial efficiency, which shows that the carbon nanotube array structure can increase the lithium absorption rate and reduce the temperature rise of lithium supplementation.
  • silicon and lithium alloying leads to volume expansion, thereby weakening the adhesion between the active material and the membrane; while carbon nanotubes have high mechanical strength, which can restrain the volume expansion of silicon during the expansion process, thereby improving the adhesion of the membrane after the cycle, avoiding the problem of powder loss, and ensuring a reliable electronic and ion conductive network structure, thereby ensuring better cycle performance.
  • Examples 8 to 17 have a uniformly distributed carbon nanotube structure, while Comparative Example 3 is a conical carbon nanotube cluster structure. Since the CNT appears in the form of a conical carbon cluster, silicon is attached to the periphery of the conical carbon cluster by physical deposition, which reduces the conductive effect of the carbon tube. The silicon deposited on the outermost side of the conical carbon cluster has a long conductive path and poor conductivity. In addition, the active loading amount of this method is lower than that of the embodiments of the present application, resulting in a low capacity per unit area. At the same time, since the carbon cluster is conical, the process of the electrolyte entering the carbon tube first goes through a narrow path.
  • the rapid transmission of the electrolyte per unit area makes it difficult for the active material particles near the lower end of the current collector to quickly obtain ions, affecting the dynamics.
  • the uniform carbon nanotube distribution (90% ⁇ S 1 /S 2 ⁇ 110%) of the present application is conducive to the uniform absorption of lithium supplement materials, as well as uniform heat generation and heat conduction functions, thereby greatly reducing the temperature rise of lithium supplementation.
  • silicon is coated between carbon tubes, compared with the gaps in the conical carbon nanotube cluster, each silicon can fully contact the carbon nanotube to ensure a conductive network.
  • silicon can be bound in small amounts/individually between carbon tubes, rather than a large amount of silicon being deposited in the conical carbon nanotube cluster array, which can alleviate volume expansion and improve the adhesion of the membrane.
  • Examples 8 to 10 S 1 /S 2 was adjusted to demonstrate the positive effect of uniformly arranging carbon tubes.
  • w was adjusted. Low w had better performance than high w, but ED was lower. It was necessary to balance electrical performance and ED, and the w value was preferred.
  • ⁇ w was adjusted, and the uniform deposition of silicon helped to improve the overall performance.
  • the distribution of carbon nanotubes was adjusted, that is, the distribution was distributed in a patterned structure, which helped to further improve the electrical performance and reduce the temperature rise, but there would be a certain degree of loss in ED.
  • Examples 18 to 27 are optimized by adjusting the particle size D of the negative electrode active material, the spacing d between adjacent carbon nanotubes, the diameter p of the carbon nanotubes, and the length H of the carbon nanotubes, thereby improving the lithium replenishment performance of the silicon-containing material, and improving the first efficiency and cycle electrical performance.
  • the uniform distribution of carbon nanotubes can further improve the cycle performance, especially improve the carbon nanotubes to restrain the silicon expansion, thereby improving the membrane adhesion.

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Abstract

一种电化学装置以及电子设备。电化学装置包括负极极片，负极极片包括碳纳米管阵列，碳纳米管阵列中设有第一负极活性材料；负极极片还包括集流体，碳纳米管阵列位于集流体上，第一负极活性材料位于碳纳米管之间，第一负极活性材料为含硅材料。通过将含硅材料和碳纳米管的表面相接触，提高了集流体与含硅材料的接触面积，减少电子电阻，保证有效的电子通路，且均匀排布的碳纳米管结构可以加快电化学反应过程中的离子传导速率，避免局部锂离子浓度不均匀导致的析锂问题，提高电池的首次放电效率、倍率和循环性能。

Description

电化学装置以及电子设备 技术领域
本申请涉及锂离子电池技术领域，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，人们对电池能量密度的需求越来越高，硅基负极材料具有高达1500～4200mAh/g的克容量，被视为实现高能量密度锂电池的最具有应用前景的下一代锂离子负极材料，但是硅的低电导性(>108Ω.cm)以及其在充放电过程中体积膨胀过大(具有约300％的体积膨胀)，在一定程度上阻碍了其进一步的应用；另外，在初始充电过程中，形成SEI需要消耗锂，且导致硅基负极材料的首效低。
目前，主要通过补锂技术改善硅基材料的首效，锂带补锂是最常见且低成本的补锂技术，但锂带补锂存在补锂效率低、补锂发热高的问题，即存在安全隐患；对于改善硅基材料膨胀、提升硅基材料循环性能和倍率性能主要有以下手段：设计多孔硅基材料、降低硅材料的尺寸、采用氧化物/聚合物包覆、采用塑性粘接剂等；其中，设计多孔硅基材料以及降低硅材料的尺寸在一定程度上可以改善倍率性能，但随着循环的进行，副反应的发生以及不可控的SEI膜的生长进一步限制了硅材料的循环稳定性；采用氧化物和聚合物的包覆可以避免电解液和电极材料的包覆，但由于其较差的导电性(>105Ω.cm)会增加电化学阻抗，且在脱嵌锂过程中包覆层易被破坏，从而降低了其循环寿命；采用塑性粘接剂虽然可以一定程度上限制硅体积膨胀的问题，但是亦存在膨胀过程中，部分粘接剂断裂，活性物质颗粒接触不良的问题，从而影响后续的循环性能。
发明内容
本申请提供一种电化学装置以及电子设备，能够改善硅基材料首效低以及补锂效率低的问题，以及能够改善硅基材料循环过程中体积膨胀导致的循环性能恶化的问题，还可以改善硅基材料导电性差的问题，改善电子转移阻抗，降低极化，提高容量，同时，利于提高硅基电极内部的离子传输，进一步提高倍率性能。
第一方面，本申请提供了一种电化学装置，包括负极极片；所述负极极片包括碳纳米管阵列，所述碳纳米管阵列中设有第一负极活性材料。
在其中一些实施例中，所述负极极片还包括集流体；所述碳纳米管阵列位于所述集流体上；所述碳纳米管阵列包括碳纳米管；所述第一负极活性材料位于所述碳纳米管之间；进一步地，所述碳纳米管的外管壁与所述第一负极活性材料相接触。
通过在所述集流体上设置碳纳米管阵列，所述碳纳米管阵列中的碳纳米管具有高的导电性，且阵列排布的碳纳米管之间具有均匀的间隙，可以保证电解液的快速且均匀浸润，正极侧锂离子穿过隔膜后，高浓度锂离子可以沿着均匀空隙快速传递到负极极片内部，加快电化学反应过程中的离子均匀快速传导，避免局部锂离子浓度不均匀现象，导致析锂问题；将所述第一负极活性材料负载在具有阵列结构的碳纳米管的外管壁的表面，利于提高集流体与负极活性物质的接触面积，减少电子电阻，增加导电性。
在其中一些实施例中，所述第一负极活性材料为含硅材料；所述含硅材料包括硅碳材料、硅氧材料或纯硅材料中的至少一种。在本专利中，硅含量为大于80％即可以视作纯硅材料。将所述含硅材料附着在所述碳纳米管的外管壁的表面，有助于硅颗粒(包括硅碳颗粒、硅氧颗粒或者纯硅颗粒)充分接触碳纳米管，保证有效的电子通路。
在其中一些实施例中，所述含硅材料中还包括锂元素。所述锂元素是通过补锂材料与均匀分布的碳纳米管接触后沉积形成的；具体地，所述补锂材料与均匀分布的碳纳米管接触后，其可以均匀且快速地被吸收并沉积到含硅材料的内部。在补锂过程中，通过在集流体的一侧设置均匀分布的碳纳米管，且所述碳纳米管的表面负载有含硅材料；补锂时，首先，补锂材料与均匀分布的碳纳米管接触，此时可以避免不均匀沉积导致的局部过热现象诱发的安全隐患，其次，补锂材料被均匀吸收并沉积到含硅材料的内部，此时，可以避免补锂不均匀引发的析锂问题，同时，具有阵列结构的碳纳米管可以起到均匀导热的作用，可以很好的降低补锂温升。可见，将补锂和含有第一负极活性材料的碳纳米管阵列结构结合后，可以改善补锂效率低、发热高、安全隐患问题，进而提高首效。
在其中一些实施例中，所述锂元素与硅元素的质量比为5％至30％。一方面，控制锂元素与硅元素的质量比在合适的范围，可以弥补负极形成SEI膜造成的锂损失，从而提高首效和循环性能；另一方面，通过选择合适的补锂量，可以实现补锂成本、补锂效率/温升、电性能之间的平衡，有助于规模化生产。
在其中一些实施例中，所述含硅材料的至少部分表面设置有导电材料；所述导电材料包括碳材料、金属材料或其他具有导电性的材料中的至少一种。在所述含硅材料的表面引入适当的导电材料进行包覆，用以进一步提高所述含硅材料的导电性。
在其中一些实施例中，所述碳纳米管阵列在所述集流体上图案化分布；或，所述碳纳米管阵列在所述集流体上全覆盖式分布。在本专利中，所述全覆盖式分布是指所述集流体的至少一侧表面全部设置所述碳纳米管阵列；所述图案化分布是指所述集流体的至少一侧表面至少部分设置所述碳纳米管阵列。
在其中一些实施例中，所述碳纳米管阵列在所述集流体上图案化分布时；
所述负极极片包括两个或两个以上间隔设置的碳纳米管阵列，所述碳纳米管阵列之间的平均距离为M，满足：d＜M≤500μm，优选d＜M≤50μm。
在其中一些实施例中，所述负极极片满足以下条件中的至少一者：
(I)沿垂直于集流体所在平面的方向观察，所述碳纳米管阵列上顶面围成的投影面积为S 1，其下底面围成的投影面积为S 2，满足：90％≤S 1/S 2≤110％；
所述碳纳米管阵列上顶面围成的投影面积S 1是指在垂直于所述集流体所在平面的方向上，将环绕所述碳纳米管阵列顶部围成的面(即上顶面)水平延伸至一水平面上得到的面积即为投影面积S 1；下底面围成的投影面积S 2是指在垂直于所述集流体所在平面的方向上，将环绕所述碳纳米管阵列底部围成的面(即下底面)水平延伸至同一水平面上得到的面积即为投影面积S 2。
(II)在垂直于集流体表面的纵截面上，选取任一碳纳米管阵列所在区域进行EDS能谱分析，所选区域内硅元素的质量含量为w，满足：60％≤w≤95％；且对于任意选取的两个区域内，硅元素的质量含量的差值为△w，满足：△w≤20％；
所述的纵截面是指通过将设于所述集流体一侧的膜层沿垂直于所述集流体表面的方向进行断面处理获得的，处理的方式可以为离子抛光获取断面，所述的膜层包括所述碳纳米管阵列；所述区域通常指至少含有一根碳纳米管的区域；所述任意选取的两个区域是指两个所述区域之间至少含有一根不同的碳纳米管。
(III)选取任一碳纳米管阵列所在区域，沿垂直于集流体所在平面的方向观察，所述碳纳米管阵列围成的投影面积与所选区域集流体投影面积的比值为S，满足：50％≤S≤100％。
所述碳纳米管阵列围成的投影面积是指将环绕所述碳纳米管阵列围成的面水平延伸至一水平面上获得的面积即为所述碳纳米管阵列围成的投影面积；其中，环绕形成的面可以是指环绕所述碳纳米管阵列任一位置处形成的面，所述碳纳米管阵列与所述集流体接触；所选区域集流体面积是指所选区域对应于集流体上的面积。
在其中一些实施例中，所述负极极片满足以下条件中的至少一者：
(i)沿垂直于集流体所在平面的方向观察，所述碳纳米管阵列上顶面围成的投影面积为S 1，其下底面围成的投影面积为S 2，满足：95％≤S 1/S 2≤105％；
(ii)在垂直于集流体表面的纵截面上，选取任一碳纳米管阵列所在区域进行EDS能谱分析，所选区域内硅元素的质量含量为w，满足：80％≤w≤95％；且对于任意选取的两个区域内，硅元素的质量含量的差值为△w，满足：△w≤10％；
(iii)选取任一碳纳米管阵列所在区域，沿垂直于集流体所在平面的方向观察，所述碳纳米管阵列围成的投影面积与所选区域集流体投影面积的比值为S，满足：70％≤S≤100％。
此时，一方面可以进一步提高电解液浸润，加快离子传导，减少浓差极化；另一方面可以进一步缓冲体积膨胀，保证极片形态的完整性，在充放电过程中无褶皱，活性物质脱落等问题。
在其中一些实施例中，所述负极极片满足：(A)所述负极活性材料的平均粒径为D，满足：5nm≤D≤2μm；(B)相邻所述碳纳米管之间的间距为d，满足：20nm≤d≤5μm；(C)所述碳纳米管的管径为p，满足：5nm≤p≤100nm；(D)所述碳纳米管的长度为H，满足：5μm≤H≤80μm。
相邻所述碳纳米管可以是在所述集流体的长度方向上的相邻，也可以是在所述集流体的宽度方向上的相邻；例如，在所述集流体的长度方向，相邻所述碳纳米管之间的间距d是指沿所述集流体的长度方向上，横向排布的两个碳纳米管之间的间距；在所述集流体的宽度方向，相邻所述碳纳米管之间的间距d是指沿所述集流体的宽度方向上，纵向排布的两个碳纳米管之间的间距，两个所述碳纳米管之间的间距通常指两个所述碳纳米管之间的平均间距。
所述碳纳米管的长度方向与所述集流体的表面垂直，所述碳纳米管的长度方向是指所述碳纳米管的底端朝向所述碳纳米管的顶端的延伸方向，需要说明的是，所述碳纳米管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。
在其中一些实施例中，所述负极极片满足以下条件中的至少一者：
(a)所述负极活性材料的平均粒径为D，满足：5nm≤D≤500nm；
(b)相邻所述碳纳米管之间的间距为d，满足：20nm≤d≤1μm；
(c)所述碳纳米管的长度为H，满足：5μm≤H≤40μm
(d)相邻所述碳纳米管之间的间距d与所述负极活性材料的平均粒径D的比值，满足：2＜d/D＜10；
(e)相邻所述碳纳米管之间的间距d与所述碳纳米管的管径p的比值，满足：0.2nm≤d/p≤500nm。
通过调节负极活性材料的平均粒径、相邻碳纳米管之间的间距以及碳管的长度和管径，一方面可以改善含硅材料的补锂性能，进而提高首效，另一方面，可以改善循环性能。
在其中一些实施例中，相邻所述碳纳米管之间的间距d与所述负极活性材料的平均粒径D的比值，满足：2≤d/D≤5。此时，可以改善硅材料的补锂性能，提高首效以及循环电性能。
在其中一些实施例中，相邻所述碳纳米管之间的间距d与所述碳纳米管的管径p的比值，满足：1nm≤d/p≤250nm。用以进一步改善硅材料的补锂性能，提高首效以及循环电性能。
第二方面，本申请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设置碳纳米管阵列，所述碳纳米管阵列中的碳纳米管的外管壁表面接触设置含硅材料，利于提高集流体与含硅材料的接触面积，减少电子电阻，增加导电性，保证有效的电子通路；且所述含硅材料的内部沉积有锂元素用以提高首效；所述含硅材料的表面引入适当的导电材料进行包覆，用以提高含硅材料的导电性；
(2)本申请中均匀排布的碳纳米管结构一方面可以起到均匀导热的作用，很好地降低补锂温升，另一方面可以保证电解液的快速且均匀浸润；正极侧锂离子穿过隔膜后，高浓度锂离子可以沿着均匀空隙快速传递到负极极片内部，加快电化学反应过程中的离子均匀快速传导，避免局部锂离子浓度不均匀现象，导致析锂问题，进而提高电池的首效、倍率性能以及循环性能；
(3)本申请中含硅材料被束缚在碳纳米管阵列之间，碳纳米管阵列具有高的机械强度，可以限制在循环过程含硅材料的体积膨胀导致的极片变形甚至电池变形，有效防止界面接触不良；还可以避免活性物质从集流体上脱落、活性物质颗粒间的接触不良以及颗粒破裂导致SEI增厚等问题，从而保证循环过程中有效的电子和离子传导，避免副反应加剧，利于改善循环性能；
(4)本申请中碳纳米管阵列中的碳纳米管可以将电池内部热量快速导出，利于降低温升，避免电池内部热量的累积，从而改善电池的安全性能。
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为本申请实施例中全覆盖式分布的碳纳米管阵列的局部放大图；
图2为本申请实施例中图案化排布的碳纳米管阵列的局部放大图；
图3为本申请实施例中图案化排布的碳纳米管阵列的俯视图。
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。
硅基负极材料具有高达1500～4200mAh/g的克容量，被视为实现高能量密度锂电池的最具有应用前景的下一代锂离子负极材料，但是硅的低电导性(>108Ω.cm)，以及其在充放电过程中体积膨胀过大(具有约300％的体积膨胀)一定程度上阻碍了其进一步的应用；另外，在初始充电过程中，形成SEI需要消耗锂，且导致该材料的首效低。目前，主要通过补锂技术改善硅基材料首效，锂带补锂是最常见且低成本的补锂技术，但锂带补锂存在补锂效率低，且补锂发热高的问题，且存在安全隐患；对于改善硅基材料膨胀、提升硅基材料循环性能和倍率性能主要有以下手段：设计多孔硅基材料、降低硅材料的尺寸、采用氧化物/聚合物包覆、采用塑性粘接剂等；其中，设计多孔硅基材料以及降低硅材料的尺寸一定程度上可以改善倍率性能，但随着循环的进行，副反应的发生以及不可控的SEI膜的生长进一步限制了硅材料的循环稳定性；采用氧化物和聚合物的包覆可以避免电解液和电极材料的包覆，但由于其较差的导电性(>105Ω.cm)会增加电化学阻抗，且在脱嵌锂过程中包覆层易被破坏，从而降低了其循环寿命；采用塑性粘接剂虽然可以一定程度上限制硅体积膨胀的问题，但是亦存在膨胀过程中，部分粘接剂断裂，活性物质颗粒接触不良的问题，从而影响后续的循环性能。
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负极极片，所述负极极片包括集流体和设于所述集流体至少一侧的碳纳米管阵列，所述碳纳米管阵列中设有第一负极活性材料；所述碳纳米管阵列包括碳纳米管，所述第一负极活性材料位于所述碳纳米管之间，所述碳纳米管的外管壁与所述第一负极活性材料相接触。
参阅图1和图2，本申请通过在所述集流体的一侧设置碳纳米管阵列，所述碳纳米管阵列至少有两种排布方式，例如图1所示的全覆盖式分布的碳纳米管阵列，即所述集流体的至少一侧铺满具有阵列结构的碳纳米管；还可以为例如图2或者图3所示的图案化排布的碳纳米管阵列，即所述集流体的至少一侧设置有多个碳纳米管阵列，且多个所述碳纳米管阵列之间呈一定间距图案化排布；进一步地，不同碳纳米管阵列之间的平均距离为M(如图3所示)，M满足：d＜M≤500μm，优选d＜M≤50μm，其中，d为相邻碳纳米管之间的间距。结合图1或者图2，可以明显地看出，上述具有阵列式排布结构的碳纳米管的外管壁表面接触设置所述第一负极活性材料，即所述第一负极活性材料与所述碳纳米管的外管壁的表面相接触；通过在所述集流体上设置具有阵列结构的碳纳米管，碳纳米管具有高的导电性，阵列结构的碳纳米管之间具有均匀的间隙，可以保证电解液的快速且均匀浸润，正极侧锂离子穿过 隔膜后，高浓度锂离子可以沿着均匀空隙快速传递到负极极片内部，加快电化学反应过程中的离子均匀快速传导，避免局部锂离子浓度不均匀现象，导致析锂问题；同时，通过将所述第一负极活性材料负载在具有阵列结构的碳纳米管的外管壁的表面，利于提高集流体与负极活性物质的接触面积，减少电子电阻，增加导电性。
在一些实施例中，所述第一负极活性材料为含硅材料；所述含硅材料包括硅碳材料、硅氧材料或纯硅材料中的至少一种。将所述含硅材料附着在所述碳纳米管的外管壁的表面，有助于含硅材料中的硅颗粒(包括硅碳颗粒、硅氧颗粒或者纯硅颗粒)充分接触所述碳纳米管，用以保证有效的电子通路。
在一些实施例中，所述含硅材料中还含有锂元素；所述锂元素是通过补锂材料与均匀分布的碳纳米管接触后沉积形成的；具体地，所述补锂材料与均匀分布的碳纳米管接触后，其可以均匀且快速地被吸收并沉积到含硅材料的内部。在补锂过程中，通过在集流体的一侧设置均匀分布的碳纳米管，且所述碳纳米管的表面负载有含硅材料；补锂时，首先，补锂材料与均匀分布的碳纳米管接触，此时可以避免不均匀沉积导致的局部过热现象诱发的安全隐患，其次，补锂材料被均匀吸收并沉积到含硅材料的内部，此时，可以避免补锂不均匀引发的析锂问题，同时，具有阵列结构的碳纳米管可以起到均匀导热的作用，可以很好的降低补锂温升。可见，将补锂和含有第一负极活性材料的碳纳米管阵列结构结合后，可以改善补锂效率低、发热高、安全隐患问题，进而提高首效。
在一些实施例中，所述锂元素与硅元素的质量比为5％至30％。一方面，控制锂元素与硅元素的质量比在合适的范围，可以弥补负极形成SEI膜造成的锂损失，从而提高首效和循环性能；另一方面，通过选择合适的补锂量，可以实现补锂成本、补锂效率/温升、电性能之间的平衡，有助于规模化生产。
示例性地，所述锂元素与硅元素的质量比为5％、8％、10％、14％、16％、18％、20％、24％、26％、28％、30％或上述任意两个值组成的范围。
结合图1或者图2所示，所述含硅材料的至少部分表面设置有导电材料；所述导电材料环绕包覆或者掺杂在所述含硅材料的至少部分表面甚至全部表面，所述导电材料包括碳材料、金属材料或其他具有导电性的材料中的至少一种。在所述含硅材料的表面引入适当的导电材料进行包覆，用以进一步提高所述含硅材料的导电性。
在一些实施例中，所述负极极片满足以下条件中的至少一者：
(I)沿垂直于集流体所在平面的方向观察，所述碳纳米管阵列上顶面围成的投影面积为S 1，其下底面围成的投影面积为S 2，满足：90％≤S 1/S 2≤110％；
所述碳纳米管阵列上顶面围成的投影面积S 1是指在垂直于所述集流体所在平面的方向 上，将环绕所述碳纳米管阵列顶部围成的面(即上顶面)水平延伸至一水平面上得到的面积即为投影面积S 1；下底面围成的投影面积S 2是指在垂直于所述集流体所在平面的方向上，将环绕所述碳纳米管阵列底部围成的面(即下底面)水平延伸至同一水平面上得到的面积即为投影面积S 2。
(II)在垂直于集流体表面的纵截面上，选取任一碳纳米管阵列所在区域进行EDS能谱分析，所选区域内硅元素的质量含量为w，满足：60％≤w≤95％；且对于任意选取的两个区域内，硅元素的质量含量的差值为△w，满足：△w≤20％；
所述纵截面是通过将设于所述集流体一侧的膜层沿垂直于所述集流体表面的方向进行断面处理获得的，处理的方式可以为离子抛光获取断面；所述区域通常指至少含有一根碳纳米管的区域；所述任意选取的两个区域内是指两个所述区域之间至少含有一根不同的碳纳米管。
(III)选取任一碳纳米管阵列所在区域，沿垂直于集流体所在平面的方向观察，所述碳纳米管阵列围成的投影面积与所选区域集流体投影面积的比值为S，满足：50％≤S≤100％。
所述碳纳米管阵列围成的投影面积是指将环绕所述碳纳米管阵列围成的面水平延伸至一水平面上获得的面积即为所述碳纳米管阵列围成的投影面积；其中，环绕形成的面可以是指环绕所述碳纳米管阵列任一位置处形成的面，所述碳纳米管阵列与所述集流体接触；所选区域集流体面积是指所选区域对应于集流体上的面积。
示例性地，所述碳纳米管阵列顶部围成的投影面积S 1与其底部围成的投影面积S 2比值S 1/S 2为90％、92％、95％、98％、100％、105％、108％、110％或上述任意两个值组成的范围。
示例性地，所选区域内硅元素的质量含量w为60％、65％、70％、75％、80％、85％、90％、95％或上述任意两个值组成的范围。
示例性地，多个区域内的硅元素的质量含量的差值△w为0％、1％、5％、8％、10％、15％、20％或上述任意两个值组成的范围。
示例性地，所述碳纳米管阵列围成的投影面积与所选区域集流体面积的比值S为50％、60％、70％、80％、90％、100％或上述任意两个值组成的范围。
在一些实施例中，所述负极极片满足以下条件中的至少一者：
(i)沿垂直于集流体所在平面的方向观察，所述碳纳米管阵列上顶面围成的投影面积为S 1，其下底面围成的投影面积为S 2，满足：95％≤S 1/S 2≤105％；
(ii)在垂直于集流体表面的纵截面上，选取任一碳纳米管阵列所在区域进行EDS能谱分析，所选区域内硅元素的质量含量为w，满足：80％≤w≤95％；且对于任意选取的两个区域内，硅元素的质量含量的差值为△w，满足：△w≤10％；
(iii)选取任一碳纳米管阵列所在区域，沿垂直于集流体所在平面的方向观察，所述碳纳米管阵列围成的投影面积与所选区域集流体投影面积的比值为S，满足：70％≤S≤100％。
此时，一方面可以进一步提高电解液浸润，加快离子传导，减少浓差极化；另一方面可以进一步缓冲体积膨胀，保证极片形态的完整性，在充放电过程中无褶皱，活性物质脱落等问题。
示例性地，所述碳纳米管阵列顶部围成的投影面积S 1与其底部围成的投影面积S 2比值S 1/S 2为95％、97％、98％、100％、102％、104％、105％或上述任意两个值组成的范围。
示例性地，所选区域内硅元素的质量含量w为80％、83％、85％、88％、90％、93％、95％或上述任意两个值组成的范围。
示例性地，多个区域内的硅元素的质量含量的差值△w为0％、1％、3％、5％、7％、9％、10％或上述任意两个值组成的范围。
示例性地，所述碳纳米管阵列围成的投影面积与所选区域集流体面积的比值S为70％、75％、80％、85％、90％、95％、100％或上述任意两个值组成的范围。
在一些实施例中，所述负极极片满足：(A)所述负极活性材料的平均粒径为D，满足：5nm≤D≤2μm；(B)相邻所述碳纳米管之间的间距为d，满足：20nm≤d≤5μm；(C)所述碳纳米管的管径为p，满足：5nm≤p≤100nm；(D)所述碳纳米管的长度为H，满足：5μm≤H≤80μm。
相邻所述碳纳米管可以是在所述集流体的长度方向上的相邻，也可以是在所述集流体的宽度方向上的相邻；例如，在所述集流体的长度方向，相邻所述碳纳米管之间的间距d是指沿所述集流体的长度方向上，横向排布的两个碳纳米管之间的间距(例如图3所示)；在所述集流体的宽度方向，相邻所述碳纳米管之间的间距d是指沿所述集流体的宽度方向上，纵向排布的两个碳纳米管之间的间距，两个所述碳纳米管之间的间距通常指两个所述碳纳米管中间位置处对应处的间距。所述碳纳米管的长度H是指所述碳纳米管的底端端部与其顶端端部之间的距离(例如图1所示)。
所述碳纳米管的长度方向与所述集流体的表面垂直，所述碳纳米管的长度方向是指所述碳纳米管的底端朝向所述碳纳米管的顶端的延伸方向，需要说明的是，所述碳纳米管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。
示例性地，所述负极活性材料的平均粒径D为5nm、50nm、100nm、500nm、1000nm、1500nm、2000nm或上述任意两个值组成的范围。
示例性地，相邻所述碳纳米管之间的间距d为20nm、40nm、60nm、80nm、100nm、 400nm、600nm、800nm、1000nm、1500nm、2000nm、2500nm、3000nm、3500nm、4000nm、4500nm、5000nm或上述任意两个值组成的范围。
示例性地，所述碳纳米管的管径p为5nm、10nm、15nm、20nm、35nm、50nm、70nm、85nm、90nm、100nm或上述任意两个值组成的范围。
示例性地，所述碳纳米管的长度H为5μm、10μm、15μm、20μm、25μm、30μm、35μm、40μm、45μm、50μm、60μm、80μm或上述任意两个值组成的范围。
在一些实施例中，所述负极极片满足以下条件中的至少一者：
(a)所述负极活性材料的平均粒径为D，满足：5nm≤D≤500nm；
(b)相邻所述碳纳米管之间的间距为d，满足：20nm≤d≤1μm；
(c)所述碳纳米管的长度为H，满足：5μm≤H≤40μm
(d)相邻所述碳纳米管之间的间距d与所述负极活性材料的平均粒径D的比值，满足：2＜d/D＜10；
(e)相邻所述碳纳米管之间的间距d与所述碳纳米管的管径p的比值，满足：0.2nm≤d/p≤500nm。
通过调节负极活性材料的平均粒径、相邻碳纳米管之间的间距以及碳管的长度和管径，一方面可以改善含硅材料的补锂性能，进而提高首效，另一方面，可以改善循环性能。
示例性地，所述负极活性材料的平均粒径D为5nm、50nm、80nm、100nm、150nm、200nm、250nm、300nm、350nm、400nm、450nm、500nm或上述任意两个值组成的范围。
示例性地，相邻所述碳纳米管之间的间距d为20nm、40nm、60nm、80nm、100nm、200nm、300nm、400nm、500nm、600nm、700nm、800nm、900nm、1000nm或上述任意两个值组成的范围。
示例性地，所述碳纳米管的长度H为5μm、10μm、15μm、20μm、25μm、30μm、35μm、40μm或上述任意两个值组成的范围。
示例性地，相邻所述碳纳米管之间的间距d与所述负极活性材料的平均粒径D的比值d/D为2.1、2.5、3、3.5、4、4.5、5、5.5、6、6.5、7、7.5、8、8.5、9、9.5、9.9或上述任意两个值组成的范围。
示例性地，相邻所述碳纳米管之间的间距d与所述碳纳米管的管径p的比值d/p为0.2nm、1nm、5nm、10nm、20nm、40nm、80nm、100nm、160nm、180nm、200nm、250nm、300nm、400nm、500nm或上述任意两个值组成的范围。
在一些实施例中，相邻所述碳纳米管之间的间距d与所述负极活性材料的平均粒径D的比值，满足：2≤d/D≤5。用以改善硅材料的补锂性能，提高首效以及循环电性能。
示例性地，相邻所述碳纳米管之间的间距d与所述负极活性材料的平均粒径D的比值d/D为2、2.5、3、3.5、4、4.5、5或上述任意两个值组成的范围。
在一些实施例中，相邻所述碳纳米管之间的间距d与所述碳纳米管的管径p的比值，满足：1nm≤d/p≤250nm。进一步改善硅材料的补锂性能，提高首效以及循环电性能。
示例性地，相邻所述碳纳米管之间的间距d与所述碳纳米管的管径p的比值d/p为1nm、5nm、10nm、30nm、60nm、80nm、100nm、150nm、200nm、250nm或上述任意两个值组成的范围。
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、镍膜、铁膜、金膜、银膜、铂膜、钛膜、锌膜、锰膜、碳膜、其他复合金属薄膜、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、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】
无碳纳米管阵列的纯硅极片
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10μm。用锂带对负极极片进行补锂。具体参数见表1～3。
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。
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锥形阵列结构的碳纳米管簇(S1/S2＝30％)，接着将含硅材料通过气相沉积的方式附着在锥形碳纳米管簇表面，接着通过气相沉积在含硅材料外侧再包裹一层导电材料，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10μm，具体参数见表1～3。
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。
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3】
锥形CNT簇+纯硅的极片
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
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，然后用惰性原子轰击形成阵列状锥形碳纳米管簇。接着将含硅材料通过气相沉积的方式附着在锥形碳纳米管表面，接着通过气相沉积在硅材料外侧再包裹一层导电材料，从而完成电极制备。完成后，将极片裁切成(1000mm×60mm)的规格待用，对上述极片进行补锂。膜片厚度为10μm，具体参数见表1～3。
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
将卷绕完成的电池进行封装、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，接着将含硅材料通过气相沉积的方式附着在均匀分布的碳纳米管表面，接着通过气相沉积在硅材料外侧再包裹一层导电材料，从而完成电极制备。完成后，将极片裁切成(1000mm×60mm)的规格待用，对极片进行补锂。膜片厚度为10μm，涉及参数见表1～3。
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2】～【实施例27】
实施例2～27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1～3。
测试部分
(1)含硅材料中锂元素与硅元素的质量比测试
a、取样：将电池放电至3.0V后，拆解，取出极片。极片表面用DMC冲洗，将极片表面的电解液清洗干净，并干燥。将极片冲成规则小圆片，极片总质量＞0.5g；
b、样品前处理-赶酸消解：取适量样品于消解罐中，加入消解试剂(3ml纯水+3ml硝酸+5ml HF)，摇晃消解罐，将消解罐置于赶酸仪中，加热蒸干至适当体积(180℃120min)，取出消解罐用超纯水冲洗边缘；
c、测试：①开机预热：打开稳压电源，调节氩气0.6MPa，打开仪器，打开软件；②建立方法：采用校准曲线法测试，选择测试元素为Li和硅；③点火；④测试：a)用1mg/L Mn单标作炬管准直，清洗进样系统，b)光学初始化，初始化值＜50step，c)依次用配置好的标液绘制工作曲线；d)查看曲线线性是否为R2＞0.999，e)测试质控样品，确认曲线准确性，f)录入样品信息，测试样品；⑤关机；⑥处理数据；⑦容器清洗。
(2)补锂升温以及锂吸收速率测试
将锂带置于极片表面，进行压合并静置12h。用温度传感器记录整个静置过程中的温度变化情况，补锂温升＝最高温度-室温。记录12h前后单位面积的增重情况，则为补锂量，锂吸收速率＝补锂量/时间，单位mg/(cm 2·h)。
(3)首效测试
将电化学装置在25℃环境下，以0.2C的充电速率从3.0充电至4.45V，记录此次容量为首次充电容量，再以0.2C的放电速率放电至3.0V，记录此次容量为首次放电容量，首效＝(首次放电容量/首次充电容量)×100％。
(4)循环性能测试
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％。
(5)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％。
(6)循环后膜片粘接力测试
将电池按(3)中测试方法循环200圈后，进行满放处理，即以0.2C放电至3.0V，然后拆解电池，取出极片。将待测极片用刀片裁取宽30mm，长度100mm的试样。将专用的双 面胶贴于钢板上，胶带宽度为20mm，长度为90mm。将极片试样贴在双面胶上，测试面朝下。将宽度与极片等宽，长度大于试样长度80-200mm的纸带插入极片下方，并且用皱纹胶固定。将钢板未贴极片的一端用拉力机下夹具固定。将纸带向上翻折，用拉力机上夹具固定，利用拉力机附带的手动控制器上的“上行”和“下行”按钮调整上夹具的位置。启动拉力机测试程序，测试即可。
对比例1～3和实施例1～27的测试结果参见表1～3。
表1
Figure PCTCN2022122593-appb-000001
实施例1～7与对比例1相比，通过将补锂与碳纳米管阵列结构结合，可以提高锂的利用率，进而提高首效；而且碳纳米管阵列结构可以通过碳纳米管之间的毛细作用力，加快锂的吸收，提高锂吸收速率。同时，由于碳纳米管具有高导热性，可以将补锂过程中产生的热量快速导出到外界环境中，从而极大降低补锂温升。实施例1～7与对比例2相比，通过补锂的方式，可以弥补负极形成SEI膜造成的锂损失，从而提高首效和循环性能。实施例1～4通过优化不同补锂量，实现补锂成本、补锂效率/温升、电性能之间的平衡。实施例5通过改变补锂材料，可以进一步降低补锂温升和吸收速率，但锂浆料成本略高。实施例6证明，就不同负极活性材料而言，通过碳纳米管阵列和补锂结合，均能实现相似的技术效果。实施例 7证明在不同导电层包覆下的可能性，可以从表1中看出，具有类似的技术效果，但金属类导电层会存在金属颗粒造成内部自放电的风险，导致循环性能略有降低。
表2
Figure PCTCN2022122593-appb-000002
实施例8～17与对比例1相比，补锂的利用率提高，首效提高，可见碳纳米管阵列结构可以提高锂吸收速率并降低补锂温升。无碳纳米管阵列的情况下，循环过程中，硅与锂合金化导致体积膨胀，从而使活性物质与膜片粘接力减弱；而碳纳米管具有高机械强度，可以束缚住膨胀过程中硅的体积膨胀，从而提高循环后的膜片粘接力，避免掉粉问题，保证可靠的 电子和离子导电网络结构，从而保证较好的循环性能。
实施例8～17与对比例3相比，实施例8～17具有均匀分布的碳纳米管结构，而对比例3为锥形的碳纳米管簇结构，该结构由于CNT以锥形碳簇形式出现，硅通过物理沉积附着在锥形碳簇外围，降低了碳管的导电作用，沉积在锥形碳簇最外侧的硅的导电路径长，导电性差，另外，该方式的活性负载量低于本申请的实施例，导致单位面积的容量低，同时，由于碳簇是锥形，电解液进入碳管的过程，是先经历窄口的路径，一定程度上单位面积上电解液的快速传输，使靠近集流体下端的活性物质颗粒很难快速获得离子，影响动力学。相比于锥形的碳纳米管簇结构而言，本申请的均匀的碳纳米管分布(90％≤S 1/S 2≤110％)有助于补锂物质的均匀吸收，以及均匀发热和导热功能，从而使补锂温升大大降低，另外由于硅包覆在碳管之间，相比于锥形的碳纳米管簇的间隙而言，每个硅可以充分与碳纳米管接触，保证导电网络，同时硅可以少量/单独束缚在碳管之间，而非大量硅沉积在锥形的碳纳米管簇阵列中，可以缓解体积膨胀，提高膜片粘接力。
实施例8～10中调整S 1/S 2，证明均匀排布碳管的积极作用。实施例11～13调整w，低w相比于高w具有更好的性能，但ED较低，需平衡电性能和ED，优选w值。实施例14～15，调整△w，硅的均匀沉积，有助于整体性能的提高。实施例16～17，调整碳纳米管分布情况即以图案化结构分布，有助于进一步提高电性能，降低温升，但对ED方面会存在一定程度损失。
表3
Figure PCTCN2022122593-appb-000003
Figure PCTCN2022122593-appb-000004
实施例18～27与对比例1相比，通过调节负极活性材料的颗粒尺寸D、相邻碳纳米管之间的间距d、碳纳米管的管径p以及碳纳米管的长度H的各项参数，进行优化，从而改善含硅材料的补锂性能，提高首效以及循环电性能。相比于对比例3，均匀的碳纳米管分布，可以进一步提高循环性能，特别是提高碳纳米管对硅膨胀的束缚，进而提高膜片粘接力。
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 (15)

  1. 一种电化学装置，其特征在于，包括负极极片；所述负极极片包括碳纳米管阵列；所述碳纳米管阵列中设有第一负极活性材料。
  2. 根据权利要求1所述的电化学装置，其特征在于，所述负极极片还包括集流体；
    所述碳纳米管阵列位于所述集流体上；
    所述碳纳米管阵列包括碳纳米管；
    所述第一负极活性材料位于所述碳纳米管之间。
  3. 根据权利要求1所述的电化学装置，其特征在于，所述第一负极活性材料为含硅材料。
  4. 根据权利要求3所述的电化学装置，其特征在于，所述含硅材料包括硅碳材料、硅氧材料或纯硅材料中的至少一种。
  5. 根据权利要求3所述的电化学装置，其特征在于，所述含硅材料中还包括锂元素；
    所述锂元素与硅元素的质量比为5％至30％。
  6. 根据权利要求3所述的电化学装置，其特征在于，所述含硅材料的至少部分表面设置有导电材料；
    所述导电材料包括碳材料、金属材料或其他具有导电性的材料中的至少一种。
  7. 根据权利要求2所述的电化学装置，其特征在于，所述碳纳米管阵列在所述集流体上图案化分布；或，
    所述碳纳米管阵列在所述集流体上全覆盖式分布。
  8. 根据权利要求7所述的电化学装置，其特征在于，所述碳纳米管阵列在所述集流体上图案化分布时；
    所述负极极片包括两个或两个以上间隔设置的碳纳米管阵列，所述碳纳米管阵列之间的平均距离为M；在一个所述碳纳米管阵列中，相邻所述碳纳米管之间的间距为d，满足：d＜M≤500μm，优选d＜M≤50μm。
  9. 根据权利要求1～8任一项所述的电化学装置，其特征在于，满足以下条件中的至少一者：
    (I)沿垂直于集流体所在平面的方向观察，所述碳纳米管阵列上顶面围成的投影面积为S 1，其下底面围成的投影面积为S 2，满足：90％≤S 1/S 2≤110％；
    (II)在垂直于集流体表面的纵截面上，选取任一碳纳米管阵列所在区域进行EDS能谱分析，所选区域内硅元素的质量含量为w，满足：60％≤w≤95％；且对于任意选取的两个区域内，硅元素的质量含量的差值为△w，满足：△w≤20％；
    (III)选取任一碳纳米管阵列所在区域，沿垂直于集流体所在平面的方向观察，所述碳纳米管阵列围成的投影面积与所选区域集流体投影面积的比值为S，满足：50％≤S≤100％。
  10. 根据权利要求9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)沿垂直于集流体所在平面的方向观察，所述碳纳米管阵列上顶面围成的投影面积为S 1，其下底面围成的投影面积为S 2，满足：95％≤S 1/S 2≤105％；
    (ii)在垂直于集流体表面的纵截面上，选取任一碳纳米管阵列所在区域进行EDS能谱分析，所选区域内硅元素的质量含量为w，满足：80％≤w≤95％；且对于任意选取的两个区域内，硅元素的质量含量的差值为△w，满足：△w≤10％；
    (iii)选取任一碳纳米管阵列所在区域，沿垂直于集流体所在平面的方向观察，所述碳纳米管阵列围成的投影面积与所选区域集流体投影面积的比值为S，满足：70％≤S≤100％。
  11. 根据权利要求1所述的电化学装置，其特征在于，满足：
    (A)所述负极活性材料的平均粒径为D，满足：5nm≤D≤2μm；
    (B)相邻所述碳纳米管之间的间距为d，满足：20nm≤d≤5μm；
    (C)所述碳纳米管的管径为p，满足：5nm≤p≤100nm；
    (D)所述碳纳米管的长度为H，满足：5μm≤H≤80μm。
  12. 根据权利要求11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：
    (a)所述负极活性材料的平均粒径为D，满足：5nm≤D≤500nm；
    (b)相邻所述碳纳米管之间的间距为d，满足：20nm≤d≤1μm；
    (c)所述碳纳米管的长度为H，满足：5μm≤H≤40μm
    (d)相邻所述碳纳米管之间的间距d与所述负极活性材料的平均粒径D的比值，满足： 2＜d/D＜10；
    (e)相邻所述碳纳米管之间的间距d与所述碳纳米管的管径p的比值，满足：0.2nm≤d/p≤500nm。
  13. 根据权利要求12所述的电化学装置，其特征在于，相邻所述碳纳米管之间的间距d与所述负极活性材料的平均粒径D的比值，满足：2≤d/D≤5。
  14. 根据权利要求12所述的电化学装置，其特征在于，相邻所述碳纳米管之间的间距d与所述碳纳米管的管径p的比值，满足：1nm≤d/p≤250nm。
  15. 一种电子设备，包括权利要求1至14中任一项所述的电化学装置。
PCT/CN2022/122593 2022-09-29 2022-09-29 电化学装置以及电子设备 Ceased WO2024065396A1 (zh)

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