WO2025251663A1 - 负极片及其制备方法、电池和用电设备 - Google Patents

负极片及其制备方法、电池和用电设备

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Publication number
WO2025251663A1
WO2025251663A1 PCT/CN2025/076051 CN2025076051W WO2025251663A1 WO 2025251663 A1 WO2025251663 A1 WO 2025251663A1 CN 2025076051 W CN2025076051 W CN 2025076051W WO 2025251663 A1 WO2025251663 A1 WO 2025251663A1
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WIPO (PCT)
Prior art keywords
carbon material
hard carbon
active layer
negative electrode
battery
Prior art date
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Pending
Application number
PCT/CN2025/076051
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English (en)
French (fr)
Inventor
鲍春晓
张震
王学万
彭宇东
何科峰
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BYD Co Ltd
Original Assignee
BYD Co Ltd
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Publication date
Application filed by BYD Co Ltd filed Critical BYD Co Ltd
Publication of WO2025251663A1 publication Critical patent/WO2025251663A1/zh
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/054—Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
    • 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
    • H01M4/139—Processes of manufacture
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • 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
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • 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

  • This application relates to the field of battery technology, specifically to a negative electrode sheet and its preparation method, a battery, and an electrical device.
  • Sodium-ion batteries are cheaper than lithium-ion batteries, but the energy density of existing sodium-ion battery systems is much lower than that of lithium-ion batteries, which limits the application scenarios of sodium-ion batteries.
  • sodium-ion battery anodes have significant room for improvement in specific capacity and compaction.
  • improving the specific capacity of the anode requires improving its plateau region around 0V, which would increase the capacity proportion of the plateau region. But this would lead to a decrease in the capacity proportion of the ramp region, i.e., a decrease in power performance. It is difficult to achieve both simultaneously.
  • the purpose of this application is to provide a negative electrode sheet and its preparation method, a battery, and an electrical device to solve the problem of the difficulty in balancing the power performance and battery capacity of sodium-ion batteries.
  • this application provides a negative electrode sheet, comprising:
  • a current collector having a first surface
  • n active layers are sequentially stacked on the first surface along a first direction, wherein the first direction is perpendicular to the first surface;
  • Each of the active layers includes a first hard carbon material and/or a second hard carbon material; the content of the first hard carbon material in the (m+1)th active layer is less than the content of the first hard carbon material in the mth active layer, the content of the second hard carbon material in the (m+1)th active layer is greater than the content of the second hard carbon material in the mth active layer, the mth active layer is closer to the first surface than the (m+1)th active layer, and satisfies 1 ⁇ m ⁇ n-1, where m and n are both positive integers;
  • the slope region capacity ratio of the first hard carbon material is b1, and the slope region capacity ratio of the second hard carbon material is b2, satisfying: b1 ⁇ b2;
  • the capacity of the slope region of the first hard carbon material and the second hard carbon material is the capacity of the battery sodium intercalation process at 0.1V vs. Na + /Na.
  • the following condition is also satisfied: 2 ⁇ n ⁇ 4.
  • the reversible specific capacity of the first hard carbon material is a1, which satisfies: a1 ⁇ 290mAh/g.
  • the following condition is also satisfied: 20% ⁇ b1 ⁇ 40%.
  • the following condition is also satisfied: 40% ⁇ b2 ⁇ 70%.
  • the thickness of the active layer is h, which satisfies: h ⁇ 20 ⁇ m.
  • the following condition is also satisfied: 30 ⁇ m ⁇ h ⁇ 60 ⁇ m.
  • the platform region capacity ratio of the first hard carbon material is e1, satisfying: 60% ⁇ e1 ⁇ 80%; the platform region capacity ratio of the second hard carbon material is e2, satisfying: 30% ⁇ e2 ⁇ 60%, and the capacity of the platform regions of the first hard carbon material and the second hard carbon material is the capacity of the battery sodium intercalation process from 0V vs. Na + /Na to 0.1V vs. Na + /Na.
  • this application provides a method for preparing a negative electrode sheet, comprising the following steps:
  • a current collector is provided, the current collector having a first surface
  • n active layers are sequentially stacked on the first surface along a first direction, wherein the first direction is perpendicular to the first surface;
  • Each of the active layers includes a first hard carbon material and/or a second hard carbon material; the content of the first hard carbon material in the (m+1)th active layer is less than the content of the first hard carbon material in the mth active layer, the content of the second hard carbon material in the (m+1)th active layer is greater than the content of the second hard carbon material in the mth active layer, the mth active layer is closer to the first surface than the (m+1)th active layer, and satisfies 1 ⁇ m ⁇ n-1, where m and n are both positive integers;
  • the slope region capacity ratio of the first hard carbon material is b1, and the slope region capacity ratio of the second hard carbon material is b2, satisfying: b1 ⁇ b2;
  • the capacity of the slope region of the first hard carbon material and the second hard carbon material is the capacity of the battery sodium intercalation process above 0.1V vs. Na + /Na.
  • this application provides a battery including a positive electrode, a separator, and a negative electrode as described in any of the first aspects, wherein the separator is disposed between the positive electrode and the negative electrode.
  • this application provides an electrical device, including an electrical appliance and a battery as described in the third aspect, wherein the battery supplies power to the electrical appliance.
  • the negative electrode sheet of this application has multiple active layers.
  • the active layers contain a first hard carbon material to improve battery capacity and a second hard carbon material to improve battery rate.
  • the first hard carbon material decreases in gradient along the direction away from the current collector in the active layers, while the second hard carbon material increases in gradient along the direction away from the current collector, i.e., closer to the electrode.
  • the gradient of the first and second hard carbon materials in the multi-layer active layers improves the ion exchange rate near the electrode and the ion capacity near the current collector.
  • the corresponding sodium-ion battery can achieve both improved power performance and battery capacity, resulting in improved battery capacity while having better rate performance and shorter fast charging time.
  • Figure 1 is a side view of the negative electrode and separator according to an embodiment
  • Figure 2 is a flowchart of a method for preparing a negative electrode sheet according to an embodiment.
  • a component when a component is said to be “fixed” to another component, it can be directly on the other component or it can be in a middle component.
  • a component When a component is said to be “connected” to another component, it can be directly connected to the other component or it may be in a middle component.
  • this application provides a negative electrode 100, including a current collector 10 and n active layers 20.
  • the current collector 10 has a first surface 11.
  • the n active layers 20 are sequentially stacked on the first surface 11 along a first direction X, which is perpendicular to the first surface 11.
  • Each active layer 20 includes a first hard carbon material and/or a second hard carbon material.
  • the content of the first hard carbon material in the (m+1)th active layer 20 is less than the content of the first hard carbon material in the mth active layer 20, and the content of the second hard carbon material in the (m+1)th active layer 20 is greater than the content of the second hard carbon material in the mth active layer 20.
  • the mth active layer 20 is closer to the first surface 11 than the (m+1)th active layer 20, and satisfies 1 ⁇ m ⁇ n-1, where m and n are both positive integers.
  • the first hard carbon material and the second hard carbon material have specific special properties, namely: the slope region capacity ratio of the first hard carbon material is b1, and the slope region capacity ratio of the second hard carbon material is b2, satisfying: b1 ⁇ b2.
  • the capacity of the slope region of the first hard carbon material and the second hard carbon material is the capacity of the battery sodium intercalation process above 0.1V vs. Na + /Na.
  • the corresponding current collector 10 can be any one of copper foil, composite copper foil or carbon-coated copper foil, or any one of aluminum foil, composite aluminum foil or carbon-coated aluminum foil.
  • the first and second hard carbon materials can be resin carbon (such as phenolic resin, epoxy resin, polyfurfuryl alcohol resin, etc.), organic polymer carbon (such as polyvinyl alcohol, polyvinyl chloride, polyvinylidene fluoride, polyacrylonitrile, etc.), carbon black (acetylene black prepared by chemical vapor deposition, etc.), biomass carbon (such as plant residues and shells, etc.), without limitation.
  • Hard carbon materials, as a negative electrode material for sodium-ion batteries are suitable for sodium-ion intercalation and deintercalation due to their large interlayer spacing and irregular structure.
  • the reversible specific capacity of the first hard carbon material is a1, satisfying: a1 ⁇ 290mAh/g.
  • a1 can be 290mAh/g, 300mAh/g, 350mAh/g, 400mAh/g, etc., and is not limited.
  • the following condition is also satisfied: 20% ⁇ b1 ⁇ 40%.
  • b1 can be 20%, 25%, 30%, 35%, or 40%, without limitation.
  • b1 also satisfies 30% ⁇ b1 ⁇ 40%.
  • the first hard carbon material has a1 ⁇ 290mAh/g and the slope region capacity ratio b1 satisfies 20% ⁇ b1 ⁇ 40%, making the first hard carbon material a capacity-type hard carbon material. This results in a higher energy density for the battery and the more electricity it can store.
  • the following condition is also satisfied: 40% ⁇ b2 ⁇ 70%.
  • b2 can be 40%, 50%, 60%, or 70%, without limitation.
  • b1 is 40%, then b2 cannot be 40%.
  • the second hard carbon material is a rate-controlled hard carbon material, enabling the battery to release or absorb energy more quickly, resulting in faster charging and discharging speeds and improved device efficiency.
  • the total mass of the first hard carbon material and the second hard carbon material in each active layer 20 may or may not be the same.
  • the number of active layers 20, n satisfies 1 ⁇ m ⁇ n-1. Optionally, it also satisfies 2 ⁇ n ⁇ 4; specifically, n can be 2, 3, or 4.
  • Multiple active layers 20 are stacked on the current collector 10, and as the active layers move away from the current collector 10 along the first direction X, the content gradient of the first hard carbon material in the active layers 20 decreases, while the content gradient of the second hard carbon material in the active layers 20 increases.
  • the active layer 20 directly stacked on the first surface 11 is the first active layer 20, and the active layer 20 furthest from the first surface 11 is the nth active layer 20.
  • the nth active layer 20 is in close contact with the diaphragm 200.
  • all the hard carbon material in the first active layer 20 is the first hard carbon material
  • all the hard carbon material in the nth active layer 20 is the second hard carbon material.
  • the negative electrode 100 of this application is provided with multiple active layers 20.
  • the active layers 20 are provided with a first hard carbon material to improve battery capacity and a second hard carbon material to improve battery rate.
  • the first hard carbon material in the active layers 20 decreases in a gradient away from the current collector 10, and the second hard carbon material in the active layers 20 increases in a gradient away from the current collector 10, i.e., closer to the electrode.
  • the multi-layer active layers 20 are provided with gradient-changing first and second hard carbon materials, which improves the ion exchange rate in the part near the electrode and the ion capacity in the part near the current collector.
  • the corresponding sodium-ion battery can improve battery capacity while having better rate performance and shorter fast charging time.
  • the thickness of the active layer 20 is h, satisfying: h ⁇ 20 ⁇ m. Specifically, 30 ⁇ m ⁇ h ⁇ 60 ⁇ m. h can be 20 ⁇ m, 30 ⁇ m, 40 ⁇ m, 50 ⁇ m, or 60 ⁇ m, and is not limited.
  • the active layer 20 can provide more electrochemical reaction area, thereby improving the battery capacity and energy density.
  • an excessively thick active layer 20 may increase the transport distance of electrons and ions, thereby increasing the battery's internal resistance and charging/discharging time.
  • An excessively thick active layer 20 is also susceptible to the effects of lithium dendrites, leading to a decrease in battery performance.
  • the active layer 20 can balance battery capacity, energy density, and charging/discharging speed, and can also reduce battery weight, thereby improving battery energy density and portability.
  • the platform region capacity ratio of the first hard carbon material is e1, satisfying: 60% ⁇ e1 ⁇ 80%; the platform region capacity ratio of the second hard carbon material is e2, satisfying: 30% ⁇ e2 ⁇ 60%, and the capacity of the platform regions of the first hard carbon material and the second hard carbon material is the capacity of the battery sodium intercalation process from 0V vs. Na+ /Na to 0.1V vs. Na + /Na.
  • e1 can be 60%, 65%, 70%, 75%, 80%, etc., without restriction.
  • e2 can be 30%, 40%, 50%, 60%, etc., without restriction. Specifically, the sum of e1 and b1 is 100%, and the sum of e2 and b2 is 100%.
  • the first hard carbon material has a large plateau region capacity, which enables it to have a high specific capacity; the second hard carbon material has a large plateau region capacity, which enables it to have better rate performance.
  • this application also provides a method for preparing a negative electrode 100, comprising the following steps:
  • Step S10 Provide a current collector 10, the current collector 10 having a first surface 11;
  • Step S20 n active layers 20 are sequentially stacked on the first surface 11 along the first direction X, where the first direction X is perpendicular to the first surface 11.
  • Each active layer 20 includes a first hard carbon material and/or a second hard carbon material; the content of the first hard carbon material in the (m+1)th active layer 20 is less than the content of the first hard carbon material in the mth active layer 20, the content of the second hard carbon material in the (m+1)th active layer 20 is greater than the content of the second hard carbon material in the mth active layer 20, the mth active layer 20 is closer to the first surface 11 than the (m+1)th active layer, and satisfies 1 ⁇ m ⁇ n-1, where m and n are both positive integers;
  • the capacity ratio of the slope region of the first hard carbon material is b1, and the capacity ratio of the slope region of the second hard carbon material is b2, satisfying: b1 ⁇ b2; wherein, the capacity of the slope region of the first hard carbon material and the second hard carbon material is the capacity of the battery sodium intercalation process above 0.1V vs. Na+/Na.
  • step S20 n active layers 20 are sequentially stacked on the first surface 11 along the first direction X, which can be achieved by a multilayer coating method.
  • This application provides a battery including a positive electrode, a separator 200 and a negative electrode 100 as described in any of the preceding embodiments, wherein the separator 200 is disposed between the positive electrode and the negative electrode 100.
  • the battery can be a prismatic battery, a cylindrical battery, or other types such as a prismatic battery, without any restrictions.
  • the battery also includes a casing with a receiving cavity in which the positive electrode plate, separator 200, and negative electrode plate 100 are housed.
  • the casing is made of a material with high structural strength, specifically metal, high-strength plastic, ceramic, etc. Metal materials include aluminum, aluminum alloy, magnesium alloy, iron, and iron alloys.
  • the casing includes a base plate and side plates.
  • the casing can be a one-piece structure, meaning the base plate and side plates are manufactured using a single molding process, such as stamping or casting, without limitation.
  • the casing can also be a separate structure, with the side plates and base plate connected and fixed by welding, bonding, snap-fitting, screwing, etc.
  • the wall thickness of the casing can be approximately uniform throughout, meaning the side plates can have a roughly uniform thickness, and the base plate and side plates can also have roughly the same thickness.
  • the positive electrode material of the battery can be a sodium-ion battery positive electrode active material. In specific embodiments, it includes one or more of sodium transition metal oxides, Prussian blue/white compounds, polyanionic compounds, mixed metal oxides, and layered oxides.
  • the separator 200 can be any type of woven membrane, nonwoven membrane (non-woven fabric), microporous membrane, composite membrane, rolled membrane, etc., without limitation. Several layers of separator 200 are used to separate several layers of positive and negative electrode sheets 100.
  • the positive electrode material, conductive agent, and binder are uniformly mixed and dispersed in NMP (N-methylpyrrolidone), coated onto a foil, and baked to obtain the positive electrode sheet.
  • the conductive agent includes one or more of graphite, carbon black, acetylene black, graphene, carbon fiber, C60 (carbon 60), and carbon nanotubes;
  • the binder includes one or more of polyvinylidene chloride, soluble polytetrafluoroethylene, styrene-butadiene rubber, hydroxypropyl methylcellulose, methylcellulose, carboxymethyl cellulose, polyvinyl alcohol, acrylonitrile copolymer, sodium alginate, chitosan, and chitosan derivatives, without limitation. This application does not specifically limit these materials; suitable materials can be selected according to actual application requirements.
  • This application provides an electrical device, including an electrical device and a battery as described in the foregoing embodiments, wherein the battery supplies power to the electrical device.
  • the first hard carbon material and the second hard carbon material are mixed with conductive agent, binder and other materials in deionized water in a certain proportion, and then uniformly coated on the surface of current collector 10.
  • the resulting negative electrode sheet 100 is baked and rolled.
  • the positive electrode, separator 200 and negative electrode 100 are wound sequentially and orderly to obtain the electrode core.
  • This embodiment provides a negative electrode 100, which includes a current collector 10 and two active layers 20.
  • the first active layer 20 of the two active layers 20 is disposed on the first surface 11 of the current collector 10, and the second active layer 20 is disposed on the surface of the first active layer 20 away from the current collector 10.
  • the mass ratio of the first hard carbon material and the second hard carbon material of the negative electrode 100 is 1:1.
  • the first hard carbon material is resin carbon
  • the second hard carbon material is biomass carbon.
  • the thickness h of both the first active layer 20 and the second active layer 20 is 40 ⁇ m ⁇ 2 ⁇ m.
  • the a1 of the first hard carbon material is 315.6 mAh/g
  • the reversible specific capacity of the second hard carbon material is a2
  • a2 is 280.4 mAh/g
  • the b1 of the first hard carbon material is 34.3%
  • the b2 of the second hard carbon material is 43.4%.
  • the mass ratio of the first hard carbon material to the second hard carbon material in the first active layer 20 is 6:4.
  • the mass ratio of the first hard carbon material to the second hard carbon material in the second active layer 20 is 4:6.
  • This embodiment provides a negative electrode 100, which is basically the same as that in Embodiment 1, except that:
  • the mass ratio of the first hard carbon material to the second hard carbon material in the first active layer 20 is 8:2.
  • the mass ratio of the first hard carbon material to the second hard carbon material is 2:8.
  • This embodiment provides a negative electrode 100, which is basically the same as that in Embodiment 1, except that:
  • the mass ratio of the first hard carbon material to the second hard carbon material in the first active layer 20 is 10:0.
  • the mass ratio of the first hard carbon material to the second hard carbon material in the second active layer 20 is 0:10.
  • This embodiment provides a negative electrode 100, which is basically the same as that in embodiment 3, except that:
  • the second hard carbon material is resin carbon
  • the a2 of the second hard carbon material is 262.6 mAh/g, and the b2 of the second hard carbon material is 60%.
  • This embodiment provides a negative electrode 100, which is basically the same as that in embodiment 4, except that:
  • the a2 of the second hard carbon material is 248.8 mAh/g, and the b2 of the second hard carbon material is 70%.
  • This embodiment provides a negative electrode 100, which is basically the same as that in embodiment 3, except that:
  • the a1 of the first hard carbon material is 300 mAh/g, and the b1 of the first hard carbon material is 36%.
  • This embodiment provides a negative electrode 100, which is basically the same as that in embodiment 3, except that:
  • the a1 of the first hard carbon material is 290 mAh/g, and the b1 of the first hard carbon material is 39%.
  • This comparative example provides a negative electrode 100, which is basically the same as that in Example 1, except that:
  • the mass ratio of the first hard carbon material to the second hard carbon material in the active layer 20 is 5:5.
  • This comparative example provides a negative electrode 100, which is basically the same as that in Example 1, except that:
  • the mass ratio of the first hard carbon material to the second hard carbon material in the first active layer 20 is 4:6.
  • the mass ratio of the first hard carbon material to the second hard carbon material is 6:4.
  • This comparative example provides a negative electrode 100, which is basically the same as that in Example 2, except that:
  • the mass ratio of the first hard carbon material to the second hard carbon material in the first active layer 20 is 2:8.
  • the mass ratio of the first hard carbon material to the second hard carbon material in the second active layer 20 is 8:2.
  • This comparative example provides a negative electrode 100, which is basically the same as that in Example 3, except that:
  • the mass ratio of the first hard carbon material to the second hard carbon material in the first active layer 20 is 0:10.
  • the mass ratio of the first hard carbon material to the second hard carbon material is 10:0.
  • This comparative example provides a negative electrode 100, which is basically the same as that in Example 4, except that:
  • This comparative example provides a negative electrode sheet that is basically the same as that in Example 5, except that:
  • This comparative example provides a negative electrode sheet that is basically the same as that in Example 6, except that:
  • This comparative example provides a negative electrode sheet that is basically the same as that in Example 7, except that:
  • Table 1 shows the distribution of the mass ratio of the first hard carbon material and the second hard carbon material in each layer of the current collector 10 in the negative electrode sheets of Examples 1-7 and Comparative Examples 1-8.
  • Table 2 shows the data on the reversible specific capacity and the proportion of the ramp region of the first hard carbon material and the second hard carbon material in Examples 1-7 and Comparative Examples 1-8.
  • Table 3 compares the energy density and charging capacity of the batteries corresponding to Examples 1-7 and Comparative Examples 1-8.
  • Example 1 Comparing Example 1 with Comparative Example 2, Example 2 with Comparative Example 3, and Example 3 with Comparative Example 4, it can be seen that when the mass ratio of the first hard carbon material and the second hard carbon material in the corresponding active layer 20 is reversed, the fast charging time of the battery increases.
  • the battery with a higher proportion of the first hard carbon material has a higher specific capacity but a longer fast charging time; the battery with a higher proportion of the second hard carbon material has a shorter fast charging time but a higher specific capacity; adding both the first and second hard carbon materials can balance the specific capacity and fast charging performance of the battery; further gradient design of the first and second hard carbon materials can further improve the fast charging performance of the battery.

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Abstract

一种负极片（100）及其制备方法、电池和用电设备，负极片（100）包括集流体（10）和n个活性层（20），集流体（10）具有第一表面（11）；n个活性层（20），沿第一方向（X）依次层叠设置在第一表面（11），第一方向（X）垂直于第一表面（11）；每一活性层（20）包括第一硬碳材料和/或第二硬碳材料；第m+1个活性层（20）中的第一硬碳材料的含量小于第m个活性层（20）中的第一硬碳材料的含量，第m+1个活性层（20）中的第二硬碳材料的含量大于第m个活性层（20）中的第二硬碳材料的含量，第m个活性层（20）相比于第m+1个活性层（20）更靠近第一表面（11），且满足1≤m≤n-1，m、n均为正整数；第一硬碳材料的斜坡区容量占比为b1，第二硬碳材料的斜坡区容量占比为b2，满足：b1＜b2。该负极片（100）能使电池同时兼顾能量密度和充电能力。

Description

负极片及其制备方法、电池和用电设备
本申请要求于2024年06月03日提交中国专利局、申请号为202410711813.5、申请名称为“负极片及其制备方法、电池和用电设备”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及电池技术领域，具体涉及一种负极片及其制备方法、电池和用电设备。
背景技术
钠离子电池成本低于锂离子电池，但现有钠离子电池体系能量密度远低于锂离子电池，限制了钠离子电池的应用场景。
其中，钠离子电池负极的克容量和压实改善空间较大。然而，负极的克容量提升需要提升其在0V左右的平台区，对应的平台区容量占比会提升，但如此会带来斜坡区容量比例的降低，即动力性能的下降，二者很难兼顾。
发明内容
本申请的目的是提供一种负极片及其制备方法、电池和用电设备，解决钠离子电池动力性能和电池容量难以兼顾的问题。
为实现本申请的目的，本申请提供了如下的技术方案：
第一方面，本申请提供一种负极片，包括：
集流体，具有第一表面；
n个活性层，沿第一方向依次层叠设置在所述第一表面，所述第一方向垂直于所述第一表面；
每一所述活性层包括第一硬碳材料和/或第二硬碳材料；第m+1个所述活性层中的所述第一硬碳材料的含量小于第m个所述活性层中的所述第一硬碳材料的含量，第m+1个所述活性层中的所述第二硬碳材料的含量大于第m个所述活性层中的所述第二硬碳材料的含量，第m个所述活性层相比于第m+1个所述活性层更靠近所述第一表面，且满足1≤m≤n-1，m、n均为正整数；
所述第一硬碳材料的斜坡区容量占比为b1，所述第二硬碳材料的斜坡区容量占比为b2，满足：b1＜b2；
且，所述第一硬碳材料和所述第二硬碳材料的所述斜坡区的容量为电池嵌钠过程在0.1V vs.Na+/Na以上的容量。
一种实施方式中，还满足：2≤n≤4。
一种实施方式中，所述第一硬碳材料的可逆克容量为a1，满足：a1≥290mAh/g。
一种实施方式中，还满足：20％≤b1≤40％。
一种实施方式中，还满足：40％≤b2≤70％。
一种实施方式中，所述活性层的厚度为h，满足:h≥20μm。
一种实施方式中，还满足：30μm≤h≤60μm。
一种实施方式中，所述第一硬碳材料的平台区容量占比为e1，满足：60％≤e1≤80％；所述第二硬碳材料的平台区容量占比为e2，满足：30％≤e2≤60％，所述第一硬碳材料和所述第二硬碳材料的平台区的容量为电池嵌钠过程在0V vs.Na+/Na至0.1V vs.Na+/Na的容量。
第二方面，本申请提供一种负极片的制备方法，包括如下步骤：
提供集流体，所述集流体具有第一表面；
在所述第一表面上沿第一方向依次层叠n个活性层，所述第一方向垂直于所述第一表面；
每一所述活性层包括第一硬碳材料和/或第二硬碳材料；第m+1个所述活性层中的所述第一硬碳材料的含量小于第m个所述活性层中的所述第一硬碳材料的含量，第m+1个所述活性层中的所述第二硬碳材料的含量大于第m个所述活性层中的所述第二硬碳材料的含量，第m个所述活性层相比于第m+1个所述活性层更靠近所述第一表面，且满足1≤m≤n-1，m、n均为正整数；
所述第一硬碳材料的斜坡区容量占比为b1，所述第二硬碳材料的斜坡区容量占比为b2，满足：b1＜b2；
其中，所述第一硬碳材料和所述第二硬碳材料的所述斜坡区的容量为电池嵌钠过程在0.1V vs.Na+/Na以上的容量。
第三方面，本申请提供一种电池，包括正极片、隔膜和如第一方面任一项所述的负极片，所述隔膜设置于所述正极片和所述负极片之间。
第四方面，本申请提供一种用电设备，包括用电装置和如第三方面所述的电池，所述电池向所述用电装置供电。
本申请的负极片设置有多个活性层，活性层中设置有提高电池容量的第一硬碳材料和提高电池倍率的第二硬碳材料，且第一硬碳材料在活性层中沿远离集流体的方向梯度减少，第二硬碳材料在活性层中沿远离集流体的方向即靠近电极的方向上梯度增加，多层活性层中设置梯度变化的第一硬碳材料和第二硬碳材料，使得在靠近电极的部分的离子交换速率提升，在靠近集流体的部分的离子容纳能力提升，对应的钠离子电池能兼顾动力性能和电池容量的改善，使电池的电池容量提升的同时能具有更好的倍率性能，更短的快充时间。
附图说明
为了更清楚地说明本申请实施方式或现有技术中的技术方案，下面将对实施方式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方式，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1是一种实施例的负极片和隔膜的侧视图；
图2是一种实施例的负极片的制备方法的流程图。
附图标记说明：
100-负极片，10-集流体，11-第一表面，20-活性层，200-隔膜，X-第一
方向。
具体实施方式
下面将结合本申请实施方式中的附图，对本申请实施方式中的技术方案进行清楚、完整地描述，显然，所描述的实施方式仅仅是本申请一部分实施方式，而不是全部的实施方式。基于本申请中的实施方式，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施方式，都属于本申请保护的范围。
需要说明的是，当组件被称为“固定于”另一个组件，它可以直接在另一个组件上或者也可以存在居中的组件。当一个组件被认为是“连接”另一个组件，它可以是直接连接到另一个组件或者可能同时存在居中组件。
除非另有定义，本申请所使用的所有的技术和科学术语与属于本申请的技术领域的技术人员通常理解的含义相同。本申请中在说明书中所使用的术语只是为了描述具体的实施例的目的，不是旨在于限制本申请。本申请所使用的术语“及/或”包括一个或多个相关的所列项目的任意的和所有的组合。
下面结合附图，对本申请的一些实施方式作详细说明。在不冲突的情况下，下述的实施例及实施例中的特征可以相互组合。
参考图1，本申请提供一种负极片100，包括集流体10和n个活性层20。集流体10具有第一表面11。n个活性层20沿第一方向X依次层叠设置在第一表面11，第一方向X垂直于第一表面11。每一活性层20包括第一硬碳材料和/或第二硬碳材料。第m+1个活性层20中的第一硬碳材料的含量小于第m个活性层20中的第一硬碳材料的含量，第m+1个活性层20中的第二硬碳材料的含量大于第m个活性层20中的第二硬碳材料的含量，第m个活性层20相比于第m+1个活性层20更靠近第一表面11，且满足1≤m≤n-1，m、n均为正整数。
第一硬碳材料和第二硬碳材料具体特殊性质，具体为：第一硬碳材料的斜坡区容量占比为b1，第二硬碳材料的斜坡区容量占比为b2，满足：b1＜b2；
其中，第一硬碳材料和第二硬碳材料的斜坡区的容量为电池嵌钠过程在0.1V vs.Na+/Na以上的容量。
极片为负极片100时，对应的集流体10可为铜箔、复合铜箔或涂炭铜箔中的任意一种，或，铝箔、复合铝箔或涂炭铝箔中的任意一种。
第一硬碳材料和第二硬碳材料可为树脂碳(如酚醛树脂、环氧树脂、聚糠醇树脂等)、有机聚合物碳(如聚乙烯醇、聚氯乙烯、聚偏二氟乙烯、聚丙烯腈等)、炭黑(化学气相沉积法制备的乙炔黑等)、生物质碳(如植物残渣和外壳等)，不做限制。硬碳材料作为钠离子电池的负极材料，由于其具有较大的层间距和不规则结构，适合钠离子脱嵌。
一种实施方式中，第一硬碳材料的可逆克容量为a1，满足：a1≥290mAh/g。a1可为290mAh/g、300mAh/g、350mAh/g、400mAh/g等，不做限制。
一种实施方式中，还满足：20％≤b1≤40％。b1可为20％、25％、30％、35％、40％，不做限制。可选的，b1还满足30％≤b1≤40％。
第一硬碳材料的a1≥290mAh/g且斜坡区容量占比b1满足20％≤b1≤40％，使得第一硬碳材料为容量型硬碳材料，使电池的能量密度就越大，能够储存的电量就越多。
一种实施方式中，还满足：40％≤b2≤70％。b2可为40％、50％、60％、70％，不做限制。可选的，40％≤b2≤60％。且b1为40％时，则b2不可为40％。第二硬碳材料为倍率型硬碳材料，使电池能够更快地释放或吸收能量，使电池的充电和放电速度快，可以提高设备的工作效率。
每一活性层20中的第一硬碳材料和第二硬碳材料的质量总和可一致，也可不一致。
活性层20的层数n满足1≤m≤n-1。可选的，还满足2≤n≤4，具体的，n可为2、3、4。多个活性层20层叠设置在集流体10上，且沿第一方向X远离集流体10时，活性层20中第一硬碳材料的含量梯度减少，活性层20中第二硬碳材料的含量梯度增加。参考图1，直接层叠在第一表面11上的活性层20为第1层活性层20，与第一表面11距离最远的活性层20为第n层活性层20，且第n层活性层20与隔膜200紧贴，可选的，第1层活性层20中的硬碳材料全为第一硬碳材料，第n层活性层20中的硬碳材料全为第二硬碳材料。
本申请的负极片100设置有多个活性层20，活性层20中设置有提高电池容量的第一硬碳材料和提高电池倍率的第二硬碳材料，且第一硬碳材料在活性层20中沿远离集流体10的方向梯度减少，第二硬碳材料在活性层20中沿远离集流体10的方向即靠近电极的方向上梯度增加，多层活性层20中设置梯度变化的第一硬碳材料和第二硬碳材料，使得在靠近电极的部分的离子交换速率提升，在靠近集流体的部分的离子容纳能力提升，对应的钠离子电池提高电池容量的同时，能具有更好的倍率性能，更短的快充时间。
一种实施方式中，活性层20的厚度为h，满足:h≥20μm。具体的，30μm≤h≤60μm。h可为20μm、30μm、40μm、50μm、60μm，不做限制。
h≥20μm时，活性层20可以提供更多的电化学反应面积，从而提高电池的容量和能量密度。
h＞60μm时，过厚的活性层20可能会导致电子和离子的传输距离增加，从而增加电池的内阻和充电/放电时间。过厚的活性层20也容易受到锂枝晶的影响，导致电池性能下降；30μm≤h≤60μm时，活性层20能兼顾电池的容量、能量密度和充电/放电速度，还可以减轻电池的重量，从而提高电池的能量密度和便携性。
一种实施方式中，第一硬碳材料的平台区容量占比为e1，满足：60％≤e1≤80％；第二硬碳材料的平台区容量占比为e2，满足：30％≤e2≤60％，第一硬碳材料和第二硬碳材料的平台区的容量为电池嵌钠过程在0Vvs.Na+/Na至0.1V vs.Na+/Na的容量。
e1可为60％、65％、70％、75％、80％等，不做限制。e2可为30％、40％、50％、60％等，不做限制。具体的，e1与b1的和为100％，e2与b2的和为100％。
第一硬碳材料的平台区容量占比大，使得第一硬碳材料能具有较高的克容量；第二硬碳材料的平台区占比大，能使第二硬碳材料具有较好的倍率性能。
参考图1和图2，本申请还提供一种负极片100的制备方法，包括如下步骤：
步骤S10，提供集流体10，集流体10具有第一表面11；
步骤S20，在第一表面11上沿第一方向X依次层叠n个活性层20，第一方向X垂直于第一表面11。
每一活性层20包括第一硬碳材料和/或第二硬碳材料；第m+1个活性层20中的第一硬碳材料的含量小于第m个活性层20中的第一硬碳材料的含量，第m+1个活性层20中的第二硬碳材料的含量大于第m个活性层20中的第二硬碳材料的含量，第m个活性层20相比于第m+1个活性层更靠近第一表面11，且满足1≤m≤n-1，m、n均为正整数；
第一硬碳材料的斜坡区容量占比为b1，第二硬碳材料的斜坡区容量占比为b2，满足：b1＜b2；其中，第一硬碳材料和第二硬碳材料的斜坡区的容量为电池嵌钠过程在0.1V vs.Na+/Na以上的容量。
步骤S20中，在第一表面11上沿第一方向X依次层叠n个活性层20可采用多层涂布的方法。
本申请提供一种电池，包括正极片、隔膜200和如前述任一项实施方式所述的负极片100，隔膜200设置于正极片和负极片100之间。
该电池可为方壳电池、圆柱电池等，还可为其他类型的如棱柱电池等，不做限制。
电池还包括外壳，外壳开设有容纳腔，正极片、隔膜200和负极片100收容于容纳腔内。外壳为具有较高结构强度的材料，具体可为金属材料、高强度塑料、陶瓷等，金属材料例如铝、铝合金、镁合金、铁及铁合金等。外壳包括底板和侧板，外壳可为一体式结构，即底板和侧板为一体成型工艺制作的一体式结构，一体成型工艺具体可为冲压、铸造等，不做限制。外壳也可分体式结构，侧板和底板可通过焊接、粘接、卡接、螺接等方式连接固定。外壳的各处的壁厚可大致均匀，即侧板的厚度可大致均匀一致，底板和侧板的厚度也可大致相同。
电池的正极材料可为钠电正极活性材料，具体实施例中，包括钠过渡金属氧化物、普鲁士蓝/白化合物、聚阴离子化合物、混合金属氧化物、层状氧化物的一种或多种。
隔膜200可为织造膜、非织造膜(无纺布)、微孔膜、复合膜、碾压膜等的任一种，不做限制。若干层正负极片100之间使用若干层隔膜200隔开。
将正极材料、导电剂、粘结剂在NMP(N-甲基吡咯烷酮)中均匀混合分散，涂敷在箔材上，烘烤后得到正极极片。导电剂包括石墨、碳黑、乙炔黑、石墨烯、碳纤维、C60(碳60)和碳纳米管中的一种或多种；粘结剂的种类包括聚偏氯乙烯、可溶性聚四氟乙烯、丁苯橡胶、羟丙基甲基纤维素、甲基纤维素、羧甲基纤维素、聚乙烯醇、丙烯腈共聚物、海藻酸钠、壳聚糖和壳聚糖衍生物中的一种或多种，不做限制。本申请对这些材料不做具体限定，可根据实际应用需求选择合适的材料。
本申请提供一种用电设备，包括用电装置和如前述实施方式所述的电池，电池向用电装置供电。
本申请一种实施例的电池的制备流程如下：
将第一硬碳材料和第二硬碳材料与导电剂、粘结剂等按比例均匀混合在去离子水中，均匀涂覆在集流体10表面，烘烤辊压后的到负极片100。
将正极片，隔膜200和负极片100依次有序卷绕，得到极芯。
极芯套壳后，注入电解液，经过陈化、老化、化成和分容得到完整的二次钠离子电池。
以下通过具体实施例对本申请的技术方案进行详细说明。
实施例1
本实施例提供一种负极片100，负极片100包括集流体10和两层活性层20。
两层活性层20中的第1层活性层20设置于集流体10的第一表面11上，第2层活性层20设置于第1层活性层20远离集流体10的一侧表面上。负极片100的整体的第一硬碳材料和第二硬碳材料的质量比为1：1。第一硬碳材料为树脂碳，第二硬碳材料为生物质碳。第1层活性层20和第2层活性层20的厚度h均为40μm±2μm。
第一硬碳材料的a1为315.6mAh/g，第二硬碳材料的可逆克容量为a2，a2为280.4mAh/g，第一硬碳材料的b1为34.3％，第二硬碳材料的b2为43.4％。
第1层活性层20中第一硬碳材料：第二硬碳材料的质量比为6：4。
第2层活性层20中第一硬碳材料：第二硬碳材料的质量比为4：6。
实施例2
本实施例提供一种负极片100，与实施例1基本相同，区别在于：
第1层活性层20中第一硬碳材料：第二硬碳材料的质量比为8：2。
第2层活性层20中第一硬碳材料：第二硬碳材料的质量比为2：8。
实施例3
本实施例提供一种负极片100，与实施例1基本相同，区别在于：
第1层活性层20中第一硬碳材料：第二硬碳材料的质量比为10：0。
第2层活性层20中第一硬碳材料：第二硬碳材料的质量比为0：10。
实施例4
本实施例提供一种负极片100，与实施例3基本相同，区别在于：
第二硬碳材料为树脂碳；
第二硬碳材料的a2为262.6mAh/g，第二硬碳材料的b2为60％。
实施例5
本实施例提供一种负极片100，与实施例4基本相同，区别在于：
第二硬碳材料的a2为248.8mAh/g，第二硬碳材料的b2为70％。
实施例6
本实施例提供一种负极片100，与实施例3基本相同，区别在于：
第一硬碳材料的a1为300mAh/g，第一硬碳材料的b1为36％。
实施例7
本实施例提供一种负极片100，与实施例3基本相同，区别在于：
第一硬碳材料的a1为290mAh/g，第一硬碳材料的b1为39％。
对比例1
本对比例提供一种负极片100，与实施例1基本相同，区别在于：
只具有1层活性层20，且对比例1的活性层20的厚度与实施例1的两层活性层20的总厚度相同，活性层20中第一硬碳材料：第二硬碳材料的质量比为5：5。
对比例2
本对比例提供一种负极片100，与实施例1基本相同，区别在于：
第1层活性层20中第一硬碳材料：第二硬碳材料的质量比为4：6。
第2层活性层20中第一硬碳材料：第二硬碳材料的质量比为6：4。
对比例3
本对比例提供一种负极片100，与实施例2基本相同，区别在于：
第1层活性层20中第一硬碳材料：第二硬碳材料的质量比为2：8。
第2层活性层20中第一硬碳材料：第二硬碳材料的质量比为8：2。
对比例4
本对比例提供一种负极片100，与实施例3基本相同，区别在于：
第1层活性层20中第一硬碳材料：第二硬碳材料的质量比为0：10。
第2层活性层20中第一硬碳材料：第二硬碳材料的质量比为10：0。
对比例5
本对比例提供一种负极片100，与实施例4基本相同，区别在于：
只具有1层活性层20，且对比例5的活性层20的厚度与实施例4的两层活性层20的总厚度相同。
对比例6
本对比例提供一种负极片，与实施例5基本相同，区别在于：
只具有1层活性层20，且对比例6的活性层20的厚度与实施例5的两层活性层20的总厚度相同。
对比例7
本对比例提供一种负极片，与实施例6基本相同，区别在于：
只具有1层活性层20，且对比例7的活性层20的厚度与实施例6的两层活性层20的总厚度相同。
对比例8
本对比例提供一种负极片，与实施例7基本相同，区别在于：
只具有1层活性层20，且对比例8的活性层20的厚度与实施例7的两层活性层20的总厚度相同。
表1为实施例1-7和对比例1-8的负极片中的第一硬碳材料和第二硬碳材料在集流体10上的每一层中的质量比的分布情况，表2为实施例1-7和对比例1-8的第一硬碳材料和第二硬碳材料的可逆克容量和斜坡区占比的数据，表3为实施例1-7和对比例1-8对应的电池的能量密度和充电能力对比。
表1
表2

表3

可参考表1-3，对比实施例1-3可知，双层活性层20的电池随着第一硬碳材料和第二硬碳材料的梯度变化的幅度增大，电池的克容量增加，电池的快充时间减少。
对比实施例1和对比例2、实施例2和对比例3、实施例3和对比例4可知，对应的活性层20中的第一硬碳材料和第二硬碳材料的质量比对调时，电池的快充时间增加。
对比实施例1-3和对比例1可知，在电池的克容量相近的情况下，只具有第1层活性层20的电池的快充时间大于具有两层活性层20的电池的快充时间。
对比实施例4和实施例5可知，第二硬碳材料的斜坡区占比b2越大，第二硬碳材料的可逆克容量a2越小。对比实施例6和实施例7可知，第一硬碳材料的斜坡区占比b1越大，第一硬碳材料的可逆克容量a1越小。
对比实施例1-3和对比例2-4可知，实施例1-3的电池的克容量与对比例2-4的电池的克容量相近，但实施例1-3的电池的快充时间均小于对比例2-4的电池的快充时间，最大的快充时间的差值为实施例3和对比例4，最大可达到9.2min。因此，本申请的电池在保证电池的克容量的同时改善了电池的充电能力，即本申请的电池能兼顾电池容量和动力性能。
对比实施例4和对比例5、实施例5和对比例6、实施例6和对比例7、实施例7和对比例8可知，在第一硬碳材料和第二硬碳材料的可逆克容量以及斜坡区占比均不变的情况下，改变第一硬碳材料和第二硬碳材料的分布情况，对电池的克容量影响不大，但使用本申请的负极片(双层涂布且第一硬碳材料更靠近集流体的负极片)的电池的快充时间明显下降，因此可认为实施例4-7的电池在保证电池容量的前提下减少了快充时间，即本申请的电池能兼顾电池容量和动力性能。
对比实施例3-5可知，改变第二硬碳材料的斜坡区占比b2使得电池的克容量下降，对应的电池的快充时间有所提升，但电池的克容量下降5.25％时，电池的快充时间能缩短26.2％，说明本申请的电池能兼顾电池容量和动力性能。对比实施例1-5可知，第一硬碳材料占比多的电池的克容量高，但快充时间长；第二硬碳材料占比多的电池的快充时间短，但克容量高；同时加入第一硬碳材料和第二硬碳材料能平衡电池的克容量和快充性能；再对电池的第一硬碳材料和第二硬碳材料的分别进行梯度设计，能进一步提升电池的快充性能。
在本申请实施例的描述中，需要说明的是，术语“中心”、“上”、“下”、“左”、“右”、“竖直”、“水平”、“内”、“外”等指标的方位或位置关系为基于附图所述的方位或位置关系，仅是为了便于描述本申请和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本申请的限制。
以上所揭露的仅为本申请一种较佳实施例而已，当然不能以此来限定本申请之权利范围，本领域普通技术人员可以理解实现上述实施例的全部或部分流程，并依本申请权利要求所作的等同变化，仍属于本申请所涵盖的范围。

Claims (11)

  1. 一种负极片(100)，其特征在于，包括：
    集流体(10)，具有第一表面(11)；
    n个活性层(20)，沿第一方向(X)依次层叠设置在所述第一表面(11)，所述第一方向(X)垂直于所述第一表面(11)；
    每一所述活性层(20)包括第一硬碳材料和/或第二硬碳材料；第m+1个所述活性层(20)中的所述第一硬碳材料的含量小于第m个所述活性层(20)中的所述第一硬碳材料的含量，第m+1个所述活性层(20)中的所述第二硬碳材料的含量大于第m个所述活性层(20)中的所述第二硬碳材料的含量，第m个所述活性层(20)相比于第m+1个所述活性层(20)更靠近所述第一表面(11)，且满足1≤m≤n-1，m、n均为正整数；
    所述第一硬碳材料的斜坡区容量占比为b1，所述第二硬碳材料的斜坡区容量占比为b2，满足：b1＜b2；
    其中，所述第一硬碳材料和所述第二硬碳材料的所述斜坡区的容量为电池嵌钠过程在0.1V vs.Na+/Na以上的容量。
  2. 根据权利要求1所述的负极片(100)，其特征在于，还满足：2≤n≤4。
  3. 根据权利要求1所述的负极片(100)，其特征在于，所述第一硬碳材料的可逆克容量为a1，满足：a1≥290mAh/g。
  4. 根据权利要求1所述的负极片(100)，其特征在于，还满足：20％≤b1≤40％。
  5. 根据权利要求1所述的负极片(100)，其特征在于，还满足：40％≤b2≤70％。
  6. 根据权利要求1所述的负极片(100)，其特征在于，所述活性层(20)的厚度为h，满足:h≥20μm。
  7. 根据权利要求6所述的负极片(100)，其特征在于，还满足：30μm≤h≤60μm。
  8. 根据权利要求1所述的负极片(100)，其特征在于，所述第一硬碳材料的平台区容量占比为e1，满足：60％≤e1≤80％；所述第二硬碳材料的平台区容量占比为e2，满足：30％≤e2≤60％，所述第一硬碳材料和所述第二硬碳材料的平台区的容量为电池嵌钠过程在0V vs.Na+/Na至0.1V vs.Na+/Na的容量。
  9. 一种负极片(100)的制备方法，其特征在于，包括：
    提供集流体(10)，所述集流体(10)具有第一表面(11)；
    在所述第一表面(11)上沿第一方向(X)依次层叠n个活性层(20)，所述第一方向(X)垂直于所述第一表面(11)；
    每一所述活性层(20)包括第一硬碳材料和/或第二硬碳材料；第m+1个所述活性层(20)中的所述第一硬碳材料的含量小于第m个所述活性层(20)中的所述第一硬碳材料的含量，第m+1个所述活性层(20)中的所述第二硬碳材料的含量大于第m个所述活性层(20)中的所述第二硬碳材料的含量，第m个所述活性层(20)相比于第m+1个所述活性层(20)更靠近所述第一表面(11)，且满足1≤m≤n-1，m、n均为正整数；
    所述第一硬碳材料的斜坡区容量占比为b1，所述第二硬碳材料的斜坡区容量占比为b2，满足：b1＜b2；
    其中，所述第一硬碳材料和所述第二硬碳材料的所述斜坡区的容量为电池嵌钠过程在0.1V vs.Na+/Na以上的容量。
  10. 一种电池，其特征在于，包括正极片、隔膜(200)和如权利要求1至8任一项所述的负极片(100)，所述隔膜(200)设置于所述正极片和所述负极片(100)之间。
  11. 一种用电设备，其特征在于，包括用电装置和如权利要求10所述的电池，所述电池向所述用电装置供电。
PCT/CN2025/076051 2024-06-03 2025-02-06 负极片及其制备方法、电池和用电设备 Pending WO2025251663A1 (zh)

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