CN116454284B - Negative electrode sheet, secondary battery and device comprising same - Google Patents

Negative electrode sheet, secondary battery and device comprising same Download PDF

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CN116454284B
CN116454284B CN202310704991.0A CN202310704991A CN116454284B CN 116454284 B CN116454284 B CN 116454284B CN 202310704991 A CN202310704991 A CN 202310704991A CN 116454284 B CN116454284 B CN 116454284B
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negative electrode
mass
material layer
carbon
silicon
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CN116454284A (en
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陈帅
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Weilai Battery Technology Anhui Co ltd
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Weilai Battery Technology Anhui Co ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—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
    • 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
    • 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
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • 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

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

The application provides a negative electrode plate, a secondary battery and a device comprising the secondary battery, wherein the negative electrode plate comprises a negative electrode current collector and a negative electrode material layer arranged on at least one surface of the negative electrode current collector, the negative electrode material layer comprises a negative electrode active material and a conductive agent, the negative electrode active material comprises a carbon-based material and a silicon-based material, the conductive agent comprises carbon nano tubes, and the content of the carbon nano tubes satisfies the following relational expression:wherein Cap is the specific capacity of the negative electrode;an aspect ratio of the carbon nanotubes; m is M CNT The mass content of the carbon nanotubes is based on the mass of the negative electrode material layer. The negative electrode plate provided by the application has good first charge and discharge efficiency and rate capability on the premise of higher specific capacity.

Description

Negative electrode sheet, secondary battery and device comprising same
Technical Field
The application relates to a negative electrode plate, in particular to a negative electrode plate, a secondary battery and a device comprising the secondary battery, and belongs to the field of batteries.
Background
With the widespread use of lithium ion batteries in the power field, higher demands are also being made on their energy density to eliminate mileage anxiety during application. Compared with the graphite anode materials widely used at present, the silicon-based material has extremely high theoretical capacity and is considered as the first choice material of the next-generation high-energy-density secondary battery. However, the silicon-based material is far higher than the problems of volume expansion and particle breakage of graphite, so that the longitudinal electron conduction capacity of the pole piece is greatly reduced and part of broken particles lose the electron activity in the practical application process.
Carbon Nanotubes (CNTs) are one of the necessary conductive agents for the negative electrode of a silicon-containing system due to their advantages of high electron conductivity, high aspect ratio, specific surface area, and the like. The carbon nanotubes have a high aspect ratio, which results in the ability to continue to ensure long-range electron conduction between particles after expansion of the active material. In addition, the high specific surface area of the carbon nano tube can provide a high contact area with the active material, so that the possibility of losing the electronic activity of the active material is reduced. In addition, the cost of carbon nanotubes is far higher than that of ordinary carbon black, especially single-walled carbon nanotubes. Therefore, when designing a high specific capacity negative electrode sheet compounded by graphite and a silicon-based material, the content of the carbon nano tube directly relates to the dynamics (first charge-discharge efficiency and multiplying power) of an electrode layer surface and the manufacturing cost of the electrode.
Disclosure of Invention
The application provides a negative electrode plate, a secondary battery and a device comprising the secondary battery. The lithium ion battery prepared from the negative electrode plate can give consideration to better first charge and discharge efficiency and multiplying power performance on the premise of higher specific capacity.
The first aspect of the present application provides a negative electrode tab, which includes a negative electrode current collector and a negative electrode material layer disposed on at least one surface of the negative electrode current collector, the negative electrode material layer including a negative electrode active material and a conductive agent, the negative electrode active material including a carbon-based material and a silicon-based material, the conductive agent including carbon nanotubes, and the content of the carbon nanotubes satisfying the following relationship:wherein Cap is the specific capacity of the negative electrode plate, wherein 440 mAh/g is less than or equal to Cap<1000 mAh/g； M CNT Based on the mass of the negative electrode material layer, the mass content of the carbon nano tube is 0.2 per mill or less M CNT <8‰；/>Is the length-diameter ratio of the carbon nano tube, wherein ∈>. Further, M is 0.3 per mill or less CNT Less than or equal to 7.0 per mill. Further, M is 1 ≡m CNT Less than or equal to 5 per mill; and/or 450mAh/g is less than or equal to Cap is less than or equal to 960 mAh/g; and/or. Further, 550 mAh/g is less than or equal to Cap and less than or equal to 650 mAh/g; and/or +.>. Further, the carbon-based material has a mass content of 30% to the maximum based on the mass of the anode active material95%; and/or the mass content of the silicon-based material is 10 to 70% based on the mass of the anode active material. Further, the carbon-based material has a mass content of 40 to 80% based on the mass of the anode active material; and/or the mass content of the silicon-based material is 20 to 50% based on the mass of the anode active material. Further, the conductive agent further comprises carbon black, wherein the mass content of the carbon black and the carbon nanotubes is 0.7-5.0% based on the mass of the anode material layer, and/or the mass content of the anode active material is 90-98% based on the mass of the anode material layer, and/or the anode material layer further comprises a binder, wherein the mass content of the binder is 1.3-5.0% based on the mass of the anode material layer, and/or the silicon-based material is silicon, a silicon alloy, a silicon carbon compound or a silicon oxygen compound, and/or the carbon-based material is at least one of artificial graphite, natural graphite and mesophase carbon fiber. Further, the silicon-based material is SiOx, wherein x is more than or equal to 0.5 and less than or equal to 1.5; and/or the carbon-based material is artificial graphite. Further, the carbon black and the carbon nanotubes are contained in an amount of 0.8 to 2.2% by mass based on the mass of the anode material layer, and/or the anode active material is contained in an amount of 94 to 98% by mass based on the mass of the anode material layer, and/or the binder is contained in an amount of 1.8 to 3.8% by mass based on the mass of the anode material layer.
The second aspect of the present application provides a secondary battery comprising a negative electrode tab including a negative electrode current collector and a negative electrode material layer disposed on at least one surface of the negative electrode current collector, the negative electrode material layer including a negative electrode active material including a carbon-based material and a silicon-based material, and a conductive agent including carbon nanotubes, the content of the carbon nanotubes satisfying the following relationship:wherein Cap is the specific capacity of the negative electrode plate, wherein 440 mAh/g is less than or equal to Cap<1000 mAh/g； M CNT Based on the mass of the negative electrode material layer, the mass content of the carbon nano tube is 0.2 per mill or less M CNT <8‰；/>Is the length-diameter ratio of the carbon nano tube, wherein ∈>. Further, M is 0.3 per mill or less CNT Less than or equal to 7.0 per mill. Further, M is 1 ≡m CNT Less than or equal to 5 per mill; and/or 450mAh/g is less than or equal to Cap is less than or equal to 960 mAh/g; and/or +.>. Further, 550 mAh/g is less than or equal to Cap and less than or equal to 650 mAh/g; and/or +.>. Further, the mass content of the carbon-based material is 30 to 95% based on the mass of the anode active material; and/or the mass content of the silicon-based material is 10 to 70% based on the mass of the anode active material. Further, the carbon-based material has a mass content of 40 to 80% based on the mass of the anode active material; and/or the mass content of the silicon-based material is 20 to 50% based on the mass of the anode active material. Further, the conductive agent further comprises carbon black, wherein the mass content of the carbon black and the carbon nanotubes is 0.7-5.0% based on the mass of the anode material layer, and/or the mass content of the anode active material is 90-98% based on the mass of the anode material layer, and/or the anode material layer further comprises a binder, wherein the mass content of the binder is 1.3-5.0% based on the mass of the anode material layer, and/or the silicon-based material is silicon, a silicon alloy, a silicon carbon compound or a silicon oxygen compound, and/or the carbon-based material is at least one of artificial graphite, natural graphite and mesophase carbon fiber. Further, the silicon-based material is SiOx, wherein x is more than or equal to 0.5 and less than or equal to 1.5; and/or
The carbon-based material is artificial graphite. Further, the carbon black and the carbon nanotubes are contained in an amount of 0.8 to 2.2% by mass based on the mass of the anode material layer, and/or the anode active material is contained in an amount of 94 to 98% by mass based on the mass of the anode material layer, and/or the binder is contained in an amount of 1.8 to 3.8% by mass based on the mass of the anode material layer.
A third aspect of the present application provides an apparatus comprising the above secondary battery.
According to the application, the addition amount of the carbon nano tube, the length-diameter ratio and the specific capacity of the negative electrode are regulated, so that the conductive agent (carbon black and the carbon nano tube) can form an effective short-range and long-range conductive network, and particularly under the condition of higher silicon content, even if the rebound rate of the negative electrode is large, the conductive path can be maintained due to the addition of sufficient carbon nano tube with sufficient length-diameter ratio, so that the obtained negative electrode piece shows better first charge-discharge efficiency and rate capability. In particular, when the content of the carbon nanotube conductive agent in the pole piece is within the range of the present application, a higher discharge capacity and rapid reaction kinetics can be obtained.
Detailed Description
For simplicity, the present application discloses only a few numerical ranges specifically. However, any lower limit may be combined with any upper limit to form a range not explicitly recited; and any lower limit may be combined with any other lower limit to form a range not explicitly recited, and any upper limit may be combined with any other upper limit to form a range not explicitly recited. Furthermore, each separately disclosed point or individual value may itself be combined as a lower limit or upper limit with any other point or individual value or with other lower limit or upper limit to form a range not explicitly recited.
Unless otherwise indicated, terms used in the present application have well-known meanings commonly understood by those skilled in the art. Unless otherwise indicated, the numerical values of the parameters set forth in the present application may be measured by various measurement methods commonly used in the art (e.g., may be tested according to the methods set forth in the examples of the present application).
The list of items to which the term "at least one of," "at least one of," or other similar terms are connected may mean any combination of the listed items. For example, if items a and B are listed, the phrase "at least one of a and B" means only a; only B; or A and B. In another example, if items A, B and C are listed, then the phrase "at least one of A, B and C" means only a; or only B; only C; a and B (excluding C); a and C (excluding B); b and C (excluding A); or A, B and C. Item a may comprise a single component or multiple components. Item B may comprise a single component or multiple components. Item C may comprise a single component or multiple components.
The application is further described below in conjunction with the detailed description. It should be understood that the detailed description is intended by way of illustration only and is not intended to limit the scope of the application.
The carbon black and the carbon nano tube are used as the conductive agent, wherein the carbon black, the carbon nano tube and the adhesive are fully dispersed and uniformly distributed on the surfaces of the active material particles, the conductive agents are mutually communicated to form an electron transmission network, the adhesive is uniformly distributed, and the bonding strength and the mechanical stability of the particle coating are ensured to be high. And the content (addition amount) of the carbon nanotubes satisfies the following relation:wherein M is 0.2 per mill or less CNT <8%o, preferably 0.2%o or less M CNT Less than or equal to 5 per mill. When the content of the carbon nano tube conductive agent in the pole piece is within the range of the application, higher discharge capacity and quick reaction kinetics can be obtained, and when the content of the carbon nano tube conductive agent is too low, the number of electron conductive channels is small, and the high-current charge and discharge are not facilitated, so that the utilization rate of active materials in the electrode is low; the high content of the carbon nanotube conductive agent increases the specific surface area of the negative electrode, improves the possibility of side reaction, reduces the first charge and discharge efficiency of the negative electrode, and also has overhigh cost of the conductive agent, in particular, the conductivity of the carbon nanotube is superior to that of carbon black, so that the specific resistance of the pole piece is slightly reduced when the carbon nanotube is excessive. In addition, due to the high specific surface area of the carbon nanotubes, side reactions caused by the addition of a large amount are also relatively large, and the generation amount of the SEI film is increased, so that the initial charge and discharge efficiency of the lithium ion battery is also relatively low. For example, when the specific capacity of the negative electrode is 450mAh/g, the following is used +.>The optimal addition amount of the carbon nano tube is 0.3 per mill or less than M CNT When the addition amount of the carbon nano tube is less than or equal to 0.4 per mill, the actual discharge capacity is lower and the reaction is dynamicThe mechanical property is insufficient, and when the addition amount of the carbon nano tube is more than 0.4 per mill, the first charge and discharge efficiency is low and the cost is high. In addition, because the conductivity of the carbon nanotubes is better than that of carbon black, when the carbon nanotubes are not contained in the negative electrode material layer of the negative electrode plate, the resistivity of the plate is obviously higher. And after the first-ring lithium intercalation expansion of the negative electrode plate which does not contain the carbon nano tube, the capacity of the first-ring lithium intercalation expansion is limited because of the poor capacity of the long Cheng Daodian carbon black and the electronic bridge cut-off of a part of active materials, so that the first-ring lithium intercalation expansion has low first-time charge and discharge efficiency. In some embodiments, the negative electrode material layer includes a negative electrode active material, carbon black, carbon nanotubes, and a binder.
In some embodiments, the carbon nanotubes are at least one of single-walled carbon nanotubes and multi-walled carbon nanotubes.
In some embodiments, 0.2% M CNT <8 per mill. In some embodiments, M CNT 0.3%, 0.4%, 0.6%, 0.8%, 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2.3%, 2.8%, 3.3%, 3.8%, 4.3%, 4.8%, 5.3%, 5.8%, 6.3%, 6.5%, 6.7%, 7%, 7.3%, 7.6%, 7.9% or any value therebetween. In some embodiments, 0.35% M CNT Less than or equal to 6.3 per mill. In some embodiments, 1 ≡M CNT Less than or equal to 5 per mill. In some embodiments, 0.7% M CNT Less than or equal to 4.2 per mill. In some embodiments, 1.05% M CNT Less than or equal to 3.15 per mill. In some embodiments, 1.58% M CNT Less than or equal to 2.1 per mill. In some embodiments, 0.9% M CNT Less than or equal to 1.2 per mill. In some embodiments, 1.35% M CNT Less than or equal to 1.8 per mill. In some embodiments, 2.7.mu.M CNT Less than or equal to 3.6 per mill. In some embodiments, 5.4% M CNT Less than or equal to 7.2 per mill. In some embodiments, 0.3% M CNT Less than or equal to 0.4 per mill. In some embodiments, 0.45% M CNT Less than or equal to 0.6 per mill. In some embodiments, 1.8.mu.M CNT Less than or equal to 2.4 per mill. In some embodiments, 0.6% M CNT Less than or equal to 0.8 per mill. At the position ofIn some embodiments, 0.9 ≡M CNT Less than or equal to 1.2 per mill. In some embodiments, 3.6.mu.M CNT Less than or equal to 4.8 per mill. In some embodiments, 1.2.mu.M CNT Less than or equal to 1.6 per mill. In some embodiments, 1.8.mu.M CNT Less than or equal to 2.4 per mill. In some embodiments, 2.7.mu.M CNT ≤3.6‰。
In some embodiments, 450 mAh/g.ltoreq.Cap <1000 mAh/g. In some embodiments, cap is 450mAh/g, 475 mAh/g, 525 mAh/g, 575 mAh/g, 625mAh/g, 675 mAh/g, 725 mAh/g, 775 mAh/g, 825mAh/g, 875 mAh/g, 925 mAh/g, 950mAh/g, 975mAh/g, 995 mAh/g, or any value therebetween. In some embodiments, 450 mAh/g.ltoreq.Cap.ltoreq.950 mAh/g. In some embodiments, 550 mAh/g.ltoreq.Cap.ltoreq.650 mAh/g.
In some embodiments, the carbon-based material is present in an amount of 30 to 95% by mass based on the mass of the anode active material. In some embodiments, the carbon-based material is present in an amount of 40 to 80% by mass based on the mass of the negative electrode active material. In some embodiments, the carbon-based material is present in an amount of 40%, 45%, 51%, 52%, 53%, 55%, 57%, 59%, 61%, 65%, 69%, 73%, 77%, 81%, 85%, 90%, 92%, 94% or any value therebetween, based on the mass of the negative electrode active material. In some embodiments, the carbon-based material is present in an amount of 60 to 70% by mass based on the mass of the anode active material.
In some embodiments, the silicon-based material is present in an amount of 10 to 70% by mass based on the mass of the anode active material. In some embodiments, the silicon-based material is present in an amount of 20 to 50% by mass based on the mass of the anode active material. In some embodiments, the silicon-based material is present in an amount of 15%, 20%, 25%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 69% or any value therebetween, based on the mass of the negative electrode active material. In some embodiments, the silicon-based material is present in an amount of 25 to 45% by mass based on the mass of the anode active material.
In some embodiments of the present application, in some embodiments,. In some embodiments, the->500, 600, 700, 800, 1000, 1200, 1400, 1600, 1800, 2100, 2400, 2700, 3000, 3300, 3600, 3900, or any value therebetween. In some embodiments, the->. In some embodiments, the->。
In some embodiments, the carbon black and the carbon nanotubes are present in an amount of 0.7 to 5.0% by mass based on the mass of the negative electrode material layer. In some embodiments, the carbon black and the carbon nanotubes are present in an amount of 0.7%, 1.0%, 1.2%, 1.7%, 2.2%, 2.7%, 3.2%, 3.7%, 4.2%, 4.7%, 4.9% or any value therebetween based on the mass of the negative electrode material layer. In some embodiments, the carbon black and the carbon nanotubes are present in an amount of 0.8 to 2.2% by mass based on the mass of the negative electrode material layer.
In some embodiments, the mass content of the anode active material is 90-98% based on the mass of the anode material layer. In some embodiments, the mass content of the anode active material is 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or any value therebetween, based on the mass of the anode material layer. In some embodiments, the mass content of the anode active material is 94-97% based on the mass of the anode material layer.
In some embodiments, the negative electrode material layer further includes a binder, wherein the mass content of the binder is 1.3 to 5.0% based on the mass of the negative electrode material layer. In some embodiments, wherein the mass content of the binder is 1.3%, 1.5%, 2.0%, 2.2%, 2.4%, 2.6%, 2.8%, 3.0%, 3.2%, 3.4%, 3.6%, 3.8%, 4.0%, 4.2%, 4.4%, 4.6%, 4.8%, 4.9% or any value therebetween based on the mass of the negative electrode material layer. In some embodiments, the mass content of the binder is 1.8-3.8% based on the mass of the negative electrode material layer.
In some embodiments, the anode includes an anode material layer including an anode active material including a silicon-based material, or a mixture of a silicon-based material and at least one material selected from a carbon-based material, a tin-based material, a phosphorus-based material, and metallic lithium.
In some embodiments, the silicon-based material includes at least one of silicon, a silicon alloy, a silicon oxygen compound, and a silicon carbon compound. The silicon oxide compound comprises a carbon-coated silicon oxide compound (SiOx/C) (wherein 0.5.ltoreq.x.ltoreq.1.5, preferably 0.9), siOx (wherein 0.5.ltoreq.x.ltoreq.1.5, preferably 0.9). In some embodiments, the carbon-based material comprises at least one of graphite, soft carbon, hard carbon, carbon nanotubes, and graphene. In some embodiments, the tin-based material includes at least one of tin, tin oxide, and tin alloy. In some embodiments, the phosphorus-based material includes phosphorus and/or a phosphorus complex.
In some embodiments, the negative electrode material layer further includes a binder and a conductive agent. In some embodiments, the binder includes, but is not limited to: polyvinyl alcohol, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, an ethyleneoxy-containing polymer, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, or the like. In some embodiments, the conductive agent includes, but is not limited to: carbon-based materials, metal-based materials, conductive polymers, and mixtures thereof. In some embodiments, the carbon-based material is selected from natural graphite, synthetic graphite, carbon black, acetylene black, ketjen black, carbon fiber, or any combination thereof. In some embodiments, the metal-based material is selected from metal powder, metal fiber, copper, nickel, aluminum, or silver. In some embodiments, the conductive polymer is a polyphenylene derivative.
In some embodiments, the anode further comprises an anode current collector comprising: copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, or any combination thereof. The secondary battery of the present application further includes an electrolyte, which in some embodiments includes a lithium salt and a solvent.
In some embodiments, the secondary battery is a lithium secondary battery or a sodium secondary battery. In some embodiments, lithium secondary batteries include, but are not limited to: lithium metal secondary batteries, lithium ion secondary batteries, lithium polymer secondary batteries, or lithium ion polymer secondary batteries.
In some embodiments, the secondary battery may include an outer package, which may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, or the like. The exterior package of the secondary battery may also be a pouch type pouch, for example. The soft bag can be made of one or more of polypropylene (PP), polybutylene terephthalate (PBT), polybutylene succinate (PBS), etc.
In some embodiments, the shape of the secondary battery is not particularly limited, and may be cylindrical, square, or any other shape.
In some embodiments, the application also provides a battery module. The battery module includes the secondary battery described above. The battery module of the present application employs the above-described secondary battery, and thus has at least the same advantages as the secondary battery. The number of secondary batteries included in the battery module of the present application may be plural, and the specific number may be adjusted according to the application and capacity of the battery module.
In some embodiments, the application further provides a battery pack, which comprises the battery module. The number of battery modules included in the battery pack may be adjusted according to the application and capacity of the battery pack.
The present application also provides an apparatus comprising at least one of the above secondary battery, battery module or battery pack.
In some embodiments, the apparatus includes, but is not limited to: electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric storage systems, and the like. In order to meet the high power and high energy density requirements of the device for the secondary battery, a battery pack or a battery module may be employed.
In other embodiments, the device may be a cell phone, tablet, notebook, or the like. The device is generally required to be light and thin, and a secondary battery can be used as a power source.
Examples and comparative examples
Example 1
Preparation of lithium ion battery (half-cell):
(1) Preparation of negative electrode plate
Artificial graphite (commercially available), siOx (wherein x is more than or equal to 0.5 and less than or equal to 1.5, preferably 0.9 and commercially available), conductive agent Super-P (SP), conductive agent carbon nano-tube, binder sodium carboxymethyl cellulose (CMCNa) and binder styrene-butadiene rubber (SBR) are dispersed in deionized water according to a certain mass ratio, uniformly stirred and coated on Cu foil with the thickness of 6 mu m, and placed in a vacuum drying oven, and vacuum dried at 110 ℃ for 2 h to prepare the negative electrode plate (working electrode). Wherein, the specific capacity Cap of the negative electrode plate is 652 mAh/g.
Based on the mass of the anode material layer, the mass content of the anode active material (wherein the mass ratio of the artificial graphite to the SiOx is 7:3) is 96%, the mass content of the binder is 3.0% (wherein the mass ratio of CMCNa to the SBR is 2:3), the mass content of the conductive agent (including SP and CNT) is 1.0%, wherein the mass content of the carbon nanotube is 1.05%o; average length-diameter ratio of carbon nano tube3000.
(2) Preparation of lithium ion Battery (CR 2016 type button half Battery)
Taking a metal lithium sheet as a counter electrode; in 1M LiPF 6 EC: DEC: DMC (1:1:1) is electrolyte; taking a polypropylene microporous membrane of Celgard2400 model as a diaphragm; the battery of the application is fully filled with Ar 2 Is assembled in a glove box.
Preparing four parallel sample electrode plates according to the mass ratio, detecting resistivity, detecting each sample for 3 times, and taking an average value; after the assembled button half-cell was used, the first charge-discharge efficiency and the rate discharge retention were measured, and the measurement results are shown in table 1.
Example 2
The procedure of example 2 was the same as in example 1, except that in example 2, in step (1), the specific capacity of the negative electrode sheet was 653 mAh/g; based on the mass of the negative electrode material layer, the mass content of the carbon nano tube is 1.58 per mill. Average length-diameter ratio of carbon nano tube2000.
Example 3
The procedure of example 3 was the same as in example 1, except that in example 3, the specific capacity of the negative electrode sheet in step (1) was 647 mAh/g; based on the mass of the negative electrode material layer, the mass content of the carbon nano tube is 3.15 per mill. Average length-diameter ratio of carbon nano tube1000.
Example 4
The procedure of example 4 was the same as in example 1, except that in example 4, the specific capacity of the negative electrode sheet in step (1) was 646 mAh/g; based on the mass of the negative electrode material layer, the mass content of the carbon nano tube is 6.3 per mill. Average length-diameter ratio of carbon nano tube500.
Example 5
The procedure of example 5 was the same as in example 1, except that in example 5, in step (1), the specific capacity Cap of the negative electrode sheet was 453mAh/g (wherein the mass ratio of artificial graphite to SiOx was 8:2), the mass content of carbon nanotubes was 0.35% by mass based on the mass of the negative electrode material layer, and the average value of the aspect ratio of the carbon nanotubes was3000.
Example 6
The procedure of example 6 was the same as in example 5, except that in example 6, the specific capacity of the negative electrode sheet was 452 mAh/g in step (1), and the mass content of the carbon nanotubes was 0.53% based on the mass of the negative electrode material layer. Average length-diameter ratio of carbon nano tube2000.
Example 7
The procedure of example 7 was the same as in example 5, except that in example 7, the specific capacity of the negative electrode sheet in step (1) was 449mAh/g, and the mass content of the carbon nanotubes was 2.1% based on the mass of the negative electrode material layer. Average length-diameter ratio of carbon nano tube500.
Example 8
The procedure of example 8 was the same as that of example 5, except that in example 8, the specific capacity Cap of the negative electrode sheet was 551mAh/g (wherein the mass ratio of artificial graphite to SiOx was 8:2) in step (1), wherein the mass content of carbon nanotubes was 0.7% based on the mass of the negative electrode material layer. Average length-diameter ratio of carbon nano tube3000.
Example 9
The procedure of example 9 was the same as that of example 8, except that in example 9, the specific capacity of the negative electrode sheet in step (1) was 552 mAh/g, and the mass content of the carbon nanotubes was 1.05% based on the mass of the negative electrode material layer. Average length-diameter ratio of carbon nano tube2000.
Example 10
The procedure of example 10 was the same as in example 8, except that in example 10, in step (1), negativeThe specific capacity of the pole piece is 549 mAh/g, and the mass content of the carbon nano tube is 4.2 per mill based on the mass of the negative electrode material layer. Average length-diameter ratio of carbon nano tube500.
Example 11
The procedure of example 11 was the same as in example 1, except that in example 11, the specific capacity Cap of the negative electrode sheet in step (1) was 752 mAh/g (wherein the mass ratio of artificial graphite to SiOx was 6:4), and the mass content of carbon nanotubes was 1.4% based on the mass of the negative electrode material layer. Average length-diameter ratio of carbon nano tube3000.
Example 12
The procedure of example 12 was the same as in example 1, except that in example 12, in step (1), the specific capacity Cap of the negative electrode sheet was 958 mAh/g (wherein the mass ratio of artificial graphite to SiOx was 4:6), and the mass content of carbon nanotubes was 2.1% based on the mass of the negative electrode material layer. Average length-diameter ratio of carbon nano tube3000. The specific capacity of the negative electrode was 958 mAh/g.
Example 13
The procedure of example 13 was the same as in example 1, except that in example 13, in step (1), the specific capacity Cap of the negative electrode sheet was 956 mAh/g (wherein the mass ratio of artificial graphite to SiOx was 4:6), and the mass content of carbon nanotubes was 3.15% based on the mass of the negative electrode material layer. Average length-diameter ratio of carbon nano tube2000.
Comparative example 1
The procedure of comparative example 1 was the same as in example 1, except that in comparative example 1, the specific capacity of the negative electrode sheet was 617 mAh/g in step (1), and no carbon nanotube was added in the negative electrode material layer.
Comparative example 2
The procedure of comparative example 2 was the same as in example 10, except that in comparative example 2, the specific capacity of the negative electrode sheet was 948 mAh/g in step (1), and the mass content of the carbon nanotubes was 15.0% based on the mass of the negative electrode material layer.
Comparative example 3
The procedure of comparative example 3 was the same as in example 4, except that in comparative example 3, no carbon nanotube was added in the anode material layer. The specific capacity of the negative electrode plate is 428 mAh/g.
Comparative example 4
The procedure of comparative example 4 was the same as in example 1, except that in comparative example 4, the specific capacity of the negative electrode tab was 626 mAh/g, and the mass content of the carbon nanotube was 0.1% based on the mass of the negative electrode material layer. Average length-diameter ratio of carbon nano tube3000.
Comparative example 5
The procedure of comparative example 5 was the same as in example 10, except that in comparative example 5, the specific capacity of the negative electrode tab was 717 mAh/g, and the mass content of the carbon nanotube was 0.1% by mass based on the mass of the negative electrode material layer. Average length-diameter ratio of carbon nano tube3000.
Comparative example 6
The procedure of comparative example 6 was the same as in example 1, except that in comparative example 6, in step (1), the specific capacity Cap of the negative electrode sheet was 903mAh/g (wherein the mass ratio of artificial graphite to SiOx was 3:7), and the mass content of carbon nanotubes was 0.1% based on the mass of the negative electrode material layer. Average length-diameter ratio of carbon nano tube3000.
Test method
The model of the performance test equipment of the lithium ion battery is Land CT 2001A, the voltage window is 0.005-1.5V, and the pole piece loading capacity (the weight of the negative electrode active material layer with single-sided unit area) is 8+/-0.05 g/cm 2 。
1. Testing of resistivity of negative electrode sheet
Rolling the middle strip of the whole pole piece to the target compaction density of 1.65+/-0.05 g/cm 3 4 circular pole pieces are cut by adopting a phi 14mm sheet punching machine, and the thickness of each pole piece is measured and recorded. And (3) carrying out resistivity test by using an RM2610 electrode resistance test system, wherein each circular pole piece takes 3 points for measurement, and the average value of 12 points is taken after the measurement is finished.
2. Measurement of first charge and discharge efficiency
The electrochemical performance of the battery was tested by using a blue electric test cabinet, and discharged at 0.1C to 0.005V at 25 ℃ in the voltage range of 0.005V to 1.5V, discharged at 0.05C to 0.005V after 5min of standing, and charged at 0.1C to 1.5V after 5min of standing, wherein the charge-discharge efficiency=first charge capacity/(0.1C discharge specific capacity+0.05C discharge specific capacity) ×100%.
3.2C discharge capacity retention rate (vs. 0.1C)
The electrochemical performance of the cells was tested using a blue electric test cabinet, discharged at 0.1C to 0.005V at 25 ℃ in the voltage range of 0.005V to 1.5V, discharged at 0.05C to 0.005V after 5min of rest, charged at 0.1C to 1.5V, discharged at 2C to 0.005V after 5min of rest, discharged at 0.05C to 0.005V after 5min of rest, and charged at 0.1C to 1.5V after 5min of rest. 2C discharge capacity retention rate (vs. 0.1C) = C discharge specific capacity/0.1C discharge specific capacity 100%.
The results of the electrical property tests of the negative electrode tabs and the lithium ion batteries in examples 1 to 12 and comparative examples 1 to 6 are shown in Table 1.
TABLE 1
As can be seen from Table 1, the first charge and discharge efficiency of the lithium ion battery prepared by the negative electrode plate in the application can reach more than 88.4%, and the 2C discharge capacity retention rate (vs. 0.1C) can reach more than 42.4%. In particular, when the content of the carbon nano tube is 0.35 per mill, the first charge and discharge efficiency can reach more than 92.1 percent, and the 2C discharge capacity retention rate (vs. 0.1C) can reach more than 49.2 percent.

Claims (11)

1. A negative electrode tab comprising a negative electrode current collector and a negative electrode material layer disposed on at least one surface of the negative electrode current collector, the negative electrode material layer comprising a negative electrode active material comprising a mixture of artificial graphite and a silicon-based material, and a conductive agent comprising carbon nanotubes, and the content of the carbon nanotubes satisfying the following relationship:wherein, the method comprises the steps of, wherein,
cap is the specific capacity of the negative pole piece, wherein 452 mAh/g is less than or equal to Cap and less than or equal to 752 mAh/g;
M CNT the mass content of the carbon nano tube is 0.35 per mill or less M based on the mass of the negative electrode material layer CNT <8‰；
Is the length-diameter ratio of the carbon nano tube, wherein ∈>。
2. The negative electrode sheet according to claim 1, wherein 0.35 +.o.m CNT ≤7.0‰。
3. The negative electrode sheet according to claim 1, wherein 1%o is less than or equal to M CNT Less than or equal to 5 per mill; and/or 550 mAh/g is less than or equal to Cap is less than or equal to 650 mAh/g; and/or。
4. The negative electrode tab of claim 3, wherein,。
5. the negative electrode tab according to claim 1, wherein the mass content of the artificial graphite is 30 to 95% based on the mass of the negative electrode active material; and/or
The mass content of the silicon-based material is 10 to 70% based on the mass of the anode active material.
6. The negative electrode tab according to claim 5, wherein the mass content of the artificial graphite is 40 to 80% based on the mass of the negative electrode active material; and/or
The mass content of the silicon-based material is 20 to 50% based on the mass of the anode active material.
7. The negative electrode sheet according to claim 1, wherein the conductive agent further comprises carbon black, wherein the mass content of the carbon black and the carbon nanotubes is 0.7 to 5.0% based on the mass of the negative electrode material layer, and/or
Based on the mass of the anode material layer, the mass content of the anode active material is 90-98%, and/or
The negative electrode material layer further comprises a binder, wherein the mass content of the binder is 1.3-5.0% based on the mass of the negative electrode material layer, and/or
The silicon-based material is silicon, silicon alloy, silicon carbon compound or silicon oxygen compound.
8. The negative electrode tab of claim 7 wherein the silicon-based material is SiOx, wherein 0.5-1.5.
9. The negative electrode sheet according to claim 7, wherein the mass content of the carbon black and the carbon nanotubes is 0.8 to 2.2% based on the mass of the negative electrode material layer, and/or
Based on the mass of the anode material layer, the mass content of the anode active material is 94-98%, and/or
Based on the mass of the negative electrode material layer, the mass content of the binder is 1.8-3.8%.
10. A secondary battery comprising the negative electrode tab of any one of claims 1-9.
11. An apparatus comprising the secondary battery according to claim 10.
CN202310704991.0A 2023-06-14 2023-06-14 Negative electrode sheet, secondary battery and device comprising same Active CN116454284B (en)

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