WO2024040437A1 - 电极极片、电化学装置及用电装置 - Google Patents

电极极片、电化学装置及用电装置 Download PDF

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Publication number
WO2024040437A1
WO2024040437A1 PCT/CN2022/114280 CN2022114280W WO2024040437A1 WO 2024040437 A1 WO2024040437 A1 WO 2024040437A1 CN 2022114280 W CN2022114280 W CN 2022114280W WO 2024040437 A1 WO2024040437 A1 WO 2024040437A1
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active material
material layer
electrode
layer
amphiphilic
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PCT/CN2022/114280
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English (en)
French (fr)
Inventor
刘胜奇
应豆
郭俊
张青文
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宁德新能源科技有限公司
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Priority to CN202280005989.8A priority Critical patent/CN116235319A/zh
Priority to PCT/CN2022/114280 priority patent/WO2024040437A1/zh
Publication of WO2024040437A1 publication Critical patent/WO2024040437A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • 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 belongs to the field of battery technology, and specifically relates to an electrode pole piece, an electrochemical device and an electrical device.
  • Secondary batteries have outstanding characteristics such as high energy density, long cycle life, no pollution, and no memory effect. As a clean energy source, the application of secondary batteries has gradually spread from electronic products to large-scale devices such as electric vehicles to adapt to the sustainable development strategy of the environment and energy. As a result, higher requirements have been placed on the energy density of secondary batteries.
  • Increasing the active material content per unit area is a direct means to increase the energy density of secondary batteries.
  • the active material layer of the electrode piece is easily cracked during the drying process.
  • the purpose of this application is to provide an electrode pole piece, an electrochemical device and an electrical device, aiming to reduce and improve the energy density of the electrode pole piece, thereby increasing the energy density of the secondary battery.
  • a first aspect of the present application provides an electrode pole piece, including: a current collector; and an active material layer located on at least one surface of the current collector.
  • the active material layer includes an active material and an amphiphilic additive, and the amphiphilic additive includes Si-O-C bonds. of amphiphilic compounds.
  • the active material layer includes the above-mentioned amphiphilic compound containing Si-O-C bonds, which can significantly increase the coating weight and yield of the active material layer, thereby improving the performance of the electrode piece of the present application.
  • Energy density and production capacity of secondary batteries is added to the electrode slurry.
  • the polar group in the amphiphilic compound has good affinity with the solvent in the electrode slurry.
  • the non-polar groups have good affinity with solid particles such as conductive agents in the electrode slurry.
  • the solid particles in the electrode slurry can be uniformly and stably dispersed in the solvent, and the solvent of the electrode slurry can also have lower polarity.
  • the electrode slurry can have low surface tension.
  • the electrode slurry has low surface tension, which can increase the leveling of the electrode slurry during the coating process and reduce the stress shrinkage of the electrode slurry coating during the drying process, thereby effectively reducing the cracking of the electrode pole pieces during the drying process. and the rim phenomenon. Therefore, even under high coating weight, the electrode pole piece of the present application is not prone to cracking and has a high yield rate. Therefore, the electrode pole piece of the present application can have high energy density and high productivity, and can be used in secondary batteries to allow secondary batteries to have high energy density and high productivity.
  • the infrared spectrum of the active material layer has a characteristic peak located between 1700 cm ⁇ 1 and 1600 cm ⁇ 1 , a characteristic peak located between 1280 cm ⁇ 1 and 1210 cm ⁇ 1 , and a characteristic peak located between 1200 cm ⁇ 1 and 1000 cm ⁇ 1 .
  • the risk of cracking of the active material layer during the drying process of the electrode sheet can be further reduced, thereby allowing the electrode sheet to have a higher coating weight, thereby allowing the secondary battery using the electrode sheet of the present application to have higher Energy density and higher productivity.
  • the infrared spectrum of the active material layer has two characteristic peaks located between 1200 cm ⁇ 1 and 1000 cm ⁇ 1 .
  • the infrared spectrum of the active material layer has two characteristic peaks located between 1200 cm -1 and 1000 cm -1 , and the amphiphilic additives included in it can further improve the leveling properties of the electrode slurry. This can effectively reduce the bulging phenomenon of the electrode pieces during the drying process, thereby increasing the productivity of the electrode pieces, allowing the electrode pieces to have a higher coating weight, and thereby allowing the application of the second electrode piece of the present application.
  • Secondary batteries have higher energy density and higher production capacity.
  • the amphiphilic additive includes a compound represented by Formula 1, in which R and R' are each independently selected from an alkyl group having 1 to 5 carbon atoms.
  • the amphiphilic additive When the amphiphilic additive has the structure shown in Formula 1, it can significantly reduce the polarity of the solvent in the electrode slurry, thereby reducing the risk of cracking of the active material layer under high coating weight. This allows the active material layer in the electrode plate to have a higher thickness, thereby allowing the secondary battery to have a higher energy density.
  • the active material layer of the electrode plate satisfies: 0.1 ⁇ W ⁇ 0.6, where W% represents the mass percentage of the amphiphilic additive based on the total mass of the active material layer.
  • W% represents the mass percentage of the amphiphilic additive based on the total mass of the active material layer.
  • the mass percentage content of the amphiphilic additive in the active material layer is within the appropriate range, which allows the active material layer to have a high thickness while allowing the active material to have a high mass percentage content in the active material layer. Therefore, the electrode pole pieces can have high energy density.
  • the mass percentage of the amphiphilic additive in the active material layer is within the above-mentioned appropriate range, the electrode piece can also have good electrolyte wetting performance, so that the electrode piece has low internal resistance. This allows secondary batteries using the electrode pole pieces of the present application to have high energy density and good cycle performance.
  • the active material layer of the electrode plate satisfies: 0.01 ⁇ Ws ⁇ 0.2, where Ws% represents the mass percentage of silicon element based on the total mass of the active material layer. If the mass percentage of silicon element in the active material layer is within the above-mentioned appropriate range, it can be considered that the mass percentage of the amphiphilic additive is within the appropriate range. This allows the active material to have a high mass percentage in the active material layer while allowing the active material layer to have a high thickness. Therefore, the electrode pole pieces can have high energy density. In addition, if the mass percentage of the amphiphilic additive is within an appropriate range, the electrode piece can also have good electrolyte wetting properties, so that the electrode piece has low internal resistance. This allows secondary batteries using the electrode pole pieces of the present application to have high energy density and good cycle performance.
  • the active material layer satisfies: 300*W ⁇ H ⁇ 560*W, and 50 ⁇ H ⁇ 280, where H ⁇ m represents the thickness of the single-sided active material layer.
  • W and H meet the above quantitative relationship, the thickness of the active material layer and the content of the amphiphilic additive are appropriate, which can make the active material have a suitable drying gradient from the inside, thereby reducing cracking of the active material layer during the drying process of the electrode plate. While reducing the risk, the electrode pieces are easy to dry.
  • the appropriate thickness of the active material layer can also reduce the degree of polarization of the electrode plates, thereby improving the cycle performance of the secondary battery. Therefore, the electrode pole piece of the present application can have high energy density, high productivity and good cycle performance.
  • the active material layer includes a first layer away from the current collector surface and a second layer close to the current collector surface along its thickness direction.
  • the thickness of the first layer and the second layer is equal, and the active material layer satisfies: 1.1 ⁇ Ws 1 /Ws 2 ⁇ 100, where Ws 1 % represents the mass percentage of silicon element in the first layer based on the total mass of the first layer; Ws 2 % represents the mass percentage of silicon in the second layer based on the total mass of the second layer The mass percentage of silicon element.
  • the active material layer satisfies: 1.1 ⁇ Ws 1 /Ws 2 ⁇ 10.
  • the amphiphilic additive When the amphiphilic additive is included in the active material layer, the amphiphilic additive can move during the drying process of the electrode pole piece, so that Ws 1 and Ws 2 satisfy the above quantitative relationship, that is, the content of the amphiphilic additive in the first layer is high The amount of amphiphilic additive in the second layer.
  • the content of amphiphilic additives in the first layer is higher than the content of amphiphilic additives in the second layer, it can effectively increase the surface tension inside the active material layer during the drying process, thereby easing the problem that the surface of the active material layer dries first and the interior dries later. Cracking caused by dryness.
  • Ws 1 and Ws 2 are within the above-mentioned appropriate range, which can make the content of the amphiphilic additives remaining on the surface of the electrode plate appropriate, thereby reducing the risk of cracking of the active material layer and facilitating the smooth progress of processes such as rolling. This enables the electrode pole piece to have high energy density and high productivity.
  • the active material layer also includes a conductive agent, the conductive agent includes conductive carbon black secondary particles, and the cross-section of the active material layer satisfies: within every 0.01 mm 2 , the cross-sectional area of the conductive carbon black secondary particles is ⁇ 5 ⁇ m 2 Quantity ⁇ 2.
  • the cross-section of the active material layer satisfies: within every 0.01mm2 , the number of conductive carbon black secondary particles with a cross-sectional area of 0.1 ⁇ m2 to 1 ⁇ m2 is ⁇ 4.
  • the distribution of the conductive carbon black secondary particles in the cross section of the active material layer can meet the above conditions. .
  • the distribution of conductive carbon black secondary particles in the cross-section of the active material layer meets the above conditions. It can be considered that the amphiphilic additive can significantly reduce the risk of cracking of the active material layer, and the electrode pole piece can have good electronic conductivity. Therefore, the electrode pole piece of the present application is applied to a secondary battery and can improve the energy density and cycle performance of the secondary battery.
  • a second aspect of the application provides an electrochemical device, including a positive electrode piece and a negative electrode piece, where the positive electrode piece and/or the negative electrode piece are selected from the electrode pieces of the first aspect of the application.
  • the electrochemical device of the present application includes the electrode pole piece of the first aspect of the present application, and can have high energy density and high productivity.
  • the positive electrode piece and the negative electrode piece are selected from the electrode pieces of the first aspect of the application, and the electrochemical device satisfies 0.1 ⁇ Ws 3 /Ws 4 ⁇ 10, where Ws 3 % represents based on the positive active material layer
  • the total mass is the mass percentage of silicon element in the positive active material layer
  • Ws 4 % represents the mass percentage of silicon element in the negative active material layer based on the total mass of the negative active material layer.
  • Both the positive active material layer and the negative active material layer include amphiphilic additives, and make Ws 3 and Ws 4 meet the above quantitative relationship, which can effectively reduce the surface tension inside the active material layer during the drying process of the electrode pole piece, thereby relieving the active material The cracking phenomenon caused by the surface drying first and the interior drying later.
  • a third aspect of the present application provides an electrical device, which includes the electrochemical device of the second aspect of the present application.
  • the electrical device of the present application includes the electrochemical device of the present application, and therefore has at least the same advantages as the electrochemical device.
  • Figure 1 is a schematic diagram of an electrochemical device according to an embodiment of the present application.
  • FIG. 2 is an exploded view of the electrochemical device shown in FIG. 1 .
  • Figure 3 is a schematic diagram of an electrical device according to an embodiment of the present application.
  • Figure 4 is an infrared spectrum chart of Example 1.
  • Figure 5 is a test diagram of the distribution of conductive carbon black secondary particles in the cross section of the active material layer.
  • Figure 6 is a test diagram of the distribution of conductive carbon black secondary particles in the cross section of the active material layer.
  • Figure 7 is a test diagram of the distribution of conductive carbon black secondary particles in the cross section of the active material layer.
  • Figure 8 is a test diagram of the distribution of conductive carbon black secondary particles in the cross section of the active material layer.
  • any lower limit can be combined with any upper limit to form an unexpressed range; and any lower limit can be combined with other lower limits to form an unexpressed range, and likewise any upper limit can be combined with any other upper limit to form an unexpressed range.
  • every point or individual value between the endpoints of a range is included in the range.
  • each point or single value may serve as a lower or upper limit on its own in combination with any other point or single value or with other lower or upper limits to form a range not expressly recited.
  • a term may refer to a variation of less than or equal to ⁇ 10% of the stated numerical value, such as less than or equal to ⁇ 5%, less than or equal to ⁇ 4%, less than or equal to ⁇ 3%, Less than or equal to ⁇ 2%, less than or equal to ⁇ 1%, less than or equal to ⁇ 0.5%, less than or equal to ⁇ 0.1%, or less than or equal to ⁇ 0.05%. Additionally, quantities, ratios, and other numerical values are sometimes presented herein in range format.
  • a list of items connected by the terms “at least one of,” “at least one of,” “at least one of,” or other similar terms 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 the 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 all of A, B and C.
  • Item A may contain a single component or multiple components.
  • Item B may contain a single component or multiple components.
  • Item C may contain a single component or multiple components.
  • the active material layer of the electrode piece is easily cracked during the drying process.
  • the surface tension of the electrode slurry is relatively large due to the particle nanonization effect. Therefore, during the drying process of the electrode pole piece, the internal stress of the active material layer is uneven, which is prone to problems such as cracking and bulging, thus limiting the thickness and productivity of the active material layer.
  • the inventor has provided an electrode plate, an electrochemical device and an electrical device after in-depth thinking and extensive experiments.
  • the electrode plate is used in electrochemistry and can enable the electrochemical device to have high energy density and high power consumption. production capacity.
  • a first aspect of the present application provides an electrode pole piece, including: a current collector; and an active material layer located on at least one surface of the current collector.
  • the active material layer includes an active material and an amphiphilic additive.
  • the amphiphilic additive includes Amphiphilic compounds containing Si-O-C bonds.
  • the electrode piece of the present application can be a positive electrode piece or a negative electrode piece.
  • the active material layer may be a positive active material layer; correspondingly, when the electrode piece is a negative electrode piece, the negative active material layer may be a negative active material layer.
  • the above-mentioned amphiphilic compound containing a Si-O-C bond may be a compound that contains both a polar group and a non-polar group in the molecule and contains a Si-O-C bond.
  • the substances used to form the active material layer include the above-mentioned amphiphilic compound containing Si-OC bonds, which can significantly increase the coating weight and yield of the active material layer. Therefore, The energy density and production capacity of secondary batteries using the electrode pole pieces of the present application can be improved.
  • the single-sided coating weight of the active material layer of the electrode plate can reach more than 250 mg/1540.25mm 2 , or even more than 500 mg/1540.25mm 2 .
  • the above-mentioned amphiphilic compound containing Si-O-C bonds is added to the electrode slurry, and the polar group in the amphiphilic compound has good properties with the solvent in the electrode slurry.
  • the non-polar groups have good affinity with solid particles such as conductive agents in the electrode slurry. Therefore, the solid particles in the electrode slurry can be uniformly and stably dispersed in the solvent, and the solvent of the electrode slurry can also have lower polarity. Thereby, the electrode slurry can have low surface tension.
  • the electrode slurry has low surface tension, which can increase the leveling of the electrode slurry during the coating process and reduce the stress shrinkage of the electrode slurry coating during the drying process, thereby effectively reducing the cracking of the electrode pole pieces during the drying process. and the rim phenomenon. Therefore, even under high coating weight, the electrode pole piece of the present application is not prone to cracking and has a high yield rate. Therefore, the electrode pole piece of the present application can have high energy density and high productivity, and can be used in secondary batteries to allow secondary batteries to have high energy density and high productivity.
  • the infrared spectrum of the active material layer may have a characteristic peak located at 1700 cm -1 to 1600 cm -1 , a characteristic peak located at 1280 cm -1 to 1210 cm -1 , and a characteristic peak located at 1200 cm -1 to 1000 cm -1 peak.
  • the characteristic peaks located between 1280cm -1 and 1210cm -1 are characteristic peaks that can characterize Si-C bonds.
  • Peaks, the characteristic peaks located between 1200cm -1 and 1000cm -1 are characteristic peaks that can characterize Si-OC bonds.
  • the above characteristic peaks may be characteristic peaks characterizing amphiphilic additives.
  • the risk of cracking of the active material layer during the drying process of the electrode sheet can be further reduced, thereby allowing the electrode sheet to have a higher coating weight, thereby allowing the secondary battery using the electrode sheet of the present application to have higher Energy density and higher productivity.
  • the infrared spectrum of the active material layer may have two characteristic peaks located between 1200 cm ⁇ 1 and 1000 cm ⁇ 1 .
  • the infrared spectrum of the active material layer has two characteristic peaks located between 1200 cm -1 and 1000 cm -1 , and the amphiphilic additives included can further improve the leveling properties of the electrode slurry. This can effectively reduce the bulging phenomenon of the electrode pieces during the drying process, thereby increasing the productivity of the electrode pieces, allowing the electrode pieces to have a higher coating weight, and thereby allowing the application of the second electrode piece of the present application.
  • Secondary batteries have higher energy density and higher production capacity.
  • the amphiphilic additive may include a compound represented by Formula 1.
  • R and R' can each be independently selected from an alkyl group with 1 to 5 carbon atoms.
  • the alkyl group with 1 to 5 carbon atoms can be methyl, ethyl, propyl, butyl. , Pentyl, among which there is an isomer alkyl group, it can also be its isomer.
  • propyl group can be n-propyl and isopropyl
  • butyl can be n-butyl, isobutyl, sec-butyl, tert. butyl. .
  • amphiphilic additives including alkoxy groups can effectively reduce the polarity of the solvent in the electrode slurry.
  • the amphiphilic additive has the structure shown in Formula 1, it can significantly reduce the polarity of the solvent in the electrode slurry, thereby reducing the risk of cracking of the active material layer under high coating weight. This allows the active material layer in the electrode plate to have a higher thickness, thereby allowing the secondary battery to have a higher energy density.
  • the active material layer of the electrode pole piece can satisfy: 0.1 ⁇ W ⁇ 0.6, where W% represents the mass percentage of the amphiphilic additive based on the total mass of the active material layer.
  • W% can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6% or within the range of any of the above values.
  • the mass percentage of the amphiphilic additive in the active material layer is within the above-mentioned suitable range, which can allow the active material layer to have a high thickness while allowing the active material to be in the active material layer. It has high quality content. Therefore, the electrode pole pieces can have high energy density.
  • the electrode piece can also have good electrolyte wetting performance, so that the electrode piece has low internal resistance. This allows secondary batteries using the electrode pole pieces of the present application to have high energy density and good cycle performance.
  • the active material layer of the electrode pole piece can satisfy: 0.01 ⁇ Ws ⁇ 0.2, where Ws% represents the mass percentage of silicon element based on the total mass of the active material layer.
  • W S can be 0.01, 0.05, 0.08, 0.1, 0.12, 0.15, 0.18, 0.2 or within the range of any of the above values.
  • the silicon element may be the silicon element contained in the amphiphilic additive.
  • the mass percentage content of the silicon element in the active material layer is within the above-mentioned appropriate range, and it can be considered that the mass percentage content of the amphiphilic additive is within the appropriate range. This allows the active material to have a high mass percentage in the active material layer while allowing the active material layer to have a high thickness. Therefore, the electrode pole pieces can have high energy density.
  • the electrode piece can also have good electrolyte wetting properties, so that the electrode piece has low internal resistance. This allows secondary batteries using the electrode pole pieces of the present application to have high energy density and good cycle performance.
  • the active material layer may satisfy: 300*W ⁇ H ⁇ 560*W, and 50 ⁇ H ⁇ 280, where W% represents the total mass of the amphiphilic additive based on the total mass of the active material layer. Mass percentage; H ⁇ m represents the thickness of the active material layer on one side.
  • the thickness of the active material layer and the content of the amphiphilic additive are appropriate, which can make the active material have a suitable drying gradient from the inside, thereby reducing cracking of the active material layer during the drying process of the electrode plate. While reducing the risk, the electrode pieces are easy to dry.
  • the appropriate thickness of the active material layer can also reduce the degree of polarization of the electrode plates, thereby improving the cycle performance of the secondary battery. Therefore, the electrode pole piece of the present application can have high energy density, high productivity and good cycle performance.
  • the active material layer includes a first layer away from the current collector surface and a second layer close to the current collector surface along its thickness direction, and the first layer and the second layer are The thickness is equal, and the active material layer can satisfy: 1.1 ⁇ Ws 1 /Ws 2 ⁇ 100, where Ws 1 % represents the mass percentage of silicon element in the first layer based on the total mass of the first layer ; Ws 2 % represents the mass percentage of silicon element in the second layer based on the total mass of the second layer.
  • the active material layer may satisfy: 1.1 ⁇ Ws 1 /Ws 2 ⁇ 10.
  • first layer and the second layer are only different parts of the active material layer in the thickness direction, and the first layer and the second layer are not separate structures.
  • the first layer and the second layer may be determined by measuring the thickness of the active material layer to determine a central plane of the active material layer, the distance between the central plane and the surface of the active material layer away from the current collector being equal to The distance between the central plane and the surface of the active material layer close to the current collector; the portion between the central plane and the surface of the active material layer away from the current collector is determined as the first layer, and the distance from the central plane to the active material layer is The portion between the surfaces of the material layer close to the current collector is defined as the second layer.
  • the amphiphilic additive when included in the active material layer, the amphiphilic additive can move during the drying process of the electrode pole piece, so that Ws 1 and Ws 2 satisfy the above quantitative relationship, That is, the content of amphiphilic additives in the first layer is higher than the content of amphiphilic additives in the second layer.
  • the content of amphiphilic additives in the first layer is higher than the content of amphiphilic additives in the second layer, it can effectively increase the surface tension inside the active material layer during the drying process, thereby easing the problem that the surface of the active material layer dries first and the interior dries later. Cracking caused by dryness.
  • Ws 1 and Ws 2 are within the above-mentioned appropriate ranges, which can make the content of the residual amphiphilic additive on the surface of the electrode plate appropriate, thereby reducing the risk of cracking of the active material layer. , which is conducive to the smooth progress of processes such as rolling, thereby enabling the electrode pole pieces to have high energy density and high productivity.
  • the active material layer may also include a conductive agent, the conductive agent may include conductive carbon black secondary particles, and the cross-section of the active material layer may satisfy: within every 0.01 mm2 , the cross-sectional area is ⁇ 5 ⁇ m.
  • the number of the conductive carbon black secondary particles of 2 is ⁇ 2.
  • the cross-section of the active material layer can satisfy: the number of conductive carbon black secondary particles with a cross-sectional area of 0.1 ⁇ m 2 to 1 ⁇ m 2 within every 0.01 mm 2 is ⁇ 4.
  • the above-mentioned cross-section may include a cross-section along the length direction of the active material layer or a cross-section along the width direction of the active material layer.
  • the amphiphilic additive when the amphiphilic additive is included in the electrode slurry, the conductive carbon black secondary particles in the electrode slurry can be evenly mixed and dispersed. Therefore, the conductive carbon black secondary particles are in the active state.
  • the distribution of the cross-section of the material layer can meet the above conditions.
  • the distribution of conductive carbon black secondary particles in the cross-section of the active material layer meets the above conditions. It can be considered that the amphiphilic additive can significantly reduce the risk of cracking of the active material layer, and the electrode pole piece can have good electronic conductivity. Therefore, the electrode pole piece of the present application is applied to a secondary battery and can improve the energy density and cycle performance of the secondary battery.
  • the electrode piece may be a negative electrode piece
  • the current collector may be a negative electrode current collector
  • the active material layer may be a negative active material layer
  • Metal foil or porous metal plate may be used, for example, foil or porous plate using metals such as copper, nickel, titanium, iron or alloys thereof.
  • the negative electrode current collector is copper foil.
  • the negative electrode current collector has two surfaces opposite in its thickness direction, and the negative electrode active material layer can be disposed on one surface of the negative electrode current collector, or can be disposed on both surfaces of the negative electrode current collector simultaneously.
  • the negative electrode current collector has two surfaces opposite in its own thickness direction, and the negative electrode active material layer is disposed on any one or both surfaces of the opposite sides of the negative electrode current collector.
  • negative active material is not subject to specific restrictions and can be selected according to needs.
  • other negative active materials include, but are not limited to, natural graphite, artificial graphite, mesophase microcarbon beads (MCMB), hard carbon, soft carbon, silicon, silicon-carbon composite, SiO, Li-Sn alloy, Li-Sn -O alloy, Sn, SnO, SnO 2 , spinel structure Li 4 Ti 5 O 12 , and Li-Al alloy.
  • the negative active material layer optionally further includes a binder.
  • a binder includes, but are not limited to, styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl butyral (PVB), water-based acrylic resin (Water- Based on acrylic resin) and at least one of carboxymethylcellulose.
  • SBR styrene-butadiene rubber
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • PVB polyvinyl butyral
  • water-based acrylic resin Water- Based on acrylic resin
  • the negative active material layer optionally further includes a conductive agent.
  • a conductive agent includes, but is not limited to, at least one of conductive graphite, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the negative active material layer optionally also includes other auxiliaries, such as thickeners (such as sodium carboxymethyl cellulose (CMC-Na)) and the like.
  • auxiliaries such as thickeners (such as sodium carboxymethyl cellulose (CMC-Na)) and the like.
  • the negative electrode piece in this application can be prepared according to conventional methods in this field.
  • the negative active material, conductive agent, binder and thickener are dispersed in a solvent, which can be N-methylpyrrolidone (NMP) or deionized water, to form a uniform negative electrode slurry, and the negative electrode slurry is coated On the negative electrode current collector, the negative electrode piece is obtained through processes such as drying and cold pressing.
  • NMP N-methylpyrrolidone
  • deionized water deionized water
  • the electrode piece may be a positive electrode piece
  • the current collector may be a positive current collector
  • the active material layer may be a positive active material layer
  • the positive electrode current collector can use metal foil or composite current collector.
  • a metal foil aluminum foil can be used as the positive electrode current collector.
  • the composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer.
  • the metal material may be selected from one or more of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy.
  • the polymer material base layer may be selected from polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.
  • the positive electrode current collector has two surfaces opposite in its thickness direction, and the positive electrode active material layer may be disposed on one surface of the positive electrode current collector, or may be disposed on both surfaces of the positive electrode current collector.
  • the positive electrode current collector has two surfaces opposite in its own thickness direction, and the positive electrode active material layer is disposed on any one or both surfaces of the opposite sides of the positive electrode current collector.
  • the cathode active material may include one or more of lithium transition metal oxides, lithium-containing phosphates with an olivine structure, and their respective modified compounds.
  • the above-mentioned modified compounds of each positive electrode active material may be doping modification, surface coating modification, or doping and surface coating modification of the positive electrode active material.
  • lithium transition metal oxides may include lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, One or more of lithium nickel cobalt aluminum oxide and its modified compounds.
  • the lithium-containing phosphate with an olivine structure may include lithium iron phosphate, a composite of lithium iron phosphate and carbon, a lithium manganese phosphate, a composite of lithium manganese phosphate and carbon, a lithium manganese iron phosphate, a lithium manganese iron phosphate and carbon One or more of the composite materials and their modified compounds. Only one type of these positive electrode active materials may be used alone, or two or more types may be used in combination.
  • the positive active material layer optionally further includes a binder.
  • the specific type of binder is not subject to specific restrictions and can be selected according to needs.
  • binders include, but are not limited to, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene At least one of ethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer and fluorine-containing acrylate resin.
  • the positive active material layer optionally further includes a conductive agent.
  • a conductive agent includes, but is not limited to, at least one of conductive graphite, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the positive electrode piece in this application can be prepared according to conventional methods in this field.
  • the cathode active material layer is usually formed by coating the cathode slurry on the cathode current collector, drying, and cold pressing.
  • the cathode slurry is usually formed by dispersing the cathode active material, optional conductive agent, optional binder and any other components in a solvent and stirring evenly.
  • the solvent may be N-methylpyrrolidone (NMP), but is not limited thereto.
  • each electrode active material layer refers to the parameter range of the single-sided electrode active material layer.
  • the electrode active material layer is disposed on both surfaces of the negative electrode current collector, if the parameters of the electrode active material layer on any one of the surfaces meet the requirements of this application, it is deemed to fall within the protection scope of this application.
  • the electrode pole piece in this application does not exclude other additional functional layers in addition to the active material layer.
  • the electrode pole piece of the present application also includes a conductive undercoat layer (for example, composed of a conductive agent and a binder) sandwiched between the current collector and the active material layer and disposed on the surface of the current collector.
  • the electrode piece of the present application further includes a protective layer covering the surface of the active material layer.
  • infrared spectra can be measured by methods and instruments known in the art. For example, it can be obtained by testing with an infrared spectrometer. Specifically, after the battery is discharged to 0% SOC, the battery can be disassembled to obtain the electrode piece; the electrode piece can be naturally dried in a fume hood; and then a blade can be used to remove the electrode piece. Scrape off the active material layer of the tablet, soak it in NMP, centrifuge and filter, take the filtered clear liquid, heat and evaporate the clear liquid to ⁇ 5mL, refer to the test method of GB/T 21186-2007, and test to obtain the active material layer infrared spectrum.
  • the mass percentage of silicon element in the active material layer can be tested and obtained by the following method: after the battery is discharged to 0% SOC, the electrode piece is disassembled; the electrode piece is naturally placed in a fume hood. Let dry; then use a blade to scrape off the powder of the upper layer (first layer) and lower layer (second layer) respectively, weigh the mass m 1 of the upper layer powder and the mass m 2 of the lower layer powder respectively, and use ICP to test the silicon element content , respectively obtain WS1 and WS2 .
  • the distribution of conductive carbon black secondary particles in the cross-section of the active material layer can be tested by the following method: randomly select areas of the cold-pressed electrode poles, perform cross-section polishing, and take back-scattered SEM images Figure (BS-SEM), the magnification is 1000 times; use IMAGE J to image process the BS-SEM, adjust the appropriate contrast until the outline of the conductive carbon black secondary particles can be clearly seen; use software to count each section The area of the conductive carbon black secondary particles is calculated to obtain the distribution of the conductive carbon black secondary particles in the cross section of the active material layer.
  • BS-SEM back-scattered SEM images Figure
  • electrode active material layer or electrode active material particles can be performed by sampling and testing during the battery preparation process, or by sampling and testing from the prepared secondary battery.
  • the sample can be sampled according to the following steps S10-S30.
  • step S20 Bake the electrode piece dried in step S10 at a certain temperature and time (for example, 400°C, 2 hours). Select an area in the baked electrode piece to sample the electrode active material (you can choose blade scraper powder sampling).
  • step S30 sieve the electrode active material collected in step S20 (for example, sieve with a 200-mesh screen) to finally obtain a sample that can be used to test the parameters of each electrode active material mentioned above in this application.
  • a second aspect of the present application provides an electrochemical device, including any device in which an electrochemical reaction occurs to convert chemical energy into electrical energy.
  • the lithium secondary battery includes a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery or a lithium ion polymer secondary battery.
  • the electrochemical device of the present application includes electrode pole pieces, isolation membranes and electrolytes.
  • the electrode pieces may include positive electrode pieces and negative electrode pieces.
  • the positive electrode piece, the negative electrode piece and the separator film can be made into an electrode assembly through a winding process or a lamination process.
  • the electrochemical device of the present application also includes an outer package for packaging the electrode assembly and the electrolyte.
  • the outer packaging can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc., or a soft bag, such as a bag-type soft bag.
  • the soft bag may be made of plastic, such as at least one of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).
  • PP polypropylene
  • PBT polybutylene terephthalate
  • PBS polybutylene succinate
  • FIG. 1 shows an electrochemical device 5 with a square structure as an example.
  • the outer package may include a housing 51 and a top cover assembly 53 .
  • the housing 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose a receiving cavity.
  • the housing 51 has an opening communicating with the accommodating cavity, and the top cover assembly 53 can cover the opening to close the accommodating cavity.
  • the positive electrode piece, the negative electrode piece and the isolation film can be formed into the electrode assembly 52 through a winding process or a lamination process.
  • the electrode assembly 52 is packaged in the containing cavity.
  • the electrolyte soaks into the electrode assembly 52 .
  • the number of electrode assemblies 52 included in the electrochemical device 5 can be one or more, and those skilled in the art can select according to specific actual needs.
  • the positive electrode piece and/or the negative electrode piece used are the electrode pieces of the first aspect of the present application.
  • both the positive electrode piece and the negative electrode piece are the electrode pieces of the first aspect of the application, and the electrochemical device can satisfy 0.1 ⁇ Ws 3 /Ws 4 ⁇ 10, where Ws 3 % represents based on the positive electrode The total mass of the active material layer, the mass percentage of silicon element in the positive active material layer; Ws 4 % represents the mass percentage of silicon element in the negative active material layer based on the total mass of the negative active material layer.
  • Both the positive active material layer and the negative active material layer include amphiphilic additives, and make Ws 3 and Ws 4 meet the above quantitative relationship, which can effectively reduce the surface tension inside the active material layer during the drying process of the electrode pole piece, thereby relieving the active material The cracking phenomenon caused by the surface drying first and the interior drying later.
  • Ws 3 /Ws 4 >10 it means that Ws 4 is small, the amphiphilic additive content in the negative active material layer is low, and the effect on reducing the cracking of the negative electrode piece is limited; when Ws 3 /Ws 4 ⁇ 0.1, it means The larger the Ws 4 , the higher the amphiphilic additive content, which may affect the drying of the pole piece and cause the roller to stick.
  • the value of Ws 3 /Ws 4 is within the above-mentioned appropriate range, which can reduce the cracking degree of the positive electrode piece and the negative electrode piece and at the same time make the positive electrode piece and the negative electrode piece have good processing performance.
  • the electrolyte plays a role in conducting active ions between the positive electrode piece and the negative electrode piece.
  • the electrolyte solution that can be used in the electrochemical device of the present application can be an electrolyte solution known in the art.
  • the electrolyte solution includes an organic solvent, a lithium salt and optional additives.
  • organic solvent a lithium salt and optional additives.
  • the types of the organic solvent, lithium salt and additives are not specifically limited and can be selected according to needs.
  • the lithium salts include, but are not limited to, LiPF 6 (lithium hexafluorophosphate), LiBF 4 (lithium tetrafluoroborate), LiClO 4 (lithium perchlorate), LiFSI (lithium bisfluorosulfonimide) ), LiTFSI (lithium bistrifluoromethanesulfonimide), LiTFS (lithium trifluoromethanesulfonate), LiDFOB (lithium difluoromethanesulfonate), LiBOB (lithium difluoromethanesulfonate), LiPO 2 F 2 (difluorophosphoric acid Lithium), LiDFOP (lithium difluorodioxalate phosphate) and LiTFOP (lithium tetrafluorooxalate phosphate).
  • LiPF 6 lithium hexafluorophosphate
  • LiBF 4 lithium tetrafluoroborate
  • LiClO 4 lithium perchlorate
  • LiFSI
  • the organic solvent includes, but is not limited to, ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), carbonic acid Dimethyl ester (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate Ester (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), Methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS)
  • EC ethylene carbon
  • the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain properties of the battery, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance. wait.
  • the additives include, but are not limited to, fluoroethylene carbonate (FEC), vinylene carbonate (VC), vinyl ethylene carbonate (VEC), vinyl sulfate (DTD), propylene sulfate, vinyl sulfite Ester (ES), 1,3-propene sultone (PS), 1,3-propene sultone (PST), sulfonate cyclic quaternary ammonium salt, succinic anhydride, succinonitrile (SN) , at least one of adiponitrile (AND), tris(trimethylsilane)phosphate (TMSP), and tris(trimethylsilane)borate (TMSB).
  • FEC fluoroethylene carbonate
  • VC vinylene carbonate
  • VEC vinyl ethylene carbonate
  • DTD vinyl sulfate
  • ES vinyl sulfite Ester
  • PS 1,3-propene sultone
  • PST 1,3-propene sultone
  • the electrolyte solution can be prepared according to conventional methods in the art.
  • the organic solvent, lithium salt, and optional additives can be mixed evenly to obtain an electrolyte.
  • the materials There is no particular restriction on the order in which the materials are added. For example, add lithium salt and optional additives to the organic solvent and mix evenly to obtain an electrolyte; or add lithium salt to the organic solvent first, and then add the optional additives.
  • the additives are added to the organic solvent and mixed evenly to obtain an electrolyte.
  • the isolation film is placed between the positive electrode piece and the negative electrode piece. It mainly prevents the positive and negative electrodes from short-circuiting and allows active ions to pass through.
  • isolation membrane There is no particular restriction on the type of isolation membrane in this application. Any well-known porous structure isolation membrane with good chemical stability and mechanical stability can be used.
  • the material of the isolation membrane can be selected from one or more of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride, but is not limited to these.
  • the isolation film can be a single-layer film or a multi-layer composite film. When the isolation film is a multi-layer composite film, the materials of each layer may be the same or different. In some embodiments, a ceramic coating or a metal oxide coating can also be provided on the isolation film.
  • the third aspect of the present application provides an electrical device, which includes the electrochemical device of the second aspect of the present application.
  • the powered device may include, but is not limited to, a notebook computer, a pen-input computer, a mobile computer, an e-book player, a portable telephone, a portable fax machine, a portable copier, a portable printer, a stereo headset, Video recorders, LCD TVs, 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 appliances, toys, game consoles, clocks, power tools, flashlights, cameras, large household batteries and lithium-ion capacitors, etc.
  • Figure 3 is an electrical device as an example.
  • the electric device can be a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, etc.
  • the positive electrode active material lithium iron phosphate, the binder PVDF, and the conductive agent carbon black according to the mass ratio of 96:2:2, add an appropriate amount of solvent NMP, stir thoroughly, add additives, and mix evenly to obtain the positive electrode slurry;
  • the positive electrode slurry is evenly coated on both surfaces of the positive electrode current collector aluminum foil; then dried in a 120°C oven, cold pressed, cut, etc., to obtain positive electrode sheets.
  • W represents the total mass of the solid components in the positive electrode slurry, and the mass of the additives. content
  • Ws% represents the mass percentage of silicon element in the cathode active material layer based on the total mass of the cathode active material layer
  • Ws 1 % represents the total mass of the first layer of the cathode active material layer, the silicon in the first layer
  • the mass percentage of the element, Ws 2 % represents the total mass of the second layer based on the cathode active material layer, and the mass percentage of the silicon element in the second layer
  • H ⁇ m represents the thickness of the cathode active material layer.
  • EC ethylene carbonate
  • EMC ethyl methyl carbonate
  • DEC diethyl carbonate
  • FEC fluoroethylene carbonate
  • concentration of LiPF 6 is 1 mol/L
  • mass percentage of fluorinated ethylene carbonate is 5% based on the total mass of the electrolyte.
  • a porous polypropylene membrane (from Celgard Company) with a thickness of 14 ⁇ m was used as the isolation membrane.
  • Electrode assembly Stack the positive electrode sheets, isolation film, and negative electrode sheets in order and wind them to obtain an electrode assembly. Put the electrode assembly into the outer packaging, add the above-mentioned electrolyte, and after processes such as packaging, standing, forming, and shaping, the secondary Battery.
  • W'% represents the total mass of the solid components in the negative electrode slurry, and the Mass percentage
  • W's% represents the mass percentage of silicon element in the negative active material layer based on the total mass of the negative active material layer
  • W's 1 % represents the total mass of the first layer based on the negative active material layer, the first layer
  • the mass percentage of silicon element in W's 2 % represents the total mass of the second layer based on the negative active material layer, and the mass percentage of silicon element in the second layer
  • H' represents the thickness of the negative active material layer.
  • the positive electrode active material lithium iron phosphate, the binder PVDF, and the conductive agent carbon black according to the mass ratio of 96:2:2, add an appropriate amount of solvent NMP, and stir thoroughly to obtain the positive electrode slurry; apply the positive electrode slurry evenly On both surfaces of the positive electrode current collector aluminum foil; and then dried in a 120°C oven, cold pressed, cut, etc. to obtain the positive electrode piece.
  • Examples 4-1 to 4-2 the preparation processes of the electrolyte, separator and secondary battery are the same as those in Examples 1-1 to 1-7.
  • the positive electrode active material lithium iron phosphate, the binder PVDF, and the conductive agent carbon black according to the mass ratio of 96:2:2, add an appropriate amount of solvent NMP, stir thoroughly, add additives, and mix evenly to obtain the positive electrode slurry;
  • the positive electrode slurry is evenly coated on both surfaces of the positive electrode current collector aluminum foil; then dried in a 120°C oven, cold pressed, cut, etc., to obtain positive electrode sheets.
  • Examples 5-1 to 5-2 the preparation processes of the electrolyte, separator and secondary battery are the same as those in Examples 1-1 to 1-7.
  • Example 5-1 to 5-2 The preparation parameters of Examples 5-1 to 5-2 are shown in Table 1-5.
  • Table 1-5 W, W', Ws, W's, Ws 1 , W's 1 , Ws 2 , W's 2 , H, H 'respectively as defined previously.
  • Example 5-1 Based on the preparation process of Example 5-1 to Example 5-2, as shown in Table 1-5, the types of additives were adjusted to prepare the secondary battery of Comparative Example 5-1.
  • Sampling method After discharging the battery to 0% SOC, disassemble it; take the corresponding electrode pieces and dry them naturally in a fume hood; then use a blade to scrape the upper layer (first layer) and lower layer powder (second layer) respectively. After downloading, use ICP to test the silicon content, and obtain Ws 1 and Ws 2 , or W's 1 and W's 2 respectively.
  • Test method refer to GB/T 21186-2007
  • Sampling method Disassemble the battery after discharging it to 0% SOC. Take the electrode pieces and dry them naturally in a fume hood. Then use a blade to scrape off the active material layer of the pole piece, soak it in NMP, centrifuge and filter, take the filtered clear liquid, heat and dry the clear liquid to ⁇ 5mL and then test for infrared.
  • the number N1 of characteristic peaks from 1700cm -1 to 1600cm -1 the number N2 of characteristic peaks located from 1280cm -1 to 1210cm -1 and the number of characteristic peaks located from 1200cm -1 to 1000cm -1 N3 are shown in Table 2 respectively.
  • BS-SEM backscattered SEM image
  • the cross-sectional area of the conductive carbon black secondary particles is recorded as Sw ⁇ m 2 .
  • the conductive carbon black secondary particles with different cross-sectional areas are The number of secondary particles is shown in Table 2.
  • the nail penetration position is the intersection of the diagonal lines of the battery core.
  • the nail penetration depth is 15mm (from the tip of the nail to the main body of the nail).
  • the acupuncture speed: 150mm/s, angle: 90 Check whether the battery catches fire or explodes.
  • Example 2-1 Formula A 0.01 0.0007 100 3 5.6 0.001 0.001 1.35
  • Example 2-2 Formula A 0.05 0.0035 100 15 28 0.004 0.003 1.35
  • Example 2-3 Formula A 0.1 0.0070 100 30 56 0.008 0.006 1.35
  • Example 2-4 Formula A 0.2 0.0140 100 60 112 0.016 0.012 1.35
  • Example 2-5 Formula A 0.25 0.0175 100 75 140 0.020 0.015 1.35
  • Example 2-6 Formula A 0.3 0.0210 100 90 168 0.024 0.018 1.35
  • Example 2-7 Formula A 0.4 0.0280 100 120 224 0.032 0.024 1.35
  • Example 2-8 Formula A 0.5 0.0350 100 150 280 0.040 0.030 1.35
  • Example 2-9 Formula A 0.6 0.0420 100 180 336 0.048 0.036 1.35
  • Example 2-10 Formula B 0.1 0.0070 100 30 56 0.008 0.006 1.35
  • Example 2-11 Formula B 0.2 0.0140 100 60
  • Example 3-1 Formula A 0.1 0.0070 50 30 56 0.05 0.02 2.5
  • Example 3-2 Formula A 0.2 0.0140 60 60 112 0.1 0.05 2
  • Example 3-3 Formula A 0.2 0.0140 72 60 112 0.1 0.05 2
  • Example 3-4 Formula A 0.4 0.0280 140 120 224 0.35 0.05 7
  • Example 3-5 Formula A 0.4 0.0280 140 120 224 0.2 0.2 1.0
  • Example 3-6 Formula A 0.6 0.0420 200 180 336 0.3 0.27 1.1
  • Example 3-7 Formula A 0.6 0.0420 250 180 336 0.5 0.005 100
  • Example 3-8 Formula A 0.6 0.0420 280 180 336 0.5 0.005 100
  • Example 3-9 Formula A 0.4 0.0280 100 120 224 0.3 0.27 1.1
  • Example 3-10 Formula A 0.2 0.0140 150 60 112 0.1 0.05 2
  • Example 3-11 Formula A 0.2 0.0140 200 60 112 0.016 0.012 1.35
  • Example 3-12 Formula B 0.1 0.0070
  • amphiphilic additives in the active material layer can effectively reduce the risk of cracking of the active material layer after cold pressing and significantly improve the safety performance of secondary batteries.
  • Examples 3-1 to 3-8 and Examples 3-12 to 3-17 satisfy 300*W ⁇ H ⁇ 560*W, which can further improve the safety performance of secondary batteries.
  • Examples 3-9 to 3-11 did not satisfy 300*W ⁇ H ⁇ 560*W, and the safety performance of the secondary battery was slightly reduced.
  • amphiphilic additives can exert similar effects in the positive active material layer and the negative active material layer, thereby improving the safety performance of secondary batteries.

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Abstract

本申请公开了一种电极极片、电化学装置及用电装置。该电极极片包括：集流体；以及位于集流体至少一个表面的活性材料层，活性材料层包括活性材料以及两亲添加剂，两亲添加剂包括包含Si-O-C键的两亲化合物。本申请能够提升二次电池的能量密度和产能。

Description

电极极片、电化学装置及用电装置 技术领域
本申请属于电池技术领域，具体涉及一种电极极片、电化学装置及用电装置。
背景技术
二次电池具有能量密度高、循环寿命长，以及无污染、无记忆效应等突出特点。作为清洁能源，二次电池的应用已由电子产品逐渐普及到电动汽车等大型装置领域，以适应环境和能源的可持续发展战略。由此，也对二次电池的能量密度提出了更高的要求。
提高单位面积的活性物质含量是提高二次电池的能量密度的直接手段。然而，随着涂布重量的增加，电极极片在干燥的过程中极易发生活性材料层开裂的现象。
发明内容
本申请的目的在于提供一种电极极片、电化学装置及用电装置，旨在降低提升电极极片的能量密度，从而提升二次电池的能量密度。
本申请的第一方面提供一种电极极片，包括：集流体；以及位于集流体至少一个表面的活性材料层，活性材料层包括活性材料以及两亲添加剂，两亲添加剂包括包含Si-O-C键的两亲化合物。
本申请的电极极片中，活性材料层包括上述包含Si-O-C键的两亲化合物，能够显著提高活性材料物质层的涂布重量和优率，由此能够提升应用本申请的电极极片的二次电池的能量密度和产能。并非意在受限于任何理论或解释，在电极浆料中加入上述包含Si-O-C键的两亲化合物，该两亲化合物中的极性基团与电极浆料中的溶剂具有良好的亲和性，非极性基团与电极浆料中的导电剂等固体颗粒具有良好的亲和性。因此，电极浆料中的固体颗粒能够均匀、稳定地分散于溶剂中，电极浆料的溶剂也能够具有较低的极性。由此，电极浆料能够具有低表面张力。电极浆料具有低表面张力，能够增加电极浆料在涂布过程中的流平性以及降低电极浆料涂层在干燥过程中的应力收缩，从而能够有效降低电极极片在干燥过程中的开裂和鼓边的现象。因此，即使在高涂布重量下，本申请的电极极片也不易产生开裂，具有较高的优率。由此，本申请的电极极片能够具有高能量密度和高产能，应用于二次电池，能够允许二次电池具备高能量密度和高产能。
在任意实施方式中，包含Si-O-C键的两亲化合物还包含C＝N键。包含Si-O-C键的两亲化合物包含C＝N键，应用于电极浆料，能够进一步降低电极浆料的溶剂表面张力。由此，能够进一步降低电极极片干燥过程中活性材料层发生开裂的风险，从而允许电极极片具有更高的涂布重量，进而允许应用本申请的电极极片的二次电池具备更高的能量密度和更高的产能。
在任意实施方式中，活性材料层的红外光谱具有位于1700cm -1至1600cm -1的特征峰、位于1280cm -1至1210cm -1的特征峰以及位于1200cm -1至1000cm -1的特征峰。活性材料层的红外光谱具有上述特征峰，可认为两亲添加剂分子中包含C＝N键、Si-C键和Si-O-C键。两亲添加剂分子中包含上述化学键，尤其是包含C＝N键时，应用于电极浆料，能够进一步降低电极浆料的溶剂表面张力。由此，能够进一步降低电极极片干燥过程中活性材料层发生开裂的风险，从而允许电极极片具有更高的涂布重量，进而允许应用本申请的电极极片的二次电池具备更高的能量密度和更高的产能。
在任意实施方式中，活性材料层的红外光谱具有2个位于1200cm -1至1000cm -1的特征峰。活性材料层的红外光谱具有2个位于1200cm -1至1000cm -1的特征峰，其包括的两亲添加剂能够进一步改善电极浆料的流平性。由此，能够有效降低电极极片在干燥过程中的鼓边的现象，从而提高电极极片的产能、允许电极极片具有更高的涂布重量，进而允许应用本申请的电极极片的二次电池具备更高的能量密度和更高的产能。
在任意实施方式中，两亲添加剂包括式1所示的化合物，在式1中，R和R’各自独立地选自碳原子数为1至5的烷基。
(R’ 2N) 2C＝N(CH 2) 3-Si-(O-R) 3   式1
当两亲添加剂具有式1所示的结构时，能够显著降低电极浆料中溶剂的极性，从而降低高涂布重量下活性材料层开裂的风险。由此，能够允许电极极片中的活性材料层具有更高的厚度，从而允许二次电池具备更高的能量密度。
在任意实施方式中，电极极片的活性材料层满足：0.1≤W≤0.6，其中，W％表示基于活性材料层的总质量，两亲添加剂的质量百分含量。两亲添加剂在活性材料层中的质量百分含量在该合适的范围内，能够在允许活性材料层具有高厚度的同时，使得活性材料在活性材料层中具有高质量百分含量。因此，电极极片能够具有高能量密度。此外，两亲添加剂在活性材料层中的质量百分含量在上述合适的范围内，还能够使得电极极片具备良好的电解液浸润性能，从而使得电极极片具有低内阻。由此，能够允许应用本申请的电极极片的二次电池具备高能量密度和良好的循环性能。
在任意实施方式中，电极极片的活性材料层满足：0.01≤Ws≤0.2，其中，Ws％表示基于活性材料层的总质量，硅元素的质量百分含量。活性材料层中硅元素的质量百分含量在上述合适的范围内，可认为两亲添加剂的质量百分含量在合适的范围内。由此，能够在允许活性材料层具有高厚度的同时，使得活性材料在活性材料层中具有高质量百分含量。因此，电极极片能够具有高能量密度。此外，两亲添加剂的质量百分含量在合适的范围内，还能够使得电极极片具备良好的电解液浸润性能，从而使得电极极片具有低内阻。由此，能够允许应用本申请的电极极片的二次电池具备高能量密度和良好的循环性能。
在任意实施方式中，活性材料层满足：300*W≤H≤560*W，且50≤H≤280，其中，Hμm表示单面活性材料层的厚度。W和H满足上述数量关系时，活性材料层的厚度和两亲添加剂的含量适当，能够使得活性材料从内部具有合适的烘干梯度，从而能够在降低电极极片烘干过程中活性材料层开裂的风险的同时，使得电极极片容易烘干。此外，活性材料层的厚度合适，还能降低电极极片的极化程度，从而提升二次电池的循环性能。 由此，本申请的电极极片能够具有高能量密度、高产能和良好的循环性能。
在任意实施方式中，活性材料层沿自身厚度方向包括远离集流体表面的第一层和靠近集流体表面的第二层，第一层和第二层的厚度相等，活性材料层满足：1.1≤Ws 1/Ws 2≤100，其中，Ws 1％表示基于第一层的总质量，第一层中硅元素的质量百分含量；Ws 2％表示基于第二层的总质量，第二层中硅元素的质量百分含量。
在任意实施方式中，活性材料层满足：1.1≤Ws 1/Ws 2≤10。
当活性材料层中包括两亲添加剂时，在电极极片的干燥过程中，两亲添加剂可以发生运动，从而使得Ws 1和Ws 2满足上述数量关系，即第一层中两亲添加剂的含量高于第二层中两亲添加剂的含量。当第一层中两亲添加剂的含量高于第二层中两亲添加剂的含量时，能够有效提升烘干过程中活性材料层内部的表面张力，从而缓解活性材料层因表面先干、内部后干而引起的开裂现象。
在任意实施方式中，0.01≤Ws 1≤0.3，且0≤Ws 2≤0.27。Ws 1、Ws 2在上述合适的范围内，能够使得电极极片表面残留的两亲添加剂的含量适当，从而能够在降低活性材料层开裂的风险的同时，有利于辊压等工序的顺利进行，进而使得电极极片具备高能量密度和高产能。
在任意实施方式中，活性材料层还包括导电剂，导电剂包括导电炭黑二次颗粒，活性材料层的截面满足：每0.01mm 2内，截面积≥5μm 2的导电炭黑二次颗粒的数量≤2。可选地，活性材料层的截面满足：每0.01mm 2内，截面积为0.1μm 2至1μm 2的导电炭黑二次颗粒的数量≤4。当电极浆料中包括两亲添加剂时，够使得电极浆料中的导电炭黑二次颗粒混匀分散，由此，导电炭黑二次颗粒在活性材料层的截面的分布情况可满足上述条件。导电炭黑二次颗粒在活性材料层的截面的分布情况满足上述条件，可认为两亲添加剂能够显著降低活性材料层开裂的风险，且电极极片能够具备良好的电子传导能力。由此，本申请的电极极片应用于二次电池，能够提升二次电池的能量密度和循环性能。
本申请的第二方面提供一种电化学装置，包括正极极片和负极极片，正极极片和/或负极极片选自本申请第一方面的电极极片。
本申请的电化学装置中包括本申请第一方面的电极极片，能够具有具备高能量密度和高产能。
在任意实施方式中，正极极片和负极极片选自本申请第一方面的电极极片，电化学装置满足0.1≤Ws 3/Ws 4≤10，其中，Ws 3％表示基于正极活性材料层的总质量，正极活性材料层中硅元素的质量百分含量；Ws 4％表示基于负极活性材料层的总质量，负极活性材料层中硅元素的质量百分含量。正极活性材料层和负极活性材料层中均包括两亲添加剂，并使得Ws 3和Ws 4满足上述数量关系，能够有效降低电极极片烘干过程中活性材料层内部的表面张力，从而缓解活性材料层因表面先干、内部后干而引起的开裂现象。
本申请的第三方面提供一种用电装置，其包括本申请第二方面的电化学装置。
本申请的用电装置包括本申请的电化学装置，因而至少具有与所述电化学装置相同的优势
附图说明
为了更清楚地说明本申请实施例的技术方案，下面将对本申请实施例中所需要使用的附图作简单地介绍，显而易见地，下面所描述的附图仅仅是本申请的一些实施方式。
图1是本申请一实施例的电化学装置的示意图。
图2是图1所示的电化学装置的分解图。
图3是本申请一实施例的用电装置的示意图。
图4是实施例1的红外光谱图。
图5是导电炭黑二次颗粒在活性材料层的截面的分布情况测试图。
图6是导电炭黑二次颗粒在活性材料层的截面的分布情况测试图。
图7是导电炭黑二次颗粒在活性材料层的截面的分布情况测试图。
图8是导电炭黑二次颗粒在活性材料层的截面的分布情况测试图。
附图标记说明：
5电化学装置；51壳体；52电极组件；53顶盖组件。
具体实施方式
为了使本申请的发明目的、技术方案和有益技术效果更加清晰，以下结合实施例对本申请进行进一步详细说明。应当理解的是，本说明书中描述的实施例仅仅是为了解释本申请，并非为了限定本申请。
为了简便，本文仅明确地公开了一些数值范围。然而，任意下限可以与任何上限组合形成未明确记载的范围；以及任意下限可以与其它下限组合形成未明确记载的范围，同样任意上限可以与任意其它上限组合形成未明确记载的范围。此外，尽管未明确记载，但是范围端点间的每个点或单个数值都包含在该范围内。因而，每个点或单个数值可以作为自身的下限或上限与任意其它点或单个数值组合或与其它下限或上限组合形成未明确记载的范围。
在本文的描述中，需要说明的是，除非另有说明，“以上”、“以下”为包含本数，“一种或几种”中“几种”的含义是两种或两种以上。
除非另有说明，本申请中使用的术语具有本领域技术人员通常所理解的公知含义。除非另有说明，本申请中提到的各参数的数值可以用本领域常用的各种测量方法进行测量(例如，可以按照在本申请的实施例中给出的方法进行测试)。
术语“约”用以描述及说明小的变化。当与事件或情形结合使用时，所述术语可指代其中事件或情形精确发生的例子以及其中事件或情形极近似地发生的例子。举例来说，当结合数值使用时，术语可指代小于或等于所述数值的±10％的变化范围，例如小于或等于±5％、小于或等于±4％、小于或等于±3％、小于或等于±2％、小于或等于±1％、小于或等于±0.5％、小于或等于±0.1％、或小于或等于±0.05％。另外，有时在本文中以范围格式呈现量、比率和其它数值。应理解，此类范围格式是用于便利及简洁起见，且应灵活地理解，不仅包含明确地指定为范围限制的数值，而且包含涵盖于所述范围内的所有个别数值或子范围，如同明确地指定每一数值及子范围一般。
术语“中的至少一者”、“中的至少一个”、“中的至少一种”或其他相似术语所连接的项目的列表可意味着所列项目的任何组合。例如，如果列出项目A及B，那么短 语“A及B中的至少一者”意味着仅A；仅B；或A及B。在另一实例中，如果列出项目A、B及C，那么短语“A、B及C中的至少一者”意味着仅A；或仅B；仅C；A及B(排除C)；A及C(排除B)；B及C(排除A)；或A、B及C的全部。项目A可包含单个组分或多个组分。项目B可包含单个组分或多个组分。项目C可包含单个组分或多个组分。
本申请的上述发明内容并不意欲描述本申请中的每个公开的实施方式或每种实现方式。如下描述更具体地举例说明示例性实施方式。在整篇申请中的多处，通过一系列实施例提供了指导，这些实施例可以以各种组合形式使用。在各个实例中，列举仅作为代表性组，不应解释为穷举。
如背景技术所述，提高单位面积的活性物质含量是提高二次电池的能量密度的直接手段。
然而，随着涂布重量的增加，电极极片在干燥的过程中极易发生活性材料层开裂的现象。尤其是，在使用磷酸铁锂(LFP)等纳米材料时，由于颗粒纳米化效应，电极浆料的表面张力较大。因此，在电极极片干燥的过程中，活性材料层内部应力不均，极易出现开裂和鼓边等问题，由此限制了活性材料层的厚度和产能。
相关技术中，为降低活性材料层的开裂程度，采取的手段多是对电极极片的干燥工艺进行优化。但是，这种方法不仅成本高、难度大，而且很难突破活性材料层单面涂布重量250mg/1540.25mm 2的瓶颈。
为了解决上述问题，发明人经深入思考与大量实验，提供了一种电极极片、电化学装置及用电装置，该电极极片应用于电化学，能够使得电化学装置具备高能量密度和高产能。
电极极片
本申请第一方面提供一种电极极片，包括：集流体；以及位于所述集流体至少一个表面的活性材料层，所述活性材料层包括活性材料以及两亲添加剂，所述两亲添加剂包括包含Si-O-C键的两亲化合物。
本申请的电极极片可以为正极极片，也可以为负极极片。当电极极片为正极极片时，活性材料层可以为正极活性材料层；相应地，当电极极片为负极极片时，负极活性材料层可以为负极活性材料层。
上述包含Si-O-C键的两亲化合物可以为在分子中同时包括极性基团和非极性基团、且包含Si-O-C键的化合物。
虽然机理尚不明确，发明人意外地发现，用于形成活性材料层的物质中包括上述包含Si-O-C键的两亲化合物，能够显著提高活性材料物质层的涂布重量和优率，由此能够提升应用本申请的电极极片的二次电池的能量密度和产能。在一些实施例中，电极极片的活性材料层单面涂布重量可以达到250mg/1540.25mm 2以上，甚至达到500mg/1540.25mm 2以上。
具体地，并非意在受限于任何理论或解释，在电极浆料中加入上述包含Si-O-C键的两亲化合物，该两亲化合物中的极性基团与电极浆料中的溶剂具有良好的亲和性，非极性基团与电极浆料中的导电剂等固体颗粒具有良好的亲和性。因此，电极浆料中的固 体颗粒能够均匀、稳定地分散于溶剂中，电极浆料的溶剂也能够具有较低的极性。由此，电极浆料能够具有低表面张力。电极浆料具有低表面张力，能够增加电极浆料在涂布过程中的流平性以及降低电极浆料涂层在干燥过程中的应力收缩，从而能够有效降低电极极片在干燥过程中的开裂和鼓边的现象。因此，即使在高涂布重量下，本申请的电极极片也不易产生开裂，具有较高的优率。由此，本申请的电极极片能够具有高能量密度和高产能，应用于二次电池，能够允许二次电池具备高能量密度和高产能。
在一些实施方式中，所述包含Si-O-C键的两亲化合物还可包含C＝N键。
并非意在受限于任何理论或解释，包含Si-O-C键的两亲化合物包含C＝N键，应用于电极浆料，能够进一步降低电极浆料的溶剂表面张力。由此，能够进一步降低电极极片干燥过程中活性材料层发生开裂的风险，从而允许电极极片具有更高的涂布重量，进而允许应用本申请的电极极片的二次电池具备更高的能量密度和更高的产能。
在一些实施方式中，所述活性材料层的红外光谱可具有位于1700cm -1至1600cm -1的特征峰、位于1280cm -1至1210cm -1的特征峰以及位于1200cm -1至1000cm -1的特征峰。
活性材料层的红外光谱中，位于1700cm -1至1600cm -1的特征峰为可表征C＝N键的特征峰，位于1280cm -1至1210cm -1的特征峰为可表征Si-C键的特征峰，位于1200cm -1至1000cm -1的特征峰为可表征Si-O-C键的特征峰。上述特征峰可以为表征两亲添加剂的特征峰。
并非意在受限于任何理论或解释，活性材料层的红外光谱具有上述特征峰，可认为两亲添加剂分子中包含C＝N键、Si-C键和Si-O-C键。两亲添加剂分子中包含上述化学键，尤其是包含C＝N键时，应用于电极浆料，能够进一步降低电极浆料的溶剂表面张力。由此，能够进一步降低电极极片干燥过程中活性材料层发生开裂的风险，从而允许电极极片具有更高的涂布重量，进而允许应用本申请的电极极片的二次电池具备更高的能量密度和更高的产能。
在一些实施方式中，所述活性材料层的红外光谱可具有2个位于1200cm -1至1000cm -1的特征峰。
并非意在受限于任何理论或解释，活性材料层的红外光谱具有2个位于1200cm -1至1000cm -1的特征峰，其包括的两亲添加剂能够进一步改善电极浆料的流平性。由此，能够有效降低电极极片在干燥过程中的鼓边的现象，从而提高电极极片的产能、允许电极极片具有更高的涂布重量，进而允许应用本申请的电极极片的二次电池具备更高的能量密度和更高的产能。
在一些实施方式中，所述两亲添加剂可包括式1所示的化合物。
(R’ 2N) 2C＝N(CH 2) 3-Si-(O-R) 3  式1
在式1中，R和R’可各自独立地选自碳原子数为1至5的烷基，如碳原子数为1至5的烷基可以是甲基、乙基、丙基、丁基、戊基，其中有异构体烷基的还可以是其同分异构体，如丙基可以是正丙基和异丙基，丁基可以是正丁基、异丁基、仲丁基、叔丁基。。
并非意在受限于任何理论或解释，发明人发现，两亲添加剂中包括烷氧基，能够有效降低电极浆料中溶剂的极性。随着烷氧基中碳原子数的增加，两亲化合物对溶剂极 性的降低作用会有所减弱。当两亲添加剂具有式1所示的结构时，能够显著降低电极浆料中溶剂的极性，从而降低高涂布重量下活性材料层开裂的风险。由此，能够允许电极极片中的活性材料层具有更高的厚度，从而允许二次电池具备更高的能量密度。
在一些实施方式中，所述电极极片的活性材料层可满足：0.1≤W≤0.6，其中，W％表示基于所述活性材料层的总质量，所述两亲添加剂的质量百分含量。例如，W％可为0.1％，0.2％，0.3％，0.4％，0.5％，0.6％或者处于以上任意数值所组成的范围内。
并非意在受限于任何理论或解释，两亲添加剂在活性材料层中的质量百分含量在上述合适的范围内，能够在允许活性材料层具有高厚度的同时，使得活性材料在活性材料层中具有高质量百分含量。因此，电极极片能够具有高能量密度。此外，两亲添加剂在活性材料层中的质量百分含量在上述合适的范围内，还能够使得电极极片具备良好的电解液浸润性能，从而使得电极极片具有低内阻。由此，能够允许应用本申请的电极极片的二次电池具备高能量密度和良好的循环性能。
在一些实施方式中，所述电极极片的活性材料层可满足：0.01≤Ws≤0.2，其中，Ws％表示基于所述活性材料层的总质量，硅元素的质量百分含量。可选地，W S可以为0.01，0.05，0.08，0.1，0.12，0.15，0.18，0.2或者处于以上任意数值所组成的范围内。
该实施方式中，硅元素可以为两亲添加剂所包含的硅元素。并非意在受限于任何理论或解释，活性材料层中硅元素的质量百分含量在上述合适的范围内，可认为两亲添加剂的质量百分含量在合适的范围内。由此，能够在允许活性材料层具有高厚度的同时，使得活性材料在活性材料层中具有高质量百分含量。因此，电极极片能够具有高能量密度。此外，两亲添加剂的质量百分含量在合适的范围内，还能够使得电极极片具备良好的电解液浸润性能，从而使得电极极片具有低内阻。由此，能够允许应用本申请的电极极片的二次电池具备高能量密度和良好的循环性能。
在一些实施方式中，所述活性材料层可满足：300*W≤H≤560*W，且50≤H≤280，其中，W％表示基于所述活性材料层的总质量，两亲添加剂的质量百分含量；Hμm表示单面所述活性材料层的厚度。
并非意在受限于任何理论或解释，W较大时，活性材料层中两亲添加剂的含量高，W较小时，活性材料层中两亲添加剂的含量低。W和H满足上述数量关系时，活性材料层的厚度和两亲添加剂的含量适当，能够使得活性材料从内部具有合适的烘干梯度，从而能够在降低电极极片烘干过程中活性材料层开裂的风险的同时，使得电极极片容易烘干。此外，活性材料层的厚度合适，还能降低电极极片的极化程度，从而提升二次电池的循环性能。由此，本申请的电极极片能够具有高能量密度、高产能和良好的循环性能。
在一些实施方式中，所述活性材料层沿自身厚度方向包括远离所述集流体表面的第一层和靠近所述集流体表面的第二层，所述第一层和所述第二层的厚度相等，所述活性材料层可满足：1.1≤Ws 1/Ws 2≤100，其中，Ws 1％表示基于所述第一层的总质量，所述第一层中硅元素的质量百分含量；Ws 2％表示基于所述第二层的总质量，所述第二层中硅元素的质量百分含量。
在一些实施方式中，所述活性材料层可满足：1.1≤Ws 1/Ws 2≤10。
需要说明的是，所述第一层和所述第二层仅是活性材料层在厚度方向上的不同部 分，所述第一层和所述第二层并不是分立的结构。所述第一层和所述第二层可通过如下方式确定：测量活性材料层的厚度，以确定活性材料层的中心面，该中心面与活性材料层远离集流体的表面之间的距离等于该中心面与活性材料层靠近集流体的表面之间的距离；将所述中心面至活性材料层远离集流体的表面之间的部分确定为所述第一层，将所述中心面至活性材料层靠近集流体的表面之间的部分确定为所述第二层。
并非意在受限于任何理论或解释，当活性材料层中包括两亲添加剂时，在电极极片的干燥过程中，两亲添加剂可以发生运动，从而使得Ws 1和Ws 2满足上述数量关系，即第一层中两亲添加剂的含量高于第二层中两亲添加剂的含量。当第一层中两亲添加剂的含量高于第二层中两亲添加剂的含量时，能够有效提升烘干过程中活性材料层内部的表面张力，从而缓解活性材料层因表面先干、内部后干而引起的开裂现象。
在一些实施方式中，其中，0.01≤Ws 1≤0.3，且0≤Ws 2≤0.27。
并非意在受限于任何理论或解释，Ws 1、Ws 2在上述合适的范围内，能够使得电极极片表面残留的两亲添加剂的含量适当，从而能够在降低活性材料层开裂的风险的同时，有利于辊压等工序的顺利进行，进而使得电极极片具备高能量密度和高产能。
在一些实施方式中，所述活性材料层还可包括导电剂，所述导电剂可包括导电炭黑二次颗粒，所述活性材料层的截面可满足：每0.01mm 2内，截面积≥5μm 2的所述导电炭黑二次颗粒的数量≤2。可选地，所述活性材料层的截面可满足：每0.01mm 2内，截面积为0.1μm 2至1μm 2的所述导电炭黑二次颗粒的数量≤4。
上述截面可包括沿活性材料层长度方向所作的截面或沿活性材料层宽度方向所作的截面。
并非意在受限于任何理论或解释，当电极浆料中包括两亲添加剂时，够使得电极浆料中的导电炭黑二次颗粒混匀分散，由此，导电炭黑二次颗粒在活性材料层的截面的分布情况可满足上述条件。导电炭黑二次颗粒在活性材料层的截面的分布情况满足上述条件，可认为两亲添加剂能够显著降低活性材料层开裂的风险，且电极极片能够具备良好的电子传导能力。由此，本申请的电极极片应用于二次电池，能够提升二次电池的能量密度和循环性能。
在一些实施方式中，电极极片可以为负极极片，集流体可以为负极集流体，活性材料层可以为负极活性材料层。
本申请对负极极片的负极集流体不作限定。可以使用金属箔材或多孔金属板，例如使用铜、镍、钛、铁等金属或它们的合金的箔材或多孔板。作为示例，负极集流体为铜箔。
在一些实施方式中，所述负极集流体具有在自身厚度方向上相对的两个表面，负极活性材料层可以设置在负极集流体的一个表面，也可以同时设置在负极集流体的两个表面。例如，负极集流体具有在其自身厚度方向相对的两个表面，负极活性材料层设置在负极集流体相对的两侧中的任意一个表面或两个表面上。
负极活性材料的具体种类不受到具体的限制，可根据需求进行选择。作为示例，其他负极活性材料包括但不限于天然石墨、人造石墨、中间相微碳球(MCMB)、硬碳，软碳、硅、硅-碳复合物、SiO、Li-Sn合金、Li-Sn-O合金、Sn、SnO、SnO 2、尖晶石 结构的Li 4Ti 5O 12、Li-Al合金中的至少一种。
在一些实施方式中，所述负极活性材料层还可选地包括粘结剂。粘结剂的具体种类不受到具体的限制，可根据需求进行选择。作为示例，粘结剂包括但不限于丁苯橡胶(SBR)、聚偏二氟乙烯(PVDF)、聚四氟乙烯(PTFE)、聚乙烯醇缩丁醛(PVB)、水性丙烯酸树脂(Water-based acrylic resin)及羧甲基纤维素中的至少一种。
在一些实施方式中，负极活性材料层还可选地包括导电剂。导电剂的具体种类不受到具体的限制，可根据需求进行选择。作为示例，导电剂包括但不限于导电石墨、超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。
在一些实施方式中，负极活性材料层还可选地包括其他助剂，例如增稠剂(如羧甲基纤维素钠(CMC-Na))等。
本申请中负极极片可以按照本领域常规方法制备。例如将负极活性材料，导电剂，粘结剂和增稠剂分散于溶剂中，溶剂可以是N-甲基吡咯烷酮(NMP)或去离子水，形成均匀的负极浆料，将负极浆料涂覆在负极集流体上，经烘干、冷压等工序得到负极极片。
在一些实施方式中，电极极片可以为正极极片，集流体可以为正极集流体，活性材料层可以为正极活性材料层。
本申请对正极极片的正极集流体不作限定。正极集流体可采用金属箔片或复合集流体。作为金属箔片的示例，正极集流体可采用铝箔。复合集流体可包括高分子材料基层以及形成于高分子材料基层至少一个表面上的金属材料层。作为示例，金属材料可选自铝、铝合金、镍、镍合金、钛、钛合金、银、银合金中的一种或几种。作为示例，高分子材料基层可选自聚丙烯、聚对苯二甲酸乙二醇酯、聚对苯二甲酸丁二醇酯、聚苯乙烯、聚乙烯等。
在一些实施方式中，所述正极集流体具有在自身厚度方向上相对的两个表面，正极活性材料层可以设置在正极集流体的一个表面，也可以同时设置在正极集流体的两个表面。例如，正极集流体具有在其自身厚度方向相对的两个表面，正极活性材料层设置在正极集流体相对的两侧中的任意一个表面或两个表面上。
正极活性材料的具体种类不受到具体的限制，可根据需求进行选择。例如，正极活性材料可以包括锂过渡金属氧化物、橄榄石结构的含锂磷酸盐及其各自的改性化合物中的一种或几种。在本申请的电化学装置中，上述各正极活性材料的改性化合物可以是对正极活性材料进行掺杂改性、表面包覆改性、或掺杂同时表面包覆改性。
作为示例，锂过渡金属氧化物可以包括锂钴氧化物、锂镍氧化物、锂锰氧化物、锂镍钴氧化物、锂锰钴氧化物、锂镍锰氧化物、锂镍钴锰氧化物、锂镍钴铝氧化物及其改性化合物中的一种或几种。作为示例，橄榄石结构的含锂磷酸盐可以包括磷酸铁锂、磷酸铁锂与碳的复合材料、磷酸锰锂、磷酸锰锂与碳的复合材料、磷酸锰铁锂、磷酸锰铁锂与碳的复合材料及其改性化合物中的一种或几种。这些正极活性材料可以仅单独使用一种，也可以将两种以上组合使用。
在一些实施方式中，所述正极活性材料层还可选地包括粘结剂。粘结剂的具体种类不受到具体的限制，可根据需求进行选择。作为示例，粘结剂包括但不限于聚偏氟乙 烯(PVDF)、聚四氟乙烯(PTFE)、偏氟乙烯-四氟乙烯-丙烯三元共聚物、偏氟乙烯-六氟丙烯-四氟乙烯三元共聚物、四氟乙烯-六氟丙烯共聚物及含氟丙烯酸酯树脂中的至少一种。
在一些实施方式中，正极活性材料层还可选地包括导电剂。导电剂的具体种类不受到具体的限制，可根据需求进行选择。作为示例，导电剂包括但不限于导电石墨、超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。
本申请中正极极片可以按照本领域常规方法制备。例如，正极活性材料层通常是将正极浆料涂布在正极集流体上，经干燥、冷压而成的。正极浆料通常是将正极活性材料、可选的导电剂、可选的粘结剂以及任意的其他组分分散于溶剂中并搅拌均匀而形成的。溶剂可以是N-甲基吡咯烷酮(NMP)，但不限于此。
需要说明的是，本申请所给的各电极活性材料层参数均指单面电极活性材料层的参数范围。当电极活性材料层设置在负极集流体的两个表面时，其中任意一个表面的电极活性材料层参数满足本申请，即认为落入本申请的保护范围内。
另外，本申请中的电极极片并不排除除了活性材料层之外的其他附加功能层。例如，在某些实施方式中，本申请的电极极片还包括夹在集流体和活性材料层之间、设置于集流体表面的导电底涂层(例如由导电剂和粘结剂组成)。在另外一些实施方式中，本申请的电极极片还包括覆盖在活性材料层表面的保护层。
在本申请中，红外光谱可通过本领域已知的方法和仪器测定。例如，可以利用红外光谱仪测试得到，具体地，可以将电池放电至0％SOC后，拆解得到取电极极片；将所述电极极片在通风橱中自然晾干；然后使用刀片将电极极片的活性材料层刮下，用NMP浸泡后离心并抽滤，取过滤后的清液，将清液加热蒸发至≤5mL后，参照GB/T 21186-2007的测试方法，测试得到活性材料层的红外光谱。
在本申请中，活性材料层中硅元素的质量百分含量可通过如下方法测试得到：将电池放电至0％SOC后，拆解得到电极极片；将所述电极极片在通风橱中自然晾干；然后使用刀片分别将上层(第一层)和下层(第二层)的粉末刮下后，分别称取上层粉末的质量m 1和下层粉末的质量m 2，使用ICP测试硅元素含量，分别得到W S1和W S2。W S可通过将上层粉末和下层粉末混合后，使用ICP测试得到，或通过下计算得到：W S＝(m 1W S1+m 2W S2)/(m 1+m 2)。
在本申请中，导电炭黑二次颗粒在活性材料层的截面的分布情况可通过如下方法测试得到：将冷压后的电极极片，随机选取区域，进行截面抛光处理，并拍摄背散射SEM图(BS-SEM)，放大倍数为1000倍；采用IMAGE J对BS-SEM进行图像处理，调整合适的对比度，直至能够清楚地看到导电炭黑二次颗粒的轮廓；使用软件统计截面中每个导电炭黑二次颗粒的面积，计算得到导电炭黑二次颗粒在活性材料层的截面的分布情况。
需要说明的是，上述针对电极活性材料层或电极活性材料颗粒的各种参数测试，可以在电池制备过程中取样测试，也可以从制备好的二次电池中取样测试。
当上述测试样品是从制备好的二次电池中取样时，作为示例，可以按如下步骤S10-S30进行取样。
S10，将二次电池做放电处理(为了安全起见，一般使电池处于满放状态)；将电池拆卸后取出电极极片，使用碳酸二甲酯(DMC)将电极极片浸泡一定时间(例如2-10小时)；然后将电极极片取出并在一定温度和时间下干燥处理(例如60℃，4小时)，干燥后取出电极极片。此时即可以在干燥后的电极极片中取样测试本申请上述的电极活性材料层相关的各参数。
S20，将步骤S10干燥后的电极极片在一定温度及时间下烘烤(例如400℃，2小时)，在烘烤后的电极极片中任选一区域，对电极活性材料取样(可以选用刀片刮粉取样)。
S30，将步骤S20收集到的电极活性材料做过筛处理(例如用200目的筛网过筛)最终得到可以用于测试本申请上述的各电极活性材料参数的样品。
电化学装置
本申请第二方面提供一种电化学装置，包括其中发生电化学反应以将化学能与电能互相转化的任何装置，它的具体实例包括所有种类的锂一次电池或锂二次电池。特别地，锂二次电池包括锂金属二次电池、锂离子二次电池、锂聚合物二次电池或锂离子聚合物二次电池。
本申请的电化学装置包括电极极片、隔离膜和电解液。其中，电极极片可包括正极极片和负极极片。
在一些实施方式中，正极极片、负极极片和隔离膜可通过卷绕工艺或叠片工艺制成电极组件。
本申请的电化学装置还包括外包装，用于封装电极组件及电解液。在一些实施方式中，外包装可以是硬壳，例如硬塑料壳、铝壳、钢壳等，也可以是软包，例如袋式软包。软包的材质可以是塑料，如聚丙烯(PP)、聚对苯二甲酸丁二醇酯(PBT)、聚丁二酸丁二醇酯(PBS)中的至少一种。
本申请对电化学装置的形状没有特别的限制，其可以是圆柱形、方形或其他任意的形状。例如，图1是作为一个示例的方形结构的电化学装置5。
在一些实施方式中，参照图2，外包装可包括壳体51和顶盖组件53。其中，壳体51可包括底板和连接于底板上的侧板，底板和侧板围合形成容纳腔。壳体51具有与容纳腔连通的开口，顶盖组件53能够盖设于所述开口，以封闭所述容纳腔。正极极片、负极极片和隔离膜可经卷绕工艺或叠片工艺形成电极组件52。电极组件52封装于所述容纳腔内。电解液浸润于电极组件52中。电化学装置5所含电极组件52的数量可以为一个或多个，本领域技术人员可根据具体实际需求进行选择。
[电极极片]
本申请的电化学装置中，使用的正极极片和/或负极极片为本申请第一方面的电极极片。
在一些实施方式中，正极极片和负极极片均为本申请第一方面的电极极片，所述电化学装置可满足0.1≤Ws 3/Ws 4≤10，其中，Ws 3％表示基于正极活性材料层的总质量，正极活性材料层中硅元素的质量百分含量；Ws 4％表示基于负极活性材料层的总质量，负极活性材料层中硅元素的质量百分含量。
正极活性材料层和负极活性材料层中均包括两亲添加剂，并使得Ws 3和Ws 4满足上述数量关系，能够有效降低电极极片烘干过程中活性材料层内部的表面张力，从而缓解活性材料层因表面先干、内部后干而引起的开裂现象。当Ws 3/Ws 4＞10，意味着Ws 4较小，负极活性材料层中两亲添加剂含量较低，对负极极片开裂程度的降低效果有限；当Ws 3/Ws 4＜0.1，则意味着Ws 4较大，两亲添加剂含量较高，可能会影响极片干燥，造成粘辊。Ws 3/Ws 4的值在上述合适的范围内，能够在降低正极极片、负极极片的开裂程度的同时，使得正极极片、负极极片具备良好的加工性能。
[电解液]
电解液在正极极片和负极极片之间起到传导活性离子的作用。可用于本申请电化学装置的电解液可以为现有技术已知的电解液。
在一些实施方式中，所述电解液包括有机溶剂、锂盐和可选的添加剂，有机溶剂、锂盐和添加剂的种类均不受到具体的限制，可根据需求进行选择。
在一些实施方式中，作为示例，所述锂盐包括但不限于LiPF 6(六氟磷酸锂)、LiBF 4(四氟硼酸锂)、LiClO 4(高氯酸锂)、LiFSI(双氟磺酰亚胺锂)、LiTFSI(双三氟甲磺酰亚胺锂)、LiTFS(三氟甲磺酸锂)、LiDFOB(二氟草酸硼酸锂)、LiBOB(二草酸硼酸锂)、LiPO 2F 2(二氟磷酸锂)、LiDFOP(二氟二草酸磷酸锂)及LiTFOP(四氟草酸磷酸锂)中的至少一种。上述锂盐可以单独使用一种，也可以同时使用两种或两种以上。
在一些实施方式中，作为示例，所述有机溶剂包括但不限于碳酸亚乙酯(EC)、碳酸亚丙酯(PC)、碳酸甲乙酯(EMC)、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)、碳酸亚丁酯(BC)、氟代碳酸亚乙酯(FEC)、甲酸甲酯(MF)、乙酸甲酯(MA)、乙酸乙酯(EA)、乙酸丙酯(PA)、丙酸甲酯(MP)、丙酸乙酯(EP)、丙酸丙酯(PP)、丁酸甲酯(MB)、丁酸乙酯(EB)、1,4-丁内酯(GBL)、环丁砜(SF)、二甲砜(MSM)、甲乙砜(EMS)及二乙砜(ESE)中的至少一种。上述有机溶剂可以单独使用一种，也可以同时使用两种或两种以上。可选地，上述有机溶剂同时使用两种或两种以上。
在一些实施方式中，所述添加剂可以包括负极成膜添加剂、正极成膜添加剂，还可以包括能够改善电池某些性能的添加剂，例如改善电池过充性能的添加剂、改善电池高温或低温性能的添加剂等。
作为示例，所述添加剂包括但不限于氟代碳酸乙烯酯(FEC)、碳酸亚乙烯酯(VC)、乙烯基碳酸乙烯酯(VEC)、硫酸乙烯酯(DTD)、硫酸丙烯酯、亚硫酸乙烯酯(ES)、1,3-丙磺酸内酯(PS)、1,3-丙烯磺酸内酯(PST)、磺酸酯环状季铵盐、丁二酸酐、丁二腈(SN)、己二腈(AND)、三(三甲基硅烷)磷酸酯(TMSP)、三(三甲基硅烷)硼酸酯(TMSB)中的至少一种。
电解液可以按照本领域常规的方法制备。例如，可以将有机溶剂、锂盐、可选的添加剂混合均匀，得到电解液。各物料的添加顺序并没有特别的限制，例如，将锂盐、可选的添加剂加入到有机溶剂中混合均匀，得到电解液；或者，先将锂盐加入有机溶剂中，然后再将可选的添加剂加入有机溶剂中混合均匀，得到电解液。
[隔离膜]
隔离膜设置在正极极片和负极极片之间，主要起到防止正负极短路的作用，同时可以使活性离子通过。本申请对隔离膜的种类没有特别的限制，可以选用任意公知的具有良好的化学稳定性和机械稳定性的多孔结构隔离膜。
在一些实施方式中，隔离膜的材质可以选自玻璃纤维、无纺布、聚乙烯、聚丙烯、聚偏氟乙烯中的一种或几种，但不仅限于这些。隔离膜可以是单层薄膜，也可以是多层复合薄膜。隔离膜为多层复合薄膜时，各层的材料相同或不同。在一些实施方式中，隔离膜上还可以设置陶瓷涂层、金属氧化物涂层。
用电装置
本申请第三方面提供了一种用电装置，其包括本申请第二方面的电化学装置。
本申请的用电装置没有特别限定，其可以是用于现有技术中已知的任何电子设备。在一些实施方式中，用电装置可以包括但不限于，笔记本电脑、笔输入型计算机、移动电脑、电子书播放器、便携式电话、便携式传真机、便携式复印机、便携式打印机、头戴式立体声耳机、录像机、液晶电视、手提式清洁器、便携CD机、迷你光盘、收发机、电子记事本、计算器、存储卡、便携式录音机、收音机、备用电源、电机、汽车、摩托车、助力自行车、自行车、照明器具、玩具、游戏机、钟表、电动工具、闪光灯、照相机、家庭用大型蓄电池和锂离子电容器等。
图3是作为一个示例的用电装置。该用电装置可以为纯电动车、混合动力电动车、或插电式混合动力电动车等。
实施例
下述实施例更具体地描述了本发明公开的内容，这些实施例仅仅用于阐述性说明，因为在本发明公开内容的范围内进行各种修改和变化对本领域技术人员来说是明显的。除非另有声明，以下实施例中所报道的所有份、百分比、和比值都是基于质量计，而且实施例中使用的所有试剂都可商购获得或是按照常规方法进行合成获得，并且可直接使用而无需进一步处理，以及实施例中使用的仪器均可商购获得。
实施例14至实施例1-7
负极极片的制备
将石墨、粘结剂丁苯橡胶(SBR)、导电剂炭黑、增稠剂羧甲基纤维素钠(CMC-Na)按照质量比97.4:1.2:1.4进行混合，加入适量的溶剂去离子水，充分搅拌均匀后得到负极浆料；将负极浆料均匀涂覆在负极集流体铜箔的两个表面上；然后经过120℃烘箱干燥、冷压、分切等，得到负极极片。
正极极片的制备
将正极活性材料磷酸铁锂、粘结剂PVDF、导电剂炭黑按照质量比96:2:2进行混合，加入适量的溶剂NMP，充分搅拌均匀后，加入添加剂，混合均匀后得到正极浆料；将正极浆料均匀涂覆在正极集流体铝箔的两个表面上；然后经120℃烘箱干燥、冷压、分切等，得到正极极片。
实施例1-1至实施例1-7的正极极片制备参数分别如表1-1所示，表1-1中，W表示基于正极浆料中固体组份的总质量，添加剂的质量百分含量；Ws％表示基于正极活性 材料层的总质量，正极活性材料层中硅元素的质量百分含量；Ws 1％表示基于正极活性材料层的第一层的总质量，第一层中硅元素的质量百分含量，Ws 2％表示基于正极活性材料层的第二层的总质量，第二层中硅元素的质量百分含量；Hμm表示正极活性材料层的厚度。
电解液的制备
将碳酸乙烯酯(EC)、碳酸甲乙酯(EMC)及碳酸二乙酯(DEC)按照体积比为1:1:1进行混合，得到有机溶剂；将LiPF 6溶解在上述有机溶剂中，再加入氟代碳酸乙烯酯(FEC)混合均匀，得到电解液。其中，LiPF 6的浓度为1mol/L，基于电解液的总质量，氟代碳酸乙烯酯的质量百分含量为5％。
隔离膜的制备
采用厚度为14μm的多孔聚丙烯膜(来自Celgard公司)作为隔离膜。
二次电池的制备
将正极极片、隔离膜、负极极片按顺序堆叠并卷绕得到电极组件，将电极组件放入外包装中，加入上述电解液，经封装、静置化成、整形等工序后，得到二次电池。
对比例1-1至1-4
基于实施例1-1至实施例1-7的制备过程，根据表1-1所示，调整正极极片所用的添加剂种类，制备对比例1-4至1-4的二次电池。
实施例24至2-18
基于实施例1-1至实施例1-7的制备过程，根据表1-2所示，调整正极极片的制备参数，制备实施例2-1至2-18的二次电池。
实施例34至347
基于实施例1-1至实施例1-7的制备过程，根据表1-3所示，调整正极极片的制备参数，制备实施例3-1至3-17的二次电池。
实施例44至4-2
负极极片的制备
将石墨、粘结剂丁苯橡胶(SBR)、导电剂炭黑、增稠剂羧甲基纤维素钠(CMC-Na)按照质量比97.4:1.2:1.4进行混合，加入适量的溶剂去离子水，充分搅拌均匀后，加入添加剂，混合均匀后得到负极浆料；将负极浆料均匀涂覆在负极集流体铜箔的两个表面上；然后经过120℃烘箱干燥、冷压、分切等，得到负极极片。
实施例4-1至实施例4-2的负极极片制备参数分别如表4-1所示，表4-1中，W’％表示基于负极浆料中固体组份的总质量，添加剂的质量百分含量；W’s％表示基于负极活性材料层的总质量，负极活性材料层中硅元素的质量百分含量；W’s 1％表示基于负极活性材料层的第一层的总质量，第一层中硅元素的质量百分含量，W’s 2％表示基于负极活性材料层的第二层的总质量，第二层中硅元素的质量百分含量；H’表示负极活性材料层的厚度。
正极极片的制备
将正极活性材料磷酸铁锂、粘结剂PVDF、导电剂炭黑按照质量比96:2:2进行混合，加入适量的溶剂NMP，充分搅拌均匀后得到正极浆料；将正极浆料均匀涂覆在正极 集流体铝箔的两个表面上；然后经120℃烘箱干燥、冷压、分切等，得到正极极片。
实施例4-1至4-2中，电解液、隔离膜及二次电池的制备过程与实施例1-1至1-7相同。
实施例54至5-2
负极极片的制备
将石墨、粘结剂丁苯橡胶(SBR)、导电剂炭黑、增稠剂羧甲基纤维素钠(CMC-Na)按照质量比97.4:1.2:1.4进行混合，加入适量的溶剂去离子水，充分搅拌均匀后，加入添加剂，混合均匀后得到负极浆料；将负极浆料均匀涂覆在负极集流体铜箔的两个表面上；然后经过120℃烘箱干燥、冷压、分切等，得到负极极片。
正极极片的制备
将正极活性材料磷酸铁锂、粘结剂PVDF、导电剂炭黑按照质量比96:2:2进行混合，加入适量的溶剂NMP，充分搅拌均匀后，加入添加剂，混合均匀后得到正极浆料；将正极浆料均匀涂覆在正极集流体铝箔的两个表面上；然后经120℃烘箱干燥、冷压、分切等，得到正极极片。
实施例5-1至5-2中，电解液、隔离膜及二次电池的制备过程与实施例1-1至1-7相同。
实施例5-1至5-2的制备参数如表1-5所示，表1-5中，W、W’、Ws、W’s、Ws 1、W’s 1、Ws 2、W’s 2、H、H’分别如前面所定义。
对比例5-1
基于实施例5-1至实施例5-2的制备过程，根据表1-5所示，调整添加剂的种类，制备对比例5-1的二次电池。
各实施例及对比例所用的添加剂分别如下式A至式J所示。
Figure PCTCN2022114280-appb-000001
Figure PCTCN2022114280-appb-000002
测试部分
电极极片的测试
(1)活性材料层中硅元素的质量百分含量的测定
取样方法：将电池放电至0％SOC后，拆解；取对应的电极极片，在通风橱中自然晾干；然后使用刀片分别将上层(第一层)和下层粉末(第二次)刮下后，使用ICP测试硅 元素含量，分别得到Ws 1和Ws 2，或者W’s 1和W’s 2。
将上层粉末和下层粉末混合后，使用ICP测试得到Ws或W’s。。
(2)活性材料层的红外光谱测试
测试方法：参考GB/T 21186-2007
取样方法：将电池放电至0％SOC后，拆解。取电极极片，在通风橱中自然晾干。然后使用刀片将极片的活性材料层刮下，用NMP浸泡后离心并抽滤，取过滤后的清液，将清液加热烘干至≤5mL后测试红外。
各实施例及对比例中，1700cm -1至1600cm -1的特征峰的数量N1、位于1280cm -1至1210cm -1的特征峰的数量N2以及位于1200cm -1至1000cm -1的特征峰的数量N3分别如表2所示。
(3)导电炭黑二次颗粒在活性材料层的截面的分布情况测试
测试仪器：赛默飞Apreo S
将冷压后的电极极片，随机选取区域，进行截面抛光处理，并拍摄背散射SEM图(BS-SEM)，放大倍数为1000倍；采用IMAGE J对BS-SEM进行图像处理，调整合适的对比度(图5)，直至能够清楚地看到导电炭黑二次颗粒的轮廓(图6)，扣除背景色(图7)；使用软件统计截面中每个导电炭黑二次颗粒的面积(图8)，计算得到导电炭黑二次颗粒在活性材料层的截面的分布情况。
导电炭黑二次颗粒的截面积记为Swμm 2，各实施例及对比例中，含有添加剂的电极极片中，每0.01mm 2内活性材料层的截面中，截面积不同的导电炭黑二次颗粒的数量如表2所示。
(4)电极极片的裂纹宽度测试
测试仪器：电荷耦合器件CCD(基恩士VHX5000)
将冷压后的电极极片裁取10*10cm的小方片(需包含电极极片裂纹)，使用玻璃片将小方片固定在载物台上，倍数设置为×100，调节焦距至画面清晰后，水平/上下移动载物台，将裂纹最宽处置于视野正中间，调节大倍数(×300，×500或更高，视裂纹大小决定)，使用测量工具对裂纹宽度进行测量。
各实施例及对比例中，分别测量含有添加剂的正极极片及负极极片的裂纹宽度，以最大值作为电极极片的裂纹宽度d mm，测试结果如表2所示。
二次电池的测试
(1)挤压测试
参考GB31241-2014 7.6中的测试标准，对二次电池进行挤压测试。每组实施例或对比例各测试10个二次电池，二次电池在测试过程中不起火不爆炸为通过，记录通过二次电池的数量，并以“通过数量/总测试数量”方式记录挤压测试通过率。
(2)针刺测试
将电池满充(100％SOC)后，静置1h，并测试OCV/IMP；以
Figure PCTCN2022114280-appb-000003
钉子对二次电池进行穿钉，穿钉位置为电芯对角连线的交点处，穿钉深度为15mm(钉子的尖端到钉子的主体位置)，针刺速度：150mm/s，角度：90度，观察电池是否发生起火或爆炸。
每组实施例或对比例各测试10个二次电池，二次电池在测试过程中不起火且不爆 炸为通过，记录通过二次电池的数量，并以“通过数量/总测试数量”方式记录针刺测试通过率。
表1-1至1-5及表2中，“/”表示未进行相应的处理，或相应的参数无法测得。
表1-1
序号 添加剂 W W S H 300*W 560*W Ws 1 Ws 2 Ws 1/Ws 2
实施例1-1 式A 0.2 0.0140 100 60 112 0.016 0.012 1.35
实施例1-2 式B 0.2 0.0140 100 60 112 0.016 0.012 1.35
实施例1-3 式C 0.2 0.0140 100 60 112 0.016 0.012 1.35
实施例1-4 式D 0.2 0.0140 100 60 112 0.016 0.012 1.35
实施例1-5 式E 0.2 0.0140 100 60 112 0.016 0.012 1.35
实施例1-6 式F 0.2 0.0140 100 60 112 0.016 0.012 1.35
实施例1-7 式G 0.2 0.0140 100 60 112 0.016 0.012 1.35
对比例1-1 式H 0.2 0.0140 100 60 112 0.016 0.012 1.35
对比例1-2 式I 0.2 0.0140 100 60 112 0.016 0.012 1.35
对比例1-3 式J 0.2 0.0140 100 60 112 0.016 0.012 1.35
对比例1-4 式K 0.2 0.0140 100 60 112 0.016 0.012 1.35
表1-2
序号 添加剂 W W S H 300*W 560*W Ws 1 Ws 2 Ws 1/Ws 2
实施例2-1 式A 0.01 0.0007 100 3 5.6 0.001 0.001 1.35
实施例2-2 式A 0.05 0.0035 100 15 28 0.004 0.003 1.35
实施例2-3 式A 0.1 0.0070 100 30 56 0.008 0.006 1.35
实施例2-4 式A 0.2 0.0140 100 60 112 0.016 0.012 1.35
实施例2-5 式A 0.25 0.0175 100 75 140 0.020 0.015 1.35
实施例2-6 式A 0.3 0.0210 100 90 168 0.024 0.018 1.35
实施例2-7 式A 0.4 0.0280 100 120 224 0.032 0.024 1.35
实施例2-8 式A 0.5 0.0350 100 150 280 0.040 0.030 1.35
实施例2-9 式A 0.6 0.0420 100 180 336 0.048 0.036 1.35
实施例2-10 式B 0.1 0.0070 100 30 56 0.008 0.006 1.35
实施例2-11 式B 0.2 0.0140 100 60 112 0.016 0.012 1.35
实施例2-12 式B 0.25 0.0175 100 75 140 0.020 0.015 1.35
实施例2-13 式B 0.3 0.0210 100 90 168 0.024 0.018 1.35
实施例2-14 式B 0.4 0.0280 100 120 224 0.032 0.024 1.35
实施例2-15 式B 0.5 0.0350 100 150 280 0.040 0.030 1.35
实施例2-16 式B 0.6 0.0420 100 180 336 0.048 0.036 1.35
实施例2-17 式A 0.7 0.0490 100 210 392 0.056 0.042 1.35
实施例2-18 式B 0.7 0.0490 100 210 392 0.056 0.042 1.35
表1-3
序号 添加剂 W W S H 300*W 560*W Ws 1 Ws 2 Ws 1/Ws 2
实施例3-1 式A 0.1 0.0070 50 30 56 0.05 0.02 2.5
实施例3-2 式A 0.2 0.0140 60 60 112 0.1 0.05 2
实施例3-3 式A 0.2 0.0140 72 60 112 0.1 0.05 2
实施例3-4 式A 0.4 0.0280 140 120 224 0.35 0.05 7
实施例3-5 式A 0.4 0.0280 140 120 224 0.2 0.2 1.0
实施例3-6 式A 0.6 0.0420 200 180 336 0.3 0.27 1.1
实施例3-7 式A 0.6 0.0420 250 180 336 0.5 0.005 100
实施例3-8 式A 0.6 0.0420 280 180 336 0.5 0.005 100
实施例3-9 式A 0.4 0.0280 100 120 224 0.3 0.27 1.1
实施例3-10 式A 0.2 0.0140 150 60 112 0.1 0.05 2
实施例3-11 式A 0.2 0.0140 200 60 112 0.016 0.012 1.35
实施例3-12 式B 0.1 0.0070 50 30 56 0.008 0.006 1.35
实施例3-13 式B 0.2 0.0140 60 60 112 0.016 0.012 1.35
实施例3-14 式B 0.2 0.0140 140 60 112 0.016 0.012 1.35
实施例3-15 式B 0.4 0.0280 200 120 224 0.032 0.024 1.35
实施例3-16 式B 0.4 0.0280 180 120 224 0.032 0.024 1.35
实施例3-17 式B 0.6 0.0420 280 180 336 0.048 0.036 1.35
表1-4
序号 添加剂 W’ W’ S H’ 300*W’ 560*W’ W’s 1 W’s 2 W’s 1/W’s 2
实施例4-1 式A 0.2 0.014 100 4.2 7.84 0.0161 0.0119 1.35
实施例4-2 式A 0.4 0.028 100 8.4 15.68 0.0322 0.0238 1.35
Figure PCTCN2022114280-appb-000004
Figure PCTCN2022114280-appb-000005
Figure PCTCN2022114280-appb-000006
综合表1-1及表2可知，在活性材料层中包括两亲添加剂，能够有效降低活性材料层经冷压后发生开裂的风险，并显著提升二次电池的安全性能。尤其是，当两亲添加剂的的分子中同时具有Si-O-C键和C＝N键时，能够进一步提升二次电池的安全性能。
综合表1-2及表2可知，随着两亲添加剂在活性材料层中含量的增加，二次电池的安全性能呈先升高后降低的趋势。两亲添加剂在活性材料层中的质量百分含量在0.1％至0.6％时，一方面，活性材料层不易开裂，从而允许二次电池具备高能量密度；另一方面，二次电池能够具备优异的安全性能。
综合表1-3及表2可知，实施例3-1至3-8及实施例3-12至3-17满足300*W≤H≤560*W，从而能够进一步提升二次电池的安全性能。相对于此，实施例3-9至3-11不满足300*W≤H≤560*W，二次电池的安全性能稍有下降。
综合表1-1至1-5及表2可知，两亲添加剂在正极活性材料层和负极活性材料层中能够发挥类似的效果，从而提升二次电池的安全性能。
以上所述，仅为本申请的具体实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到各种等效的修改或替换，这些修改或替换都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以权利要求的保护范围为准。

Claims (13)

  1. 一种电极极片，包括：
    集流体；以及
    位于所述集流体至少一个表面的活性材料层，所述活性材料层包括活性材料以及两亲添加剂，所述两亲添加剂包括包含Si-O-C键的两亲化合物。
  2. 根据权利要求1所述的电极极片，其中，所述包含Si-O-C键的两亲化合物还包含C＝N键。
  3. 根据权利要求1或2所述的电极极片，其中，所述活性材料层满足如下至少一者：
    (1)所述活性材料层的红外光谱具有位于1700cm -1至1600cm -1的特征峰、位于1280cm -1至1210cm -1的特征峰以及位于1200cm -1至1000cm -1的特征峰；
    (2)所述活性材料层的红外光谱具有2个位于1200cm -1至1000cm -1的特征峰。
  4. 根据权利要求1至3中任一项所述的电极极片，其中，所述两亲添加剂包括式1所示的化合物，
    (R’ 2N) 2C＝N(CH 2) 3-Si-(O-R) 3  式1
    在式1中，R和R’各自独立地选自碳原子数为1～5的烷基。
  5. 根据权利要求4所述的电极极片，其中，所述活性材料层满足如下至少一者：
    (3)0.1≤W≤0.6，其中，W％表示基于所述活性材料层的总质量，所述两亲添加剂的质量百分含量；
    (4)0.01≤Ws≤0.2，其中，Ws％表示基于所述活性材料层的总质量，硅元素的质量百分含量。
  6. 根据权利要求5中所述的电极极片，其中，所述活性材料层满足：300*W≤H≤560*W，且50≤H≤280，其中，Hμm表示单面所述活性材料层的厚度。
  7. 根据权利要求1至6中任一项所述的电极极片，其中，所述活性材料层沿自身厚度方向包括远离所述集流体表面的第一层和靠近所述集流体表面的第二层，所述第一层和所述第二层的厚度相等，
    所述活性材料层满足：1.1≤Ws 1/Ws 2≤100，其中，Ws 1％表示基于所述第一层的总质量，所述第一层中硅元素的质量百分含量；Ws 2％表示基于所述第二层的总质量，所述第二层中硅元素的质量百分含量。
  8. 根据权利要求7所述的电极极片，其中，所述活性材料层满足：1.1≤Ws 1/Ws 2≤10。
  9. 根据权利要求7或8所述的电极极片，其中，0.01≤Ws 1≤0.3，且0≤Ws 2≤0.27。
  10. 根据权利要求1至9中任一项所述的电极极片，其中，所述活性材料层还包括导电剂，所述导电剂包括导电炭黑二次颗粒，所述活性材料层的截面满足如下至少一者：
    (5)每0.01mm 2内，截面积≥5μm 2的所述导电炭黑二次颗粒的数量≤2；
    (6)每0.01mm 2内，截面积为0.1μm 2至1μm 2的所述导电炭黑二次颗粒的数量≤4。
  11. 一种电化学装置，包括正极极片和负极极片，所述正极极片和/或所述负极极片选自根据权利要求1至10中任一项所述的电极极片。
  12. 根据权利要求11所述的电化学装置，其中，所述正极极片和负极极片选自根据权利要求1至10中任一项所述的电极极片，所述电化学装置满足0.1≤Ws 3/Ws 4≤10，其中，
    Ws 3％表示基于正极活性材料层的总质量，正极活性材料层中硅元素的质量百分含量；
    Ws 4％表示基于负极活性材料层的总质量，负极活性材料层中硅元素的质量百分含量。
  13. 一种用电装置，包括根据权利要求11或12所述的电化学装置。
PCT/CN2022/114280 2022-08-23 2022-08-23 电极极片、电化学装置及用电装置 WO2024040437A1 (zh)

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CN113540468A (zh) * 2021-07-26 2021-10-22 珠海冠宇电池股份有限公司 负极片及电池
CN114203962A (zh) * 2021-12-13 2022-03-18 珠海冠宇动力电池有限公司 极片、电芯及电池

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