WO2024016097A1 - Batterie secondaire, module de batterie, bloc-batterie et dispositif électrique - Google Patents

Batterie secondaire, module de batterie, bloc-batterie et dispositif électrique Download PDF

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WO2024016097A1
WO2024016097A1 PCT/CN2022/106172 CN2022106172W WO2024016097A1 WO 2024016097 A1 WO2024016097 A1 WO 2024016097A1 CN 2022106172 W CN2022106172 W CN 2022106172W WO 2024016097 A1 WO2024016097 A1 WO 2024016097A1
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positive electrode
secondary battery
current collector
lithium
conductive coating
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PCT/CN2022/106172
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English (en)
Chinese (zh)
Inventor
张翠平
韩昌隆
范朋
吴则利
黄磊
陈慧玲
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宁德时代新能源科技股份有限公司
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Priority to PCT/CN2022/106172 priority Critical patent/WO2024016097A1/fr
Publication of WO2024016097A1 publication Critical patent/WO2024016097A1/fr

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0568—Liquid materials characterised by the solutes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to the field of batteries, and specifically to a secondary battery, a battery module, a battery pack and an electrical device.
  • Secondary batteries have the characteristics of high capacity and long life, so they are widely used in electronic equipment, such as mobile phones, laptop computers, battery cars, electric cars, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes and electric tools etc.
  • This application was made in view of the above-mentioned issues, and its purpose is to provide a secondary battery, a battery module, a battery pack, and an electrical device that can improve both service life, safety performance, and energy density while ensuring Safety performance of secondary batteries.
  • a first aspect of the present application provides a secondary battery;
  • the secondary battery includes a positive electrode sheet and an electrolyte;
  • the positive electrode sheet includes a positive electrode current collector, a positive electrode film layer disposed on at least one surface of the positive electrode current collector, and A conductive coating disposed between the positive electrode current collector and the positive electrode film layer;
  • the electrolyte includes lithium hexafluorophosphate and fluorine-containing lithium sulfonylimide; wherein, the area of the conductive coating is S 1 mm 2 and the area of the positive electrode film layer is S 2 mm 2 ; the molar concentration of lithium hexafluorophosphate is C 1 mol/L, and the molar concentration of lithium fluorosulfonimide is C 2 mol/L; the secondary battery satisfies: -0.15 ⁇ S1/S2-C2/(10C1) ⁇ 0.8 ;Optionally, 0 ⁇ S 1 /S 2 -C 2 /(10C 1 ) ⁇
  • This application satisfies the above formula so that the conductive coating can play a good protective role on the positive electrode current collector and reduce the risk of corrosion of the positive electrode current collector, thereby ensuring the structural stability of the positive electrode current collector and extending the cycle life of the secondary battery, and It can improve the safety performance of secondary batteries; the conductive coating will not be over-coated on the positive electrode current collector, thereby ensuring the occupied volume of the positive electrode film layer, thereby ensuring the energy density of the secondary battery.
  • the area S 1 mm 2 of the conductive coating and the area S 2 mm 2 of the positive electrode film layer satisfy: 5% ⁇ S 1 /S 2 ⁇ 95%; optionally, 50% ⁇ S 1 /S 2 ⁇ 90%.
  • the area of the conductive coating is smaller than that of the positive electrode film.
  • the conductive coating does not cover the entire cathode current collector.
  • the conductive coating occupies a smaller volume, which can increase the occupied volume of the cathode film, thereby further improving the secondary efficiency. Battery energy density.
  • the thickness of the conductive coating is d ⁇ m; the thickness of the positive electrode film layer is L 1 ⁇ m, and the relationship between d and L 1 satisfies: 1/200 ⁇ d/L 1 ⁇ 1/30; optionally, 1 /50 ⁇ d/L 1 ⁇ 1/100.
  • This application can improve the bonding strength between the conductive coating and the cathode film layer by regulating the ratio between the thickness of the conductive coating and the thickness of the cathode film layer, and while the conductive coating plays a role in protecting the cathode current collector, It will not occupy too much volume, thereby ensuring the occupied volume of the positive electrode film layer, thereby further improving the energy density of the secondary battery.
  • the thickness of the conductive coating is d ⁇ m; the thickness of the cathode current collector is L 2 ⁇ m, and the relationship between d and L 2 satisfies: 1/26 ⁇ d/L 2 ⁇ 1/2.6; optionally, 1 /26 ⁇ d/L 2 ⁇ 1/8.
  • This application can improve the protective effect of the conductive coating on the cathode current collector by regulating the ratio between the thickness of the conductive coating and the thickness of the cathode current collector without forming excessive internal resistance, ensuring the electrochemistry of the secondary battery. performance.
  • the conductive coating includes a conductive agent and a binder.
  • the mass content of the conductive agent is W 1 %, based on the total mass of the conductive coating; the mass content of the binder is W 2 %, based on the conductive coating. Based on the total mass of the layer, 40 ⁇ W 1 ⁇ 80 and 20 ⁇ W 2 ⁇ 60.
  • the conductive agent includes one or more of conductive carbon black, conductive graphite, single-wall carbon nanotubes, multi-wall carbon nanotubes, and graphene; and/or the binder includes polyvinylidene fluoride , one or more of polyacrylonitrile, polyacrylate, epoxy resin conductive adhesive and phenolic resin conductive adhesive.
  • the conductive agent of the above-mentioned materials can provide good conductive properties and is the same as or similar to the conductive agent in the positive electrode film layer, which can improve the connection strength with the positive electrode film layer; on the other hand, during the film formation process of the conductive slurry It will basically not cause damage to the cathode current collector and can ensure the structural stability of the cathode current collector.
  • the positive electrode current collector includes metal; optionally, the positive electrode current collector includes aluminum foil or aluminum alloy foil; further optionally, the thickness of the aluminum foil is 8 ⁇ m to 20 ⁇ m.
  • the molar concentration C 1 mol/L of lithium hexafluorophosphate and the molar concentration C 2 mol/L of lithium fluorine-containing sulfonylimide satisfy: 1 ⁇ C 2 /C 1 ⁇ 5; optionally, 2 ⁇ C 2 /C 1 ⁇ 4.5.
  • This application regulates C 2 /C 1 to meet the above range, which can ensure excellent ion conductivity of the electrolyte and good thermal stability; and the combination of the lithium salt in the above range and the conductive coating can reduce the impact of lithium salt on The corrosion effect of the positive electrode current collector further ensures the safety performance of the secondary battery.
  • the molar concentration C 1 mol/L of lithium hexafluorophosphate and the molar concentration C 2 mol/L of lithium fluorine-containing sulfonylimide also satisfies: 0.6 ⁇ C 1 +C 2 ⁇ 2; optionally, 1.2 ⁇ C 1 +C 2 ⁇ 2; optionally, the molar concentration of lithium hexafluorophosphate C 1 mol/L satisfies: 0.1 ⁇ C 1 ⁇ 1; optionally, the molar concentration of lithium fluorosulfonyl imide C 2 mol/ L satisfies: 0.5 ⁇ C 2 ⁇ 1.5.
  • this application regulates C 1 + C 2 in the above range the concentration of lithium salt in the electrolyte can be ensured, thereby providing sufficient conductivity for the transmission of lithium ions.
  • the fluorine-containing lithium sulfonyl imide includes a compound represented by Formula I,
  • R1 and R2 are each independently selected from a fluorine atom or a fluorinated C1-C4 alkyl group.
  • the compound represented by Formula I has good thermal stability. When used in conjunction with a conductive coating, the conductive coating can effectively reduce the impact of the compound represented by Formula I on the cathode current collector and ensure the structural stability of the cathode current collector. , improve the safety performance of secondary batteries.
  • the fluorine-containing lithium sulfonyl imide includes lithium bisfluorosulfonyl imide LiFSI, lithium bistrifluoromethanesulfonyl imide LiTFSI, and lithium (fluorosulfonyl)(trifluoromethanesulfonyl)imide
  • LiFSI lithium bisfluorosulfonyl imide
  • LiTFSI lithium bistrifluoromethanesulfonyl imide
  • Li (fluorosulfonyl)(trifluoromethanesulfonyl)imide One or more of LiFTFSI and lithium (fluorosulfonyl)(perfluorobutylsulfonyl)imide LiFNFSI.
  • the electrolyte further includes one or more of carbonate additives, sulfate additives and sulfite additives; optionally, the carbonate additives include cyclic carbonate additives and/ Or linear carbonate additives; further, cyclic carbonate additives include vinylene carbonate VC, fluoroethylene carbonate FEC, difluoroethylene carbonate DFEC, vinyl ethylene carbonate VEC and dioctyl carbonate CC One or more of; and/or linear carbonate additives include one or more of ethyl allyl carbonate AEC and diphenyl carbonate DPC; optionally, sulfate additives include cyclic sulfonate Acid ester additives and/or sulfate hydrocarbon ester additives; further, cyclic sulfonate additives include 1,3-propane sultone PS, propylene sultone PES, 3-fluoro-1,3- One or more of propanesultone FPS; and/
  • the above additives can form an interface film on the surface of the negative electrode film layer and/or the positive electrode film layer, thereby protecting the active material, improving the structural stability of the negative electrode film layer and the positive electrode film layer, and thereby improving the cycle performance of the secondary battery. .
  • a second aspect of the application also provides a battery module, including the secondary battery according to any embodiment of the first aspect of the application.
  • a third aspect of the present application also provides a battery pack, including the battery module according to the embodiment of the second aspect of the present application.
  • a fourth aspect of the present application also provides an electrical device, including a secondary battery as in the first aspect of the present application, a battery module as in the second aspect of the present application, or a battery as in the third aspect of the present application. Bag.
  • Figure 1 is a schematic diagram of a positive electrode plate according to an embodiment of the present application.
  • Figure 2 is a schematic cross-sectional view of the positive electrode plate shown in Figure 1 along line A-A;
  • FIG. 3 is a schematic diagram of an electrode assembly according to an embodiment of the present application.
  • Figure 4 is a schematic diagram of a secondary battery according to an embodiment of the present application.
  • Figure 5 is an exploded view of the secondary battery according to an embodiment of the present application shown in Figure 4;
  • FIG. 6 is a schematic diagram of a battery module according to an embodiment of the present application.
  • Figure 7 is a schematic diagram of a battery pack according to an embodiment of the present application.
  • Figure 8 is an exploded view of the battery pack according to an embodiment of the present application shown in Figure 7;
  • Figure 9 is a schematic diagram of an electrical device according to an embodiment of the present application.
  • Ranges as disclosed herein are defined in terms of lower and upper limits. A given range is defined by selecting a lower limit and an upper limit that define the boundaries of the particular range. Ranges defined in this manner may be inclusive or exclusive of the endpoints, and may be arbitrarily combined, that is, any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, understand that ranges of 60-110 and 80-120 are also expected. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2- 3, 2-4 and 2-5.
  • the numerical range “a-b” represents an abbreviated representation of any combination of real numbers between a and b, where a and b are both real numbers.
  • the numerical range “0-5" means that all real numbers between "0-5" have been listed in this article, and "0-5" is just an abbreviation of these numerical combinations.
  • a certain parameter is an integer ⁇ 2
  • a method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially.
  • step (c) means that step (c) can be added to the method in any order.
  • the method may include steps (a), (b) and (c), and may also include step (a). , (c) and (b), and may also include steps (c), (a) and (b), etc.
  • condition "A or B” is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists) ; Or both A and B are true (or exist).
  • the secondary battery may include a lithium-ion battery, a lithium-sulfur battery, a sodium-lithium-ion battery, a sodium-ion battery or a magnesium-ion battery, etc., which are not limited in the embodiments of this application.
  • the secondary battery includes an electrode assembly and an electrolyte.
  • the electrode assembly consists of a positive electrode plate, a negative electrode plate and a separator.
  • the secondary battery mainly relies on the movement of metal ions between the positive electrode piece and the negative electrode piece.
  • the positive electrode piece includes the positive electrode film layer
  • the negative electrode piece includes the negative electrode film layer.
  • the metal ions can be lithium ions, sodium ions, etc.
  • the preparation process of the positive electrode sheet is as follows: after the positive electrode slurry containing the positive electrode active material is evenly dispersed, it is coated on the surface of the positive electrode current collector, and then dried, cold pressed and other processes to form a positive electrode film layer. Since the positive active material is granular, during the cold pressing process, the positive active material may cause damage to the positive current collector, exposing the metal material of the positive current collector. The metal material is prone to side reactions with the electrolyte in the secondary battery, which in turn causes further corrosion and damage to the metal material. As a result, the structure of the positive electrode current collector is destroyed or even the pole piece is broken, seriously deteriorating the cycle of the secondary battery. performance, and may introduce security risks.
  • the surface of the aluminum foil is easy to form an oxide film of aluminum oxide. Since aluminum oxide is chemically inert, it is not easy to have side reactions with other chemicals such as electrolytes, thereby affecting the overall integrity of the aluminum foil. Play a good protective role. During the process of cold pressing the cathode slurry, the particles of the cathode active material may destroy the passivation film formed by the aluminum oxide on the aluminum foil, thereby exposing the metallic aluminum in the aluminum foil. Metallic aluminum is prone to side reactions with the electrolyte. This further promotes corrosion of metal aluminum.
  • a conductive layer is formed on the surface of the positive electrode current collector, which can be used as a protective coating to protect the positive electrode current collector, reduce the risk of damage to the positive electrode current collector, and cause the structural stability of the positive electrode plate to be destroyed. This will worsen the cycle life of the secondary battery; and the damaged positive electrode current collector may pierce the isolation film and come into contact with the negative electrode piece, causing a short circuit, thereby posing a safety risk to the secondary battery.
  • the protective coating due to the installation of the protective coating, it occupies a relatively large volume, which will reduce the occupied volume of the positive electrode film layer, thereby possibly reducing the energy density of the secondary battery to a great extent.
  • the inventor improved the secondary battery and proposed a secondary battery, which will be described in detail below.
  • this application proposes a secondary battery.
  • the secondary battery includes a positive electrode sheet 521 and an electrolyte;
  • the positive electrode sheet 521 includes a positive electrode current collector 5211, a positive electrode film layer 5213 disposed on at least one surface of the positive electrode current collector 5211, and A conductive coating 5212 disposed between the positive electrode current collector 5211 and the positive electrode film layer 5213;
  • the electrolyte includes lithium hexafluorophosphate and fluorine-containing lithium sulfonylimide, wherein the area of the conductive coating 5212 is S 1 mm 2 and the positive electrode film layer 5213 The area of is S 2 mm 2 ;
  • the molar concentration of lithium hexafluorophosphate is C 1 mol/L, and the molar concentration of lithium fluorosulfonyl imide is C 2 mol/L;
  • S 1 , S 2 , C 1 and C 2 satisfy : -0.15 ⁇ S 1 /S 2 -C 2 /(10C 1 ) ⁇ 0.8.
  • the positive electrode current collector 5211 includes two surfaces opposite to each other along its own thickness direction, and the positive electrode film layer 5213 is provided on at least one of the two surfaces.
  • the positive electrode film layer 5213 is provided on both surfaces or in both surfaces. one of them.
  • the positive electrode current collector 5211 includes a coating area, which is used to coat the positive electrode slurry to form a positive electrode film layer 5213. It can be understood that the area of the coating area of the positive electrode current collector 5211 is the same as the area of the positive electrode film layer 5213 .
  • the positive electrode current collector 5211 may also include a tab area. The tab area may not be coated with the cathode slurry, and the tab area may be used to connect with the tab. In other embodiments, the positive electrode current collector 5211 may not include a tab area, that is, the surface of the positive electrode current collector 5211 may be coated with the positive electrode slurry.
  • the area S 1 of the conductive coating 5212 has a meaning known in the art, and can be measured using testing instruments and testing methods known in the art.
  • the solvent contained in the positive electrode slurry can be used to dissolve different areas of the positive electrode film layer 5213, and elemental analysis can be performed on the materials in the remaining areas after the dissolution to determine whether the conductive coating 5212 is included in this area, thereby determining the conductive coating 5212. area.
  • the conductive coating 5212 is conductive and can guide the current in the positive electrode film layer 5213 to the positive electrode current collector 5211. Of course, it can also guide the current from the positive electrode current collector 5211 to the positive electrode film layer 5213, thereby ensuring the smooth charging and discharging of the secondary battery. conduct.
  • the conductive coating 5212 can be continuously distributed on the surface of the positive electrode current collector 5211, or can be discretely distributed on the surface of the positive electrode current collector 5211.
  • the conductive coating 5212 is disposed on the surface of the positive electrode current collector 5211, which can separate part of the positive electrode slurry and the positive electrode current collector 5211, thereby reducing damage to the positive electrode current collector 5211 caused by particles of the positive electrode slurry during the cold pressing process of the positive electrode slurry. , which plays a protective role in the positive electrode current collector 5211.
  • the positive electrode current collector 5211 including aluminum foil as an example for illustration, the oxide film of aluminum trioxide formed on the surface of the aluminum foil can protect the positive electrode current collector 5211.
  • the oxide film formed by aluminum oxide is not easily destroyed by the positive active material, thereby ensuring the integrity of the oxide film, thereby ensuring good protection of the positive electrode current collector 5211, so that the secondary The battery ensures cycle stability during the charge and discharge cycle, thereby improving both the cycle life and safety performance of the secondary battery.
  • Lithium salts in the electrolyte will be oxidized during the charging process.
  • the anions of the oxidation product will react with the aluminum foil and produce by-products that will dissolve in the electrolyte, thus causing certain corrosion to the aluminum foil. and can deteriorate the performance of the electrolyte.
  • the conductive coating 5212 can effectively isolate the electrolyte from the positive electrode current collector 5211, thereby reducing the risk of corrosion of the positive electrode current collector 5211 by fluorinated sulfonylimide lithium and further damaging the positive electrode current collector. Fluid 5211 plays a protective role and ensures the performance of the electrolyte.
  • this application can make the conductive coating 5212 play a good protective role on the positive electrode current collector 5211 and reduce the risk of corrosion of the positive electrode current collector 5211, thereby ensuring The structural stability of the positive electrode current collector 5211 extends the cycle life of the secondary battery and improves the safety performance of the secondary battery; the conductive coating 5212 will not be over-coated on the positive electrode current collector 5211, thereby ensuring the safety of the positive electrode film layer 5213 Occupying volume, thereby ensuring the energy density of the secondary battery.
  • S 1 /S 2 -C 2 /(10C 1 ) can be -0.15, -0.1, 0, 0.1, 0.3, 0.4, 0.5, 0.6, 0.7 or 0.75; or it can be composed of any two of the above values scope.
  • the positive electrode sheet 521 includes a positive current collector 5211 and a positive electrode film layer 5213 disposed on at least one surface of the positive current collector 5211 .
  • the positive electrode current collector 5211 has two surfaces opposite in its thickness direction, and the positive electrode film layer 5213 is provided on any one or both of the two opposite surfaces of the positive electrode current collector 5211; the positive electrode plate 521 also includes a conductive coating. Layer 5212; the conductive coating 5212 is provided between the positive electrode current collector 5211 and the positive electrode film layer 5213.
  • the conductive coating 5212 is discretely distributed on the surface of the cathode current collector 5211.
  • the discrete distribution means that the conductive coating 5212 has a discontinuous coating structure; specifically, the discrete distribution can mean that most areas of the conductive coating 5212 have a discontinuous coating structure, and a small area has a continuous coating structure. form; or a small area of the conductive coating 5212 is in the form of a discontinuous coating structure, and most of the area is in the form of a continuous coating structure.
  • the discrete distribution of the conductive coating 5212 can better protect the entire positive electrode current collector 5211; and the conductive coating 5212 has a relatively small coating area and occupies a relatively small volume; accordingly, the positive electrode film layer 5213 can be improved occupied volume, thereby increasing the energy density of secondary batteries.
  • the area S 1 mm 2 of the conductive coating 5212 and the area S 2 mm 2 of the positive electrode film layer 5213 satisfy: 5% ⁇ S 1 /S 2 ⁇ 95%.
  • the area of the conductive coating 5212 is smaller than the area of the positive electrode film layer 5213.
  • the conductive coating 5212 will not cover the entire positive electrode current collector 5211.
  • the conductive coating 5212 occupies a smaller volume, which can increase the occupied volume of the positive electrode film layer 5213. , thereby further improving the energy density of secondary batteries.
  • S 1 /S 2 can be 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 38%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90% or 95%; of course, S 1 /S 2 can also be a range composed of any two of the above values. .
  • the thickness of the conductive coating 5212 may be d ⁇ m; the thickness of the positive electrode film layer 5213 may be L 1 ⁇ m, and the relationship between d and L 1 satisfies: 1/200 ⁇ d/L 1 ⁇ 1/30.
  • This application can improve the bonding strength between the conductive coating 5212 and the positive electrode film layer 5213 by regulating the ratio between the thickness of the conductive coating 5212 and the thickness of the positive electrode film layer 5213, and the conductive coating 5212 plays a role in protecting the positive electrode assembly. While the fluid 5211 acts, it will not occupy too much volume, thereby ensuring that the positive electrode film layer 5213 occupies the volume, thereby further improving the energy density of the secondary battery.
  • d/L 1 can be 1/200, 1/180, 1/150, 1/120, 1/110, 1/100 , 1/80, 1/70, 1/60, 1/50, 1/40 or 1/30; d/L 1 can also be a range composed of any two of the above values.
  • the thickness of the conductive coating 5212 is d ⁇ m; the thickness of the positive electrode current collector 5211 is L 2 ⁇ m, and the relationship between d and L 2 satisfies: 1/26 ⁇ d/L 2 ⁇ 1/2.6.
  • This application can improve the protective effect of the conductive coating 5212 on the cathode current collector 5211 by regulating the ratio between the thickness of the conductive coating 5212 and the thickness of the cathode current collector 5211, without forming excessive internal resistance and ensuring secondary The electrochemical performance of the battery.
  • the conductive coating 5212 includes a conductive agent and a bonding agent; based on the total mass of the conductive coating 5212, the mass content of the conductive agent is W 1 %; based on the total mass of the conductive coating 5212, the bonding agent The mass content of the agent is W 2 %, where 30 ⁇ W 1 ⁇ 60 and 40 ⁇ W 2 ⁇ 70.
  • the conductive agent can electrically connect the positive electrode current collector 5211 and the positive electrode film layer 5213, which is beneficial to transmitting current; the binder can ensure the connection strength between the conductive coating 5212 and the positive electrode current collector 5211, as well as the conductive coating 5212 and the positive electrode film.
  • the connection strength between the layers 5213 reduces the risk of the conductive coating 5212 falling off, thereby ensuring the connection strength between the positive electrode current collector 5211 and the positive electrode film layer 5213.
  • W 1 can be 30, 40, 50 or 60; or it can be a range consisting of any two of the above values.
  • W 2 can be 40, 50, 60 or 70; or a range consisting of any two of the above values.
  • the conductive agent includes one or more of conductive carbon black, conductive graphite, single-walled carbon nanotubes, multi-walled carbon nanotubes, and graphene.
  • the conductive agent of the above-mentioned material can provide good conductive properties, and is the same or similar to the conductive agent in the positive electrode film layer 5213, and can improve the connection strength with the positive electrode film layer 5213; on the other hand, in the composition of the conductive slurry During the membrane process, the positive electrode current collector 5211 will basically not be damaged, and the structural stability of the positive electrode current collector 5211 can be ensured.
  • the adhesive includes one or more of polyvinylidene fluoride, polyacrylonitrile, polyacrylate, epoxy resin conductive glue, and phenolic resin conductive glue.
  • the binder made of the above materials can, on the one hand, ensure good bonding performance to improve the connection strength between the conductive coating 5212 and the positive electrode current collector 5211; and is the same as or similar to the binder in the positive electrode film layer 5213, which can Improve the connection strength with the positive electrode film layer 5213.
  • the positive electrode film layer 5213 includes a positive electrode active material
  • the positive electrode active material may be a positive electrode active material known in the art for secondary batteries.
  • the cathode active material may include one or a combination of more selected from the group consisting of lithium transition metal oxides, olivine-structured lithium-containing phosphates, and their respective modified compounds.
  • the lithium transition metal oxide 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 , lithium nickel cobalt aluminum oxide and a combination of one or more of their respective modified compounds.
  • Examples of the lithium-containing phosphate with an olivine structure may include lithium iron phosphate, a composite material of lithium iron phosphate and carbon, a lithium manganese phosphate, a composite material of lithium manganese phosphate and carbon, a lithium manganese iron phosphate, a lithium manganese iron phosphate and A composite material of carbon and a combination of one or more of its respective modifying compounds.
  • the cathode active material may include a combination of one or more of the lithium transition metal oxide shown in Formula 1 and its modified compounds.
  • M includes Mn, Al, Zr , a combination of one or more of Zn, Cu, Cr, Mg, Fe, V, Ti and B, A includes a combination of one or more selected from N, F, S and Cl.
  • the above-mentioned modified compounds of each cathode active material may be doping modification or surface coating modification of the cathode active material.
  • the positive electrode film layer 5213 optionally further includes a positive electrode conductive agent.
  • a positive electrode conductive agent includes superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon. One or a combination of nanofibers.
  • the mass percentage of the positive electrode conductive agent is less than 5%.
  • the positive electrode film layer 5213 optionally further includes a positive electrode binder.
  • the positive electrode binder may include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene.
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • terpolymer vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer
  • tetrafluoroethylene-hexafluoropropylene copolymer tetrafluoroethylene-hexafluoropropylene copolymer and fluorine-containing acrylate resin.
  • the mass percentage of the positive electrode binder is less than 5%.
  • the positive electrode current collector 5211 may be a metal foil or a composite current collector.
  • the metal foil aluminum foil or aluminum alloy foil can be used.
  • the thickness of the aluminum foil is 8 ⁇ m to 20 ⁇ m. The above thickness of the aluminum foil can ensure the strength of the aluminum foil, thereby ensuring the overall mechanical stability of the positive electrode piece 521.
  • 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 include aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver. and a combination of one or more silver alloys.
  • the polymer material base layer may include polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate ( One or a combination of one or more of PBT), polystyrene (PS) and polyethylene (PE).
  • the positive electrode film layer 5213 is usually formed by coating the positive electrode slurry on the positive electrode current collector 5211, 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.
  • the electrolyte solution of the present application can be an electrolyte solution known in the art and used for secondary batteries.
  • the electrolyte includes lithium salt and organic solvent.
  • the electrolyte plays a role in transporting and conducting metal ions between the positive electrode piece 521 and the negative electrode piece 522 .
  • lithium salts may include lithium hexafluorophosphate (LiPF 6 ) and lithium fluorine-containing sulfonyl imide.
  • the molar concentration C 1 mol/L of lithium hexafluorophosphate and the molar concentration C 2 mol/L of lithium fluorosulfonimide satisfy: 1 ⁇ C 2 /C 1 ⁇ 5; optionally, 2 ⁇ C 2 /C 1 ⁇ 4.5.
  • Lithium salt is the source of ionic conductors in lithium-ion batteries and has a significant impact on the performance of secondary batteries; lithium hexafluorophosphate has high conductivity and can passivate aluminum foil, but its chemical stability is poor and it is easy to decompose at high temperatures; The thermal decomposition temperature of fluorinated sulfonylimide lithium is relatively high, and it is not easy to decompose during the normal charging and discharging process of secondary batteries; the combined use of the above two types of lithium salts can ensure the conductivity of the electrolyte and facilitate the migration of lithium ions; And it can ensure the thermal stability of the electrolyte at the same time, which is beneficial to improving the safety performance of secondary batteries.
  • C 2 /C 1 can be 1, 2, 3, 4, 4.5 or 5; or it can be a range consisting of any two of the above values.
  • the molar concentration C 1 mol/L of lithium hexafluorophosphate and the molar concentration C 2 mol/L of lithium fluorine-containing sulfonylimide also satisfies: 0.6 ⁇ C 1 +C 2 ⁇ 2.
  • C 1 + C 2 can be 0.6 mol/L, 0.8 mol/L, 1.0 mol/L, 1.2 mol/L, 1.5 mol/L, 1.6 mol/L, 1.8 mol/L or 2 mol /L; of course it can also be a range consisting of any two values mentioned above.
  • the molar concentration C 1 mol/L of lithium hexafluorophosphate satisfies: 0.1 ⁇ C 1 ⁇ 1.
  • the electrolyte has high conductivity and high oxidation resistance, has good passivation ability for the positive electrode current collector 5211, and can form a stable electrolyte on the surface of the negative electrode film layer.
  • the electrolyte interface film plays a good protective role in the negative electrode film layer.
  • the molar concentration C 1 mol/L of lithium hexafluorophosphate can be 0.1 mol/L, 0.2 mol/L, 0.3 mol/L, 0.4 mol/L, 0.5 mol/L, 0.6 mol/L, 0.7 mol/L, 0.8mol/L or 1mol/L; or a range consisting of any two of the above values.
  • the molar concentration C 2 mol/L of lithium fluorine-containing sulfonylimide satisfies: 0.5 ⁇ C 2 ⁇ 1.5.
  • the electrolyte has good conductivity, and both thermal stability and electrochemical stability are good.
  • the molar concentration C 2 mol/L of lithium fluorine-containing sulfonylimide can be 0.5mol/L, 0.6mol/L, 0.7mol/L, 0.8mol/L, 0.9mol/L, 1.0mol/L , 1.1mol/L, 1.2mol/L, 1.3mol/L, 1.4mol/L or 1.5mol/L.
  • the fluorine-containing lithium sulfonyl imide includes a compound represented by Formula I,
  • R1 and R2 are each independently selected from a fluorine atom or a fluorinated C1-C4 alkyl group.
  • the compound represented by Formula I has good thermal stability.
  • the conductive coating 5212 can effectively reduce the impact of the compound represented by Formula I on the positive electrode current collector 5211, ensuring that the positive electrode current collector 5211 Structural stability and improved safety performance of secondary batteries.
  • the fluorine-containing lithium sulfonyl imide includes lithium bisfluorosulfonyl imide LiFSI, lithium bistrifluoromethanesulfonyl imide LiTFSI, and lithium (fluorosulfonyl)(trifluoromethanesulfonyl)imide
  • LiFSI lithium bisfluorosulfonyl imide
  • LiTFSI lithium bistrifluoromethanesulfonyl imide
  • Li (fluorosulfonyl)(trifluoromethanesulfonyl)imide One or more of LiFTFSI and lithium (fluorosulfonyl)(perfluorobutylsulfonyl)imide LiFNFSI.
  • the compound represented by formula I when R1 and R2 are both selected from fluorine atoms, the compound represented by formula I is lithium bisfluorosulfonyl imide LiFSI.
  • the compound represented by formula I when R1 and R2 are both selected from -CF 3 , the compound represented by formula I is lithium bistrifluoromethylsulfonimide LiTFSI.
  • the compound represented by formula I when R1 is a fluorine atom and R2 is -CF 3 , the compound represented by formula I is lithium (fluorosulfonyl)(trifluoromethanesulfonyl)imide LiTFSI.
  • the compound represented by the formula I is lithium (fluorosulfonyl)(perfluorobutylsulfonyl)imide LiFNFSI.
  • the combined use of the above-mentioned compounds can take into account both the conductivity and stability of the electrolyte.
  • the lithium salt can also be selected from lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium perchlorate (LiClO 4 ), lithium hexafluoroarsenate (LiAsF 6 ), bisfluorosulfonyl Lithium imide (LiFSI), lithium bistrifluoromethanesulfonyl imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluoromethanesulfonate borate (LiDFOB), lithium difluoromethanesulfonylborate (LiBOB), difluorophosphoric acid
  • LiPF 6 lithium hexafluorophosphate
  • LiBF 4 lithium tetrafluoroborate
  • LiClO 4 lithium perchlorate
  • LiAsF 6 lithium hexafluoroarsenate
  • LiFSI bisfluorosulf
  • the electrolyte further includes one or more of carbonate additives, sulfate additives, and sulfite additives.
  • the above additives can form an interface film on the surface of the negative electrode film layer and/or the positive electrode film layer 5213, thereby protecting the active material, improving the structural stability of the negative electrode film layer and the positive electrode film layer 5213, and thereby improving the performance of the secondary battery. Cycle performance.
  • the carbonate additives include cyclic carbonate additives and/or linear carbonate additives; further, the cyclic carbonate additives include vinylene carbonate VC, fluoroethylene carbonate FEC, difluoroethylene carbonate One or more of ethylene carbonate DFEC, vinyl ethylene carbonate VEC and dioctyl carbonate CC; and/or linear carbonate additives include one of ethyl allyl carbonate AEC and diphenyl carbonate DPCkind or variety.
  • sulfate ester additives include cyclic sulfonate ester additives and/or sulfate hydrocarbon ester additives; further, cyclic sulfonate ester additives include 1,3-propane sulphonate PS, propylene sulfonate One or more of lactone PES, 3-fluoro-1,3-propanesultone FPS; and/or hydrocarbon sulfate additives including vinyl sulfate DTD, diethyl sulfate DES and dimethyl sulfate One or more of DMS.
  • the sulfite additive includes vinyl sulfite ES and/or vinyl vinyl sulfite VES.
  • the negative electrode sheet 522 includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector.
  • the negative electrode film layer includes a negative electrode active material.
  • the negative electrode current collector has two opposite surfaces in its own thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.
  • the negative electrode current collector may be a metal foil or a composite current collector.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base material.
  • the composite current collector can be formed by forming metal materials (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as polypropylene (PP), polyterephthalate It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the negative active material may be a negative active material known in the art for batteries.
  • the negative active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, and the like.
  • the silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon carbon composites, silicon nitrogen composites and silicon alloys.
  • the tin-based material may be selected from at least one of elemental tin, tin oxide compounds and tin alloys.
  • the present application is not limited to these materials, and other traditional materials that can be used as battery negative electrode active materials can also be used. Only one type of these negative electrode active materials may be used alone, or two or more types may be used in combination.
  • the negative electrode film layer optionally further includes a negative electrode binder.
  • the negative electrode binder can be selected from styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylate At least one of acrylic acid (PMAA) and carboxymethyl chitosan (CMCS).
  • the negative electrode film layer optionally further includes a negative electrode conductive agent.
  • the negative conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the negative electrode film layer optionally includes other auxiliaries, such as thickeners (such as sodium carboxymethylcellulose (CMC-Na)) and the like.
  • the negative electrode sheet 522 may be prepared by dispersing the above-mentioned components used to prepare the negative electrode sheet 522 , such as negative active materials, conductive agents, binders, and any other components in a solvent (e.g., deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode piece 522 can be obtained.
  • a solvent e.g., deionized water
  • a separation film 523 is further included in the secondary battery.
  • This application has no particular limitation on the type of isolation membrane 523, and any well-known porous structure isolation membrane 523 with good chemical stability and mechanical stability can be used.
  • the material of the isolation membrane 523 can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.
  • the isolation film 523 may be a single-layer film or a multi-layer composite film, and is not particularly limited.
  • the materials of each layer may be the same or different, and are not particularly limited.
  • the positive electrode piece 521 , the negative electrode piece 522 and the isolation film 523 can be formed into the electrode assembly 52 through a winding process or a lamination process.
  • the secondary battery may include an outer packaging.
  • the outer packaging can be used to package the above-mentioned electrode assembly and electrolyte.
  • the outer packaging of the secondary battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc.
  • the outer packaging of the secondary battery may also be a soft bag, such as a bag-type soft bag.
  • the soft bag may be made of plastic, such as one or a combination of polypropylene (PP), polybutylene terephthalate (PBT) and polybutylene succinate (PBS).
  • FIG. 4 shows an example of a square-structured secondary battery 5 .
  • the outer package may include a housing 51 and a cover 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 cover plate 53 is used to 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 contained in the secondary battery 5 can be one or more, and can be adjusted according to needs.
  • the positive electrode sheet, the separator, the negative electrode sheet, and the electrolyte may be assembled to form a secondary battery.
  • the positive electrode sheet, isolation film, and negative electrode sheet can be formed into an electrode assembly through a winding process or a lamination process.
  • the electrode assembly is placed in an outer package, dried, and then injected with electrolyte. After vacuum packaging, standing, and Through processes such as formation and shaping, secondary batteries are obtained.
  • the secondary batteries according to the present application can be assembled into a battery module.
  • the number of secondary batteries contained in the battery module can be multiple, and the specific number can be adjusted according to the application and capacity of the battery module.
  • FIG. 6 is a schematic diagram of the battery module 4 as an example.
  • a plurality of secondary batteries 5 may be arranged in sequence along the length direction of the battery module 4 .
  • the plurality of secondary batteries 5 can be fixed by fasteners.
  • the battery module 4 may further include a housing having an accommodation space in which a plurality of secondary batteries 5 are accommodated.
  • the above-mentioned battery modules can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be adjusted according to the application and capacity of the battery pack.
  • the battery pack 1 may include a battery box and a plurality of battery modules 4 arranged in the battery box.
  • the battery box includes an upper box 2 and a lower box 3 .
  • the upper box 2 is used to cover the lower box 3 and form a closed space for accommodating the battery module 4 .
  • Multiple battery modules 4 can be arranged in the battery box in any manner.
  • the present application provides an electrical device.
  • the electrical device includes at least one of a secondary battery, a battery module and a battery pack of the present application.
  • Secondary batteries, battery modules and battery packs can be used as power sources for power-consuming devices, and can also be used as energy storage units for power-consuming devices.
  • Electric devices may be, but are not limited to, mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, and electric golf balls). vehicles, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.
  • the electrical device can select secondary batteries, battery modules or battery packs according to its usage requirements.
  • FIG. 9 is a schematic diagram of an electrical device as an example.
  • the electric device 6 is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, or the like.
  • a battery pack 1 or a battery module can be used.
  • the power-consuming device may be a mobile phone, a tablet computer, a laptop computer, etc.
  • the electrical device is usually required to be light and thin, and secondary batteries can be used as power sources.
  • this application also proposes a method for preparing a secondary battery, which method can be used to prepare the secondary battery according to any embodiment of the first aspect of this application.
  • Methods include:
  • the area of the conductive coating is S 1 mm 2 and the area of the positive electrode film layer is S 2 mm 2 ;
  • the electrolyte includes lithium hexafluorophosphate with a molar concentration of C 1 mol/L and lithium fluorine-containing sulfonyl imide with a molar concentration of C 2 mol/L;
  • the secondary battery satisfies: -0.15 ⁇ S 1 /S 2 -C 2 /(10C 1 ) ⁇ 0.8; optionally, 0 ⁇ S 1 /S 2 -C 2 /(10C 1 ) ⁇ 0.7.
  • the method of the embodiment of the present application has a simple preparation process, and only needs to form a conductive coating on the positive electrode current collector. There is no need to change the original production process route, and the operation is convenient; and the formed positive electrode plate and the electrolyte cooperate with each other, It can simultaneously improve the cycle performance and energy density of secondary batteries.
  • the conductive slurry includes a conductive agent, the mass content of which is W 1 %, based on the total mass of the conductive coating, where 30% ⁇ W 1 ⁇ 60%.
  • the conductive properties of the conductive coating formed by the conductive slurry can be adjusted by adjusting the mass content of the conductive agent in the conductive slurry.
  • the conductive slurry further includes a binder, the mass content of which is W 2 %, based on the total mass of the conductive coating, where 40% ⁇ W 2 ⁇ 70%.
  • the adhesive properties of the conductive coating formed by the conductive slurry can be adjusted by adjusting the mass content of the binder in the conductive slurry.
  • An aluminum foil with a thickness of 13 ⁇ m was used as the positive electrode current collector.
  • the conductive slurry is coated on the surface of the positive electrode current collector, and after drying and other processes, a conductive coating is obtained.
  • the conductive coating consists of 50% conductive carbon black and 50% polyacrylate.
  • the coke raw material is pretreated to remove impurities, and pyrolyzed and granulated to obtain secondary particles with a Dv50 of 10 ⁇ m; then graphitized at 3000°C for 24 hours, and then coated with asphalt; and high-temperature carbonized at 1000°C for 15 hours to obtain artificial graphite. .
  • a copper foil with a thickness of 8 ⁇ m was used as the negative electrode current collector.
  • the above-mentioned positive electrode piece, isolation film and negative electrode piece in order so that the isolation film is between the positive electrode piece and the negative electrode piece to play an isolation role, and then wind it to obtain the electrode assembly; place the electrode assembly in the outer packaging shell After drying, the electrolyte is injected, and through processes such as vacuum packaging, standing, formation, and shaping, a lithium-ion battery is obtained.
  • Examples 2-1 to 2-4 adopt a method similar to Example 1 to prepare secondary batteries. The difference from Example 1 is that Examples 2-1 to 2-4 adjust the thickness of the conductive coating. Area S 1 .
  • Examples 2-1 to 2-4 adopt a method similar to Example 1 to prepare a secondary battery.
  • the difference from Example 1 is that the positive electrode sheet of Comparative Example 1 does not include a conductive coating.
  • the preparation process of the pole piece is as follows: add the positive active material LiNi 0.5 Co 0.2 Mn 0.3 O 2 , conductive carbon black, and binder polyvinylidene fluoride (PVDF) in an appropriate amount of N-format in a weight ratio of 98:1:1.
  • PVDF polyvinylidene fluoride
  • the positive electrode slurry is fully stirred and mixed in the NMP solvent to form a uniform positive electrode slurry; the positive electrode slurry is coated on the surface of the positive electrode current collector aluminum foil, and after drying and other processes, the positive electrode sheet is obtained.
  • Example 1 The parameters of Example 1, Example 2 and Comparative Example 1 are shown in Table 1:
  • Q represents S 1 /S 2 -C 2 /(10C 1 ).
  • Examples 3-1 to 3-6 adopt a method similar to Example 1 to prepare secondary batteries. The difference from Example 1 is that Examples 3-1 to 3-6 adjust the molar concentration C of lithium hexafluorophosphate. At least one of 1 and molar concentration C 2 of lithium fluorosulfonyl imide.
  • Example 1 The parameters of Example 1 and Example 3 are shown in Table 2.
  • Q represents S 1 /S 2 -C 2 /(10C 1 ).
  • Examples 4-1 to 4-10 adopt a method similar to Example 1 to prepare secondary batteries. The difference from Example 1 is that the thickness of the conductive coating used in Examples 4-1 to 4-10 d different.
  • Example 1 The parameters of Example 1 and Example 4 are shown in Table 3.
  • the peeled film layer is fixed on the clamp at the upper end of the tensile machine. It is pulled by the Instron 3365 high-speed rail tensile machine at a speed of 30mm/min. The film layer slowly Peel off the current collector and display the pulling force value when the pulling force is stable on the computer, which is the peeling strength value of the film layer.
  • the positive electrode piece Take the positive electrode piece, use a cotton swab or dust-free paper dipped in the positive electrode slurry solvent (usually NMP) to gently wipe off the active material on the electrode piece, leaving the conductive coating, apply dye to the coating area, and then cover it with grid paper On the coating, press lightly and the coating area will be copied to the grid paper. By counting the stained area on the grid paper, it is S1.
  • the positive electrode slurry solvent usually NMP
  • the ambient temperature is adjusted to 25°C.
  • the secondary battery prepared above is charged to 4.25V at 1C, and then charged to 0.05C at a constant voltage.
  • the secondary battery is placed in the heating furnace.
  • the heating furnace is heated at 10°C/min and kept warm for 10min. , until the secondary battery experiences thermal runaway and the process ends. Record the temperature monitored by the heating furnace when the secondary battery thermally runs out of control, which is the thermal runaway temperature.
  • the capacity retention rate (%) of the battery after 500 cycles the discharge capacity of the 500th cycle / the capacity of the first discharge ⁇ 100%.
  • Example 1 268.0 97.00% 200
  • Example 2-3 260.0 94.80% 187
  • Comparative Example 1 does not contain a conductive coating.
  • the active material particles crushed the oxide film on the surface of the aluminum foil.
  • the fluorine-containing sulfonylimide lithium in the electrolyte was oxidized in the positive electrode.
  • the product combines with aluminum ions, and the combined product dissolves into the electrolyte, causing the aluminum foil to be corroded, the adhesion between the positive electrode plates to deteriorate, and the active material to fall off, which not only affects the capacity of the secondary battery, but may also cause The internal short circuit caused thermal runaway of the secondary battery, so the overall performance of Comparative Example 1 was poor.
  • the aluminum foil can have a good protective effect and can effectively improve the cycle life of the secondary battery; and by adjusting the relationship between the parameters, it satisfies -0.15 ⁇ S 1 /S 2 -C 2 /(10C 1 ) ⁇ 0.75; especially when 0 ⁇ S 1 /S 2 -C 2 /(10C 1 ) ⁇ 0.7 is satisfied, the aluminum foil can be effectively protected, thus ensuring
  • the structural stability of the positive electrode plate improves the cycle performance of the secondary battery; during the charging and discharging process of the secondary battery, it has better safety performance and higher overall energy density.
  • Example 3-1 to Example 3-5 the molar concentrations of lithium hexafluorophosphate and lithium fluorine-containing sulfonylimide in the electrolyte are adjusted to satisfy: 1 ⁇ C 2 /C 1 ⁇ 5, 0.6 mol/L ⁇ C 1 +C 2 ⁇ 2mol/L, especially when 1.2 ⁇ C 2 /C 1 ⁇ 4.5 is satisfied, the corrosion effect on aluminum foil can be improved and the protective performance of aluminum foil can be improved.
  • Example 1 268 97.00% 200
  • Example 4-1 253 95.20% 187
  • Example 4-2 255 95.50% 188
  • Example 4-3 260 96.30% 197
  • Example 4-4 267 96.70% 196
  • Example 4-5 246 94.80% 185
  • Example 4-6 259 96.10% 192
  • Example 4-7 261 96.50% 194
  • Example 4-8 265 96.60% 196
  • Example 4-9 267 96.80% 199
  • Example 4-10 255 95.90% 188
  • Examples 4-1 to 4-10 regulate the thickness of the conductive coating, thereby adjusting the overall performance of the secondary battery, especially when 1/50 ⁇ d/L1 ⁇ 1/ 100 and/or 1/26 ⁇ d/L2 ⁇ 1/8, the overall performance of the secondary battery is better.

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Abstract

La présente invention concerne une batterie secondaire, un module de batterie, un bloc-batterie et un dispositif électrique. La batterie secondaire comprend une plaque d'électrode positive et une solution d'électrolyte, la plaque d'électrode positive comprenant un collecteur de courant d'électrode positive, une couche de film d'électrode positive disposée sur au moins une surface du collecteur de courant d'électrode positive, et un revêtement conducteur disposé entre le collecteur de courant d'électrode positive et la couche de film d'électrode positive ; la solution d'électrolyte comprend de l'hexafluorophosphate de lithium et du sulfonimide de lithium contenant du fluor ; la surface du revêtement conducteur est S1 mm2, et la surface de la couche de film d'électrode positive est S2 mm2; la concentration molaire de l'hexafluorophosphate de lithium est C1 mol/L, et la concentration molaire du sulfonimide de lithium contenant du fluor est C2 mol/L ; et la batterie secondaire satisfait : -0,15≤S1/S2-C2/(10C1) ≤ 0,8. Dans la présente invention, le revêtement conducteur peut protéger efficacement le collecteur de courant d'électrode positive, de telle sorte que la stabilité structurale du collecteur de courant d'électrode positive peut être assurée, la durée de vie de la batterie secondaire est prolongée, et les performances de sécurité de la batterie secondaire peuvent être améliorées ; et le revêtement conducteur ne recouvre pas excessivement le collecteur de courant d'électrode positive, de telle sorte que la densité d'énergie de la batterie secondaire peut être assurée.
PCT/CN2022/106172 2022-07-18 2022-07-18 Batterie secondaire, module de batterie, bloc-batterie et dispositif électrique WO2024016097A1 (fr)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102074734A (zh) * 2010-09-30 2011-05-25 张家港市国泰华荣化工新材料有限公司 一种含氟磺酰亚胺锂锂盐的电解质溶液及其用途
JP2013118058A (ja) * 2011-12-01 2013-06-13 Panasonic Corp 蓄電デバイス
CN208603718U (zh) * 2018-01-22 2019-03-15 赵井玉 一种电芯及包含其的锂离子电池
CN112582667A (zh) * 2020-04-04 2021-03-30 骆驼集团武汉新能源科技有限公司 一种汽车启停电源用高功率锂离子电池
CN113851724A (zh) * 2021-09-22 2021-12-28 宁德新能源科技有限公司 电化学装置和电子装置

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102074734A (zh) * 2010-09-30 2011-05-25 张家港市国泰华荣化工新材料有限公司 一种含氟磺酰亚胺锂锂盐的电解质溶液及其用途
JP2013118058A (ja) * 2011-12-01 2013-06-13 Panasonic Corp 蓄電デバイス
CN208603718U (zh) * 2018-01-22 2019-03-15 赵井玉 一种电芯及包含其的锂离子电池
CN112582667A (zh) * 2020-04-04 2021-03-30 骆驼集团武汉新能源科技有限公司 一种汽车启停电源用高功率锂离子电池
CN113851724A (zh) * 2021-09-22 2021-12-28 宁德新能源科技有限公司 电化学装置和电子装置

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