WO2023216076A1 - 极片、电池单体、电池以及用电装置 - Google Patents

极片、电池单体、电池以及用电装置 Download PDF

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Publication number
WO2023216076A1
WO2023216076A1 PCT/CN2022/091801 CN2022091801W WO2023216076A1 WO 2023216076 A1 WO2023216076 A1 WO 2023216076A1 CN 2022091801 W CN2022091801 W CN 2022091801W WO 2023216076 A1 WO2023216076 A1 WO 2023216076A1
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WO
WIPO (PCT)
Prior art keywords
tab
pole
pole piece
layer
active material
Prior art date
Application number
PCT/CN2022/091801
Other languages
English (en)
French (fr)
Inventor
柴志生
何昌盛
金海族
Original Assignee
宁德时代新能源科技股份有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
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Application filed by 宁德时代新能源科技股份有限公司 filed Critical 宁德时代新能源科技股份有限公司
Priority to PCT/CN2022/091801 priority Critical patent/WO2023216076A1/zh
Priority to EP22924567.5A priority patent/EP4300636A1/en
Priority to CN202280037558.XA priority patent/CN117378065A/zh
Priority to US18/446,290 priority patent/US20230387518A1/en
Publication of WO2023216076A1 publication Critical patent/WO2023216076A1/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
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings; Jackets or wrappings
    • H01M50/116—Primary casings; Jackets or wrappings characterised by the material
    • H01M50/124—Primary casings; Jackets or wrappings characterised by the material having a layered structure
    • H01M50/1243—Primary casings; Jackets or wrappings characterised by the material having a layered structure characterised by the internal coating on the casing
    • 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
    • H01M10/04—Construction or manufacture in general
    • H01M10/0431—Cells with wound or folded electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings; Jackets or wrappings
    • H01M50/102—Primary casings; Jackets or wrappings characterised by their shape or physical structure
    • H01M50/107—Primary casings; Jackets or wrappings characterised by their shape or physical structure having curved cross-section, e.g. round or elliptic
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings; Jackets or wrappings
    • H01M50/116—Primary casings; Jackets or wrappings characterised by the material
    • H01M50/117—Inorganic material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings; Jackets or wrappings
    • H01M50/172—Arrangements of electric connectors penetrating the casing
    • H01M50/174—Arrangements of electric connectors penetrating the casing adapted for the shape of the cells
    • H01M50/179—Arrangements of electric connectors penetrating the casing adapted for the shape of the cells for cells having curved cross-section, e.g. round or elliptic
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/531—Electrode connections inside a battery casing
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/531—Electrode connections inside a battery casing
    • H01M50/533—Electrode connections inside a battery casing characterised by the shape of the leads or tabs
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/531—Electrode connections inside a battery casing
    • H01M50/536—Electrode connections inside a battery casing characterised by the method of fixing the leads to the electrodes, e.g. by welding
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/531—Electrode connections inside a battery casing
    • H01M50/538—Connection of several leads or tabs of wound or folded electrode stacks
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2220/00—Batteries for particular applications
    • H01M2220/20—Batteries in motive systems, e.g. vehicle, ship, plane
    • 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 battery technology, and more specifically, to a pole piece, a battery cell, a battery and an electrical device.
  • Battery cells are widely used in electronic devices, such as mobile phones, laptops, battery cars, electric cars, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, electric tools, etc.
  • the battery cells may include cadmium-nickel battery cells, nickel-hydrogen battery cells, lithium-ion battery cells, secondary alkaline zinc-manganese battery cells, etc.
  • This application provides a pole piece, a battery cell, a battery and an electrical device, which can improve the safety of the battery cell.
  • embodiments of the present application provide a pole piece including an insulating base, a conductive layer and an active material layer.
  • the conductive layer is arranged on the surface of the insulating base.
  • the active material layer is coated on the surface of the conductive layer facing away from the insulating substrate.
  • the conductive layer includes a first part coated with the active material layer and a second part not coated with the active material layer. The first part and the second part are arranged along the first direction.
  • the thickness of the conductive layer is d1, and the size of the first part along the first direction is W. d1, W and K satisfy: 0.001J/( ⁇ mm 4 ⁇ °C) ⁇ d1/(K ⁇ W) ⁇ 0.0075J/( ⁇ ⁇ mm 4 ⁇ °C).
  • the conductive layer has a smaller thickness.
  • the burrs generated by the conductive layer at the pierced position are smaller, which can reduce the risk of burrs puncturing the isolation member, thereby reducing The possibility of short circuit improves the safety of battery cells.
  • d1/(K ⁇ W) The smaller the value of d1/(K ⁇ W), the more heat the conductive layer generates during the charge and discharge process. The higher the temperature, the faster the active material layer coated on the conductive layer ages, and the faster the battery cell capacity decreases. If d1/(K ⁇ W) is too large, the thickness d1 of the conductive layer will be over-designed, resulting in a low energy density of the battery cell.
  • the above technical solution limits the value of d1/(K ⁇ W) to 0.001J/( ⁇ mm 4 ⁇ °C)-0.0075J/( ⁇ mm 4 ⁇ °C) to balance the energy density and cycle life of the battery cell. .
  • d1, W and K satisfy: 0.002J/( ⁇ mm 4 ⁇ °C) ⁇ d1/(K ⁇ W) ⁇ 0.003J/( ⁇ mm 4 ⁇ °C).
  • d1 is between 0.5 ⁇ m and 5 ⁇ m.
  • the pole piece further includes a pole tab, which is welded to the second part and forms a first welding part; in the first direction, one end of the pole tab away from the active material layer protrudes from the second part.
  • the portion of the tab protruding from the second portion in the first direction may be used to connect with the electrode lead-out structure of the battery cell.
  • the thickness of the tab is d2, and d2 is greater than d1.
  • the thickness of the tab is greater than the thickness of the conductive layer to improve the overcurrent capability of the tab.
  • d2 is between 1 ⁇ m and 100 ⁇ m.
  • the larger d2 is, the larger the volume and weight of the tab are, and the more heat is generated by welding the tab and the conductive layer, and the easier it is for poor welding between the tab and the conductive layer.
  • the above technical solution limits the value of d2 to 1 ⁇ m-100 ⁇ m so that the tab can meet the overcurrent requirements and reduce the heat generated by the tab during the welding process.
  • the pole piece further includes an adhesive layer, the adhesive layer is connected to the tab and covers at least part of the first welding portion.
  • the adhesive layer can fix at least some particles on the first welding part, reducing the risk of particles falling into the electrode assembly and improving safety.
  • a portion of the adhesive layer is located between the active material layer and the tab in the first direction, is coated on the second portion, and is connected to the active material layer.
  • the adhesive layer is connected to the active material layer, which can cover the connection between the first part and the second part, reducing the risk of cracking of the conductive layer and ensuring the overcurrent capability of the conductive layer.
  • the adhesive layer also connects the tabs to the conductive layer and the active material layer, thereby reducing the risk of the tabs falling off.
  • the pole piece further includes an insulating layer, and at least part of the insulating layer is located on a side of the adhesive layer away from the first welding portion and is connected to the adhesive layer.
  • the insulating layer can protect the adhesive layer, reduce the risk of short circuit caused by the welding part puncturing the adhesive layer, and improve safety.
  • the insulation layer can also improve the insulation of the pole pieces and reduce the risk of overlapping short circuits between the positive and negative pole pieces.
  • the adhesive layer also connects the insulation to the tabs to reduce the risk of the insulation coming off.
  • both the insulating layer and the adhesive layer include an adhesive, the weight ratio of the adhesive in the insulating layer to the insulating layer is N1, and the weight ratio of the adhesive in the adhesive layer to the adhesive layer is N2, N1 is smaller than N2.
  • the adhesive layer has a higher adhesive content, which can better adhere to the first welding part and reduce the risk of separation between the adhesive layer and the first welding part.
  • the insulating layer does not need to be connected to the first welding portion and can contain less adhesive. In this way, the insulating layer can be provided with more material with higher strength to improve the overall strength of the insulating layer.
  • the insulating layer completely covers the adhesive layer to reduce the exposed area of the adhesive layer and reduce the risk of the adhesive layer being separated from the first welding part when soaked in the electrolyte.
  • the pole piece further includes an insulating layer, the insulating layer is connected to the tab and the active material layer, and the insulating layer covers at least part of the first welding portion.
  • the insulating layer can fix at least some particles on the first welding part, reducing the risk of particles falling into the electrode assembly and improving safety.
  • the insulating layer includes ceramic particles and a binder, and the weight ratio of the binder to the insulating layer is greater than or equal to 0.1.
  • the adhesive content in the insulating layer is higher, which can better adhere to the first welding part and reduce the risk of separation of the insulating layer and the first welding part.
  • the portion of the tab beyond the conductive layer is not coated with an insulating layer to reduce the risk of interference between the insulating layer and the electrode lead-out structure.
  • the pole tab includes a plurality of pole tab portions spaced apart along a second direction, and the second direction is perpendicular to the first direction and the thickness direction of the pole piece. In the first direction, the pole portion protrudes from the second portion.
  • the above technical solution divides the pole tab into multiple separate pole tab parts, which facilitates the bending of the pole tab part after the pole piece is wound.
  • a battery cell which includes a casing, an electrode assembly and an electrode lead-out structure.
  • the electrode assembly is contained in the housing.
  • the electrode assembly includes the pole piece according to any embodiment of the first aspect.
  • the electrode lead-out structure is arranged on the shell and connected to the tab.
  • two conductive layers are provided, and the two conductive layers are respectively provided on both sides of the insulating base.
  • the pole tab includes a first pole tab and a second pole tab, and the first pole tab and the second pole tab are respectively welded to the second parts of the two conductive layers. The first tab and the second tab are respectively used to draw out the current on the two conductive layers.
  • the electrode lead-out structure has a connecting portion.
  • the connecting portion In the first direction, the connecting portion is located on a side of the first tab away from the active material layer.
  • the connecting portion is against and welded to the first tab, and is welded to the second tab. Offset and weld.
  • the thickness of the connecting part is t
  • the size of the first tab beyond the first welding part in the first direction in the flattened state is h2.
  • t and h2 satisfy: 2.5 ⁇ h2/t ⁇ 10.
  • the size of the second tab beyond the first welding part along the first direction in the flattened state is h3, and t and h3 satisfy: 2.5 ⁇ h3/t ⁇ 10.
  • the larger h2 is, the larger the part of the first pole that can be welded to the connecting part is, but the space occupied by the first pole is also larger; the smaller the value of t, the less heat generated by welding.
  • the lower the connection strength between the first tab and the connecting part the smaller the overcurrent capacity of the connecting part.
  • the smaller h2 is, the smaller the part of the first pole that can be welded to the connecting part, but the smaller the space occupied by the first pole is; the larger the value of t, the more heat generated by welding is transferred to the first pole The more heat there is on the tabs and separators, the higher the risk of burns to the tabs and separators.
  • the above technical solution limits the value of h2/t to 2.5-10 to ensure the connection strength between the connecting part and the first tab, reduce the risk of the first tab being melted through, and increase the energy density.
  • the above technical solution limits the value of h3/t to 2.5-10 to ensure the connection strength between the connecting part and the second tab, reduce the risk of the second tab being melted through, and improve the energy density.
  • one end of the first tab facing away from the active material layer exceeds the second tab, and the second tab is bent toward the first tab and connected to the first tab.
  • the electrode extraction structure has a connecting portion. In the first direction, the connecting portion is located on a side of the first tab away from the active material layer. The connecting portion and the first tab are offset and welded. The thickness of the connecting part is t, and the size of the first tab beyond the first welding part in the first direction in the flattened state is h2. t and h2 satisfy: 5 ⁇ h2/t ⁇ 20.
  • the second tab is not welded to the connecting part. Therefore, the above technical solution limits the value of h2/t to 5-20 to ensure the connection strength between the connecting part and the first tab and reduce the meltdown of the first tab. risk of increasing energy density. Compared with the solution in which the first tab and the second tab are welded to the connection part at the same time, the solution in which only the first tab is welded to the connection part requires the first tab to have a larger h2.
  • the pole pieces are wound in multiple turns. In the radial direction of the electrode assembly, the spacing between two adjacent turns of pole pieces is d3, 0.2mm ⁇ d3 ⁇ 0.4mm.
  • the pole piece is wound in multiple turns, and correspondingly, the pole tab is also wound in multiple turns.
  • the separator of the electrode assembly may be burned by the laser, causing safety risks. Therefore, the above technical solution limits the value of d3 to less than or equal to 0.4mm to improve safety.
  • the electrode lead-out structure has a connecting portion.
  • the connecting portion In the first direction, the connecting portion is located on a side of the tab facing away from the active material layer.
  • the connecting portion and the tab are offset and welded.
  • the electrode assembly also includes a separator, which is laminated and wound with the pole piece.
  • the minimum distance between the surface of the connecting part and the first tab and the isolator is S1
  • the thickness of the connecting part is t
  • S1 ⁇ 0.75t the minimum distance between the surface of the connecting part and the first tab and the isolator
  • the above technical solution limits S1 to be greater than or equal to 0.75t to reduce the heat conducted to the isolation member and reduce the risk of the isolation member being burned.
  • the tab is wound into multiple turns along the winding direction, and one end of the multi-turn tab away from the active material layer is flattened to form an end face, and the electrode lead-out structure is welded to the end face.
  • the pole piece is wound into multiple turns along the winding direction.
  • the pole tabs include a plurality of pole tab parts spaced apart along the winding direction. The plurality of pole tab parts are bent toward the winding center of the pole piece to form an end face, and the electrode lead-out structure is welded to the end face.
  • embodiments of the present application provide a battery, including a plurality of battery cells according to any embodiment of the second aspect.
  • embodiments of the present application provide an electrical device, including the battery cell according to any embodiment of the second aspect, and the battery cell is used to provide electric energy.
  • Figure 1 is a schematic structural diagram of a vehicle provided by some embodiments of the present application.
  • FIG. 2 is an exploded schematic diagram of a battery provided by some embodiments of the present application.
  • FIG 3 is a schematic structural diagram of the battery module shown in Figure 2;
  • Figure 4 is an exploded schematic diagram of a battery cell provided by some embodiments of the present application.
  • Figure 5 is a partial cross-sectional schematic diagram of a battery cell provided by some embodiments of the present application.
  • Figure 6 is a schematic structural diagram of an electrode assembly of a battery cell provided by some embodiments of the present application.
  • Figure 7 is a schematic structural diagram of a pole piece provided by some embodiments of the present application.
  • Figure 8 is a schematic cross-sectional view of the pole piece shown in Figure 7 along line A-A;
  • Figure 9 is a schematic cross-sectional view of a pole piece provided by some embodiments of the present application.
  • Figure 10 is a schematic cross-sectional view of a pole piece provided by other embodiments of the present application.
  • Figure 11 is a partial structural diagram of a battery cell provided by some embodiments of the present application.
  • Figure 12 is a schematic cross-sectional view of a pole piece provided by some embodiments of the present application.
  • Figure 13 is a partial structural diagram of a battery cell provided by some embodiments of the present application.
  • Figure 14 is a schematic structural diagram of the pole piece in the unfolded state provided by some embodiments of the present application.
  • Figure 15 is a partial schematic diagram of a battery cell provided by some embodiments of the present application.
  • Electrode assembly 11. Pole piece; 111. Insulating matrix; 112. Conductive layer; 112a, first part; 112b, second part; 113. Active material layer; 114, tab; 114a, first 114b, second pole tab; 114c, end face; 114d, pole tab part; 115, first welding part; 116, adhesive layer; 117, insulation layer; 11a, first pole piece; 11b, second pole piece; 12. Isolator; 20. Shell; 21. Shell; 22. End cover; 30. Electrode lead-out structure; 31. Electrode terminal; 32. Current collecting member; 33. Connection part; V, winding direction; X , first direction; Y, second direction; Z, thickness direction.
  • an embodiment means that a particular feature, structure or characteristic described in connection with the embodiment may be included in at least one embodiment of the application.
  • the appearances of this phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments.
  • connection should be understood in a broad sense.
  • connection can be a fixed connection, It can also be detachably connected or integrally connected; it can be directly connected or indirectly connected through an intermediate medium; it can be internal communication between two components.
  • connection can be a fixed connection
  • connection can also be detachably connected or integrally connected; it can be directly connected or indirectly connected through an intermediate medium; it can be internal communication between two components.
  • connection can also be detachably connected or integrally connected; it can be directly connected or indirectly connected through an intermediate medium; it can be internal communication between two components.
  • “Plural” appearing in this application means two or more (including two).
  • parallel includes not only the absolutely parallel situation, but also the roughly parallel situation that is conventionally recognized in engineering; at the same time, the term “perpendicular” includes not only the absolutely vertical situation, but also the roughly parallel situation that is conventionally recognized in engineering. vertical situation.
  • battery cells may include lithium ion secondary battery cells, lithium ion primary battery cells, lithium sulfur battery cells, sodium lithium ion battery cells, sodium ion battery cells or magnesium ion battery cells, etc.
  • the embodiments of the present application are not limited to this.
  • the battery cell may be in the shape of a cylinder, a flat body, a rectangular parallelepiped or other shapes, and the embodiments of the present application are not limited to this.
  • the battery mentioned in the embodiments of this application refers to a single physical module including one or more battery cells to provide higher voltage and capacity.
  • the battery may also generally include a case for enclosing one or more battery cells.
  • the box can prevent liquid or other foreign matter from affecting the charging or discharging of the battery cells.
  • the battery cell includes an electrode assembly and an electrolyte.
  • the electrode assembly includes a positive electrode piece, a negative electrode piece and a separator. Battery cells mainly rely on the movement of metal ions between the positive and negative electrodes to work.
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer, and the positive electrode active material layer is coated on the surface of the positive electrode current collector.
  • the material of the cathode current collector can be aluminum, and the cathode active material layer includes cathode active materials.
  • the cathode active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium or lithium manganate, etc.
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer, and the negative electrode active material layer is coated on the surface of the negative electrode current collector.
  • the negative electrode current collector may be made of copper, and the negative electrode active material layer may include a negative electrode active material.
  • the negative electrode active material may be carbon or silicon.
  • the material of the isolator can be PP (polypropylene, polypropylene) or PE (polyethylene, polyethylene), etc.
  • the current collector (such as the positive electrode current collector or the negative electrode current collector) is an indispensable part. It not only plays the role of carrying active materials, but also collects the electrons generated by the electrochemical reaction and guides them to the external circuit. , thereby realizing the process of converting chemical energy into electrical energy.
  • current collectors generally use metal foil materials, and metal foil materials have a large weight, which restricts the further improvement of the energy density of battery cells.
  • the current collector of the pole piece is pierced by an external structure, the current collector will produce burrs at the punctured location. The burrs can easily pierce the separator and cause the positive and negative electrodes to conduct, thus causing An internal short circuit in a battery cell may cause the battery cell to catch fire or explode.
  • the inventor designed a pole piece that uses a current collector with a multi-layer structure.
  • the current collector may include an insulating base and a conductive layer disposed on the surface of the insulating base, and the active material layer of the pole piece may be coated on the surface of the conductive layer facing away from the insulating base.
  • the conductive layer can collect electrons generated by electrochemical reactions and guide them to the external circuit.
  • a current collector with a multi-layer structure including an insulating matrix has a smaller weight than a current collector made of metal foil, thereby further improving the energy density of the battery cell.
  • the conductive layer has a smaller thickness.
  • embodiments of the present application provide a pole piece, which adjusts the thickness of the conductive layer in combination with the current carrying capacity of the conductive layer and the size of the pole piece, so as to reduce the conductivity while meeting the current carrying requirements of the conductive layer. layer thickness, thereby extending the cycle life of the battery cell and improving the energy density of the battery cell.
  • pole pieces described in the embodiments of this application are suitable for battery cells, batteries, and electrical devices using batteries.
  • Electrical devices can be vehicles, cell phones, portable devices, laptops, ships, spacecraft, electric toys and power tools, etc.
  • Vehicles can be fuel vehicles, gas vehicles or new energy vehicles, and new energy vehicles can be pure electric vehicles, hybrid vehicles or extended-range vehicles, etc.
  • spacecraft include aircraft, rockets, space shuttles, spaceships, etc.
  • electric toys include fixed Type or mobile electric toys, such as game consoles, electric car toys, electric ship toys and electric airplane toys, etc.
  • electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools and railway electric tools, for example, Electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, planers and more.
  • Electric drills Electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, planers and more.
  • the following embodiments take the electrical device as a vehicle as an example.
  • Figure 1 is a schematic structural diagram of a vehicle provided by some embodiments of the present application.
  • a battery 2 is provided inside the vehicle 1 , and the battery 2 can be provided at the bottom, head, or tail of the vehicle 1 .
  • the battery 2 may be used to power the vehicle 1 , for example, the battery 2 may be used as an operating power source for the vehicle 1 .
  • the vehicle 1 may also include a controller 3 and a motor 4.
  • the controller 3 is used to control the battery 2 to provide power to the motor 4, for example, to meet the power requirements for starting, navigation and driving of the vehicle 1.
  • the battery 2 can not only be used as the operating power source of the vehicle 1, but also can be used as the driving power source of the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.
  • Figure 2 is an exploded schematic diagram of a battery provided by some embodiments of the present application.
  • the battery 2 includes a case 5 and a battery cell (not shown in FIG. 2 ), and the battery cell is accommodated in the case 5 .
  • the box 5 is used to accommodate battery cells, and the box 5 can be of various structures.
  • the box body 5 may include a first box body part 5a and a second box body part 5b.
  • the first box body part 5a and the second box body part 5b cover each other.
  • the first box body part 5a and the second box body part 5b cover each other.
  • the two box portions 5b jointly define an accommodating space 5c for accommodating battery cells.
  • the second box part 5b can be a hollow structure with one end open, and the first box part 5a is a plate-like structure.
  • the first box part 5a is covered with the opening side of the second box part 5b to form a receiving space 5c.
  • the box body 5; the first box body part 5a and the second box body part 5b can also be a hollow structure with one side open, and the opening side of the first box body part 5a is covered with the opening side of the second box body part 5b , to form a box 5 having an accommodation space 5c.
  • the first box part 5a and the second box part 5b can be in various shapes, such as cylinder, rectangular parallelepiped, etc.
  • a sealing member may also be provided between the first box part 5a and the second box part 5b, such as sealant, sealing ring, etc. .
  • the first box part 5a can also be called an upper box cover, and the second box part 5b can also be called a lower box.
  • the battery 2 there may be one battery cell or a plurality of battery cells. If there are multiple battery cells, the multiple battery cells can be connected in series, in parallel, or in mixed connection. Mixed connection means that multiple battery cells are connected in series and in parallel. Multiple battery cells can be directly connected in series or parallel or mixed together, and then the whole composed of multiple battery cells can be accommodated in the box 5; of course, multiple battery cells can also be connected in series or parallel first or A battery module 6 is formed by a mixed connection, and multiple battery modules 6 are connected in series, parallel, or mixed to form a whole, and are accommodated in the box 5 .
  • FIG. 3 is a schematic structural diagram of the battery module shown in FIG. 2 .
  • the plurality of battery cells 7 are first connected in series, parallel, or mixed to form the battery module 6 .
  • a plurality of battery modules 6 are connected in series, parallel, or mixed to form a whole, and are accommodated in the box.
  • the plurality of battery cells 7 in the battery module 6 can be electrically connected through bus components to achieve parallel, series or mixed connection of the plurality of battery cells 7 in the battery module 6 .
  • the battery cell 7 may be a cylindrical battery cell, a square battery cell or a battery cell of other shapes.
  • Figure 4 is an exploded schematic view of a battery cell provided by some embodiments of the present application
  • Figure 5 is a partial cross-sectional schematic view of a battery cell provided by some embodiments of the present application
  • Figure 6 is a schematic diagram of a battery cell provided by some embodiments of the present application. Structural diagram of the electrode assembly.
  • the battery cell 7 in the embodiment of the present application includes a casing 20 and an electrode assembly 10 , and the electrode assembly 10 is accommodated in the casing 20 .
  • the casing 20 has a hollow structure, and an accommodation cavity for accommodating the electrode assembly 10 and the electrolyte is formed inside.
  • the shape of the housing 20 can be determined according to the specific shape of the electrode assembly 10 . For example, if the electrode assembly 10 has a cylindrical structure, a cylindrical shell can be selected; if the electrode assembly 10 has a rectangular parallelepiped structure, a rectangular parallelepiped shell can be selected. Optionally, both the electrode assembly 10 and the housing 20 are cylindrical.
  • the housing 20 includes a housing 21 and an end cover 22.
  • the housing 21 has an opening.
  • the end cover 22 is connected to the housing 21 and used to cover the opening.
  • the end cap 22 is sealingly connected to the housing 21 to form a sealed space for accommodating the electrode assembly 10 and the electrolyte.
  • one end of the housing 21 has an opening, and the end cap 22 is provided as one and covers the opening of the housing 21 .
  • the two opposite ends of the housing 21 have openings, and two end caps 22 are provided, and the two end caps 22 cover the two openings of the housing 21 respectively.
  • electrode assembly 10 includes pole pieces and spacers 12 .
  • the pole pieces are provided in multiple numbers, and the plurality of pole pieces include a first pole piece 11a and a second pole piece 11b with opposite polarities, and the separator 12 is used to insulate the first pole piece 11a and the second pole piece 11b. isolation.
  • the electrode assembly 10 mainly relies on metal ions to move between the first pole piece 11a and the second pole piece 11b to work.
  • One of the first pole piece 11a and the second pole piece 11b is a positive pole piece, and the other one of the first pole piece 11a and the second pole piece 11b is a negative pole piece.
  • first pole piece 11a, the second pole piece 11b and the separator 12 are all strip-shaped structures, and the first pole piece 11a, the second pole piece 11b and the separator 12 are wound around the central axis to be integrated.
  • the winding structure can be a cylindrical structure, a flat structure or other shaped structures.
  • the battery cell 7 further includes an electrode lead-out structure 30, which is disposed on the housing 20 and used to electrically connect with the electrode assembly 10 to lead out the electrical energy generated by the electrode assembly 10.
  • the electrode lead-out structure 30 includes an electrode terminal 31 with at least part of the electrode terminal 31 exposed to the outside of the housing 20 to achieve electrical connection with other structures (eg, bus components).
  • At least part of the electrode terminal 31 is accommodated in the housing 20 and directly connected to the pole piece.
  • the electrode terminal 31 is welded to the pole piece.
  • the electrode lead-out structure 30 further includes a current collecting member 32 , and the current collecting member 32 is used to connect the pole piece and the electrode terminal 31 .
  • the first pole piece 11 a and the current collecting member 32 may be welded first, and then the current collecting member 32 may be welded to the electrode terminal 31 .
  • the electrode lead-out structure 30 may be integrally provided with the housing 20 .
  • the electrode lead-out structure 30 is integrally provided with the end cover 22 , and the first pole piece 11 a can be directly welded to the end cover 22 .
  • Figure 7 is a schematic structural diagram of the pole piece provided by some embodiments of the present application
  • Figure 8 is a schematic cross-sectional view of the pole piece shown in Figure 7 along line A-A.
  • the pole piece 11 in the embodiment of the present application includes an insulating base 111 , a conductive layer 112 and an active material layer 113 .
  • the conductive layer 112 is provided on the surface of the insulating base 111 .
  • the active material layer 113 is coated on the surface of the conductive layer 112 facing away from the insulating substrate 111.
  • the conductive layer 112 includes a first part 112a coated with the active material layer 113 and a second part 112b not coated with the active material layer 113.
  • the first part 112a and The second portion 112b is arranged along the first direction X.
  • the thickness of the conductive layer 112 is d1, the size of the first part 112a along the first direction /( ⁇ mm 4 ⁇ °C).
  • the conductive layer 112 may be disposed on one side surface of the insulating base body 111 , or may be disposed on the opposite side surfaces of the insulating base body 111 .
  • thickness d1 refers to the thickness of the conductive layer 112 provided on one side surface of the insulating base 111 .
  • conductive layers 112 are provided on both sides of the insulating base 111, and the thickness of the conductive layers 112 on both sides is d1.
  • the pole piece 11 in this embodiment may be a positive pole piece in the electrode assembly 10 or a negative pole piece in the electrode assembly 10 .
  • conductive layers 112 are provided on both sides of the insulating base 111 , and the surface of each conductive layer 112 is coated with an active material layer 113 .
  • the surface of the first part 112 a facing away from the insulating base 111 is covered by the active material layer 113 , and the surface of the second part 112 b facing away from the insulating base 111 is not covered by the active material layer 113 .
  • the surface of the second part 112b facing away from the insulating base 111 may be exposed, or may be coated with other coatings that do not contain active materials.
  • the active material layer 113 is used to perform electrochemistry with the electrolyte to generate electric current.
  • the first portion 112a may collect the generated current together and direct the current to an external circuit through the second portion 112b.
  • the size of the active material layer 113 along the first direction X is the same as the size of the first portion 112a along the first direction X.
  • the current carrying capacity of the conductive layer 112 is related to its resistivity ⁇ 1, specific heat capacity C, and density ⁇ 2. Specifically, the smaller the K value, the higher the current carrying capacity of the conductive layer 112; the larger the K value, the weaker the current carrying capacity of the conductive layer 112.
  • the first part 112a brings together the current generated by the active material layer 113 and conducts the current to the second part 112b.
  • the current collected in the area of the first part 112a far away from the second part 112b needs to pass through the area of the first part 112a close to the second part 112b in order to flow to the second part 112b. Therefore, during the charging and discharging process, the current flowing through the first part 112a close to the second part 112b needs to pass through the area close to the second part 112b.
  • the current in the area of the part 112b is larger, and the heat generation in the area of the first part 112a close to the second part 112b is larger.
  • the greater the value of W the greater the capacity of the active material layer 113, the greater the current generated by the active material layer 113 during the charge and discharge process, and the higher the heat generation in the area of the first part 112a close to the second part 112b.
  • the inventor limited the value of d1/(K ⁇ W) to be greater than or equal to 0.001J/( ⁇ mm 4 ⁇ °C), in order to reduce the heat generated by the pole piece 11 during the charge and discharge process and reduce the battery life.
  • the temperature of the battery cell 7 enables the battery cell 7 to be suitable for high-rate charging and discharging conditions, ensuring the cycle life of the battery cell 7 and reducing safety risks.
  • K the higher the current carrying capacity of the conductive layer 112, and the smaller the thickness of the conductive layer 112 required by the pole piece 11.
  • W the smaller the current on the conductive layer 112, and the smaller the thickness of the conductive layer 112 required by the pole piece 11.
  • d1/(K ⁇ W) is too large, the thickness d1 of the conductive layer 112 will be over-designed, resulting in a low energy density of the battery cell 7 .
  • the inventor limited the value of d1/(K ⁇ W) to less than or equal to 0.0075J/( ⁇ mm 4 ⁇ °C), so that when the current carrying capacity and heat generation of the conductive layer 112 meet the requirements, Reducing the thickness of the conductive layer 112 increases the energy density of the battery cells 7 and extends the cycle life of the battery cells 7 .
  • the conductive layer 112 may be copper foil, aluminum foil, or nickel foil.
  • the K value of copper foil is 0.0050 ⁇ mm 4 ⁇ °C/J
  • the K value of aluminum foil is 0.0120 ⁇ mm 4 ⁇ °C/J
  • the K value of nickel foil is 0.0167 ⁇ mm 4 ⁇ °C/J .
  • the value of d1/(K ⁇ W) is 0.001J/( ⁇ mm 4 ⁇ °C), 0.002J/( ⁇ mm 4 ⁇ °C), 0.003J/( ⁇ mm 4 ⁇ °C ), 0.005J/( ⁇ mm 4 ⁇ °C), 0.007J/( ⁇ mm 4 ⁇ °C) or 0.0075J/( ⁇ mm 4 ⁇ °C).
  • d1, W and K satisfy: 0.002J/( ⁇ mm 4 ⁇ °C) ⁇ d1/(K ⁇ W) ⁇ 0.003J/( ⁇ mm 4 ⁇ °C).
  • d1 is 0.5 ⁇ m-5 ⁇ m.
  • d1 is 0.5 ⁇ m, 1 ⁇ m, 2 ⁇ m, 3 ⁇ m, 4 ⁇ m or 5 ⁇ m.
  • the pole piece 11 further includes a pole tab 114 that is welded to the second portion 112b and forms a first welding portion 115 .
  • a pole tab 114 that is welded to the second portion 112b and forms a first welding portion 115 .
  • first direction X one end of the tab 114 facing away from the active material layer 113 protrudes from the second portion 112b.
  • a part of the pole tab 114 overlaps the second part 112b; the part of the pole tab 114 that overlaps the second part 112b is welded to the second part 112b and forms the first welding part 115.
  • the tab 114 can be used to draw current from the second portion 112b.
  • the portion of the tab 114 protruding from the second portion 112b in the first direction X may be used to connect with the electrode lead-out structure.
  • the thickness of tab 114 is d2, and d2 is greater than d1.
  • the thickness of the tab 114 is greater than the thickness of the conductive layer 112 to improve the overcurrent capability of the tab 114 .
  • d2 is 1 ⁇ m-100 ⁇ m.
  • two conductive layers 112 are provided, and the two conductive layers 112 are respectively provided on both sides of the insulating base 111 .
  • the pole tab 114 includes a first pole tab 114a and a second pole tab 114b.
  • the first pole tab 114a and the second pole tab 114b are respectively welded to the second portions 112b of the two conductive layers 112.
  • the first tab 114a and the second tab 114b are respectively used to draw out the current on the two conductive layers 112.
  • the aforementioned d2 refers to the thickness of a single tab 114 .
  • the thickness of the first tab 114a and the second tab 114b is d2.
  • the size of the first tab 114a and the size of the second tab 114b may be the same or different.
  • an end of the first tab 114a facing away from the active material layer 113 is flush with an end of the second tab 114b facing away from the active material layer 113 .
  • an end of the first tab 114a facing away from the active material layer 113 exceeds the second tab 114b, and the second tab 114b is bent toward the first tab 114a and connected to the first tab 114a.
  • the first tab 114a is welded to the corresponding conductive layer 112 to form a first welding sub-section
  • the second tab 114b is welded to the corresponding conductive layer 112 to form a second welding sub-section.
  • the first welding part 115 includes a first welding sub-part and a second welding sub-part.
  • insulating matrix 111 separates the first and second solder sub-sections. In other examples, a part of the insulating base 111 is welded through, and the first welding sub-section and the second welding sub-section are directly connected into one body.
  • Figure 9 is a schematic cross-sectional view of a pole piece provided by some embodiments of the present application.
  • the pole piece 11 further includes an adhesive layer 116 , which is connected to the pole lug 114 and covers at least part of the first welding portion 115 .
  • the adhesive layer 116 may cover part of the first welding part 115 , or may cover the entire first welding part 115 .
  • the adhesive layer 116 may be coated only on the tabs 114 , or may be coated on both the conductive layer 112 and the tabs 114 .
  • the adhesive layer 116 of this embodiment can fix at least some particles on the first welding part 115, reducing the risk of particles falling into the electrode assembly and improving safety.
  • the adhesive layer 116 is formed by curing colloid.
  • the colloid includes an adhesive
  • the adhesive may include at least one of epoxy resin, acrylate, and styrene-butadiene rubber.
  • the colloid includes ceramic particles, and the ceramic particles may include at least one of boehmite, silicon oxide, and zirconia.
  • the ceramic particles can enhance the puncture strength and insulation of the adhesive layer 116 .
  • the colloid includes a color identifying agent such as charcoal, Prussian blue, etc.
  • the viscosity of the colloid is 1000 MPa ⁇ s.
  • the colloid has good fluidity during coating and can cover the uneven areas of the first welding part 115 to reduce the risk of missed coating.
  • the thickness of the adhesive layer 116 is 0.01mm-0.1mm.
  • the adhesive layer 116 has good toughness and strength, and is not easy to fall off during the roll forming process of the electrode assembly 10 .
  • a portion of the adhesive layer 116 is located between the active material layer 113 and the tab 114 in the first direction X, is coated on the second portion 112b and is connected to the active material layer 113 .
  • the active material layer 113 During the forming process of the pole piece 11, it is generally necessary to roll the active material layer 113 to increase the compaction density of the active material layer 113.
  • the first part 112a is stressed while the second part 112b is not stressed, which causes stress concentration to easily occur at the connection between the first part 112a and the second part 112b, causing cracking at the connection between the first part 112a and the second part 112b. risks of.
  • the adhesive layer 116 is connected to the active material layer 113 and can cover the connection between the first part 112a and the second part 112b, thereby reducing the risk of cracking of the conductive layer 112 and ensuring the overcurrent capability of the conductive layer 112.
  • the adhesive layer 116 can also connect the tab 114 to the conductive layer 112 and the active material layer 113, thereby reducing the risk of the tab 114 falling off.
  • the pole piece 11 further includes an insulating layer 117 , at least part of the insulating layer 117 is located on a side of the adhesive layer 116 away from the first welding portion 115 and is connected to the adhesive layer 116 .
  • the insulating layer 117 can protect the adhesive layer 116, reduce the risk of short circuit caused by the welding part piercing the adhesive layer 116, and improve safety.
  • the insulating layer 117 can also improve the insulation of the pole piece 11 and reduce the risk of overlapping short circuit between the positive and negative pole pieces.
  • the adhesive layer 116 can also connect the insulating layer 117 to the tab 114 to reduce the risk of the insulating layer 117 falling off.
  • the insulating layer 117 completely covers the adhesive layer 116 to reduce the exposed area of the adhesive layer 116 and reduce the risk of the adhesive layer 116 being separated from the first welding portion 115 when soaked in the electrolyte.
  • covering refers to covering in the thickness direction Z, that is, the insulating layer 117 completely covers the adhesive layer 116 in the thickness direction Z of the pole piece 11 .
  • both the insulating layer 117 and the adhesive layer 116 include an adhesive.
  • the weight ratio of the adhesive in the insulating layer 117 to the insulating layer 117 is N1.
  • the weight ratio of layer 116 is N2, N1 is less than N2.
  • the adhesive layer 116 has a higher adhesive content, which can better adhere to the first welding part 115 and reduce the risk of separation between the adhesive layer 116 and the first welding part 115 .
  • the insulating layer 117 does not need to be connected to the first welding portion 115 and can contain less adhesive. In this way, the insulating layer 117 can be provided with more material with higher strength to improve the overall strength of the insulating layer 117 .
  • the insulating layer 117 is formed by curing insulating slurry.
  • the insulating slurry may include ceramic particles and a binder.
  • the ceramic particles may include at least one of alumina, silicon oxide and zirconium oxide.
  • the binder may include polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE). of at least one.
  • the viscosity of the insulating slurry is 3000 MPa ⁇ s-10000 MPa ⁇ s.
  • the viscosity of the insulating slurry used to prepare the insulating layer 117 is greater than the viscosity of the colloid used to prepare the adhesive layer 116 .
  • the low-viscosity colloid has good fluidity during coating and molding to cover the uneven areas of the first welding part 115 and reduce the risk of missed coating; the high-viscosity insulating slurry can have higher strength after molding. To reduce the risk of the insulation layer 117 being punctured.
  • the thickness of the insulating layer 117 is 0.005mm-0.5mm.
  • the insulating layer 117 further includes a dispersant, such as sodium carboxymethyl cellulose and the like.
  • the portion of the tab 114 beyond the conductive layer 112 is not coated with the insulating layer 117 .
  • the portion of the tab 114 beyond the conductive layer 112 is used to connect to the electrode extraction structure. If the insulating layer 117 is coated on the portion of the tab 114 beyond the conductive layer 112, it may interfere with the connection between the tab 114 and the current extraction structure. Therefore, optionally, the portion of the tab 114 that extends beyond the conductive layer 112 is not coated with the insulating layer 117 .
  • the pole piece 11 can be formed according to the following steps: providing an insulating base 111 and a conductive layer 112, and the conductive layer 112 is disposed on the surface of the insulating base 111; and coating activity on the surface of the conductive layer 112 away from the insulating base 111. Slurry, the active material layer 113 is formed after the active slurry is solidified; the tab 114 is welded to the part of the conductive layer 112 that is not coated with the active material layer 113 to form the first welding part 115; on the conductive layer 112 and the tab 114 Apply colloid so that the colloid covers the first welding portion 115; apply insulating slurry on the colloid.
  • the adhesive layer 116 is formed, and after the insulating slurry is solidified, the insulating layer 117 is formed.
  • Figure 10 is a schematic cross-sectional view of a pole piece provided by other embodiments of the present application.
  • the pole piece 11 further includes an insulating layer 117 , the insulating layer 117 is connected to the tab 114 and the active material layer 113 , and the insulating layer 117 covers at least part of the first welding portion 115 .
  • the insulating layer 117 can fix at least some particles on the first welding part 115, thereby reducing the risk of particles falling into the electrode assembly 10 and improving safety.
  • the adhesive layer of the pole piece 11 can be omitted, and the insulating layer 117 is directly bonded to the first welding portion 115 .
  • the insulating layer 117 includes ceramic particles and a binder, and the weight ratio of the binder to the insulating layer 117 is greater than or equal to 0.1.
  • the adhesive content in the insulating layer 117 is higher, which can better adhere to the first welding portion 115 and reduce the risk of separation of the insulating layer 117 and the first welding portion 115 .
  • Figure 11 is a partial structural diagram of a battery cell provided by some embodiments of the present application.
  • the embodiment of the present application also provides a battery cell 7 , which includes a casing 20 , an electrode assembly 10 and an electrode lead-out structure 30 .
  • the electrode assembly 10 is contained in the housing 20 .
  • the electrode assembly 10 includes the pole piece 11 of any of the aforementioned embodiments.
  • the electrode lead-out structure 30 is disposed on the housing 20 and connected to the tab 114 .
  • the electrode lead-out structure 30 is used to lead out the electrical energy generated by the electrode assembly 10 .
  • the pole tab 114 includes a first pole tab 114a and a second pole tab 114b.
  • the first pole tab 114a and the second pole tab 114b are respectively welded to the second portions 112b of the two conductive layers 112.
  • the first tab 114a and the second tab 114b are respectively used to draw out the current on the two conductive layers 112.
  • the electrode lead-out structure 30 has a connecting portion 33.
  • the thickness of the connecting part 33 is t
  • the size of the first tab 114a beyond the first welding part 115 along the first direction X in the flattened state is h2.
  • t and h2 satisfy: 2.5 ⁇ h2/t ⁇ 10.
  • the size of the second tab 114b beyond the first welding portion 115 along the first direction X in the flattened state is h3, and t and h3 satisfy: 2.5 ⁇ h3/t ⁇ 10.
  • the connecting portion 33 is a portion of the electrode lead-out structure 30 that abuts the first tab 114a and the second tab 114b.
  • the connecting portion 33 may be the current collecting member 32 or a part of the current collecting member 32 .
  • the connecting portion 33 is a flat plate structure.
  • the first tab 114a can be flattened, bent or other processes to form a denser end surface 114c, and the end surface 114c can be used to butt against the connecting portion 33 and be welded.
  • the flattened state of the first pole tab 114a refers to restoring the first pole tab 114a to a flat state.
  • the electrode assembly 10 can be disassembled first and the pole piece 11 can be unfolded as a whole, and then a device can be used to re-flatten the first tab 114a, and then the value of h2 can be measured.
  • the flattened state of the second pole tab 114b refers to restoring the second pole tab 114b to a flat state.
  • the electrode assembly 10 can be disassembled first and the pole piece 11 can be unfolded as a whole, and then a device can be used to flatten the second tab 114b again, and then the value of h3 can be measured.
  • h2 the larger the portion of the first tab 114a that can be welded to the connecting portion 33 is, but the space occupied by the first tab 114a is also larger; the smaller the value of t is, the less heat is generated by welding, and the first tab 114a is The lower the connection strength between the ear 114a and the connecting part 33 is, the smaller the overcurrent capacity of the connecting part 33 is. If h2/t is too large, the space occupied by the first tab 114a will be large, the energy density of the battery cell 7 will be insufficient, and the risk of connection failure between the connecting portion 33 and the first tab 114a will be high.
  • this embodiment limits the value of h2/t to 2.5-10 to ensure the connection strength between the connecting part 33 and the first tab 114a, reduce the risk of the first tab 114a being melted through, and improve the energy density.
  • the value of h2/t is limited to 5-7.5.
  • this embodiment limits the value of h3/t to 2.5-10 to ensure the connection strength between the connecting part 33 and the second tab 114b, reduce the risk of the second tab 114b being melted through, and improve the energy density. .
  • the value of h3/t is limited to 5-7.5.
  • the value of h2/t may be 2.5, 4, 5, 7.5, 9, or 10. In some embodiments, the value of h3/t may be 2.5, 4, 5, 7.5, 9, or 10.
  • the connecting portion 33 is welded to the first tab and the second tab and forms a second welding portion.
  • pole piece 11 is wound into multiple turns. In the radial direction of the electrode assembly 10, the distance between two adjacent turns of pole pieces 11 is d3, 0.2mm ⁇ d3 ⁇ 0.4mm.
  • d3 is the radial distance between two adjacent turns of the same pole piece 11.
  • the pole piece 11 (for example, the first pole piece 11a) is wound in multiple turns, and correspondingly, the pole tab 114 is also wound in multiple turns.
  • Another pole piece 11 and a separator 12 of opposite polarity need to be placed between two adjacent turns of a pole piece 11; for example, a second pole piece 11b needs to be placed between two adjacent turns of the first pole piece 11a. and two layers of spacers 12. If the value of d3 is too small, the other pole piece 11 and the isolator 12 will be limited. Therefore, this embodiment limits the value of d3 to be greater than or equal to 0.2 mm to provide space for structures such as spacers.
  • d3 is 0.2mm, 0.25mm, 0.3mm, 0.35mm, or 0.4mm.
  • the electrode lead-out structure 30 has a connecting portion 33 .
  • the electrode assembly 10 also includes a separator 12 , which is laminated and wound with the pole piece 11 . In the first direction
  • S1 The greater the value of t, the greater the heat generated by the welding connection part 33 and the first tab 114a; the smaller S1 is, the shorter the thermal conduction path between the isolation member 12 and the connection part 33, and the heat conduction to the isolation member 12 is The higher the number, the risk of burns to the spacer 12 is too high.
  • This embodiment limits S1 to be greater than or equal to 0.75t to reduce the heat transmitted to the isolation member 12 and reduce the risk of the isolation member 12 being burned.
  • the tab 114 is wound into multiple turns along the winding direction V, and one end of the multi-turn tab 114 away from the active material layer 113 is flattened to form an end surface 114c, and the electrode lead-out structure 30 is welded to the end surface 114c.
  • the tabs 114 can be flattened so that the end areas of the tabs 114 away from the active material layer 113 are gathered and brought together; the flattening process is formed on the end of the tabs 114 away from the active material layer 113
  • the dense end surface 114c reduces the gap and facilitates the connection between the tab 114 and the electrode lead-out structure 30.
  • electrode assembly 10 is generally cylindrical.
  • Figure 12 is a schematic cross-sectional view of a pole piece provided by some embodiments of the present application
  • Figure 13 is a partial structural schematic diagram of a battery cell provided by some embodiments of the present application.
  • the tab 114a in the first direction
  • the tab 114a is bent and connected to the first tab 114a.
  • the electrode lead-out structure 30 has a connecting portion 33.
  • the thickness of the connecting part 33 is t
  • the dimension of the first tab 114a beyond the first welding part 115 along the first direction X in the flattened state is h2.
  • t and h2 satisfy: 5 ⁇ h2/t ⁇ 20.
  • h2 the larger the portion of the first tab 114a that can be welded to the connecting portion 33 is, but the space occupied by the first tab 114a is also larger; the smaller the value of t is, the less heat is generated by welding, and the first tab 114a is The lower the connection strength between the ear 114a and the connecting part 33 is, the smaller the overcurrent capability of the connecting part 33 is. If h2/t is too large, the space occupied by the first tab 114a will be large, the energy density of the battery cell 7 will be insufficient, and the risk of connection failure between the connecting portion 33 and the first tab 114a will be high.
  • the second tab 114b is not welded to the connecting part 33. Therefore, the value of h2/t is limited to 5-20 to ensure the connection strength between the connecting part 33 and the first tab 114a and reduce The risk of melting through the first tab 114a increases the energy density.
  • the value of h2/t is 10-15.
  • the solution in which only the first tab 114a is welded to the connection part 33 requires the first tab 114a to have a larger h2.
  • Figure 14 is a schematic structural diagram of the pole piece in an unfolded state provided by some embodiments of the present application
  • Figure 15 is a partial schematic diagram of the battery cell 7 provided by some embodiments of the present application.
  • the pole tab 114 includes a plurality of pole tab portions 114d spaced apart along the second direction Y.
  • the second direction Y is perpendicular to the first direction X and the thickness of the pole piece 11 Direction Z.
  • the tab portion 114d protrudes from the second portion 112b.
  • first tab 114a includes a plurality of tab portions 114d
  • second tab 114b includes a plurality of tab portions 114d.
  • the pole tab 114 is divided into a plurality of separate pole tab portions 114d to facilitate the bending of the pole tab portions 114d after the pole piece 11 is wound.
  • the pole piece 11 is wound into multiple turns along the winding direction V.
  • the pole tab 114 includes a plurality of pole tab portions 114d spaced apart along the winding direction V.
  • the plurality of pole tab portions 114d are bent toward the winding center of the pole piece 11 to form an end surface 114c.
  • the electrode lead-out structure 30 is welded to the end surface 114c.
  • the plurality of pole tab portions 114d are arranged along the second direction Y. After the pole piece 11 is wound, the plurality of pole tab portions 114d are arranged along the winding direction V.
  • the pole tab portion 114d is bent toward the winding center of the pole piece 11 to cover the gap between two adjacent turns of pole pieces 11 and form a dense end face 114c to facilitate welding with the electrode lead structure 30 and reduce the risk of laser leakage. .
  • the present application also provides a battery including a plurality of battery cells described in any of the above solutions.
  • the present application also provides an electrical device, including the battery cell described in any of the above solutions, and the battery cell is used to provide electrical energy to the electrical device.
  • embodiments of the present application provide a pole piece 11 , which includes an insulating base 111 , a conductive layer 112 , an active material layer 113 and a pole tab 114 .
  • There are two conductive layers 112 and the two conductive layers 112 are respectively disposed on two surfaces of the insulating base 111 .
  • the active material layer 113 is coated on the surface of the conductive layer 112 facing away from the insulating substrate 111.
  • the conductive layer 112 includes a first part 112a coated with the active material layer 113 and a second part 112b not coated with the active material layer 113.
  • the first part 112a and The second portion 112b is arranged along the first direction X.
  • the pole tab 114 includes a first pole tab 114a and a second pole tab 114b.
  • the first pole tab 114a and the second pole tab 114b are respectively welded to the second portions 112b of the two conductive layers 112.
  • the first tab 114a and the second tab 114b are respectively used to draw out the current on the two conductive layers 112.
  • the first tab 114a is welded to the corresponding conductive layer 112 to form a first welding sub-section
  • the second tab 114b is welded to the corresponding conductive layer 112 to form a second welding sub-section.
  • the first welding part 115 includes a first welding sub-part and a second welding sub-part.
  • the pole piece 11 also includes an adhesive layer 116 and an insulating layer 117 .
  • the adhesive layer 116 is connected to the pole lug 114 and covers at least part of the first welding portion 115 .
  • At least part of the insulating layer 117 is located on a side of the adhesive layer 116 away from the first welding portion 115 and is connected to the adhesive layer 116 .
  • the thickness of the conductive layer 112 is d1, the size of the first part 112a along the first direction /( ⁇ mm 4 ⁇ °C).
  • Embodiment 1 can be prepared according to the following steps:
  • the first current collector includes an insulating base 111 and a conductive layer 112 disposed on the surface of the insulating glue.
  • the conductive layer 112 is aluminum foil, and the K value of the aluminum foil is 0.0120 ⁇ mm 4 ⁇ °C/J , the thickness of the aluminum foil is 0.001mm, and the width W of the area where the positive electrode slurry is coated on the aluminum foil is 68.5mm.
  • step (VI) the battery cell is cylindrical, with a diameter of 46mm and a height of 95mm.
  • the battery cells prepared in Example 1 were subjected to energy density detection, temperature detection and cycle performance detection.
  • Energy density detection In an environment of 25°, the battery cell starts to discharge from the upper limit voltage at a rate of 0.33C and ends when it reaches the lower limit voltage.
  • the capacity exerted is the capacity of the battery cell; the battery cell's The capacity is divided by the weight of the battery cell to obtain the energy density G of the battery cell.
  • Temperature detection Fast charge the battery cells and detect the maximum temperature Q of the active material layer of the first pole piece.
  • Fast charging refers to charging a battery cell from 0 to 80% in 25 minutes.
  • a temperature sensor can be built inside the battery cell, and an opening can be opened on the casing to lead out the sensor lead. The temperature sensor can detect the temperature of the active material layer in real time.
  • Cycle performance test In a normal temperature environment, charge the battery cell at a rate of 1C, discharge it at a rate of 1C, and conduct a full-charge-discharge cycle test until the capacity of the battery cell decays to 80% of the initial capacity. Record the number of cycles the battery cells cycle.
  • Example 2 The preparation method and detection method of the battery cell in Example 2 are as in Example 1, except that d1 is 0.0008mm.
  • Example 3 The preparation method and detection method of the battery cell in Example 3 are as in Example 1, except that d1 is 0.0015mm.
  • Example 4 The preparation method and detection method of the battery cell in Example 4 are as in Example 1, except that d1 is 0.002mm.
  • Example 5 The preparation method and detection method of the battery cell in Example 5 are as in Example 1, except that d1 is 0.0025mm.
  • Example 6 The preparation method and detection method of the battery cell in Example 6 are as in Example 1, except that d1 is 0.003mm.
  • Example 7 The preparation method and detection method of the battery cell in Example 7 are as in Example 1, except that d1 is 0.0035 mm.
  • Example 8 The preparation method and detection method of the battery cell in Example 8 are as in Example 1, except that d1 is 0.004 mm.
  • Example 9 The preparation method and detection method of the battery cell in Example 9 are as in Example 1, except that d1 is 0.0045mm.
  • Example 10 The preparation method and detection method of the battery cell in Example 10 are as in Example 1, except that d1 is 0.005mm.
  • Example 11 The preparation method and detection method of the battery cell in Example 11 are as in Example 1, except that d1 is 0.0062mm.
  • Comparative Example 1 The preparation method and detection method of the battery cell in Comparative Example 1 are as in Example 1, except that d1 is 0.0007mm.
  • Comparative Example 2 The preparation method and detection method of the battery cell in Comparative Example 1 are as in Example 1, except that d1 is 0.0065 mm.
  • Comparative Example 3 The preparation method and detection method of the battery cell in Comparative Example 3 are as in Example 1, except that d1 is 0.0074mm.
  • d1/(K ⁇ W) the more heat the conductive layer generates during the charge and discharge process, the higher the temperature, and the active material layer coated on the conductive layer ages. The faster it goes, the faster the battery cell capacity decreases. If d1/(K ⁇ W) is larger, the weight of the conductive layer will also be larger, and the energy density of the battery cell will be lower. The embodiment of this application limits d1/(K ⁇ W) to 0.001J/( ⁇ mm 4 ⁇ °C)-0.0075J/( ⁇ mm 4 ⁇ °C) to balance the energy density and cycle performance of the battery cell.

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  • Chemical & Material Sciences (AREA)
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Abstract

本申请实施例提供一种极片、电池单体、电池以及用电装置。极片包括绝缘基体、导电层和活性物质层。导电层设置于绝缘基体的表面。活性物质层涂覆于导电层背离绝缘基体的表面，导电层包括涂覆有活性物质层的第一部分和未涂覆活性物质层的第二部分，第一部分和第二部分沿第一方向布置。导电层的电阻率为ρ1，导电层的比热容为C，导电层的密度为ρ2，常数K＝ρ1/(C·ρ2)。导电层的厚度为d1，第一部分沿第一方向的尺寸为W，d1、W以及K满足：0.001J/(Ω·mm 4·℃)≤d1/(K·W)≤0.0075J/(Ω·mm 4·℃)。本申请将d1/(K·W)的值限定在0.001J/(Ω·mm 4·℃)-0.0075J/(Ω·mm 4·℃)，平衡电池单体的循环寿命和能量密度。

Description

极片、电池单体、电池以及用电装置 技术领域
本申请涉及电池技术领域，并且更具体地，涉及一种极片、电池单体、电池以及用电装置。
背景技术
电池单体广泛用于电子设备，例如手机、笔记本电脑、电瓶车、电动汽车、电动飞机、电动轮船、电动玩具汽车、电动玩具轮船、电动玩具飞机和电动工具等等。电池单体可以包括镉镍电池单体、氢镍电池单体、锂离子电池单体和二次碱性锌锰电池单体等。
在电池技术的发展中，如何提高电池单体的安全性，是电池技术中的一个研究方向。
发明内容
本申请提供了一种极片、电池单体、电池以及用电装置，其能提高电池单体的安全性。
第一方面，本申请实施例提供了一种极片，包括绝缘基体、导电层和活性物质层。导电层设置于绝缘基体的表面。活性物质层涂覆于导电层背离绝缘基体的表面，导电层包括涂覆有活性物质层的第一部分和未涂覆活性物质层的第二部分，第一部分和第二部分沿第一方向布置。导电层的电阻率为ρ1，导电层的比热容为C，导电层的密度为ρ2，常数K＝ρ1/(C·ρ2)。导电层的厚度为d1，第一部分沿第一方向的尺寸为W，d1、W以及K满足：0.001J/(Ω·mm 4·℃)≤d1/(K·W)≤0.0075J/(Ω·mm 4·℃)。
上述技术方案中，导电层具有较小的厚度，当导电层被外部结构刺穿时，导电层在被刺穿的位置产生毛刺较小，这样可以降低毛刺刺破隔离件的风险，从而减小短路的可能性，提高电池单体的安全性。
d1/(K·W)的值越小，导电层在充放电过程中产热越多，温度越高，涂覆于导电层的活性物质层老化越快，电池单体容量下降的越快。如果d1/(K·W)过大，那么会造成导电层的厚度d1过设计，导致电池单体的能量密度偏低。上述技术方案将d1/(K·W)的值限定在0.001J/(Ω·mm 4·℃)-0.0075J/(Ω·mm 4·℃)，以平衡电池单体的能量密度和循环寿命。
在一些实施方式中，d1、W以及K满足：0.002J/(Ω·mm 4·℃)≤d1/(K·W)≤ 0.003J/(Ω·mm 4·℃)。
在一些实施方式中，d1为0.5μm-5μm。
在一些实施方式中，极片还包括极耳，极耳焊接于第二部分并形成第一焊接部；在第一方向上，极耳背离活性物质层的一端凸出于第二部分。极耳在第一方向上凸出于第二部分的部分可用于与电池单体的电极引出结构连接。
在一些实施方式中，极耳的厚度为d2，d2大于d1。极耳的厚度大于导电层的厚度，以提高极耳的过流能力。
在一些实施方式中，d2为1μm-100μm。
d2越小，极耳的过流面积越小，过流能力越弱。d2越大，极耳的体积和重量越大，极耳与导电层焊接产生的热量越多，极耳和导电层越容易出现焊接不良。上述技术方案将d2的值限定为1μm-100μm，以使极耳满足过流要求，并减小极耳在焊接过程中的产热。
在一些实施方式中，极片还包括粘接层，粘接层连接于极耳并覆盖第一焊接部的至少部分。
在上述技术方案中，粘接层可以固定第一焊接部上的至少部分颗粒，降低颗粒掉入电极组件内的风险，提高安全性。
在一些实施方式中，粘接层的一部分在第一方向上位于活性物质层和极耳之间、涂覆于第二部分并连接于活性物质层。
在上述技术方案中，粘接层连接于活性物质层，其能够覆盖第一部分和第二部分的连接处，降低导电层开裂的风险，保证导电层的过流能力。粘接层还能够将极耳连接到导电层和活性物质层，从而降低极耳脱落的风险。
在一些实施方式中，极片还包括绝缘层，绝缘层的至少部分位于粘接层背离第一焊接部的一侧并连接于粘接层。
在上述技术方案中，绝缘层可以保护粘接层，降低因焊接部刺破粘接层而引发短路的风险，提高安全性。绝缘层还可以提高极片的绝缘性，降低正负极片搭接短路的风险。粘接层还能够将绝缘层连接到极耳，以降低绝缘层脱落的风险。
在一些实施方式中，绝缘层和粘接层均包括粘接剂，绝缘层中的粘接剂与绝缘层的重量比为N1，粘接层中的粘接剂与粘接层的重量比为N2，N1小于N2。
在上述技术方案中，粘接层的粘接剂的含量较高，其可以更好地粘接到第一焊接部，降低粘接层与第一焊接部分离的风险。绝缘层无需与第一焊接部相连，其可包含较少的粘接剂，这样，绝缘层可以设置更多强度较高的材料，以提高绝缘层的整体强度。
在一些实施方式中，绝缘层完全覆盖粘接层，以减少粘接层的外露面积，降低粘接层在电解液的浸泡中与第一焊接部分离的风险。
在一些实施方式中，极片还包括绝缘层，绝缘层连接于极耳和活性物质层，且绝缘层覆盖第一焊接部的至少部分。
在上述技术方案中，绝缘层可以固定第一焊接部上的至少部分颗粒，降低颗粒掉入电极组件内的风险，提高安全性。
在一些实施方式中，绝缘层包括陶瓷颗粒和粘接剂，粘结剂与绝缘层的重量比大于或等于0.1。绝缘层中的粘接剂的含量较高，其可以更好地粘接到第一焊接部，降低绝缘层与第一焊接部分离的风险。
在一些实施方式中，在第一方向上，极耳的超出导电层的部分未涂覆绝缘层，以降低绝缘层与电极引出结构干涉的风险。
在一些实施方式中，极耳包括多个沿第二方向间隔设置的极耳部，第二方向垂直于第一方向和极片的厚度方向。在第一方向上，极耳部凸出于第二部分。
上述技术方案将极耳分割为多个分离的极耳部，便于极耳部在极片卷绕后弯折。
第二方面，本申请实施例提供了一种电池单体，其包括外壳、电极组件和电极引出结构。电极组件容纳于外壳内。电极组件包括第一方面任一实施方式的极片。电极引出结构设置于外壳并连接于极耳。
在一些实施方式中，导电层设置为两个，两个导电层分别设于绝缘基体的两侧。极耳包括第一极耳和第二极耳，第一极耳和第二极耳分别焊接于两个导电层的第二部分。第一极耳和第二极耳分别用于将两个导电层上的电流引出。
在一些实施方式中，电极引出结构具有连接部，在第一方向上，连接部位于第一极耳背离活性物质层的一侧，连接部与第一极耳相抵并焊接、与第二极耳相抵并焊接。连接部的厚度为t，第一极耳在展平状态下沿第一方向超出第一焊接部的尺寸为h2，t和h2满足：2.5≤h2/t≤10。第二极耳在展平状态下沿第一方向超出第一焊接部的尺寸为h3，t和h3满足：2.5≤h3/t≤10。
在上述技术方案中，h2越大，第一极耳的能够与连接部焊接的部分越大，但第一极耳占用的空间也越大；t的值越小，焊接产生的热量越少，第一极耳与连接部的连接强度越低，连接部的过流能力越小。h2越小，第一极耳的能够与连接部焊接的部分越小，但第一极耳占用的空间也越小；t的值越大，焊接产生的热量越多，传递到第一极耳和隔离件上的热量越多，极耳和隔离件被烧伤的风险越高。上述技术方案将h2/t的值限定在2.5-10，以保证连接部和第一极耳之间的连接强度，降低第一极耳被熔穿的风险，提高能量密度。同样地，上述技术方案将h3/t的值限定在2.5-10，以保证连接部和第二极耳之间的连接强度，降低第二极耳被熔穿的风险，提高能量密度。
在一些实施方式中，在第一方向上，第一极耳的背离活性物质层的一端超出第二极耳，第二极耳朝向第一极耳弯折并连接于第一极耳。电极引出结构具有连接部，在第一方向上，连接部位于第一极耳背离活性物质层的一侧，连接部与第一极耳相抵并焊接。连接部的厚度为t，第一极耳在展平状态下沿第一方向超出第一焊接部的尺寸为h2，t和h2满足：5≤h2/t≤20。
第二极耳不与连接部焊接，因此，上述技术方案将h2/t的值限定在5-20，以保证连接部和第一极耳之间的连接强度，降低第一极耳被熔穿的风险，提高能量密度。与第一极耳和第二极耳同时焊接到连接部的方案相比，仅第一极耳与连接部焊接的方案需要使第一极耳具有更大h2。
在一些实施方式中，极片卷绕为多圈。在电极组件的径向上，相邻两圈的极片之间的间距为d3，0.2mm≤d3≤0.4mm。
在上述技术方案中，极片卷绕为多圈，对应地，极耳也卷绕为多圈。d3的值越大，相邻的两圈极耳之间的间距也越大，在焊接极耳和电极引出结构时，激光从极耳之间穿过的风险越高。如果d3的值过大，那么电极组件的隔离件可能被激光烧伤，引发安全风险。因此，上述技术方案将d3的值限定为小于或等于0.4mm，以提高安全性。
在一些实施方式中，电极引出结构具有连接部，在第一方向上，连接部位于极耳背离活性物质层的一侧，连接部与极耳相抵并焊接。电极组件还包括隔离件，隔离件与极片层叠并卷绕。在第一方向上，连接部的与第一极耳相抵的表面与隔离件的最小距离为S1，连接部的厚度为t，S1≥0.75t。
t的值越大，焊接连接部与第一极耳产生的热量也就越大；S1越小，隔离件与连接部之间的导热路径越短，传导至隔离件的热量越多，隔离件被烧伤的风险过高。上述技术方案将S1限定为大于或等于0.75t，以减少传导至隔离件的热量，降低隔离件被烧伤的风险。
在一些实施方式中，极耳沿卷绕方向卷绕为多圈，多圈极耳的背离活性物质层的一端揉平并形成端面，电极引出结构焊接于端面。
在一些实施方式中，极片沿卷绕方向卷绕为多圈。极耳包括多个沿卷绕方向间隔设置的极耳部，多个极耳部朝向极片的卷绕中心弯折以形成端面，电极引出结构焊接于端面。
第三方面，本申请实施例提供了一种电池，包括多个第二方面任一实施方式的电池单体。
第四方面，本申请实施例提供了一种用电装置，包括第二方面任一实施方式的电池单体，电池单体用于提供电能。
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例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据附图获得其他的附图。
图1为本申请一些实施例提供的车辆的结构示意图；
图2为本申请一些实施例提供的电池的爆炸示意图；
图3为图2所示的电池模块的结构示意图；
图4为本申请一些实施例提供的电池单体的爆炸示意图；
图5为本申请一些实施例提供的电池单体的局部剖视示意图；
图6为本申请一些实施例提供的电池单体的电极组件的结构示意图；
图7为本申请一些实施例提供的极片的结构示意图；
图8为图7所示的极片沿线A-A作出的剖视示意图；
图9为本申请一些实施例提供的极片的剖视示意图；
图10为本申请另一些实施例提供的极片的剖视示意图；
图11为本申请一些实施例提供的电池单体的局部结构示意图；
图12为本申请又一些实施例提供的极片的剖视示意图；
图13为本申请一些实施例提供的电池单体的局部结构示意图；
图14为本申请再一些实施例提供的极片在展开状态下的结构示意图；
图15为本申请一些实施例提供的电池单体的局部示意图。
具体实施方式的附图标记如下：
1、车辆；2、电池；3、控制器；4、马达；5、箱体；5a、第一箱体部；5b、第二箱体部；5c、容纳空间；6、电池模块；7、电池单体；10、电极组件；11、极片；111、绝缘基体；112、导电层；112a、第一部分；112b、第二部分；113、活性物质层；114、极耳；114a、第一极耳；114b、第二极耳；114c、端面；114d、极耳部；115、第一焊接部；116、粘接层；117、绝缘层；11a、第一极片；11b、第二极片；12、隔离件；20、外壳；21、壳体；22、端盖；30、电极引出结构；31、电极端子；32、集流构件；33、连接部；V、卷绕方向；X、第一方向；Y、第二方向；Z、厚度方向。
具体实施方式
为使本申请实施例的目的、技术方案和优点更加清楚，下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行清楚地描述，显然，所描述的实施例是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他实施例，都属于本申请保护的范围。
除非另有定义，本申请所使用的所有的技术和科学术语与属于本申请的技术领域的技术人员通常理解的含义相同；本申请中在申请的说明书中所使用的术语只是为了描述具体的实施例的目的，不是旨在于限制本申请；本申请的说明书和权利要求书及上述附图说明中的术语“包括”和“具有”以及它们的任何变形，意图在于覆盖不排他的包含。本申请的说明书和权利要求书或上述附图中的术语“第一”、“第二”等是用于区别不同对象，而不是用于描述特定顺序或主次关系。
在本申请中提及“实施例”意味着，结合实施例描述的特定特征、结构或特性可以包含在本申请的至少一个实施例中。在说明书中的各个位置出现该短语并不一定均是指相同的实施例，也不是与其它实施例互斥的独立的或备选的实施例。
在本申请的描述中，需要说明的是，除非另有明确的规定和限定，术语“安装”、“相连”、“连接”、“附接”应做广义理解，例如，可以是固定连接，也可以是可拆卸连接，或一体地连接；可以是直接相连，也可以通过中间媒介间接相连，可以是两个元件内部的连通。对于本领域的普通技术人员而言，可以根据具体情况理解上述术语在本申请中的具体含义。
本申请中术语“和/或”，仅仅是一种描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B这三种情况。另外，本申请中字符“/”，一般表示前后关联对象是一种“或”的关系。
在本申请的实施例中，相同的附图标记表示相同的部件，并且为了简洁，在不同实施例中，省略对相同部件的详细说明。应理解，附图示出的本申请实施例中的各种部件的厚度、长宽等尺寸，以及集成装置的整体厚度、长宽等尺寸仅为示例性说明，而不应对本申请构成任何限定。
本申请中出现的“多个”指的是两个以上(包括两个)。
本申请中术语“平行”不仅包括绝对平行的情况，也包括了工程上常规认知的大致平行的情况；同时，“垂直”也不仅包括绝对垂直的情况，还包括工程上常规认知的大致垂直的情况。
本申请中，电池单体可以包括锂离子二次电池单体、锂离子一次电池单体、锂硫电池单体、钠锂离子电池单体、钠离子电池单体或镁离子电池单体等，本申请实施例对此并不限定。电池单体可呈圆柱体、扁平体、长方体或其它形状等，本申请实施例对此也不限定。
本申请的实施例所提到的电池是指包括一个或多个电池单体以提供更高的电压和容量的单一的物理模块。电池一般还可包括用于封装一个或多个电池单体的箱体。箱体可以避免液体或其他异物影响电池单体的充电或放电。
电池单体包括电极组件和电解液，电极组件包括正极极片、负极极片和隔离件。电池单体主要依靠金属离子在正极极片和负极极片之间移动来工作。正极极片包括正极集流体和正极活性物质层，正极活性物质层涂覆于正极集流体的表面。以锂离子电池为例，正极集流体的材料可以为铝，正极活性物质层包括正极活性物质，正极活性物质可以为钴酸锂、磷酸铁锂、三元锂或锰酸锂等。负极极片包括负极集流体和负极活性物质层，负极活性物质层涂覆于负极集流体的表面。负极集流体的材料可以为铜，负极活性物质层包括负极活性物质，负极活性物质可以为碳或硅等。隔离件的材质可以为PP(polypropylene，聚丙烯)或PE(polyethylene，聚乙烯)等。
在电池单体中，集流体(例如正极集流体或负极集流体)是不可或缺的一部分，它不仅起到承载活性物质的作用，也将电化学反应所产生的电子汇集起来引导至外电路，从而实现化学能转化为电能的过程。
在相关技术中，集流体一般采用金属箔材，而金属箔材具有较大的重量，制约了电池单体能量密度的进一步提升。在电池单体的使用过程中，当极片的集流体被外部结构刺穿时，集流体会在被刺穿的位置产生毛刺，毛刺容易刺破隔离件并导致正负极导通，从而造成电池单体内部短路，引发电池单体起火、爆炸的风险。
为了提高安全性，发明人设计了一种极片，其采用具有多层结构的集流体。具体地，集流体可包括绝缘基体和设置于绝缘基体的表面的导电层，极片的活性物质层可涂覆于导电层背离绝缘基体的表面。导电层可以将电化学反应所产生的电子汇集起来引导至外电路。在厚度相同的情况下，与由金属箔材制成的集流体相比，包括绝缘基体的具有多层结构的集流体具有较小的重量，从而进一步提升电池单体的能量密度。导电层具有较小的厚度，当集流体被外部结构刺穿时，导电层在被刺穿的位置产生毛刺较小，这样可以降低毛刺刺破隔离件的风险，从而减小短路的可能性，提高电池单体的安全性。
发明人注意到，虽然具有多层结构的集流体减小了导电层的厚度，但导电层的厚度的减小也会降低导电层的载流能力，如果导电层的厚度过小，会造成导电层产热严重，影响电池单体的循环寿命。
鉴于此，本申请实施例提供了一种极片，其结合导电层的载流能力、极片的尺寸来调整导电层的厚度，以在满足导电层的载流需求的前提下，减小导电层的厚度，从而延长电池单体的循环寿命，提高电池单体的能量密度。
本申请实施例描述的极片适用于电池单体、电池以及使用电池的用电装置。
用电装置可以是车辆、手机、便携式设备、笔记本电脑、轮船、航天器、电动玩具和电动工具等等。车辆可以是燃油汽车、燃气汽车或新能源汽车，新能源汽车可以是纯电动汽车、混合动力汽车或增程式汽车等；航天器包括飞机、火箭、航天飞机和宇宙飞船等等；电动玩具包括固定式或移动式的电动玩具，例如，游戏机、电动汽车玩具、电动轮船玩具和电动飞机玩具等等；电动工具包括金属切削电动工具、研磨电动工具、装配电动工具和铁道用电动工具，例如，电钻、电动砂轮机、电动扳手、电动螺丝刀、电锤、冲击电钻、混凝土振动器和电刨等等。本申请实施例对上述用电装置不做特殊限制。
以下实施例为了方便说明，以用电装置为车辆为例进行说明。
图1为本申请一些实施例提供的车辆的结构示意图。
如图1所示，车辆1的内部设置有电池2，电池2可以设置在车辆1的底部或头部或尾部。电池2可以用于车辆1的供电，例如，电池2可以作为车辆1的操作电源。
车辆1还可以包括控制器3和马达4，控制器3用来控制电池2为马达4供电，例如，用于车辆1的启动、导航和行驶时的工作用电需求。
在本申请一些实施例中，电池2不仅仅可以作为车辆1的操作电源，还可以作为车辆1的驱动电源，代替或部分地代替燃油或天然气为车辆1提供驱动动力。
图2为本申请一些实施例提供的电池的爆炸示意图。
如图2所示，电池2包括箱体5和电池单体(图2未示出)，电池单体容纳于箱体5内。
箱体5用于容纳电池单体，箱体5可以是多种结构。在一些实施例中，箱体5可以包括第一箱体部5a和第二箱体部5b，第一箱体部5a与第二箱体部5b相互盖合，第一箱体部5a和第二箱体部5b共同限定出用于容纳电池单体的容纳空间5c。第二箱体部5b可以是一端开口的空心结构，第一箱体部5a为板状结构，第一箱体部5a盖合于第二箱体部5b的开口侧，以形成具有容纳空间5c的箱体5；第一箱体部5a和第二箱体部5b也均可以是一侧开口的空心结构，第一箱体部5a的开口侧盖合于第二箱体部5b的开口侧，以形成具有容纳空间5c的箱体5。当然，第一箱体部5a和第二箱体部5b可以是多种形状，比如，圆柱体、长方体等。
为提高第一箱体部5a与第二箱体部5b连接后的密封性，第一箱体部5a与第二箱体部5b之间也可以设置密封件，比如，密封胶、密封圈等。
假设第一箱体部5a盖合于第二箱体部5b的顶部，第一箱体部5a亦可称之为上 箱盖，第二箱体部5b亦可称之为下箱体。
在电池2中，电池单体可以是一个，也可以是多个。若电池单体为多个，多个电池单体之间可串联或并联或混联，混联是指多个电池单体中既有串联又有并联。多个电池单体之间可直接串联或并联或混联在一起，再将多个电池单体构成的整体容纳于箱体5内；当然，也可以是多个电池单体先串联或并联或混联组成电池模块6，多个电池模块6再串联或并联或混联形成一个整体，并容纳于箱体5内。
图3为图2所示的电池模块的结构示意图。
如图3所示，在一些实施例中，电池单体7为多个，多个电池单体7先串联或并联或混联组成电池模块6。多个电池模块6再串联或并联或混联形成一个整体，并容纳于箱体内。
电池模块6中的多个电池单体7之间可通过汇流部件实现电连接，以实现电池模块6中的多个电池单体7的并联或串联或混联。
电池单体7可以是圆柱电池单体、方形电池单体或其它形状的电池单体。
图4为本申请一些实施例提供的电池单体的爆炸示意图；图5为本申请一些实施例提供的电池单体的局部剖视示意图；图6为本申请一些实施例提供的电池单体的电极组件的结构示意图。
如图4至图6所示，本申请实施例的电池单体7包括外壳20和电极组件10，电极组件10容纳于外壳20内。
外壳20为空心结构，其内部形成用于容纳电极组件10和电解液的容纳腔。外壳20的形状可根据电极组件10的具体形状来确定。比如，若电极组件10为圆柱体结构，则可选用为圆柱体外壳；若电极组件10为长方体结构，则可选用长方体外壳。可选地，电极组件10和外壳20均为圆柱状。
在一些实施例中，外壳20包括壳体21和端盖22，壳体21具有开口，端盖22连接于壳体21并用于盖合开口。
端盖22与壳体21密封连接，以形成用于容纳电极组件10和电解液的密封空间。在一些示例中，壳体21的一端具有开口，端盖22设置为一个并盖合于壳体21的开口。在另一些示例中，壳体21相对的两端均具有开口，端盖22设置为两个，两个端盖22分别盖合于壳体21的两个开口。
在一些实施例中，电极组件10包括极片和隔离件12。示例性地，极片设置为多个，多个极片包括极性相反的第一极片11a和第二极片11b，隔离件12用于将第一极片11a和第二极片11b绝缘隔离。电极组件10主要依靠金属离子在第一极片11a和第二极片11b之间移动来工作。
第一极片11a和第二极片11b中的一者为正极极片，第一极片11a和第二极片11b中的另一者为负极极片。
在一些实施例中，第一极片11a、第二极片11b和隔离件12均为带状结构，第一极片11a、第二极片11b和隔离件12绕中心轴线卷绕为一体并形成卷绕结构。卷绕结构可以为圆柱状结构、扁平状结构或其它形状的结构。
在一些实施例中，电池单体7还包括电极引出结构30，设置于外壳20并用于 与电极组件10电连接，以将电极组件10产生的电能导出。
在一些实施例中，电极引出结构30包括电极端子31，电极端子31的至少部分露出到外壳20的外部，以实现与其它结构(例如汇流部件)的电连接。
在一些实施例中，电极端子31的至少部分容纳于外壳20内并与极片直接连接，示例性地，电极端子31焊接于极片。
在另一些实施例中，电极引出结构30还包括集流构件32，集流构件32用于连接极片和电极端子31。示例性地，在装配时，可先将第一极片11a与集流构件32焊接，再将集流构件32于电极端子31焊接。
在又一些实施例中，电极引出结构30可与外壳20一体设置。示例性地，电极引出结构30与端盖22一体设置，第一极片11a可直接焊接于端盖22。
图7为本申请一些实施例提供的极片的结构示意图；图8为图7所示的极片沿线A-A作出的剖视示意图。
如图7和图8所示，本申请实施例的极片11包括绝缘基体111、导电层112和活性物质层113。导电层112设置于绝缘基体111的表面。活性物质层113涂覆于导电层112背离绝缘基体111的表面，导电层112包括涂覆有活性物质层113的第一部分112a和未涂覆活性物质层113的第二部分112b，第一部分112a和第二部分112b沿第一方向X布置。导电层112的电阻率为ρ1，导电层112的比热容为C，导电层112的密度为ρ2，常数K＝ρ1/(C·ρ2)。导电层112的厚度为d1，第一部分112a沿第一方向X的尺寸为W，d1、W以及K满足：0.001J/(Ω·mm 4·℃)≤d1/(K·W)≤0.0075J/(Ω·mm 4·℃)。
在本申请实施例中，导电层112可以设置在绝缘基体111的一侧表面上，也可以设置于绝缘基体111的相对的两侧表面上。在本申请实施例中，厚度d1指的是设于绝缘基体111一侧表面上的导电层112的厚度。示例性地，绝缘基体111两侧表面上均设有导电层112，且两侧表面上的导电层112的厚度均为d1。
本实施例的极片11可以是电极组件10中的正极极片，也可以是电极组件10中的负极极片。
示例性地，绝缘基体111的两侧表面上均设有导电层112，各导电层112的表面涂覆有活性物质层113。
第一部分112a的背离绝缘基体111的表面被活性物质层113覆盖，第二部分112b的背离绝缘基体111的表面未被活性物质层113覆盖。第二部分112b的背离绝缘基体111的表面可以露出，也可以涂覆其它不包含活性物质的涂层。
活性物质层113用于与电解液发生电化学，以产生电流。第一部分112a可以将产生的电流汇集在一起，并通过第二部分112b将电流引导至外电路。
示例性地，活性物质层113沿第一方向X的尺寸与第一部分112a沿第一方向X的尺寸相同。
导电层112的载流能力与其电阻率ρ1、比热容C以及密度ρ2存在关联。具体地，K值越小，导电层112的载流能力越高；K值越大，导电层112的载流能力越弱。
d1的值越小，导电层112的电阻越大，在电流经过时产热越高；K值越大，导 电层112的载流能力越弱。
在充放电过程中，第一部分112a将活性物质层113产生的电流汇集到一起，并将电流传导至第二部分112b。第一部分112a远离第二部分112b的区域收集的电流，需要通过第一部分112a靠近第二部分112b的区域才能流动到第二部分112b，因此，在充放电过程中，流经第一部分112a靠近第二部分112b的区域的电流较大，第一部分112a的靠近第二部分112b的区域的产热较多。W的值越大，活性物质层113的容量也大，活性物质层113在充放电过程中产生的电流越大，第一部分112a靠近第二部分112b的区域的产热越高。
综上所述，d1/(K·W)的值越小，导电层112在充放电过程中产热越多，温度越高，涂覆于导电层112的活性物质层113老化越快，电池单体7容量下降的越快。如果d1/(K·W)的值过小，那么在大倍率充放电的工况下，极片11的温度过高，造成活性物质层113加速老化，电池单体7无法满足寿命要求，甚至引发安全问题。
发明人经过研究和试验，将d1/(K·W)的值限定为大于或等于0.001J/(Ω·mm 4·℃)，以减少极片11在充放电过程中的产热，降低电池单体7的温度，使电池单体7能够适用于大倍率充放电的工况，保证电池单体7的循环寿命，降低安全风险。
d1的值越大，导电层112的体积和重量也越大，电池单体7的能量密度也越低。K的值越小，导电层112的载流能力越高，极片11对导电层112厚度的需求也就越小。W的值越小，导电层112上的电流也越小，极片11对导电层112厚度的需求也就越小。
如果d1/(K·W)过大，那么会造成导电层112的厚度d1过设计，导致电池单体7的能量密度偏低。
发明人经过研究和试验，将d1/(K·W)的值限定为小于或等于0.0075J/(Ω·mm 4·℃)，以在导电层112的载流能力和产热满足要求时，减小导电层112的厚度，提高电池单体7的能量密度，延长电池单体7的循环寿命。
在一些实施例中，导电层112可为铜箔、铝箔或镍箔。示例性地，铜箔的K值为0.0050Ω·mm 4·℃/J，铝箔的K值为0.0120Ω·mm 4·℃/J，镍箔的K值为0.0167Ω·mm 4·℃/J。
在一些实施例中，d1/(K·W)的值为0.001J/(Ω·mm 4·℃)、0.002J/(Ω·mm 4·℃)、0.003J/(Ω·mm 4·℃)、0.005J/(Ω·mm 4·℃)、0.007J/(Ω·mm 4·℃)或0.0075J/(Ω·mm 4·℃)。
在一些实施例中，d1、W以及K满足：0.002J/(Ω·mm 4·℃)≤d1/(K·W)≤0.003J/(Ω·mm 4·℃)。
在一些实施例中，d1为0.5μm-5μm。可选地，d1为0.5μm、1μm、2μm、3μm、4μm或5μm。
在一些实施例中，极片11还包括极耳114，极耳114焊接于第二部分112b并形成第一焊接部115。在第一方向X上，极耳114背离活性物质层113的一端凸出于第二部分112b。
在极片11的厚度方向Z上，极耳114的一部分与第二部分112b重叠；极耳114的与第二部分112b重叠的部分焊接于第二部分112b并形成第一焊接部115。
极耳114可用于将第二部分112b上的电流引出。
极耳114在第一方向X上凸出于第二部分112b的部分可用于与电极引出结构连接。
在一些实施例中，极耳114的厚度为d2，d2大于d1。极耳114的厚度大于导电层112的厚度，以提高极耳114的过流能力。
在一些实施例中，d2为1μm-100μm。
d2越小，极耳114的过流面积越小，过流能力越弱。d2越大，极耳114的体积和重量越大，极耳114与导电层112焊接产生的热量越多，极耳114和导电层112越容易出现焊接不良。发明人将d2的值限定为1μm-100μm，以使极耳114满足过流要求，并减小极耳114在焊接过程中的产热。
在一些实施例中，导电层112设置为两个，两个导电层112分别设于绝缘基体111的两侧。极耳114包括第一极耳114a和第二极耳114b，第一极耳114a和第二极耳114b分别焊接于两个导电层112的第二部分112b。第一极耳114a和第二极耳114b分别用于将两个导电层112上的电流引出。
前述的d2指的是单个极耳114的厚度。示例性地，第一极耳114a和第二极耳114b的厚度均为d2。
在第一方向X上，第一极耳114a的尺寸和第二极耳114b的尺寸可以相同，也可以不同。在一些示例中，第一极耳114a的背离活性物质层113的一端与第二极耳114b的背离活性物质层113的一端齐平。在另一些示例中，第一极耳114a的背离活性物质层113的一端超出第二极耳114b，第二极耳114b朝向第一极耳114a弯折并连接于第一极耳114a。
在一些实施例中，第一极耳114a与对应的导电层112焊接并形成第一焊接子部，第二极耳114b与对应的导电层112焊接并形成第二焊接子部。第一焊接部115包括第一焊接子部和第二焊接子部。
在一些示例中，绝缘基体111将第一焊接子部和第二焊接子部隔开。在另一些示例中，绝缘基体111的一部分被焊穿，第一焊接子部和第二焊接子部直接连成一体。
图9为本申请一些实施例提供的极片的剖视示意图。
如图9所示，在一些实施例中，极片11还包括粘接层116，粘接层116连接于极耳114并覆盖第一焊接部115的至少部分。
粘接层116可以覆盖第一焊接部115的一部分，也可以覆盖第一焊接部115的全部。
粘接层116可以仅涂覆在极耳114上，也可以同时涂覆在导电层112和极耳114上。
第一焊接部115上会残留一些颗粒，在电池单体7受到外部冲击时，这些颗粒可能会掉入到电极组件的内部，引发短路风险。本实施例的粘接层116可以固定第一焊接部115上的至少部分颗粒，降低颗粒掉入电极组件内的风险，提高安全性。
在一些实施例中，粘接层116由胶体固化而成。示例性地，胶体包括粘接剂，粘接剂可包括环氧树脂、丙烯酸酯和丁苯橡胶中的至少一种。
在一些实施例中，胶体包括陶瓷颗粒，陶瓷颗粒可包括勃姆石、氧化硅和氧化锆中的至少一种。陶瓷颗粒可增强粘接层116的刺破强度和绝缘性。
在一些实施例中，胶体包括颜色识别剂，例如炭、普鲁士蓝等。
在一些实施例中，胶体的粘度为1000MPa·s。胶体在涂覆时具有良好的流动性，能够覆盖第一焊接部115的凹凸不平的区域，降低漏涂风险。
在一些实施例中，粘接层116的厚度为0.01mm-0.1mm。粘接层116具有良好的韧性和强度，其在电极组件10的卷绕成型的过程中不易脱落。
在一些实施例中，粘接层116的一部分在第一方向X上位于活性物质层113和极耳114之间、涂覆于第二部分112b并连接于活性物质层113。
在极片11的成型过程中，一般需要辊压活性物质层113，以提高活性物质层113的压实密度。在辊压时，第一部分112a受力而第二部分112b不受力，这造成第一部分112a和第二部分112b的连接处容易产生应力集中，引发第一部分112a和第二部分112b的连接处开裂的风险。
粘接层116连接于活性物质层113，其能够覆盖第一部分112a和第二部分112b的连接处，降低导电层112开裂的风险，保证导电层112的过流能力。粘接层116还能够将极耳114连接到导电层112和活性物质层113，从而降低极耳114脱落的风险。
在一些实施例中，极片11还包括绝缘层117，绝缘层117的至少部分位于粘接层116背离第一焊接部115的一侧并连接于粘接层116。
绝缘层117可以保护粘接层116，降低因焊接部刺破粘接层116而引发短路的风险，提高安全性。绝缘层117还可以提高极片11的绝缘性，降低正负极片搭接短路的风险。粘接层116还能够将绝缘层117连接到极耳114，以降低绝缘层117脱落的风险。
在一些实施例中，绝缘层117完全覆盖粘接层116，以减少粘接层116的外露面积，降低粘接层116在电解液的浸泡中与第一焊接部115分离的风险。
在本实施例中，覆盖指的是在厚度方向Z上覆盖，即绝缘层117在极片11的厚度方向Z上完全覆盖粘接层116。
在一些实施例中，绝缘层117和粘接层116均包括粘接剂，绝缘层117中的粘接剂与绝缘层117的重量比为N1，粘接层116中的粘接剂与粘接层116的重量比为N2，N1小于N2。
粘接层116的粘接剂的含量较高，其可以更好地粘接到第一焊接部115，降低粘接层116与第一焊接部115分离的风险。绝缘层117无需与第一焊接部115相连，其可包含较少的粘接剂，这样，绝缘层117可以设置更多强度较高的材料，以提高绝缘层117的整体强度。
在一些实施例中，绝缘层117由绝缘浆料固化而成。绝缘浆料可包括陶瓷颗粒和粘接剂，陶瓷颗粒可包括氧化铝、氧化硅和氧化锆中的至少一种，粘接剂包括聚偏氟乙烯(PVDF)和聚四氟乙烯(PTFE)中的至少一种。
在一些实施例中，绝缘浆料的粘度为3000MPa·s-10000MPa·s。
在一些实施例中，用于制备绝缘层117的绝缘浆料的粘度大于用于制备粘接层116的胶体的粘度。低粘度的胶体在涂覆成型时具有较好的流动性，以覆盖第一焊接部115的凹凸不平的区域，降低漏涂风险；高粘度的绝缘浆料可以在成型后具有较高的强度，以降低绝缘层117被刺破的风险。
在一些实施例中，绝缘层117的厚度为0.005mm-0.5mm。
在一些实施例中，绝缘层117还包括分散剂，例如羧甲基纤维素钠等。
在一些实施例中，在第一方向X上，极耳114的超出导电层112的部分未涂覆绝缘层117。
极耳114的超出导电层112的部分用于与电极引出结构相连，如果绝缘层117涂覆到极耳114的超出导电层112的部分，可能会干涉极耳114与电流引出结构的连接。因此，可选地，极耳114的超出导电层112的部分未涂覆绝缘层117。
在一些实施例中，极片11可按照下述步骤成型：提供绝缘基体111和导电层112，导电层112设置于绝缘基体111的表面；在导电层112的背离绝缘基体111的表面涂布活性浆料，活性浆料固化后形成活性物质层113；将极耳114焊接于导电层112的未涂覆活性物质层113的部分并形成第一焊接部115；在导电层112和极耳114上涂覆胶体，以使胶体覆盖第一焊接部115；在胶体上涂覆绝缘浆料。
胶体固化后形成粘接层116，绝缘浆料固化后形成绝缘层117。
图10为本申请另一些实施例提供的极片的剖视示意图。
如图10所示，在一些实施例中，极片11还包括绝缘层117，绝缘层117连接于极耳114和活性物质层113，且绝缘层117覆盖第一焊接部115的至少部分。
绝缘层117可以固定第一焊接部115上的至少部分颗粒，降低颗粒掉入电极组件10内的风险，提高安全性。
在一些实施例中，极片11可以省略粘接层，绝缘层117直接粘接在第一焊接部115上。
在一些实施例中，绝缘层117包括陶瓷颗粒和粘接剂，粘结剂与绝缘层117的重量比大于或等于0.1。
绝缘层117中的粘接剂的含量较高，其可以更好地粘接到第一焊接部115，降低绝缘层117与第一焊接部115分离的风险。
图11为本申请一些实施例提供的电池单体的局部结构示意图。
请一并参照图4至图11，本申请实施例还提供了一种电池单体7，其包括外壳20、电极组件10和电极引出结构30。电极组件10容纳于外壳20内。电极组件10包括前述任一实施例的极片11。电极引出结构30设置于外壳20并连接于极耳114。电极引出结构30用于将电极组件10产生的电能导出。
在一些实施例中，导电层112设置为两个，两个导电层112分别设于绝缘基体111的两侧。极耳114包括第一极耳114a和第二极耳114b，第一极耳114a和第二极耳114b分别焊接于两个导电层112的第二部分112b。
第一极耳114a和第二极耳114b分别用于将两个导电层112上的电流引出。
在一些实施例中，电极引出结构30具有连接部33，在第一方向X上，连接部33位于第一极耳114a背离活性物质层113的一侧，连接部33与第一极耳114a相抵并焊接、与第二极耳114b相抵并焊接。连接部33的厚度为t，第一极耳114a在展平状态下沿第一方向X超出第一焊接部115的尺寸为h2，t和h2满足：2.5≤h2/t≤10。第二极耳114b在展平状态下沿第一方向X超出第一焊接部115的尺寸为h3，t和h3满足：2.5≤h3/t≤10。
连接部33为电极引出结构30与第一极耳114a和第二极耳114b相抵的部分。示例性地，连接部33可为集流构件32，也可为集流构件32的一部分。可选地，连接部33为平板结构。
第一极耳114a可经过揉平、弯折或其它工序，以形成较为致密的端面114c，端面114c可用于与连接部33相抵并焊接。
第一极耳114a的展平状态是指，将第一极耳114a恢复到平直状态。示例性地，可先将电极组件10拆解并将极片11整体展开，然后使用设备将第一极耳114a重新压平，然后测量h2的值。
同样地，第二极耳114b的展平状态是指，将第二极耳114b恢复到平直状态。示例性地，可先将电极组件10拆解并将极片11整体展开，然后使用设备将第二极耳114b重新压平，然后测量h3的值。
h2越大，第一极耳114a的能够与连接部33焊接的部分越大，但第一极耳114a占用的空间也越大；t的值越小，焊接产生的热量越少，第一极耳114a与连接部33的连接强度越低，连接部33的过流能力越小。如果h2/t过大，将会造成第一极耳114a占用的空间大，电池单体7的能量密度不足，连接部33和第一极耳114a之间出现连接失效的风险较高。
h2越小，第一极耳114a的能够与连接部33焊接的部分越小，但第一极耳114a占用的空间也越小；t的值越大，焊接产生的热量越多，传递到第一极耳114a和隔离件12上的热量越多，极耳114和隔离件12被烧伤的风险越高。如果h2/t过小，第一极耳114a和隔离件12被烧伤的风险较高。
鉴于此，本实施例将h2/t的值限定在2.5-10，以保证连接部33和第一极耳114a之间的连接强度，降低第一极耳114a被熔穿的风险，提高能量密度。可选地，h2/t的值限定在5-7.5。
同样地，本实施例将h3/t的值限定在2.5-10，以保证连接部33和第二极耳114b之间的连接强度，降低第二极耳114b被熔穿的风险，提高能量密度。可选地，h3/t的值限定在5-7.5。
在一些实施例中，h2/t的值可为2.5、4、5、7.5、9或10。在一些实施例中，h3/t的值可为2.5、4、5、7.5、9或10。
在一些实施例中，连接部33焊接于第一极耳和第二极耳并形成第二焊接部。
在一些实施例中，极片11卷绕为多圈。在电极组件10的径向上，相邻两圈的极片11之间的间距为d3，0.2mm≤d3≤0.4mm。
d3是同一个极片11的相邻两圈在径向上的间距。
极片11(例如第一极片11a)卷绕为多圈，对应地，极耳114也卷绕为多圈。d3的值越大，相邻的两圈极耳114之间的间距也越大，在焊接极耳114和电极引出结构时，激光从极耳114之间穿过的风险越高。如果d3的值过大，那么电极组件10的隔离件12可能被激光烧伤，引发安全风险。因此，本实施例将d3的值限定为小于或等于0.4mm，以提高安全性。
一个极片11的相邻两圈之间需要设置另一个极性相反的极片11和隔离件12；例如，第一极片11a的相邻两圈之间需要设置一圈第二极片11b和两层隔离件12。如果d3的值过小，将会造成该另一个极片11和隔离件12受限。因此，本实施例将d3的值限定为大于或等于0.2mm，以为隔离件等结构提供空间。
在一些实施例中，d3为0.2mm、0.25mm、0.3mm、0.35mm或0.4mm。
在一些实施例中，电极引出结构30具有连接部33，在第一方向X上，连接部33位于极耳114背离活性物质层113的一侧，连接部33与极耳114相抵并焊接。电极组件10还包括隔离件12，隔离件12与极片11层叠并卷绕。在第一方向X上，连接部33的与第一极耳114a相抵的表面与隔离件12的最小距离为S1，连接部33的厚度为t，S1≥0.75t。
t的值越大，焊接连接部33与第一极耳114a产生的热量也就越大；S1越小，隔离件12与连接部33之间的导热路径越短，传导至隔离件12的热量越多，隔离件12被烧伤的风险过高。本实施例将S1限定为大于或等于0.75t，以减少传导至隔离件12的热量，降低隔离件12被烧伤的风险。
在一些实施例中，S1≥1.5t。
在一些实施例中，极耳114沿卷绕方向V卷绕为多圈，多圈极耳114的背离活性物质层113的一端揉平并形成端面114c，电极引出结构30焊接于端面114c。
本申请实施例可对极耳114进行揉平处理，以使极耳114的远离活性物质层113的端部区域收拢、集合在一起；揉平处理在极耳114远离活性物质层113的一端形成致密的端面114c，减小缝隙，便于极耳114与电极引出结构30连接。
在一些实施例中，电极组件10大体为圆柱状。
图12为本申请又一些实施例提供的极片的剖视示意图；图13为本申请一些实施例提供的电池单体的局部结构示意图。
如图12和图13所示，在一些实施例中，在第一方向X上，第一极耳114a的背离活性物质层113的一端超出第二极耳114b，第二极耳114b朝向第一极耳114a弯折并连接于第一极耳114a。电极引出结构30具有连接部33，在第一方向X上，连接部33位于第一极耳114a背离活性物质层113的一侧，连接部33与第一极耳114a相抵并焊接。连接部33的厚度为t，第一极耳114a在展平状态下沿第一方向X超出第一焊接部115的尺寸为h2，t和h2满足：5≤h2/t≤20。
h2越大，第一极耳114a的能够与连接部33焊接的部分越大，但第一极耳114a占用的空间也越大；t的值越小，焊接产生的热量越少，第一极耳114a与连接部33的连接强度越低，连接部33的过流能力越小。如果h2/t过大，将会造成第一极耳114a占用的空间大，电池单体7的能量密度不足，连接部33和第一极耳114a之间出现连接 失效的风险较高。
h2越小，第一极耳114a的能够与连接部33焊接的部分越小，但第一极耳114a占用的空间也越小；t的值越大，焊接产生的热量越多，传递到第一极耳114a和隔离件12上的热量越多，极耳114和隔离件12被烧伤的风险越高。如果h2/t过小，第一极耳114a和隔离件12被烧伤的风险较高。
在本实施例中，第二极耳114b不与连接部33焊接，因此，将h2/t的值限定在5-20，以保证连接部33和第一极耳114a之间的连接强度，降低第一极耳114a被熔穿的风险，提高能量密度。可选地，h2/t的值为10-15。
与第一极耳114a和第二极耳114b同时焊接到连接部33的方案相比，仅第一极耳114a与连接部33焊接的方案需要使第一极耳114a具有更大h2。
图14为本申请再一些实施例提供的极片在展开状态下的结构示意图；图15为本申请一些实施例提供的电池单体7的局部示意图。
如图14和图15所示，在一些实施例中，极耳114包括多个沿第二方向Y间隔设置的极耳部114d，第二方向Y垂直于第一方向X和极片11的厚度方向Z。在第一方向X上，极耳部114d凸出于第二部分112b。
示例性地，第一极耳114a包括多个极耳部114d，第二极耳114b包括多个极耳部114d。
本实施例将极耳114分割为多个分离的极耳部114d，便于极耳部114d在极片11卷绕后弯折。
在一些实施例中，极片11沿卷绕方向V卷绕为多圈。极耳114包括多个沿卷绕方向V间隔设置的极耳部114d，多个极耳部114d朝向极片11的卷绕中心弯折以形成端面114c，电极引出结构30焊接于端面114c。
在极片11的展平状态下，多个极耳部114d沿第二方向Y布置。当极片11卷绕后，多个极耳部114d沿卷绕方向V布置。
极耳部114d朝向极片11的卷绕中心弯折，以遮挡相邻的两圈极片11之间的间隙，并形成致密的端面114c，便于与电极引出结构30焊接，降低漏激光的风险。
根据本申请的一些实施例，本申请还提供了一种电池，包括多个以上任一方案所述的电池单体。
根据本申请的一些实施例，本申请还提供了一种用电装置，包括以上任一方案所述的电池单体，并且电池单体用于为用电装置提供电能。
根据本申请的一些实施例，参照图6至图9，本申请实施例提供了一种极片11，其包括绝缘基体111、导电层112、活性物质层113和极耳114。导电层112为两个，两个导电层112分别设置于绝缘基体111的两个表面。活性物质层113涂覆于导电层112背离绝缘基体111的表面，导电层112包括涂覆有活性物质层113的第一部分112a和未涂覆活性物质层113的第二部分112b，第一部分112a和第二部分112b沿第一方向X布置。
极耳114包括第一极耳114a和第二极耳114b，第一极耳114a和第二极耳114b分别焊接于两个导电层112的第二部分112b。第一极耳114a和第二极耳114b分别用 于将两个导电层112上的电流引出。第一极耳114a与对应的导电层112焊接并形成第一焊接子部，第二极耳114b与对应的导电层112焊接并形成第二焊接子部。第一焊接部115包括第一焊接子部和第二焊接子部。
极片11还包括粘接层116和绝缘层117，粘接层116连接于极耳114并覆盖第一焊接部115的至少部分。绝缘层117的至少部分位于粘接层116背离第一焊接部115的一侧并连接于粘接层116。
导电层112的电阻率为ρ1，导电层112的比热容为C，导电层112的密度为ρ2，常数K＝ρ1/(C·ρ2)。导电层112的厚度为d1，第一部分112a沿第一方向X的尺寸为W，d1、W以及K满足：0.001J/(Ω·mm 4·℃)≤d1/(K·W)≤0.0075J/(Ω·mm 4·℃)。
以下结合实施例进一步说明本申请。
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，以下结合实施例进一步详细描述本申请。但是，应当理解的是，本申请的实施例仅仅是为了解释本申请，并非为了限制本申请，且本申请的实施例并不局限于说明书中给出的实施例。实施例中未注明具体实验条件或操作条件的按常规条件制作，或按材料供应商推荐的条件制作。
实施例1可按照下述步骤制备：
(i)将正极活性物质NCM523、导电剂乙炔黑、粘结剂PVDF按质量比96:2:2进行混合，加入溶剂NMP，在真空搅拌机作用下搅拌至体系呈均一状，获得正极浆料；将正极浆料均匀涂覆在第一集流体上，室温晾干后转移至烘箱继续干燥，然后经过冷压、分切、裁片得到第一极片。正极浆料固化后形成活性物质层。
(ii)将负极活性物质石墨或石墨与其它活性物质按不同质量比得到的混合物、导电剂乙炔黑、增稠剂CMC、粘结剂SBR按质量比96.4:1:1.2:1.4进行混合，加入溶剂去离子水，在真空搅拌机作用下搅拌至体系呈均一状，获得负极浆料；将负极浆料均匀涂覆在第二集流体上，室温晾干后转移至烘箱继续干燥，然后经过冷压、分切、裁片得到第二极片。
(iii)将碳酸乙烯酯(EC)、碳酸甲乙酯(EMC)、碳酸二乙酯(DEC)按照按体积比1:1:1进行混合得到有机溶剂，接着将充分干燥的锂盐LiPF6溶解于混合后的有机溶剂中，配制成浓度为1mol/L的电解液。
(iv)以12μm厚的聚丙烯膜作为隔离件。
(v)将第一极片、隔离件及第二极片层叠在一起并卷绕为圆柱状。
(Ⅵ)将电极组件装入圆柱外壳，然后经过注液、静置、化成、整形等工序，获得电池单体。
在步骤(i)中，参照图8，第一集流体包括绝缘基体111和设置于绝缘胶表面的导电层112，导电层112为铝箔，铝箔的K值为0.0120Ω·mm 4·℃/J，铝箔的厚度为0.001mm，铝箔的涂覆正极浆料的区域的宽度W为68.5mm。
在步骤(Ⅵ)中，电池单体为圆柱状，直径为46mm，高度为95mm。
对实施例1制备出的电池单体进行能量密度检测、温度检测和循环性能检测。
能量密度检测：在25°的环境下，电池单体从上限电压开始，以0.33C的倍率进行放电，到达到下限电压时截止，所发挥的容量即为电池单体的容量；电池单体的容量除以电池单体的重量，得到电池单体的能量密度G。
温度检测：对电池单体进行快充，并检测第一极片的活性物质层的最高温度Q。快充是指在25分钟内将电池单体的电量从0充到80％。在制备电池单体时，可在电池单体内部内置温度传感器，并在外壳上开设开口，以将传感器的引线导出。温度传感器能够实时检测活性物质层的温度。
循环性能检测：在常温环境下，将电池单体以1C倍率充电、以1C倍率放电，进行满充满放循环测试，直至电池单体的容量衰减至初始容量的80％。记录电池单体循环的圈数。
实施例2：实施例2的电池单体的制备方法和检测方法参照实施例1，不同之处在于d1为0.0008mm。
实施例3：实施例3的电池单体的制备方法和检测方法参照实施例1，不同之处在于d1为0.0015mm。
实施例4：实施例4的电池单体的制备方法和检测方法参照实施例1，不同之处在于d1为0.002mm。
实施例5：实施例5的电池单体的制备方法和检测方法参照实施例1，不同之处在于d1为0.0025mm。
实施例6：实施例6的电池单体的制备方法和检测方法参照实施例1，不同之处在于d1为0.003mm。
实施例7：实施例7的电池单体的制备方法和检测方法参照实施例1，不同之处在于d1为0.0035mm。
实施例8：实施例8的电池单体的制备方法和检测方法参照实施例1，不同之处在于d1为0.004mm。
实施例9：实施例9的电池单体的制备方法和检测方法参照实施例1，不同之处在于d1为0.0045mm。
实施例10：实施例10的电池单体的制备方法和检测方法参照实施例1，不同之处在于d1为0.005mm。
实施例11：实施例11的电池单体的制备方法和检测方法参照实施例1，不同之处在于d1为0.0062mm。
对比例1：对比例1的电池单体的制备方法和检测方法参照实施例1，不同之处在于d1为0.0007mm。
对比例2：对比例1的电池单体的制备方法和检测方法参照实施例1，不同之处在于d1为0.0065mm。
对比例3：对比例3的电池单体的制备方法和检测方法参照实施例1，不同之处在于d1为0.0074mm。
实施例1-11和对比示例1-3的评估结果示出于表1中。
表1
Figure PCTCN2022091801-appb-000001
参照实施例1-11和对比例1-3，d1/(K·W)的值越小，导电层在充放电过程中产热越多，温度越高，涂覆于导电层的活性物质层老化越快，电池单体容量下降的越快。如果d1/(K·W)越大，那么会造成导电层的重量也大，电池单体的能量密度越低。本申请实施例将d1/(K·W)限定在0.001J/(Ω·mm 4·℃)-0.0075J/(Ω·mm 4·℃)，以平衡电池单体的能量密度和循环性能。
需要说明的是，在不冲突的情况下，本申请中的实施例及实施例中的特征可以相互组合。
最后应说明的是：以上实施例仅用以说明本申请的技术方案，而非对其限制；尽管参照前述实施例对本申请进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分技术特征进行等同替换，但这些修改或者替换，并不使相应技术方案的本质脱离本申请各实施例技术方案的精神和范围。

Claims (25)

  1. 一种极片，包括：
    绝缘基体；
    导电层，设置于所述绝缘基体的表面；
    活性物质层，涂覆于所述导电层背离所述绝缘基体的表面，所述导电层包括涂覆有所述活性物质层的第一部分和未涂覆所述活性物质层的第二部分，所述第一部分和所述第二部分沿第一方向布置；
    所述导电层的电阻率为ρ1，所述导电层的比热容为C，所述导电层的密度为ρ2，常数K＝ρ1/(C·ρ2)；
    所述导电层的厚度为d1，所述第一部分沿所述第一方向的尺寸为W，d1、W以及K满足：0.001J/(Ω·mm 4·℃)≤d1/(K·W)≤0.0075J/(Ω·mm 4·℃)。
  2. 根据权利要求1所述的极片，其中，d1、W以及K满足：0.002J/(Ω·mm 4·℃)≤d1/(K·W)≤0.003J/(Ω·mm 4·℃)。
  3. 根据权利要求1或2所述的极片，其中，d1为0.5μm-5μm。
  4. 根据权利要求1-3任一项所述的极片，还包括极耳，所述极耳焊接于所述第二部分并形成第一焊接部；在所述第一方向上，所述极耳背离所述活性物质层的一端凸出于所述第二部分。
  5. 根据权利要求4所述的极片，其中，所述极耳的厚度为d2，d2大于d1。
  6. 根据权利要求5所述的极片，其中，d2为1μm-100μm。
  7. 根据权利要求4-6任一项所述的极片，还包括粘接层，所述粘接层连接于所述极耳并覆盖所述第一焊接部的至少部分。
  8. 根据权利要求7所述的极片，其中，所述粘接层的一部分在所述第一方向上位于所述活性物质层和所述极耳之间、涂覆于所述第二部分并连接于所述活性物质层。
  9. 根据权利要求7或8所述的极片，还包括绝缘层，所述绝缘层的至少部分位于所述粘接层背离所述第一焊接部的一侧并连接于所述粘接层。
  10. 根据权利要求9所述的极片，其中，所述绝缘层和所述粘接层均包括粘接剂，所述绝缘层中的所述粘接剂与所述绝缘层的重量比为N1，所述粘接层中的所述粘接剂与所述粘接层的重量比为N2，N1小于N2。
  11. 根据权利要求9或10所述的极片，其中，所述绝缘层完全覆盖所述粘接层。
  12. 根据权利要求4-6任一项所述的极片，还包括绝缘层，所述绝缘层连接于所述极耳和所述活性物质层，且所述绝缘层覆盖所述第一焊接部的至少部分。
  13. 根据权利要求12所述的极片，其中，所述绝缘层包括陶瓷颗粒和粘接剂，所述粘结剂与所述绝缘层的重量比大于或等于0.1。
  14. 根据权利要求9-13任一项所述的极片，其中，在所述第一方向上，所述极耳的超出所述导电层的部分未涂覆所述绝缘层。
  15. 根据权利要求4-14任一项所述的极片，其中，所述极耳包括多个沿第二方向间 隔设置的极耳部，所述第二方向垂直于所述第一方向和所述极片的厚度方向；
    在所述第一方向上，所述极耳部凸出于所述第二部分。
  16. 一种电池单体，包括：
    外壳；
    电极组件，容纳于所述外壳内，所述电极组件包括根据权利要求4-14任一项所述的极片；以及
    电极引出结构，设置于所述外壳并连接于所述极耳。
  17. 根据权利要求16所述的电池单体，其中，
    所述导电层设置为两个，两个所述导电层分别设于所述绝缘基体的两侧；
    所述极耳包括第一极耳和第二极耳，所述第一极耳和所述第二极耳分别焊接于两个所述导电层的所述第二部分。
  18. 根据权利要求17所述的电池单体，其中，
    在所述第一方向上，所述第一极耳的背离所述活性物质层的一端超出所述第二极耳，所述第二极耳朝向所述第一极耳弯折并连接于所述第一极耳；
    所述电极引出结构具有连接部，在所述第一方向上，所述连接部位于所述第一极耳背离所述活性物质层的一侧，所述连接部与所述第一极耳相抵并焊接；
    所述连接部的厚度为t，所述第一极耳在展平状态下沿所述第一方向超出所述第一焊接部的尺寸为h2，t和h2满足：5≤h2/t≤20。
  19. 根据权利要求17所述的电池单体，其中，所述电极引出结构具有连接部，在所述第一方向上，所述连接部位于所述第一极耳背离所述活性物质层的一侧，所述连接部与所述第一极耳相抵并焊接、与所述第二极耳相抵并焊接；
    所述连接部的厚度为t，所述第一极耳在展平状态下沿所述第一方向超出所述第一焊接部的尺寸为h2，t和h2满足：2.5≤h2/t≤10；
    所述第二极耳在展平状态下沿所述第一方向超出所述第一焊接部的尺寸为h3，t和h3满足：2.5≤h3/t≤10。
  20. 根据权利要求16-19任一项所述的电池单体，其中，所述极片卷绕为多圈；
    在所述电极组件的径向上，相邻两圈的所述极片之间的间距为d3，0.2mm≤d3≤0.4mm。
  21. 根据权利要求16-20任一项所述的电池单体，其中，所述电极引出结构具有连接部，在所述第一方向上，所述连接部位于所述极耳背离所述活性物质层的一侧，所述连接部与所述极耳相抵并焊接；
    所述电极组件还包括隔离件，所述隔离件与所述极片层叠并卷绕；
    在所述第一方向上，所述连接部的与所述第一极耳相抵的表面与所述隔离件的最小距离为S1，所述连接部的厚度为t，S1≥0.75t。
  22. 根据权利要求16-21任一项所述的电池单体，其中，所述极耳沿卷绕方向卷绕为多圈，多圈所述极耳的背离所述活性物质层的一端揉平并形成端面，所述电极引出结构焊接于所述端面。
  23. 根据权利要求16-21任一项所述的电池单体，其中，所述极片沿卷绕方向卷绕 为多圈；所述极耳包括多个沿所述卷绕方向间隔设置的极耳部，多个所述极耳部朝向所述极片的卷绕中心弯折以形成端面，所述电极引出结构焊接于所述端面。
  24. 一种电池，包括多个根据权利要求16-23中任一项所述的电池单体。
  25. 一种用电装置，包括根据权利要求16-23中任一项所述的电池单体，所述电池单体用于提供电能。
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CN102891323A (zh) * 2011-07-22 2013-01-23 夏普株式会社 集流体和非水系二次电池
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