WO2023000859A1 - 电池单体、电池以及用电装置 - Google Patents

电池单体、电池以及用电装置 Download PDF

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Publication number
WO2023000859A1
WO2023000859A1 PCT/CN2022/097806 CN2022097806W WO2023000859A1 WO 2023000859 A1 WO2023000859 A1 WO 2023000859A1 CN 2022097806 W CN2022097806 W CN 2022097806W WO 2023000859 A1 WO2023000859 A1 WO 2023000859A1
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WIPO (PCT)
Prior art keywords
side plate
battery cell
battery
buffer member
electrode assembly
Prior art date
Application number
PCT/CN2022/097806
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English (en)
French (fr)
Inventor
王育文
吴益扬
叶永煌
Original Assignee
宁德时代新能源科技股份有限公司
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Publication of WO2023000859A1 publication Critical patent/WO2023000859A1/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
    • 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
    • H01M50/14—Primary casings; Jackets or wrappings for protecting against damage caused by external factors
    • 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
    • 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
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present application relates to the field of batteries, in particular to a battery cell, a battery and an electrical device.
  • Battery cells are widely used in electronic equipment, such as mobile phones, laptop computers, battery cars, electric cars, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes and electric tools, etc.
  • the battery cells may include nickel-cadmium battery cells, nickel-hydrogen battery cells, lithium-ion battery cells, secondary alkaline zinc-manganese battery cells, and the like.
  • the present application provides a battery cell, a battery and an electrical device, which can improve the safety performance of the battery cell.
  • the present application provides a battery cell, which includes a case, an electrode assembly and a buffer.
  • the housing includes a first side panel.
  • the electrode assembly is accommodated in the casing, the electrode assembly includes a straight area and a bending area connected to the straight area, and the straight area includes a flat surface facing the first side plate.
  • the buffer is arranged on the side of the first side plate away from the electrode assembly, and the buffer has a connection surface at an end facing the first side plate, and the connection surface is used to be attached to the first side plate.
  • the connecting surface In a first direction perpendicular to the first side plate, the connecting surface at least partially overlaps with the flat surface; in a direction in which the straight zone points to the bending zone, the flat surface exceeds the connecting surface.
  • the buffer member can absorb the expansion of the electrode assembly and reduce the pressure on the electrode assembly.
  • the connecting surface and the bending area are separated by a certain distance. The bending area, thereby reducing the stress superposition at the junction of the bending area and the straight area, reducing the stress concentration at the junction of the bending area and the straight area, reducing the risk of pole piece cracking, and improving safety performance.
  • the flat surface in a direction from the straight zone to the bent zone, exceeds the buffer member.
  • the cushioning member includes: a main body including a connecting surface, and in a direction in which the straight zone points to the bending zone, the flat surface exceeds the main body; and an extension part extends from an edge of the main part, and the extension part The thickness is smaller than that of the main body to form a gap between the extension and the first side plate. In the first direction, the extension at least partially overlaps the bending zone.
  • the connecting surface is bonded to the first side panel.
  • the electrode assembly includes a first pole piece, a second pole piece and a separator, the first pole piece, the second pole piece and the separator are wound around a winding axis.
  • the first pole piece includes an active material layer, the active material layer includes a first part and a second part arranged continuously along a second direction, the thickness of the second part is smaller than that of the first part, and the second direction is parallel to the winding axis.
  • the buffer covers at least part of the first part and at least part of the second part.
  • the cushioning member of the embodiment of the present application can absorb the expansion of the first part and the second part, and adjust the expansion amount between the first part and the second part through its own deformation, reducing the force difference between the first part and the second part, Improve consistency.
  • both ends of the cushioning member protrude beyond the active material layer in the second direction.
  • the edge of the buffer member in the second direction does not overlap with the active material layer in the first direction, so that when the active material layer expands, stress concentration can be reduced and the risk of the active material layer being crushed can be reduced.
  • a positioning structure is provided on the surface of the first side plate, and the positioning structure is used to limit the position of the buffer member.
  • the positioning structure can be used to position the buffer member during assembly, to ensure the relative position of the connection surface of the buffer member and the flat surface, and to prevent the connection surface from overlapping with the bending area due to assembly errors.
  • the positioning structure includes: a positioning mark coated on the surface of the first side plate; or, a positioning glue layer coated on the surface of the first side plate; or, protruding from the surface of the first side plate The positioning protrusion; or, the positioning recess recessed relative to the surface of the first side plate.
  • the buffer member is provided with a through hole, and the centerline of the flat surface passes through the through hole.
  • the expansion amount is greatest at the center of the flat surface.
  • the through hole in the embodiment of the present application can provide more expansion space at the center of the flat surface, thereby reducing the expansion force.
  • an embodiment of the present application provides a battery, which includes a plurality of battery cells arranged along a first direction, wherein at least one battery cell is the battery cell provided in any embodiment of the first aspect.
  • the present application provides an electrical device, which includes the battery in the second aspect, and the battery is used to provide electrical energy.
  • Fig. 1 is a schematic structural diagram of a vehicle provided by some embodiments of the present application.
  • Fig. 2 is a schematic explosion 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 FIG. 2;
  • Fig. 4 is a schematic structural diagram of a battery cell provided by some embodiments of the present application.
  • FIG. 5 is a schematic cross-sectional view of the battery cell shown in FIG. 4;
  • FIG. 6 is an enlarged schematic view of the battery cell shown in FIG. 5 at the circle frame A;
  • FIG. 7 is a schematic structural view of an electrode assembly of a battery cell provided in some embodiments of the present application.
  • FIG. 8 is another schematic cross-sectional view of the battery cell shown in FIG. 4;
  • FIG. 9 is an enlarged schematic view of the battery cell shown in FIG. 8 at the circle frame C;
  • Fig. 10 is a schematic cross-sectional view of a battery cell provided by another embodiment of the present application.
  • FIG. 11 is an enlarged schematic view at circle C in FIG. 10 .
  • connection In the description of this application, it should be noted that, unless otherwise clearly stipulated and limited, the terms “installation”, “connection”, “connection” and “attachment” should be understood in a broad sense, for example, it may be a fixed connection, It can also be detachably connected or integrally connected; it can be directly connected or indirectly connected through an intermediary, and it can be internal communication between two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in this application according to specific situations.
  • “Plurality” in this application refers to two or more (including two).
  • the 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 embodiment of the present application does not limit this.
  • the battery cell can be in the form of a cylinder, a flat body, a cuboid or other shapes, which is not limited in this embodiment of the present application.
  • Battery cells are generally divided into three types according to packaging methods: cylindrical battery cells, square battery cells and pouch battery cells, which are not limited in this embodiment of the present application.
  • the battery mentioned in the embodiments of the present application refers to a single physical module including one or more battery cells to provide higher voltage and capacity.
  • the battery mentioned in this application may include a battery module or a battery pack, and the like.
  • Batteries generally include a case for enclosing one or more battery cells. The box can prevent liquid or other foreign objects from affecting the charging or discharging of the battery cells.
  • the battery cell includes an electrode assembly and an electrolyte, and the electrode assembly includes a positive pole piece, a negative pole piece and a separator.
  • a battery cell works primarily by moving metal ions between the positive and negative pole pieces.
  • 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 positive electrode current collector includes a positive electrode current collector and a positive electrode protrusion protruding from the positive electrode current collector, and the positive electrode current collector part is coated with a positive electrode active material layer, at least part of the positive electrode convex part is not coated with a positive electrode active material layer, and the positive electrode convex part is used as a positive electrode tab.
  • the material of the positive electrode current collector can be aluminum, the positive electrode active material layer includes the positive electrode active material, and the positive electrode active material can be lithium cobaltate, lithium iron phosphate, ternary lithium or lithium manganate.
  • 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 includes a negative electrode current collector and a negative electrode protrusion protruding from the negative electrode current collector. part is coated with a negative electrode active material layer, at least part of the negative electrode convex part is not coated with a negative electrode active material layer, and the negative electrode convex part is used as a negative electrode tab.
  • the material of the negative electrode current collector may be copper, the negative electrode active material layer includes the negative electrode active material, and the negative electrode active material may be carbon or silicon. In order to ensure that a large current is passed without fusing, the number of positive pole tabs is multiple and stacked together, and the number of negative pole tabs is multiple and stacked together.
  • the material of the spacer can be PP (polypropylene, polypropylene) or PE (polyethylene, polyethylene).
  • the electrode assembly will expand during the charging and discharging process, and the expanded electrode assembly will squeeze the casing and receive the reaction force of the casing.
  • the electrode assembly with a wound structure includes a straight area and a bent area connected to the straight area. When the electrode assembly expands, stress concentration is likely to occur at the junction of the bent area and the straight area.
  • the expansion of multiple electrode assemblies accumulates together, and the stress at the junction of the bending area and the straight area is superimposed, which will cause the risk of cracking of the pole pieces in the bending area, especially The innermost pole piece in the bending area; the cracked pole piece will produce burrs, which can easily pierce the separator and cause the risk of short circuit, resulting in safety accidents.
  • the cracked pole piece will cause the negative electrode piece in the corner area to decompose lithium, thereby causing the capacity of the electrode assembly to decay, and the formed lithium dendrites will pierce the separator, resulting in a short circuit of the electrode assembly, thereby causing a safety accident.
  • an embodiment of the present application provides a battery cell, including: a casing including a first side plate; an electrode assembly housed in the casing, the electrode assembly includes a straight region and a bending region connected to the straight region,
  • the flat area includes a flat surface facing the first side plate; and a buffer, which is arranged on the side of the first side plate away from the electrode assembly, and the buffer has a connecting surface at the end facing the first side plate, and the connecting surface is used for attaching to the first side panel.
  • the connecting surface In a first direction perpendicular to the first side plate, the connecting surface at least partially overlaps with the flat surface; in a direction in which the straight zone points to the bending zone, the flat surface exceeds the connecting surface.
  • the battery cells with this structure can reduce the stress on the bending area of the electrode assembly when used in groups, reduce the risk of pole pieces cracking, and improve safety performance.
  • the isolation assembly described in the embodiments of the present application is suitable for batteries and electric devices using batteries.
  • Electric devices can be vehicles, mobile phones, portable devices, notebook computers, ships, spacecraft, electric toys and electric tools, and so on.
  • 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;
  • spacecraft include airplanes, rockets, space shuttles and spacecraft, etc.;
  • electric toys include fixed Type or mobile electric toys, such as game consoles, electric car toys, electric boat 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, electric planers, and more.
  • the embodiments of the present application do not impose special limitations on the above-mentioned electrical devices.
  • the electric device is taken as an example for description.
  • Fig. 1 is a schematic structural diagram of a vehicle provided by some embodiments of the present application.
  • a battery 2 is arranged inside the vehicle 1 , and the battery 2 can be arranged at the bottom, head or tail of the vehicle 1 .
  • the battery 2 can be used for power supply of the vehicle 1 , for example, the battery 2 can be used as an operating power source of 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 supply power to the motor 4 , for example, for the starting, navigation and working power requirements of the vehicle 1 during driving.
  • the battery 2 can not only be used as an operating power source for the vehicle 1 , but can also be used as a driving power source for the vehicle 1 to provide driving power for the vehicle 1 instead of or partially replacing fuel oil or natural gas.
  • Fig. 2 is a schematic explosion diagram of a battery provided by some embodiments of the present application.
  • the battery 2 includes a box body 5 and a battery cell (not shown in FIG. 2 ), and the battery cell is accommodated in the box body 5 .
  • the box body 5 is used to accommodate the battery cells, and the box body 5 may have various structures.
  • the box body 5 may include a first box body part 51 and a second box body part 52, the first box body part 51 and the second box body part 52 cover each other, the first box body part 51 and the second box body part 51
  • the two box parts 52 jointly define an accommodating space 53 for accommodating the battery cells.
  • the second box part 52 can be a hollow structure with one end open, the first box part 51 is a plate-shaped structure, and the first box part 51 covers the opening side of the second box part 52 to form an accommodating space 53
  • the box body 5; the first box body portion 51 and the second box body portion 52 also can be a hollow structure with one side opening, and the opening side of the first box body portion 51 is covered on the opening side of the second box body portion 52 , to form a box body 5 with an accommodation space 53 .
  • the first box body part 51 and the second box body part 52 can be in various shapes, such as a cylinder, a cuboid, and the like.
  • a sealing member may also be provided between the first box body portion 51 and the second box body portion 52, such as sealant, sealing ring, etc. .
  • the first box part 51 covers the top of the second box part 52
  • the first box part 51 can also be called an upper box cover
  • the second box part 52 can also be called a lower box.
  • the battery 2 there are a plurality of battery cells.
  • a plurality of battery cells can be connected in series, in parallel or in parallel.
  • the mixed connection means that a plurality of battery cells are connected in series and in parallel.
  • a plurality of battery cells can be directly connected in series or in parallel or mixed together, and then the whole composed of a plurality of battery cells is accommodated in the box 5; of course, it is also possible to first connect a plurality of battery cells in series or parallel or
  • the battery modules 6 are formed by parallel connection, and multiple battery modules 6 are connected in series or in parallel or in series to form a whole, and are housed in the box body 5 .
  • FIG. 3 is a schematic structural diagram of the battery module shown in FIG. 2 .
  • there are multiple battery cells 7 and the multiple battery cells 7 are connected in series, in parallel, or in parallel to form a battery module 6 .
  • a plurality of battery modules 6 are connected in series, in parallel or in parallel to form a whole, and accommodated in the box.
  • the plurality of battery cells 7 in the battery module 6 are arranged along the first direction X.
  • the plurality of battery cells 7 in the battery module 6 can be electrically connected through a confluence component, so as to realize parallel connection, series connection or mixed connection of the plurality of battery cells 7 in the battery module 6 .
  • FIG. 4 is a schematic structural view of a battery cell provided by some embodiments of the present application
  • Figure 5 is a schematic cross-sectional view of the battery cell shown in Figure 4
  • Figure 6 is a schematic view of the battery cell shown in Figure 5 at the circle frame
  • FIG. 7 is a schematic structural view of an electrode assembly of a battery cell provided in some embodiments of the present application.
  • the battery cell 7 of the embodiment of the present application includes: a casing 20 including a first side plate 211 ; an electrode assembly 10 housed in the casing 20 , and the electrode assembly 10 includes a straight region 14 and a connection In the bending zone 15 of the straight zone 14, the straight zone 14 includes a flat surface 141 facing the first side plate 211; and a buffer member 30, disposed on the side of the first side plate 211 away from the electrode assembly 10, the buffer member 30 has a connection face 311 at one end facing the first side plate 211 for attachment to the first side plate 211 .
  • the connecting surface 311 overlaps at least partially with the flat surface 141 ; in a direction from the straight zone 14 to the bending zone 15 , the flat surface 141 exceeds the connecting surface 311 .
  • At least one battery cell 7 is the battery cell 7 described in the embodiment of the present application.
  • only some of the battery cells 7 may be provided with the buffer member 30 described in the embodiment of the present application, or all the battery cells 7 may be provided with the buffer member 30 described in the embodiment of the present application.
  • Housing 20 may also be used to contain electrolyte, such as electrolytic solution.
  • the housing 20 can be in various structural forms.
  • the housing 20 may include a housing 21 and a cover assembly 22, the housing 21 is a hollow structure with one side open, the cover assembly 22 covers the opening of the housing 21 and forms a sealed connection, so as to form a An accommodating cavity for accommodating the electrode assembly 10 and electrolyte.
  • the housing 21 can be in various shapes, such as cylinder, cuboid and so on.
  • the shape of the case 21 may 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.
  • the cover assembly 22 includes an end cover 221 , and the end cover 221 covers the opening of the housing 21 .
  • the end cap 221 can be of various structures, for example, the end cap 221 is a plate-shaped structure, a hollow structure with one end open, and the like.
  • the housing 21 is a cuboid structure
  • the end cover 221 is a plate-shaped structure
  • the end cover 221 covers the opening at the top of the housing 21 .
  • the cap assembly 22 may further include an electrode terminal 222 installed on the end cap 221 .
  • the housing 20 can also be of other structures.
  • the housing 20 includes a housing 21 and two cover assemblies 22.
  • the housing 21 is a hollow structure with openings on opposite sides, and one cover assembly 22 is correspondingly closed. An opening of the casing 21 is sealed and connected to form an accommodating cavity for accommodating the electrode assembly 10 and the electrolyte.
  • two electrode terminals 222 may be provided on one cover assembly 22 while no electrode terminal 222 is provided on the other cover assembly 22 , or one electrode terminal 222 may be provided on each of the two cover assemblies 22 .
  • the battery cell 7 there may be one electrode assembly 10 housed in the case 20 or a plurality of them. Exemplarily, in FIG. 5 , there are two electrode assemblies 10 .
  • the housing 21 includes a first side plate 211 .
  • the casing 21 is a cuboid structure, and the casing 21 includes two first side plates 211, two second side plates 212 and a bottom plate, the two first side plates 211 are arranged opposite to each other along the first direction X, and the end caps 221 and the bottom plate are disposed opposite to each other along the second direction Y, and the two second side plates 212 are disposed opposite to each other along the third direction Z.
  • the first side plate 211 is generally a flat plate structure.
  • the first direction X, the second direction Y and the third direction Z intersect two by two.
  • the first direction X, the second direction Y and the third direction Z are perpendicular to each other.
  • the area of the first side plate 211 is larger than the area of the second side plate 212 and the area of the bottom plate.
  • the electrode assembly 10 includes a first pole piece 11 , a second pole piece 12 and a separator 13 , and the first pole piece 11 , the second pole piece 12 and the separator 13 are wound around a winding axis.
  • the first pole piece 11, the second pole piece 12 and the spacer 13 are all strip-shaped structures.
  • the first pole piece 11 , the separator 13 and the second pole piece 12 can be stacked in sequence and wound more than two times around the winding axis to form the electrode assembly 10 .
  • the electrode assembly 10 includes a straight region 14 and a bent region 15 .
  • the straight region 14 is the region of the electrode assembly 10 having a straight structure, and in the straight region 14 , the first pole piece 11 and the second pole piece 12 are arranged substantially straight.
  • the bending area 15 is the area where the electrode assembly 10 has a bending structure, and in the bending area 15, the first pole piece 11 and the second pole piece 12 are both bent and distributed. Exemplarily, in the bending area 15, both the first pole piece 11 and the second pole piece 12 are generally arc-shaped. There are two bending regions 15 , and the two straight regions 14 are respectively connected to two ends of the straight region 14 along the third direction Z.
  • the straight region 14 includes two flat surfaces 141 facing each other along the first direction X.
  • the flat surfaces 141 are substantially parallel to the winding axis of the electrode assembly 10 and are the surfaces with the largest area.
  • the flat surface 141 may be a relatively flat surface, and is not required to be a pure plane.
  • the flat surface 141 is substantially parallel to the inner surface of the first side plate 211 .
  • Each bending area 15 includes a bending surface 151 connecting two flat surfaces 141 .
  • the bending surfaces 151 of the two bending regions 15 face each other.
  • the bending surface 151 is at least partially an arc surface.
  • the area of the flat surface 141 is greater than that of the bent surface 151 .
  • the buffer member 30 may be attached to one first side plate 211 , or the buffer member 30 may be attached to both first side plates 211 . Attached refers to being connected by adhesion, sticking, or the like.
  • connection surface 311 does not overlap with the bending area 15 .
  • the flat surface 141 has a first end 141a and a second end 141b oppositely disposed, the first end 141a is connected to the bending surface 151 of one bending area 15 , the second end 141b is connected to the bending surface 151 of the other bending area 15
  • the bent surfaces 151 are connected to each other. "In the direction in which the straight zone 14 points to the bending zone 15, the flat surface 141 exceeds the connection surface 311" means: in the direction in which the straight zone 14 points to the one bending zone 15, the first end 141a exceeds the connecting surface 311 On the surface 311 , in the direction in which the straight zone 14 points to the other bending zone 15 , the second end portion 141b also exceeds the connecting surface 311 .
  • the direction from the straight zone 14 to the bending zone 15 is parallel to the third direction Z; in the third direction Z, the connection surface 311 is located between the first end portion 141 a and the second end portion 141 b.
  • connection surface 311 may or may not exceed the flat surface 141 , which is not limited in this embodiment of the present application.
  • the buffer member 30 can absorb the expansion of the electrode assembly 10 and reduce the pressure on the electrode assembly 10.
  • the connecting surface 311 is at a certain distance from the bending zone 15.
  • the buffer member 30 transmits the pressure to the flat surface 141 through the connecting surface 311, The pressure will not be transmitted to the bending zone 15, thereby reducing the stress superposition at the junction of the bending zone 15 and the straight zone 14, reducing the stress concentration at the junction of the bending zone 15 and the straight zone 14, and reducing the possibility of pole piece cracking risks and improve safety performance.
  • the flat surface 141 exceeds the buffer member 30 in the direction from the straight region 14 to the bending region 15 .
  • the size of the buffer member 30 is smaller than the size of the flat surface 141 .
  • the buffer member 30 as a whole may be a flat plate with uniform thickness.
  • the connecting surface 311 is bonded to the first side panel 211 .
  • the connection surface 311 can be bonded to the first side panel 211 by an adhesive.
  • adhesive agent can be coated on the first side plate 211 first, and then the connection surface 311 of the buffer member 30 is pasted on the first side plate 211 to be adhered to the first side plate 211; The adhesive is coated on the connection surface 311 first, and then the connection surface 311 of the buffer member 30 is attached to the first side panel 211 to be adhered to the first side panel 211 .
  • a positioning structure 40 is provided on the surface of the first side plate 211 , and the positioning structure 40 is used to limit the position of the buffer member 30 .
  • the positioning structure 40 can be used to position the buffer member 30 during assembly, to ensure the relative position of the connection surface 311 of the buffer member 30 and the flat surface 141 , and to prevent the connection surface 311 from overlapping with the bending area 15 due to assembly errors.
  • the positioning structure 40 positions the buffer member 30 in the third direction Z. In some other examples, the positioning structure 40 can position the buffer member 30 in the second direction Y and the third direction Z at the same time.
  • the present application does not limit the specific structure of the positioning structure 40 as long as it can position the buffer member 30 .
  • the positioning structure 40 includes positioning marks coated on the surface of the first side plate 211 .
  • the positioning mark can be a figure of a specific shape, for example, the positioning mark can be a square or two reference lines.
  • the equipment can recognize the positioning marks, and determine the installation position of the buffer member 30 according to the positions of the positioning marks.
  • the positioning structure 40 includes a positioning glue layer coated on the surface of the first side plate 211 .
  • the positioning glue layer can play the role of positioning and bonding at the same time.
  • the positioning structure 40 includes a positioning protrusion protruding from the surface of the first side plate 211 .
  • the device can recognize the position of the positioning protrusion, and determine the installation position of the buffer member 30 according to the position of the positioning protrusion.
  • the positioning structure 40 includes a positioning recess that is recessed relative to the surface of the first side plate 211 .
  • the device can recognize the position of the positioning recess, and determine the installation position of the buffer member 30 according to the position of the positioning recess.
  • the buffer member 30 is provided with a through hole 312 , and the centerline of the flat surface 141 passes through the through hole 312 .
  • the expansion amount at the center of the flat surface 141 is the largest.
  • the through hole 312 of the embodiment of the present application can provide more expansion space at the center of the flat surface 141 , thereby reducing the expansion force.
  • FIG. 8 is another schematic cross-sectional view of the battery cell shown in FIG. 4 ;
  • FIG. 9 is an enlarged schematic view of the battery cell shown in FIG. 8 at the circle C.
  • the electrode assembly 10 includes a first pole piece 11 , a second pole piece 12 and a separator 13 , and the first pole piece 11 , the second pole piece 12 and a separator 13 Winding around the winding axis.
  • the first pole piece 11 includes an active material layer 111
  • the active material layer 111 includes a first part 111a and a second part 111b that are continuously arranged along the second direction Y
  • the thickness of the second part 111b is smaller than the thickness of the first part 111a
  • the second direction Y parallel to the winding axis.
  • the buffer member 30 covers at least part of the first part 111a and at least part of the second part 111b.
  • the first pole piece 11 also includes a first current collector 112 , and the active material layer 111 is coated on the surface of the first current collector 112 .
  • the active material, binder, conductive agent and solvent are first mixed to form an active slurry, and then the active slurry is coated on the first current collector, and the active slurry passes through
  • the active material layer is formed after drying, rolling and other processes. If the active material layer is coated with equal thickness, then due to the fluidity and surface tension of the active slurry, the active material layer will have protrusions on the edge when it is dried; when rolling, the protrusions will be directly pressed by the roll, thereby initiating the activity. Risk of cracking at the edge of the material layer.
  • the thickness of the edge of the active material layer 111 when coating, the thickness of the edge of the active material layer 111 will be reduced to form a thinner second part 111b. In this way, even if the second part 111b produces protrusions when drying, the protrusions will not exceed the second part 111b.
  • the protrusions of the part 111a are not subjected to rolling during rolling, thereby reducing the risk of cracking of the active material layer 111 .
  • the cushioning member 30 of the embodiment of the present application can absorb the expansion of the first part 111a and the second part 111b, and adjust the expansion amount between the first part 111a and the second part 111b through its own deformation, and reduce the expansion of the first part 111a and the second part 111b.
  • the force difference of part 111b improves consistency.
  • both ends of the buffer member 30 protrude beyond the active material layer 111 .
  • the size of the buffer member 30 is larger than the size of the active material layer 111 .
  • the edge of the buffer member 30 in the second direction Y does not overlap with the active material layer 111 in the first direction X. In this way, when the active material layer 111 expands, stress concentration can be reduced and the risk of the active material layer 111 being crushed can be reduced. risk.
  • FIG. 10 is a schematic cross-sectional view of a battery cell provided by another embodiment of the present application;
  • FIG. 11 is an enlarged schematic view of the circle C in FIG. 10 .
  • the buffer member 30 includes: a main body 31 including a connecting surface 311 , and in the direction where the straight zone 14 points to the bending zone 15 , the flat surface 141 exceeds the main body. 31 ; and an extension 32 extending from the edge of the main body 31 , the thickness of the extension 32 is smaller than that of the main body 31 to form a gap between the extension 32 and the first side plate 211 .
  • the extension portion 32 at least partially overlaps with the bending region 15 .
  • the extension portion 32 is formed by partially thinning the buffer member 30 . There is a gap between the extension part 32 and the first side plate 211, so even if the extension part 32 overlaps with the bending area 15, the extension part 32 will not press the first side plate 211, thereby reducing the pressure when the electrode assembly 10 expands. The pressure transmitted to the bending zone 15 is small.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Connection Of Batteries Or Terminals (AREA)
  • Battery Mounting, Suspending (AREA)

Abstract

本申请公开了一种电池单体、电池以及用电装置。本申请实施例的电池单体包括外壳、电极组件和缓冲件。外壳包括第一侧板。电极组件容纳于外壳内。电极组件包括平直区和连接于平直区的弯折区，平直区包括面向第一侧板的扁平面。缓冲件设置于第一侧板的远离电极组件的一侧，缓冲件在面向第一侧板的一端具有连接面，连接面用于附接到第一侧板。在垂直于第一侧板的第一方向上，连接面与扁平面至少部分重叠；在平直区指向弯折区的方向上，扁平面超出连接面。本申请实施例能够在减小电极组件的弯折区的受力，降低电极组件的极片开裂的风险，提高安全性能。

Description

电池单体、电池以及用电装置
相关申请的交叉引用
本申请要求享有于2021年07月21日提交的名称为“电池单体、电池以及用电装置”的中国专利申请202121661758.1的优先权，该申请的全部内容通过引用并入本文中。
技术领域
本申请涉及电池领域，特别是涉及一种电池单体、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，安全问题也是一个不可忽视的问题，特别是当多个电池单体成组使用时。如何增强安全性，是电池技术中一个亟待解决的技术问题。
发明内容
本申请提供一种电池单体、电池以及用电装置，其能提高电池单体的安全性能。
第一方面，本申请提供一种电池单体，其包括外壳、电极组件和缓冲件。外壳包括第一侧板。电极组件容纳于外壳内，电极组件包括平直区和连接于平直区的弯折区，平直区包括面向第一侧板的扁平面。缓冲件设置于第一侧板的远离电极组件的一侧，缓冲件在面向第一侧板的一端具有 连接面，连接面用于附接到第一侧板。在垂直于第一侧板的第一方向上，连接面与扁平面至少部分重叠；在平直区指向弯折区的方向上，扁平面超出连接面。
上述方案中，当多个电池单体成组使用时，缓冲件可以吸收电极组件的膨胀量，减小电极组件受到的压力。在平直区指向弯折区的方向上，连接面与弯折区间隔一定距离，当缓冲件受压时，缓冲件通过连接面将压力传递到扁平面上，而不会将压力传递到弯折区，从而减少弯折区和平直区的交界处的应力叠加，减小弯折区和平直区的交界处应力集中，降低极片开裂的风险，提高安全性能。
在一些实施例中，在平直区指向弯折区的方向上，扁平面超出缓冲件。
在一些实施例中，缓冲件包括：主体部，包括连接面，且在平直区指向弯折区的方向上，扁平面超出主体部；以及延伸部，从主体部的边缘延伸，延伸部的厚度小于主体部的厚度，以在延伸部和第一侧板之间形成间隙。在第一方向上，延伸部与弯折区至少部分地重叠。
在一些实施例中，连接面粘接于第一侧板。
在一些实施例中，电极组件包括第一极片、第二极片和隔离件，第一极片、第二极片和隔离件绕卷绕轴线卷绕。第一极片包括活性物质层，活性物质层包括沿第二方向连续设置的第一部分和第二部分，第二部分的厚度小于第一部分的厚度，第二方向平行于卷绕轴线。在第一方向上，缓冲件至少覆盖第一部分的至少部分和第二部分的至少部分。
由于第一部分和第二部分厚度不同，因此在充放电时的膨胀量也不同。本申请实施例的缓冲件可以吸收第一部分和第二部分的膨胀，并通过自身的变形来调节第一部分和第二部分之间的膨胀量，减小第一部分和第二部分的受力差异，提高一致性。
在一些实施例中，在第二方向上，缓冲件的两端均超出活性物质层。缓冲件在第二方向上的边缘不与活性物质层在第一方向上重叠，这样，在活性物质层膨胀时，可以减小应力集中，降低活性物质层被压伤的风险。
在一些实施例中，第一侧板的表面设置有定位结构，定位结构用于 限定缓冲件的位置。
定位结构可用于在装配时对缓冲件进行定位，保证缓冲件的连接面与扁平面的相对位置，避免连接面因装配误差而与弯折区重叠。
在一些实施例中，定位结构包括：涂覆于第一侧板的表面的定位标记；或者，涂覆于第一侧板的表面的定位胶层；或者，凸出于第一侧板的表面的定位凸起；或者，相对于第一侧板的表面凹陷的定位凹部。
在一些实施例中，缓冲件设置有通孔，且扁平面的中心线经过通孔。
在电极组件膨胀时，扁平面的中心处的膨胀量最大。本申请实施例的通孔能够为扁平面的中心处提供更多的膨胀空间，从而减小膨胀力。
第二方面，本申请实施例提供了一种电池，其包括多个沿第一方向布置的电池单体，其中，至少一个电池单体为第一方面任一实施例提供的电池单体。
第三方面，本申请提供一种用电装置，其包括如第二方面的电池，电池用于提供电能。
附图说明
下面将参考附图来描述本申请示例性实施例的特征、优点和技术效果。
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结构示意图；
图5为图4所示的电池单体的一剖视示意图；
图6为图5所示的电池单体在圆框A处的放大示意图；
图7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8为图4所示的电池单体的另一剖视示意图；
图9为图8所示电池单体在圆框C处的放大示意图；
图10为本申请另一些实施例提供的电池单体的剖视示意图；
图11为图10在圆框C处的放大示意图。
在附图中，附图未必按照实际的比例绘制。
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，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。电池单体一般按封装的方式分成三种：柱形电池单体、方形电池单体和软包电池单体，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。例如，本申请中所提到的电池可以包括电池模块或电池包等。电池一般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质，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；正极集流体包括正极集流部和凸出于正极集流部的正极凸部，正极集流部涂覆有正极活性物质层，正极凸部的至少部分未涂覆正极活性物质层，正极凸部作为正极极耳。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；负极集流体包括负极集流部和凸出于负极集流部的负极凸部，负极集流部涂覆有负极活性物质层，负极凸部的至少部分未涂覆负极活性物质层，负极凸部作为负极极耳。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。为了保证通过大电流而不发生熔断，正极极耳的数量为多个且层叠在一起，负极极耳的数量为多个且层叠 在一起。隔离件的材质可以为PP(polypropylene，聚丙烯)或PE(polyethylene，聚乙烯)等。
电极组件在充放电过程中会发生膨胀，膨胀后的电极组件会挤压壳体并受到壳体的反作用力。卷绕式结构的电极组件包括平直区和连接于平直区的弯折区，在电极组件膨胀时，弯折区和平直区的交界处容易产生应力集中。当多个电池单体成组使用时，多个电极组件的膨胀累积在一起，弯折区和平直区的交界处的应力叠加在一起，会引发弯折区的极片开裂的风险，特别是弯折区最内侧的极片；开裂后的极片会产生毛刺，毛刺容易刺穿隔离件并引发短路风险，造成安全事故。对于锂离子电池，开裂后的极片会造成拐角区的负极极片析锂，从而造成电极组件容量衰减，形成的锂枝晶会刺穿隔离件，导致电极组件短路，从而引发安全事故。
鉴于此，本申请实施例提供了一种电池单体，包括：外壳，包括第一侧板；电极组件，容纳于外壳内，电极组件包括平直区和连接于平直区的弯折区，平直区包括面向第一侧板的扁平面；以及缓冲件，设置于第一侧板的远离电极组件的一侧，缓冲件在面向第一侧板的一端具有连接面，连接面用于附接到第一侧板。在垂直于第一侧板的第一方向上，连接面与扁平面至少部分重叠；在平直区指向弯折区的方向上，扁平面超出连接面。
具有这种结构的电池单体能够在成组使用时减小电极组件弯折区的受力，降低极片开裂的风险，提高安全性能。
本申请实施例描述的隔离组件适用于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51和第二箱体部52，第一箱体部51与第二箱体部52相互盖合，第一箱体部51和第二箱体部52共同限定出用于容纳电池单体的容纳空间53。第二箱体部52可以是一端开口的空心结构，第一箱体部51为板状结构，第一箱体部51盖合于第二箱体部52的开口侧，以形成具有容纳空间53的箱体5；第一箱体部51和第二箱体部52也均可以是一侧开口的空心结构，第一箱体部51的开口侧盖合于第二箱体部52的开口侧，以形成具有容纳空间53的箱体5。当然，第一箱体部51和第二箱体部52可以是多种形状，比如，圆柱体、长方体等。
为提高第一箱体部51与第二箱体部52连接后的密封性，第一箱体部51与第二箱体部52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51盖合于第二箱体部52的顶部，第一箱体部51亦可称之为上箱盖，第二箱体部52亦可称之为下箱体。
在电池2中，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。
在一些实施例中，电池模块6中的多个电池单体7沿第一方向X布置。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。
图4为本申请一些实施例提供的电池单体的结构示意图；图5为图4所示的电池单体的一剖视示意图；图6为图5所示的电池单体在圆框A处的放大示意图；图7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7所示，本申请实施例的电池单体7包括：外壳20，包括第一侧板211；电极组件10，容纳于外壳20内，电极组件10包括平直区14和连接于平直区14的弯折区15，平直区14包括面向第一侧板211的扁平面141；以及缓冲件30，设置于第一侧板211的远离电极组件10的一侧，缓冲件30在面向第一侧板211的一端具有连接面311，连接面311用于附接到第一侧板211。在垂直于第一侧板211的第一方向X上，连接面311与扁平面141至少部分重叠；在平直区14指向弯折区15的方向上，扁平面141超出连接面311。
在电池中，至少一个电池单体7为本申请实施例描述的电池单体7。换言之，在电池中，可以仅部分的电池单体7设有本申请实施例描述的缓冲件30，也可以是全部的电池单体7均设有本申请实施例描述的缓冲件30。
外壳20还可用于容纳电解质，例如电解液。外壳20可以是多种结构形式。
在一些实施例中，外壳20可以包括壳体21和盖组件22，壳体21为一侧开口的空心结构，盖组件22盖合于壳体21的开口处并形成密封连接，以形成用于容纳电极组件10和电解质的容纳腔。
壳体21可以是多种形状，比如，圆柱体、长方体等。壳体21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，则可选用为圆柱体壳体；若电极组件10为长方体结构，则可选用长方体壳体。
盖组件22包括端盖221，端盖221盖合于壳体21的开口处。端盖221可以是多种结构，比如，端盖221为板状结构、一端开口的空心结构等。示例性的，在图4中，壳体21为长方体结构，端盖221为板状结构，端盖221盖合于壳体21顶部的开口处。
盖组件22还可以包括电极端子222，电极端子222安装于端盖221上。电极端子222为两个，两个电极端子222分别定义为正极电极端子和负极电极端子，正极电极端子和负极电极端子均用于与电极组件10电连接，以输出电极组件10所产生的电能。
在另一些实施例中，外壳20也可以是其他结构，比如，外壳20包括壳体21和两个盖组件22，壳体21为相对的两侧开口的空心结构，一个盖组件22对应盖合于壳体21的一个开口处并形成密封连接，以形成用于容纳电极组件10和电解质的容纳腔。在这种结构中，可以一个盖组件22上设有两个电极端子222，而另一个盖组件22上未设置电极端子222，也可以两个盖组件22各设置一个电极端子222。
在电池单体7中，容纳于外壳20内的电极组件10可以是一个，也可以是多个。示例性的，在图5中，电极组件10为两个。
在一些实施例中，壳体21包括第一侧板211。示例性地，壳体21为长方体结构，壳体21包括两个第一侧板211、两个第二侧板212和底板，两个第一侧板211沿第一方向X相对设置，端盖221和底板沿第二方向Y相对设置，两个第二侧板212沿第三方向Z相对设置。第一侧板211大体为平板结构。第一方向X、第二方向Y和第三方向Z两两相交。可选地，第一方向X、第二方向Y和第三方向Z两两垂直。示例性地，第一侧板211的面积大于第二侧板212的面积和底板的面积。
电极组件10包括第一极片11、第二极片12和隔离件13，第一极片11、第二极片12和隔离件13绕卷绕轴线卷绕。第一极片11、第二极片12和隔离件13均为带状结构。本申请实施例可以将第一极片11、隔离件13 以及第二极片12依次层叠并绕卷绕轴线卷绕两圈以上形成电极组件10。
从电极组件10的外形看，电极组件10包括平直区14和弯折区15。平直区14即电极组件10的具有平直结构的区域，在平直区14，第一极片11和第二极片12基本平直布置。弯折区15即为电极组件10具有弯折结构的区域，在弯折区15，第一极片11和第二极片12均弯折分布。示例性地，在弯折区15，第一极片11和第二极片12均大体为圆弧形。弯折区15为两个，两个平直区14分别连接于平直区14沿第三方向Z的两端。
平直区14包括两个沿第一方向X相互面对的扁平面141，扁平面141大致平行于电极组件10的卷绕轴线且为面积最大的表面。扁平面141可以是相对平整的表面，并不要求是纯平面。扁平面141大体平行于第一侧板211的内表面。
各弯折区15包括弯折面151，弯折面151连接两个扁平面141。两个弯折区15的弯折面151相互面对。弯折面151至少部分为圆弧面。扁平面141的面积大于弯折面151的面积。
在本申请实施例中，可以是一个第一侧板211上附接有缓冲件30，也可以是两个第一侧板211上均附接有缓冲件30。附接指的是通过粘附、贴附等方式连接。
在第一方向X上，连接面311不与弯折区15重叠。
扁平面141具有相对设置的第一端部141a和第二端部141b，第一端部141a与一个弯折区15的弯折面151相连，第二端部141b与另一个弯折区15的弯折面151相连。“在平直区14指向弯折区15的方向上，扁平面141超出连接面311”指的是：在平直区14指向该一个弯折区15的方向上，第一端部141a超出连接面311，在平直区14指向该另一个弯折区15的方向上，第二端部141b也超出连接面311。
示例性地，平直区14指向弯折区15的方向平行于第三方向Z；在第三方向Z上，连接面311位于第一端部141a和第二端部141b之间。
在平行于卷绕轴线的第二方向Y上，连接面311可以超出扁平面141，也可以不超出扁平面141，本申请实施例不作限定。
在本申请实施例中，当多个电池单体7成组使用时，缓冲件30可以 吸收电极组件10的膨胀量，减小电极组件10受到的压力。在平直区14指向弯折区15的方向上，连接面311与弯折区15间隔一定距离，当缓冲件30受压时，缓冲件30通过连接面311将压力传递到扁平面141上，而不会将压力传递到弯折区15，从而减少弯折区15和平直区14的交界处的应力叠加，减小弯折区15和平直区14的交界处应力集中，降低极片开裂的风险，提高安全性能。
在一些实施例中，在平直区14指向弯折区15的方向上，扁平面141超出缓冲件30。
在第三方向Z上，缓冲件30的尺寸小于扁平面141的尺寸。缓冲件30整体可为厚度均匀的平板。
在一些实施例中，连接面311粘接于第一侧板211。连接面311可通过粘接剂粘接于第一侧板211。
在装配时，可以先在第一侧板211上涂覆粘接剂，然后将缓冲件30的连接面311贴合到第一侧板211上以粘附到第一侧板211上；也可以先在连接面311上涂覆粘接剂，然后再将缓冲件30的连接面311贴合到第一侧板211上以粘附到第一侧板211上。
在一些实施例中，第一侧板211的表面设置有定位结构40，定位结构40用于限定缓冲件30的位置。定位结构40可用于在装配时对缓冲件30进行定位，保证缓冲件30的连接面311与扁平面141的相对位置，避免连接面311因装配误差而与弯折区15重叠。
定位结构40在第三方向Z上对缓冲件30进行定位。在另一些示例中，定位结构40能够同时在第二方向Y和第三方向Z上对缓冲件30进行定位。
本申请对定位结构40的具体结构不作限定，只要其能够对缓冲件30进行定位即可。
在一些示例中，定位结构40包括涂覆于第一侧板211的表面的定位标记。定位标记可为特定形状的图形，例如，定位标记可为方框或两条基准线。在装配时，设备能够识别定位标记，并根据定位标记的位置来确定缓冲件30的安装位置。
在另一些示例中，定位结构40包括涂覆于第一侧板211的表面的定位胶层。定位胶层可以同时起到定位和粘接的作用。
在又一些示例中，定位结构40包括凸出于第一侧板211的表面的定位凸起。在装配时，设备能够识别定位凸起的位置，并根据定位凸起的位置来确定缓冲件30的安装位置。
在再一些示例中，定位结构40包括相对于第一侧板211的表面凹陷的定位凹部。在装配时，设备能够识别定位凹部的位置，并根据定位凹部的位置来确定缓冲件30的安装位置。
在一些实施例中，缓冲件30设置有通孔312，且扁平面141的中心线经过通孔312。
在电极组件10膨胀时，扁平面141的中心处的膨胀量最大。本申请实施例的通孔312能够为扁平面141的中心处提供更多的膨胀空间，从而减小膨胀力。
图8为图4所示的电池单体的另一剖视示意图；图9为图8所示电池单体在圆框C处的放大示意图。
如图8和图9所示，在一些实施例中，电极组件10包括第一极片11、第二极片12和隔离件13，第一极片11、第二极片12和隔离件13绕卷绕轴线卷绕。第一极片11包括活性物质层111，活性物质层111包括沿第二方向Y连续设置的第一部分111a和第二部分111b，第二部分111b的厚度小于第一部分111a的厚度，第二方向Y平行于卷绕轴线。在第一方向X上，缓冲件30至少覆盖第一部分111a的至少部分和第二部分111b的至少部分。
第一极片11还包括第一集流体112，活性物质层111涂覆于第一集流体112的表面。
在制造第一极片的过程中，先将活性材料、粘接剂、导电剂和溶剂等混合制成活性浆料，然后再将活性浆料涂覆在第一集流体上，活性浆料通过干燥、辊压等工序后形成活性物质层。如果活性物质层等厚度涂布，那么由于活性浆料的流动性和表面张力，活性物质层在干燥时会在边缘产生凸起；在辊压时，凸起会直接受到辊压，从而引发活性物质层的边缘产 生裂纹的风险。
本申请实施例在涂布时，会减少活性物质层111的边缘的厚度以形成较薄的第二部分111b，这样，即使第二部分111b在干燥时产生凸起，凸起也不会超出第一部分111a，在辊压时凸起不会受到辊压，从而降低活性物质层111开裂的风险。
由于第一部分111a和第二部分111b厚度不同，因此在充放电时的膨胀量也不同。本申请实施例的缓冲件30可以吸收第一部分111a和第二部分111b的膨胀，并通过自身的变形来调节第一部分111a和第二部分111b之间的膨胀量，减小第一部分111a和第二部分111b的受力差异，提高一致性。
在一些实施例中，在第二方向Y上，缓冲件30的两端均超出活性物质层111。
在第二方向Y上，缓冲件30的尺寸大于活性物质层111的尺寸。缓冲件30在第二方向Y上的边缘不与活性物质层111在第一方向X上重叠，这样，在活性物质层111膨胀时，可以减小应力集中，降低活性物质层111被压伤的风险。
图10为本申请另一些实施例提供的电池单体的剖视示意图；图11为图10在圆框C处的放大示意图。
如图10和图11所示，在一些实施例中，缓冲件30包括：主体部31，包括连接面311，且在平直区14指向弯折区15的方向上，扁平面141超出主体部31；以及延伸部32，从主体部31的边缘延伸，延伸部32的厚度小于主体部31的厚度，以在延伸部32和第一侧板211之间形成间隙。其中，在第一方向X上，延伸部32与弯折区15至少部分地重叠。
本申请实施例通过将缓冲件30的局部减薄以形成延伸部32。延伸部32与第一侧板211之间设有间隙，因此，即使延伸部32与弯折区15重叠，延伸部32也不会挤压第一侧板211，从而在电极组件10膨胀时减小传递到弯折区15的压力。
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 (11)

  1. 一种电池单体，包括：
    外壳，包括第一侧板；
    电极组件，容纳于所述外壳内，所述电极组件包括平直区和连接于所述平直区的弯折区，所述平直区包括面向所述第一侧板的扁平面；以及
    缓冲件，设置于所述第一侧板的远离所述电极组件的一侧，所述缓冲件在面向所述第一侧板的一端具有连接面，所述连接面用于附接到所述第一侧板，
    其中，在垂直于所述第一侧板的第一方向上，所述连接面与所述扁平面至少部分重叠；在所述平直区指向所述弯折区的方向上，所述扁平面超出所述连接面。
  2. 根据权利要求1所述的电池单体，其中，在所述平直区指向所述弯折区的方向上，所述扁平面超出所述缓冲件。
  3. 根据权利要求1所述的电池单体，其中，所述缓冲件包括：
    主体部，包括所述连接面，且在所述平直区指向所述弯折区的方向上，所述扁平面超出所述主体部；以及
    延伸部，从所述主体部的边缘延伸，所述延伸部的厚度小于所述主体部的厚度，以在所述延伸部和所述第一侧板之间形成间隙；
    在所述第一方向上，所述延伸部与所述弯折区至少部分地重叠。
  4. 根据权利要求1-3任一项所述的电池单体，其中，所述连接面粘接于所述第一侧板。
  5. 根据权利要求1-4任一项所述的电池单体，其中，所述电极组件包括第一极片、第二极片和隔离件，所述第一极片、所述第二极片和所述隔离件绕卷绕轴线卷绕；
    所述第一极片包括活性物质层，所述活性物质层包括沿第二方向连续设置的第一部分和第二部分，所述第二部分的厚度小于所述第一部分的厚度，所述第二方向平行于所述卷绕轴线；
    在所述第一方向上，所述缓冲件至少覆盖所述第一部分的至少部分和所述第二部分的至少部分。
  6. 根据权利要求5所述的电池单体，其中，在所述第二方向上，所述缓冲件的两端均超出所述活性物质层。
  7. 根据权利要求1-6任一项所述的电池单体，其中，所述第一侧板的表面设置有定位结构，所述定位结构用于限定所述缓冲件的位置。
  8. 根据权利要求7所述的电池单体，其中，所述定位结构包括：
    涂覆于所述第一侧板的表面的定位标记；或者
    涂覆于所述第一侧板的表面的定位胶层；或者
    凸出于所述第一侧板的表面的定位凸起；或者
    相对于所述第一侧板的表面凹陷的定位凹部。
  9. 根据权利要求1-8任一项所述的电池单体，其中，所述缓冲件设置有通孔，且所述扁平面的中心线经过所述通孔。
  10. 一种电池，包括多个沿第一方向布置的电池单体，其中，至少一个电池单体为权利要求1-9中任一项所述的电池单体。
  11. 一种用电装置，包括如权利要求10所述的电池，所述电池用于提供电能。
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