WO2022213306A1 - 电池单体、电池、用电设备及制备电池单体的方法和装置 - Google Patents

电池单体、电池、用电设备及制备电池单体的方法和装置 Download PDF

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Publication number
WO2022213306A1
WO2022213306A1 PCT/CN2021/085851 CN2021085851W WO2022213306A1 WO 2022213306 A1 WO2022213306 A1 WO 2022213306A1 CN 2021085851 W CN2021085851 W CN 2021085851W WO 2022213306 A1 WO2022213306 A1 WO 2022213306A1
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WIPO (PCT)
Prior art keywords
pole piece
electrode assembly
battery cell
projection
battery
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PCT/CN2021/085851
Other languages
English (en)
French (fr)
Inventor
许虎
刘晓梅
金海族
梁成都
Original Assignee
江苏时代新能源科技有限公司
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Application filed by 江苏时代新能源科技有限公司 filed Critical 江苏时代新能源科技有限公司
Priority to PCT/CN2021/085851 priority Critical patent/WO2022213306A1/zh
Priority to EP21827368.8A priority patent/EP4099461B1/en
Priority to US17/566,065 priority patent/US20220328883A1/en
Publication of WO2022213306A1 publication Critical patent/WO2022213306A1/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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
    • 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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/04—Construction or manufacture in general
    • H01M10/0468—Compression means for stacks of electrodes and separators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • 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
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/471—Spacing elements inside cells other than separators, membranes or diaphragms; Manufacturing processes thereof
    • 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
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/471—Spacing elements inside cells other than separators, membranes or diaphragms; Manufacturing processes thereof
    • H01M50/474—Spacing elements inside cells other than separators, membranes or diaphragms; Manufacturing processes thereof characterised by their position inside the cells
    • 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
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/471—Spacing elements inside cells other than separators, membranes or diaphragms; Manufacturing processes thereof
    • H01M50/477—Spacing elements inside cells other than separators, membranes or diaphragms; Manufacturing processes thereof characterised by their shape
    • 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
    • H01M10/0404—Machines for assembling batteries
    • H01M10/0409—Machines for assembling batteries for cells with wound electrodes
    • 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
    • H01M10/049—Processes for forming or storing electrodes in the battery container
    • 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
    • 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 battery technology, and in particular, to a battery cell, a battery, an electrical device, and a method and device for preparing a battery cell.
  • Batteries are widely used in the field of new energy, such as electric vehicles, new energy vehicles, etc. New energy vehicles and electric vehicles have become a new trend in the development of the automotive industry.
  • the cycle life of the battery is a factor that cannot be ignored, and the degradation of the battery performance will affect the cycle life of the battery.
  • the present application aims to provide a battery cell, a battery, an electrical device, and a method and apparatus for preparing the battery cell, so as to alleviate the problem that the performance degradation of the battery cell affects the cycle life of the battery cell.
  • an embodiment of the present application provides a battery cell, which includes:
  • the shell has a cylindrical accommodating cavity
  • the electrode assembly is arranged in the accommodating cavity, and the projection of the electrode assembly along the height direction of the battery cell is a polygon.
  • the projection of the electrode assembly along the height direction of the battery cell is a polygon, and the accommodating cavity of the casing is a cylindrical shape, even if the electrode assembly expands after charging and discharging, the electrode assembly and the casing There is still a remaining space between the inner walls of the body, so as to prevent the outer peripheral surface of the electrode assembly from being squeezed by the casing.
  • Deterioration of pole piece performance such as difficult infiltration and pole piece fracture, leads to the problem of battery cell performance degradation, which in turn alleviates the problem that battery cell performance degradation affects the battery cell's cycle life.
  • the projection of the electrode assembly is a pentagon, a hexagon, an octagon, a decagon or a hexagon.
  • the projection of the electrode assembly is a pentagon, hexagon, octagon, decagon or hexagon, which can ensure the electrode assembly and the casing.
  • the energy density of the battery cell is improved, so as to improve the cycle life and energy density of the battery cell.
  • any section of the electrode assembly perpendicular to the height direction of the battery cell has a polygonal shape.
  • any height position of the electrode assembly has a spare space, and any height position of the electrode assembly can release the stress, further preventing the excessive extrusion of the pole piece and causing local stress concentration and alleviating the battery performance. Reduce the problems that affect the cycle life of the battery.
  • the three-dimensional shape of the electrode assembly is a prism.
  • any cross section of the prism perpendicular to its own height direction ie, perpendicular to the height direction of the battery cell
  • the electrode assembly with a three-dimensional shape of a prism is more convenient to manufacture.
  • the three-dimensional shape of the electrode assembly is a regular prism.
  • the projection of the electrode assembly in the shape of a regular prism is a regular polygon.
  • the area of the regular polygon accounts for more of the area of the circumscribed circle. Therefore, when the projection is a regular polygon, the The energy density is relatively greater.
  • the stressed part of the electrode assembly is at the side edge of the regular prism, that is, at the apex of the projection of the electrode assembly, and the stressed part is evenly distributed on the outer circumference of the electrode assembly, so that the The force of the electrode assembly is more uniform, and the local stress concentration caused by the excessive extrusion of the electrode assembly is relieved, thereby further preventing the battery performance from deteriorating and affecting the cycle life of the battery cell.
  • the vertex position of the polygon is mainly abutted to the inner wall of the casing.
  • the vertex forms a rounded structure to increase the force-bearing area and reduce the local stress at the vertex position. , to further prevent excessive stress at the apex caused by excessive extrusion, thereby preventing battery performance degradation and affecting the cycle life of battery cells.
  • the ratio of the projected circumscribed circle diameter of the electrode assembly to the diameter of the accommodating cavity is 90% to 100%.
  • the ratio of the diameter of the circumscribed circle to the diameter of the accommodating cavity is the group margin of the battery cell.
  • the group margin is configured to be 90% to 100%, the battery cell has a larger energy density and the electrode assembly can be easily packaged under the condition of providing a remaining space for the expansion of the electrode assembly.
  • the ratio of the diameter of the circumscribed circle of the projection of the electrode assembly to the diameter of the accommodating cavity is 95% to 100%.
  • the above technical solution further improves the energy density on the premise of ensuring that there is a remaining space for releasing the stress of the electrode assembly.
  • the electrode assembly includes a first pole piece and a second pole piece with opposite polarity to the first pole piece, and the first pole piece and the second pole piece roll winding to form the electrode assembly;
  • a line connecting any vertex of the projection of the electrode assembly and the center of the circumscribed circle of the projection of the electrode assembly is defined as a first straight line, and the winding end edge of the first pole piece is along the
  • the projection of the height direction of the battery cell is not on any first straight line, and the projection of the winding end edge of the second pole piece along the height direction of the battery cell is not on any first straight line.
  • the diameter of the circumscribed circle will not be increased when the first pole piece or the second pole piece is closed. , so that the energy density can be improved without increasing the group margin, and the distances from each vertex to the inner wall of the shell can be roughly equal, so as to avoid excessive extrusion of individual vertices and cause excessive local stress and battery performance degradation, thereby improving the performance of the battery. battery cycle life.
  • the electrode assembly includes a first pole piece and a second pole piece with opposite polarity to the first pole piece, and the first pole piece and the second pole piece roll winding to form the electrode assembly;
  • a line connecting any vertex of the projection of the electrode assembly and the center of the circumscribed circle of the projection of the electrode assembly is defined as a first straight line, and the winding starting end edge of the first pole piece is along the
  • the projection of the height direction of the battery cell is not on any of the first straight lines, and the projection of the edge of the winding start end of the second pole piece along the height direction of the battery cell is not on any of the first straight lines.
  • the end face of the winding start end When the winding start end is on the first straight line, the end face of the winding start end will abut against the surface of the pole piece in the adjacent area, which causes the end face of the winding start end to be easily rubbed and cause the coating layer (That is, the active material layer) falls off powder, which will affect the cycle life of the battery, and may also lead to lithium precipitation.
  • the coating layer That is, the active material layer
  • the end face of the winding starting end of the pole piece and the pole piece in the adjacent area can be effectively relieved. The surfaces rub against each other and cause the coating layer to fall off, thereby avoiding affecting the cycle life of the battery.
  • the electrode assembly includes a first pole piece and a second pole piece with opposite polarity to the first pole piece, and the first pole piece and the second pole piece roll winding to form the electrode assembly;
  • a line defining any vertex of the projection of the electrode assembly and the center of the circumscribed circle of the projection of the electrode assembly is a first straight line, and the projection of the electrode assembly is composed of a plurality of the first
  • the straight line is divided into multiple regions, and the difference between the number of pole piece layers in any two regions is less than or equal to 1.
  • the difference between the number of pole piece layers in any two regions is less than or equal to 1, and the difference between the number of winding layers in each region is small or the number of winding layers is the same, which can improve the internal space utilization of the accommodating cavity and improve the The effect of battery cycle life and the effect of increasing energy density.
  • the projection of the edge of the winding start end of the first pole piece along the height direction of the battery cell and the edge of the winding end end of the first pole piece along the battery cell The projection of the height direction of the cell is located in two adjacent areas, the projection of the edge of the winding start end of the second pole piece along the height direction of the battery cell and the winding end of the second pole piece
  • the projection of the edge along the height direction of the battery cell is located in two adjacent regions.
  • the number of turns that can be wound around the first pole piece and the second pole piece is an integer.
  • the number of pole piece layers in the two regions is equal, thereby improving the utilization rate of the inner space of the accommodating cavity. It can also avoid that the gap between the outer peripheral surface of the region and the inner wall of the casing is relatively small due to the excessive number of winding layers in a certain area, so as to avoid excessive extrusion of individual vertices during expansion and cause excessive local stress, thereby avoiding affecting the cycle of the battery. life.
  • the battery cell further includes:
  • a confinement layer for wrapping the electrode assembly, the confinement layer has elasticity to allow the electrode assembly to expand.
  • the binding layer not only wraps the electrode assembly tightly, so that the electrode assembly can maintain its projected shape, but also prevents the coiled pole piece from being too loose, which increases the internal resistance and affects the performance of the battery.
  • the confinement layer is a sleeve, and the confinement layer is sleeved on the outside of the electrode assembly.
  • the sleeve-type restraint layer has good integrity, good restraint effect and easy assembly.
  • the three-dimensional shape formed by the confinement layer sleeved on the outside of the electrode assembly is the same as the three-dimensional shape of the electrode assembly.
  • the three-dimensional shape of the confinement layer is the same as the three-dimensional shape of the electrode assembly, that is, the projection of the whole formed by the electrode assembly and the confinement layer along the height direction of the battery cell is a polygon.
  • the electrode assembly can further relieve stress.
  • an embodiment of the present application provides a battery, which includes the aforementioned battery cell.
  • the battery cell is not prone to the problem of deterioration of the pole piece performance due to the expansion of the internal electrode assembly, and the battery has good durability and long service life.
  • embodiments of the present application provide an electrical device including the aforementioned battery.
  • the battery used in the battery has good durability and long service life, so that the electrical equipment works stably.
  • an embodiment of the present application provides a method for preparing a battery cell, which includes:
  • the projection of the electrode assembly along the height direction of the battery cell is a polygon
  • the electrode assembly is arranged in the accommodating cavity.
  • an embodiment of the present application provides a device for preparing a battery cell, which includes:
  • a first providing device for providing a housing, the housing having a cylindrical accommodating cavity
  • a second providing means for providing an electrode assembly the projection of the electrode assembly along the height direction of the battery cell is a polygon
  • An assembly device is used for arranging the electrode assembly in the accommodating cavity.
  • FIG. 1 is a schematic diagram of a vehicle provided by an embodiment of the present application.
  • FIG. 2 is a schematic diagram of a battery provided by an embodiment of the present application.
  • FIG. 3 is an exploded view of a battery module provided by an embodiment of the present application.
  • FIG. 4 is a schematic diagram of a battery cell provided by an embodiment of the present application.
  • FIG. 5 is a schematic assembly diagram of a battery cell according to an embodiment of the present application.
  • FIG. 6 is a schematic diagram of a projection of an electrode assembly provided by an embodiment of the present application as a regular pentagon;
  • FIG. 7 is a schematic diagram of an expansion process of an electrode assembly provided by an embodiment of the present application.
  • FIG. 8 is a schematic diagram of a three-dimensional shape of any electrode assembly with the same cross-sectional shape but different sizes according to an embodiment of the present application;
  • FIG. 9 is a schematic diagram of a three-dimensional shape of an electrode assembly whose three-dimensional shape is a prism according to an embodiment of the present application.
  • FIG. 10 is a schematic diagram of a projection of an electrode assembly provided by an embodiment of the present application as a non-regular hexagon
  • FIG. 11 is a schematic diagram of a projection of an electrode assembly provided by an embodiment of the present application as a regular hexagon;
  • FIG. 12 is a schematic diagram of a projection of an electrode assembly provided by an embodiment of the present application as a regular octagon;
  • FIG. 13 is a schematic diagram of a projection of an electrode assembly provided by an embodiment of the present application as a regular decagon;
  • 15 is a schematic diagram of a winding of the first pole piece and the second pole piece provided by an embodiment of the application;
  • 16 is another schematic diagram of winding the first pole piece and the second pole piece provided by an embodiment of the application.
  • 17 is another schematic diagram of winding of the first pole piece and the second pole piece provided by an embodiment of the application.
  • FIG. 19 is a schematic diagram illustrating that the edge of the winding start end of the pole piece and the edge of the winding end end of the pole piece are not on the first straight line provided by an embodiment of the application;
  • 20 is a comparison diagram of a smooth transition and a non-smooth transition between two adjacent sides of a projection of an electrode assembly according to an embodiment of the present application;
  • 21 is an electrode assembly formed by co-winding a first pole piece, a second pole piece, a first diaphragm, and a second diaphragm provided by an embodiment of the application;
  • FIG. 22 is a schematic overall projection diagram of a tethering layer sleeved on the outside of the electrode assembly according to an embodiment of the present application;
  • FIG. 23 is a schematic overall projection diagram of another binding layer provided outside the electrode assembly provided by an embodiment of the present application.
  • FIG. 24 is an exploded view of a battery cell provided by an embodiment of the present application.
  • FIG. 25 is a schematic flowchart of a method for preparing a battery cell according to an embodiment of the present application.
  • FIG. 26 is a schematic block diagram of an apparatus for preparing a battery cell according to an embodiment of the present application.
  • the terms “installed”, “connected”, “connected” and “attached” should be understood in a broad sense, for example, it may be a fixed connection, It can also be a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be internal communication between two components.
  • installed should be understood in a broad sense, for example, it may be a fixed connection, It can also be a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be internal communication between two components.
  • multiple refers to two or more (including two), and similarly, “multiple groups” refers to two or more groups (including two groups), and “multiple sheets” refers to two or more sheets (includes two pieces).
  • the battery cells may include lithium-ion secondary batteries, lithium-ion primary batteries, lithium-sulfur batteries, sodium-lithium-ion batteries, sodium-ion batteries or magnesium-ion batteries, etc., and may also be solid-state batteries or semi-solid-state batteries.
  • the application examples are not limited to this.
  • 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 batteries mentioned in this application may include battery modules or battery packs, and the like.
  • Batteries typically include a case for enclosing one or more battery cells. The box can prevent liquids or other foreign objects from affecting the charging or discharging of the battery cells.
  • a battery cell includes an electrode assembly and an electrolyte.
  • the electrode assembly When the electrolyte is a solid electrolyte, the electrode assembly consists of a positive pole piece and a negative pole piece; when the electrolyte is a liquid electrolyte (ie electrolyte), the electrode assembly consists of a positive pole piece, a negative pole piece and a separator.
  • the battery cell mainly relies on the movement of metal ions between the positive pole piece and the negative pole piece to work.
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer, the positive electrode active material layer is coated on the surface of the positive electrode current collector, and the current collector without the positive electrode active material layer protrudes from the current collector coated with the positive electrode active material layer, The current collector not coated with the positive electrode active material layer was used as the positive electrode tab.
  • the material of the positive electrode current collector can be aluminum, and the positive electrode active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganate.
  • the negative pole piece includes a negative electrode current collector and a negative electrode active material layer, the negative electrode active material layer is coated on the surface of the negative electrode current collector, and the current collector without the negative electrode active material layer is protruded from the current collector that has been coated with the negative electrode active material layer, The current collector not coated with the negative electrode active material layer was used as the negative electrode tab.
  • the material of the negative electrode current collector can be copper, and the negative electrode active material can be carbon or silicon. In order to ensure that a large current is passed without fusing, the number of positive tabs is multiple and stacked together, and the number of negative tabs is multiple and stacked together.
  • the material of the diaphragm can be PP or PE, etc.
  • the electrode assembly may be a wound structure or a laminated structure, and the embodiment of the present application is not limited thereto.
  • the development of battery technology needs to consider many design factors at the same time, such as energy density, cycle life, discharge capacity, charge-discharge rate and other performance parameters. In addition, the safety of the battery also needs to be considered.
  • the main safety hazard comes from the charging and discharging process, as well as appropriate ambient temperature design.
  • the protection measures include at least switch elements, selection of appropriate isolation diaphragm materials and pressure relief mechanisms.
  • the switching element refers to an element that can stop the charging or discharging of the battery when the temperature or resistance in the battery cell reaches a certain threshold.
  • the separator is used to separate the positive pole piece and the negative pole piece. When the temperature rises to a certain value, it can automatically dissolve the micro-scale (or even nano-scale) micropores attached to it, so that the metal ions cannot pass through the separator. Terminates the internal reaction of the battery cell.
  • the pressure relief mechanism refers to an element or component that is actuated to relieve the internal pressure or temperature when the internal pressure or temperature of the battery cell reaches a predetermined threshold.
  • the threshold design varies according to different design requirements.
  • the threshold value may depend on the materials of one or more of the positive electrode sheet, the negative electrode sheet, the electrolyte and the separator in the battery cell.
  • the performance of the battery cell sometimes deteriorates or drops sharply.
  • the inventor found that the main reason for the deterioration of the performance of the battery cell is that the electrolyte counteracts the pole piece after the battery cell has been used for a period of time.
  • the infiltration effect of the electrode becomes worse, and the worse the infiltration effect of the electrolyte on the pole piece, the greater the degradation of the battery performance, which seriously affects the battery cycle life.
  • the inventors have tried to improve the electrolyte wetting agent, improve the pole piece winding process and other means, but still have not solved the problem.
  • the inventor has further studied and found that the main reason for the deterioration of the wetting effect of the pole piece is that the electrode assembly is locked against the inner wall of the casing of the battery cell.
  • the locking mentioned in this embodiment means that the outer peripheral surface of the electrode assembly all abuts against the inner wall of the casing, so that the electrode assembly cannot release the stress.
  • the electrode assembly may expand slowly during use, after the outer peripheral surface of the electrode assembly all abuts against the inner wall of the casing, if it expands further, the pole piece will be squeezed, and the porosity will decrease when the pole piece is over-extruded. Therefore, the amount of electrolyte absorbed by the pole piece is reduced, the infiltration effect of the electrolyte on the pole piece becomes poor, and once the pole piece is over-extruded, permanent damage will occur, and the extruded electrolyte cannot be re-extruded even if the compressive stress disappears. All of them are absorbed, resulting in the deterioration or sudden drop in the performance of the battery cells, so that the cycle life of the battery cells is reduced.
  • the excessive extrusion of the pole piece will also cause the material particles of the pole piece to rupture. At this time, the surface of the material particle will be re-filmed, which will be accompanied by side reactions, resulting in accelerated attenuation. Therefore, whether the battery using electrolyte or solid electrolyte is used When the pole piece is excessively squeezed, it is prone to performance degradation, which affects the cycle life of the battery cell.
  • the embodiments of the present application provide a technical solution, in which a cylindrical accommodating cavity is arranged in the casing of the battery cell, and the accommodating cavity is used for accommodating the electrode assembly, and the electrode assembly is configured to extend along the
  • the projection of the height direction of the battery cell is a polygon.
  • the remaining space allows the electrode assembly to release the stress to prevent the pole piece from being over-extruded, avoid microscopic damage caused by the rupture of the pole piece material particles or the reduction of porosity, and avoid the macroscopic damage of the pole piece fracture, so as to solve the problem of the deterioration of the pole piece performance leading to the battery.
  • the problem of the performance degradation of the battery cell is solved, and the problem that the cycle life of the battery cell is reduced due to the performance degradation of the battery cell is solved.
  • a vehicle 1 may be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle Wait.
  • the interior of the vehicle 1 may be provided with a motor 2 , a controller 3 and a battery 4 , and the controller 3 is used to control the battery 4 to supply power to the motor 2 .
  • the battery 4 may be provided at the bottom of the vehicle 1 or at the front or rear of the vehicle.
  • the battery 4 can be used for power supply of the vehicle 1 , for example, the battery 4 can be used as the operating power source of the vehicle 1 , for the circuit system of the vehicle 1 , for example, for the starting, navigation and operation of the vehicle 1.
  • the battery 4 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 to provide driving power for the vehicle 1 instead of or partially instead of fuel or natural gas.
  • the battery 4 may include a plurality of battery cells, wherein the plurality of battery cells may be connected in series or in parallel or in a mixed connection, and a mixed connection refers to a mixture of series and parallel connections.
  • the battery 4 may also be referred to as a battery pack.
  • a plurality of battery cells 45 can be connected in series or in parallel or mixed to form a battery module 41 , and then a plurality of battery modules 41 can be connected in series or in parallel or mixed to form a battery 4 . That is to say, the plurality of battery cells 45 may directly form the battery 4 , or may form the battery module 41 first, and then the battery module 41 may form the battery 4 .
  • the battery 4 may include a plurality of battery cells 45 ; the battery 4 may also include a box body 42 (or a cover body), the box body 42 has a hollow structure inside, and the plurality of battery cells 45 are accommodated in the box body 42 .
  • the case 42 may include two parts, referred to herein as a first part 43 and a second part 44 respectively, which are snapped together.
  • the shapes of the first part 43 and the second part 44 may be determined according to the combined shape of the plurality of battery cells 45 , and each of the first part 43 and the second part 44 may have an opening.
  • both the first part 43 and the second part 44 can be a hollow cuboid and each has only one surface that is an open surface, the opening of the first part 43 and the opening of the second part 44 are disposed opposite to each other, and the first part 43 and the second part 44 are interlocked with each other.
  • a box 42 with a closed chamber is formed.
  • One of the first part 43 and the second part 44 may be a rectangular parallelepiped having an opening, and the other may be a cover plate structure to close the opening of the rectangular parallelepiped.
  • a plurality of battery cells 45 are placed in a box 42 formed after the first part 43 and the second part 44 are buckled together after being combined in parallel or in series or in a mixed connection.
  • the battery 4 may also include other structures.
  • the battery 4 may further include a bussing component for realizing electrical connection between the plurality of battery cells 45 , such as parallel or series or hybrid.
  • the bus member may realize electrical connection between the battery cells 45 by connecting the electrode terminals of the battery cells 45 .
  • the bus parts may be fixed to the electrode terminals of the battery cells 45 by welding.
  • the electrical energy of the plurality of battery cells 45 can be further drawn out through the box body 42 through the conductive mechanism.
  • the conducting means may also belong to the bussing member.
  • FIGS. 4 and 5 illustrate a battery cell 45 according to an embodiment of the present application.
  • the battery cell 45 includes a housing 100 , an end cap assembly 200 and one or more electrode assembly 300.
  • the casing 100 can be a rectangular parallelepiped, a cube or a cylinder, the casing 100 is hollow and has a cylindrical accommodating cavity 110 , and one surface of the casing 100 has an opening so that one or more electrode assemblies 300 can be placed in the accommodating cavity 110 .
  • the end surface of the housing 100 is a flat surface with an opening, that is, the end surface is configured without a wall so that the accommodating cavity 110 communicates with the outside of the housing 100 .
  • the end cap assembly 200 covers the opening and is connected to the housing 100 to seal the accommodating cavity 110 , and the accommodating cavity 110 is filled with electrolyte through the liquid injection hole 220 on the end cap assembly 200 .
  • the battery cell 45 further includes one or more electrode terminals 210 , and the electrode terminals 210 are disposed on the end cap assembly 200 .
  • the electrode terminal 210 is connected with a connecting member, or it can also be called an adapter (not shown in the figure), which is located between the end cap assembly 200 and the electrode assembly 300, and is used for realizing the realization of the electrode assembly 300 and the electrode terminal 210. electrical connection.
  • Each electrode assembly 300 has a first pole piece and a second pole piece, and the polarities of the first pole piece and the second pole piece are opposite.
  • the first pole piece is a positive pole piece
  • the second pole piece is a negative pole piece.
  • the tabs of the first pole pieces of the one or more electrode assemblies 300 are connected to an electrode terminal 210 through an adapter, for example, the positive electrode terminal; the tabs of the second pole pieces of the one or more electrode assemblies 300 are connected to an electrode terminal 210 through another One adapter is connected to the other electrode terminal 210, eg, the negative electrode terminal. That is to say, the positive electrode terminal is connected to the tab of the positive pole piece through one adapter, and the negative electrode terminal is connected to the tab of the negative pole piece through another adapter.
  • One or more electrode assemblies 300 may be provided in the battery cell 45 according to actual use requirements. As shown in FIG. 5 , one electrode assembly 300 is provided in the accommodating cavity 110 of the battery cell 45 .
  • the accommodating cavity 110 is configured in a cylindrical shape
  • FIG. 6 shows a schematic diagram of the projection of the battery cell 45 along the height direction of the battery cell by taking a regular pentagon as an example, wherein the projection of the electrode assembly 300 and the projection of the accommodating cavity 110 can be seen , the projection of the accommodating cavity 110 along the height direction of the battery cell is a circle, and the projection of the electrode assembly 300 along the height direction of the battery cell is a polygon.
  • projections in this embodiment are "projections along the height direction of the battery cell", which are referred to as projections hereinafter.
  • projections hereinafter.
  • the projection of the electrode assembly in the drawings of the present application only shows the outline of the projection with lines to represent the shape of the projection, which does not mean that the electrode assembly must be a hollow structure.
  • FIG. 7 shows the expansion process of the electrode assembly 300 by taking the projection of a regular pentagon as an example, and the dotted line in FIG. 7 is the expanded electrode assembly 300 projection.
  • the apex of the regular pentagon gradually approaches the inner wall of the case 100 . There is still a gap between them, so that the electrode assembly 300 still has room for stress relief.
  • the side of the regular pentagon expands and deforms toward the inner wall of the casing 100, so that the expansion force of the electrode assembly is fully released, preventing the inner wall of the casing 100 from locking the outer circumference of the electrode assembly 300. Continued expansion of the assembly 300 also does not result in excessive extrusion of the pole pieces.
  • the shape of any section of the electrode assembly 300 perpendicular to the height direction of the battery cell is a polygon. That is to say, at any height position of the electrode assembly 300, there is a remaining space between the outer peripheral surface of the electrode assembly 300 and the inner wall of the casing 100, so that the stress at any height position of the electrode assembly 300 can be relieved , so as to further prevent local stress concentration caused by excessive extrusion of the pole piece, and alleviate the problem that the battery performance is reduced and the cycle life of the battery is affected.
  • the cross-section of any part may be different.
  • FIG. 8 shows an electrode assembly 300.
  • any cross-sectional shape of the electrode assembly 300 is a hexagon, but part of the cross-section is relatively large and part of the cross-section is relatively small.
  • any section along the height direction H of the battery cell may also have different shapes, for example, the section of the electrode assembly at some heights is a quadrilateral, and the section at other heights is a pentagon Wait.
  • the shape of any section of the electrode assembly 300 perpendicular to the height direction H of the battery cells is a polygon with the same shape and size, that is, the electrode assembly
  • the three-dimensional shape of 300 is a prism.
  • the projection of the prism is the same as its cross section at any height position, which is a polygon with the same shape and size.
  • the polygon mentioned in this embodiment refers to a plane figure composed of three or more line segments connected end to end in sequence.
  • the number of sides of the polygon in this application is not limited, and it can also be a quadrilateral, hexagonal, or octagonal. , decagon or hexagon etc.
  • the shape of the polygon can be a regular polygon or a non-regular polygon.
  • FIG. 10 shows a battery cell 45 whose projection of the electrode assembly 300 is a non-regular hexagon.
  • the projection of electrode assembly 300 is a regular polygon.
  • FIG. 11 shows a battery cell 45 whose projection of the electrode assembly 300 is a regular hexagon.
  • the centroid of the regular polygon (that is, the center of the circumscribed circle Ci) is arranged on the axis line of the cylindrical accommodating cavity 110 .
  • the inner wall of 100 has a reaction force on the polygon, and the force of the reaction force is at the vertex of the polygon. Since the vertices of the regular polygon are evenly spaced, the stress-bearing parts of the electrode assembly 300 projected as a regular polygon are evenly distributed on the outer circumference, so that the electrode assembly 300 is subjected to relatively uniform force, which can prevent the electrode assembly 300 from being partially stressed due to uneven stress. Excessive extrusion of the pole pieces caused by stress concentration prevents battery performance degradation, thereby improving battery cycle life.
  • the electrode assembly 300 Since the electrode assembly 300 is not prone to local stress concentration, and there is a residual space between the electrode assembly 300 and the inner wall of the casing 100 to release the internal stress, it can not only prevent the pole pieces of the electrode assembly 300 from being over-extruded and generate pores The microscopic damage caused by the reduction of the rate or the rupture of the material particles also makes the pole piece less prone to the macroscopic damage of broken and fractured due to excessive internal stress.
  • the area of the regular polygon is larger than that of the non-regular polygon with the same number of sides, which makes the energy density of the battery cell higher.
  • the projection of the electrode assembly 300 can be configured as a regular polygon with other numbers of sides, such as the regular octagon shown in FIG.
  • the regular decagon or regular hexadecagon shown in FIG. 13 can be configured as a regular polygon with other numbers of sides, such as the regular octagon shown in FIG.
  • the regular decagon or regular hexadecagon shown in FIG. 13 can be configured as a regular polygon with other numbers of sides, such as the regular octagon shown in FIG.
  • the regular decagon or regular hexadecagon shown in FIG. 13 are examples of the projection of the electrode assembly 300 .
  • the diameter of the circumscribed circle Ci is the same, the larger the number of sides of the regular polygon, the larger the area of the regular polygon. Under the condition that there is enough remaining space between the electrode assembly and the inner wall of the casing 100, the sides of the regular polygon are increased. can effectively increase the energy density.
  • the energy density of a battery cell is often characterized by the group margin.
  • the group margin is the diameter of the cylindrical electrode assembly and the diameter of the cylindrical receiving cavity. Ratio.
  • the ratio of the diameter of the circumscribed circle Ci that defines the polygon formed by the projection of the electrode assembly 300 to the diameter of the accommodating cavity 110 is the group margin, and the larger the group margin, the greater the energy density.
  • the group margin of the battery cells 45 is configured to be 90%-100%, that is, the ratio of the diameter of the circumscribed circle Ci of the projection of the electrode assembly 300 to the diameter of the accommodating cavity 110 is 90%-100%, so that Maximize the use of the accommodating volume of the accommodating cavity 110, and at the same time provide a surplus space for the expansion of the pole piece, prevent the electrode assembly 300 from being locked by the inner wall of the housing 100, resulting in excessive internal stress of the electrode assembly 300, and prevent the occurrence of excessive extrusion of the pole piece
  • the problem of the deterioration of the performance of the pole piece such as the drop of the active material, the difficulty of infiltration of the electrolyte, and the breakage of the pole piece, thus prevents the performance of the battery cell from deteriorating and reducing the cycle life.
  • the group margin of the battery cells 45 is configured to be 95%-100%, that is, the ratio of the diameter of the circumscribed circle Ci of the projection of the electrode assembly 300 to the diameter of the accommodating cavity 110 is 95%-100%, In order to improve the energy density on the premise that there is a remaining space for releasing the stress of the electrode assembly 300 .
  • the value of the group margin mentioned here refers to the state when the battery cells 45 are charged and discharged under a constant voltage to form an activated state.
  • the electrode assembly 300 may have expanded. Even if the vertex of the electrode assembly 300 has abutted against the inner wall of the casing 100 and the group margin reaches 100%, there is still a gap between the electrode assembly 300 and the inner wall of the casing 100 . space, the electrode assembly 300 is not easy to be locked, the pole piece is not damaged by excessive extrusion, the electrolyte is not easily squeezed out, the battery cell 45 can maintain a low internal resistance, and is not prone to performance degradation or sudden drop. conditions, resulting in a longer cycle life.
  • the electrode assembly 300 in this embodiment includes the first pole piece 310 and the second pole piece 320 .
  • the electrode assembly 300 may be formed by stacking materials including the first pole piece 310 and the second pole piece 320 , or may be formed by winding the material including the first pole piece 310 and the second pole piece 320 .
  • the electrode assembly 300 is formed by winding the first pole piece 310 and the second pole piece 320 as an example for description.
  • the projected shape of the electrode assembly 300 is set.
  • the electrode assembly 300 is set as a prism, and its projection is a regular hexagon. shape.
  • FIG. 14 shows the area division diagram when projected as a regular hexagon, and the regular hexagon has six hexagons A, B, C, D, E, and F. vertices, and the connection line defining the vertex of the projection of the electrode assembly 300 and the circumscribed circle center O of the projection of the electrode assembly 300 is the first straight line, that is, the regular hexagon includes six first straight lines: AO, BO, CO, DO, EO, FO, the six first straight lines divide the regular hexagon into six regions I, II, III, IV, V, VI, of which region I is triangle AOB, region II is triangle BOC, region III is triangle COD, and region IV is the triangle DOE, the area V is the triangle EOF, and the area VI is the triangle FOA.
  • the first lines and regions described below are based on this.
  • FIG. 15 shows the projection of the first pole piece 310 and the second pole piece 320 .
  • the first pole piece 310 is a positive pole piece
  • the second pole piece 320 is a negative pole piece.
  • the first pole piece 310 originates from one of the six regions and is wound in a clockwise or counterclockwise direction
  • the second pole piece 320 originates from one of the six regions and is wound in a clockwise or counterclockwise direction.
  • the first pole piece 310 and the second pole piece 320 are stacked first and then wound, and the first pole piece 310 and the second pole piece 320 are wound in the same direction.
  • the circle close to the center O of the circumscribed circle is regarded as the inside, and the distance from the center O of the circumscribed circle is regarded as the outside.
  • the first pole piece 310 and the second pole piece 320 both start from the region I and are wound from the inside to the outside in a counterclockwise direction.
  • the winding start end 311 of the first pole piece is in the area I
  • the winding end end 312 of the first pole piece is in the area VI adjacent to the area I
  • the winding start end 321 of the second pole piece is in the area I
  • the winding end 322 of the second pole piece is in the area VI adjacent to the area I.
  • the number of winding turns of the first pole piece 310 is an integer
  • the number of winding turns of the second pole piece 320 is also an integer.
  • the first pole piece 310 passes through the area I, area II, area III, area IV, area V, and area VI the same number of times, and the first pole piece 310 has the same number of superimposed layers in each area, which is two layers
  • the second pole piece 320 is equal to the number of times through area I, area II, area III, area IV, area V, area VI, and the number of layers that the second pole piece 320 superimposes in each area is the same, and is three layers .
  • the number of pole piece layers in each region is equal, which is five layers, and the difference between the number of pole piece layers in any two regions is 0.
  • the winding start end 311 of the first pole piece and the winding end 312 of the first pole piece are in adjacent areas, and the winding start end 321 of the second pole piece and the winding end of the second pole piece The ends 322 are in adjacent areas, but the first pole piece 310 and the second pole piece 320 have different winding turns.
  • the number of winding turns of the second pole piece 320 serving as the negative pole piece is greater than the number of winding turns of the first pole piece 310 of the positive pole piece, so that the innermost and outermost layers of the electrode assembly 300 are both second
  • the pole piece 320 ensures that the inner side and the outer side of the first pole piece 310 always correspond to the second pole piece 320, and lithium ions can be embedded in the second pole piece 320 after being de-inserted from either surface of the first pole piece 310.
  • the pole piece 320 can effectively prevent lithium precipitation due to the insufficient remaining amount of the second pole piece 320 .
  • the number of winding turns of the first pole piece 310 and the second pole piece 320 may also be the same.
  • FIG. 16 shows the projection of the first pole piece 310 and the second pole piece 320, the winding start end 311 of the first pole piece is in the area I, and the winding end end 312 of the first pole piece is in the area I In region VI, the winding start end 321 of the second pole piece is in region I, and the winding end 322 of the second pole piece is in region VI, that is, the winding start end 311 of the first pole piece and the winding of the first pole piece
  • the ending end 312 is in the adjacent area, the winding start end 321 of the second pole piece and the winding ending end 322 of the second pole piece are in the adjacent area, and the first pole piece 310 and the second pole piece 320 are arranged.
  • the number of winding turns is the same, the number of superimposed layers of the first pole piece 310 and the second pole piece 320 in each region is two layers, and the number of pole piece layers in each region is four layers.
  • the innermost circle layer of the electrode assembly 300 is the second pole piece 320, and the outermost circle layer is the first pole piece 310.
  • the outer side of the first pole piece 310 at least does not cover the part of the second pole piece 320.
  • a coating layer is provided, that is, no active material is applied, and the edge of the winding end 322 of the second pole piece exceeds the edge of the winding end 312 of the first pole piece to prevent the second pole piece 320 from being insufficient.
  • Each pole piece has two surfaces, and during winding, one of the two surfaces always faces the direction of the circumscribed circle center O, and the other surface faces the direction of the inner wall of the housing 100, and the side facing the circumscribed circle center O is the inner side surface,
  • the surface facing the inner wall direction of the casing 100 is regarded as the outer surface.
  • FIG. 17 shows the projection of the first pole piece 310 and the second pole piece 320, the winding start end 311 of the first pole piece is in the area II, and the winding end 312 of the first pole piece is in the area II In region VI, the winding start end 321 of the second pole piece is in region I, and the winding end end 322 of the second pole piece is also in region I. It can be seen from FIG. 17 that the number of pole piece layers in each region is equal at this time, All are five floors.
  • the number of layers of pole pieces in a certain region refers to the sum of the number of layers of the first pole pieces 310 in the region and the number of layers of the second pole pieces 320 in the region.
  • the first pole piece 310 reaches or passes through an area, the first pole piece 310 is superimposed one layer in the area, and the number of layers of the first pole piece 310 in this area is increased by one;
  • the second pole piece 320 is superimposed one layer in the area, and the number of layers of the second pole piece 320 in this area is increased by one.
  • the number of superimposed layers of pole pieces in each region is the same, so that the distance between each vertex and the inner wall of the casing 100 is approximately equal, and the electrode assembly 300 is expanded.
  • the reaction forces are similar to avoid that a certain vertex is relatively too close to the inner wall of the housing 100 and the stress is too large, so as to prevent the overpressure or fracture of the pole pieces due to the stress concentration at the vertex.
  • the electrode assembly 300 formed by winding is relatively closer to the set regular polygon, so that the interior of the accommodating cavity 110 can be improved.
  • the space utilization rate is increased, and the energy density of the battery cells 45 is increased.
  • the second pole piece 320 continues to be wound to have enough negative pole piece margin to prevent the ions from being deintercalated from the first pole piece 310 and cannot be embedded in the second pole piece.
  • the sheet 320 is precipitated, and at this time, the difference in the number of pole sheet layers in any two regions may not be zero.
  • the difference in the number of pole piece layers in any two regions may be set to be 1. For example, in FIG. 18, FIG.
  • the 18 shows the projection of the first pole piece 310 and the second pole piece 320, and the winding start end 311 of the first pole piece and the winding start end 321 of the second pole piece are both in the region I,
  • the winding end 312 of the first pole piece is in the region VI adjacent to the region I, and the winding end 322 of the second pole piece continues to wind up to the region I after passing through the region VI.
  • the pole piece of the region I is stopped.
  • the number of layers is one more than the number of pole piece layers in other regions.
  • winding forms are also possible, so that the difference in the number of pole pieces in any two regions is 0 or 1, the region where the winding starting end 311 of the first pole piece is located, the second pole piece
  • the area where the winding start end 321 is located, the area where the winding ending end 312 of the first pole piece is located, and the area where the winding ending end 322 of the second pole piece is located may all be the same, or may be different or partially the same.
  • the edge of the wrapping end 312 of the first pole piece is not on any first straight line, and the edge of the wrapping end 322 of the second pole piece is not on any first straight line.
  • FIG. 19 shows the projection of the first pole piece 310 and the second pole piece 320.
  • the edge of the winding end 312 of the first pole piece and the edge of the winding end 322 of the second pole piece are both at in area VI, but not on the first line AO.
  • the first straight line increases the length of one layer of pole piece thickness
  • the projection of the electrode assembly 300 and its external The diameter of the circle Ci also increases accordingly. Therefore, compared with the edge of the winding tail end 312 of the first pole piece and the edge of the winding tail end 322 of the second pole piece both on the first straight line AO, the edge of the winding tail end 312 of the first pole piece, the edge of the winding tail end 322 of the first pole piece
  • the edge of the winding end 322 of the diode piece is not on the first straight line AO, the number of layers of the pole piece in each area does not change (still nine layers), and the energy density decreases less or even basically the same, but from the vertex A to
  • the distance between the inner walls of the housing 100 is relatively reduced, so that the diameter of the circumscribed circle Ci is relatively reduced, which is equivalent to improving the energy density without increasing the group margin, and further taking into account the purpose of
  • the edge of the winding end 312 of the first pole piece and the edge of the winding end 322 of the second pole piece are not on the first straight line, and there is also a guarantee
  • the distance from each vertex to the inner wall of the housing 100 is approximately equal.
  • the inner wall of the housing 100 receives equal reaction forces at the vertex A, vertex B, vertex C, vertex D, vertex E, and vertex F, so as to avoid damage due to excessive local stress at a vertex.
  • the edge of the winding starting end 311 of the first pole piece is not on any first straight line, and the edge of the winding starting end 321 of the second pole piece is not on any first straight line.
  • the end face of the winding starting end of a pole piece 310 will contact the surface of the innermost second pole piece 320 in the region VI, and the end face of the winding starting end 311 of the first pole piece is easily rubbed, causing the coating layer near the contact part to peel off
  • the edge of the winding starting end of the second pole piece 320 is on the first straight line AO
  • the end face of the winding starting end of the second pole piece 320 will contact the innermost second pole piece 320 in the region VI.
  • the end face of the winding starting end 321 of the second pole piece is easily rubbed, causing the coating layer near the contact part to fall off.
  • the edge of the winding start end 311 of the first pole piece and the edge of the winding start end 321 of the second pole piece not on the first straight line AO, the end face of the winding start end 311 of the first pole piece Neither the end face of the winding starting end 321 of the second pole piece touches the surface of the innermost second pole piece 320 in the region VI, and the coating layer near the end face of the winding starting end will not fall off.
  • the coating layer on the pole piece is generally an active material layer. The powder drop of the coating layer will cause lithium deposition and affect the cycle life of the battery cell 45.
  • the edges of the winding starting end 321 of the sheet are not on the first straight line AO, which can prevent lithium precipitation and effectively improve the cycle life of the battery cells 45 .
  • the edge of the winding start end 311 of the first pole piece, the edge of the winding start end 321 of the second pole piece, the edge of the winding end 312 of the first pole piece, and the winding end of the second pole piece is not on the same diameter of the circumscribed circle Ci, so as to avoid local stress concentration due to overlapping of steps in local positions, and to avoid that the thickness of the overlapping position of the steps is larger than that of other parts, so as to make better use of the internal space and improve the utilization rate of internal space. Increase energy density.
  • the electrode assembly 300 is provided with a roll.
  • the reel mentioned here refers to a polygonal cylinder arranged at the axis of the electrode assembly 300 to facilitate the winding and molding of the electrode assembly 300 , and the number of sides or sides of the polygonal cylinder is the same as the number of sides of the set polygon.
  • the first pole piece 310 and the second pole piece 320 are wound around the reel to form the electrode assembly 300 whose projected shape is the same as the set polygon size.
  • the winding starting end edge of the pole piece has no free margin for slight deformation inward, provided that the winding starting end edge of the pole piece is on the first straight line also increases the length of the first straight line. Therefore, in this case, the edge of the winding start end is not on the first straight line, which also has the effect of not increasing the length of the first straight line, thereby not increasing the diameter of the circumscribed circle Ci, so as not to increase the group margin.
  • it also has the effect of ensuring that the distances from each vertex to the inner wall of the housing 100 are approximately equal, so that the reaction forces received at each vertex are equal, so as to avoid local stress at a certain vertex Too large and lead to overvoltage of the pole piece.
  • FIG. 20 A regular hexagon as an example shows a schematic diagram of the projection of the electrode assembly 300 when it is expanded.
  • the dotted line in FIG. 20 is the projection of the expanded electrode assembly 300.
  • the vertex A is a non-smooth transition
  • the vertex B, the vertex C, and the vertex D , vertex E, vertex F are smooth transitions, and it can be seen from the comparison that when the electrode assembly 300 expands to abut the inner wall of the casing 100, the arc surface formed at the smooth transition position basically all contacts the inner wall of the cylindrical casing 100, In other words, the contact areas at vertex B, vertex C, vertex D, vertex E, and vertex F are all larger than the contact area at vertex A, so the force area at the vertex of the smooth transition increases and the internal force per unit area decreases.
  • changing the winding direction means that the first pole piece 310 or the second pole piece 320 turns to the other side of the polygon along one side of the polygon, and the first pole piece 310 and the second pole piece 320 are formed during each turning. Rounded corners so that each vertex is an arc face.
  • the electrode assembly 300 may not be a complete regular polygon.
  • the vertex angle of the polygon will have a manufacturing tolerance of ⁇ 10%.
  • ⁇ is The angle between the extension lines of two adjacent sides of the polygon, and n is the number of sides of the polygon.
  • an electronic insulating layer is further provided between the first pole piece 310 and the second pole piece 320 , and the electronic insulating layer may be a separator.
  • the lengths of the first diaphragm 330 and the second diaphragm 340 are respectively greater than the lengths of the first pole piece 310 and the second pole piece 320 .
  • the first pole piece 310 is stacked in sequence and then starts to be wound. After the stacking, the edge of the winding starting end 311 of the first pole piece exceeds the edge of the winding starting end 321 of the second pole piece, and the winding starting end edge of the first diaphragm 330 and the first The edges of the winding starting ends of the two separators 340 respectively exceed the edges of the winding starting ends 311 of the first pole piece.
  • the second pole piece 320 After winding, the second pole piece 320 is in the innermost layer, and at least the second diaphragm 340 covers the innermost layer.
  • the inner side of the first pole piece 310 and the outer side of the second pole piece 320 are separated by a first diaphragm 330, and the outer side of the first pole piece 310 and the inner side of the second pole piece 320 are separated by a second diaphragm 340. separated.
  • the first diaphragm 330 and the second diaphragm 340 continue to be wound to cover the winding end 312 of the first pole piece and the winding end of the second pole piece end 322.
  • the separator is wound around the outer circumference of the electrode assembly 300, the better the binding to the electrode assembly 300, preventing the loosening of the pole pieces from increasing the internal resistance, thereby avoiding the increase in the internal resistance and reducing the battery performance, thereby ensuring the battery's performance. cycle life.
  • at least one of the first separator 330 and the second separator 340 is in the roll covering the first pole piece. After wrapping around the ending end 312 and the wrapping end 322 of the second pole piece, continue winding for 0.25 to 5 turns.
  • the first diaphragm 330 and the second diaphragm 340 At least one of the coils continues to be wound for 1.25 to 2 turns after covering the winding end 312 of the first pole piece and the winding end 322 of the second pole piece.
  • FIG. 22 shows a projection view of the electrode assembly 300
  • a confinement layer 400 is provided on the outside of the electrode assembly 300 that has been wound.
  • the binding layer 400 is used to wrap the electrode assembly 300 to prevent the first pole piece 310 and the second pole piece 320 from loosening and deformation due to loosening, so that the electrode assembly 300 maintains its set polygonal shape.
  • the confinement layer 400 has elasticity to allow the electrode assembly 300 to expand, that is, as the electrode assembly 300 expands outward, the confinement layer 400 expands synchronously, preventing the pole piece from loosening and preventing the confinement layer 400 from extruding the pole piece excessively.
  • the thickness of the confinement layer 400 is enlarged for easy observation, which is only for illustration, and does not represent the actual thickness of the confinement layer 400 , nor does it represent the size ratio of the projection of the confinement layer 400 to that of the electrode assembly 300 .
  • the elastic tie layer 400 can be made of materials such as polycondensates of terephthalic acid and ethylene glycol, or made of pressure-sensitive adhesive, and the selection range of the adhesive strength of the pressure-sensitive adhesive is greater than 0.1 N/mm.
  • the confinement layer 400 is a sleeve, and the sleeve is sleeved on the outside of the electrode assembly 300 .
  • a gap is preset between the inner wall of the confinement layer 400 and the inner wall of the casing 100 , and the gap can further provide more remaining space for the electrode assembly 300 to expand. .
  • the electrode assembly 300 After the electrode assembly 300 is expanded, the electrode assembly 300 indirectly contacts the inner wall of the case 100 through the confinement layer 400 .
  • the three-dimensional shape formed by the confinement layer 400 after being sleeved on the outside of the electrode assembly 300 is the same as the three-dimensional shape of the electrode assembly 300 . same shape.
  • the three-dimensional shape of the confinement layer 400 is different from the three-dimensional shape of the electrode assembly 300 when the confinement layer 400 is not sheathed outside the electrode assembly 300 .
  • the three-dimensional shape is the same as that of the electrode assembly 300 .
  • the three-dimensional shape of the confinement layer 400 when not sheathed outside the electrode assembly 300 is the same as the three-dimensional shape of the electrode assembly 300 .
  • FIG. 24 shows an exploded view of a battery cell 45 , wherein the electrode assembly 300 is a regular hexagonal prism, and the confinement layer 400 is a regular hexagonal prism.
  • the confinement layer 400 when the electrode assembly 300 is in other three-dimensional shapes , the confinement layer 400 has the same other three-dimensional shape.
  • the outer shape of the housing 100 is configured as a cylinder, and correspondingly, the projection of the end cap assembly 200 along the height direction H of the battery cell is a circle.
  • the edge of the casing 100 at least at the opening is also the same polygon, and the casing 100 and the end cap assembly 200 need to be aligned during assembly , so that the vertices and sides of the projections of the two overlap; after aligning, the housing 100 and the end cap assembly 200 need to be welded and fixed, and the welding torch needs to be stopped at the vertex of the polygon to switch the welding direction during welding.
  • the cylindrical shell 100 and the end cap assembly 200 projected as a circle do not need to be aligned during assembly, and can be directly closed. During welding, they can be welded along a circular path at one time without pause, which reduces the difficulty of assembly and improves assembly. efficiency, reducing labor costs.
  • the battery cell 45 and the battery 4 according to the embodiment of the present application are described above, and the electric equipment is described by taking the vehicle 1 as an example.
  • the method and apparatus for preparing the battery cell 45 according to the embodiment of the present application will be described below, which is not detailed. Part of the description can be found in the previous embodiments.
  • FIG. 25 shows a schematic flowchart of a method for preparing a battery cell 45 according to an embodiment of the present application, and the method may include:
  • an electrode assembly 300 is provided, and the projection of the electrode assembly 300 along the height direction H of the battery cell is a polygon;
  • the electrode assembly 300 is arranged in the accommodating cavity 110 .
  • FIG. 26 shows a schematic block diagram of an apparatus 500 for preparing a battery cell 45 according to an embodiment of the present application.
  • the preparing apparatus 500 may include: a first providing device 510 , a second providing device 520 and an assembling device 530 .
  • the first providing device 510 is used to provide the housing 100, and the housing 100 has a cylindrical accommodating cavity 110;
  • the second providing device 520 is configured to provide the electrode assembly 300, and the projection of the electrode assembly 300 along the height direction H of the battery cell is a polygon;
  • the assembling device 530 is used for disposing the electrode assembly 300 in the accommodating cavity 110 .

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Abstract

本申请实施例公开一种电池单体、电池、用电设备及制备电池单体的方法和装置，用电装置中装配有电池，电池内具有一个或多个电池单体，其中电池单体包括：壳体，具有圆柱状的容纳腔；电极组件，设置在所述容纳腔内，所述电极组件沿所述电池单体的高度方向的投影为多边形。该电池单体中的电极组件即使在充放电后膨胀，电极组件与壳体的内壁之间仍然存在余留空间，从而避免电极组件的外周面受到壳体的挤压，该余留空间能够容许电极组件发生膨胀，防止极片过度挤压出现活性物质掉落、电解液浸润难、极片断裂等极片性能恶化导致电池单体性能衰减的问题，进而缓解电池单体性能衰减影响电池单体的循环寿命的问题。

Description

电池单体、电池、用电设备及制备电池单体的方法和装置 技术领域
本申请涉及电池技术领域，特别是涉及一种电池单体、电池、用电设备及制备电池单体的方法和装置。
背景技术
电池在新能源领域应用甚广，例如电动汽车、新能源汽车等，新能源汽车、电动汽车已经成为汽车产业的发展新趋势。
在应用中，电池的循环寿命是不可忽视的要素，电池性能衰减会影响电池的循环寿命。
发明内容
本申请旨在提供一种电池单体、电池、用电设备及制备电池单体的方法和装置，以缓解电池单体性能衰减影响电池单体的循环寿命的问题。
本申请的实施例是这样实现的：
第一方面，本申请实施例提供一种电池单体，其包括：
壳体，具有圆柱状的容纳腔；
电极组件，设置在所述容纳腔内，所述电极组件沿所述电池单体的高度方向的投影为多边形。
本申请实施例的技术方案中，由于电极组件沿所述电池单体的高度方向的投影为多边形，而壳体的容纳腔为圆柱状，因此电极组件即使在充放电后膨胀，电极组件与壳体的内壁之间仍然存在余留空间，从而避免电极组件的外周面受到壳体的挤压，该余留空间能够容许电极组件发生膨胀，防止极片过度挤压出现活性物质掉落、电解液浸润难、极片断裂等极片性能恶化导致电池单体性能衰减的问题，进而缓解电池单体性能衰减影响电池单体的循环寿命的问题。
在本申请的一种实施例中，所述电极组件的所述投影为五边形、六边形、八边形、十边形或十六边形。
相比于电极组件的投影为三角形，将所述电极组件的所述投影为五边形、六边 形、八边形、十边形或十六边形，可以实现在保证电极组件和壳体的内壁之间留有足够的余留空间的前提下，提高电池单体的能量密度，从而兼顾提高电池单体循环寿命和能量密度。
在本申请的一种实施例中，所述电极组件的任一与所述电池单体的高度方向垂直的截面的形状均为多边形。
沿电池单体的高度方向上，电极组件的任一高度位置都具有余留空间，电极组件的任一高度位置都能够释放应力，进一步防止极片过度挤压而造成局部应力集中，缓解电池性能降低影响电池的循环寿命的问题。
在本申请的一种实施例中，所述电极组件的三维形状为棱柱。
棱柱在垂直其自身高度方向上(即垂直于电池单体的高度方向)的任一截面都相同，相比部分截面的形状不同的情况而言，三维形状为棱柱的电极组件更便于生产制造。
在本申请的一种实施例中，所述电极组件的三维形状为正棱柱。
正棱柱形状的电极组件的投影为正多边形，与外接圆直径相同的非正多边形相比，正多边形的面积在外接圆面积中的占比更多，因此投影为正多边形时，电池单体的能量密度相对更大。另外，电极组件的三维形状为正棱柱时，电极组件的受力部位在正棱柱的侧棱处，也就是在电极组件的投影的顶点处，受力部位在电极组件的外周上均匀分布，使电极组件的受力更均匀，缓解电极组件过度挤压而造成局部应力集中，从而进一步防止电池性能衰减而影响电池单体的循环寿命。
在本申请的一种实施例中，所述电极组件的所述投影的相邻两条边之间平滑过渡。
当电极组件膨胀时，主要是多边形的顶点位置抵接壳体的内壁，通过使多边形的相邻两条边平滑过渡，顶点形成圆角结构以增大受力面积、减小顶点位置的局部应力，进一步防止顶点处过度挤压而造成应力过大，从而防止电池性能衰减而影响电池单体的循环寿命。
在本申请的一种实施例中，所述电极组件的所述投影的外接圆直径与所述容纳腔的直径的比值为90％～100％。
电极组件的投影所形成的多边形，其外接圆直径与容纳腔的直径的比值为电池单体的群裕度。群裕度越小则间隙越大，电池单体的能量密度越小，但此时电极组件装壳相对容易；反之，群裕度越大则间隙越小，电池单体的能量密度越大，但此时电极组件装壳相对困难。当群裕度配置为90％～100％时，在给电极组件的膨胀提供余留空间的情况下，使电池单体具有较大的能量密度，且还方便电极组件装壳。
在本申请的一种实施例中，所述电极组件的所述投影的外接圆直径与所述容纳腔的直径的比值为95％～100％。
上述技术方案在保证具有用于释放电极组件应力的余留空间的前提下，进一步提高能量密度。
在本申请的一种实施例中，所述电极组件包括第一极片和与所述第一极片极性相反的第二极片，所述第一极片和所述第二极片卷绕形成所述电极组件；
定义所述电极组件的所述投影的任一顶点与所述电极组件的所述投影的外接圆圆心的连线为第一直线，所述第一极片的卷绕收尾端边缘沿所述电池单体的高度方向的投影不在任一第一直线上，所述第二极片的卷绕收尾端边缘沿所述电池单体的高度方向的投影不在任一第一直线上。
通过使第一极片的卷绕收尾端边缘、第二极片的卷绕收尾端边缘均不在第一直线上，使第一极片或第二极片在收尾时不增加外接圆的直径，从而在不增加群裕度的情况下提高能量密度，还能够使各个顶点到壳体的内壁的距离大致相等，以免个别顶点过度挤压而造成局部应力过大而出现电池性能衰减，从而提高电池循环寿命。
在本申请的一种实施例中，所述电极组件包括第一极片和与所述第一极片极性相反的第二极片，所述第一极片和所述第二极片卷绕形成所述电极组件；
定义所述电极组件的所述投影的任一顶点与所述电极组件的所述投影的外接圆圆心的连线为第一直线，所述第一极片的卷绕起始端边缘沿所述电池单体的高度方向的投影不在任一第一直线上，所述第二极片的卷绕起始端边缘沿所述电池单体的高度方向的投影不在任一第一直线上。
当卷绕起始端在第一直线上时，卷绕起始端的端面会抵在相邻区域的极片表面，这导致卷绕起始端的端面容易被摩擦而致使端面附近的涂覆层(即活性物质层)掉粉，掉粉会影响电池的循环寿命，还可能导致出现析锂现象。通过使第一极片的卷绕起始端边缘、第二极片的卷绕起始端边缘均不在第一直线上，能够有效缓解极片的卷绕起始端的端面与相邻区域的极片表面相互摩擦而导致涂覆层掉粉，从而避免影响电池的循环寿命。
在本申请的一种实施例中，所述电极组件包括第一极片和与所述第一极片极性相反的第二极片，所述第一极片和所述第二极片卷绕形成所述电极组件；
定义所述电极组件的所述投影的任一顶点与所述电极组件的所述投影的外接圆圆心的连线为第一直线，所述电极组件的所述投影由多条所述第一直线划分为多个区域，任意两个区域内的极片层数之差小于或等于1。
任意两个区域内的极片层数之差小于或等于1，每个区域内的卷绕层数相差较小或卷绕层数一致，从而能够提高容纳腔的内部空间利用率，兼顾提高电池循环寿命的效果和增大能量密度的效果。
在本申请的一种实施例中，所述第一极片的卷绕起始端边缘沿所述电池单体的高度方向的投影和所述第一极片的卷绕收尾端边缘沿所述电池单体的高度方向的投影 位于相邻两个区域内，所述第二极片的卷绕起始端边缘沿所述电池单体的高度方向的投影和所述第二极片的卷绕收尾端边缘沿所述电池单体的高度方向的投影位于相邻两个区域内。
当第一极片和第二极片的卷绕起始端、卷绕收尾端在相邻的两个区域时，能够实现第一极片和第二极片卷绕的圈数均为整数，任意两个区域内的极片层数相等，从而提高容纳腔的内部空间利用率。还能避免由于某一区域卷绕层数过多导致该区域外周面与壳体的内壁的间隙相对较小，以免膨胀时个别顶点过度挤压而造成局部应力过大，从而避免影响电池的循环寿命。
在本申请的一种实施例中，所述电池单体还包括：
束缚层，用于包裹所述电极组件，所述束缚层具有弹性以容许所述电极组件膨胀。
束缚层既裹紧电极组件的作用，使电极组件能够保持其投影的形状，又防止卷绕的极片过于松散而增大内阻影响电池性能。
在本申请的一种实施例中，所述束缚层为套筒，所述束缚层套设在所述电极组件的外部。
套筒式的束缚层整体性好，束缚效果好，且容易装配。
在本申请的一种实施例中，所述束缚层与所述壳体的内壁之间具有空隙。
束缚层与壳体的内壁之间具有空隙，因此可以进一步为电极组件膨胀提供更多的余留空间。
在本申请的一种实施例中，套设在所述电极组件的外部的所述束缚层所形成的三维形状与所述电极组件的三维形状相同。
束缚层的三维形状与电极组件的三维形状相同，即电极组件与束缚层形成的整体沿电池单体的高度方向的投影为多边形，确保束缚层与壳体的内壁之间存在余留空间，以使电极组件能进一步释放应力。
第二方面，本申请实施例提供一种电池，其包括前述的电池单体。
本实施例提供的电池，其电池单体不容易因内部电极组件膨胀而出现极片性能恶化的问题，该电池具有较好的耐久性，使用寿命长。
第三方面，本申请实施例提供一种用电设备，其包括前述的电池。
本实施例提供的用电设备，其所使用的电池具有较好的耐久性和较长的使用寿命，从而用电设备工作稳定。
第四方面，本申请实施例提供一种电池单体的制备方法，其包括：
提供壳体，所述壳体具有圆柱状的容纳腔；
提供电极组件，所述电极组件沿所述电池单体的高度方向的投影为多边形；
将所述电极组件设置在所述容纳腔内。
第四方面，本申请实施例提供一种电池单体的制备装置，其包括：
第一提供装置，用于提供壳体，所述壳体具有圆柱状的容纳腔；
第二提供装置，用于提供电极组件，所述电极组件沿所述电池单体的高度方向的投影为多边形；
组装装置，用于将所述电极组件设置在所述容纳腔内。
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为本申请一个实施例提供的车辆的示意图；
图2为本申请一个实施例提供的电池的示意图；
图3为本申请一个实施例提供的电池模块的分解图；
图4为本申请一个实施例提供的电池单体的示意图；
图5为本申请一个实施例提供的电池单体的装配示意图；
图6为本申请一个实施例提供的电极组件的投影为正五边形的示意图；
图7为本申请一个实施例提供的电极组件的膨胀过程的示意图；
图8为本申请一个实施例提供的任一截面形状相同但大小不同的电极组件的三维形状示意图；
图9为本申请一个实施例提供的三维形状为棱柱的电极组件的三维形状示意图；
图10为本申请一个实施例提供的电极组件的投影为非正六边形的示意图；
图11为本申请一个实施例提供的电极组件的投影为正六边形的示意图；
图12为本申请一个实施例提供的电极组件的投影为正八边形的示意图；
图13为本申请一个实施例提供的电极组件的投影为正十边形的示意图；
图14为本申请为当电极组件的投影为正六边形时的区域划分对照图；
图15为本申请一个实施例提供的第一极片和第二极片的一种卷绕示意图；
图16为本申请一个实施例提供的第一极片和第二极片的另一种卷绕示意图；
图17为本申请一个实施例提供的第一极片和第二极片的又一种卷绕示意图；
图18为本申请一个实施例提供的第一极片和第二极片的再一种卷绕示意图；
图19为本申请一个实施例提供的极片的卷绕起始端边缘和极片的卷绕收尾端边缘不在第一直线上的示意图；
图20为本申请一个实施例提供的电极组件的投影的相邻两条边之间平滑过渡和非平滑过渡的对比图；
图21为本申请一个实施例提供的第一极片、第二极片、第一隔膜和第二隔膜共同卷绕形成的电极组件；
图22为本申请一个实施例提供的一种束缚层套设于电极组件外部时的整体投影示意图；
图23为本申请一个实施例提供的另一种束缚层套设于电极组件外部时的整体投影示意图；
图24为本申请一个实施例提供的电池单体的分解图；
图25为本申请一个实施例提供的电池单体的制备方法的示意性流程图；
图26为本申请一个实施例提供的电池单体的制备装置的示意性框图。
在附图中，附图并未按照实际的比例绘制。
标记说明：1-车辆；2-马达；3-控制器；4-电池；41-电池模块；42-箱体；43-第一部分；44-第二部分；45-电池单体；100-壳体；110-容纳腔；200-端盖组件；210-电极端子；220-注液孔；300-电极组件；310-第一极片；311-第一极片的卷绕起始端；312-第一极片的卷绕收尾端；320-第二极片；321-第二极片的卷绕起始端；322-第二极片的卷绕收尾端；330-第一隔膜；340-第二隔膜；400-束缚层；500-制备装置；510-第一提供装置；520-第二提供装置；530-组装装置；H-电池单体的高度方向；Ci-外接圆。
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。本领域技术人员显式地和隐式地理解的是，本申请所描述的实施例可以与其它实施例相结合。
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)，同理，“多组”指的是两组以上(包括两组)，“多片”指的是两片以上(包括两片)。
本申请中，电池单体可以包括锂离子二次电池、锂离子一次电池、锂硫电池、钠锂离子电池、钠离子电池或镁离子电池等，还可以是固态电池或半固态电池等，本申请实施例对此并不限定。
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。当电解质为固态电解质时，电极组件由正极极片和负极极片组成；当电解质为液态电解质(即电解液)时，电极组件由正极极片、负极极片和隔离膜组成。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，未涂敷正极活性物质层的集流体凸出于已涂覆正极活性物质层的集流体，未涂敷正极活性物质层的集流体作为正极极耳。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，未涂敷负极活性物质层的集流体凸出于已涂覆负极活性物质层的集流体，未涂敷负极活性物质层的集流体作为负极极耳。负极集流体的材料可以为铜，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。隔膜的材质可以为PP或PE等。此外，电极组件可以是卷绕式结构，也可以是叠片式结构，本申请实施例并不限于此。电池技术的发展要同时考虑多方面的设计因素，例如，能量密度、循环寿命、放电容量、充放电倍率等性能参数，另外，还需要考虑电池的安全性。
对于电池单体来说，主要的安全危险来自于充电和放电过程，同时还有适宜的环境温度设计，为了有效地避免不必要的损失，对电池单体一般会有至少三重保护措施。具体而言，保护措施至少包括开关元件、选择适当的隔离膜材料以及泄压机构。开关元件是指电池单体内的温度或者电阻达到一定阈值时而能够使电池停止充电或者放电的元件。隔离膜用于隔离正极极片和负极极片，可以在温度上升到一定数值时自动溶解掉附着在其上的微米级(甚至纳米级)微孔，从而使金属离子不能在隔离膜上通过，终止电池单体的内部反应。泄压机构是指电池单体的内部压力或温度达到预定阈值时致动以泄放内部压力或温度的元件或部件。该阈值设计根据设计需求不同而不同。所述阈值可能取决于电池单体中的正极极片、负极极片、电解液和隔离膜中一种或几种的材料。
在电池单体使用过程中，有时会出现电池单体的性能衰减或骤降的情况，发明人研究发现导致电池单体性能变差的主要原因是电池单体使用一段时间后电解液对极片的浸润效果变差，而电解液对极片的浸润效果越差，电池性能衰减越大，严重影响电池循环寿命。然而发明人尝试了改善电解液浸润剂、改善极片卷绕工艺等手段仍未解决该问题。发明人进一步研究发现，导致极片的浸润效果变差的主要原因是电极组件抵接电池单体的壳体内壁锁死导致的。本实施例中所说的锁死是指电极组件的外周面全部抵接壳体内壁，导致电极组件无法释放应力。
由于电极组件在使用时过程中可能会缓慢膨胀，当电极组件的外周面全部抵接在壳体内壁后，若进一步膨胀，会导致极片受到挤压，极片被过度挤压时孔隙率降低，因此极片吸收的电解液的量降低，电解液对极片的浸润效果变差，而且一旦极片被过度挤压将产生永久损伤，即使压应力消失也不能重新将被挤出的电解液全部吸收，导致出现电池单体性能衰减或骤降的情况，以致电池单体的循环寿命降低。
另外，极片被过度挤压还会导致极片的材料颗粒破裂，这时材料颗粒表面要重新成膜，此时会伴有副反应，导致衰减加快，因此无论采用电解液还是固态电解质的电池单体，当极片被过度挤压时都容易出现性能衰减的问题，影响电池单体的循环寿命。
鉴于此，为解决电池循环寿命降低的问题，本申请实施例提供一种技术方案，在电池单体的壳体内设置圆柱状的容纳腔，容纳腔用于容纳电极组件，电极组件被配 置成沿电池单体的高度方向的投影为多边形。当电极组件在使用过程中由于充放电而膨胀时，多边形的顶点位置抵紧壳体的内壁，而多边形的边和壳体的内壁之间仍有余留空间，从而避免电极组件的外周面全部贴紧壳体的内壁而锁死。该余留空间容许电极组件释放应力以免极片被过度挤压，避免出现极片材料颗粒破裂或孔隙率减小的微观损伤，及避免极片断裂的宏观损伤，从而解决极片性能恶化导致电池单体性能衰减的问题，进而解决电池单体性能衰减导致电池单体的循环寿命降低的问题。
本申请实施例描述的技术方案均适用于各种使用电池的用电设备，例如，手机、便携式设备、笔记本电脑、电瓶车、电动玩具、电动工具、电动车辆、船舶和航天器等，例如，航天器包括飞机、火箭、航天飞机和宇宙飞船等。
应理解，本申请实施例描述的技术方案不仅仅局限适用于上述所描述的用电设备，还可以适用于所有使用电池的用电设备，但为描述简洁，下述实施例均以电动车辆为例进行说明。
例如，如图1所示，本申请一种实施例的一种车辆1，车辆1可以为燃油汽车、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。车辆1的内部可以设置马达2，控制器3以及电池4，控制器3用来控制电池4为马达2的供电。例如，在车辆1的底部或车头或车尾可以设置电池4。电池4可以用于车辆1的供电，例如，电池4可以作为车辆1的操作电源，用于车辆1的电路系统，例如，用于车辆1的启动、导航和运行时的工作用电需求。在本申请的另一实施例中，电池4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，替代或部分地替代燃油或天然气为车辆1提供驱动动力。
为了满足不同的使用电力需求，电池4可以包括多个电池单体，其中，多个电池单体之间可以串联或并联或混联，混联是指串联和并联的混合。电池4也可以称为电池包。可选地，请结合图2和图3所示，多个电池单体45可以先串联或并联或混联组成电池模块41，多个电池模块41再串联或并联或混联组成电池4。也就是说，多个电池单体45可以直接组成电池4，也可以先组成电池模块41，电池模块41再组成电池4。
电池4可以包括多个电池单体45；电池4还可以包括箱体42(或称罩体)，箱体42内部为中空结构，多个电池单体45容纳于箱体42内。箱体42可以包括两个部分，这里分别称为第一部分43和第二部分44，第一部分43和第二部分44扣合在一起。第一部分43和第二部分44的形状可以根据多个电池单体45组合的形状而定，第一部分43和第二部分44可以均具有一个开口。例如，第一部分43和第二部分44均可以为中空长方体且各自只有一个面为开口面，第一部分43的开口和第二部分44的开口相对设置，并且第一部分43和第二部分44相互扣合形成具有封闭腔室的箱体42。第一部分43和第二部分44中，也可以一者为具有开口的长方体，另一者为盖板结构以封闭长方体的开口。多个电池单体45相互并联或串联或混联组合后置于第一部分43和第二部分44扣合后形成的箱体42内。
可选地，电池4还可以包括其他结构。例如，该电池4还可以包括汇流部件，汇流部件用于实现多个电池单体45之间的电连接，例如并联或串联或混联。具体地，汇流部件可通过连接电池单体45的电极端子实现电池单体45之间的电连接。进一步地，汇流部件可通过焊接方式固定于电池单体45的电极端子。多个电池单体45的电能可进一步通过导电机构穿过箱体42而引出。可选地，导电机构也可属于汇流部件。
下面针对任意一个电池单体45进行详细描述，图4和图5示出了本申请一个实施例的一种电池单体45，电池单体45包括壳体100、端盖组件200和一个或多个电极组件300。
壳体100可以为长方体或正方体或圆柱体，该壳体100中空并具有圆柱状的容纳腔110，壳体100的其中一个面具有开口以便一个或多个电极组件300可以放置于容纳腔110内。例如，壳体100的端面为具有开口的平面，即该端面被配置为不具有壁体而使得容纳腔110与壳体100的外部相通。端盖组件200覆盖该开口并与壳体100连接，以将容纳腔110封闭，并通过端盖组件200上的注液孔220向容纳腔110内填充电解液。
该电池单体45还包括一个或多个电极端子210，电极端子210设置于端盖组件200。电极端子210连接有一个连接构件，或者也可称之为转接件(图中未示出)，其位于端盖组件200和电极组件300之间，用于使电极组件300和电极端子210实现电连接。
每个电极组件300均具有第一极片和第二极片，第一极片和第二极片的极性相反。例如，当第一极片为正极极片时，第二极片为负极极片。一个或多个电极组件300的第一极片的极耳通过一个转接件与一个电极端子210连接，例如，正电极端子；一个或多个电极组件300的第二极片的极耳通过另一个转接件与另一个电极端子210连接，例如，负电极端子。也就是说，正电极端子通过一个转接件与正极极片的极耳连接，负电极端子通过另一个转接件与负极极片的极耳连接。
在电池单体45中，根据实际使用需求，可设置为一个或多个电极组件300，如图5所示，电池单体45的容纳腔110内设置有一个电极组件300。
容纳腔110被配置为圆柱状，图6中以正五边形为例示出了电池单体45的沿电池单体的高度方向的投影示意图，其中可见电极组件300的投影与容纳腔110的投影，容纳腔110沿电池单体的高度方向的投影为圆形，电极组件300沿电池单体的高度方向的投影为多边形。
本实施例中所有投影均为“沿电池单体的高度方向的投影”，以下均简称投影。另外，本申请附图中电极组件的投影仅以线条示出了投影的轮廓，以表征投影的形状，不代表电极组件必须为中空结构。
电极组件300封闭于容纳腔110后，充放电时电极组件300会膨胀，图7以 正五边形的投影为例示出了电极组件300的膨胀过程，图7中虚线为膨胀后的电极组件300的投影。随着电极组件300膨胀，正五边形的顶点逐渐靠近壳体100的内壁，当电极组件300膨胀至顶点抵紧壳体100的内壁后，正五边形的边与壳体100的内壁之间仍然具有间隙，这使得电极组件300仍有释放应力的空间。电极组件继续膨胀时，正五边形的边朝向壳体100的内壁膨胀鼓起变形，使得电极组件的极片膨胀力充分释放，避免壳体100的内壁锁死电极组件300的外周，即使电极组件300继续膨胀也不会导致极片过度挤压。
在一些实施例中，电极组件300的任一与电池单体的高度方向垂直的截面的形状均为多边形。也就是说，在电极组件300的任一高度位置，电极组件300的外周面与壳体100的内壁之间都具有余留空间，使得电极组件300的任一高度位置处的应力都能够得到释放，从而进一步防止极片过度挤压而造成局部应力集中，缓解电池性能降低影响电池的循环寿命的问题。
在一些实施例中，任一部分截面的可以不同。例如，图8示出了一种电极组件300，沿电池单体的高度方向H，电极组件300的任一截面形状都为六边形，但部分截面相对较大、部分截面相对较小。在另一些实施例中，沿电池单体的高度方向H上的任一截面也可以具有不同的形状，例如电极组件在一些高度处的截面为四边形、在另一些高度处的截面为五边形等。
在一些实施例中，为便于生产制造，如图9所示，电极组件300的任一与电池单体的高度方向H垂直的截面的形状均为形状大小相同的多边形，也就是说，电极组件300的三维形状为棱柱。沿电池单体的高度方向H上，棱柱的投影与其任一高度位置处的截面相同，为形状大小相同的多边形。
本实施例中所说的多边形是指由三条或三条以上的线段首尾顺次连接所组成的平面图形，本申请中多边形的边数不受限制，还可以是四边形、六边形、八边形、十边形或十六边形等。
多边形的形状可以是正多边形，也可以是非正多边形。例如，图10示出了一种电池单体45，其电极组件300的投影为非正六边形。
在一些实施例中，电极组件300的投影为正多边形。例如，图11示出了一种电池单体45，其电极组件300的投影为正六边形。
在装配时，将正多边形的形心(即外接圆Ci的圆心)配置在圆柱状的容纳腔110的轴心线上，当正多边形膨胀至各顶点抵接壳体100的内壁时，壳体100的内壁对多边形具有反作用力，反作用力的着力部位在多边形的顶点。由于正多边形的各顶点间隔均匀，使得投影为正多边形的电极组件300的受力部位在外周上均匀分布，从而电极组件300受力相对均匀，能够防止电极组件300出现由于受力不均而局部应力集中造成的极片过度挤压，进而防止电池性能衰减，从而提高电池循环寿命。
由于电极组件300不容易出现局部应力集中的情况，且电极组件300与壳体 100的内壁之间还存在余留空间来释放内应力，不仅能够防止电极组件300的极片过度挤压而产生孔隙率降低或材料颗粒破裂的微观损伤，还使得极片不容易出现因为内应力过大而破碎、断裂的宏观损伤。
并且，在外接圆Ci直径相同的情况下，正多边形的面积比同样边数的非正多边形的面积更大，这使得电池单体的能量密度更大。
在一些实施例中，电极组件300的投影除了如前述被配置为正五边形或正六边形外，还可以被配置为其他边数的正多边形，例如图12所示的正八边形、如图13所示的正十边形、或正十六边形。
在外接圆Ci直径相同时，正多边形的边数越多则正多边形的面积越大，在保证电极组件与壳体100的内壁之间具有足够的余留空间的情况下，增加正多边形的边数能够有效提高能量密度。
在本领域中，常以群裕度来表征电池单体的能量密度，如现有技术中圆柱形的电极组件，其群裕度为圆柱形的电极组件的直径与圆柱形的容纳腔的直径之比。本实施例中，定义电极组件300的投影所形成的多边形的外接圆Ci的直径与容纳腔110的直径之比为群裕度，群裕度越大则能量密度越大。
在一些实施例中，电池单体45的群裕度被配置为90％～100％，即电极组件300的投影的外接圆Ci直径与容纳腔110的直径的比值为90％～100％，以最大化利用容纳腔110的容纳体积，同时又给极片的膨胀提供余留空间，避免电极组件300被壳体100的内壁锁死导致电极组件300内部应力过大，防止极片过度挤压出现活性物质掉落、电解液浸润难、极片断裂等极片性能恶化的问题，进而防止电池单体的性能衰减而致使循环寿命减少。
在另一些实施例中，电池单体45的群裕度被配置为95％～100％，即电极组件300的投影的外接圆Ci直径与容纳腔110的直径的比值为95％～100％，以在保证具有用于释放电极组件300应力的余留空间的前提下，提高能量密度。
需要说明的是，这里所说的群裕度的值是指电池单体45在恒压下充电放电以化成激活时的状态。此时电极组件300可能已发生膨胀，即使此时电极组件300的顶点已抵接壳体100的内壁而群裕度达到100％，由于电极组件300和壳体100的内壁之间仍存在余留空间，电极组件300也不容易被锁死，极片不会过度挤压损坏，电解液不容易被挤出，电池单体45能够保持较低的内阻，不容易出现性能衰减或骤降的情况，从而具有较长的循环寿命。
如前文所述，本实施例中的电极组件300包括第一极片310和第二极片320。电极组件300可以由包括第一极片310和第二极片320在内的材料堆叠成型，也可以由包括第一极片310和第二极片320在内的材料卷绕成型。
在此以电极组件300由第一极片310和第二极片320卷绕成型为例进行说明，先设定电极组件300的投影形状，例如设定电极组件300为棱柱，其投影为正六 边形。
如图14所示，为便于描述电极组件300的卷绕结构，图14中给出了投影为正六边形时的区域划分图，正六边形具有A、B、C、D、E、F六个顶点，定义电极组件300的投影的顶点与电极组件300的投影的外接圆圆心O的连线为第一直线，即正六边形包括六条第一直线：AO、BO、CO、DO、EO、FO，六条第一直线将正六边形分成I、II、III、IV、V、VI六个区域，其中区域I为三角形AOB、区域II为三角形BOC、区域III为三角形COD、区域IV为三角形DOE、区域V为三角形EOF、区域VI为三角形FOA。以下描述的第一直线和区域均以此为准。
图15中示出了第一极片310和第二极片320的投影，本实施例中，第一极片310为正极极片，第二极片320为负极极片。
第一极片310从六个区域中的一个出发并沿顺时针方向或逆时针方向卷绕，第二极片320从六个区域中的一个出发并沿顺时针方向或逆时针方向卷绕。一般而言，第一极片310和第二极片320先层叠后再卷绕，第一极片310和第二极片320的卷绕方向相同。
以下描述中，以靠近外接圆圆心O为内、以远离外接圆圆心O为外。例如图15中，第一极片310和第二极片320均从区域I出发并沿逆时针方向由内向外卷绕。
图15中，第一极片的卷绕起始端311在区域I，第一极片的卷绕收尾端312在与区域I相邻的区域VI；第二极片的卷绕起始端321在区域I，第二极片的卷绕收尾端322在与区域I相邻的区域VI。此时，第一极片310的卷绕圈数为整数，第二极片320的卷绕圈数也为整数。换句话说，第一极片310经过区域I、区域II、区域III、区域IV、区域V、区域VI的次数相等，第一极片310在每个区域中叠加的层数相同，为两层；同理，第二极片320经过区域I、区域II、区域III、区域IV、区域V、区域VI的次数相等，第二极片320在每个区域中叠加的层数相同，为三层。此时每个区域内的极片层数相等，均为五层，任意两个区域内的极片层数差为0。
图15中，第一极片的卷绕起始端311和第一极片的卷绕收尾端312在相邻的区域，第二极片的卷绕起始端321和第二极片的卷绕收尾端322在相邻的区域，但第一极片310和第二极片320的卷绕圈数不同。作为负极极片的第二极片320的卷绕圈数大于正极极片的第一极片310的卷绕圈数，以使电极组件300的最内圈层和最外圈层均为第二极片320，保证第一极片310的内侧面和外侧面均始终对应有第二极片320，锂离子从第一极片310的两个表面中的任一个脱嵌后都能嵌入第二极片320，有效防止由于第二极片320余量不足而析锂。
在其他实施例中，第一极片310和第二极片320的卷绕圈数也可以相同。如图16所示，图16示出了第一极片310和第二极片320的投影，第一极片的卷绕起始端311在区域I、第一极片的卷绕收尾端312在区域VI，第二极片的卷绕起始端321在区域I、第二极片的卷绕收尾端322在区域VI，即第一极片的卷绕起始端311和第 一极片的卷绕收尾端312在相邻的区域，第二极片的卷绕起始端321和第二极片的卷绕收尾端322在相邻的区域，且设置第一极片310和第二极片320的卷绕圈数相同，第一极片310和第二极片320在每个区域中叠加的层数都为两层，每个区域的极片层数都为四层。电极组件300的最内圈层为第二极片320，最外圈层为第一极片310，为防止析锂，第一极片310的外侧面至少没有覆盖第二极片320的部分不设涂覆层，即不涂布活性物质，且第二极片的卷绕收尾端322边缘超出第一极片的卷绕收尾端312边缘，以防第二极片320余量不足。
每个极片具有两个表面，在卷绕时，两个表面中始终有一面朝向外接圆圆心O方向、另一面朝向壳体100的内壁方向，以朝向外接圆圆心O的一面为内侧面，以朝向壳体100的内壁方向的一面为外侧面。
在其他实施例中，还可以有其他卷绕形式以使任意两个区域内的极片层数差为0。
例如图17所示，图17示出了第一极片310和第二极片320的投影，第一极片的卷绕起始端311在区域II，第一极片的卷绕收尾端312在区域VI，第二极片的卷绕起始端321在区域I，第二极片的卷绕收尾端322也在区域I，从图17中可见此时每个区域内的极片层数相等，均为五层。
需要说明的是，某一区域内的极片层数是指该区域内的第一极片310层数与该区域内的第二极片320层数之和。第一极片310每到达或经过一个区域一次，第一极片310在该区域内叠加一层，该区域的第一极片310层数加一；同理，第二极片320每到达或经过一个区域一次，第二极片320在该区域内叠加一层，该区域的第二极片320层数加一。
每个区域内的极片层数相差为0时，每个区域内极片叠加的层数相同，使得每个顶点与壳体100的内壁的距离大致相等，电极组件300膨胀时各顶点受到的反作用力相近，以免出现某一顶点相对地过于接近壳体100的内壁而应力过大，以防该顶点应力集中而出现极片过压或断裂。
当电极组件300的投影被设定为正多边形时，每个区域内的极片层数相同时，卷绕成型的电极组件300相对更接近设定的正多边形，从而能够提高容纳腔110的内部空间利用率，增大电池单体45的能量密度。
为防止出现析锂现象，第一极片310收尾后，第二极片320继续卷绕以具备足够的负极极片余量，以防离子从第一极片310脱嵌后不能嵌入第二极片320而析出，此时任意两个区域内的极片层数差可能不为0。为兼顾防止应力过于集中的目的和保证内部空间利用率的目的，在另一些实施例中，可设定任意两个区域内的极片层数差为1。例如图18中，图18示出了第一极片310和第二极片320的投影，第一极片的卷绕起始端311和第二极片的卷绕起始端321均在区域I，第一极片的卷绕收尾端312在与区域I相邻的区域VI，第二极片的卷绕收尾端322在经过区域VI后继续卷绕至区 域I停止，此时区域I的极片层数相比其他区域的极片层数多一层。
在其他实施例中，还可以有其他卷绕形式以使任意两个区域内的极片层数差为0或1，第一极片的卷绕起始端311所在的区域、第二极片的卷绕起始端321所在的区域、第一极片的卷绕收尾端312所在的区域和第二极片的卷绕收尾端322所在的区域可以均相同、也可以均不相同或部分相同。
在一些实施例中，第一极片的卷绕收尾端312边缘不在任一第一直线上，第二极片的卷绕收尾端322边缘不在任一第一直线上。
如图19所示，图19示出了第一极片310和第二极片320的投影，第一极片的卷绕收尾端312边缘、第二极片的卷绕收尾端322边缘均在区域VI中，但不在第一直线AO上。
由于第一极片310或第二极片320卷绕时每到达或经过某一第一直线一次，该第一直线就增加一层极片厚度的长度，电极组件300的投影及其外接圆Ci直径也相应增大。因此，与第一极片的卷绕收尾端312边缘和第二极片的卷绕收尾端322边缘均在第一直线AO上相比，第一极片的卷绕收尾端312边缘、第二极片的卷绕收尾端322边缘不在第一直线AO上时，各个区域内极片层数并未改变(仍为九层)，能量密度减小较少甚至基本相同，但顶点A到壳体100的内壁的距离相对减小，使得外接圆Ci的直径相对减小，相当于在不增加群裕度的情况下提高能量密度，进一步兼顾便于装配的目的和提高能量密度的目的。
在任意两个区域的极片层数相差为0的情况下，第一极片的卷绕收尾端312边缘、第二极片的卷绕收尾端322边缘不在第一直线上，还具有保证各个顶点到壳体100的内壁的距离大致相等的作用。以图19为例，由于收尾时顶点A处没有增加层数，第一直线AO、第一直线BO、第一直线CO、第一直线DO、第一直线EO、第一直线FO上均具有九层极片，进一步保证顶点A、顶点B、顶点C、顶点D、顶点E、顶点F到壳体100的内壁的距离大致相等，从而保证电极组件300的外周面抵接壳体100的内壁时顶点A、顶点B、顶点C、顶点D、顶点E、顶点F处受到的反作用力相等，以免某一顶点处局部应力过大而损坏。
在一些实施例中，第一极片的卷绕起始端311边缘不在任一第一直线上，第二极片的卷绕起始端321边缘不在任一第一直线上。
当卷绕起始端边缘在第一直线上时，卷绕起始端的端面会抵在相邻区域的极片表面，这导致卷绕起始端的端面容易被摩擦而致使端面附近的涂覆层掉粉，或导致被该端面抵接的极片表面掉粉。以图19为例，图19中为便于查看放大了极片之间的间距，实际极片之间间距很小，由于第一极片310卷绕起始端边缘在第一直线AO上，第一极片310卷绕起始端的端面将接触区域VI中最内层的第二极片320的表面，第一极片的卷绕起始端311的端面容易被摩擦导致接触部位附近涂覆层掉粉；同理，假设第二极片320卷绕起始端边缘在第一直线AO上，第二极片320卷绕起始端的端面 将接触区域VI中最内层的第二极片320的表面，第二极片的卷绕起始端321的端面容易被摩擦导致接触部位附近的涂覆层掉粉。
如图21，通过使第一极片的卷绕起始端311边缘、第二极片的卷绕起始端321边缘均不在第一直线AO上，第一极片的卷绕起始端311的端面和第二极片的卷绕起始端321的端面都不会抵在区域VI中最内层的第二极片320的表面，不会导致卷绕起始端的端面附近涂覆层掉粉。极片上的涂覆层一般为活性物质层，涂覆层掉粉会导致出现析锂及影响电池单体45的循环寿命，因此通过使第一极片的卷绕起始端311边缘、第二极片的卷绕起始端321边缘均不在第一直线AO上，能够防止析锂，并有效提高电池单体45的循环寿命。
在一些实施例中，第一极片的卷绕起始端311边缘、第二极片的卷绕起始端321边缘、第一极片的卷绕收尾端312边缘、第二极片的卷绕收尾端322边缘不在外接圆Ci的同一直径上，以免局部位置台阶重叠而出现局部应力集中，同时避免台阶重叠位置处厚度相对其他部位较大，从而更好的利用内部空间，提高内部空间利用率以提高能量密度。
在一些实施例中，电极组件300设有卷筒。这里说的卷筒是指为便于使电极组件300卷绕成型而设置在电极组件300的轴心的多边形柱体，该多边形柱体的边数或者说侧面数量与设定的多边形的边数相同，第一极片310和第二极片320绕卷筒卷绕以形成投影形状与设定的多边形大小相同的电极组件300。
当电极组件300同轴设置有用于辅助卷绕的卷筒时，极片的卷绕起始端边缘没有向内侧轻微变形的活动余量，倘若极片的卷绕起始端边缘在第一直线上时也会增加第一直线的长度。因此，该情况下，卷绕起始端边缘不在第一直线上，同样具有不增加第一直线的长度的作用，进而起到不增加外接圆Ci直径的作用，以在不增加群裕度的情况下进一步提高能量密度；在一些情况下，也同样具有保证各个顶点到壳体100的内壁的距离大致相等的作用，以使各顶点处受到的反作用力相等，以免某一顶点处局部应力过大而导致极片过压。
为进一步缓解顶点处应力集中的问题，在一些实施例中，电极组件300的投影的相邻两条边之间平滑过渡。
相邻两条边之间平滑过渡使得多边形的顶点处为圆角，形成圆弧面，圆弧面与圆柱形的壳体100的内壁的接触面积更大，如图20所示，图20以正六边形为例示出了电极组件300膨胀时的投影示意图，图20中虚线为膨胀后的电极组件300的投影，图20中顶点A处为非平滑过渡的，顶点B、顶点C、顶点D、顶点E、顶点F处为平滑过渡，对比可见：在电极组件300膨胀至抵接壳体100的内壁时，平滑过渡位置处形成的圆弧面基本全部接触圆柱形的壳体100的内壁，换句话说，顶点B、顶点C、顶点D、顶点E、顶点F处的接触面积均大于顶点A处的接触面积，因此平滑过渡的顶点处的受力面积增加而使得单位面积上的内力减小，也即应力减小，缓解了局部应力集中的问题，进一步防止极片过度挤压，缓解极片过度挤压导致电池单体的性能衰 减，进而提高电池单体的循环寿命。
卷绕时，如图21所示，图21示出了第一极片310和第二极片320的投影，第一极片310和第二极片320在第一直线处转折以改变卷绕方向，改变卷绕方向就是指第一极片310或第二极片320沿多边形的一条边转向多边形的另一条边，而第一极片310和第二极片320在每次转折时形成圆角，以使各个顶点处为圆弧面。在采用除卷绕以外的方式处理极片以形成电极组件300时，例如采用堆叠成型的方式时，可通过热压等其他手段使电极组件300的投影的相邻两条边之间平滑过渡。
在电极组件300实际成型过程中，由于工艺波动，电极组件300可能不是完全的正多边形。多边形的顶角会有±10％的制造公差，顶角处形成圆角时：0.9*(180°-360°/n)≤φ≤1.10*(180°-360°/n)，其中φ为多边形两相邻边的延长线的夹角，n为多边形的边数。
当电池单体45的电解质为电解液时，第一极片310和第二极片320之间还设有电子绝缘层，电子绝缘层可以是隔膜。
如图21所示，第一隔膜330和第二隔膜340的长度分别大于第一极片310和第二极片320的长度，第二隔膜340、第二极片320、第一隔膜330、第一极片310依次层叠后再开始卷绕，层叠后第一极片的卷绕起始端311边缘超出第二极片的卷绕起始端321边缘，第一隔膜330的卷绕起始端边缘、第二隔膜340的卷绕起始端边缘分别超出第一极片的卷绕起始端311边缘。
卷绕后，第二极片320处于最内圈层，至少第二隔膜340覆盖最内圈层。第一极片310的内侧面和第二极片320的外侧面之间由第一隔膜330分隔，第一极片310的外侧面和第二极片320的内侧面之间由第二隔膜340分隔。
在第一极片310和第二极片320卷绕收尾后，第一隔膜330和第二隔膜340继续卷绕以覆盖第一极片的卷绕收尾端312和第二极片的卷绕收尾端322。
隔膜在电极组件300的外周卷绕的圈数越多，对电极组件300的束缚性越好，防止极片松散导致内阻增大，进而避免内阻增大导致电池性能降低，从而保证电池的循环寿命。为更好裹紧电极组件300，以防第一极片310和第二极片320松散、间距过大，第一隔膜330和第二隔膜340中的至少一者在覆盖第一极片的卷绕收尾端312和第二极片的卷绕收尾端322后继续卷绕0.25～5圈。
但隔膜卷绕圈数较多将占用电极组件300与壳体100的内壁之间的空间，为兼顾裹紧效果和空间占用问题，在一些实施例中，第一隔膜330和第二隔膜340中的至少一者在覆盖第一极片的卷绕收尾端312和第二极片的卷绕收尾端322后继续卷绕1.25～2圈。
为进一步裹紧电极组件300，以免出现界面差，同时避免隔膜卷绕圈数较多而占用空间，在一些实施例中，如图22所示，图22示出了电极组件300的投影视图，在卷绕完成的电极组件300的外部设有束缚层400。束缚层400用于包裹电极组件 300，以防止第一极片310和第二极片320松散，并防止由于松散而变形，使电极组件300保持其设定的多边形形状。并且，束缚层400具有弹性以容许电极组件300膨胀，即随着电极组件300向外膨胀，束缚层400同步向外膨胀，在防止极片松散的同时避免束缚层400过度挤压极片。
本申请附图中为便于观察，放大了束缚层400的厚度，这仅是示意，不代表束缚层400的实际厚度，也不代表束缚层400投影与电极组件300的投影的尺寸比例。
在一些实施例中，具有弹性的束缚层400可以采用对苯二甲酸与乙二醇的缩聚物等材料制成，或采用压敏胶制成，压敏胶的粘黏强度的选取范围大于0.1N/mm。
在一些实施例中，束缚层400为套筒，套筒套设在电极组件300的外部。
为进一步防止电极组件300锁死，在一些实施例中，束缚层400的内壁与壳体100的内壁之间预设有空隙，该空隙可以进一步为电极组件300膨胀的提供更多的余留空间。
电极组件300膨胀后，电极组件300通过束缚层400间接接触壳体100的内壁。为进一步防止电极组件300锁死，如图23所示，图23示出了电极组件300的投影视图，束缚层400套设在电极组件300的外部后所形成的三维形状与电极组件300的三维形状相同。
在一些实施例中，束缚层400未套设在电极组件300外部时的三维形状与电极组件300的三维形状不同，由于具有弹性，使得束缚层400套设在电极组件300的外部后所形成的三维形状与电极组件300的三维形状相同。
在另一些实施例中，束缚层400未套设在电极组件300外部时的三维形状与电极组件300的三维形状相同。如图24所示，图24示出了一种电池单体45的分解图，其中电极组件300为正六棱柱，束缚层400为正六棱柱，在其他实施例中，电极组件300为其他三维形状时，束缚层400为相同的其他三维形状。
在一些实施例中，如图24所示，壳体100的外部形状被配置为圆柱状，相应的，端盖组件200沿电池单体的高度方向H的投影为圆形。
当端盖组件200的外部形状沿电池单体的高度方向H的投影为多边形时，壳体100至少在开口处的边缘也为相同的多边形，装配时需要将壳体100和端盖组件200对齐，以使二者的投影的顶点和边重叠；在对齐后需要将壳体100与端盖组件200焊接固定，焊接时每到多边形的顶点处就需要停下焊枪，转换焊接方向。而圆柱状的壳体100和投影为圆形的端盖组件200在装配时无需对齐，直接盖合即可，焊接时能够沿环形路径一次性焊接，无需停顿，降低了装配难度，提高了装配效率，减小了工时成本。
上文描述了本申请实施例的电池单体45、电池4，并以车辆1为例描述了 用电设备，下面将描述本申请实施例的制备电池单体45的方法和装置，其中未详细描述的部分可参见前述各实施例。
图25示出了本申请一个实施例的电池单体45的制备方法的流程示意图，该方法可以包括：
S100，提供壳体100，壳体100具有圆柱状的容纳腔110；
S200，提供电极组件300，电极组件300沿电池单体的高度方向H的投影为多边形；
S300，将电极组件300设置在容纳腔110内。
图26示出了本申请一个实施例的电池单体45的制备装置500的示意性框图，制备装置500可以包括：第一提供装置510、第二提供装置520和组装装置530。
第一提供装置510用于提供壳体100，壳体100具有圆柱状的容纳腔110；
第二提供装置520用于提供电极组件300，电极组件300沿所述电池单体的高度方向H的投影为多边形；
组装装置530用于将电极组件300设置在容纳腔110内。
以上所述仅为本申请的优选实施例而已，并不用于限制本申请，对于本领域的技术人员来说，本申请可以有各种更改和变化。凡在本申请的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本申请的保护范围之内。

Claims (20)

  1. 一种电池单体，其中，包括：
    壳体，具有圆柱状的容纳腔；
    电极组件，设置在所述容纳腔内，所述电极组件沿所述电池单体的高度方向的投影为多边形。
  2. 根据权利要求1所述的电池单体，其中，所述电极组件的所述投影为五边形、六边形、八边形、十边形或十六边形。
  3. 根据权利要求1-2任一项所述的电池单体，其中，所述电极组件的任一与所述电池单体的高度方向垂直的截面的形状均为多边形。
  4. 根据权利要求1-3任一项所述的电池单体，其中，所述电极组件的三维形状为棱柱。
  5. 根据权利要求4所述的电池单体，其中，所述电极组件的三维形状为正棱柱。
  6. 根据权利要求1-5任一项所述的电池单体，其中，所述电极组件的所述投影的相邻两条边之间平滑过渡。
  7. 根据权利要求1-6任一项所述的电池单体，其中，所述电极组件的所述投影的外接圆直径与所述容纳腔的直径的比值为90％～100％。
  8. 根据权利要求7所述的电池单体，其中，所述电极组件的所述投影的外接圆直径与所述容纳腔的直径的比值为95％～100％。
  9. 根据权利要求1-8任一项所述的电池单体，其中，所述电极组件包括第一极片和与所述第一极片极性相反的第二极片，所述第一极片和所述第二极片卷绕形成所述电极组件；
    定义所述电极组件的所述投影的任一顶点与所述电极组件的所述投影的外接圆圆心的连线为第一直线，所述第一极片的卷绕收尾端边缘沿所述电池单体的高度方向的投影不在任一第一直线上，所述第二极片的卷绕收尾端边缘沿所述电池单体的高度方向的投影不在任一第一直线上。
  10. 根据权利要求1-9任一项所述的电池单体，其中，所述电极组件包括第一极片和与所述第一极片极性相反的第二极片，所述第一极片和所述第二极片卷绕形成所述电极组件；
    定义所述电极组件的所述投影的任一顶点与所述电极组件的所述投影的外接圆圆心的连线为第一直线，所述第一极片的卷绕起始端边缘沿所述电池单体的高度方向的投影不在任一第一直线上，所述第二极片的卷绕起始端边缘沿所述电池单体的高度方向的投影不在任一第一直线上。
  11. 根据权利要求1-10任一项所述的电池单体，其中，所述电极组件包括第一极片和与所述第一极片极性相反的第二极片，所述第一极片和所述第二极片卷绕形成所述电极组件；
    定义所述电极组件的所述投影的任一顶点与所述电极组件的所述投影的外接圆圆心的连线为第一直线，所述电极组件的所述投影由多条所述第一直线划分为多个区 域，任意两个区域内的极片层数之差小于或等于1。
  12. 根据权利要求11所述的电池单体，其中，所述第一极片的卷绕起始端边缘沿所述电池单体的高度方向的投影和所述第一极片的卷绕收尾端边缘沿所述电池单体的高度方向的投影位于相邻两个区域内，所述第二极片的卷绕起始端边缘沿所述电池单体的高度方向的投影和所述第二极片的卷绕收尾端边缘沿所述电池单体的高度方向的投影位于相邻两个区域内。
  13. 根据权利要求1-12任一项所述的电池单体，其中，所述电池单体还包括：
    束缚层，用于包裹所述电极组件，所述束缚层具有弹性以容许所述电极组件膨胀。
  14. 根据权利要求13所述的电池单体，其中，所述束缚层为套筒，所述束缚层套设在所述电极组件的外部。
  15. 根据权利要求14所述的电池单体，其中，所述束缚层与所述壳体的内壁之间具有空隙。
  16. 根据权利要求15所述的电池单体，其中，套设在所述电极组件的外部的所述束缚层所形成的三维形状与所述电极组件的三维形状相同。
  17. 一种电池，其中，包括根据权利要求1-16任一项所述的电池单体。
  18. 一种用电设备，其中，包括根据权利要求17所述的电池。
  19. 一种电池单体的制备方法，其中，包括：
    提供壳体，所述壳体具有圆柱状的容纳腔；
    提供电极组件，所述电极组件沿所述电池单体的高度方向的投影为多边形；
    将所述电极组件设置在所述容纳腔内。
  20. 一种电池单体的制备装置，其中，包括：
    第一提供装置，用于提供壳体，所述壳体具有圆柱状的容纳腔；
    第二提供装置，用于提供电极组件，所述电极组件沿所述电池单体的高度方向的投影为多边形；
    组装装置，用于将所述电极组件设置在所述容纳腔内。
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