WO2024031256A1 - 电极组件、电池单体、电池及用电设备 - Google Patents

电极组件、电池单体、电池及用电设备 Download PDF

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Publication number
WO2024031256A1
WO2024031256A1 PCT/CN2022/110921 CN2022110921W WO2024031256A1 WO 2024031256 A1 WO2024031256 A1 WO 2024031256A1 CN 2022110921 W CN2022110921 W CN 2022110921W WO 2024031256 A1 WO2024031256 A1 WO 2024031256A1
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WO
WIPO (PCT)
Prior art keywords
active material
material layer
ending end
electrode assembly
thinned portion
Prior art date
Application number
PCT/CN2022/110921
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English (en)
French (fr)
Inventor
陈江
周建华
宋晋阳
吴凯
Original Assignee
宁德时代新能源科技股份有限公司
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Publication date
Application filed by 宁德时代新能源科技股份有限公司 filed Critical 宁德时代新能源科技股份有限公司
Priority to PCT/CN2022/110921 priority Critical patent/WO2024031256A1/zh
Priority to CN202280006795.XA priority patent/CN117859231A/zh
Priority to CN202320920260.5U priority patent/CN220382161U/zh
Publication of WO2024031256A1 publication Critical patent/WO2024031256A1/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
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/054—Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
    • 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
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • 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, specifically, to an electrode assembly, a battery cell, a battery and electrical equipment.
  • secondary batteries have the advantages of small size, high energy density, high power density, multiple cycles and long storage time. Therefore, it is widely used in portable electronic devices, electric vehicles, power tools, drones, energy storage equipment and other fields.
  • the safety of batteries is one of the main concerns of users and one of the main factors restricting the development of batteries. Therefore, how to improve the safety performance of batteries has become an urgent problem in the battery field.
  • Embodiments of the present application provide an electrode assembly, a battery cell, a battery and electrical equipment to improve the safety performance of the battery.
  • inventions of the present application provide an electrode assembly.
  • the electrode assembly has a wound structure.
  • the electrode assembly includes a first pole piece.
  • the first pole piece includes a first current collector and a first active material layer. and a second active material layer, the first active material layer and the second active material layer are respectively disposed on two opposite surfaces of the first current collector; wherein the first active material layer has a first ending end, the second active material layer has a second ending end, and the first ending end and the second ending end are staggered along the winding direction of the electrode assembly.
  • the first ending end of the first active material layer and the second ending end of the second active material layer provided on the two opposite surfaces of the first current collector are offset along the winding direction of the electrode assembly, so that the first The pole piece forms a smaller thickness area between the first ending end and the second ending end, which can reduce the thickness of the winding ending area of the first pole piece and reduce the rolling of the first pole piece during the expansion process of the electrode assembly.
  • the shear stress on the adjacent pole pieces around the winding end area makes the pole pieces adjacent to the winding end area of the first pole piece less likely to be locally strained, thus slowing down the winding end area of the first pole piece and causing the adjacent pole pieces to
  • the problem of pole piece cracking can be reduced, thereby reducing the risk of short circuit caused by the isolation film being punctured due to pole piece cracking, thereby improving the safety performance of battery cells and batteries equipped with the electrode assembly.
  • the distance between the first ending end and the second ending end is L 1 , which satisfies L 1 ⁇ 10 mm.
  • the distance between the first ending end and the second ending end is L 1 , which satisfies L 1 ⁇ 10mm, so as to form a winding ending area of sufficient length and small thickness of the first pole piece, which is beneficial to the use of
  • the pole pieces adjacent to the first ending end and the second ending end are not prone to local strain, thereby mitigating the problem of cracking of the adjacent pole pieces.
  • the first pole piece further includes a first thinned portion, and the first thinned portion and the first active layer are disposed on the first current collector. On the same surface, the first thinned portion extends from the first ending end along the winding direction; wherein the thickness of the first weakened portion is smaller than the thickness of the first active material layer.
  • the first thinned portion is provided to cover part of the first current collector, so that the first current collector is exposed as little as possible, and the isolation film of the electrode assembly is reduced from being in contact with the first current collector and being damaged by the surface of the first current collector.
  • the risk of short circuit caused by burr puncture further improves the safety performance of battery cells and batteries equipped with this electrode assembly.
  • the thickness of the first thinned portion gradually decreases along the winding direction.
  • the thickness of the first thinned part gradually decreases, that is, the thickness of the first thinned part gradually changes, so that the connection position between the first thinned part and the first active material layer does not have a sudden change in thickness.
  • reducing the connection position between the first thinned portion and the first active material layer makes the adjacent pole piece susceptible to the risk of local strain.
  • the first thinned portion is an active material layer with the same polarity as the first active material layer.
  • the first thinned portion is an active material layer with the same polarity as the first active material layer, which is beneficial to improving the energy density of the battery cells and batteries equipped with the electrode assembly.
  • the expansion coefficient of the first thinned portion is smaller than the expansion coefficient of the first active material layer.
  • the expansion coefficient of the first thinned part is smaller than the expansion coefficient of the first active material layer, and the first thinned part is connected to the first ending end, which can restrain the expansion of the first active material layer to a certain extent. , can reduce the expansion degree of the first active material layer during the charging and discharging process, thereby reducing the risk that the first active material layer expands too much and causes local strain to occur in the pole piece adjacent to the first ending end, thereby slowing down the relationship between the first active material layer and the first ending end. The pole piece adjacent to the end and the second ending end is cracked.
  • the first thinned portion extends from the first ending end to the ending end of the first current collector along the winding direction.
  • the first thinned portion extends to the ending end of the first current collector.
  • the surface of the first current collector provided with the first active material layer is covered by the first active material layer and the first thinned portion. Cover to reduce the risk of the burrs of the first current collector puncturing the isolation membrane and causing a short circuit.
  • the first pole piece further includes a second thinned portion, and the second thinned portion and the second active layer are disposed on the first current collector.
  • the second thinned portion extends from the second ending end along the winding direction; wherein the thickness of the second weakened portion is smaller than the thickness of the second active material layer.
  • the second thinned portion is provided to cover part of the first current collector, so that the first current collector is exposed as little as possible, and the isolation film of the electrode assembly is reduced from being in contact with the first current collector and being damaged by the surface of the first current collector.
  • the risk of short circuit caused by burr puncture further improves the safety performance of battery cells and batteries equipped with this electrode assembly.
  • the thickness of the second thinned portion gradually decreases along the winding direction.
  • the thickness of the second thinned portion gradually decreases, that is, the thickness of the second thinned portion gradually changes, so that the connection position between the second thinned portion and the second active material layer does not have a sudden change in thickness.
  • reducing the connection position between the second thinned portion and the second active material layer makes the adjacent pole piece susceptible to the risk of local strain.
  • the second thinned portion is an active material layer with the same polarity as the second active material layer.
  • the second thinned portion is an active material layer with the same polarity as the second active material layer, which is beneficial to improving the energy density of the battery cells and batteries equipped with the electrode assembly.
  • the expansion coefficient of the second thinned portion is smaller than the expansion coefficient of the second active material layer.
  • the expansion coefficient of the second thinned portion is smaller than the expansion coefficient of the second active material layer, and the second thinned portion is connected to the second ending end, which can restrain the expansion of the second active material layer to a certain extent. , can reduce the expansion degree of the second active material layer during the charge and discharge process, thereby reducing the risk that the second active material layer expands too much and causes local strain to occur in the adjacent pole pieces, thus slowing down the connection between the first terminal end and the second terminal end.
  • the pole pieces adjacent to each other are cracked.
  • the second thinned portion extends from the second ending end to the ending end of the first current collector along the winding direction.
  • the second thinned portion extends to the ending end of the first current collector.
  • the surface of the first current collector provided with the second active material layer is covered by the second active material layer and the second thinned portion. Covering them together reduces the risk that the burrs of the first current collector will puncture the isolation film and cause a short circuit.
  • the electrode assembly further includes an isolation film and a second pole piece stacked and wound with the first pole piece, and the second pole piece is connected to the first pole piece.
  • the polarity of the plates is opposite, and the isolation film is sandwiched between the first pole piece and the second pole piece;
  • the second pole piece includes a second current collector, a third active material layer and a fourth active material layer, The third active material layer and the fourth active material layer are respectively disposed on two opposite surfaces of the second current collector; wherein the third active material layer has a third ending end, and the fourth active material layer
  • the material layer has a fourth ending end, and the first ending end and the second ending end are offset along the winding direction.
  • the third ending end of the third active material layer and the fourth ending end of the fourth active material layer provided on the opposite surfaces of the second current collector are offset along the winding direction of the electrode assembly, so that the second The pole piece forms a smaller thickness area between the third ending end and the third ending end, which can reduce the thickness of the winding ending area of the second pole piece and reduce the winding of the second pole piece during the expansion process of the electrode assembly.
  • the shear stress on the adjacent pole pieces around the winding end area makes the pole pieces adjacent to the winding end area of the second pole piece less likely to be locally strained, thereby slowing down the winding end area of the second pole piece and causing the adjacent pole pieces to
  • the problem of pole piece cracking can be reduced, thereby reducing the risk of short circuit caused by the isolation film being punctured due to pole piece cracking, thereby improving the safety performance of battery cells and batteries equipped with the electrode assembly.
  • the distance between the third ending end and the fourth ending end is L 2 , which satisfies L 2 ⁇ 10 mm.
  • the distance between the third ending end and the fourth ending end is L 2 , which satisfies L 2 ⁇ 10 mm, so as to form a winding ending area of sufficient length and smaller thickness of the second pole piece, which is beneficial to the use of
  • the pole pieces adjacent to the third ending end and the fourth ending end are not prone to local strain, thereby mitigating the problem of cracking of adjacent pole pieces.
  • the second pole piece further includes a third thinned portion, and the third thinned portion and the third active layer are disposed on the second current collector.
  • the third thinned portion extends from the third ending end along the winding direction; wherein the thickness of the third weakened portion is smaller than the thickness of the third active material layer.
  • the third thinned portion is provided to cover part of the second current collector, so that the second current collector is exposed as little as possible, thereby reducing the possibility that the isolation film of the electrode assembly is in contact with the second current collector and is exposed to the surface of the second current collector.
  • the risk of short circuit caused by burr puncture further improves the safety performance of battery cells and batteries equipped with this electrode assembly.
  • the thickness of the third thinned portion gradually decreases along the winding direction.
  • the thickness of the third thinned part gradually decreases, that is, the thickness of the third thinned part gradually changes, so that the connection position between the third thinned part and the third active material layer does not have a sudden change in thickness.
  • reducing the connection position between the third thinned portion and the third active material layer makes the adjacent pole piece susceptible to the risk of local strain.
  • the third thinned portion is an active material layer with the same polarity as the third active material layer.
  • the third thinned portion is an active material layer with the same polarity as the third active material layer, which is beneficial to improving the energy density of the battery cells and batteries equipped with the electrode assembly.
  • the expansion coefficient of the third thinned portion is smaller than the expansion coefficient of the third active material layer.
  • the expansion coefficient of the third thinned part is smaller than the expansion coefficient of the second active material layer, and the third thinned part is connected to the third ending end, which can restrain the expansion of the third active material layer to a certain extent. , can reduce the expansion degree of the third active material layer during the charging and discharging process, thereby reducing the risk that the third active material layer expands too much and causes local strain to occur in adjacent pole pieces, thus slowing down the connection between the third terminal and the fourth terminal. The pole pieces adjacent to each other are cracked.
  • the third thinned portion extends from the third ending end to the ending end of the second current collector along the winding direction.
  • the third thinned portion extends to the ending end of the second current collector.
  • the surface of the second current collector provided with the third active material layer is covered by the third active material layer and the third thinned portion. Covering them together reduces the risk that the burrs of the second current collector will puncture the isolation film and cause a short circuit.
  • the second pole piece further includes a fourth thinned portion, and the fourth thinned portion and the fourth active layer are disposed on the second current collector.
  • the fourth thinned portion extends from the fourth ending end along the winding direction; wherein the thickness of the fourth weakened portion is smaller than the thickness of the fourth active material layer.
  • the provision of the fourth thinned part can cover part of the second current collector, so that the second current collector is exposed as little as possible, reducing the isolation film of the electrode assembly from contacting the second current collector and being damaged by the surface of the second current collector.
  • the risk of short circuit caused by burr puncture further improves the safety performance of battery cells and batteries equipped with this electrode assembly.
  • the thickness of the fourth thinned portion gradually decreases along the winding direction.
  • the thickness of the fourth thinned part gradually decreases, that is, the thickness of the fourth thinned part gradually changes, so that the connection position between the fourth thinned part and the fourth active material layer does not have a sudden change in thickness.
  • reducing the connection position between the fourth thinned portion and the fourth active material layer makes the adjacent pole piece susceptible to the risk of local strain.
  • the fourth thinned portion is an active material layer with the same polarity as the fourth active material layer.
  • the fourth thinned portion is an active material layer with the same polarity as the fourth active material layer, which is beneficial to improving the energy density of the battery cell and battery equipped with the electrode assembly.
  • the expansion coefficient of the fourth thinned portion is smaller than the expansion coefficient of the fourth active material layer.
  • the expansion coefficient of the fourth thinned part is smaller than the expansion coefficient of the fourth active material layer, and the fourth thinned part is connected to the fourth ending end, which can restrain the expansion of the fourth active material layer to a certain extent. , can reduce the expansion degree of the fourth active material layer during the charging and discharging process, thereby reducing the risk of excessive expansion of the fourth active material layer causing local strain to occur in adjacent pole pieces, thereby slowing down the connection between the third terminal and the fourth terminal. The pole pieces adjacent to each other are cracked.
  • the fourth thinned portion extends from the fourth ending end to the ending end of the second current collector along the winding direction.
  • the fourth thinned portion extends to the ending end of the second current collector.
  • the surface of the second current collector provided with the fourth active material layer is covered by the fourth active material layer and the fourth thinned portion. Covering them together reduces the risk that the burrs of the second current collector will puncture the isolation film and cause a short circuit.
  • the first pole piece is a negative pole piece
  • the second pole piece is a positive pole piece
  • the first ending end is located outside the first current collector and along the The winding direction exceeds the second ending end
  • the third ending end is located outside the second current collector and exceeds the fourth ending end along the winding direction
  • the second ending end is along the The winding direction exceeds the third ending end.
  • the second ending end exceeds the third ending end along the winding direction, so that the second active material layer completely covers the third active material layer, which can reduce the risk of lithium precipitation, thereby improving the battery cell with the electrode assembly. and the safety performance of the battery; it can also prevent the alignment of the second ending end and the second ending end to form a new step with a larger size, which may cause the adjacent pole piece to be severely stressed locally and break.
  • the first pole piece is a negative pole piece
  • the second pole piece is a positive pole piece
  • the first ending end is located outside the first current collector and along the The winding direction exceeds the second ending end
  • the fourth ending end is located inside the second current collector and exceeds the third ending end along the winding direction; the second ending end is along the The winding direction exceeds the third ending end.
  • the second ending end exceeds the third ending end along the winding direction, which can avoid the alignment of the second ending end and the second ending end to form a new step with a larger size, which will cause serious local stress on the adjacent pole pieces. Fracture occurs, and the second active material layer can completely cover the third active material layer, thereby reducing the risk of lithium deposition in battery cells and batteries equipped with the electrode assembly, thereby improving the safety performance of battery cells and batteries.
  • the distance between the second ending end and the third ending end is L 3 , which satisfies L 3 ⁇ 10 mm.
  • the distance L 3 between the second ending end and the third ending end satisfies L 3 ⁇ 10mm, which can avoid the alignment of the second ending end and the second ending end to form a new step with a larger size, which will cause a phase change.
  • the adjacent pole piece was severely stressed locally and broke.
  • embodiments of the present application further provide a battery cell, including the electrode assembly provided in any embodiment of the first aspect.
  • the pole piece of the electrode assembly provided by any embodiment of the first aspect is not prone to cracking of the pole piece due to local strain of the pole piece, and the battery cell including the electrode assembly is damaged due to the cracking of the pole piece causing the separator to be punctured.
  • the risk of causing a short circuit is low, so the safety of the battery cells is better.
  • an embodiment of the present application provides a battery, including a box and the battery cell provided in the embodiment of the second aspect; the battery cell is accommodated in the box.
  • the battery cell in the embodiment of the second aspect has a low risk of short circuit due to the cracking of the pole piece and the puncture of the isolation film, and the safety of the battery cell is better. Therefore, the embodiment of the second aspect has The battery cells provided are also safer.
  • an embodiment of the present application provides an electrical device, including the battery provided in an embodiment of the third aspect.
  • the battery in the embodiment of the third aspect has better safety, and the electrical equipment is powered by the battery provided in the embodiment of the third aspect, which can improve the safety of electricity consumption.
  • Figure 1 is a schematic structural diagram of an electrode assembly in the prior art
  • Figure 2 is a schematic structural diagram of a vehicle provided by some embodiments of the present application.
  • FIG. 3 is a schematic structural diagram of a battery provided by some embodiments of the present application.
  • Figure 4 is an exploded view of a battery cell provided by some embodiments of the present application.
  • FIG. 5 is a schematic structural diagram of an electrode assembly provided by some embodiments of the present application.
  • FIG. 6 is a schematic structural diagram of an electrode assembly provided by other embodiments of the present application.
  • Figure 7 is a schematic structural diagram of an electrode assembly provided by some embodiments of the present application.
  • Figure 8 is a schematic structural diagram of an electrode assembly provided by some embodiments of the present application.
  • Figure 9 is a schematic structural diagram of an electrode assembly provided by some further embodiments of the present application.
  • Figure 10 is an enlarged view of point A in Figure 9;
  • FIG 11 is a schematic structural diagram of an electrode assembly provided by still other embodiments of the present application.
  • Figure 12 is an enlarged view of B in Figure 11;
  • Figure 13 is a schematic structural diagram of an electrode assembly provided by some further embodiments of the present application.
  • Figure 14 is an enlarged view of C in Figure 13;
  • FIG. 15 is a schematic structural diagram of an electrode assembly provided by still other embodiments of the present application.
  • Figure 16 is an enlarged view of D in Figure 15;
  • Figure 17 is a schematic structural diagram of an electrode assembly provided by some embodiments of the present application.
  • Figure 18 is an enlarged view of E in Figure 17;
  • Figure 19 is a schematic structural diagram of an electrode assembly provided by some further embodiments of the present application.
  • Figure 20 is an enlarged view of F in Figure 19;
  • Figure 21 is a schematic structural diagram of an electrode assembly provided by some embodiments of the present application.
  • Figure 22 is an enlarged view of G in Figure 21;
  • Figure 23 is a schematic structural diagram of an electrode assembly provided by other embodiments of the present application.
  • Figure 24 is an enlarged view of H in Figure 23;
  • FIG. 25 is a schematic structural diagram of an electrode assembly provided by still other embodiments of the present application.
  • Figure 26 is an enlarged view of J in Figure 25;
  • Figure 27 is a schematic structural diagram of an electrode assembly provided by some further embodiments of the present application.
  • Figure 28 is an enlarged view of K in Figure 27;
  • Figure 29 is a schematic structural diagram of an electrode assembly provided by still other embodiments of the present application.
  • Figure 30 is a schematic structural diagram of an electrode assembly provided by some other embodiments of the present application.
  • Icon 1000-vehicle; 100-battery; 10-box; 11-first part; 12-second part; 20-battery cell; 21-casing; 211-opening; 22', 22-electrode assembly; 221 ', 221-the first pole piece; 2211', 2211-the first current collector; 22111-the first surface; 22112-the second surface; 22113-the ending end of the first current collector; 2212', 2212-the first active material layer; 22121', 22121-first ending end; 2213', 2213-second active material layer; 22131', 22131-second ending end; 2214-first thinned portion; 2215-second thinned portion; 222 ', 222-isolation film; 223', 223-the second pole piece; 2231', 2231-the second current collector; 22311-the third surface; 22312-the fourth surface; 22313-the ending end of the second current collector; 2232 ', 2232-the third active material layer; 2
  • the indicated orientation or positional relationship is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of this application is commonly placed when used, or the orientation or positional relationship of this application.
  • the orientation or positional relationship commonly understood by those skilled in the art is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.
  • the terms “first”, “second”, “third”, etc. are only used to distinguish descriptions and shall not be understood as indicating or implying relative importance.
  • Power batteries are not only used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, but are also widely used in electric vehicles such as electric bicycles, electric motorcycles and electric cars, as well as in many fields such as military equipment and aerospace. . As the application fields of power batteries continue to expand, their market demand is also constantly expanding.
  • the battery mentioned in the embodiments of this application refers to a single physical module including one or more battery cells to provide higher voltage and capacity.
  • the battery mentioned in this application may include a battery module or a battery pack.
  • Batteries generally include a box for packaging one or more battery cells.
  • 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., which are not limited in the embodiments of this application.
  • the battery cell may be in the shape of a cylinder, a flat body, a rectangular parallelepiped or other shapes, and the embodiments of the present application are not limited to this.
  • Battery cells are generally divided into three types according to packaging methods: cylindrical battery cells, rectangular battery cells and soft-pack battery cells, and the embodiments of the present application are not limited to this.
  • the battery cell includes an electrode assembly.
  • the electrode assembly includes a first pole piece, a second pole piece and a separator.
  • the first pole piece and the second pole piece have opposite polarities, that is, one of the first pole piece and the second pole piece. One is the positive plate and the other is the negative plate.
  • the isolation film is used to separate the first pole piece and the second pole piece to prevent the first pole piece and the second pole piece from being short-circuited.
  • the first pole piece, the second pole piece and the isolation film may be laminated and rolled to form an electrode assembly in a rolled form.
  • the first pole piece, the second pole piece and the isolation film may be stacked to form a stacked electrode assembly.
  • the first pole piece 221 ′ includes a first current collector 2211 ′, a first active material layer 2212 ′ and a second active material layer 2213 ', the first active material layer 2212' and the second active material layer 2213' are respectively disposed on the two opposite surfaces of the first current collector 2211', the first ending end 22121' of the first active material layer 2212' and the second active material layer 2212'.
  • the second ending end 22131' of the material layer 2213' is flush in the winding direction , the first ending end 22121' and the second ending end 22131' will generate large shear stress on the adjacent pole pieces, so that the pole pieces adjacent to the first ending end 22121' and the second ending end 22131'
  • the second pole piece 223' includes a second current collector 2231', a third active material layer 2232' and a third active material layer 2232'.
  • the material layer 2232' and the fourth active material layer 2233' are respectively disposed on the two opposite surfaces of the second current collector 2231', the third ending end 22321' of the third active material layer 2232' and the fourth active material layer 2233'.
  • the fourth ending end 22331' is flush in the winding direction 22321' and the fourth ending end 22331' will produce large shear stress on the pole pieces adjacent to them, causing local strains on the pole pieces adjacent to the third ending end 22321' and the fourth ending end 22331'. As a result, adjacent pole pieces are squeezed and broken.
  • the first pole piece 221' is a negative pole piece
  • the second pole piece 223' is a positive pole piece
  • the first ending end 22121' and the second ending end 22131' are both located at the third ending end 22321 ' and the outside of the fourth ending end 22331'
  • the first ending end 22121' and the second ending end 22131' both extend beyond the third ending end 22321' and the fourth ending end 22331' along the winding direction X, in the electrode assembly 22 '
  • the second ending end 22131' will generate a large shear stress on the pole piece inside it (the first pole piece 221')
  • the third ending end 22321' will exert a large shear stress on the pole piece outside it (the first pole piece 221').
  • the fourth ending end 22331' will generate a large shear stress on the inner pole piece (the first pole piece 221'), causing the pole piece to generate local strain, thereby causing the adjacent
  • the pole piece is extruded, cracked or broken. Cracked or broken pole pieces will produce burrs, which can easily pierce the isolation film 222' and cause a short circuit risk, thereby causing safety issues for the battery cells and batteries equipped with the electrode assembly 22'.
  • the inventor in order to alleviate the problem that the pole piece is extruded, cracked or broken due to large shear stress, thereby causing safety issues for the battery cells and batteries equipped with the electrode assembly, the inventor has designed a In the electrode assembly, along the winding direction of the electrode assembly, the first ending end of the first active material layer of the first pole piece of the electrode assembly and the second ending end of the second active material layer are staggered.
  • the first ending end of the first active material layer and the second ending end of the second active material layer provided on two opposite surfaces of the first current collector are offset along the winding direction of the electrode assembly, so that the first pole piece is at the first end of the first current collector.
  • a smaller thickness area is formed between the ending end and the second ending end, which can reduce the thickness of the winding ending area of the first pole piece and reduce the relative angle between the winding ending area of the first pole piece during the expansion process of the electrode assembly.
  • the shear stress of the adjacent pole pieces makes the pole pieces adjacent to the winding end area of the first pole piece less likely to be locally deformed, thereby slowing down the winding end area of the first pole piece and causing the adjacent pole pieces to crack. problem, thereby reducing the risk of short circuit caused by the cracking of the pole piece causing the separator to be punctured, thereby improving the safety performance of the battery cells and batteries equipped with the electrode assembly.
  • the battery cells disclosed in the embodiments of the present application and equipped with the electrode assemblies provided by the embodiments of the present application can be, but are not limited to, used in electrical devices such as vehicles, ships, or aircrafts. Battery cells equipped with the electrode assemblies disclosed in the present application can also be used. Batteries and other components form the power supply system of the electrical equipment, which is beneficial to improving the energy density of battery cells and batteries.
  • Embodiments of the present application provide an electrical device that uses a battery as a power source.
  • the electrical device may be, but is not limited to, a mobile phone, a tablet, a laptop, an electric toy, an electric tool, a battery car, an electric vehicle, a ship, a spacecraft, etc.
  • electric toys can include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, electric airplane toys, etc.
  • spacecraft can include airplanes, rockets, space shuttles, spaceships, etc.
  • an electrical device is a vehicle 1000 as an example.
  • the vehicle 1000 may be a fuel vehicle, a gas vehicle or a new energy vehicle.
  • the new energy vehicle may be a pure electric vehicle, a hybrid vehicle or an extended range vehicle, etc.
  • the battery 100 is disposed inside the vehicle 1000 , and the battery 100 may be disposed at the bottom, head, or tail of the vehicle 1000 .
  • the battery 100 may be used to power the vehicle 1000 , for example, the battery 100 may serve as an operating power source for the vehicle 1000 .
  • the vehicle 1000 may also include a controller 200 and a motor 300 .
  • the controller 200 is used to control the battery 100 to provide power to the motor 300 , for example, for starting, navigating and driving the vehicle 1000 .
  • the battery 100 can not only be used as an operating power source for the vehicle 1000 , but also can be used as a driving power source for the vehicle 1000 , replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000 .
  • the battery 100 includes a case 10 and a battery cell 20 .
  • the battery cell 20 is accommodated in the case 10 .
  • the box 10 is used to provide an accommodation space for the battery cells 20, and the box 10 can adopt a variety of structures.
  • the box 10 may include a first part 11 and a second part 12 , the first part 11 and the second part 12 cover each other, and the first part 11 and the second part 12 jointly define a space for accommodating the battery cells 20 of accommodation space.
  • the second part 12 may be a hollow structure with one end open to form a receiving cavity for accommodating the battery cell 20 .
  • the first part 11 may be a plate-like structure.
  • the first part 11 is covered with the open side of the second part 12 so that the first part 11 Together with the second part 12, an accommodation space is defined; the first part 11 and the second part 12 may also be a hollow structure with one side open to form an accommodation cavity for accommodating the battery cell 20, and the open side of the first part 11 is closed. on the open side of the second part 12.
  • the box 10 formed by the first part 11 and the second part 12 can be in various shapes, such as cylinder, rectangular parallelepiped, etc.
  • the battery 100 there may be a plurality of battery cells 20, and the plurality of battery cells 20 may be connected in series, in parallel, or in mixed connection.
  • Mixed connection means that the plurality of battery cells 20 are connected in series and in parallel.
  • the plurality of battery cells 20 can be directly connected in series or in parallel or mixed together, and then the whole composed of the plurality of battery cells 20 can be accommodated in the box 10 ; of course, the battery 100 can also be a plurality of battery cells 20 First, the battery modules are connected in series, parallel, or mixed to form a battery module, and then multiple battery modules are connected in series, parallel, or mixed to form a whole, and are accommodated in the box 10 .
  • the battery 100 may also include other structures.
  • the battery 100 may further include a bus component for realizing electrical connections between multiple battery cells 20 .
  • the battery 100 may further include a bus component (not shown), through which the multiple battery cells 20 may be electrically connected to achieve series, parallel, or mixed connection of the multiple battery cells 20 .
  • a bus component (not shown), through which the multiple battery cells 20 may be electrically connected to achieve series, parallel, or mixed connection of the multiple battery cells 20 .
  • Each battery cell 20 may be a secondary battery or a primary battery; it may also be a lithium-sulfur battery, a sodium-ion battery or a magnesium-ion battery, but is not limited thereto.
  • the battery cells 20 may be flat, rectangular, or other shapes.
  • the battery cell 20 may include a case 21 , an electrode assembly 22 and an end cap 23 .
  • the housing 21 has an opening 211
  • the electrode assembly 22 is accommodated in the housing 21
  • the end cap 23 is used to cover the opening 211 .
  • the housing 21 can be in various shapes, such as square structure, cylindrical structure, etc.
  • the contour of the electrode assembly 22 can be adapted to the structural shape of the housing 21 .
  • the housing 21 can have a cylindrical structure; if the electrode assembly 22 has a square shape, the housing 21 can have a square shape.
  • FIG. 4 shows the case where the electrode assembly 22 and the housing 21 are both cylindrical structures.
  • the housing 21 can also be made of a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc., which are not particularly limited in the embodiment of the present application.
  • the end cap 23 refers to a component that covers the opening 211 of the housing 21 to isolate the internal environment of the battery cell 20 from the external environment.
  • the shape of the end cap 23 can be adapted to the shape of the housing 21 to fit the housing 21 .
  • the end cap 23 can be made of a material with a certain hardness and strength (such as aluminum alloy). In this way, the end cap 23 is less likely to deform when subjected to extrusion and collision, so that the battery cell 20 can have higher durability. Structural strength and safety performance can also be improved.
  • the end cap 23 is used to cover the opening 211 of the housing 21 to form a sealed installation space (not shown), and the installation space is used to accommodate the electrode assembly 22 .
  • the installation space is also used to accommodate electrolytes, such as electrolytes.
  • the end cap 23 is also provided with an electrode terminal 24 for outputting the electric energy of the electrode assembly 22.
  • the electrode terminal 24 is used for electrical connection with the electrode assembly 22, that is, the electrode terminal 24 is electrically connected to the tab (not shown in the figure) of the electrode assembly 22. , for example, the electrode terminal 24 and the tab are connected through a current collecting member (not shown in the figure) to realize the electrical connection between the electrode terminal 24 and the tab.
  • the opening 211 of the housing 21 may be one or two. If the opening 211 of the housing 21 is one, the end cover 23 can also be one, and two electrode terminals 24 can be provided in the end cover 23.
  • the two electrode terminals 24 are respectively a positive electrode terminal and a negative electrode terminal.
  • the positive electrode terminal and The negative electrode terminal is used to be electrically connected to the positive electrode lug (not shown in the figure) and the negative electrode lug (not shown in the figure) of the electrode assembly 22 respectively.
  • the two electrode terminals 24 in the end cap 23 are respectively the positive electrode terminal and the negative electrode terminal. extreme. In an embodiment where there is only one end cap 23 , the electrode terminal 24 is insulated from the end cap 23 .
  • One of the positive electrode lug and the negative electrode lug of the electrode assembly 22 is electrically connected to the electrode terminal 24 on the end cover 23 , and the other one can be electrically connected to the housing 21 .
  • the electrode terminal 24 in one end cover 23 may be a positive electrode terminal for electrical connection with the positive ear of the electrode assembly 22; the electrode terminal 24 in the other end cover 23 may be a negative electrode terminal for electrical connection with the positive electrode lug of the electrode assembly 22. to be electrically connected to the negative electrode piece of the electrode assembly 22 .
  • the end cap 23 can also be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., which are not particularly limited in the embodiment of the present application.
  • the housing 21 and the end cover 23 may be independent components, and an opening 211 may be provided on the housing 21.
  • the end cover 23 covers the opening 211 at the opening 211 to form the internal environment of the battery cell 20.
  • the end cover 23 and the housing 21 can also be integrated.
  • the end cover 23 and the housing 21 can form a common connection surface before other components are put into the housing. When it is necessary to encapsulate the inside of the housing 21 When the end cap 23 is closed, the housing 21 is closed.
  • the end cover 23 may also be provided with a pressure relief mechanism (not shown in the figure), which is used to relieve the pressure inside the battery cell 20 when the pressure or temperature inside the battery cell 20 reaches a threshold.
  • the pressure relief mechanism 25 may take the form of an explosion-proof valve, an explosion-proof disk, an air valve, a pressure relief valve, a safety valve, a weak portion formed on the end cover 23, etc.
  • the electrode assembly 22 has a wound structure.
  • the electrode assembly 22 includes a first pole piece 221.
  • the first pole piece 221 includes a first current collector 2211, a first active material layer 2212 and a second active material.
  • Layer 2213, the first active material layer 2212 and the second active material layer 2213 are respectively disposed on two opposite surfaces of the first current collector 2211; wherein, the first active material layer 2212 has a first ending end 22121, and the second active material layer 2213 has a second ending end 22131.
  • the first ending end 22121 and the second ending end 22131 are staggered.
  • the first active material layer 2212 and the second active material layer 2213 are respectively disposed on the two opposite surfaces of the first current collector 2211 along its thickness direction, respectively defined as the first surface 22111 and the second surface 22112.
  • the second surface 22112 is opposite to the second surface 22112 .
  • a surface 22111 is closer to the winding center of the electrode assembly 22 .
  • the first active material layer 2212 is disposed on the first surface 22111, and the second active material layer 2213 is disposed on the second surface 22112.
  • the second active material layer 2213 is disposed inside the first current collector 2211, and the first active material layer 2213 is disposed on the second surface 22112.
  • the layer 2212 is disposed outside the first current collector 2211.
  • the first ending end 22121 is the end of the first active material layer 2212 along the winding direction X
  • the second ending end 22131 is the end of the second active material layer 2213 along the winding direction X.
  • the first ending end 22121 and the second ending end 22131 are disposed in a staggered position" means that there is a distance between the first ending end 22121 and the second ending end 22131 along the winding direction X.
  • the first pole piece 221 may be a positive pole piece or a negative pole piece. If the first electrode piece 221 is a positive electrode piece, the first current collector 2211 is a positive electrode current collector, and both the first active material layer 2212 and the second active material layer 2213 are positive electrode active material layers. Taking the lithium ion battery 100 as an example, the positive electrode The material of the current collector can be aluminum, and the positive active material layer can be lithium cobalt oxide, lithium iron phosphate, ternary lithium or lithium manganate. If the first electrode piece 221 is a negative electrode piece, the first current collector 2211 is a negative electrode current collector, and the first active material layer 2212 and the second active material layer 2213 are both negative electrode active material layers.
  • the positive electrode can be copper, and the negative active material layer can be carbon or silicon.
  • FIG. 5 shows the case where the first pole piece 221 is a negative pole piece.
  • FIG. 6 shows the case where the first pole piece 221 is a positive pole piece.
  • the first ending end 22121 of the first active material layer 2212 and the second ending end 22131 of the second active material layer 2213 provided on the two opposite surfaces of the first current collector 2211 are offset along the winding direction X of the electrode assembly 22 so that The first pole piece 221 forms a smaller thickness area between the first ending end 22121 and the second ending end 22131, which can reduce the thickness of the winding ending area of the first pole piece 221 and reduce the expansion process of the electrode assembly 22.
  • the shear stress of the winding end area of the first pole piece 221 on the adjacent pole pieces makes the pole pieces adjacent to the winding end area of the first pole piece 221 less prone to local strain, thereby slowing down the first pole piece.
  • the winding end area of 221 causes the problem of cracking of adjacent pole pieces, thereby reducing the risk of short circuit caused by cracking of pole pieces causing the isolation film 222 to be punctured, thereby improving the battery cell 20 and the battery cell 20 with the electrode assembly 22 Battery 100 safety performance.
  • L 1 can be 11mm, 12mm, 13mm, 15mm, 16mm, 18mm, 20mm, etc.
  • the distance between the first ending end 22121 and the second ending end 22131 is L 1 , which satisfies L 1 ⁇ 10 mm, so as to form a winding ending area of a sufficient length and a small thickness for the first pole piece 221 , which is beneficial to the connection with the first pole piece 221 .
  • the adjacent pole pieces of the first ending end 22121 and the second ending end 22131 are not prone to local strain, thereby mitigating the problem of cracking of the adjacent pole pieces.
  • FIG. 5 shows a situation where the second ending end 22131 exceeds the first ending end 22121 along the winding direction X, that is, the second ending end 22131 is located in front of the first ending end 22121 along the winding direction X.
  • FIG. 6 shows a situation in which the first ending end 22121 exceeds the second ending end 22131 along the winding direction X, that is, the first ending end 22121 is located in front of the second ending end 22131 along the winding direction X.
  • the first current collector 2211 has a ending end, and the ending end 22113 of the first current collector is the end of the first current collector 2211 along the winding direction X. As shown in FIGS. 5 and 6 , the end end 22113 of the first current collector may be flush with the one in front of the first end end 22121 and the second end end 22131 . As shown in FIGS. 7 and 8 , the ending end 22113 of the first current collector may also extend beyond the first ending end 22121 or the second ending end 22131 along the winding direction X.
  • the first pole piece 221 further includes a first thinned portion 2214 , and the first thinned portion 2214 and the first active layer are disposed on the same surface of the first current collector 2211 .
  • the first thinned portion 2214 extends from the first ending end 22121 along the winding direction X; wherein the thickness of the first weakened portion is smaller than the thickness of the first active material layer 2212 .
  • the first thinned portion 2214 is connected to the first ending end 22121, and the first thinned portion 2214 is provided on a portion of the first surface 22111 beyond the first ending end 22121 along the winding direction X.
  • the first thinned portion 2214 may be a constant thickness structure.
  • the first thinned portion 2214 may also have a non-uniform thickness structure. In an embodiment in which the first thinned portion 2214 has an unequal thickness structure, the maximum thickness of the first thinned portion 2214 is smaller than the thickness of the first active active material layer.
  • the arrangement of the first thinned portion 2214 can cover part of the first current collector 2211, so that the first current collector 2211 is exposed as little as possible, and the isolation film 222 of the electrode assembly 22 is reduced from being in contact with the first current collector 2211.
  • the risk of short circuit caused by burrs on the surface of 2211 further improves the safety performance of the battery cells 20 and batteries 100 equipped with the electrode assembly 22 .
  • the first thinned portion 2214 may also have various forms of unequal thickness structures. As shown in FIGS. 11 and 12 , along the winding direction X, the thickness of the first thinned portion 2214 gradually decreases.
  • the surface of the first thinned portion 2214 facing away from the first surface 22111 is inclined along the winding direction X, so that the thickness of the first thinned portion 2214 gradually decreases along the winding direction X.
  • the material of the first thinned portion 2214 may be the same as that of the first active material layer 2212, or may be different. In some embodiments, the first thinned portion 2214 is an active material layer with the same polarity as the first active material layer 2212 .
  • the first active material layer 2212 is a positive electrode active material layer
  • the first thinned portion 2214 is also a positive electrode active material layer
  • the first active material layer 2212 is a negative electrode active material layer
  • the first thinned portion 2214 is also a positive electrode active material layer. 2214 is also the negative active material layer.
  • the first thinned portion 2214 is an active material layer with the same polarity as the first active material layer 2212, which is beneficial to improving the energy density of the battery cell 20 and the battery 100 including the electrode assembly 22.
  • the expansion coefficient of the first thinned portion 2214 is less than the expansion coefficient of the first active material layer 2212 .
  • the expansion coefficient is a physical quantity that characterizes the thermal expansion properties of an object, that is, a physical quantity that characterizes the degree of increase in length, area, and volume of an object when it is heated.
  • the expansion coefficient represents the degree of increase in length, area, and volume of the first thinned portion 2214 and the first active material layer 2212 during the charging and discharging process. physical quantity.
  • the partial composition and composition ratio of the material of the first thinned portion 2214 can be changed to make the second thinned portion 2214
  • the expansion coefficient of a thinned portion 2214 is smaller than the expansion coefficient of the first active material layer 2212 .
  • the expansion coefficient of the material of the first thinned part 2214 may be smaller than that of the first thinned part 2214.
  • the expansion coefficient of the first thinned portion 2214 is smaller than the expansion coefficient of the first active material layer 2212, and the first thinned portion 2214 is connected to the first ending end 22121, which can restrain the expansion of the first active material layer 2212 to a certain extent. , can reduce the expansion degree of the first active material layer 2212 during the charging and discharging process, thereby reducing the risk that the first active material layer 2212 expands too much and causes local strain to occur in the pole piece adjacent to the first ending end 22121, thereby mitigating the problem with The pole pieces adjacent to the first ending end 22121 and the second ending end 22131 are cracked.
  • the first thinned portion 2214 extends from the first ending end 22121 to the ending end 22113 of the first current collector along the winding direction X.
  • the first thinned portion 2214 extends to the ending end 22113 of the first current collector.
  • the surface of the first current collector 2211 provided with the first active material layer 2212 is thinned by the first active material layer 2212 and the first The portion 2214 is covered to reduce the risk that the burrs of the first current collector 2211 will puncture the isolation film 222 and cause a short circuit.
  • the first thinned portion 2214 may not extend from the first ending end 22121 to the ending end 22113 of the first current collector along the winding direction The direction X extends beyond an end of the first thinned portion 2214 away from the first ending end 22121.
  • the first pole piece 221 further includes a second thinned portion 2215 , and the second thinned portion 2215 and the second active layer are disposed on the same surface of the first current collector 2211 .
  • the second thinned portion 2215 extends from the second ending end 22131 along the winding direction X; wherein the thickness of the second weakened portion is smaller than the thickness of the second active material layer 2213 .
  • the second thinned portion 2215 is connected to the second ending end 22131, and the second thinned portion 2215 is provided on the portion of the second surface 22112 that exceeds the second ending end 22131 along the winding direction X.
  • the second thinned portion 2215 may be a constant thickness structure.
  • the second thinned portion 2215 may also have an unequal thickness structure. In an embodiment in which the second thinned portion 2215 has an unequal thickness structure, the maximum thickness of the second thinned portion 2215 is smaller than the thickness of the second active active material layer.
  • the arrangement of the second thinned portion 2215 can cover part of the first current collector 2211 so that the first current collector 2211 is exposed as little as possible and reduces the isolation film 222 of the electrode assembly 22 from contacting the first current collector 2211 and being damaged by the first current collector.
  • the risk of short circuit caused by burrs on the surface of 2211 further improves the safety performance of the battery cells 20 and batteries 100 equipped with the electrode assembly 22 .
  • the second thinned portion 2215 can also have various forms of unequal thickness structures. As shown in Figures 15 and 16, along the winding direction X, the thickness of the second thinned portion 2215 gradually decreases.
  • the surface of the second thinned portion 2215 facing away from the second surface 22112 is inclined along the winding direction X, so that the thickness of the second thinned portion 2215 gradually decreases along the winding direction X.
  • the material of the second thinned portion 2215 may be the same as that of the second active material layer 2213, or may be different. In some embodiments, the second thinned portion 2215 is an active material layer with the same polarity as the second active material layer 2213 .
  • the second active material layer 2213 is a positive electrode active material layer
  • the second thinned portion 2215 is also a positive electrode active material layer
  • the second active material layer 2213 is a negative electrode active material layer
  • the second thinned portion 2215 is also a positive electrode active material layer. 2215 is also the negative active material layer.
  • the second thinned portion 2215 is an active material layer with the same polarity as the second active material layer 2213, which is beneficial to improving the energy density of the battery cell 20 and the battery 100 including the electrode assembly 22.
  • the expansion coefficient of the second thinned portion 2215 is smaller than the expansion coefficient of the second active material layer 2213 .
  • the expansion coefficient represents the degree to which the length, area, and volume of the second thinned portion 2215 and the second active material layer 2213 increase during the charge and discharge process. physical quantity.
  • the partial composition, composition ratio, etc. of the material of the second thinned portion 2215 can be changed so that the second thinned portion 2215 has the same polarity.
  • the expansion coefficient of the two thinned parts 2215 is smaller than the expansion coefficient of the second active material layer 2213 .
  • the expansion coefficient of the material of the second thinned part 2215 may be smaller than that of the second thinned part 2215. The expansion coefficient of the second active material layer 2213.
  • the expansion coefficient of the second thinned portion 2215 is smaller than the expansion coefficient of the second active material layer 2213, and the second thinned portion 2215 is connected to the second ending end 22131, which can restrain the expansion of the second active material layer 2213 to a certain extent. , can reduce the expansion degree of the second active material layer 2213 during the charging and discharging process, thereby reducing the risk that the second active material layer 2213 expands too much and causes local strain to occur in the adjacent pole pieces, thereby mitigating the connection between the first terminal end 22121 and the first terminal end 22121.
  • the pole piece adjacent to the second ending end 22131 is cracked.
  • the second thinned portion 2215 extends from the second end end 22131 to the end end 22113 of the first current collector along the winding direction X.
  • the second thinned portion 2215 extends to the ending end 22113 of the first current collector.
  • the surface of the first current collector 2211 provided with the second active material layer 2213 is thinned by the second active material layer 2213 and the second 2215 are jointly covered to reduce the risk that the burrs of the first current collector 2211 will puncture the isolation film 222 and cause a short circuit.
  • the second thinned portion 2215 may not extend from the second ending end 22131 to the ending end 22113 of the first current collector along the winding direction The direction X extends beyond an end of the second thinned portion 2215 away from the second ending end 22131.
  • the electrode assembly 22 further includes an isolation film 222 and a second pole piece 223 stacked and wound with the first pole piece 221 .
  • the second pole piece 223 is in contact with the first pole piece 221 .
  • the isolation film 222 is sandwiched between the first pole piece 221 and the second pole piece 223;
  • the second pole piece 223 includes a second current collector 2231, a third active material layer 2232 and a fourth active material layer 2233.
  • the material layer 2232 and the fourth active material layer 2233 are respectively disposed on two opposite surfaces of the second current collector 2231;
  • the third active material layer 2232 has a third ending end 22321, and the fourth active material layer 2233 has a fourth ending end. 22331, along the winding direction X, the first ending end 22121 and the second ending end 22131 are staggered.
  • the isolation film 222 is stacked between the first pole piece 221 and the second pole piece 223 to insulate and separate the first pole piece 221 and the second pole piece 223 .
  • the material of the isolation film 222 may be PP (polypropylene, polypropylene) or PE (polyethylene, polyethylene), etc.
  • the third active material layer 2232 and the fourth active material layer 2233 are respectively disposed on the two opposite surfaces of the second current collector 2231 along the thickness direction, respectively defined as the third surface 22311 and the fourth surface 22312.
  • the fourth surface 22312 is opposite to the second current collector 2231 .
  • the three surfaces 22311 are closer to the winding center of the electrode assembly 22 .
  • the third active material layer 2232 is disposed on the third surface 22311, and the fourth active material layer 2233 is disposed on the fourth surface 22312. In other words, the fourth active material layer 2233 is disposed inside the second current collector 2231.
  • the layer 2232 is disposed outside the second current collector 2231 .
  • the third ending end 22321 is the end of the third active material layer 2232 along the winding direction X
  • the fourth ending end 22331 is the end of the fourth active material layer 2233 along the winding direction X.
  • the third ending end 22321 and the fourth ending end 22331 are dislocated means that there is a distance between the third ending end 22321 and the fourth ending end 22331 along the winding direction X.
  • the third ending end 22321 of the third active material layer 2232 and the fourth ending end 22331 of the fourth active material layer 2233 provided on the two opposite surfaces of the second current collector 2231 are offset along the winding direction X of the electrode assembly 22 so that The second pole piece 223 forms a smaller thickness area between the third ending end 22321 and the third ending end 22321, which can reduce the thickness of the winding ending area of the second pole piece 223 and reduce the expansion process of the electrode assembly 22.
  • the shear stress of the winding end area of the second pole piece 223 on the adjacent pole pieces makes the pole pieces adjacent to the winding end area of the second pole piece 223 less susceptible to local strain, thereby slowing down the second pole piece.
  • the winding end area of 223 causes the problem of cracking of the adjacent pole pieces, thereby reducing the risk of short circuit caused by the cracking of the pole pieces causing the isolation film 222 to be punctured, thereby improving the battery cell 20 and the battery cell 20 with the electrode assembly 22 Battery 100 safety performance.
  • the distance between the third ending end 22321 and the fourth ending end 22331 is L 2 , which satisfies L 2 ⁇ 10 mm.
  • L 2 can be 11mm, 12mm, 13mm, 15mm, 16mm, 18mm, 20mm, etc.
  • the distance between the third ending end 22321 and the fourth ending end 22331 is L2, which satisfies L2 ⁇ 10 mm, so as to form a winding ending area of sufficient length and smaller thickness for the second pole piece 223, which is beneficial to the third ending end.
  • the adjacent pole pieces at the end 22321 and the fourth ending end 22331 are not prone to local strain, thereby mitigating the problem of cracking of the adjacent pole pieces.
  • the second current collector 2231 has a ending end, and the ending end 22313 of the second current collector is the end of the second current collector 2231 along the winding direction X.
  • the end end 22313 of the second current collector may be flush with the one in front of the third end end 22321 and the fourth end end 22331. As shown in FIGS. 18 and 20 , the ending end 22313 of the second current collector may also exceed the one in front of the third ending end 22321 or the fourth ending end 22331 along the winding direction X.
  • the second pole piece 223 further includes a third thinned portion 2234.
  • the third thinned portion 2234 and the third active layer are disposed on the same surface of the second current collector 2231.
  • the third thinned portion 2234 is disposed on the same surface of the second current collector 2231. 2234 extends from the third ending end 22321 along the winding direction X; wherein the thickness of the third weakened portion is smaller than the thickness of the third active material layer 2232.
  • the third thinned portion 2234 is connected to the third ending end 22321, and the third thinned portion 2234 is provided on a portion of the third surface 22311 that exceeds the third ending end 22321 along the winding direction X.
  • the third thinned portion 2234 may be a constant thickness structure.
  • the third thinned portion 2234 may also have a structure of unequal thickness. In an embodiment in which the third thinned portion 2234 has an unequal thickness structure, the maximum thickness of the third thinned portion 2234 is smaller than the thickness of the third active active material layer.
  • the arrangement of the third thinned portion 2234 can cover part of the second current collector 2231 so that the second current collector 2231 is exposed as little as possible and reduces the isolation film 222 of the electrode assembly 22 from contacting the second current collector 2231 and being blocked by the second current collector.
  • the risk of short circuit caused by burrs on the surface of 2231 further improves the safety performance of the battery cells 20 and batteries 100 equipped with the electrode assembly 22 .
  • the third thinned portion 2234 can also have various forms of unequal thickness structures, as shown in Figures 23 and 24. In some embodiments, the thickness of the third thinned portion 2234 gradually decreases along the winding direction X. .
  • the surface of the third thinned portion 2234 facing away from the third surface 22311 is inclined along the winding direction X, so that the thickness of the third thinned portion 2234 gradually decreases along the winding direction X.
  • the material of the third thinned portion 2234 may be the same as that of the third active material layer 2232, or may be different. In some embodiments, the third thinned portion 2234 is an active material layer with the same polarity as the third active material layer 2232 .
  • the third active material layer 2232 is a positive electrode active material layer
  • the first thinned portion 2214 is also a positive electrode active material layer
  • the third active material layer 2232 is a negative electrode active material layer
  • the third thinned portion 2214 is also a positive electrode active material layer.
  • 2234 is also the negative active material layer.
  • the third thinned portion 2234 is an active material layer with the same polarity as the third active material layer 2232, which is beneficial to improving the energy density of the battery cell 20 and the battery 100 including the electrode assembly 22.
  • the expansion coefficient of the third thinned portion 2234 is smaller than the expansion coefficient of the third active material layer 2232 .
  • the expansion coefficient represents the degree to which the length, area, and volume of the third thinned portion 2234 and the third active material layer 2232 increase during the charge and discharge process. physical quantity.
  • the partial composition and composition ratio of the material of the third thinned portion 2234 can be changed to make the third thinned portion 2234 .
  • the expansion coefficient of the three thinned portions 2234 is smaller than the expansion coefficient of the third active material layer 2232 .
  • the expansion coefficient of the material of the third thinned part 2234 may be smaller than that of the third thinned part 2234.
  • the expansion coefficient of the third thinned portion 2234 is smaller than the expansion coefficient of the second active material layer 2213, and the third thinned portion 2234 is connected to the third ending end 22321, which can restrain the expansion of the third active material layer 2232 to a certain extent. , can reduce the expansion degree of the third active material layer 2232 during the charging and discharging process, thereby reducing the risk that the third active material layer 2232 expands too much and causes local strain to occur in the adjacent pole pieces, thereby slowing down the connection between the third terminal end 22321 and the third active material layer 2232.
  • the pole piece adjacent to the fourth end 22331 is cracked.
  • the third thinned portion 2234 extends from the third end end 22321 to the end end 22313 of the second current collector along the winding direction X.
  • the third thinned portion 2234 extends to the ending end 22313 of the second current collector.
  • the surface of the second current collector 2231 provided with the third active material layer 2232 is thinned by the third active material layer 2232 and the third The parts 2234 are jointly covered to reduce the risk that the burrs of the second current collector 2231 will puncture the isolation film 222 and cause a short circuit.
  • the third thinned portion 2234 may not extend from the third end 22321 to the end 22313 of the second current collector along the winding direction X. That is, the end 22313 of the second current collector extends along the winding direction The direction X extends beyond an end of the third thinned portion 2234 away from the third ending end 22321.
  • the second pole piece 223 further includes a fourth thinned portion 2235 , and the fourth thinned portion 2235 and the fourth active layer are disposed on the same surface of the second current collector 2231 .
  • the fourth thinned portion 2235 extends from the fourth ending end 22331 along the winding direction X; wherein the thickness of the fourth weakened portion is smaller than the thickness of the fourth active material layer 2233 .
  • the fourth thinned portion 2235 is connected to the fourth ending end 22331, and the fourth thinned portion 2235 is provided on the portion of the fourth surface 22312 that exceeds the second ending end 22131 along the winding direction X.
  • the structures of the fourth thinned portion 2235 and the third thinned portion 2234 may be the same or different.
  • the fourth thinned portion 2235 may be a constant thickness structure.
  • the fourth thinned portion 2235 may also have a non-uniform thickness structure. In an embodiment in which the fourth thinned portion 2235 has an unequal thickness structure, the maximum thickness of the fourth thinned portion 2235 is smaller than the thickness of the fourth active active material layer.
  • the arrangement of the fourth thinned portion 2235 can cover part of the second current collector 2231 so that the second current collector 2231 is exposed as little as possible and reduces the isolation film 222 of the electrode assembly 22 from contacting the second current collector 2231 and being blocked by the second current collector.
  • the risk of short circuit caused by burrs on the surface of 2231 further improves the safety performance of the battery cells 20 and batteries 100 equipped with the electrode assembly 22 .
  • the fourth thinned portion 2235 can also have various forms of unequal thickness structures, as shown in Figures 27 and 28. In some embodiments, the thickness of the fourth thinned portion 2235 gradually decreases along the winding direction X. .
  • the surface of the fourth thinned portion 2235 facing away from the fourth surface 22312 is inclined along the winding direction X, so that the thickness of the fourth thinned portion 2235 gradually decreases along the winding direction X.
  • the material of the fourth thinned portion 2235 may be the same as that of the fourth active material layer 2233, or may be different. In some embodiments, the fourth thinned portion 2235 is an active material layer with the same polarity as the fourth active material layer 2233 .
  • the fourth active material layer 2233 is a positive electrode active material layer
  • the fourth thinned portion 2235 is also a positive electrode active material layer
  • the fourth active material layer 2233 is a negative electrode active material layer
  • the fourth thinned portion 2235 is also a positive electrode active material layer. 2235 is also the negative active material layer.
  • the fourth thinned portion 2235 is an active material layer with the same polarity as the fourth active material layer 2233, which is beneficial to improving the energy density of the battery cell 20 and the battery 100 including the electrode assembly 22.
  • the expansion coefficient of the fourth thinned portion 2235 is smaller than the expansion coefficient of the fourth active material layer 2233 .
  • the expansion coefficient represents the degree to which the length, area, and volume of the fourth thinned portion 2235 and the fourth active material layer 2233 increase during the charge and discharge process. physical quantity.
  • the fourth thinned portion 2235 is an active material layer with the same polarity as the fourth active material layer 2233
  • the partial composition and composition ratio of the material of the fourth thinned portion 2235 can be changed to make the fourth thinned portion 2235
  • the expansion coefficient of the fourth thinned portion 2235 is smaller than the expansion coefficient of the fourth active material layer 2233 .
  • the expansion coefficient of the fourth thinned portion 2235 is smaller than the expansion coefficient of the fourth active material layer 2233, and the fourth thinned portion 2235 is connected to the fourth ending end 22331, which can restrain the expansion of the fourth active material layer 2233 to a certain extent. , can reduce the expansion degree of the fourth active material layer 2233 during the charging and discharging process, thereby reducing the risk that the fourth active material layer 2233 expands too much and causes local strain to occur in adjacent pole pieces, thereby slowing down the connection between the third terminal end 22321 and The pole piece adjacent to the fourth end 22331 is cracked.
  • the fourth thinned portion 2235 extends from the fourth ending end 22331 to the ending end 22313 of the second current collector along the winding direction X.
  • the fourth thinned portion 2235 extends to the ending end 22313 of the second current collector.
  • the surface of the second current collector 2231 provided with the fourth active material layer 2233 is thinned by the fourth active material layer 2233 and the fourth 2235 are jointly covered to reduce the risk that the burrs of the second current collector 2231 will puncture the isolation film 222 and cause a short circuit.
  • the fourth thinned portion 2235 may not extend from the fourth ending end 22331 to the ending end 22313 of the second current collector along the winding direction The direction X extends beyond an end of the fourth thinned portion 2235 away from the fourth ending end 22331.
  • the first pole piece 221 is a negative pole piece
  • the second pole piece 223 is a positive pole piece
  • the first ending end 22121 is located outside the first current collector 2211 and extends beyond the winding direction X.
  • the second ending end 22131 and the third ending end 22321 are located outside the second current collector 2231 and exceed the fourth ending end 22331 along the winding direction X; the second ending end 22131 exceeds the third ending end 22321 along the winding direction X.
  • the outside and the inside refer to the side farther away from the electrode assembly 22 in the direction perpendicular to the winding center of the electrode assembly 22 relative to the winding center of the electrode assembly 22 .
  • the inner side refers to the side closer to the electrode assembly 22 in a direction perpendicular to the winding center of the electrode assembly 22 .
  • “Outside of the first current collector 2211” refers to the side of the first current collector 2211 further away from the winding center of the electrode assembly 22 along its thickness direction.
  • the first surface 22111 of the first current collector 2211 If the second surface 22112 is further away from the winding center of the electrode assembly 22 , the side of the first surface 22111 is the outside of the first current collector 2211 , and the side of the second surface 22112 is the inside of the first current collector 2211 .
  • “Outside of the second current collector 2231” refers to the side of the second current collector 2231 that is further away from the winding center of the electrode assembly 22 along its thickness direction.
  • the third surface 22311 of the second current collector 2231 If the fourth surface 22312 is further away from the winding center of the electrode assembly 22 , the side of the third surface 22311 is the outside of the second current collector 2231 , and the side of the fourth surface 22312 is the inside of the second current collector 2231 .
  • first ending end 22121 and the second ending end 22131 are both located outside the third ending end 22321.
  • the second ending end 22131 exceeds the third ending end 22321 along the winding direction
  • the safety performance of the body 20 and the battery 100 is improved; it can also prevent the alignment of the second ending end 22131 and the second ending end 22131 to form a new step with a larger size, which may cause the adjacent pole pieces to be severely stressed locally and break.
  • the first pole piece 221 is a negative pole piece
  • the second pole piece 223 is a positive pole piece
  • the first ending end 22121 is located outside the first current collector 2211 and along the winding direction X
  • the fourth ending end 22331 is located inside the second current collector 2231 and extends beyond the third ending end 22321 along the winding direction X; the second ending end 22131 exceeds the third ending end along the winding direction X 22321.
  • first ending end 22121 and the second ending end 22131 are both located outside the third ending end 22321.
  • the second ending end 22131 exceeds the third ending end 22321 along the winding direction Breakage occurs, and the second active material layer 2213 can completely cover the third active material layer 2232, thereby reducing the risk of lithium deposition in the battery cell 20 and the battery 100 equipped with the electrode assembly 22, thereby improving the efficiency of the battery cell 20 and the battery. 100% safety performance.
  • L 3 can be 11mm, 13mm, 15mm, 17mm, 19mm, 21mm, 23mm, etc.
  • the distance L 3 between the second ending end 22131 and the third ending end 22321 satisfies L 3 ⁇ 10mm, which can avoid the alignment of the second ending end 22131 and the second ending end 22131 to form a new step with a larger size that causes adjacent The pole piece was partially stressed and broken.
  • An embodiment of the present application also provides a battery cell 20.
  • the battery cell 20 includes the electrode assembly 22 provided in any of the above embodiments.
  • the pole pieces of the electrode assembly 22 provided in any of the above embodiments are not easily cracked due to local strain of the pole piece.
  • the battery cell 20 includes the electrode assembly 22 and the isolation film 222 is punctured due to cracking of the pole pieces, thereby causing a short circuit risk. It is lower, so the safety of the battery cell 20 is better.
  • An embodiment of the present application also provides a battery 100.
  • the battery 100 includes a box 10 and the battery cells 20 provided in the above embodiments; the battery cells 20 are accommodated in the box 10.
  • the battery cell 20 in the above embodiment has a low risk of short circuit due to the cracking of the pole piece and the puncture of the isolation film 222, and the safety of the battery cell 20 is better. Therefore, the battery cell provided by the second embodiment has a low risk of short circuit. The safety of the battery 100 of the body 20 is also better.
  • An embodiment of the present application also provides an electrical device.
  • the electrical device includes the battery 100 provided in the above embodiment.
  • the battery 100 provides electrical energy for electrical equipment.
  • the battery 100 in the above embodiment has good safety, and the electrical equipment is powered by the battery 100 provided in the third embodiment, which can improve the safety of electricity consumption.
  • the embodiment of the present application provides a cylindrical electrode assembly 22.
  • the electrode assembly 22 includes a first pole piece 221, an isolation film 222 and a second pole piece 223.
  • the first pole piece 221 is a negative pole piece
  • the second pole piece 223 is a positive pole piece.
  • the isolation film 222 insulates and separates the first pole piece 221 and the second pole piece 223 .
  • the first pole piece 221 , the isolation film 222 and the second pole piece 223 are stacked and rolled to form a cylindrical wound electrode assembly 22 .
  • the first pole piece 221 includes a first current collector 2211, a first active material layer 2212 and a second active material layer 2213.
  • the first active material layer 2212 is disposed on the first surface 22111 of the first current collector 2211
  • the second active material layer 2213 is disposed on the second surface 22112 of the first current collector 2211 .
  • the first ending end 22121 of the first active material layer 2212 and the second ending end 22131 of the second active material layer 2213 are offset along the winding direction X.
  • the distance between the first ending end 22121 and the second ending end 22131 is L 1 , satisfying L 1 ⁇ 10 mm.
  • the first ending end 22121 is located outside the first current collector 2211
  • the second ending end 22131 is located inside the first current collector 2211.
  • the second pole piece 223 includes a second current collector 2231, a third active material layer 2232 and a fourth active material layer 2233.
  • the third active material layer 2232 is disposed on the third surface 22311 of the second current collector 2231
  • the fourth active material layer 2233 is disposed on the fourth surface 22312 of the second current collector 2231 .
  • the third ending end 22321 of the third active material layer 2232 and the fourth ending end 22331 of the fourth active material layer 2233 are offset along the winding direction X.
  • the distance between the third ending end 22321 and the fourth ending end 22331 is L 2 , satisfying L 2 ⁇ 10 mm.
  • the third ending end 22321 is located outside the second current collector 2231, and the fourth ending end 22331 is located inside the second current collector 2231.
  • the first ending end 22121 and the second ending end 22131 are both located outside the third ending end 22321.

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Abstract

一种电极组件（22）、电池单体（20）、电池（100）及用电设备。电极组件（22）包括第一极片（221），第一极片（221）包括第一集流体（2211）、第一活性物质层（2212）和第二活性物质层（2213），第一活性物质层（2212）和第二活性物质层（2213）分别设置于第一集流体（2211）相对的两个表面；第一活性物质层（2212）具有第一收尾端（22121），第二活性物质层（2213）具有第二收尾端（22131），沿电极组件（22）的卷绕方向，第一收尾端（22121）和第二收尾端（22131）错位设置，使得第一极片（221）在第一收尾端（22121）和第二收尾端（22131）之间形成厚度较小的区域，可以减小第一极片（221）的卷绕收尾区域的厚度，减小在电极组件（221）膨胀过程中第一极片（221）的卷绕收尾区域对相邻的极片的剪切应力，使得与第一极片（221）的卷绕收尾区域相邻的极片不容易发生局部应变，从而减缓与第一极片（221）的卷绕收尾区域相邻的极片发生开裂的问题。

Description

电极组件、电池单体、电池及用电设备 技术领域
本申请涉及电池技术领域，具体而言，涉及一种电极组件、电池单体、电池及用电设备。
背景技术
目前，二次电池具有体积小、能量密度高、功率密度高、循环使用次数多和存储时间长等优点。因此，广泛应用于便携式电子设备、电动交通工具、电动工具、无人机、储能设备等领域。而电池的安全问题是用户主要关注的问题之一，也是制约电池发展的主要因素之一。因此，如何提高电池的安全性能成为电池领域亟待解决的问题。
发明内容
本申本申请实施例提供一种电极组件、电池单体、电池及用电设备，以提高电池的安全性能。
第一方面，本申请实施例提供一种电极组件，所述电极组件为卷绕结构，所述电极组件包括第一极片，所述第一极片包括第一集流体、第一活性物质层和第二活性物质层，所述第一活性物质层和所述第二活性物质层分别设置于所述第一集流体相对的两个表面；其中，所述第一活性物质层具有第一收尾端，所述第二活性物质层具有第二收尾端，沿所述电极组件的卷绕方向，所述第一收尾端和所述第二收尾端错位设置。
上述技术方案中，设置于第一集流体的相对的两表面第一活性物质层的第一收尾端和第二活性物质层的第二收尾端沿电极组件的卷绕方向错位设置，使得第一极片在第一收尾端和第二收尾端之间形成厚度较小的区域，可以减小第一极片的卷绕收尾区域的厚度，减小在电极组件膨胀过程中第一极片的卷绕收尾区域对相邻的极片的剪切应力，使得与第一极片的卷绕收尾区域相邻的极片不容易局部应变，从而减缓第一极片的卷绕收尾区域使相邻的极片发生开裂的问题，进而降低因极片开裂导致隔离膜被刺破而引起短路风险的问题，从而提高具备该电极组件的电池单体和电池的安全性能。
在本申请第一方面的一些实施例中，沿所述卷绕方向，所述第一收尾端和所述第二收尾端之间的距离为L 1，满足L 1≥10mm。
上述技术方案中，第一收尾端和第二收尾端之间的距离为L 1，满足L 1≥10mm，以形成足够长度的厚度较小的第一极片的卷绕收尾区域，有利于使与第一收尾端和第二收尾端相邻极片不容易发生局部应变，减缓相邻极片发生开裂的问题。
在本申请第一方面的一些实施例中，所述第一极片还包括第一削薄部，所述第一削薄部和所述第一活性物层设置于所述第一集流体的同一表面，所述第一削薄部从所述第一收尾端沿所述卷绕方向延伸；其中，所述第一削弱部的厚度小于所述第一活性物质层的厚度。
上述技术方案中，第一削薄部的设置能够覆盖部分第一集流体，使得第一集流体尽可能少的裸露，降低电极组件的隔离膜与第一集流体接触而被第一集流体表面的毛刺刺破而导致短路的风险，进一步提高具备该电极组件的电池单体和电池的安全性能。
在本申请第一方面的一些实施例中，沿所述卷绕方向，所述第一削薄部的厚度逐渐减小。
上述技术方案中，沿卷绕方向，第一削薄部的厚度逐渐减小，即第一削薄部的厚度渐变，使得第一削薄部和第一活性物质层的连接位置不会厚度突变，降低使第一削薄部和第一活性物质层的连接位置使得相邻极片容易发生局部应变风险。
在本申请第一方面的一些实施例中，所述第一削薄部为与所述第一活性物质层的极性相同的活性物质层。
上述技术方案中，第一削薄部为与第一活性物质层的极性相同的活性物质层，有利于提高具备该电极组件的电池单体和电池的能量密度。
在本申请第一方面的一些实施例中，所述第一削薄部的膨胀系数小于所述第一活性物质层的膨胀系数。
上述技术方案中，第一削薄部的膨胀系数小于第一活性物质层的膨胀系数，且第一削薄部连接于第一收尾端，能够对第一活性物质层的膨胀有一定的束缚作用，能够减小充放电过程中第一活性物质层的膨胀程度，从而降低第一活性物质层膨胀过大导致与第一收尾端相邻极片容易发生局部应变的风险，从而减缓与第一收尾端和第二收尾端相邻的极片发生开裂的问题。
在本申请第一方面的一些实施例中，所述第一削薄部从所述第一收尾端沿所述卷绕方向延伸至所述第一集流体的收尾端。
上述技术方案中，第一削薄部延伸至第一集流体的收尾端，沿卷绕方向，第一集流体设有第一活性物质层的表面被第一活性物质层和第一削薄部覆盖，降低第一集流体的毛刺刺破隔离膜而导致短路的风险。
在本申请第一方面的一些实施例中，所述第一极片还包括第二削薄部，所述第二削薄部和所述第二活性物层设置于所述第一集流体的同一表面，所述第二削薄部从所述第二收尾端沿所述卷绕方向延伸；其中，所述第二削弱部的厚度小于所述第二活性物质层的厚度。
上述技术方案中，第二削薄部的设置能够覆盖部分第一集流体，使得第一集流体尽可能少的裸露，降低电极组件的隔离膜与第一集流体接触而被第一集流体表面的毛刺刺破而导致短路的风险，进一步提高具备该电极组件的电池单体和电池的安全性能。
在本申请第一方面的一些实施例中，沿所述卷绕方向，所述第二削薄部的厚度逐渐减小。
上述技术方案中，沿卷绕方向，第二削薄部的厚度逐渐减小，即第二削薄部的厚度渐变，使得第二削薄部和第二活性物质层的连接位置不会厚度突变，降低使第二削薄部和第二活性物质层的连接位置使得相邻极片容易发生局部应变风险。
在本申请第一方面的一些实施例中，所述第二削薄部为与所述第二活性物质层的极性相同的活性物质层。
上述技术方案中，第二削薄部为与第二活性物质层的极性相同的活性物质层，有利于提高具备该电极组件的电池单体和电池的能量密度。
在本申请第一方面的一些实施例中，所述第二削薄部的膨胀系数小于所述第二活性物质层的膨胀系数。
上述技术方案中，第二削薄部的膨胀系数小于第二活性物质层的膨胀系数，且第二削薄部连接于第二收尾端，能够对第二活性物质层的膨胀有一定的束缚作用，能够减小充放电过程中第二活性物质层的膨胀程度，从而降低第二活性物质层膨胀过大导致相邻极片容易发生局部应变的风险，从而减缓与第一收尾端和第二收尾端相邻的极片发生开裂的问题。
在本申请第一方面的一些实施例中，沿所述卷绕方向，所述第二削薄部从所述第二收尾端沿所述卷绕方向延伸至所述第一集流体的收尾端。
上述技术方案中，第二削薄部延伸至第一集流体的收尾端，沿卷绕方向，第一集流体设置有第二活性物质层的表面被第二活性物质层和第二削薄部共同覆盖，降低第一集流体的毛刺刺破隔离膜而导致短路的风险。
在本申请第一方面的一些实施例中，所述电极组件还包括隔离膜以及与所述第一极片层叠卷绕设置的第二极片，所述第二极片与所述第一极片极性相反，所述隔离膜夹设于所述第一极片与所述第二极片；所述第二极片包括第二集流体、第三活性物质层和第四活性物质层，所述第三活性物质层和所述第四活性物质层分别设置于所述第二集流体相对的两个表面；其中，所述第三活性物质层具有第三收尾端，所述第四活性物质层具有第四收尾端，沿所述卷绕方向，所述第一收尾端和所述第二收尾端错位设置。
上述技术方案中，设置于第二集流体的相对的两表面第三活性物质层的第三收尾端和第四活性物质层的第四收尾端沿电极组件的卷绕方向错位设置，使得第二极片在第三收尾端和第三收尾端之间形成厚度较小的区域，可以减小第二极片的卷绕收尾区域的厚度，减小在电极组件膨胀过程中第二极片的卷绕收尾区域对相邻的极片的剪切应力，使得与第二极片的卷绕收尾区域相邻的极片不容易局部应变，从而减缓第二极片的卷绕收尾区域使相邻的极片发生开裂的问题，进而降低因极片开裂导致隔离膜被刺破而引起短路风险的问题，从而提高具备该电极组件的电池单体和电池的安全性能。
在本申请第一方面的一些实施例中，沿所述卷绕方向，所述第三收尾端和所述第四收尾端之间的距离为L 2，满足L 2≥10mm。
上述技术方案中，第三收尾端和第四收尾端之间的距离为L 2，满足L 2≥10mm，以形成足够长度的厚度较小的第二极片的卷绕收尾区域，有利于使与第三收尾端和第四收尾端相邻极片不容易发生局部应变，减缓相邻极片发生开裂的问题。
在本申请第一方面的一些实施例中，所述第二极片还包括第三削薄部，所述第三削薄部和所述第三活性物层设置于所述第二集流体的同一表面，所述第三削薄部从所述第三收尾端沿所述卷绕方向延伸；其中，所述第三削弱部的厚度小于所述第三活性物质层的厚度。
上述技术方案中，第三削薄部的设置能够覆盖部分第二集流体，使得第二集流体尽可能少的裸露，降低电极组件的隔离膜与第二集流体接触而被第二集流体表面的毛刺刺破而导致短路的风险，进一步提高具备该电极组件的电池单体和电池的安全性能。
在本申请第一方面的一些实施例中，沿所述卷绕方向，所述第三削薄部的厚度逐渐减小。
上述技术方案中，沿卷绕方向，第三削薄部的厚度逐渐减小，即第三削薄部的厚度渐变，使得第三削薄部和第三活性物质层的连接位置不会厚度突变，降低使第三削薄部和第三活性物质层的连接位置使得相邻极片容易发生局部应变风险。
在本申请第一方面的一些实施例中，所述第三削薄部为与所述第三活性物质层的极性相同的活性物质层。
上述技术方案中，第三削薄部为与第三活性物质层的极性相同的活性物质层，有利于提高具备该电极组件的电池单体和电池的能量密度。
在本申请第一方面的一些实施例中，所述第三削薄部的膨胀系数小于所述第三活性物质层的膨胀系数。
上述技术方案中，第三削薄部的膨胀系数小于第二活性物质层的膨胀系数，且第三削薄部连接于第三收尾端，能够对第三活性物质层的膨胀有一定的束缚作用，能够减小充放电过程中第三活性物质层的膨胀程度，从而降低第三活性物质层膨胀过大导致相邻极片容易发生局部应变的风险，从而减缓与第三收尾端和第四收尾端相邻的极片发生开裂的问题。
在本申请第一方面的一些实施例中，沿所述卷绕方向，所述第三削薄部从所述第三收尾端沿所述卷绕方向延伸至所述第二集流体的收尾端。
上述技术方案中，第三削薄部延伸至第二集流体的收尾端，沿卷绕方向，第二集流体设有第三活性物质层的表面被第三活性物质层和第三削薄部共同覆盖，降低第二集流体的毛刺刺破隔离膜而导致短路的风险。
在本申请第一方面的一些实施例中，所述第二极片还包括第四削薄部，所述第四削薄部和所述第四活性物层设置于所述第二集流体的同一表面，所述第四削薄部从所述第四收尾端沿所述卷绕方向延伸；其中，所述第四削弱部的厚度小于所述第四活性物质层的厚度。
上述技术方案中，第四削薄部的设置能够覆盖部分第二集流体，使得第二集流体尽可能少的裸露，降低 电极组件的隔离膜与第二集流体接触而被第二集流体表面的毛刺刺破而导致短路的风险，进一步提高具备该电极组件的电池单体和电池的安全性能。
在本申请第一方面的一些实施例中，沿所述卷绕方向，所述第四削薄部的厚度逐渐减小。
上述技术方案中，沿卷绕方向，第四削薄部的厚度逐渐减小，即第四削薄部的厚度渐变，使得第四削薄部和第四活性物质层的连接位置不会厚度突变，降低使第四削薄部和第四活性物质层的连接位置使得相邻极片容易发生局部应变风险。
在本申请第一方面的一些实施例中，所述第四削薄部为与所述第四活性物质层的极性相同的活性物质层。
上述技术方案中，第四削薄部为与第四活性物质层的极性相同的活性物质层，有利于提高具备该电极组件的电池单体和电池的能量密度。
在本申请第一方面的一些实施例中，所述第四削薄部的膨胀系数小于所述第四活性物质层的膨胀系数。
上述技术方案中，第四削薄部的膨胀系数小于第四活性物质层的膨胀系数，且第四削薄部连接于第四收尾端，能够对第四活性物质层的膨胀有一定的束缚作用，能够减小充放电过程中第四活性物质层的膨胀程度，从而降低第四活性物质层膨胀过大导致相邻极片容易发生局部应变的风险，从而减缓与第三收尾端和第四收尾端相邻的极片发生开裂的问题。
在本申请第一方面的一些实施例中，沿所述卷绕方向，所述第四削薄部从所述第四收尾端沿所述卷绕方向延伸至所述第二集流体的收尾端。
上述技术方案中，第四削薄部延伸至第二集流体的收尾端，沿卷绕方向，第二集流体设有第四活性物质层的表面被第四活性物质层和第四削薄部共同覆盖，降低第二集流体的毛刺刺破隔离膜而导致短路的风险。
在本申请第一方面的一些实施例中，所述第一极片为负极片，所述第二极片为正极片，所述第一收尾端位于所述第一集流体的外侧并沿所述卷绕方向超出所述第二收尾端，所述第三收尾端位于所述第二集流体的外侧并沿所述卷绕方向超出所述第四收尾端；所述第二收尾端沿所述卷绕方向超出所述第三收尾端。
上述技术方案中，第二收尾端沿卷绕方向超出第三收尾端，使得第二活性物质层完全覆盖第三活性物质层，能够降低析锂的风险，从而提高具备该电极组件的电池单体和电池的安全性能；还能够避免第二收尾端和第二收尾端对齐形成新的尺寸较大的台阶而导致相邻的极片局部受力严重而发生断裂。
在本申请第一方面的一些实施例中，所述第一极片为负极片，所述第二极片为正极片，所述第一收尾端位于所述第一集流体的外侧并沿所述卷绕方向超出所述第二收尾端，所述第四收尾端位于所述第二集流体的内侧并沿所述卷绕方向超出所述第三收尾端；所述第二收尾端沿所述卷绕方向超出所述第三收尾端。
上述技术方案中，第二收尾端沿卷绕方向超出第三收尾端，能够避免第二收尾端和第二收尾端对齐形成新的尺寸较大台阶而导致相邻的极片局部受力严重而发生断裂，且还使得第二活性物质层能够完全覆盖第三活性物质层，从而降低具备该电极组件的电池单体和电池析锂的风险，进而提高电池单体和电池的安全性能。
在本申请第一方面的一些实施例中，沿所述卷绕方向，所述第二收尾端和所述第三收尾端之间的距离为L 3，满足L 3≥10mm。
上述技术方案中，第二收尾端和第三收尾端之间的距离L 3，满足L 3≥10mm，能够避免第二收尾端和第二收尾端对齐形成新的尺寸较大的台阶而导致相邻的极片局部受力严重而发生断裂。
第二方面，本申请实施例还提供一种电池单体，包括第一方面任一实施例提供的电极组件。
上述技术方案中，第一方面任一实施例提供的电极组件的极片不容易因极片局部应变而导致极片开裂，电池单体包括该电极组件因极片开裂导致隔离膜被刺破而引起短路风险较低，因此电池单体的安全性较好。
第三方面，本申请实施例提供一种电池，包括箱体和第二方面实施例提供的电池单体；所述电池单体容纳于所述箱体内。
上述技术方案中，第二方面实施例中的电池单体因极片开裂导致隔离膜被刺破而引起短路风险较低，电池单体的安全性较好，因此，具备该第二方面实施例提供的电池单体的电池的安全性也较好。
第四方面，本申请实施例提供一种用电设备，包括第三方面实施例提供的电池。
上述技术方案中，第三方面实施例中的电池安全性较好，用电设备通过第三方面实施例提供的电池供电，能够提高用电安全。
附图说明
为了更清楚地说明本申请实施例的技术方案，下面将对实施例中所需要使用的附图作简单地介绍，应当理解，以下附图仅示出了本申请的某些实施例，因此不应被看作是对范围的限定，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，还可以根据这些附图获得其他相关的附图。
图1为现有技术中的电极组件的结构示意图；
图2为本申请一些实施例提供的车辆的结构示意图；
图3为本申请一些实施例提供的电池的结构示意图；
图4为本申请一些实施例提供的电池单体的分解图；
图5为本申请一些实施例提供的电极组件的结构示意图；
图6为本申请另一些实施例提供的电极组件的结构示意图；
图7为本申请再一些实施例提供的电极组件的结构示意图；
图8为本申请又一些实施例提供的电极组件的结构示意图；
图9为本申请再又一些实施例提供的电极组件的结构示意图；
图10为图9中A处的放大图；
图11为本申请再另一些实施例提供的电极组件的结构示意图；
图12为图11中B处的放大图；
图13为本申请又再一些实施例提供的电极组件的结构示意图；
图14为图13中C中的放大图；
图15为本申请又另一些实施例提供的电极组件的结构示意图；
图16为图15中D中的放大图；
图17为本申请的一些实施例提供的电极组件的结构示意图；
图18为图17中E处的放大图；
图19为本申请的再一些实施例提供的电极组件的结构示意图；
图20为图19中F处的放大图；
图21为本申请又一些实施例提供的电极组件的结构示意图；
图22为图21中G处的放大图；
图23为本申请的另一些实施例提供的电极组件的结构示意图；
图24为图23中H处的放大图；
图25为本申请的再另一些实施例提供的电极组件的结构示意图；
图26为图25中J处的放大图；
图27为本申请的再又一些实施例提供的电极组件的结构示意图；
图28为图27中K处的放大图；
图29为本申请的再另一些实施例提供的电极组件的结构示意图；
图30为本申请的另再一些实施例提供的电极组件的结构示意图。
图标：1000-车辆；100-电池；10-箱体；11-第一部分；12-第二部分；20-电池单体；21-壳体；211-开口；22'、22-电极组件；221'、221-第一极片；2211'、2211-第一集流体；22111-第一表面；22112-第二表面；22113-第一集流体的收尾端；2212'、2212-第一活性物质层；22121'、22121-第一收尾端；2213'、2213-第二活性物质层；22131'、22131-第二收尾端；2214-第一削薄部；2215-第二削薄部；222'、222-隔离膜；223'、223-第二极片；2231'、2231-第二集流体；22311-第三表面；22312-第四表面；22313-第二集流体的收尾端；2232'、2232-第三活性物质层；22321'、22321-第三收尾端；2233'、2233-第四活性物质层；22331'、22331-第四收尾端；2234-第三削薄部；2235-第四削薄部；23-端盖；24-电极端子；200-控制器；300-马达；X-卷绕方向。
具体实施方式
为使本申请实施例的目的、技术方案和优点更加清楚，下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行清楚、完整地描述，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。通常在此处附图中描述和示出的本申请实施例的组件可以以各种不同的配置来布置和设计。
因此，以下对在附图中提供的本申请的实施例的详细描述并非旨在限制要求保护的本申请的范围，而是仅仅表示本申请的选定实施例。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。
需要说明的是，在不冲突的情况下，本申请中的实施例及实施例中的特征可以相互组合。
应注意到：相似的标号和字母在下面的附图中表示类似项，因此，一旦某一项在一个附图中被定义，则在随后的附图中不需要对其进行进一步定义和解释。
在本申请实施例的描述中，需要说明的是，指示方位或位置关系为基于附图所示的方位或位置关系，或者是该申请产品使用时惯常摆放的方位或位置关系，或者是本领域技术人员惯常理解的方位或位置关系，仅是为了便于描述本申请和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本申请的限制。此外，术语“第一”、“第二”、“第三”等仅用于区分描述，而不能理解为指示或暗示相对重要性。
目前，从市场形势的发展来看，动力电池的应用越加广泛。动力电池不仅被应用于水力、火力、风力和太阳能电站等储能电源系统，而且还被广泛应用于电动自行车、电动摩托车、电动汽车等电动交通工具，以及军事装备和航空航天等多个领域。随着动力电池应用领域的不断扩大，其市场的需求量也在不断地扩增。
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。
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，本申请实施例对此并不限定。电池单体可呈圆柱体、扁平体、长方体或其它形状等，本申请实施例对此也不限定。电池单体一般按封装的方式分成三种：柱形电池单体、方体方形电池单体和软包电池单体，本申请实施例对此也不限定。
电池单体包括电极组件，电极组件包括第一极片、第二极片和隔离膜，第一极片和第二极片极性相反，即第一极片和第二极片中的一者为正极片，另一者为负极片。隔离膜用于分隔第一极片和第二极片，以避免第一极片和第二极片接触短路。第一极片、第二极片和隔离膜可以层叠并卷绕形成卷绕形式的电极组件。第一极片、第二极片和隔离膜可以层叠设置形成叠片式电极组件。
电池技术的发展要同时考虑多方面的设计因素，例如，电池的能量密度、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能
发明人发现，如图1所示，对卷绕式的电极组件22'而言，第一极片221'包括第一集流体2211'、第一活性物质层2212'和第二活性物质层2213'，第一活性物质层2212'和第二活性物质层2213'分别设置于第一集流体2211'相对的两个表面，第一活性物质层2212'的第一收尾端22121'和第二活性物质层2213'的第二收尾端22131'在卷绕方向X上平齐，使得第一收尾端22121'和第二收尾端22131'共同形成尺寸较大的台阶，在电极组件22'膨胀过程中，第一收尾端22121'和第二收尾端22131'会对与之相邻的极片产生较大的剪应力，从而使得与第一收尾端22121'和第二收尾端22131'相邻的极片产生局部应变，从而使得相邻的极片被挤压断裂；第二极片223'包括第二集流体2231'、第三活性物质层2232'和第三活性物质层2232'，第三活性物质层2232'和第四活性物质层2233'分别设置于第二集流体2231'相对的两个表面，第三活性物质层2232'的第三收尾端22321'和第四活性物质层2233'的第四收尾端22331'在卷绕方向X上平齐，使得第三收尾端22321'和第四收尾端22331'共同形成尺寸较大的台阶，在电极组件22'膨胀过程中，第三收尾端22321'和第四收尾端22331'会对与之相邻的极片产生较大的剪应力，从而使得与第三收尾端22321'和第四收尾端22331'相邻的极片产生局部应变，从而使得相邻的极片被挤压断裂。示例性地，如图1所示，第一极片221'为负极片，第二极片223'为正极片，第一收尾端22121'和第二收尾端22131'均位于第三收尾端22321'和第四收尾端22331'的外侧，且第一收尾端22121'和第二收尾端22131'均沿卷绕方向X超出第三收尾端22321'和第四收尾端22331'，在电极组件22'膨胀时，第二收尾端22131'会对其内侧的极片(第一极片221')产生较大的剪应力，第三收尾端22321'会对其外侧的极片(第一极片221')产生较大的剪应力，第四收尾端22331'会对其内侧的极片(第一极片221')产生较大的剪应力，从而使得极片产生局部应变，进而使得相邻的极片被挤压开裂或者断裂。开裂或者断裂的极片会产生毛刺，容易刺破隔离膜222'而引起短路风险的问题，从而引发具备该电极组件22'的电池单体和电池的安全问题。
基于上述考虑，为了缓解极片因受到较大剪应力而被挤压开裂或者断裂，从而引发具备该电极组件的电池单体和电池的安全问题的问题，发明人经过深入研究，设计了一种电极组件，沿电极组件的卷绕方向，电极组件的第一极片的第一活性物质层的第一收尾端和第二活性物质层的第二收尾端错位设置。
设置于第一集流体的相对的两表面第一活性物质层的第一收尾端和第二活性物质层的第二收尾端沿电极组件的卷绕方向错位设置，使得第一极片在第一收尾端和第二收尾端之间形成厚度较小的区域，可以减小第一极片的卷绕收尾区域的厚度，减小在电极组件膨胀过程中第一极片的卷绕收尾区域对相邻的极片的剪切应力，使得与第一极片的卷绕收尾区域相邻的极片不容易局部应变，从而减缓第一极片的卷绕收尾区域使相邻的极片发生开裂的问题，进而降低因极片开裂导致隔离膜被刺破而引起短路风险的问题，从而提高具备该电极组件的电池单体和电池的安全性能。
本申请实施例公开的具备本申请实施例提供的电极组件的电池单体可以但不限用于车辆、船舶或飞行器等用电装置中，还可以使用具备本申请公开电极组件的电池单体、电池等组成该用电设备的电源系统，这样，有利于提高电池单体和电池的能量密度。
本申请实施例提供一种使用电池作为电源的用电设备，用电设备可以为但不限于手机、平板、笔记本电脑、电动玩具、电动工具、电瓶车、电动汽车、轮船、航天器等等。其中，电动玩具可以包括固定式或移动式的电动玩具，例如，游戏机、电动汽车玩具、电动轮船玩具和电动飞机玩具等等，航天器可以包括飞机、火箭、航天飞机和宇宙飞船等等。
以下实施例为了方便说明，以本申请一实施例的一种用电设备为车辆1000为例进行说明。
请参照图2，车辆1000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1000的内部设置有电池100，电池100可以设置在车辆1000的底部或头部或尾部。电池100可以用于车辆1000的供电，例如，电池100可以作为车辆1000的操作电源。车辆1000还可以包括控制器200和马达300，控制器200用来控制电池100为马达300供电，例如，用于车辆1000的启动、导航和行驶时的工作用电需求。
在本申请一些实施例中，电池100不仅可以作为车辆1000的操作电源，还可以作为车辆1000的驱动电源，代替或部分地代替燃油或天然气为车辆1000提供驱动动力。
请参照图3，电池100包括箱体10和电池单体20，电池单体20容纳于箱体10内。其中，箱体10用于为电池单体20提供容纳空间，箱体10可以采用多种结构。在一些实施例中，箱体10可以包括第一部分11和第二部分12，第一部分11与第二部分12相互盖合，第一部分11和第二部分12共同限定出用于容纳电池单体20的容纳空间。第二部分12可以为一端开口以形成容纳电池单体20的容纳腔的空心结构，第一部分11可以为板状结构，第一部分11盖合于第二部分12的开口侧，以使第一部分11与第二部分12共同限定出容纳空间；第一部分11和第二部分12也可以是均为一侧开口的以形成容纳电池单体20的容纳腔的空心结构，第一部分11的开口侧盖合于第二部分12的开口侧。当然，第一部分11和第二部分12形成的箱体10可以是多种形状，比如，圆柱体、长方体等。
在电池100中，电池单体20可以是多个，多个电池单体20之间可串联或并联或混联，混联是指多个电池单体20中既有串联又有并联。多个电池单体20之间可直接串联或并联或混联在一起，再将多个电池单体20构成的整体容纳于箱体10内；当然，电池100也可以是多个电池单体20先串联或并联或混联组成电池模块形式，多个电池模块再串联或并联或混联形成一个整体，并容纳于箱体10内。电池100还可以包括其他结构，例如，该电池100还可以包括汇流部件，用于实现多个电池单体20之间的电连接。
在一些实施例中，电池100还可以包括汇流部件(图未示出)，多个电池单体20之间可通过汇流部件实现电连接，以实现多个电池单体20的串联或并联或混联。
其中，每个电池单体20可以为二次电池或一次电池；还可以是锂硫电池、钠离子电池或镁离子电池，但不局限于此。电池单体20可扁平体、长方体或其它形状等。
请参照图4，电池单体20可以包括壳体21、电极组件22和端盖23。壳体21具有开口211，电极组件22容纳于壳体21内，端盖23用于封盖于开口211。
壳体21可以是多种形状，比如方形结构、圆柱结构等。电极组件22的轮廓可以根据壳体21的结构形状相适配。比如，若电极组件22为圆柱结构，壳体21可以为圆柱结构；若电极组件22为方形，则壳体21可以为方形。图4中示出了电极组件22和壳体21均为圆柱结构的情况。
壳体21的材质也可以是多种，比如，铜、铁、铝、不锈钢、铝合金等，本申请实施例对此不作特殊限制。
端盖23是指盖合于壳体21的开口211处以将电池单体20的内部环境隔绝于外部环境的部件。不限地，端盖23的形状可以与壳体21的形状相适应以配合壳体21。可选地，端盖23可以由具有一定硬度和强度的材质(如铝合金)制成，这样，端盖23在受挤压碰撞时就不易发生形变，使电池单体20能够具备更高的结构强度，安全性能也可以有所提高。端盖23用于封盖壳体21的开口211，以形成一密闭的安装空间(图未示出)，安装空间用于容纳电极组件22。安装空间还用于容纳电解质，例如电解液。
端盖23上还设有输出电极组件22的电能的电极端子24，电极端子24用于与电极组件22电连接，即电极端子24与电极组件22的极耳(图中未示出)电连接，比如，电极端子24与极耳通过集流构件(图中未示出)连接，以实现电极端子24与极耳的电连接。
需要说明的，壳体21的开口211可以是一个，也可以是两个。若壳体21的开口211为一个，端盖23也可以为一个，端盖23中则可设置两个电极端子24，两个电极端子24分别为正极电极端子和负极电极端子，正极电极端子和负极电极端子分别用于与电极组件22正极耳(图中未示出)和负极耳(图中未示出)电连接，端盖23中的两个电极端子24分别为正极电极端子和负极电极端。在端盖23为一个的实施例中，电极端子24绝缘设置于端盖23。电极组件22的正极耳和负极耳中的一者与端盖23上的电极端子24电连接，另一者可以与壳体21电连接。
若壳体21的开口211为两个，比如，两个开口211设置在壳体21相对的两侧，端盖23也可以为两个，两个端盖23分别盖合于21的两个开口211处。在这种情况下，可以是一个端盖23中的电极端子24为正极电极端子，用于与电极组件22的正极耳电连接；另一个端盖23中的电极端子24为负极电极端子，用于与电极组件22的负极片电连接。
端盖23的材质也可以是多种的，比如，铜、铁、铝、不锈钢、铝合金、塑胶等，本申请实施例对此不作特殊限制。
壳体21和端盖23可以是独立的部件，可以于壳体21上设置开口211，通过在开口211处使端盖23盖合开口211以形成电池单体20的内部环境。不限地，也可以使端盖23和壳体21一体化，具体地，端盖23和壳体21可以在其他部件入壳前先形成一个共同的连接面，当需要封装壳体21的内部时，再使端盖23盖合壳体21。
端盖23上还可以设置泄压机构(图中未示出)，泄压机构用于在电池单体20内部的压力或者温度达到阈值时泄放电池单体20内部的压力。泄压机构25可以采用诸如防爆阀、防爆片、气阀、泄压阀、安全阀、形成于端盖23上的薄弱部等的形式。
如图5、图6所示，电极组件22为卷绕结构，电极组件22包括第一极片221，第一极片221包括第一集流体2211、第一活性物质层2212和第二活性物质层2213，第一活性物质层2212和第二活性物质层2213分别设置于第一集流体2211相对的两个表面；其中，第一活性物质层2212具有第一收尾端22121，第二活性物质层2213具有第二收尾端22131，沿电极组件22的卷绕方向X，第一收尾端22121和第二收尾端22131错位设置。
第一活性物质层2212和第二活性物质层2213分别设置于第一集流体2211沿其厚度方向相对的两个表面，分别定义为第一表面22111和第二表面22112，第二表面22112相对第一表面22111更加靠近电极组件22的卷绕中心。第一活性物质层2212设置于第一表面22111，第二活性物质层2213设置于第二表面22112，换句话说，第二活性物质层2213设置于第一集流体2211的内侧，第一活性物质层2212设置于第一集流体2211的外侧。
第一收尾端22121是第一活性物质层2212沿卷绕方向X的末端，第二收尾端22131是第二活性物质层2213沿卷绕方向X的末端。“第一收尾端22121和第二收尾端22131错位设置”，是指沿卷绕方向X，第一收尾端22121和第二收尾端22131之间存在距离。
第一极片221可以是正极片，也可以是负极片。若第一极片221为正极片，则第一集流体2211为正极集流体，第一活性物质层2212和第二活性物质层2213均是正极活性物质层，以锂离子电池100为例，正极集流体的材料可以为铝，正极活性物质层可以为钴酸锂、磷酸铁锂、三元锂或锰酸锂等。若第一极片221为负极片，则第一集流体2211为负极集流体，第一活性物质层2212和第二活性物质层2213均是负极活性物质层，以锂离子电池100为例，正极集流体的材料可以为铜，负极活性物质层可以为碳或硅等。图5中示出了第一极片221为负极片的情况。图6中示出了第一极片221为正极片的情况。
设置于第一集流体2211的相对的两表面第一活性物质层2212的第一收尾端22121和第二活性物质层2213的第二收尾端22131沿电极组件22的卷绕方向X错位设置，使得第一极片221在第一收尾端22121和第二收尾端22131之间形成厚度较小的区域，可以减小第一极片221的卷绕收尾区域的厚度，减小在电极组件22膨胀过程中第一极片221的卷绕收尾区域对相邻的极片的剪切应力，使得与第一极片221的卷绕收尾区域相邻的极片不容易局部应变，从而减缓第一极片221的卷绕收尾区域使相邻的极片发生开裂的问题，进而降低因极片开裂导致隔离膜222被刺破而引起短路风险的问题，从而提高具备该电极组件22的电池单体20和电池100的安全性能。
请继续参照图5、图6，沿卷绕方向X，第一收尾端22121和第二收尾端22131之间的距离为L 1，满足L 1≥10mm。
L 1可以为11mm、12mm、13mm、15mm、16mm、18mm、20mm等。
第一收尾端22121和第二收尾端22131之间的距离为L 1，满足L 1≥10mm，以形成足够长度的厚度较小 的第一极片221的卷绕收尾区域，有利于使与第一收尾端22121和第二收尾端22131相邻极片不容易发生局部应变，减缓相邻极片发生开裂的问题。
由于第一收尾端22121和第二收尾端22131沿卷绕方向X错位设置，则沿卷绕方向X，第一收尾端22121和第二收尾端22131中的一者超出另一者，即沿卷绕方向X，第一收尾端22121和第二收尾端22131中的一者位于另一者的前方。图5中示出了第二收尾端22131沿卷绕方向X超出第一收尾端22121，即第二收尾端22131沿卷绕方向X位于第一收尾端22121的前方的情况。图6中示出了第一收尾端22121沿卷绕方向X超出第二收尾端22131，即第一收尾端22121沿卷绕方向X位于第二收尾端22131的前方的情况。
第一集流体2211具有收尾端，第一集流体的收尾端22113为第一集流体2211沿卷绕方向X的末端。如图5、图6所示，第一集流体的收尾端22113可以与第一收尾端22121和第二收尾端22131在前的一者平齐。如图7、图8所示，第一集流体的收尾端22113也可以沿卷绕方向X超出第一收尾端22121和第二收尾端22131在前的一者。
如图9、图10所示，在一些实施例中，第一极片221还包括第一削薄部2214，第一削薄部2214和第一活性物层设置于第一集流体2211的同一表面，第一削薄部2214从第一收尾端22121沿卷绕方向X延伸；其中，第一削弱部的厚度小于第一活性物质层2212的厚度。
第一削薄部2214连接于第一收尾端22121，第一削薄部2214设置于第一表面22111沿卷绕方向X超出第一收尾端22121的部分。
如图10所示，第一削薄部2214可以是等厚度结构。
在另一些实施例中，第一削薄部2214也可以非等厚度结构。在第一削薄部2214为非等厚度结构的实施例中，第一削薄部2214的最大厚度小于第一活性活性物质层的厚度。
第一削薄部2214的设置能够覆盖部分第一集流体2211，使得第一集流体2211尽可能少的裸露，降低电极组件22的隔离膜222与第一集流体2211接触而被第一集流体2211表面的毛刺刺破而导致短路的风险，进一步提高具备该电极组件22的电池单体20和电池100的安全性能。
第一削薄部2214也可以非等厚度结构的形式有多种，如图11、图12所示，沿卷绕方向X，第一削薄部2214的厚度逐渐减小。
第一削薄部2214的背离第一表面22111的方向的表面沿卷绕方向X倾斜，以使第一削薄部2214的厚度沿卷绕方向X逐渐减小。
沿卷绕方向X，第一削薄部2214的厚度逐渐减小，即第一削薄部2214的厚度渐变，使得第一削薄部2214和第一活性物质层2212的连接位置不会厚度突变，降低使第一削薄部2214和第一活性物质层2212的连接位置使得相邻极片容易发生局部应变风险。
第一削薄部2214的材质可以与第一活性物质层2212相同，也可以不相同。在一些实施例中，第一削薄部2214为与第一活性物质层2212的极性相同的活性物质层。
可以理解为，若第一活性物质层2212为正极活性物质层，则第一削薄部2214也为正极活性物质层，若第一活性物质层2212为负极活性物质层，则第一削薄部2214也为负极活性物质层。
第一削薄部2214为与第一活性物质层2212的极性相同的活性物质层，有利于提高具备该电极组件22的电池单体20和电池100的能量密度。
在一些实施例中，第一削薄部2214的膨胀系数小于第一活性物质层2212的膨胀系数。
膨胀系数是表征物体热膨胀性质的物理量，即表征物体受热时其长度、面积、体积增大程度的物理量。对第一削薄部2214和第一活性物质层2212而言，膨胀系数是表征在充放电过程中，第一削薄部2214和第一活性物质层2212的长度、面积、体积增大程度的物理量。
在第一削薄部2214为与第一活性物质层2212的极性相同的活性物质层的情况下，可以通过改变第一削薄部2214的材料的部分成分、成分比例等方式，以使第一削薄部2214的膨胀系数小于第一活性物质层2212的膨胀系数。
在第一削薄部2214的材质与第一活性物质层2212的材质不同的情况下，即第一削薄部2214的材质不是活性材质，第一削薄部2214的材质的膨胀系数可以小于第一活性物质层2212的膨胀系数。
第一削薄部2214的膨胀系数小于第一活性物质层2212的膨胀系数，且第一削薄部2214连接于第一收尾端22121，能够对第一活性物质层2212的膨胀有一定的束缚作用，能够减小充放电过程中第一活性物质层2212的膨胀程度，从而降低第一活性物质层2212膨胀过大导致与第一收尾端22121相邻极片容易发生局部应变的风险，从而减缓与第一收尾端22121和第二收尾端22131相邻的极片发生开裂的问题。
请继续参见图12，在一些实施例中，第一削薄部2214从第一收尾端22121沿卷绕方向X延伸至第一集流体的收尾端22113。
可以理解为，沿卷绕方向X，第一集流体的收尾端22113与第一削薄部2214背离第一收尾端22121的一端平齐。
第一削薄部2214延伸至第一集流体的收尾端22113，沿卷绕方向X，第一集流体2211设有第一活性物质层2212的表面被第一活性物质层2212和第一削薄部2214覆盖，降低第一集流体2211的毛刺刺破隔离膜222而导致短路的风险。
在另一些实施例中，第一削薄部2214从第一收尾端22121沿卷绕方向X也可以不延伸至第一集流体的收尾端22113，即第一集流体的收尾端22113沿卷绕方向X超出第一削薄部2214背离第一收尾端22121的一端。
如图13、图14所示，在一些实施例中，第一极片221还包括第二削薄部2215，第二削薄部2215和第二活性物层设置于第一集流体2211的同一表面，第二削薄部2215从第二收尾端22131沿卷绕方向X延伸；其中，第 二削弱部的厚度小第二活性物质层2213的厚度。
第二削薄部2215连接于第二收尾端22131，第二削薄部2215设置于第二表面22112沿卷绕方向X超出第二收尾端22131的部分。
如图14所示，第二削薄部2215可以是等厚度结构。
在另一些实施例中，第二削薄部2215也可以非等厚度结构。在第二削薄部2215为非等厚度结构的实施例中，第二削薄部2215的最大厚度小于第二活性活性物质层的厚度。
第二削薄部2215的设置能够覆盖部分第一集流体2211，使得第一集流体2211尽可能少的裸露，降低电极组件22的隔离膜222与第一集流体2211接触而被第一集流体2211表面的毛刺刺破而导致短路的风险，进一步提高具备该电极组件22的电池单体20和电池100的安全性能。
第二削薄部2215也可以非等厚度结构的形式有多种，如图15、图16所示，沿卷绕方向X，第二削薄部2215的厚度逐渐减小。
第二削薄部2215的背离第二表面22112的方向的表面沿卷绕方向X倾斜，以使第二削薄部2215的厚度沿卷绕方向X逐渐减小。
沿卷绕方向X，第二削薄部2215的厚度逐渐减小，即第二削薄部2215的厚度渐变，使得第二削薄部2215和第二活性物质层2213的连接位置不会厚度突变，降低使第二削薄部2215和第二活性物质层2213的连接位置使得相邻极片容易发生局部应变风险。
第二削薄部2215的材质可以与第二活性物质层2213相同，也可以不相同。在一些实施例中，第二削薄部2215为与第二活性物质层2213的极性相同的活性物质层。
可以理解为，若第二活性物质层2213为正极活性物质层，则第二削薄部2215也为正极活性物质层，若第二活性物质层2213为负极活性物质层，则第二削薄部2215也为负极活性物质层。
第二削薄部2215为与第二活性物质层2213的极性相同的活性物质层，有利于提高具备该电极组件22的电池单体20和电池100的能量密度。
在一些实施例中，第二削薄部2215的膨胀系数小于第二活性物质层2213的膨胀系数。
对第二削薄部2215和第二活性物质层2213而言，膨胀系数是表征在充放电过程中，第二削薄部2215和第二活性物质层2213的长度、面积、体积增大程度的物理量。
在第二削薄部2215为与第二活性物质层2213的极性相同的活性物质层的情况下，可以通过改变第二削薄部2215的材料的部分成分、成分比例等方式，以使第二削薄部2215的膨胀系数小于第二活性物质层2213的膨胀系数。
在第二削薄部2215的材质与第二活性物质层2213的材质不同的情况下，即第二削薄部2215的材质不是活性材质，第二削薄部2215的材质的膨胀系数可以小于第二活性物质层2213的膨胀系数。
第二削薄部2215的膨胀系数小于第二活性物质层2213的膨胀系数，且第二削薄部2215连接于第二收尾端22131，能够对第二活性物质层2213的膨胀有一定的束缚作用，能够减小充放电过程中第二活性物质层2213的膨胀程度，从而降低第二活性物质层2213膨胀过大导致相邻极片容易发生局部应变的风险，从而减缓与第一收尾端22121和第二收尾端22131相邻的极片发生开裂的问题。
如图16所示，在一些实施例中，沿卷绕方向X，第二削薄部2215从第二收尾端22131沿卷绕方向X延伸至第一集流体的收尾端22113。
可以理解为，沿卷绕方向X，第一集流体的收尾端22113与第二削薄部2215背离第二收尾端22131的一端平齐。
第二削薄部2215延伸至第一集流体的收尾端22113，沿卷绕方向X，第一集流体2211设置有第二活性物质层2213的表面被第二活性物质层2213和第二削薄部2215共同覆盖，降低第一集流体2211的毛刺刺破隔离膜222而导致短路的风险。
在另一些实施例中，第二削薄部2215从第二收尾端22131沿卷绕方向X也可以不延伸至第一集流体的收尾端22113，即第一集流体的收尾端22113沿卷绕方向X超出第二削薄部2215背离第二收尾端22131的一端。
如图17所示，在一些实施例中，电极组件22还包括隔离膜222以及与第一极片221层叠卷绕设置的第二极片223，第二极片223与第一极片221极性相反，隔离膜222夹设于第一极片221与第二极片223；第二极片223包括第二集流体2231、第三活性物质层2232和第四活性物质层2233，第三活性物质层2232和第四活性物质层2233分别设置于第二集流体2231相对的两个表面；其中，第三活性物质层2232具有第三收尾端22321，第四活性物质层2233具有第四收尾端22331，沿卷绕方向X，第一收尾端22121和第二收尾端22131错位设置。
第一极片221若为正极片，则第二极片223为负极片；若第一极片221为负极片，则第二极片223为正极片。隔离膜222层叠设置在第一极片221和第二极片223之间，以绝缘分隔第一极片221和第二极片223。隔离膜222的材质可以为PP(polypropylene，聚丙烯)或PE(polyethylene，聚乙烯)等。
第三活性物质层2232和第四活性物质层2233分别设置于第二集流体2231沿其厚度方向相对的两个表面，分别定义为第三表面22311和第四表面22312，第四表面22312相对第三表面22311更加靠近电极组件22的卷绕中心。第三活性物质层2232设置于第三表面22311，第四活性物质层2233设置于第四表面22312，换句话说，第四活性物质层2233设置于第二集流体2231的内侧，第三活性物质层2232设置于第二集流体2231的外侧。
第三收尾端22321是第三活性物质层2232沿卷绕方向X的末端，第四收尾端22331是第四活性物质层2233沿卷绕方向X的末端。“第三收尾端22321和第四收尾端22331错位设置”，是指沿卷绕方向X，第三收尾端22321和第四收尾端22331之间存在距离。
设置于第二集流体2231的相对的两表面第三活性物质层2232的第三收尾端22321和第四活性物质层 2233的第四收尾端22331沿电极组件22的卷绕方向X错位设置，使得第二极片223在第三收尾端22321和第三收尾端22321之间形成厚度较小的区域，可以减小第二极片223的卷绕收尾区域的厚度，减小在电极组件22膨胀过程中第二极片223的卷绕收尾区域对相邻的极片的剪切应力，使得与第二极片223的卷绕收尾区域相邻的极片不容易局部应变，从而减缓第二极片223的卷绕收尾区域使相邻的极片发生开裂的问题，进而降低因极片开裂导致隔离膜222被刺破而引起短路风险的问题，从而提高具备该电极组件22的电池单体20和电池100的安全性能。
在一些实施例中，沿卷绕方向X，第三收尾端22321和第四收尾端22331之间的距离为L 2，满足L 2≥10mm。
L 2可以为11mm、12mm、13mm、15mm、16mm、18mm、20mm等。
第三收尾端22321和第四收尾端22331之间的距离为L2，满足L2≥10mm，以形成足够长度的厚度较小的第二极片223的卷绕收尾区域，有利于使与第三收尾端22321和第四收尾端22331相邻极片不容易发生局部应变，减缓相邻极片发生开裂的问题。
由于第三收尾端22321和第四收尾端22331沿卷绕方向X错位设置，则沿卷绕方向X，第三收尾端22321和第四收尾端22331中的一者超出另一者，即沿卷绕方向X，第三收尾端22321和第四收尾端22331中的一者位于另一者的前方。图18中示出了第三收尾端22321沿卷绕方向X超出第四收尾端22331，即第三收尾端22321沿卷绕方向X位于第四收尾端22331的前方的情况。图19、图20中示出了第四收尾端22331沿卷绕方向X超出第三收尾端22321，即第四收尾端22331沿卷绕方向X位于第撒收尾端的前方的情况。
第二集流体2231具有收尾端，第二集流体的收尾端22313为第二集流体2231沿卷绕方向X的末端。第二集流体的收尾端22313可以与第三收尾端22321和第四收尾端22331在前的一者平齐。如图18、图20所示，第二集流体的收尾端22313也可以沿卷绕方向X超出第三收尾端22321和第四收尾端22331在前的一者。
在一些实施例中，所述第二极片223还包括第三削薄部2234，第三削薄部2234和第三活性物层设置于第二集流体2231的同一表面，第三削薄部2234从第三收尾端22321沿卷绕方向X延伸；其中，第三削弱部的厚度小于第三活性物质层2232的厚度。
第三削薄部2234连接于第三收尾端22321，第三削薄部2234设置于第三表面22311沿卷绕方向X超出第三收尾端22321的部分。
如图22所示，第三削薄部2234可以是等厚度结构。
在另一些实施例中，第三削薄部2234也可以非等厚度结构。在第三削薄部2234为非等厚度结构的实施例中，第三削薄部2234的最大厚度小于第三活性活性物质层的厚度。
第三削薄部2234的设置能够覆盖部分第二集流体2231，使得第二集流体2231尽可能少的裸露，降低电极组件22的隔离膜222与第二集流体2231接触而被第二集流体2231表面的毛刺刺破而导致短路的风险，进一步提高具备该电极组件22的电池单体20和电池100的安全性能。
第三削薄部2234也可以非等厚度结构的形式有多种，如图23、图24所示，在一些实施例中，沿卷绕方向X，第三削薄部2234的厚度逐渐减小。
第三削薄部2234的背离第三表面22311的方向的表面沿卷绕方向X倾斜，以使第三削薄部2234的厚度沿卷绕方向X逐渐减小。
沿卷绕方向X，第三削薄部2234的厚度逐渐减小，即第三削薄部2234的厚度渐变，使得第三削薄部2234和第三活性物质层2232的连接位置不会厚度突变，降低使第三削薄部2234和第三活性物质层2232的连接位置使得相邻极片容易发生局部应变风险。
第三削薄部2234的材质可以与第三活性物质层2232相同，也可以不相同。在一些实施例中，第三削薄部2234为与第三活性物质层2232的极性相同的活性物质层。
可以理解为，若第三活性物质层2232为正极活性物质层，则第一削薄部2214也为正极活性物质层，若第三活性物质层2232为负极活性物质层，则第三削薄部2234也为负极活性物质层。
第三削薄部2234为与第三活性物质层2232的极性相同的活性物质层，有利于提高具备该电极组件22的电池单体20和电池100的能量密度。
在一些实施例中，第三削薄部2234的膨胀系数小于第三活性物质层2232的膨胀系数。
对第三削薄部2234和第三活性物质层2232而言，膨胀系数是表征在充放电过程中，第三削薄部2234和第三活性物质层2232的长度、面积、体积增大程度的物理量。
在第三削薄部2234为与第三壁活性物质层的极性相同的活性物质层的情况下，可以通过改变第三削薄部2234的材料的部分成分、成分比例等方式，以使第三削薄部2234的膨胀系数小于第三活性物质层2232的膨胀系数。
在第三削薄部2234的材质与第三活性物质层2232的材质不同的情况下，即第三削薄部2234的材质不是活性材质，第三削薄部2234的材质的膨胀系数可以小于第三活性物质层2232的膨胀系数。
第三削薄部2234的膨胀系数小于第二活性物质层2213的膨胀系数，且第三削薄部2234连接于第三收尾端22321，能够对第三活性物质层2232的膨胀有一定的束缚作用，能够减小充放电过程中第三活性物质层2232的膨胀程度，从而降低第三活性物质层2232膨胀过大导致相邻极片容易发生局部应变的风险，从而减缓与第三收尾端22321和第四收尾端22331相邻的极片发生开裂的问题。
如图22、图24，在一些实施例中，沿卷绕方向X，第三削薄部2234从第三收尾端22321沿卷绕方向X延伸至第二集流体的收尾端22313。
可以理解为，沿卷绕方向X，第二集流体的收尾端22313与第三削薄部2234背离第三收尾端22321的一端平齐。
第三削薄部2234延伸至第二集流体的收尾端22313，沿卷绕方向X，第二集流体2231设有第三活性物质层2232的表面被第三活性物质层2232和第三削薄部2234共同覆盖，降低第二集流体2231的毛刺刺破隔离膜222而导致短路的风险。
在另一些实施例中，第三削薄部2234从第三收尾端22321沿卷绕方向X也可以不延伸至第二集流体的收尾端22313，即第二集流体的收尾端22313沿卷绕方向X超出第三削薄部2234背离第三收尾端22321的一端。
如图25、图26所示，在一些实施例中，第二极片223还包括第四削薄部2235，第四削薄部2235和第四活性物层设置于第二集流体2231的同一表面，第四削薄部2235从第四收尾端22331沿卷绕方向X延伸；其中，第四削弱部的厚度小于第四活性物质层2233的厚度。
第四削薄部2235连接于第四收尾端22331，第四削薄部2235设置于第四表面22312沿卷绕方向X超出第二收尾端22131的部分。第四削薄部2235和第三削薄部2234的结构可以相同，也可以不同。
如图26所示，第四削薄部2235可以是等厚度结构。
在另一些实施例中，第四削薄部2235也可以非等厚度结构。在第四削薄部2235为非等厚度结构的实施例中，第四削薄部2235的最大厚度小于第四活性活性物质层的厚度。
第四削薄部2235的设置能够覆盖部分第二集流体2231，使得第二集流体2231尽可能少的裸露，降低电极组件22的隔离膜222与第二集流体2231接触而被第二集流体2231表面的毛刺刺破而导致短路的风险，进一步提高具备该电极组件22的电池单体20和电池100的安全性能。
第四削薄部2235也可以非等厚度结构的形式有多种，如图27、图28所示，在一些实施例中，沿卷绕方向X，第四削薄部2235的厚度逐渐减小。
第四削薄部2235的背离第四表面22312的方向的表面沿卷绕方向X倾斜，以使第四削薄部2235的厚度沿卷绕方向X逐渐减小。
沿卷绕方向X，第四削薄部2235的厚度逐渐减小，即第四削薄部2235的厚度渐变，使得第四削薄部2235和第四活性物质层2233的连接位置不会厚度突变，降低使第四削薄部2235和第四活性物质层2233的连接位置使得相邻极片容易发生局部应变风险。
第四削薄部2235的材质可以与第四活性物质层2233相同，也可以不相同。在一些实施例中，第四削薄部2235为与第四活性物质层2233的极性相同的活性物质层。
可以理解为，若第四活性物质层2233为正极活性物质层，则第四削薄部2235也为正极活性物质层，若第四活性物质层2233为负极活性物质层，则第四削薄部2235也为负极活性物质层。
第四削薄部2235为与第四活性物质层2233的极性相同的活性物质层，有利于提高具备该电极组件22的电池单体20和电池100的能量密度。
在一些实施例中，第四削薄部2235的膨胀系数小于第四活性物质层2233的膨胀系数。
对第四削薄部2235和第四活性物质层2233而言，膨胀系数是表征在充放电过程中，第四削薄部2235和第四活性物质层2233的长度、面积、体积增大程度的物理量。
在第四削薄部2235为与第四活性物质层2233的极性相同的活性物质层的情况下，可以通过改变第四削薄部2235的材料的部分成分、成分比例等方式，以使第四削薄部2235的膨胀系数小于第四活性物质层2233的膨胀系数。
第四削薄部2235的膨胀系数小于第四活性物质层2233的膨胀系数，且第四削薄部2235连接于第四收尾端22331，能够对第四活性物质层2233的膨胀有一定的束缚作用，能够减小充放电过程中第四活性物质层2233的膨胀程度，从而降低第四活性物质层2233膨胀过大导致相邻极片容易发生局部应变的风险，从而减缓与第三收尾端22321和第四收尾端22331相邻的极片发生开裂的问题。
如图26、图28所示，在一些实施例中，沿卷绕方向X，第四削薄部2235从第四收尾端22331沿卷绕方向X延伸至第二集流体的收尾端22313。
可以理解为，沿卷绕方向X，第二集流体的收尾端22313与第四削薄部2235背离第四收尾端22331的一端平齐。
第四削薄部2235延伸至第二集流体的收尾端22313，沿卷绕方向X，第二集流体2231设有第四活性物质层2233的表面被第四活性物质层2233和第四削薄部2235共同覆盖，降低第二集流体2231的毛刺刺破隔离膜222而导致短路的风险。
在另一些实施例中，第四削薄部2235从第四收尾端22331沿卷绕方向X也可以不延伸至第二集流体的收尾端22313，即第二集流体的收尾端22313沿卷绕方向X超出第四削薄部2235背离第四收尾端22331的一端。
如图29所示，在一些实施例中，第一极片221为负极片，第二极片223为正极片，第一收尾端22121位于第一集流体2211的外侧并沿卷绕方向X超出第二收尾端22131，第三收尾端22321位于第二集流体2231的外侧并沿卷绕方向X超出第四收尾端22331；第二收尾端22131沿卷绕方向X超出所第三收尾端22321。
外侧和内侧是在垂直电极组件22的卷绕中心的方向上相对电极组件22的卷绕中心而言，外侧是指在垂直电极组件22的卷绕中心的方向上更加远离电极组件22的一侧，内侧是指在垂直电极组件22的卷绕中心的方向上更加靠近电极组件22的一侧。
“第一集流体2211的外侧”，是指第一集流体2211沿其厚度方向更加远离电极组件22的卷绕中心的一侧，在本实施例中，第一集流体2211的第一表面22111相对第二表面22112更加远离电极组件22的卷绕中心，则第一表面22111所在侧为第一集流体2211的外侧，第二表面22112所在侧为第一集流体2211的内侧。
“第二集流体2231的外侧”，是指第二集流体2231沿其厚度方向更加远离电极组件22的卷绕中心的一侧，在本实施例中，第二集流体2231的第三表面22311相对第四表面22312更加远离电极组件22的卷绕中心，则 第三表面22311所在侧为第二集流体2231的外侧，第四表面22312所在侧为第二集流体2231的内侧。
在本实施例中，第一收尾端22121和第二收尾端22131均位于第三收尾端22321的外侧。
第二收尾端22131沿卷绕方向X超出第三收尾端22321，使得第二活性物质层2213完全覆盖第三活性物质层2232，能够降低析锂的风险，从而提高具备该电极组件22的电池单体20和电池100的安全性能；还能够避免第二收尾端22131和第二收尾端22131对齐形成新的尺寸较大的台阶而导致相邻的极片局部受力严重而发生断裂。
如图30所示，在另一些实施例中，第一极片221为负极片，第二极片223为正极片，第一收尾端22121位于第一集流体2211的外侧并沿卷绕方向X超出第二收尾端22131，第四收尾端22331位于第二集流体2231的内侧并沿卷绕方向X超出所述第三收尾端22321；第二收尾端22131沿卷绕方向X超出第三收尾端22321。
在本实施例中，第一收尾端22121和第二收尾端22131均位于第三收尾端22321的外侧。
第二收尾端22131沿卷绕方向X超出第三收尾端22321，能够避免第二收尾端22131和第二收尾端22131对齐形成新的尺寸较大台阶而导致相邻的极片局部受力严重而发生断裂，且还使得第二活性物质层2213能够完全覆盖第三活性物质层2232，从而降低具备该电极组件22的电池单体20和电池100析锂的风险，进而提高电池单体20和电池100的安全性能。
请继续参照图29、图30，沿卷绕方向X，第二收尾端22131和第三收尾端22321之间的距离为L 3，满足L 3≥10mm。
L 3可以为11mm、13mm、15mm、17mm、19mm、21mm、23mm等。
第二收尾端22131和第三收尾端22321之间的距离L 3，满足L 3≥10mm，能够避免第二收尾端22131和第二收尾端22131对齐形成新的尺寸较大的台阶而导致相邻的极片局部受力严重而发生断裂。
本申请实施例还提供一种电池单体20，电池单体20包括上述任一实施例提供的电极组件22。
上述任一实施例提供的电极组件22的极片不容易因极片局部应变而导致极片开裂，电池单体20包括该电极组件22因极片开裂导致隔离膜222被刺破而引起短路风险较低，因此电池单体20的安全性较好。
本申请实施例还提供一种电池100，电池100包括箱体10和上述实施例提供的电池单体20；电池单体20容纳于箱体10内。
上述实施例中的电池单体20因极片开裂导致隔离膜222被刺破而引起短路风险较低，电池单体20的安全性较好，因此，具备该第二方面实施例提供的电池单体20的电池100的安全性也较好。
本申请实施例还提供一种用电设备，用电设备包括上述实施例提供的电池100。
电池100为用电设备提供电能。上述实施例中的电池100安全性较好，用电设备通过第三方面实施例提供的电池100供电，能够提高用电安全。
本申请实施例提供一种圆柱形电极组件22，该电极组件22包括第一极片221、隔离膜222和第二极片223。第一极片221为负极片，第二极片223为正极片。隔离膜222绝缘分隔第一极片221和第二极片223。第一极片221、隔离膜222和第二极片223层叠并卷绕形成圆柱形的卷绕式的电极组件22。
第一极片221包括第一集流体2211、第一活性物质层2212和第二活性物质层2213。第一活性物质层2212设置与第一集流体2211的第一表面22111，第二活性物质层2213设置与第一集流体2211的第二表面22112。第一活性物质层2212的第一收尾端22121和第二活性物质层2213的第二收尾端22131沿卷绕方向X错位设置。沿卷绕方向X，第一收尾端22121和第二收尾端22131的之间的距离为L 1，满足L 1≥10mm。第一收尾端22121位于第一集流体2211的外侧，第二收尾端22131位于第一集流体2211的内侧。
第二极片223包括第二集流体2231、第三活性物质层2232和第四活性物质层2233。第三活性物质层2232设置与第二集流体2231的第三表面22311，第四活性物质层2233设置与第二集流体2231的第四表面22312。第三活性物质层2232的第三收尾端22321和第四活性物质层2233的第四收尾端22331沿卷绕方向X错位设置。沿卷绕方向X，第三收尾端22321和第四收尾端22331的之间的距离为L 2，满足L 2≥10mm。
第三收尾端22321位于第二集流体2231的外侧，第四收尾端22331位于第二集流体2231的内侧。第一收尾端22121和第二收尾端22131均位于第三收尾端22321的外侧。沿卷绕方向X，第二收尾端22131超出第三收尾端22321，第二收尾端22131和第三收尾端22321的之间的距离为L 3，满足L 3≥10mm。
以上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 (30)

  1. 一种电极组件，所述电极组件为卷绕结构，所述电极组件包括第一极片，所述第一极片包括第一集流体、第一活性物质层和第二活性物质层，所述第一活性物质层和所述第二活性物质层分别设置于所述第一集流体相对的两个表面；
    其中，所述第一活性物质层具有第一收尾端，所述第二活性物质层具有第二收尾端，沿所述电极组件的卷绕方向，所述第一收尾端和所述第二收尾端错位设置。
  2. 根据权利要求1所述的电极组件，其中，沿所述卷绕方向，所述第一收尾端和所述第二收尾端之间的距离为L 1，满足L 1≥10mm。
  3. 根据权利要求1或2所述的电极组件，其中，所述第一极片还包括第一削薄部，所述第一削薄部和所述第一活性物层设置于所述第一集流体的同一表面，所述第一削薄部从所述第一收尾端沿所述卷绕方向延伸；
    其中，所述第一削弱部的厚度小于所述第一活性物质层的厚度。
  4. 根据权利要求3所述的电极组件，其中，沿所述卷绕方向，所述第一削薄部的厚度逐渐减小。
  5. 根据权利要求3或4所述的电极组件，其中，所述第一削薄部为与所述第一活性物质层的极性相同的活性物质层。
  6. 根据权利要求3-5任一项所述的电极组件，其中，所述第一削薄部的膨胀系数小于所述第一活性物质层的膨胀系数。
  7. 根据权利要求3-6任一项所述的电极组件，其中，所述第一削薄部从所述第一收尾端沿所述卷绕方向延伸至所述第一集流体的收尾端。
  8. 根据权利要求3-7任一项所述的电极组件，其中，所述第一极片还包括第二削薄部，所述第二削薄部和所述第二活性物层设置于所述第一集流体的同一表面，所述第二削薄部从所述第二收尾端沿所述卷绕方向延伸；
    其中，所述第二削弱部的厚度小于所述第二活性物质层的厚度。
  9. 根据权利要求8所述的电极组件，其中，沿所述卷绕方向，所述第二削薄部的厚度逐渐减小。
  10. 根据权利要求8或9所述的电极组件，其中，所述第二削薄部为与所述第二活性物质层的极性相同的活性物质层。
  11. 根据权利要求8-10任一项所述的电极组件，其中，所述第二削薄部的膨胀系数小于所述第二活性物质层的膨胀系数。
  12. 根据权利要求8-11任一项所述的电极组件，其中，沿所述卷绕方向，所述第二削薄部从所述第二收尾端沿所述卷绕方向延伸至所述第一集流体的收尾端。
  13. 根据权利要求1-12任一项所述的电极组件，其中，所述电极组件还包括隔离膜以及与所述第一极片层叠卷绕设置的第二极片，所述第二极片与所述第一极片极性相反，所述隔离膜夹设于所述第一极片与所述第二极片；
    所述第二极片包括第二集流体、第三活性物质层和第四活性物质层，所述第三活性物质层和所述第四活性物质层分别设置于所述第二集流体相对的两个表面；
    其中，所述第三活性物质层具有第三收尾端，所述第四活性物质层具有第四收尾端，沿所述卷绕方向，所述第一收尾端和所述第二收尾端错位设置。
  14. 根据权利要求13所述的电极组件，其中，沿所述卷绕方向，所述第三收尾端和所述第四收尾端之间的距离为L 2，满足L 2≥10mm。
  15. 根据权利要求13或14所述的电极组件，其中，所述第二极片还包括第三削薄部，所述第三削薄部和所述第三活性物层设置于所述第二集流体的同一表面，所述第三削薄部从所述第三收尾端沿所述卷绕方向延伸；
    其中，所述第三削弱部的厚度小于所述第三活性物质层的厚度。
  16. 根据权利要求15所述的电极组件，其中，沿所述卷绕方向，所述第三削薄部的厚度逐渐减小。
  17. 根据权利要求15或16所述的电极组件，其中，所述第三削薄部为与所述第三活性物质层的极性相同的活性物质层。
  18. 根据权利要求15-17任一项所述的电极组件，其中，所述第三削薄部的膨胀系数小于所述第三活性物质层的膨胀系数。
  19. 根据权利要求15-18任一项所述的电极组件，其中，沿所述卷绕方向，所述第三削薄部从所述第三收尾端沿所述卷绕方向延伸至所述第二集流体的收尾端。
  20. 根据权利要求15-19任一项所述的电极组件，其中，所述第二极片还包括第四削薄部，所述第四削薄部和所述第四活性物层设置于所述第二集流体的同一表面，所述第四削薄部从所述第四收尾端沿所述卷绕方向延伸；
    其中，所述第四削弱部的厚度小于所述第四活性物质层的厚度。
  21. 根据权利要求20所述的电极组件，其中，沿所述卷绕方向，所述第四削薄部的厚度逐渐减小。
  22. 根据权利要求20或21所述的电极组件，其中，所述第四削薄部为与所述第四活性物质层的极性相同的活性物质层。
  23. 根据权利要求20-22任一项所述的电极组件，其中，所述第四削薄部的膨胀系数小于所述第四活性物质层的膨胀系数。
  24. 根据权利要求20-23任一项所述的电极组件，其中，沿所述卷绕方向，所述第四削薄部从所述第四收尾端沿所述卷绕方向延伸至所述第二集流体的收尾端。
  25. 根据权利要求13-24任一项所述的电极组件，其中，所述第一极片为负极片，所述第二极片为正极片，所述第一收尾端位于所述第一集流体的外侧并沿所述卷绕方向超出所述第二收尾端，所述第三收尾端位于所述第二集流体的外侧并沿所述卷绕方向超出所述第四收尾端；
    所述第二收尾端沿所述卷绕方向超出所述第三收尾端。
  26. 根据权利要求13-24任一项所述的电极组件，其中，所述第一极片为负极片，所述第二极片为正极片，所述第一收尾端位于所述第一集流体的外侧并沿所述卷绕方向超出所述第二收尾端，所述第四收尾端位于所述第二集流体的内侧并沿所述卷绕方向超出所述第三收尾端；
    所述第二收尾端沿所述卷绕方向超出所述第三收尾端。
  27. 根据权利要求25或26所述的电极组件，其中，沿所述卷绕方向，所述第二收尾端和所述第三收尾端之间的距离为L 3，满足L 3≥10mm。
  28. 一种电池单体，包括如权利要求1-27任一项所述的电极组件。
  29. 一种电池，包括：
    箱体；以及
    如权利要求28所述的电池单体，所述电池单体容纳于所述箱体内。
  30. 一种用电设备，包括如权利要求29所述的电池。
PCT/CN2022/110921 2022-08-08 2022-08-08 电极组件、电池单体、电池及用电设备 WO2024031256A1 (zh)

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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002063939A (ja) * 2000-06-09 2002-02-28 Gs-Melcotec Co Ltd 非水電解質電池及びその製造方法
CN201584463U (zh) * 2010-02-25 2010-09-15 惠州亿纬锂能股份有限公司 一种提高电池容量的卷绕结构
CN202495549U (zh) * 2012-03-31 2012-10-17 宁德新能源科技有限公司 圆柱形锂离子电池的电芯
CN212517286U (zh) * 2020-07-23 2021-02-09 珠海冠宇电池股份有限公司 卷芯、电池以及电子产品
CN214203736U (zh) * 2021-02-08 2021-09-14 宁德新能源科技有限公司 电池
CN216354456U (zh) * 2021-10-25 2022-04-19 宁德时代新能源科技股份有限公司 一种电池单体、电池及用电装置
CN114613942A (zh) * 2022-03-30 2022-06-10 湖北亿纬动力有限公司 一种含硅负极极片及含有其的锂离子电池

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002063939A (ja) * 2000-06-09 2002-02-28 Gs-Melcotec Co Ltd 非水電解質電池及びその製造方法
CN201584463U (zh) * 2010-02-25 2010-09-15 惠州亿纬锂能股份有限公司 一种提高电池容量的卷绕结构
CN202495549U (zh) * 2012-03-31 2012-10-17 宁德新能源科技有限公司 圆柱形锂离子电池的电芯
CN212517286U (zh) * 2020-07-23 2021-02-09 珠海冠宇电池股份有限公司 卷芯、电池以及电子产品
CN214203736U (zh) * 2021-02-08 2021-09-14 宁德新能源科技有限公司 电池
CN216354456U (zh) * 2021-10-25 2022-04-19 宁德时代新能源科技股份有限公司 一种电池单体、电池及用电装置
CN114613942A (zh) * 2022-03-30 2022-06-10 湖北亿纬动力有限公司 一种含硅负极极片及含有其的锂离子电池

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