WO2024077602A1 - 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
WO2024077602A1
WO2024077602A1 PCT/CN2022/125414 CN2022125414W WO2024077602A1 WO 2024077602 A1 WO2024077602 A1 WO 2024077602A1 CN 2022125414 W CN2022125414 W CN 2022125414W WO 2024077602 A1 WO2024077602 A1 WO 2024077602A1
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WIPO (PCT)
Prior art keywords
winding structure
pole piece
electrode assembly
sided adhesive
diaphragm
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PCT/CN2022/125414
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English (en)
French (fr)
Inventor
曹丹
柴志生
谷慧
Original Assignee
宁德时代新能源科技股份有限公司
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Priority to PCT/CN2022/125414 priority Critical patent/WO2024077602A1/zh
Publication of WO2024077602A1 publication Critical patent/WO2024077602A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators

Definitions

  • the present disclosure relates to the field of battery technology, and in particular to an electrode assembly, a battery cell, a battery and an electrical device.
  • Secondary batteries especially lithium-ion batteries, have the advantages of high voltage, high specific energy, long cycle life, green and pollution-free, wide operating temperature range and low self-discharge. They are widely used in portable electronic devices and power equipment of large new energy electric vehicles, and are of great significance to solving human environmental pollution and energy crisis. With the widespread application of secondary batteries, the reliability of battery use has become a problem that users pay close attention to.
  • an electrode assembly comprising: a first pole piece, a second pole piece, and a separator disposed between the first pole piece and the second pole piece, wherein the first pole piece, the second pole piece, and the separator are wound along a winding direction to form a winding structure;
  • At least one of the first pole piece and the second pole piece is provided with a flexible interlayer between an end region at at least one end in the winding direction and a diaphragm segment adjacent to the end region on the diaphragm, and the flexible interlayer protrudes from the edge of the end region in the circumferential direction of the winding structure.
  • the more concentrated shear stress formed by the step can be dispersed through the flexible partition, thereby reducing the risk of the electrode sheet being broken by the shear force, thereby improving the reliability of the electrode assembly.
  • one of the end region and the diaphragm segment is bonded to the flexible barrier layer, and the other of the end region and the diaphragm segment is in slidable contact with the flexible barrier layer.
  • one of the end region and the diaphragm segment is relatively fixed to the flexible interlayer so that the flexible interlayer can be maintained in the area where the step is located, thereby ensuring the effective dispersion of shear stress; by making the other of the end region and the diaphragm segment slidably contact with the flexible interlayer, the phenomenon of wrinkling of the diaphragm caused by the end region, the diaphragm segment and the flexible interlayer being bonded together is avoided.
  • the flexible barrier layer includes at least one single-sided adhesive tape.
  • the adhesive effect is achieved via the adhesive surface of the single-sided adhesive tape, and the sliding contact with the surface of the end region or the diaphragm segment is achieved via the non-adhesive surface.
  • the diaphragm segment comprises:
  • the flexible barrier layer includes a first single-sided adhesive tape bonded to one of the first diaphragm segment and the second diaphragm segment.
  • a first single-sided adhesive tape bonded to the side diaphragm segment is provided on one side of the end region.
  • the first single-sided adhesive tape can disperse the shear stress of the end region of the pole piece on the inner or outer side of the pole piece, and can also separate the burrs at the cut portion of the end region from the side diaphragm segment to avoid the risk of the burrs piercing the diaphragm segment and causing a short circuit with the other polarity pole piece.
  • the diaphragm segment comprises:
  • the flexible barrier layer includes a first single-sided adhesive tape and a second single-sided adhesive tape respectively bonded to the first diaphragm segment and the second diaphragm segment, and a protruding length of the first single-sided adhesive tape relative to the edge of the end area in the circumferential direction of the winding structure is the same as or different from a protruding length of the second single-sided adhesive tape relative to the edge of the end area in the circumferential direction of the winding structure.
  • the shear stress dispersion effect on both sides of the end region can be achieved through the first single-sided adhesive tape and the second single-sided adhesive tape, and the burrs at the cut-off part of the end region are effectively separated from the first diaphragm segment and the second diaphragm segment, thereby reducing the risk of the burrs piercing the diaphragm segment and causing a short circuit with the other polarity pole piece.
  • the shear stress dispersion effect on both sides of the end region can be made more uniform.
  • the protruding part of the first single-sided adhesive tape, the end area and the protruding part of the second single-sided adhesive tape can form a step with a gradual thickness.
  • Such a step can effectively reduce the shear stress, and combined with the flexibility of the first single-sided adhesive tape and the second single-sided adhesive tape, the risk of the pole piece being broken by the shear force can be more effectively reduced.
  • the flexible barrier layer includes a first single-sided adhesive tape, and the first single-sided adhesive tape is bonded to both the inner surface and the outer surface of the end region by folding.
  • Two relative bonding surfaces and two opposite non-bonding surfaces are formed by folding the first single-sided adhesive tape.
  • the two bonding surfaces are respectively bonded to the inner surface and the outer surface of the end area, and the two non-bonding surfaces are used to achieve sliding contact with the diaphragm segments on both sides inside and outside the end area.
  • the folded area is also used to seal the cut part of the end area to avoid burrs at the cut part piercing or scratching the diaphragm, causing the risk of overlapping short circuit.
  • the flexible barrier layer includes a first single-sided adhesive tape and a second single-sided adhesive tape respectively bonded to the inner surface and the outer surface of the end region, and a protruding length of the first single-sided adhesive tape relative to the edge of the end region in the circumferential direction of the winding structure is the same as or different from a protruding length of the second single-sided adhesive tape relative to the edge of the end region in the circumferential direction of the winding structure.
  • the inner and outer surfaces of the end region are bonded by the first and second single-sided adhesive tapes with opposite bonding surfaces, and the cut portion of the end region is sealed by bonding the protruding segments of the first and second single-sided adhesive tapes with the same or different protruding lengths relative to the edge of the end region, thereby preventing the burrs at the cut portion from piercing or scratching the diaphragm and causing the risk of overlapping short circuits.
  • the process difficulty of this bonding method of the first and second single-sided adhesive tapes is relatively small.
  • the first pole piece is a negative pole piece
  • the second pole piece is a positive pole piece
  • the pole piece layer where the first end of the first pole piece in the winding direction is located is located on the outside of the pole piece layer where the second end of the second pole piece in the winding direction is located, and the first end protrudes relative to the second end in the circumferential direction of the winding structure
  • a flexible partition layer is provided between the end region of the pole piece layer where the first end is located and the diaphragm segment adjacent to the end region of the pole piece layer where the first end is located on the diaphragm
  • a flexible partition layer is provided between the end region of the pole piece layer where the second end is located and the diaphragm segment adjacent to the end region of the pole piece layer where the second end is located on the diaphragm.
  • the outermost negative electrode sheet can wrap the outermost positive electrode sheet to ensure that the negative electrode sheet has sufficient lithium insertion space, thereby reducing the possibility of lithium precipitation of the outermost negative electrode sheet.
  • the shear stress of the steps formed by the first and second ends on the electrode sheet can be dispersed during the cycle of the electrode assembly, reducing the risk of the electrode sheet being broken by the shear force, thereby improving the reliability of the electrode assembly; and for the second end, the flexible separator can separate the burrs at the cut-off part of its end area from the diaphragm to prevent the burrs from piercing the diaphragm and short-circuiting with the negative electrode sheet.
  • the pole piece layer where the first starting end of the first pole piece in the winding direction is located is located on the inner side of the pole piece layer where the second starting end of the second pole piece in the winding direction is located, and the first starting end protrudes relative to the second starting end in the circumferential direction of the winding structure, and a flexible partition layer is provided between the end region of the pole piece layer where the second starting end is located and the diaphragm segment adjacent to the end region of the pole piece layer where the second starting end is located.
  • the electrode layer where the first starting end of the first electrode sheet is located on the inner side of the electrode layer where the second starting end of the second electrode sheet is located, and making the first starting end protrude relative to the second starting end in the circumferential direction it is ensured that the negative electrode sheet has sufficient lithium embedding space, thereby reducing the possibility of lithium precipitation in the innermost negative electrode sheet.
  • the shear stress of the step formed at the second starting end on the electrode sheet can be dispersed during the cycle of the electrode assembly, reducing the risk of the electrode sheet being broken by the shear force, thereby improving the reliability of the electrode assembly.
  • the negative electrode sheet here can be wound empty for several turns, so that there is no need to set a flexible partition layer at the first starting end, and there is no need to worry that the burrs at the cut-off part of the end area of the first starting end will pierce the diaphragm and overlap with the positive electrode sheet for short circuit.
  • At least one of the first pole piece and the second pole piece comprises:
  • An active material layer is provided at least on the surface of the current collector substrate adjacent to the separator;
  • a surface portion of at least one end of the current collector substrate corresponding to the end region is not covered by the active material layer.
  • the step height of the end area can be reduced, thereby reducing the shear stress caused by the step during cyclic expansion of the electrode assembly, thereby reducing the risk of the electrode sheet being broken by the shear force, and further improving the reliability of the electrode assembly.
  • the winding structure is a cylindrical winding structure, and the length L of the flexible barrier in the winding direction satisfies:
  • D is the diameter of the cylindrical winding structure.
  • the bonding and fixation between the flexible partition and the electrode sheet or diaphragm can be reliable, reducing the difficulty of setting up the flexible partition, and also reducing the obstruction of the flexible partition to the lithium ion diffusion channel, thereby reducing its impact on the performance of the electrode assembly.
  • the length L satisfies: 0.07 ⁇ *D ⁇ L ⁇ 0.13 ⁇ *D.
  • the bonding and fixation between the flexible partition and the electrode sheet or diaphragm can be made more reliable, further reducing the difficulty of setting the flexible partition, and can also effectively reduce the obstruction of the flexible partition to the lithium ion diffusion channel, thereby reducing its impact on the performance of the electrode assembly.
  • the winding structure is a cylindrical winding structure, and the width W of the flexible interlayer in the extension direction of the axis of the cylindrical winding structure satisfies:
  • W1 is the width of the end region in the extending direction of the axis of the cylindrical winding structure
  • H is the height of the cylindrical winding structure in the extending direction of the axis of the cylindrical winding structure.
  • the width W of the flexible spacer satisfy W1 ⁇ W ⁇ H, the risk of the electrode sheet being broken due to shear stress during cyclic expansion of the electrode assembly can be reduced, and the adverse effects on subsequent processes can be reduced.
  • the protruding length L1 of the flexible barrier layer relative to the edge of the end region in the circumferential direction of the wound structure satisfies:
  • L is the length of the flexible barrier layer in the winding direction.
  • the flexible interlayer can effectively overcome the influence of fluctuations in the actual bonding position of the flexible interlayer, ensuring the dispersion effect of the flexible interlayer on shear stress.
  • the protrusion length L1 satisfies: (1/3)*L ⁇ L1 ⁇ (2/3)*L.
  • the flexible interlayer can more effectively overcome the influence of fluctuations in the actual bonding position of the flexible interlayer, further ensuring the dispersion effect of the flexible interlayer on shear stress.
  • the thickness T of the flexible barrier layer satisfies:
  • t is the thickness of the first pole piece and the second pole piece that is disposed adjacent to the flexible barrier layer after the initial charge and discharge of the electrode assembly.
  • the shear stress at the step can be effectively dispersed during the cyclic expansion of the electrode assembly, reducing the risk of the pole piece breaking due to excessive shear stress.
  • the thickness T satisfies: 0.2*t ⁇ T ⁇ 0.5*t.
  • the shear stress at the step can be more effectively dispersed during the cyclic expansion of the electrode assembly, further reducing the risk of the electrode sheet breaking due to excessive shear stress.
  • the pole piece layer where the first end of the first pole piece in the winding direction is located and the pole piece layer where the second end of the second pole piece in the winding direction is located are both located on the inner side of the diaphragm layer where the third end of the diaphragm in the winding direction is located, and the third end protrudes relative to the first end and the second end in the circumferential direction of the winding structure, and the third end is bonded and fixed to the electrode assembly by a third single-sided adhesive tape.
  • the diaphragm By providing a third single-sided adhesive tape at the third end of the diaphragm to achieve bonding and fixing, the diaphragm can be fixed at the end to ensure that the electrode assembly will not become loose after winding.
  • the winding structure is a cylindrical winding structure, and the length L2 of the third single-sided adhesive tape in the winding direction satisfies:
  • D is the diameter of the cylindrical winding structure.
  • the electrode assembly can be firmly bonded and not loose, and can also be easily inserted into the housing of the battery cell.
  • the length L2 satisfies: 0.25 ⁇ *D ⁇ L2 ⁇ 1.05 ⁇ *D.
  • the electrode assembly can be bonded more securely and not loosely, and it is further convenient for the electrode assembly to enter the housing of the battery cell.
  • the length L2 satisfies: ⁇ *D ⁇ L2 ⁇ 1.05 ⁇ *D.
  • the third single-sided tape can have a small overlap when bonding and fixing the end of the diaphragm, thereby reducing the number of steps formed on the diaphragm by the end of the third single-sided tape, reducing the effect of the steps formed by the third single-sided tape on the shear stress of the electrode piece during cyclic expansion of the electrode assembly, and reducing the risk of the electrode piece breaking under the action of shear stress.
  • the winding structure is a cylindrical winding structure
  • the number of the third single-sided adhesive tapes is two
  • the two third single-sided adhesive tapes are arranged at intervals along the extension direction of the axis of the cylindrical winding structure.
  • the minimum distance from the third single-sided adhesive tape adjacent to the first end of the cylindrical winding structure among the two third single-sided adhesive tapes to the first end is h1
  • the width of the third single-sided adhesive tape adjacent to the first end of the cylindrical winding structure among the two third single-sided adhesive tapes is W2
  • the minimum distance from the third single-sided adhesive tape adjacent to the second end of the cylindrical winding structure among the two third single-sided adhesive tapes to the second end is h2
  • the width of the third single-sided adhesive tape adjacent to the second end of the cylindrical winding structure among the two third single-sided adhesive tapes is W3, and h1, W2, h2 and W3 satisfy:
  • H is the height of the cylindrical winding structure in the extension direction of the axis of the cylindrical winding structure.
  • the third single-sided tape can be mainly adhered to the active material coating thinning area on both sides of the electrode piece. In this way, a third single-sided tape with a larger thickness range can be used, and even if a relatively thick third single-sided tape is used, it is not easy to affect the electrode assembly entering the battery cell shell.
  • the thickness T1 of the third single-sided adhesive tape satisfies: 5 ⁇ m ⁇ T1 ⁇ 120 ⁇ m.
  • the third single-sided tape can have appropriate tensile strength, thereby reducing the risk of the third single-sided tape breaking under tension during cyclic expansion of the electrode assembly, and making the overall outer contour size of the electrode assembly bonded with the third single-sided tape more appropriate, thereby avoiding interference between the electrode assembly and the shell when entering the shell.
  • the minimum distance from the third single-sided adhesive tape adjacent to the first end of the cylindrical winding structure among the two third single-sided adhesive tapes to the first end is h1
  • the width of the third single-sided adhesive tape adjacent to the first end of the cylindrical winding structure among the two third single-sided adhesive tapes is W2
  • the minimum distance from the third single-sided adhesive tape adjacent to the second end of the cylindrical winding structure among the two third single-sided adhesive tapes to the second end is h2
  • the width of the third single-sided adhesive tape adjacent to the second end of the cylindrical winding structure among the two third single-sided adhesive tapes is W3, and h1, W1, h2 and W2 satisfy:
  • H is the height of the cylindrical winding structure in the extension direction of the axis of the cylindrical winding structure.
  • the third single-sided tape can be pasted not only on the thinned areas of the active material coating on both sides of the electrode but also on the areas of normal thickness of the active material coating. Therefore, a third single-sided tape with a relatively small thickness range is suitable, and the bonding strength can be improved by increasing the width of the third single-sided tape, so that the electrode assembly is not easy to loosen.
  • the thickness T1 of the third single-sided adhesive tape satisfies: 5 ⁇ m ⁇ T1 ⁇ 60 ⁇ m.
  • the third single-sided tape can have appropriate tensile strength, thereby reducing the risk of the third single-sided tape breaking under tension during cyclic expansion of the electrode assembly, and making the overall outer contour size of the electrode assembly bonded with the third single-sided tape more appropriate, thereby avoiding interference between the electrode assembly and the shell when entering the shell.
  • a battery cell comprising: the aforementioned electrode assembly.
  • the battery cell using the aforementioned electrode assembly can achieve better reliability in use.
  • a battery comprising: the aforementioned battery cell.
  • the battery using the aforementioned battery cell can achieve better reliability in use.
  • an electric device comprising: the aforementioned battery.
  • the electric device using the aforementioned battery can achieve better reliability in use.
  • FIG1 is a schematic diagram of the structure of some embodiments of electric equipment according to the present disclosure.
  • FIG2A is an exploded schematic diagram of some embodiments of batteries according to the present disclosure.
  • FIG. 2B is an exploded schematic diagram of some embodiments of a battery cell according to the present disclosure.
  • FIG3 is a schematic diagram of a winding structure of an electrode assembly according to some embodiments of the present disclosure.
  • 4A and 4B are schematic diagrams of the forces exerted on adjacent electrode layers by the electrode end regions when the electrode assembly is cyclically expanded when the electrode assembly is not provided with a flexible barrier layer and when the electrode end regions are provided with a flexible barrier layer;
  • 5A-5G are schematic diagrams of the arrangement structures of flexible barriers in some embodiments of the electrode assembly of the present disclosure.
  • FIG6A is a schematic diagram of a portion of an electrode assembly located at an end region in some embodiments of the present disclosure in an unfolded state;
  • FIG6B is a schematic diagram of the dimensions of FIG6A ;
  • FIG6C is a schematic diagram of the AA section in FIG6A ;
  • FIG7A is a schematic diagram of the structure of some embodiments of the electrode assembly of the present disclosure.
  • FIG7B is a schematic diagram of the dimensions of FIG7A ;
  • FIG. 7C is a cross-sectional schematic diagram of the third single-sided adhesive tape in FIG. 7A being adhered to the third end of the diaphragm.
  • 10 electrode assembly; 10A: current collector substrate; 10B: active material layer; 100: winding structure; 100A: first end; 100B: second end; 11: first pole piece; 11A: first starting end; 11B: first end; 12: second pole piece; 12A: second starting end; 12B: second end; 13: diaphragm; 131: first diaphragm segment; 132: second diaphragm segment; 133: third end; 14: flexible barrier; 14A: bonding surface; 14B: non-bonding surface; 141: first single-sided adhesive tape; 142: second single-sided adhesive tape; 15: end region; 16: third single-sided adhesive tape;
  • a step is formed between the beginning or end of the electrode sheet along the winding direction and the electrode sheet layer adjacent to the end.
  • Such a step may form a shear stress on the adjacent electrode sheet layer when the electrode assembly cyclically expands. If such a shear stress is large, the electrode sheet may be fractured at the position corresponding to the step, thereby causing the electrode assembly to fail and affecting the reliability of the electrode assembly.
  • the embodiments of the present disclosure provide an electrode assembly, a battery cell, a battery, and an electrical device, which can improve the reliability of the battery.
  • 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 by the embodiments of the present disclosure.
  • Battery cells may be cylindrical, flat, rectangular or other shapes, etc., which are not limited by the embodiments of the present application. Battery cells are generally divided into cylindrical battery cells, square battery cells and soft-pack battery cells according to the packaging method, which are not limited by the embodiments of the present application.
  • the battery cells of the embodiments of the present disclosure may be applicable to various types of batteries.
  • the battery may be used to power electrical equipment such as vehicles, for example, to provide a power source for the vehicle to operate or drive.
  • the battery may include a housing and a battery module, wherein the housing is used to provide a storage space for the battery module, and the battery module is installed in the housing.
  • the housing may be made of metal.
  • the battery module may include a plurality of battery cells connected in series, in parallel or in mixed connection.
  • a battery cell is the smallest unit that makes up a battery.
  • a battery cell includes an electrode assembly that can undergo an electrochemical reaction.
  • the battery of the embodiment of the present disclosure can be applied to various types of battery-using electrical equipment.
  • Electrical equipment can be mobile phones, portable devices, laptop computers, battery cars, electric cars, ships, spacecraft, electric toys and electric tools, etc.
  • spacecraft include airplanes, rockets, space shuttles and spacecrafts, etc.
  • Electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys and electric airplane toys, etc.
  • Electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators and electric planers.
  • the embodiment of the present disclosure does not impose any special restrictions on the above-mentioned electrical equipment.
  • FIG1 is a schematic diagram of the structure of some embodiments of the electric device according to the present disclosure.
  • the electric device is a vehicle as an example for description.
  • the vehicle 40 can be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle can be a pure electric vehicle or a hybrid vehicle, etc.
  • a battery 30 can be arranged at the bottom, front or rear of the vehicle 40.
  • the battery 30 can be used to power the vehicle 40.
  • the battery 30 can be used as an operating power source for the vehicle 40 and for the circuit system of the vehicle 40, such as for starting, navigating, and operating the vehicle 40.
  • the battery 30 can not only be used as an operating power source for the vehicle 40, but also as a driving power source for the vehicle 40, replacing or partially replacing fuel or natural gas to provide driving force for the vehicle 40.
  • FIG2A is a schematic diagram of an exploded view of some embodiments of the battery according to the present disclosure.
  • FIG2B is a schematic diagram of an exploded view of some embodiments of the battery cell according to the present disclosure.
  • the battery 30 includes a case 31, a case cover 32, and one or more battery cells 20 disposed in the case 31. While accommodating the battery cells 20, the case 31 can also provide the battery cells 20 with functions such as cooling, sealing, and anti-collision, and can also prevent liquids or other foreign matter from adversely affecting the charging, discharging, or safety of the battery cells 20.
  • the case cover 32 can be covered at the end of the case 31 to close the case 31.
  • the battery cells 20 are electrically connected, such as in series, in parallel, or in mixed connection, to achieve the required electrical performance parameters of the battery 30.
  • a plurality of battery cells 10 are arranged in rows, and one or more rows of battery cells 20 can be arranged in the case as needed.
  • the battery cells 20 of the battery 30 may be arranged along at least one of the length direction and the width direction of the box. At least one row or one column of battery cells 20 may be arranged according to actual needs. One or more layers of battery cells 20 may also be arranged in the height direction of the battery 30 as needed.
  • multiple battery cells 20 may be connected in series, in parallel, or in a hybrid connection to form a battery module, and then multiple battery modules may be connected in series, in parallel, or in a hybrid connection to form a whole, and then accommodated in the box 31.
  • all battery cells 20 are directly connected in series, in parallel, or in a hybrid connection, and then the whole formed by all battery cells 20 is accommodated in the box.
  • the electrode terminals of the battery cells 20 may be electrically connected to adjacent battery cells 20 through a busbar.
  • the battery cell 20 may include a shell 21, an end cap 22, and an electrode assembly 10.
  • the shell 21 has a cavity for accommodating the electrode assembly, and at least one end of the shell 21 may be configured to be open for setting the end cap 22.
  • the battery cell 20 also includes an electrolyte.
  • the battery cell 20 may also include a collector plate 23. The collector plate 23 is located at the diameter of the electrode pole on the electrode lug of the electrode assembly and the end cap, and may be fixedly connected to the smoothed lug by welding.
  • the cavity of the shell 21 can be used to accommodate the electrode assembly 10 and the electrolyte.
  • the end opening of the shell 21 is used to allow the electrode assembly 10 to enter the cavity through the end opening when the battery cell is installed.
  • the shape of the shell 21 can be determined according to the shape of one or more electrode assemblies 10 accommodated in the cavity.
  • the shape of the shell 21 is a hollow cuboid, a hollow cube, or a hollow cylinder.
  • the shell 21 can be made of a metal (such as aluminum, aluminum alloy, etc.) or a non-metallic material (plastic) with a certain hardness and strength.
  • the end cap 22 is disposed at the end opening of the shell 21, and is used to close the end opening, and to form a closed cavity with the shell 21 to accommodate the electrode assembly 10.
  • the end cap 22 can be made of a metal (such as aluminum, aluminum alloy, etc.) or a non-metallic material (plastic) with a certain hardness and strength.
  • the end cap 22 and the shell 21 can be fixedly connected by welding, bonding, or connecting through a connector.
  • Some functional components can be set on the end cap 22, such as a pole, a liquid injection mechanism, a pressure relief mechanism, etc. for electrical connection with the electrode assembly.
  • FIG3 is a schematic diagram of a winding structure according to some embodiments of an electrode assembly of the present disclosure.
  • FIG4A and FIG4B are schematic diagrams of the force exerted on adjacent electrode layers by the end regions of the electrode sheets without and with flexible interlayers, respectively, when the electrode assembly cyclically expands.
  • the present disclosure provides an electrode assembly 10, comprising: a first electrode sheet 11, a second electrode sheet 12, and a diaphragm 13 disposed between the first electrode sheet 11 and the second electrode sheet 12, wherein the first electrode sheet 11, the second electrode sheet 12, and the diaphragm 13 are wound along a winding direction r and form a winding structure 100.
  • the polarity of the first electrode 11 is opposite to that of the second electrode 12.
  • the first electrode 11 is a negative electrode
  • the second electrode 12 is a positive electrode.
  • the first electrode 11 is a positive electrode
  • the second electrode 12 is a negative electrode.
  • the operation of the electrode assembly 10 is achieved by the movement of internal metal ions between the positive electrode and the negative electrode.
  • the positive electrode plate includes a positive current collector substrate and a positive active material layer.
  • the positive electrode tab is connected or formed on the positive current collector substrate.
  • the material of the positive current collector substrate can be aluminum
  • the positive active material can be a lithium-ion material that can provide lithium ions, such as lithium cobalt oxide, lithium iron phosphate, ternary lithium or lithium manganese oxide.
  • the adhesive material can be PVDF (Polyvinylidene Fluoride) or the like.
  • the negative electrode plate includes a negative current collector substrate and a negative active material layer.
  • the negative electrode tab is connected to the negative current collector substrate.
  • the material of the negative current collector substrate can be copper
  • the negative active material can be graphite, silicon, lithium titanate and other materials that can store lithium ions.
  • the bonding material can be carboxymethyl cellulose, epoxy resin, styrene-butadiene rubber and the like.
  • the material of the diaphragm can be PP (polypropylene) or PE (polyethylene).
  • the electrolyte includes electrolyte and solvent.
  • the electrolyte is an organic metal salt, an inorganic salt, etc., which can provide metal ions that shuttle between the positive electrode and the negative electrode.
  • the tabs corresponding to the positive electrode sheets of each layer of the winding structure can be smoothed and welded to the collector plate or the positive electrode column on the end cover, and the tabs corresponding to the negative electrode sheets of each layer can be smoothed and welded to the collector plate or the negative electrode column on the end cover.
  • the first pole piece 11 has a first starting end 11A and a first ending end 11B in the winding direction r
  • the second pole piece 12 has a second starting end 12A and a second ending end 12B in the winding direction r.
  • a diaphragm 13, a first pole piece 11, another diaphragm 13, and a second pole piece 12 are sequentially stacked and wound along the winding direction r. Both diaphragms 13 can be longer than the first pole piece 11 and the second pole piece 12 in the winding direction r. Accordingly, the innermost side of the winding structure 100 can be firstly rolled up from the two diaphragms 13, and the third ends 133 of the two diaphragms 13 are wound on the outermost side of the winding structure 100.
  • At least one of the first pole piece 11 and the second pole piece 12 is provided with a flexible partition layer 14 between an end region 15 at at least one end in the winding direction r and a diaphragm segment adjacent to the end region 15 on the diaphragm 13, and the flexible partition layer 14 protrudes from the edge of the end region 15 in the circumferential direction of the winding structure 100.
  • the end region 15 may be at least one of the end region 15 of the pole piece layer where the first starting end 11A of the first pole piece 11 is located, the end region 15 of the pole piece layer where the first end 11B of the first pole piece 11 is located, the end region 15 of the pole piece layer where the second starting end 12A of the second pole piece 12 is located, and the end region 15 of the pole piece layer where the second end 12B of the second pole piece 12 is located.
  • the edge of the end region 15 is the cutting position of the pole piece.
  • the diaphragm segment adjacent to the end region 15 on the diaphragm 13 may be a diaphragm segment located inside or outside the end region 15 on the diaphragm 13 and adjacent to the end region.
  • the inside and outside here are relative to the winding structure 100, the side close to the center of the winding structure 100 is the inside, and the side away from the center of the winding structure 100 is the outside.
  • the circumferential direction of the winding structure 100 may be the winding direction r, or the opposite direction of the winding direction r.
  • the direction in which the flexible interlayer 14 protrudes relative to the edge of the end region 15 may be different.
  • the flexible interlayer 14 when the flexible interlayer 14 is provided in the end region 15 of the first starting end 11A or the second starting end 12B, the flexible interlayer 14 protrudes relative to the edge of the end region 15 in the opposite direction of the winding direction r; when the flexible interlayer 14 is provided in the end region 15 of the pole piece layer where the first end 11B is located or the pole piece layer where the second end 12B is located, the flexible interlayer 14 protrudes relative to the edge of the end region 15 in the winding direction r.
  • the diaphragm section adjacent to the end region 15 on the diaphragm 13 may be a diaphragm section located inside the end region 15 and adjacent to the end region 15, or may be a diaphragm section located outside the end region 15 and adjacent to the end region 15. Accordingly, the flexible barrier layer 14 may be disposed between the end region 15 and the inner diaphragm section, or between the end region 15 and the outer diaphragm section.
  • the position of the second end 12B of the second pole piece 12 is selected.
  • no flexible barrier layer 14 is provided between the end region 15 of the pole piece layer where the second end 12B is located and the diaphragm segment inside thereof
  • a flexible barrier layer 14 is provided between the end region 15 of the pole piece layer where the second end 12B is located and the diaphragm segment inside thereof.
  • the end region 15 of the pole sheet layer where the second end 12B of the second pole sheet 12 along the winding direction r is located forms a step with the pole sheet layer of the first pole sheet 11 inside the end, and this step can form a shear stress on the inner pole sheet layer when the electrode assembly 10 cyclically expands.
  • the step edge in FIG. 4A forms a relatively concentrated shear stress F. Since the shear stress F is relatively concentrated, it is easy to cause the inner pole sheet layer to break due to the shear force.
  • the flexible interlayer 14 in FIG. 4B can be deformed under the action of external force, so that the relatively concentrated shear stress formed by the step can be dispersed through the flexible interlayer 14. It can be seen that the shear stress F' is dispersed to a larger range, and accordingly the shear stress F' is significantly smaller than the shear stress F when the flexible interlayer 14 is not provided. In this way, the risk of the electrode sheet being broken due to the shear force is reduced, thereby improving the reliability of the electrode assembly 10.
  • the edge of the end region 15 is the cutting position of the electrode sheet.
  • the flexible barrier layer 14 can separate the burr at the cutting position of the end region 15 from the diaphragm 13 to prevent the burr from piercing the diaphragm 13 and short-circuiting with the electrode sheet of the other polarity, thereby improving the safety of the electrode assembly 10. Accordingly, the thickness of the flexible barrier layer 14 is greater than the height of the burr to prevent the burr from piercing the flexible barrier layer 14 and then piercing the diaphragm 13.
  • one of the end region 15 and the diaphragm segment may be bonded to the flexible barrier layer 14, and the other of the end region 15 and the diaphragm segment may be in slidable contact with the flexible barrier layer 14.
  • the end region 15 is bonded to the flexible barrier layer 14, and the diaphragm segment is in slidable contact with the flexible barrier layer 14.
  • the diaphragm segment is bonded to the flexible barrier layer 14, and the end region 15 is in slidable contact with the flexible barrier layer 14.
  • the end region 15 and one of the diaphragm segments are relatively fixed to the flexible interlayer 14 by bonding, so that the flexible interlayer 14 can be maintained in the area where the step is located, thereby ensuring the effective dispersion of shear stress; and the other of the end region 15 and the diaphragm segment is in slidable contact with the flexible interlayer 14 to avoid the phenomenon of wrinkling of the diaphragm 13 caused by the end region 15, the diaphragm segment and the flexible interlayer 14 being bonded together.
  • the flexible barrier layer 14 may include at least one single-sided adhesive tape.
  • the adhesive surface 14A of the single-sided adhesive tape is used to achieve the adhesive effect, and the non-adhesive surface 14B is used to achieve the sliding contact with the surface of the end region 15 or the diaphragm segment.
  • the flexible barrier layer 14 may also be a film layer coated on the surface of the end region 15 or the diaphragm segment.
  • the single-sided adhesive tape may include an adhesive tape substrate and an adhesive coating disposed on one side of the adhesive tape substrate, the adhesive coating serving as an adhesive surface 14A, and the other side of the adhesive tape substrate serving as a non-adhesive surface 14B.
  • the material of the adhesive tape substrate may include polypropylene (PP), polyethylene terephthalate (PET), or polyimide (PI).
  • the material of the adhesive coating may include acrylic glue (PMMA glue), etc.
  • the diaphragm segment includes: a first diaphragm segment 131 and a second diaphragm segment 132.
  • the first diaphragm segment 131 is located inside the end region 15.
  • the second diaphragm segment 132 is located outside the end region 15.
  • the flexible barrier layer 14 includes a first single-sided adhesive tape 141 bonded to one of the first diaphragm segment 131 and the second diaphragm segment 132.
  • a first single-sided adhesive tape 141 bonded to the side diaphragm segment is provided on one side of the end region 15.
  • the first single-sided adhesive tape 141 can disperse the shear stress of the end region 15 of the pole piece on its inner or outer side, and can also separate the burrs at the cut portion of the end region 15 from the side diaphragm segment to avoid the risk of the burrs piercing the diaphragm segment and causing a short circuit with the other polarity pole piece.
  • the adhesive surface 14A of the first single-sided adhesive tape 141 is bonded to the surface of the diaphragm segment on one side of the end region 15, its non-adhesive surface 14B will not be bonded to the surface of the diaphragm segment on the other side of the end region 15, thereby avoiding the first single-sided adhesive tape 141 from being wrinkled during winding due to the adhesion of the two diaphragms 13 after being set, thereby causing undesirable conditions such as lithium precipitation.
  • the first single-sided adhesive tape 141 can be set only on the inner side of the end region 15 of the pole piece layer where the second end 12B is located, thereby saving the step of setting single-sided adhesive tape on both sides of the end region 15.
  • the flexible barrier layer 14 includes a first single-sided adhesive tape 141 bonded to the first diaphragm segment 131 and a second single-sided adhesive tape 142 bonded to the second diaphragm segment 132.
  • the shear stress on both sides of the end region 15 can be dispersed by the first single-sided adhesive tape 141 and the second single-sided adhesive tape 142, and the burrs at the cut-off part of the end region 15 can be effectively separated from the first diaphragm segment 131 and the second diaphragm segment 132, thereby reducing the risk of the burrs piercing the diaphragm segment and causing a short circuit with the other polarity pole piece.
  • the protruding length p1 of the first single-sided adhesive tape 141 relative to the edge of the end region 15 in the circumferential direction of the winding structure 100 is the same as the protruding length p2 of the second single-sided adhesive tape 142 relative to the edge of the end region 15 in the circumferential direction of the winding structure 100.
  • the protruding length here refers to the protruding length when the first single-sided adhesive tape 141 and the second single-sided adhesive tape 142 are both flattened.
  • the shear stress on both sides of the end area 15 can be dispersed more evenly.
  • the protruding length of the first single-sided adhesive tape 141 relative to the edge of the end region 15 in the circumferential direction of the winding structure 100 may be different from the protruding length of the second single-sided adhesive tape 142 relative to the edge of the end region 15 in the circumferential direction of the winding structure 100.
  • the protruding length here refers to the protruding length when the first single-sided adhesive tape 141 and the second single-sided adhesive tape 142 are both flattened.
  • the protruding part of the first single-sided adhesive tape 141, the end area 15 and the protruding part of the second single-sided adhesive tape 142 can form a step with a gradual thickness change.
  • Such a step can effectively reduce the shear stress and, combined with the flexibility of the first single-sided adhesive tape 141 and the second single-sided adhesive tape 142, can more effectively reduce the risk of the pole piece being broken due to the shear force.
  • the flexible barrier layer 14 includes a first single-sided adhesive tape 141 and a second single-sided adhesive tape 142 respectively bonded to the inner surface and the outer surface of the end region 15.
  • the protruding length of the first single-sided adhesive tape 141 relative to the edge of the end region 15 in the circumferential direction of the winding structure 100 is the same as or different from the protruding length of the second single-sided adhesive tape 142 relative to the edge of the end region 15 in the circumferential direction of the winding structure 100.
  • the protruding length here refers to the protruding length when the first single-sided adhesive tape 141 and the second single-sided adhesive tape 142 are both flattened.
  • the inner and outer surfaces of the end region 15 are bonded by the first single-sided adhesive tape 141 and the second single-sided adhesive tape 142 on the bonding surface 14A, and the cut portion of the end region 15 is sealed by bonding the protruding sections of the first single-sided adhesive tape 141 and the second single-sided adhesive tape 142 with the same or different protruding lengths relative to the edge of the end region 15, so as to avoid the risk of burrs at the cut portion piercing or scratching the diaphragm 13 and causing a lap short circuit.
  • the process difficulty of this bonding method of the first single-sided adhesive tape 141 and the second single-sided adhesive tape 142 is relatively small.
  • the flexible barrier layer 14 includes a first single-sided adhesive tape 141, which is bonded to both the inner and outer surfaces of the end region 15 by folding.
  • the folding of the first single-sided adhesive tape 141 can form two opposite bonding surfaces 14A and two opposite non-bonding surfaces 14B.
  • the two bonding surfaces 14A are bonded to the inner and outer surfaces of the end region 15 respectively, and the two non-bonding surfaces 14B achieve sliding contact with the diaphragm segments on both sides of the end region 15.
  • the folded area closes the cut-off portion of the end region 15, which can effectively avoid the risk of burrs at the cut-off portion piercing or scratching the diaphragm 13 and causing a lap short circuit.
  • the first pole piece 11 may be a negative pole piece
  • the second pole piece 12 may be a positive pole piece.
  • the pole piece layer where the first end 11B of the first pole piece 11 in the winding direction r is located may be located outside the pole piece layer where the second end 12B of the second pole piece 12 in the winding direction r is located, and the first end 11B protrudes relative to the second end 12B in the circumferential direction of the winding structure 100.
  • the outermost negative electrode sheet can be wrapped around the outermost positive electrode sheet to ensure that the negative electrode sheet has sufficient lithium embedding space, thereby reducing the possibility of lithium deposition on the outermost negative electrode sheet.
  • a flexible barrier layer 14 is provided between the end region 15 of the pole sheet layer where the first end 11B is located and the diaphragm segment on the diaphragm 13 adjacent to the end region 15 of the pole sheet layer where the first end 11B is located.
  • a flexible barrier layer 14 is provided between the end region 15 of the pole sheet layer where the second end 12B is located and the diaphragm segment on the diaphragm 13 adjacent to the end region 15 of the pole sheet layer where the second end 12B is located.
  • the shear stress of the steps formed by the first end 11B and the second end 12B on the electrode sheet can be dispersed during the cycle of the electrode assembly 10, thereby reducing the risk of the electrode sheet being broken by the shear force, thereby improving the reliability of the electrode assembly 10; and for the second end 12B, the flexible partition 14 can separate the burrs at the cut-off part of its end area from the diaphragm 13 to prevent the burrs from piercing the diaphragm 13 and short-circuiting with the negative electrode sheet.
  • the pole piece layer where the first starting end 11A of the first pole piece 11 in the winding direction r is located is located inside the pole piece layer where the second starting end 12A of the second pole piece 12 in the winding direction r is located, and the first starting end 11A protrudes relative to the second starting end 12A in the circumferential direction of the winding structure 100.
  • the negative pole piece has sufficient lithium insertion space, thereby reducing the possibility of lithium deposition in the innermost negative pole piece.
  • a flexible barrier layer 14 is provided between the end region 15 of the electrode layer where the second starting end 12A is located and the diaphragm section adjacent to the end region 15 of the electrode layer where the second starting end 12A is located on the diaphragm 13.
  • the shear stress of the step formed by the second starting end 12A on the electrode sheet can be dispersed during the cycle of the electrode assembly 10, reducing the risk of the electrode sheet being broken by the shear force, thereby improving the reliability of the electrode assembly 10.
  • the negative electrode sheet can be wound empty for several turns, so that the first starting end 11A does not need to be provided with a flexible barrier layer 14, and there is no need to worry that the burrs at the cut-off part of the end region 11A of the first starting end 11A will pierce the diaphragm 13 and overlap and short-circuit with the positive electrode sheet.
  • At least one of the first electrode sheet 11 and the second electrode sheet 12 includes: a current collector substrate 10A and an active material layer 10B.
  • the active material layer 10B is at least arranged on the surface of the current collector substrate 10A adjacent to the separator 13.
  • the current collector substrate 10A and the active material layer 10B in the positive electrode sheet are respectively the positive electrode current collector substrate and the positive electrode active material layer.
  • the current collector substrate 10A and the active material layer 10B in the negative electrode sheet are respectively the negative electrode current collector substrate and the negative electrode active material layer.
  • the flexible barrier layer 14 may be disposed on the surface portion of the current collector substrate 10A that is not covered with the active material layer 10B on the end region 15, and the step height formed in the end region 15 is reduced compared to the flexible barrier layer 14 disposed on the active material layer 10B.
  • the structure shown in FIG. 5F also forms a multi-step structure in which the active material layer 10B, the current collector substrate 10A, and the flexible barrier layer 14 change sequentially.
  • the step height of the end region 15 can be reduced, thereby reducing the shear stress caused by the step during the cyclic expansion of the electrode assembly 10, thereby reducing the risk of the electrode sheet being broken by the shear force, and further improving the reliability of the electrode assembly 10.
  • Flexible interlayers 14 may be provided at both the beginning and the end of the first pole piece 11 and the second pole piece 12, or may be provided only in the beginning and the end of the first pole piece 11 and the second pole piece 12.
  • the inner side of the first end 11B is still adjacent to the pole piece layer inside itself, and the flexible interlayer 14 may not be provided here, but a lower step height may be formed by not covering the active material layer 10B with the portion corresponding to the end region 15 on the current collector substrate 10A as shown in FIG. 5G, so as to reduce the shear stress caused by the step here during the cyclic expansion of the electrode assembly 10, thereby reducing the risk of the pole piece being broken by the shear force, and thus improving the reliability of the electrode assembly 10.
  • FIG6A is a schematic diagram of a portion of an electrode assembly in an end region in some embodiments of the present disclosure in an unfolded state.
  • FIG6B is a schematic diagram of the dimensions of FIG6A.
  • FIG6C is a schematic diagram of the AA section in FIG6A.
  • the winding structure 100 is a cylindrical winding structure, and the length L of the flexible interlayer 14 in the winding direction r satisfies: 0.03 ⁇ *D ⁇ L ⁇ 0.25 ⁇ *D.
  • D is the diameter of the cylindrical winding structure.
  • the flexible partition 14 arranged between the electrode and the diaphragm 13 can block a part of the lithium ion diffusion channel. If the length L of the flexible partition 14 in the winding direction r is too large compared to the cross-sectional circumference ⁇ *D of the cylindrical winding structure, it will have a greater impact on the lithium ion diffusion, thereby affecting the performance of the electrode assembly 10.
  • the bonding and fixing effect between the flexible barrier layer 14 and the pole piece or the diaphragm 13 is weakened, causing the flexible barrier layer 14 to easily escape from the setting position.
  • the bonding and fixation between the flexible partition 14 and the electrode plate or diaphragm 13 can be reliable, thereby reducing the difficulty of setting up the flexible partition 14 and reducing the obstruction of the flexible partition 14 to the lithium ion diffusion channel, thereby reducing its impact on the performance of the electrode assembly 10.
  • the length L satisfies: 0.07 ⁇ *D ⁇ L ⁇ 0.13 ⁇ *D, for example, L is equal to 0.09 ⁇ *D, 0.1 ⁇ *D, 0.12 ⁇ *D, etc.
  • the winding structure 100 is a cylindrical winding structure, and the width W of the flexible interlayer 14 in the extension direction of the axis ax of the cylindrical winding structure satisfies: W1 ⁇ W ⁇ H.
  • W1 is the width of the end region 15 in the extension direction of the axis ax of the cylindrical winding structure
  • H is the height of the cylindrical winding structure in the extension direction of the axis ax of the cylindrical winding structure.
  • the height H of the cylindrical winding structure can be the maximum distance from the tab surface at one end of the cylindrical winding structure (i.e., the end surface of the tab on this side after being flattened) to the tab surface at the other end (i.e., the end surface of the tab on this side after being flattened) in the extension direction of the axis of the cylindrical winding structure.
  • the width W of the flexible interlayer 14 is smaller than the width W1 of the end region 15, it means that there is a portion between the end region 15 of the pole piece and the diaphragm 13 that is not covered by the flexible interlayer 14. Since the shear stress of these portions is not dispersed by the flexible interlayer 14, there is a risk of the pole piece breaking due to excessive shear stress.
  • the flexible interlayer 14 will be too long and extend beyond the pole ear at the end of the cylindrical winding structure 100, affecting the subsequent process of smoothing and welding the pole ear. In order not to affect the subsequent process, it is also necessary to cut off the excessively long portion of the flexible interlayer 14, which increases the manufacturing links and raises the manufacturing cost.
  • the width W of the flexible separator 14 satisfy W1 ⁇ W ⁇ H, the risk of the electrode sheet being broken due to shear stress during cyclic expansion of the electrode assembly 10 can be reduced, and the adverse effects on subsequent processes can be reduced.
  • the protruding length L1 of the flexible barrier layer 14 relative to the edge of the end region 15 in the circumferential direction of the winding structure 100 satisfies: (1/4)*L ⁇ L1 ⁇ (3/4)*L.
  • L is the length of the flexible barrier layer 14 in the winding direction r.
  • the relationship between the protruding length L1 of the flexible interlayer 14 and the length L of the flexible interlayer 14 reflects the position of the flexible interlayer 14 relative to the edge of the end area 15. If the protruding length L1 is too small or too large compared to the length L, the flexible interlayer 14 may not be accurately set at the appropriate position between the end area 15 of the pole piece and the diaphragm 13 due to fluctuations in the actual bonding position of the flexible interlayer 14.
  • the flexible barrier layer 14 When none or only a small part of the flexible barrier layer 14 is located between the end region 15 of the electrode piece and the diaphragm 13, or the flexible barrier layer 14 does not extend outward relative to the edge of the end region 15 in the circumferential direction of the electrode assembly 10, it makes it difficult for the flexible barrier layer 14 to effectively disperse the shear stress.
  • the flexible interlayer 14 can effectively overcome the influence of fluctuations in the actual bonding position of the flexible interlayer 14, ensuring the dispersion effect of the flexible interlayer 14 on shear stress.
  • the protrusion length L1 satisfies: (1/3)*L ⁇ L1 ⁇ (2/3)*L, for example, L1 is equal to (3/8)*L, (1/2)*L, etc.
  • the thickness T of the flexible barrier layer 14 satisfies: 0.07*t ⁇ T ⁇ 0.8*t.
  • t is the thickness of the first electrode sheet 11 and the second electrode sheet 12 adjacent to the flexible barrier layer 14 after the electrode assembly 10 is initially charged and discharged.
  • the flexible partition 14 can disperse the shear stress of the step formed at the end of the electrode sheet to the adjacent electrode sheet layer, thereby reducing the risk of rupture.
  • the step height of the end area 15 relative to the adjacent electrode sheet layer is also increased.
  • the overly thin flexible interlayer 14 is difficult to effectively disperse the shear stress at the step, increasing the risk of the pole piece breaking. If the thickness T of the flexible interlayer 14 is too large compared to the thickness t of the pole piece, the end region 15 forms a higher step after the overly thick flexible interlayer 14 is provided, which will lead to an increase in the shear stress at the step.
  • the shear stress at the step can be effectively dispersed during the cyclic expansion of the electrode assembly 10, thereby reducing the risk of the electrode sheet breaking due to excessive shear stress.
  • the thickness T satisfies: 0.2*t ⁇ T ⁇ 0.5*t, for example, T is equal to 0.3*t, 0.36*t, 0.42*t, etc.
  • the first electrode plate as the negative electrode plate and the second electrode plate as the positive electrode plate are both provided with a flexible barrier between the end area and the inner diaphragm segment at the end area of the end, and the flexible barrier is a single-sided adhesive tape with the adhesive surface bonded to the diaphragm segment.
  • the length L of the single-sided adhesive tape is 10mm
  • the width W is 87mm
  • the protruding length L1 is 5mm.
  • the test conditions are 45°C, and the charge and discharge rate is 0.5C (i.e., 1/2 times the battery cell capacity C).
  • the cycle depth is 10% battery state of charge SOC to 100% SOC, and the test is terminated when the battery cell capacity decays to 80%.
  • the electrode assembly after the test is disassembled to observe the fracture of the electrode plate.
  • the thickness t of the pole piece is 160 ⁇ m
  • 0.07 times t is 11.2 ⁇ m
  • 0.8 times t is 128 ⁇ m
  • the thickness T of the flexible barrier layer 14 is 0 ⁇ m, 5 ⁇ m and 150 ⁇ m respectively, which are all outside the numerical range of 11.2 ⁇ m to 128 ⁇ m, and it can be observed that the inner circle negative pole piece corresponding to the step in the end region has been broken.
  • the thickness t of the pole piece is 160 ⁇ m
  • the thickness T of the flexible barrier layer 14 is 30 ⁇ m and 60 ⁇ m respectively, which are all within the numerical range of 11.2 ⁇ m to 128 ⁇ m, and it can be observed that the inner circle negative pole piece corresponding to the step in the end region has not been broken.
  • FIG7A is a schematic diagram of the structure of some embodiments of the electrode assembly of the present disclosure.
  • FIG7B is a schematic diagram of the dimensions of FIG7A.
  • FIG7C is a schematic cross-sectional diagram of the third single-sided tape in FIG7A being adhered to the third end of the diaphragm.
  • the electrode layer where the first end 11B of the first pole piece 11 in the winding direction r is located and the electrode layer where the second end 12B of the second pole piece 12 in the winding direction r is located are both located on the inner side of the diaphragm layer where the third end 133 of the diaphragm 13 in the winding direction r is located, and the third end 133 protrudes relative to the first end 11B and the second end 12B in the circumferential direction of the winding structure 100, and the third end 133 is bonded and fixed to the electrode assembly 10 by the third single-sided tape 16.
  • the edge 133a of the third end 133 is bonded and fixed by the third single-sided tape 16. Since a portion of the third single-sided tape 16 is bonded to the third end 133 and another portion is bonded to the diaphragm layer inside the third end 133, the third single-sided tape 16 crosses the edge 133a.
  • the structure of the third single-sided tape 16 can refer to the first single-sided tape, and will not be described in detail here.
  • the pole piece layer where the first end 11B and the pole piece layer where the second end 12B are located are both arranged on the inner side of the diaphragm layer where the third end 133 is located, and the third end 133 is made to protrude relative to the first end 11B and the second end 12B in the circumferential direction of the winding structure 100, so as to ensure that the diaphragm 13 layer wraps the first pole piece 11 and the second pole piece 12, and prevents the pole piece ends from being exposed.
  • the third single-sided adhesive tape 16 at the third end 133 of the diaphragm 13 to achieve bonding and fixing, the diaphragm 13 can be fixed at the end, so as to ensure that the electrode assembly 10 after winding will not be loose.
  • the winding structure 100 is a cylindrical winding structure, and the length L2 of the third single-sided adhesive tape 16 in the winding direction r satisfies: 0.07 ⁇ *D ⁇ L2 ⁇ 1.5 ⁇ *D.
  • D is the diameter of the cylindrical winding structure.
  • the relationship between the length L2 of the third single-sided adhesive tape 16 in the winding direction r and the cross-sectional perimeter ⁇ *D of the cylindrical winding structure reflects the degree of wrapping of the outer circumference of the cylindrical winding structure by the third single-sided adhesive tape 16. If the length L2 of the third single-sided adhesive tape 16 is too small compared to the cross-sectional perimeter ⁇ *D of the cylindrical winding structure, the finishing and fixing effect of the diaphragm 13 achieved by the third single-sided adhesive tape 16 is affected, and there is a risk that the electrode assembly 10 becomes loose due to weak bonding and fixing.
  • the thickness of the third single-sided tape 16 may increase due to excessive overlap, thereby increasing the cross-sectional size of the electrode assembly 10, making it more difficult for the electrode assembly 10 to enter the battery cell shell 21.
  • the electrode assembly 10 can be firmly bonded and not loose, and can also be easily inserted into the housing 21 of the battery cell.
  • the length L2 satisfies: 0.25 ⁇ *D ⁇ L2 ⁇ 1.05 ⁇ *D, for example, L2 is equal to 0.4 ⁇ *D, 0.75 ⁇ *D, ⁇ *D, etc.
  • the length L2 may satisfy: ⁇ *D ⁇ L2 ⁇ 1.05 ⁇ *D, for example, L2 is equal to 1.02 ⁇ *D, 1.03 ⁇ *D, etc.
  • the third single-sided adhesive tape 16 can have a small overlap while bonding and fixing the end of the diaphragm 13, thereby reducing the number of steps formed by the end of the third single-sided adhesive tape 16 on the diaphragm 13, reducing the effect of the steps formed by the third single-sided adhesive tape 16 on the shear stress of the electrode sheet when the electrode assembly 10 is cyclically expanded, and reducing the risk of the electrode sheet breaking under the action of shear stress.
  • the winding structure 100 is a cylindrical winding structure
  • the third single-sided adhesive tape 16 is provided in two pieces, and the two third single-sided adhesive tapes 16 are arranged at intervals along the extension direction of the axis ax of the cylindrical winding structure.
  • the minimum distance from the third single-sided adhesive tape 16 adjacent to the first end 100A of the cylindrical winding structure among the two third single-sided adhesive tapes 16 to the first end 100A is h1
  • the width of the third single-sided adhesive tape 16 adjacent to the first end 100A of the cylindrical winding structure among the two third single-sided adhesive tapes 16 is W2
  • the minimum distance from the third single-sided adhesive tape 16 adjacent to the second end 100B of the cylindrical winding structure among the two third single-sided adhesive tapes 16 is h2.
  • the width of the third single-sided adhesive tape 16 adjacent to the second end 100B of the cylindrical winding structure is W3, and h1, W2, h2 and W3 satisfy the following conditions: 0 ⁇ h1 ⁇ 0.07*H, 0 ⁇ h2 ⁇ 0.07*H, 0.05*H ⁇ W2 ⁇ 0.12*H, 0.05*H ⁇ W3 ⁇ 0.12*H.
  • h1 is equal to 0.02*H, 0.04*H, 0.055*H, etc.
  • h2 is equal to 0.015*H, 0.035*H, 0.56*H, etc.
  • W2 is equal to 0.07*H, 0.09*H, 0.11*H
  • W3 is equal to 0.06*H, 0.08*H, 0.1*H.
  • H is the height of the cylindrical winding structure in the extension direction of the axis ax of the cylindrical winding structure.
  • the minimum distances h1 and h2 from the two third single-sided adhesive tapes 16 to the two ends of the cylindrical winding structure respectively reflect the degree to which the third single-sided adhesive tapes 16 are close to the ends of the winding structure 100, while the widths W2 and W3 reflect the range covered by the third single-sided adhesive tapes 16.
  • the third single-sided tape 16 can be mainly adhered to the active material coating thinning area on both sides of the electrode piece. In this way, a third single-sided tape 16 with a larger thickness range can be used. Even if a relatively thick third single-sided tape 16 is used, it is not easy to affect the electrode assembly 10 from entering the battery cell shell 21.
  • the thickness T1 of the third single-sided adhesive tape 16 satisfies: 5 ⁇ m ⁇ T1 ⁇ 120 ⁇ m.
  • T1 is equal to 10 ⁇ m, 40 ⁇ m, 85 ⁇ m, 115 ⁇ m, etc.
  • a third single-sided adhesive tape 16 that is too thin has a low tensile strength, and there is a risk that the third single-sided adhesive tape 16 breaks under the action of tension when the electrode assembly 10 expands cyclically, causing the electrode assembly 10 to loosen.
  • a third single-sided adhesive tape 16 that is too thick will increase the outer contour size of the electrode assembly 10, making it more difficult for the electrode assembly 10 to enter the housing 21.
  • the third single-sided tape 16 can have appropriate tensile strength, thereby reducing the risk of the third single-sided tape 16 breaking under the action of tension when the electrode assembly 10 cyclically expands, and making the overall outer contour size of the electrode assembly 10 bonded with the third single-sided tape 16 more appropriate, thereby avoiding interference between the electrode assembly 10 and the shell 21 when entering the shell 21.
  • the minimum distance from the third single-sided adhesive tape 16 adjacent to the first end 100A of the cylindrical winding structure among the two third single-sided adhesive tapes 16 to the first end is h1
  • the width of the third single-sided adhesive tape 16 adjacent to the first end 100A of the cylindrical winding structure among the two third single-sided adhesive tapes 16 is W2
  • the minimum distance from the third single-sided adhesive tape 16 adjacent to the second end 100B of the cylindrical winding structure among the two third single-sided adhesive tapes 16 to the second end is h2.
  • the width of the third single-sided adhesive tape 16 adjacent to the second end 100B of the cylindrical winding structure is W3, and h1, W1, h2 and W2 satisfy: 0.07*H ⁇ h1 ⁇ 0.25*H, 0.07*H ⁇ h2 ⁇ 0.25*H, 0.05*H ⁇ W2 ⁇ 0.23*H, 0.05*H ⁇ W3 ⁇ 0.23*H.
  • h1 is equal to 0.09*H, 0.15*H, 0.22*H, etc.
  • h2 is equal to 0.1*H, 0.18*H, 0.24*H, etc.
  • W2 is equal to 0.12*H, 0.18*H, 0.22*H
  • W3 is equal to 0.1*H, 0.16*H, 0.2*H.
  • H is the height of the cylindrical winding structure in the extension direction of the axis ax of the cylindrical winding structure.
  • the minimum distances h1 and h2 from the two third single-sided adhesive tapes 16 to the two ends of the cylindrical winding structure respectively reflect the degree to which the third single-sided adhesive tapes 16 are close to the ends of the winding structure 100, while the widths W2 and W3 reflect the range covered by the third single-sided adhesive tapes 16.
  • the third single-sided tape 16 can be adhered to the active material coating thinning area on both sides of the electrode as well as the area with normal thickness of the active material coating. Therefore, a third single-sided tape 16 with a relatively small thickness range is suitable, and the bonding strength is improved by increasing the width of the third single-sided tape 16, so that the electrode assembly 10 is not easy to loosen.
  • the thickness T1 of the third single-sided adhesive tape 16 satisfies: 5 ⁇ m ⁇ T1 ⁇ 60 ⁇ m.
  • T1 is equal to 12 ⁇ m, 24 ⁇ m, 32 ⁇ m, 46 ⁇ m, 52 ⁇ m, etc.
  • a third single-sided adhesive tape 16 that is too thin has a low tensile strength, and there is a risk that the third single-sided adhesive tape 16 breaks under the action of tension when the electrode assembly 10 expands cyclically, causing the electrode assembly 10 to loosen.
  • a third single-sided adhesive tape 16 that is too thick will increase the outer contour size of the electrode assembly 10, making it more difficult for the electrode assembly 10 to enter the housing 21.
  • the third single-sided tape 16 can have appropriate tensile strength, thereby reducing the risk of the third single-sided tape 16 breaking under the action of tension when the electrode assembly 10 cyclically expands, and making the overall outer contour size of the electrode assembly 10 bonded with the third single-sided tape 16 more appropriate, thereby avoiding interference between the electrode assembly 10 and the shell 21 when entering the shell 21.
  • the embodiments of the present disclosure also provide a battery cell, including the aforementioned electrode assembly.
  • the battery cell using the aforementioned electrode assembly embodiment can obtain better reliability in use.
  • a battery comprising the aforementioned battery cell.
  • the battery using the aforementioned battery cell can achieve better reliability in use.
  • an electric device comprising the battery described above.
  • the electric device using the battery described above can achieve better reliability in use.
  • the present disclosure also provides an embodiment of a battery using the aforementioned battery cell embodiments.
  • the battery includes a battery cell of any of the aforementioned embodiments.
  • the battery using the aforementioned battery cell embodiments can achieve better reliability in use.
  • an electric device comprising the battery described above.
  • the electric device using the battery described above can achieve better reliability in use.

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Abstract

一种电极组件(10)，包括：第一极片(11)、第二极片(12)和设于所述第一极片(11)和所述第二极片(12)之间的隔膜(13)，所述第一极片(11)、所述第二极片(12)和所述隔膜(13)沿卷绕方向(r)卷绕并形成卷绕结构(100)；其中，所述第一极片(11)和所述第二极片(12)中的至少一个在所述卷绕方向(r)上的至少一端的端部区域(15)和所述隔膜(13)上与所述端部区域(15)相邻的隔膜段之间设有柔性隔层(14)，所述柔性隔层(14)在所述卷绕结构(100)的周向上凸出于所述端部区域(15)的边缘。

Description

电极组件、电池单体、电池及用电设备 技术领域
本公开涉及电池技术领域，特别涉及一种电极组件、电池单体、电池及用电设备。
背景技术
二次电池尤其是锂离子电池具有电压高、比能量大、循环寿命长、绿色无污染、工作温度范围宽及自放电小等优点，在便携式电子设备及大型新能源电动汽车的动力设备方面得到广泛应用，对解决人类环境污染和能源危机有着重大意义。随着二次电池的广泛应用，电池的使用可靠性成为使用者密切关注的问题。
发明内容
在本公开的一个方面，提供一种电极组件，包括：第一极片、第二极片和设于所述第一极片和所述第二极片之间的隔膜，所述第一极片、所述第二极片和所述隔膜沿卷绕方向卷绕并形成卷绕结构；
其中，所述第一极片和所述第二极片中的至少一个在所述卷绕方向上的至少一端的端部区域和所述隔膜上与所述端部区域相邻的隔膜段之间设有柔性隔层，所述柔性隔层在所述卷绕结构的周向上凸出于所述端部区域的边缘。
通过在端部区域和与端部区域相邻的隔膜段之间设置柔性隔层，并使柔性隔层凸出于所述端部区域的边缘，这样可通过柔性隔层来分散台阶所形成的较集中的剪切应力，从而降低极片受剪切力作用而断裂的风险，进而提高电极组件的使用可靠性。
在一些实施例中，所述端部区域和所述隔膜段中之一与所述柔性隔层粘接，所述端部区域和所述隔膜段中另一与所述柔性隔层可滑动地接触。
通过粘接实现端部区域和隔膜段中之一与柔性隔层的相对固定，以便使柔性隔层能够保持在台阶所在区域，从而确保对剪切应力的有效分散效果；通过使端部区域和隔膜段中另一与柔性隔层可滑动地接触，以免端部区域、隔膜段和柔性隔层均粘接在一起而造成隔膜起皱的现象。
在一些实施例中，所述柔性隔层包括至少一个单面胶纸。
通过单面胶纸的粘接面实现粘接作用，通过非粘接面实现与端部区域或隔膜段的表面的滑动接触。
在一些实施例中，所述隔膜段包括：
第一隔膜段，位于所述端部区域内侧；
第二隔膜段，位于所述端部区域外侧；
其中，所述柔性隔层包括与所述第一隔膜段和所述第二隔膜段中之一粘接的第一单面胶纸。
在端部区域的一侧设置与该侧隔膜段粘接的第一单面胶纸，可通过第一单面胶纸实现极片的端部区域对其内侧或外侧的极片的剪切应力的分散作用，还能够将端部区域切断部位的毛刺与该侧隔膜段隔开，以免造成毛刺刺穿该隔膜段而导致与另一极性极片搭接短路的风险。
在一些实施例中，所述隔膜段包括：
第一隔膜段，位于所述端部区域内侧；
第二隔膜段，位于所述端部区域外侧；
其中，所述柔性隔层包括与所述第一隔膜段和所述第二隔膜段分别粘接的第一单面胶纸和第二单面胶纸，所述第一单面胶纸在所述卷绕结构的周向上相对于所述端部区域的边缘的凸出长度与所述第二单面胶纸在所述卷绕结构的周向上相对于所述端部区域的边缘的凸出长度相同或不同。
通过将第一单面胶纸和第二单面胶纸分别粘接到第一隔膜段和第二隔膜段，可通过第一单面胶纸和第二单面胶纸实现端部区域内外两侧的剪切应力的分散作用，并有效地使端部区域切断部位的毛刺与第一隔膜段和第二隔膜段均隔开，从而降低毛刺刺穿该隔膜段而导致与另一极性极片搭接短路的风险。另外，通过使第一单面胶纸在所述卷绕结构的周向上相对于所述端部区域的边缘的凸出长度与所述第二单面胶纸在所述卷绕结构的周向上相对于所述端部区域的边缘的凸出长度相同，可以使端部区域内外两侧的剪切应力的分散作用更均匀。
通过使第一单面胶纸在所述卷绕结构的周向上相对于所述端部区域的边缘的凸出长度与所述第二单面胶纸在所述卷绕结构的周向上相对于所述端部区域的边缘的凸出长度不同，可使得第一单面胶纸的外伸部分、端部区域和第二单面胶纸的外伸部分形成厚度渐变的台阶，这种台阶可以有效地降低剪切应力，配合第一单面胶纸和第二单面胶纸的柔性，从而更有效地降低极片受剪切力作用而断裂的风险。
在一些实施例中，所述柔性隔层包括第一单面胶纸，所述第一单面胶纸通过折叠方式与所述端部区域的内侧表面和外侧表面均粘接。
通过第一单面胶纸的折叠形成相对的两个粘接面和相反的两个非粘接面，利用两个粘接面分别与端部区域的内侧表面和外侧表面进行粘接，利用两个非粘接面实现与端部区域内外两侧的隔膜段的滑动接触，还利用折叠区域封闭端部区域的切断部位，避免切断部位的毛刺刺穿或划伤隔膜，造成搭接短路的风险。
在一些实施例中，所述柔性隔层包括与所述端部区域的内侧表面和外侧表面分别粘接的第一单面胶纸和第二单面胶纸，所述第一单面胶纸在所述卷绕结构的周向上相对于所述端部区域的边缘的凸出长度与所述第二单面胶纸在所述卷绕结构的周向上相对于所述端部区域的边缘的凸出长度相同或不同。
通过粘接面相对的第一单面胶纸和第二单面胶纸对端部区域的内侧表面和外侧表面进行粘接，并通过第一单面胶纸和第二单面胶纸相对于端部区域的边缘的凸出长度相同或不同的凸出段的相互粘接来封闭端部区域的切断部位，避免切断部位的毛刺刺穿或划伤隔膜，造成搭接短路的风险。并且，这种第一单面胶纸和第二单面胶纸的粘接方式的工艺难度相对较小。
在一些实施例中，所述第一极片为负极极片，所述第二极片为正极极片。
在一些实施例中，在所述卷绕结构中，所述第一极片在所述卷绕方向上的第一末端所在极片层位于所述第二极片在所述卷绕方向上的第二末端所在极片层的外侧，且所述第一末端在所述卷绕结构的周向上相对于所述第二末端凸出，所述第一末端所在极片层的端部区域和所述隔膜上与所述第一末端所在极片层的端部区域相邻的隔膜段之间设有柔性隔层，所述第二末端所在极片层的端部区域和所述隔膜上与所述第二末端所在极片层的端部区域相邻的隔膜段之间设有柔性隔层。
通过使第一极片的第一末端所在极片层位于第二极片的第二末端所在极片层的外侧，并使第一末端沿周向相对于第二末端凸出，可实现最外层的负极极片对最外层的正极极片的包裹作用，以确保负极极片具有充足的嵌锂空间，从而减小最外层的负极极片析锂的可能性。在这种结构下，通过在第一末端和第二末端均设置柔性隔层，可以在电极组件循环过程中分散第一末端和第二末端分别形成的台阶对极片的剪切应力，降低极片受剪切力作用而断裂的风险，进而提高电极组件的使用可靠性；并且对于第二末端来说，柔性隔层可将其端部区域的切断部位的毛刺与隔膜隔开，以免毛刺刺穿隔膜而与负极极片搭接短路。
在一些实施例中，在所述卷绕结构中，所述第一极片在所述卷绕方向上的第一始端所在极片层位于所述第二极片在所述卷绕方向上的第二始端所在极片层的内侧，且 所述第一始端在所述卷绕结构的周向上相对于所述第二始端凸出，所述第二始端所在极片层的端部区域和所述隔膜上与所述第二始端所在极片层的端部区域相邻的隔膜段之间设有柔性隔层。
通过使第一极片的第一始端所在极片层位于第二极片的第二始端所在极片层的内侧，并使第一始端沿周向相对于第二始端凸出，这样可确保负极极片具有充足的嵌锂空间，从而减小最内层的负极极片析锂的可能性。在这种结构下，通过在第二始端所在极片层的端部区域设置柔性隔层，可以在电极组件循环过程中分散第二始端形成的台阶对极片的剪切应力，降低极片受剪切力作用而断裂的风险，进而提高电极组件的使用可靠性。由于电极组件中心卷绕较松驰，此处负极极片可以空卷几圈，使得第一始端无需设置柔性隔层，无需担心第一始端的端部区域切断部位的毛刺会刺穿隔膜而与正极极片搭接短路。
在一些实施例中，所述第一极片和所述第二极片中的至少一个包括：
集流体基材；
活性物质层，至少设置在所述集流体基材邻近所述隔膜一侧的表面；
其中，在所述卷绕方向上，所述集流体基材的至少一端对应于所述端部区域的表面部分未被所述活性物质层覆盖。
通过使极片的集流体基材上对应于端部区域的部分不覆盖活性物质层，无论是否在端部区域设置柔性隔层，都可以降低端部区域的台阶高度，从而降低电极组件循环膨胀时台阶带来的剪切应力，从而降低极片受剪切力作用而断裂的风险，进而提高电极组件的使用可靠性。
在一些实施例中，所述卷绕结构为圆柱形卷绕结构，所述柔性隔层在所述卷绕方向上的长度L满足：
0.03π*D≤L≤0.25π*D；
其中，D为所述圆柱形卷绕结构的直径。
通过使长度L大于等于0.03π倍的直径D，且小于等于0.25π倍的直径D，可以使柔性隔层与极片或隔膜之间的粘接固定可靠，降低柔性隔层的设置难度，也能够减小柔性隔层对锂离子扩散通道的阻挡，从而降低其对电极组件性能的影响。
在一些实施例中，长度L满足：0.07π*D≤L≤0.13π*D。
通过使长度L大于等于0.07π倍的直径D，且小于等于0.13π倍的直径D，可以使柔性隔层与极片或隔膜之间的粘接固定更加可靠，进一步降低柔性隔层的设置难度， 也能够有效地减小柔性隔层对锂离子扩散通道的阻挡，从而降低其对电极组件性能的影响。
在一些实施例中，所述卷绕结构为圆柱形卷绕结构，所述柔性隔层在所述圆柱形卷绕结构的轴线的延伸方向上的宽度W满足：
W1≤W≤H；
其中，W1为所述端部区域在所述圆柱形卷绕结构的轴线的延伸方向上的宽度，H为所述圆柱形卷绕结构在所述圆柱形卷绕结构的轴线的延伸方向上的高度。
通过使柔性隔层的宽度W满足W1≤W≤H，可以降低极片在电极组件循环膨胀时因剪切应力导致断裂的风险，并减少对后续工序的不利影响。
在一些实施例中，所述柔性隔层在所述卷绕结构的周向上相对于所述端部区域的边缘的凸出长度L1满足：
(1/4)*L≤L1≤(3/4)*L；
其中，L为所述柔性隔层在所述卷绕方向上的长度。
通过使凸出长度L1大于等于1/4倍的L，且小于等于3/4倍的L，可以使柔性隔层有效地克服柔性隔层实际粘接位置的波动的影响，确保柔性隔层对剪切应力的分散作用。
在一些实施例中，所述凸出长度L1满足：(1/3)*L≤L1≤(2/3)*L。
通过使凸出长度L1大于等于1/3倍的L，且小于等于2/3倍的L，可以使柔性隔层更有效地克服柔性隔层实际粘接位置的波动的影响，进一步确保柔性隔层对剪切应力的分散作用。
在一些实施例中，所述柔性隔层的厚度T满足：
0.07*t≤T≤0.8*t；
其中，t为所述第一极片和所述第二极片中与所述柔性隔层相邻设置的极片在所述电极组件初次充放电后的厚度。
通过使柔性隔层的厚度T大于等于0.07倍的极片厚度t，且小于等于0.8倍的极片厚度t，可以在电极组件循环膨胀时有效地分散台阶处的剪切应力，降低极片因过大的剪切应力断裂的风险。
在一些实施例中，厚度T满足：0.2*t≤T≤0.5*t。
通过使柔性隔层的厚度T大于等于0.2倍的极片厚度t，且小于等于0.5倍的极片厚度t，可以在电极组件循环膨胀时更有效地分散台阶处的剪切应力，进一步降低极 片因过大的剪切应力断裂的风险。
在一些实施例中，所述第一极片在所述卷绕方向上的第一末端所在极片层和所述第二极片在所述卷绕方向上的第二末端所在极片层均位于所述隔膜在所述卷绕方向上的第三末端所在隔膜层的内侧，且所述第三末端在所述卷绕结构的周向上相对于所述第一末端和所述第二末端均凸出，所述第三末端通过第三单面胶纸在所述电极组件上粘接固定。
通过在隔膜第三末端设置第三单面胶纸来实现粘接固定，可实现隔膜收尾固定效果，确保卷绕后的电极组件不会松散。
在一些实施例中，所述卷绕结构为圆柱形卷绕结构，所述第三单面胶纸在所述卷绕方向上的长度L2满足：
0.07π*D≤L2≤1.5π*D；
其中，D为所述圆柱形卷绕结构的直径。
通过使长度L2大于等于0.07π倍的直径D，且小于等于1.5π倍的直径D，可以使电极组件粘接牢靠不松散，也能够方便进入电池单体的壳体。
在一些实施例中，长度L2满足：0.25π*D≤L2≤1.05π*D。
通过使长度L2大于等于0.25π倍的直径D，且小于等于1.05π倍的直径D，可以使电极组件粘接更加牢靠不松散，并且进一步方便电极组件进入电池单体的壳体。
在一些实施例中，长度L2满足：π*D<L2≤1.05π*D。
通过使长度L2大于π倍的直径D，且小于等于1.05π倍的直径D，可以使第三单面胶纸在粘接固定隔膜的末端的同时有少量交叠，这样就减少了第三单面胶纸的端部在隔膜上形成的台阶数量，降低第三单面胶纸形成的台阶在电极组件循环膨胀时对极片的剪切应力的作用，降低极片在剪切应力作用下断裂的风险。
在一些实施例中，所述卷绕结构为圆柱形卷绕结构，所述第三单面胶纸设置为两个，两个所述第三单面胶纸沿所述圆柱形卷绕结构的轴线的延伸方向间隔排布。
通过设置沿轴线的延伸方向间隔排布的两个第三单面胶纸，可以在满足粘接固定要求的同时，避免第三单面胶纸对电极组件形成过大的束缚力，从而降低电极组件的集流体基材的延伸率，并且还减少了第三单面胶纸的胶纸用量。
在一些实施例中，在所述圆柱形卷绕结构的轴线的延伸方向上，两个所述第三单面胶纸中邻近所述圆柱形卷绕结构的第一端的所述第三单面胶纸到所述第一端的最小距离为h1，两个所述第三单面胶纸中邻近所述圆柱形卷绕结构的第一端的所述第三 单面胶纸的宽度为W2，两个所述第三单面胶纸中邻近所述圆柱形卷绕结构的第二端的所述第三单面胶纸到所述第二端的最小距离为h2，两个所述第三单面胶纸中邻近所述圆柱形卷绕结构的第二端的所述第三单面胶纸的宽度为W3，h1、W2、h2和W3满足：
0≤h1≤0.07*H，0≤h2≤0.07*H，0.05*H≤W2≤0.12*H，0.05*H≤W3≤0.12*H；
其中，H为所述圆柱形卷绕结构在所述圆柱形卷绕结构的轴线的延伸方向上的高度。
通过使h1和h2满足0≤h1≤0.07*H，0≤h2≤0.07*H，并使W2和W3满足0.05*H≤W2≤0.12*H，0.05*H≤W3≤0.12*H，可以使第三单面胶纸主要粘贴在极片两侧的活性材料涂布减薄区，这样可适用更大厚度范围的第三单面胶纸，即使采用相对较厚的第三单面胶纸也不容易影响电极组件进入电池单体的壳体。
在一些实施例中，所述第三单面胶纸的厚度T1满足：5μm≤T1≤120μm。
在最小距离h1、h2和宽度W2、W3满足合适取值范围时，通过使第三单面胶纸的厚度T1满足5μm≤T1≤120μm，可使得第三单面胶纸具备合适的抗拉强度，降低在电极组件循环膨胀时第三单面胶纸在拉力作用下断裂的风险，并使粘接第三单面胶纸的电极组件整体外轮廓尺寸更合适，避免电极组件进入壳体时与壳体干涉。
在一些实施例中，在所述圆柱形卷绕结构的轴线的延伸方向上，两个所述第三单面胶纸中邻近所述圆柱形卷绕结构的第一端的所述第三单面胶纸到所述第一端的最小距离为h1，两个所述第三单面胶纸中邻近所述圆柱形卷绕结构的第一端的所述第三单面胶纸的宽度为W2，两个所述第三单面胶纸中邻近所述圆柱形卷绕结构的第二端的所述第三单面胶纸到所述第二端的最小距离为h2，两个所述第三单面胶纸中邻近所述圆柱形卷绕结构的第二端的所述第三单面胶纸的宽度为W3，h1、W1、h2和W2满足：
0.07*H≤h1≤0.25*H，0.07*H≤h2≤0.25*H，0.05*H≤W2≤0.23*H，0.05*H≤W3≤0.23*H；
其中，H为所述圆柱形卷绕结构在所述圆柱形卷绕结构的轴线的延伸方向上的高度。
通过使h1和h2满足0.07*H≤h1≤0.25*H，0.07*H≤h2≤0.25*H，并使W2和W3满足0.05*H≤W2≤0.23*H，0.05*H≤W3≤0.23*H，可以使第三单面胶纸粘贴极片两侧的活性材料涂布减薄区之外还粘贴在活性材料涂布正常厚度的区域，因此适用相对较小 厚度范围的第三单面胶纸，并且通过增加第三单面胶纸的宽度来提高粘接的牢靠程度，使电极组件不容易松散。
在一些实施例中，所述第三单面胶纸的厚度T1满足：5μm≤T1≤60μm。
在最小距离h1、h2和宽度W2、W3满足合适取值范围时，通过使第三单面胶纸的厚度T1满足5μm≤T1≤60μm，可使得第三单面胶纸具备合适的抗拉强度，降低在电极组件循环膨胀时第三单面胶纸在拉力作用下断裂的风险，并使粘接第三单面胶纸的电极组件整体外轮廓尺寸更合适，避免电极组件进入壳体时与壳体干涉。
在本公开的一个方面，提供一种电池单体，包括：前述的电极组件。采用了前述的电极组件的电池单体可实现更优的使用可靠性。
在本公开的一个方面，提供一种电池，包括：前述的电池单体。采用了前述的电池单体的电池可实现更优的使用可靠性。
在本公开的一个方面，提供一种用电设备，包括：前述的电池。采用了前述的电池的用电设备可实现更优的使用可靠性。
附图说明
为了更清楚地说明本公开实施例的技术方案，下面将对本公开实施例中所需要使用的附图作简单地介绍，显而易见地，下面所描述的附图仅仅是本公开的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据附图获得其他的附图。
参照附图，根据下面的详细描述，可以更加清楚地理解本公开，其中：
图1是根据本公开用电设备的一些实施例的结构示意图；
图2A是根据本公开电池的一些实施例的分解示意图；
图2B是根据本公开电池单体的一些实施例的分解示意图；
图3是根据本公开电极组件的一些实施例的卷绕结构的示意图；
图4A和图4B分别是未设置柔性隔层和设置柔性隔层的极片端部区域在电极组件循环膨胀时对相邻极片层的作用力示意图；
图5A-图5G分别是本公开电极组件的一些实施例的柔性隔层的设置结构示意图；
图6A是本公开电极组件的一些实施例中位于端部区域的部分在展开状态下的示意图；
图6B是图6A的尺寸示意图；
图6C是图6A中AA截面的示意图；
图7A是本公开电极组件的一些实施例的结构示意图；
图7B是图7A的尺寸示意图；
图7C是图7A中第三单面胶纸粘贴在隔膜的第三末端的截面示意图。
应当明白，附图中所示出的各个部分的尺寸并不是按照实际的比例关系绘制的。此外，相同或类似的参考标号表示相同或类似的构件。
附图标记说明：
10：电极组件；10A：集流体基材；10B：活性物质层；100：卷绕结构；100A：第一端；100B：第二端；11：第一极片；11A：第一始端；11B：第一末端；12：第二极片；12A：第二始端；12B：第二末端；13：隔膜；131：第一隔膜段；132：第二隔膜段；133：第三末端；14：柔性隔层；14A：粘接面；14B：非粘接面；141：第一单面胶纸；142：第二单面胶纸；15：端部区域；16：第三单面胶纸；
20：电池单体；21：壳体；22：端盖；23：集流盘；
30：电池；31：箱体；32：箱盖
40：车辆。
具体实施方式
下面结合附图和实施例对本公开的实施方式作进一步详细描述。以下实施例的详细描述和附图用于示例性地说明本公开的原理，但不能用来限制本公开的范围，即本公开不限于所描述的实施例。
在本公开的描述中，需要说明的是，除非另有说明，“多个”的含义是两个以上；术语“上”、“下”、“左”、“右”、“内”、“外”等指示的方位或位置关系仅是为了便于描述本公开和简化描述，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公开的限制。此外，术语“第一”、“第二”、“第三”等仅用于描述目的，而不能理解为指示或暗示相对重要性。“垂直”并不是严格意义上的垂直，而是在误差允许范围之内。“平行”并不是严格意义上的平行，而是在误差允许范围之内。
下述描述中出现的方位词均为图中示出的方向，并不是对本公开的具体结构进行限定。在本公开的描述中，还需要说明的是，除非另有明确的规定和限定，术语“安装”、“相连”、“连接”应做广义理解，例如，可以是固定连接，也可以是可拆卸连接， 或一体地连接；可以是直接相连，也可以通过中间媒介间接相连。对于本领域的普通技术人员而言，可视具体情况理解上述术语在本公开中的具体含义。
下面结合附图，对本发明的一些实施方式作详细说明。在不冲突的情况下，下述的实施例中的特征可以相互组合。
在电极组件的卷绕结构中，极片沿卷绕方向的始端或末端与该端相邻的极片层形成台阶，这种台阶在电极组件循环膨胀时可形成对该相邻极片层的剪切应力，如果这种剪切应力较大则可能造成极片在对应于台阶的位置受力断裂，从而导致电极组件失效，影响电极组件的使用可靠性。
有鉴于此，本公开实施例提供一种电极组件、电池单体、电池及用电设备，能够改善电池的使用可靠性。
本公开实施例的电极组件可适用于各类电池单体。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，本公开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柱形电池单体、方形电池单体和软包电池单体，本申请实施例对此也不限定。
本公开实施例的电池单体可适用于各类电池。电池可用于车辆等用电设备的供电，例如给车辆提供操控用的电源或者驱动行驶用的电源。电池可包括壳体和电池模组，壳体用于为电池模组提供容纳空间，电池模组安装在壳体内。壳体可采用金属材质。电池模组可包括串联、并联或混联的多个电池单体。电池单体为组成电池的最小单元。电池单体包括能够发生电化学反应的电极组件。
本公开实施例的电池可适用于各类使用电池的用电设备。用电设备可以是手机、便携式设备、笔记本电脑、电瓶车、电动汽车、轮船、航天器、电动玩具和电动工具等等，例如，航天器包括飞机、火箭、航天飞机和宇宙飞船等，电动玩具包括固定式或移动式的电动玩具，例如，游戏机、电动汽车玩具、电动轮船玩具和电动飞机玩具等等，电动工具包括金属切削电动工具、研磨电动工具、装配电动工具和铁道用电动工具，例如，电钻、电动砂轮机、电动扳手、电动螺丝刀、电锤、冲击电钻、混凝土振动器和电刨。本公开实施例对上述用电设备不做特别限制。
图1是根据本公开用电设备的一些实施例的结构示意图。为了方便，以用电装置为车辆为例进行说明。车辆40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或混合动力汽车等。在车辆40的底部或车头或车尾可以设置电 池30。
电池30可以用于车辆40的供电，例如，电池30可以作为车辆40的操作电源，用于车辆40的电路系统，例如用于车辆40的启动、导航和运行时的工作用电需求。电池30不仅仅可以作为车辆40的操作电源，还可以作为车辆40的驱动电源，替代或部分替代燃油或天然气为车辆40提供驱动力。
图2A是根据本公开电池的一些实施例的分解示意图。图2B是根据本公开电池单体的一些实施例的分解示意图。参考图2A，在一些实施例中，电池30包括箱体31、箱盖32以及设置于箱体31中的一个或者多个电池单体20。箱体31在容纳电池单体20的同时，还可给电池单体20提供诸如冷却、密封及防撞击等功能，还能够避免液体或其他异物对电池单体20的充放电或安全的不利影响。箱盖32可盖合在箱体31的端部，以封闭箱体31。各个电池单体20之间电连接，比如串联、并联或者混联，以实现所需要的电池30的电性能参数。多个电池单体10成排设置，根据需要可以在箱体内设置一排或者多排电池单体20。
在一些实施例中，电池30的各电池单体20可以沿着箱体的长度方向和宽度方向中的至少一个排列。根据实际需要可设置至少一行或一列电池单体20。根据需要，还可以在电池30的高度方向，也可设置一层或者多层电池单体20。
在一些实施例中，多个电池单体20可先串联或并联或混联组成电池模块，然后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31内。在另一些实施例中，所有电池单体20直接串联或并联或混联在一起，再将所有电池单体20构成的整体容纳于箱体内。电池单体20的电极端子可通过汇流排(Busbar)与相邻的电池单体20电连接。
参考图2B，在一些实施例中，电池单体20可包括壳体21、端盖22和电极组件10。壳体21具有空腔，用于容纳所述电极组件，且所述壳体21的至少一端可被构造为敞口的，用于设置端盖22。电池单体20除了包括电极组件、端盖22和壳体21，还包括电解液。电池单体20还可以包括集流盘23。集流盘23位于电极组件的极耳与端盖上的电极极柱直径，并可与已抚平的极耳通过焊接方式固定连接。
壳体21的空腔可用于容纳电极组件10，并可容纳电解液。壳体21的端部开口用于电池单体安装时使电极组件10经该端部开口进入空腔。壳体21的形状可根据空腔中容纳的一个或多个电极组件10的形状而定，例如壳体21的形状为中空长方体或中空正方体或中空圆柱体。壳体21可由具有一定硬度和强度的金属(例如铝、铝合金 等)或非金属材料(塑料)制成。
端盖22设置在壳体21的端部开口，用于封闭端部开口，并与壳体21形成容纳电极组件10的密闭腔体。端盖22可由具有一定硬度和强度的金属(例如铝、铝合金等)或非金属材料(塑料)制成。端盖22与壳体21可通过焊接、粘接或通过连接件连接等方式实现固定连接。端盖22上可设置一些功能部件，例如用于与电极组件电连接的极柱、注液机构、泄压机构等。
图3是根据本公开电极组件的一些实施例的卷绕结构的示意图。图4A和图4B分别是未设置柔性隔层和设置柔性隔层的极片端部区域在电极组件循环膨胀时对相邻极片层的作用力示意图。参考图3和图4B，本公开提供了一种电极组件10，包括：第一极片11、第二极片12和设于所述第一极片11和所述第二极片12之间的隔膜13，所述第一极片11、所述第二极片12和所述隔膜13沿卷绕方向r卷绕并形成卷绕结构100。
第一极片11与第二极片12的极性相反。在一些实施例中，第一极片11为负极极片，第二极片12为正极极片。在另一些实施例中，第一极片11为正极极片，第二极片12为负极极片。电极组件10的运行是通过内部的金属离子在正极极片和负极极片之间移动实现的。
正极极片包括正极集流体基材和正极活性物质层。正极极耳连接或形成在正极集流体基材上。以锂离子电池为例，正极集流体基材的材料可以为铝，正极活性物质可以为钴酸锂、磷酸铁锂、三元锂或锰酸锂等可以提供锂离子的锂化物质。对于采用粘结物质粘接正极集流体基材和正极活性物质层的情况，该粘结物质可以是PVDF(Polyvinylidene Fluoride，聚偏氟乙烯)等。
负极极片包括负极集流体基材和负极活性物质层。负极极耳连接活性成在负极集流体基材上。以锂离子电池为例，负极集流体基材的材料可以为铜，负极活性物质可以为石墨、硅、钛酸锂等可以储存锂离子的物质。对于采用粘结物质粘接负极集流体基材和负极活性物质层的情况，该粘结物质可以是羧甲基纤维素、环氧树脂、丁苯橡胶等。
隔膜的材质可以为PP(polypropylene，聚丙烯)或PE(polyethylene，聚乙烯)等。电解液包括电解质及溶剂，电解质为有机金属盐、无机盐等，可以提供在正极极片和负极极片之间穿梭的金属离子。为了保证具有足够的过电流能力，卷绕结构的各层正极极片对应的极耳可抚平后与集流盘焊接或与端盖上的正极极柱焊接，各层负极极片 对应的极耳可抚平后与集流盘焊接或与端盖上的负极极柱焊接。
在图3中，第一极片11在卷绕方向r上具有第一始端11A和第一末端11B，第二极片12在卷绕方向r上具有第二始端12A和第二末端12B。在卷绕结构100中，一个隔膜13、第一极片11、另一个隔膜13和第二极片12依次叠置后沿卷绕方向r卷绕，两个隔膜13在卷绕方向r上均可比第一极片11和第二极片12更长，相应地，卷绕结构100的最内侧可先从两个隔膜13卷起，并将两个隔膜13的第三末端133卷绕在卷绕结构100的最外侧。
参考图3和图4B，所述第一极片11和所述第二极片12中的至少一个在所述卷绕方向r上的至少一端的端部区域15和所述隔膜13上与所述端部区域15相邻的隔膜段之间设有柔性隔层14，所述柔性隔层14在所述卷绕结构100的周向上凸出于所述端部区域15的边缘。
在图3中，端部区域15可以为第一极片11的第一始端11A所在极片层的端部区域15、第一极片11的第一末端11B所在极片层的端部区域15、第二极片12的第二始端12A所在极片层的端部区域15和第二极片12的第二末端12B所述极片层的端部区域15中的至少一个。对于通过切断方式来形成一定长度的极片的实施例来说，端部区域15的边缘为极片的切断位置。
隔膜13上与所述端部区域15相邻的隔膜段可以为隔膜13上位于端部区域15内侧或外侧且与端部区域相邻的隔膜段。这里的内侧和外侧是相对于卷绕结构100来说的，靠近卷绕结构100的中心的一侧为内侧，远离卷绕结构100的中心的一侧为外侧。
卷绕结构100的周向可以为卷绕方向r，也可以为卷绕方向r的反方向。根据端部区域15所在的位置，柔性隔层14相对于所述端部区域15的边缘凸出的方向可能不同。例如在第一始端11A或第二始端12B的端部区域15设置柔性隔层14时，柔性隔层14在所述卷绕方向r的反方向上相对于端部区域15的边缘凸出；在第一末端11B所在极片层或第二末端12B所在极片层的端部区域15设置柔性隔层14时，柔性隔层14在所述卷绕方向r上相对于端部区域15的边缘凸出。
所述隔膜13上与所述端部区域15相邻的隔膜段可以为隔膜13位于端部区域15内侧且与端部区域15相邻的隔膜段，也可以为隔膜13位于端部区域15外侧且与端部区域15相邻的隔膜段。相应地，柔性隔层14可以设置在端部区域15与内侧的隔膜段之间，也可以设置在端部区域15与外侧的隔膜段之间。
为了方便说明，选取了第二极片12的第二末端12B所在的位置。在图4A中，第 二末端12B所在极片层的端部区域15与其内侧的隔膜段之间未设置柔性隔层14，在图4B中，第二末端12B所在极片层的端部区域15与其内侧的隔膜段之间设有柔性隔层14。
从图4A和图4B可以看到，在卷绕结构100中，第二极片12沿卷绕方向r的第二末端12B所在极片层的端部区域15与该端内侧的第一极片11的极片层形成台阶，这种台阶在电极组件10循环膨胀时可形成对内侧的极片层的剪切应力。图4A中的台阶边缘在内侧的极片层循环膨胀时，形成比较集中的剪切应力F。由于剪切应力F比较集中，容易导致内侧的极片层受剪切力而断裂。
图4B中的柔性隔层14可以在受到外力的作用下发生形变，这样可通过柔性隔层14来分散台阶所形成的较集中的剪切应力，可以看到剪切应力F’被分散到更大的范围，相应地剪切应力F’明显地小于不设置柔性隔层14时的剪切应力F。这样就降低极片受剪切力作用而断裂的风险，进而提高电极组件10的使用可靠性。
对于通过切断方式来形成一定长度的极片的实施例来说，端部区域15的边缘为极片的切断位置。柔性隔层14可将端部区域15切断部位的毛刺与隔膜13隔开，以免毛刺刺穿隔膜13而与另一极性的极片搭接短路，从而提高了电极组件10的使用安全性。相应地，柔性隔层14的厚度比毛刺的高度更大，以免毛刺刺穿柔性隔层14后再刺穿隔膜13。
在上述实施例中，所述端部区域15和所述隔膜段中之一可与所述柔性隔层14粘接，所述端部区域15和所述隔膜段中另一可与所述柔性隔层14可滑动地接触。例如所述端部区域15与所述柔性隔层14粘接，所述隔膜段与所述柔性隔层14可滑动地接触。又例如所述隔膜段与所述柔性隔层14粘接，所述端部区域15与所述柔性隔层14可滑动地接触。
通过粘接实现端部区域15和隔膜段中之一与柔性隔层14的相对固定，以便使柔性隔层14能够保持在台阶所在区域，从而确保对剪切应力的有效分散效果；通过使端部区域15和隔膜段中另一与柔性隔层14可滑动地接触，以免端部区域15、隔膜段和柔性隔层14均粘接在一起而造成隔膜13起皱的现象。
为了更方便地设置柔性隔层，在一些实施例中，柔性隔层14可包括至少一个单面胶纸。通过单面胶纸的粘接面14A实现粘接作用，通过非粘接面14B实现与端部区域15或隔膜段的表面的滑动接触。在另一些实施例中，柔性隔层14也可以为涂敷在端部区域15或隔膜段的表面的膜层。
单面胶纸可包括胶纸基材和设置在胶纸基材的一侧表面的胶粘涂层，胶粘涂层可作为粘接面14A，而胶纸基材的另一侧表面作为非粘接面14B。胶纸基材的材料可包括聚丙烯(Polypropylene，即PP)、聚对苯二甲酸乙二醇酯(polyethylene terephthalate，即PET)或聚酰亚胺(polyimide，即PI)等。胶粘涂层的材料可包括亚克力胶(即PMMA胶)等。
图5A-图5G分别是本公开电极组件的一些实施例的柔性隔层的设置结构示意图。参考图5A，在一些实施例中，所述隔膜段包括：第一隔膜段131和第二隔膜段132。第一隔膜段131位于所述端部区域15内侧。第二隔膜段132位于所述端部区域15外侧。所述柔性隔层14包括与所述第一隔膜段131和所述第二隔膜段132中之一粘接的第一单面胶纸141。
在端部区域15的一侧设置与该侧隔膜段粘接的第一单面胶纸141，可通过第一单面胶纸141实现极片的端部区域15对其内侧或外侧的极片的剪切应力的分散作用，还能够将端部区域15切断部位的毛刺与该侧隔膜段隔开，以免造成毛刺刺穿该隔膜段而导致与另一极性极片搭接短路的风险。
由于第一单面胶纸141的粘接面14A粘接在端部区域15一侧的隔膜段表面，其非粘接面14B就不会与端部区域15另一侧的隔膜段表面粘接，从而避免第一单面胶纸141设置后由于粘连两个隔膜13而导致隔膜13在卷绕时被拉皱，从而导致析锂等不良状态。对于图5A所示的第二末端12B的内侧有第一极片11，而外侧无第一极片11而只有隔膜13的情况，可以仅在第二末端12B所在极片层的端部区域15的内侧设置第一单面胶纸141即可，从而可节省在端部区域15两侧都设置单面胶纸的步骤。
参考图5B和图5C，在一些实施例中，所述柔性隔层14包括与所述第一隔膜段131粘接的第一单面胶纸141和与所述第二隔膜段132粘接的第二单面胶纸142。通过将第一单面胶纸141和第二单面胶纸142分别粘接到第一隔膜段131和第二隔膜段132，可通过第一单面胶纸141和第二单面胶纸142实现端部区域15内外两侧的剪切应力的分散作用，并有效地使端部区域15切断部位的毛刺与第一隔膜段131和第二隔膜段132均隔开，从而降低毛刺刺穿该隔膜段而导致与另一极性极片搭接短路的风险。
在图5B中，所述第一单面胶纸141在所述卷绕结构100的周向上相对于所述端部区域15的边缘的凸出长度p1与所述第二单面胶纸142在所述卷绕结构100的周向上相对于所述端部区域15的边缘的凸出长度p2相同。这里的凸出长度是指第一单面 胶纸141和第二单面胶纸142均展平时的凸出长度。
通过使第一单面胶纸141在所述卷绕结构100的周向上相对于所述端部区域15的边缘的凸出长度与所述第二单面胶纸142在所述卷绕结构100的周向上相对于所述端部区域15的边缘的凸出长度相同，可以使端部区域15内外两侧的剪切应力的分散作用更均匀。
在图5C中，所述第一单面胶纸141在所述卷绕结构100的周向上相对于所述端部区域15的边缘的凸出长度与所述第二单面胶纸142在所述卷绕结构100的周向上相对于所述端部区域15的边缘的凸出长度也可以不同。这里的凸出长度是指第一单面胶纸141和第二单面胶纸142均展平时的凸出长度。
通过使第一单面胶纸141在所述卷绕结构100的周向上相对于所述端部区域15的边缘的凸出长度与所述第二单面胶纸142在所述卷绕结构100的周向上相对于所述端部区域15的边缘的凸出长度不同，可使得第一单面胶纸141的外伸部分、端部区域15和第二单面胶纸142的外伸部分形成厚度渐变的台阶，这种台阶可以有效地降低剪切应力，配合第一单面胶纸141和第二单面胶纸142的柔性，从而更有效地降低极片受剪切力作用而断裂的风险。
参考图5D，在一些实施例中，所述柔性隔层14包括与所述端部区域15的内侧表面和外侧表面分别粘接的第一单面胶纸141和第二单面胶纸142。所述第一单面胶纸141在所述卷绕结构100的周向上相对于所述端部区域15的边缘的凸出长度与所述第二单面胶纸142在所述卷绕结构100的周向上相对于所述端部区域15的边缘的凸出长度相同或不同。这里的凸出长度是指第一单面胶纸141和第二单面胶纸142均展平时的凸出长度。
通过粘接面14A相对的第一单面胶纸141和第二单面胶纸142对端部区域15的内侧表面和外侧表面进行粘接，并通过第一单面胶纸141和第二单面胶纸142相对于端部区域15的边缘的凸出长度相同或不同的凸出段的相互粘接来封闭端部区域15的切断部位，避免切断部位的毛刺刺穿或划伤隔膜13，造成搭接短路的风险。并且，这种第一单面胶纸141和第二单面胶纸142的粘接方式的工艺难度相对较小。
参考图5E，在一些实施例中，所述柔性隔层14包括第一单面胶纸141，所述第一单面胶纸141通过折叠方式与所述端部区域15的内侧表面和外侧表面均粘接。第一单面胶纸141的折叠可形成相对的两个粘接面14A和相反的两个非粘接面14B。两个粘接面14A分别与端部区域15的内侧表面和外侧表面进行粘接，两个非粘接面14B 实现与端部区域15内外两侧的隔膜段的滑动接触，而折叠区域封闭端部区域15的切断部位，可以有效地避免切断部位的毛刺刺穿或划伤隔膜13而造成搭接短路的风险。
参考图3，在上述实施例中，所述第一极片11可以为负极极片，所述第二极片12可以为正极极片。在这种卷绕结构100中，所述第一极片11在所述卷绕方向r上的第一末端11B所在极片层可位于所述第二极片12在所述卷绕方向r上的第二末端12B所在极片层的外侧，且所述第一末端11B在所述卷绕结构100的周向上相对于所述第二末端12B凸出。
通过使第一极片11的第一末端11B所在极片层位于第二极片12的第二末端12B所在极片层的外侧，并使第一末端11B沿周向向相对于第二末端12B凸出，可实现最外层的负极极片对最外层的正极极片的包裹作用，以确保负极极片具有充足的嵌锂空间，从而减小最外层的负极极片析锂的可能性。
所述第一末端11B所在极片层的端部区域15和所述隔膜13上与所述第一末端11B所在极片层的端部区域15相邻的隔膜段之间设有柔性隔层14。所述第二末端12B所在极片层的端部区域15和所述隔膜13上与所述第二末端12B所在极片层的端部区域15相邻的隔膜段之间设有柔性隔层14。
在这种结构下，通过在第一末端11B和第二末端12B均设置柔性隔层14，可以在电极组件10循环过程中分散第一末端11B和第二末端12B分别形成的台阶对极片的剪切应力，降低极片受剪切力作用而断裂的风险，进而提高电极组件10的使用可靠性；并且对于第二末端12B来说，柔性隔层14可将其端部区域的切断部位的毛刺与隔膜13隔开，以免毛刺刺穿隔膜13而与负极极片搭接短路。
仍参考图3，在前述所述第一极片11为负极极片，所述第二极片12为正极极片的实施例的所述卷绕结构100中，所述第一极片11在所述卷绕方向r上的第一始端11A所在极片层位于所述第二极片12在所述卷绕方向r上的第二始端12A所在极片层的内侧，且所述第一始端11A在所述卷绕结构100的周向上相对于所述第二始端12A凸出。通过使第一极片11的第一始端11A所在极片层位于第二极片12的第二始端12A所在极片层的内侧，并使第一始端11A沿周向相对于第二始端12A凸出，这样可确保负极极片具有充足的嵌锂空间，从而减小最内层的负极极片析锂的可能性。
所述第二始端12A的所在极片层端部区域15和所述隔膜13上与所述第二始端12A所在极片层的端部区域15相邻的隔膜段之间设有柔性隔层14。在这种结构下，通过在第二始端12A设置柔性隔层14，可以在电极组件10循环过程中分散第二始端 12A形成的台阶对极片的剪切应力，降低极片受剪切力作用而断裂的风险，进而提高电极组件10的使用可靠性。由于电极组件10中心卷绕较松驰，此处负极极片可以空卷几圈，使得第一始端11A无需设置柔性隔层14，无需担心第一始端11A的端部区域11A切断部位的毛刺会刺穿隔膜13而与正极极片搭接短路。
参考图5F和图5G，在一些实施例中，所述第一极片11和所述第二极片12中的至少一个包括：集流体基材10A和活性物质层10B。活性物质层10B至少设置在所述集流体基材10A邻近所述隔膜13一侧的表面。正极极片中的集流体基材10A和活性物质层10B分别为正极集流体基材和正极活性物质层。负极极片中的集流体基材10A和活性物质层10B分别为负极集流体基材和负极活性物质层。
在所述卷绕方向r上，所述集流体基材10A的至少一端对应于所述端部区域15的表面部分未被所述活性物质层10B覆盖。在图5F中，柔性隔层14可设置在端部区域15上对应于未覆盖活性物质层10B的集流体基材10A的表面部分上，相比于柔性隔层14设置在活性物质层10B上，在端部区域15形成的台阶高度得以降低。而且，图5F所示的结构还形成了活性物质层10B、集流体基材10A和柔性隔层14依次变化的多级台阶结构。
通过使极片的集流体基材10A上对应于端部区域15的部分不覆盖活性物质层10B，无论是否在端部区域15设置柔性隔层14，都可以降低端部区域15的台阶高度，从而降低电极组件10循环膨胀时台阶带来的剪切应力，从而降低极片受剪切力作用而断裂的风险，进而提高电极组件10的使用可靠性。
在第一极片11和第二极片12各自的始端和末端可以都设置柔性隔层14，也可以只在第一极片11和第二极片12各自的始端和末端中的部分设置柔性隔层14。对于图3中第一末端11B来说，其内侧相邻的仍是自身在内的极片层，此处也可不设置柔性隔层14，而是可通过图5G所示的通过集流体基材10A上对应于端部区域15的部分不覆盖活性物质层10B来形成较低的台阶高度，以此降低电极组件10循环膨胀时此处台阶带来的剪切应力，从而降低极片受剪切力作用而断裂的风险，进而提高电极组件10的使用可靠性。
图6A是本公开电极组件的一些实施例中位于端部区域的部分在展开状态下的示意图。图6B是图6A的尺寸示意图。图6C是图6A中AA截面的示意图。参考图2B、图6A和图6B，在一些实施例中，所述卷绕结构100为圆柱形卷绕结构，所述柔性隔层14在所述卷绕方向r上的长度L满足：0.03π*D≤L≤0.25π*D。D为所述圆柱形卷绕 结构的直径。
设置在极片和隔膜13之间的柔性隔层14可阻挡一部分面积的锂离子扩散通道，如果柔性隔层14在所述卷绕方向r上的长度L相比于圆柱形卷绕结构的横截面周长π*D过大，则对锂离子扩散影响较大，从而影响电极组件10的性能。
如果该长度L相比于圆柱形卷绕结构的横截面周长π*D过小，则使得柔性隔层14与极片或隔膜13之间的粘接固定效果变弱，导致柔性隔层14容易脱离设置位置。另外在制造电极组件10时过小的长度L的设置比较困难，从而导致电极组件10的制造难度增加。
因此，通过使长度L大于等于0.03π倍的直径D，且小于等于0.25π倍的直径D，可以使柔性隔层14与极片或隔膜13之间的粘接固定可靠，降低柔性隔层14的设置难度，也能够减小柔性隔层14对锂离子扩散通道的阻挡，从而降低其对电极组件10性能的影响。
在一些实施例中，长度L满足：0.07π*D≤L≤0.13π*D，例如L等于0.09π*D、0.1π*D、0.12π*D等。通过使长度L大于等于0.07π倍的直径D，且小于等于0.13π倍的直径D，可以使柔性隔层14与极片或隔膜13之间的粘接固定更加可靠，进一步降低柔性隔层14的设置难度，也能够有效地减小柔性隔层14对锂离子扩散通道的阻挡，从而降低其对电极组件10性能的影响。
通过下表所示的几个实验例和对比例来说明一下取不同长度L和厚度D的技术效果。
直径D(mm) 长度L(mm) L/(π*D) 效果
90 10 0.0354 柔性隔层未松脱
90 35 0.1238 柔性隔层未松脱
120 10 0.0265 柔性隔层松脱
120 35 0.0928 柔性隔层未松脱
参考图6B，在一些实施例中，所述卷绕结构100为圆柱形卷绕结构，所述柔性隔层14在所述圆柱形卷绕结构的轴线ax的延伸方向上的宽度W满足：W1≤W≤H。W1为所述端部区域15在所述圆柱形卷绕结构的轴线ax的延伸方向上的宽度，H为所述圆柱形卷绕结构在所述圆柱形卷绕结构的轴线ax的延伸方向上的高度。圆柱体卷绕结构的高度H可以为从圆柱体卷绕结构一端的极耳面(即该侧极耳揉平后的端面)到另一端的极耳面(即该侧极耳抚平后的端面)在所述圆柱形卷绕结构的轴线的延伸方 向上的最大距离。
如果柔性隔层14的宽度W小于端部区域15的宽度W1，则表示极片的端部区域15与隔膜13之间存在未被柔性隔层14覆盖的部分，这些部分由于未通过柔性隔层14分散剪切应力，存在着因剪切应力过大导致极片断裂的风险。
如果柔性隔层14的宽度W大于圆柱体卷绕结构100的高度H，则会因柔性隔层14过长而超出位于圆柱体卷绕结构100端部的极耳，影响极耳抚平焊接的后续工序，而为了不影响后续工序，则还需要切除柔性隔层14过长部分的工序，增加制造环节，提高制造成本。
因此，通过使柔性隔层14的宽度W满足W1≤W≤H，可以降低极片在电极组件10循环膨胀时因剪切应力导致断裂的风险，并减少对后续工序的不利影响。
仍参考图6B，在一些实施例中，所述柔性隔层14在所述卷绕结构100的周向上相对于所述端部区域15的边缘的凸出长度L1满足：(1/4)*L≤L1≤(3/4)*L。L为所述柔性隔层14在所述卷绕方向r上的长度。
柔性隔层14的凸出长度L1与柔性隔层14的长度L的关系体现了柔性隔层14相对于端部区域15的边缘的位置，如果凸出长度L1相比于长度L过小或过大，都容易因柔性隔层14实际粘接位置的波动而导致柔性隔层14不能准确地被设置在极片的端部区域15和隔膜13之间合适的位置。
当柔性隔层14没有或只有很少部分位于极片的端部区域15和隔膜13之间，或者柔性隔层14未在电极组件10的周向上相对于端部区域15的边缘外伸，则导致柔性隔层14难以有效地分散剪切应力。
因此，通过使凸出长度L1大于等于1/4倍的L，且小于等于3/4倍的L，可以使柔性隔层14有效地克服柔性隔层14实际粘接位置的波动的影响，确保柔性隔层14对剪切应力的分散作用。
在一些实施例中，所述凸出长度L1满足：(1/3)*L≤L1≤(2/3)*L，例如L1等于(3/8)*L、(1/2)*L等。通过使凸出长度L1大于等于1/3倍的L，且小于等于2/3倍的L，可以使柔性隔层14更有效地克服柔性隔层14实际粘接位置的波动的影响，进一步确保柔性隔层14对剪切应力的分散作用。
参考图6C，在一些实施例中，所述柔性隔层14的厚度T满足：0.07*t≤T≤0.8*t。t为所述第一极片11和所述第二极片12中与所述柔性隔层14相邻设置的极片在所述电极组件10初次充放电后的厚度。
在电极组件10循环膨胀时，柔性隔层14能够对极片端部形成的台阶给相邻极片层的剪切应力进行分散，降低破裂风险，但端部区域15在设置柔性隔层14后相对于相邻极片层的台阶高度也增加了。
如果柔性隔层14的厚度T相比于极片厚度t过小，则过薄的柔性隔层14难以有效地分散台阶处的剪切应力，增大了极片断裂的风险。如果柔性隔层14的厚度T相比于极片厚度t过大，则端部区域15在设置过厚的柔性隔层14之后形成了更高的台阶，又会导致台阶处剪切应力的增加。
因此，通过使柔性隔层14的厚度T大于等于0.07倍的极片厚度t，且小于等于0.8倍的极片厚度t，可以在电极组件10循环膨胀时有效地分散台阶处的剪切应力，降低极片因过大的剪切应力断裂的风险。
在一些实施例中，厚度T满足：0.2*t≤T≤0.5*t，例如T等于0.3*t、0.36*t、0.42*t等。通过使柔性隔层14的厚度T大于等于0.2倍的极片厚度t，且小于等于0.5倍的极片厚度t，可以在电极组件10循环膨胀时更有效地分散台阶处的剪切应力，进一步降低极片因过大的剪切应力断裂的风险。
为了说明柔性隔层的作用，下面通过多个实验例进行验证说明。在该多个实验例中，作为负极极片的第一极片和作为正极极片的第二极片均在末端的端部区域设置了位于端部区域和其内侧隔膜段之间的柔性隔层，该柔性隔层为粘接面与隔膜段粘接的单面胶纸。该单面胶纸的长度L为10mm，宽度W为87mm，凸出长度L1为5mm。对使用不同厚度的单面胶纸粘胶后的电极结构进行入壳封装，得到圆柱形电池单体，并进行循环测试，测试条件为45℃，以0.5C(即电池单体容量C的1/2倍)倍率进行充放电，循环深度为10％电池荷电状态SOC到100％SOC，并在电池单体容量衰减到80％时，测试截止。对测试后的电极组件进行拆解，观察极片断裂情况。
参考上述实施例，在多个实验例中，极片厚度t为160μm，0.07倍的t为11.2μm，0.8倍的t为128μm，柔性隔层14的厚度T分别为0μm、5μm和150μm，这些取值均在11.2μm到128μm的数值范围之外，可观察到端部区域台阶处对应的内圈负极极片已断裂。在另两组实验例中，极片厚度t为160μm，柔性隔层14的厚度T分别为30μm和60μm，这些取值均在11.2μm到128μm的数值范围之内，可观察到端部区域台阶处对应的内圈负极极片未发生断裂。
图7A是本公开电极组件的一些实施例的结构示意图。图7B是图7A的尺寸示意图。图7C是图7A中第三单面胶纸粘贴在隔膜的第三末端的截面示意图。参考图3 和图7A，在一些实施例中，所述第一极片11在所述卷绕方向r上的第一末端11B所在极片层和所述第二极片12在所述卷绕方向r上的第二末端12B所在极片层均位于所述隔膜13在所述卷绕方向r上的第三末端133所在隔膜层的内侧，且所述第三末端133在所述卷绕结构100的周向上相对于所述第一末端11B和所述第二末端12B均凸出，所述第三末端133通过第三单面胶纸16在所述电极组件10上粘接固定。
在图7A中，第三末端133的边缘133a通过第三单面胶纸16进行粘接固定，由于第三单面胶纸16的一部分与第三末端133粘接，另一部分与第三末端133内侧的隔膜层粘接，使得第三单面胶纸16跨过边缘133a。第三单面胶纸16的结构可参考前述第一单面胶纸，这里不再赘述。
将第一末端11B所在极片层和第二末端12B所在极片层均设置在第三末端133所在隔膜层的内侧，并使得第三末端133在卷绕结构100的周向上相对于第一末端11B和第二末端12B均凸出，可以确保隔膜13层对第一极片11和第二极片12的包裹作用，避免极片末端露出。通过在隔膜13的第三末端133设置第三单面胶纸16来实现粘接固定，可实现隔膜13收尾固定效果，确保卷绕后的电极组件10不会松散。
参考图7B，在一些实施例中，所述卷绕结构100为圆柱形卷绕结构，所述第三单面胶纸16在所述卷绕方向r上的长度L2满足：0.07π*D≤L2≤1.5π*D。D为所述圆柱形卷绕结构的直径。
第三单面胶纸16在卷绕方向r上的长度L2与圆柱形卷绕结构的横截面周长π*D的关系体现了第三单面胶纸16对圆柱形卷绕结构外周的包裹程度。如果第三单面胶纸16的长度L2相比于圆柱形卷绕结构的横截面周长π*D过小，则影响第三单面胶纸16所实现隔膜13收尾固定效果，存在电极组件10因粘接固定不牢而松散的风险。
如果第三单面胶纸16的长度L2相比于圆柱形卷绕结构的横截面周长π*D过大，则可能因第三单面胶纸16过多交叠而增加厚度，从而增加电极组件10的横截面尺寸，导致电极组件10进入电池单体的壳体21的难度增加。
因此，通过使长度L2大于等于0.07π倍的直径D，且小于等于1.5π倍的直径D，可以使电极组件10粘接牢靠不松散，也能够方便进入电池单体的壳体21。
在一些实施例中，长度L2满足：0.25π*D≤L2≤1.05π*D，例如L2等于0.4π*D、0.75π*D、π*D等。通过使长度L2大于等于0.25π倍的直径D，且小于等于1.05π倍的直径D，可以使电极组件10粘接更加牢靠不松散，并且进一步方便电极组件10进入电池单体的壳体21。
进一步地，长度L2可满足：π*D<L2≤1.05π*D，例如L2等于1.02π*D、1.03π*D等。通过使长度L2大于π倍的直径D，且小于等于1.05π倍的直径D，可以使第三单面胶纸16在粘接固定隔膜13的末端的同时有少量交叠，这样就减少了第三单面胶纸16的端部在隔膜13上形成的台阶数量，降低第三单面胶纸16形成的台阶在电极组件10循环膨胀时对极片的剪切应力的作用，降低极片在剪切应力作用下断裂的风险。
参考图7A，在一些实施例中，所述卷绕结构100为圆柱形卷绕结构，所述第三单面胶纸16设置为两个，两个所述第三单面胶纸16沿所述圆柱形卷绕结构的轴线ax的延伸方向上间隔排布。通过设置沿轴线ax的延伸方向间隔排布的两个第三单面胶纸16，可以在满足粘接固定要求的同时，避免第三单面胶纸16对电极组件10形成过大的束缚力，从而降低电极组件10的集流体基材的延伸率，并且还减少了第三单面胶纸16的胶纸用量。
参考图7A和图7B，在一些实施例中，在所述圆柱形卷绕结构的轴线ax的延伸方向上，两个所述第三单面胶纸16中邻近所述圆柱形卷绕结构的第一端100A的所述第三单面胶纸16到所述第一端100A的最小距离为h1，两个所述第三单面胶纸16中邻近所述圆柱形卷绕结构的第一端100A的所述第三单面胶纸16的宽度为W2，两个所述第三单面胶纸16中邻近所述圆柱形卷绕结构的第二端100B的所述第三单面胶纸16到所述第二端100B的最小距离为h2。
两个所述第三单面胶纸16中邻近所述圆柱形卷绕结构的第二端100B的所述第三单面胶纸16的宽度为W3，h1、W2、h2和W3满足：0≤h1≤0.07*H，0≤h2≤0.07*H，0.05*H≤W2≤0.12*H，0.05*H≤W3≤0.12*H。例如h1等于0.02*H、0.04*H、0.055*H等，h2等于0.015*H、0.035*H、0.56*H等，W2等于0.07*H、0.09*H、0.11*H，W3等于0.06*H、0.08*H、0.1*H。H为所述圆柱形卷绕结构在所述圆柱形卷绕结构的轴线ax的延伸方向上的高度。
两个第三单面胶纸16分别到圆柱形卷绕结构的两端的最小距离h1和h2体现了第三单面胶纸16靠近卷绕结构100端部的程度，而宽度W2和W3体现了第三单面胶纸16覆盖的范围大小。
通过使h1和h2满足0≤h1≤0.07*H，0≤h2≤0.07*H，并使W2和W3满足0.05*H≤W2≤0.12*H，0.05*H≤W3≤0.12*H，可以使第三单面胶纸16主要粘贴在极片两侧的活性材料涂布减薄区，这样可适用更大厚度范围的第三单面胶纸16，即使采用相对较厚的第三单面胶纸16也不容易影响电极组件10进入电池单体的壳体21。
参考图7C，在一些实施例中，所述第三单面胶纸16的厚度T1满足：5μm≤T1≤120μm。例如T1等于10μm、40μm、85μm、115μm等。过薄的第三单面胶纸16抗拉强度较低，存在着在电极组件10循环膨胀时第三单面胶纸16在拉力作用下断裂而导致电极组件10松散的风险。过厚的第三单面胶纸16会增大电极组件10的外轮廓尺寸，导致电极组件10进入壳体21的难度增加。
因此，在最小距离h1、h2和宽度W2、W3满足合适取值范围时，通过使第三单面胶纸16的厚度T1满足5μm≤T1≤120μm，可使得第三单面胶纸16具备合适的抗拉强度，降低在电极组件10循环膨胀时第三单面胶纸16在拉力作用下断裂的风险，并使粘接第三单面胶纸16的电极组件10整体外轮廓尺寸更合适，避免电极组件10进入壳体21时与壳体21干涉。
参考图7A和图7B，在一些实施例中，在所述圆柱形卷绕结构的轴线ax的延伸方向上，两个所述第三单面胶纸16中邻近所述圆柱形卷绕结构的第一端100A的所述第三单面胶纸16到所述第一端的最小距离为h1，两个所述第三单面胶纸16中邻近所述圆柱形卷绕结构的第一端100A的所述第三单面胶纸16的宽度为W2，两个所述第三单面胶纸16中邻近所述圆柱形卷绕结构的第二端100B的所述第三单面胶纸16到所述第二端的最小距离为h2。两个所述第三单面胶纸16中邻近所述圆柱形卷绕结构的第二端100B的所述第三单面胶纸16的宽度为W3，h1、W1、h2和W2满足：0.07*H≤h1≤0.25*H，0.07*H≤h2≤0.25*H，0.05*H≤W2≤0.23*H，0.05*H≤W3≤0.23*H。例如h1等于0.09*H、0.15*H、0.22*H等，h2等于0.1*H、0.18*H、0.24*H等，W2等于0.12*H、0.18*H、0.22*H，W3等于0.1*H、0.16*H、0.2*H。H为所述圆柱形卷绕结构在所述圆柱形卷绕结构的轴线ax的延伸方向上的高度。
两个第三单面胶纸16分别到圆柱形卷绕结构的两端的最小距离h1和h2体现了第三单面胶纸16靠近卷绕结构100端部的程度，而宽度W2和W3体现了第三单面胶纸16覆盖的范围大小。
通过使h1和h2满足0.07*H≤h1≤0.25*H，0.07*H≤h2≤0.25*H，并使W2和W3满足0.05*H≤W2≤0.23*H，0.05*H≤W3≤0.23*H，可以使第三单面胶纸16粘贴极片两侧的活性材料涂布减薄区之外还粘贴在活性材料涂布正常厚度的区域，因此适用相对较小厚度范围的第三单面胶纸16，并且通过增加第三单面胶纸16的宽度来提高粘接的牢靠程度，使电极组件10不容易松散。
参考图7C，在一些实施例中，所述第三单面胶纸16的厚度T1满足： 5μm≤T1≤60μm。例如T1等于12μm、24μm、32μm、46μm、52μm等。过薄的第三单面胶纸16抗拉强度较低，存在着在电极组件10循环膨胀时第三单面胶纸16在拉力作用下断裂而导致电极组件10松散的风险。过厚的第三单面胶纸16会增大电极组件10的外轮廓尺寸，导致电极组件10进入壳体21的难度增加。
因此，在最小距离h1、h2和宽度W2、W3满足合适取值范围时，通过使第三单面胶纸16的厚度T1满足5μm≤T1≤60μm，可使得第三单面胶纸16具备合适的抗拉强度，降低在电极组件10循环膨胀时第三单面胶纸16在拉力作用下断裂的风险，并使粘接第三单面胶纸16的电极组件10整体外轮廓尺寸更合适，避免电极组件10进入壳体21时与壳体21干涉。
基于本公开上述电极组件的各个实施例，本公开实施例还提供了电池单体，包括前述的电极组件。采用前述电极组件实施例的电池单体可获得更优的使用可靠性。
在本公开的一个方面，提供一种电池，包括前述的电池单体。采用前述电池单体的电池可获得更优的使用可靠性。
在本公开的一个方面，提供一种用电装置，包括前述的电池。采用前述电池的用电装置可获得更优的使用可靠性。
基于本公开的前述电池单体的各个实施例，本公开还提供了采用前述电池单体实施例的电池的实施例。该电池包括前述任一种实施例的电池单体。采用前述电池单体实施例的电池可获得更优的使用可靠性。
在本公开的一个方面，提供一种用电设备，包括前述的电池。采用前述电池的用电设备可获得更优的使用可靠性。
虽然已经参考优选实施例对本公开进行了描述，但在不脱离本公开的范围的情况下，可以对其进行各种改进并且可以用等效物替换其中的部件。尤其是，只要不存在结构冲突，各个实施例中所提到的各项技术特征均可以任意方式组合起来。本公开并不局限于文中公开的特定实施例，而是包括落入权利要求的范围内的所有技术方案。

Claims (30)

  1. 一种电极组件(10)，包括：第一极片(11)、第二极片(12)和设于所述第一极片(11)和所述第二极片(12)之间的隔膜(13)，所述第一极片(11)、所述第二极片(12)和所述隔膜(13)沿卷绕方向(r)卷绕并形成卷绕结构(100)；
    其中，所述第一极片(11)和所述第二极片(12)中的至少一个在所述卷绕方向(r)上的至少一端的端部区域(15)和所述隔膜(13)上与所述端部区域(15)相邻的隔膜段之间设有柔性隔层(14)，所述柔性隔层(14)在所述卷绕结构(100)的周向上凸出于所述端部区域(15)的边缘。
  2. 根据权利要求1所述的电极组件(10)，其中，所述端部区域(15)和所述隔膜段中之一与所述柔性隔层(14)粘接，所述端部区域(15)和所述隔膜段中另一与所述柔性隔层(14)可滑动地接触。
  3. 根据权利要求2所述的电极组件(10)，其中，所述柔性隔层(14)包括至少一个单面胶纸。
  4. 根据权利要求1～3任一所述的电极组件(10)，其中，所述隔膜段包括：
    第一隔膜段(131)，位于所述端部区域(15)内侧；
    第二隔膜段(132)，位于所述端部区域(15)外侧；
    其中，所述柔性隔层(14)包括与所述第一隔膜段(131)和所述第二隔膜段(132)中之一粘接的第一单面胶纸(141)。
  5. 根据权利要求1～3任一所述的电极组件(10)，其中，所述隔膜段包括：
    第一隔膜段(131)，位于所述端部区域(15)内侧；
    第二隔膜段(132)，位于所述端部区域(15)外侧；
    其中，所述柔性隔层(14)包括与所述第一隔膜段(131)和所述第二隔膜段(132)分别粘接的第一单面胶纸(141)和第二单面胶纸(142)，所述第一单面胶纸(141)在所述卷绕结构(100)的周向上相对于所述端部区域(15)的边缘的凸出长度与所述第二单面胶纸(142)在所述卷绕结构(100)的周向上相对于所述端部区域(15)的边缘的凸出长度相同或不同。
  6. 根据权利要求1～3任一所述的电极组件(10)，其中，所述柔性隔层(14)包括第一单面胶纸(141)，所述第一单面胶纸(141)通过折叠方式与所述端部区域(15)的内侧表面和外侧表面均粘接。
  7. 根据权利要求1～3任一所述的电极组件(10)，其中，所述柔性隔层(14)包括与所述端部区域(15)的内侧表面和外侧表面分别粘接的第一单面胶纸(141)和第二单面胶纸(142)，所述第一单面胶纸(141)在所述卷绕结构(100)的周向上相对于所述端部区域(15)的边缘的凸出长度与所述第二单面胶纸(142)在所述卷绕结构(100)的周向上相对于所述端部区域(15)的边缘的凸出长度相同或不同。
  8. 根据权利要求1～7任一所述的电极组件(10)，其中，所述第一极片(11)为负极极片，所述第二极片(12)为正极极片。
  9. 根据权利要求8所述的电极组件(10)，其中，在所述卷绕结构(100)中，所述第一极片(11)在所述卷绕方向(r)上的第一末端(11B)所在极片层位于所述第二极片(12)在所述卷绕方向(r)上的第二末端(12B)所在极片层的外侧，且所述第一末端(11B)在所述卷绕结构(100)的周向上相对于所述第二末端(12B)凸出，所述第一末端(11B)所在极片层的端部区域(15)和所述隔膜(13)上与所述第一末端(11B)所在极片层的端部区域(15)相邻的隔膜段之间设有柔性隔层(14)，所述第二末端(12B)所在极片层的端部区域(15)和所述隔膜(13)上与所述第二末端(12B)所在极片层的端部区域(15)相邻的隔膜段之间设有柔性隔层(14)。
  10. 根据权利要求8或9所述的电极组件(10)，其中，在所述卷绕结构(100)中，所述第一极片(11)在所述卷绕方向(r)上的第一始端(11A)所在极片层位于所述第二极片(12)在所述卷绕方向(r)上的第二始端(12A)所在极片层的内侧，且所述第一始端(11A)在所述卷绕结构(100)的周向上相对于所述第二始端(12A)凸出，所述第二始端(12A)所在极片层的端部区域(15)和所述隔膜(13)上与所述第二始端(12A)所在极片层的端部区域(15)相邻的隔膜段之间设有柔性隔层(14)。
  11. 根据权利要求1～10任一所述的电极组件(10)，其中，所述第一极片(11)和所述第二极片(12)中的至少一个包括：
    集流体基材(10A)；
    活性物质层(10B)，至少设置在所述集流体基材(10A)邻近所述隔膜(13)一侧的表面；
    其中，在所述卷绕方向(r)上，所述集流体基材(10A)的至少一端对应于所述端部区域(15)的表面部分未被所述活性物质层(10B)覆盖。
  12. 根据权利要求1～11任一所述的电极组件(10)，其中，所述卷绕结构(100)为圆柱形卷绕结构，所述柔性隔层(14)在所述卷绕方向(r)上的长度L满足：
    0.03π*D≤L≤0.25π*D；
    其中，D为所述圆柱形卷绕结构的直径。
  13. 根据权利要求12所述的电极组件(10)，其中，长度L满足：0.07π*D≤L≤0.13π*D。
  14. 根据权利要求1～13任一所述的电极组件(10)，其中，所述卷绕结构(100)为圆柱形卷绕结构，所述柔性隔层(14)在所述圆柱形卷绕结构的轴线方向上的宽度W满足：
    W1≤W≤H；
    其中，W1为所述端部区域(15)在所述圆柱形卷绕结构的轴线方向上的宽度，H为所述圆柱形卷绕结构在所述圆柱形卷绕结构的轴线方向上的高度。
  15. 根据权利要求1～14任一所述的电极组件(10)，其中，所述柔性隔层(14)在所述卷绕结构(100)的周向上相对于所述端部区域(15)的边缘的凸出长度L1满足：
    (1/4)*L≤L1≤(3/4)*L；
    其中，L为所述柔性隔层(14)在所述卷绕方向(r)上的长度。
  16. 根据权利要求15所述的电极组件(10)，其中，所述凸出长度L1满足：(1/3)*L≤L1≤(2/3)*L。
  17. 根据权利要求1～16任一所述的电极组件(10)，其中，所述柔性隔层(14)的厚度T满足：
    0.07*t≤T≤0.8*t；
    其中，t为所述第一极片(11)和所述第二极片(12)中与所述柔性隔层(14)相邻设置的极片在所述电极组件(10)初次充放电后的厚度。
  18. 根据权利要求17所述的电极组件(10)，其中，厚度T满足：0.2*t≤T≤0.5*t。
  19. 根据权利要求1～18任一所述的电极组件(10)，其中，所述第一极片(11)在所述卷绕方向(r)上的第一末端(11B)所在极片层和所述第二极片(12)在所述卷绕方向(r)上的第二末端(12B)所在极片层均位于所述隔膜(13)在所述卷绕方向(r)上的第三末端(133)所在隔膜层的内侧，且所述第三末端(133)在所述卷绕结构(100)的周向上相对于所述第一末端(11B)和所述第二末端(12B)均凸出，所述第三末端(133)通过第三单面胶纸(16)在所述电极组件(10)上粘接固定。
  20. 根据权利要求19所述的电极组件(10)，其中，所述卷绕结构(100)为圆 柱形卷绕结构，所述第三单面胶纸(16)在所述卷绕方向(r)上的长度L2满足：
    0.07π*D≤L2≤1.5π*D；
    其中，D为所述圆柱形卷绕结构的直径。
  21. 根据权利要求20所述的电极组件(10)，其中，长度L2满足：0.25π*D≤L2≤1.05π*D。
  22. 根据权利要求21所述的电极组件(10)，其中，长度L2满足：π*D<L2≤1.05π*D。
  23. 根据权利要求19～22任一所述的电极组件(10)，其中，所述卷绕结构(100)为圆柱形卷绕结构，所述第三单面胶纸(16)设置为两个，两个所述第三单面胶纸(16)沿所述圆柱形卷绕结构的轴线(ax)的延伸方向间隔排布。
  24. 根据权利要求23所述的电极组件(10)，其中，在所述圆柱形卷绕结构的轴线(ax)的延伸方向上，两个所述第三单面胶纸(16)中邻近所述圆柱形卷绕结构的第一端(100A)的所述第三单面胶纸(16)到所述第一端(100A)的最小距离为h1，两个所述第三单面胶纸(16)中邻近所述圆柱形卷绕结构的第一端(100A)的所述第三单面胶纸(16)的宽度为W2，两个所述第三单面胶纸(16)中邻近所述圆柱形卷绕结构的第二端(100B)的所述第三单面胶纸(16)到所述第二端(100B)的最小距离为h2，两个所述第三单面胶纸(16)中邻近所述圆柱形卷绕结构的第二端(100B)的所述第三单面胶纸(16)的宽度为W3，h1、W2、h2和W3满足：
    0≤h1≤0.07*H，0≤h2≤0.07*H，0.05*H≤W2≤0.12*H，0.05*H≤W3≤0.12*H；
    其中，H为所述圆柱形卷绕结构在所述圆柱形卷绕结构的轴线(ax)的延伸方向上的高度。
  25. 根据权利要求24所述的电极组件(10)，其中，所述第三单面胶纸(16)的厚度T1满足：5μm≤T1≤120μm。
  26. 根据权利要求23所述的电极组件(10)，其中，在所述圆柱形卷绕结构的轴线(ax)的延伸方向上，两个所述第三单面胶纸(16)中邻近所述圆柱形卷绕结构的第一端(100A)的所述第三单面胶纸(16)到所述第一端的最小距离为h1，两个所述第三单面胶纸(16)中邻近所述圆柱形卷绕结构的第一端(100A)的所述第三单面胶纸(16)的宽度为W2，两个所述第三单面胶纸(16)中邻近所述圆柱形卷绕结构的第二端(100B)的所述第三单面胶纸(16)到所述第二端的最小距离为h2，两个所述第三单面胶纸(16)中邻近所述圆柱形卷绕结构的第二端(100B)的所述第三单面胶纸(16)的宽度为W3，h1、W1、h2和W2满足：
    0.07*H≤h1≤0.25*H，0.07*H≤h2≤0.25*H，0.05*H≤W2≤0.23*H，0.05*H≤W3≤0.23*H；
    其中，H为所述圆柱形卷绕结构在所述圆柱形卷绕结构的轴线(ax)的延伸方向上的高度。
  27. 根据权利要求26所述的电极组件(10)，其中，所述第三单面胶纸(16)的厚度T1满足：5μm≤T1≤60μm。
  28. 一种电池单体(20)，包括：权利要求1～27任一所述的电极组件(10)。
  29. 一种电池(30)，包括权利要求28所述的电池单体(20)。
  30. 一种用电装置，包括权利要求29所述的电池(30)。
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