WO2025246760A1 - 二次电池和电子装置 - Google Patents

二次电池和电子装置

Info

Publication number
WO2025246760A1
WO2025246760A1 PCT/CN2025/091483 CN2025091483W WO2025246760A1 WO 2025246760 A1 WO2025246760 A1 WO 2025246760A1 CN 2025091483 W CN2025091483 W CN 2025091483W WO 2025246760 A1 WO2025246760 A1 WO 2025246760A1
Authority
WO
WIPO (PCT)
Prior art keywords
segment
secondary battery
edge
region
layer
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/CN2025/091483
Other languages
English (en)
French (fr)
Inventor
吕南希
于利民
李晟开
詹东欧
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ningde Amperex Technology Ltd
Original Assignee
Ningde Amperex Technology Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ningde Amperex Technology Ltd filed Critical Ningde Amperex Technology Ltd
Publication of WO2025246760A1 publication Critical patent/WO2025246760A1/zh
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings; Jackets or wrappings
    • H01M50/102—Primary casings; Jackets or wrappings characterised by their shape or physical structure
    • H01M50/105—Pouches or flexible bags
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H01M10/0585—Construction or manufacture of accumulators having only flat construction elements, i.e. flat positive electrodes, flat negative electrodes and flat separators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/463—Separators, membranes or diaphragms characterised by their shape
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • This application relates to the field of energy storage technology, and in particular to a secondary battery and an electronic device having the aforementioned secondary battery.
  • Pouch batteries typically consist of a packaging bag and electrode assemblies housed within it. To improve the energy density of the battery, the distance between the electrode assemblies and the inner surface of the packaging bag can be reduced. However, if this distance is too small, part of the separator membrane from the electrode assemblies may penetrate into the area to be sealed within the packaging bag. Once this area is sealed, the separator membrane that has entered the sealing area may damage the packaging bag, leading to leakage, increased boundary voltage (IV value), and other safety hazards. Therefore, achieving a balance between high energy density and safety performance in pouch batteries is a pressing issue that needs to be addressed.
  • This application provides a secondary battery, including a packaging bag, an electrode assembly, and a conductive plate.
  • the packaging bag includes a receiving portion and a first seal.
  • the electrode assembly is disposed within the receiving portion, and the conductive plate is electrically connected to the electrode assembly and extends out of the packaging bag.
  • the direction from the electrode assembly to the conductive plate is a first direction.
  • the electrode assembly includes a positive electrode, a negative electrode, and a separator, which are sequentially stacked in a second direction to form a laminated structure.
  • the electrode assembly includes N layers of separator in the second direction, and the N layers of separator include n layers of first separator, where n ⁇ N.
  • the first separator includes a main body region and a first edge region connected in a third direction.
  • the receiving portion includes a first sidewall and a second sidewall disposed opposite to each other in a third direction, and the first seal is connected to the first sidewall.
  • the first seal includes a first segment connected to the first sidewall and a second segment connected to the first segment along the extension direction of the first seal. At least a portion of each first edge region is disposed within the first segment. Define the thickness of the first segment as H1 , the thickness of the second segment as H2 , and H2 ⁇ H1 .
  • the first direction, the second direction, and the third direction are all perpendicular to each other.
  • the first segment has a larger thickness, resulting in lower encapsulation pressure and/or temperature. This reduces the risk of the metal layer being exposed due to damage to the first adhesive layer within the first sealing edge, thereby reducing the risk of the metal layer contacting and being corroded by the electrolyte. This mitigates potential hazards such as leakage from the packaging bag and increased edge voltage, improving the safety performance of the secondary battery.
  • the second segment has a smaller thickness, allowing for higher encapsulation pressure and/or temperature, resulting in higher overall encapsulation strength for the first sealing edge. This further reduces the risk of leakage from the packaging bag.
  • the first edge region is at least partially located within the first segment, the risk of leakage and increased edge voltage is reduced. Therefore, the gap between the negative electrode and the first sidewall of the packaging bag can be reduced accordingly, thereby increasing the energy density of the secondary battery.
  • the secondary battery of this application achieves a balance between high safety performance and high energy density.
  • the electrode assembly can be fixed inside the packaging bag. This reduces the shaking of the electrode assembly inside the packaging bag during mechanical abuse and further reduces the risk of short circuit between the positive and negative electrode plates caused by the first separator folding or wrinkling during mechanical abuse, thereby further improving the safety performance of the secondary battery.
  • 0.11mm ⁇ H1 ⁇ 0.40mm, and 0.10mm ⁇ H2 ⁇ 0.20mm If the thickness H1 of the first segment is too large, it means that the packaging pressure and/or temperature used to encapsulate the first segment is too low. This may result in insufficient restraint on the first edge region, failing to properly fix the electrode assembly inside the packaging bag, thus failing to improve the safety performance of the secondary battery under mechanical abuse. If H1 is too small, it means that the packaging pressure and/or temperature used to encapsulate the first segment is too high. This will cause the first adhesive layer in the first segment to be damaged, resulting in potential hazards such as leakage from the packaging bag and increased edge voltage.
  • limiting H1 within the above range can balance the restraint effect of the first segment on the first edge region with the preservation of the first adhesive layer within the first segment, thereby enabling the secondary battery to have higher safety performance. If the thickness H2 of the second segment is too large, it means that the encapsulation pressure and/or temperature used to package the second segment is too low. This will result in insufficient encapsulation strength and inadequate encapsulation pull, potentially leading to leakage. If H2 is too small, it means that the encapsulation pressure and/or temperature used to package the second segment is too high. This could damage the first adhesive layer within the second segment, causing problems such as increased edge voltage. Therefore, limiting H2 within the above range can balance the encapsulation reliability and safety performance of the secondary battery.
  • the length of the first segment is L1
  • the length of the second segment is L2
  • 0.8mm ⁇ L1 ⁇ 2mm , 0.8mm ⁇ L2 ⁇ 2mm Limiting the lengths of the first and second segments within the above range can reduce the impact on the energy density of the secondary battery when the length of the first or second segment is too large.
  • L1 is not less than 0.8mm, the first edge region can fully enter the first segment, thereby more firmly fixing the electrode assembly to the packaging bag.
  • L2 is not less than 0.8mm, which can make the first sealing edge have high overall sealing strength, and can further reduce the risk of leakage from the packaging bag.
  • the length of the first edge region within the first segment is L3 , where 0.4mm ⁇ L3 ⁇ L1 .
  • This can further reduce the gap between the negative electrode and the first sidewall of the packaging bag, thereby further improving the energy density of the secondary battery.
  • the electrode assembly is better fixed to the packaging bag. In the event of mechanical abuse of the secondary battery, the shaking of the electrode assembly within the packaging bag can be further reduced, and the risk of short circuit between the positive and negative electrode due to folding or wrinkling of the first separator during mechanical abuse can also be further reduced.
  • the first release film includes a substrate layer, which includes a first substrate region located in the main body region and a second substrate region located in the first edge region.
  • the packaging bag includes a first sealing film and a second sealing film disposed opposite to each other, which are bonded together to form a first edge seal.
  • the first edge seal includes a first protective layer, a first metal layer, a first adhesive layer, a second metal layer, and a second protective layer stacked sequentially, with the second substrate region bonded to the first adhesive layer. Since both the substrate layer and the first adhesive layer are polymer materials, it facilitates full fusion and bonding between the first edge region and the first adhesive layer, thereby improving the bonding strength between the first edge region and the first segment.
  • the first separator further includes an insulating layer containing inorganic particles.
  • the insulating layer is disposed on the first substrate region, and the second substrate region extends beyond the insulating layer.
  • the insulating layer on the first substrate region can improve the electrolyte wetting effect in the main body region, and since no insulating layer is disposed on the second substrate region within the first segment, both the substrate layer and the first adhesive layer are polymer materials, which facilitates the full fusion and adhesion between the first edge region and the first adhesive layer, thereby improving the bonding strength between the first edge region and the first segment.
  • the first separator further includes an insulating layer containing inorganic particles.
  • the insulating layers are respectively disposed on the first substrate region and the second substrate region.
  • the insulating layer disposed on the second substrate region is bonded to the first adhesive layer.
  • the insulating layer on the first substrate region can improve the electrolyte wetting effect in the main body region, and an insulating layer is also disposed on the first edge region within the first segment. Therefore, the main body region and the first edge region of the first separator can be integrally formed, thereby simplifying the process.
  • the first separator further includes a first adhesive layer, which is disposed on the side of the insulating layer away from the substrate layer.
  • the first adhesive layer can improve the adhesion between the first separator and the positive or negative electrode sheet, reducing the risk of damage to the electrode assembly structure during mechanical abuse.
  • no insulating layer or first adhesive layer is disposed on the first edge region within the first sealing edge. The first edge region is bonded to the first adhesive layer through the second substrate region.
  • Both the substrate layer and the first adhesive layer are polymer materials, which facilitates the full fusion and bonding of the first edge region and the first adhesive layer, thereby improving the bonding strength between the first edge region and the first segment.
  • the first separator further includes a first adhesive layer.
  • the first adhesive layer is disposed on the side of the insulating layer away from the substrate layer.
  • the first adhesive layer disposed on the second substrate region is bonded to the first adhesive layer.
  • the first adhesive layer can improve the adhesion between the first separator and the positive or negative electrode sheet, reduce the risk of damage to the electrode assembly structure during mechanical abuse, and since the insulating layer and the first adhesive layer are also disposed on the first edge region within the first sealing edge, the main body region and the first edge region of the first separator can be integrally formed, thereby simplifying the process.
  • the first adhesive layer includes a first polymer material
  • the substrate layer includes a second polymer material.
  • the first polymer material and the second polymer material are each independently selected from at least one of polyethylene, polypropylene, polyurethane, and polyimide. Therefore, the substrate layer and the first adhesive layer have similar or identical properties, which is more conducive to the full fusion and adhesion between the first edge region and the first adhesive layer.
  • the first polymer material and the second polymer material are the same material. Therefore, the substrate layer and the first adhesive layer have the same properties, which is more conducive to the full fusion and adhesion between the first edge region and the first adhesive layer.
  • H1 d1 + d2 + n ⁇ S + X1
  • H2 d1 + d2 + X2
  • d1 the thickness of the first encapsulation film located in the receiving portion
  • d2 the thickness of the second encapsulation film located in the receiving portion
  • S is the thickness of the main body region
  • X1 and X2 are adjustment coefficients, -2mm ⁇ X1 ⁇ 0mm, -2mm ⁇ X2 ⁇ 0mm.
  • the outermost part of the electrode assembly in the second direction is a first separator. Therefore, the outermost first separator can bind at least part of the positive and negative electrode plates while fixing the electrode assembly to the packaging bag more securely, further reducing the shaking of the electrode assembly inside the packaging bag when the secondary battery is mechanically abused.
  • the edges of two adjacent first edge regions in the second direction are directly connected within the first sealing edge. Therefore, the first separator can bind at least part of the positive and negative electrode sheets while securing the electrode assembly to the packaging bag more securely. In the event of mechanical abuse of the secondary battery, it can further reduce the shaking of the electrode assembly within the packaging bag, and further reduce the risk of short circuits caused by the first separator folding or wrinkling during mechanical abuse.
  • the packaging bag includes a second sealing film
  • the second segment includes a first segment connected to the first segment and a second segment connected to the first segment along the extension direction of the first sealing edge.
  • the second segment is bent toward the first segment in a direction away from the second sealing film. Therefore, the size of the secondary battery in the third direction can be reduced, further improving the energy density of the secondary battery.
  • the bending point is located in the thinner second segment, which facilitates bending the second segment and also reduces the risk of the second segment opening up compared to the first segment. In addition, it can also reduce the risk that the exposed metal layer at the edge of the second segment is easily short-circuited to the outside, further improving the safety performance of the secondary battery.
  • the secondary battery further includes a first adhesive member, through which the second segment is adhered to the first segment. Therefore, the risk of the second segment opening apart relative to the first segment can be further reduced.
  • the first segment is bent toward the first sidewall in a direction away from the second encapsulation film, and the second segment is disposed between the first segment and the first sidewall in a third direction. Therefore, the size of the secondary battery in the third direction can be further reduced, thereby further improving the energy density of the secondary battery.
  • the secondary battery further includes a second adhesive member, through which the second segment is adhered to the first sidewall.
  • the second adhesive member can reduce the risk of the first segment opening relative to the first sidewall.
  • the distance between the negative electrode and the first sidewall in the third direction is D, 0.2mm ⁇ D ⁇ 2mm, which can reduce the gap between the negative electrode and the first sidewall, thereby enabling the secondary battery to have a higher energy density.
  • the packaging bag further includes a second sealing edge connected to the second sidewall.
  • the second sealing edge includes a third segment connected to the second sidewall and a fourth segment connected to the third segment along the extension direction of the second sealing edge.
  • the first separator also includes a second edge region, and the first edge region, the main body region, and the second edge region are sequentially connected in a third direction. Viewed from a second direction, the second edge region extends from the main body region and beyond the negative electrode sheet. At least a portion of each second edge region is located within the third segment.
  • the thickness of the third segment is defined as H3
  • the thickness of the fourth segment is defined as H4 , where H4 ⁇ H3 .
  • the thickness of the third segment By setting the thickness of the third segment to be smaller, the corresponding encapsulation pressure and/or temperature used is lower, which can reduce the risk of the metal layer being exposed due to damage to the second adhesive layer within the second sealing edge, thereby reducing the risk of the metal layer contacting the electrolyte and being corroded by the electrolyte, thus reducing the hidden dangers such as leakage of the packaging bag and increase in edge voltage, and further improving the safety performance of the secondary battery.
  • the fourth segment is thinner, allowing for higher encapsulation pressure and/or temperature. This results in higher encapsulation strength compared to the third segment, further reducing the risk of leakage from the packaging bag.
  • the second edge region is at least partially located within the third segment, the risks of leakage and increased edge voltage are reduced. This allows for a corresponding reduction in the gap between the negative electrode and the second sidewall of the packaging bag, thereby further improving the energy density of the secondary battery. Additionally, because the second edge region is at least partially located within the third segment, mechanical abuse of the secondary battery reduces the shaking of the electrode assembly within the packaging bag. It also further reduces the risk of short circuits between the positive and negative electrodes caused by folding or wrinkling of the first separator during mechanical abuse, thus further improving the safety performance of the secondary battery.
  • a second aspect of this application also provides an electronic device comprising a battery compartment and a secondary battery as described above.
  • the secondary battery is disposed within the battery compartment.
  • the electronic device is powered by the secondary battery, which balances high energy density and safety performance.
  • Figure 1 is a schematic diagram of the structure of a secondary battery provided in an embodiment of this application when viewed from a second direction.
  • Figure 2 is a cross-sectional view of the secondary battery shown in Figure 1 along section line II-II in some embodiments.
  • Figure 3 is a partial enlarged view of the secondary battery shown in Figure 2.
  • Figure 4 is another enlarged view of the secondary battery shown in Figure 2.
  • Figure 5 is a schematic diagram of the secondary battery shown in Figure 1 before packaging.
  • Figure 6 is a cross-sectional view of the first sealing film of the packaging bag for the secondary battery shown in Figure 5.
  • Figure 7 is a cross-sectional view of the second sealing film of the packaging bag for the secondary battery shown in Figure 5.
  • Figure 8 is a cross-sectional view of the secondary battery shown in Figure 1 in some other embodiments.
  • Figure 9 is a cross-sectional view of the secondary battery shown in Figure 1 in some other embodiments.
  • Figure 10 is a cross-sectional view of the separator of the secondary battery shown in Figure 2 or Figure 3 in some embodiments.
  • Figure 11 is a cross-sectional view of the separator of the secondary battery shown in Figure 2 or Figure 3 in some embodiments.
  • Figure 12 is a cross-sectional view of the separator of the secondary battery shown in Figure 2 or Figure 3 in some embodiments.
  • Figure 13 is a cross-sectional view of the separator of the secondary battery shown in Figure 2 or Figure 3 in some embodiments.
  • Figure 14 is a cross-sectional view of the separator of the secondary battery shown in Figure 2 or Figure 3 in some embodiments.
  • Figure 15 is a cross-sectional view of a secondary battery provided in another embodiment of this application.
  • Figure 16 is a cross-sectional view of a secondary battery provided in another embodiment of this application.
  • Figure 17 is a schematic diagram of the structure of an electronic device provided in one embodiment of this application.
  • Spatial terms such as “above,” may be used herein for convenience in describing the relationship between one element or feature and another element (or feature) or feature (or feature) illustrated in the figures. It should be understood that, in addition to the directions depicted in the figures, spatial terms are intended to include different orientations of the device or apparatus during use or operation. For example, if the device in the figure is flipped, an element described as “above” or “on” other elements or features would be oriented “below” or “under” other elements or features. Therefore, the exemplary term “above” can include both above and below orientations.
  • first, second, third, etc. may be used herein to describe various elements, components, regions, layers, and/or portions, these elements, components, regions, layers, and/or portions should not be limited by these terms. These terms are used to distinguish one element, component, region, layer, or portion from another element, component, region, layer, or portion. Therefore, a first element, component, region, layer, or portion discussed below may be referred to as a second element, component, region, layer, or portion without departing from the teachings of the exemplary embodiments.
  • a secondary battery 100 which includes a packaging bag 10, an electrode assembly 20, an electrolyte (not shown), and a conductive plate.
  • the electrode assembly 20 and the electrolyte are disposed inside the packaging bag 10.
  • the conductive plate may include a first conductive plate 30 and a second conductive plate 40, both of which are electrically connected to the electrode assembly 20 and extend out of the packaging bag 10.
  • the first conductive plate 30 and the second conductive plate 40 can be connected to external components (not shown).
  • a three-dimensional coordinate system is established based on two mutually perpendicular first directions X, second directions Y, and a third direction Z, wherein the direction from the electrode assembly 20 to the first conductive plate 30 or the second conductive plate 40 is the first direction X, the thickness direction of the electrode assembly 20 is the second direction Y, and in some embodiments, the direction from the first conductive plate 30 to the second conductive plate 40 is the third direction Z.
  • the packaging bag 10 includes a receiving portion 14 and a first sealing edge 11.
  • the electrode assembly 20 and electrolyte are disposed within the receiving portion 14.
  • the receiving portion 14 includes a first sidewall 141 and a second sidewall 142 disposed opposite to each other.
  • the surface of the first sidewall 141 extends in the first direction X and the second direction Y
  • the surface of the second sidewall 142 extends in the first direction X and the second direction Y.
  • the receiving portion 14 includes a first endwall 143 and a second endwall 144 disposed opposite to each other.
  • the surface of the first endwall 143 extends in the second direction Y and the third direction Z, and the surface of the second endwall 144 extends in the second direction Y and the third direction Z.
  • the first sealing edge 11 is connected to the first endwall 143.
  • the packaging bag 10 may further include a second sealing edge 12, and the second sealing edge 12 is connected to the second sidewall 142.
  • the packaging bag 10 may further include a third sealing edge 13, and the third sealing edge 13 is connected to the first endwall 143.
  • the first conductive plate 30 and the second conductive plate 40 can both extend out of the packaging bag 10 from the third sealing edge 13.
  • the packaging bag 10 includes a first encapsulation film 101 and a second encapsulation film 102 disposed opposite to each other in the second direction Y.
  • the first encapsulation film 101 and the second encapsulation film 102 are integral structures before encapsulation, and the first encapsulation film 101 and the second encapsulation film 102 are obtained by folding a single encapsulation film.
  • the materials of the first encapsulation film 101 and the second encapsulation film 102 are both multilayer sheets.
  • the first encapsulation film 101 may include a first protective layer 1011, a first metal layer 1012, and a first polymer layer 1013 stacked sequentially.
  • the first polymer layer 1013 is closer to the electrode assembly 20 than the first protective layer 1011.
  • the material of the first protective layer 1011 can be a polymer resin, which can be used to protect the first metal layer 1012, reduce the risk of the first metal layer 1012 being damaged by external forces, and at the same time delay the air infiltration from the external environment, maintaining the internal environment of the secondary battery 100 in a normal operating environment.
  • the material of the first protective layer 1011 may be selected from at least one of polyethylene terephthalate, polybutylene terephthalate, polyvinylidene fluoride, polytetrafluoroethylene, polypropylene, polyamide, and polyimide.
  • the first metal layer 1012 may be used to delay the penetration of moisture from the external environment and reduce damage to the electrode assembly 20 caused by external forces.
  • the first metal layer 1012 may be an aluminum foil layer or a steel foil layer.
  • the first polymer layer 1013 has the property of melting upon heating, can be used for encapsulation, and can reduce the risk of the multilayer sheet being dissolved or swollen by organic solvents in the electrolyte.
  • the first polymer layer 1013 may also be used to reduce the risk of corrosion of the metal layer due to contact between the electrolyte in the electrolyte and the first metal layer 1012.
  • the first polymer layer 1013 includes a first polymer material, which may be selected from at least one of polyethylene, polypropylene, polyurethane, and polyimide.
  • the second encapsulation film 102 may include a second protective layer 1021, a second metal layer 1022, and a second polymer layer 1023 stacked sequentially. It can be understood that when the first encapsulation film 101 and the second encapsulation film 102 are obtained by folding a single encapsulation film, the materials of the second protective layer 1021, the second metal layer 1022, and the second polymer layer 1023 are the same as the materials of the first protective layer 1011, the first metal layer 1012, and the first polymer layer 1013, respectively.
  • the sealing head of the sealing equipment can simultaneously apply a certain temperature and pressure to the edges of the first sealing film 101 and the second sealing film 102, causing the first polymer layer 1013 and the second polymer layer 1023 to melt and bond together, resulting in a first adhesive layer 110, a second adhesive layer 120, and a third adhesive layer (not shown).
  • the first adhesive layer 110 is located inside the first sealing edge 11
  • the second adhesive layer 120 is located inside the second sealing edge 12
  • the third adhesive layer is located inside the third sealing edge 13.
  • the first sealing edge 11 includes a first protective layer 1011, a first metal layer 1012, a first adhesive layer 110, a second metal layer 1022, and a second protective layer 1021 stacked sequentially.
  • the second sealing edge 12 includes a first protective layer 1011, a first metal layer 1012, a second adhesive layer 120, a second metal layer 1022, and a second protective layer 1021 stacked sequentially.
  • the third edge seal 13 comprises a first protective layer 1011, a first metal layer 1012, a third adhesive layer, a second metal layer 1022, and a second protective layer 1021, which are stacked sequentially.
  • Each adhesive layer comprises the aforementioned first polymer material, namely at least one of polyethylene, polypropylene, polyurethane, and polyimide.
  • each adhesive layer refers to the portion of the first polymer layer 1013 and the second polymer layer 1023 that is melted and bonded together within the corresponding edge seal. The unbonded portions of the first polymer layer 1013 and the second polymer layer 1023 that separate within the receiving portion 14 are not included in each adhesive layer.
  • the first sealing edge 11 does not need to be bent.
  • the surface where the first sealing edge 11 is located may be substantially perpendicular to the surface where the first sidewall 141 is located.
  • the first sealing edge 11 Viewed from the first direction X, the first sealing edge 11 has a first edge 11A connected to the first sidewall 141 and a second edge 11B opposite to the first edge 11A.
  • the first sealing edge 11 extends from the first edge 11A in a direction away from the receiving portion 14. Therefore, the extension direction of the first sealing edge 11 is opposite to the third direction Z, such that the first sealing edge 11 is substantially perpendicular to the first sidewall 141.
  • the extension direction of the first sealing edge 11 may also deviate from the third direction Z.
  • the electrode assembly 20 has a stacked structure and includes multiple positive electrode plates 21, multiple negative electrode plates 22, and at least one separator 23.
  • the positive electrode plates 21 and negative electrode plates 22 are stacked alternately, with one negative electrode plate 22 in every two adjacent positive electrode plates 21 and one positive electrode plate 21 in every two adjacent negative electrode plates 22.
  • the separator 23 is disposed between adjacent positive electrode plates 21 and negative electrode plates 22.
  • Each positive electrode plate 21 includes a positive current collector 210 and a positive active material layer 211 disposed on the positive current collector 210, and a first conductive plate 30 is electrically connected to the positive current collector 210.
  • Each negative electrode plate 22 includes a negative current collector 220 and a negative active material layer 221 disposed on the negative current collector 220, and a second conductive plate 40 is electrically connected to the negative current collector 220.
  • the electrode assembly 20 includes N independent insulating films 23, each insulating film 23 disposed between adjacent positive electrode plates 21 and negative electrode plates 22.
  • the electrode assembly 20 is stacked sequentially in the second direction Y in the order of positive electrode plate 21, insulating film 23, negative electrode plate 22, positive electrode plate 21, insulating film 23, negative electrode plate 22, and so on.
  • the electrode assembly 20 may also include an insulating film 23.
  • This insulating film 23 is a one-piece structure and is formed into a Z-shaped structure by alternating bending and folding in both directions.
  • the insulating film 23 includes N insulating films 23 in the second direction Y, and the edges of adjacent insulating films 23 are connected to each other.
  • the N-layer separator 23 includes n layers of first separator 23A, where n and N are both positive integers greater than 1, and n can be equal to or less than N.
  • the first separator 23A includes a main body region 230 and a first edge region 231 connected in the third direction Z. In the third direction Z, the first edge region 231 is closer to the first edge 11 than the second sealing edge 12. Viewed from the second direction Y, the main body region 230 overlaps with the negative electrode 22, and the first edge region 231 extends from the main body region 230 and beyond the negative electrode 22. The first edge region 231 reduces the risk of short circuit between the positive electrode 21 and the negative electrode 22.
  • the first separator 23A may also include a second edge region 232.
  • the first edge region 231, the main body region 230, and the second edge region 232 are connected sequentially in the third direction Z. Viewed from the second direction Y, the second edge region 232 extends from the main body region 230 and beyond the negative electrode 22. The second edge region 232 further reduces the risk of short circuit between the positive electrode 21 and the negative electrode 22.
  • the first sealing edge 11 includes a first segment 111 connected to the first sidewall 141 and a second segment 112 connected to the first segment 111.
  • the second segment 112 is connected to the first segment 111 along the extending direction of the first sealing edge 11 (in some embodiments, the opposite direction of the third direction Z).
  • At least a portion of each first edge region 231 is disposed within the first segment 111. After encapsulation, at least a portion of the first edge region 231 is fused and bonded to the first adhesive layer 110. In some embodiments, after encapsulation, only a portion of the first edge region 231 is fused and bonded to the first adhesive layer 110.
  • the thickness of the first segment 111 is defined as H1
  • the thickness of the second segment 112 is defined as H2 , where H2 ⁇ H1 .
  • the thickness of the first segment 111 is the thickness of the first segment 111 in the second direction Y
  • the thickness of the second segment 112 is the thickness of the second segment 112 in the second direction Y.
  • the first segment 111 containing the first edge region 231 can be encapsulated first, and then the second segment 112 can be encapsulated.
  • the pressure and/or temperature of the sealing head during the first encapsulation is lower than that during the second encapsulation, resulting in a greater thickness for the first segment 111 than for the second segment 112.
  • the above example illustrates the use of two encapsulations for the first edge 11; however, the encapsulation order of the first segment 111 and the second segment 112 can be reversed.
  • the first segment 111 and the second segment 112 can also be encapsulated using two sealing heads in the same encapsulation step.
  • the pressure and/or temperature of the sealing head used to encapsulate the first segment 111 is lower, resulting in a thicker first segment 111 after encapsulation.
  • the first segment 111 and the second segment 112 can also be encapsulated using irregularly shaped sealing heads in the same encapsulation step.
  • the distance between the upper and lower sealing heads used to encapsulate the first segment 111 is relatively large, resulting in a thicker first segment 111 after encapsulation.
  • 0.11mm ⁇ H1 ⁇ 0.40mm, and 0.10mm ⁇ H2 ⁇ 0.20mm If the thickness H1 of the first segment 111 is too large, it means that the encapsulation pressure and/or temperature used to encapsulate the first segment 111 is too low. This may result in insufficient restraint of the first segment 111 on the first edge region 231, failing to properly fix the electrode assembly 20 inside the packaging bag 10, thus failing to improve the safety performance of the secondary battery 100 under mechanical abuse. If H1 is too small, it means that the encapsulation pressure and/or temperature used to encapsulate the first segment 111 is too high.
  • an edge voltage between -0.3V and 0.95V is within the normal range, and a value higher than 0.95V is considered an excessively high edge voltage.
  • the edge voltage can be obtained by measuring the potential difference between the metal layer of the packaging bag 10 and the tabs of the secondary battery 100 using a multimeter. Therefore, limiting H1 to the above range can balance the binding effect of the first segment 111 on the first edge region 231 and prevent the first adhesive layer 110 in the first segment 111 from being damaged, thereby giving the secondary battery 100 higher safety performance.
  • Encapsulation strength can be quantified by encapsulation tensile force, which can be obtained by testing with a tensile testing instrument.
  • the encapsulated secondary battery 100 is placed on the stage of the tensile testing instrument. Two clamps hold the first encapsulation film 101 and the second encapsulation film 102 of the second segment 112, respectively.
  • the tensile force at this point is the encapsulation tensile force of the second segment 112.
  • the encapsulation tensile force can be used to characterize the encapsulation strength of the second segment 112. The greater the encapsulation tensile force, the higher its encapsulation reliability. Generally speaking, to ensure sufficient encapsulation reliability of the secondary battery 100, the encapsulation tensile force at the encapsulation edge needs to meet the standard of greater than 7N.
  • H2 If the encapsulation tensile force is less than 7N, it can be considered that there is a significant risk of leakage. If H2 is too small, it means that the packaging pressure and/or temperature used for the second segment 112 is too high, which may cause the first adhesive layer 110 inside the second segment 112 to be damaged, thereby causing problems such as increased side voltage. Therefore, limiting H2 within the above range can balance the packaging reliability and safety performance of the secondary battery 100.
  • the measurement steps for H1 and H2 may be as follows: (1) Take the first sealing edge 11 from the packaging bag 10 as a sample; (2) Prepare a resin composition, which is made of a crystal resin matrix (such as epoxy resin), catalyst and curing agent in a certain proportion; (3) Pour the resin composition into a mold and place the sample in the mold so that the sample is completely immersed in the resin composition, and then let it stand until the resin composition solidifies; (4) Cut the sample covered with the resin composition along a section perpendicular to the first direction X and polish the cut surface to obtain the cross section of the sample; (5) Use a suitable measuring tool (such as a micrometer) to measure the values of H1 and H2 in the above cross section respectively.
  • a suitable measuring tool such as a micrometer
  • the first adhesive layer 110 inside the first sealing edge 11 is prone to damage, exposing the metal layer (e.g., aluminum layer).
  • the metal layer may be continuously consumed by the electrolyte corrosion, causing the packaging bag 10 to leak. Furthermore, the electrolyte and the metal layer will generate ion channels after contact, leading to an increase in edge voltage and causing safety hazards.
  • the thickness of the first segment 111 is relatively large (this can be achieved by reducing the pressure and/or temperature during the encapsulation of the first segment 111, but this application is not limited to this), which reduces the risk of the metal layer being exposed due to damage to the first adhesive layer 110 within the first sealing edge 11. This, in turn, reduces the risk of the metal layer coming into contact with the electrolyte and being corroded by the electrolyte, thereby reducing potential hazards such as leakage of the packaging bag 10 and increased edge voltage, and improving the safety performance of the secondary battery 100.
  • the thickness of the second segment 112 is relatively small, allowing the first sealing edge 11 to have higher overall encapsulation strength, thus further reducing the risk of leakage of the packaging bag 10.
  • the first edge region 231 is at least partially located within the first segment 111, the risks of leakage of the packaging bag 10 and increased edge voltage are reduced. Therefore, the gap between the negative electrode 22 and the first sidewall 141 of the packaging bag 10 can be reduced accordingly, thereby increasing the energy density of the secondary battery 100. Therefore, the secondary battery 100 of this application can achieve both high safety performance and high energy density.
  • the distance between the negative electrode 22 and the first sidewall 141 in the third direction Z can be set to D, where 0.2mm ⁇ D ⁇ 2mm. This reduces the gap between the negative electrode 22 and the first sidewall 141, thereby enabling the secondary battery 100 to have a higher energy density.
  • the electrode assembly 20 can be fixed to the packaging bag 10.
  • the shaking of the electrode assembly 20 within the packaging bag 10 can be reduced, thereby reducing the risk of the packaging bag 10 being opened and causing leakage, and also reducing the risk of the electrode assembly 20 being damaged during shaking. Therefore, this application can omit the hot melt adhesive between the electrode assembly 20 and the inner surface of the packaging bag 10, which is beneficial for reducing costs and further improving the energy density of the secondary battery 100.
  • the first edge region 231 is at least partially located within the first segment 111, the risk of short circuit between the positive electrode 21 and the negative electrode 22 caused by the first separator 23A folding or wrinkling during mechanical abuse can also be reduced, thereby further improving the safety performance of the secondary battery 100.
  • the first edge region 231 is at least partially located within the first segment 111. This not only eliminates the need for hot melt adhesive between the electrode assembly 20 and the inner surface of the packaging bag 10, but also reduces the risk of the first edge region 231 folding or shrinking due to its fixation within the first segment 111. Furthermore, it eliminates the need for side wrapping adhesive on the electrode assembly 20, thereby facilitating a further increase in the energy density of the secondary battery 100.
  • the electrode assembly 20 includes a first end 20A and a second end 20B disposed opposite each other in the first direction X. In the first direction X, the first end 20A is closer to the third sealing edge 13 than the second end 20B.
  • the secondary battery 100 also includes a tail wrapping adhesive 50 located at the second end 20B, which adheres to the edge of the separator 23 in the first direction X, thereby reducing the risk of short circuit between the positive electrode 21 and the negative electrode 22 due to folding or shrinking of the separator 23.
  • the edge of the separator 23 can be fixed by wrapping the tail with adhesive 50, which helps to further improve the energy density of the secondary battery 100.
  • the length of the first segment 111 is L1
  • the length of the second segment 112 is L2 , where 0.8mm ⁇ L1 ⁇ 2mm and 0.8mm ⁇ L2 ⁇ 2mm.
  • the shaking of the electrode assembly 20 within the packaging bag 10 can be further reduced, and the risk of short circuit between the positive electrode 21 and the negative electrode 22 due to folding or wrinkling of the first separator 23A during mechanical abuse can also be further reduced.
  • the length L2 of the second segment 112 can be no less than 0.8 mm, the first sealing edge 11 can have high overall sealing strength, thus further reducing the risk of leakage from the packaging bag 10.
  • setting L1 and L2 to be no greater than 2 mm can reduce the impact on the energy density of the secondary battery 100 when the length of the first segment 111 or the second segment 112 is too large.
  • the length of the first edge region 231 within the first segment 111 is L3 , where 0.4mm ⁇ L3 ⁇ L1 . Therefore, the gap between the negative electrode 22 and the first sidewall 141 of the packaging bag 10 can be further reduced, thereby further improving the energy density of the secondary battery 100. Moreover, since the first edge region 231 can fully enter the first segment 111, the electrode assembly 20 is better fixed to the packaging bag 10. This further reduces the shaking of the electrode assembly 20 within the packaging bag 10 during mechanical abuse of the secondary battery 100, and also further reduces the risk of short circuits caused by folding or wrinkling of the first separator 23A during mechanical abuse, which could lead to contact between the positive electrode 21 and the negative electrode 22.
  • the measurement steps for L1 , L2 , and L3 can be as follows: after obtaining the cross-section of the first sealing edge 11 using the method described above, the values of L1 , L2 , and L3 in the cross-section are measured using appropriate measuring tools. Although a portion of the first edge region 231 is fused and bonded to the first adhesive layer 110 after encapsulation, the boundary between the first edge region 231 and the first adhesive layer 110 can still be observed from the cross-section.
  • the number n of first separators 23A disposed within the first sealing edge 11 is less than the total number N of separators 23 in the second direction Y. Furthermore, the outermost layer of the electrode assembly 20 in the second direction Y is the first separator 23A. Therefore, the outermost first separator 23A can bind at least a portion of the positive electrode 21 and the negative electrode 22 while securing the electrode assembly 20 relatively firmly to the packaging bag 10, further reducing the shaking of the electrode assembly 20 within the packaging bag 10 in the event of mechanical abuse of the secondary battery 100.
  • the separator 23 when the separator 23 forms a Z-shaped structure by alternating bending and folding in both directions, the edges of two adjacent first edge regions 231 in the second direction Y are directly connected within the first sealing edge 11. Therefore, the separator 23 can bind at least part of the positive electrode 21 and the negative electrode 22 while also securing the electrode assembly 20 to the packaging bag 10 more securely. In the event of mechanical abuse of the secondary battery 100, it can further reduce the shaking of the electrode assembly 20 within the packaging bag 10, and further reduce the risk of short circuits caused by the first separator 23A folding or wrinkling during mechanical abuse, which could lead to contact between the positive electrode 21 and the negative electrode 22.
  • the number n of the first separators 23A within the first segment 111 is equal to the total number N of separators 23 in the second direction Y, meaning all separators 23 are present in the first segment 111. Therefore, this facilitates a more secure fixation of the electrode assembly 20 to the packaging bag 10, further reducing the shaking of the electrode assembly 20 within the packaging bag 10 during mechanical abuse of the secondary battery 100. It also further reduces the risk of short circuits caused by folding or wrinkling of all separators 23 during mechanical abuse, which could lead to contact between the positive electrode 21 and the negative electrode 22.
  • the first release film 23A includes a substrate layer 233, which includes a first substrate region 2331 located in the main body region 230 and a second substrate region 2332 located in the first edge region 231.
  • the second substrate region 2332 is bonded to the first adhesive layer 110 of the first edge seal 11. Since the first edge region 231 is bonded to the first adhesive layer 110 of the first edge seal 11 through the second substrate region 2332, and both the substrate layer 233 and the first adhesive layer 110 are polymer materials with similar or identical properties, it is more conducive to the full fusion and bonding of the first edge region 231 and the first adhesive layer 110 of the first edge seal 11 (shown in Figure 3), thereby improving the bonding strength between the first edge region 231 and the first edge seal 11.
  • the substrate layer 233 may further include a third substrate region 2333 located in the second edge region 232, and the second substrate region 2332, the first substrate region 2331, and the third substrate region 2333 are connected sequentially.
  • the substrate layer 233 includes a second polymer material, each of which is independently selected from at least one of polyethylene, polypropylene, polyurethane, and polyimide. Therefore, the second polymer material of the substrate layer 233 has the same or similar properties as the first polymer material of the first adhesive layer 110. To better fuse and bond the substrate layer 233 with the first adhesive layer 110, the second polymer material of the substrate layer 233 may be the same as the first polymer material of the first adhesive layer 110.
  • H1 d1 + d2 + n ⁇ S + X1
  • H2 d1 + d2 + X2
  • d1 is the thickness of the first encapsulation film 101 located in the receiving portion 14
  • d2 is the thickness of the second encapsulation film 102 located in the receiving portion 14
  • S is the thickness of the main body region 230 (i.e., the thickness of the first substrate region 2331)
  • X1 and X2 are adjustment coefficients, -2mm ⁇ X1 ⁇ 0mm, -2mm ⁇ X2 ⁇ 0mm.
  • the adjustment coefficients can be set by adjusting the encapsulation pressure and/or temperature of the first segment 111 and the second segment 112, so that the first segment 111 and the second segment 112 each have the required thickness. In this way, not only can the risk of metal layer exposure due to damage to the first adhesive layer 110 inside the first sealing edge 11 be reduced, and the hidden dangers such as leakage of packaging bag 10 and edge voltage rise be reduced, but the first sealing edge 11 as a whole can also have high sealing strength, thus further reducing the risk of leakage of packaging bag 10.
  • the first separator 23A may also include a substrate layer 233 and an insulating layer 234 stacked together, and the insulating layer 234 contains inorganic particles.
  • the substrate layer 233 includes a first substrate region 2331 located in the main body region 230 and a second substrate region 2332 located in the first edge region 231.
  • the insulating layer 234 is disposed on the first substrate region 2331 but not on the insulating layer 234, and the second substrate region 2332 extends beyond the insulating layer 234.
  • H1 d1 + d2 + n ⁇ S + X1
  • S is the thickness of the first substrate region 2331.
  • an insulating layer 234 containing inorganic particles By providing an insulating layer 234 containing inorganic particles on the main body region 230, it is beneficial to improve the wetting effect of the electrolyte in the main body region 230. Meanwhile, no insulating layer 234 is provided on the first edge region 231 within the first segment 111. That is, the first edge region 231 is bonded to the first adhesive layer 110 of the first edge sealing 11 through the second substrate region 2332. Since both the substrate layer 233 and the first adhesive layer 110 are polymer materials with similar or identical properties, it is more conducive to the full fusion and bonding of the first edge region 231 and the first adhesive layer 110 of the first edge sealing 11.
  • the insulating layer 234 may be provided on one surface of the first substrate region 2331 or on two opposite surfaces of the first substrate region 2331.
  • the inorganic particles are selected from at least one of alumina, silicon dioxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, cerium dioxide, nickel oxide, zinc oxide, calcium oxide, zirconium dioxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, or barium sulfate.
  • the insulating layer 234 can also be disposed on the first substrate region 2331 and the second substrate region 2332 respectively.
  • the insulating layer 234 disposed on the second substrate region 2332 is bonded to the first adhesive layer 110.
  • S is the sum of the thicknesses of the first substrate region 2331 and the insulating layer 234.
  • the main body region 230 and the first edge region 231 of the first separator 23A can be integrally formed, thereby simplifying the process.
  • the first separating membrane 23A may also include a substrate layer 233, an insulating layer 234, and a first adhesive layer 235 stacked together.
  • the first adhesive layer 235 is disposed on the side of the insulating layer 234 opposite to the first substrate layer 233.
  • the substrate layer 233 includes a first substrate region 2331 located in the main body region 230 and a second substrate region 2332 located in the first edge region 231.
  • the insulating layer 234 is disposed on the first substrate region 2331 but not on the second substrate region 2332, and the second substrate region 2332 extends beyond the insulating layer 234 in the third direction Z.
  • the first adhesive layer 235 is disposed on the side of the insulating layer 234 opposite to the substrate layer 233.
  • S is the thickness of the first substrate region 2331.
  • the first adhesive layer 235 can improve the adhesion between the first separator 23A and the positive electrode 21 or the negative electrode 22, reducing the risk of damage to the electrode assembly 20 structure during mechanical abuse. Meanwhile, no insulating layer 234 and the first adhesive layer 235 are provided on the first edge region 231 within the first sealing edge 11. That is, the first edge region 231 is bonded to the first adhesive layer 110 of the first sealing edge 11 via the second substrate region 2332.
  • the adhesive material of the first adhesive layer 235 may be selected from at least one of the following: a copolymer of vinylidene fluoride-hexafluoropropylene, a copolymer of vinylidene fluoride-trichloroethylene, polymethyl methacrylate, polyacrylic acid, polyacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, a copolymer of ethylene and vinyl acetate, polyimide, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl amylopectin, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoe
  • the first adhesive layer 235 is disposed on the side of the insulating layer 234 away from the substrate layer 233. That is, the first adhesive layer 235 can also be disposed on the first substrate region 2331 and the second substrate region 2332. In this case, the first adhesive layer 235 disposed on the second substrate region 2332 is bonded to the first adhesive layer 110.
  • H1 d1 + d2 + n ⁇ S + X1
  • S is the sum of the thicknesses of the first substrate region 2331, the insulating layer 234, and the first adhesive layer 235. Therefore, the main body region 230 and the first edge region 231 of the first separator 23A can be integrally formed, thereby simplifying the process.
  • the second sealing edge 12 includes a third segment 121 connected to the second sidewall 142 and a fourth segment 122 connected to the third segment 121 along the extension direction of the second sealing edge 12 (in some embodiments, the third direction Z). At least a portion of each second edge region 232 is disposed within the third segment 121. After encapsulation, at least a portion of the second edge region 232 is fused and bonded to the second adhesive layer 120. In some embodiments, after encapsulation, only a portion of the second edge region 232 is fused and bonded to the second adhesive layer 120.
  • the thickness of the third segment 121 is defined as H3
  • the thickness of the fourth segment 122 is defined as H4 , where H4 ⁇ H3 .
  • the thickness of the third segment 121 or the fourth segment 122 is its thickness in the second direction Y.
  • the corresponding encapsulation pressure and/or temperature used can be lower, reducing the risk of the metal layer being exposed due to damage to the second adhesive layer 120 within the second sealing edge 12. This reduces the risk of the metal layer contacting the electrolyte and being corroded by the electrolyte, thereby reducing potential hazards such as leakage of the packaging bag 10 and increased edge voltage, and improving the safety performance of the secondary battery 100.
  • the thickness of the fourth segment 122 is smaller, and the corresponding encapsulation pressure and/or temperature used can be higher, allowing the second sealing edge 12 to have higher overall encapsulation strength, thus further reducing the risk of leakage of the packaging bag 10.
  • the gap between the negative electrode plate 22 and the second sidewall 142 of the packaging bag 10 can be reduced accordingly, thereby further improving the energy density of the secondary battery 100.
  • the distance between the negative electrode plate 22 and the second sidewall 142 in the third direction Z can be set to T, 0.2mm ⁇ T ⁇ 2mm, thereby enabling the secondary battery 100 to have a higher energy density.
  • the shaking of the electrode assembly 20 within the packaging bag 10 can be further reduced when the secondary battery 100 is subjected to mechanical abuse. It can also further reduce the risk of short circuit between the positive electrode 21 and the negative electrode 22 caused by the first separator 23A being folded or wrinkled during mechanical abuse, thereby further improving the safety performance of the secondary battery 100.
  • the length settings of the third segment 121 and the fourth segment 122 of the second edge sealing 12 can be referenced to the length settings of the first segment 111 and the second segment 112.
  • the length setting of the second edge region 232 located within the third segment 121 can be referenced to the length setting of the first edge region 231 located within the first segment 111.
  • the first sealing edge 11 is bent to form a single-fold structure.
  • the second segment 112 includes a first segment 1121 connected to the first segment 111 and a second segment 1122 connected to the first segment 1121 along the extending direction of the first sealing edge 11.
  • the second segment 1122 is bent toward the first segment 1121 in a direction away from the second encapsulation film 102. Viewed from the second direction Y, the first segment 1121 and the second segment 1122 overlap.
  • the first sealing edge 11 first extends along the opposite direction of the third direction Z and then along the third direction Z again, where H2 is the thickness of the first segment 1121 or the second segment 1122 in the second direction Y. Since the second segment 1122 is bent toward the first segment 1121, the size of the secondary battery 200 in the third direction Z can be reduced, further improving the space utilization and energy density of the secondary battery 200. Furthermore, the bending point is located in the thinner second segment 112, which facilitates bending the second segment 112 and reduces the risk of the second segment 1122 opening up compared to the first segment 1121. In addition, it also reduces the risk of the exposed metal layer at the edge of the second segment 1122 easily short-circuiting with the outside, further improving the safety performance of the secondary battery 200.
  • the secondary battery 200 also includes a first adhesive member 60, and the second segment 1122 is bonded to the first segment 1121 via the first adhesive member 60.
  • the first adhesive member 60 can be double-sided tape or hot melt adhesive.
  • the adhesive layer material in the double-sided tape can be selected from one or more of acrylate, polyurethane, rubber, and silicone.
  • the hot melt adhesive can be selected from one or more of polyolefin hot melt adhesives, polyurethane hot melt adhesives, ethylene and its copolymers hot melt adhesives, polyester hot melt adhesives, polyamide hot melt adhesives, and styrene and its block copolymers hot melt adhesives.
  • the first sealing edge 11 is bent to form a double-folded edge structure.
  • the second segment 112 includes a first segment 1121 connected to the first segment 111 and a second segment 1122 connected to the first segment 1121 along the extending direction of the first sealing edge 11.
  • the second segment 1122 is bent toward the first segment 1121 in a direction away from the second encapsulation film 102.
  • the first segment 111 is bent toward the first sidewall 141 in a direction away from the second encapsulation film 102, and the second segment 1122 is disposed between the first segment 1121 and the first sidewall 141 in the third direction Z.
  • the first sealing edge 11 extends successively along the first direction X and the opposite direction of the first direction X.
  • H1 is the thickness of the first segment 111 in the third direction Z
  • H2 is the thickness of the first segment 1121 or the second segment 1122 in the third direction Z.
  • the second segment 112 can be bent for the first time to form the first segment 1121 and the second segment 1122, thereby protecting the exposed metal layer at the edge of the second segment 112, reducing the risk of short circuits with the outside after the metal layer is exposed, and improving safety.
  • the first segment 111 is bent for the second time onto the first sidewall 141.
  • the bending sequence of the double-folded edge structure can also be: the first segment 111 can be bent for the first time onto the first sidewall 141, and then part of the second segment 112 can be bent for the second time to form the first segment 1121 and the second segment 1122, thereby protecting the exposed metal layer at the edge of the second segment 112.
  • the order of the two bending can be selected according to the actual situation, and this application does not impose any restrictions. Therefore, the size of the secondary battery 300 in the third direction Z can be reduced, further improving the space utilization and energy density of the secondary battery 300.
  • the bending point is located in the second segment 112, which has a smaller thickness, thus facilitating the bending of the second segment 112 and reducing the risk of the second segment 1122 opening up compared to the first segment 1121.
  • the secondary battery 300 also includes a second adhesive member 70, and the second segment 1122 is bonded to the first sidewall 141 via the second adhesive member 70.
  • the second adhesive member 70 can be double-sided tape or hot melt adhesive.
  • the adhesive layer material in the double-sided tape can be selected from one or more of acrylate, polyurethane, rubber, and silicone.
  • the hot melt adhesive can be selected from one or more of polyolefin hot melt adhesives, polyurethane hot melt adhesives, ethylene and its copolymers hot melt adhesives, polyester hot melt adhesives, polyamide hot melt adhesives, and styrene and its block copolymers hot melt adhesives.
  • the secondary batteries 100, 200, and 300 in this application can be lithium secondary batteries, including lithium metal secondary batteries, lithium-ion secondary batteries, lithium polymer secondary batteries, or lithium-ion polymer secondary batteries.
  • One embodiment of this application also provides an electronic device 1, which includes a battery compartment 1001 and the aforementioned secondary battery 100 (or secondary batteries 200, 300) disposed within the battery compartment 101.
  • the secondary battery 100 of this application is applicable to electronic devices 1 in various fields.
  • the electronic device 1 is powered by the aforementioned secondary battery 100, which balances high energy density and safety performance.
  • the electronic device 1 of this application may be, but is not limited to, laptops, pen-based computers, mobile computers, e-book players, portable telephones, portable fax machines, portable copiers, portable printers, stereo headphones, video recorders, LCD TVs, portable cleaners, portable C-type devices, mini CD-ROMs, transceivers, electronic notebooks, calculators, memory cards, portable recorders, radios, backup power supplies, motors, automobiles, motorcycles, electric bicycles, bicycles, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, household large-capacity batteries, and lithium-ion capacitors, etc.

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Abstract

一种二次电池及电子装置。二次电池包括包装袋、电极组件和导电板。包装袋包括容纳部和第一封边，电极组件设置于容纳部内，导电板电连接电极组件并伸出包装袋。电极组件包括正极极片、负极极片以及隔离膜，正极极片、隔离膜以及负极极片依次层叠形成叠片结构。容纳部包括在第三方向上相对设置的第一侧壁和第二侧壁，第一封边连接于第一侧壁，且包括连接于第一侧壁的第一段以及沿第一封边延伸方向连接于第一段的第二段。至少一层隔离膜的边缘区域超出负极极片并设于第一段内，使得第二段的厚度小于第一段的厚度。本申请可兼顾较高的能量密度和安全性能。

Description

二次电池和电子装置 技术领域
本申请涉及储能技术领域，尤其涉及一种二次电池和具有上述二次电池的电子装置。
背景技术
随着消费电子类的产品如笔记本电脑、手机、掌上游戏机、平板电脑、移动电源和无人机等的普及，人们对二次电池(如软包二次电池)能量密度和安全性能的要求越来越严格。
软包二次电池通常包括包装袋和设于包装袋内的电极组件。为提高二次电池的能量密度，可减小电极组件与包装袋内表面之间的间距。然而，若上述间距较小，电极组件的部分隔离膜可能会进入包装袋的待封装区域，当对待封装区域进行封装后，进入封装区域的隔离膜可能导致包装袋破损，继而引发漏液、边电压值(IV值)升高等安全隐患。因此，如何使软包二次电池兼顾较高的能量密度和安全性能成为亟待解决的问题。
发明内容
有鉴于此，有必要提供一种可兼顾较高的能量密度和安全性能的二次电池以及具有上述二次电池的电子装置。
本申请第一方面提供一种二次电池，包括包装袋、电极组件和导电板。包装袋包括容纳部和第一封边。电极组件设置于容纳部内，导电板电连接电极组件并伸出包装袋。从电极组件指向导电板的方向为第一方向。电极组件包括正极极片、负极极片以及隔离膜，正极极片、隔离膜以及负极极片在第二方向上依次层叠形成叠片结构。电极组件在第二方向上包括N层隔离膜，N层隔离膜包括n层第一隔离膜，n≤N。第一隔离膜包括在第三方向上相连接的主体区域和第一边缘区域，从第二方向观察，主体区域与负极极片存在重叠，第一边缘区域自主体区域延伸并超出负极极片。容纳部包括在第三方向上相对设置的第一侧壁和第二侧壁，第一封边连接于第一侧壁。第一封边包括连接于第一侧壁的第一段以及沿第一封边延伸方向连接于第一段的第二段。每一第一边缘区域的至少部分设于第一段内。定义第一段的厚度为H1，第二段的厚度为H2，H2<H1。第一方向、第二方向和第三方向两两垂直。
本申请中，第一段的厚度较大，相应使用的封装压力和/或温度较小，可降低第一封边内的第一粘合层破损导致金属层露出的风险，进而降低金属层与电解液接触并被电解液腐蚀的风险，从而降低包装袋漏液、边电压升高等隐患，提高二次电池的安全性能，同时第二段的厚度较小，相应使用的封装压力和/或温度较大，使第一封边整体可具备较高的封装强度，因此可进一步降低包装袋漏液的风险。而且，由于第一边缘区域至少部分设于第一段内后包装袋漏液、边电压升高等风险降低，因此可相应减小负极极片与包装袋的第一侧壁之间的间隙，从而提高二次电池的能量密度。因此本申请的二次电池可兼顾较高的安全性能和能量密度。另外，由于第一边缘区域至少部分设于第一段内，因此可将电极组件固定至包装袋内，机械滥用时可减小电极组件在包装袋内的晃动，还可进一步降低机械滥用时由于第一隔离膜翻折或产生褶皱引发正极极片和负极极片接触短路的风险，从而进一步提高二次电池的安全性能。
基于第一方面，在以上一个或多个可能的实现方式中，0.11mm≤H1≤0.40mm，0.10mm≤H2≤0.20mm。若第一段的厚度H1过大，意味着封装第一段使用的封装压力和/或温度较小，这可能造成对于第一边缘区域的束缚不够，不能很好地将电极组件固定在包装袋内，从而无法提高机械滥用时二次电池的安全性能；若H1过小，意味着封装第一段使用的封装压力和/或温度较大，这将导致第一段中的第一粘合层被破坏，从而导致包装袋漏液、边电压升高等隐患。因此，将H1限定在上述范围内，可以兼顾第一段对于第一边缘区域的束缚作用与第一段内的第一粘合层不被破坏，从而使二次电池具备更高的安全性能。若第二段的厚度H2过大，意味着封装第二段使用的封装压力和/或温度较小，这将导致二次电池的封装强度不够、封装拉力不达标，存在漏液等隐患；若H2过小，意味着封装第二段使用的封装压力和/或温度较大，这将导致第二段内的第一粘合层可能被破坏，从而引发边电压升高等问题。因此，将H2限定在上述范围内，可以兼顾二次电池的封装可靠性与安全性能。
基于第一方面，在以上一个或多个可能的实现方式中，沿第一封边延伸方向，第一段的长度为L1，第二段的长度为L2，0.8mm≤L1≤2mm，0.8mm≤L2≤2mm。将第一段和第二段的长度限定在上述范围内，可减小第一段或第二段长度较大时对二次电池的能量密度的影响。而且由于L1不小于0.8mm，第一边缘区域能够充分进入第一段，从而将电极组件更稳固地固定至包装袋，在二次电池发生机械滥用时可进一步减小电极组件在包装袋内的晃动，还可进一步降低机械滥用时由于第一隔离膜翻折或产生褶皱引发正极极片和负极极片接触短路的风险。同时，L2不小于0.8mm，可使得第一封边整体具备较高的封装强度，可进一步降低包装袋漏液的风险。
基于第一方面，在以上一个或多个可能的实现方式中，沿第一封边延伸方向，设于第一段内的第一边缘区域的长度为L3，0.4mm≤L3≤L1。可进一步减小负极极片与包装袋的第一侧壁之间的间隙，从而进一步提高二次电池的能量密度。而且由于第一边缘区域能够充分进入第一段，从而将电极组件较好地固定至包装袋，在二次电池发生机械滥用时可进一步减小电极组件在包装袋内的晃动，还可进一步降低机械滥用时由于第一隔离膜翻折或产生褶皱引发正极极片和负极极片接触短路的风险。
基于第一方面，在以上一个或多个可能的实现方式中，第一隔离膜包括基材层，基材层包括位于主体区域的第一基材区域以及位于第一边缘区域的第二基材区域。包装袋包括相对设置的第一封装膜和第二封装膜，第一封装膜和第二封装膜相粘合形成第一封边。第一封边包括依次叠设的第一保护层、第一金属层、第一粘合层、第二金属层以及第二保护层，第二基材区域与第一粘合层粘接。由于基材层与第一粘合层均为聚合物材料，利于第一边缘区域与第一粘合层充分融合并粘接，从而提高第一边缘区域与第一段之间的结合强度。
基于第一方面，在以上一个或多个可能的实现方式中，第一隔离膜还包括含有无机颗粒的绝缘层。绝缘层设于第一基材区域上，第二基材区域超出绝缘层。第一基材区域上的绝缘层可提高主体区域处的电解液浸润效果，而且设于第一段内的第二基材区域上未设置绝缘层，基材层与第一粘合层均为聚合物材料，利于第一边缘区域与第一粘合层充分融合并粘接，从而提高第一边缘区域与第一段之间的结合强度。
基于第一方面，在以上一个或多个可能的实现方式中，第一隔离膜还包括含有无机颗粒的绝缘层。绝缘层分别设于第一基材区域和第二基材区域上。设于第二基材区域上的绝缘层与第一粘合层粘接。第一基材区域上的绝缘层可提高主体区域处的电解液浸润效果，而且设于第一段内的第一边缘区域上也设置绝缘层，因此第一隔离膜的主体区域和第一边缘区域可以一体成型，从而简化工艺。
基于第一方面，在以上一个或多个可能的实现方式中，第一隔离膜还包括第一粘接层，第一粘接层设于绝缘层远离基材层的一侧。第一粘接层可提高第一隔离膜与正极极片或负极极片之间的粘接力，降低机械滥用时电极组件结构被破坏的风险，而且设于第一封边内的第一边缘区域上未设置绝缘层和第一粘接层，第一边缘区域通过第二基材区域与第一粘合层粘接，而基材层与第一粘合层均为聚合物材料，利于第一边缘区域与第一粘合层充分融合并粘接，从而提高第一边缘区域与第一段之间的结合强度。
基于第一方面，在以上一个或多个可能的实现方式中，第一隔离膜还包括第一粘接层。第一粘接层设于绝缘层远离基材层的一侧。设于第二基材区域上的第一粘接层与第一粘合层粘接。第一粘接层可提高第一隔离膜与正极极片或负极极片之间的粘接力，降低机械滥用时电极组件结构被破坏的风险，而且设于第一封边内的第一边缘区域上也设置绝缘层和第一粘接层，因此第一隔离膜的主体区域和第一边缘区域可以一体成型，从而简化工艺。
基于第一方面，在以上一个或多个可能的实现方式中，第一粘合层包括第一聚合物材料，基材层包括第二聚合物材料，第一聚合物材料和第二聚合物材料各自独立地选自聚乙烯、聚丙烯、聚氨酯以及聚酰亚胺中的至少一种。因此，基材层与第一粘合层性质相同或相近，更利于第一边缘区域与第一粘合层充分融合并粘接。
基于第一方面，在以上一个或多个可能的实现方式中，第一聚合物材料与第二聚合物材料为同一种材料。因此，基材层与第一粘合层性质相同，更利于第一边缘区域与第一粘合层充分融合并粘接。
基于第一方面，在以上一个或多个可能的实现方式中，H1＝d1+d2+n×S+X1，H2＝d1+d2+X2。其中，d1为位于容纳部的第一封装膜的厚度，d2为位于容纳部的第二封装膜的厚度，S为主体区域的厚度，X1和X2为调整系数，-2mm≤X1<0mm，-2mm≤X2<0mm。通过设置调整系数，第一段和第二段可分别具有所需的厚度，这不仅可降低第一封边内的第一粘合层破损导致金属层露出的风险，降低包装袋漏液、边电压升高等隐患，且第一封边整体可具备较高的封装强度，因此可进一步降低包装袋漏液的风险。
基于第一方面，在以上一个或多个可能的实现方式中，n<N，电极组件在第二方向上的最外侧为第一隔离膜。因此，最外侧的第一隔离膜可对至少部分正极极片和负极极片起到束缚作用的同时将电极组件较稳固地固定至包装袋，在二次电池发生机械滥用时进一步减小电极组件在包装袋内的晃动。
基于第一方面，在以上一个或多个可能的实现方式中，在第二方向上相邻的两个第一边缘区域的边缘在第一封边内直接连接。因此，第一隔离膜可对至少部分正极极片和负极极片起到束缚作用的同时将电极组件较稳固地固定至包装袋，在二次电池发生机械滥用时可进一步减小电极组件在包装袋内的晃动，还可进一步降低机械滥用时第一隔离膜翻折或产生褶皱引发正极极片和负极极片接触短路的风险。
基于第一方面，在以上一个或多个可能的实现方式中，包装袋包括第二封装膜，第二段包括连接于第一段的第一分段和沿第一封边延伸方向连接于第一分段的第二分段，第二分段沿远离第二封装膜的方向朝向第一分段弯折设置。因此，可减小二次电池在第三方向上的尺寸，进一步提高二次电池的能量密度。而且弯折处设于厚度较小的第二段，利于将第二段进行弯折，也可降低第二分段相较于第一分段张开的风险。另外，还可降低第二分段的边缘裸露的金属层容易与外界短接的风险，进一步提高二次电池的安全性能。
基于第一方面，在以上一个或多个可能的实现方式中，二次电池还包括第一粘接件，第二分段通过第一粘接件粘接于第一分段。因此，可以进一步降低第二分段相较于第一分段张开的风险。
基于第一方面，在以上一个或多个可能的实现方式中，第一段沿远离第二封装膜的方向朝向第一侧壁弯折设置，第二分段在第三方向上设置于第一分段和第一侧壁之间。因此，可进一步减小二次电池在第三方向上的尺寸，从而进一步提高二次电池的能量密度。
基于第一方面，在以上一个或多个可能的实现方式中，二次电池还包括第二粘接件，第二分段通过第二粘接件粘接于第一侧壁。第二粘接件可降低第一段相较于第一侧壁张开的风险。
基于第一方面，在以上一个或多个可能的实现方式中，负极极片和第一侧壁在第三方向上的距离为D，0.2mm≤D≤2mm，可减小负极极片与第一侧壁之间的间隙，从而使得二次电池具有较高的能量密度。
基于第一方面，在以上一个或多个可能的实现方式中，包装袋还包括连接于第二侧壁的第二封边。第二封边包括连接于第二侧壁的第三段以及沿第二封边延伸方向连接于第三段的第四段。第一隔离膜还包括第二边缘区域，第一边缘区域、主体区域以及第二边缘区域在第三方向上依次连接。从第二方向观察，第二边缘区域自主体区域延伸并超出负极极片。每一第二边缘区域的至少部分设于第三段内。定义第三段的厚度为H3，第四段的厚度为H4，H4<H3。通过设置第三段的厚度较小，相应使用的封装压力和/或温度较小，可降低第二封边内的第二粘合层破损导致金属层露出的风险，进而降低金属层与电解液接触并被电解液腐蚀的风险，从而降低包装袋漏液、边电压升高等隐患，进一步提高二次电池的安全性能。同时第四段的厚度较小，相应使用的封装压力和/或温度较大，第四段可相对于第三段具有更高的封装强度，因此可进一步降低包装袋漏液的风险。而且，由于第二边缘区域至少部分设于第三段可使得包装袋漏液、边电压升高等的风险降低，因此可相应减小负极极片与包装袋的第二侧壁之间的间隙，从而进一步提高二次电池的能量密度。另外，由于第二边缘区域至少部分设于第三段内，二次电池发生机械滥用时可进一步减小电极组件在包装袋内的晃动，还可进一步降低机械滥用时由于第一隔离膜翻折或产生褶皱引发正极极片和负极极片接触短路的风险，从而进一步提高二次电池的安全性能。
本申请第二方面还提供一种电子装置，其包括电池仓和如上二次电池。二次电池设于电池仓内。电子装置通过上述二次电池供电，且二次电池可兼顾较高的能量密度和安全性能。
附图说明
本申请的上述和/或附加的方面和优点从结合下面附图对实施例的描述中将变得明显和容易理解，其中：
图1为本申请一实施方式提供的二次电池从第二方向观察时的结构示意图。
图2为图1所示的二次电池于一些实施例中沿剖切线II-II的剖视图。
图3为图2所示的二次电池的局部放大图。
图4为图2所示的二次电池的另一局部放大图。
图5为图1所示的二次电池在封装前的结构示意图。
图6为图5所示的二次电池的包装袋的第一封装膜的剖视图。
图7为图5所示的二次电池的包装袋的第二封装膜的剖视图。
图8为图1所示的二次电池于另一些实施例中的剖视图。
图9为图1所示的二次电池于另一些实施例中的剖视图。
图10为图2或图3所示的二次电池的隔离膜于一些实施例中的剖视图。
图11为图2或图3所示的二次电池的隔离膜于一些实施例中的剖视图。
图12为图2或图3所示的二次电池的隔离膜于一些实施例中的剖视图。
图13为图2或图3所示的二次电池的隔离膜于一些实施例中的剖视图。
图14为图2或图3所示的二次电池的隔离膜于一些实施例中的剖视图。
图15为本申请另一实施方式提供的二次电池的剖视图。
图16为本申请又一实施方式提供的二次电池的剖视图。
图17为本申请一实施方式提供的电子装置的结构示意图。
主要元件符号说明
电子装置               1
包装袋                 10
第一封边               11
第一边缘               11A
第二边缘               11B
第二封边               12
第三封边               13
容纳部                 14
电极组件               20
第一端部               20A
第二端部               20B
正极极片               21
负极极片               22
隔离膜                 23
第一隔离膜             23A
第一导电板              30
第二导电板             40
尾部绕胶               50
第一粘接件             60
第二粘接件             70
二次电池               100、200、300
第一封装膜              101
第二封装膜              102
第一粘合层              110
第一段                 111
第二段                 112
第三段                 121
第四段                 122
第二粘合层              120
第一侧壁                141
第二侧壁                142
第一端壁                143
第二端壁                144
正极集流体             210
正极活性材料层          211
负极集流体             220
负极活性材料层          221
主体区域               230
第一边缘区域            231
第二边缘区域            232
基材层                 233
绝缘层                 234
第一粘接层             235
电池仓                  1001
第一保护层              1011
第一金属层              1012
第一聚合物层            1013
第二保护层              1021
第二金属层              1022
第二聚合物层           1023
第一分段                1121
第二分段                1122
第一基材区域            2331
第二基材区域            2332
第三基材区域            2333
距离                   D、T
厚度                   H1、H2、H3、H4、d1、d2、S
长度                   L1、L2、L3
第一方向               X
第二方向               Y
第三方向               Z
如下具体实施方式将结合上述附图进一步说明本申请。
具体实施方式
下面对本申请实施例中的技术方案进行清楚、详细地描述，显然，所描述的实施例是本申请一部分实施例，而不是全部的实施例。除非另有定义，本文所使用的所有的技术和科学术语与属于本申请的技术领域的技术人员通常理解的含义相同。在本申请的说明书中所使用的术语只是为了描述具体的实施例的目的，不是旨在于限制本申请。
下文，将详细地描述本申请的实施方式。但是，本申请可体现为许多不同的形式，并且不应解释为限于本文阐释的示例性实施方式。而是，提供这些示例性实施方式，从而使本申请透彻的和详细的向本领域技术人员传达。
另外，为了简洁和清楚，在附图中，各种组件、层的尺寸或厚度可被放大。遍及全文，相同的数值指相同的要素。如本文所使用，术语“及/或”、“以及/或者”包括一个或多个相关列举项目的任何和所有组合。另外，应当理解，当要素A被称为“连接”要素B时，要素A可直接连接至要素B，或可能存在中间要素C并且要素A和要素B可彼此间接连接。
进一步，当描述本申请的实施方式时使用“可”指“本申请的一个或多个实施方式”。
本文使用的专业术语是为了描述具体实施方式的目的并且不旨在限制本申请。如本文所使用，单数形式旨在也包括复数形式，除非上下文另外明确指出。应进一步理解，术语“包括”，当在本说明书中使用时，指存在叙述的特征、数值、步骤、操作、要素和/或组分，但是不排除存在或增加一个或多个其他特征、数值、步骤、操作、要素、组分和/或其组合。
空间相关术语，比如“上”等可在本文用于方便描述，以描述如图中阐释的一个要素或特征与另一要素(多个要素)或特征(多个特征)的关系。应理解，除了图中描述的方向之外，空间相关术语旨在包括设备或装置在使用或操作中的不同方向。例如，如果将图中的设备翻转，则描述为在其他要素或特征“上方”或“上”的要素将定向在其他要素或特征的“下方”或“下面”。因此，示例性术语“上”可包括上面和下面的方向。应理解，尽管术语第一、第二、第三等可在本文用于描述各种要素、组分、区域、层和/或部分，但是这些要素、组分、区域、层和/或部分不应受这些术语的限制。这些术语用于区分一个要素、组分、区域、层或部分与另一要素、组分、区域、层或部分。因此，下面讨论的第一要素、组分、区域、层或部分可称为第二要素、组分、区域、层或部分，而不背离示例性实施方式的教导。
在本申请中，参数数值之间的大于、小于或不等于设计关系，需要排除测量设备的合理误差。
请参阅图1至图4，本申请一实施方式提供一种二次电池100，其包括包装袋10、电极组件20、电解液(图未示)以及导电板。电极组件20和电解液设于包装袋10内。导电板可包括第一导电板30和第二导电板40，第一导电板30和第二导电板40均电连接于电极组件20并伸出包装袋10。第一导电板30和第二导电板40可以连接外部元件(图未示)。根据两两垂直的第一方向X、第二方向Y以及第三方向Z建立三维坐标系，其中从电极组件20指向第一导电板30或第二导电板40的方向为第一方向X，电极组件20的厚度方向为第二方向Y，在一些实施例中，从第一导电板30至第二导电板40的方向为第三方向Z。
如图1所示，包装袋10包括容纳部14和第一封边11。电极组件20和电解液设置于容纳部14内。在第三方向Z上，容纳部14包括相对设置的第一侧壁141和第二侧壁142。第一侧壁141所在的表面在第一方向X和第二方向Y上延伸，第二侧壁142所在的表面在第一方向X和第二方向Y上延伸。在第一方向X上，容纳部14包括相对设置的第一端壁143和第二端壁144。第一端壁143所在的表面在第二方向Y和第三方向Z上延伸，第二端壁144所在的表面在第二方向Y和第三方向Z上延伸。第一封边11连接于第一端壁143。在一些实施例中，包装袋10还可包括第二封边12，且第二封边12连接于第二侧壁142。包装袋10还可包括第三封边13，且第三封边13连接于第一端壁143。第一导电板30和第二导电板40可均从第三封边13伸出包装袋10。
请参阅图5，为二次电池100在封装前的结构示意图。包装袋10包括在第二方向Y上相对设置的第一封装膜101和第二封装膜102。在一些实施例中，第一封装膜101与第二封装膜102在封装前为一体式结构，第一封装膜101和第二封装膜102由一张封装膜折叠得到。第一封装膜101和第二封装膜102的材料均为多层片材。如图6所示，第一封装膜101可包括依次层叠设置的第一保护层1011、第一金属层1012和第一聚合物层1013。第一聚合物层1013相较于第一保护层1011更靠近电极组件20。第一保护层1011的材质可以为高分子树脂，其可以用于保护第一金属层1012，降低第一金属层1012因外力作用破损的风险，同时能够延缓外部环境的空气渗透，维持二次电池100内部处于正常运作的环境。在一些实施例中，第一保护层1011的材质可选自对苯二甲酸乙二醇酯、聚对苯二甲酸丁二醇酯、聚偏氟乙烯、聚四氟乙烯、聚丙烯、聚酰胺以及聚酰亚胺中的至少一种。第一金属层1012可以用于延缓外部环境的水分渗透，并减少外力对电极组件20造成的损伤。在一些实施例中，第一金属层1012可以为铝箔层或钢箔层。第一聚合物层1013具有加热熔融的性质，可以用于封装，且可以降低多层片材被电解液中的有机溶剂溶解或溶胀的风险。第一聚合物层1013还可用于降低电解液中的电解质与第一金属层1012接触而导致金属层被腐蚀的风险。在一些实施例中，第一聚合物层1013包括第一聚合物材料，其可选自聚乙烯、聚丙烯、聚氨酯以及聚酰亚胺中的至少一种。
如图7所示，第二封装膜102可包括依次层叠设置的第二保护层1021、第二金属层1022和第二聚合物层1023。可以理解，当第一封装膜101和第二封装膜102由一张封装膜折叠得到时，第二保护层1021、第二金属层1022和第二聚合物层1023的材质分别与第一保护层1011、第一金属层1012和第一聚合物层1013的材质相同。
如图3至图5所示，制备包装袋10时，可利用封装设备的封头同时在第一封装膜101和第二封装膜102的边缘处施加一定的温度和压力，使第一聚合物层1013和第二聚合物层1023相互熔融并粘合在一起，得到第一粘合层110、第二粘合层120以及第三粘合层(图未示)。第一粘合层110位于第一封边11内，第二粘合层120位于第二封边12内，第三粘合层位于第三封边13内。即，如图3所示，第一封边11包括依次层叠的第一保护层1011、第一金属层1012、第一粘合层110、第二金属层1022以及第二保护层1021。如图4所示，第二封边12包括依次层叠的第一保护层1011、第一金属层1012、第二粘合层120、第二金属层1022以及第二保护层1021。第三封边13包括依次层叠的第一保护层1011、第一金属层1012、第三粘合层、第二金属层1022以及第二保护层1021。各粘合层包括上述第一聚合物材料，即聚乙烯、聚丙烯、聚氨酯以及聚酰亚胺中的至少一种。其中，本申请的各个粘合层指的是第一聚合物层1013和第二聚合物层1023在对应的封边内熔融并相互粘合在一起的部分。第一聚合物层1013和第二聚合物层1023在容纳部14内相分离未粘合的部分不包括在各个粘合层内。
如图2和图3所示，在一些实施例中，第一封边11不需要弯折。第一封边11所在的表面可大致垂直于第一侧壁141所在的表面。从第一方向X观察，第一封边11具有连接于第一侧壁141的第一边缘11A以及与第一边缘11A相对的第二边缘11B。第一封边11自第一边缘11A开始向背离容纳部14的方向延伸形成。因此，第一封边11的延伸方向为第三方向Z的反方向，使得第一封边11大致垂直于第一侧壁141。在另一些实施例中，当第一封边11未弯折时，第一封边11的延伸方向也可以偏离第三方向Z。
电极组件20为叠片结构，且包括多个正极极片21、多个负极极片22以及至少一隔离膜23。叠片结构中正极极片21和负极极片22依次交替层叠，每相邻两个正极极片21中设有一个负极极片22，每相邻两个负极极片22中设有一个正极极片21。隔离膜23设置于相邻的正极极片21和负极极片22之间。其中，正极极片21包括正极集流体210和设置于正极集流体210上的正极活性材料层211，第一导电板30电连接于正极集流体210。负极极片22包括负极集流体220和设置于负极集流体220上的负极活性材料层221，第二导电板40电连接于负极集流体220。
如图2和图3所示，在一些实施例中，电极组件20包括N层相互独立的隔离膜23，每一隔离膜23设于相邻的正极极片21和负极极片22之间。电极组件20按照正极极片21、隔离膜23、负极极片22、正极极片21、隔离膜23、负极极片22以此类推的顺序在第二方向Y上依次堆叠。如图8所示，在另一些实施例中，电极组件20也可以包括一个隔离膜23。该隔离膜23为一体式结构，且通过正反向交替弯曲折叠的方式形成类似Z形结构。此时，该隔离膜23在第二方向Y上包括N层隔离膜23，N层隔离膜23中的相邻两层隔离膜23的边缘相互连接。
其中，N层隔离膜23包括n层第一隔离膜23A，n和N均为大于1的正整数，n可以等于N，也可以小于N。如图3所示，第一隔离膜23A包括在第三方向Z上相连接的主体区域230和第一边缘区域231，在第三方向Z上，第一边缘区域231相较于第二封边12更靠近第一封边11。从第二方向Y观察，主体区域230与负极极片22存在重叠，第一边缘区域231自主体区域230延伸并超出负极极片22。设置第一边缘区域231可降低正极极片21和负极极片22接触短路的风险。如图4所示，在一些实施例中，第一隔离膜23A还可包括第二边缘区域232，结合参考图3和图4，第一边缘区域231、主体区域230以及第二边缘区域232在第三方向Z上依次连接。从第二方向Y观察，第二边缘区域232自主体区域230延伸并超出负极极片22。设置第二边缘区域232可进一步降低正极极片21和负极极片22接触短路的风险。
第一封边11包括连接于第一侧壁141的第一段111以及连接于第一段111的第二段112。第二段112沿第一封边11延伸方向(在一些实施例中为第三方向Z的反方向)连接于第一段111。每一第一边缘区域231的至少部分设于第一段111内。在封装后，至少部分第一边缘区域231与第一粘合层110融合并粘接。在一些实施例中，在封装后，仅部分第一边缘区域231与第一粘合层110融合并粘接。定义第一段111的厚度为H1，第二段112的厚度为H2，H2<H1。其中，当第一封边11沿第三方向Z的反方向延伸时，第一段111的厚度为第一段111在第二方向Y上的厚度，第二段112的厚度为第二段112在第二方向Y上的厚度。
封装时，可先对含有第一边缘区域231的第一段111进行第一次封装，然后再对第二段112进行封装，且第一次封装时封头的压力和/或温度小于第二次封装时封头的压力和/或温度，从而使得第一段111的厚度大于第二段112的厚度。以上对第一封边11采用两次封装进行举例说明，然而第一段111和第二段112的封装顺序也可以对换。在另一实施例中，第一段111和第二段112也可以在同一个封装步骤下通过两个封头进行封装，用于封装第一段111的封头的压力和/或温度较低，封装后也可以形成厚度较大的第一段111。在其它实施例中，第一段111和第二段112也可以在同一个封装步骤下通过异形封头进行封装，用于封装第一段111的上下封头距离相对较大，封装后也可以形成厚度较大的第一段111。
其中，0.11mm≤H1≤0.40mm，0.10mm≤H2≤0.20mm。若第一段111的厚度H1过大，意味着封装第一段111使用的封装压力和/或温度较小，这可能造成第一段111对于第一边缘区域231的束缚不够，不能很好地将电极组件20固定在包装袋10内，从而无法提高机械滥用时二次电池100的安全性能。若H1过小，意味着封装第一段111使用的封装压力和/或温度较大，这将导致第一段111中的第一粘合层110被破坏，从而导致包装袋10漏液、边电压升高等隐患。一般而言，边电压介于-0.3V～0.95V是正常的范围，高于0.95V视为边电压过高。边电压可采用万用表测量包装袋10的金属层与二次电池100的极耳之间的电势差得到。因此，将H1限定在上述范围内，可以兼顾第一段111对于第一边缘区域231的束缚作用与第一段111内的第一粘合层110不被破坏，从而使二次电池100具备更高的安全性能。
若第二段112的厚度H2过大，意味着封装第二段112使用的封装压力和/或温度较小，这将导致二次电池100的封装强度不够，存在漏液等隐患。封装强度可以使用封装拉力量化，其中封装拉力可使用拉力测试仪测试获得。将完成封装的二次电池100置于拉力测试仪载台上，两个夹具分别夹持第二段112的第一封装膜101和第二封装膜102，之后两个夹具分别往相反方向拉扯，直至第二段112的第一封装膜101和第二封装膜102完全分离，此时的拉力值即为第二段112的封装拉力。封装拉力可用于表征第二段112的封装强度，封装拉力越大代表其封装可靠性越高。一般而言，要使二次电池100获得足够的封装可靠性，封装边的封装拉力需要满足大于7N的标准，若封装拉力不足7N，则可认为存在较大的漏液隐患。若H2过小，意味着封装第二段112使用的封装压力和/或温度较大，这将导致第二段112内的第一粘合层110可能被破坏，从而引发边电压升高等问题。因此，将H2限定在上述范围内，可以兼顾二次电池100的封装可靠性与安全性能。
在本申请中，H1、H2的测量步骤可以是：(1)从包装袋10中取下第一封边11作为样品；(2)配置树脂组合物，其由水晶胶树脂基体(如环氧树脂)、催化剂及固化剂按照一定比例调配而成；(3)将树脂组合物倒入模具中，并将样品置于模具中，使得样品完全浸没于树脂组合物中，然后静置至树脂组合物凝固；(4)沿垂直于第一方向X的截面切割包覆有树脂组合物的样品并对切割面进行打磨，从而得到样品的截面；(5)采用合适的量具(如万分尺)分别测量上述截面中H1、H2的数值。
若含有第一边缘区域231的第一段111的厚度等于第二段112的厚度(如第一段111和第二段112采用相同的封装压力或温度)，第一封边11内的第一粘合层110容易出现破损以使金属层(如铝层)露出，而金属层可能会被电解液腐蚀而不断消耗，导致包装袋10漏液，且电解液和金属层接触后会产生离子通道，导致边电压升高，引发安全隐患。本申请中，第一段111的厚度较大(可通过降低第一段111封装时的压力和/或温度实现，但本申请并不限于此)，可降低第一封边11内的第一粘合层110破损导致金属层露出的风险，进而降低金属层与电解液接触并被电解液腐蚀的风险，从而降低包装袋10漏液、边电压升高等隐患，提高二次电池100的安全性能，同时第二段112的厚度较小，使得第一封边11整体可具备较高的封装强度，因此可进一步降低包装袋10漏液的风险。而且，由于第一边缘区域231至少部分设于第一段111内后包装袋10漏液、边电压升高等风险降低，因此可相应减小负极极片22与包装袋10的第一侧壁141之间的间隙，从而提高二次电池100的能量密度。因此本申请的二次电池100可兼顾较高的安全性能和能量密度。在一些实施例中，可设置负极极片22和第一侧壁141在第三方向Z上的距离为D，0.2mm≤D≤2mm。因此可减小负极极片22和第一侧壁141之间的间隙，从而使得二次电池100具有较高的能量密度。
另外，由于第一边缘区域231至少部分设于第一段111内，因此可将电极组件20固定至包装袋10。当二次电池100发生机械滥用(跌落、碰撞或晃动)时，可减小电极组件20在包装袋10内的晃动，进而降低包装袋10被冲开导致漏液的风险，也可降低电极组件20在晃动时破损的风险，因此本申请可省略电极组件20与包装袋10内表面之间的热熔胶，有利于降低成本并进一步提高二次电池100的能量密度。而且，由于第一边缘区域231至少部分设于第一段111内，还可降低机械滥用时由于第一隔离膜23A翻折或产生褶皱引发正极极片21和负极极片22接触短路的风险，从而进一步提高二次电池100的安全性能。
可以理解，第一边缘区域231至少部分设于第一段111内，不仅可省略电极组件20与包装袋10内表面之间的热熔胶，由于第一边缘区域231被固定在第一段111内使第一边缘区域231翻折或收缩的风险较低，还可省略电极组件20的侧边绕胶，从而利于进一步提高二次电池100的能量密度。如图1所示，在一些实施例中，电极组件20在第一方向X上包括相对设置的第一端部20A和第二端部20B。在第一方向X上，第一端部20A相较于第二端部20B更靠近第三封边13。从第二方向Y观察，第一导电板30伸出第一端部20A。二次电池100还包括位于第二端部20B的尾部绕胶50，该尾部绕胶50粘接隔离膜23在第一方向X上的边缘，从而降低隔离膜23翻折或收缩导致正极极片21和负极极片22接触短路的风险。即在一些实施例中，可通过尾部绕胶50固定隔离膜23的边缘，从而利于进一步提高二次电池100的能量密度。
如图3所示，在一些实施例中，沿第一封边11延伸方向(在一些实施例中为第三方向Z的反方向)，第一段111的长度为L1，第二段112的长度为L2，0.8mm≤L1≤2mm，0.8mm≤L2≤2mm。通过设置第一段111的长度，可进一步减小负极极片22与包装袋10的第一侧壁141之间的间隙，从而进一步提高二次电池100的能量密度。而且由于L1不小于0.8mm，第一边缘区域231能够充分进入第一段111，从而将电极组件20更稳固地固定至包装袋10，在二次电池100发生机械滥用时可进一步减小电极组件20在包装袋10内的晃动，还可进一步降低机械滥用时由于第一隔离膜23A翻折或产生褶皱引发正极极片21和负极极片22接触短路的风险。通过设置第二段112的长度L2不小于0.8mm，第一封边11整体可具备较高的封装强度，因此可进一步降低包装袋10漏液的风险。同时，L1和L2不大于2mm，可减小第一段111或第二段112长度较大时对二次电池100的能量密度的影响。
在一些实施例中，沿第一封边11延伸方向，设于第一段111内的第一边缘区域231的长度为L3，0.4mm≤L3≤L1。因此，可进一步减小负极极片22与包装袋10的第一侧壁141之间的间隙，从而进一步提高二次电池100的能量密度。而且由于第一边缘区域231能够充分进入第一段111，从而将电极组件20较好地固定至包装袋10，在二次电池100发生机械滥用时可进一步减小电极组件20在包装袋10内的晃动，还可进一步降低机械滥用时由于第一隔离膜23A翻折或产生褶皱引发正极极片21和负极极片22接触短路的风险。
在本申请中，L1、L2、L3的测量步骤可以是通过上述方法获得第一封边11的截面后，采用合适的量具分别测量上述截面中L1、L2、L3的数值。其中，封装后虽然部分第一边缘区域231与第一粘合层110融合并粘接，从上述截面中仍可观测到第一边缘区域231与第一粘合层110之间的边界。
如图2至图4所示，在一些实施例中，设于第一封边11内的第一隔离膜23A的数量n少于隔离膜23在第二方向Y上的总层数N。而且，电极组件20在第二方向Y上的最外侧为第一隔离膜23A。因此，最外侧的第一隔离膜23A可对至少部分正极极片21和负极极片22起到束缚作用的同时将电极组件20较稳固地固定至包装袋10，在二次电池100发生机械滥用时可进一步减小电极组件20在包装袋10内的晃动。
如图8所示，当隔离膜23通过正反向交替弯曲折叠的方式形成类似Z形结构时，在第二方向Y上相邻的两个第一边缘区域231的边缘在第一封边11内直接连接。因此，隔离膜23可对至少部分正极极片21和负极极片22起到束缚作用的同时可将电极组件20较稳固地固定至包装袋10，在二次电池100发生机械滥用时可进一步减小电极组件20在包装袋10内的晃动，还可进一步降低机械滥用时第一隔离膜23A翻折或产生褶皱引发正极极片21和负极极片22接触短路的风险。
如图9所示，在另一些实施例中，设于第一段111内的第一隔离膜23A的数量n等于隔离膜23在第二方向Y上的总层数N，即所有隔离膜23均进入第一段111。因此，利于将电极组件20更稳固地固定至包装袋10，在二次电池100发生机械滥用时可进一步减小电极组件20在包装袋10内的晃动，还可进一步降低机械滥用时所有的隔离膜23翻折或产生褶皱引发正极极片21和负极极片22接触短路的风险。
如图10所示，在一些实施例中，第一隔离膜23A包括基材层233，基材层233包括位于主体区域230的第一基材区域2331以及位于第一边缘区域231的第二基材区域2332。第二基材区域2332与第一封边11的第一粘合层110粘接。由于第一边缘区域231通过第二基材区域2332与第一封边11的第一粘合层110粘接，而基材层233与第一粘合层110均为聚合物材料，性质相同或相近，因此更利于第一边缘区域231与第一封边11的第一粘合层110(在图3中示出)充分融合并粘接，提高第一边缘区域231与第一封边11之间的粘接强度。在一些实施例中，基材层233还可包括位于第二边缘区域232的第三基材区域2333，且第二基材区域2332、第一基材区域2331以及第三基材区域2333依次连接。在一些实施例中，基材层233包括第二聚合物材料，第二聚合物材料各自独立地选自聚乙烯、聚丙烯、聚氨酯以及聚酰亚胺中的至少一种，因此基材层233的第二聚合物材料与第一粘合层110的第一聚合物材料性质相同或相近。为了使基材层233与第一粘合层110更好地融合粘接，基材层233的第二聚合物材料可以与第一粘合层110的第一聚合物材料相同。
其中，结合参照图3和图10，H1＝d1+d2+n×S+X1，H2＝d1+d2+X2，d1为位于容纳部14的第一封装膜101的厚度，d2为位于容纳部14的第二封装膜102的厚度，S为主体区域230的厚度(即第一基材区域2331的厚度)，X1和X2为调整系数，-2mm≤X1<0mm，-2mm≤X2<0mm。其中，可通过调整第一段111和第二段112的封装压力和/或温度以设置调整系数，使得第一段111和第二段112分别具有所需的厚度。如此，不仅可降低第一封边11内的第一粘合层110破损导致金属层露出的风险，降低包装袋10漏液、边电压升高等隐患，还可使第一封边11整体具备较高的封装强度，因此可进一步降低包装袋10漏液的风险。
如图11所示，在另一些实施例中，第一隔离膜23A也可包括层叠设置的基材层233和绝缘层234，且绝缘层234含有无机颗粒。基材层233包括位于主体区域230的第一基材区域2331以及位于第一边缘区域231的第二基材区域2332。绝缘层234设于第一基材区域2331上但未设于绝缘层234上，第二基材区域2332超出绝缘层234。此时，上式H1＝d1+d2+n×S+X1中，S为第一基材区域2331的厚度。通过在主体区域230上设置含有无机颗粒的绝缘层234，利于提高主体区域230处电解液的浸润效果。同时，设于第一段111内的第一边缘区域231上未设置绝缘层234，即第一边缘区域231通过第二基材区域2332与第一封边11的第一粘合层110粘接，而基材层233与第一粘合层110均为聚合物材料，性质相同或相近，因此更利于第一边缘区域231与第一封边11的第一粘合层110充分融合并粘接。在一些实施例中，绝缘层234可设于第一基材区域2331的一个表面上，也可设于第一基材区域2331相对的两个表面上。无机颗粒选自氧化铝、二氧化硅、氧化镁、氧化钛、二氧化铪、氧化锡、二氧化铈、氧化镍、氧化锌、氧化钙、二氧化锆、氧化钇、碳化硅、勃姆石、氢氧化铝、氢氧化镁、氢氧化钙或硫酸钡的至少一种。
如图12所示，绝缘层234也可以分别设于第一基材区域2331和第二基材区域2332上，此时，设于第二基材区域2332上的绝缘层234与第一粘合层110粘接，上式H1＝d1+d2+n×S+X1中，S为第一基材区域2331和绝缘层234的厚度之和。此时，第一隔离膜23A的主体区域230和第一边缘区域231可以一体成型，从而简化工艺。
如图13所示，在另一些实施例中，第一隔离膜23A也可包括层叠设置的基材层233、绝缘层234以及第一粘接层235。第一粘接层235设于绝缘层234背离第一基材层233的一侧。基材层233包括位于主体区域230的第一基材区域2331以及位于第一边缘区域231的第二基材区域2332。绝缘层234设于第一基材区域2331上但未设于第二基材区域2332上，第二基材区域2332沿第三方向Z超出绝缘层234。第一粘接层235设于绝缘层234背离基材层233的一侧。此时，上式H1＝d1+d2+n×S+X1中，S为第一基材区域2331的厚度。第一粘接层235可提高第一隔离膜23A与正极极片21或负极极片22之间的粘接力，降低机械滥用时电极组件20结构被破坏的风险。同时，设于第一封边11内的第一边缘区域231上未设置绝缘层234和第一粘接层235，即第一边缘区域231通过第二基材区域2332与第一封边11的第一粘合层110粘接，而基材层233与第一粘合层110均为聚合物材料，性质相同或相近，因此更利于第一边缘区域231与第一封边11的第一粘合层110充分融合并粘接。在一些实施例中，第一粘接层235的粘接材料可选自偏二氟乙烯-六氟丙烯的共聚物、偏二氟乙烯-三氯乙烯的共聚物、聚甲基丙烯酸甲酯、聚丙烯酸、聚丙烯酸盐、聚丙烯腈、聚乙烯基吡咯烷酮、聚乙酸乙烯酯、乙烯-乙酸乙烯酯的共聚物、聚酰亚胺、聚氧化乙烯、乙酸纤维素、乙酸丁酸纤维素、乙酸丙酸纤维素、氰基乙基支链淀粉、氰基乙基聚乙烯醇、氰基乙基纤维素、氰基乙基蔗糖、支链淀粉、羧甲基纤维素钠、羧甲基纤维素锂、丙烯腈-苯乙烯-丁二烯的共聚物、聚乙烯醇、聚乙烯醚、聚四氟乙烯、聚六氟丙烯、苯乙烯-丁二烯的共聚物或聚偏二氟乙烯中的至少一种。这些聚合物能够产生较强的粘接作用，将第一隔离膜23A与正极极片21或负极极片22粘结在一起。
如图14所示，当绝缘层234分别设于第一基材区域2331和第二基材区域2332上时，第一粘接层235设于绝缘层234背离基材层233的一侧，即第一粘接层235还可分别设于第一基材区域2331和第二基材区域2332上。此时，设于第二基材区域2332上的第一粘接层235与第一粘合层110粘接，上式H1＝d1+d2+n×S+X1中，S为第一基材区域2331、绝缘层234以及第一粘接层235的厚度之和。因此，第一隔离膜23A的主体区域230和第一边缘区域231可以一体成型，从而简化工艺。
如图2和图4所示，在一些实施例中，第二封边12包括连接于第二侧壁142的第三段121以及沿第二封边12延伸方向(在一些实施例中为第三方向Z)连接于第三段121的第四段122。每一第二边缘区域232的至少部分设于第三段121内。在封装后，至少部分第二边缘区域232与第二粘合层120融合并粘接。在一些实施例中，在封装后，仅部分第二边缘区域232与第二粘合层120融合并粘接。定义第三段121的厚度为H3，第四段122的厚度为H4，H4<H3。其中，当第二封边12沿第三方向Z延伸时，第三段121或第四段122的厚度为其在第二方向Y上的厚度。
通过设置第三段121的厚度较大，相应使用的封装压力和/或温度较小，可降低第二封边12内的第二粘合层120破损导致金属层露出的风险，进而降低金属层与电解液接触并被电解液腐蚀的风险，从而降低包装袋10漏液、边电压升高等隐患，提高二次电池100的安全性能，同时第四段122的厚度较小，相应使用的封装压力和/或温度较大，使得第二封边12整体可具备较高的封装强度，因此可进一步降低包装袋10漏液的风险。而且，由于第二边缘区域232至少部分设于第三段121后包装袋10漏液、边电压升高等风险降低，因此可相应减小负极极片22与包装袋10的第二侧壁142之间的间隙，从而进一步提高二次电池100的能量密度。在一些实施例中，可设置负极极片22和第二侧壁142在第三方向Z上的距离为T，0.2mm≤T≤2mm，从而使得二次电池100具有较高的能量密度。
另外，由于第二边缘区域232至少部分设于第三段121内，二次电池100发生机械滥用时可进一步减小电极组件20在包装袋10内的晃动，还可进一步降低机械滥用时由于第一隔离膜23A翻折或产生褶皱引发正极极片21和负极极片22接触短路的风险，从而进一步提高二次电池100的安全性能。
其中，第二封边12的第三段121和第四段122的长度设置可参考第一段111和第二段112的长度设置。设于第三段121内的第二边缘区域232的长度设置可参考设于第一段111内的第一边缘区域231的长度设置。
请参阅图15，本申请另一实施方式还提供一种二次电池200。与上述二次电池100的不同之处在于，第一封边11弯折形成单折边结构。具体地，第二段112包括连接于第一段111的第一分段1121和沿第一封边11延伸方向连接于第一分段1121的第二分段1122，第二分段1122沿远离第二封装膜102的方向朝向第一分段1121弯折设置。从第二方向Y观察，第一分段1121和第二分段1122存在重叠。此时，第一封边11先沿着第三方向Z的反方向再沿着第三方向Z延伸，H2为第一分段1121或第二分段1122在第二方向Y上的厚度。由于第二分段1122朝向第一分段1121弯折设置，因此可减小二次电池200在第三方向Z上的尺寸，进一步提高二次电池200的空间利用率和能量密度。而且，弯折处设于厚度较小的第二段112，因此利于将第二段112进行弯折，也可降低第二分段1122相较于第一分段1121张开的风险。另外，还可降低第二分段1122的边缘裸露的金属层容易与外界短接的风险，进一步提高二次电池200的安全性能。
为了进一步降低第二分段1122相较于第一分段1121张开的风险，二次电池200还包括第一粘接件60，且第二分段1122通过第一粘接件60粘接于第一分段1121。其中，第一粘接件60可以为双面胶或热熔胶。双面胶中粘结层的材质可以选自丙烯酸酯、聚氨酯、橡胶及硅胶中的一种或多种，热熔胶可以选自聚烯烃类热熔胶、聚氨酯类热熔胶、乙烯及其共聚物类热熔胶、聚酯类热熔胶、聚酰胺类热熔胶、苯乙烯及其嵌段共聚物类热熔胶中的一种或几种。
请参阅图16，本申请再一实施方式还提供一种二次电池300。与上述二次电池100的不同之处在于，第一封边11弯折形成双折边结构。具体地，第二段112包括连接于第一段111的第一分段1121和沿第一封边11延伸方向连接于第一分段1121的第二分段1122，第二分段1122沿远离第二封装膜102的方向朝向第一分段1121弯折设置。而且，第一段111沿远离第二封装膜102的方向朝向第一侧壁141弯折设置，第二分段1122在第三方向Z上设置于第一分段1121和第一侧壁141之间。这可进一步减小二次电池300在第三方向Z上的尺寸，从而进一步提高二次电池300的空间利用率和能量密度。此时，第一封边11先后沿着第一方向X以及第一方向X的反方向延伸，H1为第一段111在第三方向Z上的厚度，H2为第一分段1121或第二分段1122在第三方向Z上的厚度。在封装后，可先将第二段112经第一次弯折形成第一分段1121和第二分段1122，从而将第二段112边缘裸露的金属层保护起来，降低金属层露出后容易与外界短接的风险，提高安全性。然后，再将第一段111经第二次弯折至第一侧壁141上。在另一些实施例中，双折边结构的弯折顺序也可以是：也可以先将第一段111经第一次弯折至第一侧壁141上，然后再将部分第二段112经第二次弯折形成第一分段1121和第二分段1122，从而将第二段112边缘裸露的金属层保护起来。两次弯折的顺序可以根据实际情况选择，本申请并不作限制。因此可减小二次电池300在第三方向Z上的尺寸，进一步提高二次电池300的空间利用率和能量密度。而且，弯折处设于厚度较小的第二段112，因此利于将第二段112进行弯折，也可降低第二分段1122相较于第一分段1121张开的风险。
为了降低第一段111相较于第一侧壁141张开的风险，二次电池300还包括第二粘接件70，且第二分段1122通过第二粘接件70粘接于第一侧壁141。其中，第二粘接件70可以为双面胶或热熔胶。双面胶中粘结层的材质可以选自丙烯酸酯、聚氨酯、橡胶及硅胶中的一种或多种，热熔胶可以选自聚烯烃类热熔胶、聚氨酯类热熔胶、乙烯及其共聚物类热熔胶、聚酯类热熔胶、聚酰胺类热熔胶、苯乙烯及其嵌段共聚物类热熔胶中的一种或几种。
其中，本申请的二次电池100、200、300可以为锂二次电池，包括锂金属二次电池、锂离子二次电池、锂聚合物二次电池或锂离子聚合物二次电池。
请参阅图17，本申请一实施方式还提供一种电子装置1，电子装置1包括电池仓1001和设于电池仓101内的上述二次电池100(或二次电池200、300)。其中，本申请的二次电池100适用于各种领域的电子装置1。电子装置1通过上述二次电池100供电，且二次电池100可兼顾较高的能量密度和安全性能。在一实施方式中，本申请的电子装置1可以是，但不限于笔记本电脑、笔输入型计算机、移动电脑、电子书播放器、便携式电话、便携式传真机、便携式复印机、便携式打印机、头戴式立体声耳机、录像机、液晶电视、手提式清洁器、便携C机、迷你光盘、收发机、电子记事本、计算器、存储卡、便携式录音机、收音机、备用电源、电机、汽车、摩托车、助力自行车、自行车、照明器具、玩具、游戏机、钟表、电动工具、闪光灯、照相机、家庭用大型蓄电池和锂离子电容器等。
以上所揭露的仅为本申请较佳实施方式而已，当然不能以此来限定本申请，因此依本申请所作的等同变化，仍属本申请所涵盖的范围。

Claims (21)

  1. 一种二次电池，包括包装袋、电极组件和导电板，所述包装袋包括容纳部和第一封边，所述电极组件设置于所述容纳部内，所述导电板电连接所述电极组件并伸出所述包装袋，从所述电极组件指向所述导电板的方向为第一方向；其中，
    所述电极组件包括正极极片、负极极片以及隔离膜，所述正极极片、所述隔离膜以及所述负极极片在第二方向上依次层叠形成叠片结构，所述电极组件在所述第二方向上包括N层隔离膜，所述N层隔离膜包括n层第一隔离膜，n≤N；
    所述第一隔离膜包括在第三方向上相连接的主体区域和第一边缘区域，从所述第二方向观察，所述主体区域与所述负极极片存在重叠，所述第一边缘区域自所述主体区域延伸并超出所述负极极片；
    所述容纳部包括在所述第三方向上相对设置的第一侧壁和第二侧壁，所述第一封边连接于所述第一侧壁，所述第一封边包括连接于所述第一侧壁的第一段以及沿所述第一封边延伸方向连接于所述第一段的第二段，每一所述第一边缘区域的至少部分设于所述第一段内，定义所述第一段的厚度为H1，所述第二段的厚度为H2，H2<H1；其中，
    所述第一方向、所述第二方向和所述第三方向两两垂直。
  2. 如权利要求1所述的二次电池，其中，0.11mm≤H1≤0.40mm，0.10mm≤H2≤0.20mm。
  3. 如权利要求1或2所述的二次电池，其中，沿所述第一封边延伸方向，所述第一段的长度为L1，所述第二段的长度为L2，0.8mm≤L1≤2mm，0.8mm≤L2≤2mm。
  4. 权利要求3所述的二次电池，其中，沿所述第一封边延伸方向，设于所述第一段内的所述第一边缘区域的长度为L3，0.4mm≤L3≤L1。
  5. 如权利要求1至4中任一项所述的二次电池，其中，所述第一隔离膜包括基材层，所述基材层包括位于所述主体区域的第一基材区域以及位于所述第一边缘区域的第二基材区域；所述包装袋包括相对设置的第一封装膜和第二封装膜，所述第一封装膜和所述第二封装膜相粘合形成所述第一封边，所述第一封边包括依次叠设的第一保护层、第一金属层、第一粘合层、第二金属层以及第二保护层，所述第二基材区域与所述第一粘合层粘接。
  6. 如权利要求5所述的二次电池，其中，所述第一隔离膜还包括含有无机颗粒的绝缘层，所述绝缘层设于所述第一基材区域上，所述第二基材区域超出所述绝缘层。
  7. 如权利要求5所述的二次电池，其中，所述第一隔离膜还包括含有无机颗粒的绝缘层，所述绝缘层分别设于所述第一基材区域和所述第二基材区域上，设于所述第二基材区域上的所述绝缘层与所述第一粘合层粘接。
  8. 如权利要求6所述的二次电池，其中，所述第一隔离膜还包括第一粘接层，所述第一粘接层设于所述绝缘层远离所述基材层的一侧。
  9. 如权利要求7所述的二次电池，其中，所述第一隔离膜还包括第一粘接层，所述第一粘接层设于所述绝缘层远离所述基材层的一侧，设于所述第二基材区域上的所述第一粘接层与所述第一粘合层粘接。
  10. 如权利要求5至9中任一项所述的二次电池，其中，所述第一粘合层包括第一聚合物材料，所述基材层包括第二聚合物材料，所述第一聚合物材料和所述第二聚合物材料各自独立地选自聚乙烯、聚丙烯、聚氨酯以及聚酰亚胺中的至少一种。
  11. 如权利要求10所述的二次电池，其中，所述第一聚合物材料和所述第二聚合物材料为同一种材料。
  12. 如权利要求5、7、9任一项所述的二次电池，其中，H1＝d1+d2+n×S+X1，H2＝d1+d2+X2，d1为位于所述容纳部的所述第一封装膜的厚度，d2为位于所述容纳部的所述第二封装膜的厚度，S为所述主体区域的厚度，X1和X2为调整系数，-2mm≤X1<0mm，-2mm≤X2<0mm。
  13. 如权利要求1至12中任一项所述的二次电池，其中，n<N，所述电极组件在所述第二方向上的最外侧为所述第一隔离膜。
  14. 如权利要求1至13中任一项所述的二次电池，其中，在所述第二方向上相邻的两个所述第一边缘区域的边缘在所述第一封边内直接连接。
  15. 如权利要求1至14中任一项所述的二次电池，其中，所述包装袋包括第二封装膜，所述第二段包括连接于所述第一段的第一分段和沿所述第一封边延伸方向连接于所述第一分段的第二分段，所述第二分段沿远离所述第二封装膜的方向朝向所述第一分段弯折设置。
  16. 如权利要求15所述的二次电池，其中，所述二次电池还包括第一粘接件，所述第二分段通过所述第一粘接件粘接于所述第一分段。
  17. 如权利要求15或16所述的二次电池，其中，所述第一段沿远离所述第二封装膜的方向朝向所述第一侧壁弯折设置，所述第二分段在所述第三方向上设置于所述第一分段和所述第一侧壁之间。
  18. 如权利要求17所述的二次电池，其中，所述二次电池还包括第二粘接件，所述第二分段通过所述第二粘接件粘接于所述第一侧壁。
  19. 如权利要求1至18中任一项所述的二次电池，其中，所述负极极片和所述第一侧壁在所述第三方向上的距离为D，0.2mm≤D≤2mm。
  20. 如权利要求1至19中任一项所述的二次电池，其中，所述包装袋还包括连接于所述第二侧壁的第二封边，所述第二封边包括连接于所述第二侧壁的第三段以及沿所述第二封边延伸方向连接于所述第三段的第四段；所述第一隔离膜还包括第二边缘区域，所述第一边缘区域、所述主体区域以及所述第二边缘区域在所述第三方向上依次连接，从所述第二方向观察，所述第二边缘区域自所述主体区域延伸并超出所述负极极片；每一所述第二边缘区域的至少部分设于所述第三段内，定义所述第三段的厚度为H3，所述第四段的厚度为H4，H4<H3。
  21. 一种电子装置，包括电池仓，其中，所述电子装置还包括如权利要求1至20中任一项所述的二次电池，所述二次电池设于所述电池仓内。
PCT/CN2025/091483 2024-05-31 2025-04-27 二次电池和电子装置 Pending WO2025246760A1 (zh)

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