WO2025199787A1 - 二次电池和用电装置 - Google Patents

二次电池和用电装置

Info

Publication number
WO2025199787A1
WO2025199787A1 PCT/CN2024/084014 CN2024084014W WO2025199787A1 WO 2025199787 A1 WO2025199787 A1 WO 2025199787A1 CN 2024084014 W CN2024084014 W CN 2024084014W WO 2025199787 A1 WO2025199787 A1 WO 2025199787A1
Authority
WO
WIPO (PCT)
Prior art keywords
secondary battery
area
connection
connection area
connection region
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/CN2024/084014
Other languages
English (en)
French (fr)
Inventor
肖良针
李勇
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
Priority to PCT/CN2024/084014 priority Critical patent/WO2025199787A1/zh
Priority to CN202480017382.0A priority patent/CN120981979A/zh
Publication of WO2025199787A1 publication Critical patent/WO2025199787A1/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
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/572—Means for preventing undesired use or discharge
    • H01M50/574—Devices or arrangements for the interruption of current
    • H01M50/583—Devices or arrangements for the interruption of current in response to current, e.g. fuses
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present application relates to the field of energy storage technology, and in particular to a secondary battery and an electrical device having the secondary battery.
  • secondary batteries eg. lithium-ion batteries
  • secondary batteries eg, lithium-ion secondary batteries
  • secondary batteries can short-circuit during operation, causing the internal temperature to continue to rise, raising safety concerns. Furthermore, if a high-current discharge, micro-short circuit, or high-temperature environment occurs within the secondary battery, while the internal temperature may not reach the high temperature of a short-circuit, it still presents a safety hazard and can lead to safety issues if the battery is continued in use.
  • the present application provides a secondary battery comprising a housing, an electrode assembly disposed within the housing, and a first tab.
  • the electrode assembly includes a first electrode plate, the first tab being connected to the first electrode plate.
  • the secondary battery further comprises a first flow guide and a first insulating protective layer. At least a portion of the first flow guide is disposed within the housing.
  • the first flow guide comprises a first connection region, at least one second connection region, and a third connection region, the second connection region being connected between the first and third connection regions.
  • the first connection region is connected to the first tab.
  • the third connection region is connected to the housing.
  • the electrode assembly further includes a separator, and the melting point of the first polymer is less than or equal to the melting point of the separator.
  • the first polymer melts before the separator.
  • the insulating film melts or melts simultaneously with the insulating film to reduce the risk of the insulating film melting first and causing the short circuit to worsen.
  • the first side is at least partially in the shape of a broken line. In this way, when the protective effect of the first insulating protective layer on the second connection area is weakened or even disappears, the second connection area is more likely to break under mechanical abuse, preventing the secondary battery with safety hazards from continuing to operate.
  • the thickness of the second connection region is smaller than the thickness of either the first connection region or the third connection region, so that the minimum cross-sectional area of each second connection region is smaller.
  • the first connection region, the second connection region, and the third connection region are integrated into one structure. In this way, when the secondary battery is operating normally, the risk of the second connection region breaking under mechanical abuse is reduced.
  • the shell is a packaging bag, which includes a connected receiving portion and an edge seal
  • the electrode assembly is accommodated in the receiving portion
  • at least part of the second connection area is located in the edge seal, in the receiving portion or outside the shell
  • at least part of the third connection area extends out of the shell.
  • the first insulating protective layer includes a first layer and a second layer that are stacked.
  • the first layer includes the above-mentioned first polymer.
  • the second layer includes a second polymer, and the melting point of the second polymer is 160 to 170 degrees.
  • the second layer is connected to the edge seal and the first layer respectively.
  • the third connection area can be connected to external elements, and the second layer of the first insulating protective layer has a higher sealing performance, which can reduce the risk of leakage during use and the risk of separation of the first flow guide from the edge seal, and can also maintain electrical insulation between the first flow guide and the shell.
  • the first connection region, the second connection region, and the third connection region are coplanar.
  • the housing is a metal housing, comprising a first end wall and a second end wall disposed opposite each other, a side wall connected between the first end wall and the second end wall, and a first pole disposed on the first end wall.
  • the first pole is electrically isolated from the first end wall.
  • the third connection region is connected to the first pole. This allows the first pole to have the same electrical polarity as the first pole piece.
  • the electrode assembly is a wound structure.
  • the first pole piece includes a first current collector.
  • the first current collector includes a first end edge facing the first end wall, and the first pole lug is formed by extending from the first end edge.
  • the first pole lug includes a first pole lug region connected to the first end edge and a second pole lug region connected to the first pole lug region.
  • the second pole lug region is bent compared to the first pole lug region and forms a first end face, and the first connection region is connected to the first end face.
  • the full pole lug structure prevents the current distribution of the first pole piece from being too concentrated, reduces the internal resistance of the first pole piece, and thus improves the charge and discharge rate of the first pole piece.
  • the second pole lug region forms a first end face, which facilitates the connection between the second pole lug region and the first connection region.
  • the third connection area includes a third subarea connected to the second connection area and a fourth subarea connected to the third subarea.
  • the first connection area, the second connection area, and the third subarea are coplanar, and the fourth subarea is bent relative to the third subarea. Observed along the thickness direction of the first connection area, the first connection area and the fourth subarea overlap. Because the bend of the first flow guide is located in the third connection area rather than the second connection area, when the secondary battery is operating normally, the risk of the second connection area, which has a smaller minimum cross-sectional area, being easily broken under mechanical abuse is reduced.
  • the first flow guide further includes a bending area and a transition area.
  • the transition area includes a third side and a fourth side that are adjacently arranged.
  • the second connection area is connected to the third side.
  • the bending area is connected between the fourth side and the third connection area.
  • the bending area is bent relative to both the transition area and the third connection area. Observed from the thickness direction of the third connection area, the transition area and the third connection area overlap.
  • a second aspect of the present application further provides an electrical device comprising a battery compartment and a secondary battery as described above.
  • the secondary battery is housed in the battery compartment.
  • the electrical device is powered by the secondary battery, and the safety and reliability of the secondary battery are improved.
  • FIG1 is a schematic structural diagram of a secondary battery provided in one embodiment of the present application.
  • FIG. 2 is a cross-sectional view of the secondary battery shown in FIG. 1 along the cutting line II-II in some embodiments.
  • FIG. 4B is a partial enlarged view of the secondary battery shown in FIG. 4A at position IVA.
  • FIG. 5A is an expanded view of the first flow guide of the secondary battery shown in FIG. 4 in some embodiments.
  • FIG. 5B is an expanded view of the first flow guide of the secondary battery shown in FIG. 4 in other embodiments.
  • FIG. 5C is an expanded view of the first flow guide of the secondary battery shown in FIG. 4 in other embodiments.
  • FIG. 5D is an expanded view of the first flow guide of the secondary battery shown in FIG. 4 in other embodiments.
  • FIG. 6 is a bottom view of the first flow guide of the secondary battery shown in FIG. 5A .
  • FIG. 8 is a partially enlarged cross-sectional view of the secondary battery shown in FIG. 1 along the cutting line IV-IV in some other embodiments.
  • FIG. 9 is a cross-sectional view of the secondary battery shown in FIG. 1 along the cutting line IV-IV in some other embodiments.
  • FIG11 is a cross-sectional view of the secondary battery shown in FIG10 along the cutting line XII-XII.
  • FIG. 12 is an expanded view of the first flow guide of the secondary battery shown in FIG. 11 .
  • FIG13 is a schematic structural diagram of a secondary battery provided in another embodiment of the present application.
  • FIG14 is a cross-sectional view of the secondary battery shown in FIG13 taken along the cutting line XV-XV.
  • FIG15 is a cross-sectional view of the secondary battery shown in FIG13 taken along the cutting line XVI-XVI.
  • FIG. 16 is an expanded view of the first flow guide of the secondary battery shown in FIG. 14 or FIG. 15 .
  • FIG17 is a schematic structural diagram of an electrical device provided in one embodiment of the present application.
  • spatially relative terms such as “above” and the like, may be used herein for convenience of description to describe the relationship of one element or feature to another element(s) or feature(s) as illustrated in the figures. It will be understood that spatially relative terms are intended to encompass different orientations of the device or apparatus in use or operation in addition to the orientation depicted in the figures. For example, if the apparatus in the figures were turned over, elements described as being “above” or “on” other elements or features would be oriented “below” or “below” the other elements or features. Thus, the exemplary term “above” may encompass both an orientation of above and below. It will be understood that, while The terms first, second, third, etc.
  • Perpendicular can refer to the angle between two straight lines being between 90 ⁇ 10°, perpendicular can also refer to the dihedral angle between two planes being between 90 ⁇ 10°, and perpendicular can also refer to the angle between a straight line and a plane being between 90 ⁇ 10°.
  • the two components described as "parallel” or “perpendicular” may not be absolute straight lines or planes, but may be roughly straight lines or planes. From a macroscopic perspective, a component can be considered a "straight line” or "plane” if its overall extension direction is a straight line or plane.
  • the electrode assembly 20 may be a stacked structure comprising multiple first electrode sheets 21, multiple second electrode sheets 22, and multiple separators 23.
  • the first electrode sheets 21 and the second electrode sheets 22 are alternately stacked, with one second electrode sheet 22 positioned between every two adjacent first electrode sheets 21 and one first electrode sheet 21 positioned between every two adjacent second electrode sheets 22.
  • the isolation film 23 is disposed between the adjacent first pole piece 21 and the adjacent second pole piece 22 .
  • a three-dimensional coordinate system is established based on mutually perpendicular first direction X, second direction Y, and third direction Z.
  • first direction X is the direction in which the first electrode tab 30 extends from the first electrode sheet 21
  • second direction Y is the thickness direction of the electrode assembly 20
  • third direction Z is the direction from the first electrode tab 30 to the second electrode tab 40.
  • the first electrode sheet 21 includes a first current collector 210 and a first active material layer 211 stacked together.
  • the first electrode sheet 21 can be a positive electrode sheet.
  • the first current collector 210 can be a positive electrode current collector
  • the first active material layer 211 can be a positive electrode active material layer.
  • the second electrode sheet 22 includes a second current collector 220 and a second active material layer 221 stacked together.
  • the second electrode sheet 22 can be a negative electrode sheet.
  • the second current collector 220 can be a negative electrode.
  • the current collector and the second active material layer 221 may be a negative electrode active material layer.
  • the first electrode tab 30 may be connected to the surface of the first current collector 210 by welding or other means, and the second electrode tab 40 may be connected to the surface of the second current collector 220 by welding or other means.
  • the first electrode tab 30 may be integrally formed with the first current collector 210, and the second electrode tab 40 may be integrally formed with the second current collector 220.
  • the positive electrode current collector may be aluminum foil or nickel foil, and the negative electrode current collector may be at least one of copper foil, nickel foil, or a carbon-based current collector.
  • the positive electrode active material layer comprises a positive electrode active material, which includes a compound that reversibly intercalates and deintercalates lithium ions (lithiated intercalation compound).
  • the positive electrode active material may include a lithium transition metal composite oxide.
  • the lithium transition metal composite oxide contains lithium and at least one element selected from cobalt, manganese, and nickel.
  • the positive electrode active material is selected from at least one of lithium cobalt oxide (LiCoO2), lithium nickel manganese cobalt ternary material (NCM), lithium manganese oxide (LiMn2O4), lithium nickel manganese oxide (LiNi0.5Mn1.5O4 ) , or lithium iron phosphate ( LiFePO4 ).
  • LiCoO2 lithium cobalt oxide
  • NCM lithium nickel manganese cobalt ternary material
  • LiMn2O4 lithium manganese oxide
  • LiNi0.5Mn1.5O4 lithium nickel manganese oxide
  • LiFePO4 lithium iron phosphate
  • the negative electrode active material layer contains a negative electrode active material, which is a negative electrode active material known in the art that can reversibly deintercalate active ions, and is not limited in this application.
  • a negative electrode active material which is a negative electrode active material known in the art that can reversibly deintercalate active ions, and is not limited in this application.
  • it can be a combination of one or more of graphite, soft carbon, hard carbon, carbon fiber, mesophase carbon microspheres, silicon-based materials, tin-based materials, lithium titanate or other metals that can form alloys with lithium.
  • graphite can be selected from a combination of one or more of artificial graphite, natural graphite and modified graphite
  • silicon-based materials can be selected from a combination of one or more of elemental silicon, silicon oxide compounds, silicon-carbon composites, and silicon alloys
  • tin-based materials can be selected from a combination of one or more of elemental tin, tin oxide compounds, and tin alloys.
  • the isolation film 23 includes at least one of polyethylene, polypropylene, polyvinylidene fluoride, polyethylene terephthalate, polyimide, or aramid.
  • the polyethylene includes at least one selected from high-density polyethylene, low-density polyethylene, or ultra-high molecular weight polyethylene. Polyethylene and polypropylene have a good effect on improving short circuits.
  • the secondary battery 100 further includes a first flow guide 50 and a first insulating protective layer 70 .
  • Figure 5A is a schematic structural diagram of the first flow guide 50 shown in Figures 4A and 4B in an expanded state. At least a portion of the first flow guide 50 is disposed within the housing 10 . The first flow guide 50 is connected to the first electrode tab 30 and extends beyond the housing 10 . The first flow guide 50 can be connected to external components (not shown).
  • the first flow guide 50 includes a first connection region 51 , at least one second connection region 52 , and a third connection region 53 . Each second connection region 52 is connected between the first connection region 51 and the third connection region 53 .
  • the first connection region 51 is connected to the first electrode tab 30 .
  • the first connection region 51 can be welded to the first electrode tab 30 to enhance the connection strength between the first connection region 51 and the first electrode tab 30 .
  • at least a portion of the second connection region 52 can be located within the edge seal 17 .
  • the third connection area 53 is connected to the housing 10.
  • the third connection area 53 can be connected to the edge seal 17 and extend from the housing 10 from the edge seal 17.
  • the first flow guide 50 can be an integrated structure, that is, the first connection area 51, the second connection area 52, and the third connection area 53 are connected as a whole. Therefore, when the secondary battery 100 is operating normally, the risk of the second connection area 52 breaking under mechanical abuse is reduced.
  • the first connection area 51, the second connection area 52, and the third connection area 53 can also be connected together by welding or other methods.
  • the material of the first flow guide 50 can be one of aluminum, nickel, copper, steel, or copper-plated nickel.
  • the first electrode tab 30 is bent.
  • the first electrode tab 30 includes a first section 30a connected to the first electrode sheet 21 and a second section 30b connected to the first section 30a.
  • the second section 30b is bent compared to the first section 30a.
  • the first connecting area 51 is connected to the second section 30b of the first electrode tab 30.
  • the first flow guide 50 can be bent.
  • the first connection region 51 includes a first subarea 511 connected to the second connection region 52 and a second subarea 512 connected to the first subarea 511.
  • the second connection region 52, the third connection region 53, and the first subarea 511 are coplanar, and the second subarea 512 is bent relative to the first subarea 511. That is, the bend of the first flow guide 50 is located in the first connection region 51.
  • the second subarea 512 is connected to the first tab 30.
  • the first subarea 511, the second connection region 52, and the third connection region 53 are arranged along the first direction X, and the plane containing the second connection region 52, the third connection region 53, and the first subarea 511 is perpendicular to the second direction Y.
  • the minimum cross-sectional area of each second connection region 52 along the thickness direction of the second connection region 52 is S 1
  • the cross-sectional area of the third connection region 53 along the thickness direction of the third connection region 53 is S 2
  • At least one second connection region 52 satisfies the following conditions: 0.1S 2 ⁇ S 1 ⁇ 0.5S 2 . Because the minimum cross-sectional area S 1 of each second connection region 52 is relatively small, the second connection region 52 can be melted preferentially under the action of the short-circuit current when the secondary battery 100 short-circuits.
  • the bend of the first flow guide 50 is located in the first connection area 51 rather than the second connection area 52, the risk of the second connection area 52, which has a smaller minimum cross-sectional area, being easily broken when the secondary battery 100 is subjected to mechanical abuse (such as vibration or falling), thereby reducing the risk of the secondary battery 100 malfunctioning due to the rupture of all second connection areas 52 when the secondary battery 100 is subjected to mechanical abuse, such as vibration or falling, and thus reducing the risk of the secondary battery 100 malfunctioning due to the rupture of all second connection areas 52 when the secondary battery 100 is subjected to mechanical abuse.
  • the minimum cross-sectional area S1 of each second connection area 52 is set to be smaller, so that each second connection area 52 can be preferentially melted under the action of the short-circuit current when the secondary battery 100 short-circuits.
  • the thickness H 2 of each second connection region 52 is less than the thickness H 1 of the first connection region 51 and less than the thickness H 3 of the third connection region 53, thereby reducing the minimum cross-sectional area S 1 of each second connection region 52.
  • the thicknesses of the first connection region 51 and the third connection region 53 may be the same or different. In other embodiments, the thickness H 2 of each second connection region 52 may be equal to the thickness H 1 of the first connection region 51 or equal to the thickness H 3 of the third connection region 53.
  • the width W 2 of each second connection region 52 is less than the width W 1 of the first connection region 51 or less than the width W 3 of the third connection region 53. This may also reduce the minimum cross-sectional area S 1 of each second connection region 52.
  • the second connection region 52 when viewed along the thickness direction of the second connection region 52, the second connection region 52 includes a first side 521 and a second side 522 that are oppositely disposed.
  • the first side 521 and the second side 522 are both connected between the first connection region 51 and the third connection region 53.
  • the first side 521 and the second side 522 may be oppositely disposed.
  • the minimum cross-sectional area S1 of each second connection region 52 is the area of the cross section taken along the thickness direction of the second connection region 52 and passing through any point of the first side 521 .
  • the first insulating protective layer 70 covers at least the surface of the second connection area 52. Because the first insulating protective layer 70 can cover the second connection area 52 with a smaller minimum cross-sectional area, it protects the second connection area 52 when the secondary battery 100 is subjected to mechanical abuse, reducing the risk of the second connection area 52 breaking (for example, when dropped, the electrode assembly 20 shakes within the housing 10, thereby pulling on the first electrode tab 30 and the first flow guide 50, causing the second connection area 52 to break), which could cause the secondary battery 100 to malfunction. In some embodiments, the first insulating protective layer 70 can cover multiple surfaces of the second connection area 52 to enclose the second connection area 52.
  • the first insulating protective layer 70 can also cover a portion of the surface of the first connection area 51 and a portion of the surface of the third connection area 53. This allows the first insulating protective layer 70 to fully protect the second connection area 52 during normal operation of the secondary battery 100.
  • the first insulating protective layer 70 includes a first polymer having a melting point of 100 to 170 degrees Celsius. This allows the first polymer to melt promptly when the interior of the secondary battery 100 reaches this melting point (e.g., when a high current discharge or micro-short circuit occurs within the secondary battery 100, or when the ambient temperature is high, although the internal temperature of the secondary battery 100 does not reach the short-circuit high temperature, a safety hazard still exists). This weakens or even eliminates the protective effect of the first insulating protective layer 70 on the second connection region 52, making the second connection region 52 more susceptible to rupture under mechanical abuse, thus preventing the secondary battery 100 from continuing to operate despite the safety hazard.
  • the first polymer is made of at least one of polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), a modified polypropylene material, or a modified polyethylene material.
  • polyethylene can be selected from at least one of low-density polyethylene (LDPE) with a melting point of 108-126 degrees Celsius, high-density polyethylene (HDPE) with a melting point of 126-140 degrees Celsius, or linear low-density polyethylene (LLDPE) with a melting point of 110-125 degrees Celsius. Therefore, the melting point of the first polymer can be adjusted by selecting different types of polyethylene.
  • LDPE low-density polyethylene
  • HDPE high-density polyethylene
  • LLDPE linear low-density polyethylene
  • the polyethylene modified material obtained by adding other materials to polyethylene for modification can also have different melting points.
  • the melting point of the first polymer can also be adjusted by a similar method.
  • the melting point of the first polymer is 100 degrees Celsius to 130 degrees Celsius, thereby improving the sensitivity of the first polymer when there are safety hazards in the secondary battery 100.
  • the first insulating protective layer 70 can cover the second connection region 52, which has a smaller minimum cross-sectional area. This protects the second connection region 52 from mechanical abuse and reduces the risk of fracture.
  • the second connection region 52 which has a smaller minimum cross-sectional area, can preferentially fuse under the action of the short-circuit current, severing the connection between the first tab 30 and external components, effectively placing the secondary battery 100 in an open-circuit state and mitigating safety issues caused by continued internal temperature increases.
  • the secondary battery 100 may further include a second flow guide 60 and a second insulating protective layer (not shown).
  • the second flow guide 60 is connected to the second tab 40.
  • the second guide member 60 may have a structure similar to that of the first guide member 50
  • the second insulating protection layer may have a structure similar to that of the first insulating protection layer 70 .
  • the first side 521 may be curved, i.e., non-linear, when viewed along the thickness of the second connection region 52.
  • the first side 521 includes a first endpoint 5211 connected to the first connection region 51, a second endpoint 5212 connected to the third connection region 53, and a top portion 5210 disposed between the first and second endpoints 5211, 5212.
  • the top portion 5210 is recessed toward the interior of the second connection region 52 relative to the first and second endpoints 5211, 5212.
  • the minimum cross-sectional area of the second connection region 52 is the area of the cross-section taken along the thickness of the second connection region 52 through the top portion 5210. This allows the second connection region 52 to preferentially fuse at the location corresponding to the top portion 5210 when a short circuit occurs in the secondary battery 100.
  • at least a portion of the first side 521 may be in the shape of a broken line. As shown in FIG5B , the first side 521 is a partial outline of a trapezoid, and the top 5210 of the first side 521 is the upper base of the trapezoid.
  • the first side 521 is V-shaped, and the top 5210 of the first side 521 can be a pointed top.
  • the first side 521 is sawtooth-shaped, and the top 5210 of the first side 521 is the peak of the sawtooth.
  • the shape of the second side 522 can be the same as that of the first side 521.
  • the width W2 of each second connection area 52 is the distance between the top 5210 of the first side 521 and the top of the second side 522 (not shown) in the second connection area 52.
  • the melting point of the first polymer is less than or equal to the melting point of the separator 23. This allows the first polymer to melt before or simultaneously with the separator 23 when a short circuit occurs in the secondary battery 100, reducing the risk of the separator 23 preferentially melting and exacerbating the short circuit.
  • polyethylene or polypropylene with a melting point of 130-170 degrees Celsius can be used as the separator 23
  • polyethylene or polypropylene with a melting point of 100-130 degrees Celsius can be used as the first polymer. This allows the first polymer to melt before the separator 23 when a short circuit occurs in the secondary battery 100, further reducing the risk of the separator 23 preferentially melting and exacerbating the short circuit.
  • the first insulating protective layer 70 when the housing 10 is a packaging bag, the first insulating protective layer 70 is sandwiched within the edge seal 17.
  • the first insulating protective layer 70 also seals the first flow guide 50 and the edge seal 17. Specifically, the first insulating protective layer 70 fills any gaps between the second connection area 52 or the third connection area 53 and the edge seal 17, thereby sealing the first flow guide 50 and the edge seal 17. This reduces the risk of leakage and separation of the first flow guide 50 from the edge seal 17 during use, and also maintains electrical insulation between the first flow guide 50 and the housing 10.
  • the first insulating protective layer 70 can have a two-layer structure, comprising a first layer 71 and a second layer 72 stacked together.
  • the melting point of the second polymer can be higher than the melting point of the first polymer. In this case, when the melting point is reached inside the secondary battery 100, the first polymer melts in time, while the second polymer does not melt. This can also make The protective effect of the first insulating protective layer 70 on the second connection area 52 is weakened. In this case, the mass percentage of the first polymer in the first insulating protective layer 70 can be set to be greater than or equal to 50%, so that the protective effect of the first insulating protective layer 70 on the second connection area 52 is weakened when the interior of the secondary battery 100 reaches this melting point.
  • At least a portion of the second connection area 52 is located within the edge seal 17. As shown in Figure 7 , in other embodiments, at least a portion of the second connection area 52 may also be located outside the housing 10. When the protective effect of the first layer 71 on the second connection area 52 is weakened or even eliminated, the second connection area 52 located outside the housing 10 is more likely to break under mechanical abuse. As shown in Figure 8 , in other embodiments, at least a portion of the second connection area 52 may also be located within the accommodating portion 16.
  • the first connection region 51, the second connection region 52, and the third connection region 53 may also be coplanar. That is, the first flow guide 50 is not bent as a whole. In this case, the first connection region 51, the second connection region 52, and the third connection region 53 are arranged in the first direction X, and the plane of the first flow guide 50 is perpendicular to the second direction Y. After the first tab 30 is connected to the first flow guide 50, the first connection region 51 of the first flow guide 50 extends from the edge seal 17 along the first direction X and out of the housing 10.
  • FIG. 10 and 11 another embodiment of the present application also provides a secondary battery 200. Differences from the aforementioned secondary battery 100 include that the housing 10 can also be made of metal. Accordingly, the secondary battery 200 can be a cylindrical battery, a prismatic battery, or a button battery. Figures 10 and 11 illustrate the secondary battery 200 as a cylindrical battery, with the electrode assembly 20 having a wound structure. A coordinate system is established based on mutually perpendicular first and second directions X and Y. In the description of the present embodiment, the first direction X is the direction in which the first electrode tab 30 extends from the first electrode sheet 21. Any direction within a two-dimensional plane perpendicular to the first direction X can be considered the second direction Y of the present application.
  • the first insulating protective layer 70 is a single-layer structure.
  • the first insulating protective layer 70 may include a first polymer and a second polymer, with the mass percentage of the first polymer in the first insulating protective layer 70 being greater than or equal to 50%.
  • the first insulating protective layer 70 may also include only the first polymer, i.e., the mass percentage of the first polymer in the first insulating protective layer 70 is 100%.
  • the first current collector 210 of the first electrode sheet 21 includes a first edge 21a facing the first end wall 11, and the first electrode tab 30 is formed by extending from the first edge 21a.
  • the width of the first electrode tab 30 can be equal to the width of the first current collector 210. This prevents excessive current concentration in the first electrode sheet 21, reduces the internal resistance of the first electrode sheet 21, and thereby improves the charge and discharge rate of the first electrode sheet 21.
  • the first electrode tab 30 includes a first electrode tab region 31 connected to the first edge 21a and a second electrode tab region 32 connected to the first electrode tab region 31.
  • the second electrode tab region 32 is bent relative to the first electrode tab region 31 and forms a first end face 320.
  • a first connection region 51 is connected to the first end face 320, thereby connecting the first electrode tab 30 to the first electrode post 14 via the first current guide 50.
  • the first electrode post 14 can exhibit the same electrical polarity as the first electrode sheet 21.
  • a portion of the first tab 30 is flattened by a flattening device to form a flat surface.
  • the kneaded surface is the first end surface 320 formed by the second tab region 32 .
  • the second current collector 220 of the second electrode sheet 22 includes a second end edge 22a facing the second end wall 12, and the second electrode tab 40 is formed by extending from the second end edge 22a.
  • the width of the second electrode tab 40 can be equal to the width of the second current collector 220.
  • the second electrode tab 40 includes a third electrode tab region 41 connected to the second end edge 22a and a fourth electrode tab region 42 connected to the third electrode tab region 41.
  • the fourth electrode tab region 42 is bent relative to the third electrode tab region 41 and forms a second end face 420.
  • a portion of the second electrode tab 40 is flattened using a flattening device to form a flat surface.
  • the flat surface is the second end face 420 formed by the fourth electrode tab region 42.
  • the second end face 420 can be directly connected to the second end wall 12 or connected to the second end wall 12 via a second flow guide 60. In this way, the second end wall 12 can exhibit the same electrical polarity as the second electrode sheet 22.
  • the first flow guide 50 can be bent so that, when viewed along the thickness of the first connection region 51, the first connection region 51 and the third connection region 53 overlap.
  • Figure 12 shows the structure of the first flow guide 50 shown in Figure 11 after unfolding.
  • the third connection region 53 includes a third subregion 531 connected to the second connection region 52 and a fourth subregion 532 connected to the third subregion 531.
  • the first connection region 51, the second connection region 52, and the third subregion 531 are coplanar, and the fourth subregion 532 is bent relative to the third subregion 531. In other words, the bend of the first flow guide 50 is located in the third connection region 53.
  • the first connection area 51 is connected to the first end surface 320 , for example, the first connection area 51 can be welded to the first end surface 320 .
  • the fourth section 532 of the third connection area 53 is connected to the first pole 14 , for example, the fourth section 532 can be welded to the first pole 14 .
  • Figures 13 to 15 show that the secondary battery 200 is a square shell battery, in which case the electrode assembly 20 can be a wound structure or a laminated structure.
  • the housing 10 includes a first end wall 11 and a second end wall 12 arranged opposite to each other in a first direction X, a side wall 13 connected between the first end wall 11 and the second end wall 12, and a first pole 14 and a second pole 15 respectively provided on the first end wall 11.
  • the first pole 14 and the second pole 15 are both electrically isolated from the first end wall 11.
  • the first end wall 11 and the second end wall 12 can be arranged in parallel.
  • the side wall 13 and the second end wall 12 enclose a storage space for accommodating the electrode assembly 20 and the electrolyte, and the first end wall 11 covers the storage space.
  • Figure 16 is a schematic diagram of the structure of the first flow guide 50 shown in Figure 14 or Figure 15 after it is unfolded.
  • the first flow guide 50 may also include a bending area 54 and a transition area 55.
  • the transition area 55 includes a third side 551 and a fourth side 552 arranged adjacent to each other.
  • the second connection area 52 is connected to the third side 551.
  • the bending area 54 is connected between the fourth side 552 and the third connection area 53.
  • the bending area 54 is bent relative to both the transition area 55 and the third connection area 53. Observed from the thickness direction of the third connection area 53, the transition area 55 and the third connection area 53 overlap.
  • the transition region 55 and the third connection region 53 can jointly fill the gap between the housing 10 and the electrode assembly 20, reducing the shaking of the electrode assembly 20 within the housing 10 when the secondary battery 200 is subjected to mechanical abuse. Even if the electrode assembly 20 shakes within the housing 10 and pulls the first tab 30, the transition region 55 connected to the bend region 54 can provide a larger buffer space, reducing the risk of the first tab 30 detaching from the first flow guide 50 and causing the secondary battery 200 to malfunction.
  • FIG14 shows that the second segment 30b of the first tab 30 is connected to the transition region 55, it is understood that the first connection region 51 in FIG14 is actually located behind the transition region 55. Therefore, the second segment 30b of the first tab 30 is actually connected to the first connection region 51 located behind the transition region 55.
  • the secondary battery 100 or the secondary battery 200 of the present application may be a lithium secondary battery, including a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, and a lithium ion polymer secondary battery.
  • an embodiment of the present application further provides an electric device 1, comprising a battery compartment 101 and a secondary battery 100 (or secondary battery 200) housed in the battery compartment 101.
  • the electric device 1 is powered by the above-mentioned secondary battery 100, and the safety and reliability of the secondary battery 100 are improved.
  • the difference from the above-mentioned embodiment 1 lies in the relevant parameters of the first flow guide and the first insulating protective layer.
  • the difference from the above-mentioned embodiment 1 is that the first insulating protection layer is omitted.
  • the melting point test steps of the first polymer include: 1) discharging the secondary battery to 3V and then disassembling it, removing the first insulating protective layer covering the surface of the first tab, cleaning it, and drying it at 80°C to obtain a sample; 2) placing the sample in an aluminum crucible, the sample weight is 1 mg, and using a differential scanning calorimeter (instrument model: DSC214, manufacturer: NETZSCH, Germany) to test the DSC curve of the sample, the test temperature range is 60°C to 200°C, the heating rate is 10°C/min, and the DSC curve is analyzed to obtain the melting point.
  • a differential scanning calorimeter instrument model: DSC214, manufacturer: NETZSCH, Germany
  • the external short-circuit test steps of the secondary battery include: 1) charging the secondary battery to 100% SOC (State of Charge) under environmental conditions of 25 ⁇ 5°C; 2) placing the secondary battery in a test environment of 25 ⁇ 5°C, using a 10 ⁇ 2m ⁇ load resistor to short-circuit the first flow guide and the second flow guide of the secondary battery respectively. If the secondary battery does not catch fire or explode, test until the voltage is lower than 0.2V. Monitor the temperature change of the secondary battery during the test.
  • SOC State of Charge
  • the room temperature drop test steps for secondary batteries include: 1) charging the secondary battery to 100% SOC under environmental conditions of 25 ⁇ 5°C; 2) placing the secondary battery in a fixture compartment, and using an automatic dropping device to drop the bottom, side, and top of the secondary battery in sequence from a position of 1.8m to a steel plate, for a total of 6 rounds, or 18 drops; 3) disassembling the secondary battery after the drop, observing whether the second connection area of the first guide member is broken, and then calculating the fracture rate of the first guide member in each sample.
  • the high-temperature drop test steps for secondary batteries include: 1) inspecting the appearance of the secondary battery before and after the test and taking photos; 2) attaching a temperature sensing wire to the center of the surface of the secondary battery, and then placing the secondary battery vertically in a hot box, heating it to 130 ⁇ 2°C at a heating rate of 5 ⁇ 2°C and maintaining it for 10 minutes; 3) charging the secondary battery to 100% SOC under environmental conditions of 25 ⁇ 5°C; 4) placing the battery in a fixture compartment, and using an automatic dropping device to drop the bottom, side, and top of the battery in a round from a position of 1.8m to a steel plate, for a total of 6 rounds, or 18 times; 5) disassembling the secondary battery after the drop is completed, observing whether the second connection area of the first guide member is broken, and then calculating the fracture rate of the first guide member in each sample.
  • the test steps for the DC resistance (DCR) growth rate of the secondary battery include: 1) Under the environmental conditions of 25 ⁇ 5°C, the secondary battery is charged to 4.48V at a constant current of 0.7C, then charged to a current of 0.05C at a constant voltage, then discharged at a constant current of 0.1C for 10s, and the voltage before discharge V 0 is measured, then discharged at a constant current of 1C for 1s, and the voltage after discharge V 1 is measured.
  • the initial DCR of the battery is (V 1 -V 0 )/1C; 2) 30 charge and discharge cycles are performed according to the same charge and discharge steps as above, and then the voltage after the cycle is measured.
  • DCR after the cycle; 3) calculate the DCR growth rate after the cycle (DCR after the cycle - initial DCR) / initial DCR ⁇ 100%.
  • Examples 4 and 9-14 satisfy the requirement of 0.1S 2 ⁇ S 1 , reducing the risk of the second connection region fusing during normal secondary battery operation and fracturing during a room-temperature drop. Consequently, the second connection region does not rupture during normal cycling, the DCR growth rate of the secondary battery is low, and the secondary battery can operate normally.
  • Examples 4 and 9-14 satisfy the requirement of S 1 ⁇ 0.5S 2 , allowing the second connection region to fuse promptly when a short circuit occurs. This reduces the fracturing rate of the first flow guide after a short circuit, improving the safety of the secondary battery.
  • Example 4 Comparing Example 4 with Examples 9-14, it can be seen that when the minimum cross-sectional area S1 of the second connection region gradually increases within a predetermined range, the sensitivity of the second connection region to short-circuit current and high temperature decreases accordingly, thereby reducing the safety of the secondary battery.
  • the DCR growth rate of the secondary battery also decreases, which is beneficial to the normal cycling of the secondary battery. Therefore, when Examples 4 and 10-11 meet the condition of 0.2S2 ⁇ S1 ⁇ 0.4S2 , the sensitivity of the second connection region to short-circuit current and high temperature is high, while the secondary battery has a low DCR growth rate, allowing the secondary battery to achieve both high safety and cycling performance.

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Abstract

一种二次电池（72）和用电装置。二次电池（72）包括壳体（1）、设于壳体（1）内的电极组件（17）、以及第一极耳（23）。电极组件（17）包括第一极片（20），第一极耳（23）连接于第一极片（20）。二次电池（72）还包括第一导流件（42）和第一绝缘保护层（60）。至少部分第一导流件（42）设于壳体（1）内。第一导流件（42）包括第一连接区（50）、至少一第二连接区（51）、以及第三连接区（52），第二连接区（51）连接于第一连接区（50）和第三连接区（52）之间。第一连接区（50）连接于第一极耳（23）。第三连接区（52）连接于壳体（1）。第二连接区（51）沿第二连接区（51）的厚度方向的最小截面积为S 1，第三连接区（52）沿第三连接区（52）的厚度方向的截面积为S 2，至少一第二连接区（51）满足：0.1S 2≤S 1≤0.5S 2。第一绝缘保护层（60）至少覆盖第二连接区（51）的表面。第一绝缘保护层（60）包括第一聚合物，第一聚合物的熔点为100摄氏度至170摄氏度。

Description

二次电池和用电装置 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该二次电池的用电装置。
背景技术
随着二次电池(如锂离子电池)在电子移动设备、电动工具及电动汽车等电子产品中广泛使用，人们对二次电池(例如，锂离子二次电池)的要求越来越严格。
然而，二次电池在工作中时可能会发生短路，导致二次电池内的温度持续增加，引发安全问题。而且，若二次电池内部发生大电流放电、微短路、或所处环境温度较高，虽然此时二次电池的内部温度可能未达到短路下的高温，但同样存在安全隐患，若继续使用会导致安全问题。
发明内容
有鉴于此，有必要提供一种能够提高安全性和可靠性的二次电池和具有上述二次电池的用电装置。
本申请第一方面提供一种二次电池，包括壳体、设于壳体内的电极组件、以及第一极耳。电极组件包括第一极片，第一极耳连接于第一极片。二次电池还包括第一导流件和第一绝缘保护层。至少部分第一导流件设于壳体内。第一导流件包括第一连接区、至少一第二连接区、以及第三连接区，第二连接区连接于第一连接区和第三连接区之间。第一连接区连接于第一极耳。第三连接区连接于壳体。第二连接区沿第二连接区的厚度方向的最小截面积为S1，第三连接区沿第三连接区的厚度方向的截面积为S2，至少一第二连接区满足：0.1S2≤S1≤0.5S2。第一绝缘保护层至少覆盖第二连接区的表面。第一绝缘保护层包括第一聚合物，第一聚合物的熔点为100摄氏度至170摄氏度。
本申请中，在二次电池正常工作时，第一绝缘保护层能够覆盖最小截面积较小的第二连接区，在二次电池发生机械滥用时保护第二连接区，减小第二连接区断裂的风险。通过设置S1与S2的关系，在二次电池发生短路时，第二连接区能够在短路电流作用下优先熔断，断开第一极耳与外部元件的连接，减小内部温度继续上升导致的安全问题，同时也可减小二次电池正常工作时第二连接区熔断对二次电池使用寿命的影响。另一方面，在二次电池内部达到第一聚合物的熔点(如二次电池所处环境温度较高，存在安全隐患)时，第一聚合物及时熔融，使得第一绝缘保护层对第二连接区的保护作用减弱甚至消失，从而使得第二连接区容易在机械滥用时断裂，阻止存在安全隐患的二次电池继续工作。因此第二连接区和第一绝缘保护层共同作用，可提高二次电池的安全性和可靠性。
基于第一方面，在一些可能的实现方式中，电极组件还包括隔离膜，第一聚合物的熔点小于或等于隔离膜的熔点。如此，可使得二次电池发生短路时第一聚合物先于隔离膜熔 融或与隔离膜同时熔融，减小隔离膜优先熔融导致短路加剧的风险。
基于第一方面，在一些可能的实现方式中，第一聚合物的材质选自聚丙烯(PP)、聚乙烯(PE)、聚对苯二甲酸乙二醇酯(PET)、聚萘二甲酸乙二醇酯(PEN)、聚丙烯改性材料或聚乙烯改性材料中的至少一种。
基于第一方面，在一些可能的实现方式中，第一绝缘保护层还覆盖部分第一连接区的表面和部分第三连接区的表面。如此，在二次电池正常工作时，使得第一绝缘保护层可充分保护第二连接区，减小机械滥用时第二连接区断裂的风险。
基于第一方面，在一些可能的实现方式中，至少一第二连接区满足：0.2S2≤S1≤0.4S2。如此，第二连接区在短路电流和高温下更加灵敏，不仅在二次电池发生短路时可及时熔断，而且在二次电池存在安全隐患使第一聚合物熔融后，第二连接区更容易在机械滥用时断裂，从而一步提高二次电池的安全性。再者，在二次电池正常工作时，可进一步减小第二连接区熔断导致对二次电池使用寿命的影响。
基于第一方面，在一些可能的实现方式中，沿第二连接区的厚度方向观察，第二连接区包括相对设置的第一边和第二边。第一边和第二边均连接于第一连接区和第三连接区之间。第一边为弯曲形状。第一边包括连接于第一连接区的第一端点、连接于第三连接区的第二端点、以及设于第一端点和第二端点之间的顶部。顶部相较于第一端点以及第二端点朝向第二连接区的内部凹进。如此，使得二次电池发生短路时，第二连接区在对应该顶部的位置优先熔断。
基于第一方面，在一些可能的实现方式中，第一边至少部分为折线形。如此，当第一绝缘保护层对第二连接区的保护作用减弱甚至消失时，第二连接区更容易在机械滥用时断裂，阻止存在安全隐患的二次电池继续工作。
基于第一方面，在一些可能的实现方式中，第二连接区的厚度小于第一连接区和第三连接区中任一者的厚度。如此，使得每一第二连接区的最小截面积较小。
基于第一方面，在一些可能的实现方式中，第一连接区、第二连接区以及第三连接区为一体式结构。如此，在二次电池正常工作时，第二连接区在机械滥用下断裂的风险降低。
基于第一方面，在一些可能的实现方式中，壳体为包装袋，其包括相连接的容纳部和封边，电极组件容纳于容纳部内，至少部分第二连接区位于封边内、容纳部内或壳体外，至少部分第三连接区伸出壳体。第一绝缘保护层包括层叠设置的第一层和第二层。第一层包括上述第一聚合物。第二层包括第二聚合物，且第二聚合物的熔点为160度至170度。第二层与封边和第一层分别连接。如此，使得第三连接区可连接外部元件，且第一绝缘保护层的第二层具有较高的密封性能，可减小使用过程中漏液的风险以及第一导流件与封边发生分离的风险，还可使得第一导流件与壳体之间维持电绝缘。
基于第一方面，在一些可能的实现方式中，第一连接区、第二连接区以及第三连接区共面。
基于第一方面，在一些可能的实现方式中，第一连接区包括连接于第二连接区的第一分区和连接于第一分区的第二分区。第二连接区、第三连接区以及第一分区共面。第二分 区相较于第一分区弯折。第二分区连接于第一极耳。由于第一导流件的弯折处位于第一连接区而非第二连接区，当二次电池正常工作时，减小了最小截面积较小的第二连接区在机械滥用下容易断裂的风险。
基于第一方面，在一些可能的实现方式中，壳体为金属壳体，其包括相对设置的第一端壁和第二端壁、连接于第一端壁和第二端壁之间的侧壁、以及设于第一端壁的第一极柱。第一极柱与第一端壁电性隔绝。第三连接区连接于第一极柱。如此，可使得第一极柱具有与第一极片相同的电极性。
基于第一方面，在一些可能的实现方式中，电极组件为卷绕结构。第一极片包括第一集流体。第一集流体包括朝向第一端壁的第一端边，第一极耳由第一端边延伸形成。第一极耳包括连接第一端边的第一极耳区和连接第一极耳区的第二极耳区。第二极耳区相较于第一极耳区弯折并形成第一端面，第一连接区连接于第一端面。全极耳结构使得第一极片的电流分布不会过于集中，降低第一极片的内阻，从而提高第一极片的充放电倍率。第二极耳区形成第一端面，便于第二极耳区与第一连接区连接。
基于第一方面，在一些可能的实现方式中，第三连接区包括连接于第二连接区的第三分区和连接于第三分区的第四分区。第一连接区、第二连接区以及第三分区共面，第四分区相较于第三分区弯折。沿第一连接区的厚度方向观察，第一连接区和第四分区存在重叠。由于第一导流件的弯折处位于第三连接区而非第二连接区，当二次电池正常工作时，减小了最小截面积较小的第二连接区在机械滥用下容易断裂的风险。
基于第一方面，在一些可能的实现方式中，第一导流件还包括弯折区和转接区。转接区包括相邻设置的第三边和第四边。第二连接区连接于第三边。弯折区连接于第四边和第三连接区之间。弯折区相对转接区和第三连接区均弯折。从第三连接区的厚度方向观察，转接区和第三连接区存在重叠。转接区和第三连接区能够共同填充壳体与电极组件之间的间隙，当二次电池发生机械滥用时减小电极组件在壳体内的晃动，且即便电极组件在壳体内晃动进而拉扯第一极耳，连接于弯折区的转接区能够提供较大的缓冲空间，减小第一极耳脱离第一导流件而导致二次电池无法正常工作的风险。
本申请第二方面还提供一种用电装置，包括电池仓和如上二次电池。二次电池容置于电池仓中。用电装置通过上述二次电池供电，且二次电池的安全性和可靠性得到改善。
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1所示的二次电池于另一些实施例中沿剖切线II-II的剖视图。
图4A为图1所示的二次电池于一些实施例中沿剖切线IV-IV的剖视图。
图4B为图4A所示的二次电池于IVA处的局部放大图。
图5A为图4所示的二次电池的第一导流件于一些实施例中的展开图。
图5B为图4所示的二次电池的第一导流件于另一些实施例中的展开图。
图5C为图4所示的二次电池的第一导流件于另一些实施例中的展开图。
图5D为图4所示的二次电池的第一导流件于另一些实施例中的展开图。
图6为图5A所示的二次电池的第一导流件的仰视图。
图7为图1所示的二次电池于另一些实施例中沿剖切线IV-IV的局部放大剖视图。
图8为图1所示的二次电池于另一些实施例中沿剖切线IV-IV的局部放大剖视图。
图9为图1所示的二次电池于另一些实施例中沿剖切线IV-IV的剖视图。
图10为本申请另一实施方式提供的二次电池的结构示意图。
图11为图10所示的二次电池沿剖切线XII-XII的剖视图。
图12为图11所示的二次电池的第一导流件的展开图。
图13为本申请另一实施方式提供的二次电池的结构示意图。
图14为图13所示的二次电池沿剖切线XV-XV的剖视图。
图15为图13所示的二次电池沿剖切线XVI-XVI的剖视图。
图16为图14或图15所示的二次电池的第一导流件的展开图。
图17为本申请一实施方式提供的用电装置的结构示意图。
主要元件符号说明
用电装置             1
壳体                 10
第一端壁             11
第二端壁             12
侧壁                 13
第一极柱             14
第二极柱             15
容纳部               16
封边                 17
电极组件             20
第一极片             21
第一端边             21a
第二极片             22
第二端边             22a
隔离膜               23
第一极耳             30
第一段               30a
第二段               30b
第一极耳区           31
第二极耳区           32
第二极耳             40
第三极耳区           41
第四极耳区           42
第一导流件           50
第一连接区           51
第二连接区           52
第三连接区           53
弯折区               54
转接区               55
第二导流件           60
第一绝缘保护层       70
第一层               71
第二层               72
二次电池             100、200
电池仓               101
第一集流体           210
第一活性材料层       211
第二集流体           220
第二活性材料层       221
第一端面             320
第二端面             420
第一分区             511
第二分区             512
第一边               521
第二边               522
第三分区             531
第四分区             532
第三边              551
第四边              552
顶部                5210
第一端点            5211
第二端点            5212
第一方向            X
第二方向            Y
第三方向            Z
截面积              S1、S2
宽度                W1、W2、W3
厚度                H1、H2、H3
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“和/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。
如本文中所使用，属于“平行”、“垂直”用于描述两个部件之间的理想状态。实际生产或使用的状态中，两个部件之间可以存在近似于平行或垂直的状态。举例来说，结合数值描述，平行可以指代两直线之间夹角范围在±10°之间，平行也可以指代两平面的二面角范围在±10°之间，平行还可以指代直线与平面之间的夹角范围在±10°之间。垂直可以指代两直线之间夹角范围在90±10°之间，垂直也可以指代两平面的二面角范围在90±10°之间，垂直还可以指代直线与平面之间的夹角范围在90±10°之间。被描述“平行”、“垂直”的两个部件可以不是绝对的直线、平面，也可以大致呈直线或平面，从宏观来看整体延伸方向为直线或平面即可认为部件为“直线”或“平面”。
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4A，本申请一实施方式提供一种二次电池100，包括壳体10、设于壳体10内的至少一电极组件20和电解液(图未示)、第一极耳30以及第二极耳40。在一些实施例中，壳体10可以为包装袋，对应地，二次电池100可以为软包电池。壳体10包括相连接的容纳部16和封边17。电极组件20容纳于容纳部16内。
以电极组件20的数量为一个进行说明，如图2所示，电极组件20可以为卷绕结构，其包括第一极片21、第二极片22和隔离膜23。隔离膜23设置于第一极片21和第二极片22之间，隔离膜23用于防止第一极片21和第二极片22直接接触，从而降低第一极片21和第二极片22发生接触短路的可能性。第一极耳30的数量可以为一个或多个，其电连接于第一极片21并伸出第一极片21。第二极耳40的数量可以为一个或多个，其电连接于第二极片22并伸出第二极片22。如图3所示，在另一些实施例中，电极组件20还可以为叠片结构，其包括多个第一极片21、多个第二极片22和多个隔离膜23。叠片结构中第一极片21和第二极片22依次交替堆叠，每相邻两个第一极片21中设有一个第二极片22，每相邻两个第二极片22中设有一个第一极片21。隔离膜23设置于相邻的第一极片21和第二极片22之间。
其中，根据相互垂直的第一方向X、第二方向Y和第三方向Z建立三维坐标系。在本申请实施例的说明中，第一方向X为第一极耳30伸出第一极片21的方向，第二方向Y为电极组件20的厚度方向，第三方向Z为第一极耳30至第二极耳40的方向。
如图2至图4A所示，第一极片21包括叠设的第一集流体210和第一活性材料层211。其中，第一极片21可以是正极极片。对应地，第一集流体210可以是正极集流体，第一活性材料层211可以是正极活性材料层。第二极片22包括叠设的第二集流体220和第二活性材料层221。其中，第二极片22可以是负极极片。对应地，第二集流体220可以是负极 集流体，第二活性材料层221可以是负极活性材料层。其中，当电极组件20为卷绕结构时，第一极耳30可通过焊接或其它方式连接于第一集流体210的表面，第二极耳40可通过焊接或其它方式连接于第二集流体220的表面。当电极组件20为叠片结构时，第一极耳30可与第一集流体210一体成型，第二极耳40可与第二集流体220一体成型。
正极集流体可以采用铝箔或镍箔，负极集流体可以采用铜箔、镍箔或碳基集流体中的至少一种。正极活性材料层包含正极活性材料，正极活性材料包括可逆地嵌入和脱嵌锂离子的化合物(锂化插层化合物)。在一些实施例中，正极活性材料可以包括锂过渡金属复合氧化物。该锂过渡金属复合氧化物含有锂以及从钴、锰和镍中选择的至少一种元素。在一些实施例中，正极活性材料选自钴酸锂(LiCoO2)、锂镍锰钴三元材料(NCM)、锰酸锂(LiMn2O4)、镍锰酸锂(LiNi0.5Mn1.5O4)或磷酸铁锂(LiFePO4)中的至少一种。
负极活性材料层包含负极活性材料，采用本领域已知的能够进行活性离子可逆脱嵌的负极活性材料，本申请不做限制。例如，可以是包括但不限于石墨、软碳、硬碳、碳纤维、中间相碳微球、硅基材料、锡基材料、钛酸锂或其他能与锂形成合金的金属等中的一种或多种的组合。其中，石墨可选自人造石墨、天然石墨以及改性石墨中的一种或多种的组合；硅基材料可选自单质硅、硅氧化合物、硅碳复合物、硅合金中的一种或多种的组合；锡基材料可选自单质锡、锡氧化合物、锡合金等中的一种或多种的组合。
隔离膜23包括聚乙烯、聚丙烯、聚偏氟乙烯、聚对苯二甲酸乙二醇酯、聚酰亚胺或芳纶中的至少一种。例如，聚乙烯包括选自高密度聚乙烯、低密度聚乙烯或超高分子量聚乙烯中的至少一种。其中聚乙烯和聚丙烯，它们对改善短路具有良好的作用。
结合参照图4A至图5A，二次电池100还包括第一导流件50和第一绝缘保护层70，其中图5A为图4A和图4B所示的第一导流件50处于展开状态时的结构示意图。至少部分第一导流件50设于壳体10内。第一导流件50连接于第一极耳30并伸出壳体10，且第一导流件50可以连接外部元件(图未示)。第一导流件50包括第一连接区51、至少一第二连接区52、以及第三连接区53。每一第二连接区52连接于第一连接区51和第三连接区53之间。第一连接区51连接于第一极耳30，例如，第一连接区51可以与第一极耳30焊接固定，从而提高第一连接区51与第一极耳30之间的连接强度。如图4A和图4B所示，至少部分第二连接区52可以位于封边17内。第三连接区53连接于壳体10，例如，第三连接区53可连接于封边17并从封边17伸出壳体10。其中，第一导流件50可以为一体式结构，即第一连接区51、第二连接区52、以及第三连接区53一体连接，因此在二次电池100正常工作时，第二连接区52在机械滥用下断裂的风险降低。在另一些实施例中，第一连接区51、第二连接区52以及第三连接区53也可以通过焊接或其它方式连接在一起。第一导流件50的材质可以为铝、镍、铜、钢、或铜镀镍等中的一种。
如图4A和图4B所示，在一些实施例中，第一极耳30呈弯折设置。第一极耳30包括连接第一极片21的第一段30a和连接第一段30a的第二段30b，第二段30b相较于第一段30a弯折设置。第一连接区51连接于第一极耳30的第二段30b。通过将第一极耳30弯折设置，有利于降低第一极耳30在第一方向X上占用电极组件20一侧的空间，从而提高二 次电池200的能量密度。
在一些实施例中，第一导流件50可弯折设置。第一连接区51包括连接于第二连接区52的第一分区511和连接于第一分区511的第二分区512。第二连接区52、第三连接区53以及第一分区511共面，第二分区512相较于第一分区511弯折。即，第一导流件50的弯折处位于第一连接区51。第二分区512连接于第一极耳30。此时第一分区511、第二连接区52以及第三连接区53沿着第一方向X排列，第二连接区52、第三连接区53以及第一分区511所在的平面垂直于第二方向Y。
如图6所示，其中图6为图5A所示的二次电池100的第一导流件50的仰视图，每一第二连接区52沿第二连接区52的厚度方向的最小截面积为S1，第三连接区53沿第三连接区53的厚度方向的截面积为S2，至少一第二连接区52满足：0.1S2≤S1≤0.5S2。由于每一第二连接区52的最小截面积S1较小，因此在二次电池100发生短路时，第二连接区52能够在短路电流作用下优先熔断，同时也可减小二次电池100正常工作时第二连接区52熔断对二次电池100使用寿命的影响。可以理解，如图4A和图4B所示，当第一导流件50弯折设置时，第二连接区52的厚度方向以及第三连接区53的厚度方向均为第二方向Y。由于第一导流件50的弯折处位于第一连接区51而非第二连接区52，减小了最小截面积较小的第二连接区52在二次电池100发生机械滥用(如振动、跌落)时容易断裂导致二次电池100无法正常工作的风险。在一些实施例中，第二连接区52的数量为两个或两个以上，设置多个第二连接区52，可减小二次电池100发生机械滥用时第二连接区52全部断裂导致二次电池100无法正常工作的风险，且设置每一第二连接区52的最小截面积S1较小，使得在二次电池100发生短路时每一第二连接区52能够在短路电流作用下优先熔断。
在一些实施例中，每一第二连接区52满足：0.2S2≤S1≤0.4S2。通过进一步限定S1的上限，使得第二连接区52在短路电流和高温下更加灵敏，不仅在二次电池100发生短路时可及时熔断，而且在二次电池100存在安全隐患使第一聚合物熔融后，第二连接区52更容易在机械滥用时断裂，从而一步提高二次电池100的安全性。通过进一步限定S1的下限，从而在二次电池100正常工作时，可进一步减小第二连接区52熔断对二次电池100使用寿命的影响。
如图6所示，在一些实施例中，每一第二连接区52的厚度H2小于第一连接区51的厚度H1，也小于第三连接区53的厚度H3，从而使得每一第二连接区52的最小截面积S1较小。第一连接区51和第三连接区53的厚度可以相同，也可以不同。在另一些实施例中，每一第二连接区52的厚度H2也可以等于第一连接区51的厚度H1或等于第三连接区53的厚度H3，同时在第二方向Y上(图6中两个第二连接区52的排列方向即为第二方向Y)，每一第二连接区52的宽度W2小于第一连接区51的宽度W1或小于第三连接区53的宽度W3，这也可使得每一第二连接区52的最小截面积S1较小。
如图5A所示，在一些实施例中，沿第二连接区52的厚度方向观察，第二连接区52包括相对设置的第一边521和第二边522。第一边521和第二边522均连接于第一连接区51和第三连接区53之间。沿第二连接区52的厚度方向观察，第一边521和第二边522可均 为直线形。此时，每一第二连接区52的最小截面积S1即为沿第二连接区52的厚度方向作经过第一边521任一点的截面时该截面的面积。
如图4A至图5A所示，第一绝缘保护层70至少覆盖第二连接区52的表面。由于第一绝缘保护层70能够覆盖最小截面积较小的第二连接区52，因此在二次电池100发生机械滥用时保护第二连接区52，减小第二连接区52断裂(如跌落时，电极组件20在壳体10内晃动，进而拉扯第一极耳30和第一导流件50，导致第二连接区52断裂)导致二次电池100无法正常工作的风险。在一些实施例中，第一绝缘保护层70可覆盖第二连接区52的多个表面以将第二连接区52包裹于其中，从而在二次电池100正常工作时，第一绝缘保护层70可充分保护第二连接区52，减小机械滥用时第二连接区52断裂的风险。第一绝缘保护层70还可覆盖部分第一连接区51的表面和部分第三连接区53的表面，从而在二次电池100正常工作时，第一绝缘保护层70可充分保护第二连接区52。
而且，第一绝缘保护层70包括第一聚合物，第一聚合物的熔点为100摄氏度至170摄氏度，使得当二次电池100内部达到该熔点时(如二次电池100内部发生大电流放电或微短路、或环境温度较高，虽然此时二次电池100的内部温度未达到短路高温，但同样存在安全隐患)，第一聚合物及时熔融，进而使得第一绝缘保护层70对第二连接区52的保护作用减弱甚至消失，从而使得第二连接区52容易在机械滥用时断裂，阻止存在安全隐患的二次电池100继续工作。在一些实施例中，第一聚合物的材质选自聚丙烯(PP)、聚乙烯(PE)、聚对苯二甲酸乙二醇酯(PET)、聚萘二甲酸乙二醇酯(PEN)、聚丙烯改性材料或聚乙烯改性材料中的至少一种。例如，聚乙烯可选自熔点为108-126摄氏度的低密度聚乙烯(LDPE)、熔点为126-140摄氏度的高密度聚乙烯(HDPE)、或熔点为110-125摄氏度的线性低密度聚乙烯(LLDPE)中的至少一种，因此可通过选择不同种类的聚乙烯以调整第一聚合物的熔点。另外聚乙烯添加其它材料进行改性处理得到的聚乙烯改性材料也可以具有不同的熔点。同理，当第一聚合物包括聚丙烯等其它组分时，也可通过相似的方法调整第一聚合物的熔点。可选地，第一聚合物的熔点为100摄氏度至130摄氏度，从而在二次电池100存在安全隐患时提高第一聚合物的灵敏度。
在本申请中，在二次电池100正常工作时，第一绝缘保护层70能够覆盖最小截面积较小的第二连接区52，在二次电池100发生机械滥用时保护第二连接区52，减小第二连接区52断裂的风险。在二次电池100发生短路时，最小截面积较小的第二连接区52能够在短路电流作用下优先熔断，断开第一极耳30与外部元件的连接即二次电池100处于开路状态，减小内部温度继续上升导致的安全问题。另一方面，在二次电池100内部达到第一聚合物的熔点时，第一绝缘保护层70的第一聚合物及时熔融，使得第一绝缘保护层70对第二连接区52的保护作用减弱甚至消失，从而使得第二连接区52容易在机械滥用时断裂，阻止存在安全隐患的二次电池100继续工作。因此第二连接区52和第一绝缘保护层70共同作用，可提高二次电池100的安全性和可靠性。
其中，二次电池100还可包括第二导流件60和第二绝缘保护层(图未示)，第二导流件60连接于第二极耳40。为进一步提高二次电池100在发生短路时的安全性和可靠性， 可设置第二导流件60具有与第一导流件50相似的结构，第二绝缘保护层具有与第一绝缘保护层70相似的结构。
请参阅图5B至图5D，在另一些实施例中，沿第二连接区52的厚度方向观察，第一边521还可以为弯曲形状即非直线形。第一边521包括连接于第一连接区51的第一端点5211、连接于第三连接区53的第二端点5212、以及设于第一端点5211和第二端点5212之间的顶部5210。顶部5210相较于第一端点5211以及第二端点5212朝向第二连接区52的内部凹进。由于第一边521为弯曲形状且第一边521的顶部5210朝向第二连接区52的内部凹进，因此第二连接区52的最小截面积即为沿第二连接区52的厚度方向作经过顶部5210的截面时该截面的面积，使得二次电池100发生短路时第二连接区52在对应该顶部5210的位置优先熔断。进一步地，在一些具体地实施例中，第一边521至少部分可以为折线形。其中，如图5B所示，第一边521为梯形的部分轮廓线，第一边521的顶部5210为梯形的上底。如图5C所示，第一边521为V字形，第一边521的顶部5210可以为尖顶。如图5D所示，第一边521为锯齿形，第一边521的顶部5210为锯齿的峰。通过设置第一边521至少部分为折线形，当第一绝缘保护层70对第二连接区52的保护作用减弱甚至消失时，第二连接区52更容易在机械滥用时断裂，阻止存在安全隐患的二次电池100继续工作。其中，第二边522的形状可以与第一边521的形状相同。每一第二连接区52的宽度W2为该第二连接区52中第一边521的顶部5210至第二边522的顶部(图未标示)之间的距离。
在一些实施例中，第一聚合物的熔点小于或等于隔离膜23的熔点。如此，可使得二次电池100发生短路时第一聚合物先于隔离膜23熔融或与隔离膜23同时熔融，减小隔离膜23优先熔融导致短路加剧的风险。例如，可采用熔点为130-170摄氏度的聚乙烯或聚丙烯作为隔离膜23，同时采用熔点为100-130摄氏度的聚乙烯或聚丙烯作为第一聚合物，使得二次电池100发生短路时第一聚合物先于隔离膜23熔融，从而进一步减小隔离膜23优先熔融导致短路加剧的风险。
如图4A和图4B所示，当壳体10为包装袋时，第一绝缘保护层70夹设于封边17内，第一绝缘保护层70还密封连接第一导流件50和封边17。具体地，第一绝缘保护层70可填充第二连接区52或第三连接区53与封边17之间可能存在的间隙，从而密封连接第一导流件50和封边17，且减小了使用过程中漏液的风险以及第一导流件50与封边17发生分离的风险，还可使得第一导流件50与壳体10之间维持电绝缘。第一绝缘保护层70可为双层结构，其包括层叠设置的第一层71和第二层72。第一层71包括上述第一聚合物，因此在二次电池100内部达到第一聚合物的熔点时第一层71能够及时熔融。第二层72包括第二聚合物，且第二聚合物的熔点为160度至170度，如第二聚合物可采用熔点为160度至170度的聚丙烯。第二层72与封边17和第一层71分别连接，第二层71具有较高的密封性能，能够进一步减小使用过程中漏液的风险以及第一导流件50与封边17发生分离的风险。在另一些实施例中，第一绝缘保护层70也可以为单层结构，第一绝缘保护层70除第一聚合物外还可包括第二聚合物，第二聚合物的熔点可高于第一聚合物的熔点，此时当二次电池100内部达到该熔点时第一聚合物及时熔融，而第二聚合物未熔融，这也可使 得第一绝缘保护层70对第二连接区52的保护作用减弱。此时，可设置第一聚合物在第一绝缘保护层70中的质量百分比大于或等于50％，从而使得二次电池100内部达到该熔点时第一绝缘保护层70对第二连接区52的保护作用减弱。
如图4A和图4B所示，在一些实施例中，至少部分第二连接区52位于封边17内。如图7所示，在另一些实施例中，至少部分第二连接区52还可以位于壳体10外，当第一层71对第二连接区52的保护作用减弱甚至消失时，位于壳体10外的第二连接区52更容易在机械滥用时断裂。如图8所示，在另一些实施例中，至少部分第二连接区52还可以位于容纳部16内。
如图9所示，在另一些实施例中，第一连接区51、第二连接区52以及第三连接区53也可以共面。即，第一导流件50整体未弯折。此时第一连接区51、第二连接区52以及第三连接区53的排列方向即为第一方向X，第一导流件50所在平面垂直于第二方向Y。当第一极耳30连接于第一导流件50后，第一导流件50的第一连接区51沿着第一方向X从封边17伸出壳体10。
请参阅图10和图11，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不同之处包括，壳体10还可以为金属材质，对应地，二次电池200可以为圆柱电池、方壳电池或扣式电池。图10和图11示出二次电池200为圆柱电池，且电极组件20为卷绕结构。其中，根据相互垂直的第一方向X和第二方向Y建立坐标系，在本申请实施例的说明中，第一方向X为第一极耳30伸出第一极片21的方向，在垂直于第一方向X的二维平面内的任一方向都可视为本申请的第二方向Y。在一些实施例中，壳体10包括在第一方向X上相对设置的第一端壁11和第二端壁12、连接于第一端壁11和第二端壁12之间的侧壁13、以及设于第一端壁11的第一极柱14。侧壁13和第二端壁12围设形成用于容纳电极组件20和电解液的容纳空间，第一端壁11盖合于该容纳空间。第一极柱14与第一端壁11电性隔绝。此时，第三连接区53连接于第一极柱14。
当壳体10为金属材质时，第一绝缘保护层70为单层结构，第一绝缘保护层70可包括第一聚合物和第二聚合物，第一聚合物在第一绝缘保护层70中的质量百分比大于或等于50％。第一绝缘保护层70也可以仅包括第一聚合物，即第一聚合物在第一绝缘保护层70中的质量百分比为100％。
如图11所示，第一极片21的第一集流体210包括朝向第一端壁11的第一端边21a，第一极耳30由第一端边21a延伸形成。沿着第一端边21a在电极组件20中的延伸方向，第一极耳30的宽度可等于第一集流体210的宽度，这能够使得第一极片21的电流分布不会过于集中，降低第一极片21的内阻，从而提高第一极片21的充放电倍率。第一极耳30包括连接第一端边21a的第一极耳区31和连接第一极耳区31的第二极耳区32。第二极耳区32相较于第一极耳区31弯折并形成第一端面320。第一连接区51连接于第一端面320，从而将第一极耳30通过第一导流件50连接至第一极柱14。如此，第一极柱14可呈现与第一极片21相同的电极性。制作时，将部分第一极耳30通过揉平设备揉平形成揉平面， 揉平面即为第二极耳区32形成的第一端面320。
第二极片22的第二集流体220包括朝向第二端壁12的第二端边22a，第二极耳40由第二端边22a延伸形成。沿着第二端边22a在电极组件20中的延伸方向，第二极耳40的宽度可等于第二集流体220的宽度。第二极耳40包括连接第二端边22a的第三极耳区41和连接第三极耳区41的第四极耳区42。第四极耳区42相较于第三极耳区41弯折并形成第二端面420。制作时，将部分第二极耳40通过揉平设备揉平形成揉平面，揉平面即为第四极耳区42形成的第二端面420。第二端面420可直接连接于第二端壁12或通过第二导流件60连接于第二端壁12。如此，第二端壁12可呈现与第二极片22相同的电极性。
如图11所示，在一些实施例中，第一导流件50可弯折设置，使得沿第一连接区51的厚度方向观察，第一连接区51和第三连接区53存在重叠。具体地，请一并参照图12，其中图12为图11所示的第一导流件50展开后的结构示意图。在一些实施例中，第三连接区53包括连接于第二连接区52的第三分区531和连接于第三分区531的第四分区532。第一连接区51、第二连接区52以及第三分区531共面，第四分区532相较于第三分区531弯折。即，第一导流件50的弯折处位于第三连接区53，当二次电池100正常工作时，减小了最小截面积较小的第二连接区52在机械滥用下容易断裂的风险。沿第一连接区51的厚度方向观察，第一连接区51和第四分区532存在重叠。第一连接区51连接于第一端面320，如，第一连接区51可焊接固定于第一端面320。第三连接区53的第四分区532连接于第一极柱14，如，第四分区532可焊接固定于第一极柱14。
图13至图15示出二次电池200为方壳电池，此时电极组件20可以为卷绕结构或叠片结构。在一些实施例中，壳体10包括在第一方向X上相对设置的第一端壁11和第二端壁12、连接于第一端壁11和第二端壁12之间的侧壁13、以及分别设于第一端壁11的第一极柱14和第二极柱15。第一极柱14和第二极柱15均与第一端壁11电性隔绝。第一端壁11和第二端壁12可平行设置。侧壁13和第二端壁12围设形成用于容纳电极组件20和电解液的容纳空间，第一端壁11盖合于容纳空间。
请一并参阅图16，其中图16为图14或图15所示的第一导流件50展开后的结构示意图。第一导流件50除包括第一连接区51、第二连接区52以及第三连接区53外，还可包括弯折区54和转接区55。转接区55包括相邻设置的第三边551和第四边552。第二连接区52连接于第三边551。弯折区54连接于第四边552和第三连接区53之间。弯折区54相对转接区55和第三连接区53均弯折。从第三连接区53的厚度方向观察，转接区55和第三连接区53存在重叠。转接区55和第三连接区53能够共同填充壳体10与电极组件20之间的间隙，当二次电池200发生机械滥用时减小电极组件20在壳体10内的晃动，且即便电极组件20在壳体10内晃动进而拉扯第一极耳30，连接于弯折区54的转接区55能够提供较大的缓冲空间，减小第一极耳30脱离第一导流件50而导致二次电池200无法正常工作的风险。其中，虽然图14示出第一极耳30的第二段30b与转接区55有连接关系，然而可以理解，图14中第一连接区51实际上位于转接区55后方，因此第一极耳30的第二段30b实际连接于位于转接区55后方的第一连接区51上。
其中，本申请的二次电池100或二次电池200可以为锂二次电池，包括锂金属二次电池、锂离子二次电池、锂聚合物二次电池和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用电装置1，包括电池仓101和容置于电池仓101内的二次电池100(或二次电池200)。用电装置1通过上述二次电池100供电，且二次电池100的安全性和可靠性得到改善。在一些实施例中，本申请的用电装置1可以是，但不限于笔记本电脑、笔输入型计算机、移动电脑、用电书播放器、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CD机、迷你光盘、收发机、用电记事本、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。
以下通过具体实施例和对比例对本申请提供的二次电池的性能进行说明。其中，以二次电池为锂离子软包电池、第一极片为正极极片、第二极片为负极极片为例并结合具体制备过程和测试方法对本申请进行说明，本领域技术人员应理解，本申请中描述的制备方法仅是实施例，其他任何合适的制备方法均在本申请的范围内。
实施例1
(1)第一极片的制备：将正极活性材料钴酸锂(LiCoO2)、导电炭黑(Super P)、聚偏二氟乙烯(PVDF)按照重量比97.5:1.0:1.5进行混合，加入N-甲基吡咯烷酮(NMP)作为溶剂，调配成固含量为75wt％的浆料，并搅拌均匀。预先在厚度为12μm的集流体铝箔的预定区域上贴发泡胶，将浆料均匀涂覆在铝箔的一个表面上，加热使得发泡胶脱落以使铝箔的预定区域露出，然后90℃条件下烘干，得到涂层厚度为100μm的正极活性材料层，在铝箔的另一个表面上重复以上涂覆步骤，得到双面涂覆的第一极片。接着，在铝箔的预定区域上焊接第一极耳，第一极耳的材质为铝。
(2)第二极片的制备：将负极活性材料人造石墨、导电炭黑(Super P)、丁苯橡胶(SBR)按照重量比96:1.5:2.5进行混合，加入去离子水作为溶剂，调配成重量百分比为70wt％的浆料，并搅拌均匀。预先在10μm的集流体铜箔的预定区域上贴发泡胶，将浆料均匀涂覆在铜箔的一个表面上，加热使得发泡胶脱落以使铜箔的预定区域露出，110℃条件下烘干，得到涂层厚度为130μm的负极活性材料层。在铜箔的另一个表面上重复以上步骤，得到双面涂覆的第二极片。接着，在铜箔的预定区域上焊接第二极耳，第二极耳的材质为铜。
(3)电解液的制备：在干燥氩气气氛中，首先将有机溶剂碳酸乙烯酯(EC)、碳酸甲乙酯(EMC)和碳酸二乙酯(DEC)以质量比EC:EMC:DEC＝30:50:20混合，然后向有机溶剂中加入锂盐六氟磷酸锂(LiPF6)溶解并混合均匀，得到锂盐的浓度为1.15mol/L的电解液。
(4)隔离膜的制备：选用厚度为15μm的聚乙烯(PE)膜。
(5)二次电池的组装：将第一极片、隔离膜和第二极片依次层叠并卷绕后得到卷绕结构的电极组件，并将电极组件置于壳体内。然后，将第一极耳层叠并焊接至第一导流件，第一导流件的材质为铝箔，并在第一导流件的第二连接区上覆盖第一绝缘保护层。将第二极耳层叠并焊接至第二导流件，第二导流件的材质为铜箔。第一绝缘保护层为双层结构，第 二层采用熔点为160-170摄氏度的PP，第一导流件和第一绝缘保护层的第一层的相关参数记录于表1中，第一导流件和第二绝缘保护层分别具有与第一导流件和第一绝缘保护层类似的结构。然后，然后进行注液、化成、封装，第一绝缘保护层密封连接封边和第一导流件，得到图1至图4B中示出的二次电池。
实施例2-13和对比例1-6
与上述实施例1不同之处在于第一导流件和第一绝缘保护层的相关参数。
对比例7
与上述实施例1不同之处在于省略第一绝缘保护层。
对各实施例和对比例的二次电池各取100个分别进行外部短路测试、常温跌落测试、高温跌落测试和直流电阻增长率测试，对应的测试结果记录于表1中。
第一聚合物的熔点测试步骤包括：1)将二次电池放电至3V后拆解，取出覆盖于第一极耳表面的第一绝缘保护层，清洗，在80℃烘干后，得到样品；2)将样品置于铝坩埚内，样品重量为1mg，采用差示扫描量热仪(仪器型号：DSC214，厂商：德国耐驰)测试样品的DSC曲线，测试温度范围为60℃至200℃，升温速率为10℃/min，分析该DSC曲线得到熔点。
二次电池的外部短路测试步骤包括：1)在25±5℃的环境条件下，将二次电池充电至100％ SOC(State of Charge，荷电状态)；2)将二次电池置于25±5℃的测试环境下,使用10±2mΩ的负载电阻与二次电池的第一导流件和第二导流件分别短接,若二次电池未发生起火和爆炸，测试直到电压低于0.2V，测试过程中监测二次电池的温度变化，当出现电池温度下降至环境温度的±5℃时或短接时间达到24小时测试终止；3)拆解二次电池，观察第一导流件的第二连接区是否断裂，然后计算各个样品中第一导流件的断裂率(即发生断裂的样品在所有样品中所占的比例)。
二次电池的常温跌落测试步骤包括：1)在25±5℃的环境条件下，将二次电池充电至100％ SOC；2)将二次电池放入夹具仓，用自动跌落设备将二次电池的底面、侧面、顶面为一轮依次从1.8m位置跌落至钢板上，共计跌落6轮即18次；3)跌落完毕后拆解二次电池，观察第一导流件的第二连接区是否断裂，然后计算各个样品中第一导流件的断裂率。
二次电池的高温跌落测试步骤包括：1)测试前后检查二次电池的外观并拍照；2)将感温线贴于二次电池表面中心处，然后将二次电池竖直地置于热箱体中，以5±2℃的升温速度升温至130±2℃并保持10分钟；3)在25±5℃的环境条件下，将二次电池充电至100％ SOC；4)将电池放入夹具仓，用自动跌落设备将电池的底面、侧面、顶面为一轮依次从1.8m位置跌落至钢板上，共计跌落6轮即18次；5)跌落完毕后拆解二次电池，观察第一导流件的第二连接区是否断裂，然后计算各个样品中第一导流件的断裂率。
二次电池的直流电阻(DCR)增长率测试步骤包括：1)在25±5℃的环境条件下，将二次电池以0.7C恒流充电至4.48V，再恒压充电至电流为0.05C，然后用0.1C恒流放电10s，测试放电前的电压V0，然后用1C恒流放电1s，测试放电后的电压V1，则电池的初始DCR＝(V1-V0)/1C；2)按照上述相同的充放电步骤进行30次充放电循环，然后测试循环后 的DCR；3)计算循环后的DCR增长率＝(循环后DCR-初始DCR)/初始DCR×100％。
表1
从表1测试结果可知，相较于对比例1，实施例4、9-14满足0.1S2≤S1，可减小二次电池正常工作时第二连接区熔断以及常温跌落下断裂的风险，因此正常循环过程中第二连接区未断裂，二次电池的DCR增长率较低，二次电池可正常工作。相较于对比例2，实施例4、9-14满足S1≤0.5S2，二次电池发生短路时第二连接区可及时熔断，因此短路后第一导流件的断裂率提高，二次电池的安全性提高。相较于对比例3，实施例1-8中第一聚合物的熔点不小于100摄氏度，因此在二次电池并未存在安全风险的情况下第一聚合物不会熔融并持续对第二连接区提供保护作用，因此在常温跌落测试下第一导流件未断裂，二次电池可持续工作。相较于对比例4，实施例1-8中第一聚合物的熔点不超过170摄氏度，因此在二次电池存在安全隐患的情况下第一聚合物熔融，因此在高温跌落测试下第一导流件的断裂率提高，阻止存在安全隐患的二次电池继续工作，二次电池的安全性提高。对比例5-6中S1以及第一聚合物熔点均不满足要求，对比例7省略第一绝缘保护层，因此二次 电池的多项性能测试结果较差。
比较实施例1-8可知，当第一聚合物的熔点在预定范围内逐渐降低时，第一聚合物对二次电池内部温度的灵敏度提高，高温跌落测试后第一导流件的断裂率也逐渐提高。
比较实施例4、实施例9-14可知，当第二连接区的最小截面积S1在预定范围内逐渐增大时，第二连接区在短路电流和高温下的灵敏度相应降低，二次电池的安全性相应减低，但同时二次电池的DCR增长率也降低，利于二次电池的正常循环。因此当实施例4、10-11满足0.2S2≤S1≤0.4S2时，第二连接区在短路电流和高温下的灵敏度较高，同时二次电池具有较低的DCR增长率，使得二次电池可兼顾较高的安全性和循环能力。
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 (17)

  1. 一种二次电池，包括壳体、设于所述壳体内的电极组件、以及第一极耳，所述电极组件包括第一极片，所述第一极耳连接于所述第一极片，其中，所述二次电池还包括：
    第一导流件，至少部分所述第一导流件设于所述壳体内，所述第一导流件包括第一连接区、至少一第二连接区、以及第三连接区，所述第二连接区连接于所述第一连接区和所述第三连接区之间，所述第一连接区连接于所述第一极耳，所述第三连接区连接于所述壳体，所述第二连接区沿所述第二连接区的厚度方向的最小截面积为S1，所述第三连接区沿所述第三连接区的厚度方向的截面积为S2，至少一所述第二连接区满足：0.1S2≤S1≤0.5S2；
    第一绝缘保护层，至少覆盖所述第二连接区的表面，所述第一绝缘保护层包括第一聚合物，所述第一聚合物的熔点为100摄氏度至170摄氏度。
  2. 如权利要求1所述的二次电池，其中，所述电极组件还包括隔离膜，所述第一聚合物的熔点小于或等于所述隔离膜的熔点。
  3. 如权利要求1或2所述的二次电池，其中，所述第一聚合物的材质选自聚丙烯、聚乙烯、聚对苯二甲酸乙二醇酯、聚萘二甲酸乙二醇酯、聚丙烯改性材料或聚乙烯改性材料中的至少一种。
  4. 如权利要求1至3中任一项所述的二次电池，其中，所述第一绝缘保护层还覆盖部分所述第一连接区的表面和部分所述第三连接区的表面。
  5. 如权利要求1至4中任一项所述的二次电池，其中，至少一所述第二连接区满足：0.2S2≤S1≤0.4S2。
  6. 如权利要求1至5中任一项所述的二次电池，其中，沿所述第二连接区的厚度方向观察，所述第二连接区包括相对设置的第一边和第二边，所述第一边和所述第二边均连接于所述第一连接区和所述第三连接区之间，所述第一边为弯曲形状，所述第一边包括连接于所述第一连接区的第一端点、连接于所述第三连接区的第二端点、以及设于所述第一端点和所述第二端点之间的顶部，所述顶部相较于所述第一端点以及所述第二端点朝向所述第二连接区的内部凹进。
  7. 如权利要求6所述的二次电池，其中，所述第一边至少部分为折线形。
  8. 如权利要求1至7中任一项所述的二次电池，其中，所述第二连接区的厚度小于所述第一连接区和所述第三连接区中任一者的厚度。
  9. 如权利要求1至8中任一项所述的二次电池，其中，所述第一连接区、所述第二连接区以及所述第三连接区为一体式结构。
  10. 如权利要求1至9中任一项所述的二次电池，其中，所述壳体为包装袋，其包括相连接的容纳部和封边，所述电极组件容纳于所述容纳部内，至少部分所述第二连接区位于所述封边内、所述容纳部内或所述壳体外，至少部分所述第三连接区伸出所述壳体，所述第一绝缘保护层包括层叠设置的第一层和第二层，所述第一层包括所述第一聚合物，所述第二层包括第二聚合物，所述第二聚合物的熔点为160度至170度，所述第二层与所述 封边和所述第一层分别连接。
  11. 如权利要求10所述的二次电池，其中，所述第一连接区、所述第二连接区以及所述第三连接区共面。
  12. 如权利要求10所述的二次电池，其中，所述第一连接区包括连接于所述第二连接区的第一分区和连接于所述第一分区的第二分区，所述第二连接区、所述第三连接区以及所述第一分区共面，所述第二分区相较于所述第一分区弯折，所述第二分区连接于所述第一极耳。
  13. 如权利要求1至9中任一项所述的二次电池，其中，所述壳体为金属壳体，其包括相对设置的第一端壁和第二端壁、连接于所述第一端壁和所述第二端壁之间的侧壁、以及设于所述第一端壁的第一极柱，所述第一极柱与所述第一端壁电性隔绝，所述第三连接区连接于所述第一极柱。
  14. 如权利要求13所述的二次电池，其中，所述电极组件为卷绕结构，所述第一极片包括第一集流体，所述第一集流体包括朝向所述第一端壁的第一端边，所述第一极耳由所述第一端边延伸形成，所述第一极耳包括连接所述第一端边的第一极耳区和连接所述第一极耳区的第二极耳区，所述第二极耳区相较于所述第一极耳区弯折并形成第一端面，所述第一连接区连接于所述第一端面；沿所述第一连接区的厚度方向观察，所述第一连接区和所述第三连接区存在重叠。
  15. 如权利要求14所述的二次电池，其中，所述第三连接区包括连接于所述第二连接区的第三分区和连接于所述第三分区的第四分区，所述第一连接区、所述第二连接区以及所述第三分区共面，所述第四分区相较于所述第三分区弯折；沿所述第一连接区的厚度方向观察，所述第一连接区和所述第四分区存在重叠。
  16. 如权利要求11所述的二次电池，其中，所述第一导流件还包括弯折区和转接区，所述转接区包括相邻设置的第三边和第四边，所述第二连接区连接于所述第三边，所述弯折区连接于所述第四边和所述第三连接区之间，所述弯折区相对所述转接区和所述第三连接区均弯折，从所述第三连接区的厚度方向观察，所述转接区和所述第三连接区存在重叠。
  17. 一种用电装置，包括电池仓，其中，所述用电装置还包括如权利要求1至16中任一项所述的二次电池，所述二次电池容置于所述电池仓中。
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Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101373822A (zh) * 2008-08-15 2009-02-25 广州丰江电池新技术有限公司 安全性的软包装锂电池导流体
JP2014013711A (ja) * 2012-07-05 2014-01-23 Auto Network Gijutsu Kenkyusho:Kk ヒューズ内蔵導電部品
CN106450475A (zh) * 2016-11-15 2017-02-22 宁德时代新能源科技股份有限公司 二次电池及电池模组
WO2018055677A1 (ja) * 2016-09-20 2018-03-29 株式会社東芝 組電池および導電部材
CN208062180U (zh) * 2018-04-09 2018-11-06 宁德时代新能源科技股份有限公司 二次电池
CN115843399A (zh) * 2021-12-29 2023-03-24 东莞新能源科技有限公司 电化学装置和电子装置
WO2023122881A1 (zh) * 2021-12-27 2023-07-06 东莞新能源科技有限公司 电池及包含其的电子装置
CN116544345A (zh) * 2023-06-28 2023-08-04 宁德新能源科技有限公司 二次电池及电子装置
WO2023184369A1 (zh) * 2022-03-31 2023-10-05 宁德新能源科技有限公司 电化学装置、模组以及电子装置

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101373822A (zh) * 2008-08-15 2009-02-25 广州丰江电池新技术有限公司 安全性的软包装锂电池导流体
JP2014013711A (ja) * 2012-07-05 2014-01-23 Auto Network Gijutsu Kenkyusho:Kk ヒューズ内蔵導電部品
WO2018055677A1 (ja) * 2016-09-20 2018-03-29 株式会社東芝 組電池および導電部材
CN106450475A (zh) * 2016-11-15 2017-02-22 宁德时代新能源科技股份有限公司 二次电池及电池模组
CN208062180U (zh) * 2018-04-09 2018-11-06 宁德时代新能源科技股份有限公司 二次电池
WO2023122881A1 (zh) * 2021-12-27 2023-07-06 东莞新能源科技有限公司 电池及包含其的电子装置
CN115843399A (zh) * 2021-12-29 2023-03-24 东莞新能源科技有限公司 电化学装置和电子装置
WO2023184369A1 (zh) * 2022-03-31 2023-10-05 宁德新能源科技有限公司 电化学装置、模组以及电子装置
CN116544345A (zh) * 2023-06-28 2023-08-04 宁德新能源科技有限公司 二次电池及电子装置

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