WO2023283808A1 - 电池单体、电池及用电装置 - Google Patents

电池单体、电池及用电装置 Download PDF

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Publication number
WO2023283808A1
WO2023283808A1 PCT/CN2021/106111 CN2021106111W WO2023283808A1 WO 2023283808 A1 WO2023283808 A1 WO 2023283808A1 CN 2021106111 W CN2021106111 W CN 2021106111W WO 2023283808 A1 WO2023283808 A1 WO 2023283808A1
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WO
WIPO (PCT)
Prior art keywords
liquid bag
battery cell
battery
liquid
electrolyte
Prior art date
Application number
PCT/CN2021/106111
Other languages
English (en)
French (fr)
Inventor
徐晓富
叶永煌
刘倩
何建福
孙雪阳
孙婧轩
金海族
Original Assignee
宁德时代新能源科技股份有限公司
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.)
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Application filed by 宁德时代新能源科技股份有限公司 filed Critical 宁德时代新能源科技股份有限公司
Priority to PCT/CN2021/106111 priority Critical patent/WO2023283808A1/zh
Priority to JP2022550830A priority patent/JP2023539705A/ja
Priority to CN202180072910.9A priority patent/CN116420261A/zh
Priority to EP21923588.4A priority patent/EP4145619A4/en
Priority to KR1020227028980A priority patent/KR20230012456A/ko
Priority to US17/980,591 priority patent/US20230046770A1/en
Publication of WO2023283808A1 publication Critical patent/WO2023283808A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/60—Arrangements or processes for filling or topping-up with liquids; Arrangements or processes for draining liquids from casings
    • H01M50/673—Containers for storing liquids; Delivery conduits therefor
    • H01M50/682—Containers for storing liquids; Delivery conduits therefor accommodated in battery or cell casings
    • 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
    • H01M50/60—Arrangements or processes for filling or topping-up with liquids; Arrangements or processes for draining liquids from casings
    • H01M50/609—Arrangements or processes for filling with liquid, e.g. electrolytes
    • 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
    • H01M50/60—Arrangements or processes for filling or topping-up with liquids; Arrangements or processes for draining liquids from casings
    • H01M50/609—Arrangements or processes for filling with liquid, e.g. electrolytes
    • H01M50/627—Filling ports
    • H01M50/636—Closing or sealing filling ports, e.g. using lids
    • H01M50/664—Temporary seals, e.g. for storage of instant batteries or seawater batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings; Jackets or wrappings
    • H01M50/102—Primary casings; Jackets or wrappings characterised by their shape or physical structure
    • 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
    • H01M50/14—Primary casings; Jackets or wrappings for protecting against damage caused by external factors
    • H01M50/145—Primary casings; Jackets or wrappings for protecting against damage caused by external factors for protecting against corrosion
    • 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
    • H01M50/20—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders
    • H01M50/202—Casings or frames around the primary casing of a single cell or a single battery
    • 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
    • H01M50/20—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders
    • H01M50/204—Racks, modules or packs for multiple batteries or multiple cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/60—Arrangements or processes for filling or topping-up with liquids; Arrangements or processes for draining liquids from casings
    • H01M50/673—Containers for storing liquids; Delivery conduits therefor
    • 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
    • H01M2220/00—Batteries for particular applications
    • H01M2220/20—Batteries in motive systems, e.g. vehicle, ship, plane
    • 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
    • H01M50/543—Terminals
    • 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

Definitions

  • the present application relates to the field of batteries, in particular to a battery cell, a battery and an electrical device.
  • the present application provides a battery cell, a battery, and an electrical device, which can alleviate battery performance deterioration caused by lithium depletion or local electrolyte depletion during battery use.
  • the present application provides a battery cell, comprising: a casing filled with electrolyte; at least one cell assembly arranged in the casing; The side wall of the core assembly is correspondingly provided with at least one closed liquid bag, and electrolyte is contained in the liquid bag; at least one weak structure is provided on the liquid bag, and when the pressure in the liquid bag reaches a threshold value, The electrolyte in the liquid bag breaks through the weak structure and flows out of the liquid bag.
  • a liquid bag is arranged in the casing of the battery cell, and the liquid bag is arranged at least correspondingly to the side wall of the battery cell assembly.
  • Such a design enables the liquid bag to occupy the free space in the battery case at the initial stage of battery use, which overcomes the problem of wrinkling of the battery cell in the battery with low group margin design, thereby avoiding the problem of lithium deposition in the electrode; as the battery charge-discharge cycle progresses
  • the side wall of the cell will squeeze the liquid bag, causing the liquid bag to deform and fill the empty area in the battery case to relieve the expansion pressure of the cell; as the expansion force of the cell further increases, the cell will The side wall of the component further squeezes the liquid bag so that when the pressure in the liquid bag reaches the threshold value, the electrolyte in the liquid bag will break through the weak structure provided on the liquid bag and flow out of the liquid bag, realizing automatic replenishment of the electrolyte in the casing.
  • the side wall includes an intermediate side wall portion located in the middle region between the two ends of the battery core assembly, and the liquid bag is disposed corresponding to the intermediate side wall portion.
  • the liquid bag is arranged between the cell assembly and the side wall of the housing, and/or the liquid bag is arranged between adjacent cell assemblies.
  • the arrangement of the liquid bladder in the casing is flexible, as long as one side of the liquid bladder is in contact with the side wall of the battery cell assembly.
  • At least one of said weakened structures is provided at least part of an edge of said bladder.
  • a plurality of the weakened structures are arranged at least part of the edge of the liquid bag at intervals.
  • the battery cell includes an upper end in a state of use, and at least one of the weakened structures is located on the liquid bladder near the upper end.
  • the top of the battery is more likely to have insufficient electrolyte or even dry up.
  • Such a design can conveniently replenish the electrolyte from the top of the battery cell to avoid partial depletion of the electrolyte.
  • the liquid bag includes at least one first liquid bag and at least one second liquid bag, the first liquid bag contains electrolyte, and the second liquid bag does not hold electrolyte, so The first liquid bag and the second liquid bag are isolated from each other in an initial state.
  • the second liquid bag acts as a buffer space, which increases the space for adjusting the expansion pressure of the liquid bag to the cell assembly.
  • the fluid bladder includes a first weak structure disposed between the first fluid bladder and the second fluid bladder to isolate them from each other, when the pressure in the first fluid bladder When the first threshold is reached, the electrolyte in the first liquid bag breaks through the first weak structure and flows into the second liquid bag.
  • the electrolytic solution flows into the second liquid bag after breaking through the first weak structure, thereby providing a stepwise expansion pressure adjustment capability.
  • the second liquid bag is further provided with a second weak structure, and when the pressure in the second liquid bag reaches the second threshold, the electrolysis in the second liquid bag The liquid breaks through the second weak structure and flows out of the second liquid bag.
  • a second weak structure on the second liquid bag, when the first liquid bag is squeezed, the electrolyte inside the second liquid bag first enters the second liquid bag, and when further squeezed, the electrolyte breaks through the second weak structure and passes through the second liquid bag.
  • the liquid capsule flows out to automatically replenish the electrolyte in the shell.
  • At least one of the second liquid bladders is located at two end regions of the cell assembly. In this way, the height space between the end cap and the cell assembly at the end of the cell assembly can be effectively utilized, and such a design is advantageous in the case of increasing requirements on battery energy density.
  • the second liquid bag is located in an area of the upper end of the battery core assembly where no lug is provided.
  • the end of the cell assembly is usually provided with tabs, but the tabs do not occupy the entire height space between the end cover and the cell assembly, so that the second liquid bag is located in the area above the cell assembly without tabs, which can Make further use of this part of the space.
  • the fluid capsule further includes at least one buffer capsule and a third weak structure disposed between the first fluid capsule and the second fluid capsule, and the first weak structure isolates the first fluid capsule.
  • a fluid bladder and the buffer bladder the third weak structure isolates the buffer bladder from the second fluid bladder, and when the pressure in the buffer bladder reaches a third threshold, the The electrolyte solution breaks through the third weak structure and flows into the second liquid bag.
  • At least one of the buffer capsules is at least one channel arranged at intervals, each of the channels is provided with the first weak structure at one end, and the other end of each of the channels is provided with the third weak structure. Setting the buffer capsule as at least one channel at intervals can prevent the battery performance from deteriorating due to large changes in the interface contact position when the weak structure is broken by the electrolyte.
  • the volumes of the channels are the same or different.
  • the position, stress, and temperature environment factors of each cell assembly in the casing affect the usage and expansion pressure of the cell assembly.
  • the volume of each channel is the same or different, so that the buffer space provided by each channel can be the same Or different, so as to provide fine inflation pressure adjustment capability for the liquid bladder.
  • the first thresholds of each of the first weak structures are the same or different; in some embodiments, when the liquid bladder When multiple second weak structures are included, the second thresholds of each of the second weak structures are the same or different; in some embodiments, when the fluid bladder includes multiple third weak structures, The third thresholds of the respective third weak structures are the same or different.
  • the liquid bladder can simultaneously and uniformly release the buffer space at the position of each weak structure when it is squeezed, and The electrolyte is evenly released to the position of each weak structure in the casing, which is beneficial for the quick release of the buffer space and the quick replenishment of the electrolyte.
  • the liquid sac can be squeezed with the squeezed condition.
  • the buffer space is gradually released to a certain extent, and the electrolyte is gradually released into the casing, so as to avoid the deterioration of battery performance caused by excessive changes, and ensure that the performance of the battery cell components tends to a consistent level under different positions and temperature conditions.
  • the first weakened structure includes at least one thinned region and/or at least one interlayer portion provided on the first liquid bladder; in some embodiments, the second weakened structure includes At least one thinned region and/or at least one sandwich portion on the second liquid bladder; in some embodiments, the third weakened structure includes at least one thinned region on the second liquid bladder and/or at least one sandwich section.
  • the implementation of each weak structure is flexible, and it can be a thinned area on the liquid capsule, which is easy to manufacture; it can also be an interlayer of different materials arranged on the liquid capsule, as long as it can form a force-bearing weak structure.
  • the first threshold, the second threshold, and the third threshold are each independently between 0.1 MPa and 2.0 MPa. Set the pressure threshold of the weak structure within this range, so that when the pressure in the liquid bag reaches this threshold, the electrolyte will break through the weak structure and enter the buffer space or flow out of the liquid bag, relieving the expansion pressure of the cell assembly, thereby avoiding the battery Detrimental effects of excessive swelling of components on battery performance.
  • the present application provides a battery, which includes the battery cell in the above embodiment.
  • the present application provides an electric device, which includes the battery in the above embodiment, and the battery is used to provide electric energy.
  • FIG. 1 is a schematic structural view of a vehicle in some embodiments of the present application.
  • Fig. 2 is a schematic diagram of an exploded structure of a battery in some embodiments of the present application.
  • FIG. 3 is a schematic diagram of an exploded structure of a battery cell in some embodiments of the present application.
  • FIG. 4 is a schematic cross-sectional structure diagram of a battery cell along the Y direction in some embodiments of the present application.
  • FIG. 5 is a schematic cross-sectional structure diagram of a battery cell along the X direction in some embodiments of the present application.
  • FIG. 6 is a schematic cross-sectional structure diagram of a battery cell along the X direction in some embodiments of the present application, showing the state of the liquid bag when it is squeezed;
  • FIG. 7 is a schematic cross-sectional structure diagram of a battery cell along the X direction in some embodiments of the present application, showing the state when the liquid bag is squeezed and the electrolyte breaks through the weak structure and flows out of the liquid bag;
  • Fig. 8 is a schematic structural diagram of a liquid bag in a battery cell according to some embodiments of the present application.
  • Fig. 9 is a schematic structural view of the liquid bag in the battery cell according to some embodiments of the present application.
  • FIG. 10 is a schematic cross-sectional structure diagram of a battery cell along the X direction in some embodiments of the present application.
  • FIG. 11 is a schematic cross-sectional structure diagram of a battery cell along the X direction in some embodiments of the present application.
  • Fig. 12 is a schematic structural diagram of a liquid bag in a battery cell according to some embodiments of the present application.
  • Fig. 13 is a schematic structural diagram of a liquid bag in a battery cell according to some embodiments of the present application.
  • Fig. 14 is a schematic structural diagram of a liquid bag in a battery cell according to some embodiments of the present application.
  • Fig. 15 is a schematic diagram of the sandwich material structure of some embodiments of the present application.
  • multiple refers to more than two (including two), similarly, “multiple groups” refers to more than two groups (including two), and “multiple pieces” refers to More than two pieces (including two pieces).
  • Power batteries are not only used in energy storage power systems such as hydraulic, thermal, wind and solar power plants, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, electric vehicles, as well as military equipment and aerospace and other fields . With the continuous expansion of power battery application fields, its market demand is also constantly expanding.
  • the expansion of the pole piece has an adverse effect on the performance and service life of the battery.
  • the force extrusion may cause the porosity of the pole piece to decrease, affect the infiltration of the electrolyte on the pole piece, cause the change of the ion transmission path, and bring about the problem of lithium analysis;
  • the sheet When the sheet is subjected to a large extrusion force for a long time, it may also break and cause the risk of short circuit in the battery and so on.
  • the electrolyte of the battery will be continuously consumed during the charge-discharge cycle. After the battery cell has been used for a certain period of time, the electrolyte may even be partially depleted, and the swelling of the cell will further aggravate the local electrolyte shortage.
  • an expansion space can be reserved for the battery core in design.
  • it is to reduce the group margin of the cells in the battery casing, that is, to reduce the percentage of the thickness of the cells in the battery to the thickness of the inner cavity of the casing.
  • the cell group margin in the thickness direction is usually below 88.5%
  • the full charge group margin is usually below 97%.
  • the problem of cell wrinkling may occur due to the large gap in the casing.
  • the wrinkling of the anode sheet will cause changes in the path of lithium ions at the anode interface, which will bring the risk of lithium precipitation and affect the performance and life of the battery.
  • the inventor designed a battery cell after in-depth research. , by arranging at least one closed liquid bag in the casing of the battery cell, and setting the liquid bag at least corresponding to the side wall of the cell assembly, containing the electrolyte in the liquid bag, and setting a weak structure on the liquid bag, so that When the pressure in the liquid capsule reaches a threshold value, the electrolyte can break through the weak structure and flow out of the liquid capsule.
  • the liquid bag since the liquid bag is arranged correspondingly to the side wall of the battery cell assembly, the liquid bag can occupy the empty space in the casing in the thickness direction of the battery cell assembly at the initial stage of use of the battery cell, which is equivalent to improving The equivalent group margin of the battery cell is improved, which can effectively avoid the problem of wrinkling of the pole piece of the battery cell component in the battery with a low group margin design.
  • the liquid bag corresponding to the side wall of the battery cell assembly will be squeezed and deformed.
  • the cell components at different positions in the battery cell are affected by factors such as force differences and temperature environment differences, and the expansion force of the cell components is also different.
  • the liquid bladder can be expanded to varying degrees according to the actual expansion pressure of each cell component. Extrusion deformation, so as to realize the self-adaptive adjustment of the expansion pressure of the cell assembly.
  • the battery cell of the present application can make full use of the inner space of the casing as the expansion force buffer space of the battery cell assembly.
  • the middle position of the cell assembly is more severely bulged than the two ends, and the expansion force is also greater.
  • the inside of the liquid bag is squeezed and deformed, the part corresponding to the middle position of the side wall of the cell assembly becomes thinner, and the electrolyte is squeezed into the buffer space at both ends, which can relieve the expansion force of the middle part of the cell assembly and prevent battery performance. further deterioration and the risk of lithium analysis.
  • the liquid bag is further squeezed, and when the pressure in the liquid bag is squeezed to a threshold value, the electrolyte will break through the weak structure on the liquid bag and flow out of the liquid bag , into the casing and replenish the loss of electrolyte in the battery cell casing to achieve the effect of automatic liquid replenishment.
  • the electrolyte solution in the liquid bag may be the same as the initial electrolyte solution in the shell, or may be a different electrolyte solution.
  • the electrolyte in the liquid bag can be a special electrolyte for the used cell assembly, or other functional electrolytes.
  • the battery cells disclosed in the embodiments of the present application can be used, but not limited to, in electric devices such as vehicles, ships or aircrafts.
  • the power supply system comprising the battery unit and battery disclosed in this application can be used to form the electrical device, which is conducive to alleviating and automatically adjusting the deterioration of the expansion force of the battery cell, supplementing the consumption of the electrolyte, and improving the stability of battery performance and battery life. .
  • the embodiment of the present application provides an electric device using a battery as a power source.
  • the electric device can be, but not limited to, a mobile phone, a tablet, a notebook computer, an electric toy, an electric tool, a battery car, an electric car, a ship, a spacecraft, and the like.
  • electric toys may include fixed or mobile electric toys, such as game consoles, electric car toys, electric boat toys, electric airplane toys, etc.
  • spacecraft may include airplanes, rockets, space shuttles, spaceships, etc.
  • a vehicle 1000 as an electric device according to an embodiment of the present application is taken as an example for description.
  • FIG. 1 is a schematic structural diagram of a vehicle 1000 provided by some embodiments of the present application.
  • the vehicle 1000 can be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle.
  • the interior of the vehicle 1000 is provided with a battery 100 , and the battery 100 may be provided at the bottom, head or tail of the vehicle 1000 .
  • the battery 100 can be used for power supply of the vehicle 1000 , for example, the battery 100 can be used as an operating power source of the vehicle 1000 .
  • the vehicle 1000 may further include a controller 200 and a motor 300 , the controller 200 is used to control the battery 100 to supply power to the motor 300 , for example, for starting, navigating and running the vehicle 1000 .
  • the battery 100 can not only be used as an operating power source for the vehicle 1000 , but can also be used as a driving power source for the vehicle 1000 , replacing or partially replacing fuel oil or natural gas to provide driving power for the vehicle 1000 .
  • FIG. 2 is an exploded view of a battery 100 provided by some embodiments of the present application.
  • the battery 100 includes a case 10 and battery cells 20 housed in the case 10 .
  • the box body 10 is used to provide accommodating space for the battery cells 20 , and the box body 10 may adopt various structures.
  • the box body 10 may include a first part 11 and a second part 12, the first part 11 and the second part 12 cover each other, the first part 11 and the second part 12 jointly define a of accommodation space.
  • the second part 12 can be a hollow structure with one end open, the first part 11 can be a plate-like structure, and the first part 11 covers the opening side of the second part 12, so that the first part 11 and the second part 12 jointly define an accommodation space ;
  • the first part 11 and the second part 12 can also be hollow structures with one side opening, and the opening side of the first part 11 is covered by the opening side of the second part 12 .
  • the box body 10 formed by the first part 11 and the second part 12 can be in various shapes, such as a cylinder, a cuboid and the like.
  • the battery 100 there may be multiple battery cells 20 , and the multiple battery cells 20 may be connected in series, in parallel or in parallel.
  • the mixed connection means that the multiple battery cells 20 are connected in series and in parallel.
  • a plurality of battery cells 20 can be directly connected in series, in parallel or mixed together, and then the whole composed of a plurality of battery cells 20 is housed in the box 10; of course, the battery 100 can also be a plurality of battery cells 20
  • the battery modules are firstly connected in series or parallel or in combination, and then multiple battery modules are connected in series or in parallel or in combination to form a whole, which is accommodated in the case 10 .
  • the battery 100 may also include other structures, for example, the battery 100 may also include a bus component for realizing electrical connection between multiple battery cells 20 .
  • each battery cell 20 may be a lithium-ion secondary battery, a lithium-ion primary battery, a lithium-sulfur battery, a sodium-lithium-ion battery or a magnesium-ion battery, but is not limited thereto.
  • the battery cell 20 may be in the form of a cylinder, a flat body, a cuboid or other shapes.
  • FIG. 3 is a schematic diagram of an exploded structure of a battery cell 20 provided in some embodiments of the present application.
  • the battery cell 20 refers to the smallest unit constituting a battery.
  • the battery cell 20 includes an end cover 21 , a casing 22 , a cell assembly 23 , a liquid bag 24 and other functional components.
  • the end cap 21 refers to a component that covers the opening of the casing 22 to isolate the internal environment of the battery cell 20 from the external environment.
  • the shape of the end cap 21 can be adapted to the shape of the housing 22 to fit the housing 22 .
  • the end cap 21 can be made of a material (such as aluminum alloy) with a certain hardness and strength, so that the end cap 21 is not easy to deform when being squeezed and collided, so that the battery cell 20 can have a higher Structural strength and safety performance can also be improved.
  • Functional components such as electrode terminals 21 a may be provided on the end cap 21 .
  • the electrode terminal 21 a can be used for electrical connection with the battery cell assembly 23 for outputting or inputting electric energy of the battery cell 20 .
  • the end cover 21 may also be provided with a pressure relief mechanism for releasing the internal pressure when the internal pressure or temperature of the battery cell 20 reaches a threshold value.
  • the material of the end cap 21 can also be various, for example, copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., which is not particularly limited in this embodiment of the present application.
  • an insulator can be provided inside the end cover 21 , and the insulator can be used to isolate the electrical connection components in the housing 22 from the end cover 21 to reduce the risk of short circuit.
  • the insulating member may be plastic, rubber or the like.
  • the casing 22 is a component used to cooperate with the end cap 21 to form the internal environment of the battery cell 20 , wherein the formed internal environment can be used to accommodate the cell assembly 23 , electrolyte and other components.
  • the housing 22 and the end cover 21 can be independent components, and an opening can be provided on the housing 22 , and the internal environment of the battery cell 20 can be formed by making the end cover 21 cover the opening at the opening.
  • the end cover 21 and the housing 22 can also be integrated. Specifically, the end cover 21 and the housing 22 can form a common connection surface before other components are inserted into the housing. When the inside of the housing 22 needs to be encapsulated , then make the end cover 21 cover the housing 22.
  • the housing 22 can be in various shapes and sizes, such as cuboid, cylinder, hexagonal prism and so on. Specifically, the shape of the casing 22 can be determined according to the specific shape and size of the battery core assembly 23 .
  • the housing 22 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., which is not particularly limited in this embodiment of the present application.
  • the cell assembly 23 is a component in the battery cell 100 where the electrochemical reaction occurs.
  • One or more cell assemblies 23 may be contained in the casing 22 .
  • the cell assembly 23 is mainly formed by winding or stacking the positive electrode sheet and the negative electrode sheet, and usually a separator is provided between the positive electrode sheet and the negative electrode sheet.
  • the part of the positive electrode sheet and the negative electrode sheet with the active material constitutes the main body of the cell assembly, and the parts of the positive electrode sheet and the negative electrode sheet without the active material respectively constitute the tab 23a.
  • the positive pole tab and the negative pole tab can be located at one end of the main body together or at two ends of the main body respectively.
  • the positive electrode active material and the negative electrode active material react with the electrolyte, and the tabs 23a are connected to the electrode terminals to form a current loop.
  • the liquid bag 24 is a closed bag filled with electrolyte, which can be deformed when being squeezed.
  • the liquid bag 24 should be formed with a non-conductive packaging material with corrosion resistance and adhesiveness.
  • functional composite films or encapsulation materials comprising an outer protective layer and an inner sealing layer can be used.
  • the outer protective layer is a corrosion-resistant insulating material, which is suitable for the electrolyte environment in the battery and adapts to the environment such as temperature and pressure in the battery use state.
  • the outer protective layer can be aluminum, Teflon, acrylic, polypropylene, etc.
  • the inner sealing layer can be, for example, a thermoplastic polyester film or coating, such as polypropylene, polyvinyl chloride, polystyrene, acrylic resin, polycarbonate, polytetrafluoroethylene, polyurethane, etc., which facilitates encapsulation by a heat-sealing process.
  • a thermoplastic polyester film or coating such as polypropylene, polyvinyl chloride, polystyrene, acrylic resin, polycarbonate, polytetrafluoroethylene, polyurethane, etc.
  • an aluminum plastic film can be used to form the closed liquid bladder 24 by heat sealing.
  • the liquid bag 24 is provided with a weak structure, and the weak structure has a lower strength than other positions on the liquid bag 24, so that when the pressure in the liquid bag 24 reaches a threshold value, the electrolyte will break through the weak structure and flow from the breach of the weak structure. Flow out of the fluid sac 24 .
  • FIG. 4 is a schematic cross-sectional structure diagram of a battery cell along the Y direction according to some embodiments of the present application
  • FIGS. 5 to 7 are battery cells according to some embodiments of the present application.
  • Figure 6 and Figure 7 respectively show the state when the liquid bag is squeezed and the state when the electrolyte breaks through the weak structure and flows out of the liquid bag.
  • the Y direction in the figure is the height direction of the cell assembly 23 .
  • the tab 23 a is located at the end of the cell assembly 23 in the height direction, and is electrically connected to the electrode terminal 21 a on the end cap 21 .
  • the casing 22 is filled with electrolyte; at least one cell assembly 23 is arranged in the casing 22; the closed liquid bag 24 is arranged in the casing 22, and the liquid bag 24 is filled with electrolyte, and is at least connected to the cell assembly 23
  • the side walls of the liquid capsule 24 are provided with at least one weak structure 25 . When the pressure in the liquid bag 24 reaches a threshold value, the electrolyte in the liquid bag breaks through the weak structure 25 and flows out of the liquid bag 24 .
  • the side wall of the cell assembly 23 refers to the outer wall of the cell assembly 23 in a direction parallel to the height direction (Y direction in FIG. 3 ).
  • the expansion force of the cell assembly 23 is usually along the direction perpendicular to the height direction, so the bulging direction of the cell assembly 23 mainly occurs on the sidewall of the large surface (ie, the thickness direction, the Z direction in FIG. 3 ) and the corners (ie, the width direction). both ends of the X direction in Fig. 3).
  • Making “the liquid bag 24 is arranged at least corresponding to the side wall of the cell assembly 23 ” means that the liquid bag 24 is arranged in the housing 22 and at least part of the liquid bag 24 abuts against the side wall of the cell assembly 23 .
  • the liquid bag 24 can occupy the space between the side wall of the cell assembly 23 and the side wall of the casing 22 when the battery cell 100 is initially used.
  • the vacant space can support the cell assembly 23, and can effectively avoid the wrinkling of the cell assembly 23. This is especially beneficial for cells designed with low group margin.
  • the internal pressure of the liquid bag 24 increases, which produces certain resistance and relief to the expansion force of the side wall of the battery cell assembly 23 . In this way, the further deterioration of the expansion force of the cell assembly 23 and the risk of lithium deposition caused by extrusion of the pole pieces can be avoided.
  • the expansion force further increases, and the degree of extrusion to the liquid bag 24 also further increases.
  • the weak structure 25 is broken, and the electrolyte in the liquid bag 24 flows out of the liquid bag 24 from the breach at the position of the weak structure 25, as shown by the curved arrow at the top in FIG. 7 .
  • at least one weak structure 25 is provided on the liquid bag 24, so that when the expansion force of the cell assembly 23 reaches a certain level, the electrolyte in the liquid bag 24 can automatically replenish the electrolyte in the casing 22. Electrolyte loss.
  • the capsule 24 is disposed corresponding to the middle side wall portion of the cell assembly 23 .
  • the middle side wall part of the battery cell assembly 23 is often the part with the most severe swelling and the largest expansion force during the use of the battery cell, so that at least part of the liquid bag 24 is arranged corresponding to the middle side wall part, which can relieve the pressure of this part of the battery cell assembly 23.
  • the expansion force can prevent the pole piece in the middle area of the battery cell assembly 23 from being greatly squeezed, thereby avoiding the problem of lithium precipitation and the deterioration of battery performance.
  • the liquid bag 24 may be disposed between the cell assembly 23 and the side wall of the casing 22 ; or the liquid bag 24 may also be disposed between adjacent cell assemblies 23 . As long as at least one side of the liquid bag 24 is in contact with the side wall of the cell assembly 23 so that the liquid bag 24 can be squeezed when the cell assembly 23 swells due to use, the purpose of the present application can be achieved.
  • At least a part of the liquid bag 24 may be disposed between the side wall of the cell assembly 23 and the side wall of the housing 22; in an embodiment in which two or more cell assemblies 23 are arranged in the housing 22, At least a part of the liquid bag 24 can be arranged between the side walls of the adjacent cell assemblies 23, or between the side walls of the cell assemblies 23 and the side walls of the casing 22; the cell assemblies 23 are cylinders In a shape embodiment, at least a part of the liquid bag 24 may surround the side wall of the cylindrical cell assembly 23 in a ring shape, and be disposed between the side wall of the cell assembly 23 and the side wall of the housing 22 . There may also be one or more fluid capsules 24.
  • At least one fluid capsule 24 may also be arranged on the side wall of the cell assembly 23 and the side wall of the casing 22. Between the side walls, or at least one liquid bag 24 is disposed between the side walls of adjacent cell assemblies 23 .
  • the form in which the liquid bag 24 is disposed in the housing may specifically be sandwiched between the side walls of the cell assembly 23 and/or the side walls of the housing 11 .
  • FIG. 8 is a schematic structural diagram of the fluid bag 24 in the battery cell 100 according to some embodiments of the present application. As shown in the figures, at least one weakened structure 25 is provided at least part of the edge of the bladder 24 .
  • the edge of the liquid bag 24 refers to the part of the liquid bag 24 that is not in contact with the side wall of the cell assembly 23 or the side wall of the casing 22 .
  • the edge of the liquid bag 24 may include the liquid bag 24 along the cell assembly 23. Both ends in the height direction (for example, the Y direction in FIG. 3 ), or the two sides of the liquid bag 24 along the width direction of the cell assembly 23 (for example, the X direction in FIG. 3 ).
  • the edge of the liquid bag 24 is in the gap between adjacent cell assemblies 23, or the gap between the cell assembly 23 and the casing 22, and is not in contact with the side wall of the cell assembly 23 or the casing 22. fit.
  • the weak structure 25 is arranged at least part of the edge of the liquid bag 24, so that when the liquid bag 24 is squeezed and the internal pressure reaches a threshold value, the electrolyte can break through the weak structure 25 at the edge of the liquid bag 24 and easily flow from the liquid
  • the outflow from the edge of the capsule 24 is not blocked by the side wall of the cell assembly 23 or the side wall of the casing 22, and it is more convenient to replenish the consumption of electrolyte in the casing 22 from the gap of the side wall of the cell assembly 24.
  • the battery cell 100 includes an upper end in a use state, and at least one weak structure 25 is located on the liquid bag 24 close to the upper end. Due to the effect of gravity, the upper end of the battery cell 100 in the use state is more prone to lack of electrolyte or even partial depletion.
  • the weak structure 25 is arranged on the liquid bag 24 near the upper end, so that when the electrolyte in the liquid bag 24 breaks through the weak structure 25, the liquid bag 24 flows out from the upper end of the battery cell 100, and the housing 22 The electrolyte in the battery is replenished to avoid the risk of partial depletion of the electrolyte.
  • the upper end of the battery cell 100 in use may be the end close to the end cap 21, or the other end opposite to the end cap 21. It may also be the upper end along the thickness direction of the cell assembly 23 and the like.
  • FIG. 9 is a schematic structural diagram of the liquid bag in the battery cell 100 according to some embodiments of the present application.
  • the liquid bag 24 may include at least one first liquid bag 241 and at least one second liquid bag 242, the first liquid bag 241 contains electrolyte, the second liquid bag 242 does not hold electrolyte, and the second liquid bag 242 contains electrolyte.
  • the first liquid bag 241 and the second liquid bag 242 are isolated from each other in the initial state.
  • the second liquid bag 242 Since the first liquid bag 241 contains the electrolyte, the second liquid bag 242 isolated from the first liquid bag 241 does not contain the electrolyte. Such a design makes the second liquid bag 242 barely occupy the space in the housing 22 in the initial state; after the first liquid bag 241 is squeezed by the side wall of the cell assembly 23, the electrolyte in the first liquid bag 241 enters The second liquid bag 242, therefore, the second liquid bag 242 is equivalent to the function of a buffer space. It is equivalent to setting the position of the second liquid bag 242 in the housing 22 to guide the electrolyte in the liquid bag 24 to gather at this position when being squeezed, thereby improving the protection of the space in the housing 22 of the battery cell 100 utilization rate.
  • the position of the second liquid bag 242 can be set in any empty space in the casing 22 as required, and can be set in a specific shape according to actual conditions. This is particularly advantageous in the context of the current increasing demands on the energy density of batteries.
  • FIG. 9 is a schematic structural diagram of the liquid bag 24 in the battery cell 100 according to some embodiments of the present application.
  • the liquid bag 24 includes a first weak structure 251 that can be arranged between the first liquid bag 241 and the second liquid bag 242 to isolate them from each other.
  • the pressure in the first liquid bag 241 reaches the first
  • a threshold value is reached, the electrolyte in the first liquid bag 241 breaks through the first weak structure 251 and flows into the second liquid bag 242 , so as to achieve a first-level cushioning of the expansion force of the cell assembly 23 .
  • the electrolyte can flow into the second liquid bag 242 after breaking through the first weak structure 251, so as to realize the expansion force of the cell assembly 23. secondary buffer.
  • the battery cell 100 can be provided with a stepwise expansion pressure adjustment capability.
  • a second weak structure 252 may also be provided on the second liquid bag 242.
  • the pressure in the second liquid bag 242 reaches a second threshold, the first The electrolyte in the second liquid bag 242 breaks through the second weak structure 252 and flows out of the second liquid bag 242 .
  • the second weak structure 252 By arranging the second weak structure 252 on the second liquid bag 242 , it is convenient for the electrolyte to flow out from the second weak structure 252 on the second liquid bag 242 to supplement the loss of electrolyte in the casing 22 .
  • the second weak structure 252 for the electrolyte to flow out may not be provided on the second liquid bag 242, but only the first liquid bag 241 is provided with a hole for the electrolyte to flow out of the liquid bag 24.
  • Another weak structure makes the electrolyte inside the first liquid bag 241 flow into the second liquid bag 242 first as the liquid bag 24 is squeezed, and then flows out from the weak structure on the first liquid bag 241 to the shell. body 22.
  • the second weak structure 252 is provided on the second liquid bag 242
  • another weak structure for allowing the electrolyte to flow out of the liquid bag 24 is also provided on the first liquid bag 241
  • the electrolyte can flow out of the liquid bag 24 from the second weak structure 252 and another weak structure located on the first liquid bag 241 at the same time, so as to increase the liquid replenishment speed of the liquid bag 24 to the casing 22 .
  • FIG. 10 is a schematic cross-sectional structure diagram of a battery cell 100 along the Y direction according to some embodiments of the present application.
  • at least one first liquid bag 241 is disposed between the cell assemblies 23
  • at least one second liquid bag 242 is located at two ends of the cell assembly 23 .
  • the second liquid bag 242 may be arranged at one or both ends of the cell assembly 23 , at the end where the tab 23a is located, or at the other end where the tab 23a is not provided. As shown in FIG.
  • the second liquid bag 242 is at one end of the tab 23a on the cell assembly, and extends to the tabs 23a of the cell assembly on both sides respectively, and is used to fill the tab 23a, the housing 22 and the battery pack.
  • the space between the core components 23; the liquid bag 242 extends to both sides of the battery core component 23 at one end of the battery core component 23 without tabs, and is used to fill the space between the other end of the battery core 23 and the housing 22 Space.
  • FIG. 11 is a schematic cross-sectional structure diagram of a battery cell 100 along the Y direction according to some embodiments of the present application.
  • a first liquid bag 241 is provided between the side wall of the cell assembly 23 and the side wall of the casing 22, and between the cell assembly 23, and at least one second liquid bag 242 can be located in the cell assembly. 23 in the region where the tab 23a is not provided.
  • the shape of the second liquid bag 242 can be designed to fill and deduct the tab 23a according to the shape of the tab 23a.
  • a second liquid bag 242 is provided at the corner of the end of the cell assembly 23 and the side wall of the housing 22 , and the shape of the second liquid bag 242 is adapted to the end of the cell assembly 23
  • the structure of the space between the shell and the shell, the second liquid bag 242 is at one end of the tab 23a on the cell assembly, extending toward the tab 23a, and is used to fill the space between the tab 23a and the side wall of the shell 22 Space; the liquid bag 242 is at one end of the cell assembly 23 without tabs, and is used to fill the space between the other end of the cell 23 and the casing 22 .
  • the shape of the second liquid bag 242 provided between the cell assemblies 23 is adapted to the space structure between the ends of the cell assemblies 23, and the second liquid bag 242 is at one end of the tab 23a on the cell assembly, Extend to the tabs 23a of the battery components on both sides respectively, for filling the space between the tabs 23a, the housing 22 and the battery components 23; One end respectively extends to both sides of the battery cell assembly 23 and is used to fill the space between the other end of the battery cell 23 and the casing 22 .
  • FIG. 12 is a schematic structural diagram of the liquid bag 24 in the battery cell 100 according to some embodiments of the present application.
  • the fluid capsule 24 may further include at least one buffer capsule 243 and a third weak structure 253 disposed between the first fluid capsule 241 and the second fluid capsule 242 .
  • the first weak structure 251 isolates the first liquid bag 241 and the buffer bag 243
  • the third weak structure 253 isolates the buffer bag 243 and the second liquid bag 242.
  • the buffer bag 243 When the pressure in the buffer bag 243 reaches a third threshold, the buffer bag 243 The electrolyte solution inside breaks through the third weak structure 253 and flows into the second liquid bag 242 .
  • the buffer bladder 243 can provide a connection between the first fluid bladder 241 and the second fluid bladder 242 , and the arrangement of the buffer bladder 243 is particularly advantageous when the second fluid bladder 242 is located in the area of the end of the cell assembly 23 .
  • the first weak structure 251 and the third weak structure 253 are used to isolate the first liquid bag 241 , the second liquid bag 242 , and the buffer bag 243 , thereby further providing the cell assembly 23 with a stepped expansion buffer capability.
  • FIG. 13 is a schematic structural diagram of the liquid bag 24 in the battery cell 100 according to some embodiments of the present application.
  • the at least one cushioning capsule 243 is at least one channel 243a spaced apart from each other, each channel 243a is provided with a first weak structure 251 at one end, and the other end of each channel 243a is provided with a third weak structure 253 .
  • Setting the buffer capsule 243 as at least one channel 243a at intervals can enable the battery cell 100 to break through different numbers of channels 243a according to the use degree and expansion force of the battery cell assembly 23, so as to achieve adaptive adjustment and release of the buffer space and internal electrolyte. Therefore, it is ensured that the performance of the battery cell assembly 23 tends to a consistent level in different positions and under different working conditions.
  • the volumes of the channels 243a may be the same or different. Affected by the position of the battery cell assembly 23 in the casing 22 , the force condition, and the temperature environment, the usage degree and expansion pressure of the battery cell assembly 23 are also different. Correspondingly configure the volumes of each channel 243a to be the same or different, so that the buffer space provided by each channel 243a can be the same or different, so that the liquid bag 24 can provide a precise Optimized inflation pressure adjustment capability.
  • FIG. 14 is a schematic structural diagram of the liquid bag 24 in the battery cell 100 according to some embodiments of the present application.
  • a second liquid bag 242 is respectively arranged on both sides of the first liquid bag 241
  • a first liquid bag 242 is arranged between the first liquid bag 241 and the second liquid bag 242.
  • a weak structure 251 when the pressure in the first liquid bag 241 reaches the first threshold, the electrolyte in the first liquid bag 241 breaks through the first weak structures 251 on both sides of the first liquid bag 241, and flows into the first liquid bag from both sides respectively.
  • each of the second liquid bags 242 is respectively provided with a second weak structure 252, and when the pressure in the second liquid bag 242 reaches a second threshold, the electrolyte in the second liquid bag 242 breaks through.
  • the second weakened structure 252 flows out of the second fluid bladder 242 .
  • a buffer bladder 243 and a third weak structure 253 are respectively provided between the first fluid bladder 241 and each of the second fluid bladders 242 , As shown in the figure, the first weak structure 251 isolates the first fluid bladder 241 from the buffer bladder 243, and the third weak structure 253 isolates the buffer bladder 243 from the second fluid bladder 242. When the pressure in the buffer bladder 243 reaches a third threshold, The electrolyte in the buffer bag 243 breaks through the third weak structure 253 and flows into the second liquid bag 242 . Further, continuing to refer to refer to FIG.
  • At least one buffer capsule 243 is at least one channel 243a arranged at intervals, each channel 243a is provided with a first weak structure 251 at one end, and the other end of each channel 243a is provided with a third weak structure 253 .
  • the interior arrangement of the cushion capsule 243 may be the same or different.
  • the interior of the cushion capsule 243 at one end is provided with a channel, and the interior of the cushion capsule 243 at the other end may not be provided with any channel, which is not limited here.
  • each second liquid bag 242 is disposed at both ends of the cell.
  • the first thresholds of each first weak structure 251 may be the same.
  • the pressure in the housing 22 will increase and produce a pressing force on the liquid bag 24, so that the pressure in the liquid bag 24 will also increase accordingly.
  • the first threshold the first weak structure 251 is broken by the electrolyte in the liquid bag 24 , and the electrolyte flows out of the liquid bag 24 from the rupture of the first weak structure 251 .
  • the pressure within the bladder 24 decreases until it reaches equilibrium with the pressure within the housing 22 .
  • the first thresholds of each first weak structure 251 may also be different.
  • the first thresholds of each first weak structure 251 are set to be different, so that each first weak structure 251 can be broken stepwise and step by step with the expansion of the battery cell assembly 23 and the increase of the pressure in the casing 22, realizing The stepwise relief of the expansion pressure of the cell assembly 23 and the gradual release of the electrolyte, and by setting the specific position of each first weak structure 251 and the value of each first threshold, the ability to relieve the expansion pressure and replenish the electrolyte can be realized fine-tuning.
  • the first threshold of the first weakened structure 251 may be in the range of 0.1 MPa to 2.0 MPa, which corresponds to the pressure range of the battery cell 100 in the casing 22 when the battery cell 100 is in use.
  • each second weak structure may be the same, or different.
  • the second weak structure 252 is disposed on the second liquid bag 242 , and the second liquid bag 242 does not contain electrolyte in an initial state.
  • the pressure in the casing 22 will increase and produce a pressing force on the first liquid bag 241, so that when the pressure in the liquid bag 241 increases to a first threshold, the first weak structure 251 is The electrolyte in the first liquid bag 241 breaks through, and the electrolyte flows out of the first liquid bag 241 into the second liquid bag 242 from the rupture of the first weak structure 251 , and the pressure in the first liquid bag 24 is released and correspondingly reduced.
  • the first liquid bag 241 and the second liquid bag 242 are further squeezed, the pressure in the second liquid bag 242 reaches the second threshold, and the electrolyte solution entering the second liquid bag 242 breaks through the first The second weak structure 252, and the second liquid bag flows out from the rupture of the second weak structure 242.
  • Setting the second thresholds of the plurality of second weak structures 252 to be the same can speed up the ability of the liquid bladder 24 to relieve the expansion pressure of the cell assembly 23 and realize rapid replenishment of the electrolyte in the casing 22 .
  • the expansion pressure buffering capacity of the liquid bladder 24 and the electrolyte solution can be finely adjusted by setting the specific positions of each second weak structure 252 and the value of each second threshold. Replenish.
  • the second threshold value of the second weak structure 252 may also be in the range of 0.1 MPa to 2.0 MPa, which corresponds to the pressure range of the battery cell 100 in the case 22 in use.
  • the third thresholds of each third weak structure 253 may also be the same or different.
  • the third weak structure 253 is disposed on the second liquid bag 242 and is spaced between the second liquid bag 242 and the buffer bag 243 .
  • the second liquid bag 242 and the buffer bag 243 do not contain electrolyte in the initial state.
  • the pressure in the casing 22 will increase and produce a pressing force on the first liquid bag 241, so that when the pressure in the liquid bag 241 increases to a first threshold, the first weak structure 251 is The electrolyte in the first liquid bag 241 breaks through, the electrolyte flows out of the first liquid bag 241 from the rupture of the first weak structure 251 and enters the buffer bag 243 , and the pressure in the first liquid bag 24 is released and correspondingly reduced.
  • the first liquid bag 241 and the buffer bag 243 are further squeezed, the pressure in the buffer bag 243 reaches the third threshold, and the electrolyte entering the buffer bag 243 breaks through the third weak structure 253, and The buffer bladder flows out from the rupture of the third weak structure 243 and enters the second liquid bladder 242 .
  • Setting the third thresholds of the plurality of third weak structures 253 to be the same can speed up the ability of the liquid bag 24 to relieve the expansion pressure of the cell assembly 23 and the electrolyte solution can quickly enter the second liquid bag 242 .
  • the expansion pressure cushioning capacity of the liquid bladder 24 can be finely adjusted by setting the values of the respective second thresholds.
  • each weakened structure 25 may include a thinned area formed on the liquid bladder 24 .
  • the weak structure 25 can be obtained by thinning the aluminum-plastic film at a specific position, such as stamping, melting, heat sealing, etc.
  • the structure 25 has a lower pressure bearing capacity than other positions on the liquid sac 24, so that when the pressure in the liquid sac 24 increases, the weak structure 25 formed by the thinning area is more likely to be broken by the electrolyte in the liquid sac 24, So that the electrolyte can flow out of the liquid bag 24 from the rupture of the thinned area.
  • each weak structure 25 can weaken the strength of the heat seal by adjusting the heat sealing process and parameters (optional parameters: packaging temperature: 25-300°C, hot air pressure: 10-500kgf , time 0.001-60s), to form a weak structure, and an additional interlayer part can also be designed on the liquid bladder 24 .
  • the interlayer portion may be formed by disposing an interlayer material at a specific position on the liquid bladder 24 .
  • the interlayer material can be a composite interlayer with a nylon layer and a CPP (Cast Polypropylene, cast polypropylene) layer, as shown in Figure 15, the interlayer material includes a nylon layer a, an adhesive layer b, an aluminum foil layer c, and a protective layer d , adhesive layer e and CPP layer f.
  • CPP Chemical Polypropylene, cast polypropylene
  • the nylon layer a is an outer protective layer, mainly to prevent the aluminum foil layer c from being scratched and play a protective role, generally polyhydantoin;
  • the adhesive layer b is used to connect the nylon layer a and the aluminum foil layer c , is generally an adhesive polymer layer, such as: polyolefin resin, etc.;
  • the aluminum foil layer c is a supporting layer, which mainly plays the role of sealing;
  • the protective layer d is an inorganic salt functional coating, which can play a role of resistance The role of electrolyte corrosion and high temperature corrosion resistance;
  • the adhesive layer e plays a bonding role, which can be a polyolefin adhesive;
  • the CPP layer is mainly used for heat sealing, and is generally made of polypropylene material.
  • the composite interlayer of the above-mentioned nylon layer and CPP layer is used as the composite material of the interlayer part, so that the interlayer part has a lower pressure bearing capacity than other positions of the liquid bag 24, and thus when the pressure in the liquid bag 24 increases, the CPP layer
  • the weak structure 25 formed by thermal bonding is more likely to be broken by the electrolyte in the liquid bag 24, so that the electrolyte can flow out of the liquid bag 24 from the rupture of the CPP layers of the two aluminum-plastic films.
  • the first weakened structure 251 may include at least one thinning area, or at least one interlayer part, or At the same time, at least one thinning zone and at least one interlayer part are included.
  • the second weakened structure 252 may include at least one thinned area, or at least one sandwich portion, or include at least one thinned area and at least A mezzanine.
  • the third weakened structure 253 may also include at least one thinned area, or at least one sandwich portion, or It includes at least one thinning zone and at least one interlayer part at the same time.

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Abstract

本申请公开了一种电池单体、电池及用电装置。电池单体包括：内部填充电解液的壳体；布置于所述壳体内的至少一个电芯组件；以及至少一个盛放有电解液的封闭的液囊，所述液囊布置于所述壳体内，并至少与所述电芯组件的侧壁对应设置；所述液囊上设有至少一个薄弱结构，当所述液囊内的压力达到阈值时，所述液囊内的所述电解液冲破所述薄弱结构流出所述液囊。本申请实施例的电池单体通过在壳体内布置带有薄弱结构的液囊，并使液囊与电芯组件的侧壁对应设置，使得当电芯组件在使用过程中发生膨胀时，能够缓解电池析锂或局部电解液枯竭导致的电池性能恶化的情况。

Description

电池单体、电池及用电装置 技术领域
本申请涉及电池领域，具体涉及一种电池单体、电池及用电装置。
背景技术
节能减排是汽车产业可持续发展的关键，电动车辆由于其节能环保的优势成为汽车产业可持续发展的重要组成部分。对于电动车辆而言，电池技术又是关乎其发展的一项重要因素。
电池在充放电的使用过程中，考虑电芯发生鼓胀而采用低群裕度设计，带来析锂风险。此外随着电池的充放电循环，电解液也被不断消耗甚至发生局部电解液枯竭，进一步导致电池性能衰退，影响电池的寿命并可能带来安全隐患。
发明内容
鉴于上述问题，本申请提供一种电池单体、电池及用电装置，能够缓解电池使用过程中的电池析锂或局部电解液枯竭导致的电池性能恶化的情况。
第一方面，本申请提供了一种电池单体，包括：内部填充电解液的壳体；布置于所述壳体内的至少一个电芯组件；以及布置于所述壳体内并至少与所述电芯组件的侧壁对应设置的至少一个封闭的液囊，所述液囊内盛放有电解液；所述液囊上设有至少一个薄弱结构，当所述液囊内的压力达到阈值时，所述液囊内的所述电解液冲破所述薄弱结构流出所述液囊。
本申请实施例的技术方案中，在电池单体的壳体内布置液囊，并使液囊至少与电芯组件的侧壁对应设置。这样的设计使得在电池使用初期，液囊能够占据电池壳体内的空余空间，克服低群裕度设计的电池中电芯打皱的问题，从而避免电极析锂问题；随着电池充放电循环的进行，电芯发生膨胀时，电芯侧壁将挤压液囊，使液囊发生形变并填充电池壳体内的空余区域，缓解电芯膨胀压力；随着电芯膨胀力进一步增大，电芯组件的侧壁进一步挤压液囊使液囊内的压力达到阈值时，液囊内的电解液将冲破液囊 上设置的薄弱结构流出液囊，实现对壳体内电解液的自动补充。
在一些实施例中，所述侧壁包括位于所述电芯组件的两个端部中间区域的中间侧壁部分，所述液囊与所述中间侧壁部分对应设置。通过将液囊设置为与电芯组件的中间侧壁部分对应，可以缓解电芯组件中部的膨胀压力，更有效地缓解电池使用过程中电芯膨胀力对电池壳体的变形。
在一些实施例中，所述液囊设置在所述电芯组件与所述壳体的侧壁之间，和/或，所述液囊设置在相邻的所述电芯组件之间。本申请实施例的电池单体中，液囊在壳体内的布置方式灵活，只要满足液囊有一侧与电芯组件的侧壁相贴即可。
在一些实施例中，至少一个所述薄弱结构设置在所述液囊的至少部分边缘处。这样的设计使得当液囊内的电解液能够从液囊的边缘处流出，从而方便从电芯组件侧壁的间隙处补充壳体内的电解液消耗。
在一些实施例中，多个所述薄弱结构间隔设置于所述液囊的至少部分边缘处。通过在液囊的至少部分边缘处设置间隔布置的多个薄弱结构，使得电解液能够分散地从多个薄弱结构处流出液囊，实现分散缓释的效果。
在一些实施例中，所述电池单体包括在使用状态时的上方端部，至少一个所述薄弱结构位于所述液囊上靠近所述上方端部的位置处。在电池使用后期，因重力作用，顶部更容易发生电解液不足甚至枯竭。这样的设计能够方便地从电池单体顶部补充电解液，避免电解液局部枯竭。
在一些实施例中，所述液囊包括至少一个第一液囊和至少一个第二液囊，所述第一液囊盛放有电解液，所述第二液囊未盛放电解液，所述第一液囊与所述第二液囊在初始状态时相互隔离。这样的设计中，第二液囊起到缓冲空间的作用，增大了液囊对电芯组件膨胀压力的调节空间。
在一些实施例中，所述液囊包括设于所述第一液囊与所述第二液囊之间用于使其相互隔离的第一薄弱结构，当所述第一液囊内的压力达到第一阈值时，所述第一液囊内的所述电解液冲破所述第一薄弱结构，流入所述第二液囊中。通过设置隔离在第一液囊与第二液囊之间的第一薄弱结构，使得电解液在冲破第一薄弱结构后流入第二液囊，提供阶梯式的膨胀压力调节能力。
在一些实施例中，所述第二液囊上还设有第二薄弱结构，当所述第二 液囊内的压力达到所述第二阈值时，所述第二液囊内的所述电解液冲破所述第二薄弱结构流出所述第二液囊。通过在第二液囊上进一步设置第二薄弱结构，第一液囊在受挤压时，内部的电解液首先进入第二液囊，进一步受挤压时电解液冲破第二薄弱结构从第二液囊流出，对壳体内电解液进行自动补充。
在一些实施例中，至少一个所述第二液囊位于所述电芯组件的两个端部的区域。如此可以有效利用电芯组件端部在端盖与电芯组件之间的高度空间，在对电池能量密度要求日益提高的情况下，这样的设计是有利的。
在一些实施例中，所述第二液囊位于所述电芯组件的所述上方端部的未设置极耳的区域内。电芯组件端部通常设置有极耳，但极耳并未占据端盖与电芯组件之间的全部高度空间，使第二液囊位于电芯组件上方端部未设置极耳的区域，可以进一步利用到这部分空间。
在一些实施例中，所述液囊还包括设于所述第一液囊与所述第二液囊之间的至少一个缓冲囊以及第三薄弱结构，所述第一薄弱结构隔离所述第一液囊与所述缓冲囊，所述第三薄弱结构隔离所述缓冲囊与所述第二液囊，当所述缓冲囊内的压力达到第三阈值时，所述缓冲囊内的所述电解液冲破所述第三薄弱结构流入所述第二液囊。通过在第一液囊与第二液囊之间设置缓冲囊，并利用第一薄弱结构和第三薄弱结构隔离在它们之间，进一步为液囊提供阶梯式的膨胀压力调节能力。
在一些实施例中，至少一个所述缓冲囊为相互间隔设置的至少一个通道，每个所述通道一端设置有所述第一薄弱结构，每个所述通道的另一端设置有所述第三薄弱结构。将缓冲囊设置为间隔的至少一个通道，可以防止薄弱结构在被电解液冲破时，界面接触位置改变幅度较大导致电池性能恶化。
在一些实施例中，当所述缓冲囊包括多个所述通道时，各个所述通道的体积相同或不同。壳体内各电芯组件的位置、受力情况、温度环境因素影响电芯组件的使用程度和膨胀压力，相应地，配置各个通道的体积为相同或不同，使得各通道所提供的缓冲空间可以相同或不同，从而为液囊提供精细化的膨胀压力调节能力。
在一些实施例中，当所述液囊包括多个所述第一薄弱结构时，各个所 述第一薄弱结构的所述第一阈值相同或不同；在一些实施例中，当所述液囊包括多个所述第二薄弱结构时，各个所述第二薄弱结构的所述第二阈值相同或不同；在一些实施例中，当所述液囊包括多个所述第三薄弱结构时，各个所述第三薄弱结构的所述第三阈值相同或不同。
多个第一阈值、多个第二阈值和多个第三阈值各自为相同的值时，液囊在受挤压的情况下，能够在各个薄弱结构的位置处同时均匀地释放缓冲空间，以及均匀地释放电解液到壳体内的各个薄弱结构的位置处，这对于缓冲空间的快速释放、电解液的快速补充是有利的。
多个第一阈值、第二阈值或第三阈值各自为不同的值，或是部分薄弱结构的阈值相同、部分薄弱结构的阈值不同时，液囊在受挤压的情况下，能够随挤压程度逐级释放缓冲空间，以及逐步释放电解液到壳体内，从而避免变化幅度过大导致电池性能恶化，确保不同位置和温度工况下电芯组件的性能趋向一致性水平。
在一些实施例中，所述第一薄弱结构包括设于所述第一液囊上的至少一个减薄区和/或至少一个夹层部；在一些实施例中，所述第二薄弱结构包括设于所述第二液囊上的至少一个减薄区和/或至少一个夹层部；在一些实施例中，所述第三薄弱结构包括设于所述第二液囊上的至少一个减薄区和/或至少一个夹层部。各薄弱结构的实现方式灵活，可以为位于液囊上的减薄区，这样的方式制作工艺简单；也可以为设置在液囊上的不同材料的夹层，只要能够形成受力薄弱结构即可。
在一些实施例中，所述第一阈值、所述第二阈值、所述第三阈值各自独立地在0.1MPa至2.0MPa之间。将薄弱结构的压力阈值设置在该范围，使得当液囊内的压力达到该阈值时，电解液将冲破薄弱结构进入缓冲空间或流出液囊，缓解电芯组件的膨胀压力，从而避免因电芯组件过度膨胀对电池性能的不利影响。
第二方面，本申请提供了一种电池，其包括上述实施例中的电池单体。
第三方面，本申请提供了一种用电装置，其包括上述实施例中的电池，所述电池用于提供电能。
上述说明仅是本申请技术方案的概述，为了能够更清楚了解本申请的技术手段，而可依照说明书的内容予以实施，并且为了让本申请的上述和 其它目的、特征和优点能够更明显易懂，以下特举本申请的具体实施方式。
附图说明
通过阅读对下文优选实施方式的详细描述，各种其他的优点和益处对于本领域普通技术人员将变得清楚明了。附图仅用于示出优选实施方式的目的，而并不认为是对本申请的限制。而且在全部附图中，用相同的附图标号表示相同的部件。在附图中：
图1为本申请一些实施例的车辆的结构示意图；
图2位本申请一些实施例的电池的分解结构示意图；
图3为本申请一些实施例的电池单体的分解结构示意图；
图4为本申请一些实施例的电池单体沿Y方向的剖面结构示意图；
图5为本申请一些实施例的电池单体沿X方向的剖面结构示意图；
图6为本申请一些实施例的电池单体沿X方向的剖面结构示意图，示出液囊受挤压时的状态；
图7为本申请一些实施例的电池单体沿X方向的剖面结构示意图，示出液囊受挤压并且电解液冲破薄弱结构流出液囊时的状态；
图8为本申请一些实施例的电池单体中液囊的结构示意图；
图9为本申请一些实施例的电池单体中液囊的结构示意图；
图10为本申请一些实施例的电池单体沿X方向的剖面结构示意图；
图11为本申请一些实施例的电池单体沿X方向的剖面结构示意图；
图12为本申请一些实施例的电池单体中液囊的结构示意图；
图13为本申请一些实施例的电池单体中液囊的结构示意图；
图14为本申请一些实施例的电池单体中液囊的结构示意图；
图15为本申请一些实施例的夹层材料结构示意图。
具体实施方式中的附图标号如下：
车辆1000；
电池100，控制器200，马达300；
箱体10，第一部分11，第二部分12；
电池单体20，端盖21，电极端子21a，壳体22，电芯组件23，极耳23a，液囊24，薄弱结构25；
第一液囊241，第二液囊242，缓冲囊243，通道243a，第一薄弱结构251，第二薄弱结构252，第三薄弱结构253。
具体实施方式
下面将结合附图对本申请技术方案的实施例进行详细的描述。以下实施例仅用于更加清楚地说明本申请的技术方案，因此只作为示例，而不能以此来限制本申请的保护范围。
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；本文中所使用的术语只是为了描述具体的实施例的目的，不是旨在于限制本申请；本申请的说明书和权利要求书及上述附图说明中的术语“包括”和“具有”以及它们的任何变形，意图在于覆盖不排他的包含。
在本申请实施例的描述中，技术术语“第一”“第二”等仅用于区别不同对象，而不能理解为指示或暗示相对重要性或者隐含指明所指示的技术特征的数量、特定顺序或主次关系。在本申请实施例的描述中，“多个”的含义是两个以上，除非另有明确具体的限定。
在本文中提及“实施例”意味着，结合实施例描述的特定特征、结构或特性可以包含在本申请的至少一个实施例中。在说明书中的各个位置出现该短语并不一定均是指相同的实施例，也不是与其它实施例互斥的独立的或备选的实施例。本领域技术人员显式地和隐式地理解的是，本文所描述的实施例可以与其它实施例相结合。
在本申请实施例的描述中，术语“和/或”仅仅是一种描述关联对象的关联关系，表示可以存在三种关系，例如A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B这三种情况。另外，本文中字符“/”，一般表示前后关联对象是一种“或”的关系。
在本申请实施例的描述中，术语“多个”指的是两个以上(包括两个)，同理，“多组”指的是两组以上(包括两组)，“多片”指的是两片以上(包括两片)。
在本申请实施例的描述中，技术术语“中心”“纵向”“横向”“长度”“宽度”“厚度”“上”“下”“前”“后”“左”“右”“竖直”“水平”“顶” “底”“内”“外”“顺时针”“逆时针”“轴向”“径向”“周向”等指示的方位或位置关系为基于附图所示的方位或位置关系，仅是为了便于描述本申请实施例和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本申请实施例的限制。
在本申请实施例的描述中，除非另有明确的规定和限定，技术术语“安装”“相连”“连接”“固定”等术语应做广义理解，例如，可以是固定连接，也可以是可拆卸连接，或成一体；也可以是机械连接，也可以是电连接；可以是直接相连，也可以通过中间媒介间接相连，可以是两个元件内部的连通或两个元件的相互作用关系。对于本领域的普通技术人员而言，可以根据具体情况理解上述术语在本申请实施例中的具体含义。
目前，从市场形势的发展来看，动力电池的应用越加广泛。动力电池不仅被应用于水力、火力、风力和太阳能电站等储能电源系统，而且还被广泛应用于电动自行车、电动摩托车、电动汽车等电动交通工具，以及军事装备和航空航天等多个领域。随着动力电池应用领域的不断扩大，其市场的需求量也在不断地扩增。
本发明人注意到，随着电池的充放电循环中正极活性物质和负极活性物质嵌入或脱出离子，电芯体系副反应堆积厚度及石墨片层剥离等导致电芯会发生鼓胀，即正极片和负极片向外膨胀。极片膨胀对电池的性能及使用寿命有不利影响，例如，受力挤压可能导致极片孔隙率降低影响电解液对极片的浸润，引起离子传输路径发生改变，带来析锂问题；极片在长期承受较大挤压力时，还可能断裂引发电池内短路风险等等。此外，电池在充放电循环中电解液也会被不断消耗，在电芯使用一定时间后，甚至会发生局部电解液枯竭，电芯鼓胀则会更进一步加剧局部电解液不足的状况。
为了缓解电芯膨胀力的问题，申请人研究发现，可以在设计上为电芯预留膨胀空间。具体为降低电芯在电池壳体内的群裕度，即降低电池中电芯厚度占壳体内腔厚度的百分比。例如，在低群裕度设计的电池中，电芯在厚度方向上的入壳群裕度通常在88.5％以下，满充群裕度通常在97％以下。然而，低群裕度设计的电池在初期的状态下，由于壳体内较大的空隙，可能发生电芯打皱的问题。例如，阳极极片打皱会引发锂离子在阳极界面 的路径变化，带来析锂风险，影响电池的性能和寿命。
基于以上考虑，为了解决电芯使用过程中考虑电芯的膨胀力采用低群裕度设计导致电芯性能恶化的问题及电解液不足的问题，发明人经过深入研究，设计了一种电池单体，通过在电池单体的壳体内布置至少一个封闭的液囊，并设置液囊至少与电芯组件的侧壁对应，在液囊内盛放电解液，并在液囊上设置薄弱结构，使得当液囊内的压力达到阈值时，电解液能够冲破薄弱结构流出液囊。
在这样的电池单体中，由于液囊与电芯组件的侧壁对应设置，使得在电池单体的使用初期，液囊能够占据壳体内在电芯组件厚度方向上的空余空间，相当于提高了电池单体的等效群裕度，能够有效避免低群裕度设计的电池中电芯组件极片打皱的问题。
伴随电池单体在使用中的充放电循环，电芯组件发生鼓胀时，与电芯组件侧壁对应设置的液囊将受挤压并发生形变。电池单体中不同位置的电芯组件因受力差异和温度环境差异等因素影响，电芯组件之间的膨胀力大小也有不同，液囊可以根据各个电芯组件的实际膨胀压力被不同程度地挤压变形，从而实现对电芯组件膨胀压力的自适应调节。
在对电池能量密度需求的日益增加的背景下，本申请的电池单体能够充分利用壳体内部空间作为电芯组件的膨胀力缓冲空间。例如，通常电芯组件中间位置相较于两端鼓胀较为严重，膨胀力也较大。该情况下，液囊内被挤压变形，对应于电芯组件侧壁中间位置的部分变薄，电解液被挤压到两端的缓冲空间，如此可以缓解电芯组件中部膨胀力，避免电池性能的进一步恶化及析锂风险。
随着电芯组件的进一步使用和膨胀力的进一步增大，液囊被进一步挤压，当液囊内的压力被挤压达到阈值时，电解液将冲破液囊上的薄弱结构并流出液囊，进入壳体内并补充电池单体壳体内的电解液损耗，实现自动补液的效果。需要说明的是，液囊中的电解液可以与壳体内的初始电解液一致，也可以为不同的电解液。例如液囊中的电解液可以采用针对使用的电芯组件的特制电解液，或为其他功能性电解液。
本申请实施例公开的电池单体可以但不限用于车辆、船舶或飞行器等用电装置中。可以使用具备本申请公开的电池单体、电池等组成该用电装置的 电源系统，这样，有利于缓解并自动调节电芯膨胀力恶化，补充电解液消耗，提升电池性能的稳定性和电池寿命。
本申请实施例提供一种使用电池作为电源的用电装置，用电装置可以为但不限于手机、平板、笔记本电脑、电动玩具、电动工具、电瓶车、电动汽车、轮船、航天器等等。其中，电动玩具可以包括固定式或移动式的电动玩具，例如，游戏机、电动汽车玩具、电动轮船玩具和电动飞机玩具等等，航天器可以包括飞机、火箭、航天飞机和宇宙飞船等等。
以下实施例为了方便说明，以本申请一实施例的一种用电装置为车辆1000为例进行说明。
请参照图1，图1为本申请一些实施例提供的车辆1000的结构示意图。车辆1000可以为燃油汽车、燃气汽车或新能源汽车，新能源汽车可以是纯电动汽车、混合动力汽车或增程式汽车等。车辆1000的内部设置有电池100，电池100可以设置在车辆1000的底部或头部或尾部。电池100可以用于车辆1000的供电，例如，电池100可以作为车辆1000的操作电源。车辆1000还可以包括控制器200和马达300，控制器200用来控制电池100为马达300供电，例如，用于车辆1000的启动、导航和行驶时的工作用电需求。
在本申请一些实施例中，电池100不仅可以作为车辆1000的操作电源，还可以作为车辆1000的驱动电源，代替或部分地代替燃油或天然气为车辆1000提供驱动动力。
请参照图2，图2为本申请一些实施例提供的电池100的爆炸图。电池100包括箱体10和电池单体20，电池单体20容纳于箱体10内。其中，箱体10用于为电池单体20提供容纳空间，箱体10可以采用多种结构。在一些实施例中，箱体10可以包括第一部分11和第二部分12，第一部分11与第二部分12相互盖合，第一部分11和第二部分12共同限定出用于容纳电池单体20的容纳空间。第二部分12可以为一端开口的空心结构，第一部分11可以为板状结构，第一部分11盖合于第二部分12的开口侧，以使第一部分11与第二部分12共同限定出容纳空间；第一部分11和第二部分12也可以是均为一侧开口的空心结构，第一部分11的开口侧盖合于第二部分12的开口侧。当然，第一部分11和第二部分12形成的箱体10可以 是多种形状，比如，圆柱体、长方体等。
在电池100中，电池单体20可以是多个，多个电池单体20之间可串联或并联或混联，混联是指多个电池单体20中既有串联又有并联。多个电池单体20之间可直接串联或并联或混联在一起，再将多个电池单体20构成的整体容纳于箱体10内；当然，电池100也可以是多个电池单体20先串联或并联或混联组成电池模块形式，多个电池模块再串联或并联或混联形成一个整体，并容纳于箱体10内。电池100还可以包括其他结构，例如，该电池100还可以包括汇流部件，用于实现多个电池单体20之间的电连接。
其中，每个电池单体20可以为锂离子二次电池、锂离子一次电池、锂硫电池、钠锂离子电池或镁离子电池，但不局限于此。电池单体20可呈圆柱体、扁平体、长方体或其它形状等。
请参照图3，图3为本申请一些实施例提供的电池单体20的分解结构示意图。电池单体20是指组成电池的最小单元。如图3，电池单体20包括有端盖21、壳体22、电芯组件23、液囊24以及其他的功能性部件。
端盖21是指盖合于壳体22的开口处以将电池单体20的内部环境隔绝于外部环境的部件。不限地，端盖21的形状可以与壳体22的形状相适应以配合壳体22。可选地，端盖21可以由具有一定硬度和强度的材质(如铝合金)制成，这样，端盖21在受挤压碰撞时就不易发生形变，使电池单体20能够具备更高的结构强度，安全性能也可以有所提高。端盖21上可以设置有如电极端子21a等的功能性部件。电极端子21a可以用于与电芯组件23电连接，以用于输出或输入电池单体20的电能。在一些实施例中，端盖21上还可以设置有用于在电池单体20的内部压力或温度达到阈值时泄放内部压力的泄压机构。端盖21的材质也可以是多种的，比如，铜、铁、铝、不锈钢、铝合金、塑胶等，本申请实施例对此不作特殊限制。在一些实施例中，在端盖21的内侧还可以设置有绝缘件，绝缘件可以用于隔离壳体22内的电连接部件与端盖21，以降低短路的风险。示例性的，绝缘件可以是塑料、橡胶等。
壳体22是用于配合端盖21以形成电池单体20的内部环境的组件，其中，形成的内部环境可以用于容纳电芯组件23、电解液以及其他部件。壳体22和端盖21可以是独立的部件，可以于壳体22上设置开口，通过在开口处使端盖21盖合开口以形成电池单体20的内部环境。不限地，也可 以使端盖21和壳体22一体化，具体地，端盖21和壳体22可以在其他部件入壳前先形成一个共同的连接面，当需要封装壳体22的内部时，再使端盖21盖合壳体22。壳体22可以是多种形状和多种尺寸的，例如长方体形、圆柱体形、六棱柱形等。具体地，壳体22的形状可以根据电芯组件23的具体形状和尺寸大小来确定。壳体22的材质可以是多种，比如，铜、铁、铝、不锈钢、铝合金、塑胶等，本申请实施例对此不作特殊限制。
电芯组件23是电池单体100中发生电化学反应的部件。壳体22内可以包含一个或更多个电芯组件23。电芯组件23主要由正极片和负极片卷绕或层叠放置形成，并且通常在正极片与负极片之间设有隔膜。正极片和负极片具有活性物质的部分构成电芯组件的主体部，正极片和负极片不具有活性物质的部分各自构成极耳23a。正极极耳和负极极耳可以共同位于主体部的一端或是分别位于主体部的两端。在电池的充放电过程中，正极活性物质和负极活性物质与电解液发生反应，极耳23a连接电极端子以形成电流回路。
液囊24为内部盛放有电解液的封闭囊体，在受到挤压时可发生形变。为适应于电池内部的使用环境以及便于密封，液囊24应当使用具有耐腐蚀性和粘合性的不导电封装材料形成。例如可以使用包含外部保护层和内部密封层的功能复合膜或封装材料。其中外部保护层为耐腐蚀的绝缘材料，能够适用于电池内的电解质环境，并适应电池使用状态下的温度压力等环境。例如外部保护层可以为铝、铁氟龙、亚克力、聚丙烯等。内部密封层例如可以为方便通过热封工艺进行封装的热塑性聚酯膜或涂层，如聚丙烯、聚氯乙烯、聚苯乙烯、丙烯酸树脂、聚碳酸酯、聚四氟乙烯、聚氨酯等。在一些实施例中，可以使用铝塑膜通过热封形成封闭的液囊24。
液囊24上设有薄弱结构，薄弱结构具有较液囊24上其他位置更低的强度，使得当液囊24内的压力达到阈值时，电解液将冲破薄弱结构并从薄弱结构处的破裂口流出液囊24。
请参照图3并请进一步参照图4至图7，图4为根据本申请一些实施例的电池单体沿Y方向的剖面结构示意图，图5至图7为根据本申请一些实施例的电池单体在沿X方向的剖面结构示意图，其中图6和图7分别示出液囊受挤压时的状态以及电解液冲破薄弱结构流出液囊时的状态。
如图中所示，图中Y方向为电芯组件23的高度方向。极耳23a位于电芯组件23高度方向上的端部，并与端盖21上的电极端子21a电连接。壳体22内填充电解液；至少一个电芯组件23布置于壳体22内；封闭的液囊24布置于壳体22内，液囊24内盛放有电解液，并至少与电芯组件23的侧壁对应设置；液囊24上设有至少一个薄弱结构25。当液囊24内的压力达到阈值时，液囊内的电解液冲破薄弱结构25流出液囊24。
“电芯组件23的侧壁”是指电芯组件23在与高度方向(图3中的Y方向)平行方向的外壁。电芯组件23的膨胀力通常沿与高度方向垂直的方向，因此电芯组件23的鼓胀方向主要发生在大面侧壁(即厚度方向，图3中的Z方向)和拐角处(即宽度方向的两端，图3中的X方向的两端)。使“液囊24至少与电芯组件23的侧壁对应设置”是指在液囊24布置在壳体22内并至少部分液囊24与电芯组件23的侧壁相贴靠。
通过在壳体22内设置液囊24至少与电芯组件23的侧壁对应，使得在电池单体100使用初期，液囊24能够占据电芯组件23的侧壁与壳体22侧壁之间的空余空间，对电芯组件23起到支撑作用，可以有效避免电芯组件23的打皱问题。这对于低群裕度设计的电池是尤其有利的。
参照图6，随着电芯组件23使用时间的增加，在侧壁发生鼓胀时，对与电芯组件23的侧壁对应设置的液囊24产生挤压力，图6中箭头方向为电芯组件23鼓胀对液囊24的挤压力方向。液囊24受挤压将发生形变，与电芯组件23侧壁对应位置处变薄，液囊24内的电解液相对地聚集到受挤压力较小的区域，例如图中在液囊24沿电芯组件23高度方向的端部区域，利用该区域作为电芯组件23膨胀力的缓冲空间。同时液囊24内部压力增大，对电芯组件23侧壁的膨胀力产生一定对抗和缓解。这样，可以避免电芯组件23膨胀力进一步恶化，挤压极片导致的析锂风险。
参考图7，随着电芯组件23使用时间进一步增加，膨胀力进一步增大，对液囊24的挤压程度也进一步增加。当液囊24内部压力增大到阈值时，薄弱结构25被冲破，液囊24内的电解液从薄弱结构25位置处的破裂口流出液囊24，如图7中上方的弯曲箭头所示。本申请实施例的电池单体100通过在液囊24上设置至少一个薄弱结构25，使得在电芯组件23膨胀力达到一定程度时，液囊24内的电解液能够自动补充壳体22内的电解液损耗。
根据本申请的一些实施例，可选地，请继续参考图5至图7，电芯组件23的侧壁包括位于电芯组件23两个端部中间区域的中间侧壁部分，并且至少部分液囊24与电芯组件23的中间侧壁部分对应设置。电芯组件23的中间侧壁部分往往为电芯使用过程中，鼓胀最严重、膨胀力最大的部分，使至少部分液囊24与该中间侧壁部分对应设置，能够缓解该部分电芯组件23的膨胀力，避免电芯组件23中间区域的极片承受较大挤压，避免因此导致的析锂问题以及电池性能恶化。
根据本申请的一些实施例，可选地，液囊24可以设置在电芯组件23与壳体22的侧壁之间；或者液囊24也可以设置在相邻的电芯组件23之间。只要满足液囊24至少一面与电芯组件23的侧壁相贴，使得在电芯组件23因使用而发生鼓胀时，能够对液囊24产生挤压，即可实现本申请的目的。
例如，液囊24的至少一部分可以设置在电芯组件23的侧壁与壳体22的侧壁之间；在壳体22内布置有两个或更多个电芯组件23的实施例中，液囊24的至少一部分可以设置在相邻的电芯组件23的侧壁之间，或是设置在电芯组件23的侧壁与壳体22的侧壁之间；在电芯组件23为圆柱形的实施例中，液囊24的至少一部分可以呈环形围绕圆柱形电芯组件23的侧壁，并且设置在电芯组件23的侧壁与壳体22的侧壁之间。液囊24也可以为一个或多个，在壳体22内布置有多个液囊24的实施例中，也可以是至少一个液囊24设置在电芯组件23的侧壁与壳体22的侧壁之间，或是至少一个液囊24设置在相邻的电芯组件23的侧壁之间。可选地，液囊24设置于壳体中的形式，可以具体为被夹设在电芯组件23的侧壁和/或壳体11的侧壁之间。
根据本申请的一些实施例，可选地，请参考图8，图8为根据本申请一些实施例的电池单体100中液囊24的结构示意图。如图中所示，至少一个薄弱结构25设置在液囊24的至少部分边缘处。
液囊24的边缘处是指液囊24上不与电芯组件23的侧壁或壳体22的侧壁相贴合的部分。例如在电芯组件23为方块形，并且液囊24设置在相邻的电芯组件23的侧壁之间的实施例中，液囊24的边缘处可以包括液囊24在沿电芯组件23高度方向(例如图3中的Y方向)的两端，或是液囊24在沿电芯组件23宽度方向(例如图3中的X方向)的两侧。因此，液 囊24的边缘处于相邻的电芯组件23之间的间隙，或是电芯组件23与壳体22之间的间隙，并且不与电芯组件23或壳体22的侧壁相贴合。将薄弱结构25设置在液囊24的至少部分边缘处，使得当液囊24受挤压并且内部压力达到阈值时，电解液能够冲破位于液囊24边缘处的薄弱结构25，并容易地从液囊24的边缘处流出，不被电芯组件23的侧壁或壳体22的侧壁阻挡，更方便从电芯组件24侧壁的间隙处补充壳体22内的电解液消耗。
根据本申请的一些实施例，可选地，电池单体100包括在使用状态时的上方端部，至少一个薄弱结构25位于液囊24上靠近上方端部的位置处。由于重力作用，电池单体100在使用状态下的上方端部更容易出现电解液不足甚至局部枯竭。将薄弱结构25设置在液囊24上靠近上方端部的位置处，方便在液囊24内的电解液冲破薄弱结构25时，从电池单体100上方端部流出液囊24，对壳体22内的电解液进行补充，避免电解液局部枯竭的风险。与电池单体100在使用状态时的放置方向相关，电池单体100在使用状态时的上方端部可以是靠近端盖21所在的一端，也可以是与端盖21所在端相反的另一端，也可以是沿电芯组件23厚度方向上的上方端部等等。
根据本申请的一些实施例，可选地，请参考图9，图9为根据本申请一些实施例的电池单体100中液囊的结构示意图。如图中所示，液囊24可以包括至少一个第一液囊241和至少一个第二液囊242，第一液囊241盛放有电解液，第二液囊242未盛放电解液，第一液囊241与第二液囊242在初始状态时相互隔离。
由于第一液囊241内盛放有电解液，与第一液囊241相隔离的第二液囊242内未盛放电解液。这样的设计使得在初始状态时，第二液囊242几乎不占据壳体22内的空间；第一液囊241受电芯组件23侧壁挤压后，第一液囊241内的电解液进入第二液囊242，因此第二液囊242相当于起到的缓冲空间的作用。相当于可以通过设置第二液囊242在壳体22内的位置，引导液囊24内的电解液在受挤压时向该位置处聚集，提高了对电池单体100壳体22内空间的利用率。例如，第二液囊242的位置可以根据需要设置在壳体22内任何空余空间，并且可以根据实际情况设置为特定形状。这在目前对电池能量密度要求日益增加的背景下，是尤其有利的。
根据本申请的一些实施例，可选地，请再次参考图9，图9为根据本申请一些实施例的电池单体100中液囊24的结构示意图。如图中所示，液囊24包括可以设于第一液囊241与第二液囊242之间用于使其相互隔离的第一薄弱结构251，当第一液囊241内的压力达到第一阈值时，第一液囊241内的电解液冲破第一薄弱结构251，流入第二液囊242中，实现对电芯组件23膨胀力的一级缓冲。通过设置隔离在第一液囊241与第二液囊242之间的第一薄弱结构251，使得电解液在冲破第一薄弱结构251后流入第二液囊242，实现对电芯组件23膨胀力的二级缓冲。如此，可以为电池单体100提供阶梯式的膨胀压力调节能力。
根据本申请的一些实施例，可选地，请再次参考图9，第二液囊242上还可以设有第二薄弱结构252，当第二液囊242内的压力达到第二阈值时，第二液囊242内的电解液冲破第二薄弱结构252流出第二液囊242。通过在第二液囊242上设置第二薄弱结构252，可以方便电解液从第二液囊242上的第二薄弱结构252处流出补充壳体22内的电解液损耗。
当然，在其他实施例中，也可以不在第二液囊242上设置供电解液流出的第二薄弱结构252，而是仅在第一液囊241上设有用于供电解液流出液囊24的另外的薄弱结构，使得随液囊24受挤压程度的增加，第一液囊241内部的电解液先流入第二液囊242，再从设于第一液囊241上的薄弱结构流出到壳体22内。或者在其他实施例中，也可以在第二液囊242上设置第二薄弱结构252的同时，还在第一液囊241上同时设有用于供电解液流出液囊24的另外的薄弱结构，使得电解液能够从第二薄弱结构252和位于第一液囊241上的另外的薄弱结构同时流出液囊24，提升液囊24对壳体22内的补液速度。
根据本申请的一些实施例，可选地，请参考图10，为根据本申请一些实施例的电池单体100在沿Y方向的剖面结构示意图。如图中所示，至少一个第一液囊241设置在电芯组件23之间，至少一个第二液囊242位于电芯组件23的两个端部的区域。在电芯组件23端部区域，通常有空余空间。例如端盖21与电芯组件23之间的高度空间，除极耳23a所占空间以外，还存在一些未被极耳23a占据的空余空间；或者在电芯组件23底部与壳体22底部之间也存在一定空余空间，这些空间往往难以得到利用。本申请通 过将第二液囊242布置在电芯组件23的端部区域，可以有效利用电芯组件23端部的高度空余空间，用于电芯组件23的膨胀力缓冲空间。第二液囊242可以布置在电芯组件23的一端或两端，可以在极耳23a所在一端，也可以在未设置极耳23a的另一端。如图10所示，所述第二液囊242在电芯组件上极耳23a的一端，分别向两侧电芯组件的极耳23a处延伸，用于填充极耳23a、壳体22与电芯组件23之间的空间；所述液囊242在电芯组件23上未设置极耳的一端，分别向电芯组件23两侧延伸，用于填充电芯23另一端与壳体22之间的空间。
根据本申请的一些实施例，可选地，请继续参考图11，为根据本申请一些实施例的电池单体100在沿Y方向的剖面结构示意图。如图中所示，所述电芯组件23侧壁与壳体22侧壁之间，以及电芯组件23之间设置有第一液囊241，至少一个第二液囊242可以位于电芯组件23的上方端部的未设置极耳23a的区域内。当第二液囊242布置在电芯组件23上方端部时，尤其是在极耳23a所在的一端时，可以根据极耳23a的形状，设计第二液囊242的形状为填充扣除极耳23a所占空间以外的空间，以充分利用电池单体100壳体22内的空间，这对于提高电池能量密度尤为有利。如图11所示，在电芯组件23的端部与壳体22侧壁的拐角处设置有第二液囊242，所述的第二液囊242的形状适应于电芯组件23的端部与壳体之间的空间的结构，所述第二液囊242在电芯组件上极耳23a的一端，向极耳23a处延伸，用于填充极耳23a与壳体22侧壁之间的空间；所述液囊242在电芯组件23上未设置极耳的一端，用于填充电芯23另一端与壳体22之前的空间。同时，在电芯组件23之间设置的第二液囊242的形状适应于电芯组件23端部之间的空间结构，所述第二液囊242在电芯组件上极耳23a的一端，分别向两侧电芯组件的极耳23a处延伸，用于填充极耳23a、壳体22与电芯组件23之间的空间；所述液囊242在电芯组件23上未设置极耳的一端，分别向电芯组件23两侧延伸，用于填充电芯23另一端与壳体22之间的空间。
根据本申请的一些实施例，可选地，请参考图12，图12为根据本申请一些实施例的电池单体100中液囊24的结构示意图。如图中所示，液囊24还可以包括设于第一液囊241与第二液囊242之间的至少一个缓冲囊 243以及第三薄弱结构253。其中，第一薄弱结构251隔离第一液囊241与缓冲囊243，第三薄弱结构253隔离缓冲囊243与第二液囊242，当缓冲囊243内的压力达到第三阈值时，缓冲囊243内的电解液冲破第三薄弱结构253流入第二液囊242。缓冲囊243可以提供第一液囊241与第二液囊242之间的连接，在第二液囊242处于电芯组件23端部位置区域内时，缓冲囊243的设置尤其有利。此外，利用第一薄弱结构251和第三薄弱结构253隔离在第一液囊241、第二液囊242、缓冲囊243，进一步为电芯组件23提供了阶梯式的膨胀缓冲能力。
根据本申请的一些实施例，可选地，请参考图13，图13为根据本申请一些实施例的电池单体100中液囊24的结构示意图。如图中所示，至少一个缓冲囊243为相互间隔设置的至少一个通道243a，每个通道243a一端设置有第一薄弱结构251，每个通道243a的另一端设置有第三薄弱结构253。将缓冲囊243设置为间隔的至少一个通道243a，可以使得电池单体100能够根据电芯组件23的使用程度和膨胀力变化，冲破不同个数的通道243a，从而可以达到自适应调节释放缓冲空间和内部电解液。从而确保电芯组件23在不同位置和不同工况下的性能趋向一致性水平。
根据本申请的一些实施例，可选地，当缓冲囊243包括多个通道243a时，各个通道243a的体积可以相同，也可以不同。受壳体22内电芯组件23的位置、受力情况、温度环境因素影响，电芯组件23的使用程度和膨胀压力也有不同。相应地配置各个通道243a的体积为相同或不同，使得各通道243a所提供的缓冲空间可以相同或不同，从而使液囊24能够根据不同位置处电芯组件23的使用程度和膨胀压力，提供精细化的膨胀压力调节能力。
根据本申请的一些实施例，可选地，请参考图14，图14为根据本申请一些实施例的电池单体100中液囊24的结构示意图。图14中示出的液囊24中，在所述第一液囊241的两侧分别设置有第二液囊242，所述第一液囊241和第二液囊242之间均设置有第一薄弱结构251，当第一液囊241内的压力达到第一阈值时，第一液囊241内的电解液冲破第一液囊241两侧的第一薄弱结构251，分别从两侧流入第二液囊242中，实现对电芯组件23膨胀力的一级缓冲。通过在所述第一液囊241两侧分别设置第二液囊 242可以在所述第一液囊241内部压力过大时，快速的进行压力的释放，实现对电芯组件23膨胀力的快速缓冲。进一步的，继续参考图14，各所述第二液囊242分别设置有第二薄弱结构252，当第二液囊242内的压力达到第二阈值时，第二液囊242内的电解液冲破第二薄弱结构252流出第二液囊242。通过在第二液囊242上设置第二薄弱结构252，可以方便电解液从第二液囊242上的第二薄弱结构252处流出补充壳体22内的电解液损耗。
根据本申请的一些实施例，可选地，请继续参考图14，在所述第一液囊241和各所述第二液囊242之间分别设置有缓冲囊243及第三薄弱结构253，如图所示，第一薄弱结构251隔离第一液囊241与缓冲囊243，第三薄弱结构253隔离缓冲囊243与第二液囊242，当缓冲囊243内的压力达到第三阈值时，缓冲囊243内的电解液冲破第三薄弱结构253流入第二液囊242。进一步的，继续参考图14，至少一个缓冲囊243为相互间隔设置的至少一个通道243a，每个通道243a一端设置有第一薄弱结构251，每个通道243a的另一端设置有第三薄弱结构253。所述缓冲囊243内部的设置方式可以相同，也可以不同，一端的缓冲囊243内部设置有通道，另一端的缓冲囊243内部可以不设置任何通道，在这里不做限定。本申请实施例通过在所述第一液囊241两端分别设置缓冲囊243，可以很好的适应电芯两端分别都存在空余空间的情况，两端的缓冲囊243可以很好的使所述各第二液囊242设置于电芯的两端。
根据本申请的一些实施例，可选地，在液囊24包含多个第一薄弱结构251时，各个第一薄弱结构251的第一阈值可以相同。随着电芯组件23的使用膨胀，壳体22内的压力会增加并对液囊24产生挤压力，使得液囊24内的压力也相应增加。当液囊24内的压力达到第一阈值时，第一薄弱结构251被液囊24内的电解液冲破，电解液从第一薄弱结构251的破裂处流出液囊24。随着电解液的释放，液囊24内的压力减小，直到与壳体22内的压力达成平衡。将多个第一薄弱结构251各自的第一阈值设置为相同，将使当液囊24内的压力达到第一阈值时，各个第一薄弱结构251同时破裂，电解液同时流出，能够快速缓解电芯组件23的膨胀压力，快速实现对壳体22内电解液的补充。
根据本申请的一些实施例，可选地，在液囊24包含多个第一薄弱结构251时，各个第一薄弱结构251的第一阈值也可以不同。将各个第一薄弱结构251的第一阈值设置为不同，使得各个第一薄弱结构251可以随着电芯组件23的膨胀以及壳体22内压力的增大，阶梯式地、逐步被冲破，实现对电芯组件23膨胀压力的阶梯式缓解，以及电解液的逐步释放，并且可以通过设置各个第一薄弱结构251的具体位置和各个第一阈值的值，实现对膨胀压力缓解能力和电解液补充的精细化调整。
第一薄弱结构251的第一阈值可以在0.1MPa至2.0MPa之间的范围内，该压力范围对应于电池单体100在使用状态下壳体22内的压力范围。
类似地，根据本申请的一些实施例，在液囊24包括第一液囊241和第二液囊242，并且第二液囊242上设有多个第二薄弱结构252时，各个第二薄弱结构252的第二阈值可以相同，或不同。第二薄弱结构252设置于第二液囊242上，第二液囊242在初始状态时内部未盛放电解液。随着电芯组件23的使用膨胀，壳体22内的压力会增加并对第一液囊241产生挤压力，使得液囊241内的压力增加达到第一阈值时，第一薄弱结构251被第一液囊241内的电解液冲破，电解液从第一薄弱结构251的破裂处流出第一液囊241进入第二液囊242，第一液囊24内的压力得到释放并相应减小。随着电芯组件23的进一步膨胀，对第一液囊241和第二液囊242进一步挤压，第二液囊242内的压力达到第二阈值，进入第二液囊242的电解液冲破第二薄弱结构252，并从第二薄弱结构242的破裂处流出第二液囊。将多个第二薄弱结构252的第二阈值设置为相同，可以加快液囊24对电芯组件23的膨胀压力的缓解能力，以及实现对壳体22内电解液的快速补充。将多个第二薄弱结构252的第二阈值设置为不同，则可以通过设置各个第二薄弱结构252的具体位置和各个第二阈值的值，精细调整液囊24的膨胀压力缓冲能力及电解液补充。
同样类似地，第二薄弱结构252的第二阈值也可以在0.1MPa至2.0MPa之间的范围内，该压力范围对应于电池单体100在使用状态下壳体22内的压力范围。
类似地，根据本申请的一些实施例，在液囊24包括多个第三薄弱结构253时，各个第三薄弱结构253的第三阈值也可以相同，或不同。第三 薄弱结构253设置于第二液囊242上，并且间隔在第二液囊242与缓冲囊243之间，第二液囊242和缓冲囊243在初始状态时内部未盛放电解液。随着电芯组件23的使用膨胀，壳体22内的压力会增加并对第一液囊241产生挤压力，使得液囊241内的压力增加达到第一阈值时，第一薄弱结构251被第一液囊241内的电解液冲破，电解液从第一薄弱结构251的破裂处流出第一液囊241进入缓冲囊243，第一液囊24内的压力得到释放并相应减小。随着电芯组件23的进一步膨胀，对第一液囊241和缓冲囊243进一步挤压，缓冲囊243内的压力达到第三阈值，进入缓冲囊243的电解液冲破第三薄弱结构253，并从第三薄弱结构243的破裂处流出缓冲囊，进入第二液囊242。将多个第三薄弱结构253的第三阈值设置为相同，可以加快液囊24对电芯组件23的膨胀压力的缓解能力，以及电解液快速进入第二液囊242。将多个第三薄弱结构253的第三阈值设置为不同，则可以通过设置各个第二阈值的值，精细调整液囊24的膨胀压力缓冲能力。
根据本申请的一些实施例，可选地，各个薄弱结构25可以包括形成在液囊24上的减薄区。例如，在液囊24采用铝塑膜形成的实施例中，可以通过在特定位置处将铝塑膜进行减薄处理，例如通过冲压、融蚀、热封等操作，来获得薄弱结构25，薄弱结构25处具有较液囊24上其他位置更低的压力承受能力，从而当液囊24内的压力增大时，减薄区形成的薄弱结构25更容易被液囊24内的电解液冲破，以使电解液能够从减薄区的破裂处流出液囊24。
根据本申请的一些实施例，可选地，各个薄弱结构25可以由热封工艺和参数的调节弱化热封的强度(可选的参数：封装温度：25～300℃，热风压力：10～500kgf，时间0.001～60s)，形成薄弱结构，也可以在液囊24上设计额外的夹层部。夹层部可以通过将夹层材料设置在液囊24上特定位置处来形成。夹层材料可以为具备尼龙层与CPP(Cast Polypropylene，流延聚丙烯)层的复合夹层，如图15所示，所述夹层材料包括尼龙层a、粘结层b、铝箔层c、保护层d、粘接层e和CPP层f。其中，所述尼龙层a为外保护层，主要为了防止铝箔层c被划伤，起到保护作用，一般为聚乙内酰胺；所述粘结层b用于连接尼龙层a和铝箔层c，一般为粘接类高分子层，比如：聚烯烃类树脂等；所述铝箔层c为支撑层，主要起到密封的 作用；所述保护层d为无机盐功能涂层，可以起到耐电解液腐蚀和耐高温腐蚀的作用；所述粘接层e起到粘接作用，可以为聚烯烃类粘接剂；所述CPP层主要用于起到热封作用，一般为聚丙烯材料。
采用上述尼龙层与CPP层的复合夹层作为夹层部的复合材料，使得夹层部具有较液囊24的其他位置更低的压力承受能力，在从而当液囊24内的压力增大时，CPP层受热粘接形成的薄弱结构25更容易被液囊24内的电解液冲破，以使电解液能够从两片铝塑膜的CPP层处破裂处流出液囊24。
因此，在液囊24包括第一液囊241并且第一液囊241上设有第一薄弱结构251时，第一薄弱结构251可以包括至少一个减薄区，或是至少一个夹层部，或是同时包括至少一个减薄区和至少一个夹层部。相应地，在第二液囊242上设有第二薄弱结构252时，第二薄弱结构252可以包括至少一个减薄区，或是至少一个夹层部，或是同时包括至少一个减薄区和至少一个夹层部。相应地，在液囊24包括缓冲囊243，并且第二液囊242上设有第三薄弱结构253时，第三薄弱结构253也可以包括至少一个减薄区，或是至少一个夹层部，或是同时包括至少一个减薄区和至少一个夹层部。
最后应说明的是：以上各实施例仅用以说明本申请的技术方案，而非对其限制；尽管参照前述各实施例对本申请进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分或者全部技术特征进行等同替换；而这些修改或者替换，并不使相应技术方案的本质脱离本申请各实施例技术方案的范围，其均应涵盖在本申请的权利要求和说明书的范围当中。尤其是，只要不存在结构冲突，各个实施例中所提到的各项技术特征均可以任意方式组合起来。本申请并不局限于文中公开的特定实施例，而是包括落入权利要求的范围内的所有技术方案。

Claims (19)

  1. 一种电池单体，其特征在于，包括：
    壳体，所述壳体内填充电解液；
    至少一个电芯组件，布置于所述壳体内；以及
    至少一个封闭的液囊，盛放有电解液，所述液囊布置于所述壳体内，并至少与所述电芯组件的侧壁对应设置；所述液囊上设有至少一个薄弱结构，当所述液囊内的压力达到阈值时，所述液囊内的所述电解液冲破所述薄弱结构流出所述液囊。
  2. 如权利要求1所述的电池单体，其特征在于，所述侧壁包括位于所述电芯组件的两个端部中间区域的中间侧壁部分，所述液囊与所述中间侧壁部分对应设置。
  3. 如权利要求1至3中任一项所述的电池单体，其特征在于，所述液囊设置在所述电芯组件与所述壳体的侧壁之间，和/或，所述液囊设置在相邻的所述电芯组件之间。
  4. 如权利要求1至3中任一项所述的电池单体，其特征在于，至少一个所述薄弱结构设置在所述液囊的至少部分边缘处。
  5. 如权利要求4所述的电池单体，其特征在于，多个所述薄弱结构间隔设置于所述液囊的至少部分边缘处。
  6. 如权利要求1至5中任一项所述的电池单体，其特征在于，所述电池单体包括在使用状态时的上方端部，至少一个所述薄弱结构位于所述液囊上靠近所述上方端部的位置处。
  7. 如权利要求1至6中任一项所述的电池单体，其特征在于，所述液囊包括至少一个第一液囊和至少一个第二液囊，所述第一液囊盛放有电解液，所述第二液囊未盛放电解液，所述第一液囊与所述第二液囊在初始状态时相互隔离。
  8. 如权利要求7所述的电池单体，其特征在于，所述液囊包括设于所述第一液囊与所述第二液囊之间用于使其相互隔离的第一薄弱结构，当所述第一液囊内的压力达到第一阈值时，所述第一液囊内的所述电解液冲破所述第一薄弱结构，流入所述第二液囊中。
  9. 如权利要求7至8任一项所述的电池单体，其特征在于，所述第二 液囊上还设有第二薄弱结构，当所述第二液囊内的压力达到所述第二阈值时，所述第二液囊内的所述电解液冲破所述第二薄弱结构流出所述第二液囊。
  10. 如权利要求7至9中任一项所述的电池单体，其特征在于，至少一个所述第二液囊位于所述电芯组件的两个端部的区域。
  11. 如权利要求7至10任一项所述的电池单体，其特征在于，所述第二液囊位于所述电芯组件的所述上方端部的未设置极耳的区域内。
  12. 如权利要求7至11中任一项所述的电池单体，其特征在于，所述液囊还包括设于所述第一液囊与所述第二液囊之间的至少一个缓冲囊以及第三薄弱结构，所述第一薄弱结构隔离所述第一液囊与所述缓冲囊，所述第三薄弱结构隔离所述缓冲囊与所述第二液囊，当所述缓冲囊内的压力达到第三阈值时，所述缓冲囊内的所述电解液冲破所述第三薄弱结构流入所述第二液囊。
  13. 如权利要求12所述的电池单体，其特征在于，至少一个所述缓冲囊为相互间隔设置的至少一个通道，每个所述通道一端设置有所述第一薄弱结构，每个所述通道的另一端设置有所述第三薄弱结构。
  14. 如权利要求13所述的电池单体，其特征在于，当所述缓冲囊包括多个所述通道时，各个所述通道的体积相同或不同。
  15. 如权利要求8至14中任一项所述的电池单体，其特征在于，
    当所述液囊包括多个所述第一薄弱结构时，各个所述第一薄弱结构的所述第一阈值相同或不同；和/或
    当所述液囊包括多个所述第二薄弱结构时，各个所述第二薄弱结构的所述第二阈值相同或不同；和/或
    当所述液囊包括多个所述第三薄弱结构时，各个所述第三薄弱结构的所述第三阈值相同或不同。
  16. 如权利要求8至14中任一项所述的电池单体，其特征在于，
    所述第一薄弱结构包括设于所述第一液囊上的至少一个减薄区和/或至少一个夹层部；和/或
    所述第二薄弱结构、所述第三薄弱结构各自独立地包括设于所述第二液囊上的至少一个减薄区和/或至少一个夹层部。
  17. 如权利要求8至16中任一项所述的电池单体，其特征在于，所述第一阈值、所述第二阈值、所述第三阈值各自独立地在0.1MPa至2.0MPa之间。
  18. 一种电池，其特征在于，包括：如权利要求1至17中任一项所述的电池单体。
  19. 一种用电装置，其特征在于，所述用电装置包括如权利要求18所述的电池，所述电池用于提供电能。
PCT/CN2021/106111 2021-07-13 2021-07-13 电池单体、电池及用电装置 WO2023283808A1 (zh)

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