WO2025060008A1 - 电池单体、电池和用电装置 - Google Patents

电池单体、电池和用电装置 Download PDF

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Publication number
WO2025060008A1
WO2025060008A1 PCT/CN2023/120508 CN2023120508W WO2025060008A1 WO 2025060008 A1 WO2025060008 A1 WO 2025060008A1 CN 2023120508 W CN2023120508 W CN 2023120508W WO 2025060008 A1 WO2025060008 A1 WO 2025060008A1
Authority
WO
WIPO (PCT)
Prior art keywords
electrode assembly
elastic buffer
buffer pad
battery cell
optionally
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.)
Ceased
Application number
PCT/CN2023/120508
Other languages
English (en)
French (fr)
Inventor
林晨辉
何建福
叶永煌
金海族
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.)
Contemporary Amperex Technology Co Ltd
Original Assignee
Contemporary Amperex Technology Co 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 Contemporary Amperex Technology Co Ltd filed Critical Contemporary Amperex Technology Co Ltd
Priority to PCT/CN2023/120508 priority Critical patent/WO2025060008A1/zh
Priority to EP23952664.3A priority patent/EP4756945A1/en
Publication of WO2025060008A1 publication Critical patent/WO2025060008A1/zh
Priority to US19/536,609 priority patent/US20260180007A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • 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
    • H01M10/04—Construction or manufacture in general
    • H01M10/0468—Compression means for stacks of electrodes and separators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings; Jackets or wrappings
    • H01M50/102—Primary casings; Jackets or wrappings characterised by their shape or physical structure
    • H01M50/103—Primary casings; Jackets or wrappings characterised by their shape or physical structure prismatic or rectangular
    • 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
    • H01M50/116—Primary casings; Jackets or wrappings characterised by the material
    • H01M50/121—Organic material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/471—Spacing elements inside cells other than separators, membranes or diaphragms; Manufacturing processes thereof
    • H01M50/474—Spacing elements inside cells other than separators, membranes or diaphragms; Manufacturing processes thereof characterised by their position inside the 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
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/471—Spacing elements inside cells other than separators, membranes or diaphragms; Manufacturing processes thereof
    • H01M50/48—Spacing elements inside cells other than separators, membranes or diaphragms; Manufacturing processes thereof characterised by the material
    • H01M50/486—Organic material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • 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 belongs to the field of battery technology, and specifically, relates to battery cells, batteries and electrical devices.
  • batteries are widely used in various fields. Take lithium-ion batteries as an example. They are green, environmentally friendly, high-energy, and low-carbon. They are not only used in energy storage power systems such as hydropower, thermal, wind, and solar power stations, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, electric cars, and ships, as well as military equipment and aerospace and other fields. With the development of the current society, people's requirements for batteries are getting higher and higher.
  • the present application provides a battery cell, which aims to improve the effect of the buffer pad and improve the uniformity of the force on the electrode during the charging and discharging process.
  • the first aspect of the present application provides a battery cell, which includes:
  • the electrode assembly being disposed within the housing;
  • At least one elastic buffer pad is arranged on at least a portion of the surface of the electrode assembly and/or inside the electrode assembly, and the compression rate of the elastic buffer pad along the thickness direction under a pressure of 0.1 MPa is ⁇ 30%, and the compression rate along the thickness direction under a pressure of 1 MPa is ⁇ 50%.
  • the battery cell of the first aspect of the present application has the following beneficial effects: on the one hand, it can buffer the volume expansion force generated by the electrode assembly during charging, discharging and use, and inhibit the deformation of the battery cell; on the other hand, it can make the elastic buffer pad provide different strengths and stresses in different charging and discharging processes.
  • the elastic buffer pad In the early stage of charging or use, the elastic buffer pad is not over-compressed, and can provide a certain support strength, which is conducive to the direct bonding of the electrode assembly with the inner wall of the shell or the bonding of the elastic buffer pad with the inner wall of the shell, to achieve the interaction force and improve the force uniformity of the pole piece.
  • the elastic buffer pad can be fully compressed during the expansion of the electrode assembly, and the space in the thickness direction is transferred to the electrode assembly, reducing the expansion force of the electrode assembly, and providing a larger stress, while reducing the expansion force of the electrode assembly, improving the force uniformity of the pole piece during the charging and discharging process.
  • the elastic buffer pad can play a better effect, while improving the volume stability of the battery cell during long-term use, it is also conducive to maintaining the force uniformity of the pole piece during the charging and discharging process, thereby helping to reduce the risk of expansion deformation or performance deterioration of the battery cell and improve the long-term use performance.
  • the elastic buffer pad is provided between the electrode assembly and the housing, and/or the elastic buffer pad is provided between two adjacent electrode assemblies. Meeting the given conditions is conducive to improving the volume stability of the battery cell during long-term use.
  • the compression rate of the elastic buffer pad along its thickness direction under a pressure of 0.1Mpa is ⁇ 20%, and optionally ⁇ 10%; and/or the compression rate of the elastic buffer pad along its thickness direction under a pressure of 1Mpa is ⁇ 60%, and optionally ⁇ 80%. Meeting the given conditions is conducive to further improving the force uniformity of the pole piece during the charging and discharging process.
  • the compression rate of the elastic buffer pad under a pressure of 0.5 MPa is 30% to 60%. Meeting the given conditions is conducive to improving the volume stability of the battery cell and further improving the force uniformity of the pole piece during the charging and discharging process.
  • the electrode assembly is a wound electrode assembly and includes a straight portion and a corner portion, and the elastic buffer pad is provided on at least a portion of the surface of the straight portion and/or the corner portion.
  • the battery cell is a prismatic battery cell.
  • the prismatic battery cell includes: at least one first elastic buffer pad and/or at least one The second elastic buffer pad, the first elastic buffer pad and the electrode assembly are stacked along the thickness direction of the battery cell, and/or the second elastic buffer pad and the electrode assembly are stacked along the length direction of the battery cell. Meeting the given conditions is conducive to reducing the expansion force generated by the electrode assembly during use.
  • the prismatic battery cell satisfies at least one of the following conditions: in the thickness direction of the battery cell, the sum of the total thickness of the first elastic buffer pad in the free state and the total thickness of the electrode assembly in the fully discharged state is 80% to 99% of the distance between the inner walls of the shell, which can be optionally 85% to 98%, and further optionally 90% to 95%; in the thickness direction of the battery cell, the sum of the total thickness of the first elastic buffer pad in the free state and the total thickness of the electrode assembly in the fully charged state is 95% to 110% of the distance between the inner walls of the shell, which can be optionally 98% ⁇ 105%, and can be further selected as 99% ⁇ 102%; in the length direction of the battery cell, the sum of the total thickness of the second elastic buffer pad in the free state and the length of the electrode assembly in the fully discharged state is 80% ⁇ 99% of the distance between the inner walls of the shell, can be further selected as 85% ⁇ 98%, and can be further selected as 90% ⁇
  • the ratio of the total thickness of the first elastic buffer pad in a free state to the total thickness of the electrode assembly in a fully discharged state is 2% to 25%, optionally 5% to 20%, and further optionally 8% to 15%. Meeting the given conditions is conducive to maintaining the volume stability of the battery cell and taking into account the energy density of the battery cell.
  • the ratio of the extension distance of the first elastic buffer in the length direction of the electrode assembly to the length of the electrode assembly in a free state is 0.8 to 1.2, optionally 0.85 to 1.1, and further optionally 0.9 to 1.05; and/or the ratio of the extension distance of the first elastic buffer in the height direction of the electrode assembly to the height of the electrode assembly in a free state is 0.8 to 1.2, optionally 0.85 to 1.1, and further optionally 0.9 to 1.05.
  • Meeting the given conditions is conducive to enabling the elastic buffer to cover most areas of the electrode assembly, which is conducive to improving the volume stability of the battery cell and further improving the force uniformity of the pole piece.
  • the orthographic projection of the first elastic buffer pad on the electrode assembly is located in the region where the electrode assembly is located. Meeting the given conditions is not only conducive to the smooth insertion of the elastic buffer pad into the shell during assembly, but also conducive to further taking into account the energy density of the battery.
  • the battery cell is a cylindrical battery cell
  • at least one of the elastic buffer pads and the electrode assembly are stacked along the radial direction of the electrode assembly, and the distance between the inner wall surfaces of the shell is equal to the diameter of the inner cavity of the shell.
  • the thickness of a single elastic buffer pad in a free state is 2% to 15%, and optionally 5% to 10%, of the thickness of a single electrode assembly in a fully discharged state.
  • Meeting the given conditions is beneficial to maintaining the volume stability of the battery cell during its service life, especially in the later period of use, and can also take into account the energy density of the battery cell.
  • the second aspect of the present application provides a battery, which includes: the battery cell described in the first aspect of the present application.
  • FIG. 1 is a schematic cross-sectional view of a prismatic battery cell according to one embodiment of the present application.
  • FIG. 2 is a schematic cross-sectional view of a prismatic battery cell according to another embodiment of the present application.
  • FIG. 3 is a schematic cross-sectional view of a prismatic battery cell according to another embodiment of the present application.
  • FIG. 4 is a schematic cross-sectional view of a prismatic battery cell according to yet another embodiment of the present application.
  • FIG. 5 is a schematic cross-sectional view of a prismatic battery cell according to yet another embodiment of the present application.
  • FIG. 6 is a schematic cross-sectional view of a prismatic battery cell according to yet another embodiment of the present application.
  • FIG. 7 is a schematic cross-sectional view of a prismatic battery cell according to yet another embodiment of the present application.
  • FIG. 8 is a schematic cross-sectional structure diagram of a prismatic battery cell according to yet another embodiment of the present application.
  • FIG. 9 is a schematic cross-sectional structure diagram of a cylindrical battery cell according to one embodiment of the present application.
  • FIG. 10 is a schematic cross-sectional view of a cylindrical battery cell according to another embodiment of the present application.
  • FIG. 11 is a schematic structural diagram of a battery cell according to an embodiment of the present application.
  • FIG. 12 is a schematic structural diagram of a battery module according to an embodiment of the present application.
  • FIG. 13 is a schematic diagram of the structure of a battery pack according to an embodiment of the present application.
  • FIG. 14 is an exploded view of a battery pack according to an embodiment of the present application.
  • FIG. 15 is a schematic diagram of an implementation of an electric device using a battery as a power source according to an embodiment of the present application.
  • range disclosed in the present application is defined in the form of a lower limit and/or an upper limit, and a given range is defined by selecting a lower limit and/or an upper limit, and the selected lower limit and/or upper limit define the boundaries of a particular range.
  • the range defined in this way can be inclusive or exclusive of end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form an unambiguous range, and any lower limit can be combined with other lower limits to form an unambiguous range, and any upper limit can be combined with any other upper limit to form an unambiguous range.
  • each individually disclosed point or single value itself can be combined with any other point or single value as a lower limit or upper limit or with other lower limits or upper limits to form an unambiguous range.
  • a range of 60 to 120 and 80 to 110 is listed for a particular parameter, it is understood that the range of 60 to 110 and 80 to 120 is also expected.
  • the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4 and 5 are listed, the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5.
  • the numerical range "a-b" represents any combination of real numbers between a and b. Abbreviation, where a and b are both real numbers.
  • the method includes steps S1 and S2, which means that the method may include steps S1 and S2 performed sequentially, or may include steps S2 and S1 performed sequentially.
  • the method may also include step S3, which means that step S3 may be added to the method in any order.
  • the method may include steps S1, S2 and S3, or may include steps S1, S3 and S2, or may include steps S3, S1 and S2, etc.
  • the “include” and “comprising” mentioned in this application represent open-ended or closed-ended expressions.
  • the “include” and “comprising” may represent that other components not listed may also be included or only the listed components may be included or only the listed components may be included.
  • the term "or” is inclusive.
  • the phrase “A or B” means “A, B, or both A and B”. More specifically, any of the following conditions satisfies the condition "A or B”: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).
  • lithium-ion batteries will be accompanied by volume changes during charge and discharge cycles, overcharging, etc., and as the working time increases, the amount of expansion gradually increases. This not only easily causes the battery shell to deform under the extrusion force, affecting the volume stability of the battery, but also if the pole piece expands excessively during the charge and discharge cycle of the battery, it may also affect the distance between the pole piece and the diaphragm, increase the risk of lithium plating, and affect the service life of the battery.
  • an elastic buffer pad with a compression rate of ⁇ 30% along its thickness direction under a pressure of 0.1Mpa and a compression rate of ⁇ 50% along its thickness direction under a pressure of 1Mpa is selected, so that the elastic buffer pad can provide different strengths and stresses during the charging process.
  • the elastic buffer pad In the early stage of use or charging of the battery cell, the elastic buffer pad is not over-compressed and can provide a certain support strength, which is conducive to the direct bonding of the electrode assembly with the inner wall of the shell or the bonding of the electrode assembly with the inner wall of the shell through the elastic buffer pad, thereby improving the force uniformity of the electrode piece.
  • the elastic buffer pad In the later stage of charging or the later stage of use of the battery cell, the elastic buffer pad can be fully compressed during the expansion of the electrode assembly, transferring its space in the thickness direction to the electrode assembly and providing a larger stress, thereby reducing the expansion force of the electrode assembly. At the same time, it is beneficial to maintain the uniformity of force on the electrode during the charging and discharging process.
  • the battery cells and batteries disclosed in the embodiments of the present application can be used in electrical devices that use batteries as power sources or various energy storage systems that use batteries as energy storage elements.
  • Electrical devices may include, but are not limited to, mobile phones, tablets, laptops, electric toys, electric tools, battery cars, electric cars, ships, spacecraft, etc.
  • electric toys may include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc.
  • spacecraft may include airplanes, rockets, space shuttles, and spacecraft, etc.
  • the first aspect of the present application provides a battery cell, which includes: a shell; at least one electrode assembly, which is placed in the shell; at least one elastic buffer pad, which is arranged on at least a portion of the surface of the electrode assembly and/or inside the electrode assembly, and the compression rate of the elastic buffer pad along the thickness direction under a pressure of 0.1 MPa is ⁇ 30%, and the compression rate along the thickness direction under a pressure of 1 MPa is ⁇ 50%.
  • the battery cell 1 of the first aspect of the present application includes a housing 11, at least one electrode assembly 12, and at least one elastic buffer pad 13.
  • the electrode assembly 12 is placed in the housing 11, and the elastic buffer pad 13 can be provided on at least a portion of the surface of the electrode assembly 12 and/or inside the electrode assembly 12.
  • the elastic buffer pad 13 can be provided between the electrode assembly 12 and the housing 11 (for understanding with reference to FIG. 1 ), and/or between two adjacent electrode assemblies 12 (for understanding with reference to FIG. 2 ), and/or inside the electrode assembly (for understanding with reference to FIG. 3 ).
  • the elastic buffer pad 13 can be arranged between the electrode assembly 12 and the shell 11, which can be understood as being arranged in at least one of the areas between the electrode assembly 12 and the side wall of the shell 11, between the electrode assembly 12 and the bottom wall of the shell 11, and between the electrode assembly 12 and the top wall of the shell 11.
  • the elastic buffer pad 13 can be arranged between the electrode assembly 12 and the shell 11 and between two adjacent electrode assemblies at the same time; and optionally, referring to FIG. 1, FIG. 6, and FIG. 7, the elastic buffer pad 13 can be arranged between the electrode assembly 12 and the side wall of the shell 11.
  • both sides of the elastic buffer pad 13 along the thickness direction thereof can be arranged in affixed with the electrode assembly 12 (refer to FIG. 2 for understanding), or one side can be arranged in affixed with the electrode assembly 12, and the other side can be arranged in affixed with the inner wall of the shell 11.
  • the number of the elastic buffer pads 13 may be one or more, and they may be arranged between the electrode assembly 12 and the shell 11, or inside the electrode assembly, and optionally, they may be arranged between the electrode assembly 12 and the side wall of the shell 11.
  • the number of the elastic buffer pads 13 may be one or more, and the one or more elastic buffer pads 13 may be arranged only between the battery assemblies 12, or only between the battery assembly 12 and the shell 11, or only inside the electrode assembly 12, or partially between the battery assemblies 12, partially between the battery assembly 12 and the shell 11, and so on.
  • the elastic buffer pad 13 arranged between the battery assembly 12 and the shell 11 may be arranged between the electrode assembly 12 and the side wall of the shell 11.
  • the thickness direction of at least one elastic buffer pad 13 is the same as the thickness direction of the battery cell 1 (refer to Figures 1 to 6 and 8 for understanding), and further optionally, the thickness direction of at least one elastic buffer pad 13 is the same as the thickness direction of the battery cell 1 and the electrode assembly 12.
  • the first direction can be the thickness direction of the electrode assembly 12.
  • the first direction can be the thickness direction of the straight portion.
  • the electrode assembly 12 is cylindrical, the first direction is the radial direction of the electrode assembly, and the distance between the inner wall surfaces of the shell 11 along the first direction is the inner cavity diameter of the shell.
  • the deformation and expansion force generated by the electrode assembly will also increase, and as the number of cycles increases, the expansion amount and expansion force generated by the electrode assembly during the charge and discharge process usually also increase, that is, the expansion amount and expansion force generated by the electrode assembly during the charge and discharge process in the later stage of the battery's service life are usually greater than those in the early stage of the battery's service life.
  • an elastic buffer pad is selected with a compression rate along its thickness direction under a pressure of 0.1 MPa of ⁇ 30% (such as ⁇ 30%, ⁇ 28%, ⁇ 25%, ⁇ 22%, ⁇ 20%, ⁇ 18%, ⁇ 16%, ⁇ 14%, ⁇ 12%, ⁇ 10%, ⁇ 8%, ⁇ 6%, ⁇ 4%, etc., or it can be a range composed of any of the above values), and a compression rate along its thickness direction under a pressure of 1 MPa of ⁇ 50% (such as ⁇ 50%, ⁇ 55%, ⁇ 60%, ⁇ 65%, ⁇ 70%, ⁇ 75%, ⁇ 80%, ⁇ 85%, etc., or it can be a range composed of any of the above values).
  • the elastic buffer pad can provide different strengths and stresses in different charging and discharging processes.
  • the elastic buffer pad In the early stage of charging or the early stage of battery cell use, the elastic buffer pad is not over-compressed and can provide a certain supporting strength, which is conducive to the direct bonding of the electrode assembly with the inner wall of the shell or the bonding of the elastic buffer pad with the inner wall of the shell to achieve mutual force, improve the force uniformity of the pole piece, reduce the risk of wrinkles in the local area of the electrode assembly and the occurrence of purple spots and lithium precipitation in the wrinkled area, which may cause the utilization rate of active lithium to decrease; and in the late stage of charging or the late stage of battery cell cycle, the elastic buffer pad It can be fully compressed during the expansion process of the electrode assembly, transferring its space in the thickness direction to the electrode assembly, reducing the expansion force of the electrode assembly, and providing greater stress. While reducing the expansion force of the electrode assembly, it improves and maintains the uniformity of force on the electrode during the charging and discharging process.
  • the compression rate of the elastic buffer pad along its thickness direction under different stresses can be carried out with reference to GB/T 1041-92.
  • the compression rate of the elastic buffer pad along its thickness direction is the ratio of the thickness change of the elastic buffer pad in the free state and in the stress state to the thickness in the free state.
  • the free state of the elastic buffer pad refers to the state in which the elastic buffer pad is not subjected to any external force
  • the stress state of the elastic buffer pad refers to the state in which the elastic buffer pad is subjected to a certain compressive stress.
  • the thickness test of the elastic buffer pad in the free state can be tested by conventional instruments and conventional methods in the field, such as Mitutoyo ID-C112MX micrometer thickness gauge (or similar instrument), and the test can be carried out under the state where the test force is less than or equal to 1.8N, and multiple points (such as 5, 10, etc.) are randomly measured to obtain the average value.
  • the thickness test of the elastic buffer pad under stress state can be carried out by using two parallel plates, so that the elastic buffer pad is located in the middle of the plates, and the plates are used to apply a preset pressure to the elastic buffer pad and measure the distance between the plates.
  • the instruments used to measure the distance between the plates may include but are not limited to conventional instruments such as vernier calipers.
  • the battery cell of the first aspect of the present application has the following beneficial effects: it can enable the elastic buffer pad to play a better effect, while improving the volume stability of the battery cell during long-term use, it is also beneficial to maintain the uniformity of force on the electrode during the charging and discharging process, thereby helping to reduce the risk of expansion and deformation or performance deterioration of the battery cell and improve long-term performance.
  • battery cells include but are not limited to shells, electrode assemblies and elastic buffer pads.
  • battery cells may also include electrolytes; in the embodiments of the present application, battery cells include but are not limited to secondary battery cells, primary battery cells, etc.; in the embodiments of the present application, battery cells include but are not limited to lithium-ion battery cells, sodium-ion battery cells, magnesium-ion battery cells, etc.; in the embodiments of the present application, battery cells include but are not limited to hard battery cells, soft-pack battery cells, etc., and hard battery cells include but are not limited to metal battery shell cells, etc.
  • the battery cell of the first aspect of the present application can further improve the performance of the battery cell by further controlling the compression rate of the elastic buffer pad along its thickness direction under a specific stress, the relationship between the elastic buffer pad and the electrode assembly and/or the shell size, the arrangement mode for different battery cell types, etc. on the basis of satisfying the above conditions. That is, on the basis of satisfying the above conditions, one or more of the following conditions can be optionally satisfied.
  • an elastic buffer pad 13 is provided between the electrode assembly 12 and the shell 11, and/or an elastic buffer pad 13 is provided between two adjacent electrode assemblies 12.
  • Meeting the given conditions is further conducive to improving the volume stability of the battery cell during long-term use and reducing the risk of expansion deformation or performance deterioration.
  • an elastic buffer pad 13 can be provided only between the electrode assembly 12 and the shell 11 and/or between two adjacent electrode assemblies 12, which is beneficial to the molding of the electrode assembly and also helps to reduce the expansion force generated by the electrode assembly on the shell.
  • the compression rate of the elastic buffer pad 13 along its thickness direction under a pressure of 0.1Mpa can be ⁇ 20%, and can be ⁇ 10%. Selecting an elastic buffer pad that further meets the given conditions is conducive to further preventing the elastic buffer pad from being over-compressed at the initial stage of battery cell charging, can provide a certain support strength, and is conducive to achieving direct bonding of the electrode assembly with the inner wall of the shell or bonding with the inner wall of the shell through the elastic buffer pad, achieving mutual force, and improving the force uniformity of the pole piece.
  • the compression rate of the elastic buffer pad 13 along its thickness direction under a pressure of 1Mpa can be ⁇ 60%, and can be ⁇ 80%. Selecting an elastic buffer pad that further meets the given conditions is beneficial in that in the late stage of charging or the late stage of battery cell cycle, the elastic buffer pad can be fully compressed during the expansion of the electrode assembly, and the space in its thickness direction is transferred to the electrode assembly, thereby reducing the expansion force of the electrode assembly and providing greater stress, which is beneficial to reducing the expansion force of the electrode assembly, improving the volume stability of the battery cell, and maintaining the force uniformity of the electrode sheet during the charging and discharging process.
  • the compression rate of the elastic buffer pad 13 under a pressure of 0.5 MPa may be 30% to 60%.
  • the compression rate of the elastic buffer pad 13 under a pressure of 0.5 MPa can be 30%, 35%, 40%, 45%, 50%, 55%, 60%, etc., or can be a range composed of any of the above values.
  • Selecting an elastic buffer pad that further meets the given conditions is further conducive to the elastic buffer pad being able to provide different strengths and stresses in different charging and discharging processes, and is conducive to further improving the volume stability of the battery cell while further maintaining the force uniformity of the pole piece during the charging and discharging process.
  • the electrode assembly 12 may be a wound electrode assembly and include a straight portion and a corner portion, and the elastic buffer pad 13 may be disposed on at least a portion of the surface of the straight portion and/or the corner portion.
  • the electrode assembly can be a laminated electrode assembly or a wound electrode assembly; the wound electrode assembly can be used in a prismatic shell or a cylindrical shell.
  • the risk of uneven force on the pole piece is relatively high, especially for a prismatic battery cell with a wound electrode assembly.
  • Combining the wound electrode assembly with an elastic buffer pad is conducive to alleviating the problem of uneven force on the pole piece in the wound electrode assembly, reducing polarization differences, and improving volume stability and long-term cycle performance.
  • the electrode assembly 12 can be a wound electrode assembly, and includes a straight portion and a corner portion, and the elastic buffer pad 13 can be provided on at least part of the surface of the straight portion and/or the corner portion, thereby helping to further alleviate the problem of uneven force on the pole piece in the prismatic battery cell.
  • prismatic battery cells include but are not limited to square battery cells.
  • the straight portion of the wound electrode assembly can be provided with an elastic buffer pad 13.
  • the battery cell 1 may be a prismatic battery cell.
  • a prismatic battery cell may include: at least one first elastic buffer pad 13a and/or at least one second elastic buffer pad 13b, the first elastic buffer pad 13a and the electrode assembly 12 may be stacked along the thickness direction of the battery cell, and/or the second elastic buffer pad 13b and the electrode assembly 12 may be stacked along the length direction of the battery cell.
  • the thickness of the first elastic buffer pad 13a can extend along the thickness direction of the battery cell, and/or the thickness of the second elastic buffer pad 13b can extend along the length direction of the battery cell.
  • the provision of the first elastic buffer pad 13a and the second elastic buffer pad 13b are both beneficial to reducing the expansion force generated by the electrode assembly during use.
  • the square battery cell may include at least one first elastic buffer pad 13a.
  • the area of the two side walls arranged opposite to each other in the thickness direction of the battery cell is usually large.
  • the first elastic buffer pad is provided between the two side walls, which is beneficial to increase the contact area between the elastic buffer pad and the electrode assembly, thereby not only facilitating further reducing the expansion force that may be generated by the electrode assembly during use, but also facilitating further alleviating the problem of uneven force that may exist on the pole pieces in the wound electrode assembly.
  • the prismatic battery cell may only include the first elastic buffer pad 13a. Meeting the given conditions is beneficial to reducing the expansion force of the electrode assembly and improving the problem of uneven force on the pole piece.
  • omitting the provision of the second elastic buffer pad is beneficial to simplifying the battery cell structure and improving the energy density of the battery cell.
  • the sum of the total thickness of the first elastic buffer pad 13a in a free state and the total thickness of the electrode assembly 12 in a fully discharged state may be 80% to 99% of the distance between the inner walls of the shell 11, optionally 85% to 98%, and further optionally 90% to 95%; and/or, the sum of the total thickness of the first elastic buffer pad 13a in a free state and the total thickness of the electrode assembly 12 in a fully charged state may be 95% to 110% of the distance between the inner walls of the shell 11, optionally 98% to 105%, and further optionally 99% to 102%.
  • a square battery cell can be taken as an example, the sum of the total thickness d of the first elastic buffer pad 13a in a free state and the total thickness d2 of the electrode assembly 12 in a fully discharged state can be 80% to 99% of the distance d0 between the two inner wall surfaces of the shell 11 oppositely arranged along the thickness direction thereof, that is, For example, The value of can be 80%, 82%, 85%, 87%, 89%, 91%, 95%, 97%, 99%, etc., or can be a range consisting of any of the above values.
  • the fully discharged state refers to the state of discharging to the lower limit of the cut-off voltage at a constant current of 0.33C of the rated capacity of the battery cell at room temperature.
  • Meeting the given conditions can allow a gap to exist between the elastic buffer pad and the electrode assembly before entering the shell, which is conducive to the smooth entry of the elastic buffer pad and the electrode assembly into the shell and facilitates the assembly of the battery cell.
  • Meeting the given conditions is further conducive to the smooth insertion of the elastic buffer pad and the electrode assembly into the shell.
  • it is also conducive to achieving direct or indirect contact between the electrode assembly and the inner wall of the shell after charging, thereby improving the uniformity of force on the pole piece.
  • the sum of the total thickness d of the first elastic buffer pad 13a in a free state and the total thickness d1 of the electrode assembly 12 in a fully charged state can be 95% to 110% of the distance d0 between the two inner wall surfaces of the shell 11 oppositely arranged along the thickness direction thereof, that is,
  • the value may be 95%, 97%, 99%, 100%, 102%, 104%, 106%, 108%, 110%, etc., or may be a range consisting of any of the above values.
  • the fully charged state refers to a state where the battery cell is charged at room temperature with a constant current of 0.33C of the rated capacity of the battery cell to the upper limit of the cut-off voltage, and then charged at a constant voltage until the current is 0.05C, or the battery is charged under this condition until the SOC no longer changes.
  • Meeting the given conditions is further beneficial for the battery cell to directly fit the electrode assembly to the inner wall of the shell or to fit the electrode assembly to the inner wall of the shell through an elastic buffer pad (or mylar film, i.e., insulating film) during use, to achieve mutual force, which is beneficial to further improve the force uniformity of the pole piece, reduce the generation of wrinkles in local areas of the electrode assembly, and reduce the occurrence of purple spots and lithium precipitation in the wrinkled area.
  • the risk of abnormally causing a decrease in the utilization rate of active lithium is improved to improve the capacity retention rate of the battery cell.
  • Meeting the given conditions can improve the uniformity of force on the pole piece while further reducing the expansion force that the electrode assembly may generate on the shell.
  • Meeting the given conditions is not only beneficial to the assembly of battery cells, but also beneficial to improving the volume stability of the battery cells and the force uniformity of the pole pieces, thereby helping to reduce the risk of expansion and deformation or performance deterioration of the battery cells.
  • the sum of the total thickness of the second elastic buffer pad 13b in the free state and the length of the electrode assembly 12 in the fully discharged state can be 80% to 99% of the distance between the inner wall surfaces of the shell 11, optionally 85% to 98%, and further optionally 90% to 95%; and/or, the sum of the total thickness of the second elastic buffer pad 13b in the free state and the length of the electrode assembly 12 in the fully charged state can be 85% to 110% of the distance between the inner wall surfaces of the shell 11, optionally 98% to 105%, and further optionally 99% to 102%.
  • the sum of the total thickness of the second elastic buffer pad 13b in a free state and the length of the electrode assembly 12 in a fully discharged state can be 80%, 82%, 85%, 87%, 89%, 91%, 95%, 97%, 99% of the distance between the two inner wall surfaces of the shell 11 arranged opposite to each other along its length direction, or can be a range composed of any of the above values.
  • the length direction of the electrode assembly 12 in a fully discharged state and the length direction of the inner cavity of the shell are shown in FIG8.
  • the length of the electrode assembly 12 can be the maximum extension distance in the length direction of the battery cell.
  • the elastic buffer pad and the electrode assembly before entering the shell, which is conducive to the smooth entry of the elastic buffer pad and the electrode assembly into the shell and facilitates the assembly of the battery cell.
  • the sum of the total thickness of the second elastic buffer pad 13b in the free state and the length of the electrode assembly 12 in the fully discharged state can be 85% to 98% of the distance between the two inner wall surfaces of the shell 11 arranged opposite to each other along its length direction, and can be further optionally 90% to 95%.
  • Meeting the given conditions is further conducive to the smooth insertion of the elastic buffer pad and the electrode assembly into the shell. At the same time, it is also conducive to achieving direct or indirect contact between the electrode assembly and the inner wall of the shell after charging, thereby improving the uniformity of force on the electrode piece.
  • the sum of the total thickness of the second elastic buffer pad 13b in a free state and the length of the electrode assembly 12 in a fully charged state can be 95%, 97%, 99%, 100%, 102%, 104%, 106%, 108%, 110%, etc. of the distance between the two inner wall surfaces of the shell 11 oppositely arranged along its length direction, or can be a range composed of any of the above values.
  • Meeting the given conditions is further conducive to making the electrode assembly directly fit with the inner wall of the shell or fit with the inner wall of the shell through the elastic buffer pad (or mylar film) during use to achieve mutual force, which is conducive to further improving the force uniformity of the pole piece, reducing the risk of wrinkles in the local area of the electrode assembly and the occurrence of purple spots and lithium precipitation in the wrinkled area, which leads to a decrease in the utilization rate of active lithium, and improving the capacity retention rate of the battery cell.
  • the sum of the total thickness of the second elastic buffer pad 13b in the free state and the length of the electrode assembly 12 in the fully charged state can be 98% to 105% of the distance between the two inner wall surfaces of the shell 11 arranged opposite to each other along its length direction, and can be further selected to be 99% to 102%.
  • Meeting the given conditions can improve the uniformity of the force on the electrode piece while further reducing the expansion force that the electrode assembly may generate on the shell.
  • Meeting the given conditions is not only beneficial to the assembly of battery cells, but also beneficial to improving the volume stability of the battery cells and the force uniformity of the pole pieces, thereby helping to reduce the risk of expansion and deformation or performance deterioration of the battery cells.
  • the ratio of the total thickness of the first elastic buffer pad 13a in the free state to the total thickness of the electrode assembly 12 in the fully discharged state can be 2% to 25%, optionally 5% to 20%, and further optionally 8% to 15%.
  • the ratio of the total thickness d of the first elastic buffer pad 13a in the free state to the total thickness d2 of the electrode assembly 12 in the fully discharged state can be 2% to 25%, that is, 2% ⁇ d/ d2 ⁇ 25%.
  • the value of d/ d2 can be 2%, 3%, 5%, 7%, 9%, 11%, 13%, 15%, 17%, 19%, 21%, 23%, 25%, etc., or can be a range composed of any of the above values.
  • d/ d2 is conducive to improving the elastic buffer pad's ability to absorb the expansion deformation and expansion force generated by the electrode assembly, and is conducive to further suppressing the expansion deformation of the battery cell.
  • the value of d/ d2 meets the given conditions, which is conducive to maintaining the volume stability of the battery cell during the service cycle, especially in the later period of use, and can also take into account the energy density of the battery cell.
  • the value of d/ d2 can be 5% to 20%, and can be optionally 8% to 15%. Meeting the given conditions is conducive to further taking into account the volume stability and energy density of the battery cell during the service cycle, especially in the later period of use.
  • Meeting the given conditions is beneficial to maintaining the volume stability of the battery cell while taking into account the energy density of the battery cell.
  • the first elastic buffer pad 13a is extended in the length direction of the electrode assembly 12 in a free state.
  • the ratio of the extension distance to the length of the electrode assembly 12 can be 0.8 to 1.2, optionally 0.85 to 1.1, and further optionally 0.9 to 1.05; and/or, in the free state, the ratio of the extension distance of the first elastic buffer pad 13a in the height direction of the electrode assembly 12 to the height of the electrode assembly 12 can be 0.8 to 1.2, optionally 0.85 to 1.1, and further optionally 0.9 to 1.05.
  • the ratio of the extension distance of the first elastic buffer pad 13a in the length direction of the electrode assembly 12 in the free state to the length of the electrode assembly 12 can be 0.8, 0.85, 0.9, 0.95, 1, 1.05, 1.1, 1.15, 1.2, etc., or can be a range consisting of any of the above values.
  • the length of the electrode assembly refers to the maximum extension distance of the electrode assembly along the length direction of the battery cell in the fully charged state, and the length of the electrode assembly and the extension distance of the first elastic buffer pad in the length direction of the electrode assembly in the free state can be measured by conventional methods and conventional instruments.
  • the ratio of the extension distance of the first elastic buffer pad 13a in the free state in the height direction of the electrode assembly 12 to the height of the electrode assembly 12 can be 0.8 to 1.2, 0.8, 0.85, 0.9, 0.95, 1, 1.05, 1.1, 1.15, 1.2, etc., or can be a range composed of any of the above values.
  • the height of the electrode assembly refers to the maximum extension distance of the electrode assembly in the height direction of the battery cell in the fully charged state, and the height of the electrode assembly and the extension distance of the first elastic buffer pad in the free state in the height direction of the electrode assembly can be measured by conventional methods and conventional instruments.
  • the dimensions of the first elastic buffer pad and the electrode assembly meet the given conditions, which is conducive to the elastic buffer pad covering most areas of the electrode assembly, which is conducive to improving the volume stability of the battery cell, further improving the force uniformity of the pole piece, and reducing the risk of deterioration of battery cell performance.
  • the orthographic projection of the first elastic buffer 13a on the electrode assembly 12 can be located in the area where the electrode assembly 12 is located.
  • the first elastic buffer meets the given conditions, which is not only conducive to the smooth insertion of the elastic buffer into the shell during the assembly process, but also conducive to further considering the energy density of the battery.
  • the battery cell 1 can be a cylindrical battery cell, at least one elastic buffer pad 13 and the electrode assembly 12 are stacked along the radial direction of the electrode assembly 12, and the distance between the inner wall surfaces of the shell 11 is equal to the inner cavity diameter of the shell 11. That is, the thickness of the electrode assembly 12 can extend along its radial direction, and the distance between the inner wall surfaces of the shell 11 can be equal to or slightly less than the inner cavity diameter of the shell 11. Exemplarily, the difference between the distance between the inner wall surfaces of the shell 11 and the inner cavity diameter of the shell 11 can be less than or equal to 2%, and optionally less than or equal to 1%.
  • a cylindrical battery cell usually includes only one wound electrode assembly, and the elastic buffer pad can be arranged inside the wound electrode assembly so that the laminated unit of the electrode assembly begins to wind around the elastic buffer pad; and/or, the elastic buffer pad can be arranged between the wound electrode assembly and the shell.
  • the inner cavity diameter of the shell 11 can be understood as the average diameter of the inner cavity of the shell.
  • the sum of the total thickness of the elastic buffer pad 13 in a free state and the total thickness of the electrode assembly 12 in a fully discharged state may be 80% to 99% of the diameter of the inner cavity of the shell 11, optionally 85% to 98%, and further optionally 90% to 95%; and/or, the sum of the total thickness of the elastic buffer pad 13 in a free state and the total thickness of the electrode assembly 12 in a fully charged state may be 85% to 110% of the diameter of the inner cavity of the shell 11, optionally 98% to 105%, and further optionally 99% to 102%.
  • the total thickness of the elastic cushion 13 in the free state and the total thickness of the electrode assembly 12 in the full discharge state can be understood as the average diameter of the electrode assembly plus twice the thickness of the single-layer elastic cushion 13 in the free state; in FIG10, the total thickness of the elastic cushion 13 in the free state and the total thickness of the electrode assembly 12 in the full discharge state (or in the full discharge state) can be understood as the average diameter of the elastic cushion 13 plus twice the thickness of the electrode assembly.
  • the inner cavity diameter of the shell 11 can be understood as the average diameter of the inner cavity of the shell, which can be measured by conventional methods and conventional instruments.
  • the sum of the total thickness of the elastic buffer pad 13 in a free state and the total thickness of the electrode assembly 12 in a fully discharged state can be 80%, 82%, 85%, 87%, 89%, 91%, 95%, 97%, 99%, etc., of the inner cavity diameter of the shell 11, or can be a range consisting of any of the above values. If the given conditions are met, a gap can be provided between the elastic buffer pad and the electrode assembly before they are inserted into the shell, which is beneficial for the smooth insertion of the elastic buffer pad and the electrode assembly into the shell and facilitates the assembly of the battery cell.
  • the sum of the total thickness of the elastic buffer pad 13 in the free state and the total thickness of the electrode assembly 12 in the fully charged state can be 95%, 97%, 99%, 100%, 102%, 104%, 106%, 108%, 110% of the inner diameter of the shell 11, or can be a range composed of any of the above values.
  • Meeting the given conditions is further beneficial to the use of the battery cell, so that the electrode assembly is directly attached to the inner wall of the shell or attached to the inner wall of the shell through the elastic buffer pad (or mylar film) to achieve mutual force, which is beneficial to further improve the force uniformity of the pole piece, reduce the occurrence of wrinkles in the local area of the electrode assembly, and reduce the occurrence of purple spots and lithium precipitation in the wrinkled area.
  • Abnormalities such as causing a decrease in the utilization rate of active lithium Risk, improve the capacity retention rate of battery cells.
  • Meeting the given conditions is not only beneficial to the assembly of battery cells, but also beneficial to improving the volume stability of the battery cells and the force uniformity of the pole pieces, thereby helping to reduce the risk of expansion and deformation or performance deterioration of the battery cells.
  • an elastic buffer pad 13 in a cylindrical battery cell, may be disposed between the electrode assembly 12 and the shell 11, and when the elastic buffer pad 13 is in a free state, a ratio of an extension distance in the circumferential direction of the electrode assembly 12 to the circumference of the electrode assembly 12 may be 0.8 to 1.2, optionally 0.85 to 1.1, and further optionally 0.9 to 1.05; and/or, when the elastic buffer pad 13 is in a free state, a ratio of an extension distance in the height direction of the electrode assembly 12 to the height of the electrode assembly 12 may be 0.8 to 1.2, optionally 0.85 to 1.1, and further optionally 0.9 to 1.05.
  • the ratio of the extension distance of the elastic buffer pad 13 in the circumferential direction of the electrode assembly 12 to the circumference of the electrode assembly 12 in the free state can be 0.8, 0.85, 0.9, 0.95, 1, 1.05, 1.1, 1.15, 1.2, etc., or can be a range composed of any of the above values, in which the circumference of the electrode assembly refers to the average circumference of the electrode assembly in the fully charged state.
  • the ratio of the extension distance of the elastic buffer pad 13 in the height direction of the electrode assembly 12 to the height of the electrode assembly 12 in the free state can be 0.8, 0.85, 0.9, 0.95, 1, 1.05, 1.1, 1.15, 1.2, etc., or can be a range composed of any of the above values, in which the height of the electrode assembly refers to the maximum extension distance of the electrode assembly along the height direction of the battery cell in the fully charged state.
  • the circumference and height of the electrode assembly, and the extension distance of the elastic buffer pad 13 in the circumference or height of the electrode assembly in a free state can be measured by conventional methods and conventional instruments.
  • the dimensions of the first elastic buffer pad and the electrode assembly meet the given conditions, which is conducive to the elastic buffer pad covering most areas of the electrode assembly, which is conducive to improving the volume stability of the battery cell, further improving the force uniformity of the pole piece, and reducing the risk of deterioration of battery cell performance.
  • the elastic buffer pad 13, in a free state extends a distance in the circumferential direction of the electrode assembly 12 that is less than or equal to the circumference of the electrode assembly 12; and/or, the elastic buffer pad 13, in a free state, extends a distance in the height direction of the electrode assembly 12 that is less than or equal to the height of the electrode assembly 12.
  • the elastic buffer pad meets the given conditions, which is not only conducive to the smooth insertion of the elastic buffer pad into the shell during the assembly process, but also conducive to further taking into account the energy density of the battery.
  • the thickness of a single elastic buffer pad 13 in a free state may be 2% to 15% of the thickness of a single electrode assembly 12 in a fully discharged state, and may be 5% to 10%.
  • the thickness of a single elastic buffer pad 13 in a free state may be 2%, 3%, 5%, 7%, 9%, 11%, 13%, 15%, etc. of the thickness of a single electrode assembly 12 in a fully discharged state, or may be a range consisting of any of the above values.
  • Meeting the given conditions is not only conducive to maintaining the volume stability of the battery cell during the service life, especially in the later period of use, but also takes into account the energy density of the battery cell.
  • the thickness of a single elastic buffer pad 13 in a free state may be 0.2 mm to 10.5 mm.
  • the thickness of a single elastic buffer pad 13 in a free state may be 0.2 mm, 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 10.5 mm, etc., or may be a range consisting of any of the above values.
  • Meeting the given conditions can not only take into account the compressible deformation of the elastic buffer pad and the energy density of the battery cell, but also make the support layer have a certain strength.
  • the structure and material of the elastic buffer pad are not particularly limited, as long as its compression rate along its thickness direction under a preset pressure can meet the given requirements.
  • at least one of the material, porosity and pore size of the elastic buffer pad can be adjusted to obtain elastic buffer pads with different stress-strain relationships, so as to achieve different compression rates of the elastic buffer pad along its thickness direction under a preset pressure.
  • the elastic buffer pad may be a single-layer structure, and its material may include but is not limited to at least one of foamed polyethylene, polypropylene, polyurethane, silicone rubber, etc.
  • the elastic buffer pad may be a multi-layer structure, and may specifically include an elastic buffer layer and a support layer.
  • the support layer may be provided on at least one of the two sides of the elastic buffer layer along the thickness direction.
  • at least one elastic buffer pad includes an elastic buffer layer and a support layer, and/or at least one elastic buffer pad includes an elastic buffer layer and two support layers.
  • the elastic modulus of the elastic buffer layer is smaller than the elastic modulus of the support layer, and/or, under the same pressure, the compression rate of the elastic buffer layer along its thickness direction is greater than the compression rate of the support layer along its thickness direction, and/or, the porosity of the elastic buffer layer may be greater than the porosity of the support layer.
  • the porosity of the elastic buffer layer 31 may be 40% to 95%, optionally 55% to 90%, and further optionally 70% to 85%, and the porosity of the support layer 32 may be less than or equal to 5%.
  • the elastic buffer layer may include at least 1% of foamed polyethylene, polypropylene, polyurethane, and silicone rubber.
  • At least one of the supporting layer may include but is not limited to at least one of high-density polyethylene, polymethacrylate, polyethylene terephthalate, and polytetrafluoroethylene.
  • the thickness of the elastic buffer layer may be greater than the thickness of the supporting layer; in a single elastic buffer pad, the ratio of the total thickness of the supporting layer to the free thickness of the elastic buffer layer may be 0.005 to 0.1, such as 0.02 to 0.05; the thickness of the elastic buffer layer in a natural state may be 0.2 mm to 10 mm, and the thickness of a single supporting layer may be 30 ⁇ m to 200 ⁇ m; the elastic buffer layer and the supporting layer may be bonded together.
  • the use of the supporting layer and the elastic buffer layer to composite can provide support for the elastic buffer layer, which can not only inhibit the thermal shrinkage of the elastic buffer layer (such as thermal shrinkage during vacuum baking), but also can optionally use the supporting layer to inhibit the thermal shrinkage of the elastic buffer layer in a two-dimensional direction perpendicular to its thickness direction, improve the problem of losing its original function due to thermal shrinkage, and at the same time improve the problem of material damage caused by mechanical stress in the elastic buffer pad in the later stage of battery use.
  • placing the elastic buffer pad inside the battery cell is beneficial to further improve the volume stability of the battery during long-term use and enhance the long-term use performance.
  • the electrode assembly 12 may include a positive electrode sheet, a negative electrode sheet, and a separator.
  • the positive electrode sheet, the negative electrode sheet, and the separator may be wound to form an electrode assembly.
  • active ions are embedded and removed back and forth between the positive electrode sheet and the negative electrode sheet.
  • the separator is disposed between the positive electrode sheet and the negative electrode sheet to play an isolation role.
  • a positive electrode plate generally includes a positive electrode current collector and a positive electrode active material layer disposed on the positive electrode current collector, wherein the positive electrode active material layer includes a positive electrode active material.
  • the positive electrode current collector may be a conventional metal foil or a composite current collector (a metal material may be disposed on a polymer substrate to form a composite current collector).
  • the positive electrode current collector may be an aluminum foil.
  • the specific type of positive electrode active material is not limited, and active materials known in the art that can be used for the positive electrode of the battery can be used, and those skilled in the art can choose according to actual needs.
  • the positive electrode active material may include but is not limited to lithium transition metal oxides and/or positive electrode active materials containing lithium phosphates of olivine structure, and the lithium transition metal oxides may include undoped and/or optionally doped and modified lithium transition metal oxides, uncoated and/or coated and modified lithium transition metal oxides, and the lithium phosphate containing olivine structure may include undoped and/or optionally doped and modified lithium phosphate containing olivine structure, uncoated and/or coated and modified lithium phosphate containing olivine structure.
  • the positive electrode active materials within the given range can be obtained either by preparation or by commercial channels.
  • the positive electrode active material layer may also optionally include a binder, a conductive agent and other optional additives.
  • the conductive agent may include but is not limited to one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, Super P (SP), graphene and carbon nanofibers.
  • the binder may include but is not limited to one or more of styrene-butadiene rubber (SBR), water-based acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyacrylic acid (PAA), carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA) and polyvinyl butyral (PVB).
  • SBR styrene-butadiene rubber
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • EVA ethylene-vinyl acetate copolymer
  • PAA polyacrylic acid
  • CMC carboxymethyl cellulose
  • PVA polyvinyl alcohol
  • PVB polyvinyl butyral
  • the negative electrode plate generally includes a negative electrode current collector and a negative electrode active material layer disposed on the negative electrode current collector, wherein the negative electrode active material layer includes a negative electrode active material.
  • the negative electrode current collector may be a conventional metal foil or a composite current collector (for example, a metal material may be disposed on a polymer substrate to form a composite current collector).
  • the negative electrode current collector may be a copper foil.
  • the battery cell of the first aspect of the present application may be a lithium-ion battery cell.
  • the specific type of the negative electrode active material is not limited, and active materials known in the art that can be used for the negative electrode of the battery may be used. Those skilled in the art may flexibly select according to actual needs.
  • the negative electrode active material may include, but is not limited to, one or more of artificial graphite, natural graphite, hard carbon, soft carbon, silicon-based materials, and tin-based materials.
  • the silicon-based material may include one or more of elemental silicon, silicon oxide compounds (such as silicon monoxide), silicon-carbon composites, silicon-nitrogen composites, and silicon alloys.
  • the tin-based material may include one or more of elemental tin, tin oxide compounds, and tin alloys.
  • the negative electrode active material within the given range can be obtained either by preparation or by commercial channels.
  • the negative electrode active material layer may also optionally include a binder, a conductive agent and other optional additives.
  • the conductive agent may include but is not limited to one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the binder may include but is not limited to one or more of styrene-butadiene rubber (SBR), water-based acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyvinyl alcohol (PVA) and polyvinyl butyral (PVB).
  • SBR styrene-butadiene rubber
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • EVA ethylene-vinyl acetate copolymer
  • PVA polyvinyl alcohol
  • PVB polyvinyl butyral
  • other optional additives may include but are not limited to thickeners and dispersants (such as sodium carboxymethyl cellulose CMC-Na), PTC thermistor materials.
  • the isolation membrane in the battery may include but is not limited to a polyethylene porous membrane, a polypropylene porous membrane, a polyimide porous membrane, and a porous membrane formed by a composite of multiple polymers.
  • the second aspect of the present application provides a battery, which includes: the battery cell described in the first aspect of the present application.
  • the battery may be a secondary battery, for example, the battery may be a lithium-ion secondary battery.
  • the battery may be either a battery cell 1 (refer to FIG. 11 for understanding), or a battery module 2 (refer to FIG. 12 for understanding) or a battery pack 3 (refer to FIG. 13 for understanding) composed of battery cells 1.
  • the battery may be a battery module, and the number of battery cells contained in the battery module may be one or more, and the specific number may be adjusted according to the application and capacity of the battery module.
  • a battery module 2 is taken as an example.
  • a plurality of battery cells 1 may be arranged in sequence along the length direction of the battery module 2. Of course, they may also be arranged in any other manner.
  • the plurality of battery cells 1 may further be fixed by fasteners.
  • the battery module 2 may also include a housing having a housing space, and a plurality of battery cells 1 are accommodated in the housing space.
  • the battery modules can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be adjusted according to the application and capacity of the battery pack.
  • the battery pack 3 may include a battery box and a plurality of battery modules 2 disposed in the battery box.
  • the battery box may include an upper box body 4 and a lower box body 5, and the upper box body 4 can be covered on the lower box body 5 to form a closed space for accommodating the battery modules 2.
  • the plurality of battery modules 2 can be arranged in the battery box in any manner.
  • the battery may include a first battery cell assembly and at least two second battery cell assemblies, the first battery cell assembly includes at least one battery cell 1 of the first aspect of the present application, the second battery cell assembly includes at least two second battery cells, the at least two second battery cells are arranged on both sides of the first battery cell assembly along the thickness direction of the first battery cell assembly, and the thickness direction of the first battery cell assembly is consistent with the thickness direction of the battery cell 1.
  • the battery cell of the first aspect of the present application is a prismatic battery cell with a wound electrode assembly, and by combining a prismatic shell, a wound electrode assembly and an elastic buffer pad, the problem of uneven force on the pole piece in the prismatic wound battery can be alleviated, and the stability of the battery cell can be improved.
  • the battery can be either a battery module or a battery pack.
  • the first battery cell assembly may include a plurality of battery cells 1 arranged in rows and/or columns, and/or, the first battery cell assembly may be independently provided with a plurality of second battery cells arranged in rows and/or columns on both sides along its thickness direction, optionally, at least two second battery cells may be symmetrically arranged on both sides of the first battery cell assembly along the thickness direction; further optionally, in the battery module or the battery pack, based on the total number of battery cells 1 and second battery cells, the number of battery cells 1 may account for 30% to 70%.
  • a battery usually includes multiple battery cells.
  • the stacking method of the multiple battery cells includes stacking them along the thickness direction of the battery cells. In the thickness direction of the battery cells, the battery cells located in the middle of the battery are often the parts that swell most severely and have the greatest expansion force during use.
  • the first elastic buffer pad in the first battery cell located in the middle By only embedding the first elastic buffer pad in the first battery cell located in the middle, and not providing the elastic buffer pad in the second battery cells located on both sides of the thickness direction of the first battery cell assembly, it is not only beneficial to absorb the volume expansion of the battery cells with relatively more severe expansion and relatively greater expansion force in the battery, reduce the expansion force of the battery cells in the middle of the battery, and improve the volume stability of the battery, but also beneficial to alleviate the problem of stress concentration in the battery cells located in the middle of the battery due to the volume expansion of the battery cells in the later stage of battery use, thereby causing lithium precipitation in the battery cells in the middle; at the same time, it can also take into account the high energy density of the battery.
  • the present application also provides an electrical device, which includes: the battery of the second aspect of the present application.
  • the battery such as a battery cell, a battery module or a battery pack
  • the electrical device may include, but is not limited to, mobile devices (such as mobile phones, laptops), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, and energy storage systems.
  • the electrical device can be a vehicle.
  • the electrical device can select the specific type of battery according to its usage requirements, such as a battery cell, a battery module or a battery pack.
  • the electric device may be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle.
  • a battery pack or a battery module may be used.
  • the electrical device may be a mobile phone, a tablet computer, or a laptop computer.
  • the electrical device is usually required to be thin and light, and may use a battery cell as a power source.
  • the positive electrode active material LiNi 0.6 Co 0.1 Mn 0.3 O 2 , the conductive agent Super P, and the binder PVDF were mixed in a weight ratio of 96:2:2, and the solvent N-methylpyrrolidone was added, and the mixture was fully stirred and mixed to obtain a positive electrode slurry, which was then coated on both surfaces of a positive electrode current collector aluminum foil with a thickness of 13 ⁇ m.
  • the coating surface density of the positive electrode slurry on one side of the aluminum foil was 20 mg/cm 2 , and then dried and cold pressed to obtain a positive electrode sheet.
  • the negative electrode active material artificial graphite, the conductive agent Super P, the binder styrene-butadiene rubber, and the thickener sodium carboxymethyl cellulose were mixed in a weight ratio of 96:0.5:2:1.5, and the solvent deionized water was added, and the mixture was fully stirred to obtain a negative electrode slurry, which was then coated on both surfaces of a negative electrode current collector copper foil with a thickness of 6 ⁇ m.
  • the coating thickness of the negative electrode slurry on one side of the copper foil was 100 ⁇ m, and the coating surface density of the negative electrode slurry on one side of the copper foil was 11 mg/cm 2 .
  • the negative electrode sheet was then dried and cold pressed.
  • solvents EC ethylene carbonate
  • PC propylene carbonate
  • DMC dimethyl carbonate
  • a polyethylene porous membrane with a thickness of 7 ⁇ m was used as the separator.
  • Polypropylene with a thickness of 3 mm in a free state is used as the elastic buffer pad.
  • the positive electrode sheet, the separator, and the negative electrode sheet are stacked in order, the separator is placed between the positive and negative electrode sheets to play a role of isolation, and the electrode assembly is obtained by winding and molding.
  • the two electrode assemblies and the elastic cushion are placed in a battery shell (the distance d0 between the two inner wall surfaces oppositely arranged along the thickness direction is 60 mm), and a layer of elastic cushion is sandwiched between the two electrode assemblies, and the prepared electrolyte is injected and packaged to obtain a lithium-ion lithium secondary battery.
  • Examples 2 to 19 and Comparative Examples 1 to 3 and Example 1 are detailed in Table 1.
  • the elastic buffer pads in Examples 1 to 19 and Comparative Examples 1 to 3 are all porous structures, and the elastic buffer pads of the same material have different compression rates under the same stress due to the different porosity and pore size of the elastic buffer pads;
  • the elastic buffer pads in Examples 7 to 8 are all obtained by mixing polypropylene and polyethylene in a mass ratio of 1:1 and melt-forming, and the porosity and pore size of the elastic buffer pads in Examples 7 and 8 are different.
  • the test method is: place the electrode assembly in the middle of two parallel flat plates, use the flat plates to apply a pressure of 0.1MPa to the electrode assembly, and measure the distance between the flat plates to obtain the thickness of the electrode assembly.
  • the total thickness d1 of the electrode assembly in the secondary battery in a fully charged state and the total thickness d2 of the electrode assembly in a fully discharged state are calculated.
  • the thickness of the elastic buffer pad in the free state is measured by using a Mitutoyo ID-C112MX micrometer thickness gauge under a test force less than or equal to 1.8 N. Multiple points (such as 5, 10, etc.) are randomly measured and the average value is taken to calculate the total thickness d of the elastic buffer pad in the secondary battery in the free state, and the length L2 and height h2 of the elastic buffer pad are tested (the length and height of the elastic buffer pad match the length direction and height direction of the electrode assembly respectively); the elastic buffer pad is placed between two parallel flat plates, and the flat plates are used to respectively By applying pressures of 0.1MPa and 0.5MPa and measuring the distance between the plates, the thickness of the electrode assembly under compressive stress is obtained.
  • the compression rate of the elastic buffer pad along its thickness under compressive stress is the ratio of the thickness change of the elastic buffer pad in the free state and the compressive stress state to the thickness in the free state multiplied by 100%.
  • the secondary battery After the secondary battery was left at rest for 5 minutes at 25°C, it was charged to 4.4V at a constant current of 0.5C, and then charged to 0.05C at a constant voltage of 4.4V, and left to rest for 5 minutes. Then the secondary battery was discharged to 2.8V at a constant current of 0.33C, and left to rest for 5 minutes.
  • Six pressure sensors were set at different positions on one side in the thickness direction, and charged to 4.4V at a constant current of 0.5C, and then charged to 0.05C at a constant voltage of 4.4V, and left to rest for 5 minutes.
  • the expansion force displayed by the pressure sensors at different positions of the secondary battery was recorded when it was charged to 30% SOC, 50% SOC, and 100% SOC, respectively, and the average value of the expansion force under different charging states was calculated, and the range of the rate of change of each expansion force under different charging states compared to the average value was calculated based on the average value.
  • the secondary battery After the secondary battery is left at 25°C for 5 minutes, it is charged to 4.4V at 0.5C constant current, and then charged to 0.05C at 4.4V constant voltage, and left to stand for 5 minutes. Then the secondary battery is discharged to 2.8V at 0.33C constant current, and left to stand for 5 minutes. Repeat the above charge and discharge cycle until the capacity of the secondary battery is significantly attenuated. After the charge and discharge cycle test is completed, the secondary battery is disassembled to observe whether there is lithium deposition on the negative electrode.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Secondary Cells (AREA)
  • Battery Mounting, Suspending (AREA)
  • Sealing Battery Cases Or Jackets (AREA)

Abstract

一种电池单体、电池和用电装置。电池单体包括：壳体；至少一个电极组件，所述电极组件置于所述壳体内；至少一个弹性缓冲垫，所述弹性缓冲垫设在所述电极组件的至少部分表面和/或所述电极组件内部，所述弹性缓冲垫在0.1MPa的压力下沿其厚度方向的压缩率≤30％、在1MPa的压力下沿其厚度方向的压缩率≥50％。

Description

电池单体、电池和用电装置 技术领域
本申请属于电池技术领域，具体而言，涉及电池单体、电池和用电装置。
背景技术
电池作为储能装置，广泛应用于各个领域。以锂离子电池为例，其具有绿色、环保、高能、低碳等特点，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，还被广泛应用于电动自行车、电动摩托车、电动汽车、船舶等电动交通工具，以及军事装备和航空航天等多个领域。随着当前社会的发展，人们对于电池的要求也越来越高。
公开内容
鉴于背景技术中存在的技术问题，本申请提供一种电池单体，旨在改善缓冲垫的效果发挥，改善极片在充放电过程中的受力均匀性。
为了实现上述目的，本申请的第一方面提供一种电池单体，其包括：
壳体；
至少一个电极组件，所述电极组件置于所述壳体内；
至少一个弹性缓冲垫，所述弹性缓冲垫设在所述电极组件的至少部分表面和/或所述电极组件内部，所述弹性缓冲垫在0.1Mpa的压力下沿其厚度方向的压缩率≤30％、在1Mpa的压力下沿其厚度方向的压缩率≥50％。
本申请第一方面的电池单体具有以下有益效果：一方面，可以缓冲电极组件在充放电和使用过程中产生的体积膨胀力，抑制电池单体变形；另一方面，可以使弹性缓冲垫在不同的充放电进程中提供不同的强度和应力，在充电初期或使用初期弹性缓冲垫不被过度压缩，可以提供一定的支撑强度，有利于实现电极组件与壳体内壁的直接贴合或通过弹性缓冲垫与壳体内壁贴合，实现相互作用力，改善极片的受力均匀性，而在充电后期或电池单体循环后期，弹性缓冲垫可以在电极组件膨胀过程中被充分压缩，将其厚度方向的空间让渡给到电极组件，降低电极组件的膨胀力，并提供较大的应力，在降低电极组件的膨胀力的同时，改善维持极片在充放电过程中的受力均匀性。由此，可以使弹性缓冲垫发挥较好的效果，在改善电池单体在长期使用过程中的体积稳定性的同时，还利于维持极片在充放电过程中的受力均匀性，进而有利于降低电池单体膨胀变形或性能恶化的风险，提高长期使用性能。
在本申请的一些实施方式中，所述电极组件与所述壳体之间设有所述弹性缓冲垫，和/或相邻两个所述电极组件之间设有所述弹性缓冲垫。满足所给条件有利于改善电池单体在长期使用过程中的体积稳定性。
在本申请的一些实施方式中，所述弹性缓冲垫在0.1Mpa的压力下沿其厚度方向的压缩率≤20％，可选≤10％；和/或，所述弹性缓冲垫在1Mpa的压力下沿其厚度方向的压缩率≥60％，可选≥80％。满足所给条件有利于进一步改善极片在充放电进程中的受力均匀性。
在本申请的一些实施方式中，所述弹性缓冲垫在0.5Mpa压力下的压缩率为30％～60％。满足所给条件有利于在提高电池单体的体积稳定性的同时，进一步改善极片在充放电过程中的受力均匀性。
在本申请的一些实施方式中，所述电极组件为卷绕电极组件，且包括平直部和拐角部，所述弹性缓冲垫设在所述平直部和/或所述拐角部的至少部分表面。
在本申请的一些实施方式中，所述电池单体为棱柱状电池单体。
在本申请的一些实施方式中，所述棱柱状电池单体包括：至少一个第一弹性缓冲垫和/或至少一个 第二弹性缓冲垫，所述第一弹性缓冲垫和所述电极组件沿所述电池单体的厚度方向层叠设置，和/或，所述第二弹性缓冲垫和所述电极组件沿所述电池单体的长度方向层叠设置。满足所给条件有利于降低电极组件在使用过程中产生的膨胀力。
在本申请的一些实施方式中，所述棱柱状电池单体满足以下条件中的至少之一：在所述电池单体的厚度方向上，所述第一弹性缓冲垫在自由状态下的总厚度与所述电极组件在满放电状态下的总厚度之和为所述壳体内壁面之间的距离的80％～99％，可选为85％～98％，再可选为90％～95％；在所述电池单体的厚度方向上，所述第一弹性缓冲垫在自由状态下的总厚度与所述电极组件在满充电状态下的总厚度之和为所述壳体内壁面之间的距离的95％～110％，可选为98％～105％，再可选为99％～102％；在所述电池单体的长度方向上，所述第二弹性缓冲垫在自由状态下的总厚度与所述电极组件在满放电状态下的长度之和为所述壳体内壁面之间的距离的80％～99％，可选为85％～98％，再可选为90％～95％；在所述电池单体的长度方向上，所述第二弹性缓冲垫在自由状态下的总厚度与所述电极组件在满充电状态下的长度之和为所述壳体内壁面之间的距离的95％～110％，可选为98％～105％，再可选为99％～102％。满足所给条件有利于弹性缓冲垫顺利入壳，和/或改善电池单体的体积稳定性和极片的受力均匀性。
在本申请的一些实施方式中，所述第一弹性缓冲垫在自由状态下的总厚度与所述电极组件在满放电状态下的总厚度的比值为2％～25％，可选为5％～20％，再可选为8％～15％。满足所给条件既有利于维持电池单体的体积稳定，还可以兼顾电池单体的能量密度。
在本申请的一些实施方式中，所述第一弹性缓冲垫在自由状态下，在所述电极组件长度方向上的延伸距离与所述电极组件长度的比值为0.8～1.2，可选为0.85～1.1，再可选为0.9～1.05；和/或，所述第一弹性缓冲垫在自由状态下，在所述电极组件高度方向上的延伸距离与所述电极组件高度的比值为0.8～1.2，可选为0.85～1.1，再可选为0.9～1.05。满足所给条件有利于使弹性缓冲垫能够覆盖电极组件的大部分区域，既有利于改善电池单体的体积稳定性，还有利于进一步改善极片的受力均匀性。
在本申请的一些实施方式中，所述第一弹性缓冲垫在所述电极组件上的正投影位于所述电极组件所在的区域内。满足所给条件，既有利于弹性缓冲垫在装配过程中顺利入壳，还有利于进一步兼顾电池的能量密度。
在本申请的一些实施方式中，所述电池单体为圆柱形电池单体，至少一个所述弹性缓冲垫和所述电极组件沿所述电极组件的半径方向层叠设置，所述壳体内壁面之间的距离等于所述壳体内腔直径。
在本申请的一些实施方式中，所述圆柱形电池单体中，所述弹性缓冲垫在自由状态下的总厚度与所述电极组件在满放电状态下的总厚度之和为所述壳体内腔直径的80％～99％，可选为85％～98％，再可选为90％～95％；和/或，所述弹性缓冲垫在自由状态下的总厚度与所述电极组件在满充电状态下的总厚度之和为所述壳体内腔直径的85％～110％，可选为98％～105％，再可选为99％～102％。满足所给条件有利于弹性缓冲垫顺利入壳，和/或改善电池单体的体积稳定性和极片的受力均匀性。
在本申请的一些实施方式中，所述圆柱形电池单体中，所述弹性缓冲垫设在所述电极组件与所述壳体之间，所述弹性缓冲垫在自由状态下，在所述电极组件周向上的延伸距离与所述电极组件的周长的比值为0.8～1.2，可选为0.85～1.1，再可选为0.9～1.05；和/或，所述弹性缓冲垫在自由状态下，在所述电极组件高度方向上的延伸距离与所述电极组件高度的比值为0.8～1.2，可选为0.85～1.1，再可选为0.9～1.05。满足所给条件有利于使弹性缓冲垫能够覆盖电极组件的大部分区域，既有利于改善电池单体的体积稳定性，还有利于进一步改善极片的受力均匀性。
在本申请的一些实施方式中，所述圆柱形电池单体中，所述弹性缓冲垫在自由状态下，在所述电极组件周向上的延伸距离小于或等于所述电极组件的周长；和/或，所述弹性缓冲垫在自由状态下，在所述电极组件高度方向上的延伸距离小于或等于所述电极组件的高度。满足所给条件，既有利于弹性缓冲垫在装配过程中顺利入壳，还有利于进一步兼顾电池的能量密度。
在本申请的一些实施方式中，单个所述弹性缓冲垫在自由状态下的厚度为单个所述电极组件在满放电状态下的厚度的2％～15％，可选为5％～10％。满足所给条件既有利于维持电池单体在使用周期内尤其是使用后期的体积稳定性，还可以兼顾电池单体的能量密度。
在本申请的一些实施方式中，单个所述弹性缓冲垫在自由状态下的厚度为0.2mm～10.5mm。满足所给条件既可以兼顾弹性缓冲垫的可压缩形变量和电池单体的能量密度，还能使支撑层具有一定的强度。
本申请的第二方面提供了一种电池，其包括：本申请第一方面所述的电池单体。
本申请的第三方面提供了一种用电装置，其包括：本申请第二方面所述的电池。
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是根据本申请一个实施方式的棱柱状电池单体的截面结构示意图。
图2是根据本申请再一个实施方式的棱柱状电池单体的截面结构示意图。
图3是根据本申请另一个实施方式的棱柱状电池单体的截面结构示意图。
图4是根据本申请又一个实施方式的棱柱状电池单体的截面结构示意图。
图5是根据本申请又一个实施方式的棱柱状电池单体的截面结构示意图。
图6是根据本申请又一个实施方式的棱柱状电池单体的截面结构示意图。
图7是根据本申请又一个实施方式的棱柱状电池单体的截面结构示意图。
图8是根据本申请又一个实施方式的棱柱状电池单体的截面结构示意图。
图9是根据本申请一个实施方式的圆柱形电池单体的截面结构示意图。
图10是根据本申请再一个实施方式的圆柱形电池单体的截面结构示意图。
图11是根据本申请一个实施例的电池单体的结构示意图。
图12是根据本申请一个实施例的电池模块的结构示意图。
图13是根据本申请一个实施例的电池包的结构示意图。
图14是根据本申请一个实施例的电池包的爆炸图。
图15是根据本申请一个实施例的电池用作电源的用电装置的一个实施方式的示意图。
附图标记：
11：壳体；12：电极组件；13：弹性缓冲垫；13a：第一弹性缓冲垫；13b：第二弹性缓冲垫；1：
电池；2：电池模块；3：电池包；4：上箱体；5：下箱体。
具体实施方式
下面结合具体实施方式，进一步阐述本申请。应理解，这些具体实施方式仅用于说明本申请而不用于限制本申请的范围。
以下，适当地参照附图详细说明具体公开了本申请的正极活性材料及其制备方法、正极极片、电池和用电装置的实施方式。但是会有省略不必要的详细说明的情况。例如，有省略对已众所周知的事项的详细说明、实际相同结构的重复说明的情况。这是为了避免以下的说明不必要地变得冗长，便于本领域技术人员的理解。此外，附图及以下说明是为了本领域技术人员充分理解本申请而提供的，并不旨在限定权利要求书所记载的主题。
本申请所公开的“范围”以下限和/或上限的形式来限定，给定范围是通过选定一个下限和/或一个上限进行限定的，选定的下限和/或上限限定了特别范围的边界。这种方式进行限定的范围可以是包括端值或不包括端值的，并且可以进行任意地组合，即任意下限可以与任意上限组合形成未明确记载的范围，以及任意下限可以与其它下限组合形成未明确记载的范围，同样任意上限可以与任意其它上限组合形成未明确记载的范围。此外，每个单独公开的点或单个数值自身可以作为下限或上限与任意其它点或单个数值组合或与其它下限或上限组合形成未明确记载的范围。例如，如果针对特定参数列出了60～120和80～110的范围，理解为60～110和80～120的范围也是预料到的。此外，如果列出的最小范围值1和2，和如果列出了最大范围值3，4和5，则下面的范围可全部预料到：1～3、1～4、1～5、2～3、2～4和2～5。在本申请中，除非有其它说明，数值范围“a～b”表示a到b之间的任意实数组合的 缩略表示，其中a和b都是实数。例如数值范围“0～5”表示本文中已经全部列出了“0～5”之间的全部实数，“0～5”只是这些数值组合的缩略表示。另外，当表述某个参数为≥2的整数，则相当于公开了该参数为例如整数2、3、4、5、6、7、8、9、10、11、12等。
如果没有特别的说明，本申请的所有实施方式以及可选实施方式可以相互组合形成新的技术方案，并且这样的技术方案应被认为包含在本申请的公开内容中。
如果没有特别的说明，本申请的所有技术特征以及可选技术特征可以相互组合形成新的技术方案，并且这样的技术方案应被认为包含在本申请的公开内容中。
如果没有特别的说明，本申请的所有步骤可以顺序进行，也可以随机进行，优选是顺序进行的。例如，所述方法包括步骤S1和S2，表示所述方法可包括顺序进行的步骤S1和S2，也可以包括顺序进行的步骤S2和S1。例如，所述提到所述方法还可包括步骤S3，表示步骤S3可以任意顺序加入到所述方法，例如，所述方法可以包括步骤S1、S2和S3，也可包括步骤S1、S3和S2，也可以包括步骤S3、S1和S2等。
如果没有特别的说明，本申请所提到的“包括”和“包含”表示开放式，也可以是封闭式。例如，所述“包括”和“包含”可以表示还可以包括或包含没有列出的其它组分，也可以仅包括或包含列出的组分。
如果没有特别的说明，在本申请中，术语“或”是包括性的。举例来说，短语“A或B”表示“A，B，或A和B两者”。更具体地，以下任一条件均满足条件“A或B”：A为真(或存在)并且B为假(或不存在)；A为假(或不存在)而B为真(或存在)；或A和B都为真(或存在)。
如果没有特别的说明，在本申请中，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。
在本申请中，术语“多个”、“多种”是指两个或两种以上。
除非另有定义，本申请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；本申请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。除非另有说明，本申请中使用的术语具有本领域技术人员通常所理解的公知含义。除非另有说明，本申请中提到的各参数的数值可以用本领域常用的各种测量方法进行测量(例如，可以按照在本申请的实施例中给出的方法进行测试)。
随着绿色环保主题的不断推进，电池的应用已经深入到了生活的方方面面，包括车辆、电子设备、储能装置等。但随着电池应用的不断推广，人们对于电池的要求也越来越高。以锂离子为例，锂离子电池在充放电循环、过充等过程中会伴随着体积变化，且随着工作时长的增长，其膨胀量是逐渐变大的，这不仅易导致电池壳体在挤压力下变形，影响电池的体积稳定性，而且电池在充放电循环中若极片过度膨胀，还可能会影响极片与隔膜之间的间距，增加析锂风险，影响电池的使用寿命。针对该问题，目前有在电芯之间或电芯内设置缓冲垫的方案，但受电极极片活性材料种类及活性物质层的厚度、循环次数等因素的影响，电池在不同的充放电进程和在不同使用阶段的充放电过程中的膨胀量和膨胀率也会有所不同。而针对不同的充放电进程和不同使用阶段的充放电过程，对位于电芯内部的缓冲垫的应力应变的需求是不同的，不恰当的匹配不利于缓冲垫效果的发挥，甚至还可能会引发电芯性能的恶化。
本申请中，针对电池单体中电极组件在不同的充放电进程和不同使用阶段的膨胀量及膨胀率不同，对弹性缓冲垫的应力应变关系做了不同的限定，即，选择在0.1Mpa的压力下沿其厚度方向的压缩率≤30％，且在1Mpa的压力下沿其厚度方向的压缩率≥50％的弹性缓冲垫，从而可以使弹性缓冲垫在充电过程中提供不同的强度和应力，在电池单体使用初期或充电初期，弹性缓冲垫不被过度压缩，可以提供一定的支撑强度，有利于实现电极组件与壳体内壁的直接贴合或通过弹性缓冲垫与壳体内壁贴合，改善极片的受力均匀性；而在充电后期或电池单体使用后期，弹性缓冲垫可以在电极组件膨胀过程中被充分压缩，将其厚度方向的空间让渡给到电极组件，并提供较大的应力，在降低电极组件的膨胀力 的同时，有利于维持极片在充放电过程中的受力均匀性。
本申请实施例公开的电池单体和电池可以用于使用电池作为电源的用电装置或者使用电池作为储能元件的各种储能系统。用电装置可以包括但不限于手机、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。
本申请的第一方面提供一种电池单体，其包括：壳体；至少一个电极组件，电极组件置于壳体内；至少一个弹性缓冲垫，弹性缓冲垫设在所述电极组件的至少部分表面和/或所述电极组件内部，弹性缓冲垫在0.1Mpa的压力下沿其厚度方向的压缩率≤30％、在1Mpa的压力下沿其厚度方向的压缩率≥50％。
参考图1～7理解，本申请的第一方面的电池单体1包括壳体11、至少一个电极组件12和至少一个弹性缓冲垫13，电极组件12置于壳体11内，弹性缓冲垫13可以设在电极组件12的至少部分表面和/或电极组件12内部。示例性的，弹性缓冲垫13可以设在电极组件12与壳体11之间(参考图1理解)，和/或设在相邻两个电极组件12之间(参考图2理解)，和/或设在电极组件内部(参考图3理解)。其中，弹性缓冲垫13可以设在电极组件12与壳体11之间，可以理解为，可以设在电极组件12与壳体11侧壁之间、电极组件12和壳体11底壁之间、电极组件12和壳体11顶壁之间中的至少之一的区域内，可选地，参考图4或图5理解，可以在电极组件12与壳体11之间和相邻两个电极组件之间同时设置弹性缓冲垫13；再可选地，参考图1、图6、图7理解，弹性缓冲垫13可以设在电极组件12与壳体11的侧壁之间。在实际操作过程中，弹性缓冲垫13沿其厚度方向的两侧可以均与电极组件12可贴合设置(参考图2理解)，也可以一侧与电极组件12可贴合设置，另一侧与壳体11内壁可贴合设置。
作为一些具体示例，当电池单体1仅包括一个电极组件12时，弹性缓冲垫13的个数可以为一个或多个，既可以设在电极组件12和壳体11之间，也可以设在电极组件的内部，可选地，可以设在电极组件12和壳体11的侧壁之间。作为另一些具体示例，当电池单体1包括至少两个电极组件12时，弹性缓冲垫13的个数可以为一个或多个，所述一个或多个弹性缓冲垫13既可以仅设在电池组件12之间，或仅设在电池组件12与壳体11之间，或仅设在电极组件12内部，也可以部分设在电池组件12之间、部分设在电池组件12与壳体11之间，等等。可选地，设在电池组件12与壳体11之间的弹性缓冲垫13可以设在电极组件12和壳体11的侧壁之间。
可选地，至少一个弹性缓冲垫13的厚度方向与电池单体1的厚度方向相同(参考图1～6和8理解)，再可选地，至少一个弹性缓冲垫13的厚度方向与电池单体1和电极组件12的厚度方向相同。
本申请的电池单体中，至少一个电极组件12和至少一个弹性缓冲垫13沿第一方向层叠设置，可选地，所述第一方向可以为电极组件12的厚度方向，当电极组件12为卷绕电极组件且包括平直部和拐角部时，所述第一方向可以为所述平直部的厚度方向；当电极组件12为圆柱状时，所述第一方向为电极组件的径向，壳体11沿所述第一方向的壳体内壁面之间的距离即壳体的内腔直径。
电池单体在充放电进程中，随着剩余容量(即SOC值)的提高，电极组件产生的形变和膨胀力也会提升，且随着循环次数的增加，电极组件在充放电过程中产生的膨胀量和膨胀力通常也是增加的，即在电池使用寿命的后期电极组件在充放电过程中产生的膨胀量和膨胀力通常是大于电池使用寿命的初期的。本申请的电池单体中，针对弹性缓冲垫在不同应力状态下的应变做了要求，即选择在0.1Mpa的压力下沿其厚度方向的压缩率≤30％(如可以≤30％、≤28％、≤25％、≤22％、≤20％、≤18％、≤16％、≤14％、≤12％、≤10％、≤8％、≤6％、≤4％等，或者可以为以上任何数值所组成的范围)、且在1Mpa的压力下沿其厚度方向的压缩率≥50％(如可以≥50％、≥55％、≥60％、≥65％、≥70％、≥75％、≥80％、≥85％等，或者可以为以上任何数值所组成的范围)的弹性缓冲垫。进而，可以使弹性缓冲垫在不同的充放电进程中能提供不同的强度和应力，在充电初期或电池单体使用初期，弹性缓冲垫不被过度压缩，可以提供一定的支撑强度，有利于实现电极组件与壳体内壁的直接贴合或通过弹性缓冲垫与壳体内壁贴合，实现相互作用力，改善极片的受力均匀性，降低电极组件局部区域产生褶皱以及在褶皱区域出现紫斑和析锂等异常引发活性锂利用率下降的风险；而在充电后期或电池单体循环后期，弹性缓冲垫 可以在电极组件膨胀过程中被充分压缩，将其厚度方向的空间让渡给到电极组件，降低电极组件的膨胀力，并提供较大的应力，在降低电极组件的膨胀力的同时，改善维持极片在充放电过程中的受力均匀性。
其中，弹性缓冲垫在不同应力下沿其厚度方向的压缩率可参照GB/T 1041-92进行。弹性缓冲垫沿其厚度方向的压缩率为弹性缓冲垫在自由状态下和在应力状态下的厚度变化量与在自由状态下厚度的比值，弹性缓冲垫的自由状态指弹性缓冲垫没有受到任何外力的作用的状态，弹性缓冲垫的应力状态指弹性缓冲垫在受到一定的压应力的状态。弹性缓冲垫在自由状态下的厚度测试可以采用本领域的常规仪器和常规方法进行测试，如可以采用MitutoyoID-C112MX千分尺测厚仪(或同类型仪器)，在测试力小于或等于1.8N的状态下进行测试，随机测量多个点(如5、10个等)取平均值。弹性缓冲垫在应力状态下的厚度测试可以采用两块平行的平板，使弹性缓冲垫位于平板中间，利用平板向弹性缓冲垫施加预设压力并测量平板间距得到，测量平板间距时采用的仪器可以包括但不限于游标卡尺等常规仪器。
本申请第一方面的电池单体具有以下有益效果：可以使弹性缓冲垫发挥较好的效果，在改善电池单体在长期使用过程中的体积稳定性的同时，还利于维持极片在充放电过程中的受力均匀性，进而有利于降低电池单体膨胀变形或性能恶化的风险，提高长期使用性能。
可以理解的是，在本申请的实施例中，电池单体包括但不限于壳体、电极组件和弹性缓冲垫，例如，电池单体还可以包括电解液；在本申请的实施例中，电池单体包括但不限于二次电池单体、一次电池单体等；在本申请的实施例中，电池单体包括但不限于锂离子电池单体、钠离子电池单体、镁离子电池单体等；在本申请的实施例中，电池单体包括但不限于硬质电池单体、软包电池单体等，硬质电池单体包括但不限于金属电池壳体单体等。
进一步地，本申请的第一方面的电池单体在满足上述条件的基础上，还可以进一步控制弹性缓冲垫在特定应力下沿其厚度方向上的压缩率、弹性缓冲垫与电极组件和/和壳体尺寸之间的关系、针对不同电池单体类型的布置方式等来进一步改善电池单体的性能。即，在满足上述条件的基础上，还可选地满足下述条件中的一个或多个。
在本申请的一些实施方式中，电极组件12与壳体11之间设有弹性缓冲垫13，和/或相邻两个电极组件12之间设有弹性缓冲垫13。可参考图1、图2和图4理解。满足所给条件进一步有利于改善电池单体在长期使用过程中的体积稳定性，降低其膨胀变形或性能恶化的风险。可选地，可以仅在电极组件12与壳体11之间和/或相邻两个电极组件12之间设置弹性缓冲垫13，由此既有利于电极组件成型，还有利于降低电极组件对壳体产生的膨胀力。
在本申请的一些实施方式中，弹性缓冲垫13在0.1Mpa的压力下沿其厚度方向的压缩率可以≤20％，可选≤10％。选择进一步满足所给条件的弹性缓冲垫，有利于进一步实现弹性缓冲垫在电池单体充电初期不被过度压缩，可以提供一定的支撑强度，有利于实现电极组件与壳体内壁的直接贴合或通过弹性缓冲垫与壳体内壁贴合，实现相互作用力，改善极片的受力均匀性。
在本申请的一些实施方式中，弹性缓冲垫13在1Mpa的压力下沿其厚度方向的压缩率可以≥60％，可选≥80％。选择进一步满足所给条件的弹性缓冲垫，有利于在充电后期或电池单体循环后期，弹性缓冲垫可以在电极组件膨胀过程中被充分压缩，将其厚度方向的空间让渡给到电极组件，降低电极组件的膨胀力，并提供较大的应力，从而既有利于降低电极组件的膨胀力，改善电池单体的体积稳定性，还有利于维持极片在充放电过程中的受力均匀性。
在本申请的一些实施方式中，弹性缓冲垫13在0.5Mpa压力下的压缩率可以为30％～60％。
例如，弹性缓冲垫13在0.5Mpa压力下的压缩率可以为30％、35％、40％、45％、50％、55％、60％等，或者可以为以上任何数值所组成的范围。选择进一步满足所给条件的弹性缓冲垫，进一步有利于弹性缓冲垫在不同的充放电进程中能提供不同的强度和应力，有利于进一步在改善电池单体的体积稳定性的同时，进一步维持极片在充放电过程中的受力均匀性。
在本申请的一些实施方式中，电极组件12可以为卷绕电极组件，且包括平直部和拐角部，弹性缓冲垫13可以设在平直部和/或拐角部的至少部分表面。
本申请的电池单体中，电极组件可以为叠片式电极组件，也可以为卷绕电极组件；卷绕电极组件又可以用于棱柱状壳体中或圆柱形壳体中。其中，卷绕电极组件在充放电过程中，极片存在受力不均的风险相对较高，尤其是具有卷绕电极组件的棱柱状电池单体，将卷绕电极组件和弹性缓冲垫结合，有利于缓解卷绕电极组件中极片受力不均的问题，降低极化差异，改善体积稳定性和长期循环性能。可选地，电极组件12可以为卷绕电极组件，且包括平直部和拐角部，弹性缓冲垫13可以设在平直部和/或拐角部的至少部分表面，由此有利于进一步缓解棱柱状电池单体中极片受力不均的问题。可以理解的是，棱柱状电池单体包括但不限于方形电池单体。又可选地，卷绕电极组件的平直部可以设有弹性缓冲垫13。
在本申请的一些实施方式中，参考图1～8理解，电池单体1可以为棱柱状电池单体。
在本申请的一些实施方式中，棱柱状电池单体可以包括：至少一个第一弹性缓冲垫13a和/或至少一个第二弹性缓冲垫13b，第一弹性缓冲垫13a和电极组件12可以沿电池单体的厚度方向层叠设置，和/或，第二弹性缓冲垫13b和电极组件12可以沿电池单体的长度方向层叠设置。
参考图8理解，以方形电池单体为例，所给结构设计中，第一弹性缓冲垫13a的厚度可以沿电池单体的厚度方向延伸，和/或，第二弹性缓冲垫13b的厚度可以沿电池单体的长度方向延伸。设置第一弹性缓冲垫13a和第二弹性缓冲垫13b均有利于降低电极组件在使用过程中产生的膨胀力。可选地，方形电池单体可以包括至少一个第一弹性缓冲垫13a，方形电池单体的壳体11中，在电池单体厚度方向上相对设置的两个侧壁的面积通常较大，在该两个侧壁之间设置第一弹性缓冲垫，有利于提高弹性缓冲垫与电极组件的接触面积，从而既有利于进一步降低电极组件在使用过程中可能产生的膨胀力，还有利于进一步缓解卷绕电极组件中极片可能存在的受力不均的问题。再可选地，棱柱状电池单体可以仅包括第一弹性缓冲垫13a，满足所给条件既有利于降低电极组件的膨胀力，改善极片可能存在的受力不均的问题，而且省去第二弹性缓冲垫的设置还有利于简化电池单体结构，提高电池单体的能量密度。
在本申请的一些实施方式中，棱柱状电池单体中，在电池单体的厚度方向上，第一弹性缓冲垫13a在自由状态下的总厚度与电极组件12在满放电状态下的总厚度之和可以为壳体11内壁面之间的距离的80％～99％，可选为85％～98％，再可选为90％～95％；和/或，第一弹性缓冲垫13a在自由状态下的总厚度与电极组件12在满充电状态下的总厚度之和可以为壳体11内壁面之间的距离的95％～110％，可选为98％～105％，再可选为99％～102％。
参考图8理解，以方形电池单体为例，第一弹性缓冲垫13a在自由状态下的总厚度d与电极组件12在满放电状态下的总厚度d2之和可以为壳体11在沿其厚度方向上相对设置的两个内壁面之间的距离d0的80％～99％，即例如，的值可以为80％、82％、85％、87％、89％、91％、95％、97％、99％等，或者可以为以上任何数值所组成的范围。本申请中，满放电状态指室温下以电池单体额定容量的0.33C恒流进行放电至截止电压下限的状态。满足所给条件，可以使弹性缓冲垫与电极组件在入壳前与壳体之间存在间隙，有利于弹性缓冲垫和电极组件的顺利入壳，便于电池单体装配。可选地，再可选地，满足所给条件进一步有利于弹性缓冲垫和电极组件的顺利入壳，同时，还有利于实现电极组件在充电后与壳体内壁的直接或间接接触，改善极片的受力均匀性。
以方形电池单体为例，第一弹性缓冲垫13a在自由状态下的总厚度d与电极组件12在满充电状态下的总厚度d1之和可以为壳体11在沿其厚度方向上相对设置的两个内壁面之间的距离d0的95％～110％，即例如，的值可以为95％、97％、99％、100％、102％、104％、106％、108％、110％等，或者可以为以上任何数值所组成的范围。本申请中，满充电状态指室温下以电池单体额定容量的0.33C恒流充电至截止电压上限，再恒压充电直至电流为0.05C的状态，或在该条件下充电至电池的SOC不再变化的状态。满足所给条件，进一步有利于电池单体在使用过程中，使电极组件与壳体内壁直接贴合或通过弹性缓冲垫(或mylar膜，既绝缘膜)与壳体内壁贴合，实现相互作用力，进而有利于进一步改善极片的受力均匀性，降低电极组件局部区域产生褶皱以及在褶皱区域出现紫斑和析锂等 异常引发活性锂利用率下降的风险，改善电池单体的容量保持率。可选地，再可选地，满足所给条件可以在改善极片受力均匀性的同时，进一步降低电极组件可能对壳体产生的膨胀力。
满足所给条件既有利于电池单体的装配，还有利于改善电池单体的体积稳定性和极片的受力均匀性，进而有利于降低电池单体膨胀变形或性能恶化的风险。
在本申请的一些实施方式中，棱柱状电池单体中，在电池单体的长度方向上，第二弹性缓冲垫13b在自由状态下的总厚度与电极组件12在满放电状态下的长度之和可以为壳体11内壁面之间的距离的80％～99％，可选为85％～98％，再可选为90％～95％；和/或，第二弹性缓冲垫13b在自由状态下的总厚度与电极组件12在满充电状态下的长度之和可以为壳体11内壁面之间的距离的85％～110％，可选为98％～105％，再可选为99％～102％。
例如，参考图8理解，以方形电池单体为例，第二弹性缓冲垫13b在自由状态下的总厚度与电极组件12在满放电状态下的长度之和可以为壳体11在沿其长度方向上相对设置的两个内壁面之间的距离的80％、82％、85％、87％、89％、91％、95％、97％、99％等，或者可以为以上任何数值所组成的范围。其中，电极组件12在满放电状态下的长度方向和壳体内腔的长度方向如图8所示，本申请中，电极组件12的长度可以为在电池单体长度方向上的最大延伸距离。满足所给条件，可以使弹性缓冲垫与电极组件在入壳前与壳体之间存在间隙，有利于弹性缓冲垫和电极组件的顺利入壳，便于电池单体装配。可选地，第二弹性缓冲垫13b在自由状态下的总厚度与电极组件12在满放电状态下的长度之和可以为壳体11在沿其长度方向上相对设置的两个内壁面之间的距离的85％～98％，再可选为90％～95％，满足所给条件进一步有利于弹性缓冲垫和电极组件的顺利入壳，同时，还有利于实现电极组件在充电后与壳体内壁的直接或间接接触，改善极片的受力均匀性。
例如，参考图8理解，以方形电池单体为例，第二弹性缓冲垫13b在自由状态下的总厚度与电极组件12在满充电状态下的长度之和可以为壳体11在沿其长度方向上相对设置的两个内壁面之间的距离的95％、97％、99％、100％、102％、104％、106％、108％、110％等，或者可以为以上任何数值所组成的范围。满足所给条件，进一步有利于在使用过程中使电极组件与壳体内壁直接贴合或通过弹性缓冲垫(或mylar膜)与壳体内壁贴合，实现相互作用力，进而有利于进一步改善极片的受力均匀性，降低电极组件局部区域产生褶皱以及在褶皱区域出现紫斑和析锂等异常引发活性锂利用率下降的风险，改善电池单体的容量保持率。可选地，第二弹性缓冲垫13b在自由状态下的总厚度与电极组件12在满充电状态下的长度之和可以为壳体11在沿其长度方向上相对设置的两个内壁面之间的距离的98％～105％，再可选为99％～102％，满足所给条件可以在改善极片受力均匀性的同时，进一步降低电极组件可能对壳体产生的膨胀力。
满足所给条件既有利于电池单体的装配，还有利于改善电池单体的体积稳定性和极片的受力均匀性，进而有利于降低电池单体膨胀变形或性能恶化的风险。
在本申请的一些实施方式中，第一弹性缓冲垫13a在自由状态下的总厚度与电极组件12在满放电状态下的总厚度的比值可以为2％～25％，可选为5％～20％，再可选为8％～15％。
参考图8理解，第一弹性缓冲垫13a在自由状态下的总厚度d与电极组件12在满放电状态下的总厚度d2的比值可以为2％～25％，即2％≤d/d2≤25％，例如，d/d2的值可以为2％、3％、5％、7％、9％、11％、13％、15％、17％、19％、21％、23％、25％等，或者可以为以上任何数值所组成的范围。提高d/d2的值有利于提高弹性缓冲垫对电极组件产生的膨胀变形和膨胀力的吸收能力，有利于进一步抑制电池单体的膨胀变形。d/d2的值满足所给条件，既有利于维持电池单体在使用周期内尤其是使用后期的体积稳定性，还可以兼顾电池单体的能量密度。可选地，d/d2的值可以为5％～20％，再可选为8％～15％，满足所给条件有利于进一步兼顾电池单体在使用周期内尤其是使用后期的体积稳定性和能量密度。
满足所给条件既有利于维持电池单体的体积稳定，还可以兼顾电池单体的能量密度。
在本申请的一些实施方式中，第一弹性缓冲垫13a在自由状态下，在电极组件12长度方向上的延 伸距离与电极组件12长度的比值可以为0.8～1.2，可选为0.85～1.1，再可选为0.9～1.05；和/或，第一弹性缓冲垫13a在自由状态下，在电极组件12高度方向上的延伸距离与电极组件12高度的比值可以为0.8～1.2，可选为0.85～1.1，再可选为0.9～1.05。
参考图8理解，第一弹性缓冲垫13a在自由状态下，在电极组件12长度方向上的延伸距离与电极组件12长度的比值可以为0.8、0.85、0.9、0.95、1、1.05、1.1、1.15、1.2等，或者可以为以上任何数值所组成的范围。该比值中，电极组件的长度指的是电极组件在满充状态下沿电池单体长度方向上的最大延伸距离，电极组件的长度和第一弹性缓冲垫在自由状态下在电极组件长度方向上的延伸距离可以通过常规方法和常规仪器测得。
参考图8理解，第一弹性缓冲垫13a在自由状态下，在电极组件12高度方向上的延伸距离与电极组件12高度的比值可以为0.8～1.2，0.8、0.85、0.9、0.95、1、1.05、1.1、1.15、1.2等，或者可以为以上任何数值所组成的范围。该比值中，电极组件的高度指的是电极组件在满充状态下沿电池单体高度方向上的最大延伸距离，电极组件的高度和第一弹性缓冲垫在自由状态下在电极组件高度方向上的延伸距离可以通过常规方法和常规仪器测得。
第一弹性缓冲垫与电极组件的尺寸满足所给条件，有利于使弹性缓冲垫能够覆盖电极组件的大部分区域，既有利于改善电池单体的体积稳定性，还有利于进一步改善极片的受力均匀性，降低电池单体性能恶化的风险。
在本申请的一些实施方式中，参考图8理解，第一弹性缓冲垫13a在电极组件12上的正投影可以位于电极组件12所在的区域内。第一弹性缓冲垫满足所给条件，既有利于弹性缓冲垫在装配过程中顺利入壳，还有利于进一步兼顾电池的能量密度。
在本申请的一些实施方式中，参考图9和图10理解，电池单体1可以为圆柱形电池单体，至少一个弹性缓冲垫13和电极组件12沿电极组件12的半径方向层叠设置，壳体11内壁面之间的距离等于壳体11的内腔直径。即，电极组件12的厚度可以沿其径向方向延伸，壳体11内壁面之间的距离可以等于或略微小于壳体11的内腔直径，示例性的，壳体11内壁面之间的距离与壳体11的内腔直径的差值可以小于或等于2％，可选小于或等于1％。圆柱形电池单体中通常仅包括一个卷绕电极组件，可以将弹性缓冲垫设在卷绕电极组件的内部，使电极组件的叠片单元围绕弹性缓冲垫开始卷绕；和/或，可以将弹性缓冲垫设在卷绕电极组件和壳体之间。本申请中，壳体11的内腔直径可以理解为壳体内腔的平均直径。
在本申请的一些实施方式中，圆柱形电池单体中，弹性缓冲垫13在自由状态下的总厚度与电极组件12在满放电状态下的总厚度之和可以为壳体11内腔直径的80％～99％，可选为85％～98％，再可选为90％～95％；和/或，弹性缓冲垫13在自由状态下的总厚度与电极组件12在满充电状态下的总厚度之和可以为壳体11内腔直径的85％～110％，可选为98％～105％，再可选为99％～102％。
示例性的，参考图9理解，弹性缓冲垫13在自由状态下的总厚度与电极组件12在满放电状态下(或满放电状态下)的总厚度可以理解为电极组件的平均直径加上两倍的单层弹性缓冲垫13在自由状态下的厚度；图10中，弹性缓冲垫13在自由状态下的总厚度与电极组件12在满放电状态下(或满放电状态下)的总厚度可以理解为弹性缓冲垫13的平均直径加上两倍的电极组件的厚度。本申请中，壳体11的内腔直径可以理解为壳体内腔的平均直径，可以采用常规方法和常规仪器测得。
参考图9和图10理解，圆柱形电池单体中，弹性缓冲垫13在自由状态下的总厚度与电极组件12在满放电状态下的总厚度之和可以为壳体11内腔直径的80％、82％、85％、87％、89％、91％、95％、97％、99％等，或者可以为以上任何数值所组成的范围，满足所给条件，可以使弹性缓冲垫与电极组件在入壳前与壳体之间存在间隙，有利于弹性缓冲垫和电极组件的顺利入壳，便于电池单体装配。弹性缓冲垫13在自由状态下的总厚度与电极组件12在满充电状态下的总厚度之和可以为壳体11内腔直径的95％、97％、99％、100％、102％、104％、106％、108％、110％等，或者可以为以上任何数值所组成的范围，满足所给条件，进一步有利于电池单体使用过程中，使电极组件与壳体内壁直接贴合或通过弹性缓冲垫(或mylar膜)与壳体内壁贴合，实现相互作用力，进而有利于进一步改善极片的受力均匀性，降低电极组件局部区域产生褶皱以及在褶皱区域出现紫斑和析锂等异常引发活性锂利用率下降的 风险，改善电池单体的容量保持率。
满足所给条件既有利于电池单体的装配，还有利于改善电池单体的体积稳定性和极片的受力均匀性，进而有利于降低电池单体膨胀变形或性能恶化的风险。
在本申请的一些实施方式中，圆柱形电池单体中，弹性缓冲垫13可以设在电极组件12与壳体11之间，弹性缓冲垫13在自由状态下，在电极组件12周向上的延伸距离与电极组件12的周长的比值可以为0.8～1.2，可选为0.85～1.1，再可选为0.9～1.05；和/或，弹性缓冲垫13在自由状态下，在电极组件12高度方向上的延伸距离与电极组件12高度的比值可以为0.8～1.2，可选为0.85～1.1，再可选为0.9～1.05。
参考图9理解，弹性缓冲垫13在自由状态下，在电极组件12周向上的延伸距离与电极组件12的周长的比值可以为0.8、0.85、0.9、0.95、1、1.05、1.1、1.15、1.2等，或者可以为以上任何数值所组成的范围，该比值中，电极组件的周长指的是电极组件在满充状态下的平均周长。弹性缓冲垫13在自由状态下，在电极组件12高度方向上的延伸距离与电极组件12高度的比值可以为0.8、0.85、0.9、0.95、1、1.05、1.1、1.15、1.2等，或者可以为以上任何数值所组成的范围，该比值中，电极组件的高度指的是电极组件在满充状态下沿电池单体高度方向上的最大延伸距离。本申请中，电极组件的周长、高度，以及弹性缓冲垫13在自由状态下在电极组件周向或高度上的延伸距离均可以通过常规方法和常规仪器测得。
第一弹性缓冲垫与电极组件的尺寸满足所给条件，有利于使弹性缓冲垫能够覆盖电极组件的大部分区域，既有利于改善电池单体的体积稳定性，还有利于进一步改善极片的受力均匀性，降低电池单体性能恶化的风险。
在本申请的一些实施方式中，圆柱形电池单体中，弹性缓冲垫13在自由状态下，在电极组件12周向上的延伸距离小于或等于电极组件12的周长；和/或，弹性缓冲垫13在自由状态下，在电极组件12高度方向上的延伸距离小于或等于电极组件12的高度。弹性缓冲垫满足所给条件，既有利于弹性缓冲垫在装配过程中顺利入壳，还有利于进一步兼顾电池的能量密度。
在本申请的一些实施方式中，单个弹性缓冲垫13在自由状态下的厚度可以为单个电极组件12在满放电状态下的厚度的2％～15％，可选为5％～10％。例如，单个弹性缓冲垫13在自由状态下的厚度可以为单个电极组件12在满放电状态下的厚度的2％、3％、5％、7％、9％、11％、13％、15％等，或者可以为以上任何数值所组成的范围。满足所给条件，既有利于维持电池单体在使用周期内尤其是使用后期的体积稳定性，还可以兼顾电池单体的能量密度。
在本申请的一些实施方式中，单个弹性缓冲垫13在自由状态下的厚度可以为0.2mm～10.5mm。例如，单个弹性缓冲垫13在自由状态下的厚度可以为0.2mm、0.5mm、1mm、2mm、3mm、4mm、5mm、6mm、7mm、8mm、9mm、10mm、10.5mm等，或者可以为以上任何数值所组成的范围。满足所给条件，既可以兼顾弹性缓冲垫的可压缩形变量和电池单体的能量密度，还能使支撑层具有一定的强度。
可以理解的是，本申请第一方面的电池单体中，弹性缓冲垫的结构及材质并不受特别限制，只要其在预设压力下沿其厚度方向的压缩率能够满足所给的要求即可，示例性的，可以调控弹性缓冲垫的材质、孔隙率和孔径等中的至少之一来获得不同应力应变关系的弹性缓冲垫，实现弹性缓冲垫在预设压力下沿其厚度方向的压缩率不同。
示例性的，弹性缓冲垫可以为单层结构，其材质可以包括但不限于发泡聚乙烯、聚丙烯、聚氨酯、硅橡胶等中的至少之一。
示例性的，弹性缓冲垫可以为多层结构，具体可以包括弹性缓冲层和支撑层，支撑层可以设在弹性缓冲层沿其厚度方向的两侧中的至少一侧上，示例性的，电池单体中，至少一个弹性缓冲垫包括一层弹性缓冲层和一层支撑层，和/或，至少一个弹性缓冲垫包括一层弹性缓冲层和两层支撑层。可选地，弹性缓冲层的弹性模量小于支撑层的弹性模量，和/或，在相同的压力下弹性缓冲层沿其厚度方向的压缩率大于支撑层沿其厚度方向的压缩率，和/或，弹性缓冲层的孔隙率可以大于支撑层的孔隙率，例如，弹性缓冲层31的孔隙率可以为40％～95％，可选为55％～90％，再可选为70％～85％，支撑层32的孔隙率可以小于或等于5％。再可选地，弹性缓冲层可以包括发泡聚乙烯、聚丙烯、聚氨酯、硅橡胶中的至 少之一，支撑层可以包括但不限于高密度聚乙烯、聚甲基丙烯酸酯、聚对苯二甲酸乙二醇酯、聚四氟乙烯中的至少之一。又可选地，还可以满足以下条件中的至少之一：弹性缓冲层的厚度可以大于支撑层的厚度；单个弹性缓冲垫中，支撑层的总厚度与弹性缓冲层的自由厚度的比值可以为0.005～0.1，如可以为0.02～0.05；弹性缓冲层在自然状态下的厚度可以为0.2mm～10mm，单层支撑层的厚度可以为30μm～200μm；弹性缓冲层与支撑层可以粘结相连。其中，利用支撑层与弹性缓冲层复合可以给予弹性缓冲层支撑，不仅可以抑制弹性缓冲层的热收缩(如在真空烘烤过程中的热收缩)，可选利用支撑层抑制弹性缓冲层在与其厚度方向垂直的二维方向上的热收缩，改善其因热收缩而失去原有作用的问题，同时还能改善弹性缓冲垫在电池使用后期因机械应力导致的材料破损问题。进而，将该弹性缓冲垫置于电池单体内部有利于进一步改善电池在长期使用过程中的体积稳定性，提高长期使用性能。
在本申请的一些实施例中，电极组件12可以包括正极极片、负极极片、隔离膜，正极极片、负极极片和隔离膜可以经卷绕工艺形成电极组件。在电池充放电过程中，活性离子在正极极片和负极极片之间往返嵌入和脱出。隔离膜设置在正极极片和负极极片之间，起到隔离的作用。
[正极极片]
在电池中，正极极片通常包括正极集流体及设置在正极集流体上的正极活性物质层，正极活性物质层包括正极活性材料。正极集流体可以采用常规金属箔片或复合集流体(可以将金属材料设置在高分子基材上形成复合集流体)。作为示例，正极集流体可以采用铝箔。
本申请中，正极活性材料的具体种类不做限制，可以采用本领域已知的能够用于电池正极的活性材料，本领域技术人员可以根据实际需求进行选择。例如，正极活性材料可以包括但不限于锂过渡金属氧化物和/或橄榄石结构的含锂磷酸盐的正极活性材料，所述锂过渡金属氧化物可以包括未掺杂和/或可选掺杂改性的锂过渡金属氧化物、未包覆和/或包覆改性的锂过渡金属氧化物，所述橄榄石结构的含锂磷酸盐可以包括未掺杂和/或可选掺杂改性的橄榄石结构的含锂磷酸盐、未包覆和/或包覆改性的橄榄石结构的含锂磷酸盐。所给范围内的正极活性材料既可以通过制备得到，也可以通过商业途径获得。
在本申请的一些具体实施例中，正极活性物质层还可以可选地包括粘结剂、导电剂和其他可选助剂。作为示例，导电剂可以包括但不限于超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、Super P(SP)、石墨烯及碳纳米纤维中一种或几种。作为示例，粘结剂可以包括但不限于丁苯橡胶(SBR)、水性丙烯酸树脂(water-based acrylic resin)、聚偏二氟乙烯(PVDF)、聚四氟乙烯(PTFE)、乙烯-醋酸乙烯酯共聚物(EVA)、聚丙烯酸(PAA)、羧甲基纤维素(CMC)、聚乙烯醇(PVA)及聚乙烯醇缩丁醛(PVB)中的一种或几种。
[负极极片]
在电池中，负极极片通常包括负极集流体及设置在负极集流体上的负极活性物质层，负极活性物质层包括负极活性材料。负极集流体可以采用常规金属箔片或复合集流体(例如可以将金属材料设置在高分子基材上形成复合集流体)。作为示例，负极集流体可以采用铜箔。
在本申请的一些实施例中，本申请第一方面的电池单体可以为锂离子电池单体，此时负极活性材料的具体种类不做限制，可以采用本领域已知的能够用于电池负极的活性材料，本领域技术人员可以根据实际需求灵活选择。作为示例，负极活性材料可以包括但不限于人造石墨、天然石墨、硬碳、软碳、硅基材料和锡基材料中的一种或几种。可选地，硅基材料可以包括单质硅、硅氧化合物(例如氧化亚硅)、硅碳复合物、硅氮复合物、硅合金中的一种或几种。再可选地，锡基材料可以包括单质锡、锡氧化合物、锡合金中的一种或几种。所给范围内的负极活性材料既可以通过制备得到，也可以通过商业途径获得。
在本申请的一些具体实施例中，负极活性物质层还可以可选地包括粘结剂、导电剂和其他可选助剂。作为示例，导电剂可以包括但不限于超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中一种或几种。作为示例，粘结剂可以包括但不限于丁苯橡胶(SBR)、水性丙烯酸树脂(water-based acrylic resin)、聚偏二氟乙烯(PVDF)、聚四氟乙烯(PTFE)、乙烯-醋酸乙烯酯共聚物(EVA)、聚乙烯醇(PVA)及聚乙烯醇缩丁醛(PVB)中的一种或几种。作为示例，其他可选助剂可以包括但不限于增稠剂及分散剂(例如羧甲基纤维素钠CMC-Na)、PTC热敏电阻材料。
在本申请的一些实施例中，电池中的隔离膜可以包括但不限于聚乙烯多孔膜、聚丙烯多孔膜、聚酰亚胺多孔膜以及多种聚合物复合形成的多孔膜。
本申请的第二方面提供了一种电池，其包括：本申请第一方面所述的电池单体。可选地，该电池可以为二次电池，例如该电池可以是锂离子二次电池等。
在本申请的一些实施例中，电池既可以为电池单体1(参考图11理解)，也可以为由电池单体1组成的电池模块2(参考图12理解)或电池包3(参考图13理解)。
在一些实施方式中，电池可以为电池模块，电池模块所含的电池单体的数量可以为一个或多个，具体数量可根据电池模块的应用和容量来调节。如图12是作为一个示例的电池模块2。参照图12，在电池模块2中，多个电池单体1可以是沿电池模块2的长度方向依次排列设置。当然，也可以按照其他任意的方式进行排布。进一步可以通过紧固件对该多个电池单体1进行固定。可选地，电池模块2还可以包括具有容纳空间的外壳，多个电池单体1容纳于该容纳空间。
在一些实施方式中，上述电池模块还可以组装成电池包，电池包所含的电池模块的数量可以根据电池包的应用和容量进行调节。参照图13或图14(图13和图14为作为一个示例的电池包3)，在电池包3中可以包括电池箱和设置于电池箱中的多个电池模块2。电池箱可以包括上箱体4和下箱体5，上箱体4能够盖设于下箱体5，并形成用于容纳电池模块2的封闭空间。多个电池模块2可以按照任意的方式排布于电池箱中。
在一些实施方式中，电池可以包括第一电池单体组件和至少两个第二电池单体组件，第一电池单体组件包括至少一个本申请第一方面的电池单体1，第二电池单体组件包括至少两个第二电池单体，所述至少两个第二电池单体沿第一电池单体组件的厚度方向分设在第一电池单体组件的两侧，第一电池单体组件的厚度方向与电池单体1的厚度方向一致。可选地，本申请第一方面的电池单体为具有卷绕电极组件的棱柱状电池单体，通过将棱柱状壳体、卷绕电极组件和弹性缓冲垫结合，可以缓解棱柱状卷绕电池中极片受力不均的问题，改善电池单体的稳定性。其中，所述电池既可以为电池模组，也可以为电池包。示例性的，以第一电池单体组件的长度方向为排，以第一电池单体组件的厚度方向为列，所述电池模组或所述电池包中，第一电池单体组件可以包括多个成排和/或成列布置的电池单体1，和/或，第一电池单体组件沿其厚度方向的两侧可以分别独立地设有多个成排和/或成列布置的第二电池单体，可选地，至少两个第二电池单体可以沿第一电池单体组件的厚度方向对称布置在第一电池单体组件的两侧；再可选地，所述电池模组或所述电池包中，以电池单体1和第二电池单体的总数量为基准，电池单体1的数量占比可以为30％～70％。电池中通常包括多个电池单体，多个电池单体的叠放方式包括沿电池单体的厚度方向叠放，而在电池单体的厚度方向上，位于电池中部的电池单体往往为在使用过程中膨胀最严重、膨胀力最大的部分，通过仅在位于中部的第一电池单体中内置第一弹性缓冲垫，而在位于第一电池单体组件厚度方向的两侧的第二电池单体中不设弹性缓冲垫，不仅有利于吸收电池中膨胀相对更严重、膨胀力相对更大的电池单体的体积膨胀，降低电池中部电池单体的膨胀力，改善电池的体积稳定性，还有利于缓解电池使用后期因电池单体体积膨胀导致位于电池中部的电池单体产生应力集中进而引发中部电池单体析锂跳水的问题；同时，还能兼顾电池的高能量密度。
另外，本申请还提供了一种用电装置，其包括：本申请第二方面的电池。所述电池，如电池单体、电池模块或电池包，既可以作为该用电装置的电源，也可以作为该用电装置的能量存储单元。该用电装置可以包括但不限于是移动设备(例如手机、笔记本电脑)、电动车辆(例如纯电动车、混合动力电动车、插电式混合动力电动车、电动自行车、电动踏板车、电动高尔夫球车、电动卡车等)、电气列车、船舶及卫星、储能系统。参考图15理解，作为一个具体示例，该用电装置可以为车辆。用电装置可以根据其使用需求来选择电池的具体种类，如可以选择电池单体、电池模块或电池包。
作为一个示例，该用电装置可以为纯电动车、混合动力电动车、或插电式混合动力电动车。为了满足该用电装置对电池的高功率和高能量密度的需求，可以采用电池包或电池模块。
作为另一个示例，该用电装置可以是手机、平板电脑、笔记本电脑。该用电装置通常要求轻薄化，可以采用电芯作为电源。
以下，说明本申请的实施例。下面描述的实施例是示例性的，仅用于解释本申请，而不能理解为 对本申请的限制。实施例中未注明具体技术或条件的，按照本领域内的文献所描述的技术或条件或者按照产品说明书进行。所用试剂或仪器未注明生产厂商者，均为可以通过市购获得的常规产品。
实施例1
(一)锂二次电池的制备
(1)正极极片制备
将正极活性物质LiNi0.6Co0.1Mn0.3O2、导电剂Super P、粘结剂PVDF按重量比96:2:2进行混合，加入溶剂N-甲基吡咯烷酮，充分搅拌混合均匀得到正极浆料，然后涂覆于厚度为13μm正极集流体铝箔的两个表面上，正极浆料在铝箔单侧上的涂布面密度为20mg/cm2，然后烘干、冷压，得到正极极片。
(2)负极极片制备
将负极活性物质人造石墨、导电剂Super P、粘结剂丁苯橡胶，增稠剂羧甲基纤维素钠按照重量比96:0.5:2:1.5进行混合，加入溶剂去离子水，充分搅拌混合均匀得到负极浆料，然后涂覆于厚度为6μm负极集流体铜箔的两个表面上，其负极浆料在铜箔单侧上的涂布厚度为100μm、负极浆料的在铜箔单侧上的涂布面密度为11mg/cm2，然后烘干、冷压，得到负极极片。
(3)电解液的制备
在含水量<10ppm的氩气气氛手套箱中，将溶剂EC(碳酸乙烯酯)、PC(碳酸丙烯酯)、DMC(碳酸二甲酯)按照1:1:1比例混合后再将充分干燥的锂盐LiPF6溶解于上述混合有机溶剂中，搅拌均匀后得到电解液，其中LiPF6的浓度为1mol/L。
(4)隔离膜的制备
以厚度为7μm聚乙烯多孔膜作为隔离膜。
(5)弹性缓冲垫的制备
以自由状态下厚度为3mm的聚丙烯作为弹性缓冲垫。
(6)锂二次电池的制备
将正极极片、隔离膜、负极极片按顺序叠好，使隔离膜处于正负极极片中间起到隔离的作用，并卷绕、成型得到电极组件。将两个电极组件和弹性缓冲垫置于电池壳体(沿其厚度方向相对设置的两个内壁面之间的距离d0为60mm)中，并在两个电极组件之间夹设一层弹性缓冲垫，注入配好的电解液并封装，获得锂离子锂二次电池。
实施例2～19及对比例1～3
实施例2～19及对比例1～3与实施例1的区别详见表1。其中，实施例1～19和对比例1～3中的弹性缓冲垫均为多孔结构，相同材质的弹性缓冲垫在相同应力下的压缩率不同由于弹性缓冲垫的孔隙率和孔径不同引起的；另外，实施例7～8中的弹性缓冲垫均是将聚丙烯和聚乙烯按照质量比为1：1混合并进行熔融造孔得到，实施例7和实施例8中弹性缓冲垫的孔隙率和孔径不同。
(二)电池测试方法
(a)测试电池及电极组件的尺寸及弹性缓冲垫的压缩率
取两组二次电池平行样品，将两组二次电池在25℃下静止5分钟后以0.33C的电流恒流充电至4.4V，再以4.4V的恒压充电至0.05C，静置5分钟。将其中一组二次电池进行拆解得到电极组件，对电极组件进行清洗、干燥后测试电极组件厚度，以及电极组件的长度L1和高度h1(电极组件的长度和高度分别二次电池壳体长度方向和高度方向匹配；注：圆柱电池电极组件和二次电池的长度以周长记)；将另一组二次电池0.33C恒流进行放电至2.8V，静置5分钟，之后对二次电池进行拆解得到电极组件，对电极组件进行清洗、干燥后测试电极组件厚度。其中，测试方法为：将电极组件置于两块平行的平板中间，利用平板向电极组件施加0.1MPa的压力，测量平板间距即得到电极组件的厚度。计算二次电池中电极组件在满充电状态下的总厚度d1和电极组件在满放电状态下的总厚度d2。
弹性缓冲垫在自由状态下的厚度采用MitutoyoID-C112MX千分尺测厚仪，在测试力小于或等于1.8N的状态下进行测试，随机测量多个点(如5、10个等)取平均值，计算二次电池中弹性缓冲垫在自由状态下的总厚度d，并测试弹性缓冲垫的长度L2和高度h2(弹性缓冲垫的长度和高度分别电极组件的长度方向和高度方向匹配)；将弹性缓冲垫置于两块平行的平板中间，利用平板分别向弹性缓冲垫 施加0.1MPa、0.5MPa的压力，测量平板间距即得到电极组件在压应力下厚度，弹性缓冲垫在压应力下沿其厚度的压缩率为弹性缓冲垫在自由状态与压应力状态下的厚度变化与在自由状态下厚度的比值乘以100％。
(b)测试二次电池的容量保持率
取多个二次电池平行样品，将二次电池在25℃下静置5分钟后以0.5C恒流充电至4.4V，再以4.4V恒压充电至0.05C，静置5分钟，然后将二次电池以0.33C恒流放电至2.8V，静置5分钟，记录放电容量C0。重复上述操作，通过下式计算电池容量保持率：n次循环后二次电池的容量保持率(％)＝Cn/C0×100％。记录循环n次后的电池容量保持率。
(c)电池单体膨胀力测试
将二次电池在25℃下静置5分钟后0.5C恒流充电至4.4V，再以4.4V恒压充电至0.05C，静置5分钟。然后将二次电池以0.33C恒流放电至2.8V，静止5分钟。在的厚度方向的一侧不同位置设置6个压力传感器，以0.5C恒流充电至4.4V，再以4.4V恒压充电至0.05C，静置5分钟，期间在充电至30％SOC、50％SOC、100％SOC，分别记录二次电池不同位置处压力传感器显示的膨胀力，计算不同充电状态下膨胀力的平均值，并以该平均值为基准计算不同充电状态下各膨胀力相比于平均值的变化率范围。
(d)析锂跳水测试
将二次电池在25℃下静置5分钟后0.5C恒流充电至4.4V，再以4.4V恒压充电至0.05C，静置5分钟。然后将二次电池以0.33C恒流放电至2.8V，静止5分钟。重复上述充放电循环，直至二次电池容量有显著衰减。充放电循环测试完成后，对二次电池进行拆解，观测负极极片上是否存在析锂现象。
对实施例1～19和对比例1～3进行相关测试，测试结果详见表2。
结论：
综合实施例1～19及对比例1～3和表1～2可知，采用本申请上述实施例的方案有利于改善电池单体和极片在充放电过程中的体积稳定性和受力均匀性，降低其膨胀变形或性能恶化的风险。并且，通过进一步调控弹性缓冲垫在自由状态下的总厚度d和电极组件在满充(放)电状态下的总厚度d1(d2)之和与壳体沿其厚度方向相对设置的两个内壁面之间的距离d0的比值、以及弹性缓冲垫相对于电极组件尺寸大小也有利于进一步改善电池单体在长期使用过程中的体积稳定性和受力均匀性，降低其膨胀变形或性能恶化的风险。
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 (18)

  1. 一种电池单体，其中，包括：
    壳体；
    至少一个电极组件，所述电极组件置于所述壳体内；
    至少一个弹性缓冲垫，所述弹性缓冲垫设在所述电极组件的至少部分表面和/或所述电极组件内部，所述弹性缓冲垫在0.1Mpa的压力下沿其厚度方向的压缩率≤30％、在1Mpa的压力下沿其厚度方向的压缩率≥50％。
  2. 根据权利要求1所述的电池单体，其中，所述电极组件与所述壳体之间设有所述弹性缓冲垫，和/或相邻两个所述电极组件之间设有所述弹性缓冲垫。
  3. 根据权利要求1或2所述的电池单体，其中，所述弹性缓冲垫在0.1Mpa的压力下沿其厚度方向的压缩率≤20％，可选≤10％；和/或，
    所述弹性缓冲垫在1Mpa的压力下沿其厚度方向的压缩率≥60％，可选≥80％。
  4. 根据权利要求1～3中任一项所述的电池单体，其中，所述弹性缓冲垫在0.5Mpa压力下的压缩率为30％～60％。
  5. 根据权利要求1～4中任一项所述的电池单体，其中，所述电极组件为卷绕电极组件，且包括平直部和拐角部，所述弹性缓冲垫设在所述平直部和/或所述拐角部的至少部分表面。
  6. 根据权利要求1～5中任一项所述的电池单体，其中，所述电池单体为棱柱状电池单体。
  7. 根据权利要求6所述的电池单体，其中，所述电池单体包括：至少一个第一弹性缓冲垫和/或至少一个第二弹性缓冲垫，所述第一弹性缓冲垫和所述电极组件沿所述电池单体的厚度方向层叠设置，和/或，所述第二弹性缓冲垫和所述电极组件沿所述电池单体的长度方向层叠设置。
  8. 根据权利要求7所述的电池单体，其中，满足以下条件中的至少之一：
    在所述电池单体的厚度方向上，所述第一弹性缓冲垫在自由状态下的总厚度与所述电极组件在满放电状态下的总厚度之和为所述壳体内壁面之间的距离的80％～99％，可选为85％～98％，再可选为90％～95％；
    在所述电池单体的厚度方向上，所述第一弹性缓冲垫在自由状态下的总厚度与所述电极组件在满充电状态下的总厚度之和为所述壳体内壁面之间的距离的95％～110％，可选为98％～105％，再可选为99％～102％；
    在所述电池单体的长度方向上，所述第二弹性缓冲垫在自由状态下的总厚度与所述电极组件在满放电状态下的长度之和为所述壳体内壁面之间的距离的80％～99％，可选为85％～98％，再可选为90％～95％；
    在所述电池单体的长度方向上，所述第二弹性缓冲垫在自由状态下的总厚度与所述电极组件在满充电状态下的长度之和为所述壳体内壁面之间的距离的95％～110％，可选为98％～105％，再可选为99％～102％。
  9. 根据权利要求7或8所述的电池单体，其中，所述第一弹性缓冲垫在自由状态下的总厚度与所述电极组件在满放电状态下的总厚度的比值为2％～25％，可选为5％～20％，再可选为8％～15％。
  10. 根据权利要求7～9中任一项所述的电池单体，其中，所述第一弹性缓冲垫在自由状态下，在所述电极组件长度方向上的延伸距离与所述电极组件长度的比值为0.8～1.2，可选为0.85～1.1，再可选为0.9～1.05；和/或，
    所述第一弹性缓冲垫在自由状态下，在所述电极组件高度方向上的延伸距离与所述电极组件高度的比值为0.8～1.2，可选为0.85～1.1，再可选为0.9～1.05。
  11. 根据权利要求7～10中任一项所述的电池单体，其中，所述第一弹性缓冲垫在所述电极组件上的正投影位于所述电极组件所在的区域内。
  12. 根据权利要求1～5中任一项所述的电池单体，其中，所述电池单体为圆柱形电池单体，至少 一个所述弹性缓冲垫和所述电极组件沿所述电极组件的半径方向层叠设置，所述壳体内壁面之间的距离等于所述壳体内腔直径。
  13. 根据权利要求12所述的电池单体，其中，所述弹性缓冲垫在自由状态下的总厚度与所述电极组件在满放电状态下的总厚度之和为所述壳体内腔直径的80％～99％，可选为85％～98％，再可选为90％～95％；和/或，
    所述弹性缓冲垫在自由状态下的总厚度与所述电极组件在满充电状态下的总厚度之和为所述壳体内腔直径的85％～110％，可选为98％～105％，再可选为99％～102％。
  14. 根据权利要求12或13所述的电池单体，其中，所述弹性缓冲垫设在所述电极组件与所述壳体之间，所述弹性缓冲垫在自由状态下，在所述电极组件周向上的延伸距离与所述电极组件的周长的比值为0.8～1.2，可选为0.85～1.1，再可选为0.9～1.05；和/或，
    所述弹性缓冲垫在自由状态下，在所述电极组件高度方向上的延伸距离与所述电极组件高度的比值为0.8～1.2，可选为0.85～1.1，再可选为0.9～1.05。
  15. 根据权利要求14所述的电池单体，其中，所述弹性缓冲垫在自由状态下，在所述电极组件周向上的延伸距离小于或等于所述电极组件的周长；和/或，所述弹性缓冲垫在自由状态下，在所述电极组件高度方向上的延伸距离小于或等于所述电极组件的高度。
  16. 根据权利要求1～15中任一项所述的电池单体，其中，单个所述弹性缓冲垫在自由状态下的厚度为单个所述电极组件在满放电状态下的厚度的2％～15％，可选为5％～10％；和/或，
    单个所述弹性缓冲垫在自由状态下的厚度为0.2mm～10.5mm。
  17. 一种电池，其中，包括权利要求1～16中任一项所述的电池单体。
  18. 一种用电装置，其中，包括权利要求17所述的电池。
PCT/CN2023/120508 2023-09-21 2023-09-21 电池单体、电池和用电装置 Ceased WO2025060008A1 (zh)

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