Single battery, energy storage device and energy storage system

Abstract

The invention provides a single battery, an energy storage device and an energy storage system. The single battery comprises a battery cell assembly, the battery cell assembly comprises a plurality of roll cores which are arranged in sequence, the roll cores are connected in parallel, and the battery cell assembly is provided with a first surface and a second surface which are arranged back to back in the arrangement direction of the roll cores; the first heat insulation film is arranged on the side, away from the second face, of the first face.

Description

Technical Field

[0001] This application relates to the field of energy storage, specifically to a single battery cell, an energy storage device, and an energy storage system. Background Technology

[0002] In related technologies, when a single battery cell in an energy storage device experiences thermal runaway, it is prone to excessive instantaneous gas production rate and low instantaneous gas exhaust rate. This causes the casing of the single battery cell to deform due to pressure difference, leading to casing breakage and failure, or even fire and ignition failure, thus reducing the safety of the single battery cell in use. Summary of the Invention

[0003] Therefore, this application provides a single-cell battery with high safety.

[0004] A first aspect of this application provides a single-cell battery, the single-cell battery comprising:

[0005] A battery cell assembly, comprising a plurality of wound cores arranged sequentially and connected in parallel, wherein the battery cell assembly has a first side and a second side disposed opposite to each other along the arrangement direction of the plurality of wound cores; and

[0006] A first heat insulation film is disposed on the side of the first surface that is opposite to the second surface.

[0007] Furthermore, the single-cell battery also includes:

[0008] An insulating film that wraps around the outer periphery of the winding core;

[0009] The first heat insulation film is disposed between the insulating film and the battery cell assembly, or the first heat insulation film is disposed on the side of the insulating film away from the battery cell assembly.

[0010] Furthermore, the single-cell battery also includes:

[0011] The housing has a receiving cavity with one end open, and the battery cell assembly, the first heat insulation film and the insulating film are all housed in the receiving cavity;

[0012] When the first heat insulation film is disposed on the side of the insulating film away from the cell assembly, the first heat insulation film is disposed on the surface of the insulating film away from the cell assembly, or the first heat insulation film is disposed on the surface of the housing facing the cell assembly;

[0013] When the first heat insulation film is disposed between the insulating film and the battery cell assembly, the first heat insulation film is disposed on the surface of the insulating film facing the battery cell assembly, or the first heat insulation film is disposed on the surface of the battery cell assembly.

[0014] Furthermore, the first heat insulation film includes at least one of polyimide film, mica paper, and two-dimensional transition metal carbonitride nanocoating.

[0015] Furthermore, the polyimide film comprises a polyimide matrix and a heat-insulating filler, wherein the heat-insulating filler is dispersed in the polyimide matrix, and the heat-insulating filler comprises at least one of silica aerogel, hollow glass microspheres, hollow ceramic microspheres, boron nitride, ceramic fiber felt, glass fiber, and reflective foil;

[0016] The mica paper includes at least one of aerogel-mica composite material and fiber composite mica paper.

[0017] Furthermore, the single cell also includes a second heat insulation film, which is disposed on the side of the second surface opposite to the first surface, and the thermal diffusivity of the first heat insulation film is different from that of the second heat insulation film.

[0018] Furthermore, the thickness of the first heat insulation film is different from the thickness of the second heat insulation film.

[0019] Furthermore, the thermal conductivity of the first heat insulation film is different from that of the second heat insulation film.

[0020] Furthermore, the single-cell battery also includes:

[0021] An insulating film that wraps around the outer periphery of the winding core;

[0022] The second heat insulation film is disposed between the insulating film and the battery cell assembly, or the second heat insulation film is disposed on the side of the insulating film away from the battery cell assembly.

[0023] Furthermore, the single-cell battery also includes:

[0024] The housing has a receiving cavity with one end open, and the battery cell assembly, the first heat insulation film, the second heat insulation film and the insulating film are all received in the receiving cavity;

[0025] When the second heat insulation film is disposed on the side of the insulating film away from the cell assembly, the second heat insulation film is disposed on the surface of the insulating film away from the cell assembly, or the second heat insulation film is disposed on the surface of the housing facing the cell assembly;

[0026] When the second heat insulation film is disposed between the insulating film and the battery cell assembly, the second heat insulation film is disposed on the surface of the insulating film facing the battery cell assembly, or the second heat insulation film is disposed on the surface of the battery cell assembly.

[0027] Furthermore, the battery cell assembly includes at least four winding cores, each winding core having a side surface that is arc-shaped;

[0028] The maximum distance between the side and the shell is d, then 1mm≤d≤6mm;

[0029] And / or,

[0030] The radius of curvature R of the side surface is in the range of 5mm≤R≤10mm.

[0031] Furthermore, along the extension plane of the first surface, the area of ​​the first heat insulation film is greater than or equal to the area of ​​the first surface; and / or, along the extension plane of the second surface, the area of ​​the second heat insulation film is greater than or equal to the area of ​​the second surface.

[0032] A second aspect of this application provides an energy storage device comprising one or more single-cell batteries as described in the embodiments of this application.

[0033] A third aspect of this application provides an energy storage system, comprising: a high-voltage cable, a first power conversion device, a second power conversion device, and the energy storage device described in this application embodiment; the high-voltage cable is electrically connected to the energy storage device, the first power conversion device, and the second power conversion device, the first power conversion device and the second power conversion device being used to generate electrical energy, and the energy storage device being used to store the electrical energy.

[0034] The single-cell battery of this application embodiment includes a cell assembly and a first heat-insulating film. The cell assembly includes a plurality of wound cores arranged in sequence and connected in parallel. Along the arrangement direction of the plurality of wound cores, the cell assembly has a first side and a second side disposed opposite to each other; the first heat-insulating film is disposed on the side of the first side opposite to the second side. Because the first heat-insulating film has a heat-insulating effect, heat diffusion or heat transfer on the first side of the cell assembly is slower, while heat diffusion or heat transfer on the second side closer to the cell assembly is faster. Thus, when a single cell is heated, the core closer to the second side heats up faster and experiences thermal runaway earlier, while the core closer to the first side heats up slower and experiences thermal runaway later. This allows the thermal runaway times of multiple cores to be staggered, preventing excessively rapid instantaneous gas generation when multiple cores simultaneously short-circuit and experience thermal runaway, which could exceed the instantaneous gas emission rate of the single cell. This better avoids the risk of the single cell casing rupture or even fire and explosion, resulting in a lower instantaneous gas generation rate (i.e., a lower maximum gas generation rate) when a single cell experiences thermal runaway, improving the safety of the single cell. Furthermore, the cell assembly of the single cell in this application includes multiple cores. Compared to a single-core solution, this improves space utilization within limited space constraints, making full use of the space at the corners of the single cell and increasing the capacity and energy density of the single cell. Attached Figure Description

[0035] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of the structure of an energy storage system according to an embodiment of this application.

[0037] Figure 2 This is a schematic diagram of the structure of an energy storage device according to an embodiment of this application.

[0038] Figure 3 This is a schematic diagram of the structure of a single battery cell according to an embodiment of this application.

[0039] Figure 4 This application describes a single-cell battery according to an embodiment of the present application. Figure 3 A schematic diagram of the cross-sectional structure of AA.

[0040] Figure 5 This is another embodiment of the single-cell battery of this application. Figure 3 A schematic diagram of the cross-sectional structure of AA.

[0041] Figure 6 This is a schematic diagram of the structure of a core according to an embodiment of this application.

[0042] Figure 7 This is another embodiment of the single-cell battery of this application. Figure 3 A schematic diagram of the cross-sectional structure of AA.

[0043] Figure 8 This is another embodiment of the single-cell battery of this application. Figure 3 A schematic diagram of the cross-sectional structure of AA.

[0044] Figure 9 This is another embodiment of the single-cell battery of this application. Figure 3 A schematic diagram of the cross-sectional structure of AA.

[0045] Figure 10 This is another embodiment of the single-cell battery of this application. Figure 3 A schematic diagram of the cross-sectional structure of AA.

[0046] Figure 11 This is another embodiment of the single-cell battery of this application. Figure 3 A schematic diagram of the cross-sectional structure of AA.

[0047] Figure 12 This is another embodiment of the single-cell battery of this application. Figure 3 A schematic diagram of the cross-sectional structure of AA.

[0048] Explanation of reference numerals in the attached figures:

[0049] 100 - Energy storage system; 110 - High-voltage cable; 120 - First energy conversion device; 130 - Second energy conversion device; 200 - Energy storage device; 300 - Single cell; 310 - Cell assembly; 311 - Core; 3111 - Positive electrode; 3112 - Separator; 3113 - Negative electrode; 3114 - Side; 312 - First side; 313 - Second side; 320 - First heat insulation film; 330 - Insulating film; 340 - Housing; 341 - Reception cavity; 350 - Second heat insulation film; 360 - End cap assembly; 361 - Positive terminal; 362 - Negative terminal. Detailed Implementation

[0050] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0051] The terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0052] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings.

[0053] It should be noted that, for ease of explanation, the same reference numerals denote the same components in the embodiments of this application, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments.

[0054] Because the energy we need is highly time- and space-dependent, in order to utilize energy rationally and improve energy efficiency, it is necessary to store one form of energy in the same way or by converting it into another, and then release it in a specific energy form based on future application needs. Currently, the main way to generate green electricity is to develop green energy sources such as photovoltaics and wind power to replace fossil fuels.

[0055] Currently, the generation of green electricity generally relies on solar, wind, and hydropower. However, wind and solar power are generally characterized by strong intermittency and large fluctuations, which can cause grid instability, insufficient power during peak demand periods, and excessive power during off-peak periods. Unstable voltage can also damage the power grid. Therefore, insufficient electricity demand or insufficient grid capacity may lead to the problem of "wind and solar curtailment." Solving these problems requires energy storage. This involves converting electrical energy into other forms of energy through physical or chemical means and storing it. When needed, this energy can be converted back into electrical energy and released. Simply put, energy storage is like a large "power bank," storing electrical energy when solar and wind power are abundant and releasing the stored electricity when needed.

[0056] Taking electrochemical energy storage as an example, this solution provides an energy storage device for use in energy storage systems. The energy storage device is equipped with a set of chemical batteries, which mainly use the chemical elements in the batteries as energy storage media. The charging and discharging process is accompanied by the chemical reaction or change of the energy storage media. Simply put, the electrical energy generated by wind and solar energy is stored in the chemical batteries. When the use of external electrical energy reaches its peak, the stored electricity is released for use, or transferred to places with a shortage of electricity for use.

[0057] Current energy storage applications are quite widespread, including generation-side energy storage, grid-side energy storage, and consumption-side energy storage. The corresponding types of energy storage devices include:

[0058] (1) Large-scale energy storage power stations (including multiple prefabricated energy storage modules) applied to wind power and photovoltaic power stations can help renewable energy power generation meet grid connection requirements and improve the utilization rate of renewable energy. As a high-quality active / reactive power regulation power source on the power supply side, energy storage power stations can achieve load matching of power in time and space, enhance the absorption capacity of renewable energy, reduce instantaneous power changes, reduce the impact on the power grid, improve the absorption of new energy power generation, and are of great significance in power grid system backup, alleviating peak load power supply pressure and peak regulation and frequency regulation.

[0059] (2) The energy storage prefabricated cabin applied on the grid side mainly functions as peak regulation, frequency regulation and grid congestion relief. In terms of peak regulation, it can realize peak shaving and valley filling of electricity load, that is, charging the energy storage battery when the electricity load is low and releasing the stored electricity during the peak electricity load period, thereby achieving a balance between power production and consumption.

[0060] (3) Small energy storage cabinets applied to the electricity consumption side mainly function as self-consumption of electricity, peak-valley price arbitrage, capacity cost management, and improvement of power supply reliability. Depending on the application scenario, electricity consumption side energy storage can be divided into industrial and commercial energy storage cabinets, household energy storage devices, energy storage charging piles, etc., which are generally used in conjunction with distributed photovoltaics. Industrial and commercial users can use energy storage for peak-valley price arbitrage and capacity cost management. In the electricity market implementing peak-valley pricing, by charging the energy storage system when the electricity price is low and discharging the energy storage system when the electricity price is high, peak-valley price arbitrage can be achieved, reducing electricity costs. In addition, industrial enterprises subject to two-part tariffs can use energy storage systems to store energy during off-peak hours and discharge during peak loads, thereby reducing peak power and the maximum demand declared, achieving the goal of reducing capacity charges. Household photovoltaics with energy storage can improve the level of self-consumption of electricity. Due to high electricity prices and poor power supply stability, the demand for household photovoltaic installations is driven. Given that photovoltaic power generation occurs during the day, while user load is generally higher at night, configuring energy storage can better utilize photovoltaic power, improve self-consumption levels, and reduce electricity costs. Furthermore, energy storage is needed in areas such as communication base stations and data centers for backup power.

[0061] In some embodiments, see Figure 1 , Figure 1 This is a schematic diagram of the structure of an energy storage system 100 according to an embodiment of this application, and this application Figure 1 The embodiments are illustrated using a shared energy storage scenario on the power generation / distribution side as an example. The energy storage device 200 in this application is not limited to a prefabricated energy storage module in a power generation / distribution energy storage scenario.

[0062] This application provides an energy storage system 100, which includes: a high-voltage cable 110, a first power conversion device 120, a second power conversion device 130, and an energy storage device 200 provided in this application. In some embodiments of the power generation scenario, the second power conversion device 130 can be a wind power conversion device. Since the electricity generated by wind power conversion is volatile, random, and intermittent, the unstable electricity output by the wind power conversion device can be stored in the energy storage device 200 through grid connection. The energy storage device 200 is connected to the high-voltage cable 110 and outputs smooth electricity to the power consumption side of the distribution network, realizing peak shaving and frequency regulation, and stable grid operation; or, wind power conversion... The power conversion device is always connected to the high-voltage cable 110. Under normal power generation conditions, the power output of the wind power conversion device is supplied to the power consumption side of the distribution network through the high-voltage cable 110. When the current power load is low and the wind power conversion device generates excess power, the excess power is first stored in the energy storage device 200 to reduce wind and solar curtailment rates and improve the problem of new energy power generation consumption. When the power load is high, the power grid issues an instruction to transmit the power stored in the energy storage device 200 together with the high-voltage cable 110 in grid-connected mode to supply power to the power consumption side. This provides the power grid with various services such as peak shaving, frequency regulation, and backup, giving full play to the peak shaving role of the power grid, promoting peak shaving and valley filling, and alleviating the power supply pressure of the power grid.

[0063] In some embodiments on the distribution network side, the first power conversion device 120 can be a photovoltaic panel, and the energy storage device 200 is connected to the high-voltage cable 110 and installed downstream of the high-voltage cable 110 between the user load and the photovoltaic power conversion device. The electrical energy output by the photovoltaic power conversion device is stored in the energy storage device 200, which can respond in a timely manner to act as a backup power source when the power grid / distribution network fails; or, it can provide power supply support to alleviate line congestion when the high-voltage cable 110 transmission line is blocked, and to delay the economic pressure caused by the expansion of the power grid / distribution capacity when the power grid is planned to be expanded.

[0064] Optionally, the first power conversion device 120 may include, but is not limited to, a photovoltaic panel, and the second power conversion device 130 may include, but is not limited to, a wind power conversion device. The first power conversion device 120 and the second power conversion device 130 can convert at least one of solar energy, light energy, wind energy, thermal energy, tidal energy, biomass energy, and mechanical energy into electrical energy.

[0065] Optionally, the energy storage device 200 may include, but is not limited to, energy storage applications such as energy storage power stations, hydropower / thermal / wind power generation systems, solar power generation systems, mobile power systems, smart home systems, or temporary power supply systems, and may also be applied in multiple fields such as data centers, military equipment, aerospace, charging piles, and electric vehicles.

[0066] Understandably, in some embodiments, the energy storage system 100 includes: a high-voltage cable 110, a first power conversion device 120, a second power conversion device 130, and an energy storage device 200; the high-voltage cable 110 is electrically connected to the energy storage device 200, the first power conversion device 120, and the second power conversion device 130 respectively, the first power conversion device 120 and the second power conversion device 130 are both used to generate electrical energy, and the energy storage device 200 is used to store the electrical energy.

[0067] Please see Figure 2 , Figure 2 This is a schematic diagram of the structure of an energy storage device 200 according to an embodiment of this application.

[0068] Optionally, the energy storage device 200 may include, but is not limited to, one or more individual battery cells 300.

[0069] The term "multiple" refers to two or more, such as, but not limited to, 2, 5, 10, 30, 50, 100, 200, 300, 400, 800, 1000, etc. The number of individual battery cells 300 included in the energy storage device 200 can be determined based on the rated capacity of the individual battery cells 300 and the rated capacity to be achieved by the energy storage device 200.

[0070] It should be noted that when the energy storage device 200 includes a single battery cell 300, the energy storage device 200 can exist in the form of a single battery cell 300. When the energy storage device 200 includes multiple single batteries 300, the multiple single batteries 300 can be stacked, arranged, assembled, and other processes to form battery integrated systems such as battery modules, battery packs, battery clusters, power banks, energy storage cabinets / prefabricated energy storage compartments. In other words, the energy storage device 200 can exist in the form of, but is not limited to, battery integrated systems such as battery modules, battery packs, battery clusters, power banks, energy storage cabinets / prefabricated energy storage compartments. The actual application form of the energy storage device 200 provided in this application embodiment can be, but is not limited to, the listed products, and can also be other application forms. This application embodiment does not strictly limit the application form of the energy storage device 200.

[0071] Optionally, the single cell 300 can be, but is not limited to, at least one of cylindrical, square, prismatic, or other shaped cells.

[0072] Optionally, the single cell 300 can be a rechargeable battery, which refers to a single cell 300 that can be recharged after discharge to activate the active materials and continue to be used. The single cell 300 can be a lithium-ion battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, nickel-metal hydride battery, nickel-cadmium battery, lead-acid battery, etc., and this application does not specifically limit it.

[0073] In related technologies, when a single battery cell in an energy storage device experiences thermal runaway, it is prone to excessive instantaneous gas production rate and low instantaneous gas exhaust rate. This causes the casing of the single battery cell to deform due to pressure difference, leading to casing breakage and failure, or even fire and ignition failure, thus reducing the safety of the single battery cell in use.

[0074] To achieve greater capacity and energy density and fully utilize the internal space of individual battery cells, for prismatic hard-shell cells (such as lithium-ion cells), two or more cores are typically connected in parallel under limited space constraints. Multiple cores can better utilize the limited space and make fuller use of the corner space, thus increasing capacity and energy density. However, in the event of thermal runaway, multiple cores in a multi-core cell are prone to simultaneously triggering short circuits and violent gas venting. This causes the instantaneous gas generation rate within the cell to exceed the effective instantaneous gas venting rate, easily leading to deformation of the cell casing due to pressure differences, resulting in cell failure due to casing rupture or even fire.

[0075] Figure 3 This is a schematic diagram of the structure of a single cell battery 300 according to an embodiment of this application. Figure 4 This application describes a single-cell battery 300 along one embodiment. Figure 3 A schematic diagram of the cross-sectional structure of AA. Figure 5 This application also describes another embodiment of the single-cell battery 300. Figure 3 A schematic diagram of the cross-sectional structure of AA.

[0076] Please see Figures 3 to 5 This application provides a single-cell battery 300, which includes a cell assembly 310 and a first heat-insulating film 320. The cell assembly 310 includes a plurality of wound cores 311 arranged in sequence, the plurality of wound cores 311 being connected in parallel, and along the arrangement direction of the plurality of wound cores 311, the cell assembly 310 has a first surface 312 and a second surface 313 disposed opposite to each other; the first heat-insulating film 320 is disposed on the side of the first surface 312 opposite to the second surface 313.

[0077] It should be noted that the phrase "deposited on one side of a component" in this application can mean that it is disposed on the surface of the component; or it can mean that it is disposed at a distance from the component, with other components disposed between it and the component. For example, the first heat insulation film 320 can be disposed on the surface of the first surface 312; the first heat insulation film 320 can also be disposed on the side of the first surface 312, but at a distance from the first surface 312, with other film layers or components disposed between the first heat insulation film 320 and the first surface 312.

[0078] Understandably, multiple cores 311 are arranged sequentially along the arrangement direction of the first surface 312 and the second surface 313.

[0079] Optionally, the first surface 312 and the second surface 313 are the two surfaces with the largest area among all the surfaces of the housing 340.

[0080] Optionally, the core 311 has a flat structure, and the core 311 has a winding direction (e.g., Figure 5 As indicated by arrow M, the core 311 has a cross-section in a direction parallel to the winding direction of the core 311. The cross-section has a long side and a short side, and the long side is parallel to the first surface 312 and / or the second surface 313.

[0081] The term "multiple" refers to two or more.

[0082] Specifically, the number of the winding cores 311 in the battery cell assembly 310 can be, but is not limited to, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16, 18, 20, etc.

[0083] Figure 6 This is a schematic diagram of the structure of the core 311 according to an embodiment of this application.

[0084] Please see Figure 6 Optionally, the core 311 is formed by sequentially stacking a positive electrode 3111, a separator 3112, and a negative electrode 3113, and then winding them together. The separator 3112 is used to separate the positive electrode 3111 from the negative electrode 3113 to prevent a short circuit between them.

[0085] The single-cell battery 300 of this application embodiment includes a cell assembly 310 and a first heat insulation film 320. The cell assembly 310 includes a plurality of wound cores 311 arranged in sequence, the plurality of wound cores 311 being connected in parallel, and along the arrangement direction of the plurality of wound cores 311, the cell assembly 310 has a first surface 312 and a second surface 313 disposed opposite to each other; the first heat insulation film 320 is disposed on the side of the first surface 312 opposite to the second surface 313. Because the first heat insulation film 320 has a heat insulation effect, the heat diffusion or heat transfer on the first side 312 of the cell assembly 310 is slower, while the heat diffusion or heat transfer on the second side 313 near the cell assembly 310 is faster. Thus, when the single cell 300 is heated, the winding core 311 near the second side 313 heats up faster and thermal runaway occurs earlier, while the winding core 311 near the first side 312 heats up slower and thermal runaway occurs later. This allows the thermal runaway times of multiple winding cores 311 to be staggered, avoiding the situation where multiple winding cores 311 simultaneously short-circuit and thermal runaway occur, resulting in an excessively fast instantaneous gas generation rate that exceeds the instantaneous gas discharge rate of the single cell 300. This better avoids the risk of the single cell 300's casing rupture or even fire and explosion, thus ensuring a lower instantaneous gas generation rate (i.e., a lower maximum gas generation rate) when the single cell 300 experiences thermal runaway, improving the safety of the single cell 300 in use. Furthermore, the cell assembly 310 of the single cell 300 of this application includes multiple cores 311. Compared with the single core 311 solution, it can better improve the space utilization under limited space constraints, make fuller use of the space at the side corner of the single cell 300, and improve the capacity and energy density of the single cell 300.

[0086] Furthermore, the cell assembly 310 includes multiple cores 311. Compared to a single-core battery, when a single cell 300 experiences thermal runaway, multiple support points are formed between the sides of the cores 311 and the casing, and multiple venting gaps are also created. Gas generated by the cell assembly 310 can be evenly discharged through the gaps between the cell assembly 310 and the casing, thus better preventing concentrated stress on a single core 311, local deformation of the casing, stress overload, or casing failure, further improving the safety of the single cell 300. Moreover, for the same capacity, compared to a single core 311, the gaps between the corners of multiple cores 311 and the casing are smaller, thus accommodating more electrode active materials (such as positive and negative electrode active materials), thereby increasing the volumetric energy density of the single cell 300. When the number of cores 311 exceeds two, when thermal runaway occurs in a single cell 300, heat is transferred from the cores 311 closest to the casing to the cores 311 in the middle, thus forming a multi-stage heat transfer, which can delay the spread of thermal runaway and reduce the impact of instantaneous high voltage on the casing of the single cell 300.

[0087] Thermal diffusivity, also known as thermal conductivity coefficient, represents the ability of an object to maintain a uniform temperature during heating or cooling.

[0088] Figure 7 This application also describes another embodiment of the single-cell battery 300. Figure 3 A schematic diagram of the cross-sectional structure of AA. Figure 8 This application also describes another embodiment of the single-cell battery 300. Figure 3 A schematic diagram of the cross-sectional structure of AA.

[0089] Please see Figure 7 and Figure 8 In some embodiments, the single cell 300 further includes: an insulating film 330 that wraps around the outer periphery of the core 311; a first heat insulation film 320 disposed between the insulating film 330 and the cell assembly 310, or the first heat insulation film 320 disposed on the side of the insulating film 330 away from the cell assembly 310.

[0090] Optionally, the insulating film 330 may be, but is not limited to, a Mylar film.

[0091] It should be noted that when the first heat insulation film 320 is disposed between the insulating film 330 and the cell assembly 310, the first heat insulation film 320 can be attached to the first surface 312 of the cell assembly 310, or it can be attached to the surface of the insulating film 330 facing the first surface 312. When the first heat insulation film 320 is disposed on the side of the insulating film 330 away from the cell assembly 310, the first heat insulation film 320 can be attached to the surface of the insulating film 330 away from the first surface 312; the first heat insulation film 320 can also be disposed separately from the insulating film 330.

[0092] It should be noted that the insulating film 330 covers the first surface 312 and the second surface 313.

[0093] In this embodiment, by setting the first heat insulation film 320 at different positions of the single cell 300, the structure is simple and does not excessively increase the volume and weight of the single cell 300. However, when the single cell 300 is heated, the timing of thermal runaway of multiple cores 311 can be staggered, which can avoid the instantaneous gas generation rate being too fast when multiple cores 311 short-circuit and thermal runaway occur simultaneously, exceeding the instantaneous gas exhaust rate of the single cell 300. This can better avoid the risk of the single cell 300 casing cracking or even causing fire or explosion, thus making the single cell 300 have a lower instantaneous gas generation rate (i.e., a lower maximum gas generation rate) when thermal runaway occurs, improving the safety of the single cell 300. In addition, the cell assembly 310 of the single cell 300 of this application includes multiple cores 311. Compared with the single core 311 solution, it can better improve the space utilization rate under limited space constraints, make full use of the space at the side corners of the single cell 300, and achieve an increase in the capacity and energy density of the single cell 300.

[0094] Figure 9 This application also describes another embodiment of the single-cell battery 300. Figure 3 A schematic diagram of the cross-sectional structure of AA. Figure 10 This application also describes another embodiment of the single-cell battery 300. Figure 3 A schematic diagram of the cross-sectional structure of AA.

[0095] Please see Figure 9 and Figure 10 In other embodiments, the single battery cell 300 further includes: a housing 340 having a receiving cavity 341 with one end open, wherein the cell assembly 310, the first heat insulation film 320, and the insulating film 330 are all received within the receiving cavity 341; when the first heat insulation film 320 is disposed on the side of the insulating film 330 away from the cell assembly 310, the first heat insulation film 320 is disposed on the surface of the insulating film 330 away from the cell assembly 310, or the first heat insulation film 320 is disposed on the surface of the housing 340 facing the cell assembly 310; when the first heat insulation film 320 is disposed between the insulating film 330 and the cell assembly 310, the first heat insulation film 320 is disposed on the surface of the insulating film 330 facing the cell assembly 310, or the first heat insulation film 320 is disposed on the surface of the cell assembly 310.

[0096] Optionally, the housing 340 may be, but is not limited to, an aluminum housing.

[0097] It should be noted that the insulating film 330 can insulate the battery cell assembly 310 from the housing 340, but the insulating film 330 allows electrolyte to pass through. Understandably, the insulating film 330 has ion-conducting properties.

[0098] In this embodiment, compared to the scheme where the first heat insulation film 320 is disposed between the insulating film 330 and the battery cell assembly 310, when the first heat insulation film 320 is disposed between the insulating film 330 and the housing 340, in addition to using insulating heat insulation materials, the first heat insulation film 320 can also use partially conductive heat insulation materials, giving the first heat insulation film 320 a wider range of options.

[0099] In some embodiments, the first heat insulation film 320 includes at least one of a polyimide film, mica paper, and a two-dimensional transition metal carbonitride nanocoating (also known as MXene nanocoating or two-dimensional titanium carbide material). In this embodiment, these first heat insulation films 320 all have low thermal conductivity and low thermal diffusivity. When disposed on the first side 312 of the cell assembly 310, the core 311 on the first side 312 of the single cell 300 heats up more slowly and experiences thermal runaway later when the single cell 300 is heated externally, while the core 311 on the second side 313 heats up more quickly and experiences thermal runaway earlier. The thermal runaway times of the core 311 on the first side 312 and the core 311 on the second side 313 can be staggered, reducing the instantaneous gas generation rate inside the single cell 300 when thermal runaway occurs, better avoiding the risk of explosion and fire of the single cell 300, and improving the safety of the single cell 300 in use.

[0100] It should be noted that when the first heat insulation film 320 includes a two-dimensional transition metal carbonitride nanocoating, since the two-dimensional transition metal carbonitride nanocoating is conductive, the first heat insulation film 320 is disposed between the insulating film 330 and the housing 340.

[0101] Optionally, the thermal conductivity of the first heat insulation film 320 is less than or equal to 0.2 W / m·K. Specifically, the thermal conductivity of the first heat insulation film 320 can be, but is not limited to, 0.005 W / m·K, 0.01 W / m·K, 0.015 W / m·K, 0.02 W / m·K, 0.025 W / m·K, 0.03 W / m·K, 0.04 W / m·K, 0.05 W / m·K, 0.06 W / m·K, 0.07 W / m·K, 0. .08W / m·K, 0.09W / m·K, 0.10W / m·K, 0.11W / m·K, 0.12W / m·K, 0.13W / m·K, 0.14W / m·K, 0.15W / m·K, 0.16W / m·K, 0.17W / m·K, 0.18W / m·K, 0.19W / m·K, 0.2W / m·K, etc. The heat insulation coefficient of the first heat insulation film 320 is too low. When the single cell 300 is heated, the heating rate of the core 311 near the first surface 312 and the core 311 near the second surface 313 of the cell assembly 310 is not much different. The thermal runaway time of the core 311 near the first surface 312 and the core 311 near the second surface 313 of the cell assembly 310 is difficult to stagger. The effect of reducing the maximum gas production rate during thermal runaway of the single cell 300 is not obvious, which is not conducive to improving the safety of the single cell 300.

[0102] Optionally, the first heat insulation film 320 may have, but is not limited to, one or more layers. When the first heat insulation film 320 is multi-layered, the multiple layers of the first heat insulation film 320 are stacked sequentially. In other embodiments, the multiple layers of heat insulation film may also be disposed separately, for example, a portion of the heat insulation film may be disposed between the first surface 312 and the insulating film 330, and the remaining portion of the heat insulation film may be disposed between the insulating film 330 and the housing 340.

[0103] In some embodiments, the polyimide film comprises a polyimide matrix and a thermally insulating filler, wherein the thermally insulating filler is dispersed in the polyimide matrix. The thermally insulating filler includes at least one of silica aerogel, hollow glass microspheres, hollow ceramic microspheres, boron nitride, ceramic fiber felt, glass fiber, and reflective foil. These thermally insulating fillers have good thermal insulation properties and can enhance the thermal insulation effect of the first thermally insulating film 320 by utilizing interface reflection and blocking effects. This better staggers the thermal runaway time of the core 311 near the first surface 312 and the core 311 near the second surface 313 of the cell assembly 310, reduces the maximum gas generation rate during thermal runaway of the single cell 300, and improves the safety of the single cell 300. In addition, nano-thermal insulating fillers can be combined to form complex thermal conduction paths in the matrix, increasing interfacial thermal resistance and reducing the thermal conductivity of the first thermally insulating film 320.

[0104] It should be noted that when the reflective foil used is conductive, the first heat insulation film 320 is disposed between the insulating film 330 and the housing 340.

[0105] It should be noted that in other embodiments, the polyimide film may be only a polyimide matrix.

[0106] Optionally, the mica paper includes at least one of aerogel-mica composite material and fiber composite mica paper. Mica paper has a low thermal conductivity and good heat insulation effect, better staggering the thermal runaway time of the core 311 near the first side 312 and the core 311 near the second side 313 of the cell assembly 310, reducing the maximum gas generation rate during thermal runaway of the individual cell 300, and improving the safety of the individual cell 300 in use.

[0107] Optionally, the fiber-composite mica paper can also suppress at least one of hollow glass microspheres, aluminosilicates, etc. This can better improve the heat insulation effect of the fiber-composite mica paper and reduce the thermal conductivity of the first heat insulation film 320.

[0108] Figure 11 This application also describes another embodiment of the single-cell battery 300. Figure 3 A schematic diagram of the cross-sectional structure of AA. Figure 12 This application also describes another embodiment of the single-cell battery 300. Figure 3 A schematic diagram of the cross-sectional structure of AA.

[0109] Please see Figure 11 and Figure 12 In some embodiments, the single cell 300 further includes a second heat insulation film 350, which is disposed on the side of the second surface 313 opposite to the first surface 312, and the thermal diffusivity of the first heat insulation film 320 is different from that of the second heat insulation film 350.

[0110] Understandably, in this embodiment, the single battery cell 300 includes a first heat-insulating film 320 and a second heat-insulating film 350. The first heat-insulating film 320 and the second heat-insulating film 350 are respectively disposed on opposite sides of the cell assembly 310, that is, the first heat-insulating film 320 is disposed on the first surface 312 side, and the second heat-insulating film 350 is disposed on the second surface 313 side. It should be noted that in other embodiments, the single battery cell 300 may only include the first heat-insulating film 320 and may not include the second heat-insulating film 350.

[0111] Optionally, the thermal diffusivity of the first heat insulation film 320 may be less than that of the second heat insulation film 350, or the thermal diffusivity of the first heat insulation film 320 may be greater than that of the second heat insulation film 350. This application does not make specific limitations in this regard.

[0112] In this embodiment, by providing a first heat-insulating film 320 and a second heat-insulating film 350 on the first surface 312 and the second surface 313 of the cell assembly 310 respectively, and making the heat diffusivity of the first heat-insulating film 320 and the second heat-insulating film 350 different, when there is a heat source or heat outside the single cell 300, the winding core 311 on the side of the cell assembly 310 with a higher heat diffusivity heats up faster and thermal runaway occurs earlier, while the winding core 311 on the side of the cell assembly 310 with a lower heat diffusivity heats up slower and thermal runaway occurs later. This allows the timing of short-circuit thermal runaway of multiple winding cores 311 to be staggered, avoiding the instantaneous gas generation rate being too fast when multiple winding cores 311 short-circuit and thermal runaway occur simultaneously, exceeding the instantaneous exhaust rate of the single cell 300. This better avoids the risk of the casing 340 of the single cell 300 cracking or even causing fire or explosion, improving the safety of the single cell 300. Furthermore, the single cell 300 of this application includes multiple cores 311. Compared with the single core 311 solution, it can better improve the space utilization rate under limited space constraints, make fuller use of the space at the side corners of the single cell 300, and improve the capacity and energy density of the single cell 300.

[0113] In some embodiments, the thickness of the first heat insulation film 320 is different from the thickness of the second heat insulation film 350, so that the thermal diffusivity of the first heat insulation film 320 is different from that of the second heat insulation film 350.

[0114] In this embodiment, by designing a thickness difference between the first heat insulation film 320 and the second heat insulation film 350, the heating rates of the core 311 near the first heat insulation film 320 and the core 311 near the second heat insulation film 350 are different when the single cell 300 is heated. The time of thermal runaway can be staggered, which can better reduce the maximum gas production rate when the single cell 300 experiences thermal runaway and improve the safety of the single cell 300 in use.

[0115] In some embodiments, the thermal conductivity of the first heat insulation film 320 is different from that of the second heat insulation film 350, so that the thermal diffusivity of the first heat insulation film 320 is different from that of the second heat insulation film 350.

[0116] In this embodiment, by designing the difference in thermal conductivity between the first heat insulation film 320 and the second heat insulation film 350, the heating rates of the core 311 near the first heat insulation film 320 and the core 311 near the second heat insulation film 350 are different when the single cell 300 is heated. The time of thermal runaway can be staggered, which can better reduce the maximum gas generation rate when the single cell 300 experiences thermal runaway and improve the safety of the single cell 300 in use.

[0117] In other embodiments, the thermal conductivity of the first heat-insulating film 320 is less than that of the second heat-insulating film, and the thickness of the first heat-insulating film 320 is greater than that of the second heat-insulating film 350; or, the thermal conductivity of the first heat-insulating film 320 is greater than that of the second heat-insulating film, and the thickness of the first heat-insulating film 320 is less than that of the second heat-insulating film 350. This allows for a better differentiation in the thermal diffusivity of the first heat-insulating film 320 and the second heat-insulating film 350, resulting in different heating rates for the core 311 near the first heat-insulating film 320 and the core 311 near the second heat-insulating film 350 when the single cell 300 is heated. This staggers the occurrence of thermal runaway, better reducing the maximum gas generation rate when the single cell 300 experiences thermal runaway, and improving the safety of the single cell 300 in use.

[0118] In some embodiments, the thermal diffusivity of the first heat insulation film 320 is α1 (first thermal diffusivity), and the thermal diffusivity of the second heat insulation film 350 is α2 (second thermal diffusivity). If α1 < α2, then the single cell 300 satisfies the relationship: 100% × |α1 - α2| / α2 ≥ 10%.

[0119] Specifically, 100% × |α1-α2| / α2 can be, but is not limited to, 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 85%, 90%, 92%, 94%, 96%, 97%, 98%, 98.5%, 99%, 99.5%, 99.9%, 99.99%, etc.

[0120] In this embodiment, if 100% × |α1-α2| / α2 is too small (i.e., the difference in thermal diffusivity between the first heat insulation film 320 and the second heat insulation film 350 is too small), then when thermal runaway occurs in the single cell 300, the timing of thermal runaway of the core 311 on the first heat insulation film 320 side and the core 311 on the second heat insulation film 350 side is not significantly staggered, and the effect on reducing the maximum gas generation rate within the single cell 300 is not significant, thus having limited improvement on the safety of the single cell 300. If 100% × |α1-α2| / α2 is too large (i.e., the difference in thermal diffusivity between the first heat insulation film 320 and the second heat insulation film 350 is too large), then the material requirements for the first heat insulation film 320 and the second heat insulation film 350 are higher, increasing the cost of the single cell 300.

[0121] Furthermore, 30% ≤ 100% × |α1 - α2| / α2 ≤ 99%. This effectively reduces the time for thermal runaway between the core 311 on the first heat insulation film 320 side and the core 311 on the second heat insulation film 350 side, decreases the instantaneous gas generation rate during thermal runaway of the single cell 300, improves the safety of the single cell 300 during thermal runaway, and also significantly reduces the cost of the first heat insulation film 320 and the second heat insulation film 350.

[0122] Please see again Figure 11 and Figure 12 In some embodiments, the single cell 300 further includes: an insulating film 330 that wraps around the outer periphery of the core 311; and a second heat insulation film 350 disposed between the insulating film 330 and the cell assembly 310, or the second heat insulation film 350 disposed on the side of the insulating film 330 away from the cell assembly 310.

[0123] Optionally, the insulating film 330 may be, but is not limited to, a Mylar film.

[0124] It should be noted that when the second heat insulation film 350 is disposed between the insulating film 330 and the cell assembly 310, the second heat insulation film 350 can be attached to the second surface 313 of the cell assembly 310, or it can be attached to the surface of the insulating film 330 facing the second surface 313. When the second heat insulation film 350 is disposed on the side of the insulating film 330 away from the cell assembly 310, the second heat insulation film 350 can be attached to the surface of the insulating film 330 away from the second surface 313; the second heat insulation film 350 can also be disposed separately from the insulating film 330.

[0125] It should be noted that the insulating film 330 covers the first surface 312 and the second surface 313.

[0126] It should be noted that when the single cell 300 includes the first heat insulation film 320 and the second heat insulation film 350, the first heat insulation film 320 and the second heat insulation film 350 can both be disposed between the insulating film 330 and the cell assembly 310; the first heat insulation film 320 and the second heat insulation film 350 can also both be disposed on the side of the insulating film 330 away from the cell assembly 310; the first heat insulation film 320 and the second heat insulation film 350 can also have one disposed between the insulating film 330 and the cell assembly 310, and the other disposed on the side of the insulating film 330 away from the cell assembly 310.

[0127] In this embodiment, by setting the second heat insulation film 350 at different positions of the single cell 300, the structure is simple and does not excessively increase the volume and weight of the single cell 300. However, when the single cell 300 is heated, the timing of thermal runaway of multiple cores 311 can be staggered, which can avoid the instantaneous gas generation rate being too fast when multiple cores 311 short-circuit and thermal runaway occur simultaneously, exceeding the instantaneous gas exhaust rate of the single cell 300. This can better avoid the risk of the casing 340 of the single cell 300 cracking or even causing fire or explosion, thus making the instantaneous gas generation rate (i.e., the lower maximum gas generation rate) of the single cell 300 when thermal runaway occurs, improving the safety of the single cell 300. In addition, the cell assembly 310 of the single cell 300 of this application includes multiple cores 311. Compared with the single core 311 solution, it can better improve the space utilization rate under limited space constraints, make full use of the space at the side corners of the single cell 300, and improve the capacity and energy density of the single cell 300.

[0128] Please see again Figure 11 and Figure 12 In other embodiments, the single battery cell 300 further includes: a housing 340 having a receiving cavity 341 with one end open, wherein the cell assembly 310, the first heat insulation film 320, the second heat insulation film 350, and the insulating film 330 are all received within the receiving cavity 341; when the second heat insulation film 350 is disposed on the side of the insulating film 330 away from the cell assembly 310, the second heat insulation film 350 is disposed on the surface of the insulating film 330 away from the cell assembly 310, or the second heat insulation film 350 is disposed on the surface of the housing 340 facing the cell assembly 310; when the second heat insulation film 350 is disposed between the insulating film 330 and the cell assembly 310, the second heat insulation film 350 is disposed on the surface of the insulating film 330 facing the cell assembly 310, or the second heat insulation film 350 is disposed on the surface of the cell assembly 310.

[0129] Optionally, the housing 340 may be, but is not limited to, an aluminum housing.

[0130] It should be noted that the insulating film 330 can insulate the battery cell assembly 310 from the housing 340, but the insulating film 330 allows electrolyte to pass through. Understandably, the insulating film 330 has ion-conducting properties.

[0131] In this embodiment, compared to the scheme where the second heat insulation film 350 is disposed between the insulating film 330 and the battery cell assembly 310, when the second heat insulation film 350 is disposed between the insulating film 330 and the housing 340, in addition to using insulating heat insulation materials, the second heat insulation film 350 can also use partially conductive heat insulation materials, giving the second heat insulation film 350 a wider range of options.

[0132] In some embodiments, the second heat insulation film 350 includes at least one of a polyimide film, mica paper, and a two-dimensional transition metal carbonitride nanocoating (also known as an MXene nanocoating). In this embodiment, these materials, as the second heat insulation film 350, can better regulate the thermal diffusivity of the first heat insulation film 320 and the second heat insulation film 350, so that when the single cell 300 experiences thermal runaway, the thermal runaway times of the core 311 on the first side 312 and the core 311 on the second side 313 can be staggered, reducing the instantaneous gas generation rate inside the single cell 300 when thermal runaway occurs, better avoiding the risk of explosion and fire of the single cell 300, and improving the safety of the single cell 300 in use.

[0133] It should be noted that when the second heat insulation film 350 includes a two-dimensional transition metal carbonitride nanocoating, since the two-dimensional transition metal carbonitride nanocoating is conductive, the second heat insulation film 350 is disposed between the insulating film 330 and the housing 340.

[0134] Optionally, the second heat insulation film 350 may have, but is not limited to, one or more layers. When the second heat insulation film 350 is multi-layered, the multiple layers of the second heat insulation film 350 are stacked sequentially. In other embodiments, the multiple layers of heat insulation film may also be disposed separately, for example, a portion of the heat insulation film may be disposed between the second surface 313 and the insulating film 330, and the remaining portion of the heat insulation film may be disposed between the insulating film 330 and the housing 340.

[0135] In some embodiments, the polyimide film includes a polyimide matrix and a thermal insulation filler, wherein the thermal insulation filler is dispersed in the polyimide matrix, and the thermal insulation filler includes at least one of silica aerogel, hollow glass microspheres, hollow ceramic microspheres, boron nitride, ceramic fiber felt, glass fiber, and reflective foil. This allows for better adjustment of the thermal diffusivity of the first thermal insulation film 320 and the second thermal insulation film 350, so that when the single cell 300 experiences thermal runaway, the thermal runaway times of the core 311 on the first side 312 and the core 311 on the second side 313 can be staggered, reducing the instantaneous gas generation rate inside the single cell 300 during thermal runaway, better avoiding the risk of explosion and fire of the single cell 300, and improving the safety of the single cell 300 in use.

[0136] It should be noted that when the reflective foil used is conductive, the second heat insulation film 350 is disposed between the insulating film 330 and the housing 340.

[0137] Optionally, the mica paper includes at least one of aerogel-mica composite material and fiber composite mica paper. The mica paper can be adjusted to better regulate the thermal diffusivity of the first heat insulation film 320 and the second heat insulation film 350, better stagger the thermal runaway time of the core 311 near the first surface 312 and the core 311 near the second surface 313 of the cell assembly 310, reduce the maximum gas production rate during thermal runaway of the single cell 300, and improve the safety of the single cell 300 in use.

[0138] Optionally, the fiber-composite mica paper can also suppress at least one of hollow glass microspheres, aluminosilicates, etc. This can better improve the heat insulation effect of the fiber-composite mica paper and reduce the thermal conductivity of the second heat insulation film 350.

[0139] Please see again Figure 9 and Figure 10 In some embodiments, the battery cell assembly 310 includes at least four cores 311, each core 311 having a side 3114 which is arc-shaped, and the maximum distance between the side 3114 and the housing 340 is d, where 1mm≤d≤6mm.

[0140] Understandably, the side surface 3114 of the core 311 is arc-shaped, thereby forming a gap between the side surfaces 3114 of adjacent cores 311, that is, a gap is formed between the cell assembly 310 and the housing 340. The maximum value of the gap between the cell assembly 310 and the housing 340 is the maximum distance between the side surface 3114 and the housing 340.

[0141] Specifically, the maximum distance between the side surface 3114 and the housing 340 can be, but is not limited to, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, etc. If the maximum distance d between the side surface 3114 and the housing 340 is too small, the cell assembly 310 will be difficult to assemble. In addition, when the single cell 300 experiences thermal runaway, it will be difficult to vent, which may easily lead to excessive local pressure, causing the housing 340 to deform and increasing the risk of explosion or fire when the single cell 300 experiences thermal runaway. If the maximum distance d between the side surface 3114 and the housing 340 is too large, the energy density of the single cell 300 will be reduced.

[0142] In this embodiment, a gap exists between the cell assembly 310 and the housing 340, which provides better expansion space for the cell assembly 310 and facilitates venting in the event of thermal runaway of the individual battery 300. By designing the maximum distance between the side surface 3114 and the housing 340, venting is facilitated when thermal runaway occurs in the individual battery 300, while also ensuring that the individual battery 300 has a high energy density.

[0143] Please see again Figure 9 and Figure 10 In some embodiments, the radius of curvature R of the side surface 3114 is in the range of 5mm≤R≤10mm.

[0144] Understandably, the radius of curvature R of the side surface 3114 can be, but is not limited to, 5mm, 5.5mm, 6mm, 6.5mm, 7mm, 7.5mm, 8mm, 8.5mm, 9mm, 9.5mm, 10mm, etc.

[0145] If the radius of curvature R of the side surface 3114 is too small, the thickness of the large surface of the core 311 will increase, and the expansion of the core 311 during charging, discharging and thermal runaway will increase; if the radius of curvature R of the side surface 3114 is too large, the side surface 3114 of the shell 340 will easily deform during thermal runaway.

[0146] In some embodiments, the area of ​​the first heat insulation film 320 is greater than or equal to the area of ​​the first surface 312 on the extended plane of the first surface 312; and / or, the area of ​​the second heat insulation film 350 is greater than or equal to the area of ​​the second surface 313 on the extended plane of the second surface 313.

[0147] Understandably, the first heat insulation film 320 covers at least the first surface 312, and the second heat insulation film 350 covers at least the second surface 313. In other words, the first surface 312 is completely covered by the first heat insulation film 320, and the second surface 313 is completely covered by the second heat insulation film 350.

[0148] In this embodiment, the area of ​​the first heat insulation film 320 is greater than or equal to the area of ​​the first surface 312 and / or the area of ​​the second heat insulation film 350 is greater than or equal to the area of ​​the second surface 313. This allows for better design of the thermal diffusivity of the first heat insulation film 320 and the second heat insulation film 350, so that the thermal runaway times of the cores on both sides of the cell assembly 310 are staggered as much as possible, thereby improving the safety of the single cell 300.

[0149] Please see again Figure 3The single battery 300 further includes an electrolyte and an end cap assembly 360. The electrolyte is disposed in the receiving cavity 341 for wetting the plurality of winding cores 311. The end cap assembly 360 is connected to the housing 340 for sealing the opening of the receiving cavity 341. The end cap assembly 360 includes an insulated positive terminal 361 and a negative terminal 362. The positive terminal 361 is electrically connected to the positive electrode 3111 of each winding core 311, and the negative terminal 362 is electrically connected to the negative electrode 3113 of each winding core 311.

[0150] The following specific embodiments further describe the single cell 300 of this application.

[0151] Example 1

[0152] The single-cell battery 300 of this embodiment includes a housing 340, a cell assembly 310, an insulating film 330, and a first heat-insulating film 320. The cell assembly 310 includes two wound cores 311 arranged in sequence, the two wound cores 311 being connected in parallel. Along the arrangement direction of the two wound cores 311, the cell assembly 310 has a first surface 312 and a second surface 313 disposed opposite to each other. The insulating film 330 wraps around the outer periphery of the cell assembly 310, and the first heat-insulating film 320 is disposed on the surface of the insulating film 330 opposite to the first surface 312. The first heat-insulating film 320 is a polyimide film, and the thickness of the first heat-insulating film 320 is 50 micrometers.

[0153] Example 2

[0154] The single-cell battery 300 of this embodiment includes a casing 340, a cell assembly 310, an insulating film 330, and a first heat-insulating film 320. The cell assembly 310 includes four wound cores 311 arranged in sequence, the four wound cores 311 being connected in parallel. Along the arrangement direction of the four wound cores 311, the cell assembly 310 has a first surface 312 and a second surface 313 arranged opposite to each other. The insulating film 330 wraps around the outer periphery of the cell assembly 310, and the first heat-insulating film 320 is disposed on the surface of the insulating film 330 opposite to the first surface 312. The first heat-insulating film 320 is a polyimide film, and the thickness of the first heat-insulating film 320 is 100 micrometers.

[0155] Example 3

[0156] The single-cell battery 300 of this embodiment includes a casing 340, a cell assembly 310, an insulating film 330, and a first heat-insulating film 320. The cell assembly 310 includes four coils 311 arranged in sequence, the four coils 311 being connected in parallel. Along the arrangement direction of the four coils 311, the cell assembly 310 has a first surface 312 and a second surface 313 arranged opposite to each other. The insulating film 330 wraps around the outer periphery of the cell assembly 310, and the first heat-insulating film 320 is disposed on the surface of the insulating film 330 opposite to the first surface 312. The first heat-insulating film 320 is mica paper, and the thickness of the mica paper is 50 micrometers.

[0157] Example 4

[0158] The single-cell battery 300 of this embodiment includes a housing 340, a cell assembly 310, an insulating film 330, and a first heat-insulating film 320. The cell assembly 310 includes six coils 311 arranged in sequence, the six coils 311 being connected in parallel. Along the arrangement direction of the six coils 311, the cell assembly 310 has a first surface 312 and a second surface 313 arranged opposite to each other. The insulating film 330 wraps around the outer periphery of the cell assembly 310, and the first heat-insulating film 320 is disposed on the surface of the insulating film 330 opposite to the first surface 312. The first heat-insulating film 320 is mica paper, and the thickness of the mica paper is 100 micrometers.

[0159] Example 5

[0160] The single-cell battery 300 of this embodiment includes a housing 340, a cell assembly 310, an insulating film 330, a first heat-insulating film 320, and a second heat-insulating film 350; the cell assembly 310 includes four wound cores 311 arranged in sequence, the four wound cores 311 are connected in parallel, and along the arrangement direction of the four wound cores 311, the cell assembly 310 has a first surface 312 and a second surface 313 disposed opposite to each other; the insulating film 330 wraps around the outer periphery of the cell assembly 310, and the first heat-insulating film 320 is disposed on the surface of the insulating film 330 opposite to the first surface 312.

[0161] The first heat insulation film 320 is a polyimide film, and the thickness of the first heat insulation film 320 is 100 micrometers;

[0162] The second heat insulation film 350 is mica paper, and the thickness of the second heat insulation film 350 is 20 micrometers.

[0163] Comparative Example 1

[0164] The difference between this comparative example and Example 2 is that this comparative example does not have a first heat insulation film 320.

[0165] Comparative Example 2

[0166] The difference between this comparative example and Example 4 is that the first heat insulation film 320 and the second heat insulation film 350 in this comparative example have the same material and thickness.

[0167] Thermal runaway tests were performed on the single cell 300 of each embodiment and comparative example:

[0168] (1) Thermal runaway tests were conducted according to UL9540A to obtain the gas production rate-time curve. The number of gas production peaks, the time of the peak position, and the gas production rate value during thermal runaway were obtained from the gas production rate-time curve. The thermal runaway data of the single cell 300 of each embodiment and comparative example are shown in Table 1 below.

[0169] Table 1 Performance parameters of the 300 single-cell batteries in each embodiment and comparative example

[0170]

[0171] As can be seen from the test results of Example 2 and Comparative Example 1, neither the first nor the second side of the cell assembly in Comparative Example 1 was provided with a heat insulation film. The thermal diffusivity of the cores on both sides of the cell assembly was the same. Therefore, when the single cell of Comparative Example 1 underwent thermal runaway testing, multiple cores almost simultaneously experienced thermal runaway, with only one gas production peak. The maximum gas production rate of the gas production peak was relatively large, and the single cell failed the thermal runaway test. In Example 1, the cell assembly had a first heat insulation film on its first side. When the single cell of Example 1 underwent thermal runaway testing, it had two gas production peaks, and the maximum gas production rate of both peaks was less than that of the gas production peak in Comparative Example 1. This indicates that some cores in the cell assembly experienced thermal runaway first, and some cores experienced thermal runaway later, thus staggering the thermal runaway times of multiple cores. When a single cell experienced thermal runaway, the maximum gas production rate within the single cell was greatly reduced, and the safety of the single cell was greatly improved.

[0172] As can be seen from the test results of Example 4 and Comparative Example 2, the first side of the cell assembly of Comparative Example 2 is provided with a first heat insulation film and the second side is provided with a second heat insulation film. However, the material and thickness of the first heat insulation film and the second heat insulation film are the same. Therefore, the thermal diffusivity of the cores on both sides of the cell assembly is the same. Therefore, when the single cell of Comparative Example 2 is subjected to thermal runaway test, multiple cores almost simultaneously experience thermal runaway, and there is only one gas production peak. The maximum gas production rate of the gas production peak is relatively large, and the single cell fails the thermal runaway test. In Example 4, a first heat-insulating film is provided on the first side of the cell assembly, and a second heat-insulating film is provided on the second side. The materials and thicknesses of the first and second heat-insulating films are different, resulting in different thermal diffusivity on opposite sides of the cell assembly. When the single cell of Example 4 undergoes thermal runaway testing, it exhibits three gas production peaks, and the maximum gas production rate of all three peaks is less than the maximum gas production rate of the gas production peak in Comparative Example 1. This indicates that some cores in the cell assembly experience thermal runaway first, followed by another part of the cores, and finally the remaining cores. The thermal runaway of multiple cores occurs at three different times. When a single cell experiences thermal runaway, the maximum gas production rate within the single cell is significantly reduced, and the safety of the single cell is greatly improved.

[0173] As can be seen from the test results of Examples 1 to 5, when the single cell of this application is heated, the time when multiple cores in the single cell undergo thermal runaway can be staggered (i.e., the time when multiple cores undergo thermal runaway is different), which can greatly reduce the maximum instantaneous gas production rate when the single cell undergoes thermal runaway, better reduce the risk of single cell explosion and fire, and improve the safety of single cell use.

[0174] In this application, the terms "embodiment" and "implementation" mean that a specific feature, structure, or characteristic described in connection with an embodiment can be included in at least one embodiment of this application. The appearance of these phrases in various locations throughout the specification does not necessarily refer to the same embodiment, nor are they independent or alternative embodiments mutually exclusive with other embodiments. Those skilled in the art will understand, explicitly and implicitly, that the embodiments described in this application can be combined with other embodiments. Furthermore, it should be understood that the features, structures, or characteristics described in the various embodiments of this application can be arbitrarily combined to form yet another embodiment that does not depart from the spirit and scope of the technical solution of this application, provided there is no contradiction between them.

[0175] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit it. Although this application has been described in detail with reference to the above preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of this application should not depart from the spirit and scope of the technical solutions of this application.

Claims

1. A single-cell battery, characterized in that, The single battery cell includes: A battery cell assembly, comprising a plurality of wound cores arranged sequentially and connected in parallel, wherein the battery cell assembly has a first side and a second side disposed opposite to each other along the arrangement direction of the plurality of wound cores; and A first heat insulation film is disposed on the side of the first surface that is opposite to the second surface.

2. The single-cell battery according to claim 1, characterized in that, The single battery cell also includes: An insulating film that wraps around the outer periphery of the winding core; The first heat insulation film is disposed between the insulating film and the battery cell assembly, or the first heat insulation film is disposed on the side of the insulating film away from the battery cell assembly.

3. The single-cell battery according to claim 2, characterized in that, The single battery cell also includes: The housing has a receiving cavity with one end open, and the battery cell assembly, the first heat insulation film and the insulating film are all housed in the receiving cavity; When the first heat insulation film is disposed on the side of the insulating film away from the cell assembly, the first heat insulation film is disposed on the surface of the insulating film away from the cell assembly, or the first heat insulation film is disposed on the surface of the housing facing the cell assembly; When the first heat insulation film is disposed between the insulating film and the battery cell assembly, the first heat insulation film is disposed on the surface of the insulating film facing the battery cell assembly, or the first heat insulation film is disposed on the surface of the battery cell assembly.

4. The single-cell battery according to claim 1, characterized in that, The first heat insulation film includes at least one of polyimide film, mica paper, and two-dimensional transition metal carbonitride nanocoating.

5. The single-cell battery according to claim 4, characterized in that, The polyimide film includes a polyimide matrix and a heat-insulating filler, wherein the heat-insulating filler is dispersed in the polyimide matrix, and the heat-insulating filler includes at least one of silica aerogel, hollow glass microspheres, hollow ceramic microspheres, boron nitride, ceramic fiber felt, glass fiber, and reflective foil; The mica paper includes at least one of aerogel-mica composite material and fiber composite mica paper.

6. The single-cell battery according to any one of claims 1-5, characterized in that, The single cell also includes a second heat insulation film, which is disposed on the side of the second surface away from the first surface. The thermal diffusivity of the first heat insulation film is different from that of the second heat insulation film.

7. The single-cell battery according to claim 6, characterized in that, The thickness of the first heat insulation film is different from the thickness of the second heat insulation film.

8. The single-cell battery according to claim 6, characterized in that, The thermal conductivity of the first heat insulation film is different from that of the second heat insulation film.

9. The single-cell battery according to claim 6, characterized in that, The single battery cell also includes: An insulating film that wraps around the outer periphery of the winding core; The second heat insulation film is disposed between the insulating film and the battery cell assembly, or the second heat insulation film is disposed on the side of the insulating film away from the battery cell assembly.

10. The single-cell battery according to claim 9, characterized in that, The single battery cell also includes: The housing has a receiving cavity with one end open, and the battery cell assembly, the first heat insulation film, the second heat insulation film and the insulating film are all received in the receiving cavity; When the second heat insulation film is disposed on the side of the insulating film away from the cell assembly, the second heat insulation film is disposed on the surface of the insulating film away from the cell assembly, or the second heat insulation film is disposed on the surface of the housing facing the cell assembly; When the second heat insulation film is disposed between the insulating film and the battery cell assembly, the second heat insulation film is disposed on the surface of the insulating film facing the battery cell assembly, or the second heat insulation film is disposed on the surface of the battery cell assembly.

11. The single-cell battery according to claim 3 or 10, characterized in that, The battery cell assembly includes at least four cores, each core having a side surface that is arc-shaped; The maximum distance between the side and the shell is d, then 1mm≤d≤6mm; And / or, The radius of curvature R of the side surface is in the range of 5mm≤R≤10mm.

12. The single-cell battery according to claim 6, characterized in that, Along the extended plane of the first surface, the area of ​​the first heat insulation film is greater than or equal to the area of ​​the first surface; and / or, along the extended plane of the second surface, the area of ​​the second heat insulation film is greater than or equal to the area of ​​the second surface.

13. An energy storage device, characterized in that, include: One or more single-cell batteries according to any one of claims 1-12.

14. An energy storage system, characterized in that, include: High-voltage cable, first power conversion device, second power conversion device and energy storage device as described in claim 13; The high-voltage cable is electrically connected to the energy storage device, the first power conversion device, and the second power conversion device, respectively. The first power conversion device and the second power conversion device are both used to generate electrical energy, and the energy storage device is used to store the electrical energy.

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