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 plurality of roll cores, the roll cores are connected in parallel, each roll core comprises a positive pole piece, a diaphragm and a negative pole piece, and the diaphragm is located between the positive pole piece and the negative pole piece; and the thermal diffusivity of the diaphragms of at least two roll cores in the plurality of roll cores is different.

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] The first aspect of this application provides a single-cell battery, the single-cell battery comprising a plurality of winding cores connected in parallel, each winding core comprising a positive electrode, a separator, and a negative electrode, the separator being located between the positive electrode and the negative electrode; at least two of the winding cores have separators with different thermal diffusivity.

[0005] Furthermore, the single battery cell also includes a housing with a receiving cavity for receiving the plurality of winding cores arranged sequentially; the plurality of winding cores includes a first winding core and a second winding core, wherein the thermal diffusivity of the separator of the first winding core is greater than that of the separator of the second winding core, and along the arrangement direction of the plurality of winding cores, the first winding core is closer to the housing than the second winding core.

[0006] Furthermore, the single cell also includes a housing with a receiving cavity for accommodating the plurality of winding cores arranged sequentially; along the arrangement direction of the plurality of winding cores, and in the direction from the housing to the plurality of winding cores, the thermal diffusivity of the separator of the plurality of winding cores gradually decreases.

[0007] Furthermore, at least two of the winding cores include a first winding core and a second winding core, the thermal diffusivity of the separator of the first winding core is α1, the thermal diffusivity of the separator of the second winding core is α2, and the single cell satisfies the relationship: 100%×(α1-α2) / α2≥5%.

[0008] Furthermore, the separator includes a base film and a coating, the coating being disposed on at least one of two opposing surfaces of the base film; the single cell satisfies at least one of the following conditions:

[0009] The areal density of the diaphragm is different in at least two of the plurality of cores;

[0010] At least two of the plurality of cores have different areal densities of the coating;

[0011] The total thickness of the coating is different for at least two of the plurality of cores; and

[0012] The coating is provided on one surface of the base film of the diaphragm of at least two of the plurality of cores, and the coating is provided on both opposite surfaces of the diaphragm of the other core.

[0013] Furthermore, at least two of the winding cores include a first winding core and a second winding core, wherein the areal density of the diaphragm of the first winding core is m. A1 The areal density of the diaphragm in the second core is m. B1 Then 0.6≤m A1 / m B1 ≤0.9.

[0014] Furthermore, the areal density m of the diaphragm of the first winding core A1 The range is 5g / m 2 ≤m A1 ≤12g / m 2 The areal density m of the diaphragm of the second core B1 The range is 5.5g / m 2 ≤m B1 ≤20g / m 2 .

[0015] Furthermore, at least two of the cores include a first core and a second core, wherein the areal density of the coating on the first core is m. A2 The areal density of the coating of the second core is m. B2 Then 0.5≤m A2 / m B2 ≤0.88.

[0016] Furthermore, the areal density m of the coating of the first core A2 The range is 2g / m 2 ≤m A2 ≤7g / m 2 The areal density m of the coating of the second core B2 The range is 2g / m 2 ≤m B2 ≤14g / m 2 .

[0017] Furthermore, at least two of the cores include a first core and a second core, the total thickness of the coating on the first core is d1, the total thickness of the coating on the second core is d2, and then 0.6≤d1 / d2≤0.9.

[0018] Furthermore, the total thickness d1 of the coating on the first core ranges from 1μm≤d1≤5μm, and the total thickness d2 of the coating on the second core ranges from 1.5μm≤d2≤5.5μm.

[0019] Secondly, embodiments of this application also provide an energy storage device, which includes: one or more single-cell batteries as described in the first aspect of this application.

[0020] 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.

[0021] The single-cell battery of this application embodiment includes multiple cores, and at least two of the cores have different thermal diffusivity of their separators. When the single-cell battery is heated, the core with higher thermal diffusivity heats up faster and short-circuit earlier, while the core with lower thermal diffusivity heats up slower and short-circuit later. This staggers the timing of short-circuit thermal runaway among the multiple cores, preventing excessively rapid instantaneous gas generation exceeding the instantaneous exhaust rate of the single-cell battery when multiple cores short-circuit and experience thermal runaway simultaneously. This better avoids the risk of casing rupture, fire, or explosion, improving the safety of the single-cell battery. Furthermore, the single-cell battery of this application, including multiple cores, improves space utilization within limited space constraints compared to a single-core design, making better use of the corner space on the side of the single-cell battery, thereby increasing the capacity and energy density of the single-cell battery. Attached Figure Description

[0022] 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.

[0023] Figure 1 This is a schematic diagram of the structure of an energy storage system according to an embodiment of this application.

[0024] Figure 2 This is a schematic diagram of the structure of an energy storage device according to an embodiment of this application.

[0025] Figure 3 This is a schematic diagram of the structure of a single battery cell according to an embodiment of this application.

[0026] 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.

[0027] Figure 5 This is a structural schematic diagram of the arrangement of multiple cores according to an embodiment of this application.

[0028] Figure 6 This is a schematic diagram of the structure of a core according to an embodiment of this application.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] Figure 10 This is a cross-sectional view of a diaphragm according to an embodiment of this application.

[0033] Figure 11 This is a cross-sectional view of a diaphragm according to an embodiment of this application.

[0034] Explanation of reference numerals in the attached figures:

[0035] 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 - Core; 310a - First core; 310b - Second core; 310c - Third core; 311 - Positive electrode; 312 - Separator; 3121 - Base film; 3122 - Coating; 313 - Negative electrode; 320 - Housing; 321 - Reception cavity; 322 - First surface; 323 - Second surface; 330 - End cap assembly; 331 - Positive terminal; 332 - Negative terminal. Detailed Implementation

[0036] 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.

[0037] 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.

[0038] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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:

[0044] (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.

[0045] (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.

[0046] (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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] Optionally, the energy storage device 200 may include, but is not limited to, one or more individual battery cells 300.

[0054] 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.

[0055] 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.

[0056] Optionally, the single cell 300 can be, but is not limited to, at least one of cylindrical, square, prismatic, or other shaped cells.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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 is a structural schematic diagram of the arrangement of multiple cores 310 according to an embodiment of this application. Figure 6 This is a schematic diagram of the structure of the core 310 according to an embodiment of this application.

[0061] Please see Figures 3 to 6 This application provides a single-cell battery 300, which includes a plurality of coils 310 connected in parallel. Each coil 310 includes a positive electrode 311, a separator 312, and a negative electrode 313. The separator 312 is located between the positive electrode 311 and the negative electrode 313. At least two of the coils 310 have different thermal diffusivity of their separators 312.

[0062] The term "multiple" refers to two or more.

[0063] Thermal diffusivity, also known as thermal conductivity coefficient, represents the ability of an object to maintain a uniform temperature during heating or cooling.

[0064] Understandably, the core 310 is formed by sequentially stacking a positive electrode 311, a separator 312, and a negative electrode 313, and then winding them together. The separator 312 is used to separate the positive electrode 311 from the negative electrode 313 to prevent a short circuit between them.

[0065] Specifically, the number of winding cores 310 in the single battery cell 300 can be, but is not limited to, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16, 18, 20, etc.

[0066] In one example, the single cell 300 includes two cores 310, the two cores 310 having different thermal diffusivity of the separator 312.

[0067] In yet another example, the single cell 300 includes four cores 310, and the separators 312 of the four cores 310 have two types of thermal diffusivity. For example, the separator 312 of one core 310 has a first thermal diffusivity, and the separators 312 of the other three cores 310 have a second thermal diffusivity, the first thermal diffusivity being different from the second thermal diffusivity; for another example, the separators 312 of two cores 310 have a first thermal diffusivity, and the separators 312 of the other two cores 310 have a second thermal diffusivity, the first thermal diffusivity being different from the second thermal diffusivity; for yet another example, the separators 312 of three cores 310 have a first thermal diffusivity, and the separator 312 of the other core 310 has a second thermal diffusivity, the first thermal diffusivity being different from the second thermal diffusivity.

[0068] In another example, the single cell 300 includes six cores 310, and the separators 312 of the six cores 310 have three thermal diffusivityes. For example, the separators 312 of two cores 310 have a first thermal diffusivity, the separators 312 of two cores 310 have a second thermal diffusivity, and the separators 312 of the remaining two cores 310 have a third thermal diffusivity, wherein the first, second, and third thermal diffusivityes are all different. In other embodiments, the thermal diffusivityes of the separators 312 of the six cores 310 may also all be different.

[0069] The single-cell battery 300 of this application embodiment includes a plurality of winding cores 310. At least two of the winding cores 310 have different thermal diffusivity of the separator 312. Thus, when the single-cell battery 300 is heated, the winding core 310 with higher thermal diffusivity heats up faster and short-circuit earlier, while the winding core 310 with lower thermal diffusivity heats up slower and short-circuit later. This allows the timing of short-circuit thermal runaway of the multiple winding cores 310 to be staggered. This avoids the instantaneous gas generation rate being too fast when multiple winding cores 310 short-circuit and thermal runaway occur simultaneously, exceeding the instantaneous gas exhaust rate of the single-cell battery 300. This better avoids the risk of the single-cell battery 300 casing cracking or even causing fire or explosion, and improves the safety of using the single-cell battery 300. Furthermore, the single cell 300 of this application includes multiple cores 310. Compared with the single core 310 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.

[0070] 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.

[0071] Please see Figure 7 and Figure 8 In some embodiments, the single battery cell 300 further includes a housing 320, the housing 320 having a receiving cavity 321 for receiving the plurality of winding cores 310 arranged sequentially; the plurality of winding cores 310 includes a first winding core 310a and a second winding core 310b, the thermal diffusivity of the separator 312 of the first winding core 310a is greater than the thermal diffusivity of the separator 312 of the second winding core 310b, and along the arrangement direction of the plurality of winding cores 310, the first winding core 310a is closer to the housing 320 than the second winding core 310b.

[0072] Understandably, the first core 310a is closer to the housing 320, and the second core 310b is closer to the middle of the plurality of cores 310.

[0073] Understandably, the receiving cavity 321 is a receiving cavity 321 with one end open.

[0074] like Figure 7 As shown, in one example, at least two of the cores 310 include two first cores 310a and two second cores 310b. The thermal diffusivity of the diaphragm 312 of the first core 310a is greater than that of the diaphragm 312 of the second core 310b. The four cores 310 are arranged in the order of first core 310a, second core 310b, second core 310b, and first core 310a. That is, the two cores 310 with larger diaphragm 312 thermal diffusivity are located on the outer side (closer to the housing 320), and the two cores 310 with smaller diaphragm 312 thermal diffusivity are located in the middle (closer to the inside of the core 310).

[0075] like Figure 8 As shown, in another example, at least two of the cores 310 include two first cores 310a and four second cores 310b. The thermal diffusivity of the diaphragm 312 of the first cores 310a is greater than that of the diaphragm 312 of the second cores 310b. The six cores 310 are arranged in the order of first core 310a, second core 310b, second core 310b, second core 310b, second core 310b, and first core 310a. That is, the two first cores 310a with a larger thermal diffusivity of the diaphragm 312 are located on the outer side (closer to the housing 320), and the four second cores 310b with a smaller thermal diffusivity of the diaphragm 312 are located in the middle (closer to the inside of the cores 310).

[0076] When there is a heat source outside the single cell 300, the first core 310a near the casing 320 is heated first, and then the heat is transferred or conducted to the second core 310b. The separator 312 of the first core 310a near the casing 320 has a higher thermal diffusivity, while the separator 312 of the second core 310b away from the casing 320 has a lower thermal diffusivity. The first core 310a is heated first and has a higher thermal diffusivity, which allows the first core 310a to reach the thermal runaway temperature faster. The second core 310b is heated after being transferred by the first core 310a and has a lower thermal diffusivity, which allows the second core 310b to reach the thermal runaway temperature more slowly. This allows the thermal runaway times of the first core 310a and the second core 310b to be staggered as much as possible, reducing the instantaneous gas generation rate inside the single cell 300 when thermal runaway occurs, better avoiding the danger of fire, explosion and other hazards when the single cell 300 experiences thermal runaway, and improving the safety of the single cell 300 in use.

[0077] Optionally, the housing 320 has a first surface 322 and a second surface 323 arranged opposite to each other, wherein the first surface 322 and the second surface 323 are the two surfaces with the largest area among all the surfaces of the housing 320. The plurality of winding cores 310 are arranged sequentially along the arrangement direction of the first surface 322 and the second surface 323.

[0078] Optionally, the core 310 has a flat structure, and the core 310 has a cross-section parallel to the winding direction of the core 310. The cross-section has a long side and a short side, and the long side is parallel to the first surface 322 or the second surface 323.

[0079] In some embodiments, the single battery cell 300 further includes a housing 320 having a receiving cavity 321 for receiving the plurality of winding cores 310 arranged sequentially; along the arrangement direction of the plurality of winding cores 310, and in the direction from the housing 320 to the plurality of winding cores 310, the thermal diffusivity of the separator 312 of the plurality of winding cores 310 gradually decreases.

[0080] Understandably, along the arrangement direction of the plurality of cores 310, the thermal diffusion of the diaphragm 312 of the plurality of cores 310 first gradually decreases and then gradually increases.

[0081] It is also understandable that the thermal diffusivity of the diaphragm 312 of the core 310 closer to the housing 320 is higher, and the thermal diffusivity of the diaphragm 312 of the core 310 further away from the housing 320 is lower.

[0082] In one example, at least two of the cores 310 include two first cores 310a and two second cores 310b, wherein the thermal diffusivity of the diaphragm 312 of the first core 310a is greater than that of the diaphragm 312 of the second core 310b, and the four cores 310 are arranged in the order of first core 310a, second core 310b, second core 310b, and first core 310a. That is, the two cores 310 with larger diaphragm 312 thermal diffusivity are located on the outer side (closer to the housing 320), and the two cores 310 with smaller diaphragm 312 thermal diffusivity are located in the middle (closer to the inside of the core 310).

[0083] 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.

[0084] Please see Figure 9 In another example, at least two of the cores 310 include two first cores 310a, two second cores 310b, and two third cores 310c. The thermal diffusivity of the diaphragm 312 of the first core 310a is greater than that of the diaphragm 312 of the second core 310b, and the thermal diffusivity of the diaphragm 312 of the second core 310b is greater than that of the diaphragm 312 of the third core 310c. The six cores 310 are arranged in the order of first core 310a, second core 310b, third core 310c, third core 310c, second core 310b, and first core 310a. That is, the first core 310a with the maximum thermal diffusivity of the two diaphragms 312 is located on the outermost side (closer to the housing 320), the second core 310b with the medium thermal diffusivity of the two diaphragms 312 is located on the next outermost side, and the third core 310c with the minimum thermal diffusivity of the two diaphragms 312 is located in the middle.

[0085] In this embodiment, along the arrangement direction of the plurality of winding cores 310, and in the direction from the housing 320 to the plurality of winding cores 310, the thermal diffusivity of the separator 312 of the plurality of winding cores 310 gradually decreases. Thus, when the single cell 300 has a large number of winding cores 310, when the single cell 300 experiences thermal runaway due to an external heat source, the multiple winding cores 310 can gradually undergo thermal runaway, better staggering the thermal runaway time of each winding core 310. This results in more stable gas production during thermal runaway of the single cell 300, better preventing the single cell 300 from exploding or catching fire due to excessively rapid instantaneous gas production.

[0086] In some embodiments, at least two of the winding cores 310 include a first winding core 310a and a second winding core 310b, wherein the thermal diffusivity of the separator 312 of the first winding core 310a is α1 (first thermal diffusivity), and the thermal diffusivity of the separator 312 of the second winding core 310b is α2 (second thermal diffusivity), and the single cell 300 satisfies the relationship: 100% × (α1 - α2) / α2 ≥ 5%.

[0087] Specifically, 100%×(α1-α2) / α2 can be, but is not limited to, 5%, 8%, 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, etc.

[0088] In this embodiment, if 100%×(α1-α2) / α2 is too small (i.e., the difference in thermal diffusivity of the separator 312 between the first core 310a and the second core 310b is too small), then when the single cell 300 experiences thermal runaway, the timing of thermal runaway between the first core 310a and the second core 310b is not significantly staggered, and the effect on reducing the instantaneous gas generation rate within the single cell 300 is not significant, thus limiting the improvement in the safety of the single cell 300. If 100%×(α1-α2) / α2 is too large (i.e., the thermal diffusivity of the separator 312 of the first core 310a and the second core 310b differs too much), the consistency of the multiple cores 310 in the single cell 300 will be poor, the transport path of metal ions (e.g., lithium ions) of the first core 310a and the second core 310b will be too different, the dynamic performance of the core 310 with the excessively long metal ion transport path will be reduced, and the capacity will not be fully utilized. This will not only reduce the capacity of the entire single cell 300, but also reduce the cycle capacity retention rate of the single cell 300.

[0089] Furthermore, 5% ≤ 100% × (α1 - α2) / α2 ≤ 30%. This effectively staggers the thermal runaway times of the first core 310a and the second core 310b, reduces the instantaneous gas generation rate during thermal runaway of the individual cell 300, improves the safety of the individual cell 300 during thermal runaway, and allows the capacity of each core 310 within the individual cell 300 to be fully utilized, resulting in higher capacity and cycle capacity retention.

[0090] In some embodiments, at least two of the winding cores 310 include a first winding core 310a, a second winding core 310b, and a third winding core 310c. The thermal diffusivity of the separator 312 of the first winding core 310a is α1, the thermal diffusivity of the separator 312 of the second winding core 310b is α2, and the thermal diffusivity of the separator 312 of the third winding core 310c is α3 (third thermal diffusivity). The single cell 300 satisfies the following relationships: 100% × (α1 - α2) / α2 ≥ 5%; 100% × (α2 - α3) / α3 ≥ 5%.

[0091] Specifically, 100%×(α1-α2) / α2 can be, but is not limited to, 5%, 8%, 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, etc. In this embodiment, if 100%×(α1-α2) / α2 is too small (i.e., the difference in thermal diffusivity of the separator 312 between the first core 310a and the second core 310b is too small), then when the single cell 300 experiences thermal runaway, the time difference between the thermal runaway of the first core 310a and the second core 310b is not significant, the effect on reducing the instantaneous gas generation rate within the single cell 300 is not significant, and the improvement on the safety of the single cell 300 is limited. If 100%×(α1-α2) / α2 is too large (i.e., the thermal diffusivity of the separator 312 of the first core 310a and the second core 310b differs too much), the consistency of the multiple cores 310 in the single cell 300 will be poor, the transport path of metal ions (e.g., lithium ions) of the first core 310a and the second core 310b will be too different, the dynamic performance of the core 310 with the excessively long metal ion transport path will be reduced, and the capacity will not be fully utilized. This will not only reduce the capacity of the entire single cell 300, but also reduce the cycle capacity retention rate of the single cell 300.

[0092] Specifically, 100%×(α2-α3) / α3 can be, but is not limited to, 5%, 8%, 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, etc. In this embodiment, if 100%×(α2-α3) / α3 is too small (i.e., the difference in thermal diffusivity between the separator 312 of the second core 310b and the third core 310c is too small), then when the single cell 300 experiences thermal runaway, the time difference between the thermal runaway of the second core 310b and the third core 310c is not significant, the effect on reducing the instantaneous gas generation rate within the single cell 300 is not significant, and the improvement on the safety of the single cell 300 is limited. If 100%×(α2-α3) / α3 is too large (i.e., the thermal diffusivity of the separator 312 of the second core 310b and the third core 310c differs too much), the consistency of the multiple cores 310 in the single cell 300 will be poor, the transport path of metal ions (e.g., lithium ions) of the second core 310b and the third core 310c will be too different, the dynamic performance of the core 310 with the excessively long metal ion transport path will be reduced, and the capacity will not be fully utilized. This will not only reduce the capacity of the entire single cell 300, but also reduce the cycle capacity retention rate of the single cell 300.

[0093] Furthermore, 5% ≤ 100% × (α1 - α2) / α2 ≤ 20% and 5% ≤ 100% × (α2 - α3) / α3 ≤ 20%. This effectively staggers the thermal runaway times of the first core 310a, the second core 310b, and the third core 310c, reducing the instantaneous gas generation rate during thermal runaway of the individual cell 300, improving the safety of the individual cell 300 during thermal runaway, and allowing the capacity of each core 310 within the individual cell 300 to be fully utilized, resulting in higher capacity and cycle capacity retention.

[0094] Figure 10 This is a cross-sectional view of a diaphragm 312 according to an embodiment of this application. Figure 11 This is a cross-sectional view of a diaphragm 312 according to an embodiment of this application.

[0095] Please see Figure 10 and Figure 11 In some embodiments, the separator 312 includes a base film 3121 and a coating 3122, the coating 3122 being disposed on at least one of two opposite surfaces of the base film 3121; the single cell 300 satisfies at least one of the following conditions:

[0096] At least two of the plurality of cores 310 have different areal densities of the diaphragm 312;

[0097] At least two of the plurality of cores 310 have different areal densities of the coating 3122;

[0098] At least two of the plurality of cores 310 have different total thicknesses of the coating 3122; and

[0099] At least two of the plurality of cores 310 have the coating 3122 on one surface of the base film 3121 of the diaphragm 312 of one of them, and the coating 3122 is provided on both opposite surfaces of the diaphragm 312 of the other.

[0100] It should be noted that the areal density of the diaphragm 312 of a certain core 310 is equal to the areal density of the coating 3122 of the core 310 plus the areal density of the base film 3121 of the core 310.

[0101] The term "area density" refers to the weight per unit area.

[0102] It should be noted that when the diaphragm 312 includes a single coating 3122 (i.e., a single-sided coating 3122), the areal density of the coating 3122 is the areal density of that single-sided coating 3122. When the diaphragm 312 includes two coatings 3122 (i.e., a double-sided coating 3122, with the base membrane 3121 having coatings 3122 on both sides), the areal density of the coatings 3122 is the total areal density of the double-sided coatings 3122. For example, if one of the two coatings 3122 has an areal density of 2 g / m³, then... 2 The areal density of the other layer is 1.5 g / m³. 2 Therefore, the areal density of the coating 3122 of the diaphragm 312 is 3.5 g / m³. 2 .

[0103] Optionally, coating 3122 includes an adhesive and insulating particles. The insulating particles are dispersed in the adhesive.

[0104] Optionally, the heat-insulating particles may be, but are not limited to, ceramic particles.

[0105] It should be noted that the coating 3122 of the single cell 300 has heat insulation properties. Therefore, differences in the areal density of the separator 312, the areal density of the coating 3122, the total thickness of the coating 3122, or the difference between single-sided and double-sided coatings 3122 will all affect the heat insulation properties of the separator 312 and its thermal diffusivity. The higher the areal density and the thicker the coating 3122, the lower the thermal diffusivity of the separator 312.

[0106] It should be noted that when the diaphragm 312 includes a single coating 3122 (i.e., a single-sided coating 3122), the total thickness of the coating 3122 is the thickness of the single-sided coating 3122. When the diaphragm 312 includes two coatings 3122 (i.e., a double-sided coating 3122, where the base membrane 3121 has coatings 3122 on both sides), the total thickness of the coating 3122 is the sum of the thicknesses of the double-sided coatings 3122.

[0107] In one example, the diaphragms 312 of a plurality of cores 310 all have a single-sided coating 3122 or all have a double-sided coating 3122, the areal density of the coatings 3122 of the plurality of cores 310 is the same; the total thickness of the coatings 3122 of the plurality of cores 310 is the same; and the areal density of the diaphragms 312 of at least two of the plurality of cores 310 is different.

[0108] In another example, the diaphragms 312 of a plurality of cores 310 all have a single-sided coating 3122 or all have a double-sided coating 3122, the areal density of the coatings 3122 of the plurality of cores 310 is the same; the total thickness of the coatings 3122 of at least two of the plurality of cores 310 is different; and the areal density of the diaphragms 312 of the plurality of cores 310 is the same.

[0109] In yet another example, the diaphragms 312 of the plurality of cores 310 all have a single-sided coating 3122 or all have a double-sided coating 3122, and the areal density of the coating 3122 of at least two of the plurality of cores 310 is different; the total thickness of the coating 3122 of the plurality of cores 310 is the same; and the areal density of the diaphragms 312 of the plurality of cores 310 is the same.

[0110] In yet another example, the diaphragms 312 of the plurality of cores 310 all have a single-sided coating 3122 or all have a double-sided coating 3122, the areal density of the coating 3122 of at least two of the plurality of cores 310 is different; the total thickness of the coating 3122 of at least two of the plurality of cores 310 is different; and the areal density of the diaphragms 312 of the plurality of cores 310 is the same.

[0111] In another example, the diaphragms 312 of the plurality of cores 310 all have a single-sided coating 3122 or all have a double-sided coating 3122, and the areal density of the coating 3122 of at least two of the plurality of cores 310 is different; the total thickness of the coating 3122 of the plurality of cores 310 is the same; and the areal density of the diaphragm 312 of at least two of the plurality of cores 310 is different.

[0112] In another example, the diaphragms 312 of the plurality of cores 310 all have a single-sided coating 3122 or all have a double-sided coating 3122, the areal density of the coatings 3122 of the plurality of cores 310 is the same; the total thickness of the coatings 3122 of at least two of the plurality of cores 310 is different; the areal density of the diaphragms 312 of at least two of the plurality of cores 310 is different; that is, the volume density of the coatings 3122 of the plurality of cores 310 is different.

[0113] In yet another example, the diaphragms 312 of the plurality of cores 310 all have a single-sided coating 3122 or all have a double-sided coating 3122, and the areal density of the coating 3122 of at least two of the plurality of cores 310 is different; the total thickness of the coating 3122 of at least two of the plurality of cores 310 is different; and the areal density of the diaphragm 312 of at least two of the plurality of cores 310 is different.

[0114] In yet another example, the areal density of the coating 3122 of the plurality of cores 310 is the same; the total thickness of the coating 3122 of the plurality of cores 310 is the same; the areal density of the diaphragm 312 of the plurality of cores 310 is the same; at least some of the cores 310 have a single-sided coating 3122 for their diaphragm 312, and at least some of the cores 310 have a double-sided coating 3122 for their diaphragm 312.

[0115] In this embodiment, by differentiating the parameters such as the areal density of the separator 312, the areal density of the coating 3122, the thickness of the coating 3122, and whether the coating 3122 is single-sided or double-sided, at least two of the multiple winding cores 310 have different thermal diffusivity of the separator 312. Thus, when the single cell 300 is heated, the winding core 310 with higher thermal diffusivity heats up faster and short-circuit earlier, while the winding core 310 with lower thermal diffusivity heats up slower and short-circuit later. This staggers the timing of short-circuit thermal runaway in multiple winding cores 310, preventing the instantaneous gas generation rate from exceeding the instantaneous exhaust rate of the single cell 300 when multiple winding cores 310 short-circuit and thermal runaway simultaneously. This better avoids the risk of the single cell 300's casing 320 rupturing or even causing fire or explosion, improving the safety of the single cell 300.

[0116] Please see again Figure 7 and Figure 8 In some embodiments, at least two of the winding cores 310 include a first winding core 310a and a second winding core 310b, wherein the areal density of the diaphragm 312 of the first winding core 310a is m. A1The areal density of the diaphragm 312 of the second core 310b is m. B1 Then 0.6≤m A1 / m B1 ≤0.9.

[0117] Understandably, the areal density m of the diaphragm 312 of the first core 310a A1 The areal density m of the diaphragm 312 of the second core 310b B1 The ratio k1 (k1 = m) A1 / m B1 The range is 0.6 to 0.9.

[0118] Understandably, in this embodiment, the thermal diffusivity of the diaphragm 312 of the first core 310a is greater than that of the diaphragm 312 of the second core 310b.

[0119] Specifically, m A1 / m B1 It can be, but is not limited to, 0.6, 0.62, 0.64, 0.66, 0.68, 0.7, 0.72, 0.74, 0.76, 0.78, 0.8, 0.82, 0.84, 0.86, 0.88, 0.9, etc.

[0120] In this embodiment, if m A1 / m B1 If the diameter is too small, the thermal diffusivity of the separator 312 between the first core 310a and the second core 310b will differ too much, resulting in poor consistency among the multiple cores 310 within the single cell 300. The transport paths of metal ions (e.g., lithium ions) between the first core 310a and the second core 310b will differ significantly. Cores 310 with excessively long metal ion transport paths will exhibit reduced kinetic performance and incomplete capacity utilization. This will not only reduce the overall capacity of the single cell 300 but also decrease its cycle capacity retention rate. If m A1 / m B1 If the thermal diffusivity is too large, the difference between the thermal diffusivity of the separator 312 of the first core 310a and the second core 310b will be too small. When the single cell 300 experiences thermal runaway, the timing of thermal runaway of the first core 310a and the second core 310b will not be significantly staggered. This will not have a significant effect on reducing the instantaneous gas generation rate within the single cell 300, and will have limited impact on improving the safety of the single cell 300.

[0121] In this embodiment, further, 0.7 ≤ m A1 / m B1≤0.9. This allows for better staggering of the thermal runaway times of the first core 310a and the second core 310b when thermal runaway occurs in the single cell 300, reducing the instantaneous gas generation rate during thermal runaway, improving the safety of the single cell 300 during thermal runaway, and also allowing the capacity of each core 310 (first core 310a and second core 310b) in the single cell 300 to be fully utilized, resulting in higher capacity and cycle capacity retention.

[0122] Please see again Figure 9 In some embodiments, at least two of the cores 310 include a first core 310a, a second core 310b, and a third core 310c, wherein the areal density of the diaphragm 312 of the first core 310a is m. A1 The areal density of the diaphragm 312 of the second core 310b is m. B1 The areal density of the diaphragm 312 of the second core 310b is m. C1 Then 0.6≤m A1 / m B1 ≤0.9 and 0.6≤m B1 / m C1 ≤0.9.

[0123] Understandably, the areal density m of the diaphragm 312 of the first core 310a A1 The areal density m of the diaphragm 312 of the second core 310b B1 The ratio ranges from 0.6 to 0.9. The areal density m of the diaphragm 312 of the second core 310b... B1 The areal density m of the diaphragm 312 of the third core 310c C1 The ratio ranges from 0.6 to 0.9.

[0124] Understandably, in this embodiment, along the arrangement direction of the plurality of cores 310, and in the direction from the housing 320 to the plurality of cores 310, the thermal diffusivity of the diaphragm 312 of the first core 310a, the second core 310b, and the third core 310c gradually decreases. In other words, the thermal diffusivity of the diaphragm 312 of the first core 310a is greater than that of the diaphragm 312 of the second core 310b, and the thermal diffusivity of the diaphragm 312 of the second core 310b is greater than that of the diaphragm 312 of the third core 310c.

[0125] Specifically, m A1 / m B1The denominator can be, but is not limited to, 0.6, 0.62, 0.64, 0.66, 0.68, 0.7, 0.72, 0.74, 0.76, 0.78, 0.8, 0.82, 0.84, 0.86, 0.88, 0.9, etc. In this embodiment, if m... A1 / m B1 If the diameter is too small, the thermal diffusivity of the separator 312 between the first core 310a and the second core 310b will differ too much, resulting in poor consistency among the multiple cores 310 within the single cell 300. The transport paths of metal ions (e.g., lithium ions) between the first core 310a and the second core 310b will differ significantly. Cores 310 with excessively long metal ion transport paths will exhibit reduced kinetic performance and incomplete capacity utilization. This will not only reduce the overall capacity of the single cell 300 but also decrease its cycle capacity retention rate. If m A1 / m B1 If the thermal diffusivity is too large, the difference between the thermal diffusivity of the separator 312 of the first core 310a and the second core 310b will be too small. When the single cell 300 experiences thermal runaway, the timing of thermal runaway of the first core 310a and the second core 310b will not be significantly staggered. This will not have a significant effect on reducing the instantaneous gas generation rate within the single cell 300, and will have limited impact on improving the safety of the single cell 300.

[0126] Specifically, m B1 / m C1 The denominator can be, but is not limited to, 0.6, 0.62, 0.64, 0.66, 0.68, 0.7, 0.72, 0.74, 0.76, 0.78, 0.8, 0.82, 0.84, 0.86, 0.88, 0.9, etc. In this embodiment, if m... B1 / m C1 If the value is too small, the thermal diffusivity of the separator 312 between the second core 310b and the third core 310c will differ too much, resulting in poor consistency among the multiple cores 310 within the single cell 300. The transport paths of metal ions (e.g., lithium ions) between the second core 310b and the third core 310c will also differ significantly. Cores 310 with excessively long metal ion transport paths will exhibit reduced kinetic performance and incomplete capacity utilization, thus reducing not only the overall capacity of the single cell 300 but also its cycle capacity retention rate. If m B1 / m C1 If the thermal diffusivity is too large, the difference between the thermal diffusivity of the separator 312 of the second core 310b and the third core 310c will be too small. When the single cell 300 experiences thermal runaway, the timing of thermal runaway of the second core 310b and the third core 310c will not be significantly staggered. This will not have a significant effect on reducing the instantaneous gas generation rate within the single cell 300, and will have limited impact on improving the safety of the single cell 300.

[0127] In this embodiment, further, 0.7 ≤ mA1 / m B1 ≤0.9 and 0.7≤m B1 / m C1 ≤0.9. This allows for better staggering of the thermal runaway times of the first core 310a, the second core 310b, and the third core 310c when thermal runaway occurs in a single cell 300, reducing the instantaneous gas generation rate during thermal runaway and improving the safety of the single cell 300 during thermal runaway. It also allows the capacity of each core 310 (first core 310a, second core 310b, and third core 310c) within the single cell 300 to be fully utilized, resulting in higher capacity and cycle capacity retention.

[0128] In some embodiments, the areal density m of the diaphragm 312 of the first winding core 310a A1 The range is 5g / m 2 ≤m A1 ≤12g / m 2 .

[0129] Specifically, the areal density m of the diaphragm 312 of the first core 310a A1 It can be, but is not limited to, 5g / m 2 6g / m 2 7g / m 2 8g / m 2 9g / m 2 10g / m 2 11g / m 2 12g / m 2 wait.

[0130] In this embodiment, if the areal density m of the diaphragm 312 of the first core 310a is... A1 If the areal density m of the diaphragm 312 is too small, the diaphragm 312 will easily conduct electrons, making it difficult to insulate the positive electrode 311 and the negative electrode 313 of the first core 310a, thus making it easy for the positive electrode 311 and the negative electrode 313 of the first core 310a to short-circuit; if the areal density m of the diaphragm 312 of the first core 310a is too small, the diaphragm 312 will easily conduct electrons, making it difficult to insulate the positive electrode 311 and the negative electrode 313 of the first core 310a to short-circuit. A1 If the thickness is too large, the separator 312 of the first core 310a will be too thick, reducing the energy density of the single cell 300.

[0131] In some embodiments, the areal density m of the diaphragm 312 of the second core 310b B1 The range is 5.5g / m 2 ≤m B1 ≤20g / m 2 .

[0132] Specifically, the areal density m of the diaphragm 312 of the second core 310bB1 It can be, but is not limited to, 5.5g / m³. 2 6g / m 2 7g / m 2 8g / m 2 9g / m 2 10g / m 2 11g / m 2 12g / m 2 13g / m 2 14g / m 2 15g / m 2 16g / m 2 17g / m 2 18g / m 2 19g / m 2 20g / m 2 wait.

[0133] In this embodiment, if the areal density m of the diaphragm 312 of the second core 310b is... B1 If the areal density m of the diaphragm 312 is too small, the diaphragm 312 will easily conduct electrons, making it difficult to insulate the positive electrode 311 and the negative electrode 313 of the second core 310b, thus making it easy for the positive electrode 311 and the negative electrode 313 of the second core 310b to short-circuit; if the areal density m of the diaphragm 312 of the second core 310b is too small, the diaphragm 312 will easily conduct electrons, making it difficult to insulate the positive electrode 311 and the negative electrode 313 of the second core 310b to short-circuit. B1 If the thickness is too large, the separator 312 of the second core 310b will be too thick, reducing the energy density of the single cell 300.

[0134] In some embodiments, the areal density m of the diaphragm 312 of the third core 310c C1 The range is 5.5g / m 2 ≤m C1 ≤20g / m 2 .

[0135] Specifically, the areal density m of the diaphragm 312 of the third core 310c C1 It can be, but is not limited to, 5.5g / m³. 2 6g / m 2 7g / m 2 8g / m 2 9g / m 2 10g / m 2 11g / m 2 12g / m 2 13g / m 2 14g / m 2 15g / m 2 16g / m 2 17g / m 2 18g / m2 19g / m 2 20g / m 2 wait.

[0136] In this embodiment, if the areal density m of the diaphragm 312 of the third core 310c is... C1 If the areal density m of the diaphragm 312 is too small, the diaphragm 312 will easily conduct electrons, making it difficult to insulate the positive electrode 311 and the negative electrode 313 of the third core 310c, thus making it easy for the positive electrode 311 and the negative electrode 313 of the third core 310c to short-circuit; if the areal density m of the diaphragm 312 of the third core 310c is too small, the diaphragm 312 will easily conduct electrons, making it difficult to insulate the positive electrode 311 and the negative electrode 313 of the third core 310c to short-circuit. C1 If the thickness is too large, the separator 312 of the third core 310c will be too thick, reducing the energy density of the single cell 300.

[0137] In some embodiments, at least two of the cores 310 include a first core 310a and a second core 310b, wherein the areal density of the coating 3122 of the first core 310a is m. A2 The areal density of the coating 3122 of the second core 310b is m. B2 Then 0.5≤m A2 / m B2 ≤0.88.

[0138] Understandably, the areal density m of the coating 3122 of the first core 310a A2 The areal density m of the coating 3122 of the second core 310b B2 The ratio ranges from 0.5 to 0.88.

[0139] Understandably, in this embodiment, the thermal diffusivity of the diaphragm 312 of the first core 310a is greater than that of the diaphragm 312 of the second core 310b.

[0140] Specifically, m A2 / m B2 It can be, but is not limited to, 0.5, 0.52, 0.54, 0.56, 0.58, 0.6, 0.62, 0.64, 0.66, 0.68, 0.7, 0.72, 0.74, 0.76, 0.78, 0.8, 0.82, 0.84, 0.86, 0.88, etc.

[0141] In this embodiment, if m A2 / m B2If the diameter is too small, the thermal diffusivity of the separator 312 between the first core 310a and the second core 310b will differ too much, resulting in poor consistency among the multiple cores 310 within the single cell 300. The transport paths of metal ions (e.g., lithium ions) between the first core 310a and the second core 310b will differ significantly. Cores 310 with excessively long metal ion transport paths will exhibit reduced kinetic performance and incomplete capacity utilization. This will not only reduce the overall capacity of the single cell 300 but also decrease its cycle capacity retention rate. If m A2 / m B2 If the thermal diffusivity is too large, the difference between the thermal diffusivity of the separator 312 of the first core 310a and the second core 310b will be too small. When the single cell 300 experiences thermal runaway, the timing of thermal runaway of the first core 310a and the second core 310b will not be significantly staggered. This will not have a significant effect on reducing the instantaneous gas generation rate within the single cell 300, and will have limited impact on improving the safety of the single cell 300.

[0142] In this embodiment, further, 0.7 ≤ m A2 / m B2 ≤0.88. This allows for better staggering of the thermal runaway times of the first core 310a and the second core 310b when thermal runaway occurs in the single cell 300, reducing the instantaneous gas generation rate during thermal runaway, improving the safety of the single cell 300 during thermal runaway, and also allowing the capacity of each core 310 (first core 310a and second core 310b) within the single cell 300 to be fully utilized, resulting in higher capacity and cycle capacity retention.

[0143] In some embodiments, at least two of the cores 310 include a first core 310a, a second core 310b, and a third core 310c, wherein the areal density of the coating 3122 of the first core 310a is m. A2 The areal density of the coating 3122 of the second core 310b is m. B2 The areal density of the coating 3122 of the third core 310c is m. C2 Then 0.5≤m A2 / m B2 ≤0.88 and 0.5≤m B2 / m C2 ≤0.88.

[0144] Understandably, the areal density m of the coating 3122 of the first core 310a A2 The areal density m of the coating 3122 of the second core 310b B2 The ratio ranges from 0.5 to 0.88. The areal density m of the coating 3122 of the second core 310b is... B2The areal density m of the coating 3122 of the third core 310c C2 The ratio ranges from 0.5 to 0.88.

[0145] Understandably, in this embodiment, along the arrangement direction of the plurality of cores 310, and in the direction from the housing 320 to the plurality of cores 310, the thermal diffusivity of the diaphragm 312 of the first core 310a, the second core 310b, and the third core 310c gradually decreases. In other words, the thermal diffusivity of the diaphragm 312 of the first core 310a is greater than that of the diaphragm 312 of the second core 310b, and the thermal diffusivity of the diaphragm 312 of the second core 310b is greater than that of the diaphragm 312 of the third core 310c.

[0146] Specifically, m A2 / m B2 The denominator can be, but is not limited to, 0.5, 0.52, 0.54, 0.56, 0.58, 0.6, 0.62, 0.64, 0.66, 0.68, 0.7, 0.72, 0.74, 0.76, 0.78, 0.8, 0.82, 0.84, 0.86, 0.88, etc. In this embodiment, if m A2 / m B2 If the diameter is too small, the thermal diffusivity of the separator 312 between the first core 310a and the second core 310b will differ too much, resulting in poor consistency among the multiple cores 310 within the single cell 300. The transport paths of metal ions (e.g., lithium ions) between the first core 310a and the second core 310b will differ significantly. Cores 310 with excessively long metal ion transport paths will exhibit reduced kinetic performance and incomplete capacity utilization. This will not only reduce the overall capacity of the single cell 300 but also decrease its cycle capacity retention rate. If m A2 / m B2 If the thermal diffusivity is too large, the difference between the thermal diffusivity of the separator 312 of the first core 310a and the second core 310b will be too small. When the single cell 300 experiences thermal runaway, the timing of thermal runaway of the first core 310a and the second core 310b will not be significantly staggered. This will not have a significant effect on reducing the instantaneous gas generation rate within the single cell 300, and will have limited impact on improving the safety of the single cell 300.

[0147] Specifically, m B2 / m C2 The denominator can be, but is not limited to, 0.5, 0.52, 0.54, 0.56, 0.58, 0.6, 0.62, 0.64, 0.66, 0.68, 0.7, 0.72, 0.74, 0.76, 0.78, 0.8, 0.82, 0.84, 0.86, 0.88, etc. In this embodiment, if m B2 / m C2If the value is too small, the thermal diffusivity of the separator 312 between the second core 310b and the third core 310c will differ too much, resulting in poor consistency among the multiple cores 310 within the single cell 300. The transport paths of metal ions (e.g., lithium ions) between the second core 310b and the third core 310c will also differ significantly. Cores 310 with excessively long metal ion transport paths will exhibit reduced kinetic performance and incomplete capacity utilization, thus reducing not only the overall capacity of the single cell 300 but also its cycle capacity retention rate. If m B2 / m C2 If the thermal diffusivity is too large, the difference between the thermal diffusivity of the separator 312 of the second core 310b and the third core 310c will be too small. When the single cell 300 experiences thermal runaway, the timing of thermal runaway of the second core 310b and the third core 310c will not be significantly staggered. This will not have a significant effect on reducing the instantaneous gas generation rate within the single cell 300, and will have limited impact on improving the safety of the single cell 300.

[0148] In this embodiment, further, 0.7 ≤ m A2 / m B2 ≤0.88 and 0.7≤m B2 / m C2 ≤0.88. This allows for better staggering of the thermal runaway times of the first core 310a, the second core 310b, and the third core 310c when thermal runaway occurs in a single cell 300, reducing the instantaneous gas generation rate during thermal runaway and improving the safety of the single cell 300 during thermal runaway. It also allows the capacity of each core 310 (first core 310a, second core 310b, and third core 310c) within the single cell 300 to be fully utilized, resulting in higher capacity and cycle capacity retention.

[0149] In some embodiments, the areal density m of the coating 3122 of the first core 310a A2 The range is 2g / m 2 ≤m A2 ≤7g / m 2 .

[0150] Specifically, the areal density m of the coating 3122 of the first core 310a A2 It can be, but is not limited to, 2g / m 2 2.5g / m 2 3g / m 2 3.5g / m 2 4g / m 2 4.5g / m 2 5g / m 2 5.5g / m 2 6g / m 2 5.5g / m 27g / m 2 wait.

[0151] In this embodiment, if the areal density m of the coating 3122 of the first core 310a is... A2 If the surface density m of the coating 3122 is too small, the coating 3122 will not be able to provide adhesion and / or insulation, making it difficult to reduce the thermal shrinkage rate of the diaphragm 312 of the first core 310a; if the surface density m of the coating 3122 of the first core 310a is too small, the coating 3122 will not be able to provide adhesion and / or insulation, making it difficult to reduce the thermal shrinkage rate of the diaph A2 If the membrane is too thick, it will reduce the energy density of the single cell 300, increase the material cost of the single cell 300, and increase the difficulty of manufacturing the separator 312.

[0152] In some embodiments, the areal density m of the coating 3122 of the second core 310b B2 The range is 2g / m 2 ≤m B2 ≤14g / m 2 .

[0153] Specifically, the areal density m of the coating 3122 of the second core 310b B2 It can be, but is not limited to, 2g / m 2 2.5g / m 2 3g / m 2 3.5g / m 2 4g / m 2 4.5g / m 2 5g / m 2 5g / m 2 6g / m 2 7g / m 2 8g / m 2 9g / m 2 10g / m 2 11g / m 2 12g / m 2 13g / m 2 14g / m 2 wait.

[0154] In this embodiment, if the areal density m of the coating 3122 of the second core 310b is... B2 If the surface density m of the coating 3122 is too small, the coating 3122 will not be able to provide adhesion and / or insulation, making it difficult to reduce the thermal shrinkage rate of the diaphragm 312 of the second core 310b; if the surface density m of the coating 3122 of the second core 310b is too small, the coating 3122 will not be able to provide adhesion and / or insulation, making it difficult to reduce the thermal shrinkage rate of the diaph B2 If the membrane is too thick, it will reduce the energy density of the single cell 300, increase the material cost of the single cell 300, and increase the difficulty of manufacturing the separator 312.

[0155] In some embodiments, the areal density m of the coating 3122 of the third core 310c is... C2 The range is 2.5g / m 2 ≤m C2 ≤15g / m 2 .

[0156] Specifically, the areal density m of the coating 3122 of the third core 310c C2 It can be, but is not limited to, 2.5g / m 2 3g / m 2 3.5g / m 2 4g / m 2 4.5g / m 2 5g / m 2 5g / m 2 6g / m 2 7g / m 2 8g / m 2 9g / m 2 10g / m 2 11g / m 2 12g / m 2 13g / m 2 14g / m 2 15g / m 2 wait.

[0157] In this embodiment, if the areal density m of the coating 3122 of the third core 310c is... C2 If the surface density m of the coating 3122 is too small, the coating 3122 will not be able to provide adhesion and / or insulation, making it difficult to reduce the thermal shrinkage rate of the diaphragm 312 of the third core 310c; if the surface density m of the coating 3122 of the third core 310c is too small, the coating 3122 will not be able to provide adhesion and / or insulation, making it difficult to reduce the thermal shrinkage rate of the diaph C2 If the membrane is too thick, it will reduce the energy density of the single cell 300, increase the material cost of the single cell 300, and increase the difficulty of manufacturing the separator 312.

[0158] Please see again Figure 7 and Figure 8 In some embodiments, at least two of the cores 310 include a first core 310a and a second core 310b, the total thickness of the coating 3122 of the first core 310a is d1, the total thickness of the coating 3122 of the second core 310b is d2, and then 0.6≤d1 / d2≤0.9.

[0159] Understandably, the ratio of the total thickness d1 of the coating 3122 of the first core 310a to the total thickness d2 of the coating 3122 of the second core 310b ranges from 0.6 to 0.9.

[0160] Specifically, d1 / d2 can be, but is not limited to, 0.6, 0.62, 0.64, 0.66, 0.68, 0.7, 0.72, 0.74, 0.76, 0.78, 0.8, 0.82, 0.84, 0.86, 0.88, 0.9, etc.

[0161] In this embodiment, if d1 / d2 is too small, the thermal diffusivity of the separator 312 between the first core 310a and the second core 310b will differ too much, resulting in poor consistency among the multiple cores 310 within the single cell 300. The transport paths of metal ions (e.g., lithium ions) between the first core 310a and the second core 310b will differ significantly, leading to reduced kinetic performance and incomplete capacity utilization in the core 310 with excessively long metal ion transport paths. This will not only reduce the overall capacity of the single cell 300 but also decrease its cycle capacity retention rate. Conversely, if d1 / d2 is too large, the thermal diffusivity of the separator 312 between the first core 310a and the second core 310b will be too small. When thermal runaway occurs in the single cell 300, the timing of thermal runaway between the first core 310a and the second core 310b will not be significantly staggered, resulting in minimal reduction of the instantaneous gas generation rate within the single cell 300 and limited improvement in the safety of the single cell 300.

[0162] In this embodiment, further, 0.7 ≤ d1 / d2 ≤ 0.9. This allows for better staggering of the thermal runaway times of the first core 310a and the second core 310b when thermal runaway occurs in the single cell 300, reducing the instantaneous gas generation rate during thermal runaway and improving the safety of the single cell 300 during thermal runaway. It also allows the capacity of each core 310 (first core 310a and second core 310b) within the single cell 300 to be fully utilized, resulting in higher capacity and cycle capacity retention.

[0163] In some embodiments, the total thickness d1 of the coating 3122 of the first core 310a ranges from 1 μm ≤ d1 ≤ 5 μm.

[0164] Specifically, the total thickness d1 of the coating 3122 of the first core 310a can be, but is not limited to, 1μm, 1.5μm, 2μm, 2.5μm, 3μm, 3.5μm, 4μm, 4.5μm, 5μm, etc.

[0165] In this embodiment, if the total thickness d1 of the coating 3122 of the first core 310a is too small, the coating 3122 will not play a role in bonding and / or heat insulation, making it difficult to reduce the thermal shrinkage rate of the separator 312 of the first core 310a; if the total thickness d1 of the coating 3122 of the first core 310a is too thick, the energy density of the single cell 300 will be reduced, the material cost of the single cell 300 will be increased, and the manufacturing difficulty of the separator 312 will be increased.

[0166] In some embodiments, the total thickness d2 of the coating 3122 of the second core 310b ranges from 1.5 μm ≤ d2 ≤ 5.5 μm.

[0167] Specifically, the total thickness d2 of the coating 3122 of the second core 310b can be, but is not limited to, 1.5μm, 2μm, 2.5μm, 3μm, 3.5μm, 4μm, 4.5μm, 5μm, 5.5μm, etc.

[0168] In this embodiment, if the total thickness d2 of the coating 3122 of the second core 310b is too small, the coating 3122 will not play a role in bonding and / or heat insulation, making it difficult to reduce the thermal shrinkage rate of the separator 312 of the second core 310b; if the total thickness d2 of the coating 3122 of the second core 310b is too thick, the energy density of the single cell 300 will be reduced, the material cost of the single cell 300 will be increased, and the manufacturing difficulty of the separator 312 will be increased.

[0169] Please see again Figure 3 The single cell 300 further includes an electrolyte and an end cap assembly 330. The electrolyte is disposed in the receiving cavity 321 for wetting the plurality of winding cores 310. The end cap assembly 330 is connected to the housing 320 for sealing the opening of the receiving cavity 321. The end cap assembly 330 includes an insulated positive terminal 331 and a negative terminal 332. The positive terminal 331 is electrically connected to the positive electrode 311 of each winding core 310, and the negative terminal 332 is electrically connected to the negative electrode 313 of each winding core 310.

[0170] The single cell 300 of this application will be further described below through specific embodiments.

[0171] Example 1

[0172] The single cell 300 of this embodiment includes a first core 310a and a second core 310b. The first core 310a and the second core 310b are connected in parallel. The separator 312 of the first core 310a and the separator 312 of the second core 310b both include a base film 3121 and two coating layers 3122. The two coating layers 3122 are respectively disposed on two opposite surfaces of the base film 3121. The performance parameters of the separators 312 of the first core 310a and the second core 310b are shown in Table 1 below.

[0173] Example 2

[0174] The single-cell battery 300 of this embodiment includes four cores 310 connected in parallel. The four cores 310 include two first cores 310a and two second cores 310b, and are arranged in the order of first core 310a, second core 310b, second core 310b and first core 310a. The separator 312 of the first core 310a and the separator 312 of the second core 310b both include a base film 3121 and two coating layers 3122, which are respectively disposed on two opposite surfaces of the base film 3121. The performance parameters of the separators 312 of the first core 310a and the second core 310b are shown in Table 1 below.

[0175] Example 3

[0176] The single-cell battery 300 of this embodiment includes six cores 310 connected in parallel. Four cores 310 include two first cores 310a and four second cores 310b. The six cores 310 are arranged in the order of first core 310a, second core 310b, second core 310b, second core 310b, second core 310b, and first core 310a. The separator 312 of the first core 310a and the separator 312 of the second core 310b both include a base film 3121 and two coating layers 3122. The two coating layers 3122 are respectively disposed on two opposite surfaces of the base film 3121. The performance parameters of the separators 312 of the first core 310a and the second core 310b are shown in Table 1 below.

[0177] Example 4

[0178] The single-cell battery 300 of this embodiment includes six cores 310 connected in parallel. Four cores 310 include two first cores 310a, two second cores 310b, and two third cores 310c. The six cores 310 are arranged in the order of first core 310a, second core 310b, third core 310c, third core 310c, second core 310b, and first core 310a. The separator 312 of the first core 310a, the separator 312 of the second core 310b, and the separator 312 of the third core 310c all include a base film 3121 and two coating layers 3122. The two coating layers 3122 are respectively disposed on two opposite surfaces of the base film 3121. The performance parameters of the separators 312 of the first core 310a, the second core 310b, and the third core 310c are shown in Table 1 below.

[0179] Comparative Example 1

[0180] The difference between this comparative example and Example 1 is that both cores 310 in this comparative example are first cores 310a.

[0181] Comparative Example 2

[0182] The single cell 300 of this embodiment includes a first core 310a and a second core 310b. The first core 310a and the second core 310b are connected in parallel. The separator 312 of the first core 310a and the separator 312 of the second core 310b both include a base film 3121 and two coating layers 3122. The two coating layers 3122 are respectively disposed on two opposite surfaces of the base film 3121. The performance parameters of the separators 312 of the first core 310a and the second core 310b are shown in Table 1 below.

[0183] Comparative Example 3

[0184] The difference between this comparative example and Example 2 is that all four cores 310 in this comparative example are first cores 310a.

[0185] Thermal runaway tests were conducted on the single-cell batteries 300 of each embodiment and comparative example: thermal runaway tests were performed according to UL9540A, and gas production rate-time curves were obtained. From the gas production rate-time curves, the number of gas production peaks during thermal runaway, the time of the peak position, and the gas production rate value were obtained. The thermal runaway data of the single-cell batteries 300 of each embodiment and comparative example are shown in Table 1 below.

[0186] Table 1 Performance parameters of the 300 single-cell batteries in each embodiment and comparative example

[0187]

[0188]

[0189] As can be seen from the test results of Example 1, Comparative Example 1, and Comparative Example 2, Example 1 only includes two cores 310 (a first core 310a and a second core 310b). During the thermal runaway test according to UL9540A, heat sources were provided on both sides of the first core 310a and the second core 310b. The first core 310a and the second core 310b were heated simultaneously. Therefore, the time interval between the thermal runaway of the first core 310a and the second core 310b was relatively short, and the gas production rate curve during thermal runaway showed a broad peak. In contrast, the areal density of the diaphragm 312, the areal density of the coating 3122, and the areal density of the base film 3121 of the two cores 310 in Comparative Example 1 are all the same. Therefore, during the thermal runaway test, since thermal runaway occurred simultaneously, a sharp slit appeared. Although the areal density of the separator 312 and the areal density of the coating 3122 of the two cores 310 in Comparative Example 2 are different, the difference is very small. Therefore, the time interval for thermal runaway is shorter than that in Example 1, and a sharp slit also appears. In addition, the maximum gas production rate of Comparative Example 1 is v, the maximum gas production rate of Comparative Example 2 is 0.94v, and the maximum gas production rate of Example 1 is 0.73v. Compared with Comparative Example 1 and Comparative Example 2, the maximum gas production rate of Example 1 is significantly reduced, which can better avoid the instantaneous gas production rate being too high when the single cell 300 experiences thermal runaway, avoid the risk of the single cell 300 casing rupture or even fire and explosion, and improve the safety of the single cell 300 in use.

[0190] As shown in the test results of Example 2, the two first cores 310a near the casing 320 of the single cell 300 are heated first and have a higher thermal diffusivity, thus experiencing thermal runaway first. The two second cores 310b near the middle of the single cell 300 transfer heat through the first cores 310a and have a lower thermal diffusivity, thus experiencing thermal runaway later. This staggers the thermal runaway times of the first cores 310a and the second cores 310b, resulting in two slits on the thermal runaway gas generation rate curve. Compared to the case in Comparative Example 3 where the areal density of the separator and the areal density of the coating are the same for all four cores, the maximum gas generation rates of the two gas generation peaks in Example 2 are significantly reduced, greatly improving the safety of the single cell 300.

[0191] The test results of Example 3 show that the two outer first winding cores 310a experienced thermal runaway first, followed by the four inner second winding cores 310b. On the thermal runaway gas generation rate curve, a narrow slit appeared first, followed by a broad peak. Compared to Comparative Examples 1 to 3, the maximum gas generation rate of both gas generation peaks in Example 3 was significantly reduced, greatly improving the safety of the single-cell battery 300.

[0192] As shown in the test results of Example 4, since the areal density of the separator 312 and the areal density of the coating 3122 of the first core 310a, the second core 310b, and the third core 310c are all different, their thermal diffusivity is also different. Furthermore, the thermal diffusivity gradually decreases from the outside to the inside. Therefore, during thermal runaway, the two outermost first cores 310a experience thermal runaway first, followed by the two second cores 310b, and finally the two innermost third cores 310c. This results in three slits appearing on the thermal runaway gas generation rate curve. Compared to Comparative Examples 1 to 3, the maximum gas generation rate of the three gas generation peaks in Example 4 is significantly reduced, greatly improving the safety of the single-cell battery 300.

[0193] 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.

[0194] 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, characterized by, The monomer battery comprises a plurality of winding cores connected in parallel, the winding core comprises a positive pole sheet, a diaphragm and a negative pole sheet, and the diaphragm is located between the positive pole sheet and the negative pole sheet; the thermal diffusivity of the diaphragm of at least two winding cores in the plurality of winding cores is different.

2. The cell according to claim 1, wherein The monomer battery further comprises a shell having a receiving cavity for receiving the plurality of winding cores, and the plurality of winding cores are arranged in sequence; the plurality of winding cores comprises a first winding core and a second winding core, the thermal diffusivity of the diaphragm of the first winding core is greater than the thermal diffusivity of the diaphragm of the second winding core, and the first winding core is closer to the shell than the second winding core along the arrangement direction of the plurality of winding cores.

3. The cell according to claim 1, wherein The monomer battery further comprises a shell having a receiving cavity for receiving the plurality of winding cores, and the plurality of winding cores are arranged in sequence; along the arrangement direction of the plurality of winding cores, the thermal diffusivity of the diaphragm of the plurality of winding cores first gradually decreases and then gradually increases, and the thermal diffusivity of the diaphragm of the plurality of winding cores gradually decreases in the direction from the shell to the plurality of winding cores.

4. The cell according to claim 1, wherein At least two winding cores comprise a first winding core and a second winding core, the thermal diffusivity of the diaphragm of the first winding core is α1, the thermal diffusivity of the diaphragm of the second winding core is α2, and the monomer battery satisfies the relationship: 100% × (α1-α2) / α2≥5%.

5. The cell according to claim 1, wherein The diaphragm comprises a base film and a coating layer, and the coating layer is arranged on at least one of the two opposite surfaces of the base film; the monomer battery satisfies at least one of the following conditions: The face density of the diaphragm of at least two winding cores in the plurality of winding cores is different; The face density of the coating layer of at least two winding cores in the plurality of winding cores is different; The total thickness of the coating layer of at least two winding cores in the plurality of winding cores is different; and One surface of the base film of the diaphragm of one of the at least two winding cores is provided with the coating layer, and the two opposite surfaces of the diaphragm of the other winding core are both provided with the coating layer. At least two winding cores comprise a first winding core and a second winding core, the total thickness of the coating layer of the first winding core is d1, and the total thickness of the coating layer of the second winding core is d2, then 0.6≤d1 / d2≤0.

9.

6. The cell according to claim 5, wherein At least two of the winding cores include a first winding core and a second winding core, a face density of the separator of the first winding core is m A1 , a face density of the separator of the second winding core is m B1 , and 0.6≤m A1 / m B1 ≤0.

9.

7. The cell according to claim 6, wherein the areal density m of the separator of the first core A1 ranges from 5 g / m 2 ≤ m A1 ≤ 12 g / m 2 ; the areal density m of the separator of the second core B1 ranges from 5.5 g / m 2 ≤ m B1 ≤ 20 g / m 2 .

8. The cell according to claim 5, wherein At least two of the said cores include a first core and a second core, wherein the areal density of the coating on the first core is m. A2 The areal density of the coating of the second core is m. B2 Then 0.5≤m A2 / m B2 ≤0.

88.

9. The cell according to claim 8, wherein the areal density m of the coating of the first winding core A2 is in the range of 2 g / m 2 ≤ m A2 ≤ 7 g / m 2 ; the areal density m of the coating of the second winding core B2 is in the range of 2 g / m 2 ≤ m B2 ≤ 14 g / m 2 .

10. The cell according to claim 5, wherein The total thickness d1 of the coating layer of the first winding core ranges from 1μm≤d1≤5μm, and the total thickness d2 of the coating layer of the second winding core ranges from 1.5μm≤d2≤5.5μm.

11. The cell according to claim 10, wherein Comprise:

12. An energy storage device, characterized by One or more monomer batteries according to any one of claims 1-11. Comprise:

13. An energy storage system characterized by, A high-voltage cable, a first electric energy conversion device, a second electric energy conversion device and the energy storage device according to claim 12; the high-voltage cable is electrically connected to the energy storage device, the first electric energy conversion device and the second electric energy conversion device respectively, the first electric energy conversion device and the second electric energy conversion device are both used for generating electric energy, and the energy storage device is used for storing the electric energy. ​

Images