Secondary battery, battery pack, and electric device

Abstract

The invention discloses a secondary battery, a battery pack and electric equipment. The secondary battery includes a case, an end cap, a plurality of electrode units, a heat insulating member, and a heat conducting member. The shell is provided with an opening. The end cover is connected to the shell and covers the opening; and a plurality of electrode units accommodated in the housing and arranged along the first direction, each electrode unit comprising at least two electrode assemblies arranged along the first direction. And a heat insulation piece is arranged between the adjacent electrode units. And a heat conduction piece is arranged between the adjacent electrode assemblies of each electrode unit. In the first direction, the sum of the minimum sizes of the heat conduction pieces is T1 mm, the sum of the sizes of the heat insulation pieces is T2 mm, and the sum of the sizes of the electrode assemblies is T3 mm; 5.1 < = T3 / (T1 + T2) < = 15, and 4.8 < = T1 * T2 < = 30. The high-rate discharge temperature rise and thermal runaway probability can be reduced while the high energy density is maintained.

Description

Technical Field

[0001] This application relates to the field of batteries, and in particular to a secondary battery, a battery pack, and an electrical device. Background Technology

[0002] Lithium-ion batteries and other energy storage devices have been widely used in electric vehicles, portable electronic devices, energy storage power stations, and many other fields. As the core unit for battery energy storage and conversion, the electrode assembly's structural design and manufacturing process directly determine the battery's overall performance, while thermal management capability is a crucial factor in maintaining the battery's safe operation.

[0003] In the prior art, secondary batteries composed of multiple electrode components only have heat dissipation structures on the outside of the casing. This results in the Joule heat and exothermic reactions generated during charging and discharging not being quickly conducted to the outside. Local heat accumulation is easily formed inside the electrode components or between adjacent electrode components. When the temperature exceeds the threshold, it will trigger a chain reaction such as electrolyte decomposition and oxygen release from the positive electrode material, which in turn induces thermal runaway. Summary of the Invention

[0004] This application provides a secondary battery, battery pack, and electrical device that helps maintain a high energy density while reducing the temperature rise and probability of thermal runaway during high-rate discharge.

[0005] In a first aspect, embodiments of this application provide a secondary battery, comprising a casing, an end cap, multiple electrode units, a heat insulation component, and a heat-conducting component. The casing has an opening. The end cap is connected to the casing and closes the opening. Multiple electrode units are housed within the casing and arranged along a first direction, each electrode unit including at least two electrode assemblies arranged along the first direction. A heat insulation component is provided between adjacent electrode units. A heat-conducting component is provided between adjacent electrode assemblies of each electrode unit. Along the first direction, the sum of the minimum dimensions of the heat-conducting component is T1 mm, the sum of the dimensions of the heat insulation component is T2 mm, and the sum of the dimensions of the electrode assemblies is T3 mm; 5.1 ≤ T3 / (T1+T2) ≤ 15, and 4.8 ≤ T1×T2 ≤ 30.

[0006] According to the embodiments of this application, when the secondary battery satisfies 4.8≤T1×T2≤30, the heat-conducting and heat-insulating components construct a precise and efficient internal heat conduction path within the secondary battery. The heat-conducting component allows the Joule heat and exothermic reactions generated during high-rate charging and discharging of the electrode assembly to be quickly diffused and conducted to the casing / end cap of the secondary battery, reducing heat accumulation in the localized electrode assembly. Simultaneously, the heat-insulating component reduces heat accumulation between electrode units, promoting heat dissipation along the heat-conducting component within the electrode assembly, and effectively blocks heat transfer during thermal runaway. However, the addition of the heat-conducting and heat-insulating components reduces the energy density of the secondary battery. Based on this, when the secondary battery satisfies 5.1≤T3 / (T1+T2)≤15, the effective volume ratio of the electrode assembly can be maximized while improving the thermal management effect of the secondary battery.

[0007] When T1×T2 is less than 4.8, at least one or both of the minimum dimensions of multiple heat-conducting components (T1) and the total dimensions of the insulation components (T2) are at extremely low levels, leading to an imbalance in the internal heat transfer path design. If T1 is too small, the size of the heat-conducting components between electrode assemblies is insufficient, and the Joule heat generated by high-rate charging and discharging cannot be quickly diffused to the shell through the heat-conducting components, causing heat to accumulate locally in the electrode assemblies, forming hot spots. If T2 is too small, the size of the heat-conducting components between electrode units is insufficient, failing to form an effective thermal barrier. Even if there are heat-conducting components within the electrode units, heat between adjacent electrode units is easily cross-contaminated, resulting in poor overall temperature uniformity and a coexistence of local overheating and poor overall heat dissipation, further exacerbating the risk of heat accumulation. When T1×T2 is greater than 30, it means that the size of the heat-conducting or insulation components is over-designed, leading to a disordered heat transfer path. If T1 is too large, the redundant size of the heat-conducting components between the electrode components will increase the thermal conduction resistance (such as excessive stacking of the contact surface between the heat-conducting components and the electrode components, leading to increased contact thermal resistance), which will reduce the heat dissipation efficiency. At the same time, excessive heat-conducting components will cause the heat to transfer too quickly within the unit, and the local overheating of a single electrode component will quickly spread to the entire electrode unit, creating a risk of rapid expansion of local thermal runaway. If T2 is too large, the size of the heat-conducting components between the electrode units will be too large, which will hinder the overall heat dissipation channel inside the housing (such as affecting the heat transfer path between the heat-conducting components and the housing and end caps). This will cause the heat generated during normal charging and discharging to be unable to be conducted to the outside in time, resulting in overall heat accumulation. Even if the heat-conducting components can quickly dissipate the heat, the temperature will continue to rise because the external heat dissipation channel is blocked.

[0008] When T3 / (T1+T2) is less than 5.1, the total size of the heat-conducting and heat-insulating components is too large, which will encroach on the arrangement space of the electrode assembly and lead to a significant decrease in energy density. When T3 / (T1+T2) is greater than 15, the size of the heat-conducting and heat-insulating structure is insufficient and cannot meet the thermal management requirements.

[0009] In one or more of the above optional embodiments, the secondary battery satisfies at least one of the following: (1) 7.3≤T3 / (T1+T2)≤12; (2) 7.5≤T1×T2≤15.

[0010] In the above optional embodiments, when the secondary battery satisfies the condition 7.3≤T3 / (T1+T2)≤12, the total size of the electrode assembly and the total size of the thermally conductive-insulating structure achieve a precise match between heat dissipation demand and path supply. During high-rate charging and discharging, heat can be quickly diffused to the shell / end cap through the thermally conductive components, while reducing heat crosstalk between electrode units, thus achieving a precise balance between energy density and heat dissipation efficiency.

[0011] For secondary batteries, the optimal size coordination between the heat-conducting and heat-insulating components is achieved when 7.5 ≤ T1 × T2 ≤ 15. The heat-conducting component ensures sufficient contact with the electrode assembly and prevents excessive heat dissipation due to excessive size; the heat-insulating component forms an effective thermal barrier and does not obstruct the overall heat dissipation channel due to excessive size. During high-rate charging and discharging, this reduces the coexistence of localized hot spots and overall heat accumulation, effectively improving the battery's performance stability under high-rate conditions.

[0012] In one or more of the above optional embodiments, the secondary battery satisfies at least one of the following: (1) along the first direction, the multiple electrode assemblies have the same size; (2) along the first direction, the multiple heat conductors have the same minimum size; (3) along the first direction, the minimum size of a heat conductor is 1.2 mm to 3.5 mm; (4) along the first direction, the size of a heat insulation component is 2 mm to 5 mm.

[0013] In the above optional embodiments, when multiple electrode components are of the same size along the first direction, the current density, reactive area, and heat generation rate of electrode components of the same size are highly consistent during charging and discharging, reducing the problem of overcurrent heating of small-sized electrode components and heat accumulation of large-sized electrode components caused by differences in electrode component size. This effectively suppresses the formation of local hot spots and reduces the risk of thermal runaway.

[0014] Along the first direction, when multiple heat-conducting components have the same minimum size, heat-conducting components of the same size can form a uniform contact area and contact pressure with adjacent electrode components, so that the heat generated by the electrode components in the electrode unit can be quickly discharged through a unified path, reducing heat dissipation bottlenecks caused by some heat-conducting components being too small, or heat conduction redundancy caused by some components being too large.

[0015] Along the first direction, when the minimum size of a heat-conducting component is 1.2mm to 3.5mm, the heat-conducting component has both structural rigidity and flexibility, and is not easy to bend or break during assembly. At the same time, it can adapt to the expansion and contraction of the electrode assembly, and can still maintain close contact with the electrode assembly after long-term cycling.

[0016] Along the first direction, an effective thermal resistance layer can be formed when the size of a thermal insulation element is 2mm to 5mm. At the same time, it will not break due to structural fragility caused by being too small, nor will it deform due to thermal expansion stress caused by being too large.

[0017] In one or more of the above optional embodiments, the secondary battery satisfies at least one of the following: (1) along the first direction, the compressibility of the heat insulation component is less than that of the heat conduction component; (2) along the first direction, the compressibility of the heat conduction component is 50% to 70%; (3) along the first direction, the compressibility of the heat insulation component is 30% to 50%.

[0018] In the above optional embodiments, the compressibility of the heat insulation component is less than that of the heat conduction component. When the battery is slightly squeezed by external force or the component expands, the heat conduction component absorbs the deformation stress through compression to maintain the heat conduction path. The heat insulation component resists deformation with its lower compressibility, avoiding a decrease in thermal resistance due to thinning.

[0019] Along the first direction, when the compressibility of the heat-conducting component is 50% to 70%, the pore structure of the heat-conducting medium inside the heat-conducting component can remain connected after compression, so that the heat-conducting component maintains a small thermal conductivity decay rate.

[0020] Along the first direction, when the compressibility of the heat insulation component is 30% to 50%, the porous heat insulation structure inside the heat insulation component only undergoes partial deformation, and the thermal conductivity remains at a low level, allowing the heat insulation component to continue to function during the operation of the secondary battery.

[0021] In one or more of the above optional embodiments, the electrode assembly satisfies at least one of the following: (1) 40≤T3≤80; (2) along the third direction, the size of the electrode assembly is T4 mm, and 2.5≤T4 / T3≤10.

[0022] In the above optional embodiments, when the secondary battery satisfies 40≤T3≤80, this size range is well-suited to the internal space height in the first direction of the mainstream battery casing. This allows the total capacity of multiple electrode components to reach practical standards, reducing the low energy density caused by excessively small overall size, and also reducing the problem of internal thermal resistance accumulation caused by excessive stacking of electrode components. In addition, this size range provides sufficient space for the arrangement of heat-conducting components, improving their heat dissipation capacity and reducing the overall temperature difference of the electrode component cluster.

[0023] When the secondary battery satisfies the condition 2.5≤T4 / T3≤10, this ratio achieves structural balance of the electrode assembly in the first and third directions. The three-dimensional structure of the electrode assembly synergizes with the multidirectional thermal conductivity of the heat conductor, efficiently dissipating heat from the second and third directions to the casing and end caps through the heat conductor, reducing the temperature difference between the electrode assembly core and end caps during battery cycling. Furthermore, the balanced size ratio reduces ineffective space within the electrode assembly, resulting in a more uniform packing density of active materials.

[0024] In one or more of the above optional embodiments, the electrode assembly and the end cap are arranged along a third direction, and the secondary battery satisfies at least one of the following: (1) along the third direction, the size of the heat conductor is M mm, 205≤M≤412; (2) along the third direction, the size of the heat conductor is M mm, and the size of the electrode assembly is T4 mm, 5≤M-T4≤12.

[0025] In the above optional embodiments, when the secondary battery satisfies the condition that 205≤M≤412, the heat-conducting component can cover the extension range of the symmetrically distributed electrode assemblies on both sides in the third direction, reducing the problem of local hot spots caused by insufficient size preventing heat transfer to the heat-conducting component in some areas. Simultaneously, it adapts to the internal space of mainstream battery casings in the third direction, avoiding assembly difficulties or compression of the connection structure between the end cap and the electrode assembly due to excessive size.

[0026] When the secondary battery meets the condition 5≤M-T4≤12, the design where M is slightly larger than T4 achieves both precise coverage and flexible adaptation. The heat-conducting component can cover the electrode assembly in the third direction, reducing the increase in thermal resistance caused by assembly gaps that may exist when M=T4, thus lowering the contact thermal resistance between the heat-conducting component and the electrode assembly. Furthermore, the redundant dimensions of the heat-conducting component are controlled, preventing interference with the end cap or housing due to excessive protrusion of the electrode assembly. It also provides space for the slight expansion of the electrode assembly during battery charging and discharging, avoiding damage to the heat-conducting component due to structural stress. The heat-conducting component can transfer heat synchronously with the temperature changes of the electrode assembly, improving the thermal response speed in the third direction.

[0027] In one or more of the above optional embodiments, the heat-conducting component satisfies at least one of the following: (1) the material of the heat-conducting component includes one or more of graphite sheets, carbon nanotubes and carbon fibers; (2) the material of the heat insulation component includes one or more of phenolic resin, aerogel and polyurethane materials.

[0028] In one or more of the above optional embodiments, the heat-conducting component includes a main body and an extension, the main body being located between adjacent electrode assemblies, the extension being connected to an end of the main body along a third direction and extending along a first direction; the housing includes a bottom wall, the bottom wall and an end cap being arranged along a third direction; at least a portion of the extension is located between the bottom wall and the electrode assembly, and / or, at least a portion of the extension is located between the end cap and the electrode assembly.

[0029] In the above optional embodiments, the ends of the electrode assembly along the third direction are prone to forming end hotspots due to obstructed heat transfer to the housing. The extension has a larger dimension in the first direction, which can fully cover the gap between the end of the electrode assembly and the bottom wall / end cap, directly establishing a direct heat dissipation channel from the assembly end to the extension and the bottom wall / end cap, reducing heat transfer links and improving the heat dissipation efficiency of the electrode assembly end area. At the same time, the integrated design of the extension and the main body can collect the heat of adjacent electrode assemblies and guide it to the housing, reducing the cross-accumulation of heat within the assembly cluster and further improving heat dissipation efficiency.

[0030] Secondly, this application provides a battery pack that includes a secondary battery provided in any embodiment of the first aspect.

[0031] Thirdly, this application provides an electrical device that includes a secondary battery provided in any embodiment of the first aspect. Attached Figure Description

[0032] The features, advantages, and technical effects of exemplary embodiments of this application will now be described with reference to the accompanying drawings.

[0033] Figure 1 This is a schematic diagram of the structure of a secondary battery provided in some embodiments of this application; Figure 2 A cross-sectional schematic diagram of a secondary battery provided in some embodiments of this application; Figure 3 A front view of a heat-conducting component provided in some embodiments of this application; Figure 4 A front view of a heat-conducting component provided in other embodiments of this application; Figure 5 A front view of a heat-conducting component provided in some embodiments of this application; Figure 6 This is a schematic diagram of the battery pack structure provided in some embodiments of this application; Figure 7 This is a schematic diagram of the structure of an electrical device provided in some embodiments of this application.

[0034] The reference numerals in the accompanying drawings for the specific embodiments are as follows: Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of this application, but not all embodiments.

[0036] The terms "first," "second," "third," etc., used in the specification, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy. In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments.

[0037] In this application, the reference to "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0038] In the description of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0039] In the embodiments of this application, "parallel" includes not only the case of absolute parallelism, but also the case of approximate parallelism as commonly understood in engineering; similarly, "perpendicular" also includes not only the case of absolute perpendicularity, but also the case of approximate perpendicularity as commonly understood in engineering. For example, if the angle between two directions is 85°-95°, the two directions can be considered perpendicular; if the angle between two directions is 0°-10°, the two directions can be considered parallel.

[0040] The secondary battery, battery pack, and electrical equipment of this application are described below with reference to the accompanying drawings.

[0041] Reference Figures 1 to 3 This application provides a secondary battery 1. The secondary battery 1 can refer to a battery that can be used again after being discharged by recharging to activate the active materials.

[0042] As an example, the secondary battery 1 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.

[0043] As an example, the secondary battery 1 can be a prismatic battery, a pouch battery, or a battery of other shapes. Prismatic batteries include square-shell batteries, blade-shaped batteries, and multi-prismatic batteries, such as hexagonal prismatic batteries.

[0044] As an example, the rated capacity of secondary battery 1 can be C Ah, where 280 ≤ C ≤ 1200. For example, C can be 280, 300, 320, 360, 400, 420, 440, 460, 500, 600, 700, 800, 900, 100, 1100, 1200, or any range of the above values.

[0045] In some embodiments, the secondary battery 1 includes a housing 11, an end cap 12, an electrode unit 10, a heat-conducting element 13, and a heat-insulating element 14. The housing 11 has an opening, and the end cap 12 is connected to the housing 11 and closes the opening. The electrode unit 10 is housed within the housing 11.

[0046] The housing 11 is a component used to fit the end cap 12 to form the internal cavity of the secondary battery 1. The formed internal cavity can be used to accommodate the electrode unit 10, the heat conductor 13, the heat insulation component 14, the electrolyte, and other components.

[0047] The shell 11 can be of various shapes and sizes, such as cuboid, cylindrical, hexagonal prism, etc.

[0048] The shell 11 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc.

[0049] The shape of the end cap 12 can be adapted to the shape of the housing 11 to fit the housing 11. The material of the end cap 12 can be the same as or different from the material of the housing 11. Optionally, the end cap 12 can be made of a material with a certain hardness and strength (e.g., copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.).

[0050] The end cap 12 is connected to the housing 11 by welding, bonding, snap-fitting or other means.

[0051] The housing 11 may be open at one end or open at both ends. In some examples, the housing 11 may be a structure with an opening on one side, and one end cap 12 is provided to cover the housing 11. In other examples, the housing 11 may also be a structure with openings on both sides, and two end caps 12 are provided, with the two end caps 12 respectively covering the two openings of the housing 11.

[0052] In some embodiments, the secondary battery 1 includes a first direction X, a second direction Y, and a third direction Z, wherein the first direction X, the second direction Y, and the third direction Z are perpendicular to each other.

[0053] In some embodiments, the secondary battery 1 includes a plurality of electrode units 10, the end cap 12 and the plurality of electrode units 10 are arranged along a third direction Z, and the plurality of electrode units 10 are housed in the housing 11 along a first direction X.

[0054] As an example, the electrode unit 10 may be 2, 3, 4, 8 or more.

[0055] In some embodiments, a heat insulation element 14 is provided between at least some adjacent electrode units 10.

[0056] As an example, in the first direction X, at least a portion of the heat insulation element 14 is located between adjacent electrode units 10.

[0057] As an example, there may be one, two, three or more insulation elements.

[0058] In some embodiments, the electrode unit 10 may include a plurality of electrode assemblies 101. As an example, the electrode unit 10 may include two, three, four, five, six or more electrode assemblies 101.

[0059] Electrode assembly 101 is a component in the secondary battery 1 where electrochemical reactions occur. The housing 11 may contain electrode assembly 101. Exemplarily, electrode assembly 101 can be a wound structure or a stacked structure.

[0060] The electrode assembly 101 includes a first electrode, a second electrode, and a separator. The first and second electrodes have opposite polarities, and the separator separates the first and second electrodes. During the charging and discharging process of the secondary battery 1, active ions (such as lithium ions) repeatedly insert and extract between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, prevents short circuits between the positive and negative electrodes while allowing active ions to pass through.

[0061] In some embodiments, a heat-conducting element 13 is provided between at least some adjacent electrode assemblies 101.

[0062] As an example, in the first direction X, at least a portion of the heat conductor 13 is located between adjacent electrode assemblies 101.

[0063] In some embodiments, along the first direction X, the sum of the minimum dimensions of the heat-conducting element 13 is T1 mm, the sum of the dimensions of the heat-insulating element 14 is T2 mm, and the sum of the dimensions of the electrode assembly 101 is T3 mm; the secondary battery 1 satisfies: 5.1≤T3 / (T1+T2)≤15, and 4.8≤T1×T2≤30.

[0064] As an example, T3 / (T1+T2) can be 5.1, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or any of the above values.

[0065] As an example, T1×T2 can be 4.8, 8, 10, 12, 15, 18, 20, 22, 25, 28, 30, or any of the above values.

[0066] Optionally, 5.5≤T3 / (T1+T2)≤15, 6≤T3 / (T1+T2)≤15, 6.5≤T3 / (T1+T2)≤15, 7≤T3 / (T1+T2)≤15, 7.3≤T3 / (T1+T2)≤15, 7.3≤T3 / (T1+T2)≤14.5, 7.3≤T3 / (T1+T2)≤14, 7.3≤T3 / (T1+T2)≤13.5, 7.3≤T3 / (T1+T2)≤13, 7.3≤T3 / (T1+T2)≤12.5, 7.3≤T3 / (T1+T2)≤12.

[0067] Optionally, 5≤T1×T2≤30, 5.5≤T1×T2≤30, 6≤T1×T2≤30, 6.5≤T1×T2≤30, 7≤T1×T2≤30, 7.5≤T1×T2≤30, 7.5≤T1×T2≤30, 7.5≤T1×T2≤28, 7.5≤T1×T2≤25, 7.5≤T1×T2≤22, 7.5≤T1×T2≤20, 7.5≤T1×T2≤15.

[0068] According to the embodiments of this application, when the secondary battery 1 satisfies 4.8≤T1×T2≤30, the heat-conducting component 13 and the heat-insulating component 14 construct a precise and efficient internal heat conduction path within the secondary battery 1. The heat-conducting component 13 allows the Joule heat and side reaction exothermic generated by the electrode assembly 101 during high-rate charging and discharging to be quickly diffused and conducted to the casing 11 / end cap 12 of the secondary battery 1, reducing the local accumulation of heat in the electrode assembly 101. At the same time, the heat-insulating component 14 can reduce the accumulation of heat between the electrode units 10, promoting the heat in the electrode assembly 101 to be discharged along the heat-conducting component 13, and can also effectively block the heat transfer during thermal runaway. However, the addition of the heat-conducting component 13 and the heat-insulating component 14 will reduce the energy density of the secondary battery 1. Based on this, when the secondary battery 1 satisfies 5.1≤T3 / (T1+T2)≤15, the effective volume ratio of the electrode assembly 101 can be maximized while improving the thermal management effect of the secondary battery 1.

[0069] Furthermore, when the secondary battery 1 satisfies the condition 7.3≤T3 / (T1+T2)≤12, the total size of the electrode assembly 101 and the total size of the thermally conductive-insulating structure achieve a precise match between heat dissipation demand and path supply. During high-rate charging and discharging, heat can be rapidly diffused to the housing 11 / end cap 12 through the thermally conductive component 13, while reducing heat crosstalk between electrode units 10, thus achieving a precise balance between energy density and heat dissipation efficiency.

[0070] Furthermore, when the secondary battery 1 satisfies the condition 7.5 ≤ T1 × T2 ≤ 15, the size coordination between the heat-conducting component 13 and the heat-insulating component 14 reaches its optimal state. The heat-conducting component 13 can ensure sufficient contact with the electrode assembly 101 and will not cause excessive heat dissipation due to excessive size; the heat-insulating component 14 can form an effective thermal barrier and will not obstruct the overall heat dissipation channel due to excessive size. During high-rate charging and discharging, the problem of local hot spots and overall heat accumulation can be reduced, effectively improving the performance stability of the battery under high-rate conditions.

[0071] When T1×T2 is less than 4.8, at least one or both of the total dimensions T1 of the heat-conducting component 13 and T2 of the heat-insulating component 14 are at extremely low levels, leading to an imbalance in the internal heat transfer path design. If T1 is too small, the size of the heat-conducting component 13 between the electrode assemblies 101 is insufficient, and the Joule heat generated by high-rate charging and discharging cannot be quickly diffused to the shell 11 through the heat-conducting component 13. Heat will accumulate locally in the electrode assembly 101, forming hot spots. If T2 is too small, the size of the heat-insulating component 14 between the electrode units 10 is insufficient, and an effective thermal barrier cannot be formed. Even if there is a heat-conducting component 13 inside the electrode unit 10, the heat between adjacent electrode units 10 is easily disturbed, resulting in poor overall temperature uniformity. This leads to the coexistence of local overheating and poor overall heat dissipation, further exacerbating the risk of heat accumulation. When T1×T2 is greater than 30, it means that the size of the heat-conducting component 13 or the heat-insulating component 14 is over-designed, resulting in disordered heat transfer paths. If T1 is too large, the size of the heat-conducting component 13 between the electrode components 101 will be redundant, which will increase the thermal conduction resistance (such as excessive stacking of the contact surface between the heat-conducting component 13 and the electrode components 101, resulting in increased contact thermal resistance), thus reducing the heat dissipation efficiency. At the same time, excessive heat-conducting components 13 will cause the heat to transfer too quickly within the unit, and the local overheating of a single electrode component 101 will quickly spread to the entire electrode unit 10, forming a risk of rapid expansion of local thermal runaway. If T2 is too large, the size of the heat-conducting component 14 between the electrode unit 10 will be too large, which will hinder the overall heat dissipation channel inside the housing 11 (such as affecting the heat transfer path between the heat-conducting component 13 and the housing 11 and the end cap 12), causing the heat generated during normal charging and discharging to be unable to be conducted to the outside in time, forming overall heat accumulation. Even if the heat-conducting component 13 can quickly dissipate heat, the temperature will continue to rise because the external heat dissipation channel is blocked.

[0072] When T3 / (T1+T2) is less than 5.1, the total size of the heat-conducting component 13 and the heat-insulating component 14 is too large, which will encroach on the arrangement space of the electrode assembly 101, resulting in a significant decrease in energy density. When T3 / (T1+T2) is greater than 15, the size of the heat-conducting-heat-insulating structure is insufficient and cannot meet the thermal management requirements.

[0073] In some embodiments, multiple electrode components 101 are identical in size along the first direction X. Electrode components 101 of the same size exhibit highly consistent current density, reactive regions, and heat generation rates during charging and discharging, reducing overcurrent heating in smaller electrode components 101 and heat accumulation in larger electrode components 101 due to size differences. This effectively suppresses the formation of localized hot spots and reduces the risk of thermal runaway.

[0074] In some embodiments, the minimum dimensions of the plurality of heat-conducting elements 13 are the same along the first direction X. Heat-conducting elements 13 of the same size can form a uniform contact area and contact pressure with adjacent electrode assemblies 101, so that the heat generated by the electrode assemblies 101 in the electrode unit 10 can be quickly discharged through a unified path, reducing heat dissipation bottlenecks caused by some heat-conducting elements 13 being too small, or heat conduction redundancy caused by some being too large.

[0075] In some embodiments, along the first direction X, the minimum dimension of a heat-conducting element 13 is 1.2 mm to 3.5 mm. For example, it can be 1.2 mm, 1.5 mm, 1.8 mm, 2 mm, 2.2 mm, 2.5 mm, 2.8 mm, 3 mm, 3.2 mm, 3.5 mm, or any range of the above values. When the minimum dimension of a heat-conducting element 13 is 1.2 mm to 3.5 mm, the heat-conducting element 13 has both structural rigidity and flexibility, is not easily bent or broken during assembly, and can adapt to the expansion and contraction of the electrode assembly 101, maintaining close contact with the electrode assembly 101 even after long-term cycling.

[0076] In some embodiments, the size of a thermal insulation element 14 along the first direction X is 2 mm to 5 mm. For example, it can be 2 mm, 2.2 mm, 2.5 mm, 2.8 mm, 3 mm, 3.2 mm, 3.5 mm, 3.8 mm, 4 mm, 4.2 mm, 4.5 mm, 4.8 mm, 5 mm, or any range of the above values. When the size of a thermal insulation element 14 is 2 mm to 5 mm, an effective thermal resistance layer can be formed. At the same time, it will not break due to structural fragility caused by excessively small size, nor will it cause deformation of the shell 11 due to thermal expansion stress caused by excessively large size.

[0077] In some embodiments, along the first direction X, the compressibility of the heat insulation element 14 is less than that of the heat conduction element 13. When the battery is slightly squeezed by an external force or the component expands, the heat conduction element 13 absorbs deformation stress through compression, maintaining the unobstructed heat conduction path; while the heat insulation element 14 resists deformation with its lower compressibility, avoiding a decrease in thermal resistance due to thinning.

[0078] In some embodiments, the compressibility of the heat-conducting element 13 along the first direction X is 50% to 70%. For example, it can be 50%, 52%, 55%, 58%, 60%, 62%, 65%, 68%, 70%, or any range of the above values. When the compressibility of the heat-conducting element 13 is 50% to 70%, the pore structure of the heat-conducting medium inside the heat-conducting element 13 can remain connected after compression, so that the heat-conducting element 13 maintains a small rate of thermal conductivity decay.

[0079] In some embodiments, the compressibility of the heat insulation element 14 along the first direction X is 30% to 50%. For example, it can be 30%, 32%, 35%, 38%, 40%, 42%, 45%, 48%, 50%, or any range of the above values. When the compressibility of the heat insulation element 14 is 30% to 50%, the porous heat insulation structure inside the heat insulation element 14 only undergoes partial deformation, and the thermal conductivity remains at a low level, allowing the heat insulation element 14 to continue to function during the operation of the secondary battery 1.

[0080] In some embodiments, along the first direction X, the sum of the dimensions of the plurality of electrode assemblies 101 is T3 mm, where 40 ≤ T3 ≤ 80. For example, T3 can be 40, 45, 50, 55, 60, 65, 70, 75, 80, or any range of the above values.

[0081] In the above embodiments, when the secondary battery 1 satisfies 40≤T3≤80, this size range is well-suited to the internal space height of the casing 11 in the first direction X of the mainstream battery. This allows the total capacity of multiple electrode components 101 to reach a practical standard, reducing the low energy density caused by an excessively small total size, and also reducing the problem of internal thermal resistance accumulation caused by excessive stacking of electrode components 101. In addition, this size range provides sufficient space for the arrangement of the heat-conducting component 13, improving the heat dissipation capacity of the heat-conducting component 13 and reducing the overall temperature difference of the electrode component 101 cluster.

[0082] In some embodiments, along the third direction Z, the size of the electrode assembly 101 is T4 mm, and 2.5 ≤ T4 / T3 ≤ 10. For example, T4 / T3 can be 2.5, 3, 4, 5, 6, 7, 8, 9, 10, or any range of the above values.

[0083] In the above embodiments, when the secondary battery 1 satisfies the condition 2.5≤T4 / T3≤10, this ratio achieves structural balance of the electrode assembly 101 in the first direction X and the third direction Z. The three-dimensional structure of the electrode assembly 101 synergizes with the multidirectional thermal conductivity of the heat conductor 13, and the heat in the second direction Y and the third direction Z is efficiently conducted to the housing 11 and the end cap 12 through the heat conductor 13, reducing the temperature difference between the core of the electrode assembly 101 and the end cap 12 during the cycling of the secondary battery 1. In addition, the balanced size ratio reduces the ineffective space inside the electrode assembly 101, and the packing density of the active material is more uniform.

[0084] In some embodiments, the size of the heat-conducting element 13 along the third direction Z is M mm, where 205 ≤ M ≤ 412. For example, M can be 205, 220, 250, 280, 300, 320, 350, 380, 400, 412, or any range of the above values.

[0085] In the above embodiments, when the secondary battery 1 satisfies 205≤M≤412, the heat-conducting element 13 can cover the extension range of the symmetrically distributed electrode assemblies 101 in the third direction Z, reducing the problem of local hot spots caused by insufficient size preventing heat transfer to the heat-conducting element 13 in some areas. At the same time, it adapts to the third direction Z internal space of the casing 11 of mainstream batteries, and will not cause assembly difficulties or compress the connection structure between the end cap 12 and the electrode assembly 101 due to excessive size.

[0086] In some embodiments, along the third direction Z, the size of the heat-conducting element 13 is M mm, and the size of the electrode assembly 101 is T4 mm, where 5 ≤ M - T4 ≤ 12. For example, M - T4 can be 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, or any range of the above values.

[0087] In the above embodiment, when the secondary battery 1 satisfies the condition 5≤M-T4≤12, the design where M is slightly larger than T4 achieves the dual effects of precise coverage and flexible adaptation. The heat-conducting component 13 can cover the electrode assembly 101 in the third direction Z, reducing the increase in thermal resistance caused by the assembly gap that may exist when M=T4, thus lowering the contact thermal resistance between the heat-conducting component 13 and the electrode assembly 101. Furthermore, the redundant dimensions of the heat-conducting component 13 are controlled, preventing interference with the end cap 12 or the housing 11 due to excessive protrusion of the electrode assembly 101. At the same time, space is reserved for the slight expansion of the electrode assembly 101 during battery charging and discharging, avoiding damage to the heat-conducting component 13 caused by structural stress. The heat-conducting component 13 can transfer heat synchronously with the temperature change of the electrode assembly 101, thereby improving the thermal response speed in the third direction Z.

[0088] In some embodiments, the thermal conductivity of the heat-conducting element 13 can be from 100 W / (m·K) to 1500 W / (m·K), for example, it can be 100 W / (m·K), 200 W / (m·K), 300 W / (m·K), 400 W / (m·K), 500 W / (m·K), 600 W / (m·K), 700 W / (m·K), 800 W / (m·K), 900 W / (m·K), 1000 W / (m·K), 1100 W / (m·K), 1200 W / (m·K), 1300 W / (m·K), 1400 W / (m·K), 1500 W / (m·K), or any range of the above values.

[0089] In some embodiments, the thermal conductivity of the insulation element 14 can be 0.01 W / (m·K) to 0.1 W / (m·K), for example, it can be 0.01 W / (m·K), 0.012 W / (m·K), 0.015 W / (m·K), 0.018 W / (m·K), 0.02 W / (m·K), 0.03 W / (m·K), 0.04 W / (m·K), 0.05 W / (m·K), 0.06 W / (m·K), 0.07 W / (m·K), 0.08 W / (m·K), 0.09 W / (m·K), 0.1 W / (m·K), or any range of the above values.

[0090] In some embodiments, the material of the heat-conducting element 13 includes one or more of graphite sheets, carbon nanotubes, and carbon fibers.

[0091] In some embodiments, the material of the thermal insulation element 14 includes one or more of phenolic resin, aerogel, and polyurethane materials.

[0092] In some embodiments, refer to Figures 3 to 5 The heat-conducting component 13 includes a main body 131 and an extension 132. The main body 131 is located between adjacent electrode assemblies 101, and the extension 132 is connected to the end of the main body 131 along a third direction Z and extends along a first direction X. The housing 11 includes a bottom wall 111, which is arranged with an end cap 12 along a third direction Z. At least a portion of the extension 132 is located between the bottom wall 111 and the electrode assembly 101, or at least a portion of the extension 132 is located between the end cap 12 and the electrode assembly 101.

[0093] In some embodiments, the heat-conducting member 13 includes a main body 131 and an extension 132. The main body 131 is located between adjacent electrode assemblies 101, and the extension 132 is connected to an end of the main body 131 along a third direction Z and extends along a first direction X. The housing 11 includes a bottom wall 111, which is arranged with an end cap 12 along a third direction Z. At least a portion of the extension 132 is located between the bottom wall 111 and the electrode assembly 101, and at least a portion of the extension 132 is located between the end cap 12 and the electrode assembly 101.

[0094] In the above embodiment, the end of the electrode assembly 101 along the third direction Z is prone to heat transfer obstruction to the housing 11, forming an end hotspot. The extension 132 has a larger dimension in the first direction X, which can fully cover the gap between the end of the electrode assembly 101 and the bottom wall 111 / end cap 12, directly establishing a direct heat dissipation channel from the end of the electrode assembly 101 to the extension and the bottom wall 111 / end cap 12, reducing heat transfer links and improving the heat dissipation efficiency of the end area of ​​the electrode assembly 101. At the same time, the integrated design of the extension 132 and the main body 131 can collect the heat of adjacent electrode assemblies 101 and guide it to the housing 11 / end cap 12, reducing the cross-accumulation of heat within the cluster of electrode assemblies 101, further improving the heat dissipation efficiency.

[0095] According to the second aspect of this application, please refer to Figure 6 This application also provides a battery pack 1000, which includes a plurality of secondary batteries 1 provided according to any embodiment of this application.

[0096] In some embodiments, the battery pack 1000 further includes a plurality of busbars. The busbars are connected to the secondary batteries 1. At least two secondary batteries 1 can be connected in series or in parallel via the busbars.

[0097] According to the third aspect of this application, please refer to Figure 7 This application also provides an electrical device 2000, which includes a secondary battery 1 provided in any embodiment of this application. The secondary battery 1 can provide electrical energy for the operation of the electrical device 2000.

[0098] The electrical device 2000 in this application embodiment can be a portable device, a laptop computer, an electric toy, a drone, a power tool, an energy storage system, a new energy vehicle, etc. Power tools include metal cutting power tools, cleaning tools, etc., such as electric drills, electric wrenches, vacuum cleaners, robot vacuum cleaners, etc. This application embodiment does not impose any special limitations on the aforementioned electrical device 2000. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc.

[0099] The secondary battery 1 used as an example in this application has a charging cut-off voltage of 3.65V and a discharging cut-off voltage of 2.5V. The charging and discharging cut-off voltages of the secondary battery 1 can be based on the information printed on the outer packaging or the product specification sheet. The charging and discharging current values ​​of the secondary battery 1 can be calculated based on the rated capacity printed on the outer packaging and the multiplier specified in this application's specification.

[0100] Performance testing (1) Temperature rise test of secondary battery at high rate discharge The secondary battery was left to stand at 25℃ for 30 minutes, then discharged to 2.5V at a current of 0.2C, and left to stand for 15 minutes. It was then charged at a constant current of 1C to 3.65V, followed by constant voltage charging, stopping when the current reached 0.02C. After standing for 60 minutes, the battery was discharged to 2.5V at a current of 2C. Temperature sensing wires were attached to the middle, end caps, and bottom wall of the secondary battery using Teflon to monitor the highest temperature of the secondary battery during the test. The rate discharge temperature rise = (highest temperature - 25)℃.

[0101] For each embodiment or comparative example, three parallel samples were tested, and the average value was calculated.

[0102] (2) Secondary battery energy density test The secondary batteries used in the examples or comparative examples were subjected to the following tests at 25°C: Step 1: Use a precision measuring tool (such as a vernier caliper) to measure the length, width, and height of the secondary battery, and calculate the volume of the secondary battery (L).

[0103] Step 2: Place the secondary battery in a 25°C constant temperature chamber and let it stand for 30 minutes. Then, charge the secondary battery with a constant current at a charging current of 0.2C until it reaches 3.65V. Next, charge it with a constant voltage until the current reaches 0.02C. Finally, discharge it with a constant current at a discharging current of 0.2C until the voltage reaches 2.5V. Record the discharge capacity (Ah) and the average discharge voltage (V).

[0104] Step 3: Calculate the volumetric energy density according to the formula based on the measurement and test data, and take the average value of three tests. Volumetric energy density (Wh / L) = battery capacity (Ah) × discharge platform voltage (V) / cell volume (L). Take the average value of three parallel samples for each embodiment or comparative example test.

[0105] (3) Thermal runaway test of secondary battery Thermal runaway tests were conducted on the secondary batteries used in the examples or comparative examples, specifically including the following steps: a) Place the secondary battery 1, which has been fully charged (the secondary battery is left to stand in a 25°C environment for 30 minutes, discharged to 2.5V with a 0.2C current, left to stand for 15 minutes; charged to 3.65V with a 1C constant current, then switched to constant voltage charging, and stopped charging when the current reaches 0.02C, at which point it is fully charged), into a high-temperature furnace.

[0106] b) After the battery is fully charged, continue charging at a constant current of 1C and start heating (heating rate 3℃ / s). When the battery temperature reaches 300℃ or the test time reaches 4 hours, stop charging and heating, and observe for 1 hour.

[0107] c) Passing condition: The battery does not catch fire or explode.

[0108] For each embodiment or comparative example, 20 parallel samples were tested to calculate the thermal runaway test pass rate.

[0109] Example The following embodiments describe the contents disclosed in this application in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosures in this application.

[0110] Example 1 <Secondary Battery Preparation> Four identical electrode assemblies 101 with a total capacity of 280Ah are named JR1, JR2, JR3, and JR4, respectively. Each battery assembly has a capacity of 70Ah. JR1, thermal conductive element 13, JR2, thermal insulation element 14, JR3, thermal conductive element 13, and JR4 are stacked in sequence. After welding tabs to the electrode assemblies 101, they are placed in the housing 11, and electrolyte is injected. After vacuum drying, standing, formation, capacity testing, and other processes, a secondary battery 1 is obtained.

[0111] Each electrode assembly 101 has dimensions of 16.5 mm in the first X direction, 170 mm in the second Y direction, and 200 mm in the third Z direction. The two heat-conducting components 13 each have dimensions of 2.5 mm in the first X direction, 170 mm in the second Y direction, and 210 mm in the third Z direction. The heat insulation component 14 has dimensions of 3 mm in the first X direction, 170 mm in the second Y direction, and 200 mm in the third Z direction. Both heat-conducting components 13 are made of artificial graphite sheets with a thermal conductivity of 800 W / (m·K). The heat insulation component 14 is made of aerogel with a thermal conductivity of 0.014 W / (m·K).

[0112] Examples 2 to 18 and Comparative Examples 1 to 9 Examples 2 to 11 and Comparative Examples 1 to 9 are prepared in a manner basically the same as that of Example 1. The main differences are in the capacity of the electrode assembly, the sum of the first direction X dimensions of the electrode assembly (T3), the sum of the minimum first direction X dimensions of the heat-conducting component (T1), and the sum of the first direction X dimensions of the heat-insulating component (T2). See Table 1 for details.

[0113] The difference between Embodiment 2 and Embodiment 1 is that the minimum dimension of the first direction X of the heat-conducting component 13 is 3.5 mm, and the dimension of the first direction X of the heat insulation component 14 is 2 mm.

[0114] The difference between Example 3 and Example 1 is that the minimum dimension of the first direction X of the heat-conducting component 13 is 1.2 mm, and the dimension of the first direction X of the heat insulation component 14 is 5 mm.

[0115] The difference between Example 4 and Example 1 is that the minimum dimension of the first direction X of the heat-conducting component 13 is 1.5mm, and the dimension of the first direction X of the heat insulation component 14 is 2.5mm.

[0116] The difference between Example 5 and Example 1 is that the minimum dimension of the first direction X of the heat-conducting component 13 is 1.8 mm, and the dimension of the first direction X of the heat insulation component 14 is 2 mm.

[0117] The difference between Example 6 and Example 1 is that the minimum dimension of the first direction X of the heat-conducting component 13 is 3mm, and the dimension of the first direction X of the heat insulation component 14 is 5mm.

[0118] The difference between Example 7 and Example 1 is that the minimum dimension of the first direction X of the heat-conducting component 13 is 1.2 mm, and the dimension of the first direction X of the heat insulation component 14 is 4 mm.

[0119] The difference between Example 8 and Example 1 is that the third-direction Z dimension of the heat-conducting component 13 is 205mm.

[0120] The difference between Example 9 and Example 1 is that the total capacity of the electrode assembly 101 is 587 Ah, meaning the capacity of a single electrode assembly is 146.75 Ah. The dimensions of a single electrode assembly 101 are 16.5 mm in the first direction (X), 220 mm in the second direction (Y), and 270 mm in the third direction (Z). The dimensions of both heat-conducting components 13 are 2.5 mm in the first direction (X), 220 mm in the second direction (Y), and 280 mm in the third direction (Z). The dimensions of the heat insulation component 14 are 3 mm in the first direction (X), 220 mm in the second direction (Y), and 270 mm in the third direction (Z).

[0121] The difference between Example 10 and Example 9 is that the minimum dimension of the first direction X of the heat-conducting component 13 is 3.5 mm, and the dimension of the first direction X of the heat insulation component 14 is 2 mm.

[0122] The difference between Example 11 and Example 9 is that the minimum dimension of the first direction X of the heat-conducting component 13 is 1.2 mm, and the dimension of the first direction X of the heat insulation component 14 is 5 mm.

[0123] The difference between Example 12 and Example 9 is that the minimum dimension of the first direction X of the heat-conducting component 13 is 1.5 mm, and the dimension of the first direction X of the heat insulation component 14 is 2.5 mm.

[0124] The difference between Example 13 and Example 9 is that the minimum dimension of the first direction X of the heat-conducting component 13 is 1.2 mm, and the dimension of the first direction X of the heat insulation component 14 is 2 mm.

[0125] The difference between Example 14 and Example 1 is that the total capacity of the electrode assembly 101 is 1200Ah, meaning the capacity of a single electrode assembly 101 is 300Ah. The dimensions of a single electrode assembly 101 are 14mm in the first direction (X), 580mm in the second direction (Y), and 400mm in the third direction (Z). The dimensions of both heat-conducting components 13 are 2.5mm in the first direction (X), 580mm in the second direction (Y), and 412mm in the third direction (Z). The dimensions of the heat insulation component 14 are 3mm in the first direction (X), 220mm in the second direction (Y), and 270mm in the third direction (Z).

[0126] The difference between Example 15 and Example 14 is that the minimum dimension of the first direction X of the heat-conducting component 13 is 3.5 mm, and the dimension of the first direction X of the heat insulation component 14 is 2 mm.

[0127] The difference between Example 16 and Example 14 is that the minimum dimension of the first direction X of the heat-conducting component 13 is 1.2 mm, and the dimension of the first direction X of the heat insulation component 14 is 5 mm.

[0128] The difference between Example 17 and Example 14 is that the minimum dimension of the first direction X of the heat-conducting component 13 is 3mm, and the dimension of the first direction X of the heat insulation component 14 is 5mm.

[0129] The difference between Example 18 and Example 14 is that the minimum first direction X of the heat-conducting component 13 is 1.2 mm, and the first direction X dimension of the heat insulation component 14 is 2 mm.

[0130] The difference between Comparative Example 1 and Example 1 is that the minimum dimension of the first direction X of the heat-conducting element 13 is 0.5 mm, and the dimension of the first direction X of the heat insulation element 14 is 3 mm.

[0131] The difference between Comparative Example 2 and Example 1 is that the minimum dimension of the first direction X of the heat-conducting element 13 is 1 mm, and the dimension of the first direction X of the heat insulation element 14 is 2 mm.

[0132] The difference between Comparative Example 3 and Example 1 is that the minimum dimension of the first direction X of the heat-conducting element 13 is 0.25 mm, and the dimension of the first direction X of the heat insulation element 14 is 3 mm.

[0133] The difference between Comparative Example 4 and Example 1 is that the minimum dimension of the first direction X of the heat-conducting element 13 is 3.5 mm, and the dimension of the first direction X of the heat insulation element 14 is 0.4 mm.

[0134] The difference between Comparative Example 5 and Example 1 is that the minimum dimension of the first direction X of the heat-conducting element 13 is 3mm, and the dimension of the first direction X of the heat insulation element 14 is 8mm.

[0135] The difference between Comparative Example 6 and Example 1 is that the minimum dimension of the first direction X of the heat-conducting element 13 is 4 mm, and the dimension of the first direction X of the heat insulation element 14 is 6 mm.

[0136] The difference between Comparative Example 7 and Example 1 is that the secondary battery 1 does not have a heat insulation component 14.

[0137] The difference between Comparative Example 8 and Example 1 is that the secondary battery 1 does not have a heat-conducting component 13.

[0138] The difference between Comparative Example 9 and Example 1 is that the secondary battery 1 does not have a heat-conducting component 13 and a heat-insulating component 14.

[0139] Table 1 Note: In Table 1, " / " indicates that the secondary battery does not contain the corresponding parameters, that is, the secondary battery does not have heat-conducting and / or heat-insulating components.

[0140] According to Table 1, when the secondary battery satisfies the following conditions: 5.1≤T3 / (T1+T2)≤15 and 4.8≤T1×T2≤30, the secondary battery has both a lower rate discharge temperature rise, a higher energy density, and a higher thermal runaway test pass rate.

[0141] According to Examples 1 to 5 and Examples 8 to 10, when the secondary battery satisfies 7.3≤T3 / (T1+T2)≤12 and / or 7.5≤T1×T2≤15, the secondary battery has better rate discharge temperature rise, energy density and thermal runaway test pass rate.

[0142] Although this application has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A secondary battery, characterized in that, include: The shell has an opening; End cap, connected to the housing and covering the opening; Multiple electrode units are arranged along a first direction, and each electrode unit includes at least two electrode assemblies arranged along the first direction; A heat insulation element is provided between adjacent electrode units; A heat-conducting component is provided between adjacent electrode assemblies of each electrode unit; Along the first direction, the sum of the minimum dimensions of the heat-conducting components is T1 mm, the sum of the dimensions of the heat-insulating components is T2 mm, and the sum of the dimensions of the electrode assembly is T3 mm. 5.1≤T3 / (T1+T2)≤15, and 4.8≤T1×T2≤30.

2. The secondary battery according to claim 1, characterized in that, The secondary battery satisfies at least one of the following: (1)7.3≤T3 / (T1+T2)≤12; (2) 7.5 ≤ T1 × T2 ≤ 15.

3. The secondary battery according to claim 1 or 2, characterized in that, The secondary battery satisfies at least one of the following: (1) Along the first direction, the plurality of electrode assemblies are of the same size; (2) Along the first direction, the minimum dimensions of the plurality of heat-conducting elements are the same; (3) Along the first direction, the minimum dimension of one of the heat-conducting elements is 1.2 mm to 3.5 mm; (4) Along the first direction, the size of one of the heat insulation elements is 2 mm to 5 mm.

4. The secondary battery according to any one of claims 1 to 3, characterized in that, The secondary battery satisfies at least one of the following: (1) Along the first direction, the compressibility of the thermal insulation element is less than that of the thermal conductive element; (2) Along the first direction, the compressibility of the heat-conducting element is 50%~70%; (3) Along the first direction, the compressibility of the thermal insulation element is 30% to 50%.

5. The secondary battery according to any one of claims 1 to 4, characterized in that, The electrode assembly satisfies at least one of the following: （1）40≤T3≤80； (2) Along the third direction, the size of the electrode assembly is T4 mm, 2.5≤T4 / T3≤10.

6. The secondary battery according to any one of claims 1 to 5, characterized in that, The electrode assembly and the end cap are arranged along a third direction, and the secondary battery satisfies at least one of the following: (1) Along the third direction, the size of the heat-conducting element is M mm, where 205 ≤ M ≤ 412; (2) Along the third direction, the size of the heat-conducting element is M mm, and the size of the electrode assembly is T4 mm, 5≤M-T4≤12.

7. The secondary battery according to any one of claims 1 to 6, characterized in that, The heat-conducting component satisfies at least one of the following: (1) The material of the heat-conducting component includes one or more of graphite sheets, carbon nanotubes and carbon fibers; (2) The material of the heat insulation component includes one or more of phenolic resin, aerogel and polyurethane materials.

8. The secondary battery according to any one of claims 1 to 7, characterized in that, The heat-conducting component includes a main body and an extension, the main body being located between adjacent electrode assemblies, and the extension being connected to the end of the main body along the third direction and extending along the first direction; The housing includes a bottom wall, which is arranged with the end cap in a third direction; At least a portion of the extension is located between the bottom wall and the electrode assembly, and / or at least a portion of the extension is located between the end cap and the electrode assembly.

9. A battery pack, characterized in that, Includes the secondary battery according to any one of claims 1 to 8.

10. An electrical appliance, characterized in that, Includes the secondary battery according to any one of claims 1 to 8.

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