Secondary battery and electric device

Abstract

The application provides a secondary battery and a power consumption device. The secondary battery comprises a shell, an electrode assembly and a support. The shell comprises a top wall, a bottom wall and a side wall. The top wall and the bottom wall are oppositely arranged along a first direction. The side wall is connected to the top wall and the bottom wall. The top wall is provided with a pressure relief mechanism. The electrode assembly is arranged in the shell. The support is arranged between the bottom wall and the electrode assembly. The support has a first channel. The electrode assembly and the side wall are spaced apart to form a first spacing space. The first spacing space is communicated with the first channel. The first channel is used for guiding the gas discharged from the electrode assembly towards the bottom wall to the first spacing space. The secondary battery can improve the discharge speed of the gas between the electrode assembly and the bottom wall during thermal runaway, and improve the safety performance of the secondary battery.

Description

Technical Field

[0001] This application relates to the field of battery technology, and more specifically, to a secondary battery and an electrical device. Background Technology

[0002] In the process of improving battery energy density, large-capacity design has become an important direction. However, currently, large-capacity batteries generate a large amount of gas when thermal runaway is triggered. The gas accumulation at the bottom of the battery can easily cause internal short circuits, affecting the battery's safety performance. Summary of the Invention

[0003] This application provides a secondary battery and an electrical device that can help improve the safety performance of the secondary battery.

[0004] In a first aspect, this application provides a secondary battery, which includes a casing, an electrode assembly, and a support. The casing includes a top wall, a bottom wall, and a side wall. The top wall and the bottom wall are disposed opposite each other along a first direction, and the side wall connects the top wall and the bottom wall. The top wall is provided with a pressure relief mechanism. The electrode assembly is disposed within the casing. The support is disposed between the bottom wall and the electrode assembly, and the support has a first channel. A first gap space is formed between the electrode assembly and the side wall, and the first gap space communicates with the first channel. The first channel is used to guide gas discharged from the electrode assembly toward the bottom wall into the first gap space.

[0005] In the above technical solution, by placing the support between the bottom wall and the electrode assembly, the support has a first channel, and the electrode assembly and the side wall are spaced apart to form a first gap space. The first gap space is connected to the first channel. The first channel is used to guide the gas discharged from the electrode assembly toward the bottom wall to the first gap space, so that the gas can be discharged from the pressure relief mechanism through the first gap space, reducing the accumulation of gas between the electrode assembly and the bottom wall. This reduces the risk of the electrode assembly being lifted toward the top wall due to excessive gas pressure between the electrode assembly and the bottom wall, and reduces the risk of the electrode assembly coming into contact with the top wall or other parts on the top wall and causing a short circuit. It also reduces the risk of the gas between the electrode assembly and the bottom wall impacting the separator of the electrode assembly and causing the electrode assembly to come into contact with the bottom wall and short circuit, thus improving the safety performance of the secondary battery.

[0006] In some embodiments of this application, the first channel includes a conductive cavity formed inside the support, the conductive cavity including a first cavity wall, a second spacer space being formed between the first cavity wall and the electrode assembly, the second spacer space connecting the first spacer space and the first channel. The first channel also includes a plurality of first through holes disposed in the first cavity wall, at least one first through hole connecting the interior of the electrode assembly and the conductive cavity, and at least one first through hole connecting the conductive cavity and the second spacer space.

[0007] In the above technical solution, by including a conductive cavity formed inside the support in the first channel, the conductive cavity includes a first cavity wall, and a second space is formed between the first cavity wall and the electrode assembly. The second space connects the first space and the first channel, allowing gas discharged from the electrode assembly toward the bottom wall to flow through the first channel and the second space to the first space, reducing gas accumulation between the electrode assembly and the bottom wall. Furthermore, the gas discharged from the electrode assembly toward the bottom wall first enters the conductive cavity, mitigating the impact force of the gas discharged toward the bottom wall and further reducing the risk of the electrode assembly being lifted toward the top wall due to excessive gas pressure between the electrode assembly and the bottom wall. By also including multiple first through holes disposed in the first cavity wall, at least one first through hole connecting the interior of the electrode assembly and the conductive cavity, and at least one first through hole connecting the conductive cavity and the second space, gas discharged from the interior of the electrode assembly can directly enter the conductive cavity through the first through hole and flow to the second space. The gas flow speed is relatively fast, further reducing gas accumulation between the electrode assembly and the bottom wall.

[0008] In some embodiments of this application, a third space is formed between the support and the bottom wall, and the third space connects the first space and the first channel.

[0009] In the above technical solution, by forming a third space between the support and the bottom wall, and the third space connecting the first space and the first channel, the gas discharged from the electrode assembly toward the bottom wall can flow through the first channel and the third space to the second space, reducing the accumulation of gas between the electrode assembly and the bottom wall. Furthermore, the third space can store gas and act as a buffer, thereby further reducing the risk of the electrode assembly being lifted toward the top wall due to excessive gas pressure between the electrode assembly and the bottom wall.

[0010] In some embodiments of this application, the inner wall of the first through hole is provided with a hydrophilic coating, the thickness of which is t in μm, and the diameter of the first through hole is D0 in mm, satisfying 10≤t / D0≤200.

[0011] In the above technical solution, by providing a hydrophilic coating on the inner wall of the first through hole, the electrolyte can be accelerated to flow back to the interior of the electrode assembly through the first through hole, which helps to reduce the risk of lithium plating caused by local liquid shortage in the electrode assembly and improves the safety performance of the secondary battery.

[0012] When 10≤t / D0≤200, the hydrophilic coating can better adsorb electrolyte, improve the safety performance of the secondary battery, and reduce the influence of the hydrophilic coating on the gas discharge velocity from the first through hole and the local flow field shear force, thereby reducing gas accumulation between the electrode assembly and the bottom wall. The hydrophilic coating can destroy the adhesion of bubbles on the hole wall and promote the gas-liquid two-phase flow to pass through in an annular flow pattern. Thus, while ensuring the exhaust efficiency, the gas-liquid shear force is used to accelerate the electrolyte backflow along the hole wall.

[0013] In some embodiments of this application, the hydrophilic coating comprises at least one of hydrophilic polyurethane, modified cellulose, or hydrophilic acrylate polymer.

[0014] In the above technical solution, by making the hydrophilic coating include at least one of hydrophilic polyurethane, modified cellulose, or hydrophilic acrylate polymer, the hydrophilic coating can better adsorb electrolyte.

[0015] In some embodiments of this application, the outer surface of the hydrophilic coating away from the inner wall of the first through hole has a micro-rough structure, and the surface arithmetic mean roughness Ra of the micro-rough structure satisfies 0.8μm≤Ra≤6.3μm.

[0016] In the above technical solution, by giving the outer surface of the hydrophilic coating facing away from the inner wall of the first through hole a micro-rough structure, the electrolyte can rapidly penetrate into the valleys of the micro-rough structure under the combined action of surface tension and the hydrophilic coating, forming a continuous and stable thin liquid film. The micro-rough structure can effectively anchor the liquid film formed by the adsorption of the hydrophilic coating, preventing it from breaking under high-speed airflow, thereby providing a continuous and smooth gas-liquid sliding interface, significantly reducing the frictional resistance of gas exhaust and improving exhaust efficiency. It provides a low-friction sliding interface for the gas, allowing the gas to be quickly and with low resistance discharged from the first through hole, resulting in higher exhaust efficiency.

[0017] By ensuring that 0.8μm≤Ra≤6.3μm, the roughness of the micro-roughness structure is not too small, which reduces the problem of bubble nucleation and pinning on the surface of the hydrophilic coating due to an overly smooth surface, forming "dry spots" that hinder the spread of the liquid film. This makes the liquid film more continuous and stable, and less prone to breakage due to airflow shear. At the same time, the roughness of the micro-roughness structure is not too large, which reduces the peak-valley height difference on the surface of the hydrophilic coating, thereby reducing the problem of liquid accumulation in the valleys and incomplete liquid coverage in the convex valleys, making the liquid film more continuous and stable.

[0018] In some embodiments of this application, the first cavity wall includes a first portion, a second portion, and a third portion. Along a second direction, the second portion is located between the first and third portions and abuts against the electrode assembly. A first through-hole disposed on the second portion connects the interior of the electrode assembly and the conductive cavity. The first portion is spaced from the electrode assembly to form part of a second spacer space, and the third portion is spaced from the electrode assembly to form another part of the second spacer space. The first through-hole disposed on the first portion and / or the third portion connects the conductive cavity and the second spacer space. The second direction is perpendicular to the first direction.

[0019] In the above technical solution, since the middle part of the electrode assembly generally produces more gas and produces gas faster than other parts, by making the first cavity wall include a first part, a second part, and a third part, with the second part located between the first part and the third part along the second direction, and the second part abutting against the electrode assembly, and the first through hole provided on the second part connecting the interior of the electrode assembly and the conductive cavity, the first through hole on the second part can quickly guide the gas discharged from the middle part of the electrode assembly to the conductive cavity, further reducing the gas accumulation between the electrode assembly and the bottom wall.

[0020] By spacing the first part from the electrode assembly to form part of the second space, and the third part from the electrode assembly to form another part of the second space, a first through hole provided on the first part and / or the third part connects the conductive cavity and the second space, so that the gas in the conductive cavity can flow to the second space through the first through hole on the first part and / or the third part, thereby realizing the gas being discharged through the pressure relief mechanism.

[0021] In some embodiments of this application, along the second direction, the first cavity wall has opposing first and second edges, and the first cavity wall has a first region. Along the second direction, the first region has opposing first and second sides, with the first side closer to the first edge than the second side. The minimum distance between the first side and the first edge, and the minimum distance between the second side and the second edge, are both S1. The length of the first cavity wall is L1, satisfying 1 / 6 ≤ S1 / L1 ≤ 1 / 3. Along the third direction, the first cavity wall has opposing third and fourth edges, and along the third direction, the first region has opposing third and fourth sides, with the third side closer to the third edge than the fourth side. The minimum distance between the third side and the third edge, and the minimum distance between the fourth side and the fourth edge, are both S2. The width of the first cavity wall is W1, satisfying 1 / 6 ≤ S2 / W1 ≤ 1 / 3. The diameter of the first through hole in the first region is larger than the diameter of the first through holes in other regions of the first cavity wall. The first direction, the second direction, and the third direction are mutually perpendicular.

[0022] In the above technical solution, by limiting the first region to 1 / 6≤S1 / L1≤1 / 3 and 1 / 6≤S2 / W1≤1 / 3, the first region encompasses the middle of the first cavity wall without deviating too far from its geometric center. This allows for better coverage of the area corresponding to the middle of the electrode assembly within the first cavity wall, resulting in a more effective first through-hole in the first region. Furthermore, by making the diameter of the first through-hole in the first region larger than the diameter of first through-holes in other regions of the first cavity wall, the flow of gas discharged from the middle of the electrode assembly through the first through-hole to the conductive cavity is accelerated, further reducing gas accumulation between the electrode assembly and the bottom wall.

[0023] In some embodiments of this application, the first cavity wall has a second region. Along a second direction, the second region has a fifth side and a sixth side, with the fifth side being closer to the first edge than the sixth side. The minimum distance between the fifth side and the first edge, and the minimum distance between the sixth side and the second edge, are both S3. The length of the first cavity wall is L1, satisfying 0 < S3 / L1 ≤ 1 / 6. Along a third direction, the second region has a seventh side and an eighth side, with the seventh side being closer to the third edge than the eighth side. The minimum distance between the seventh side and the third edge, and the minimum distance between the eighth side and the fourth edge, are both S4. The width of the first cavity wall is W1, satisfying 0 < S4 / W1 ≤ 1 / 6. The first, second, third, and fourth sides are the inner sides of the second region, and the other regions of the first cavity wall besides the first and second regions are the third region. The diameter of the first through hole in the first region is larger than the diameter of the first through hole in the second region, and the diameter of the first through hole in the first region is larger than the diameter of the first through hole in the third region.

[0024] In the above technical solution, since the amount and velocity of gas generated generally decrease from the center to the edge of the electrode assembly, by limiting the second region to 0 < S3 / L1 ≤ 1 / 6 and 0 < S4 / W1 ≤ 1 / 6, the second region encompasses the area between the center and the edge of the first cavity wall. This effectively covers the area between the center and the edge of the electrode assembly, allowing the first through hole in the second region to perform better. By making the diameter of the first through hole in the first region larger than that in the second region, and the diameter of the first through hole in the first region larger than that in the third region, the diameter of the first through hole decreases from the center to the edge of the electrode assembly. Corresponding to the amount and velocity of gas generated by the electrode assembly, this results in a more uniform exhaust velocity of the electrode assembly, reducing problems such as gas accumulation and instability of the internal structure of the secondary battery caused by uneven local gas pressure.

[0025] In some embodiments of this application, the diameter of the first through hole in the first region is D1, and the diameter of the first through hole in the second region is D2, satisfying 50%≤D2 / D1≤60%.

[0026] In the above technical solution, when 50%≤D2 / D1≤60%, the gas can be discharged through the first through hole in the first region at a faster speed than through the first through hole in the second region, which is convenient for the first through hole in the first region to receive a large amount of gas discharged from the middle of the electrode assembly. At the same time, the gas can be discharged through the first through hole in the first region at a slower speed than through the first through hole in the second region, which makes the exhaust speed of the electrode assembly more uniform.

[0027] In some embodiments of this application, the diameter of the first through hole disposed in the third region is D3, which satisfies 30%≤D3 / D2≤50%.

[0028] In the above technical solution, when 30%≤D3 / D2≤50%, the gas can be discharged faster through the first through hole in the second region than through the first through hole in the third region, which is convenient for the first through hole in the second region to receive the gas discharged between the middle and the edge of the electrode assembly. At the same time, the gas can be discharged faster through the first through hole in the second region than through the first through hole in the third region, which makes the exhaust speed of the electrode assembly more uniform.

[0029] In some embodiments of this application, a plurality of first through holes are provided in the first region, and the distance between two adjacent first through holes is D4, satisfying 0.8*(D2+D3)≤D4≤1.2*(D2+D3).

[0030] In the above technical solution, when 0.8*(D2+D3)≤D4≤1.2*(D2+D3), the distance between two adjacent first through holes is not too small, which reduces the risk of airflow convergence and collision between two adjacent first through holes and makes the exhaust efficiency higher. At the same time, the distance between two adjacent first through holes is not too large, and the number of first through holes can be set to be more, which can improve the exhaust efficiency of the first through holes.

[0031] In some embodiments of this application, the electrode assembly is covered with a protective film, and a second through hole is provided on the protective film located between the electrode assembly and the bottom wall. When viewed along the first direction, the second through hole does not overlap with the first through hole.

[0032] In the above technical solution, by providing a second through-hole on the protective film located between the electrode assembly and the bottom wall, the gas discharged from the electrode assembly can be discharged through the second through-hole, reducing the impact of the protective film on the venting of the electrode assembly. By ensuring that the second through-hole does not overlap with the first through-hole when viewed along the first direction, the risk of particles generated by the electrode assembly falling directly to the bottom wall through the first and second through-holes and causing a micro-short circuit inside the secondary battery can be reduced.

[0033] In some embodiments of this application, the diameter of the first through hole is D0 and the diameter of the second through hole is D5, satisfying 60%≤D0 / D5≤150%.

[0034] In the above technical solution, when 60%≤D0 / D5≤150%, the diameter of the first through hole is not too small, and the efficiency of gas discharge through the first through hole is higher. At the same time, the diameter of the first through hole is not too large, and the structure of the support is more stable.

[0035] In some embodiments of this application, along the first direction, the height of the electrode assembly is H1, and the height of the conductive cavity is H2, satisfying 0.8%≤H2 / H1≤3.5%.

[0036] In the above technical solution, when 0.8%≤H2 / H1≤3.5%, the height of the conductive cavity is not too small, allowing the conductive cavity to accommodate more gas and further reducing the risk of the electrode assembly being lifted to the top wall due to excessive gas pressure between the electrode assembly and the bottom wall. At the same time, the height of the conductive cavity is not too large, resulting in a smaller space occupied by the support, which is beneficial to improving the energy density of the secondary battery.

[0037] In some embodiments of this application, the cavity wall of the conductive cavity includes a second cavity wall, and a third spacer is formed between the second cavity wall and the bottom wall. The first channel also includes a plurality of third through holes disposed in the second cavity wall, the third through holes connecting the conductive cavity and the third spacer. Viewed along the first direction, the first through holes and the third through holes do not overlap.

[0038] In the above technical solution, by making the cavity wall of the conductive cavity include a second cavity wall, and forming a third space between the second cavity wall and the bottom wall, the first channel also includes a plurality of third through holes disposed on the second cavity wall. The third through holes connect the conductive cavity and the third space, so that the gas in the conductive cavity can flow directly through the third through holes to the third space and further flow to the second space. The gas flow speed is relatively fast, which further reduces the gas accumulation between the electrode assembly and the bottom wall.

[0039] By ensuring that the first through hole and the third through hole do not overlap when viewed along the first direction, the risk of particles generated by the electrode assembly falling directly onto the bottom wall through the first and third through holes and causing a micro short circuit inside the secondary battery can be reduced.

[0040] In some embodiments of this application, the first cavity wall and / or the second cavity wall are arranged in an arc shape.

[0041] In the above technical solution, by making the first cavity wall and / or the second cavity wall arc-shaped, it is possible to facilitate the formation of the second interval space and / or the third interval space, and to reduce the risk of damage to the electrode assembly when the support and the electrode assembly interfere with each other, thereby improving the safety performance of the secondary battery.

[0042] In some embodiments of this application, a third space is formed between the support and the bottom wall. The first channel includes a plurality of first through holes disposed on the support. At least one first through hole connects the interior of the electrode assembly and the third space, and at least one first through hole connects the third space and the first space.

[0043] In the above technical solution, by forming a third space between the support and the bottom wall, the first channel includes a plurality of first through holes disposed on the support, at least one first through hole connects the interior of the electrode assembly and the third space, and at least one first through hole connects the third space and the first space, so that the gas generated by the electrode assembly can flow directly through the first through hole to the third space and further flow to the first space, the gas flow speed is relatively fast, and the gas accumulation between the electrode assembly and the bottom wall is further reduced.

[0044] In some embodiments of this application, a second space is formed between the support and the electrode assembly, and the first channel includes a third through hole disposed in the support, the third through hole connecting the second space and the first space.

[0045] In the above technical solution, by forming a second space between the support and the electrode assembly, the first channel includes a third through hole disposed on the support. The third through hole connects the second space and the first space, so that the gas generated by the electrode assembly can directly enter the second space and flow to the first space through the third through hole. The gas flow speed is relatively fast, which further reduces the gas accumulation between the electrode assembly and the bottom wall.

[0046] In some embodiments of this application, along the second direction, the length of the outer shell is L2, the length of the bracket is L3, and the distance between the electrode assembly and the sidewall is L4, satisfying L2-2*L4≤L3≤L2; and / or, along the third direction, the width of the outer shell is W2, the width of the bracket is W3, and the distance between the electrode assembly and the sidewall is W4, satisfying W2-2*W4≤W3≤W2.

[0047] In the above technical solution, when L2-2*L4≤L3≤L2 and / or W2-2*W4≤W3≤W2, the electrode assembly can be fully supported on the bracket, reducing the risk of damage to the electrode assembly due to uneven force, and the bracket can be easily installed inside the housing.

[0048] In some embodiments of this application, the support is an elastic element with an elastic rebound rate of 0.05-0.35.

[0049] In the above technical solution, by making the bracket an elastic element, it is easy to install the bracket and electrode assembly inside the housing, and the bracket can provide elastic support to the electrode assembly, so that when the secondary battery is subjected to external force, it can provide buffer to the electrode assembly, reduce the risk of damage to the electrode assembly, and improve the safety of the secondary battery.

[0050] When the elastic rebound rate of the stent is 0.05-0.35, it can ensure that the elastic rebound rate of the stent is not too small, further improving the elastic support force of the stent on the electrode assembly and reducing the risk of damage to the electrode assembly when the secondary battery is subjected to external forces. At the same time, it can ensure that the elastic rebound rate of the stent is not too large, so that the pressure of the stent on the electrode assembly is not too large, reducing the influence of the stent on the internal resistance of the electrode assembly.

[0051] Secondly, this application provides electrical equipment, including the secondary battery as described above. Attached Figure Description

[0052] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings.

[0053] Figure 1 A cross-sectional view of the electrode assembly of a secondary battery provided in some embodiments of this application; Figure 2 This is a schematic diagram of the structure of the secondary battery holder provided in some embodiments of this application; Figure 3 A schematic diagram of the structure of a secondary battery holder provided in some embodiments of this application from another perspective; Figure 4 This is a schematic diagram of a partial structure of a secondary battery provided in some embodiments of this application; Figure 5 This is a schematic diagram of the structure of a secondary battery provided in some other embodiments of this application; Figure 6 Schematic diagrams of the structure of the secondary battery holder provided in other embodiments of this application; Figure 7 This is a schematic diagram of the structure of a secondary battery provided in some other embodiments of this application; Figure 8 This is a schematic diagram of the structure of a secondary battery provided in some other embodiments of this application.

[0054] Icons: 10-Secondary battery; 100-Outer casing; 101-First space; 102-Second space; 103-Third space; 110-Top wall; 111-Pressure relief mechanism; 112-Positive electrode post; 113-Negative electrode post; 120-Bottom wall; 130-Side wall; 200-Electrode assembly; 210-Protective film; 211-Second through hole; 300-Support; 301-First channel; 3011-Conductive cavity; 3012-First through hole; 3013-Third through hole; 310-First cavity wall; 310a-First edge; 310b-Second... Second edge; 310c - Third edge; 310d - Fourth edge; 311 - First part; 312 - Second part; 313 - Third part; 314 - First region; 314a - First side; 314b - Second side; 314c - Third side; 314d - Fourth side; 315 - Second region; 315a - Fifth side; 315b - Sixth side; 315c - Seventh side; 315d - Eighth side; 316 - Third region; 320 - Second cavity wall; 330 - Connecting post; X - First direction; Y - Second direction; Z - Third direction. Detailed Implementation

[0055] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0056] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the specification of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having" and any variations thereof in the specification, claims and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0057] The terms "first," "second," etc., in the specification, claims, or the accompanying drawings of this application are used to distinguish different objects, rather than to describe a specific order or primary / secondary relationship.

[0058] 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.

[0059] 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. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0060] With the development of the new energy industry, batteries are gradually moving towards higher energy density and higher power density, which also places higher demands on battery safety. Currently, large-capacity batteries are often used to improve energy density. However, large-capacity batteries are more prone to thermal runaway, and triggering thermal runaway generates a large amount of gas. For batteries with a pressure relief mechanism on the top wall of the casing, the gas between the electrode assembly and the top wall of the casing can be discharged through the pressure relief mechanism. However, the gas between the electrode assembly and the bottom wall of the casing is difficult to discharge and will accumulate, resulting in excessive gas pressure between the electrode assembly and the bottom wall of the casing. This causes the electrode assembly to rise towards the top wall, and the electrode assembly to come into contact with the top wall or other components such as terminals mounted on the top wall, leading to a short circuit (if there is plastic between the electrode assembly and the top wall, the plastic will melt at high temperatures). Furthermore, the gas discharged from the electrode assembly towards the bottom wall can impact the separator of the electrode assembly, causing the electrode assembly to come into direct contact with the bottom wall, which can also easily cause a short circuit, all of which affect the safety performance of the battery.

[0061] To improve battery safety, this application provides a secondary battery, which includes a casing, an electrode assembly, and a support. The casing includes a top wall, a bottom wall, and a side wall. The top wall and bottom wall are disposed opposite each other along a first direction, and the side wall connects the top wall and bottom wall. The top wall is provided with a pressure relief mechanism. The electrode assembly is disposed within the casing. The support is disposed between the bottom wall and the electrode assembly, and the support has a first channel. A first gap space is formed between the electrode assembly and the side wall, and the first gap space communicates with the first channel. The first channel is used to guide gas discharged from the electrode assembly toward the bottom wall into the first gap space.

[0062] In this type of secondary battery, a support is disposed between the bottom wall and the electrode assembly. The support has a first channel, and a first gap space is formed between the electrode assembly and the side wall. The first gap space communicates with the first channel. The first channel is used to guide the gas discharged from the electrode assembly toward the bottom wall to the first gap space, so that the gas can be discharged from the pressure relief mechanism through the first gap space. This reduces the accumulation of gas between the electrode assembly and the bottom wall, thereby reducing the risk of the electrode assembly being lifted toward the top wall due to excessive gas pressure between the electrode assembly and the bottom wall, and reducing the risk of short circuit caused by the electrode assembly contacting the top wall or other components on the top wall. Furthermore, it also reduces the risk of short circuit caused by gas impacting the separator of the electrode assembly between the electrode assembly and the bottom wall, thus improving the safety performance of the secondary battery.

[0063] The secondary battery provided in this application embodiment can be a lithium-ion battery, a sodium-ion battery, or a magnesium-ion battery, etc., and this application embodiment is not limited to this. The secondary battery can be cylindrical, flat, cuboid, or other shapes, etc., and this application embodiment is not limited to this either.

[0064] This application provides an electrical device that uses a secondary battery as a power source. The electrical device can be, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, drones, ships, spacecraft, etc.

[0065] See Figure 1 , Figure 1 This is a cross-sectional view of the electrode assembly of a secondary battery provided in some embodiments of this application.

[0066] This application provides a secondary battery 10, which includes a casing 100, an electrode assembly 200, and an electrolyte. The electrode assembly 200 and the electrolyte are housed within the casing 100. The electrode assembly 200 includes a positive electrode, a separator, and a negative electrode, with the separator disposed between the positive and negative electrodes. The battery primarily operates by the movement of metal ions between the positive and negative electrodes. The positive electrode includes a positive current collector and a positive active material layer. The positive active material layer is coated on the surface of the positive current collector, and the portion of the positive current collector not coated with the positive active material layer serves as a positive electrode tab, through which electrical energy is input or output. Taking a lithium-ion battery as an example, the material of the positive current collector can be aluminum, and the positive active material can be lithium cobalt oxide, lithium iron phosphate, ternary materials (such as lithium nickel cobalt manganese oxide), lithium manganese oxide, or sodium, etc. The negative electrode includes a negative current collector and a negative active material layer. The negative active material layer is coated on the surface of the negative current collector, and the portion of the negative current collector without the negative active material layer serves as the negative electrode tab, through which electrical energy is input or output. The negative current collector can be made of copper, and the negative active material can be made of carbon-containing materials, silicon-containing materials, or other materials. The separator can be made of polypropylene (PP) or polyethylene (PE), etc. The electrolyte can include organic solvents, lithium salts, etc.

[0067] The outer casing 100 can be made of a high-strength hard material, such as metal materials like steel or aluminum alloy; or non-metallic materials such as carbon fiber or hard plastic, which gives the outer casing 100 high stress performance and makes it less likely to deform or break due to stress or environmental changes, thereby making the secondary battery 10 more reliable.

[0068] In some embodiments, the secondary battery 10 includes a support 300, and the housing 100 includes a top wall 110, a bottom wall 120, and a side wall 130. The top wall 110 and the bottom wall 120 are disposed opposite each other along a first direction X, and the side wall 130 connects the top wall 110 and the bottom wall 120. The top wall 110 is provided with a pressure relief mechanism 111. The support 300 is disposed between the bottom wall 120 and the electrode assembly 200. The support 300 has a first channel 301. The electrode assembly 200 and the side wall 130 are spaced apart to form a first gap space 101. The first gap space 101 communicates with the first channel 301. The first channel 301 is used to guide the gas discharged from the electrode assembly 200 toward the bottom wall 120 to the first gap space 101.

[0069] By positioning the support 300 between the bottom wall 120 and the electrode assembly 200, the support 300 has a first channel 301. A first space 101 is formed between the electrode assembly 200 and the side wall 130, communicating with the first channel 301. The first channel 301 guides gas discharged from the electrode assembly 200 toward the bottom wall 120 into the first space 101, allowing the gas to be discharged through the first space 101 from the pressure relief mechanism 111, thus reducing the pressure on the electrode assembly 200. The accumulation of gas between the electrode assembly 200 and the bottom wall 120 reduces the risk of the electrode assembly 200 rising towards the top wall 110 due to excessive gas pressure between the electrode assembly 200 and the bottom wall 120, and reduces the risk of short circuit caused by the electrode assembly 200 contacting the top wall 110 or other components on the top wall 110; it also reduces the risk of short circuit caused by gas impacting the separator of the electrode assembly 200 between the electrode assembly 200 and the bottom wall 120, thereby improving the safety performance of the secondary battery 10.

[0070] In some embodiments, the pressure relief mechanism 111 can be fixedly connected to the top wall 110 by welding, bonding or other means, and the pressure relief mechanism 111 and the top wall 110 can also be integrally formed.

[0071] In some embodiments, the support 300 may be made of insulating material or metal material, and an insulating layer is provided on its surface to achieve insulation between the electrode assembly 200 and the bottom wall 120.

[0072] See Figure 1 and Figure 2 , Figure 2 This is a schematic diagram of the structure of a secondary battery holder provided in some embodiments of this application.

[0073] In some embodiments, the first channel 301 includes a conductive cavity 3011 formed inside the support 300. The conductive cavity 3011 includes a first cavity wall 310, and a second space 102 is formed between the first cavity wall 310 and the electrode assembly 200. The second space 102 connects the first space 101 and the first channel 301. The first channel 301 also includes a plurality of first through holes 3012 disposed in the first cavity wall 310. At least one first through hole 3012 connects the interior of the electrode assembly 200 and the conductive cavity 3011, and at least one first through hole 3012 connects the conductive cavity 3011 and the second space 102.

[0074] By including a conductive cavity 3011 formed inside the support 300 in the first channel 301, the conductive cavity 3011 includes a first cavity wall 310, and a second space 102 is formed between the first cavity wall 310 and the electrode assembly 200. The second space 102 connects the first space 101 and the first channel 301, so that the gas discharged by the electrode assembly 200 toward the bottom wall 120 can flow through the first channel 301 and the second space 102 to the first space 101, reducing the gas accumulation between the electrode assembly 200 and the bottom wall 120. Furthermore, the gas discharged by the electrode assembly 200 toward the bottom wall 120 first enters the conductive cavity 3011, which can alleviate the impact force of the gas discharged toward the bottom wall 120, further reducing the risk of the electrode assembly 200 being lifted toward the top wall 110 due to excessive air pressure between the electrode assembly 200 and the bottom wall 120. By including a plurality of first through holes 3012 disposed on the first cavity wall 310 in the first channel 301, at least one first through hole 3012 connects the interior of the electrode assembly 200 and the conductive cavity 3011, and at least one first through hole 3012 connects the conductive cavity 3011 and the second spacer space 102, the gas discharged from the interior of the electrode assembly 200 can directly enter the conductive cavity 3011 through the first through hole 3012 and flow to the second spacer space 102 through the first through hole 3012. The gas flow speed is relatively fast, which further reduces the gas accumulation between the electrode assembly 200 and the bottom wall 120.

[0075] In some embodiments, the inner wall of the first through hole 3012 is provided with a hydrophilic coating.

[0076] By providing a hydrophilic coating on the inner wall of the first through hole 3012, the electrolyte can be accelerated to flow back to the interior of the electrode assembly 200 through the first through hole 3012, which helps to reduce the risk of lithium plating caused by local liquid shortage in the electrode assembly 200 and improves the safety performance of the secondary battery 10.

[0077] In some embodiments, the thickness of the hydrophilic coating is t, in μm, and the diameter of the first through-hole 3012 is D0, in mm, satisfying 10 ≤ t / D0 ≤ 200. For example, t / D0 can be 10, 20, 50, 80, 100, 120, 150, 180, or 200, or a range of any two of these values, wherein the ratio of t / D0 is a dimensionless parameter directly calculated based on the units mentioned above.

[0078] When 10≤t / D0≤200, the hydrophilic coating can better adsorb electrolyte, improve the safety performance of the secondary battery 10, and reduce the influence of the hydrophilic coating on the gas discharge velocity from the first through hole 3012 and the local flow field shear force, thereby reducing gas accumulation between the electrode assembly 200 and the bottom wall 120. The hydrophilic coating can destroy the adhesion of bubbles on the hole wall and promote the gas-liquid two-phase flow to pass through in an annular flow form, thereby ensuring exhaust efficiency while using gas-liquid shear force to accelerate the electrolyte backflow along the hole wall.

[0079] In some embodiments, the hydrophilic coating comprises at least one of a hydrophilic polyurethane, a modified cellulose, or a hydrophilic acrylate polymer.

[0080] By including at least one of hydrophilic polyurethane, modified cellulose, or hydrophilic acrylate polymer in the hydrophilic coating, the hydrophilic coating can be made to adsorb electrolyte better.

[0081] In some embodiments, the outer surface of the hydrophilic coating away from the inner wall of the first through hole 3012 has a micro-rough structure.

[0082] By creating a micro-rough structure on the outer surface of the hydrophilic coating facing away from the inner wall of the first through-hole 3012, the electrolyte can rapidly penetrate into the valleys of the micro-rough structure under the combined action of surface tension and the hydrophilic coating, forming a continuous and stable thin liquid film. The micro-rough structure effectively anchors the liquid film formed by the hydrophilic coating, preventing it from breaking under high-speed airflow, thus providing a continuous and smooth gas-liquid sliding interface. This significantly reduces the frictional resistance of gas exhaust and improves exhaust efficiency. It provides a low-friction sliding interface for the gas, allowing it to be quickly and with low resistance exited from the first through-hole 3012, resulting in higher exhaust efficiency.

[0083] In some embodiments, the surface arithmetic mean roughness Ra of the micro-roughened structure satisfies 0.8 μm ≤ Ra ≤ 6.3 μm. For example, Ra can be 0.8 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, or 6.3 μm, or a range consisting of any two of these values.

[0084] By ensuring that 0.8μm≤Ra≤6.3μm, the roughness of the micro-roughness structure is not too small, which reduces the problem of bubble nucleation and pinning on the surface of the hydrophilic coating due to an overly smooth surface, forming "dry spots" that hinder the spread of the liquid film. This makes the liquid film more continuous and stable, and less prone to breakage due to airflow shear. At the same time, the roughness of the micro-roughness structure is not too large, which reduces the peak-valley height difference on the surface of the hydrophilic coating, thereby reducing the problem of liquid accumulation in the valleys and incomplete liquid coverage in the convex valleys, making the liquid film more continuous and stable.

[0085] In some embodiments, the method for measuring the surface arithmetic mean roughness Ra of the micro-rough structure includes: disassembling the secondary battery, directly using a laser confocal microscope or white light interferometer to perform a non-contact surface scan on the hydrophilic coating surface of the inner wall of the first through hole, and the instrument software automatically calculating the Ra value.

[0086] See Figure 1 In some embodiments, the first cavity wall 310 includes a first portion 311, a second portion 312, and a third portion 313. Along the second direction Y, the second portion 312 is located between the first portion 311 and the third portion 313, and abuts against the electrode assembly 200. A first through hole 3012 disposed on the second portion 312 connects the interior of the electrode assembly 200 and the conductive cavity 3011. The first portion 311 is spaced from the electrode assembly 200 to form a part of the second spacer space 102, and the third portion 313 is spaced from the electrode assembly 200 to form another part of the second spacer space 102. The first through hole 3012 disposed on the first portion 311 and / or the third portion 313 connects the conductive cavity 3011 and the second spacer space 102. The second direction Y is perpendicular to the first direction X.

[0087] Since the middle part of the electrode assembly 200 generally produces more gas and produces gas at a faster rate than other parts, by making the first cavity wall 310 include a first part 311, a second part 312, and a third part 313, along the second direction Y, the second part 312 is located between the first part 311 and the third part 313, and the second part 312 abuts against the electrode assembly 200. The first through hole 3012 provided on the second part 312 connects the interior of the electrode assembly 200 and the conductive cavity 3011, so that the first through hole 3012 on the second part 312 can quickly guide the gas discharged from the middle part of the electrode assembly 200 to the conductive cavity 3011, further reducing the gas accumulation between the electrode assembly 200 and the bottom wall 120. By spacing the first portion 311 from the electrode assembly 200 to form a part of the second space 102, and the third portion 313 from the electrode assembly 200 to form another part of the second space 102, a first through hole 3012 provided on the first portion 311 and / or the third portion 313 connects the conductive cavity 3011 and the second space 102, so that the gas in the conductive cavity 3011 can flow to the second space 102 through the first through hole 3012 on the first portion 311 and / or the third portion 313, thereby realizing the gas being discharged through the pressure relief mechanism 111.

[0088] See Figure 2 and Figure 3 , Figure 3 This is a structural schematic diagram of a secondary battery holder provided in some embodiments of this application from another perspective.

[0089] In some embodiments, along the second direction Y, the first cavity wall 310 has a first edge 310a and a second edge 310b, and the first cavity wall 310 has a first region 314. Along the second direction Y, the first region 314 has a first side 314a and a second side 314b, the first side 314a being closer to the first edge 310a than the second side 314b. The minimum distance between the first side 314a and the first edge 310a and the minimum distance between the second side 314b and the second edge 310b are both S1. The length of the first cavity wall 310 is L1, which satisfies 1 / 6≤S1 / L1≤1 / 3. Along the third direction Z, the first cavity wall 310 has opposing third edges 310c and fourth edges 310d. Along the third direction Z, the first region 314 has opposing third sides 314c and fourth sides 314d. The third side 314c is closer to the third edge 310c than the fourth side 314d. The minimum distance between the third side 314c and the third edge 310c, and the minimum distance between the fourth side 314d and the fourth edge 310d, are both S2. The width of the first cavity wall 310 is W1, satisfying 1 / 6 ≤ S2 / W1 ≤ 1 / 3. The diameter of the first through hole 3012 disposed in the first region 314 is larger than the diameter of the first through hole 3012 disposed in other regions of the first cavity wall 310. The first direction X and the second direction Y are perpendicular to the third direction Z. For example, S1 / L1 can be 1 / 6, 3 / 16, 5 / 24, 11 / 48, 1 / 4, 13 / 48, 7 / 24, 15 / 48, or 1 / 3, or a range consisting of any two of these values. Similarly, S2 / W1 can be 1 / 6, 3 / 16, 5 / 24, 11 / 48, 1 / 4, 13 / 48, 7 / 24, 15 / 48, or 1 / 3, or a range consisting of any two of these values.

[0090] By defining the first region 314 as 1 / 6≤S1 / L1≤1 / 3 and 1 / 6≤S2 / W1≤1 / 3, the first region 314 encompasses the middle of the first cavity wall 310 without deviating too far from its geometric center. This allows for better coverage of the area corresponding to the middle of the electrode assembly 200 within the first cavity wall 310, thus enhancing the effectiveness of the first through hole 3012 located in the first region 314. Furthermore, by making the diameter of the first through hole 3012 in the first region 314 larger than the diameter of first through holes 3012 in other areas of the first cavity wall 310, the flow of gas discharged from the middle of the electrode assembly 200 through the first through hole 3012 to the conductive cavity 3011 is accelerated, further reducing gas accumulation between the electrode assembly 200 and the bottom wall 120.

[0091] In some embodiments, the first cavity wall 310 has a second region 315 along the second direction Y. The second region 315 has a fifth side 315a and a sixth side 315b. The fifth side 315a is closer to the first edge 310a than the sixth side 315b. The minimum distance between the fifth side 315a and the first edge 310a and the minimum distance between the sixth side 315b and the second edge 310b are both S3. The length of the first cavity wall 310 is L1, which satisfies 0 < S3 / L1 ≤ 1 / 6. Along the third direction Z, the second region 315 has a seventh side 315c and an eighth side 315d. The seventh side 315c is closer to the third edge 310c than the eighth side 315d. The minimum distance between the seventh side 315c and the third edge 310c, and the minimum distance between the eighth side 315d and the fourth edge 310d, are both S4. The width of the first cavity wall 310 is W1, satisfying 0 < S4 / W1 ≤ 1 / 6. The first side 314a, the second side 314b, the third side 314c, and the fourth side 314d are the inner sides of the second region 315. The other regions of the first cavity wall 310 besides the first region 314 and the second region 315 constitute the third region 316. The diameter of the first through hole 3012 in the first region 314 is larger than the diameter of the first through hole 3012 in the second region 315, and the diameter of the first through hole 3012 in the first region 314 is larger than the diameter of the first through hole 3012 in the third region 316. For example, S3 / L1 can be 1 / 48, 1 / 24, 1 / 16, 1 / 12, 5 / 48, 1 / 8, 7 / 48, or 1 / 6, or a range consisting of any two of these values. For example, S4 / W1 can be 1 / 48, 1 / 24, 1 / 16, 1 / 12, 5 / 48, 1 / 8, 7 / 48, or 1 / 6, or a range consisting of any two of these values.

[0092] Since the amount and speed of gas generated generally decrease from the center to the edge of the electrode assembly 200, by defining the second region 315 as 0 < S3 / L1 ≤ 1 / 6 and 0 < S4 / W1 ≤ 1 / 6, the second region 315 encompasses the area between the center and the edge of the first cavity wall 310, which can better cover the area between the center and the edge of the electrode assembly 200 corresponding to the first cavity wall 310, so that the first through hole 3012 provided in the second region 315 can play a better role. By making the diameter of the first through hole 3012 in the first region 314 larger than the diameter of the first through hole 3012 in the second region 315, and the diameter of the first through hole 3012 in the first region 314 larger than the diameter of the first through hole 3012 in the third region 316, the diameter of the first through hole 3012 can decrease from the center to the edge of the electrode assembly 200. Corresponding to the amount and speed of gas production by the electrode assembly 200, the exhaust speed of the electrode assembly 200 can be made more uniform, reducing problems such as gas accumulation and instability of the internal structure of the secondary battery 10 caused by uneven local gas pressure.

[0093] In some embodiments, the diameter of the first through hole 3012 disposed in the first region 314 is D1, and the diameter of the first through hole 3012 disposed in the second region 315 is D2, satisfying 50%≤D2 / D1≤60%. For example, D2 / D1 can be 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, or 60%, or a range consisting of any two of these values.

[0094] When 50%≤D2 / D1≤60%, the gas can be discharged through the first through hole 3012 of the first region 314 at a faster rate than the gas can be discharged through the first through hole 3012 of the second region 315, which facilitates the first through hole 3012 of the first region 314 to receive a large amount of gas discharged from the middle of the electrode assembly 200. At the same time, the gas can be discharged through the first through hole 3012 of the first region 314 at a slower rate than the gas can be discharged through the first through hole 3012 of the second region 315, which makes the exhaust speed of the electrode assembly 200 more uniform.

[0095] In some embodiments, the diameter of the first through hole 3012 disposed in the third region 316 is D3, satisfying 30%≤D3 / D2≤50%. For example, D3 / D2 can be 30%, 32%, 35%, 37%, 40%, 42%, 45%, 47% or 50%, or a range consisting of any two of these values.

[0096] When 30%≤D3 / D2≤50%, the gas can be discharged through the first through hole 3012 of the second region 315 at a faster rate than the gas can be discharged through the first through hole 3012 of the third region 316, which facilitates the first through hole 3012 of the second region 315 to receive the gas discharged between the middle and the edge of the electrode assembly 200. At the same time, the gas can be discharged through the first through hole 3012 of the second region 315 at a slower rate than the gas can be discharged through the first through hole 3012 of the third region 316, which makes the exhaust speed of the electrode assembly 200 more uniform.

[0097] In some embodiments, the first region 314 is provided with a plurality of first through holes 3012, and the spacing between two adjacent first through holes 3012 is D4, satisfying 0.8*(D2+D3)≤D4≤1.2*(D2+D3). For example, D4 / (D2+D3) can be 0.8, 0.85, 0.9, 0.95, 1, 1.05, 1.1, 1.15 or 1.2, or a range of any two of these values.

[0098] When 0.8*(D2+D3)≤D4≤1.2*(D2+D3), the spacing between two adjacent first through holes 3012 is not too small, which reduces the risk of airflow convergence and collision between the two adjacent first through holes 3012, resulting in higher exhaust efficiency. At the same time, the spacing between two adjacent first through holes 3012 is not too large, allowing for a greater number of first through holes 3012, which can improve the exhaust efficiency of the first through holes 3012.

[0099] Wherein, D4 is the minimum distance between the edges of two adjacent first through holes 3012.

[0100] See Figure 4 , Figure 4 This is a schematic diagram of a partial structure of a secondary battery provided in some embodiments of this application.

[0101] In some embodiments, the electrode assembly 200 is covered with a protective film 210, and a second through hole 211 is provided on the protective film 210 located between the electrode assembly 200 and the bottom wall 120. When viewed along the first direction X, the second through hole 211 does not overlap with the first through hole 3012.

[0102] By providing a second through-hole 211 on the protective film 210 located between the electrode assembly 200 and the bottom wall 120, the gas discharged from the electrode assembly 200 can be discharged through the second through-hole 211, reducing the influence of the protective film 210 on the venting of the electrode assembly 200. By ensuring that the second through-hole 211 does not overlap with the first through-hole 3012 when viewed along the first direction X, the risk of particles generated by the electrode assembly 200 falling directly onto the bottom wall 120 through the first through-hole 3012 and the second through-hole 211, causing a micro-short circuit inside the secondary battery 10, can be reduced.

[0103] In some embodiments, the protective film 210 is a Mylar film, including at least one of polypropylene, polyester, polyimide, and low-sulfur polypropylene.

[0104] In some embodiments, the diameter of the first through hole 3012 is D0, and the diameter of the second through hole 211 is D5, satisfying 60%≤D0 / D5≤150%. For example, D0 / D5 can be 60%, 70%, 80%, 90%, 100%, 110%, 120%, 130%, 140%, or 150%, or a range consisting of any two of these values.

[0105] When 60%≤D0 / D5≤150%, the diameter of the first through hole 3012 is not too small, so that the gas can be discharged more efficiently through the first through hole 3012. At the same time, the diameter of the first through hole 3012 is not too large, so that the structure of the support 300 is more stable.

[0106] See Figure 1 In some embodiments, along the first direction X, the height of the electrode assembly 200 is H1, and the height of the conductive cavity 3011 is H2, satisfying 0.8% ≤ H2 / H1 ≤ 3.5%. For example, H2 / H1 can be 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.3%, 2.5%, 2.7%, 3%, 3.2%, or 3.5%, or a range consisting of any two of these values.

[0107] When 0.8%≤H2 / H1≤3.5%, the height of the conductive cavity 3011 is not too small, allowing it to hold more gas and further reducing the risk of the electrode assembly 200 rising to the top wall 110 due to excessive gas pressure between the electrode assembly 200 and the bottom wall 120. At the same time, the height of the conductive cavity 3011 is not too large, resulting in a smaller space occupied by the support 300, which is beneficial to improving the energy density of the secondary battery 10.

[0108] H2 is the maximum height of the conduction cavity 3011.

[0109] In some embodiments, a third space 103 is formed between the support 300 and the bottom wall 120, and the third space 103 connects the first space 101 and the first channel 301.

[0110] By forming a third space 103 between the support 300 and the bottom wall 120, and connecting the first space 101 and the first channel 301, the gas discharged from the electrode assembly 200 toward the bottom wall 120 can flow through the first channel 301 and the third space 103 to the second space 102, reducing gas accumulation between the electrode assembly 200 and the bottom wall 120. Furthermore, the third space 103 can store gas and act as a buffer, thereby further reducing the risk of the electrode assembly 200 rising toward the top wall 110 due to excessive gas pressure between the electrode assembly 200 and the bottom wall 120.

[0111] See Figure 1 and Figure 2 In some embodiments, the cavity wall of the conductive cavity 3011 includes a second cavity wall 320, and a third space 103 is formed between the second cavity wall 320 and the bottom wall 120. The first channel 301 also includes a plurality of third through holes 3013 disposed in the second cavity wall 320, and the third through holes 3013 connect the conductive cavity 3011 and the third space 103.

[0112] By making the cavity wall of the conductive cavity 3011 include a second cavity wall 320, and forming a third space 103 between the second cavity wall 320 and the bottom wall 120, the first channel 301 also includes a plurality of third through holes 3013 disposed in the second cavity wall 320. The third through holes 3013 connect the conductive cavity 3011 and the third space 103, so that the gas in the conductive cavity 3011 can flow directly through the third through holes 3013 to the third space 103, and further flow to the second space 102. The gas flow speed is relatively fast, which further reduces the gas accumulation between the electrode assembly 200 and the bottom wall 120.

[0113] In some embodiments, when viewed along the first direction X, the first through hole 3012 and the third through hole 3013 do not overlap.

[0114] By ensuring that the first through hole 3012 and the third through hole 3013 do not overlap when viewed along the first direction X, the risk of particles generated by the electrode assembly 200 falling directly onto the bottom wall 120 through the first through hole 3012 and the third through hole 3013, causing a micro short circuit inside the secondary battery 10, can be reduced.

[0115] In some embodiments, the first cavity wall 310 and / or the second cavity wall 320 are arranged in an arc shape.

[0116] By making the first cavity wall 310 and / or the second cavity wall 320 arc-shaped, it is easier to form the second space 102 and / or the third space 103, and the risk of damaging the electrode assembly 200 when the support 300 interferes with the electrode assembly 200 can be reduced, thereby improving the safety performance of the secondary battery 10.

[0117] See Figure 5 , Figure 5 This is a schematic diagram of the structure of a secondary battery provided in some other embodiments of this application.

[0118] In other embodiments, the first cavity wall 310 and / or the second cavity wall 320 may also be stepped.

[0119] In some embodiments, the first cavity wall 310 and the second cavity wall 320 are connected at opposite ends along the second direction Y, and the conductive cavity 3011 communicates with the first spacer space 101 through the first through hole 3012 and / or the third through hole 3013.

[0120] See Figure 6 , Figure 6 This is a schematic diagram of the structure of a secondary battery holder provided for other embodiments of this application.

[0121] In other embodiments, the first cavity wall 310 and the second cavity wall 320 are spaced apart along a first direction X, and a connecting post 330 is provided between the first cavity wall 310 and the second cavity wall 320. The width of the connecting post 330 along a third direction Z is smaller than the width of the first cavity wall 310 and the width of the second cavity wall 320, so that the conductive cavity 3011 can be directly connected to the first space 101, further accelerating the exhaust efficiency.

[0122] See Figure 7 , Figure 7 This is a schematic diagram of the structure of a secondary battery provided in some other embodiments of this application.

[0123] In other embodiments, a third space 103 is formed between the support 300 and the bottom wall 120. The first channel 301 includes a plurality of first through holes 3012 disposed in the support 300. At least one first through hole 3012 connects the interior of the electrode assembly 200 and the third space 103, and at least one first through hole 3012 connects the third space 103 and the first space 101.

[0124] By creating a third space 103 between the support 300 and the bottom wall 120, the first channel 301 includes a plurality of first through holes 3012 disposed in the support 300. At least one first through hole 3012 connects the interior of the electrode assembly 200 and the third space 103, and at least one first through hole 3012 connects the third space 103 and the first space 101. This allows the gas generated by the electrode assembly 200 to flow directly through the first through hole 3012 to the third space 103 and further to the first space 101. The gas flow speed is relatively fast, further reducing gas accumulation between the electrode assembly 200 and the bottom wall 120.

[0125] See Figure 8 , Figure 8 This is a schematic diagram of the structure of a secondary battery provided in some other embodiments of this application.

[0126] In other embodiments, a second space 102 is formed between the support 300 and the electrode assembly 200, and the first channel 301 includes a third through hole 3013 disposed in the support 300, the third through hole 3013 connecting the second space 102 and the first space 101.

[0127] By forming a second space 102 between the support 300 and the electrode assembly 200, the first channel 301 includes a third through hole 3013 disposed in the support 300. The third through hole 3013 connects the second space 102 and the first space 101, so that the gas generated by the electrode assembly 200 can directly enter the second space 102 and flow to the first space 101 through the third through hole 3013. The gas flow speed is relatively fast, which further reduces the gas accumulation between the electrode assembly 200 and the bottom wall 120.

[0128] See Figure 1 In some embodiments, along the second direction Y, the length of the outer shell 100 is L2, the length of the bracket 300 is L3, and the distance between the electrode assembly 200 and the sidewall 130 is L4, satisfying L2-2*L4≤L3≤L2. For example, L3 can be L2-2*L4, L2-1.8*L4, L2-1.5*L4, L2-1.2*L4, L2-L4, L2-0.7*L4, L2-0.5*L4, L2-0.3*L4, L2-0.1*L4, or L2, or a range consisting of any two of these values.

[0129] In some embodiments, along the third direction Z, the width of the housing 100 is W2, the width of the bracket 300 is W3, and the distance between the electrode assembly 200 and the sidewall 130 is W4, satisfying W2-2*W4≤W3≤W2. For example, W3 can be W2-2*W4, W2-1.8*W4, W2-1.5*W4, W2-1.2*W4, W2-W4, W2-0.7*W4, W2-0.5*W4, W2-0.3*W4, W2-0.1*W4, or W2, or a range consisting of any two of these values.

[0130] Wherein, the length of the outer shell 100 is the distance between the inner walls of the two opposite side walls 130 of the outer shell 100 along the second direction Y, and the width of the outer shell 100 is the distance between the inner walls of the two opposite side walls 130 of the outer shell 100 along the third direction Z.

[0131] When L2-2*L4≤L3≤L2 and / or W2-2*W4≤W3≤W2, the electrode assembly 200 can be fully supported on the bracket 300, reducing the risk of damage to the electrode assembly 200 due to uneven force, and the bracket 300 can be easily installed inside the housing 100.

[0132] In some embodiments, the support 300 is an elastic element.

[0133] By making the bracket 300 an elastic element, it is easy to install the bracket 300 and the electrode assembly 200 inside the housing 100, and the bracket 300 can provide elastic support to the electrode assembly 200, so that when the secondary battery 10 is subjected to external force, it can provide buffer to the electrode assembly 200, reduce the risk of damage to the electrode assembly 200, and improve the safety of the secondary battery 10.

[0134] In some embodiments, the elastic rebound rate of the stent 300 is 0.05-0.35. For example, the elastic rebound rate of the stent 300 can be 0.05, 0.08, 0.1, 0.12, 0.15, 0.17, 0.2, 0.23, 0.25, 0.28, 0.3, 0.32 or 0.35, or a range consisting of any two of these values.

[0135] When the elastic rebound rate of the support 300 is 0.05-0.35, it can ensure that the elastic rebound rate of the support 300 is not too small, further improving the elastic support force of the support 300 on the electrode assembly 200 and reducing the risk of damage to the electrode assembly 200 when the secondary battery 10 is subjected to external force. At the same time, it can ensure that the elastic rebound rate of the support 300 is not too large, so that the pressure of the support 300 on the electrode assembly 200 is not too large, reducing the influence of the support 300 on the internal resistance of the electrode assembly 200.

[0136] In some embodiments, a positive electrode post 112 and a negative electrode post 113 are further provided on the top wall 110. The positive electrode post 112 penetrates the top wall 110 and is connected to the electrode assembly 200, and the negative electrode post 113 penetrates the top wall 110 and is connected to the electrode assembly 200.

[0137] This application provides an electrical device, including a secondary battery 10 as described above, which is used to provide electrical energy.

[0138] The electrical equipment can be any of the aforementioned devices or systems that use the secondary battery 10.

[0139] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0140] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A secondary battery, characterized in that, include: The housing includes a top wall, a bottom wall, and side walls. The top wall and the bottom wall are disposed opposite each other along a first direction. The side walls connect the top wall and the bottom wall. The top wall is provided with a pressure relief mechanism. Electrode assembly, disposed within the housing; A support is disposed between the bottom wall and the electrode assembly. The support has a first channel. The electrode assembly and the side wall are spaced apart to form a first gap space. The first gap space communicates with the first channel. The first channel is used to guide the gas discharged by the electrode assembly toward the bottom wall to the first gap space.

2. The secondary battery according to claim 1, characterized in that, The first channel includes a conductive cavity formed inside the support, the conductive cavity including a first cavity wall, a second space between the first cavity wall and the electrode assembly, the second space connecting the first space and the first channel; the first channel also includes a plurality of first through holes disposed in the first cavity wall, at least one first through hole connecting the interior of the electrode assembly and the conductive cavity, and at least one first through hole connecting the conductive cavity and the second space. And / or, a third space is formed between the bracket and the bottom wall, the third space connecting the first space and the first channel.

3. The secondary battery according to claim 2, characterized in that, The inner wall of the first through hole is provided with a hydrophilic coating, the thickness of which is t in μm, and the diameter of the first through hole is D0 in mm, satisfying 10≤t / D0≤200; the hydrophilic coating comprises at least one of hydrophilic polyurethane, modified cellulose, or hydrophilic acrylate polymer.

4. The secondary battery according to claim 3, characterized in that, The hydrophilic coating has a micro-rough structure on its outer surface away from the inner wall of the first through hole, and the surface arithmetic mean roughness Ra of the micro-rough structure satisfies 0.8μm≤Ra≤6.3μm.

5. The secondary battery according to any one of claims 2-4, characterized in that, The first cavity wall includes a first part, a second part, and a third part. Along a second direction, the second part is located between the first part and the third part. The second part abuts against the electrode assembly. A first through hole disposed on the second part communicates the interior of the electrode assembly and the conductive cavity. The first part is spaced from the electrode assembly to form a part of the second space. The third part is spaced from the electrode assembly to form another part of the second space. The first through hole disposed on the first part and / or the third part communicates the conductive cavity and the second space. The second direction is perpendicular to the first direction.

6. The secondary battery according to any one of claims 2-5, characterized in that, Along the second direction, the first cavity wall has a first edge and a second edge, the first cavity wall has a first region, along the second direction, the first region has a first side and a second side, the first side is closer to the first edge than the second side, the minimum distance between the first side and the first edge and the minimum distance between the second side and the second edge are both S1, the length of the first cavity wall is L1, which satisfies 1 / 6≤S1 / L1≤1 / 3; Along the third direction, the first cavity wall has opposing third edges and fourth edges. Along the third direction, the first region has opposing third sides and fourth sides. The third side is closer to the third edge than the fourth side. The minimum distance between the third side and the third edge and the minimum distance between the fourth side and the fourth edge are both S2. The width of the first cavity wall is W1, which satisfies 1 / 6≤S2 / W1≤1 / 3. The diameter of the first through hole located in the first region is larger than the diameter of the first through hole located in other regions of the first cavity wall; The first direction, the second direction, and the third direction are perpendicular to each other.

7. The secondary battery according to claim 6, characterized in that, The first cavity wall has a second region along the second direction, the second region has a fifth side and a sixth side opposite to each other, the fifth side is closer to the first edge than the sixth side, the minimum distance between the fifth side and the first edge and the minimum distance between the sixth side and the second edge are both S3, and the length of the first cavity wall is L1, satisfying 0 < S3 / L1 ≤ 1 / 6; Along the third direction, the second region has a seventh side and an eighth side, the seventh side being closer to the third edge than the eighth side. The minimum distance between the seventh side and the third edge and the minimum distance between the eighth side and the fourth edge are both S4. The width of the first cavity wall is W1, satisfying 0 < S4 / W1 ≤ 1 / 6. The first side, the second side, the third side, and the fourth side are the inner sides of the second region, and the other regions of the first cavity wall besides the first region and the second region are the third region; The diameter of the first through hole in the first region is greater than the diameter of the first through hole in the second region, and the diameter of the first through hole in the first region is greater than the diameter of the first through hole in the third region.

8. The secondary battery according to claim 7, characterized in that, The secondary battery must meet at least one of the following conditions; (1) The diameter of the first through hole in the first region is D1, and the diameter of the first through hole in the second region is D2, satisfying 50%≤D2 / D1≤60%; (2) The diameter of the first through hole in the third region is D3, which satisfies 30%≤D3 / D2≤50%; (3) The first region is provided with multiple first through holes, and the distance between two adjacent first through holes is D4, which satisfies 0.8*(D2+D3)≤D4≤1.2*(D2+D3).

9. The secondary battery according to any one of claims 2-8, characterized in that, The electrode assembly is covered with a protective film, and a second through hole is provided on the protective film located between the electrode assembly and the bottom wall. When viewed along the first direction, the second through hole does not overlap with the first through hole. The diameter of the first through hole is D0, and the diameter of the second through hole is D5, satisfying 60%≤D0 / D5≤150%.

10. The secondary battery according to any one of claims 2-9, characterized in that, Along the first direction, the height of the electrode assembly is H1, and the height of the conductive cavity is H2, satisfying 0.8%≤H2 / H1≤3.5%.

11. The secondary battery according to any one of claims 2-10, characterized in that, The cavity wall of the conductive cavity includes a second cavity wall, and the third space is formed between the second cavity wall and the bottom wall; the first channel also includes a plurality of third through holes disposed in the second cavity wall, and the third through holes connect the conductive cavity and the third space. When viewed along the first direction, the first through hole and the third through hole do not overlap.

12. The secondary battery according to claim 11, characterized in that, The first cavity wall and / or the second cavity wall are arranged in an arc shape.

13. The secondary battery according to claim 1, characterized in that, A third space is formed between the support and the bottom wall. The first channel includes a plurality of first through holes disposed on the support. At least one first through hole connects the interior of the electrode assembly and the third space, and at least one first through hole connects the third space and the first space; or, A second space is formed between the support and the electrode assembly. The first channel includes a third through hole disposed on the support, and the third through hole connects the second space and the first space.

14. The secondary battery according to any one of claims 1-13, characterized in that, Along the second direction, the length of the outer shell is L2, the length of the bracket is L3, and the distance between the electrode assembly and the sidewall is L4, satisfying L2 - 2*L4 ≤ L3 ≤ L2; and / or, Along a third direction, the width of the outer shell is W2, the width of the bracket is W3, and the distance between the electrode assembly and the sidewall is W4, satisfying W2-2*W4≤W3≤W2.

15. The secondary battery according to any one of claims 1-14, characterized in that, The bracket is an elastic element with an elastic rebound rate of 0.05-0.

35.

16. An electrical appliance, characterized in that, Includes the secondary battery as described in any one of claims 1 to 15.

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