Electrochemical device and electric device

Abstract

The utility model relates to the field of electrochemical devices, in particular to an electrochemical device and an electric device. The electrochemical device comprises a shell, the shell comprises a middle frame and a cover body, the middle frame defines a containing space, and the middle frame comprises two frame faces which are oppositely arranged; the cover body is arranged on the frame surface, the cover body seals the accommodating space, and the projection of the cover body on the frame surface is located in the frame surface; the shell is provided with a first welding seam and a second welding seam. The first welding seam is located in the middle frame and close to the cover. The second welding seam is located at the edge of the cover body and connected end to end, and the projection of the second welding seam on the frame face is located in the frame face. By applying the technical scheme of the invention, the problem of poor air tightness of the electrochemical device in the prior art can be effectively solved.

Description

Technical Field

[0001] This application relates to the field of electrochemical devices, and particularly to an electrochemical device and an electrical device using the same. Background Art

[0002] Due to many advantages, lithium-ion batteries have become the main power source for consumer electronics and electric vehicles.

[0003] In related technologies, lithium-ion batteries generally use a metal shell as the outer packaging material for wrapping the wound core. To ensure the tightness of the shell, welding is currently mostly used for connection.

[0004] However, to ensure the welding strength, a relatively large power is often used during welding, which easily leads to problems such as over-welding or even welding through when welding the shell, resulting in poor airtightness of the shell and further affecting the qualification rate of shell processing. Summary of the Utility Model

[0005] This application provides an electrochemical device and an electrical device using the same to solve the problem of poor airtightness of lithium-ion batteries in related technologies.

[0006] On the one hand, this application provides an electrochemical device, including a shell, and the shell includes:

[0007] A middle frame that encloses an accommodation space, and the middle frame includes two relatively arranged frame surfaces;

[0008] A cover body disposed on the frame surface, the cover body closes the accommodation space, and the projection of the cover body on the frame surface is located within the frame surface; the shell has a first weld seam and a second weld seam. The first weld seam is located on the middle frame and close to the cover body; the second weld seam is located at the edge of the cover body, the second weld seam is end-to-end connected, and the projection of the second weld seam on the frame surface is located within the frame surface.

[0009] In some embodiments, the middle frame includes a plurality of side plates, the first weld seam is located at the edge of the side plate close to the cover body, and at least one first weld seam is provided on each side plate.

[0010] In some embodiments, the first weld seam forms a first molten pool in a first direction, and the first molten pool includes a first molten portion located on the cover body and a second molten portion located on the middle frame.

[0011] In some embodiments, the maximum depth of the first molten portion in a third direction is H11, and the maximum depth of the second molten portion in the third direction is H12, and H11 and H12 satisfy: 0.3 ≤ H11 / H12 ≤ 0.7.

[0012] In some embodiments, the ratio of the length of the first weld seam to the length of the side plate where the first weld seam is located is between 1 / 6 and 1 / 8.

[0013] In some embodiments, the thickness of the side plate is D1, and the thickness at the location of the first weld on the side plate is D2, where D1 and D2 satisfy: 0.8 ≤ D1 / D2 ≤ 1.2.

[0014] In some embodiments, the first weld has a predetermined distance L4 from the end of the side plate where the first weld is located.

[0015] In some embodiments, the ratio of the minimum value of the predetermined distance L4 to the length of the side plate where the first weld is located is between 1 / 8 and 1 / 10.

[0016] In some embodiments, there are two first welds on the side plate of each middle frame, and the two first welds are arranged close to the end of the side plate where the first weld is located.

[0017] In some embodiments, the second weld forms a second molten pool in the third direction, and the second molten pool includes a third molten part located on the cover body and a fourth molten part located on the middle frame; the first molten pool and the second molten pool have an overlapping area.

[0018] In some embodiments, the maximum dimension of the first molten pool in the first direction is H1, and the maximum dimension of the second molten pool in the second direction is H2, where H1 and H2 satisfy: 1.5 ≤ H2 / H1 ≤ 2.5.

[0019] In some embodiments, there is a first connection line between the deepest point of the first molten pool in the second direction and the center point of the weld width on the side plate surface of the first molten pool, and there is a second connection line between the deepest point of the second molten pool and the center point of the weld width on the cover body surface. The included angle between the first connection line and the second connection line is between 60° and 120°.

[0020] In some embodiments, a welding filling part is formed between the frame surface and the end surface of the cover body.

[0021] In some embodiments, the surface of the welding filling part is an arc surface, the radius of the arc surface is between 0.2 mm and 0.4 mm, and the central angle corresponding to the arc surface is between 20° and 90°.

[0022] On the other hand, the present application provides an electrical device including the above-mentioned electrochemical device.

[0023] The electrochemical device provided by the present application includes a housing, which includes a middle frame and a cover. The middle frame has a receiving space for accommodating a wound core and electrolyte. The middle frame has a frame surface, which is the plane opposite to the cover. The cover can be connected to the middle frame by welding, so as to achieve a good sealing effect of the housing. Specifically, the housing has a first weld seam and a second weld seam. The first weld seam is located on the middle frame and close to the cover. The second weld seam is located at the edge of the cover. The second weld seam is end-to-end, and the projection of the second weld seam on the frame surface is within the frame surface. The double-seam welding of the cover and the middle frame is formed by the first weld seam and the second weld seam, ensuring the welding strength. In addition, the second weld seam is equivalent to circumferential welding of the cover, thus ensuring the welding tightness between the cover and the middle frame. At the same time, the molten pool formed by the first weld seam can also be fused with the molten pool formed by the second weld seam, effectively preventing the welding mark bulge inside the housing from contacting the inside of the battery cell and causing a short circuit. Therefore, through the improvement of the structure of the housing and the welding method of the housing in the present application, the housing can reduce the risk of welding through while ensuring the welding strength, and further ensure the airtightness of the housing. Description of the Drawings

[0024] The drawings here are incorporated into the specification and form a part of this specification, showing embodiments consistent with the present application, and are used together with the specification to explain the principles of the present application.

[0025] Figure 1 Schematic perspective view of the housing of the electrochemical device provided by the embodiment of the present application;

[0026] Figure 2 is Figure 1 Enlarged structural view of part A of the housing;

[0027] Figure 3 Exploded structural view of the housing of the electrochemical device provided by the embodiment of the present application;

[0028] Figure 4 Front view of the housing of the electrochemical device provided by the embodiment of the present application;

[0029] Figure 5 Top view of the housing of the electrochemical device provided by the embodiment of the present application;

[0030] Figure 6 Schematic view of the first frame surface of the housing of the electrochemical device provided by the embodiment of the present application;

[0031] Figure 7 Scan view of the first frame surface of the housing of the electrochemical device provided by the embodiment of the present application.

[0032] Explanation of the reference numerals:

[0033] 10. Housing

[0034] 100. Middle frame; 101. Accommodating space; 110. First frame surface; 120. Second frame surface

[0035] 200. Cover body; 210. First cover body; 220. Second cover body; 230. Welding filling part

[0036] 300. First weld seam; 400. Second weld seam

[0037] 501. First welding position; 502. Second welding position; 503. Penetration depth overlapping area Detailed implementation manners

[0038] To make the objectives, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Apparently, the described embodiments are some but not all of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts shall fall within the protection scope of the present application.

[0039] Due to many advantages, lithium-ion batteries have become the main power source for consumer electronic products and electric vehicles.

[0040] In related technologies, the outer packaging material used for mainstream consumer lithium-ion batteries is aluminum-plastic film. However, with the continuous change of the application scenarios of lithium-ion batteries, in order to adapt to harsher environments, batteries using a metal housing as the outer packaging material have emerged, such as steel shell batteries.

[0041] Currently, in order to ensure the sealing of the housing, welding is often used for connection. However, in order to ensure the welding strength, a relatively large power is often used during welding, resulting in problems such as over-welding or even welding through when welding the housing, causing poor airtightness of the housing and affecting the qualification rate of housing processing.

[0042] The present application provides an electrochemical device, which improves the welding method of the housing by improving the structure of the housing, so that the risk of welding through can be reduced while ensuring the welding strength of the housing, thereby ensuring the sealing of the housing.

[0043] The following describes the electrochemical device provided by the embodiments of the present application with reference to the accompanying drawings. It should be noted that the electrochemical device provided by the embodiments of the present application may be a battery, and the battery may be a secondary battery, that is, the battery in the embodiments of the present application can be charged, discharged, and recycled. The specific type of the battery may include, but is not limited to, lithium batteries, etc. The scenarios where the battery can be used include, but are not limited to, electrical devices such as electronic products, energy storage devices, and transportation vehicles, such as mobile communication devices, new energy vehicles, drones, etc. The embodiments of the present application do not make specific limitations in this regard.

[0044] Figure 1 It is a schematic perspective view of the housing of the electrochemical device provided by the embodiments of the present application; Figure 3 It is a schematic exploded view of the housing of the electrochemical device provided by the embodiments of the present application; Figure 4 It is a front view of the housing of the electrochemical device provided by the embodiments of the present application; Figure 5 It is a top view of the housing of the electrochemical device provided by the embodiments of the present application.

[0045] As Figure 1 、 Figures 3 to 5 shown, the electrochemical device of this embodiment includes a housing 10, and the housing 10 includes a middle frame 100 and a cover 200.

[0046] Among them, the middle frame 100 encloses an accommodation space 101, and the middle frame 100 includes two opposite frame surfaces; the cover 200 is disposed on the frame surface and closes the accommodation space 101. The projection of the cover 200 on the frame surface is located within the frame surface. The housing 10 has a first weld seam 300 and a second weld seam 400. The first weld seam 300 is located on the middle frame 100 and close to the cover 200; the second weld seam 400 is located at the edge of the cover 200. The second weld seam 400 is end-to-end, and the projection of the second weld seam 400 on the frame surface is located within the frame surface.

[0047] Applying the technical solution of this embodiment, the middle frame 100 has an accommodation space 101, and the accommodation space 101 can be used to accommodate the winding core and the electrolyte. The middle frame 100 has a frame surface, and the frame surface is the plane of the middle frame 100 opposite to the cover. The cover 200 can be connected to the middle frame 100 by welding, so as to achieve a good sealing effect of the housing. Specifically, the housing 10 has a first weld seam 300 and a second weld seam 400. The first weld seam 300 is located on the middle frame 100 and close to the cover 200. The second weld seam 400 is located at the edge of the cover 200. The second weld seam 400 is end-to-end, and the projection of the second weld seam 400 on the frame surface is located within the frame surface. The double-seam welding of the cover 200 and the middle frame 100 is formed by the first weld seam 300 and the second weld seam 400, ensuring the welding strength. In addition, the second weld seam 400 is equivalent to circumferential seam welding of the cover 200, thereby ensuring the welding tightness between the cover 200 and the middle frame 100.

[0048] Meanwhile, the molten pool formed by the first weld 300 can also fuse with the molten pool formed by the second weld, thus effectively preventing the welding mark bulge inside the housing from contacting the inside of the battery cell due to over-welding of the weld, which may cause a short circuit.

[0049] In some embodiments, the first weld 300 can be formed first, and then the second weld 400 can be formed. Forming the first weld 300 first can achieve the pre-welding of the cover 200 and the middle frame 100, thereby positioning the cover 200 on the middle frame 100. During subsequent main welding, there is no need to use a fixture to position the cover 200 on the middle frame 100, thus simplifying the welding process of the main weld. When forming the second weld 400, the second weld 400 is equivalent to performing circumferential welding on the cover 200, thereby ensuring the welding tightness between the cover 200 and the middle frame 100.

[0050] In addition, it should be noted that since the projection of the cover 200 on the frame surface only covers a part of the frame surface, the cover 200 presents a state where it can overlap on the frame surface, but its overall contour is smaller than the frame surface. This setting method makes it so that when the cover 200 is welded to the middle frame 100, even if the cover expands and deforms due to heat during welding, the cover 200 will not protrude from the middle frame 100. Therefore, no trimming is required, making the housing 10 have a smaller volume, ensuring the energy density of the lithium-ion battery, and at the same time, it can also save the material cost of the housing 10.

[0051] In addition, the housing 10 in this embodiment is convenient to process. Compared with the technology in the background art where the housing needs to be formed by stamping, the structures of the middle frame 100 and the cover 200 are simpler and more convenient to process and form.

[0052] It should be noted that the cover 200 can be a plate body, and the plate body has a small space occupancy rate, which helps to further realize the miniaturization of the structure of the housing 10.

[0053] It should also be noted that the cover can be set to one or two. In the case where only one cover is set, another plate body is used to cover the other frame surface of the middle frame so that the housing 10 can be in a closed state.

[0054] As Figure 1 and Figure 3 shown, in some embodiments, the middle frame 100 includes a first frame surface 110 and a second frame surface 120 that are oppositely arranged, the cover 200 includes a first cover 210 disposed on the first frame surface 110 and a second cover 220 disposed on the second frame surface 120. The projection of the first cover 210 on the frame surface covers a part of the first frame surface 110, and the projection of the second cover 220 on the frame surface covers a part of the second frame surface 120.

[0055] In the above structure, the cover body 200 is provided in two, namely the first cover body 210 and the second cover body 220. The structures of the first cover body 210 and the second cover body 220 are the same and the functions are the same, so that the housing 10 has the advantages of small volume, unified welding method, and unified processing method.

[0056] In some embodiments, the middle frame 100 is surrounded by a plurality of side plates, and the cover body 200 includes a plurality of edges corresponding to the plurality of side plates one by one. The projection of the edge of each cover body 200 on the frame surface covers a part of the frame surface.

[0057] In the above structure, the edge of the cover body 200 can contact the frame surface and cover a part of the frame surface, so that the cover body can cover a part of the frame surface, but there is a distance L5 between the end face of the cover body and the outer wall of the corresponding side plate (as Figure 4 shown). With such a setting, during welding, the welding device can be directed towards the edge of the cover body 200 for welding. The heat generated by welding can pass through the cover body 200 and the frame surface and radiate to the middle frame 100, so as to realize the welding of the two by melting the cover body 200 and the middle frame 100. During this process, since the cover body 200 may be deformed and extend outwards due to the influence of welding, but since there is a distance L5 between the end face of the cover body and the outer wall of the corresponding side plate, this distance makes the end face of the cover body 200 not protrude from the outer wall of the side plate even if the cover body 200 is deformed, so that the housing 10 occupies a smaller volume and there is no convex structure on the housing 10, avoiding piercing other external structures.

[0058] As Figure 1 and Figure 4 shown, in some embodiments, the middle frame 100 has a length L1 in the first direction (the x direction shown in Figure 4 ), the cover body 200 has a length L2 in the first direction, and the middle frame 100 has a thickness L3 in the first direction. L1, L2, and L3 satisfy: 0 < L1 - L2 < 2L3, that is, the difference between L1 and L2 is greater than 0 and less than 2 times L3.

[0059] The above structure enables the cover body 200 to overlap on the frame surface, and at the same time there is a distance (see L5 in Figure 4 ) between the end face of the cover body 200 and the outer wall of the corresponding side plate. This distance makes the end face of the cover body 200 not protrude from the outer wall of the side plate even if the cover body 200 is deformed, so that the housing 10 occupies a smaller volume and there is no convex structure on the housing 10, avoiding piercing other external structures.

[0060] It should be noted that if the difference between L1 and L2 is too small, the distance of L5 will be smaller, and after the cover body 200 is welded, it is easy to protrude from the outer wall of the side plate, resulting in an outward convex structure formed on the housing 10, increasing the space occupied by the housing 10 and being prone to damage to other external structures. If the difference between L1 and L2 is too large, the overlapping area of the cover body 200 and the frame surface is too small, affecting the welding stability between the cover body 200 and the frame body.

[0061] Exemplarily, the first direction (such as Figure 4 the x direction shown in

[0062] In some other embodiments, the length L of the middle frame 100 in the first direction and the length L2 of the cover body 200 in the first direction may also satisfy: 0.9 < L2 / L1 < 1. In the above structure, the size of the cover body 200 in the first direction can be determined according to the size of the middle frame 100 in the first direction, making the processing of the cover body 200 more convenient.

[0063] Exemplarily, the specific values that L2 / L1 can adopt include but are not limited to 0.91, 0.93, 0.95, 0.97, 0.99, etc.

[0064] Correspondingly, as Figure 1 and Figure 5 shown, in some embodiments, the length of the middle frame 100 in the second direction (such as Figure 5 the y direction shown in

[0065] is W1, the length of the cover body 200 in the second direction is W2, and the thickness of the middle frame 100 in the second direction is W3. W1, W2, and W3 satisfy: 0 < W1 - W2 < 2W3, that is, the difference between W1 and W2 is greater than 0 and less than 2 times W3. Figure 5 The above structure enables the cover body 200 to overlap on the frame surface. At the same time, in the second direction (such as

[0066] the y direction shown in

[0067] ), there is a distance between the end face of the cover body 200 and the outer wall of the corresponding side plate. This distance ensures that even if the cover body 200 deforms, the end face of the cover body will not protrude from the outer wall of the side plate, so that the housing 10 occupies a smaller volume, there is no outward convex structure on the housing 10, and it is avoided to pierce other external structures.

[0068] In some other embodiments, the length W1 of the middle frame 100 in the second direction and the length W2 of the cover body 200 in the second direction may also satisfy: 0.9 < W2 / W1 < 1. In the above structure, the size of the cover body 200 in the second direction can be determined according to the size of the middle frame 100 in the second direction, thereby making the processing of the cover body 200 more convenient.

[0069] Exemplarily, the specific values that W2 / W1 can adopt include but are not limited to 0.91, 0.93, 0.95, 0.97, 0.99, etc.

[0070] Furthermore, in some embodiments, the cover body 200 and the middle frame 100 are connected by welding. Welding connection can not only ensure the stable connection between the cover body 200 and the middle frame 100, but also ensure the sealing performance between the cover body 200 and the middle frame 100.

[0071] Exemplarily, both the first cover body 210 and the second cover body 220 are connected to the middle frame 100 by welding.

[0072] In some embodiments, the first weld seam 300 includes a plurality of them, and at least one first weld seam 300 is provided on each side plate, so that each edge of the cover body 200 can be pre-fixed, thereby ensuring the stability during the main welding of the cover body 200.

[0073] Since the size of the cover body is smaller than that of the middle frame, a right-angle area can be formed between the end face of the cover body and the frame face of the middle frame. When the first weld seam 300 is welded, the melted cover body or side plate can fill into the right-angle area to form a chamfer structure, making the shell smoother. At the same time, it also reduces the influence of the excess height and stress accumulation caused by conventional welding.

[0074] Specifically, the first weld seam 300 has a first molten pool a, and the first molten pool a includes a first molten part located on the cover body 200 and a second molten part located on the middle frame 100. During welding, the first molten part and the second molten part are in a molten state. When cooled, the first molten part and the second molten part are cooled into a solid state, and the cover body and the middle frame can be welded together to form a stable connection.

[0075] In some embodiments, the maximum depth of the first molten part in the third direction is H11, and the maximum depth of the second molten part in the third direction is H12, and H11 and H12 satisfy: 0.3 ≤ H11 / H12 ≤ 0.7; wherein, the first direction, the second direction, and the third direction are perpendicular to each other in pairs.

[0076] In the above structure, since the first weld seam is provided on the middle frame and close to the cover body, the maximum depth H12 of the second molten part in the third direction is greater than the maximum depth H11 of the first molten part in the third direction. Making the ratio of H11 / H12 between 0.3 and 0.7 can prevent the depth of the first molten part in the third direction from being too large, affecting the surface flatness and cleanliness of the cover body.

[0077] Exemplarily, the ratio of H11 / H12 can be 0.3, 0.5, 0.6 or 0.7. It should be noted that since the first weld seam 300 plays a role of pre-fixing, the first weld seam 300 does not need to be welded too long to reduce energy consumption. As Figure 2 and Figure 6 shown, in some embodiments, the ratio of the length of the first weld seam 300 to the length of the side plate where the first weld seam 300 is located is between 1 / 6 and 1 / 8.

[0078] Exemplarily, the specific values that the ratio of the length of the first weld seam 300 to the length of the side plate where the first weld seam 300 is located can adopt include but are not limited to 1 / 6, 1 / 7, 1 / 8, etc.

[0079] In addition, as Figure 2 and Figure 6 shown, in some embodiments, the first weld seam 300 has a predetermined distance L4 from the end of the side plate where the first weld seam 300 is located.

[0080] In the above structure, if the first weld seam 300 is at the end of the side plate where it is located, it is easy to cause welding deformation of the cover body and the side plate after welding. Having a predetermined distance L4 between the first weld seam 300 and the end of the side plate where the first weld seam 300 is located can reduce the probability of deformation of the cover body and the side plate, so as to ensure the welding effect of the housing 10.

[0081] In some embodiments, when determining the value of the predetermined distance L4, it can be determined according to the length of the side plate where the first weld seam 300 is located. Exemplarily, the ratio of the minimum value of the predetermined distance L4 to the length of the side plate where the first weld seam 300 is located can be between 1 / 8 and 1 / 10, thereby effectively reducing the probability of deformation of the cover body and the housing after pre-welding.

[0082] Specifically, in some embodiments, each side plate of the middle frame 100 has two first weld seams 300 to facilitate better fixation of the cover body 200. The two first weld seams 300 are arranged close to the end of the side plate where the first weld seam 300 is located, so as to avoid the middle area of the side plate. Pre-welding the weld seam in the middle of the side plate is likely to cause deformation of the cover body and the side plate after welding. Therefore, arranging the two first weld seams 300 close to the end of the side plate where the first weld seam 300 is located can further reduce the probability of deformation caused by pre-welding.

[0083] In some embodiments, the thickness of the side plate is D1, and the thickness at the position with the first weld on the side plate is D2. D1 and D2 satisfy: 0.8 ≤ D1 / D2 ≤ 1.2. Since the weld of the welding may cause protrusions or depressions on the outer surface and the inner surface of the middle frame, in order to ensure the welding effect, the ratio of D1 / D2 can be between 0.8 and 1.2. On the one hand, it limits the height of the protrusions formed on the inner surface of the middle frame, thereby reducing the probability of the protrusions touching the battery cell. On the other hand, it can also ensure the flatness of the outer surface of the middle frame.

[0084] In some embodiments, the welding power density of the second weld 400 is greater than that of the first weld 300.

[0085] In the above structure, the second weld 400 can achieve the main welding of the cover body 200 and the middle frame 100, thereby realizing the connection and sealing of the cover body 200 and the middle frame 100.

[0086] It should be noted that the welding power density refers to the ratio of the power applied to the metal surface per unit time to the area of the metal surface during the welding process. It is an important indicator to measure the power output ability of the welding equipment and has a direct impact on the welding quality. Therefore, the welding power density of the pre-welding can be less than that of the main welding, that is, the welding power density of the second weld 400 is greater than that of the first weld 300, so as to reduce the welding energy consumption.

[0087] Specifically, the width of the first weld 300 is less than that of the second weld 400, and the width of the first weld 300 is between 1 / 3 and 2 / 3 of the width of the second weld 400. The power density of the first weld 300 is between 3 / 5 and 4 / 5 of that of the second weld 400. The smaller power density makes the frame cover have less thermal deformation on the premise of stable connection and has less impact on the internal battery cell and other structures.

[0088] It should also be noted that as Figure 4 、 Figure 6 and Figure 7 shown, in some embodiments, the welding device welds at the first welding position 501 to form the first weld 300. The first weld 300 has a first molten pool a. The welding device welds at the second welding position 502 to form the second weld 400. The second weld 400 has a second molten pool b in the third direction (such as the z direction in Figure 4 ). As Figure 7 shown, the first weld 300 and the second weld 400 have an overlapping area 303. Specifically, the second molten pool b includes a third molten part located on the cover body and a fourth molten part located on the middle frame. Both the first molten pool a and the second molten pool b include parts located on the middle frame and parts located on the cover body. The stable connection of the middle frame and the cover body is realized through the pre-welding of the first weld 300 and the main welding of the second weld 400.

[0089] As shown Figure 6 in the figure, the first melting pool a and the second melting pool b can overlap to form a penetration overlap region 503 (as shown Figure 7 at c in the figure).

[0090] Furthermore, in some embodiments, the maximum dimension of the first melting pool in the first direction is H1, and the maximum dimension of the second melting pool in the second direction is H2, and H1 and H2 satisfy: 1.5 ≤ H2 / H1 ≤ 2.5.

[0091] In the above structure, the welding positions of the first weld seam and the second weld seam are different, so the depths of the melting pools formed are also different. The first weld seam is formed on the middle frame, and the thickness of the middle frame is small, so the thickness of the first melting pool formed by the first weld seam is small. The second weld seam is formed on the cover body and forms a part that overlaps with the middle frame, so the melting pool formed by the second weld seam can be deeper to ensure the welding effect between the cover body and the middle frame.

[0092] Exemplarily, the ratio of H2 / H1 can be 1.5, 1.6, 1.7, 1.8, 2 or 2.5.

[0093] It should be noted that there is a first connection line between the deepest point of the first melting pool in the second direction and the center point of the melting width on the side plate surface of the first melting pool, and there is a second connection line between the deepest point of the second melting pool and the center point of the melting width on the cover body surface. The included angle between the first connection line and the second connection line is between 60° and 120°. With such a setting, the welding strength between the middle frame and the cover body can be ensured.

[0094] In some embodiments, as shown Figure 4 in the figure, a welding filling part 230 is formed between the frame surface and the end surface of the cover body 200. After the second weld seam is welded, the frame surface and the end surface of the cover body 200 will be melted under the influence of welding heat, thereby forming the welding filling part 230. On the one hand, the welding filling part 230 can increase the connection strength between the cover body and the middle frame, and on the other hand, it can also make a smooth transition between the end surface of the cover body and the frame surface.

[0095] Furthermore, the surface of the welding filling part is an arc surface, the radius of the arc surface is between 0.2 mm and 0.4 mm, and the central angle corresponding to the arc surface is between 20° and 90°, ensuring the smoothness between the end surface of the cover body and the frame surface. Exemplarily, the radius of the arc surface can be 0.2 mm, 0.3 mm or 0.4 mm. The central angle corresponding to the arc surface can be 20°, 30°, 45°, 60°, 70°, 80° or 90°.

[0096] On the other hand, the present application provides an electrical device including the above-described electrochemical device. The electrochemical device further includes an electrode assembly which can be disposed on the middle frame. The electrochemical device further includes an electric core which is disposed in the accommodation space and electrically connected to the electrode assembly.

[0097] In the description of the present application, it should be noted that unless otherwise clearly defined and limited, the terms "mounted", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, or indirectly connected through an intermediate medium, and can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

[0098] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application.

[0099] The terms "first", "second", "third", "fourth", etc. (if any) in the description, claims and drawings of the present application are used to distinguish similar objects and do not necessarily need to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0100] In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0101] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and are not intended to limit them. Although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An electrochemical device, characterized in that The electrochemical device comprises a housing, the housing comprising: A middle frame, wherein the middle frame encloses a receiving space and includes two frame surfaces arranged opposite to each other; A cover body is arranged on the frame surface, the cover body closes the accommodation space, and a projection of the cover body on the frame surface is located within the frame surface; The shell has a first weld and a second weld, the first weld is located on the middle frame and close to the cover body; the second weld is located at the edge of the cover body, the second welds are connected end to end, and the projection of the second weld on the frame surface is located within the frame surface.

2. The electrochemical device according to claim 1, characterized in that The middle frame includes a plurality of side panels, the first weld is located at an edge of the side panel close to the cover body, and at least one first weld is disposed on each side panel.

3. The electrochemical device according to claim 2, characterized in that The first weld forms a first molten pool in a first direction, and the first molten pool includes a first molten portion located on the cover body and a second molten portion located on the middle frame.

4. The electrochemical device according to claim 3, characterized in that The maximum depth of the first fusion zone in the third direction is H11, the maximum depth of the second fusion zone in the third direction is H12, and H11 and H12 satisfy: 0.3≤H11 / H12≤0.

7.

5. The electrochemical device according to claim 2, characterized in that The ratio of the length of the first weld to the length of the side plate where the first weld is located is between 1 / 6 and 1 / 8.

6. The electrochemical device according to claim 2, characterized in that The thickness of the side plate is D1, and the thickness of the side plate at the first weld is D2, and D1 and D2 satisfy: 0.8≤D1 / D2≤1.

2.

7. The electrochemical device according to any one of claims 2 to 6, characterized in that: There is a predetermined distance L4 between the first weld and the end of the side plate where the first weld is located.

8. The electrochemical device according to claim 7, characterized in that The ratio of the minimum value of the predetermined distance L4 to the length of the side plate where the first weld is located is between 1 / 8 and 1 / 10.

9. The electrochemical device according to claim 8, characterized in that Each side plate of the middle frame has two first welds, and the two first welds are arranged close to the end of the side plate where the first welds are located.

10. The electrochemical device according to claim 3, characterized in that The second weld forms a second molten pool in the third direction, and the second molten pool includes a third molten portion located on the cover body and a fourth molten portion located on the middle frame; The first molten pool and the second molten pool have an overlapping area.

11. The electrochemical device according to claim 10, characterized in that The maximum size of the first molten pool in the first direction is H1, the maximum size of the second molten pool in the second direction is H2, and H1 and H2 satisfy: 1.5≤H2 / H1≤2.

5.

12. The electrochemical device according to claim 10, characterized in that There is a first connecting line between the deepest point of the first molten pool in the second direction and the center point of the molten width of the first molten pool on the side plate surface, and there is a second connecting line between the deepest point of the second molten pool and the center point of the molten width on the cover body surface, and the angle between the first connecting line and the second connecting line is between 60° and 120°.

13. The electrochemical device according to claim 1, characterized in that A welding filling portion is formed between the frame surface and the end surface of the cover body.

14. The electrochemical device according to claim 13, characterized in that The surface of the welding filling portion is an arc-shaped surface, the radius of the arc-shaped surface is between 0.2 mm and 0.4 mm, and the central angle corresponding to the arc-shaped surface is between 20° and 90°.

15. An electrical device, characterized in that: An electrochemical device comprising any one of claims 1-14.

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