Battery cell and energy storage cabinet

Abstract

The embodiment of the invention relates to the technical field of energy storage, and provides a single battery and an energy storage cabinet. The switching part comprises a first connecting part welded with the pole and a second connecting part welded with the tab, the first connecting part comprises a first main body part and a first concave part formed by bending from the first main body part to one side of the pole, and the first main body part surrounds the first concave part; the first phase change layer is located in the first sunken part; the first bonding layer is located on the surface, away from the first sunken part, of the first phase change layer, and the first bonding layer further covers part of the surface of the first main body part; the second phase change layer is positioned on the surface, far away from the second connecting part, of the tab; the second bonding layer is located on the surface, away from the tab, of the second phase change layer, and the second bonding layer further covers part of the surface of the tab and part of the surface of the second connecting part.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of energy storage technology, and in particular to a battery cell and an energy storage cabinet. Background Art

[0002] During the use of the battery, the battery will generate heat. For example, during the rapid charge and discharge process of the battery, the battery cell inside the battery shell reacts with the electrolyte and the current passes through the battery cell, which will generate a lot of heat. If the battery cell inside the shell is in a high temperature state for a long time, the performance and life of the battery cell or battery will decrease, and safety accidents such as explosions will be prone to occur. Summary of the invention

[0003] The embodiments of the present application provide a battery cell and an energy storage cabinet, which are at least beneficial to improving the stability of the battery cell.

[0004] According to some embodiments of the present application, on one hand, the embodiments of the present application provide a battery cell, comprising: a shell and a battery cell top cover, and a pole is arranged on the battery cell top cover; a battery cell body, the battery cell body is located in the shell, and the end of the battery cell body has a pole ear led out from the battery cell body; a transition part, the transition part includes a first connection part welded to the pole column and a second connection part welded to the pole ear, the first connection part includes a first main body part and a first recessed part bent from the first main body part to one side of the pole column, and the first main body part surrounds the first recessed part; a first phase change layer, the first phase change layer is located in the first recessed part; a first adhesive layer, the first adhesive layer is located on the surface of the first phase change layer away from the first recessed part, and the first adhesive layer also covers a part of the surface of the first main body; a second phase change layer, the second phase change layer is located on the surface of the pole ear away from the second connection part; a second adhesive layer, the second adhesive layer is located on the surface of the second phase change layer away from the pole ear, and the second adhesive layer also covers a part of the surface of the pole ear and a part of the surface of the second connection part.

[0005] In some embodiments, the phase change temperature of the second phase change layer is lower than the phase change temperature of the first phase change layer.

[0006] In some embodiments, the adhesive strength of the second adhesive layer is greater than the adhesive strength of the first adhesive layer.

[0007] In some embodiments, the tab has a first surface and a second surface relative to each other, the first surface contacts the second connecting portion, the second surface contacts the second phase change layer, the second surface has multiple protrusion structures, and the second phase change layer covers the surface of the protrusion structure and is located between adjacent protrusion structures.

[0008] In some embodiments, the second connecting portion includes a second main body portion and a second recessed portion formed by bending the second main body portion toward a direction away from the pole ear, and the second main body portion surrounds the second recessed portion; the pole ear includes a third main body portion and a third recessed portion formed by bending the third main body portion toward a direction away from the second connecting portion, the third main body portion surrounds the third recessed portion, the third recessed portion is located in the second recessed portion, and the second phase change layer is located in the third recessed portion.

[0009] In some embodiments, a surface of the third recessed portion away from the second recessed portion has a plurality of protruding structures, and the second phase change layer covers the surfaces of the protruding structures and is located between adjacent protruding structures.

[0010] In some embodiments, it also includes: a third phase change layer, the third phase change layer is located on the surface of the second connection part away from the pole ear; and a third adhesive layer, the third adhesive layer is located on the surface of the third phase change layer away from the second connection part and covers part of the surface of the second connection part.

[0011] In some embodiments, it also includes: a fourth phase change layer, the fourth phase change layer is a solid-solid phase change material, the fourth phase change layer is located on the surface of the second connecting part away from the tab, and is also located on the surface of the first main body away from the first phase change layer.

[0012] In some embodiments, the material of the first phase change layer or the material of the second phase change layer is one or more of paraffin-based organic phase change materials, fatty acid organic phase change materials, polymer phase change materials, salt inorganic phase change materials, and metal inorganic phase change materials.

[0013] According to some embodiments of the present application, on the other hand, the embodiments of the present application further provide an energy storage cabinet, including: multiple battery packs, the battery packs including multiple battery cells as in the above embodiments; an energy storage inverter, the energy storage inverter is connected to the battery pack and is used to control the charging or discharging of the battery pack.

[0014] The technical solution provided by the embodiments of the present application has at least the following advantages:

[0015] In the battery cell provided in the embodiment of the present application, the battery cell body is arranged in the shell, and the closed cavity surrounded by the shell and the battery cell top cover can protect the battery cell body and improve the stability of the battery cell. The top of the battery cell body has a pole ear led out from the inside of the battery cell body, and the pole ear is electrically connected to the pole on the battery cell top cover through a transition part, wherein the transition part includes a first connection part welded to the pole and a second connection part welded to the pole ear. The first connecting portion includes a first main body portion and a first recessed portion bent from the first main body portion to one side of the pole, wherein a first phase change layer and a first adhesive layer are arranged in the first recessed portion. When local high temperature is generated in the area where the pole and the first connecting portion are welded, the first phase change layer absorbs heat and undergoes phase change, so that the temperature of the welding area between the pole and the first connecting portion is reduced, thereby preventing heat from being transferred to the battery cell body through the pole ear and affecting the battery cell body; the first adhesive layer is located on the surface of the first phase change layer away from the first recessed portion, and the first adhesive layer also covers a portion of the surface of the first main body, so that the first phase change layer is sealed in the first recessed portion. In this way, even if the first phase change layer undergoes phase change, it will not flow to the area outside the first recessed portion, thereby improving the stability of the battery cell. The second phase change layer is located on the surface of the pole ear away from the second connecting part, the second adhesive layer is located on the surface of the second phase change layer away from the pole ear, and the second adhesive layer also covers part of the surface of the pole ear and part of the surface of the second connecting part. In this way, when the welding area between the pole ear and the second connecting part generates local high temperature, the second phase change layer absorbs heat and undergoes phase change, so as to reduce the temperature of the welding area between the pole ear and the second connecting part, and avoid heat being transferred to the battery cell body through the pole ear and affecting the battery cell body; the second adhesive layer wraps the second phase change layer on the surface of the pole ear away from the second connecting part, so as to avoid the second phase change layer flowing to other places inside the battery cell after phase change, thereby improving the stability of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] One or more embodiments are exemplarily illustrated by the pictures in the corresponding drawings. These exemplified descriptions do not constitute a limitation on the embodiments. Unless otherwise specified, the pictures in the drawings do not constitute a scale limitation. In order to more clearly illustrate the embodiments of the present application or the technical solutions in the traditional technology, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 A schematic diagram of an explosion structure of a battery cell provided in an embodiment of the present application;

[0018] Figure 2 A schematic diagram of the structure of a switching unit provided in an embodiment of the present application;

[0019] Figure 3 A transition portion provided in an embodiment of the present application is welded to a pole ear and a pole post. Figure 2 A schematic diagram of a cross-sectional structure in the AA1 direction shown in FIG.

[0020] Figure 4 A schematic diagram of a partial enlarged structure of a pole ear and a second connecting portion provided in an embodiment of the present application;

[0021] Figure 5 A schematic diagram of a partially enlarged structure of another electrode tab and a second connecting portion provided in an embodiment of the present application;

[0022] Figure 6 A transition portion provided in an embodiment of the present application is welded to a pole ear and a pole post. Figure 2 Another schematic diagram of the cross-sectional structure in the AA1 direction is shown in FIG.

[0023] Figure 7 A transition portion provided in an embodiment of the present application is welded to a pole ear and a pole post. Figure 2 Another schematic cross-sectional structure diagram along the AA1 direction is shown in . DETAILED DESCRIPTION

[0024] As known from the background technology, the heat concentration of the battery cell or battery is prone to thermal runaway.

[0025] At present, inside the battery cell, the tabs on the battery cell body and the poles on the battery cell top cover are connected through the adapter. The tabs and the adapter, as well as the poles and the adapter, are usually welded by laser welding. The welding mark protection in the welding area mainly adopts the method of sticking high-temperature tape or dispensing glue to avoid the welding residue from falling or causing the battery cell short circuit problem. However, due to the intrinsic electrothermal characteristics of the battery cell structure, the resistance of the welding area is large, and the heat generation is large. Therefore, the welding parts of the tabs and the adapter, as well as the welding parts of the adapter and the poles are more prone to local thermal failure. Abnormal heat generation and high temperature can easily lead to battery cell failure. Considering battery safety, it is urgent to design a thermal safety protection structure for the welding parts of the poles and the adapter, as well as the welding parts of the tabs and the adapter.

[0026] The battery cell and energy storage cabinet provided by the present application are at least beneficial to improving the stability of the battery cell.

[0027] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0028] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0029] In the description of the embodiments of the present application, technical terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0030] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of 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 embodiments of the present application can be understood according to the specific circumstances.

[0031] In the accompanying drawings corresponding to the embodiments of the present application, the thickness and area of ​​the layers are magnified for better understanding and ease of description. When describing a component on another component or on the surface of another component, the component may be "directly" located on the surface of the other component, or a third component may be present between the two components. On the contrary, when describing a component on the surface of another component or when another component is formed or provided on the surface of a component, it means that there is no third component between the two components. In addition, when describing a component as being "substantially" formed on another component, it means that the component is not formed on the entire surface of the other component, nor is it formed on a partial edge of the entire surface.

[0032] In the description of the embodiments of the present application, when a certain component “includes” another component, unless otherwise stated, other components are not excluded and other components may be further included.

[0033] The terms used in the description of the various described embodiments herein are used only to describe specific embodiments and are not intended to be limiting. As used in the description of the various described embodiments and the appended claims, "components" are also intended to include plural forms unless the context clearly indicates otherwise.

[0034] The following will describe the various embodiments of the present application in detail with reference to the accompanying drawings. However, it will be appreciated by those skilled in the art that in the various embodiments of the present application, many technical details are provided in order to enable the reader to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solution claimed in the present application can be implemented.

[0035] Figure 1 A schematic diagram of an explosion structure of a battery cell provided in an embodiment of the present application; Figure 2 A schematic diagram of the structure of a switching unit provided in an embodiment of the present application; Figure 3 A transition portion provided in an embodiment of the present application is welded to a pole ear and a pole post. Figure 2 A schematic diagram of a cross-sectional structure in the AA1 direction is shown in FIG.

[0036] refer to Figures 1 to 3 , the battery cell provided in the embodiment of the present application includes: Figure 1 , a shell 100, a cell top cover 200 and a cell body 300, the cell top cover 200 is provided with a pole 210; the cell body 300 is located in the shell 100, and the end of the cell body 300 has a pole ear 310 led out from the cell body 300. The battery cell also includes: a transition part 400, a first phase change layer 511, a first adhesive layer 512, a second phase change layer 521 and a second adhesive layer 522, reference Figure 2 and Figure 3 The transition part 400 includes a first connection part 410 welded to the pole 210 and a second connection part 420 welded to the pole ear 310, the first connection part 410 includes a first main body part 411 and a first recessed part 412 formed by bending the first main body part 411 toward one side of the pole 210, and the first main body part 411 surrounds the first recessed part 412; the first phase change layer 511 is located in the first recessed part 412; the first adhesive layer 512 is located on the surface of the first phase change layer 511 away from the first recessed part 412, and the first adhesive layer 512 also covers a part of the surface of the first main body part 411; the second phase change layer 521 is located on the surface of the pole ear 310 away from the second connection part 420; the second adhesive layer 522 is located on the surface of the second phase change layer 521 away from the pole ear 310, and the second adhesive layer 522 also covers a part of the surface of the pole ear 310 and a part of the surface of the second connection part 420.

[0037] In the battery cell provided in the embodiment of the present application, the battery cell body 300 is disposed in the housing 100. The closed cavity formed by the housing 100 and the battery cell top cover 200 can protect the battery cell body 300 and improve the stability of the battery cell. The top of the battery cell body 300 has a tab 310 extending from the inside of the battery cell body 300. The tab 310 is electrically connected to the pole 210 on the battery cell top cover 200 through the adapter 400. The adapter 400 includes a first connection portion 410 welded to the pole 210 and a second connection portion 420 welded to the tab 310. The first connecting portion 410 includes a first main body portion 411 and a first recessed portion 412 formed by bending the first main body portion 411 toward one side of the pole 210. The first recessed portion 412 includes a first phase change layer 511 and a first adhesive layer 512. When a local high temperature is generated in the area where the pole 210 and the first connecting portion 410 are welded, the first phase change layer 511 absorbs heat and undergoes a phase change, so that the welding area (i.e., the pole 210 and the first connecting portion 410) of the pole 210 and the first connecting portion 410 is Figure 2 The temperature of the area corresponding to the first recessed portion 412 in the battery cell is reduced to prevent heat from being transferred to the battery cell body 300 through the electrode ear 310 and affecting the battery cell body 300; the first adhesive layer 512 is located on the surface of the first phase change layer 511 away from the first recessed portion 412, and the first adhesive layer 512 also covers a portion of the surface of the first main body 411, so that the first phase change layer 511 is sealed in the first recessed portion 412, so that even if the first phase change layer 511 undergoes a phase change, it will not flow to the area outside the first recessed portion 412, thereby improving the stability of the battery cell. The second phase change layer 521 is located on the surface of the pole ear 310 away from the second connecting portion 420, and the second adhesive layer 522 is located on the surface of the second phase change layer 521 away from the pole ear 310, and the second adhesive layer 522 also covers part of the surface of the pole ear 310 and part of the surface of the second connecting portion 420. In this way, when the welding area between the pole ear 310 and the second connecting portion 420 generates a local high temperature, the second phase change layer 521 absorbs heat and undergoes a phase change, so that the welding area between the pole ear 310 and the second connecting portion 420 (i.e. Figure 2 The temperature of the area indicated by the dotted rectangle is reduced to prevent heat from being transferred to the battery cell body 300 through the pole ear 310 and affecting the battery cell body 300; the second adhesive layer 522 wraps the second phase change layer 521 on the surface of the pole ear 310 away from the second connecting portion 420, thereby preventing the second phase change layer 521 from flowing to other places inside the battery cell after phase change, thereby improving the stability of the battery cell.

[0038] In some embodiments, the material of the first phase change layer 511 can be one or more of paraffin-based organic phase change materials, fatty acid-based organic phase change materials, polymer phase change materials, salt-based inorganic phase change materials, and metal-based inorganic phase change materials.

[0039] In some embodiments, the material of the second phase change layer 521 can be one or more of paraffin-based organic phase change materials, fatty acid-based organic phase change materials, polymer phase change materials, salt-based inorganic phase change materials, and metal-based inorganic phase change materials.

[0040] Among them, fatty acid organic phase change materials include lauric acid, capric acid, palmitic acid, stearic acid, myristic acid and octadecanoic acid; polymer phase change materials include polyethylene; salt inorganic phase change materials include hydrates of salts such as sulfates, phosphates, nitrates, acetates and carbonates; metal inorganic phase change materials include metal halides.

[0041] In some embodiments, the material of the first adhesive layer 512 can be an adhesive material such as polyacrylic acid or styrene-butadiene latex.

[0042] In some embodiments, the material of the second adhesive layer 522 can be an adhesive material such as polyacrylic acid or styrene-butadiene latex.

[0043] In some embodiments, the phase change temperature of the second phase change layer 521 is lower than the phase change temperature of the first phase change layer 511. The phase change temperature refers to the critical temperature at which a substance changes between different phases, such as solid-solid phase change, solid-liquid phase change, solid-gas phase change, liquid-gas phase change, etc. Among them, the solid-solid phase change refers to the process in which a material changes from one crystal structure to another crystal structure in the solid state.

[0044] It can be understood that the welding part between the pole ear 310 and the adapter part 400 is closer to the battery cell body 300 than the welding part between the pole post 210 and the adapter part 400, and the heat of the welding part between the pole ear 310 and the adapter part 400 is more easily transferred to the battery cell body 300. Therefore, the welding part between the pole ear 310 and the adapter part 400 has a greater heat dissipation requirement than the welding part between the pole post 210 and the adapter part 400. When the phase change temperature of the second phase change layer 521 is lower than the phase change temperature of the first phase change layer 511, that is, the critical temperature of the phase change of the second phase change layer 521 is lower than the critical temperature of the phase change of the first phase change layer 511, when the welding position between the pole ear 310 and the transition part 400 rises, the second phase change layer 521 begins to undergo phase change and absorb heat at a relatively low temperature, so that the welding position between the pole ear 310 and the transition part 400 will not have high temperature problems. In this way, the welding position between the pole ear 310 and the transition part 400 can dissipate heat faster, thereby improving the stability of the battery cell body 300.

[0045] Taking the case where the material of the first phase change layer 511 and the material of the second phase change layer 521 are both paraffin wax, paraffin wax is composed of straight-chain alkanes with carbon atoms ranging from 14 to 34. When the carbon number of the straight-chain alkanes in the first phase change layer 511 is less than the carbon number of the straight-chain alkanes in the second phase change layer 521, the phase change temperature of the second phase change layer 521 is lower than the phase change temperature of the first phase change layer 511. For example, when the carbon number of the straight-chain alkanes in the second phase change layer 521 is 24, the phase change temperature of the second phase change layer 521 is 50.6°C; when the carbon number of the straight-chain alkanes in the first phase change layer 511 is 21, the phase change temperature of the first phase change layer 511 is 40.2°C. In some embodiments, the phase change rate of the second phase change layer 521 is greater than the phase change rate of the first phase change layer 511. For example, the first phase change layer 511 is paraffin with a phase change temperature of 50°C to 65°C, and the second phase change layer 521 is a composite phase change material formed by adding graphite to the paraffin used in the first phase change layer 511. The addition of graphite has little effect on the phase change temperature of paraffin, but graphite can improve the thermal conductivity of paraffin. For the second phase change layer 521, the addition of graphite can enhance heat transfer, so that the phase change interface of paraffin in the second phase change layer 521 moves faster and the phase change rate of paraffin increases. Therefore, the phase change rate of the second phase change layer 521 is greater than the phase change rate of the first phase change layer 511. When the welding position between the pole tab 310 and the transition part 400 has a greater heat dissipation requirement than the welding position between the pole 210 and the transition part 400, the phase change rate of the second phase change layer 521 is greater than the phase change rate of the first phase change layer 511, which can help to dissipate heat faster at the welding position between the pole tab 310 and the transition part 400, thereby improving the stability of the battery cell body 300.

[0046] In some embodiments, the bonding strength of the second bonding layer 522 is greater than the bonding strength of the first bonding layer 512. The bonding strength is also called adhesive strength or adhesive strength, which refers to the stress required to destroy the interface between the adhesive in the bonding member and the bonded material or its vicinity under external action.

[0047] It can be understood that the first connecting portion 410 includes a first main body portion 411 and a first recessed portion 412 formed by bending the first main body portion 411 toward one side of the pole 210, the first phase change layer 511 is accommodated in the groove of the first recessed portion 412, the first adhesive layer 512 is bonded to the surface of the first recessed portion 412 away from the pole 210 and to a portion of the inner wall of the first recessed portion 412, so that the first phase change layer 511 is enclosed in the first recessed portion 412; and the second phase change layer 521 is located on the surface of the pole ear 310 away from the transition portion 400, and the second adhesive layer 522 is bonded to the surface of the pole ear 310 or the second phase change layer 521 around the second phase change layer 521. The surface of the connecting portion 420 is bonded, so that the second phase change layer 521 is wrapped. The risk of the second phase change layer 521 flowing to other parts after the phase change occurs is greater than the risk of the first phase change layer 511 flowing to other parts after the phase change occurs. When the bonding strength of the second adhesive layer 522 is greater than the bonding strength of the first adhesive layer 512, the problem of the second adhesive layer 522 and the surface of the pole ear 310 or the surface of the second connecting portion 420 falling off after the second phase change layer 521 undergoes a phase change can be avoided, thereby preventing the second phase change layer 521 from flowing to other places in the battery cell after the phase change occurs, thereby improving the stability of the battery cell.

[0048] In the drawings provided in this embodiment, the tab 310 is located on the side surface of the second connection portion 420 close to the pole 210 as an example, which does not constitute a limitation on the position of the tab 310 and the second connection portion 412. In some embodiments, the tab can be located on the side surface of the second connection portion away from the pole.

[0049] Figure 4 A schematic diagram of a partially enlarged structure of a pole ear and a second connecting portion provided in an embodiment of the present application.

[0050] refer to Figure 4 In some embodiments, the tab 310 has a first surface 311 and a second surface 312 opposite to each other, the first surface 311 is in contact with the second connection portion 420, the second surface 312 is in contact with the second phase change layer 521, the second surface 312 has a plurality of protrusion structures 313, and the second phase change layer 521 covers the surface of the protrusion structures 313 and is located between adjacent protrusion structures 313. When the tab 310 and the second connection portion 420 are laser welded, the second surface 312 of the tab 310 may have protrusion structures 313 composed of tiny welding residues, so that when the second phase change layer 521 covers the surface of the protrusion structures 313 on the second surface 312, the protrusion structures 313 composed of these welding residues can be prevented from polluting the inside of the battery cell, and the heat transfer area between the second phase change layer 521 and the tab 310 can be increased, thereby avoiding the problem of high temperature concentration at the welding part between the tab 310 and the second connection portion 420, and improving the use stability of the battery cell.

[0051] In some embodiments, when the pole lug is located on a side surface of the second connecting portion away from the pole, the second side of the pole lug contacts the second connecting portion, and the first side of the pole lug contacts the second phase change layer. In this way, after the pole lug and the second connecting portion are laser welded, a plurality of protrusion structures are provided on the first side of the pole lug, and the second phase change layer covers the surface of the protrusion structure and is located between adjacent protrusion structures.

[0052] Figure 5 A schematic diagram of a partially enlarged structure of another electrode tab and a second connecting portion provided in an embodiment of the present application.

[0053] refer to Figure 5 In some embodiments, the second connecting portion 420 includes a second main body portion 421 and a second recessed portion 422 formed by bending the second main body portion 421 toward a side away from the pole ear 310, and the second main body portion 421 surrounds the second recessed portion 422; the pole ear 310 includes a third main body portion 321 and a third recessed portion 322 formed by bending the third main body portion 321 toward a side of the second connecting portion 420, the third main body portion 321 surrounds the third recessed portion 322, the third recessed portion 322 is located in the second recessed portion 422, and the second phase change layer 521 is located in the third recessed portion 322. In this way, the second adhesive layer 522 is located on the surface of the second phase change layer 521 away from the third recessed portion 322, and the second adhesive layer 522 also covers a portion of the surface of the third main body 321, so that the second adhesive layer 522 seals the second phase change layer 521 in the groove of the third recessed portion 322, thereby preventing the second phase change layer 521 from flowing to a portion outside the third recessed portion 322 after absorbing heat and undergoing phase change, thereby improving the stability of the battery cell. At the same time, the third recessed portion 322 is located in the second recessed portion 422, which can help increase the contact area between the tab 310 and the second connecting portion 420, improve the electrical transmission efficiency between the tab 310 and the adapter 400, and increase the heat dissipation area.

[0054] Combined with reference Figure 4 and Figure 5 In some embodiments, after the pole tab 310 and the second connection portion 420 are laser welded, the surface of the third recessed portion 322 away from the second recessed portion 422 has a plurality of convex structures 313, and the second phase change layer 521 covers the surface of the convex structures 313 and is located between adjacent convex structures 313. In other words, the second recessed portion 422 and the third recessed portion 322 serve as the welding parts of the pole tab 310 and the second connection portion 420, and the convex structures 313 formed by the welding residue formed after welding are located on the inner surface of the third recessed portion 322. When the second phase change layer 521 is located in the third recessed portion 322, it covers the convex structures 313 formed by the welding residue, so as to avoid the convex structures 313 formed by the welding residue from contaminating the internal structure of the battery cell, and at the same time, increase the heat transfer area between the pole tab 310 and the second phase change layer 521, and improve the heat dissipation efficiency.

[0055] In some embodiments, the first recessed portion also has a plurality of convex structures, and the first phase change layer covers the surface of the convex structures and is located between adjacent convex structures. That is, the convex structure formed by the welding residue after the first recessed portion is welded to the pole is covered by the first phase change layer, so that the welding residue after the first recessed portion is welded to the pole can be prevented from polluting the battery cell, and at the same time, the contact area between the first phase change layer and the first recessed portion can be increased, thereby improving the heat dissipation efficiency.

[0056] Figure 6 A transition portion provided in an embodiment of the present application is welded to a pole ear and a pole post. Figure 2 Another schematic diagram of the cross-sectional structure in the AA1 direction is shown in FIG.

[0057] refer to Figure 6 In some embodiments, the battery cell may further include: a third phase change layer 531 and a third adhesive layer 532, wherein the third phase change layer 531 is located on the surface of the second connection portion 420 away from the pole tab 310; and the third adhesive layer 532 is located on the surface of the third phase change layer 531 away from the second connection portion 420, and covers part of the surface of the second connection portion 420. In this way, the portion where the pole tab 310 and the second connection portion 420 are welded can also be cooled by the third phase change layer 531, further improving the cooling rate of the welding portion between the pole tab 310 and the second connection portion 420, and improving the use stability of the battery cell.

[0058] In some embodiments, the material of the third phase change layer 531 can be one or more of paraffin-based organic phase change materials, fatty acid-based organic phase change materials, polymer phase change materials, salt-based inorganic phase change materials, and metal-based inorganic phase change materials.

[0059] In some embodiments, the third adhesive layer 532 may be made of adhesive materials such as polyacrylic acid or styrene-butadiene latex.

[0060] Figure 7 A transition portion provided in an embodiment of the present application is welded to a pole ear and a pole post. Figure 2 Another schematic cross-sectional structure diagram along the AA1 direction is shown in .

[0061] refer to Figure 7In some embodiments, the battery cell may further include: a fourth phase change layer 540, which is a solid-solid phase change material, and is located on the surface of the second connection portion 420 away from the pole lug 310, and is also located on the surface of the first main body portion 411 away from the first phase change layer 511. That is, the surface of one side of the transition portion 400 close to the pole 210 is covered with the fourth phase change layer 540 except for the pole 210 and the part covered by the second adhesive layer 522. The fourth phase change layer 540 is a solid-solid phase change material, so it will not flow after absorbing heat. When the welding part of the transition portion 400 and the pole lug 310 or the pole 210 generates local high temperature, the heat can be transferred to the fourth phase change layer 540 through the transition portion 400. The fourth phase change layer 540 undergoes phase change after absorbing heat, so that the temperature of the transition portion 400 is reduced, thereby achieving overall heat dissipation of the transition portion 400, which is conducive to improving the use stability of the battery cell.

[0062] In some embodiments, the fourth phase change layer may also cover the surface of the second connection portion away from the tab and the surface of one side of the first connection portion close to the first phase change layer to further improve the heat dissipation effect of the fourth phase change layer on the transition portion.

[0063] In some embodiments, the material of the fourth phase change layer 540 is polyethylene glycol.

[0064] In some embodiments, the battery cell body 300 may be a lithium cobalt oxide battery cell, a nickel cobalt manganese battery cell, or a lithium iron phosphate battery cell.

[0065] In some embodiments, the electrode tab includes a positive electrode tab and a negative electrode tab, the electrode column includes a positive electrode column and a negative electrode column, and the corresponding transition portion includes a positive electrode transition portion and a negative electrode transition portion. The positive electrode tab is electrically connected to the positive electrode column through the positive electrode transition portion, and the negative electrode tab is connected to the negative electrode column through the negative electrode transition portion. In this way, at least one of the positive electrode transition portion or the negative electrode transition portion may include a first connecting portion and a first main body portion, and a first phase change layer, a first bonding layer, a second phase change layer and a second bonding layer are arranged on the positive electrode transition portion and the corresponding positive electrode tab; and / or, the first phase change layer, the first bonding layer, the second phase change layer and the second bonding layer are arranged on the negative electrode transition portion and the corresponding negative electrode tab.

[0066] Correspondingly, another embodiment of the present application further provides an energy storage cabinet, including: multiple battery packs and an energy storage converter, the battery pack includes multiple battery cells as in the above embodiment; the energy storage converter is connected to the battery pack, and the energy storage converter can realize energy conversion and bidirectional flow between the energy storage battery pack and the power grid. For the parts that are the same or corresponding to the previous embodiment, please refer to the corresponding description of the previous embodiment, and will not be described in detail below.

[0067] In some embodiments, the energy storage cabinet also includes a battery management system, which is connected to the energy storage inverter. The battery management system can be used to manage and monitor the operating status of the energy storage cabinet. The battery management system sends battery status information and control instructions to the energy storage inverter. The energy storage inverter adjusts power output or performs charging and discharging according to the instructions of the battery management system. The energy storage inverter feeds back real-time operating data to the battery management system to achieve safe operation of the energy storage cabinet.

[0068] The following are specific embodiments of the present application:

[0069] Embodiment 1 is Figures 1 to 3 The battery cell shown in the figure comprises a shell 100, a cell top cover 200 and a cell body 300, wherein a pole 210 is arranged on the cell top cover 200; the cell body 300 is located in the shell 100, and the end of the cell body 300 has a pole ear 310 led out from the cell body 300. The battery cell also comprises: a transition part 400, a first phase change layer 511, a first adhesive layer 512, a second phase change layer 521 and a second adhesive layer 522, the transition part 400 comprises a first connection part 410 welded to the pole 210 and a second connection part 420 welded to the pole ear 310, the first connection part 410 comprises a first main body part 411 and a first recessed part 412 formed by bending the first main body part 411 toward one side of the pole 210, the first main body part 411 surrounds the first recessed part 412; the first phase The phase change layer 511 is located in the first recessed portion 412; the first adhesive layer 512 is located on the surface of the first phase change layer 511 away from the first recessed portion 412, and the first adhesive layer 512 also covers a portion of the surface of the first main body portion 411; the second phase change layer 521 is located on the surface of the pole tab 310 away from the second connecting portion 420; the second adhesive layer 522 is located on the surface of the second phase change layer 521 away from the pole tab 310, and the second adhesive layer 522 also covers a portion of the surface of the pole tab 310 and a portion of the surface of the second connecting portion 420. The structure of the battery cell of comparative example 1 is basically the same as that of the battery cell of embodiment 1, except that the first phase change layer and the first adhesive layer are not provided on the surface of the first connecting portion away from the pole in the battery cell of comparative example 1.

[0070] The structure of the battery cell of Comparative Example 2 is substantially the same as that of the battery cell of Example 1, except that the second phase change layer and the second bonding layer are not provided on the surface of the tab away from the second connecting portion in the battery cell of Comparative Example 2.

[0071] The structure of the battery cell of Comparative Example 3 is basically the same as that of the battery cell of Example 1, except that in the battery cell of Comparative Example 3, the first phase change layer and the first bonding layer are not provided on the surface of the first connecting portion away from the pole, and the second phase change layer and the second bonding layer are not provided on the surface of the tab away from the second connecting portion.

[0072] The structure of the battery cell of Example 2 is basically the same as that of the battery cell of Example 1, except that the tab and the second connecting portion of the battery cell of Example 2 are as follows: Figure 5 The structure shown.

[0073] The structure of the battery cell of Example 3 is basically the same as that of the battery cell of Example 1, except that the surface of the second connecting portion away from the tab in the battery cell of Example 3 is further provided with a Figure 6 The third phase change layer and the third adhesive layer are shown.

[0074] The structure of the battery cell of Example 4 is basically the same as that of the battery cell of Example 1, except that the surface of the side of the transition part close to the pole in the battery cell of Example 4 is covered with a Figure 7 The fourth phase change layer is shown.

[0075] The above-mentioned Examples 1 to 4 and Comparative Examples 1 to 3 were subjected to charge and discharge cycle tests, wherein each Example or comparative example corresponds to 1000 battery cell samples, and each battery cell sample is charged from 0% to 100% and discharged from 100% to 0% under a temperature-controlled environment (25±2°C) as one charge and discharge cycle, and each battery cell sample is subjected to 10,000 charge and discharge cycle tests. During the test, the temperature of the battery cell body in the battery cell sample is obtained, and the highest temperature during the charge and discharge cycle is recorded, and the average value of the highest temperature of the 1000 battery cells corresponding to each group of Examples or Comparative Examples is calculated; and the battery cells with a maximum temperature exceeding 40°C are recorded as failed battery cell samples, and the percentage of failed battery cell samples in each Example or Comparative Example to 1000 battery cell samples is recorded as the failure rate. The test results are as follows:

[0076] Table 1

[0077] Average maximum temperature Failure rate Example 1 32.1 0.09％ Comparative Example 1 34.0 1.11％ Comparative Example 2 35.2 0.92％ Comparative Example 3 37.3 1.54％ Example 2 32.2 0.05％ Example 3 31.9 0.04％ Example 4 31.5 0.02％

[0078] Comparing the experimental results of Example 1 with Comparative Examples 1 to 3, it is found that in the battery cell provided in this embodiment, the welding area between the transition portion 400 and the pole 210 (i.e. Figure 2 The area corresponding to the first recessed portion 412 in the middle) and the welding area between the transition portion 400 and the tab 310 (i.e. Figure 2 After the first phase change layer 511 and the second phase change layer 521 are respectively arranged in the area indicated by the middle dotted rectangle), the maximum temperature rise of the battery cell body during the charge and discharge cycle is reduced, and the failure rate of the battery cell body is reduced during the repeated cycle test.

[0079] By comparing the experimental results of Example 1 and Example 2, it is found that the third recessed portion located in the second recessed portion can be beneficial to increasing the contact area between the pole ear and the second connecting portion, thereby improving the electrical transmission efficiency between the pole ear and the transition portion and increasing the heat dissipation area.

[0080] By comparing the experimental results of Example 1 with those of Example 3, it is found that the third phase change layer can further increase the cooling rate of the welding point between the electrode tab and the second connecting portion, thereby improving the use stability of the battery cell.

[0081] By comparing the experimental results of Example 1 with those of Example 4, it is found that the fourth phase change layer can achieve overall heat dissipation for the transition part, thereby improving the use stability of the battery cell.

[0082] In the battery cell and energy storage cabinet provided in the embodiment of the present application, the battery cell body 300 of the battery cell is arranged in the shell 100, and the closed cavity surrounded by the shell 100 and the battery cell top cover 200 can protect the battery cell body 300 and improve the stability of the battery cell. The top of the battery cell body 300 has a pole ear 310 led out from the inside of the battery cell body 300, and the pole ear 310 is electrically connected to the pole 210 on the battery cell top cover 200 through the adapter 400, wherein the adapter 400 includes a first connection part 410 welded to the pole 210 and a second connection part 420 welded to the pole ear 310. The first connecting portion 410 includes a first main body portion 411 and a first recessed portion 412 formed by bending the first main body portion 411 toward one side of the pole 210. The first recessed portion 412 includes a first phase change layer 511 and a first adhesive layer 512. When a local high temperature is generated in the area where the pole 210 and the first connecting portion 410 are welded, the first phase change layer 511 absorbs the heat and undergoes a phase change, so that the temperature of the welding area between the pole 210 and the first connecting portion 410 is reduced, thereby preventing heat from being transferred through the pole ear 310. The first adhesive layer 512 is located on the surface of the first phase change layer 511 away from the first recessed portion 412, and the first adhesive layer 512 also covers a portion of the surface of the first main body 411, so that the first phase change layer 511 is sealed in the first recessed portion 412. In this way, even if the first phase change layer 511 undergoes a phase change, it will not flow to the area outside the first recessed portion 412, thereby improving the stability of the battery cell. The second phase change layer 521 is located on the surface of the pole ear 310 away from the second connecting part 420, and the second adhesive layer 522 is located on the surface of the second phase change layer 521 away from the pole ear 310, and the second adhesive layer 522 also covers part of the surface of the pole ear 310 and part of the surface of the second connecting part 420. In this way, when the welding area between the pole ear 310 and the second connecting part 420 generates local high temperature, the second phase change layer 521 absorbs heat and undergoes phase change, so that the temperature of the welding area between the pole ear 310 and the second connecting part 420 is reduced, avoiding heat from being transferred to the battery cell body 300 through the pole ear 310 and causing the battery cell body 300 to be affected; the second adhesive layer 522 wraps the second phase change layer 521 on the surface of the pole ear 310 away from the second connecting part 420, thereby avoiding the second phase change layer 521 from flowing to other places inside the battery cell after phase change, thereby improving the stability of the battery cell.

[0083] Those skilled in the art will appreciate that the above-mentioned embodiments are specific examples for implementing the present application, and in practical applications, various changes may be made to the embodiments in form and detail without departing from the spirit and scope of the present application. Any person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present application, and therefore the scope of protection of the present application shall be subject to the scope defined in the claims.

Claims

1. A battery cell, characterized in that: include: A shell and a battery cell top cover, wherein the battery cell top cover is provided with a pole; A battery cell body, the battery cell body is located in the shell, and the end of the battery cell body has a pole ear led out from the battery cell body; A transition portion, the transition portion comprising a first connection portion welded to the pole and a second connection portion welded to the pole tab, the first connection portion comprising a first main body portion and a first recessed portion formed by bending the first main body portion toward one side of the pole, the first main body portion surrounding the first recessed portion; a first phase change layer, wherein the first phase change layer is located in the first recessed portion; a first adhesive layer, the first adhesive layer being located on a surface of the first phase change layer away from the first recessed portion, and the first adhesive layer also covering a portion of a surface of the first main body portion; A second phase change layer, wherein the second phase change layer is located on a surface of the electrode tab away from the second connecting portion; A second adhesive layer, wherein the second adhesive layer is located on a surface of the second phase change layer away from the electrode tab, and the second adhesive layer also covers a portion of the surface of the electrode tab and a portion of the surface of the second connecting portion.

2. The battery cell according to claim 1, characterized in that: The phase change temperature of the second phase change layer is lower than the phase change temperature of the first phase change layer.

3. The battery cell according to claim 1, characterized in that: The bonding strength of the second bonding layer is greater than the bonding strength of the first bonding layer.

4. The battery cell according to claim 1, characterized in that: The pole ear has a first surface and a second surface opposite to each other, the first surface is in contact with the second connecting portion, the second surface is in contact with the second phase change layer, the second surface has a plurality of protrusion structures, and the second phase change layer covers the surface of the protrusion structures and is located between adjacent protrusion structures.

5. The battery cell according to claim 1, characterized in that: The second connecting portion includes a second main body portion and a second recessed portion formed by bending the second main body portion toward a direction away from the pole ear, and the second main body portion surrounds the second recessed portion; the pole ear includes a third main body portion and a third recessed portion formed by bending the third main body portion toward a direction away from the second connecting portion, the third main body portion surrounds the third recessed portion, the third recessed portion is located in the second recessed portion, and the second phase change layer is located in the third recessed portion.

6. The battery cell according to claim 5, characterized in that: A surface of the third recessed portion away from the second recessed portion has a plurality of protruding structures, and the second phase change layer covers the surfaces of the protruding structures and is located between adjacent protruding structures.

7. The battery cell according to claim 1, characterized in that: Also includes: a third phase change layer, the third phase change layer being located on a surface of the second connecting portion away from the tab; A third adhesive layer is located on a surface of the third phase change layer away from the second connecting portion and covers a portion of a surface of the second connecting portion.

8. The battery cell according to claim 1, characterized in that: Also includes: The fourth phase change layer is a solid-solid phase change material, and is located on a surface of the second connecting portion away from the tab, and is also located on a surface of the first main body portion away from the first phase change layer.

9. The battery cell according to claim 1, characterized in that: The material of the first phase change layer or the material of the second phase change layer is one or more of paraffin-based organic phase change materials, fatty acid-based organic phase change materials, polymer phase change materials, salt-based inorganic phase change materials, and metal-based inorganic phase change materials.

10. An energy storage cabinet, characterized in that: include: A plurality of battery packs, each of which comprises a plurality of battery cells as claimed in any one of claims 1 to 9; An energy storage converter is connected to the battery pack.

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