Lower plastic part, end cap assembly and battery cell

Abstract

Lower plastic part used for a battery cell having a top cover, the lower plastic part comprising: a base body having a first surface and a second surface facing away from each other, the first surface (111) being a flat surface and abutting the top cover (002).

Description

Technical FieldThe present application relates to the technical field of batteries, in particular a lower plastic part, an end cap arrangement and a battery cell.Prior ArtIn the prior art, a battery cell includes a housing having a housing opening, an end cap assembly provided at the housing opening, and an electrode assembly located in the housing. The end cap assembly includes an upper cap and a lower plastic portion provided on the upper cap and located near the electrode assembly. The lower plastic part is provided with a plurality of through-holes, for example a liquid injection hole for filling electrolyte and a venting hole which is opposite an explosion-proof valve on the upper cover. The lower plastic part has a cavity on a side facing the upper cover. When liquid is introduced, the electrolyte is guided through the upper cover and the lower plastic part and then flows directly into the environment of the electrode arrangement. This has the result that after the liquid has been introduced into the battery cell, the cavity between the lower plastic part and the upper cover remains empty.It is necessary to reversely provide a part of the plurality of battery cells when the battery cells are connected in series. In the case of the inverted battery cells, a part of electrolyte flows via the through bore on the lower plastic part into a space between the lower plastic part and the upper cover and thus fills the cavity. Therefore, the level of electrolyte with which the electrode assembly is immersed is lowered, which consequently leads to insufficient wetting of the electrode assembly with electrolyte and impairs the performance of the electrode assembly.Technical ProblemThe present application provides a lower plastic part, an end cap assembly, and a battery cell to solve the above-mentioned technical problem.Technical SolutionIn the application, a lower plastic part used for a battery cell is provided in an embodiment of the present application, wherein the battery cell has an upper lid. The lower plastic part comprises a base body having a first surface and a second surface arranged facing away from each other, wherein the first surface is a flat surface and is provided to abut against the top cover.The application further provides an end cap assembly in an embodiment of the present application, comprising: an upper cap, an upper plastic part, a terminal, a pole terminal, and an aforementioned lower plastic part, wherein the first surface is in contact with one side of the upper cap; wherein the upper plastic part is in contact with the other side of the upper cap; the terminal is located on a side of the upper plastic part facing away from the upper cap; and an end of the pole terminal is passed through the lower plastic part, the upper cap, and the upper plastic part in sequence, and is thereafter connected to the terminal.The application further provides a battery cell in an embodiment of the present application that includes an end cap assembly described above.Advantageous EffectsThe present application has the following advantageous aspects:In the lower resin part provided in the present application, by the first surface of the lower resin part that is in contact with the upper lid having a flat structure to abut the lower resin part to the upper lid via the first surface, it is possible to prevent the electrolyte in a reversed battery cell from collecting between the lower resin part and the upper lid, thereby reducing the influence of the reversed battery cell on the electrode assembly immersed in electrolyte, which can ultimately improve the insufficient immersion of the electrode assembly in the reversed battery cell.In the end cap assembly provided in the present application, by the first surface of the lower resin part that is in contact with the upper cap having a flat structure to abut the lower resin part against the upper cap via the first surface, it is possible to prevent the electrolyte in a reverse battery cell from collecting between the lower resin part and the upper cap, thereby reducing the influence of the reverse battery cell on the electrode assembly immersed in electrolyte, which can ultimately improve the insufficient immersion of the electrode assembly in the reverse battery cell.In the battery cell provided in the present application, by the first surface of the lower resin part that contacts the upper lid having a flat structure to abut the lower resin part to the upper lid via the first surface, it is possible to prevent the electrolyte in a reversed battery cell from collecting between the lower resin part and the upper lid, thereby reducing the influence of the reversed battery cell on the electrode assembly immersed in electrolyte, which can ultimately improve the insufficient immersion of the electrode assembly in the reversed battery cell.Brief Description of the FiguresFIG. 1 is a schematic structural view of a lower plastic part according to an embodiment I of the present application; FIG. 2 is a sectional view taken along line E-E of FIG. 1 ; FIG. 3 is an enlarged view of the location F of FIG. 2 ; FIG. 4 is a schematic structural view of a section of a first annular groove according to an embodiment I of the present application; FIG. 5 is an enlarged view of the location G of FIG. 2 ; FIG. 6 is a schematic structural view of a section of a second annular groove according to Embodiment I of the present application; FIG. 7 is a bottom view of the lower plastic part according to Embodiment I of the present application; FIG. 8 is a schematic structural view of an end cap assembly according to Embodiment I of the present application; FIG. 9 is a sectional view taken along line H-H of FIG. 8 ; FIG. 10 is an enlarged view of the location I of FIG. 9 ; FIG. 11 is an enlarged view of the location J of FIG. 9 ; FIG. 12 is a plan view of a lower plastic part according to an embodiment II of the present application; FIG. 13 is a sectional view taken along line A-A of FIG. 1 according to Embodiment II of the present application; FIG. 14 is a schematic structural view of the lower plastic part according to Embodiment II of the present application; FIG. 15 is an enlarged view of the location B of FIG. 13 ; FIG. 16 is a bottom view of the lower plastic part according to Embodiment II of the present application; FIG. 17 is a plan view of an end cap assembly according to Embodiment II of the present application; FIG. 18 is a sectional view taken along line C-C of FIG. 17 ; and FIG. 19 is an enlarged view of the location D of FIG. 18.List of reference numbers:001. Lower plastic part; 011. Base body; 111. first surface; 1111 a. Escape groove; 1111. first annular groove; 1112. second annular groove; 112. second surface; 113. Stiffening rib; 1131. first rib; 1132. second rib; 114. Positioning rib 115. Guide rib; 116. Positioning pin; 117. Through hole; 121. Cone surface; 012. first adhesive layer; 013. second adhesive layer; 002. Top cover; 021. Mounting surface; 003. Upper plastic part; 004. Clamp 005. Pole terminal; 006. Sealing ring.DETAILED EMBODIMENTSIn the description of the present application, unless expressly stated and defined otherwise, the terms "connect", "connect", "fasten", etc. should be understood in the broader sense, which may be, for example, a fixed, detachable or one-piece connection; which may be a mechanical connection or an electrical connection; which may be a direct connection or an indirect connection via an intermediate medium, or an internal communication of two elements or an interaction relationship between the two elements. One of ordinary skill in the art can be based on the subject to determine what meaning the terms mentioned according to the present application are intended to have.In the present application, a first feature disposed "above" or "below" a second feature may be, unless expressly stated and defined otherwise, the case that the first feature directly contacts the second feature or that the first and second features contact without direct contact via another feature disposed therebetween. Moreover, the expression "that a first feature is above a second feature, on or above the second feature" means that the first feature is directly or obliquely above the second feature; alternatively, this expression means that the first feature has a horizontal height that is higher than the horizontal height of the second feature. The term "that a first feature is below a second feature or below the second feature" is understood to mean that the first feature is directly or obliquely below the second feature; alternatively, this term means that the first feature has a horizontal height that is lower than the horizontal height of the second feature.In the explanation of the embodiments, the direction or positioning indicated by the terms "upper", "lower", "right", etc. is used with reference to the direction or positioning shown in each figure, respectively, merely to facilitate the description and simplify the operation. These terms neither suggest implicitly nor explicitly the positioning and the configuration and operation of the device or element in question in a predetermined positioning, so that they do not represent any restriction of the present application here. In addition, the terms "first", "second", etc. are used for distinction in the description without giving any special meaning.Embodiment IIn this embodiment, a lower plastic part 001 used for a battery cell is provided, which includes an end cap assembly, a housing, an electrode assembly, and a current collector plate. The end cap assembly and the housing snap together to form an electrolyte storage chamber. The electrode assembly and the current collector plate are provided in the accommodation chamber. The end cap assembly includes an upper cap, a lower plastic part, and a pole terminal. A pole plate of the electrode assembly is connected to the pole terminal through the current collector plate. The lower plastic part is provided in such a way that it isolates the current collector plate from the upper cover.As shown in FIG. 1, a base 011 has, in particular, a first surface 111 and a second surface 112 which are arranged facing away from one another, wherein the first surface 111 is a flat surface and is provided in such a way that it bears against the upper cover.The lower plastic part 001 has an identical shape to the shape of the cross section of the battery cell. For example, the lower plastic part 001 has a rectangular shape when the battery cell is a square battery cell. The lower resin part 001 has a round shape when the battery cell is a cylindrical battery cell. When using the lower plastic part 001 for a battery cell, it can form a flat contact with the upper cover after it bears against the upper cover, in order to prevent electrolyte from being stored therebetween. In addition, the base body 011 is provided with a through-bore 117 through the first surface 111 and the second surface 112. The through bore 117 includes, but is not limited to, a liquid injection bore, a vent bore for an explosion-proof valve, and a mounting bore for the pole terminal. Two through-holes 117 are shown in FIG. 1, of which one through-hole 117 located in the middle of the lower plastic part 001 is a mounting hole for the pole terminal and the other through-hole 117 is a venting hole for an explosion-proof valve.For example, the roughness of the first surface 111 does not exceed Ra3.2. In particular, the roughness of the first surface 111 may be Ra0.8.In this embodiment, by making the first surface 111 of the lower resin part 001 in contact with the upper lid have a flat structure to abut the lower resin part 001 to the upper lid via the first surface 111, it is possible to prevent the electrolyte in a reverse battery cell from collecting between the lower resin part 001 and the upper lid, thereby reducing the influence of the reverse battery cell on the electrode assembly immersed in electrolyte, which can ultimately improve the insufficient immersion of the electrode assembly in the reverse battery cell.It is also provided that, as shown in FIGS. 2 and 3, the lower plastic part 001 further comprises a first adhesive layer 012, wherein the first adhesive layer 012 is provided on a side on which the first surface 111 is located around a circumferential edge of the through hole 117, and wherein the first adhesive layer 012 is configured to be bonded to the top cover and the main body 011 on both sides, respectively.It is to be understood that when using the lower plastic part 001 for a battery cell, a peripheral edge of the lower plastic part 001 abuts an inner side of the shell of the battery cell to form a sealing fit. In order to improve the tightness between the upper cover and the lower plastic part, at least the first adhesive layer 012 is therefore provided so as to run around the through-bore 117.In addition, the first adhesive layer 012 has an annular structure to conform to the structure of the through hole 117. When the lower resin part 001 has a plurality of through holes 117, the first adhesive layer 012 is provided around the outer periphery of each of the through holes 117. This is, for example, a liquid injection bore, a venting bore for an explosion-proof valve and a mounting bore for the pole terminal. The first adhesive layer 012 includes a glue that does not react with the electrolyte. For example, the adhesive of the glue may be one or more of PVDF powder, styrene-butadiene rubber, polyacrylic acid, polyacrylonitrile, and polyurethane. In particular, the first adhesive layer 012 comprises HLi-T10 series sealants.In this exemplary embodiment, the first adhesive layer 012 is provided around the circumferential edge of the through-hole 117, and the first adhesive layer 012 is bonded to the base body 011 and the top cover on both sides, respectively. Therefore, the first adhesive layer 012 can, on the one hand, sealingly isolate the contact point of the base body 011 on the upper cover from the through bore 117, as a result of which it can be prevented that, in the case of the inverted battery cell, the electrolyte flows into a space between the lower plastic part 001 and the upper cover. This further reduces the influence of the inverted battery cell on the electrode arrangement immersed in electrolytes. On the other hand, the lower plastic part 001 is bonded to one side of the upper cover by the first adhesive layer 012, whereby the stability of the connection between the lower plastic part 001 and the upper cover can be improved, thereby preventing the lower plastic part 001 from wobbling relative to the upper cover.It is further provided that, as shown in FIGS. 1 and 3, the first surface 111 is provided with a first annular groove 1111 around the through hole 117, wherein the first adhesive layer 012 is provided in the first annular groove 1111, and wherein a side of the first adhesive layer 012 facing away from the second surface 112 is coplanar with the first surface 111.It is to be understood that the first adhesive layer 012 in the initial state is a fluid, in particular a glue filling the first annular groove 1111. After the lower plastic part 001 is placed on the upper cover, the glue is in contact with the upper cover. After the glue has cured and an adhesive layer has been formed, the lower plastic part 001 is glued to the upper cover to form one piece, so that the contact point of the lower plastic part 001 on the upper cover is sealingly insulated from the through-bore 117. In addition, when the lower resin part 001 has a plurality of through holes 117, the first annular groove 1111 is provided around the outer periphery of each of the through holes 117, and a first adhesive layer 012 is provided in each annular groove.For example, the first annular groove 1111 is provided coaxially with a corresponding through hole 117.In this embodiment, the first annular groove 1111 is provided so that the first adhesive layer 012 may be provided along the first annular groove 1111. Therefore, on the one hand, the consumption amount of the glue can be controlled and the waste of the glue can be avoided. On the other hand, the first surface 111 and the top cover may remain abutting each other. Thus, there is no gap between the top cover and the first surface 111 due to the provision of the first adhesive layer 012.Further, as shown in FIG. 4, the first annular groove 1111 has one of semicircular shapes, V shapes, U shapes, and rectangular shapes in cross section in a thickness direction of the lower resin part 001. It is to be understood that the cut is a plane formed by cutting the first annular groove 1111 from a surface spanned by an axial direction and a radial direction of the lower resin part 001. Specifically, the shape of the section of the first annular groove 1111 is a semi-circular shape.Because, in this exemplary embodiment, the section of the first annular groove 1111 has a semicircular structure, on the one hand the glue can better fill the first annular groove 1111 and a region without glue is avoided, so that the tightness between the lower plastic part 001 and the upper cover is improved. On the other hand, the uniformity of the glue distribution can be improved by the first annular groove 1111 having a semicircular structure, thereby contributing to avoiding the accumulation of glue in a certain area.It is further provided that, as shown in FIG. 4, the distance between the first surface 111 and the second surface 112 is denoted by D and the depth of the first annular groove 1111 is denoted by d 1 and wherein: 10%D≤d 1≤50%D.It is understood that d may be, but is not limited to, 110% D, 20%D, 40%D, 50%D.For example, 0.4 mm ≤ d 1 ≤ 2 mm when D = 4 mm. Specifically, d may be, but is not limited to, 10,4 mm, 0.5 mm, 0.8 mm, 1 mm, 1.1 mm, 1.2 mm, 1.35 mm, 1.47 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2 mm.By defining the depth of the first annular groove 1111 as described above in this embodiment, the first annular groove 1111 can have a sufficient depth so that sealing connection between the lower plastic part 001 and the top cover can be realized by the first adhesive layer 012. On the other hand, the strength of the lower plastic part 001 can also be ensured, thereby preventing the strength of the lower plastic part 001 from not satisfying the requirements of its working condition due to too large a depth dimension of the first annular groove 1111.Further, it is contemplated that, as shown in FIGS. 4 and 7, the diameter of the lower plastic part 001 is denoted by D 0 and the width dimension of the first annular groove 1111 in a radial direction of the lower plastic part 001 is denoted by W 1 and it holds that 1.5%D 0 ≤ W 1 ≤ 6.5%D 0. It is to be understood that the diameter D 0 of the lower plastic part 001 is the largest diameter of the lower plastic part 001. W 1 may be, but is not limited to, 1.5% D 0, 2% D 0, 4% D 0, 6,5% D 0. For example, 0.45 mm≤W 1≤1.95 mm when D is 0= 30 mm. Specifically, W may be, but is not limited to, 10,45 mm, 0.5 mm, 0.6 mm, 0.71 mm, 0.8 mm, 0.9 mm, 1 mm, 1.1 mm, 1.2 mm, 1.36 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.95 mm.By defining the width of the first annular groove 1111 as described above in this embodiment, the first annular groove 1111 can have a sufficient width so that sealing connection between the lower plastic part 001 and the top cover can be realized by the first adhesive layer 012. On the other hand, the strength of the lower plastic part 001 can also be ensured, thereby preventing the strength of the lower plastic part 001 from not satisfying the requirements of its working condition due to too large a width dimension of the first annular groove 1111.It is also provided that, as shown in FIG. 3, the distance between an inner circumferential edge of the first annular groove 1111 and a circumferential edge of the through hole 117 surrounded by it is denoted by S, and wherein: 1 mm≤S≤5 mm. For example, S may be, but is not limited to, 1 mm, 1.15 mm, 1.3 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.88 mm, 1.9 mm, 2 mm, 2.1 mm, 2.3 mm, 2.9 mm, 3 mm, 3.62 mm, 4 mm, 4.2 mm, 4.5 mm, 4.8 mm, 4.9 mm, 5 mm.In this embodiment, by defining the distance S between the inner peripheral edge of the first annular groove 1111 and the corresponding peripheral edge of the through hole 117 as described above, it is possible to prevent the glue from leaking out of the first annular groove 1111 due to the distance S being too small, thus contaminating the pole terminal or the explosion-proof valve. On the other hand, it is possible to prevent the electrolyte from flowing into a space between the lower resin part 001 and the upper lid due to an excessive clearance S.It is furthermore provided that, as shown in FIG. 5, the lower plastic part 001 further comprises a second adhesive layer 013, wherein the second adhesive layer 013 is provided around an edge circumference of the first surface 111, and wherein the second adhesive layer 013 is configured such that it is bonded to the upper cover and the main body 011 on both sides, respectively. It is understood that the second adhesive layer 013 has an annular structure and the second adhesive layer 013 may have an identical material to the first adhesive layer 012. In particular, the second adhesive layer 013 comprises HLi-T10 series sealants.In this exemplary embodiment, the second adhesive layer 013 is provided around the edge circumference of the first surface 111, and the second adhesive layer 013 is bonded to the base body 011 and the top cover on both sides, respectively. Therefore, the second adhesive layer 013 can, on the one hand, sealingly isolate the contact point of the base body 011 on the upper cover from the outer periphery of the lower plastic part 001, as a result of which it can be prevented that, in the case of the inverted battery cell, the electrolyte flows into a clearance between the lower plastic part 001 and the upper cover. On the other hand, the lower plastic part 001 is bonded to one side of the upper cover by the second adhesive layer 013, whereby the stability of the connection between the lower plastic part 001 and the upper cover can be improved, thereby preventing the lower plastic part 001 from wobbling relative to the upper cover.It is furthermore provided that, as shown in FIG. 5, the first surface 111 is provided at the edge periphery with a second annular groove 1112, wherein the second adhesive layer 013 is provided in the second annular groove 1112, and wherein a side of the second adhesive layer 013 facing away from the second surface 112 is coplanar with the first surface 111. It is understood that the second adhesive layer 013 is also a fluid in the initial state and fills the second annular groove 1112, as is the case with the first adhesive layer 012. After the lower plastic part 001 is placed on the upper cover, the glue is in contact with the upper cover. The glue is cured and the second adhesive layer 013 is formed. As a result, the lower plastic part 001 is glued to the upper cover in one piece, so that the contact point of the base body 011 on the upper cover is sealingly insulated from the through bore 117. For example, the second annular groove 1112 is provided coaxially with the lower plastic part 001.In this embodiment, the second annular groove 1112 is provided so that the second adhesive layer 013 may be provided along the second annular groove 1112. Therefore, on the one hand, the consumption amount of the glue can be controlled and the waste of the glue can be avoided. On the other hand, the first surface 111 and the top cover may remain abutting each other. Thus, there is no gap between the top cover and the first surface 111 due to the provision of the second adhesive layer 013.Further, it is provided that the second annular groove 1112 has one of semicircular shapes, V shapes, U shapes, and rectangular shapes in cross section in a thickness direction of the lower resin part 001. It is to be understood that the section of the second annular groove 1112 is a plane formed by cutting the second annular groove 1112 from a surface spanned by an axial direction and a radial direction of the lower resin part 001, as is the case with the first annular groove 1111. Specifically, the shape of the section of the second annular groove 1112 is a semi-circular shape.Because, in this exemplary embodiment, the section of the second annular groove 1112 has a semicircular structure, on the one hand, the glue can better fill the second annular groove 1112 and a region without glue is avoided, so that the tightness between the lower plastic part 001 and the upper cover is improved. On the other hand, the uniformity of the glue distribution can be improved by the second annular groove 1112 having a semicircular structure, thereby contributing to avoiding the accumulation of glue in a certain area.It is further contemplated that, as shown in FIG. 6, the distance between the first surface 111 and the second surface 112 is denoted by D and the depth of the second annular groove 1112 is denoted by d 2 and where: 10%D≤d 2≤50%D. It is understood that d 210% may be, but is not limited to, D, 20%D, 40%D, 50%D. For example, 0.4 mm ≤ d 2 ≤ 2 mm when D = 4 mm. Specifically, d may be, but is not limited to, 20,4 mm, 0.47 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, 1.15 mm, 1.2 mm, 1.39 mm, 1.4 mm, 1.5 mm, 1.67 mm, 1.68 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2 mm.By defining the depth of the second annular groove 1112 as described above in this embodiment, the second annular groove 1112 can have a sufficient depth so that sealing connection between the lower plastic part 001 and the top cover can be realized by the second adhesive layer 013. On the other hand, the strength of the lower plastic part 001 can also be ensured, thereby preventing the strength of the lower plastic part 001 from not satisfying the requirements of its working condition due to too large a depth dimension of the second annular groove 1112.Further, it is arranged that, as shown in FIG. 6, the diameter of the lower plastic part 001 is denoted by D 0 and the width dimension of the second annular groove 1112 in a radial direction of the lower plastic part 001 is denoted by W 2 and 1.5%D 0 ≤ W 2 ≤ 6.5%D 0. It should be understood that W may be 21,5% D 0, 2% D 0, 4% D 0, 6,5% D 0 but is not limited thereto. For example, 0.45 mm≤W 2≤1.95 mm when D is 0= 30 mm. Specifically, W may be, but is not limited to, 20,45 mm, 0.5 mm, 0.56 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, 1.1 mm, 1.2 mm, 1.55 mm, 1.6 mm, 1.89 mm, 1.95 mm.By defining the width of the second annular groove 1112 as described above in this embodiment, the second annular groove 1112 can have a sufficient width so that sealing connection between the lower plastic part 001 and the top cover can be realized by the second adhesive layer 013. On the other hand, the strength of the lower plastic part 001 can also be ensured, thereby preventing the strength of the lower plastic part 001 from not satisfying the requirements of its working condition due to too large a width dimension of the second annular groove 1112.It is further contemplated that, with reference to FIG. 7, the second surface 112 is provided with a positioning rib 114, the positioning rib 114 being provided to be interlocked with a current collector plate of the battery cell. The positioning rib 114 may position the current collector plate to prevent rotation of the current collector plate.Further, it is arranged that, with reference to FIG. 1, the first surface 111 is provided with a plurality of positioning pins 116, the positioning pins 116 being provided to be in engagement with the top cover. For example, the positioning pins 116 and the base 011 are integrally formed, and the positioning pins 116 are cylinders.In this embodiment, by providing the first surface 111 with the positioning pins 116 that are in engagement with the upper cover, the rotation of the lower resin part 001 relative to the upper cover can be prevented, so that the stability of positioning the lower resin part 001 relative to the upper cover can be improved, and thus the stability of the structure of the battery cell is improved.As shown in FIGS. 8 and 9, an end cap assembly is further provided in this embodiment.In particular, the end cover arrangement comprises an upper cover 002, an upper plastic part 003, a terminal 004, a pole terminal 005 and an abovementioned lower plastic part 001, wherein the first surface 111 is in contact with one side of the upper cover 002; the upper plastic part 003 is in contact with the other side of the upper cover 002; the terminal 004 is located on a side of the upper plastic part 003 facing away from the upper cover 002; and one end of the pole terminal 005 is guided through the lower plastic part 001, the upper cover 002 and the upper plastic part 003 one after the other and is then connected to the terminal 004, and wherein in particular the pole terminal 005 is inserted into the terminal 004.It will be understood that the bore in the terminal 004 used to insert the pole terminal 005 is a stepped bore, with a large diameter bore portion of the stepped bore on a side of the terminal 004 remote from the top cover 002. The pole terminal 005 is a stepped shaft, a large-diameter shaft portion is located on a side of the lower resin part 001 facing away from the upper cover 002, and one end of a small-diameter shaft portion is passed through the lower resin part 001, the upper cover 002, the upper resin part 003, and the stepped bore in sequence. The small diameter shaft portion is pushed down, whereby the small diameter shaft portion extends in a radial direction toward the bore wall of the large diameter bore portion, so that the pole terminal 005 abuts against the bore bottom of the large diameter bore portion. Thus, the lower plastic part 001, the upper cover 002, the upper plastic part 003 and the terminal 004 are riveted as one piece by the pole terminal 005. In addition, a sealing ring 006 is provided between the pole terminal 005 and the upper cover 002.In connection with the foregoing embodiments, both the first adhesive layer 012 and the second adhesive layer 013 are bonded to the top cover 002 as shown in FIGS. 10 and 11. As shown in FIG. 10, the left first adhesive layer 012 is provided around the through hole 117 provided for the passage of the pole terminal 005 in the lower plastic part 001, and the right first adhesive layer 012 is provided around the through hole 117 provided for the venting in the lower plastic part 001. As shown in FIG. 11, the first adhesive layer 012 is provided around the through hole 117 provided for venting in the lower plastic part 001, and the second adhesive layer 013 is provided around the peripheral edge of the first surface 111.In this embodiment, the first surface 111 of the lower resin part 001 is formed as a flat surface, and the first surface 111 is provided with the first annular groove 1111 and the second annular groove 1112. The adhesive is then applied into the annular grooves. Then, the lower plastic part 001 is riveted to the upper cover 002, so that the lower plastic part 001 is bonded to the upper cover 002, whereby the space between the lower plastic part 001 and the upper cover 002 is sealingly insulated from the outside. Thus, it is possible to prevent the electrolyte from entering a space between the lower plastic part 001 and the upper lid 002. As a result, no liquid is stored or accumulated between the lower plastic part 001 and the upper lid 002, thereby reducing the influence of the reversed battery cell on the electrode assembly immersed in electrolyte, which can ultimately improve the problem of the electrode assembly being insufficiently immersed in the reversed battery cell.Working Example IIWhen the end cap assembly is pressed into the housing, the lower plastic part 001 typically presses the electrode assembly together in an axial direction of the battery cell. At the same time, the electrode arrangement exerts a counterforce on the lower plastic part 001. Since both sides of the lower plastic part 001 are defined by the upper cover and the electrode assembly, the lower plastic part 001 expands radially due to the axial pressure and then compresses the housing opening, resulting in deformation of the housing opening, thus being unfavorable for welding the housing to the upper cover.Proceeding from this, based on exemplary embodiment I, a lower plastic part 001 is provided in this exemplary embodiment. The lower plastic part 001 in this exemplary embodiment differs from the lower plastic part 001 of exemplary embodiment I in that,As shown in FIGS. 12 and 13, the first surface 111 is provided so as to be in contact with the top lid 002. On a circumferential line of the first surface 111, an escape groove 1111 ais provided. The escape groove 1111 aextends along at least a part of the circumference of the first surface 111. It is understood that the escape groove 1111 amay extend along a part of the perimeter of the first surface 111 or along the entire perimeter as an annular groove. In addition, the lower resin part 001 is an insulating part used for insulating the electrode assembly from the upper cover 002. The lower plastic part 001 has an identical shape to the shape of the cross section of the battery cell. For example, the lower plastic part 001 has a rectangular shape when the battery cell is a square battery cell. The lower resin part 001 has a round shape when the battery cell is a cylindrical battery cell.In this embodiment, by providing an escape groove 1111 aon the circumferential line of the first surface 111, a clearance is provided between the lower resin part 001 and the upper cover 002 at the circumferential edge, so that a space for axially deforming the circumferential edge of the lower resin part 001 is provided. When the end cover arrangement is pressed into the housing, the lower plastic part 001 therefore exerts an axial pressure on the electrode arrangement. Due to this axial pressure, the electrode arrangement generates an axial counterforce on the lower plastic part, whereby the edge circumference of the lower plastic part 001 presses against the deflection groove 1111 a, so that the radial deformation of the lower plastic part 001 and thus the pressure of the lower plastic part 001 upon entering the housing against the housing opening can be reduced, which can finally improve the deformation of the housing opening and promote the welding of the housing to the upper cover 002.In addition, the lower plastic part 001 deforms again when the lower plastic part 001 is fully assembled and remains in contact with the inner wall of the housing in order to seal the interior of the housing. In this case, the lower plastic part 001 is arranged offset with respect to the housing opening in the axial direction of the battery cell. Therefore, the assembled lower plastic part 001 does not compress the housing opening. In addition, in the assembled lower resin part 001, a gap is provided between the peripheral edge of the escape groove 1111 aon the first surface 111 and a welding surface of the upper cover 002, so that the influence of the high temperature when the upper cover 002 is welded to the housing on the lower resin part 001 can be reduced.Referring to FIG. 14, the escape groove 1111 ais optionally an annular groove. It is to be understood that the escape groove 1111 ais an annular groove that extends 360° along the circumferential line of the first surface 111. For example, the escape groove 1111 ais provided coaxially with the lower plastic part 001.In this embodiment, by forming the escape groove 1111a as an annular groove, the electrode assembly generates an axial reaction force on the lower resin part when the end cap assembly is pressed into the housing, whereby the peripheral periphery of the lower resin part 001 can press the escape groove 1111a, so that the radial deformation of the entire lower resin part 001 and thus the pressure of the lower resin part 001 when entering the housing against the housing opening can be reduced. This makes it possible to further improve the deformation of the housing opening.In addition, a gap is provided between the entire peripheral edge of the escape groove 1111 aon the first surface 111 and an entire welding surface of the upper cover 002, so that the influence of the high temperature when welding the upper cover 002 to the housing on the lower resin part 001 can be further improved.Referring to FIG. 15, it is further provided that the escape groove 1111 aincludes a first groove wall and a second groove wall. The first groove wall is connected to the first surface 111 on one side and to a second groove wall side on the other side, and the second groove wall is connected to an outer circumferential surface of the main body 011 on the other side. At least one of the following connection points is rounded: a connection point between the first surface and the first groove wall, a connection point between the first groove wall and the second groove wall, and a connection point between the second groove wall and the outer circumferential surface of the base body. It is to be understood that the escape groove 1111 ais a V-shaped groove. For example, the first groove wall is perpendicular to the second groove wall. The first groove wall has a cylindrical arcuate surface whose axis is collinear with the axis of the lower plastic part 001. The axis of the lower plastic part 001 is perpendicular to the second groove wall. In addition, all three aforementioned connection points are rounded.By the above-mentioned arrangement in this embodiment, on the one hand, a space for axially deforming the peripheral edge of the lower resin part 001 can be provided by the escape groove 1111 a. On the other hand, this allows the escape groove 1111 ato be structurally simple and easy to manufacture as a whole.In addition, when the peripheral edge of the lower plastic part 001 is axially deformed, the stress at the joints can be reduced by rounding the aforementioned joints. As a result, the tension state of the lower plastic part 001 is improved, so that the service life of the lower plastic part 001 is increased.Referring to FIG. 15, it is further provided that a first dimension of the escape groove 1111 ain a radial direction of the lower plastic part 001 is denoted by B, and where: 0<B≤2 mm.It is understood that the first dimension B may be, but is not limited to, 0.1 mm, 0.2 mm, 0.26 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.77 mm, 0.8 mm, 0.9 mm, 1 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.45 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 1.95 mm, 2 mm. Depending on different machining precisions, the first dimension B may be configured with different minimum values. For example, the minimum value of the first dimension B may be 0.05 mm when the minimum machining accuracy of the lower plastic part 001 formed by a mold is 0.05 mm. The minimum value of the first dimension B may be 0.1 mm when the minimum machining accuracy of the lower plastic part 001 formed by a mold is 0.1 mm.By defining the first dimension B in this exemplary embodiment, on the one hand, a space for the axial deformation of the circumferential edge of the lower plastic part 001 can be provided. On the other hand, the strength of the lower plastic part 001 can be ensured, thereby preventing the strength of the peripheral edge of the lower plastic part 001 from being too low due to too large a first dimension B. Thus, the lower plastic part 001 can meet the requirements of the working condition.For example, 0.1 mm≤B≤1 mm. It is also provided that 0.1 mm≤B≤0.5 mm.Referring to FIG. 15, it is further provided that a second dimension of the escape groove 1111 ain an axial direction of the lower plastic part 001 is denoted by C, and where: 0<C≤2 mm.It is to be understood that to ensure the groove structure of the escape groove 1111 a, the second dimension C is not guided by the lower plastic part 001. Depending on different dimensions of the lower plastic part 001, the second dimension C can thus be defined with different maximum values. The second dimension C may be, but is not limited to, 0.1 mm, 0.3 mm, 0.5 mm, 0.8 mm, 1.2 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 1.95 mm, 2 mm. Depending on different machining precisions, the second dimension C may be configured with different minimum values. For example, the minimum value of the second dimension C may be 0.05 mm when the minimum machining accuracy of the lower plastic part 001 formed by a mold is 0.05 mm. The minimum value of the second dimension C may be 0.1 mm when the minimum machining accuracy of the lower plastic part 001 formed by a mold is 0.1 mm. For example, 0.1 mm≤C≤1 mm.By defining the second dimension C in this embodiment, a space for axially deforming the peripheral edge of the lower resin part 001 can be provided. On the other hand, the strength of the lower plastic part 001 can be ensured, thereby preventing the strength of the peripheral edge of the lower plastic part 001 from being too low due to a second dimension C being too large. Therefore, the lower plastic part 001 satisfies the requirements of the working condition.Referring to FIG. 15, it is further provided that the second surface 112 is provided with a guide rib 115 along a peripheral edge of the main body 011, an outer peripheral surface of the guide rib 115 is a taper surface 121, and the taper surface 121 is connected to the second surface 112 at a large diameter end.It is to be understood that when the end cap assembly is pressed into the housing, a small diameter end of the cone surface 121 faces the interior of the battery cell.In addition, the distance between the first surface 111 and the second surface 112 is denoted by D, and C≤D holds.In this embodiment, by providing the guide rib 115 whose outer peripheral surface is formed as the taper surface 121, the end cap assembly can be guided by the taper surface 121 of the guide rib 115 when entering the housing. In addition, a gap may also be formed between the cone surface 121 and the inner wall of the housing, so that a space for radially deforming the guide rib 115 is provided, thereby preventing the guide rib 115 from compressing the housing opening.With reference to FIG. 15, it is further provided that the angle of inclination of the conical surface 121 is denoted by E, and wherein: 5°≤E≤ 60°.It is understood that the angle of inclination E may be 1°, 5°, 10°, 15°, 18°, 20°, 25°, 29°, 30°, 31°, 33.6°, 36°, 37°, 40°, 42°, 45°, 48°, 50°, 52°, 55°, 56.2°, 59°, 60°, but is not limited thereto. For example, 5°≤E≤45° applies. Furthermore, it is provided that 15°≤E≤ 30°.By defining the inclination angle E in this embodiment, a space for radially deforming the guide rib 115 can be provided to prevent the lower plastic part 001 from compressing the housing opening when abutting the electrode assembly. On the other hand, the strength of the guide rib 115 can also be secured to prevent the strength of the guide rib 115 from being too low due to an inclination angle E being too large. Thus, the lower plastic part 001 can meet the requirements of the working condition.With reference to FIG. 15, it is also provided that a groove wall of the avoidance groove 1111 ais formed at least partially at an end of the guide rib 115 facing the base body 011.In this embodiment, by forming the groove wall of the escape groove 1111 apartite by the guide rib 115, the thickness at the circumferential line of the lower resin part 001 can be reduced, thereby decreasing the strength at the circumferential line. When the end cover arrangement is pressed into the housing, the compression of the edge circumference of the lower plastic part 001 against the escape groove 1111 ais therefore facilitated.Furthermore, it is provided that the second surface 112 is coplanar with an end of the guide rib 115 facing the base body 011.It is to be understood that the second side wall is formed on the guide rib 115.Because, in this exemplary embodiment, the second surface 112 is coplanar with the end of the guide rib 115 facing the base body 011, the lower plastic part 001 is structurally simple and easy to produce.With reference to FIG. 16, it is further provided that the second surface 112 is provided with a plurality of stiffening ribs 113. The stiffening ribs 113 and the base body 011 are formed in one piece, for example formed in one piece by means of injection molding. Four stiffening ribs 113 are provided and they are spaced apart along the peripheral edge of the lower plastic part 001. In particular, the stiffening rib 113 comprises a first rib 1131 and a second rib 1132. The first rib 1131 is disposed to extend in the radial direction of the lower resin part 001. The second rib 1132 is an arc-shaped rib. An inner concave surface of the second rib faces the axial direction of the lower resin part 001. An outer convex surface of the second rib is connected to an end of the first rib 1131 facing the axis of the lower resin part 001.By providing the stiffening ribs 113 in this embodiment, the lower plastic part 001 can be stiffened in the radial direction and circumferential direction, so that the overall strength of the lower plastic part 001 is increased. In addition, due to the provision of the stiffening ribs 113, the elasticity of the lower plastic part 001 can be increased, so that it is more elastic for the stop on the electrode arrangement in order to restrict the movement of the electrode arrangement. In this case, the stiffening ribs 113 are not connected to one another in a planar manner in order to avoid the formation of a semi-closed structure, with the result that the electrolyte can flow smoothly therefrom after entry between the stiffening ribs 113 without impairing the flow of the electrolyte.In the lower plastic part 001 provided in this embodiment, the usual structures are the same as those in the embodiment I and are not repeated any more.Accordingly, referring to FIGS. 17 and 18, in an embodiment of the present application, there is further provided an end cap assembly including: an upper cap 002, an upper plastic part 003, a terminal 004, a pole terminal 005, and an aforementioned lower plastic part 001, the first surface 111 being in contact with one side of the upper cap 002; the upper plastic part 003 being in contact with the other side of the upper cap 002; the terminal 004 being located on a side of the upper plastic part 003 facing away from the upper cap 002; and an end of the pole terminal 005 being passed through the lower plastic part 001, the upper cap 002, and the upper plastic part 003 one after the other, and thereafter being connected to the terminal 004, and in particular, an end of the pole terminal 005 being inserted into the terminal 004.It will be understood that the bore in the terminal 004 used to insert the pole terminal 005 is a stepped bore, with a large diameter bore portion of the stepped bore on a side of the terminal 004 remote from the top cover 002. The pole terminal 005 is a stepped shaft, a large-diameter shaft portion is located on a side of the lower resin part 001 facing away from the upper cover 002, and one end of a small-diameter shaft portion is passed through the lower resin part 001, the upper cover 002, the upper resin part 003, and the stepped bore in sequence. The small diameter shaft portion is pushed down, whereby the small diameter shaft portion extends in a radial direction toward the bore wall of the large diameter bore portion, so that the pole terminal 005 abuts against the bore bottom of the large diameter bore portion. Thus, the lower plastic part 001, the upper cover 002, the upper plastic part 003 and the terminal 004 are riveted as one piece by the pole terminal 005. In addition, a sealing ring 006 is provided between the pole terminal 005 and the upper cover 002.In this embodiment, when the end cap assembly is pressed into the housing, the lower plastic part 001 compresses the electrode assembly and is subjected to a reaction force from the electrode assembly, so that the lower plastic part 001 is subjected to an axial pressure, whereby the peripheral edge of the lower plastic part 001 deforms toward the escape groove 1111 a, i.e., the radial expansion of the compressed lower plastic part 001 is converted into an axial deformation. Therefore, the end cap assembly can be prevented from compressing the housing opening upon entering the housing, thereby promoting smooth performance of welding the housing to the top cap 002.With reference to FIGS. 18 and 19, it is further provided that the upper cover 002 has a mounting surface 021, wherein the distance between the mounting surface 021 and the outer circumferential surface of the lower plastic part 001 is denoted by L, and wherein 0≤L≤3 mm.It is to be understood that the mounting surface 021 is a surface on the top cover 002 that circumferentially abuts on the inner wall of the housing. The distance L may be, but is not limited to, 0.1 mm, 0.3 mm, 0.4 mm, 0.46 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.94 mm, 1 mm, 1.1 mm, 1.2 mm, 1.26 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.62 mm, 1.7 mm, 1.85 mm, 1.9 mm, 2 mm, 2.2 mm, 2.5 mm, 2.61 mm, 2.7 mm, 2.8 mm, 2.9 mm, 3 mm.By defining the distance L in this exemplary embodiment, it is possible to avoid the electrode arrangement being in contact with the upper cover 002 owing to an excessively large distance L, as a result of which the operating stability of the battery cell can be ensured.In addition, in conjunction with the above description, it should be understood that when the end cap assembly is pressed into the housing, the lower plastic portion 001 compresses the electrode assembly and the electrode assembly applies a counterforce to the lower plastic portion 001. Since the first surface 111 is provided with the escape groove 1111 a, the peripheral edge of the lower resin part 001 deforms toward the escape groove 1111 a due to the reaction force applied from the electrode assembly to the lower resin part 001, whereby the lower resin part 001 can be prevented from being subjected to radial expansion due to the compression, and thus the lower resin part 001 can be prevented from compressing the housing opening. From this, when the lower resin part 001 is provided with the escape groove 1111 a, the deformation of the peripheral edge of the lower resin part 001 is a deformation toward the escape groove 1111 a, and the housing opening is not compressed. Thus, the outer diameter of the lower plastic part 001 can be equal to the diameter of the mounting surface 021, i.e. the outer diameter of the lower plastic part 001 can be equal to the inner diameter of the housing opening. The distance L between the mounting surface 021 and the outer circumferential surface of the lower plastic part 001 can thus be 0.To further reduce the compression of the housing opening, 0.1 mm≤L≤2 mm, for example, applies. It is also provided that 0.2≤L≤1 mm applies. Optionally, L=0.4 mm.It is also provided that the tolerance of coaxiality between the lower plastic part 001 and the upper cover 002 is denoted by A, and wherein the following applies: A≤L≤3 mm.For example, the tolerance of coaxiality is 0≤A≤0.3 mm. The tolerance of the coaxiality A may be, but is not limited to, 0.1 mm, 0.2 mm, 0.3 mm. It is 0.3 mm ≤ L ≤ 3 mm when A = 0.3 mm.In this embodiment, by defining the distance L between the lower plastic part 001 and the upper cover 002 by the tolerance of the coaxiality A between the lower plastic part 001 and the upper cover 002, when the axial offset between the lower plastic part 001 and the upper cover 002 is maximally spaced (the maximum distance of the axial offset being A), it is possible to prevent the outer periphery of the lower plastic part 001 from protruding from the mounting surface 021 of the upper cover 002, thereby improving the compression of the plastic part against the housing opening when the end cover assembly is pressed into the housing.Accordingly, in one embodiment, a battery cell is further provided that includes an end cap assembly as mentioned above. For example, the battery cell is a cylindrical battery cell. It is understood that the battery cell further comprises a case, a sub-lid assembly, an electrode assembly, a positive current collector plate, and a negative current collector plate, wherein the case has a first opening and a second opening arranged facing away from each other, and wherein the end lid assembly is provided covering the first opening and the sub-lid assembly is provided covering the second opening. The electrode assembly is disposed within the housing. A positive tab of the electrode assembly is connected to a positive pole terminal 005 of the top cover assembly 002 through the positive current collector plate, and the negative tab of the electrode assembly is connected to the bottom cover assembly through the negative current collector plate.

Claims

A lower plastic part used for a battery cell having an upper lid, the lower plastic part comprising: a base body having a first surface and a second surface arranged facing away from each other, wherein the first surface (111) is a flat surface and abuts against the upper lid (002).The lower plastic part of claim 1, wherein the base body (011) is provided with a through hole (117) through the first surface (111) and the second surface (112).The lower plastic part according to claim 2, wherein the lower plastic part further comprises a first adhesive layer (012), wherein the first adhesive layer (012) is provided around a peripheral edge of the through hole (117) on a side where the first surface (111) is located, and wherein the first adhesive layer (012) is configured to be bonded to the top cover (002) and the base body (011) on both sides, respectively.The lower plastic part of claim 3, wherein the first surface (111) is provided with a first annular groove (1111) around the through hole (117), wherein the first adhesive layer (012) is provided in the first annular groove (1111), and wherein a side of the first adhesive layer (012) facing away from the second surface (112) is coplanar with the first surface (111).The lower plastic part according to claim 4, wherein the first annular groove (1111) has one of semicircular shape, V shape, U shape, and rectangular shape in cross section in a thickness direction of the lower plastic part.The lower plastic part of claim 4 or 5, wherein a distance between the first surface (111) and the second surface (112) is denoted by D and a depth of the first annular groove (1111) is denoted by d 1 and wherein: 10%D ≤ d 1 ≤ 50%D.The lower plastic part according to any one of claims 4 to 6, wherein a diameter of the lower plastic part is denoted as D 0 and a width dimension of the first annular groove (1111) in a radial direction of the lower plastic part is denoted as W 1 and wherein 1.5%D 0 ≤ W 1 ≤ 6.5%D 0.The lower plastic part according to any one of claims 4 to 7, wherein a distance between an inner circumferential edge of the first annular groove (1111) and a circumferential edge of the through hole (117) surrounded by it is denoted as S, and wherein: 1 mm ≤ S ≤ 5 mm.The lower plastic part according to any one of claims 1 to 8, wherein the lower plastic part further comprises a second adhesive layer (013), wherein the second adhesive layer (013) is provided around an edge periphery of the first surface (111), and wherein the second adhesive layer (013) is configured to be bonded to the top cover (002) and the base body (011), respectively, on both sides.The lower plastic part according to claim 9, wherein the first surface (111) is provided with a second annular groove (1112) at the edge periphery, wherein the second adhesive layer (013) is provided in the second annular groove (1112), and wherein a side of the second adhesive layer (013) facing away from the second surface (112) is coplanar with the first surface (111).The lower plastic part according to claim 10, wherein the second annular groove (1112) has one of semicircular shapes, V shapes, U shapes, and rectangular shapes in cross section in a thickness direction of the lower plastic part.The lower plastic part of claim 10 or 11, wherein a distance between the first surface (111) and the second surface (112) is denoted D and a depth of the second annular groove (1112) is denoted d 2 and wherein: 10%D ≤ d 2 ≤ 50%D.The lower plastic part of any one of claims 10 to 12, wherein a diameter of the lower plastic part is denoted as D 0 and a width dimension of the second annular groove (1112) in a radial direction of the lower plastic part is denoted as W 2 and wherein 1.5%D 0 ≤ W 2 ≤ 6.5%D 0.The lower plastic part according to any one of claims 1 to 13, wherein the second surface (112) is provided with a positioning rib (114), the positioning rib (114) being provided to be locked to a current collector plate of the battery cell.The lower plastic part according to any one of claims 1 to 14, wherein an escape groove (1111a) is provided on a perimeter of the first surface (111), and wherein the escape groove (1111a) extends at least along a part of the perimeter of the first surface (111).The lower plastic part of claim 15, wherein the escape groove (1111a) is an annular groove.The lower plastic part according to claim 15 or 16, wherein the escape groove (1111a) comprises a first groove wall and a second groove wall, wherein the first groove wall is connected on one side to the first surface (111) and on the other side to one side of the second groove wall, and wherein the second groove wall is connected on the other side to an outer circumferential surface of the base body (011).The lower plastic part of claim 17, wherein at least one of the following joints is rounded: a joint between the first surface (111) and the first groove wall, a joint between the first groove wall and the second groove wall, and a joint between the second groove wall and the outer circumferential surface of the base body (011).The lower plastic part according to any one of claims 15 to 18, wherein a first dimension of the escape groove (1111a) in the radial direction of the lower plastic part is denoted by B, and wherein: 0 < B ≤ 2 mm.The lower plastic part according to any one of claims 15 to 19, wherein a second dimension of the escape groove (1111a) in an axial direction of the lower plastic part is denoted as C, and wherein: 0 < C ≤ 2 mm.The lower plastic part according to any one of claims 15 to 20, wherein the second surface (112) is provided with a guide rib (115) along a peripheral edge of the base body (011), wherein an outer peripheral surface of the guide rib (115) is a taper surface (121), and wherein the taper surface (121) is connected to the second surface (112) at a large diameter end.The lower plastic part according to claim 21, wherein an inclination angle of the cone surface (121) is denoted as E, and wherein: 5° ≤ E ≤ 60°.Lower plastic part according to claim 21 or 22, wherein a groove wall of the deflection groove (1111a) is formed at least partially at an end of the guide rib (115) facing the base body (011).The lower plastic part of claim 23, wherein the second surface (112) is coplanar with an end of the guide rib (115) facing the base body (011).The lower plastic part according to any one of claims 1 to 24, wherein the second surface (112) is provided with a plurality of stiffening ribs (113).The lower plastic part of claim 25, wherein the plurality of stiffening ribs (113) are spaced along a peripheral edge of the lower plastic part.The lower plastic part according to claim 25 or 26, wherein the stiffening rib (113) comprises a first rib (1131) and a second rib (1132); the first rib (1131) is arranged to extend in the radial direction of the lower plastic part; and the second rib (1132) is an arc-shaped rib, wherein an inner concave surface of the second rib (1132) faces the axial direction of the lower plastic part, and wherein an outer convex surface of the second rib (1132) is connected to an end of the first rib (1131) facing the axial direction of the lower plastic part.An end cap assembly comprising an upper cap (002), an upper plastic part (003), a clamp (004), a pole clamp (005), and a lower plastic part according to any one of claims 1 to 27, wherein the first surface (111) is in contact with one side of the upper cap (002); the upper plastic part (003) is in contact with the other side of the upper cap (002); the clamp (004) is on a side of the upper plastic part (003) facing away from the upper cap (002); and an end of the pole clamp (005) is passed through the lower plastic part, the upper cap (002), and the upper plastic part (003) in sequence and is thereafter connected to the clamp (004).The end cap assembly of claim 28, wherein the top cap (002) has a mounting surface (021), wherein a distance between the mounting surface (021) and the outer circumferential surface of the lower plastic part is denoted as L, and wherein 0 ≤ L ≤ 3 mm.The end cap assembly of claim 29, wherein a tolerance of coaxiality between the lower plastic part and the top cap (002) is denoted A, and wherein: A ≤ L ≤ 3 mm.The end cap assembly of claim 30, wherein the tolerance of coaxiality A is 0 ≤ A ≤ 0.3 mm.A battery cell comprising an end cap assembly according to any of claims 28 to 31.

Images