Secondary battery and battery module with such a battery

Abstract

Secondary battery (10) comprising: a cell body element (12) in which an electrode assembly (11) is housed and which is provided adjacent to a cooling plate element (21); and a thermally conductive element (30) which is provided in at least one section between the cell body element (12) and the cooling plate element (21) to form a heat path for transferring heat from the cell body element (12) to the cooling plate element (21), wherein the cell body element (12), which is in contact with the thermally conductive element (30) via a lower surface, has an area-enlarging groove (13) which is designed to be concave in the lower surface, characterized in that the area-enlarging groove (13) is asymmetrically designed.

Description

BACKGROUND AREA OF TECHNOLOGY The present invention relates to a secondary battery according to the preamble of claim 1 and a battery module containing the same. STATE OF THE ART With the increasing demand for mobile devices, electric vehicles, and the like, as well as the development of related technologies, the demand for secondary batteries as energy sources has risen rapidly. A secondary battery can be repeatedly charged and discharged because the conversion between chemical and electrical energy within it is reversible. A cell body element of a secondary battery refers to a laminated foil casing that protects an electrode assembly consisting of the anode, cathode, separator film, and electrolyte solution, which are the main components of a secondary battery. However, such an electrode assembly generates heat during the charging and discharging process, and a temperature increase due to the generated heat degrades the performance of the secondary battery. Accordingly, the cell body element in which the electrode assembly is housed is configured such that a cooling plate element for cooling, a heat sink and the like are connected to it. In particular, in the case of a secondary battery, where the cell body element has three sealing surfaces, a lower surface, the cooling plate element and a heat sink are associated with it. To improve the cooling efficiency of such a secondary battery, a thermally conductive element is provided between the cooling plate element and the cell body element, as disclosed in EP 3 553 843 A1. There is research on such thermally conductive elements that involves the addition of an additive or similar to improve thermal conductivity; however, there are limitations resulting from the addition of additives and the use of comparatively expensive thermally conductive materials to improve thermal conductivity. Another problem is that there is a limit to the increase in thermal conductivity, which results from the properties of the additives and the thermally conductive element. Therefore, the object of the invention is to solve the above-mentioned problems and limitations with regard to a secondary battery and a battery module that includes it. SUMMARY OF THE INVENTION In one aspect of the present invention, this problem is solved by providing a secondary battery that is able to overcome a limitation of the improvement in thermal conductivity due to the properties of a thermally conductive element, and a battery module that contains this. In another aspect of the present invention, this problem is solved by providing a secondary battery that is able to improve thermal conductivity while simultaneously reducing the use of a thermally conductive element, as well as a battery module that contains the same. According to one embodiment of the present invention, a secondary battery comprises a cell body element which accommodates an electrode assembly and is provided adjacent to a cooling plate element; and a thermally conductive element which is provided in at least one section between the cell body element and the cooling plate element to form a heat path for transferring heat from the cell body element to the cooling plate element, wherein the cell body element which is in contact with the thermally conductive element on a lower surface thereof has an area-enlarging groove which is designed to be concave in the lower surface, wherein the area-enlarging groove is designed asymmetrically. Additionally, the area-enlarging groove of the secondary battery can be asymmetrical in the direction of the thickness of the cell body element, according to an exemplary embodiment. The area-enlarging groove of the secondary battery according to an exemplary embodiment has one side that is designed to have a first radius of curvature in the thickness direction of the cell body element, and the other, connected side that is designed to have a second radius of curvature, wherein the first and the second radius of curvature are different from each other. Furthermore, according to an exemplary embodiment, the cell body element of the secondary battery can be shaped such that the area-enlarging groove is formed in a central section in the thickness direction in order to be extended in a longitudinal direction. The cell body element of the secondary battery, according to an exemplary embodiment, can be shaped such that the area-enlarging groove in the middle part is formed in the direction of the thickness and a rounded part is formed at both ends in the direction of the thickness. In this case, according to an exemplary embodiment, the cell body element of the secondary battery can have a rounded section with a radius of curvature that is smaller than the radius of curvature of the area-enlarging groove. According to another embodiment of the present invention, a battery module comprises a secondary battery containing a cell body element that accommodates an electrode assembly therein, and a thermally conductive element that is provided in at least one section between the cell body element and a cooling plate element, and a housing element that has the cooling plate element for heat exchange with the cell body element, mediated by the thermally conductive element, and which accommodates a plurality of the secondary batteries, wherein the cell body element has an area-enlarging groove that is configured to be concave on a lower surface thereof in contact with the thermally conductive element, wherein the area-enlarging groove is configured asymmetrically. Furthermore, according to another exemplary embodiment, the area-enlarging groove can have one side designed to have a first radius of curvature in the thickness direction of the cell body element, and the other, connected side designed to have a second radius of curvature, wherein the first and second radii of curvature are different from each other. When the cell body element is placed on and connected to the heat-conducting element applied to the cooling plate element, the area-enlarging groove can, according to another exemplary embodiment, have a first radius of curvature of one side that is initially in contact with the heat-conducting element applied to the cooling plate element that is larger than the second radius of curvature. In this case, the cell body element can be formed according to another exemplary embodiment with the area-enlarging groove in the middle section of a thickness direction and a rounded section at both ends in the thickness direction, wherein a radius of curvature of the rounded section is smaller than a radius of curvature of the area-enlarging groove. In the cell body element according to another exemplary embodiment, the area-enlarging groove can be formed in a central section in one thickness direction to accommodate the heat-conducting element, and at both ends in the thickness direction to be in contact with the cooling plate element. The cooling plate element according to another exemplary embodiment can have an area-enlarging strip shaped to protrude from a section in which the cell body element sits, and has at least one section that is inserted into the area-enlarging groove. In particular, the area-enlarging strip can be shaped according to another exemplary embodiment in such a way that it protrudes in such a way that it corresponds to a shape of the area-enlarging groove. Furthermore, according to another exemplary embodiment, the area-enlarging strip can be shaped such that it has a width that is smaller than the width of the area-enlarging groove in the direction of the thickness of the cell body element. BRIEF DESCRIPTION OF THE DRAWINGS The above and other aspects, features, and advantages of the present disclosure are more clearly understood in the following detailed description, which is included in conjunction with the accompanying drawings: Fig. 1 is a front view of a secondary battery of the present disclosure; Fig. 2 is a perspective view of a secondary battery of the present disclosure; Figs. 3A and 3B are a front view of a non-inventive embodiment in which an area-enlarging groove of a cell body in a secondary battery is symmetrically formed; Figs. 4A to 4C are a front view of an embodiment of the invention in which an area-enlarging groove of a cell body element in a secondary battery of the present disclosure is asymmetrically formed; Figs. 5A and 6B are a front view of a cell body element of the present disclosure.Figure 5B is a front view of a rounded section shaped to have a smaller radius of curvature than a groove for increasing the surface area in a cell body of a secondary battery; Figure 6 is a front view of a secondary battery of the present disclosure and of a battery module containing it; Figure 7 is a perspective view of a disassembled battery module of the present disclosure; Figure 8 is a front view of a disassembled battery module of the present disclosure; and Figure 9 is a front view of a battery module in which the area-enlarging cone is formed in a cooling plate part of a housing element. DETAILED DESCRIPTION The following are exemplary embodiments of the present disclosure described with reference to the accompanying drawings. The present disclosure is not limited to exemplary embodiments, and it should be understood that modifications may be made without departing from the scope of the present invention as defined by the pending claims. The shapes and sizes of the elements in the drawings may be exaggerated for the sake of clarity of description. Furthermore, an expression used in the singular also includes the plural form, unless it has a clearly different meaning in the context. Identical or corresponding elements receive the same reference numbers. The present disclosure relates to a secondary battery 10 and a battery module containing it, which can overcome a limitation in improving thermal conductivity resulting from the properties of a thermally conductive element 30, while another aspect was improving thermal conductivity as well as reducing the use of the thermally conductive element 30. Accordingly, the secondary battery 10 of the present disclosure and the battery module containing it could improve thermal conductivity while simultaneously preventing a price increase. Specifically, Fig. 1 is a front view of a secondary battery of the present disclosure, and Fig. 2 is a perspective view of a secondary battery of the present disclosure. Referring to Fig. 1 and Fig. 2, a secondary battery according to an exemplary embodiment comprises a cell body element 12 in which an electrode assembly 11 is housed and which is adjacent to a cooling plate element 21; and a thermally conductive element 30, which is provided at least in a section between the cell body element 12 and the cooling plate element 21 to form a heat path for transferring heat from the cell body element 12. The cell body element 12 may have a groove 13 that increases the surface area and is configured to be concave on a lower surface thereof in contact with the thermally conductive element 30. As described above, the cell body element 12, with its surface-enhancing groove 13, can increase the contact area with the heat-conducting element 30. In this context, a heat path between the cooling plate element 21 can be extended, thereby increasing the thermal conductivity. Accordingly, the secondary battery 10 of the present disclosure can overcome a limitation of the improvement in thermal conductivity resulting from the properties of the thermally conductive element 30. In this case, the cell body element 12 is provided with an electrode assembly 11 located therein, which serves to protect the electrode assembly 11. That is, the cell body element 12 can be proposed to provide an interior space for receiving the electrode assembly 11, which consists of an anode, a cathode, a separating film, an electrolyte solution and the like, followed by a seal. As an example, the cell body element 12 can be provided as a pocket-like element or as a barrel-like element. The pocket-like element is a shape in which the electrode assembly 11 is housed on three surfaces; that is, an element configured such that the electrode assembly 11, while housed inside, overlaps and adheres to the three surfaces of a top surface and both side surfaces, largely excluding a bottom surface. The barrel-like element has a shape in which the electrode assembly 11 is sealed and housed on one surface; that is,an element configured such that it is mainly in the form in which the electrode assembly 11, while housed inside, overlaps and adheres to one surface, with the three surfaces of the bottom surface and the two side surfaces being substantially excluded. The cell body element 12 can increase the contact area with the heat-conducting element 30 by means of an area-enlarging groove 13, which is concave on a lower surface in contact with the heat-conducting element 30, and such heat path expansion can lead to improved thermal conductivity. As an example, the area-enlarging groove 13 can be provided in a central section of the lower surface of the cell body element 12 in a thickness direction X and can also have a shape extended in a longitudinal direction Z of the cell body element 12. This means that the cell body element 12 of a secondary battery 10 according to an exemplary embodiment can have the area-enlarging groove 13, which is formed in the central section in the thickness direction X, in a form extended in the longitudinal direction Z. As above, the thermal conductivity in the longitudinal direction Z of the cell body element 12 can be uniformly increased if the area-enlarging groove 13 is designed so that it extends in the longitudinal direction Z of the cell body element 12. In addition to the area-enlarging groove 13 formed in the middle part of the lower surface, the cell body element 12 can have a rounded section 14 formed at both ends in the thickness direction X to increase the contact area with the heat-conducting element 30, which is described in detail with reference to Fig. 5A and Fig. 5B. The cell body element 12 is provided with the area-enlarging groove 13, which is asymmetrically designed, thereby preventing the formation of an air gap when coupling to the heat-conducting element 30, which is described in detail with reference to Fig. 2 and Fig. 3. In this case, the electrode assembly 11, as a secondary battery 10, is a battery capable of repeated charging and discharging due to the reversible conversion between chemical and electrical energy. Any conventionally used secondary battery 10 can be configured as an electrode assembly 11 without restrictions. For example, the electrode assembly 11 can be configured such that a cathode and an anode are stacked crosswise on top of each other, with the surfaces coated with the respective electrode-active materials facing each other, while a separating film acts as a boundary between them. Meanwhile, the electrode assembly 11 essentially contains an electrolyte solution and is incorporated into the cell body element 12 to be used. The electrolyte solution can contain an organic solvent such as ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), or the like, together with a lithium salt such as LiPF6, LiBF4, or the like. Furthermore, the electrolyte solution can be liquid, solid, or gel-like. The cooling plate element 21 serves to release heat generated in the electrode assembly 11 housed in the cell body element 12. For this purpose, the cooling plate element 21 can absorb the heat transmitted from the cell body element 12 by the thermally conductive element 30 or the like and transfer the heat to an external heat sink or the like, thereby coming into contact with the external heat sink, so that the cell body element 12, in which the electrode assembly 11 is housed, is cooled. The thermally conductive element 30 serves to dissipate the heat generated during the charging and discharging of the electrode assembly 11. For this purpose, the thermally conductive element 30 can be positioned between the cell body element 12, in which the electrode assembly 11 is housed, and the cooling plate element 21, in contact with the heat sink. For this purpose, the heat-conducting element 30 can be formed, for example, by having the cell body element 12 seated while being applied to the cooling plate element 21, and by filling the heat-conducting element 30 into the area-enlarging groove 13 formed on the lower surface of the cell body element 12, thereby providing it between the cooling plate element 21 and the cell body element 12 in such a way that it has a shape corresponding to the shape of the area-enlarging groove 13. Although not limited to this, the thermally conductive element 30 can be provided as a thermally conductive adhesive, a thermally conductive substrate or the like. Figs. 3A and 3B are a front view of a non-inventive embodiment in which an area-enlarging groove of a cell body element in a secondary battery of the present disclosure is symmetrically formed, and Figs. 4A to 4C are a front view of an embodiment according to the invention in which an area-enlarging groove of a cell body element in a secondary battery of the present disclosure is asymmetrically formed. Based on Fig. 3 and Fig. 4, a cell body element 12 of a secondary battery 10 can, according to an exemplary embodiment, have an asymmetrical, area-enlarging groove 13. This means that the cell body element 12 of the present disclosure can prevent an air gap from being formed when coupling to the heat-conducting element 30 due to the asymmetrically designed, area-enlarging groove 13. This can be easily understood by comparing Fig. 3A and Fig. 3B, which illustrate a non-inventive embodiment in which the area-enlarging groove 13 is symmetrical to Fig. 4A to 4C, and which illustrate that the area-enlarging groove 13 is asymmetrical according to the invention. In other words, if a radius of curvature of the non-inventive symmetrical area-enlarging groove 13, as shown in Fig. 3A, is larger than that of the heat-conducting element 30, which is applied to the cooling plate element 12 before it comes into contact, an initial form in which the heat-conducting element 30 is in contact with the area-enlarging groove 13 comprises an air gap between the area-enlarging groove 13 and an upper section of the heat-conducting element 30. Even if the cell body element 12 is completely seated in the cooling plate element 21 while maintaining the condition described above, a problem may occur, as shown in Fig. 3B, because a condition is maintained in which an air gap is formed between the area-enlarging groove 13 and the heat-conducting element 30. Furthermore, a problem can arise in this case if part of the heat-conducting element 30, which is not filled into the air gap, deviates towards an outside of the area-enlarging groove 13. However, if the area-enlarging groove 13 is designed asymmetrically according to the invention, such problems can be avoided. That is, as shown in Fig. 4A, if the groove 13 for increasing the surface area is designed asymmetrically according to the invention, the cell body element 12 can be fully inserted into the cooling plate element 21 without forming an air gap between the groove 13 for increasing the surface area and the heat-conducting element 30, regardless of the shape of the heat-conducting element 30 that is applied to the cooling plate element 21. In other words, when the cell body element 12 is in contact with the thermally conductive element 30, which is applied to the cooling plate element 21, and compresses the thermally conductive element 30, thus diffusing it, the thermally conductive element 30 can diffuse through the asymmetrical, area-enlarging groove 13 according to the invention, as shown in Fig. 4B. In this way, the thermally conductive element 30 and the area-enlarging groove 13 can be bonded tightly together so that no air gap is formed, as shown in Fig. 4C. More precisely, such an asymmetrical area-enlarging groove 13 can be asymmetrical in the longitudinal direction Z of the cell body element 12, but is preferably asymmetrical in the thickness direction X of the cell body element 12. In general, this means that since the cell body element 12 is longer in the longitudinal direction Z than in the thickness direction X, which facilitates the formation of an air gap in the thickness direction X of the cell body element 12, the asymmetric, area-enlarging groove 13 is formed in the thickness direction of the cell body element 12. In other words, the area-enlarging groove 13 of the secondary battery 10 according to an exemplary embodiment is asymmetrically formed in the thickness direction X of the cell body element 12. The area-enlarging groove 13, which has such an asymmetrical shape, is a specific embodiment and can be limited as described below. That is, the area-enlarging groove 13 of the secondary battery 10 according to an exemplary embodiment can have one side with a first radius of curvature Rc1 in the thickness direction X of the cell body element 12 and the associated other side with a second radius of curvature Rc2, wherein the first and the second radius of curvature Rc1 and Rc2 are different from each other to form the asymmetric shape. This is because, when the heat-conducting element 30 is in contact with the area-enlarging groove 13 in order to diffuse, a space that allows air to flow out between the heat-conducting element 30 and the area-enlarging groove 13 can be easily secured due to an initial contact with a section that has a comparatively larger radius of curvature. Figures 5A and 5B show a front view of a rounded section 14, which is shaped to have a smaller radius of curvature than the area-enlarging groove 13 in a cell body element 12 of a secondary battery 10. Referring to Figures 5A and 5B, the cell body element 12 of a secondary battery 10, according to an exemplary embodiment, has the area-enlarging groove 13 formed in a central section in the direction of the thickness, and a rounded section 14 formed at both ends in the direction of the thickness X. As mentioned above, the cell body element 12 can have a larger contact area with the heat-conducting element 30 by having the rounded section 14 in a round shape formed at both ends in the thickness direction X in addition to the area-enlarging groove 13 formed in the middle section of the lower surface. That is, the rounded section 14 is further developed in addition to the area-enlarging groove 13 in order to increase an effective area for forming a heat transfer path by contact with the heat-conducting element 30 on the lower surface of the cell body element 12. In this case, a radius of curvature Re of the rounded section 14, which has a round shape, can be set. This means that the cell body element 12 of a secondary battery 10, according to an exemplary embodiment, can have a radius of curvature Re of the rounded section 14 smaller than a radius of curvature Rc of the area-enlarging groove 13. As described above, the problem that the heat-conducting element 30 deviates towards an outside of the lower surface of the cell body element 12 can be solved by increasing the contact area with the heat-conducting element 30 due to the rounded section 14 and by ensuring that the radius of curvature Re of the rounded section 14 is smaller than the radius of curvature Rc of the area-enlarging groove 13. In other words, when the cell body element 12 is inserted into the heat-conducting element 30 after the heat-conducting element 30 has been applied to the cooling plate element 21, the heat-conducting element 30 extends in the direction of the rounded section 14 while being received in the area-enlarging groove 13 formed in the central section of the cell body element 12. Since the radius of curvature Re of the rounded section 14 is smaller than the radius of curvature Rc of the area-enlarging groove 13, an air gap between the rounded section 14 and the cooling plate element 21 is arranged such that it is smaller than a gap between the area-enlarging groove 13 and the cooling plate element 21. In this respect, a space is reduced which allows the heat-conducting element 30 to be directed towards an outside of the rounded section 14, and consequently an amount of the heat-conducting element 30 which deviates towards the outside of the lower surface of the cell body element 12 is reduced. Fig. 6 is a front view of a secondary battery of the present disclosure and of a battery module containing it, and Fig. 7 is a perspective view of a disassembly of a battery module of the present disclosure. Based on Fig. 6 and Fig. 7, a battery module according to another example, which embodies the present disclosure, comprises a cell body element 12 in which an electrode assembly is housed, and a thermally conductive element 30, which is provided at least in a section between the cell body element 12 and a cooling plate element; and a housing element 20, which includes the cooling plate element 21 for heat exchange with the cell body element 12, mediated by the thermally conductive element 30, and which accommodates a plurality of the secondary batteries 10, wherein the cell body element 12 may include the area-enlarging groove 13, which is configured to be concave on a lower surface thereof in contact with the thermally conductive element 30. As mentioned above, the cell body element 12 with the area-enlarging groove 13 can serve to increase the contact area with the heat-conducting element 30. In this context, a heat path between the cooling plate element 21 is enlarged, thereby improving the thermal conductivity of the secondary battery 10. Accordingly, the battery module including the secondary battery 10 of the present disclosure can overcome the limitation of the improvement in thermal conductivity resulting from the properties of the thermally conductive element 30. As mentioned above, the secondary battery 10 contained in the battery module can have the properties of the secondary battery 10 described above. This means that the area-enlarging groove 13 of the battery module according to another exemplary embodiment can be asymmetrical in the thickness direction X of the cell body element 12. Furthermore, according to another exemplary embodiment, the area-enlarging groove 13 of the battery module can have one side configured to have a first radius of curvature Rc1 in the thickness direction X of the cell body element 12, and the other, connected side configured to have a second radius of curvature Rc2, wherein the first and second radii of curvature Rc1 and Rc2 are different from each other. The cell body element 12 of the battery module according to another exemplary embodiment can be formed with the area-enlarging groove 13 in the middle section of the thickness direction X and a rounded section 14 at both ends in the thickness direction X, wherein the radius of curvature Re of the rounded section 14 is smaller than the radius of curvature Rc of the area-enlarging groove 13. If the cell body element 12 sits on and is connected to the thermally conductive element 30, which is applied to the cooling plate element 21, the area-enlarging groove 13 of the battery module can also, according to another exemplary embodiment, have one side in contact with the thermally conductive element 30, which is applied to the cooling plate element 21, wherein the first radius of curvature Rc1 is larger than the second radius of curvature Rc2. That is, the first radius of curvature Rc1 of one side, part of the area-enlarging groove 13 in which the heat-conducting element 30 is first in contact, is shaped in such a way that it is larger than the second radius of curvature Rc2 of the other side, thus forming the asymmetric shape. When the heat-conducting element 30 is in contact with the area-enlarging groove 13 in order to diffuse, the heat-conducting element 30 is in first contact with the first radius of curvature Rc1, a comparatively large radius of curvature, which easily secures the space that allows air to be dissipated between the heat-conducting element 30 and the area-enlarging groove 13. In the case where several of the secondary batteries 10 are installed in the housing element 20, the thermally conductive element 30 connected to the secondary batteries is provided in the plural. In this case, an air gap is formed between adjacent thermally conductive elements 30, creating an additional air cooling effect and improving the cooling performance. For this purpose, the heat-conducting element 30 can have a cross-sectional area of ​​the cell body element 12 in the direction of the thickness that is smaller than that of the area-enlarging groove 13. This means that the volume of a hollow section formed between the groove 13 (for increasing the surface area) and the cooling plate element 21 can be larger than that of the thermally conductive element 30 applied to the cooling plate element 21. This facilitates the reduction of the thermally conductive element's volume towards the outer surface of the lower surface of the cell body element 12 when the cell body element 12 is seated within the thermally conductive element 30 applied to the cooling plate element 21, causing the thermally conductive element to expand. To improve the deviation of the heat-conducting element 30 from the outside of the lower surface of the cell body element 12, both ends of the cell body element 12 can additionally be provided in the thickness direction X so that they are in contact with the cooling plate element 21, which is described in detail with reference to Fig. 8. Due to the configuration in which several secondary batteries are installed, the housing element 20 serves to protect the secondary batteries 10, while dissipating the electrical energy generated by the secondary batteries 10 to the outside or to an external heat sink for cooling. Furthermore, a base part can be formed from the cooling plate element 21, which forms a lower part of the housing element 20. Additionally, a side wall element 23, which forms a side section of the housing element 20, can be provided at an edge of the cooling plate element 21, and the cooling plate element 21 can be shaped to extend to reach the side wall element 23. A pressure element 25 is provided in an inner side surface of the side wall element 23 to further protect the secondary batteries 10. Additionally, the housing element 20 can include a cover element 24, which is provided at an upper end of the side wall element 23 to protect an upper end of the secondary batteries 10. The housing element 20 can be provided with an additional arrangement, such as a busbar for electrical connection of the secondary battery 10 to the outside or similar. Fig. 8 is a front view of a disassembled battery module of the present disclosure. With reference to Fig. 8, the cell body element 12 of the battery module according to another exemplary embodiment has the area-enlarging groove 13, which is formed in the central part in the thickness direction X for receiving the heat-conducting element 30, and both ends in the thickness direction X are shaped such that they are in contact with the cooling plate element 21. That is, both ends of the cell body element 12 in the thickness direction are designed to be in contact with the cooling plate element 21 in order to improve the deviation of the heat-conducting element 30 towards the outside of the lower surface of the cell body element 12. In other words, the lower surface of the cell body element 12 compresses the thermally conductive element 30, which is applied to the cooling plate element 21, and the thermally conductive element 30 expands when the secondary battery 10 is installed in the housing element 20. In this case, the area over which the thermally conductive element 30 expands is limited by the arrangement of the cell body element 12. Since both ends of the cell body element 12 are located in the thickness direction X in the cooling plate element 21 in order to be in contact with it, the heat-conducting element 30 is only arranged in the hollow section formed by the area-enlarging groove 13, which is formed in the central section of the cell body element 12 in the thickness direction, an inside of both ends of the cell body element 12 in the thickness direction. In this respect, the use of the thermally conductive element 30 can be reduced, while an effective contact area between the cell body element 12 and the thermally conductive element 30 is increased or maintained. Fig. 9 is a front view of a battery module of the present disclosure, in which an area-enlarging strip is formed in a cooling plate element of a housing element. With reference to Fig. 9, the cooling plate element 21 of the battery module, according to another exemplary embodiment, can have an area-enlarging strip 22 which is shaped such that it projects from a section in which the cell body element sits, and in which at least one section is inserted into the area-enlarging groove 13. As described above, the formation of the area-enlarging strip 22 can serve to reduce the use of the heat-conducting element 30 and improve thermal conductivity. In other words, if the area-enlarging strip 22, a part of the cooling plate element 21, increases a contact area with the heat-conducting element 30, a heat path between the heat-conducting element 30 and the cooling plate element 21 can be extended, thereby improving the thermal conductivity. Since the area-enlarging strip 22 fills at least part of the hollow section formed by the area-enlarging groove 13 of the cell body element 12, the use of the heat-conducting element 30, which is arranged between the cell body element 12 and the cooling plate element 21, can be reduced. In other words, the use of the heat-conducting element 30 can be reduced by filling the hollow section that needs to be filled by the heat-conducting element 30 with the area-enlarging strip 22. Specifically, according to another exemplary embodiment, the area-enlarging strip 22 of the battery module can be shaped so that it protrudes in a form that corresponds to a form of the area-enlarging groove 13. Due to such a configuration, an air gap between the area-enlarging groove 13 and the area-enlarging strip 22 is formed uniformly in the thickness direction X of the cell body element 12, and accordingly the heat-conducting element 30 is shaped so that it has a uniform thickness in the thickness direction X of the cell body element 12, thereby generating a uniform thermal conductivity in the thickness direction X of the heat-conducting element 30. In addition, according to another exemplary embodiment, the area-enlarging strip 22 of the battery module can be shaped such that it has a small width in the thickness direction of the cell body element 12 compared to the area-enlarging groove 13. In other words, an air gap is formed between the area-enlarging strip 22 and the area-enlarging groove 13 by the fact that the cross-section of the area-enlarging strip 22 is smaller than the cross-section of the hollow section of the cell body element 12 formed by the area-enlarging groove 13 in the direction of the thickness. In this context, a space in which the heat-conducting element 30 can be provided can be fixed between the area-enlarging groove 13 of the cell body element 12 and the area-enlarging strip 22 of the cooling plate element 21. According to the aforementioned exemplary explanations, the secondary battery of the present disclosure and the battery module including the same are advantageous insofar as a limitation relevant to the improvement of thermal conductivity due to the properties of a thermally conductive element can be overcome. In another aspect, the secondary battery of the present disclosure and the battery module containing it are advantageous in that they are able to improve thermal conductivity while simultaneously reducing the use of a thermally conductive element. In this respect, the secondary battery of the present disclosure and the battery module including it have the advantage of improving thermal conductivity and avoiding increased product costs. Various advantages and beneficial effects of the present disclosure are not limited to the above descriptions and can be easily understood in the course of describing the specific embodiments of the present disclosure. While the exemplary embodiments above have been shown and described, it will be obvious to the person skilled in the art that changes and variations can be made without deviating from the scope of the present invention as defined by the attached claims.

Claims

Secondary battery (10) comprising: a cell body element (12) in which an electrode assembly (11) is housed and which is provided adjacent to a cooling plate element (21); and a thermally conductive element (30) which is provided in at least one section between the cell body element (12) and the cooling plate element (21) to form a heat path for transferring heat from the cell body element (12) to the cooling plate element (21), wherein the cell body element (12), which is in contact with the thermally conductive element (30) via a lower surface, has an area-enlarging groove (13) which is designed to be concave in the lower surface, characterized in that the area-enlarging groove (13) is asymmetrically designed. Secondary battery (10) according to claim 1, wherein the area-enlarging groove (13) is asymmetrically formed in a thickness direction (X) of the cell body element (12). Secondary battery (10) according to claim 2, wherein the area-enlarging groove (13) has a side configured to have a first radius of curvature (Rc1) in the thickness direction (X) of the cell body element (12), and another side connected thereto configured to have a second radius of curvature (Rc2), wherein the first radius of curvature (Rc1) and the second radius of curvature (Rc2) are different from each other. Secondary battery (10) according to claim 2 or 3, wherein the cell body element (12) is shaped such that the area-enlarging groove (13) is formed in a central section in the thickness direction (X) of the cell body element (12) in order to be extended in a longitudinal direction (Z). Secondary battery (10) according to claim 1, wherein the cell body element (12) is shaped such that the area-enlarging groove (13) is formed in a central section in a thickness reduction (X) of the cell body element (12) and in a rounded section (14) at both ends in the thickness direction (X). Secondary battery (10) according to claim 5, wherein the cell body element (12) has a rounded section (14) with a radius of curvature (Re) that is smaller than a radius of curvature (Rc) of the area-enlarging groove (13). Battery module comprising: a secondary battery (10) containing a cell body element (12) in which an electrode assembly (11) is housed, and a thermally conductive element (30) provided in at least one section between the cell body element (12) and a cooling plate element (21); and a housing element (20) comprising the cooling plate element (21) for heat exchange with the cell body element (12), which is effected by the thermally conductive element (30) and accommodates a plurality of the secondary batteries (10), wherein the cell body element (12) has an area-enlarging groove (13) which is designed to be concave when in contact with the thermally conductive element (30) via a lower surface, characterized in that the area-enlarging groove (13) is asymmetrically designed. Battery module according to claim 7, wherein the area-enlarging groove (13) is asymmetric in a thickness direction (X) of the cell body element (12). Battery module according to claim 8, wherein the area-enlarging groove (13) has a side configured to have a first radius of curvature (Rc1) in the thickness direction (X) of the cell body element (12), and another connected side configured to have a second radius of curvature (Rc2), wherein the first radius of curvature (Rc1) and the second radius of curvature (Rc2) are different from each other. Battery module according to claim 9, wherein, when the cell body element (12) is seated on and connected to the thermally conductive element (30) applied to the cooling plate element (21), the area-enlarging groove (13) has a first radius of curvature (Rc1) of one side, which is initially in contact with the thermally conductive element (30) applied to the cooling plate element (21), which is larger than the second radius of curvature (Rc2). Battery module according to claim 7, wherein the cell body element (12) is formed with the area-enlarging groove (13) in the central section of a thickness direction (X) of the cell body element (12) and a rounded section (14) at both ends in the thickness direction (X), wherein a radius of curvature (Re) of the rounded section (14) is smaller than a radius of curvature (Rc) of the area-enlarging groove (13). Battery module according to claim 7, wherein the cell body element (12) has the area-enlarging groove (13) which is formed in a central section in a thickness direction (X) to accommodate the heat-conducting element (30), and the two ends of which are formed in the thickness direction (X) to be in contact with the cooling plate element (21). Battery module according to claim 7, wherein the cooling plate element (12) has an area-enlarging strip (22) which is designed to project from a section in which the cell body element (12) is seated, and has at least one section which is inserted into the area-enlarging groove (13). Battery module according to claim 13, wherein the area-enlarging strip (22) is shaped to protrude in order to conform to a shape of the area-enlarging groove (13). Battery module according to claim 13, wherein the area-enlarging strip (22) is shaped such that it has a width that is smaller than the width of the area-enlarging groove (13) in the thickness direction (X) of the cell body element (12).

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