Battery module including a terminal connection structure provided with a floating nut and battery pack including the same

Abstract

A battery module of the present disclosure comprises: a cell assembly comprising at least one battery cell; a busbar assembly including a terminal busbar electrically connected to the electrode wire of the cell assembly, and a busbar frame covering the cell assembly on at least one side; and an insulating frame covering the busbar assembly from the outside, and may include a nut adjacent to the terminal busbar, and adjusted to have a size capable of flowing into a nut insertion chamber provided with a space within the insulating frame, thereby being mounted in the nut insertion chamber.

Description

Battery module including a terminal connection structure provided with a floating nut and battery pack including the same Technology sector Cross-reference to related request(s) This application claims the benefit of priority of Korean patent application no. 10-2019-0020751, filed with the Korean Intellectual Property Office on February 21, 2019. This disclosure relates to a battery module and a battery pack and, more specifically, to a battery pack that includes a battery module electrically connected through a terminal connection structure. State of the art Since secondary batteries can be easily applied to various product groups and offer electrical characteristics such as high energy density, they are universally used not only in portable devices but also in electric vehicles (EVs) or hybrid electric vehicles (HEVs), energy storage systems, and similar applications powered by an electric propulsion system. Secondary batteries are gaining attention as a new, environmentally friendly energy source for improving energy efficiency, as they offer the key advantage of significantly reducing fossil fuel consumption and, moreover, generate no energy byproducts whatsoever. A battery pack for use in electric vehicles features a structure in which a plurality of cell assemblies, each including a plurality of unit cells, are connected in series to achieve high power output. Furthermore, the unit cell can be repeatedly charged and discharged through electrochemical reactions between its components, which include a positive electrode current collector, a negative electrode current collector, a separator, an active material, an electrolyte, and the like. Furthermore, given the increasing need for a high-capacity structure in recent years, along with its use as a source of energy storage, there is a growing demand for battery packs with a multi-module structure in which a plurality of battery modules are integrated, each including a plurality of secondary batteries connected in series and / or in parallel. When connecting multiple battery cells in series or parallel to form a battery pack, it is common practice to first configure a battery module consisting of at least one battery cell and then configure a battery pack using at least one battery module and adding other components. The number of battery cells included in the battery pack, or the number of battery cells included in the battery module, can be determined in various ways depending on the required output voltage or the demanded charge / discharge capacity. To connect multiple battery modules together, a terminal connection structure can be fixed between adjacent battery modules, where a bolt and nut fastening structure can be applied. However, assembling a bolt to a nut that is fully secured to the battery module requires precise positional control, which can lead to a deterioration of the bolt's mounting properties and an increased defect rate. Furthermore, additional processes such as adhesive bonding and welding are required to secure the nut to the battery module, leading to increased component prices. Document KR20070080871 discloses a battery module comprising a laminate of cartridges with protruding electrode terminals designed to facilitate interconnection between the terminals and protect the terminal connections from short circuits and corrosion caused by moisture. This is achieved by manufacturing at least one unit cell, a busbar for the electrical connection of the cartridges, and a coupling element for securing the busbar to the electrode terminals. A battery module is formed comprising at least one unit cell and a laminate of a plurality of cartridges, each having externally protruding electrode terminals (111, 132).The module includes: an insulating housing (200) having an opening for the terminal to protrude and located between several electrode terminals; a collector bar (300) for electrically connecting the cartridges to the terminals; a coupling element (520) connected to the terminal to secure the collector bar to the terminal; a release prevention element (500) corresponding in appearance to the coupling element, located inside the housing; and a removable cover on the front side of an opening in the housing. Document KR19990010996 refers to a nut structure, a nut housing into which a nut element is inserted and secured by spot welding. Since the bolt is positioned and inserted into the threaded portion of the nut along the guide surface of the nut element and the hole in the nut housing plate, the need to adjust the holes is eliminated. Object of the invention Technical problem One object of the present disclosure is to provide a battery module with improved bolt and nut mounting properties by creating a structure in which a nut can float in a terminal connection structure between battery modules. Another object of this disclosure is to provide a battery pack configured to fix together a plurality of battery modules having a floating nut structure by means of a terminal connection structure. However, the problem to be solved by the realizations of this disclosure is not limited to the problems described above, and can be expanded in various ways within the scope of the technical idea included in this disclosure. Technical solution The invention is defined in the claims independent of the pending claims. According to claim 1, the invention is a battery module comprising a cell assembly including at least one battery cell; a busbar assembly including a terminal busbar electrically connected to an electrode conductor of the cell assembly, and a busbar frame covering the cell assembly on at least one side; and an insulation frame covering the busbar assembly from the outside, and further including a nut that is adjusted to a floating size in a nut insertion chamber adjacent to a terminal busbar and provided with a space inside the insulation frame, and mounted in the nut insertion chamber. The nut insertion chamber has a rectangular flat cross-section, and the width of a first nut direction is configured to be less than the width of a first nut insertion chamber direction. The width of a second direction crossing the first nut direction is set to be less than the width of a second nut insertion chamber direction. A fixing hole has been formed in the terminal busbar, and the nut is mounted in the nut insertion chamber so that a screw hole overlaps, at least partially, with the fixing hole. The diameter of the terminal busbar fixing hole may be designed to be larger than the diameter of the nut screw hole. The nut insertion chamber can be arranged one by one on both sides of the insulation frame in a flat direction. The nut may be shaped so that an edge of the screw hole towards an inlet of the nut insertion chamber is cut at an angle. The insulation frame includes an insulation cover located adjacent to the busbar assembly, and an outer cover that covers the insulation cover and secures a terminal connection structure, and the nut insertion chamber is provided in the insulation cover. According to claim 5, a battery pack is provided that includes a plurality of battery modules according to the invention and a bolt that passes through the terminal busbar fixing hole and is screwed into the nut screw hole. The battery pack may include a terminal connection structure featuring an inter-module busbar connecting a terminal busbar of an adjacent battery module, and the bolt may be engaged with the nut via the inter-module busbar. The bolt can be attached to the insulation frame through the nut's screw hole. According to claim 8, a device may be provided that includes at least one battery pack. Advantageous effects According to one embodiment, a nut is mounted on the connection portion of the outer terminal of the battery module to ensure clearance, thereby improving the ease of fixing with a bolt for connection to an adjacent battery module. Furthermore, since precise control of the position of the bolts and nuts is not required, assembly speed can be improved and the defect rate due to assembly errors can be reduced. Furthermore, since no additional process is required to limit the nut to the outside of the battery module, it is possible to avoid an increase in component prices. Description of the figures FIG. 1 is a perspective view illustrating a battery module according to an embodiment of the present disclosure. FIG. 2 is an exploded perspective view illustrating a busbar assembly, an insulation cover, and an outer cover of a battery module according to an embodiment of the present disclosure. FIG.3 is a cross-sectional view taken along line III-III of FIG.1. FIG. 4 is a perspective view illustrating a state in which a terminal connection structure is attached to a battery module according to an embodiment of the present disclosure. FIG.5 is a cross-sectional view taken along line VV of FIG.4. Figures 6a and 6b are schematic diagrams illustrating the relative positions of the bolt end, the terminal busbar mounting hole, and the nut screw hole in a state where the terminal connection structure is attached to the battery module according to an embodiment of this disclosure. Figure 6a illustrates a case where the bolt is in a fixed position when fastening adjacent battery modules, and Figure 6b illustrates a case where the bolt position is slightly off the center of the terminal bus bar fixing hole. FIGS.7a and 7b are schematic views illustrating the relative positions of the bolt end, the terminal busbar fixing hole, and the nut screw hole in a conventional bolt-on fastening structure. Detailed description of the invention Several embodiments of this disclosure will then be described in detail with reference to the accompanying drawings, so that those skilled in the art may easily carry them out. Furthermore, throughout the descriptive report, when a part is referred to as "including" a certain component, it means that it may also include other components, without excluding the other components, unless otherwise indicated. FIG. 1 is a perspective view illustrating a battery module according to an embodiment of the present disclosure, and FIG. 2 is an exploded perspective view illustrating a busbar assembly, an insulation cover, and an outer cover of a battery module according to an embodiment of the present disclosure. With reference to FIGS. 1 and 2, the battery module 100 according to the present embodiment includes a cell assembly, a busbar assembly 150, and an insulation frame 160 on at least one side of a module housing 135 that houses the cell assembly and forms the exterior of the battery module 100. The busbar assembly 150 is configured such that a busbar 151 is fixed externally on a busbar frame 155 located on the side of the direction in which an electrode conductor is drawn from the cell assembly. The electrode conductor of the cell assembly is electrically connected to the busbar 151 through a slot formed in the busbar frame 155. The insulation frame 160 includes an insulation cover 163 and an outer cover 165 located outside the busbar assembly 150.The insulation cover 163 is adjacent to the busbar assembly 150, and the outer cover 165 covers the insulation cover 163 and is located outside of it. Each of the insulation cover 163, the outer cover 165, and the busbar frame 155, which together constitute the insulation frame 160, may be made of non-conductive injection-molded materials. The battery cells that make up the cell assembly may be presented as a secondary bag-type battery and may be arranged by stacking a plurality of battery cells within the cell assembly. The plurality of battery cells may be electrically connected to each other, and each battery cell may include an electrode assembly, a battery housing that houses the electrode assembly, and an electrode conductor that protrudes from the battery housing and is electrically connected to the electrode assembly. Furthermore, the 100 battery module may include various electrical components and may include, for example, an internal circuit board (ICB) and a battery management system (BMS). Electrical components, such as the ICB and the BMS board, may be electrically connected to the multiple battery cells. The battery module 100 may form a terminal portion of the module so that a plurality of cells may be electrically coupled to one another. In the present embodiment, the battery module 100 may include terminal collector bars 153 located on both outermost sides of the bus bars fixed to the bus bar frame 155. A terminal collector bar 153 includes a plate that is bent perpendicularly to the main surface of the bus bar frame 155 from the upper end, and a fixing hole is formed in the plate. FIG.3 is a cross-sectional view taken along line III-III of FIG.1. In the insulation cover 163, a nut insertion chamber 168 is provided adjacent to a terminal collector bar 153. A space is provided in the nut insertion chamber 168 to allow the mounting of a nut 173, and the nut 173 can be adjusted to a floating size within the nut insertion chamber 168. In this embodiment, the nut insertion chamber 168 has a substantially rectangular, flat cross-section, and the width of the nut 173 in the first direction is configured to be less than the width of the nut insertion chamber 168 in the first direction. In this case, the first direction is defined as a direction parallel to the long side of the insulation cover 163. Accordingly, as shown in FIG.3. The space between nut 173 and nut insertion chamber 168 may be separated by a gap G1, G2, and nut 173 is not confined to the insulation cover 163 and can therefore float within nut insertion chamber 168. Furthermore, when the direction intersecting the first direction is called the second direction, the width of nut 173 in the second direction is configured to be less than the width of nut insertion chamber 168 in the second direction. Therefore, nut 173 can float in four directions within nut insertion chamber 168, thus increasing the degree of freedom of nut 173. A terminal collector bar 153 can be positioned on top of the nut insertion chamber 168 in which nut 173 is mounted.The position is established when the busbar assembly 150, to which the terminal busbar 153 is attached, and the insulation cover 163, equipped with the nut insertion chamber 168, are joined together. A fixing hole is formed in the terminal busbar 153, and when a bolt is attached to the nut 173 through the terminal busbar 153, the bolt can be secured through the fixing hole. At this point, the diameter (DT) of the fixing hole in the terminal busbar 153 can be shaped to be larger than the diameter (DN) of the nut 173's screw hole, and the nut 173 can be designed so that one edge of the screw hole 173a facing the entrance of the nut insertion chamber 168 is cut at an angle.Furthermore, nut 173 is mounted in nut insertion chamber 168 so that the screw hole at least partially overlaps the fixing hole. This improves the ease of fastening and increases working speed when the bolt is inserted into nut 173 to make the electrical connection between the battery modules. This will be described later with reference to a schematic diagram. Such a nut insertion chamber 168 and the nut 173 inserted therein can be arranged one by one on both sides of the insulation cover 163 in a flat direction, i.e., on both sides in a first direction. The terminal connection structures are respectively fixed to the nuts 173 arranged on both sides by means of bolts, so that they can be used for electrical connection with adjacent battery modules on both sides. FIG.4 is a perspective view illustrating a state in which a terminal connection structure is attached to a battery module according to an embodiment of the present disclosure, and FIG. 5 is a cross-sectional view taken along line VV of FIG.4. With reference to FIG. 4, a terminal connection structure 180 can be attached to a module terminal section to secure an adjacent battery module 100. The terminal connection structure 180 can be attached to an outer cover 165 of the insulation frame 160. The module terminal section can include a terminal collector bar 153 and a nut 173 mounted in the nut insertion chamber 168. The outer cover 165 allows the terminal collector bar 153, attached to the busbar assembly 150, to be exposed when coupled with the insulation cover 163 and the busbar assembly 150. While the terminal connection structure 180, attached to the outer cover 165, is coupled with the terminal collector bar 153, coupling with adjacent battery modules can be achieved. With reference to FIG. 5, the terminal connection structure 180 may include a busbar 185 between modules that provides the electrical connection between adjacent battery modules, and a bolt 183 for coupling the busbar 185 between modules to the terminal busbar 153 of each battery module 100. Specifically, the bolt 183 can be coupled by screwing it into the threaded hole of the nut 173 through the busbar 185 between modules and the terminal busbar 153. The bolt 183 can then be coupled to the nut 173 mounted in the nut insertion chamber 168 by passing, respectively, through the fixing hole of the busbar 185 between modules and the fixing hole of the terminal busbar 153. Furthermore, the bolt 183 can be fixed to the outer cover 165 through the threaded hole of the nut 173. Figures 6a and 6b are schematic diagrams illustrating the relative positions of the bolt end, the terminal busbar mounting hole 153a, and the nut screw-in hole 173a when the terminal connection structure is attached to the battery module according to an embodiment of this disclosure. Figure 6a illustrates a case where the bolt is in a fixed position when attaching adjacent battery modules, and Figure 6b illustrates a case where the bolt position is slightly offset from the center of the terminal busbar mounting hole 153a. When the position of bolt 183 deviates slightly from the fixed position, the end of bolt 183 can be inserted by tilting it to one side into the fixing hole 153a of the terminal collector bar 153. In this case, since nut 173 is sized to float in the nut insertion chamber 168, nut 173 can be displaced slightly along the insertion position of bolt 183. Therefore, to electrically connect adjacent battery modules 100, precise control is not required when securing bolt 183 to the terminal collector bar 153 and nut 173.As the end of bolt 183 is inserted into the fixing hole 153a of the terminal collector bar 153, the nut 173 moves within the nut insertion chamber 168, so that the screw hole 173a of the nut 173 is aligned with the end of bolt 183 and can be secured without interference between bolt 183 and nut 173. That is, by increasing the degree of freedom of nut 173, it is possible to absorb the tolerance and assembly tolerance of bolt 183 to ensure the securing property of bolt 183 and nut 173. FIGS.7a and 7b are schematic views illustrating the relative positions of the bolt end, the terminal busbar fixing hole, and the nut screw hole in a conventional bolted fastening structure. Traditionally, nut 73 was attached to a battery module terminal block by laser welding or similar means, and therefore could not be floated. In this case, as shown in FIG. 7a, when bolt 83 is in a fixed position, the nut 73's threading hole 73a, the terminal block's mounting hole 53a, and bolt 83 are aligned, and therefore no fastening problems occur. However, as shown in FIG. 7b, when bolt 83 is displaced from its fixed position, nut 73 becomes fixed and cannot be moved, even if bolt 83 is in the terminal block's mounting hole 53a. Therefore, bolt 83 is positioned outside nut 73's threading hole 73a, and bolt 83 and nut 73 interfere with each other, making fastening impossible.Having to reposition bolt 83 to find the fixed position can lengthen working time, leading to a deterioration of the fastening properties. Furthermore, the battery module according to an embodiment of the present invention can be packaged in a pack housing, while one or more of the battery modules are electrically connected to each other via a terminal connection structure to form a battery pack. That is, a plurality of battery modules can be electrically connected by fixing inter-module busbars that connect the terminal busbars of adjacent battery modules using bolts, thus constituting a battery pack. The battery module and battery pack included therein may be applied to various devices. These devices may be applied to vehicles such as an electric bicycle, an electric vehicle, or a hybrid vehicle, but this disclosure is not limited to these and may apply to various devices that may use the battery module and battery pack included therein, which also falls within the scope of this disclosure. Description of reference numbers 100: battery module 135: module housing 150: busbar assembly 151: busbar 153: terminal busbar 153a: fixing hole 155: busbar frame 160: insulation frame 163: insulation cover 165: outer cover 168: nut insertion chamber 173: nut 173a: screw hole 180: terminal connection structure 183: bolt

Claims

1. A battery module (100) comprising: - a cell assembly including at least one battery cell; - a busbar assembly (150) comprising: a busbar (151) fixed to the outside of the cell assembly on a busbar frame (155) covering one side of the cell assembly from which an electrode conductor extends, wherein the electrode conductor of the cell assembly is electrically connected to the busbar (151) through a slot formed in the busbar frame (155); a terminal busbar (153) electrically connected to the electrode conductor of the cell assembly, wherein the terminal busbar (153) includes a plate bent perpendicularly to a main surface of the busbar frame (155) from its upper end,wherein a fixing hole (153a) is formed in the plate of the terminal collector bar (153); - an insulation frame (160) comprising an insulation cover (163) located adjacent to the busbar assembly (150) and an outer cover (165) covering the insulation cover (163) and configured to fix a terminal connection structure (180), wherein there is a nut insertion chamber (168) in the insulation cover (163), having a rectangular flat cross-section and located adjacent to the terminal collector bar (150); and - a nut (173) having a width in a first direction, defined as a direction parallel to the long side of the insulation cover (163), less than the width in the first direction of the nut insertion chamber (168), and a width in a second direction, defined as the direction crossing the first direction,smaller than the width in the second direction of the nut insertion chamber (168), so as to increase the degrees of freedom of the nut (173) in the nut insertion chamber (168), wherein the nut (173) is mounted in the nut insertion chamber (168) such that a screw hole (173a) for the nut (173) overlaps, at least partially, with the fixing hole (153a).

2. The battery module according to claim 1, wherein the diameter of the fixing hole (153a) for the terminal collector bar (153) is larger than the diameter of the screw hole (173a) for the nut.

3. The battery module (100) according to claim 1, wherein the nut insertion chamber (168) is arranged one-to-one on both sides of the insulation frame (160) in a planar direction.

4. The battery module (100) according to claim 1,wherein the nut is formed such that an edge of the screw hole (173a) facing an inlet of the nut insertion chamber (168) is cut at an angle.

5. A battery pack comprising a plurality of battery modules (800) according to any of claims 1 to 4, wherein the battery pack comprises a bolt (183) passing through the terminal busbar (153a) fixing hole and engaged by screwing into the nut (173a) screw hole.

6. The battery pack according to claim 5, comprising a terminal connection structure (180) having an inter-module busbar connecting a terminal busbar of an adjacent battery module, wherein the bolt (183) is engaged with the nut via the inter-module busbar.

7. The battery pack according to claim 5,wherein the bolt (183) is fixed to the insulation frame (160) through the screw hole (173a) of the nut (173).

8. A device comprising at least one battery pack according to claim 5, 6 or 7.