Patent Description:
The present application claims priority to <CIT> in the Republic of Koreainvention.

Recently, demands for portable electronic products, such as laptop computers, video cameras, portable phones, etc. have rapidly increased, and development of electric vehicles, batteries for energy storage, robots, and satellites, etc. has increased, and thus studies on high-performance secondary batteries capable of repetitive charging and discharging are actively conducted.

Currently commercialized secondary batteries include nickel cadmium batteries, nickel hydrogen batteries, nickel zinc batteries, lithium secondary batteries, etc., and thereamong, the lithium secondary batteries are in the limelight because the lithium secondary batteries have almost no memory effect compared to nickel-based secondary batteries and are thus freely charged and discharged, have a very low self-discharge rate, and have high energy density.

Such a lithium secondary battery mainly uses a lithium-based oxide and a carbon material respectively as a positive electrode active material and a negative electrode active material. The lithium secondary battery includes an electrode assembly, in which a positive electrode plate and a negative electrode plate respectively coated with a positive electrode active material and a negative electrode active material are arranged with a separator therebetween, and an exterior material, i.e., a battery case, sealing and accommodating the electrode assembly with an electrolyte solution together.

The lithium secondary battery may be classified, according to a shape of the exterior material, into a can-type secondary battery, in which the electrode assembly is embedded in a metal can, and a pouch-type secondary battery, in which an electrode assembly is embedded in a pouch of an aluminum laminate sheet.

In the can-type secondary battery, a metal can including an electrode assembly may have a cylindrical shape. The can-type secondary battery may be used to configure a battery module including a housing accommodating a plurality of secondary batteries and a bus bar configured to electrically connect the plurality of secondary batteries.

Recently, a bus bar included in such a battery module has been manufactured using a material having a relatively high electrical resistance to increase weldability of resistance welding with respect to an electrode terminal.

However, the bus bar may be a factor that increases current loss in a current generated in a secondary battery and transferred to an external device, thus degrading energy efficiency. Also, the higher the electrical resistance of a material, the lower the thermal conductivity of the material is. Thus, the material may be a factor that degrades heat dissipation performance of a battery module in which the bus bar as described above is applied.

On the other hand, a material having an excessively low electrical resistance may reduce an amount of heat generated according to resistance welding, making the resistance welding difficult. Thus, it may be difficult to select an appropriate material for bus bars.

Moreover, for bus bars applied to low-cost battery modules, a low-priced material has to be applied to lower the manufacturing costs.

Also, in the related art, in order to electrically connect a plurality of battery modules to each other to configure a battery pack, bus bars applied to each of the plurality of battery modules have to be electrically connected to each other. However, a process of electrically connecting a plurality of provided bus bars at the same time when arranging a plurality of battery modules is typically performed by using an additional connection member, and thus the connection and fixing thereof require a complicated and difficult process. Thus, this process has been a significant factor that increases the manufacturing time and the manufacturing costs.

<CIT> discloses a bus bar comprising: a tabular bus bar main body part; a junction bonded to an electrode terminal of a cylindrical battery; and a connection part connecting the bus bar main body part with the junction. The connection part has a bent and linear shape in which multiple linear portions are continued while interposing bent parts between mutually adjacent linear portions in a planar view. At least any one of the multiple linear portions includes a protrusion protruding in a direction across an extension direction of the linear portion in a planar view.

<CIT> relates to a battery pack having improved safety. The battery pack comprises: a plurality of bear cells each having an electrode portion, and arranged in a direction; a holder case receiving the bear cells; and a connecting tap having a body portion electrically connected to the bear cells, a slit portion positioned in each of the electrode portions of the bear cells, and at least one welded portion welded to the electrode portions of the bear cells. The slit portion includes first and second slits spaced apart from each other at a regular interval, first and second bridges provided at ends of the first and second slits, and a welded slit crossing between the first and second slits.

<CIT> discloses a battery pack in which a plurality of batteries are arranged and accommodated in a holder,.

<CIT> discloses a battery pack comprising secondary batteries, where each battery comprises a terminal, and welding tab coupling a terminal of a first secondary battery to a terminal of a second secondary battery, where a first end of the tab compriss a frst region having a first welding portion and a second region having a second welding portion.

The present invention is designed to solve the problems of the related art, and therefore the present invention is directed to providing a battery module including a bus bar and a battery pack including the battery module, in which weldability between a bus bar and an electrode terminal of a cylindrical battery cell may be increased, a heat dissipation efficiency may be increased, and current loss may be reduced.

The invention is defined in claim <NUM> and provides a battery module including: a plurality of cylindrical battery cells including electrode terminals respectively formed at a top and a bottom of the plurality of cylindrical cells, the plurality of cylindrical battery cells being arranged in columns and rows in a horizontal direction; a module housing including an accommodation portion having a plurality of hollow structures to accommodate the plurality of cylindrical battery cells inserted into the module housing; and a bus bar configured to contact the electrode terminals of the plurality of cylindrical battery cells to electrically connect between the plurality of cylindrical battery cells, wherein the bus bar includes: a main body portion that is positioned at a top or a bottom of the plurality of cylindrical battery cells and has a plate shape having upper and lower surfaces that are broader than a lateral surface of the main body portion in a horizontal direction; and a contact portion that is configured to electrically contact and be connected to an electrode terminal formed in one of the plurality of cylindrical battery cells, extends and protrudes from the main body portion in a horizontal direction, is stepped from the main body portion in a direction toward where the electrode terminal is positioned, and includes a branched structure bifurcated in two directions with respect to a direction in which the contact portion extends and protrudes from the main body portion, wherein an embossed protrusion protruding toward where the electrode terminal is positioned is formed in the branched structure, and a contact area is set to allow a welding rod to establish electrical connection around the embossed protrusion in the branched structure.

The preferred embodiments of the invention are defined in the dependent claims.

Also, at least one connection opening that is perforated vertically may be formed in the main body portion.

Moreover, the contact portion may be formed within a circumference of the connection opening.

Also, a notch may be formed in a connection area between the circumference of the connection opening and the contact portion.

Also, the connection opening may be formed at an end of the main body portion.

Moreover, the bus bar may include a copper alloy.

Also, the embossed protrusion may have an annular shape in a plan view and is formed to have a greater protruding depth toward a center of the annular shape of the embossed protrusion in a direction toward where the electrode terminal is formed.

Also, the welding rod may have a cylindrical shape.

Moreover, a diameter of the annular shape of the embossed protrusion may be less than a diameter of the cylindrical shape of the welding rod.

Also, an insertion groove that is internally engraved in a direction where the electrode terminal is formed may be formed in a peripheral circumference of the embossed protrusion, wherein an end of the cylindrical welding rod in a vertical direction is inserted into the insertion groove.

Moreover, the electrode terminals of the cylindrical battery cells may include a first electrode terminal formed at an upper end of the cylindrical battery cells and a second electrode terminal formed at a lower end of the cylindrical battery cells.

The bus bar may include: a first bus bar mounted to a top of the module housing to be electrically connected to the first electrode terminal; and a second bus bar mounted under the module housing to be electrically connected to the second electrode terminal,.

The first bus bar may include a mounting portion formed at a front end portion of the main body portion to be in contact with a portion of the second bus bar.

The second bus bar may include: a bent portion that is vertically and upwardly bent and extended from a rear end portion of the main body portion; and a connection portion that is bent and extended backward from an upper end of the bent portion and is configured to be mounted on the mounting portion of the first bus bar to be electrically connected to the first bus bar.

In another aspect of the present invention, there is provided a battery module including: a plurality of cylindrical battery cells including electrode terminals respectively formed at a top and a bottom of the plurality of cylindrical cells and a plurality of externally protruding protrusions formed on the electrode terminals, the plurality of cylindrical battery cells being arranged in columns and rows in a horizontal direction; a module housing including an accommodation portion having a plurality of hollow structures to accommodate the plurality of cylindrical battery cells inserted into the module housing; and a bus bar coupled to the protrusions of the electrode terminals of the plurality of cylindrical battery cells by welding and configured to electrically connect between the plurality of cylindrical battery cells, wherein the bus bar includes: a main body portion that is positioned at a top or a bottom of the plurality of cylindrical battery cells and has a plate shape having upper and lower surfaces that are broader than a lateral surface of the main body portion in a horizontal direction; and a contact portion that is configured to electrically contact and be connected to an electrode terminal formed in one of the plurality of battery cells, extends and protrudes from the main body portion in a horizontal direction, is stepped from the main body portion in a direction toward where the electrode terminal is positioned, and includes a branched structure bifurcated in two directions with respect to a direction in which the contact portion extends and protrudes from the main body portion, wherein an embossed protrusion protruding toward where the electrode terminal is positioned is formed in the branched structure, and a contact area is set to allow a welding rod to establish electrical connection around the embossed protrusion in the branched structure.

Also, a battery pack according to the present invention may include at least two battery modules described above, which are arranged in a direction.

Moreover, a device according to the present invention may include the battery pack described above.

According to an aspect of the present invention, according to a battery module of the present invention, a coupling protrusion and a guide groove are formed in an outer side wall of a module housing, thereby enabling easy arrangement of a plurality of battery modules and fixing the battery modules so as to prevent them from being easily separated from each other.

Also, according to an aspect of the present invention, a first protruded fastening portion formed in a module housing and a second protruded fastening portion of another module housing may be fastened to each other via a bolt, thus fastening the battery modules by ensuring prevention of breaking of the arrangement of the battery modules. In particular, the above fastening structure may prevent disconnection of an electrical connection between a first bus bar and a second bus bar.

Moreover, according to an aspect of the present invention, by forming a stepped structure in a contact portion of a bus bar, the contact portion may be arranged adjacent to an electrode terminal, and deformation of or damage to a connection area between the contact portion and a main body portion due to a pressure applied to the contact portion during projection welding may be reduced.

According to an aspect of the present invention, a contact portion of a bus bar may be used to set a long current path due to a branched structure during resistance welding, thereby effectively generating resistance heat and thus obtaining a high welding efficiency and high reliability.

Furthermore, according to an aspect of the present invention, as the contact area P which is annular is set in the periphery of the embossed protrusion so that the welding rod contact and pressurize the bus bar, a pressing force of the welding rod may be evenly transferred to the embossed protrusion, and a current may be flown from the welding rod to the embossed protrusion at an overall uniform current density. Accordingly, according to the bus bar of the present invention, welding between the contact portion and the electrode terminals may be obtained at a higher adhesive force and higher reliability.

Also, according to an aspect of the present invention, by forming the insertion groove, into which an end of the welding rod is inserted, in the peripheral circumference of the embossed protrusion, not only the size of the contact area of the welding rod may be increased, but an insertion position of the welding rod may also be guided along an inner surface of the insertion groove, thus facilitating resistance welding. Also, deviation of the welding rod from the contact area, which may occur when the welding rod is pressurized, may be prevented.

The accompanying drawings illustrate a preferred embodiment of the present invention and together with the foregoing invention, serve to provide further understanding of the technical features of the present invention, and thus, the present invention is not construed as being limited to the drawing.

<FIG> is a perspective view schematically showing a battery module according to an embodiment of the present invention. <FIG> is a disassembled perspective view schematically showing a battery module according to an embodiment of the present invention.

Referring to <FIG> and <FIG>, a battery module <NUM> according to an embodiment of the present invention may include a cylindrical battery cell <NUM>, a module housing <NUM>, and a bus bar <NUM>.

Here, the cylindrical battery cell <NUM> may include a cylindrical battery can <NUM> and an electrode assembly (not shown) accommodated in the battery can <NUM>.

Here, the battery can <NUM> includes a material having a high electrical conductivity. For example, the battery can <NUM> may include an aluminum material or copper material.

Also, the battery can <NUM> may be configured in a vertically extending shape. Also, the battery can <NUM> may be a vertically extending cylindrical shape. Moreover, electrode terminals <NUM> and <NUM> may be respectively formed at upper and lower portions of the battery can <NUM>. In detail, a first electrode terminal <NUM> may be formed on a flat circular upper surface at an upper end of the battery can <NUM>, and a second electrode terminal <NUM> may be formed on a flat circular lower surface at a lower end of the battery can <NUM>.

Furthermore, the cylindrical battery cell <NUM> may be arranged in a plurality of columns and rows in a horizontal direction. The horizontal direction may refer to a direction parallel to a ground surface on which the cylindrical battery cell <NUM> is placed, and may also refer to at least one direction on a plane perpendicular to a vertical direction.

For example, as illustrated in <FIG>, the battery module <NUM> may include a plurality of cylindrical battery cells <NUM> arranged in four rows in a back and forth direction W and in seven or six rows in a left and right direction V.

Also, the electrode assembly (not shown) may have a structure in which a positive electrode and a negative electrode are wound in a jelly-roll form with a separation layer interposed between the positive and negative electrodes. A positive electrode tab may be attached to the positive electrode (not shown) to be connected to the first electrode terminal <NUM> at the upper end of the battery can <NUM>. A negative electrode tab may be attached to the negative electrode (not shown) to be connected to the second electrode terminal <NUM> at the lower end of the battery can <NUM>.

Meanwhile, the module housing <NUM> may include accommodation portions 212A and 212B into which the cylindrical battery cell <NUM> may be inserted to be accommodated therein. In detail, a plurality of hollow structures formed to surround an outer side surface of the cylindrical battery cell <NUM> may be formed in the accommodation portions 212A and 212B.

Also, the module housing <NUM> may include a first outer side wall 210a, a second outer side wall 210b, a third outer side wall 210c, and a fourth outer side wall 210d that are formed to form an internal space of the module housing <NUM> and respectively in a front direction, a back direction, a left direction, and a right direction.

Also, coupling protrusions <NUM> and <NUM> and guide grooves <NUM> and <NUM> that are used to guide an arrangement position of another battery module <NUM> may be formed in at least one of the first outer side wall 210a, the second outer side wall 210b, the third outer side wall 210c, and the fourth outer side wall 210d of the module housing <NUM>.

For example, as illustrated in <FIG>, two coupling protrusions <NUM> and <NUM> and two guide grooves <NUM> and <NUM> may be respectively formed in the first outer side wall 210a and the second outer side wall 210b of the module housing <NUM>.

Thus, according to this configuration of the present invention, the coupling protrusions <NUM> and <NUM> of the module housing <NUM> according to the present invention may be inserted into the guide grooves <NUM> and <NUM> formed in the second outer side wall 210b of another module housing <NUM> to be fastened and fixed thereto, and thus, another battery module <NUM> (<FIG>) connected to one battery module <NUM> may be easily arranged, and the battery modules may be fixed so that they are not easily separated.

Referring back to <FIG> and <FIG>, an upper case 210A may include a first protruded fastening portion <NUM>, and a lower case 210B may include a second protruded fastening portion <NUM>.

In detail, the first protruded fastening portion <NUM> may protrude and extend backward from an outer surface of the second outer side wall 210b of the first upper case 210A when viewed in an F direction. Also, the second protruded fastening portion <NUM> may protrude and extend forward from an outer surface of the first outer side wall 210a of the lower case 210B when viewed in the F direction.

The terms indicating directions, such as front, back, left, right, up, and down may vary depending on a position of an observer or a manner in which an object is placed. However, for convenience of description, directions, such as front, back, left, right, up, and down, viewed in the F-direction are described in the present specification.

Also, through holes <NUM>, <NUM> may be respectively formed in the first protruded fastening portion <NUM> and the second protruded fastening portion <NUM> so as to insert a fastening bolt <NUM> (<FIG>). For example, as illustrated in <FIG>, the first protruded fastening portion <NUM> of the module housing <NUM> may be fastened and coupled to the second protruded fastening portion <NUM> of another battery module <NUM> (<FIG>) through the fastening bolt <NUM>.

Here, the through hole <NUM> of the second protruded fastening portion <NUM> may be communicatively connected to the through hole <NUM> of the first protruded fastening portion <NUM> of the upper case 210A of another battery module <NUM> such that the fastening bolt <NUM> is continuously inserted into the through holes <NUM> and <NUM>. Accordingly, in the one battery module <NUM> and the other battery module (<NUM> of <FIG>), the battery modules (<NUM>, <NUM>, <NUM>, <NUM> of <FIG>) may be arranged as the first protruded fastening portion <NUM> and the second protruded fastening portion <NUM> are fastened to each other by using the fastening bolt <NUM>.

Accordingly, according to this configuration of the present invention, as the first protruded fastening portion <NUM> of the upper case 210A is fastened to the second protruded fastening portion <NUM> of the lower case 210B of another battery module <NUM> via a bolt, breaking of the arrangement of the battery modules <NUM> may be prevented, and particularly, disconnection of electrical connection between the first bus bar 250A and the second bus bar 250B may be prevented.

Meanwhile, the module housing <NUM> may include the upper case 210A and the lower case 210B.

<FIG> is a perspective view schematically showing some components of a battery module, according to an embodiment of the present invention.

Referring to <FIG> with <FIG>, the bus bar <NUM> may include a structure in which a surface of the bus bar <NUM> contacts the electrode terminals <NUM> and <NUM> of at least two cylindrical battery cells <NUM> from among the plurality of cylindrical battery cells <NUM> to be electrically connected to the cylindrical battery cells <NUM>. That is, the bus bar <NUM> may be configured to contact the first electrode terminal <NUM> or the second electrode terminal <NUM> of the plurality of cylindrical battery cells <NUM> to electrically connect between the plurality of cylindrical battery cells <NUM>. In detail, the bus bar <NUM> may include a main body portion <NUM> and a contact portion <NUM>.

Here, the main body portion <NUM> may have a plate shape having upper and lower surfaces that are broader than a lateral surface thereof in a horizontal direction (x-direction, y-direction). Also, the main body portion <NUM> may be positioned at a top or a bottom of the plurality of cylindrical battery cells <NUM> where the first electrode terminal <NUM> or the second electrode terminal <NUM> is formed.

Also, a hanging structure 251d for fixing a position of the bus bar <NUM> may be formed at an end portion of the main body portion <NUM> in a horizontal direction (y-direction). Moreover, a through port (not shown) may be formed in the hanging structure 251d such that the hanging structure 251d is coupled to an outer wall of the module housing <NUM> via a bolt.

Also, a curved portion <NUM> that is inwardly curved to correspond to an outer shape of the module housing <NUM> may be formed in the main body portion <NUM>.

<FIG> is a partial side view schematically showing a region A' of a bus bar of <FIG>. <FIG> is a partial plan view schematically showing the region A' of the bus bar of <FIG>.

Referring to <FIG> and <FIG> with <FIG>, the contact portion <NUM> may be configured to electrically contact and be connected to the first electrode terminal <NUM> or the second electrode terminal <NUM> formed in one of the plurality of cylindrical battery cells <NUM>. To this end, the contact portion <NUM> may extend and protrude from the main body portion <NUM> in a horizontal direction (x-direction). For example, as illustrated in <FIG>, the contact portion <NUM> may extend and protrude backward from the main body portion <NUM>.

Also, in the contact portion <NUM>, a stepped structure S that is stepped from the main body portion <NUM> in a direction (downward direction) toward where the first electrode terminal <NUM> or the second electrode terminal <NUM> is positioned may be formed. For example, as illustrated in <FIG>, in the contact portion <NUM>, a stepped structure S that is stepped in a direction (downward direction) to where the first electrode terminal <NUM> formed in an upper portion of the cylindrical battery cell <NUM> is positioned may be formed.

Thus, according to this configuration of the present invention, as the stepped structure S is formed in the contact portion <NUM>, the contact portion <NUM> may be arranged adjacent to the electrode terminals <NUM> and <NUM>, and deformation of or damage to a connection area between the contact portion <NUM> and the main body portion <NUM> due to a pressure applied to the contact portion <NUM> during projection welding may be reduced.

Also, in the contact portion <NUM>, a branched structure 256n that is bifurcated in two directions with respect to a direction in which the contact portion <NUM> extends and protrudes from the main body portion <NUM> may be included. That is, in the contact portion <NUM>, a groove or a slit S1 that are inwardly curved in an opposite direction to ends (of the branched structure 256n in the extended and protruded direction.

For example, as illustrated in <FIG>, twenty-six contact portions <NUM> may be formed in the bus bar <NUM>. Also, a branched structure 256n bifurcated in left and right directions may be formed in each of the twenty-six contact portions <NUM>.

Moreover, an embossed protrusion <NUM> protruding toward where the electrode terminals <NUM> and <NUM> are positioned may be formed in the branched structure 256n. That is, an embossed protrusion <NUM> may be formed in each of two portions branched off from the branched structure 256n.

Furthermore, the branched structure 256n may be configured such that a welding rod <NUM> is contacted by and connected to the branched structure 256n. In detail, a contact area P may be set such that the welding rod <NUM> (<FIG>) having a cylindrical shape establishes electrical connection around the embossed protrusion <NUM> formed in the branched structure 256n.

Referring back to <FIG> and <FIG>, at least one connection opening H1 perforated vertically may be formed in the main body portion <NUM>. Also, the contact portion <NUM> may protrude and extend backward within a circumference of the connection opening H1. That is, the connection opening H1 may be formed to surround the protruding and extending portion of the contact portion <NUM>.

Moreover, a notch 253a and a convex structure 253b may be formed in the connection opening H1. Here, the notch 253a and the convex structure 253b may be formed such that a stepped structure is formed in the contact portion <NUM> and thus to prevent damage or deformation that may occur while pressing the contact portion <NUM> from above in a downward direction. That is, the notch 253a may have a circumference that is inwardly curved in a round shape. In other words, the notch 253a may have a curved shape to distribute a stress caused by pressing the contact portion <NUM>. Furthermore, the convex structure 253b may be convexly protruded to absorb a stress generated during formation of a stepped structure S.

Also, the connection opening H1 may be formed to space the branched structure 256n of the contact portion <NUM> apart from the main body portion <NUM> so that they do not contact each other. That is, the branched structure 256n may induce a current that is added via the welding rod <NUM> such that the current is not distributed to the main body portion <NUM> but is completely energized through the branched structure 256n.

<FIG> is a partial plan view schematically showing a region B' of the bus bar of <FIG>. The contact portion <NUM> of <FIG> may have a similar or identical component or structure as the contact portion <NUM> of <FIG> described above, and thus detailed description thereof will be omitted.

Referring to <FIG> with <FIG>, the contact portion <NUM> may be formed at an end of the main body portion <NUM>. That is, unlike the contact portion <NUM> of <FIG>, the contact portion <NUM> is not formed within the connection opening H1 formed in the main body portion <NUM>. For example, as illustrated in <FIG>, six contact portions <NUM> that are not formed within the connection opening H1 may be formed at a rear end of the bus bar <NUM>.

Accordingly, according to this configuration of the present invention, the contact portions <NUM> that are not formed within the connection opening H1 of <FIG> do not form additional connection openings H1, and thus may be formed by simple shape processing, and degradation of mechanical characteristics of the bus bar <NUM> due to shape processing may be reduced, and efficient resistance welding may be performed.

Also, the main body portion <NUM> of the bus bar <NUM> may have a shape that does not cover all of the plurality of cylindrical battery cells <NUM>. For example, as illustrated in <FIG>, the main body portion <NUM> of the bus bar <NUM> may not cover all of the plurality of cylindrical battery cells <NUM>, but may be formed such that upper ends of the cylindrical battery cells <NUM> at a rearmost column from among the plurality of cylindrical battery cells <NUM> are exposed to the outside.

Thus, according to this configuration of the present invention, by forming the main body portion <NUM> such that upper ends of some of the cylindrical battery cells <NUM> are externally exposed, the material cost of the bus bar <NUM> may be reduced, and heat generated by charging and discharging the plurality of cylindrical battery cells <NUM> accommodated in the module housing <NUM> may be effectively discharged to the outside.

The bus bar <NUM> may include a copper alloy. In detail, the copper alloy may include at least <NUM> wt% of copper in the total weight, and more specifically, the copper alloy may include at least <NUM> wt% of copper in the total weight. The copper alloy may include at least one selected from the group consisting of nickel, silicon, tin, iron, zinc, magnesium, phosphorus, chromium, and zirconium in the remaining weight percent excluding the weight percentage of copper. For example, the copper alloy may include at least <NUM> wt% copper, less than <NUM> wt% zinc, less than <NUM> wt% chromium, and less than <NUM> wt% zirconium. Further, in another embodiment, the copper alloy may include at least <NUM> wt% copper, less than <NUM> wt% nickel, less than <NUM> wt% silicon, less than <NUM> wt% tin, at least <NUM> wt% iron, at least <NUM> wt% zinc, at least <NUM> wt% magnesium, at least <NUM> wt% phosphorus, and at least <NUM> wt% zirconium. However, the bus bar <NUM> is not limited to a copper alloy, but any metal alloy consisting of nickel, aluminum, gold, silver, or the like as a main material may be used.

Therefore, when the bus bar <NUM> including a copper alloy is used, the battery module <NUM> according to the present invention has a higher conductivity than a bus bar formed of a nickel material, thereby minimizing current loss and effectively generating heat. Accordingly, heat dissipation of the battery module may be facilitated to increase a cooling efficiency of the battery module.

Also, a plating layer may be formed using a metal having a relatively high specific resistance compared to the bus bar <NUM>, on a surface of the bus bar <NUM>. For example, the metal having a high specific resistance may be nickel. Moreover, the plating layer may have a thickness of <NUM> to <NUM>. In detail, when the thickness of the plating layer is less than <NUM>, it is difficult to generate a relatively high resistance by using the plating layer in a welding portion during resistance welding, and thus, it is difficult to perform efficient resistance welding. On the other hand, when the thickness of the plating layer exceeds <NUM>, welding processability between the contact portion <NUM> and the electrode terminals <NUM> and <NUM> may be degraded, which is undesirable.

<FIG> is a partial side view schematically illustrating a process of welding a contact portion of a bus bar and an electrode terminal of a battery module, according to an embodiment of the present invention.

Referring to <FIG> with <FIG>, the embossed protrusion <NUM> formed on the branched structure 256n may be annular in a plan view. Also, the embossed protrusion <NUM> may be formed to have a greater protruding depth toward a center of the annular shape of the embossed protrusion <NUM> in a direction toward where the electrode terminals <NUM> and <NUM> are formed.

Moreover, the welding rod <NUM> used to perform welding between the contact portion <NUM> and the electrode terminals <NUM> and <NUM> may be configured to pressurize the entire contact area P which is configured to establish electrical connection of the welding rod <NUM>. For example, when the contact area P is formed along a periphery of an upper portion of the annular embossed protrusion <NUM>, a lower surface of the welding rod <NUM> contacting the contact area P may have a circular shape. Moreover, the welding rod <NUM> may have a cylindrical shape having a lower surface that is a flat circle. Here, an outermost diameter of the annular shape of the embossed protrusion <NUM> may be smaller than a diameter of the cylindrical shape of the welding rod <NUM>.

Thus, according to this configuration of the present invention, as the contact area P which is annular is set in the bus bar <NUM> in the periphery of an upper surface of the annular embossed protrusion <NUM> so that the cylindrical welding rod <NUM> may contact and pressurize the bus bar <NUM>, a pressing force of the welding rod <NUM> may be evenly transferred to the embossed protrusion <NUM>, and a current may be flown from the welding rod <NUM> to the embossed protrusion <NUM> at an overall uniform current density. Accordingly, according to the bus bar <NUM> of the present invention, welding between the contact portion <NUM> and the electrode terminals <NUM> and <NUM> may be obtained at a higher adhesive force and higher reliability.

<FIG> is a partial side view schematically illustrating a process of welding a contact portion 256C of a bus bar 250C and a first electrode terminal <NUM> of a battery module, according to another embodiment of the present invention. The contact portion 256C of <FIG> may have a similar or identical component or structure as the contact portion <NUM> of <FIG> described above, and thus detailed description thereof will be omitted.

Referring to <FIG>, in the bus bar 250C according to the other embodiment, an insertion groove H2 that is internally engraved in a direction to where the electrode terminals <NUM> and <NUM> are formed may be formed in a peripheral circumference of an upper portion of the embossed protrusion <NUM> formed in the contact portion 256C. Also, the insertion groove H2 may have a size that allows a vertical end of the cylindrical welding rod <NUM> to be inserted thereinto.

For example, as illustrated in <FIG>, when a surface of a lower end of the welding rod <NUM> has a flat cylindrical shape, the insertion groove H2 may have a circular shape in a plane view. Also, the insertion groove H2 may be formed to have a certain depth in a direction toward where the electrode terminals <NUM> and <NUM> are formed. Furthermore, an inner surface of the insertion groove H2 may be set as a contact area P of the welding rod <NUM>.

Accordingly, according to this configuration of the present invention, by forming the insertion groove H2, into which an end of the welding rod <NUM> is inserted, in the peripheral circumference of the upper portion of the embossed protrusion <NUM>, not only the size of the contact area P of the welding rod <NUM> may be increased, but a position of the welding rod <NUM> may also be guided along an inner surface of the insertion groove H2, thus facilitating resistance welding. Also, deviation of the welding rod <NUM> from the contact area P, which may occur when the welding rod <NUM> is pressurized, may be prevented.

<FIG> is a partial side view schematically illustrating a process of welding a contact portion <NUM> of a bus bar <NUM> and an electrode terminal 111B of a battery module, according to another embodiment of the present invention. A cylindrical battery cell 100B of <FIG> may have a similar or identical component or structure as the cylindrical battery cell <NUM> of <FIG> described above, except that a plurality of protrusions <NUM> are further formed on the electrode terminal 111B, and thus detailed description thereof will be omitted.

Referring to <FIG>, in the cylindrical battery cell 100B applied to a battery module, according to the other embodiment of the present invention, the plurality of protrusions <NUM> protruding externally may be formed on the electrode terminal 111B formed at a top or a bottom of cylindrical battery cell 100B.

Also, the battery module may include a bus bar <NUM> that is coupled to the protrusions <NUM> of the electrode terminal 111B of the plurality of cylindrical battery cells 100B by welding. The bus bar <NUM> may be configured to electrically connect between the plurality of cylindrical battery cells 100B.

For example, as illustrated in <FIG>, two protrusions <NUM> may be formed on the electrode terminal 111B formed on the cylindrical battery cell 100B. The two protrusions <NUM> may be coupled to a lower surface of the contact portion <NUM> of the bus bar <NUM> by projection welding.

Accordingly, according to this configuration of the present invention, when coupling the electrode terminal 111B and the bus bar <NUM> by welding, a welding defect rate may be reduced by using the protrusions <NUM> formed on the electrode terminal 111B and the embossed protrusion <NUM> of the bus bar <NUM>, and a welding strength may be further increased.

<FIG> is a perspective view schematically illustrating a first bus bar and a second bus bar regarding a battery module according to an embodiment of the present invention. <FIG> is a partial side view schematically showing a region C' of the battery module of <FIG>.

First, referring to <FIG>, the bus bar <NUM> of the battery module <NUM> according to an embodiment of the present invention may include, specifically, a first bus bar 250A and a second bus bar 250B. Also, the first bus bar 250A and the second bus bar 250B may include both the main body portion <NUM>, the connection opening H1, and the contact portion <NUM> described above.

Referring to <FIG> with <FIG> again, the bus bar <NUM> may include the first bus bar 250A that is electrically connected to the first electrode terminal <NUM> formed at the upper end of the cylindrical battery cell <NUM> and the second bus bar 250B that is electrically connected to the second electrode terminal <NUM> formed at the lower end of the cylindrical battery cell <NUM>.

Furthermore, the first bus bar 250A may be mounted to a top of the module housing <NUM> to contact the first electrode terminal <NUM>. The second bus bar 250B may be mounted under the module housing <NUM> to contact the second electrode terminal <NUM>.

Furthermore, the first bus bar 250A may include a mounting portion <NUM> that is formed at a front end portion of the main body portion <NUM> to be in contact with a portion of the second bus bar 250B when viewed in an F-direction. That is, the mounting portion <NUM> may have an upper surface to contact a lower surface of a portion of the second bus bar 250B.

Also, the second bus bar 250B may include a bent portion <NUM> and a connection portion <NUM> connected to the bent portion <NUM>. In detail, the bent portion <NUM> may have a structure that is vertically and upwardly bent from a rear end portion of the main body portion <NUM> of the second bus bar 250B to be extended. Moreover, the connection portion <NUM> may be bent and extended backward from an upper end of the bent portion <NUM>. Also, the connection portion <NUM> may be configured to be mounted on the upper surface of the mounting portion <NUM> of the first bus bar 250A to be electrically connected to the first bus bar 250A. Also, a lower surface of the connection portion <NUM> may be configured to contact the upper surface of the mounting portion <NUM> of the first bus bar 250A.

Furthermore, at least one fixing protrusion 255P protruding downwards may be formed on the lower surface of the connection portion <NUM>. Also, an accommodation groove <NUM> having a shape corresponding to the fixing protrusion 255P of the connection portion <NUM> may be formed in the mounting portion <NUM> of the first bus bar 250A. Accordingly, the fixing protrusion 255P of the connection portion <NUM> of the second bus bar 250B may be inserted into the accommodation groove <NUM> of the mounting portion <NUM> of the first bus bar 250A to be fixed.

Thus, according to this configuration of the present invention, as the fixing protrusion 255P of the connection portion <NUM> and the accommodation groove <NUM> of the mounting portion <NUM> are coupled to each other, the connection portion <NUM> may be easily mounted on the mounting portion <NUM>, and furthermore, a contact area may be effectively increased to reduce an electrical resistance and increase electrical connection reliability.

<FIG> is a perspective view schematically showing some components of a battery module, according to an embodiment of the present invention. Here, to look into an internal structure of the upper case 210A, one of the plurality of cylindrical battery cells <NUM> is excluded in the drawing.

Referring to <FIG> with <FIG>, a fixing structure for pressing against and fixing a lateral surface of the cylindrical battery cells <NUM> may be formed in an inner surface of the first accommodation portion 212A of the module housing <NUM>, the inner surface facing the lateral surface of the cylindrical battery cell <NUM>.

For example, the fixing structure may be a convex portion <NUM> protruding from the inner surface of the first accommodation portion 212A in a horizontal direction where the cylindrical battery cell <NUM> is positioned (inward direction), to press an outer side surface of the cylindrical battery cell <NUM>.

Accordingly, according to this configuration of the present invention, the convex portion <NUM> may effectively prevent an electrical short circuit between the cylindrical battery cells <NUM> and the bus bar <NUM> due to vibration or flow due to an external impact applied to the battery module <NUM>, and also, damage to the cylindrical battery cells <NUM> due to vibration may be reduced effectively.

<FIG> is a perspective view schematically illustrating a battery pack according to an embodiment of the present invention.

Referring to <FIG> with <FIG>, a battery pack <NUM> according to the present invention may include at least two battery modules <NUM>. In detail, the at least two battery modules <NUM>, <NUM>, <NUM>, and <NUM> may be arranged and aligned in a direction. For example, as illustrated in <FIG>, four battery modules <NUM>, <NUM>, <NUM>, and <NUM> may be arranged and aligned in the back and forth direction, and the four battery modules <NUM>, <NUM>, <NUM>, and <NUM> may be serially and electrically connected to each other via the first bus bar 250A and the second bus bar 250B.

Also, the battery module <NUM> may include an external input/output terminal <NUM> electrically connected to a third bus bar 250D. Moreover, unlike the first bus bar 250A illustrated in <FIG>, the third bus bar 250D of the battery module <NUM> may include a downwardly bent portion E that is bent downwards such that the third bus bar 250D is electrically contacted by and connected to the external input/output terminal <NUM>.

Accordingly, according to this configuration of the present invention, the third bus bar 250D including the downwardly bent portion E may establish electrical connection with respect to the external input/output terminal <NUM> by using a simple structure, and thus, the time for an assembly process may be reduced.

Referring back to <FIG>, the battery pack <NUM> according to the present invention may further include, in addition to the battery module <NUM>, various devices for controlling charging and discharging of the battery module <NUM>, such as a battery management system (BMS), a current sensor, a fuse, etc..

Also, the battery pack <NUM> according to the present invention may be applied to an energy storage device or a vehicle such as an electric vehicle or a hybrid vehicle. In other words, the vehicle according to the present invention may include the battery pack <NUM>.

Meanwhile, in the present specification, the terms indicating directions, such as up, down, left, right, front, and back, are used but it would be obvious to one of ordinary skill in the art that the terms are used only for convenience of description and may vary according to a position of a target object, a position of an observer, or the like.

Claim 1:
A battery module (<NUM>, <NUM>, <NUM>, <NUM>) comprising:
a plurality of cylindrical battery cells (<NUM>) including electrode terminals (<NUM>, <NUM>) respectively formed at a top and a bottom of the plurality of cylindrical cells, the plurality of cylindrical battery cells (<NUM>) being arranged in columns and rows in a horizontal direction;
a module housing (<NUM>) including an accommodation portion having a plurality of hollow structures to accommodate the plurality of cylindrical battery cells (<NUM>) inserted into the module housing (<NUM>); and
a bus bar configured to contact the electrode terminals (<NUM>, <NUM>) of the plurality of cylindrical battery cells (<NUM>) to electrically connect between the plurality of cylindrical battery cells (<NUM>),
wherein the bus bar comprises:
a main body portion (<NUM>) that is positioned at a top or a bottom of the plurality of cylindrical battery cells (<NUM>) and has a plate shape having upper and lower surfaces that are broader than a lateral surface of the main body portion (<NUM>) in a horizontal direction; and
a contact portion (<NUM>) that is configured to electrically contact and be connected to an electrode terminal (<NUM>, <NUM>) formed in one of the plurality of cylindrical battery cells (<NUM>), extends and protrudes from the main body portion (<NUM>) in a horizontal direction, is stepped from the main body portion (<NUM>) in a direction toward where the electrode terminal (<NUM>, <NUM>) is positioned,
characterized in that the contact portion includes a branched structure (256n) bifurcated in two directions with respect to a direction in which the contact portion (<NUM>) extends and protrudes from the main body portion (<NUM>), wherein an embossed protrusion (<NUM>) protruding toward where the electrode terminal (<NUM>, <NUM>) is positioned is formed in the branched structure (256n), and a contact area is set to allow a welding rod (<NUM>) to establish electrical connection around the embossed protrusion (<NUM>) in the branched structure (256n).