Patent Description:
A secondary battery is highly applicable to various products and has electrical characteristics with high energy density. The secondary battery is applied not only to portable electronic devices but also to electric vehicles, hybrid electric vehicles, power storage devices, and the like, driven by an electric driving source.

The secondary battery is attracting attention as a new energy source for improving eco-friendliness and energy efficiency since the use of fossil fuels is significantly reduced and no by-product is generated during the use of energy.

A secondary battery pack applied to an electric vehicle is configured such that a plurality of secondary battery packs, each having a plurality of secondary battery cells, are electrically connected to each other to obtain a high output. In addition, each secondary battery cell includes positive and negative electrode current collectors, a separator, an active material, an electrolyte, and the like as an electrode assembly, and may be repeatedly charged and discharged by an electrochemical reaction between the components.

Meanwhile, with the recent utilization as an energy storage source and the increased need for a large capacity structure, the demand for the secondary battery pack in which a plurality of secondary battery cells are connected in series and/or in parallel is increasing.

Moreover, in recent years, even a small secondary battery pack tends to have a high output and a high capacity due to the demand of consumers.

However, if a plurality of secondary battery cells are mounted in one small secondary battery pack, the density of secondary battery cells is very high due to a limited space. Also, since the amount of heat generated from the secondary battery cell is proportional to the square of the current, the temperature of the secondary battery cell tends to rapidly increase during high rate discharge.

Further, it is important for the small secondary battery pack to easily dissipate heat generated in each secondary battery cell. That is, if heat generated in the charging and discharging process is not effectively removed, thermal accumulation may occur. Accordingly, battery cells exposed to a high temperature environment in the long term are deteriorated faster, thereby rapidly decreasing a lifespan of the secondary battery pack. A secondary battery pack is disclosed in <CIT>, <CIT> and in <CIT>.

Therefore, there is a need for an effective cooling technology to increase the life characteristics of the secondary battery pack.

The present disclosure is designed to solve the problems of the related art, and therefore the present disclosure is directed to providing a secondary battery pack, which includes a plurality of cylindrical battery cells with improved cooling efficiency.

Also, it will be easily understood that the objects and advantages of the present disclosure may be realized by the means shown in the appended claims.

According to the invention there is provided a secondary battery pack according to claim <NUM>, an electronic device according to claim <NUM> and a power tool according to claim <NUM>. The scope of protection is defined in the appended claims.

In one aspect of the present disclosure, there is provided a secondary battery pack, comprising:.

Also, the heat transfer pad includes an upper pad formed to surround an upper portion of the plurality of cylindrical battery cells and a lower pad formed to surround a lower portion of the plurality of cylindrical battery cells.

Moreover, the upper pad and the lower pad respectively have a curved portion having a protruding structure protruding in an inner direction of the secondary battery pack to be interposed between the plurality of cylindrical battery cells and a recess structure dented in an outer direction of the secondary battery pack.

In addition, the plurality of cylindrical battery cells may be spaced apart from each other by a predetermined distance and arranged in one direction.

Further, the protruding structures of the curved portions respectively provided to the upper pad and the lower pad may be located to face each other and partially connected to each other.

Also, a convex portion formed at a location corresponding to the protruding structure of the curved portion and ridged in the inner direction of the secondary battery pack is formed at an inner surface of the heat dissipation plate.

Moreover, an insert portion dented in the inner direction of the secondary battery pack is formed at an outer surface of the heat transfer pad facing the heat dissipation plate so that the convex portion is inserted therein.

In addition, the pack case may include an upper case and a lower case at which the exposing portion is formed, respectively.

Further, the upper case may have an inner structure formed to accommodate and cover the upper portion of the plurality of cylindrical battery cells therein.

Also, the lower case may have an upper surface coupled to a lower surface of the upper case and have an inner structure formed to accommodate and cover the lower portion of the plurality of cylindrical battery cells.

Moreover, the heat dissipation plate may include a first heat dissipation plate and a second heat dissipation plate, and an insert groove dented inward may be formed at an inner side of the exposing portion of each of the upper case and the lower case so that an outer periphery of each of the first heat dissipation plate and the second heat dissipation plate is inserted and fixed therein.

In addition, a support portion protruding outward may be formed at each of the upper pad and the lower pad to contact an inner surface of each of the first heat dissipation plate and the second heat dissipation plate.

Also, the outer periphery of the heat dissipation plate may be formed to have a greater plate thickness than a center portion of the heat dissipation plate.

Moreover, at least one rib may be formed at the exposing portion to extend from one side to the other side of an opening perforated in the exposing portion.

In addition, the secondary battery pack may further comprise a connection bus bar provided in contact with the electrode terminals formed at the plurality of cylindrical battery cells to electrically connect the plurality of cylindrical battery cells.

Further, the heat transfer pad may have an extending portion extending outward to cover a bonding portion between the connection bus bar and the electrode terminals of the plurality of cylindrical battery cells.

Also, a placing member may be formed at the accommodation portion of the pack case so that the plurality of cylindrical battery cells are mounted thereto, and a plurality of concave structures dented corresponding to an outer shape of ends of the plurality of cylindrical battery cells at which the electrode terminals are provided may be formed at the placing member.

Further, in another aspect of the present disclosure, there is also provided an electronic device, comprising the secondary battery pack.

In addition, in still another aspect of the present disclosure, there is also provided a power tool, comprising the secondary battery pack.

According to an embodiment of the present disclosure, since the secondary battery pack of the present disclosure includes a heat dissipation plate and a pack case having an exposing portion for exposing at least a portion of the heat dissipation plate to the outside, it is possible to effectively dissipate the heat generated at the cylindrical battery cells to the outside.

Also, according to an embodiment of the present disclosure, since the heat transfer pad made of a thermal conductive material is interposed between the plurality of cylindrical battery cells and the heat dissipation plate, the heat generated from the plurality of cylindrical battery cells accommodated inside the secondary battery pack may be effectively transferred to the heat dissipation plate through the heat transfer pad. Accordingly, the cooling effect of the secondary battery pack may be maximized.

Moreover, according to another embodiment of the present disclosure, since the protruding structures of the curved portions respectively provided to the upper pad and the lower pad of the present disclosure are positioned to face each other and are formed to be partially connected to each other, the contact area of the heat transfer pads surrounding the outer surfaces of the cylindrical battery cells may be increased. Also, since the gap between the plurality of cylindrical battery cells may be filled with the heat transfer pad, it is possible to prevent the cylindrical battery cells from being overheated due to stagnant heat caused by the air in the gap.

In addition, according to still another embodiment of the present disclosure, since a convex portion is formed at the inner surface of the heat dissipation plate, the heat transfer path between the heat transfer pad and the heat dissipation plate may have a uniform length. That is, a cylindrical battery cell located at the center among the plurality of cylindrical battery cells may be more easily deteriorated since heat is accumulated more therein compared to cylindrical battery cells located relatively outside. Accordingly, since the convex portion is formed at the heat dissipation plate of the present disclosure, it is possible to increase the heat dissipation speed of the cylindrical battery cell located at the center, thereby effectively achieving heat balance between the plurality of cylindrical battery cells. Also, this may effectively extend the lifespan of secondary battery pack.

Also, according to still another embodiment of the present disclosure, since the heat dissipation plate is inserted into and fixed to the insert groove formed at the inner surface of the exposing portion of the pack case, the heat dissipation plate may be fixed without a separate fixing member. Accordingly, the material cost is reduced when manufacturing the secondary battery pack. In addition, since the heat dissipation plate inserted into the pack case is not easily separated even when an external shock is applied to the secondary battery pack, the durability of the secondary battery pack may be greatly improved.

Moreover, according to still another embodiment of the present disclosure, if the outer periphery of the heat dissipation plate formed relatively thicker than the center portion thereof has a shape inserted into the pack case, the rigidity of the pack case may be reinforced. That is, since the outer periphery of the heat dissipation plate is configured to support the inside of the pack case, it is possible to effectively prevent the pack case from deforming due to an external pressure. Further, the heat dissipation plate may increase the heat capacity for absorbing heat as much as the size of the thickened outer periphery. Also, the contact area with the pack case is increased, thereby effectively dissipating the heat generated from the plurality of cylindrical battery cells.

In addition, according to still another embodiment of the present disclosure, since at least one rib is formed at the exposing portion of the pack case, the rigidity of the exposing portion of the pack case may be reinforced, and a user may be prevented from directly contacting the heat dissipation plate located at the exposing portion of the pack case. Accordingly, the user of the secondary battery pack may be prevented from being burned while using the secondary battery pack, thereby increasing the safety of the secondary battery pack.

Furthermore, according to still another embodiment of the present disclosure, since the heat transfer pad has a extending portion extending outward to cover a portion where the connection bus bar and the electrode terminals of the plurality of cylindrical battery cells are bonded to each other, the heat generated at the bonded portion of the connection bus bar and the electrode terminal, which has relatively higher heat generation, may be effectively transferred to the heat dissipation plate through the extending portion. Accordingly, the cooling effect of the secondary battery pack may be further increased.

Therefore, the description proposed herein is just a preferable example for the purpose of illustrations only, not intended to limit the scope of the disclosure.

<FIG> is a perspective view schematically showing a secondary battery pack according to an embodiment of the present disclosure. Also, <FIG> is an exploded perspective view schematically showing some components of the secondary battery pack according to an embodiment of the present disclosure.

Referring to <FIG> and <FIG>, a secondary battery pack <NUM> according to the present disclosure includes a plurality of cylindrical battery cells <NUM>, a pack case <NUM>, at least one heat dissipation plate <NUM> and a heat transfer pad <NUM> and may further include a connection 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> may include a material with high electrical conductivity. For example, the battery can <NUM> may include aluminum or copper.

In addition, when viewed in the F direction, electrode terminals <NUM>, <NUM> may be formed at both left and right ends of the battery can <NUM>. Specifically, a first electrode terminal <NUM> may be formed at a flat circular one end surface of one end of the battery can <NUM>, and a second electrode terminal <NUM> may be formed at the other flat circular end surface of the other end of the battery can <NUM>.

Moreover, an electrode assembly (not shown) may be formed in a structure where a positive electrode and a negative electrode are wound in a j elly-roll form with a separator being interposed therebetween. In addition, a positive electrode tab may be attached to the positive electrode (not shown) and connected to the first electrode terminal <NUM> at one end of the battery can <NUM>. Further, a negative electrode tab may be attached to the negative electrode (not shown) and connected to the second electrode terminal <NUM> at the other end of the battery can <NUM>.

Further, the plurality of cylindrical battery cells <NUM> may be spaced apart from each other by a predetermined distance and arranged in one direction. For example, as shown in <FIG>, when viewed in the F direction, the first electrode terminal <NUM> and the second electrode terminal <NUM> of the plurality of cylindrical battery cells <NUM> may be disposed at both left and right ends. In addition, the plurality of cylindrical battery cells <NUM> may be arranged to be spaced apart from each other by a predetermined distance in the front and rear direction.

Specifically, the connection bus bar <NUM> may include a connection portion 140a elongated in one direction and a bending portion 140b bent and extending from the connection portion 140a. Further, an external input/output terminal <NUM> may be formed at an end of the bending portion 140b of the connection bus bar <NUM>, which is exposed out of the pack case <NUM>. In addition, the external input/output terminal <NUM> may have a cylindrical shape protruding outward.

Further, the connection bus bar <NUM> may electrically connect the plurality of cylindrical battery cells <NUM> to each other. Also, for this purpose, the connection portion 140a of the connection bus bar <NUM> may be configured to contact the first electrode terminal <NUM> or the second electrode terminal <NUM> formed at the plurality of cylindrical battery cells <NUM>.

Further, the connection bus bar <NUM> may be configured to contact the electrode terminals <NUM>, <NUM> of the plurality of cylindrical battery cells <NUM> to electrically connect the electrode terminals <NUM>, <NUM> to each other. In this case, the connection bus bar <NUM> may include a metal with excellent electrical conductivity. For example, the connection bus bar <NUM> may include nickel, gold, aluminum, copper, or a combination thereof.

Specifically, the connection bus bar <NUM> may have one end in contact with the first electrode terminal <NUM> of one cylindrical battery cell <NUM> and the other end in contact with the second electrode terminal <NUM> of another cylindrical battery cell <NUM> so that the first electrode terminal <NUM> of one cylindrical battery cell <NUM> and the second electrode terminal <NUM> of another cylindrical battery cell <NUM> are electrically connected to each other.

For example, as shown in <FIG>, three connection bus bars <NUM> may be provided to electrically connect the first electrode terminal <NUM> of one cylindrical battery cell <NUM> and the second electrode terminal <NUM> of another cylindrical battery cell <NUM>.

Also, the connection bus bar <NUM> may be configured such that a portion of the connection portion 140a is in contact with the electrode terminal <NUM> of one cylindrical battery cell <NUM> and the other portion of the connection portion 140a is in contact with the first electrode terminal <NUM> of another cylindrical battery cell <NUM>, to electrically connect the first electrode terminal <NUM> of one cylindrical battery cell <NUM> and the first electrode terminal <NUM> of another cylindrical battery cell <NUM>.

Moreover, the connection bus bar <NUM> may have one end in contact with the second electrode terminal <NUM> of the one cylindrical battery cell <NUM> and the other end in contact with the second electrode terminal <NUM> of another cylindrical battery cell <NUM> so that the second electrode terminal <NUM> of one cylindrical battery cell <NUM> and the second electrode terminal <NUM> of another cylindrical battery cell <NUM> are electrically connected.

Further, the connection bus bar <NUM> may be located to face one end surface or the other end surface of the cylindrical battery cell <NUM> at which the first electrode terminal <NUM> or the second electrode terminal <NUM> is formed. For example, as shown in <FIG>, two connection bus bars <NUM> may be provided to electrically connect four cylindrical battery cells <NUM> in series. Also, the connection portion 140a of one connection bus bar <NUM> may be located at one side to face the first electrode terminal <NUM> of the plurality of cylindrical battery cells <NUM>. The other connection bus bar <NUM> may be located at the other side to face the second electrode terminal <NUM> of the plurality of cylindrical battery cells <NUM>.

Meanwhile, the pack case <NUM> may be configured in an integrated form. Alternatively, the pack case <NUM> may be configured by coupling two members. Also, the pack case <NUM> has an accommodation portion <NUM> in which an empty space is formed to accommodate components such as the cylindrical battery cells <NUM>. For example, as shown in <FIG>, the accommodation portion <NUM> may be formed to have an empty space such that four cylindrical battery cells <NUM> may be accommodated in the pack case <NUM>.

Moreover, the accommodation portion <NUM> of the pack case <NUM> may have a placing member 123a on which the plurality of cylindrical battery cells <NUM> are mounted. In addition, a plurality of concave structures having a dented shape may be formed at the placing member 123a so as to correspond to the outer shape of the ends of the plurality of cylindrical battery cells <NUM> where the electrode terminals <NUM> are formed.

Thus, according to this configuration of the present disclosure, since the placing member 123a having a plurality of concave structures are formed at the accommodation portion <NUM> of the pack case <NUM>, it is possible to prevent the plurality of cylindrical battery cells <NUM> from moving due to an external impact, thereby reducing a contact failure or a disconnection with the connection bus bar <NUM> caused by frequent fluctuations.

Moreover, the pack case <NUM> includes at least one exposing portion <NUM> having an opening <NUM> performed therein from an inside to an outside. Specifically, the exposing portion <NUM> is perforated at an outer side the pack case <NUM>. For example, as shown in <FIG>, when viewed in the F direction, the exposing portion <NUM> may be formed at an upper portion and a lower portion of the pack case <NUM>, respectively.

Further, referring to <FIG> again, the pack case <NUM> may include an upper case <NUM> and a lower case <NUM> at which the exposing portion <NUM> is formed, respectively. Also, the upper case <NUM> may have an inner structure formed to accommodate and cover the upper portion of the plurality of cylindrical battery cells <NUM> therein. Further, the lower case <NUM> may have an upper surface that is coupled with a lower surface of the upper case <NUM>. In addition, the lower case <NUM> may have an inner structure formed to accommodate and cover the lower portion of the plurality of cylindrical battery cells <NUM> therein.

Here, the terms indicating directions such as front, rear, left, right, upper and lower directions may be changed depending on the position of an observer or the shape of an object. For the sake of convenience of description, in the present specification, directions are classified into front, rear, left, right, upper and lower directions, based on the F direction.

For example, as shown in <FIG>, the pack case <NUM> includes an upper case <NUM> and a lower case <NUM>. Also, the exposing portion <NUM> perforated from the inside to the outside may be formed at an upper portion of the upper case <NUM>. Further, the exposing portion <NUM> perforated from the inside to the outside may be formed at a lower portion of the lower case <NUM>. In addition, the lower portion of the upper case <NUM> and the upper portion of the lower case <NUM> may be coupled to each other.

Meanwhile, the heat dissipation plate <NUM> may be fixedly positioned at the pack case <NUM> of the present disclosure. Specifically, the heat dissipation plate <NUM> may be configured in the form of a metal plate. Also, the metal may be a metal with excellent thermal conductivity. For example, the metal may be copper, aluminum, copper alloy, or aluminum alloy.

In addition, the heat dissipation plate <NUM> is located at the exposing portion <NUM> of the pack case <NUM>. That is, the heat dissipation plate <NUM> is configured such that at least a portion thereof is exposed to the outside through the exposing portion <NUM> of the pack case <NUM>. For example, as shown in <FIG>, the heat dissipation plate <NUM> may have a rectangular plate shape with a size and shape corresponding to an opening <NUM> perforated in the exposing portion <NUM> of the pack case <NUM>.

Also, as shown in <FIG>, the pack case <NUM> may include an upper case <NUM> and a lower case <NUM>. Further, the upper case <NUM> and the lower case <NUM> may have the exposing portion <NUM> perforated from the inside to the outside, respectively. In addition, the first heat dissipation plate <NUM> and the second heat dissipation plate <NUM> may be located at the exposing portions <NUM>, respectively, such that the first heat dissipation plate <NUM> and the second heat dissipation plate <NUM> having a rectangular plate shape are partially exposed to the outside through the opening <NUM>.

Thus, according to this configuration of the present disclosure, by using the heat dissipation plate <NUM> and the exposing portion <NUM> of the pack case <NUM> capable of exposing at least a portion of the heat dissipation plate <NUM> to the outside, the heat generated from the cylindrical battery cell <NUM> may be effectively dissipated to the outside.

<FIG> is a side view schematically showing some components of the secondary battery pack according to an embodiment of the present disclosure.

Referring to <FIG> along with <FIG>, the heat transfer pad <NUM> may be in a solid state. For example, the heat transfer pad <NUM> may be prepared by processing a thermally conductive polymer material in a liquid state into a predetermined shape and then curing the same. In addition, the heat transfer pad <NUM> may be configured to be interposed between the plurality of cylindrical battery cells <NUM> and the heat dissipation plate <NUM>. Further, the heat transfer pad <NUM> may have configured such that one surface thereof contacts the inner surface of the heat dissipation plate <NUM>. In addition, the other surface of the heat transfer pad <NUM> may be formed to surround a portion of the outer surface of the plurality of cylindrical battery cells <NUM>.

Specifically, the heat transfer pad <NUM> includes an upper pad <NUM> formed to surround an upper portion of the plurality of cylindrical battery cells <NUM> and a lower pad <NUM> formed to surround a lower portion of the plurality of cylindrical battery cells <NUM>. For example, as shown in <FIG>, the upper pad <NUM> may be formed to be interposed between the first heat dissipation plate <NUM> and the plurality of cylindrical battery cells <NUM>. In addition, the lower pad <NUM> may be formed to be interposed between the second heat dissipation plate <NUM> and the plurality of cylindrical battery cells <NUM>.

In addition, the upper pad <NUM> and the lower pad <NUM> respectively have a curved portion <NUM> having a protruding structure P1 protruding in an inner direction of the secondary battery pack <NUM> so as to be interposed between the plurality of cylindrical battery cells <NUM> and a recess structure U1 dented in an outer direction of the secondary battery pack <NUM>.

More specifically, the protruding structure P1 may be shaped to partially fill the gap between the plurality of cylindrical battery cells <NUM>. For example, the protruding structure P1 may be formed to have a width gradually decreasing in the protruding direction, and an outer surface of the protruding structure P1 may have a plane.

In addition, the recess structure U1 of the curved portion <NUM> formed at each of the upper pad <NUM> and the lower pad <NUM> may have an arched structure. For example, as shown in <FIG>, the curved portion <NUM> having three protruding structures P1 and four arched recess structures U1 may be formed at four spots in each of the upper pad <NUM> and the lower pad <NUM>.

Also, the heat transfer pad <NUM> may include a material with high thermal conductivity at least partially. Here, the heat transfer pad <NUM> may include a polymer resin, a silicone-based resin or a filler with high thermal conductivity. For example, the polymer resin may be a polysiloxane resin, a polyamide resin, a urethane resin, or an epoxy resin. Moreover, the silicone resin means an artificial polymer compound having a main skeleton by siloxane bonds. For example, as shown in <FIG>, the upper pad <NUM> and the lower pad <NUM> may be in a form where the silicone resin with high thermal conductivity is cured.

Thus, according to this configuration of the present disclosure, since the heat transfer pad <NUM> made of the thermally conductive material is interposed between the plurality of cylindrical battery cells <NUM> and the heat dissipation plate <NUM>, the heat generated from the plurality of cylindrical battery cells <NUM> accommodated in the secondary battery pack <NUM> may be effectively transferred to the heat dissipation plate <NUM> through the heat transfer pad <NUM>. Accordingly, the cooling effect of the secondary battery pack <NUM> may be maximized.

<FIG> is a side view schematically showing some components of a secondary battery pack according to another embodiment of the present disclosure.

Referring to <FIG>, a secondary battery pack <NUM> according to another embodiment of the present disclosure may include a heat transfer pad 150B having a different shape from the heat transfer pad <NUM> of <FIG>. Specifically, the heat transfer pad 150B may have a curved portion 153B respectively provided to the upper pad 151B and the lower pad 155B. In this case, the protruding structures P1 of the curved portions 153B respectively provided to the upper pad 151B and the lower pad 155B may be located to face each other. Also, the protruding structures P1 respectively formed at the upper pad 151B and the lower pad 155B may be shaped to partially contact each other. That is, the upper pad 151B and the lower pad 155B may be connected to each other to have an integrated form.

For example, as shown in <FIG>, the heat transfer pad 150B may have an integrated form where the protruding structures P1 of the curved portions 153B respectively provided to the upper pad 151B and the lower pad 155B are connected to each other.

Thus, according to this configuration of the present disclosure, since the protruding structures P1 of the curved portions 153B respectively provided to the upper pad 151B and the lower pad 155B of the present disclosure are located to face each other and are shaped to be partially connected to each other, the contact area of the heat transfer pad 150B surrounding the outer surface of the plurality of cylindrical battery cells <NUM> may be increased. Moreover, since the gap between the plurality of cylindrical battery cells <NUM> may be filled with the heat transfer pad 150B, it is possible to prevent the plurality of cylindrical battery cells <NUM> from being locally overheated due to the heat stagnant by the air in the gap.

<FIG> is a side view schematically showing some components of a secondary battery pack according to still another embodiment of the present disclosure.

Referring to <FIG>, a secondary battery pack <NUM> according to another embodiment of the present disclosure may include a heat dissipation plate 130C having a different shape from the heat dissipation plate <NUM> of <FIG>. Specifically, the heat dissipation plate 130C has a convex portion <NUM> ridged in the inner direction of the secondary battery pack <NUM>. Also, the convex portion <NUM> is formed at a location corresponding to the protruding structure P1 of the curved portion <NUM> of the heat transfer pad <NUM>, at an inner surface of the heat dissipation plate 130C. Further, an insert portion <NUM> dented in the inner direction of the secondary battery pack <NUM> is formed at the outer surface of the heat transfer pad <NUM> facing the heat dissipation plate 130C such that the convex portion <NUM> is inserted therein.

Moreover, the convex portion <NUM> may have a shape corresponding to the curved portion <NUM>. That is, the convex portion <NUM> may have a protruding structure and a recess structure similar to the curved portion <NUM>.

For example, as shown in <FIG>, the secondary battery pack according to another embodiment of the present disclosure may include a first heat dissipation plate 131C and a second heat dissipation plate 135C. Also, three convex portions <NUM> ridged in the inner direction of the secondary battery pack <NUM> may be formed at the inner surfaces of the first heat dissipation plate 131C and the second heat dissipation plate 135C, respectively. Further, the convex portions <NUM> may be formed at locations of the upper pad <NUM> and the lower pad <NUM> corresponding to the protruding structures P1 of the curved portions <NUM>, respectively.

Thus, according to this configuration of the present disclosure, since the convex portion <NUM> is formed at the inner surface of the heat dissipation plate 130C, the length of the heat transfer path between the heat transfer pad <NUM> and the heat dissipation plate 130C may be made uniform. That is, a cylindrical battery cell <NUM> located at the center among the plurality of cylindrical battery cells <NUM> may be more easily degraded since heat may be accumulated more in the cylindrical battery cell <NUM> located at the center, compared to a cylindrical battery cell <NUM> located at a relatively outer side. Accordingly, by forming the convex portion <NUM> at the heat dissipation plate 130C of the present disclosure, it is possible to reduce the heat transfer distance between the cylindrical battery cell <NUM> located at the center and the heat dissipation plate 130C, thereby increasing the heat dissipation rate. Accordingly, heat balance may be achieved effectively between the plurality of cylindrical battery cells <NUM>, and the lifespan of the secondary battery pack <NUM> may be effectively increased.

<FIG> is an exploded perspective view schematically showing some components of the secondary battery pack according to another embodiment of the present disclosure. <FIG> is a perspective view schematically showing a secondary battery pack according to another embodiment of the present disclosure. Also, <FIG> is a cross-sectioned view schematically showing the secondary battery pack, taken along the line C-C' of <FIG>.

Referring to <FIG>, the heat dissipation plate <NUM> may include a first heat dissipation plate <NUM> and a second heat dissipation plate <NUM>. In addition, an insert groove <NUM> dented inward may be formed at an inner side of the exposing portion <NUM> of each of the upper case 121D and the lower case 125D. Specifically, the insert groove <NUM> may have a dented size such that the outer periphery of each of the first heat dissipation plate <NUM> and the second heat dissipation plate <NUM> is inserted and fixed therein.

For example, as shown in <FIG>, the insert groove <NUM> may be formed at the inner side of the exposing portion <NUM>. The insert groove <NUM> may be formed to extend along an inner periphery 127D of the perforated exposing portion <NUM>. Further, as shown in <FIG>, an outer periphery of each of the first heat dissipation plate <NUM> and the second heat dissipation plate <NUM> may be inserted into the insert groove <NUM> formed at each of the upper case 121D and the lower case 125D.

In this case, the first heat dissipation plate <NUM> and the second heat dissipation plate <NUM> may be formed to be inserted into the upper case 121D and the lower case 125D, respectively, by means of insert injection molding. For example, if the upper case 121D and the lower case 125D of the pack case 120D are manufactured by casting, the heat dissipation plate <NUM> is disposed in a mold in advance, and a molten material of the pack case 120D (e.g., a plastic polymer resin) is injected thereto and cured, thereby manufacturing the heat dissipation plate <NUM> inserted into the pack case 120D.

Thus, according to this configuration of the present disclosure, since the heat dissipation plate <NUM> is inserted and fixed in the insert groove <NUM> formed at the inner surface of the exposing portion <NUM> of the pack case 120D, the heat dissipation plate <NUM> may be fixed without a separate fixing member, thereby reducing the material cost. In addition, since the heat dissipation plate <NUM> is inserted into the pack case 120D and thus is not easily separated due to an external shock, the durability of the secondary battery pack <NUM> may be greatly improved.

Also, the heat transfer pad 150D of <FIG> may have a different shape from the heat transfer pad <NUM> of <FIG>. Specifically, the heat transfer pad 150D may include an upper pad 151D and a lower pad 155D. In addition, a support portion 156D protruding outward to contact the inner surface of the heat dissipation plate <NUM> is formed at the upper pad 151D and the lower pad 155D, respectively. Further, the support portion 156D may have a size corresponding to the size of the outer surface of the heat dissipation plate <NUM> exposed through the opening <NUM> of the exposing portion <NUM>.

For example, as shown in <FIG>, the heat transfer pad 150D may include an upper pad 151D and a lower pad 155D. In addition, support portions 156D protruding outwardly to respectively contact the inner surfaces of the first heat dissipation plate <NUM> and the second heat dissipation plate <NUM> may be formed at the upper pad 151D and the lower pad 155D, respectively.

Thus, according to this configuration of the present disclosure, since the support portion 156D configured to contact the inner surface of the heat dissipation plate <NUM> is formed at the heat transfer pad 150D of the present disclosure, no empty space may be formed between the heat dissipation plate <NUM> and the heat transfer pad 150D, thereby not deteriorating the cooling efficiency of the secondary battery pack.

<FIG> is a perspective view schematically showing a heat dissipation plate, employed at the secondary battery pack according to another embodiment of the present disclosure. Also, <FIG> is a cross-sectioned view schematically showing a secondary battery pack according to still another embodiment of the present disclosure as in <FIG>.

Referring to <FIG>, an outer periphery <NUM> of the heat dissipation plate 130E may have a greater plate thickness in the vertical direction W compared to the center portion <NUM> of the heat dissipation plate 130E. Also, the outer periphery <NUM> of the heat dissipation plate 130E may have a shape inserted into the pack case <NUM> through the insert groove 127h2.

Specifically, the heat dissipation plate 130E may have a rectangular plate shape as a whole. In addition, the outer periphery <NUM> of the heat dissipation plate 130E may have a great thickness that is <NUM> to <NUM> times or less compared to the center portion <NUM>. Further, a step may be formed between the outer periphery <NUM> and the center portion <NUM> of the heat dissipation plate 130E due to the thickness difference.

For example, as shown in <FIG>, the outer periphery <NUM> of the heat dissipation plate 130E may have a greater plate thickness than the center portion <NUM>. Also, the outer periphery <NUM> of the heat dissipation plate 130E may have a rectangular frame shape where the center portion <NUM> is blocked.

Thus, according to this configuration of the present disclosure, if the outer periphery <NUM> of the heat dissipation plate 130E formed relatively thicker than the center portion <NUM> has a shape inserted into the pack case <NUM>, the rigidity of the pack case <NUM> may be reinforced. That is, since the outer periphery <NUM> of the heat dissipation plate 130E is configured to support the inside of the pack case <NUM>, it is possible to effectively prevent the pack case <NUM> from deforming due to external pressure.

Further, the heat dissipation plate 130E may increase the heat capacity to absorb heat as much as the size of the thickened outer periphery <NUM>. Also, since the contact area of the heat dissipation plate 130E with the pack case <NUM> is increased, the heat generated from the plurality of cylindrical battery cells <NUM> may be effectively dissipated.

<FIG> is a perspective view schematically showing a secondary battery pack according to another embodiment of the present disclosure.

Referring to <FIG>, the pack case 120F of <FIG> may have a different shape form the pack case <NUM> of <FIG>.

Specifically, the pack case 120F may include an upper case 121F and a lower case 125F. Also, the upper case 121F and the lower case 125F of the pack case 120F may have at least one exposing portion 127F perforated from the inside to the outside. Further, the exposing portion 127F may be formed at an upper side or a lower side of the pack case 120F. For example, as shown in <FIG>, the exposing portion 127F may be formed at the upper case 121F and the lower case 125F of the pack case 120F, respectively, when viewed in the F direction.

In addition, at least one rib 128r extending from one side to the other side of the perforated opening <NUM> may be formed at the exposing portion 127F. Further, if a plurality of ribs 128r are formed, the plurality of ribs 128r may be spaced apart from each other by a predetermined distance. Also, the plurality of ribs 128r may be formed with an area less than <NUM>% of the planar size of the opening <NUM> perforated in the exposing portion 127F of <FIG>.

For example, as shown in <FIG>, six ribs 128r extending from one side to the other side of the perforated opening <NUM> may be formed at the exposing portion 127F of the pack case 120F. Moreover, the area occupied by the six ribs 128r may be about <NUM>% of the size of the opening <NUM> perforated in the exposing portion 127F of <FIG>.

Thus, according to this configuration of the present disclosure, since at least one rib 128r is formed to extend from one side to the other side of the opening <NUM> perforated in the exposing portion 127F of the pack case 120F, the rigidity of the pack case 120F may be further reinforced, and also it is possible to prevent a user from directly contacting the heat dissipation plate <NUM> located at the exposing portion 127F of the pack case 120F. Accordingly result, the user of the secondary battery pack <NUM> may be prevented from being burned while using the secondary battery pack <NUM>, thereby increasing the safety of the secondary battery pack <NUM>.

<FIG> is a perspective view schematically showing some components of a secondary battery pack according to another embodiment of the present disclosure.

Referring to <FIG> along with <FIG>, a heat transfer pad <NUM> of the secondary battery pack <NUM> according to another embodiment of the present disclosure may include a cover portion 151a configured to cover the upper portion of the plurality of cylindrical battery cells <NUM> and an extending portion 151b extending in the horizontal direction from one side of the cover portion 151a. Specifically, the extending portion 151b may be formed to extend outward to cover a portion where the connection bus bar <NUM> and the electrode terminals <NUM> of the plurality of cylindrical battery cells <NUM> are bonded.

For example, as shown in <FIG>, the heat transfer pad <NUM> according to another embodiment may include a cover portion 151a configured to cover the upper portion of the plurality of cylindrical battery cells <NUM> and extending portions 151b respectively extending in a horizontal direction from both left and right ends of the cover portion 151a. Also, the extending portion 151b may be configured to extend outward and then bend downward again to cover the bonded portion of the connection bus bar <NUM> and the electrode terminals <NUM> of the plurality of cylindrical battery cells <NUM>.

Thus, according to this configuration of the present disclosure, since the heat transfer pad <NUM> includes the extending portion 151b extends outward to cover the portion where the connection bus bar <NUM> and the electrode terminals <NUM> of the plurality of cylindrical battery cells <NUM> are bonded, the heat generated at the bonded portion of the connection bus bar <NUM> and the electrode terminal <NUM> where a relatively great is generated may be effectively transferred to the heat dissipation plate <NUM> through the extending portion 151b. Accordingly, the cooling effect of the secondary battery pack <NUM> may be further enhanced.

In addition, an electronic device (not shown) according to the present disclosure may include the battery pack. For example, the battery pack may be accommodated in an exterior case of the electronic device. Also, the electronic device may be a moving means such as an electric bicycle.

Further, a power tool according to the present disclosure may include the secondary battery pack <NUM>. For example, the power tool may be an electric drill. Also, the secondary battery pack <NUM> may be coupled to a lower portion of the power tool.

Meanwhile, even though the terms indicating directions such as upper, lower, left, right, front and rear directions are used in the specification, it is obvious to those skilled in the art that these merely represent relative locations for convenience in explanation and may vary based on a location of an observer or an object.

Claim 1:
A secondary battery pack (<NUM>), comprising:
a plurality of cylindrical battery cells (<NUM>) having electrode terminals formed at both ends thereof;
a pack case (<NUM>) having an accommodation portion (<NUM>) formed to accommodate the plurality of cylindrical battery cells (<NUM>) therein and at least one exposing portion (<NUM>) perforated from an inside to an outside thereof;
at least one heat dissipation plate (<NUM>) configured in the form of a metal plate and located at the exposing portion (<NUM>) of the pack case (<NUM>) so that at least a portion thereof is exposed out through the exposing portion (<NUM>) of the pack case (<NUM>); and
a heat transfer pad (<NUM>) having a thermally conductive material in a solid state and interposed between the plurality of cylindrical battery cells (<NUM>) and the heat dissipation plate (<NUM>),
wherein the heat transfer pad (<NUM>) includes an upper pad (<NUM>) formed to surround an upper portion of the plurality of cylindrical battery cells (<NUM>) and a lower pad (<NUM>) formed to surround a lower portion of the plurality of cylindrical battery cells (<NUM>),
wherein the upper pad (<NUM>) and the lower pad (<NUM>) respectively have a curved portion (<NUM>) having a protruding structure (P1) protruding in an inner direction of the secondary battery pack (<NUM>) to be interposed between the plurality of cylindrical battery cells (<NUM>) and a recess structure (U1) dented in an outer direction of the secondary battery pack (<NUM>), and
wherein a convex portion (<NUM>) formed at a location corresponding to the protruding structure (P1) of the curved portion (<NUM>) and ridged in the inner direction of the secondary battery pack (<NUM>) is formed at an inner surface of the heat dissipation plate (<NUM>), and
wherein an insert portion (<NUM>) dented in the inner direction of the secondary battery pack (<NUM>) is formed at an outer surface of the heat transfer pad (<NUM>) facing the heat dissipation plate (<NUM>) so that the convex portion (<NUM>) is inserted therein.