Battery pack and method for fabricating the same

A battery pack and a method for fabricating the same are provided. The battery pack includes a plurality of battery cells connected in series or in parallel to each other, a protective circuit module (PCM) controlling charging and discharging of the plurality of battery cells, and a coverlay electrically connecting the plurality of battery cells to the PCM, wherein the coverlay includes a plurality of wires, each of the plurality of wires includes battery connecting pads provided at its one end, the battery connecting pads connected to the battery cells, and module connecting pads provided at it's the other end, the module connecting pads connected to the PCM, and a solder layer is formed on the battery connecting pads.

BACKGROUND

Embodiments relate to a battery pack and a method for fabricating the same.

2. Description of the Related Art

In recent years, as electronics, communications, and computers are rapidly developed, portable electronic devices are being widely used. In addition, rechargeable secondary batteries are typically being used as power sources of such portable electronic devices.

A secondary battery including a unitary battery cell may satisfactorily serve as a power source of small-sized electronic device, e.g., a mobile phone. However, in a medium- or large-sized electronic device, e.g., a notebook computer, an electric tool, or an electric bicycle, in order to offer sufficient output or capacity, a battery pack having a plurality of battery cells connected in series or in parallel to each other may be used.

SUMMARY

Embodiments are directed to a battery pack and a method for fabricating the same, which represent advances over the related art.

At least one of the above and other features and advantages may be realized by providing a battery pack including a plurality of battery cells connected in series or in parallel; a protective circuit module (PCM) for controlling charging and discharging of the plurality of battery cells; and a coverlay electrically connecting the plurality of battery cells to the PCM, wherein the coverlay includes a plurality of wires, each of the plurality of wires including module connecting pads provided at an end thereof, the module connecting pads being connected to the PCM, battery connecting pads provided at another end thereof, the battery connecting pads being connected to the battery cells and including a solder layer thereon.

The coverlay may be a flexible printed circuit board (FPCB) including the wires.

The coverlay may include an adhesive layer on a surface thereof, the adhesive layer being for adhering the coverlay to the plurality of battery cells.

The coverlay may surround the plurality of wires to insulate the wires, and may include an insulating layer having a module connecting pad opening and a battery connecting pad opening, the module connecting pads being exposed through the module connecting pad opening and the battery connecting pads being exposed through the battery connecting pad opening.

The battery pack may further include electrode tabs electrically connecting the battery connecting pads and respective positive and negative electrode terminals of the battery cells, wherein the coverlay includes at least one through-hole at a position corresponding to at least one of the electrode tabs through which the at least one electrode tab passes.

Each of the electrode tabs may include a battery contact portion connected to the positive electrode terminal or the negative electrode terminal of the battery cells, a pad contact portion connected to each of the battery connecting pads, and a bent portion between the battery contact portion and the pad contact portion, the bent portion being configured to facilitate bending of the battery contact portion and the pad contact portion at a predetermined position.

Each of the electrode tabs may include a solder receiving hole, the solder receiving hole accommodating solder from the solder layer when the pad contact portion and the battery connecting pad are welded to each other.

An internal space and an entrance of the solder receiving hole may be covered by the solder.

The bent portion may include an area at which a width of the battery contact portion is different from a width of the pad contact portion.

The bent portion may include at least one notch on at least one lateral side or on at least one surface of the electrode tab.

The bent portion may include at least two notches on opposite lateral sides or opposite lateral surfaces of the electrode tab.

The plurality of battery cells may include a total number of battery cells and a number of the wires may be one greater than the total number of the battery cells.

At least one of the above and other features and advantages may also be realized by providing a method for manufacturing a battery pack including connecting a plurality of battery cells in series or in parallel using a plurality of electrode tabs; preparing a coverlay including a plurality of wires and through-holes; electrically connecting a protective circuit module (PCM) to the plurality of wires; mounting the coverlay on a surface of the plurality of battery cells such that at least one of the electrode tabs passes through the through-holes in the coverlay; bending the electrode tabs such that the electrode tabs contact a plurality of battery connecting pads at ends of the plurality of wires; and welding the electrode tabs to the respective battery connecting pads.

The electrode tabs may include solder receiving holes, wherein each of the battery connecting pads includes a solder layer, and wherein, during welding of the electrode tabs to the battery connecting pads, solder of the solder layer is melted such that the solder flows into the solder receiving holes.

Welding of the electrode tabs to the battery connecting pads may include sequentially welding from a negative electrode terminal to a positive electrode terminal of the battery pack including the plurality of battery cells connected in series to each other.

Sequentially welding from the negative electrode terminal to the positive electrode terminal of the battery pack may include welding the electrode tab connected to a negative electrode terminal of a first battery cell to a corresponding battery connecting pad, sequentially welding the electrode tabs connected to negative electrode terminals of a second battery cell and battery cells following the second battery cell to corresponding battery connecting pads, and welding the electrode tab connected to a positive electrode terminal of a final battery cell to a corresponding battery connecting pad.

DETAILED DESCRIPTION

Korean Patent Application No. 10-2009-0126671, filed on Dec. 18, 2009, in the Korean Intellectual Property Office, and entitled: “Battery Pack and Method for Fabricating the Same,” is incorporated by reference herein in its entirety.

In the drawing figures, the dimensions of layers and regions may be exaggerated for clarity of illustration. It will also be understood that when a layer or element is referred to as being “on” another element, it can be directly on the other element, or intervening elements may also be present. In addition, it will also be understood that when an element is referred to as being “between” two elements, it can be the only element between the two elements, or one or more intervening elements may also be present. Like reference numerals refer to like elements throughout.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings.FIG. 1illustrates a perspective view of a battery pack according to an embodiment.FIG. 2illustrates a cross-sectional view of a battery cell of the battery pack illustrated inFIG. 1.FIG. 3illustrates a perspective view of battery cells and electrode tabs of the battery pack illustrated inFIG. 1.FIGS. 4A-4CandFIGS. 5A-5Cillustrate various types of electrode tabs according to an embodiment.FIG. 6illustrates a perspective view of a coverlay and a protective circuit module (PCM) of the battery pack illustrated inFIG. 1.FIG. 7Aillustrates a cross-sectional view taken along the line A-N ofFIG. 6.FIG. 7Billustrates an enlarged view of a region “B” illustrated inFIG. 6.

Referring toFIG. 1, the battery pack1000according to the present embodiment may include battery cells100a,100b,100c, and100d, electrode tabs200a,200b,200c,200d, and200e, a coverlay300, and a protective circuit module (PCM)400.

In an implementation, the battery pack1000may also include a dummy cell500.

In an implementation, the battery pack1000may include a plurality of battery cells100a,100b,100c, and100dconnected in series to each other. In an alternative implementation, the battery pack1000may include the plurality of battery cells100a,100b,100c, and100dconnected in parallel to each other.

In the battery pack1000, the battery cells100a,100b,100c, and100dmay be electrically connected to the PCM400using the coverlay300.

The PCM400may control charging and discharging of the battery pack1000.

Although the present embodiment discloses a structure of the battery pack1000in which four battery cells100a,100b,100c, and100dare connected in series to each other, the embodiments are not limited thereto. In other words, for brevity of explanation, the battery pack1000having four battery cells denoted by reference numerals100a,100b,100c, and100dconnected in series to each other is illustrated, but the embodiments may also be applied to a battery pack having two or more battery cells connected in series or in parallel to each other.

As described above, the battery pack1000illustrated inFIG. 1may include four battery cells100a,100b,100c, and100dconnected in series to each other. Although six battery cells connected in parallel to each other are illustrated inFIG. 1, four battery cells100a,100b,100c, and100dand two dummy cells500are actually included in the battery pack1000.

In the structure illustrated inFIG. 1, the four battery cells100a,100b,100c, and100dand two dummy cells500are arranged in two rows. The four battery cells100a,100b,100c, and100dmay be connected in series to each other using the electrode tabs200a,200b,200c,200d, and200e.

In the battery pack1000according to the present embodiment, an arrangement of the battery cells100a,100b,100c, and100dand the two dummy cells500, as illustrated inFIG. 1, may be used in an electronic device, e.g., a notebook computer. Thus, the arrangement may vary according to a capacity and a size of the battery pack1000desired. Accordingly, it is noted that aspects of the embodiments are not limited to the battery pack1000having four battery cells100a,100b,100c, and100dand two dummy cells500, as illustrated inFIG. 1.

Referring toFIG. 2, the battery pack1000according to an embodiment may include four battery cells100a,100b,100c, and100d. The battery cells100a,100b,100c, and100dmay all have the same configuration; and the following description will be made with regard to the battery cell100aby way of example. The battery cell100amay include an electrode assembly110, a can120, a cap assembly130, and a label140.

The electrode assembly110may include a first electrode plate111, a second electrode plate112, and a separator113interposed between the first electrode plate111and the second electrode plate112. The first electrode plate111, the second electrode plate112, and the separator113may be wound.

In addition, the electrode assembly110may include a first electrode lead114electrically connected to the first electrode plate111and a second electrode lead115electrically connected to the second electrode plate112. The first electrode lead114may be electrically connected to the cap assembly130and the second electrode lead115may be electrically connected to the can120.

The first electrode plate111may be a positive plate and the second electrode plate112may be a negative plate, or vice versa. In the present embodiment, for convenience of explanation, it is assumed that the first electrode plate111is a positive plate and the second electrode plate112is a negative plate. Therefore, the cap assembly130electrically connected to the first electrode plate111may become a positive electrode terminal152and the can120, specifically a bottom surface122of the can120, may become a negative electrode terminal154.

The electrode assembly110may be accommodated in the can120.

The can120may be formed of a substantially cylindrical case having a top end opened and made of a metallic material. The can120may have a cylindrical surface121having a predetermined diameter and a bottom surface122to give a space for accommodating the electrode assembly110.

The accommodation space of the can120may include a lower insulating plate123and an upper insulating plate124as well as the electrode assembly110. The lower insulating plate123and the upper insulating plate124may be provided at lower and upper portions of the electrode assembly110, respectively, to prevent the first electrode plate111and the second electrode plate112of the electrode assembly110from contacting the can120when the electrode assembly110is accommodated in the can120, thereby preventing an electrical short.

The cap assembly130may seal an opening of the can120.

The cap assembly130may include a safety vent131configured to invert when an internal pressure of the battery cell100aincreases above a predetermined level. The cap assembly130may also include a current breaker132above the safety vent131and electrically and mechanically connected thereto to be disconnected when the safety vent131is inverted. The cap assembly130may also include a positive temperature coefficient (PTC) element133above the current breaker132and electrically and mechanically connected thereto to then abruptly increase resistance when an internal temperature of the battery cell100aincreases above a predetermined level. The cap assembly130may also include a cap-up134above the PTC element133and electrically and mechanically connected thereto. The cap assembly130may also include a gasket135insulating the safety vent131, the current breaker132, the PTC element133, and the cap-up134from the can120while surrounding side perimeters of the safety vent131, the current breaker132, the PTC element133, and the cap-up134.

The label140may cover at least the cylindrical surface121of the can120to protect the cylindrical surface121of the battery cell110.

The cap assembly130, specifically the cap-up134, may serve as the positive electrode terminal152and the bottom surface122of the can120may serve as the negative electrode terminal154, to then protrude outside.

The label140may be made of, e.g., a thermally shrinkable film.

Referring toFIG. 3, the battery pack1000may include a plurality of battery cells100a,100b,100c, and100dconnected in series to each other. In consideration of a capacity and a size of the battery pack1000, the battery cells100a,100b,100c, and100dmay be arranged in two or more rows. In an implementation, the battery cells100a,100b,100c, and100dmay be connected in series to each other by electrode tabs200a,200b,200c,200d, and200e. For convenience of explanation, in designating each of the respective battery cells100a,100b,100c, and100dof the battery pack1000, a battery cell denoted by reference numeral100ais referred to as a first battery cell, a battery cell denoted by reference numeral100bis referred to as a second battery cell, a battery cell denoted by reference numeral100cis referred to as a third battery cell, and a battery cell denoted by reference numeral100dis referred to as a fourth battery cell, respectively. In addition, in designating each of the respective electrode tabs200a,200b,200c,200d, and200e, an electrode tab denoted by reference numeral200ais referred to as a first electrode tab, an electrode tab denoted by reference numeral200bis referred to as a second electrode tab, an electrode tab denoted by reference numeral200cis referred to as a third electrode tab, an electrode tab denoted by reference numeral200dis referred to as a fourth electrode tab, and an electrode tab denoted by reference numeral200eis referred to as a fifth electrode tab, respectively.

In the battery pack1000, the battery cells100a,100b,100c, and100dmay be arranged such that a positive electrode terminal152aof the first battery cell100ais in contact with a negative electrode terminal154bof the second battery cell100b, a positive electrode terminal152bof the second battery cell100bis in contact with a negative electrode terminal154cof the third battery cell100c, and a positive electrode terminal152cof the third battery cell100cis in contact with a negative electrode terminal154dof the fourth battery cell100d.

Among the electrode tabs200a,200b,200c,200d, and200e, the first electrode tab200amay be connected to a negative electrode terminal154aof the first battery cell100a. The second electrode tab200bmay be simultaneously connected to the positive electrode terminal152aof the first battery cell100aand the negative electrode terminal154bof the second battery cell100b. The third electrode tab200cmay be simultaneously connected to the positive electrode terminal152bof the second battery cell100band the negative electrode terminal154cof the third battery cell100c. The fourth electrode tab200dmay be simultaneously connected to the positive electrode terminal152bof the second battery cell100band the negative electrode terminal154dof the fourth battery cell100d. The fifth electrode tab200emay be connected to the positive electrode terminal of the fourth battery cell100d.

Accordingly, among the electrode tabs200a,200b,200c,200d, and200e, the first electrode tab200amay become a negative electrode of the battery pack1000and the fifth electrode tab200emay become a positive electrode of the battery pack1000, which will now be described with reference toFIGS. 4A through 4C.

The electrode tabs200a,200b,200c,200d, and200emay be provided in the battery pack in, e.g., three types.

In detail, as illustrated inFIG. 4A, a first-type electrode tab, e.g., the first electrode tab200aor the fifth electrode tab200e, may contact only a single electrode terminal, either the positive electrode terminal152dor the negative electrode terminal154a. As illustrated inFIG. 4B, a second-type electrode tab, e.g., the second electrode tab200bor the third electrode tab200c, may simultaneously contact a positive electrode terminal and a negative electrode terminal. As illustrated inFIG. 4C, a third-type electrode tab, e.g., the fourth electrode tab200d, may simultaneously contact a positive electrode terminal and a negative electrode terminal, wherein the respective electrode terminals correspond to battery cells arranged in different rows, i.e., the third battery cell100cand the fourth battery cell100d.

The first-type electrode tab, e.g., the first electrode tab200aand the fifth electrode tab200e, will now be described with reference toFIG. 4A. Each of the first electrode tab200aand the fifth electrode tab200emay include a contact portion210a,210e, a pad contact portion220a,220e, a bent portion230a,230e, and a solder receiving hole240a,240e.

The battery contact portion210aof the first electrode tab200amay contact the negative electrode terminal154aof the first battery cell100aand the battery contact portion210eof the fifth electrode tab200emay contact the positive electrode terminal152dof the fourth battery cell100d. Contact may be established by welding, e.g., resistance welding.

Since the battery contact portion210aof the first electrode tab200aand the battery contact portion210eof the fifth electrode tab200emay contact only the negative electrode terminal154aof the first battery cell100aand the positive electrode terminal152dof the fourth battery cell100d, respectively, portions of the battery contact portion210a,210emay correspond to the negative electrode terminal154aand the positive electrode terminal152d. In the present embodiment, circular electrode tabs are illustrated, but aspects of the embodiments are not limited thereto.

The pad contact portion220a,220emay be brought into contact with, e.g., welded to, respective battery connecting pads311aand311eof the coverlay300, which will be described below.

The pad contact portion220a,220emay include the solder receiving hole240a,240eat a predetermined area.

The bent portion230a,230emay be provided at a given position between the battery contact portion210a,210eand the pad contact portion220a,220e.

The bent portion230a,230emay be an area at which each of the first electrode tab200aand the second electrode tab200eis bent in an inverted L-shape. The bent portion230a,230e, as illustrated inFIG. 4A, may be provided at an area where a width of the battery contact portion210a,210eis different from a width of the pad contact portion220a,220e. In other words, when the width of the battery contact portion210a,210eis different from the width of the pad contact portion220a,220e, the bent portion230a,230emay be bent by applying a force to the pad contact portion220a,220ein a state in which the battery contact portion210a,210eis engaged with the corresponding battery cell by welding. Thus, each of the first electrode tab200aand the second electrode tab200emay be bent in the inverted L-shape, as illustrated inFIG. 1.

The second-type electrode tab, e.g., the second electrode tab200bor the third electrode tab200c, will now be described with reference toFIG. 4B. Each of the second electrode tab200band the third electrode tab200cmay include a contact portion210b,210c, a pad contact portion220b,220c, a bent portion230b,230c, and a solder receiving hole240b,240c.

The battery contact portion210bof the second electrode tab200bmay contact the positive electrode terminal152aof the first battery cell100aand the negative electrode terminal154bof the second battery cell100b. The battery contact portion210cof the third electrode tab200cmay contact the positive electrode terminal152bof the second battery cell100band the negative electrode terminal154cof the third battery cell100c. Contact may be established by welding, e.g., resistance welding.

The battery contact portion210bof the second electrode tab200band the battery contact portion210cof the third electrode tab200cmay be in contact with two opposite electrode terminals facing each other. Consequently, the battery contact portion210bof the second electrode tab200band the battery contact portion210cof the third electrode tab200cmay include first battery contact plates212band212c, second battery contact plates214band214c, and connecting plates216band216cconnecting the first battery contact plates212band212cand the second battery contact plates214band214c, respectively.

The first battery contact plates212band212cmay be parallel with each other; and the second battery contact plates214band214cmay be parallel with each other. The connecting plate216b,216cmay connect the first battery contact plate212b,212cand the second battery contact plate214b,214cto each other and may support the same.

The pad contact portion220b,220cmay extend from one of the battery contact portion210bor the battery contact portion210c. Specifically, the pad contact portion220b,220cmay extend from one of the first battery contact plates212band212cor one of the second battery contact plates214band214c.

The pad contact portion220b,220cmay be brought into contact with, e.g., welded to, respective battery connecting pads311band311cof the coverlay300, which will be described below.

The pad contact portion220b,220cmay include the solder receiving hole240b,240cat a predetermined area. The bent portion230b,230cmay be provided at a given position between the battery contact portion210b,210cand the pad contact portion220b,220c.

The bent portion230b,230cmay be an area at which each of the second electrode tab200band the third electrode tab200cis bent in an inverted L-shape. The bent portion230b,230c, as illustrated inFIG. 4B, may be provided at an area where a width of the battery contact portion210b,210cis different from a width of the pad contact portion220b,220c. In other words, when the width of the battery contact portion210b,210cis different from the width of the pad contact portion220b,220c, the bent portion230b,230cmay be bent by applying a force to the pad contact portion220b,220cin a state in which the battery contact portion210b,210cis engaged with the corresponding battery cell by welding. Thus, each of the second electrode tab200band the third electrode tab200cmay be bent in an inverted L-shape, as illustrated inFIG. 1.

The third-type electrode tab, e.g., the fourth electrode tab200d, will now be described with reference toFIG. 4C. The fourth electrode tab200dmay include a battery contact portion210d, a pad contact portion220d, a bent portion230d, and a solder receiving hole240d.

The battery contact portion210dof the fourth electrode tab200dmay simultaneously contact the positive electrode terminal152cof the third battery cell100cand the negative electrode terminal154dof the fourth battery cell100d. Contact may be established by welding, e.g., resistance welding.

Since the battery contact portion210dof the fourth electrode tab200dmay be in contact with two electrode terminals parallel to each other, it may have a different width from the battery contact portion210a,210eof the first and fifth electrode tab200a,200eillustrated inFIG. 4A. In other words, the illustrated fourth electrode tab200dmay be an unfolded version of the second or third electrode tab200b,200cin which a first battery contact plate212b,212c, a connecting plate216b,216c, and a second battery contact plate214b,214c, are not bent in the battery contact portion210b,210c.

The pad contact portion220dmay extend from the battery contact portion210d.

The pad contact portion220dmay be brought into contact with, e.g., welded to, a battery connecting pad311dof the coverlay300, which will be described below.

The pad contact portion220dmay include the solder receiving hole240dat a predetermined area.

The bent portion230dmay be provided at a given position between the battery contact portion210dand the pad contact portion220d.

The bent portion230dmay include an area at which the fourth electrode tab200dis bent in an inverted L-shape. The bent portion230d, as illustrated inFIG. 4C, may be provided at an area where a width of the battery contact portion210dis different from a width of the pad contact portion220d. In other words, when the width of the battery contact portion210dis different from the width of the pad contact portion220d, the bent portion230dmay be bent by applying a force to the pad contact portion220din a state in which the battery contact portion210dis engaged with the corresponding battery cell by welding. Thus, the fourth electrode tab200dmay be bent in the inverted L-shape, as illustrated inFIG. 1.

Referring toFIGS. 5A through 5C, the bent portions230a,230b,230c,230d, and230eof the electrode tabs200a,200b,200c,200d, and200eillustrated inFIGS. 4A through 4Cmay be formed by making widths of the battery contact portions210a,210b,210c,210d, and210edifferent from widths of the pad contact portions220a,220b,220c,220d, and220e. However, the bent portions230a,230b,230c,230d, and230emay take on various forms, as illustrated inFIGS. 5A through 5C. WhileFIGS. 5A through 5Cillustrate a first-type electrode tab, e.g., the first electrode tab200aand the fifth electrode tab200e, as illustrated inFIG. 4A, by way of example, the embodiments may also be applied to a second-type electrode tab and a third-type electrode tab, e.g., the second electrode tab200bor the third electrode tab200c, and the fourth electrode tab200d, as illustrated inFIGS. 4B and 4C, respectively.

The bent portions230aand230emay be formed by forming notches250,260, and270between each of the battery contact portions210aand210eand each of the pad contact portions220aand220e.

In other words, as illustrated inFIGS. 5A and 5B, the electrode tabs200aand200emay respectively have a first notch250or a second notch260on opposite sides thereof. The first notch250may have a triangular shape and the second notch260may have a semicircular shape, so as to have a reduced width thereat compared to other areas. In an alternative implementation, as illustrated inFIG. 5C, the electrode tab200a,200emay have a third notch270formed on opposite surfaces thereof, to make thicknesses of bent portion230aand230ethinner than other portions of the electrode tab.

Since the notches250,260, and270may be formed on the electrode tabs200and,200e, the bent portion230a,230emay be relatively easily bent compared to other areas when a force is applied to the pad contact portion220a,220eof the electrode tab200a,200e. In other words, bending may occur around the bent portion230a,230e, thereby allowing the electrode tabs200aand200eto be easily bent in the inverted L-shape.

Referring toFIGS. 6,7A and7B, the coverlay300may be a flexible printed circuit board (FPCB). The coverlay300may include a plurality of wires310a,310b,310c,310d, and310e, an insulating layer320that insulates the wires310a,310b,310c,310d, and310efrom one another, and an adhesive layer330for adhering the coverlay300to, e.g., the battery cells100.

The wires310a,310b,310c,310d, and310emay be provided such that positive and negative electrode terminals of each of the battery cells100a,100b,100c, and100dmay all be connected to the PCM400to allow each of the battery cells100a,100b,100c, and100dto be controlled by the PCM400. Therefore, the number of the wires310a,310b,310c,310d, and310emay be one greater than the total number of active battery cells100a,100b,100c, and100d.

The wires310a,310b,310c,310d, and310emay respectively include battery connecting pads311a,311b,311c,311d, and311eat one end thereof and module connecting pads312a,312b,312c,312d, and312eat another end thereof, as representatively illustrated inFIG. 7A.FIG. 7Aillustrates a cross-sectional view of the wire310b, taken along the line A-A′ ofFIG. 6. Each of the battery connecting pads311a,311b,311c,311d, and311eand each of the module connecting pads312a,312b,312c,312d, and312emay be exposed by openings326in the insulating layer320, respectively.

Each of the battery connecting pads311a,311b,311c,311d, and311emay be formed by providing a solder layer340on each of the wires310a,310b,310c,310d, and310e, respectively.

The insulating layer320may insulate not only the wires310a,310b,310c,310d, and310efrom one another, but also the wires310a,310b,310c,310d, and310efrom the outside.

The coverlay300may include at least one through-hole350passing through the insulating layer320.

The at least one through-hole350may correspond to at least one of the electrode tabs200a,200b,200c,200d, and200eand at least one of the battery connecting pads311a,311b,311c,311d, and311e, such that at least one of the electrode tabs200a,200b,200c,200d, and200emay pass therethrough to easily come into contact with at least one of the battery connecting pads311a,311b,311c,311d, and311e. For example, as illustrated inFIG. 7B, the through-hole350may be formed at a position corresponding to the electrode tab200b, while being positioned close to the battery connecting pad311b.

The at least one of the electrode tabs200a,200b,200c,200d, and200emay pass through the at least one through-hole350to then be bent, thereby preventing undesirable movement of the coverlay300. In other words, the at least one of the electrode tabs200a,200b,200c,200d, and200e, having passed through the at least one through-hole350, may fix the coverlay300, thereby allowing the battery connecting pads311a,311b,311c,311d, and311eon the coverlay300to be connected to the electrode tabs200a,200b,200c,200d, and200eat correct positions. In addition, the fixing of the coverlay300using the at least one through-hole350may prevent the electrode tabs200a,200b,200c,200d, and200efrom moving relative to the battery connecting pads311a,311b,311c,311d, and311ewhen connecting, e.g., welding, the electrode tabs200a,200b,200c,200d, and200eto the battery connecting pads311a,311b,311c,311d, and311e, respectively.

The adhesive layer330may allow the coverlay300to be adhered to a surface of each of the battery cells100a,100b,100c, and100d.

The adhesive layer330may be formed by, e.g., coating an adhesive agent on a surface of the coverlay300or attaching a double-sided tape on the surface of the coverlay300.

The coverlay300may be connected to the PCM400.

The PCM400may perform control operations of the battery pack1000according to an embodiment.

The PCM400may include a substrate410, contact pads420on the substrate410and connected to the wires310a,310b,310c,310d, and310e, control devices430on the substrate410and including, e.g., IC elements or the like, and an external connecting member440at one side of the substrate410and connecting the battery pack1000to an external device.

The PCM400may be connected to the respective battery cells100a,100b,100c,100d,100ethrough the wires310a,310b,310c,310d, and310e. Thus, the PCM400may perform charging or discharging operations on the battery cells100a,100b,100c,100d,100e.

FIGS. 8 through 12Billustrate stages in a method for manufacturing a battery pack according to an embodiment.FIG. 11illustrates an enlarged view of a region “C” ofFIG. 10.FIG. 12Aillustrates a cross-sectional view taken along the line D-D′ ofFIG. 11.FIG. 12Billustrates a cross-sectional view taken along the line E-E′ ofFIG. 11.

Referring toFIGS. 8 through 12B, a plurality of battery cells100a,100b,100c, and100dconnected in series or in parallel to each other using a plurality of electrode tabs200a,200b,200c,200d, and200emay be prepared. In the illustrated embodiment, four battery cells100a,100b,100c, and100dand two dummy cells500are arranged in two rows. The battery pack manufacturing method according to the present embodiment will be described with regard to a battery pack having the four battery cells100a,100b,100c, and100dconnected in series to each other, but the embodiments are not limited thereto.

Next, the coverlay300and the PCM400coupled thereto may be prepared. The coverlay300may include a plurality of wires310a,310b,310c,310d, and310e.

Next, the coverlay300may be seated on a surface of the battery cells100a,100b,100c, and100dand the dummy cells500. At least one of the electrode tabs200a,200b,200c,200d, and200emay pass through through-holes350in the coverlay300.

The coverlay300, as illustrated inFIG. 8, may include three through-holes350to allow three electrode tabs200b,200c, and200damong the electrode tabs200a,200b,200c,200d, and200eto pass therethrough. Accordingly, the three electrode tabs200b,200c, and200dmay pass through the three through-holes350to then be bent, thereby allowing the three electrode tabs200b,200c, and200dto fix the coverlay300.

Since the coverlay300may include the adhesive layer330, the coverlay300may be adhered to the surface of the battery cells100a,100b,100c, and100dand the dummy cells500.

Then, the electrode tabs200a,200b,200c,200d, and200emay be bent to bring the electrode tabs200a,200b,200c,200d, and200einto contact with the respective battery connecting pads311a,311b,311c,311d, and311eof the coverlay300. The electrode tabs200a,200b,200c,200d, and200emay be bent at the bent portions230a,230b,230c,230d, and230e, respectively, as described above with reference toFIGS. 4A through 5B.

Next, the electrode tabs200a,200b,200c,200d, and200emay be attached to the battery connecting pads311a,311b,311c,311d, and311e, respectively, by, e.g., welding. In an implementation, the welding may include, e.g., soldering or resistance welding.

The welding of the electrode tabs200a,200b,200c,200d, and200eto the battery connecting pads311a,311b,311c,311d, and311emay be sequentially performed from a negative electrode terminal to a positive electrode terminal of the battery pack1000.

The battery pack1000may have the plurality of battery cells100a,100b,100c, and100dconnected in series to each other. A negative electrode terminal154aof a firstly connected one, i.e., the first battery cell100a, among the plurality of battery cells100a,100b,100c, and100dmay become a negative electrode terminal of the battery pack1000. A positive electrode terminal152dof a finally connected one, i.e., the fourth battery cell100d, among the plurality of battery cells100a,100b,100c, and100dmay become a positive electrode terminal of the battery pack1000.

The previous reference to sequentially welding from a negative electrode terminal to a positive electrode terminal of the battery pack1000means that the first electrode tab200aconnected to the negative electrode terminal154aof the first battery cell100amay be welded to the battery connecting pad311a. Then, a second electrode tab200b, a third electrode tab200c, and a fourth electrode tab200dconnected to negative electrode terminals154b,154c, and154dof a second battery cell and battery cells following the second battery cell, i.e., the second battery cell100b, the third battery cell100c, and the fourth battery cell100d, may be sequentially welded to the battery connecting pads311b,311c, and311d. Next, a fifth electrode tab200econnected to the positive electrode terminal152dof the final battery cell, i.e., the fourth battery cell100d, may be welded to the battery connecting pad311e.

When the electrode tabs200a,200b,200c,200d, and200eare welded to the battery connecting pads311a,311b,311c,311d, and311e, respectively, solder may be melted from the solder layer340of the battery connecting pads311a,311b,311c,311d, and311e, such that the molten solder flows into the solder receiving holes240a,240b,240c,240d, and240eof the electrode tabs200a,200b,200c,200d, and200e. When the welding is completed, followed by cooling, the molten solder may be solidified to then cover internal spaces and entrances of the solder receiving holes240a,240b,240c,240d, and240e.

In other words, as illustrated inFIGS. 11 through 12B, when the second electrode tab200bis welded to the battery connecting pad311b, the solder layer340may be melted as the result of the welding. The molten solder from the solder layer340may cover the internal space and entrance of the solder receiving hole240b. Thereafter, after the welding is completed and cooling is performed, the solidifying of the solder covering the internal space and entrance of, i.e., may fill, the solder receiving hole240bmay make the solder receiving hole240bconvexly protrude while covering the internal space and entrance thereof.

It will be seen that embodiments have been described in which a battery pack has a compact size with a plurality of battery cells stably mounted therein.