Rechargeable battery

A rechargeable battery, and more particularly, a rechargeable battery having a function of detecting water contact. The area for detecting water contact is formed on the rechargeable battery or its component parts by applying water-soluble ink on a surface thereof. It is straightforward to form such a rechargeable battery and to easily determine whether the rechargeable battery or its component parts have been in contact with water.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Korean Patent Application No. 2007-115310, filed Nov. 13, 2007 in the Korean Intellectual Property Office, the entire disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Aspects of the present invention relate to a rechargeable battery, and more particularly, to a rechargeable battery having the function of detecting water contact.

2. Description of the Related Art

Portable electrical/electronic devices that are compact and light, such as cellular phones, notebook computers, camcorders and the like, have been developed and are currently produced. Battery packs are embedded in such portable electrical/electronic devices, so that the portable electrical/electronic devices can operate in places where a separate power source is not provided. For economy, battery packs generally use rechargeable batteries. Representative examples of rechargeable batteries are nickel-cadmium (Ni—Cd) batteries, nickel-metal hydride (Ni-MH) batteries, lithium (Li) batteries, lithium-ion (Li-ion) rechargeable batteries and the like. In particular, lithium-ion (Li-ion) rechargeable batteries have an operating voltage three times higher than nickel-cadmium (Ni—Cd) batteries or nickel-metal hydride (Ni-MH) batteries, which are widely used as a power source of portable electronic devices. Lithium-ion (Li-ion) rechargeable batteries are also widely used since their energy density per unit weight is higher than those for the other batteries.

Lithium-ion (Li-ion) rechargeable batteries generally use lithium-based oxides as positive electrode active materials and carbon materials as negative electrode active materials. Batteries are generally classified into liquid electrolyte batteries and polymer electrolyte batteries according to the type of electrolyte. Lithium-ion (Li-ion) rechargeable batteries use a liquid electrolyte, and lithium polymer batteries use a polymer electrolyte. Lithium-ion (Li-ion) rechargeable batteries are manufactured into various types of shapes. Representative examples thereof are cylinder type lithium-ion (Li-ion) rechargeable batteries, prismatic type lithium-ion (Li-ion) rechargeable batteries, and pouch type lithium-ion (Li-ion) rechargeable batteries.

Rechargeable batteries having the above shapes in a bare cell state are incorporated into a battery pack that also includes protective circuit modules, exterior finishing materials and the like. Protective circuit modules control charging/discharging when rechargeable batteries are charged/discharged, and block current flow from charging/discharging when the rechargeable batteries are over-heated or over-charged.

Devices such as labels for detecting water contact are separately attached to battery packs and detect whether the battery packs contact water. However, labels for detecting water contact need to be separately, often manually attached to the battery packs, which reduces the efficiency of producing finished battery packs.

SUMMARY OF THE INVENTION

An aspect of the present invention improves the production efficiency for rechargeable batteries by applying water-soluble ink directly to the surface of the circuit board during the manufacturing process. Another aspect of the present invention provides a method of efficiently improving detection of water contact in a rechargeable battery.

Another aspect of the present invention provides a rechargeable battery including a circuit board; a battery electrically coupled with the circuit board; and, a cover case coupled to at least one of the circuit board and the battery, wherein an area for detecting water contact is formed on at least one of the circuit board, the battery and the cover case. The area for detecting water contact may be formed by applying a water-soluble ink on at least one of the circuit board, the battery and, the cover case. Also, areas for detecting water contact may be formed on the circuit board by applying a water-soluble ink at a plurality of sites.

The circuit board includes an insulating substrate, at least one printed circuit pattern formed on the insulating substrate, and protective circuit parts electrically connected to the printed circuit pattern, wherein the area for detecting water contact may be formed on at least one of the insulating substrate, the printed circuit pattern, and the protective circuit parts. Paint may be applied on a top surface of at least one of the insulating substrate, the printed circuit pattern, and the protective circuit parts, and the area for detecting water contact having a different color from that of the paint is formed on a top surface of the paint.

The circuit board also includes an insulating substrate, at least one printed circuit pattern formed on the insulating substrate, and protective circuit parts electrically connected to the printed circuit pattern, wherein at least one hole may be formed in the insulating substrate, and the area for detecting water contact is formed by applying water-soluble ink in the hole. Also, the circuit board includes an insulating substrate, at least one printed circuit pattern formed on the insulating substrate, and protective circuit parts electrically connected to the printed circuit pattern, wherein at least one groove may be formed in the insulating substrate, and the area for detecting water contact is formed by applying water-soluble ink in the groove.

A hole may also be formed in the cover case and the area for detecting water contact is externally exposed via the hole. Also, the circuit board may include an examination terminal, in which case a hole for exposing the examination terminal may be formed in the cover case, and the area for detecting water contact is exposed via the hole. Also, the area for detecting water contact may be formed on at least one of an inner surface and an outer surface of the cover case by applying a water-soluble ink. Also, at least one hole may be formed in the cover case and the area for detecting water contact formed by applying a water-soluble ink in the hole.

At least one groove may also be formed in the cover case and the area for detecting water contact is formed in the groove by applying a water-soluble ink in the groove. In this case, the groove may be formed in a linear shape and the area for detecting water contact is formed in the groove by applying a water-soluble ink in the groove. The groove may also be formed in a plurality of grooves, at least one groove having a different depth, and the areas for detecting water contact are formed in the grooves by applying a water-soluble ink in the groove.

The rechargeable battery may further include a combination auxiliary where the combination auxiliary is formed between the battery and the cover case, and the area for detecting water contact may then be formed in a groove in the combination auxiliary by applying water-soluble ink in the combination auxiliary groove. In this case, the combination auxiliary is one of a lead tap electrically connecting the battery and the circuit board, an insulator insulating the lead tap and the positive electrode and the negative electrode of the battery, a receiving case formed between the battery and the cover case, a label surrounding at least a part of the battery, and a reinforcing plate surrounding at least a part of the battery.

The battery also includes an electrode assembly having a positive electrode and a negative electrode, a can containing the electrode assembly, and a material for closing the electrical connection connected to the positive electrode and the negative electrode of the electrode assembly, wherein the area for detecting water contact may be formed on at least one of the can and the material for completing the electrical connection by applying a water-soluble ink to at least one of the can or the material. Also, the battery may include an electrode assembly and a pouch containing the electrode assembly, wherein the area for detecting water contact may be formed on the pouch by applying a water-soluble ink to at least one of the electrode assembly and the pouch.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIG. 1Ais a perspective view illustrating a circuit board100having the function of detecting water contact according to an embodiment of the present invention. An area for detecting water contact using water-soluble ink120is formed on an insulating substrate110.

The circuit board100includes a printed circuit pattern (not shown) formed on an insulating substrate (110) and may include an electric element (not shown) that is solder-coupled with the printed circuit pattern (not shown). However, the present invention is not limited to the constituents of the circuit board100or the connections therebetween. Therefore, the circuit board100may be any circuit board used in an electronic product.

The water-soluble ink120may be formed by using printing ink that spreads when the ink contacts water or a material equivalent to such ink, or using an equivalent method, but the present invention is not limited thereto. The water-soluble ink120that is used to form an area for detecting water contact remains in a specific shape and pattern when not contacting water, and is diluted by water and changes its shape and pattern, i.e., spreads into the water. In other words, the circuit board100having the function of detecting water contact can detect whether it contacts water because of the water-soluble ink120applied on the surface of the circuit board100. Therefore, when a portable electronic product, a battery, or the like using the circuit board100having the function of detecting water contact contacts water, it is possible to detect whether there has been water contact by visually checking the water-soluble ink120.

FIG. 1Bis a perspective view illustrating a circuit board200having the function of detecting water contact according to another embodiment of the present invention. Water-soluble ink120may be applied on an insulating substrate110in a plurality of marks to form an area210for detecting water contact. The area210for detecting water contact may be formed in a plurality of ‘x’-shaped identification marks, as shown inFIG. 1B, to visibly show well whether there has been water contact. The area210for detecting water contact may instead be formed in ‘+’-shaped identification marks or in a plurality of dotted-type identification marks and the like, which are different from the marks ofFIG. 1B. However, the present invention is not limited to the shape of the area210for detecting water contact.

FIG. 1Cis a perspective view illustrating a circuit board300having the function of detecting water contact according to still another embodiment of the present invention. The circuit board300may include an insulating substrate310, a printed circuit pattern320formed on the insulating substrate310, and an electric element330coupled with the printed circuit pattern320. An area210for detecting water contact may be applied on at least one portion of the surface of the printed circuit pattern320or the electric element330.

The insulating substrate310may be formed of phenol-formaldehyde-based resin or epoxy-based resin. However, the present invention is not limited thereto. Although not shown inFIG. 1C, the area210for detecting water contact may be applied even on the insulating substrate310.

The printed circuit pattern320may be formed in a conductive thin film, such as a copper foil and the like, and then integrally formed with the insulating substrate310. Although not shown inFIG. 1C, the area210for detecting water contact may be applied even on the printed circuit pattern320.

The electric element330may be solder coupled with the printed circuit pattern320. The electric element330may include a passive element331, an active element332, or an integrated circuit333. The passive element331may be an element such as a condenser, a resistance or coil, and the like. The active element332may be an element such as a diode and a transistor. The integrated circuit333may be a semiconductor package in which a semiconductor chip embedded with an integrated circuit is packaged. It is possible to detect whether each portion of the insulating substrate310contacts water by selectively forming the area210for detecting water contact on the specific surface of the electric elements330. As an example of the area210for detecting water contact formed on the electric element330, the area210for detecting water contact is formed on one surface of the semiconductor chip333as shown inFIG. 1C.

FIG. 1Dis a perspective view illustrating a circuit board400having the function of detecting water contact according to still another embodiment of the present invention. Paint410is applied on a top surface of an insulating substrate310formed on the circuit board400, and water-soluble ink120having a different color from that of the paint410is applied on the top surface of the paint410, thereby forming an area210for detecting water contact. The paint410may be applied on the top surface of a printed circuit pattern (not shown). The paint410may represent a produced date, a serial number, and the like, applied on one surface of the insulating substrate310using intaglio printing or embossing, and may for example be in white. It is possible to apply the area210for detecting water contact, which for example may be purple, red, or the like, on the white paint420. Therefore, it is possible to make it visually clear whether the area210for detecting water contact has changed by using the difference in color between the paint410and the area210for detecting water contact. However, the present invention is not limited to the colors of the paint410and the area210for detecting water contact. Although not shown inFIG. 1D, the paint410may also be applied on a top surface of an electric element, and the area210for detecting water contact may be formed on the paint410.

FIG. 1Eis a perspective view illustrating a circuit board500having the function of detecting water contact according to still another embodiment of the present invention. One or more holes510may be formed in an insulating substrate310of the circuit board500, and water-soluble ink120may be applied in the hole510.

If the circuit board500contacts water, the water-soluble ink120applied in the hole510is diluted in the water and then sinks through the holes510. Therefore, if the water-soluble ink120applied in the hole510of the circuit board500is examined, it is possible to detect whether there has been water contact based on whether the water-soluble ink120has spread through hole510or changed its pattern. Hole510may be formed in the center of the insulating substrate310so that it is easy to detect whether there has been water contact.

FIG. 1Fis a perspective view illustrating a circuit board600having the function of detecting water contact according to still another embodiment of the present invention. One or more grooves610may be formed in an insulating substrate310of the circuit board600, and water-soluble ink120may be applied in the grooves610. The grooves610may stay in water when the circuit board600contacts water. Therefore, water-soluble ink120is changed into a liquid state (dissolved or suspended) and drains out of the grooves610when the insulating substrate310moves, thereby showing whether there has been water contact.

FIG. 2Ais an exploded perspective view illustrating a rechargeable battery700having the function of detecting water contact according to still another embodiment of the present invention.FIG. 2Bis a perspective view illustrating the assembled rechargeable battery700ofFIG. 2A. The rechargeable battery700may include a battery710, a circuit board720, and a cover case730. Circuit board720includes an insulating substrate721, a printed circuit pattern (not shown), and protective circuit parts722.

The battery710includes a positive electrode711and a negative electrode712. The battery710may be formed of one or more batteries. The battery710may be a can type battery containing an electrode assembly in a metal can. Alternatively, the battery710may be a pouch type battery containing the electrode assembly in a pouch. However, the present invention is not limited to the type of the battery710used in the rechargeable battery700.

The circuit board720may include protective circuit parts722that are electrically connected to the positive electrode711and the negative electrode712of the battery710and perform a protective function when the battery710is charged/discharged, the printed circuit pattern (not shown) to which the protection circuit parts722are soldered, and the insulating substrate721that receives the printed circuit pattern (not shown). The positive electrode711and the negative electrode712of the battery710may be electrically connected to the circuit board720using a wire (not shown) or a lead tap (not shown), but the present invention is not limited to the particular electrical connections of the positive electrode711and the negative electrode712of the battery710to the circuit board720. Meanwhile, the protective circuit parts722may include a passive element (not shown), an active element (not shown), and an integrated circuit (not shown). When charging/discharging terminals723are connected to a charger and start charging, or when they are connected to loads and start discharging, the protective circuit parts722may turn on or off a charging/discharging field-effect transistor (FET) (not shown) by using a control integrated circuit (IC) that is a direct circuit, and selectively charge or discharge the battery710. The charging/discharging FET may be separated into a charging FET and a discharging FET and establish separate charging and discharging paths to the battery710. The protective circuit parts722may include a safety element, such as a Positive Temperature Coefficient (PTC), a thermal breaker, and the like to detect overheating and over-charge states of the battery710that is being charged/discharged and stop the charging/discharging of battery710. The protective circuit parts722may be electrically connected to the charging/discharging paths of the battery710to detect a charging/discharging current of the battery710and detect the over-charge state. The protective circuit parts722may be soldered on the printed circuit pattern (not shown) formed on the insulating substrate721to form a structurally stabilized integral type board. The protective circuit parts722having the above-described function perform the protection function for the circuit board720.

Meanwhile, the water-soluble ink120may be applied on at least one portion of the surface of the circuit board720to form an area210for detecting water contact. As described above in the aforementioned embodiments, the area210for detecting water contact may be applied on one surface of the insulating substrate721and the printed circuit pattern (not shown). The water-soluble ink120may also be applied on a top surface of paint (not shown), which is applied on a top surface of the insulating substrate721. The protective circuit parts722may be formed by using electric elements of the aforementioned embodiments. The water-soluble ink120may be selectively applied on the protective circuit parts722. That is, when the area210for detecting water contact is applied on the surface of a control IC that is an integrated circuit, or a passive element such as a condenser, and when the circuit board720contacts water, it is possible to determine whether the protective circuit parts722contact water by observing any change in the area210for detecting water contact. The area210for detecting water contact applied on the insulating substrate721is the same as described in previous embodiments, and thus its detailed description is not repeated.

The cover case730may be combined with at least one of the printed circuit board720and the battery710to insulate the circuit board720and protect the circuit board720from an external shock. The cover case730may have charging/discharging terminal holes731that expose a terminal surface of the charging/discharging terminals723formed on the printed circuit board720. The cover case730may include a sidewall732to cover a side surface of the circuit board720. The sidewall732may contact one surface of the battery710so that an outer surface of the battery710may correspond to that of the sidewall732. The cover case730may be formed by injection-molding a thermoplastic resin material. Although not shown inFIG. 2A, the cover case730may include a frame (not shown) that surrounds the circuit board720and the battery710. However, the present invention is not limited to the material and shape of the cover case730.

When the rechargeable battery700contacts water, it is possible to determine whether the circuit board720contacts water immediately after opening the cover case730covering the circuit board720. In more detail, by observing a change in the area210for detecting water contact caused when the rechargeable battery700is contacting water due to a user's carelessness or mistake, it is possible to dry the moisture from the circuit board720, prevent a short circuit, and then inspect the circuit board720when the operating state of the circuit board720is examined.

FIG. 2Cis a partial perspective view illustrating a rechargeable battery800having the function of detecting water contact according to an embodiment of the present invention. The rechargeable battery800may further include a hole810different from charging/discharging terminal holes731in cover case730. Water-soluble ink120may be exposed through the hole810. Since the hole810is formed to face the water-soluble ink120applied on a circuit board (not shown), the hole810may be formed in any portion of the cover case730. It is possible to determine whether the rechargeable battery800contacts water by observing any change in the pattern of the water-soluble ink120of the circuit board via the hole810. Therefore, it is possible to determine whether the rechargeable battery800contacts water without disassembling the cover case730.

FIG. 2Dis a partial perspective view illustrating a rechargeable battery900having the function of detecting water contact according to still another embodiment of the present invention. The rechargeable battery900may further include an examination terminal910that is electrically connected to a printed circuit pattern (not shown) formed on a circuit board (not shown), and a hole920other than charging/discharging terminal holes731in a cover case730that exposes the examination terminal910.

The examination terminal910is also used as an electrical connection part when to determine whether a protective circuit part (not shown) formed on the circuit board operates; that is, the examination terminal910is electrically connected to the printed circuit pattern. Water-soluble ink120is applied around the examination terminal910. Accordingly, one can view the water-soluble ink120through the hole920that exposes the examination terminal910. Therefore, it is possible to determine through hole920whether there has been a change in the water-soluble ink120pattern, and then, if the circuit board has not contacted water, examine whether through the examination terminal910whether an error has occurred in the protective circuit part. When it has been determined that the water-soluble ink120pattern has changed, it is then possible to examine through the examination terminal910whether the error occurred in the protective circuit part after drying the circuit board.

FIG. 2Eis a partial perspective view illustrating a rechargeable battery1000having the function of detecting water contact according to still another embodiment of the present invention. Water-soluble ink120may be applied on an outer surface of cover case730of the rechargeable battery1000to form an area210for detecting water contact. Although not shown inFIG. 2E, the water-soluble ink120may also be applied on an inner surface of the cover case730to form the area210for detecting water contact. Accordingly, it is possible to determine immediately whether the rechargeable battery1000contacts water when the water-soluble ink120is applied on the outer surface of the cover case730. Meanwhile, it is also possible to determine whether the inner surface of the cover case730of the rechargeable battery1000contacts water when the water-soluble ink120is applied on the inner surface of the cover case730.

FIG. 2Fis a partial perspective view illustrating an assembled battery pack1100having the function of detecting water contact according to still another embodiment of the present invention. The rechargeable battery1100may further include one or more holes1110different from charging/discharging terminal holes731in the cover case730. Water-soluble ink120may be applied in the holes1110.

If the rechargeable battery1100contacts water, the water-soluble ink120applied in the holes1110is diluted in water, and then sinks through the holes1110. Therefore, if the water-soluble ink120applied in the holes1110of the rechargeable battery1100is examined, it is possible to immediately detect whether there has been water contact based on whether the water-soluble ink120has spread through holes1110or changed its pattern. Holes1110may also be formed as more than one in the cover case730so that it is easy to detect whether there has been water contact.

FIG. 2Gis a partial perspective view illustrating a rechargeable battery1200having the function of detecting water contact according to another embodiment of the present invention. One or more grooves1210may be formed in the cover case730of the rechargeable battery1200, and water-soluble ink120may be applied in the grooves1210. The grooves1210may stay in water when the rechargeable battery1200contacts water. Therefore, the water-soluble ink120applied in the grooves1210is changed into a liquid state (dissolution or suspension) when the rechargeable battery1200contacts water and then drains out of the groove1210after the rechargeable battery1200moves, thereby showing whether there has been water contact. The groove1210may be formed in more than one groove in the cover case730so that it is easy to detect whether there has been water contact.

FIG. 2His a partial perspective view illustrating a rechargeable battery1300having the function of detecting water contact according to still another embodiment of the present invention. A linear groove1310may be formed in a cover case730of the rechargeable battery1300, the linear groove1310is formed in a linear shape and the water-soluble ink120is applied in the linear groove1310, thereby detecting whether there has been water contact. The depth of the linear groove1310changes and the water-soluble ink120can be applied therein along the length and to all the depths. Therefore, the water-soluble ink120having the different depths can show how much the rechargeable battery1300contacts water by observing the change in the water-soluble ink120at the various depths when the rechargeable battery1300contacts water.

FIG. 2Iis a partial perspective view illustrating a rechargeable battery1400having the function of detecting water contact according to still another embodiment of the present invention. A plurality of grooves1410may be formed in the cover case730of the rechargeable battery1400, and at least one of the grooves1410is formed at a different depth. The water-soluble ink120may be applied in the plurality of grooves1410, thereby showing whether and how much the rechargeable battery1400contacts water.

FIG. 2Jis an exploded perspective view illustrating a rechargeable battery1500having the function of detecting water contact according to still another embodiment of the present invention. The rechargeable battery1500may include battery710, circuit board720, cover case730A and, combination auxiliaries1510. In this case, water-soluble ink120may be applied on one or more of the combination auxiliaries1510. InFIG. 2J, the cover case730A is illustrated as a frame type, but the structure of the cover case730A is not limited thereto.

The combination auxiliaries1510may include a lead tap1511, an insulator1512, a receiving case1513, a label1514, and a reinforcing plate1515. The water-soluble ink120may be applied on at least one of the combination auxiliaries1510. InFIG. 2J, the water-soluble ink120is applied on the label1514.

In more detail, the lead tap1511electrically connects a positive electrode711and a negative electrode712of the battery710to the circuit board720. The lead tap1511may be formed of nickel or a nickel alloy.

The insulator1512is disposed between the lead tap1511and the battery710to insulate the lead tap1511, the positive electrode711and the negative electrode712of the battery710. The insulator1512may be formed of paper or plastic.

The receiving case1513is formed between the battery710and the cover case730A. The receiving case1513may be integrally combined with the cover case730where the circuit board720is received. The receiving case1513may be formed by injection molding.

The reinforcing plate1515is added on a wide surface of the battery710to protect the battery710from being scratched, struck or pierced. The reinforcing plate1515may be formed of injection molded plastic or a metal such as stainless steel. However, the present invention is not limited to the materials of the combination auxiliaries1510.

InFIG. 2J, the label1514surrounds at least a part of the battery710. An identification mark or the like is printed on the label1514in such a way that the label1514can both surround the battery710and be adhered to the cover case730A. Although inFIG. 2Jthe water-soluble ink120is applied on the label1514, the water-soluble ink120can be applied on at least one of the combination auxiliaries1510, thereby showing whether the rechargeable battery1500contacts water.

FIG. 3Ais a perspective view illustrating a rechargeable battery1600having the function of detecting water contact according to another embodiment of the present invention. The rechargeable battery1600may include a battery1610and water-soluble ink120. The water-soluble ink120may be applied on a surface of the battery1610, thereby showing whether the rechargeable battery1600contacts water.

FIG. 3Bis a perspective view illustrating a rechargeable battery1700having the function of detecting water contact according to another embodiment of the present invention. Water-soluble ink120is applied on the rechargeable battery1700in a plurality of marks to form an area210for detecting water contact. Therefore, it is possible to visually and easily determine whether the rechargeable battery1700contacts water.

FIG. 3Cis a perspective view illustrating a rechargeable battery1800having the function of detecting water contact according to another embodiment of the present invention.FIG. 3Dis an exploded perspective view illustrating the rechargeable battery1800shown inFIG. 3C. Referring toFIGS. 3C and 3D, the rechargeable battery1800may include an electrode assembly1810, a can1820containing the electrode assembly1810, and a structure for completing electrical connection1830to positive and negative electrodes (described below) of the electrode assembly1810, externally exposes the positive and negative electrodes (described below) within electrode assembly1810, and closes the opening in the can1820. Water-soluble ink120is applied on one of the can1820and the structure for completing electrical connection1830, thereby showing whether the rechargeable battery1800contacts water. In more detail, the electrode assembly1810may be formed by laminating and spirally winding a positive electrode plate1811, a negative electrode plate1812, and a separator1813.

The positive electrode plate1811may include a positive electrode collector (not shown) and a positive electrode active material layer (not shown). The positive electrode active material layer may include a layered compound containing lithium, a binder improving the binding force, and a conductive material improving conductivity. The positive electrode collector is generally formed of aluminum (Al), functions as a path for moving electrical charges occurring in the positive electrode active material layer and supports the positive electrode active material layer. The positive electrode active material layer is attached onto the wide surface of the positive electrode plate1811. An uncoated portion (not shown) of the positive electrode plate1911(where the positive electrode active material layer is not formed) is formed in one side end of the positive electrode plate1811. A positive electrode tap1814may be attached to the uncoated portion of the positive electrode plate1811.

The negative electrode plate1812may include a negative electrode collector (not shown) and a negative electrode active material layer (not shown). The negative electrode active material layer may include carbon or graphite and a binder improving the binding force between particles of the negative active material layer. The negative electrode collector is generally formed of copper (Cu), functions as a path for moving electrical charges occurring in the negative electrode active material layer and supports the negative electrode active material layer. The negative electrode active material layer is attached onto the wide surface of the negative electrode plate1812. An uncoated portion (not shown) of the negative electrode plate1812(where the negative electrode active material layer is not formed) is formed in one side end of the negative electrode plate1812. A negative electrode tab1815may be attached to the uncoated portion of the negative electrode plate1812.

The separator1813is disposed between the positive electrode plate1811and the negative electrode plate1812to insulate the positive electrode plate1811and the negative electrode plate1812and pass through charges from the positive electrode plate1811and the negative electrode plate1812. The separator1813is generally formed of polyethylene (PE) or polypropylene (PP), but the present invention is not limited thereto.

The structure for completing the electrical connection1830may be electrically connected to the positive electrode and the negative electrode of the electrode assembly1810to externally expose the positive electrode and the negative electrode of the electrode assembly1810, and close the opening in the can1820. An example of the structure for finishing electrical connection1830, includes a cap plate1831, an electrode terminal1832, an insulating gasket1833, a terminal plate1834, an insulating plate1835, and an insulating case1836. An electrolyte injection hole1831aand a safety vent1831care formed on a top surface of the cap plate1831. The cap plate1831is electrically connected to the positive electrode tab1814and closes the opening of the can1820through a welding method and the like. The electrolyte injection hole1831amay be sealed by an electrolyte injection hole stopper1831b. The electrode terminal1832is received in a central hole of the cap plate1831and is electrically connected to the negative electrode tab1815. The insulating gasket1833covers the body portion of the electrode terminal1832to insulate the cap plate1831and the electrode terminal1832. The insulating case1836includes holes or spaces providing for the positive electrode tab1814and the negative electrode tab1815to externally protrude. The insulating case1836is disposed on the top surface of the electrode assembly1810and insulates the top surface of the electrode assembly1810. The terminal plate1834including a hole for pressing and fixing an end portion of the electrode terminal1832is combined with the end portion of the electrode terminal1832. The insulating plate1835insulates the cap plate1831and the terminal plate1834. The insulating gasket1833and the insulating case1836may be formed of an insulating material such as polypropylene resin or polyethylene resin. The cap plate1831, the electrode terminal1832and the terminal plate1834may be formed of a conductive metal, such as aluminum or nickel, or a conductive metal alloy such as an alloy containing aluminum or nickel.

The area210for detecting water contact may be applied either on the outer portion of the can1820or the material for finishing electrical connection1830of the rechargeable battery1800. A groove (not shown) having a very shallow depth may be formed in the can1820or the material for finishing electrical connection1830. The water-soluble ink120may be applied in the groove. When the rechargeable battery1800contacts water, the area210for detecting water contact spreads or is removed, thereby detecting whether there has been water contact.

FIG. 3Eis a perspective view illustrating a rechargeable battery1900having the function of detecting water contact according to another embodiment of the present invention.FIG. 3Fis an exploded perspective view illustrating the rechargeable battery1900shown inFIG. 3E. Referring toFIGS. 3D,3E and3F, the rechargeable battery1900may include an electrode assembly1810and a pouch1910containing the electrode assembly1810.

The electrode assembly1810may have the same configuration as the rechargeable battery1800. The electrode assembly1810may include a separator1813containing polymer electrolyte.

The pouch1910contains the electrode assembly1810and externally exposes a positive electrode tab1814and a negative electrode tab1815. The pouch1910may be formed as a multi layer film by laminating a plurality of layers. The multi layer film may be formed of an inner layer, for example, a heat bonding layer, formed of casted polypropylene (CPP), a middle barrier layer formed of aluminum, and an external protective layer formed of nylon. The pouch1910may include a lower film1911in which a receiving groove1911ais formed to contain the electrode assembly1810and an upper film1912that closes the opening of the lower film1911. The lower film1911and the upper film1912may be attached to each other by heating the layer where the lower film1911and the upper film1912contact each other. A positive/negative electrode insulating tape1920that is disposed between the lower film1911and the upper film1912may be thermally adhered to the pouch1910. However, the present invention is not limited to the material of the pouch1910and the configuration thereof.

The water-soluble ink120may be applied on an outer portion of the pouch1910in area210. As shown inFIG. 3E, the water-soluble ink120may be formed in a plurality of marks and may be applied on the outer surface of an area1914where the lower film1911and the upper film1912are thermally attached to each other, and may be applied on the wide surface1915of the pouch1910. Accordingly, when the area210for detecting water contact formed on the pouch1910contacts water, it is possible to visually detect a change, such as spreading of the area210for detecting water contact, so that it is possible to immediately detect whether the pouch1910contacts water.

In the circuit board having the function of detecting water contact of according to an aspect of the present invention, water-soluble ink is applied on a substrate in advance, so that a label attaching process is skipped, making it possible to improve the production efficiency of the circuit board.

The battery pack having the function of detecting water contact according to an aspect of the present invention is formed by applying water-soluble ink thereon in advance, so that a label attaching process is skipped, making it possible to improve the production efficiency of the battery pack.

The rechargeable battery having the function of detecting water contact according to an aspect of the present invention is formed by applying water-soluble ink on an outer surface thereof in advance, so that a label attaching process is skipped, making it possible to improve the production efficiency of the rechargeable battery.

Aspects of the present invention include forming an area for detecting water contact using water-soluble ink on at least one of the circuit board, the cover case, and the battery, thereby leading to a prompt determination of which part of the circuit board, the cover case, or the battery contacts water.

The effects of these aspects of the present invention have been briefly described above to clearly demonstrate the essence of the invention, and the corresponding features of these aspects of the present invention have been described above in detail.