KR20160112417A - Battery Pack Having Overcharge Protection Structure - Google Patents

Abstract

The present invention relates to a battery pack including a safety structure, capable of blocking applied power to guarantee the safety of the battery pack in an overcharging state of the battery pack. The battery pack includes: at least two battery cells installed in the battery pack, or a battery module including the battery cells as unit batteries; a protecting circuit part electrically connected with the battery cells or battery module and a safety device, and transmitting a power blocking signal to the safety device in the overcharging state of the battery pack; and the safety device connected in series between the battery cells or battery module and an external charging and discharging device, and blocking power applied from the external charging and discharging device by the power blocking signal of the protecting circuit part.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a battery pack having an overcharge protection structure,

The present invention relates to a battery pack including a safety structure for preventing overcharge.

BACKGROUND ART [0002] In recent years, rechargeable secondary batteries have been widely used as energy sources for wireless mobile devices. The secondary battery is also attracting attention as an energy source for electric vehicles and hybrid electric vehicles, which are proposed to solve air pollution of existing gasoline vehicles and diesel vehicles using fossil fuels. Therefore, the application of the secondary battery is diversified due to the advantages of the secondary battery, and it is expected that the secondary battery will be applied to many fields and products in the future.

As the application fields and products of the secondary battery are diversified, the type of the battery is also diversified to provide an appropriate output and capacity. In addition, there is a strong demand for miniaturization and weight reduction of cells applied to the field and products.

For example, a small mobile device such as a mobile phone, a PDA, a digital camera, a smart pad, a notebook computer, and the like is one or three small and lightweight battery cells per device corresponding to the tendency to miniaturize the products. On the other hand, a middle- or large-sized device such as an electric bicycle, an electric vehicle, a hybrid electric vehicle, etc., uses a battery module (also referred to as a "battery pack") in which a large number of battery cells are electrically connected, Since the size and weight of the battery module are directly related to the accommodating space and output of the middle- or large-sized device, manufacturers try to manufacture a battery module as small and light as possible.

In the conventional middle- or large-sized secondary battery module, a plurality of unit cells are mounted in a case (housing) of a predetermined size and are electrically connected to each other, and the voltage, current, And a circuit section for controlling the display section.

As described above, various types of secondary modules are being used in the field of medium to large-sized devices. Accordingly, various types of electric modules capable of providing electric capacity and output corresponding thereto have been demanded. Furthermore, The required capacity and output are also changed accordingly, so the design of the battery module must be changed.

On the other hand, safety is one of the most important issues in a secondary battery and a battery module including a plurality of the secondary battery. Particularly, since the battery modules of high power and large capacity are used in large-sized devices such as electric bicycles and electric vehicles, they are subjected to a variety of large external forces such as shocks and vibrations from the outside. Furthermore, a lithium secondary battery, which has been recently subjected to a great deal of interest and research as to the possibility of its use as a unit cell constituting a battery module, has a problem of low safety. Therefore, the safety problem of the battery module in which a large number of unit cells are concentrated may be more serious.

The safety problem of the battery module is largely caused by heat due to overcharging, internal short-circuiting of the module components due to external impact, and the like. In order to solve the problems of damage and heat generation of a unit cell due to overcharging, over-discharge, etc., a battery module generally includes a BMS (Battery Management System) capable of sensing current and voltage of a unit cell and a temperature of the battery system, And a circuit part. Therefore, when the overcurrent, overvoltage, overheat, or the like occurs, the current is cut off, thereby protecting the unit cell and securing the safety.

In some prior arts, the electrode terminal portions of the unit cells included in the battery module are broken to cut off the connection, or the battery module may be physically deformed due to the volume change at the time of swelling of the battery module, Structures for blocking electrical connection are applied.

Since the BMS does not perform any control from the BMS at the same time as the malfunction or malfunction of the BMS, the power switch is continuously kept on, so that the battery module assembly is constantly charged and discharged even in an abnormal operating state. And even in the case of physical shutdown, ignition may occur when the battery module is not shut off before the exact point in time when the battery module is ignited, resulting in low accuracy.

Therefore, there is a high need for techniques to fundamentally solve these problems.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art and the technical problems required from the past.

An object of the present invention is to provide a protection circuit for monitoring the voltage of battery cells or battery modules in real time in order to secure the safety of the battery pack in an overcharged state of the battery pack, And a safety device that cuts off the power applied by the blocking signal, thereby solving a safety problem such as ignition and explosion of the battery.

In order to achieve the above object, a battery pack according to the present invention includes a safety structure for shutting off a power applied to a battery pack in order to secure the safety of the battery pack in an overcharged state of the battery pack,

A battery module including at least two battery cells or battery cells mounted in the battery pack as unit cells;

A protection circuit part electrically connected to the battery cells or the battery module and a safety device for transmitting a power cutoff signal to the safety device in an overcharged state of the battery pack; And

A safety device which is connected in series between the battery cells or the battery module and the external charge / discharge device and which cuts off power supplied from the external charge / discharge device by a power cutoff signal of the protection circuit;

As shown in FIG.

Therefore, the battery pack according to the present invention includes: a protection circuit part for monitoring the voltage of the battery cells or the battery modules in real time in order to secure the safety of the battery pack in an overcharged state of the battery pack; And a safety device that transmits a shutoff signal and cuts off the power supplied by the shutoff signal, thereby providing an effect of solving safety problems such as ignition and explosion of the battery.

In one specific example, the protection circuit section includes a trigger circuit for monitoring the voltage of the battery cells or the battery module in real time, and a protection circuit And a power switching element for transmitting the power.

At this time, the trigger circuit of the protection circuit part may be configured to monitor the voltage of the battery pack in real time, and to determine that the battery pack is in an overcharge state when the predetermined set voltage is reached.

Generally, in the case of a battery pack included in a middle- or large-sized device, it is tested whether the battery pack is ignited according to the SOC (State of Charge) value of the charging voltage. For example, The SOC can be set in a range between 120% and 125%, and the SOC can be set to 125%.

Therefore, based on the information obtained through the safety test, it is possible to change the set voltage according to the type and the type of the applied device.

On the other hand, the safety device has a structure for shutting off the power applied from the external charge / discharge device by a power cut-off signal of the protection circuit part, for example, a power disconnection device can be preferably applied.

In one specific example, the power-off device includes a bus bar for electrically connecting the battery cells or the battery module to the external charge / discharge device, and a structure including an initiator and a peony for rupturing the bus bar ≪ / RTI >

The bus bar having such a structure includes a first connection portion protruding to the outside of the power cutoff device for connection to the battery cells or the battery module and a second connection portion protruding to the outside of the power cutoff device for connection to the external charge / discharge device And a connecting portion connecting the first connecting portion and the second connecting portion to each other. The connecting portion is connected in series with the charging / discharging device, the battery cells or the battery module, and the connection structure inside the bus bar is physically broken, Blocking structure.

Specifically, the initiator may have a structure in which the initiator is detonated in response to a power shutoff signal of the protection circuit portion, and the connection portion of the bus bar is broken by the explosion of the pecker to interrupt current flow.

The battery pack having such a structure includes a base plate on which the battery cells or the battery module are mounted, and an upper cover plate which is fixed on the base plate and forms the upper surfaces of the battery cells or the battery module. The protection circuit unit and the safety device may be configured to be mounted on one outer surface of the upper cover plate.

The battery cell according to the present invention may be a plate-shaped battery cell so as to provide a high lamination ratio in a limited space. For example, the battery cell of the laminate sheet may have an electrode assembly embedded therein.

Specifically, the laminate sheet is provided with a receiving portion for mounting the electrode assembly, and a separate sheet separated from the sheet or a sheet extending therefrom is thermally fused with the electrode assembly mounted on the receiving portion, However, the present invention is not limited thereto.

Generally, the battery cell may be a lithium ion battery or a lithium secondary battery, but is not limited thereto.

For reference, a lithium secondary battery is composed of a positive electrode, a negative electrode, a separator, and a nonaqueous electrolyte solution containing a lithium salt.

The positive electrode is prepared, for example, by coating a mixture of a positive electrode active material, a conductive material and a binder on a positive electrode current collector, and then drying the mixture. Optionally, a filler may be further added to the mixture.

The cathode active material may be a layered compound such as lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), or a compound substituted with one or more transition metals; Lithium manganese oxides such as Li _{1 + x} Mn _{2 -x} O ₄ (where x is 0 to 0.33), LiMnO ₃ , LiMn ₂ O ₃ , LiMnO ₂ and the like; Lithium copper oxide (Li ₂ CuO ₂ ); Vanadium oxides such as LiV ₃ O ₈ , LiFe ₃ O ₄ , V ₂ O ₅ and Cu ₂ V ₂ O ₇ ; A Ni-site type lithium nickel oxide expressed by the formula LiNi _1-x M _x O ₂ (where M = Co, Mn, Al, Cu, Fe, Mg, B or Ga and x = 0.01 to 0.3); Formula _{LiMn 2-x M x O 2} ( where, M = Co, Ni, Fe , Cr, and Zn, or Ta, x = 0.01 ~ 0.1 Im) or Li ₂ Mn ₃ MO ₈ (where, M = Fe, Co, Ni, Cu, or Zn); LiMn ₂ O _{4 in} which a part of Li in the formula is substituted with an alkaline earth metal ion; Disulfide compounds; Fe ₂ (MoO ₄ ) ₃ , and the like. However, the present invention is not limited to these.

The conductive material is usually added in an amount of 1 to 30% by weight based on the total weight of the mixture including the cathode active material. Such a conductive material is not particularly limited as long as it has electrical conductivity without causing chemical changes in the battery, for example, graphite such as natural graphite or artificial graphite; Carbon black such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and summer black; Conductive fibers such as carbon fiber and metal fiber; Metal powders such as carbon fluoride, aluminum, and nickel powder; Conductive whiskey such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives and the like can be used.

The binder is a component which assists in bonding of the active material and the conductive material and bonding to the current collector, and is usually added in an amount of 1 to 30% by weight based on the total weight of the mixture containing the cathode active material. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene , Polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butylene rubber, fluorine rubber, various copolymers and the like.

The filler is optionally used as a component for suppressing the expansion of the anode, and is not particularly limited as long as it is a fibrous material without causing a chemical change in the battery. Examples of the filler include olefin polymers such as polyethylene and polypropylene; Fibrous materials such as glass fibers and carbon fibers are used.

The negative electrode is manufactured by applying and drying a negative electrode active material on a negative electrode collector, and if necessary, the above-described components may be selectively included.

Examples of the negative electrode active material include carbon such as non-graphitized carbon and graphite carbon; _{Li x Fe 2 O 3 (0≤x≤1} ), Li x WO 2 (0≤x≤1), Sn x Me 1-x Me 'y O z (Me: Mn, Fe, Pb, Ge; Me' : Metal complex oxides such as Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, Halogen, 0 < x < Lithium metal; Lithium alloy; Silicon-based alloys; Tin alloy; _{SnO, SnO 2, PbO, PbO} 2, Pb 2 O 3, Pb 3 O 4, Sb 2 O 3, Sb 2 O 4, Sb 2 O 5, GeO, GeO 2, Bi 2 O 3, Bi 2 O 4, and Bi ₂ O ₅ ; Conductive polymers such as polyacetylene; Li-Co-Ni-based materials and the like can be used.

The separation membrane is interposed between the anode and the cathode, and an insulating thin film having high ion permeability and mechanical strength is used. The pore diameter of the separator is generally 0.01 to 10 mu m, and the thickness is generally 5 to 300 mu m. Such separation membranes include, for example, olefinic polymers such as polypropylene, which are chemically resistant and hydrophobic; A sheet or nonwoven fabric made of glass fiber, polyethylene or the like is used. When a solid electrolyte such as a polymer is used as an electrolyte, the solid electrolyte may also serve as a separation membrane.

The non-aqueous electrolyte solution containing a lithium salt is composed of a polar organic electrolyte and a lithium salt. As the electrolytic solution, a non-aqueous liquid electrolytic solution, an organic solid electrolyte, an inorganic solid electrolyte and the like are used.

Examples of the nonaqueous liquid electrolytic solution include N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma -Butyrolactone, 1,2-dimethoxyethane, tetrahydroxyfuran, 2-methyltetrahydrofuran, dimethylsulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane , Acetonitrile, nitromethane, methyl formate, methyl acetate, triester phosphate, trimethoxymethane, dioxolane derivatives, sulfolane, methylsulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate Nonionic organic solvents such as tetrahydrofuran derivatives, ethers, methyl pyrophosphate, ethyl propionate and the like can be used.

Examples of the organic solid electrolyte include a polymer electrolyte such as a polyethylene derivative, a polyethylene oxide derivative, a polypropylene oxide derivative, a phosphate ester polymer, an agitation lysine, a polyester sulfide, a polyvinyl alcohol, a polyvinylidene fluoride, Polymers containing ionic dissociation groups, and the like can be used.

Examples of the inorganic solid electrolyte include Li ₃ N, LiI, Li ₅ NI ₂ , Li ₃ N-LiI-LiOH, LiSiO ₄ , LiSiO ₄ -LiI-LiOH, Li ₂ SiS ₃ , Li ₄ SiO ₄ , Nitrides, halides and sulfates of Li such as Li ₄ SiO ₄ -LiI-LiOH and Li ₃ PO ₄ -Li ₂ S-SiS ₂ can be used.

The lithium salt is a material that is readily soluble in the non-aqueous electrolyte, for example, LiCl, LiBr, LiI, LiClO 4, LiBF 4, LiB 10 Cl 10, LiPF 6, LiCF 3 SO 3, LiCF 3 CO 2, LiAsF _{6, LiSbF 6, LiAlCl 4,} CH 3 SO 3 Li, CF 3 SO 3 Li, (CF 3 SO 2) 2 NLi, chloroborane lithium, lower aliphatic carboxylic acid lithium, lithium tetraphenyl borate and imide have.

For the purpose of improving the charge-discharge characteristics and the flame retardancy, the non-aqueous liquid electrolyte may contain, for example, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, glyme, N, N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, aluminum trichloride and the like are added It is possible. In some cases, a halogen-containing solvent such as carbon tetrachloride or ethylene trifluoride may be further added to impart nonflammability, or a carbon dioxide gas may be further added to improve high-temperature storage characteristics.

The present invention also relates to a method of operating a safety structure included in the battery pack,

(a) charging the battery cells or the battery module of the battery pack connected to the external charge / discharge unit;

(b) monitoring the voltages of the battery cells or the battery modules in the protection circuit part in real time;

(c) transmitting a power-off signal to the safety device when the voltage monitored in the step (b) reaches the set voltage;

(d) explosion of peonies in the safety device in response to the power-off signal of the protection circuit part, and breaking of the connection of the bus bar due to explosion of the peony, thereby blocking current flow;

To provide a safety structure operating method.

The set voltage of the process (c) may be set to 125% of SOC. In the process (d), the break time of the connection part of the bus bar may be 2 ms or less and the activation energy of the initiator may be 1.75 A / 0.5 ms or 1.2 A / 2 ms, and the resistance of the initiator may be in a range of 1 x 10 ^-1 m? Or less.

The present invention can also provide a device including the battery pack as a power source, wherein the device is a LEV (Light Electronic Vehicle), an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, May be selected from the group consisting of

The structure of these devices and their fabrication methods are well known in the art, and a detailed description thereof will be omitted herein.

As described above, the battery pack according to the present invention includes a protection circuit part for monitoring the voltage of the battery cells or the battery modules in real time in order to secure the safety of the battery pack in an overcharged state of the battery pack, And a safety device that transmits a shut-off signal when the voltage reaches the predetermined voltage and cuts off the power applied by the cut-off signal, thereby solving the safety problem such as ignition and explosion of the battery.

1 is a schematic view of a battery pack according to one embodiment of the present invention;
2 is a circuit diagram of the battery pack of FIG. 1
3 is a schematic diagram of the operation of the safety device of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings, but the present invention is not limited by the scope of the present invention.

FIG. 1 is a schematic view of a battery pack according to an embodiment of the present invention, and FIG. 2 is a schematic view illustrating a circuit diagram of the battery pack of FIG.

Referring to FIG. 1, a battery pack 100 includes a battery module 110 in a battery pack 100, and includes a base plate 121 on which the battery module 110 is mounted, And an upper cover plate 122 fixed on the base plate 121 to form an upper surface of the battery module 110.

The protection circuit unit 130 and the safety device 140 are mounted on one outer surface of the upper cover plate 122. The protection circuit unit 130 is electrically connected to the battery module 110 and the safety device 140 .

The protection circuit unit 130 monitors the voltage of the battery module 110 in real time and transmits a power cutoff signal to the safety device 140 when the voltage of the battery pack 100 reaches the set voltage, 140 are configured to cut off the power applied from the outside by the power supply cut-off signal of the protection circuit part 130.

In this structure, the protection circuit 130 includes a trigger circuit 131 for monitoring the voltage of the battery module 110 in real time, and a power supply shutdown signal to the safety device 140 And a power switching element 132 for transmitting the power switching element 132 to the power switching element 132.

When the voltage of the battery pack 100 reaches the set voltage, the trigger circuit 131 of the protection circuit unit 130 determines that the battery pack 100 is in an overcharged state, And transmits a power-off signal to the safety device 140. [

Next, a method of operating the safety structure according to the present invention will be described with reference to FIG. 2. Referring to FIG. 2, a process of charging the battery module 110 of the battery pack 100 connected to the external charge / discharge device 200, A process of monitoring the voltage of the battery module 110 in real time in the control unit 130, a process of transmitting a power shutdown signal to the safety device 140 when the voltage monitored by the protection circuit unit 130 reaches SOC 125% (See FIG. 3) in the safety device 140 in response to the power-off signal of the protection circuit part 130 and the connection part of the bus bar (see FIG. 3) And breaking the current flow.

Fig. 3 shows a schematic diagram of the operation of the safety device of Fig.

3, the safety device 140 is a power disconnection device and includes a bus bar 150 for electrically connecting the battery module 110 and the external charge / discharge device 200, And an initiator 161 and a peony solution 162 for rupturing the bus bar 150 are included therein.

Specifically, the bus bar 150 includes a first connection part 151 protruded to the outside of the power cutoff device 141 for connection to the battery module 110, And a second connection part 152 protruding outward from the first connection part 141 and a connection part 153 connecting the first connection part 151 and the second connection part 152 to each other.

The initiator 161 transmits a power shutoff signal from the protection circuit unit 130 at an SOC of 120% which is determined to be an overcharge state of the battery pack 100. The initiator 161 responds to the shutoff signal of the protection circuit unit 130, And the connection portion 153 of the bus bar 150 is broken by the explosion of the peony 162, thereby blocking the current flow.

1 to 3, the battery pack 100 according to the present invention is configured such that the voltage of the battery module 110 is lowered in order to secure the safety of the battery pack 100 in an overcharged state of the battery pack 100, And a safety device (140) for transmitting a blocking signal when the set voltage is reached by the protection circuit part (130) and cutting off the power applied by the blocking signal, It is possible to solve the problem of safety such as ignition and explosion.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (19)

A battery pack comprising a safety structure that cuts off an applied power supply in order to secure the safety of the battery pack in an overcharged state of the battery pack,
A battery module including at least two battery cells or battery cells mounted in the battery pack as unit cells;
A protection circuit part electrically connected to the battery cells or the battery module and a safety device for transmitting a power cutoff signal to the safety device in an overcharged state of the battery pack; And
A safety device which is connected in series between the battery cells or the battery module and the external charge / discharge device and which cuts off power supplied from the external charge / discharge device by a power cutoff signal of the protection circuit;
And the battery pack (10). 2. The battery pack according to claim 1, wherein the protection circuit part comprises: a trigger circuit for monitoring the voltage of the battery cells or the battery module in real time; and a protection circuit And a power switching element for transmitting power. The battery pack according to claim 2, wherein the trigger circuit of the protection circuit part determines that the battery pack is overcharged when the voltage of the battery pack reaches the set voltage. The battery pack according to claim 3, wherein the set voltage is set in a range between 120% of SOC (State of Charg) and 125% of SOC. The battery pack according to claim 4, wherein the set voltage is SOC (State of Charge) of 125%. The battery pack according to claim 1, wherein the safety device is a power disconnection device. [7] The apparatus of claim 6, wherein the power cutoff device includes a bus bar for electrically connecting the battery cells or the battery module to the external charge / discharge device, and a structure including an initiator and a peony for rupturing the bus bar The battery pack comprising: The battery charger of claim 7, wherein the bus bar comprises: a first connection part protruding outside the power cut-off device for connection to the battery cells or the battery module; and a second connection part protruding outside the power cut- And a connection part connecting the first connection part and the second connection part to each other. 9. The battery pack according to claim 8, wherein the initiator detonates the peanut in response to a power shut-off signal of the protection circuit portion, and the connection portion of the bus bar is broken by the explosion of the peanut, thereby blocking current flow. The battery pack according to claim 1, wherein the battery pack comprises a base plate on which the battery cells or the battery module are mounted, and an upper cover plate fixed on the base plate to form upper surfaces of the battery cells or the battery module. wherein the protection circuit part and the safety device are mounted on an outer surface of one side of the upper cover plate. The battery pack according to claim 1, wherein the battery cell has a structure in which an electrode assembly is embedded in a laminate battery case. The battery pack according to claim 10, wherein the battery cell is a lithium secondary battery. A method of operating a safety structure included in a battery pack according to claim 1,
(a) charging the battery cells or the battery module of the battery pack connected to the external charge / discharge unit;
(b) monitoring the voltage of the battery cells or the battery module in the protection circuit part in real time;
(c) transmitting a power-off signal to the safety device when the voltage monitored in the step (b) reaches the set voltage;
(d) explosion of peonies in the safety device in response to the power-off signal of the protection circuit part, and breaking of the connection of the bus bar due to explosion of the peony, thereby blocking current flow;
/ RTI > 14. The method of claim 13, wherein the set voltage of step (c) is SOC 125%. 14. The method as claimed in claim 13, wherein, in the step (d), the breakage time of the connection part of the bus bar is 2 ms or less. 14. The method of claim 13, wherein the activation energy of the initiator is 1.75 A / 0.5 ms or 1.2 A / 2 ms. 17. The method of claim 16, wherein the resistance of the initiator is in the range of 1 x 10 < ^-1 > 11. A device comprising a battery pack according to claim 1. 19. The device of claim 18, wherein the device is selected from a LEV (Light Electronic Vehicle), an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, and a power storage device.

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