Patent Description:
Fuse devices which are currently used in secondary batteries include a positive temperature coefficient (PTC) thermistor, a thermal cut-out (TCO), a thermal fuse, etc. However, in the case of the thermal fuse, there is a disadvantage of one-time use, and although the PTC thermistor or the TCO is repeatedly usable, there is a disadvantage that the resistance thereof increases as the operation is repeated, which increases the overall resistance on the circuit.

In addition, all of the above-mentioned devices operate by heat generated by an overcurrent. That is, the above-mentioned devices correspond to devices that operate to block the flow of a current when the overcurrent is generated on a circuit current path due to overcharging, etc., and thus the temperature increases.

Therefore, in the case of the above-mentioned devices, it is possible to block the overcurrent by operating after a situation where safety may be threatened due to the heat, and it is impossible to block the overcurrent immediately when a cause for increasing the temperature occurs.

In addition, in the case of the above-mentioned devices, since the devices operate simply according to the temperature, it is difficult to use the devices in a secondary battery exhibiting a high output such as a battery pack used in a vehicle. In other words, in the case of a vehicle battery pack, a high c-rate is required, which also accordingly requires a large amount of heat. There is a problem in that the devices such as the PTC thermistor, the TCO, and the thermal fuse operate too early when placed in such a high temperature environment.

Therefore, there is a need for a secondary battery to which a device that is reusable and is usable even in an environment where a high current flows, and is capable of previously blocking the current when an event that may cause such a temperature rise occurs before the temperature rises is applied.

<CIT> relates to a battery cell with an electrochemical unit for generating electrical energy, two poles for providing and tapping the electrical energy, a discharge line which has an associated pole for external discharge. The tapped electrical energy is switchably electrically connectable, and a switching device which is designed to switch a direct or indirect galvanic connection and / or separation between the discharge line and the associated pole, in particular in a reversible form.

<CIT> relates to a battery cell with a conductor carrier which is connected to the battery cell via at least one electrical connection, the battery cell having an expansion device, the shape and / or dimensions of which can be changed by heating the battery cell and / or increasing the pressure inside the battery cell, characterized in that by means of the shape and / or dimensions modified expansion device at least one electrical connection between the battery cell and the conductor carrier can be mechanically interrupted.

The present disclosure is designed to solve the problems of the related art, and therefore the present disclosure is directed to providing a battery pack having a structure in which a current blocking member capable of previously blocking a current before the temperature of the battery pack rises by heat generated due to overcharging of the battery pack, etc. is installed.

The present invention is defined in the pending set of claims. According to claim <NUM>, the invention is a battery pack including a battery module assembly including a first battery module and a second battery module; a first connector connected to a first electrode of the first battery module; a second connector connected to a second electrode of the second battery module and spaced apart from the first connector; a switch configured to connect the first connector and the second connector; a current blocking member connected to one side of the switch in a longitudinal direction and configured to turn off the switch by causing a bending deformation when a potential difference formed between both electrodes of the battery module is equal to or greater than a reference value.

The battery module may include a plurality of battery cells electrically connected to each other.

One side of the switch in the longitudinal direction is formed as a free end to be in contact with the first connector and to release a contact state between the switch and the first connector by the bending deformation of the current blocking member, and the other side of the switch in the longitudinal direction is formed as a fixed end fixed to the second connector.

One side of the current blocking member in the longitudinal direction is a free end of which position is changeable by the bending deformation, and the other side of the current blocking member is a fixed end directly or indirectly connected to the battery module or a ground.

The current blocking member may include an electro active polymer (EAP) layer; a first metal layer formed on one side of the EAP layer; and a second metal layer formed on the other side of the EAP layer.

The EAP layer may include at least one polymer electrolyte selected from Nafion, polypyrrole, polyaniline and polythiophene.

The first metal layer and the second metal layer may include at least one metal selected from the group comprising platinum, silver and copper.

The first metal layer may be electrically connected to a negative electrode of the battery module, and the second metal layer may be electrically connected to a positive electrode of the battery module.

The current blocking member may be located above the switch, and the first metal layer may face the switch.

The battery pack may further include a connecting rod configured to connect between the switch and the first metal layer and having non-conductivity.

The connecting rod may be hinged to each of the switch and the first metal layer.

In another aspect of the present disclosure, there is provided a vehicle including the battery pack as described above.

According to an aspect of the present disclosure, in the use of a battery pack, before an event such as overheating and/or explosion of the battery pack due to overcharging of the battery pack, etc. occurs, a current may be blocked by previously detecting a potential difference equal to or greater than a reference value that causes occurrence of the event, thereby securing safety in the use of the battery pack.

First, referring to <FIG>, the overall configuration of a battery pack according to an embodiment of the present disclosure will be described.

<FIG> is a diagram showing a battery pack according to an embodiment of the present disclosure. <FIG> is a diagram showing an individual battery module included in the battery pack shown in <FIG>. <FIG> is a diagram showing an individual battery cell included in the battery module shown in <FIG>. Also, <FIG> is a diagram showing a current blocking member applied to the battery pack shown in <FIG>. <FIG> is a diagram showing a shape deformation of the current blocking member when a potential difference equal to or greater than a reference value is formed between a first metal layer and a second metal layer of the current blocking member shown in <FIG>.

First, referring to <FIG>, the battery pack according to an embodiment of the present disclosure includes a plurality of battery modules <NUM>, a first connector <NUM>, a second connector <NUM>, a switch <NUM>, a current blocking member <NUM>, and a connecting rod <NUM>.

Referring to <FIG> and <FIG> together, the plurality of battery modules <NUM> forms one battery module assembly electrically connected to each other. The battery module <NUM> may include a plurality of battery cells <NUM> connected in series, in parallel, or a mixture of series and parallel with each other. In addition, a cell stack formed by electrically connecting the battery cells <NUM> may be electrically connected to a first electrode terminal <NUM> and a second electrode terminal <NUM> that are formed in outside of the battery module <NUM>.

In the drawings of the present disclosure, a case where the first electrode terminal <NUM> is a negative electrode terminal and the second electrode terminal <NUM> is a positive electrode terminal is shown as an example, but the present disclosure is not limited thereto, and a case where the first electrode terminal <NUM> is a positive electrode terminal and the second electrode terminal <NUM> is a negative electrode terminal may be possible.

Referring to <FIG>, as each of the battery cells <NUM> included in the battery pack, for example, a pouch type battery cell may be applied. Referring to <FIG>, the pouch type battery cell <NUM> may include an electrode assembly (not shown), an electrode lead <NUM>, a cell case <NUM>, and a sealing tape <NUM>.

Although not shown in the drawings, the electrode assembly has a structure in which separators are interposed between positive electrode plates and negative electrode plates that are alternately and repeatedly stacked, and the separators may be positioned on both outermost sides for insulation.

The negative electrode plate includes a negative electrode current collector and a negative electrode active material layer coated on one surface or both surfaces thereof, and at one end thereof, a negative electrode non-coating portion which is not coated with a negative electrode active material is formed and a negative electrode non-coating region functions as a negative electrode tab.

The positive electrode plate includes a positive electrode current collector and a positive electrode active material layer coated on one surface or both surfaces thereof, and at one end thereof, a positive electrode non-coating portion which is not coated with a positive electrode active material is formed and a positive electrode non-coating region functions as a positive electrode tab.

In addition, the separator is interposed between the negative electrode plate and the positive electrode plate to prevent direct contact between the electrode plates having different polarities and may be formed of a porous material to enable the movement of ions by using an electrolyte as a medium between the negative electrode plate and the positive electrode plate.

The electrode lead <NUM> is connected to the electrode tab and is withdrawn to the outside of the cell case <NUM>. The battery cells <NUM> adjacent to each other may be electrically connected in series, parallel, or a mixture of series and parallel through the electrode lead <NUM> to form a single cell stack.

The cell case <NUM> includes two regions of an accommodation portion 12a that accommodates the electrode assembly and a sealing portion 12b that extends in the circumferential direction of the accommodation portion 12a and is thermally fused in a state where the electrode lead <NUM> is withdrawn to seal the cell case <NUM>.

Although not shown in the drawings, the cell case <NUM> is sealed by contacting and thermally fusing edges of an upper case and a lower case configured as a multilayer pouch film in which a resin layer/metal layer/resin layer are sequentially stacked.

The sealing tape <NUM> is attached to the circumference of the electrode lead <NUM> and is interposed between the sealing portion 12b of the cell case <NUM> and the electrode lead <NUM>. The sealing tape <NUM> is a component for preventing the degradation of sealing property of the cell case <NUM> due to a low adhesion force between the inner surface of the cell case <NUM> and the electrode lead <NUM> in a region in which the electrode lead <NUM> is withdrawn in the sealing portion 12b of the cell case <NUM>.

Referring back to <FIG>, the first connector <NUM> and the second connector <NUM> may have the shape of a metal plate of a conductive material. The first connector <NUM> is fastened to the second electrode terminal <NUM> of the first battery module <NUM> located on one side of a pair of battery modules <NUM> adjacent to each other. In addition, the second connector <NUM> is fastened to the first electrode terminal <NUM> of the second battery module <NUM> located on the other side of the pair of battery modules <NUM> adjacent to each other. The first connector <NUM> and the second connector <NUM> are spaced apart from each other by a predetermined distance.

The switch <NUM> connects a pair of connectors <NUM> and <NUM> spaced apart from each other. Specifically, the switch <NUM> may be installed to connect between upper surfaces of each of the first connector <NUM> and the second connector <NUM>.

One side of the switch <NUM> in the longitudinal direction is formed as a free end which is in contact with the first connector <NUM> and moves together upon bending deformation of the current blocking member <NUM> such that a contact state between the switch <NUM> and the first connector <NUM> may be released. Unlike this, the other side of the switch <NUM> in the longitudinal direction is formed as a fixed end which is fixed to the second connector <NUM> by welding or the like.

The current blocking member <NUM> causes the bending deformation when voltage applied to both surfaces is equal to or greater than a reference value and is connected to the switch <NUM> by the connecting rod <NUM> to move the switch <NUM> to perform an off operation upon bending deformation.

In order to perform this function, the current blocking member <NUM> may be disposed above the switch <NUM>. In addition, one side of the current blocking member <NUM> in the longitudinal direction may be formed as a free end of which position may change by the bending deformation, and the other side of the current blocking member <NUM> in the longitudinal direction may be formed as a fixed end fixed directly or indirectly to the battery module <NUM> or the ground.

In order to allow the switch <NUM> to perform the off operation by the bending deformation of the current blocking member <NUM>, the connecting rod <NUM> connects the free end of the current blocking member <NUM> and the free end of the switch <NUM>.

The connecting rod <NUM> may be formed of, for example, a plastic material, and both ends thereof may be attached to the lower surface of the current blocking member <NUM> and the upper surface of the switch <NUM>, respectively.

Meanwhile, referring to <FIG>, in order to be able to block an overcurrent due to a shape deformation according to a potential difference formed between both surfaces, the current blocking member <NUM> may include an electro active polymer (EAP) layer <NUM>, a first metal layer <NUM> formed on one side surface of the EAP layer <NUM>, and a second metal layer <NUM> formed on the other side surface of the EAP layer <NUM>.

The EAP layer <NUM>, i.e., the electroactive polymer layer, corresponds to a layer formed of a polymer electrolyte having an excellent ion transfer property, and may include at least one polymer electrolyte selected from, for example, Nafion, polypyrole, polyaniline, and polythiophene.

The first metal layer <NUM> and the second metal layer <NUM> are formed on both surfaces of the EAP layer <NUM> and may be formed of a metal having excellent electrical conductivity. The metal layers <NUM> and <NUM> may include at least one metal selected from, for example, platinum (Pt), gold (Au), silver (Ag), and copper (Cu).

The current blocking member <NUM> causes the shape deformation when voltage equal to or greater than a reference value is applied through the metal layers <NUM> and <NUM> formed on both surfaces of the EAP layer <NUM>.

That is, the first metal layer <NUM> is electrically connected to the negative electrode of the battery module <NUM>, and the second metal layer <NUM> is electrically connected to the positive electrode of the battery module <NUM> such that a potential difference corresponding to the voltage of the battery module <NUM> is formed between the pair of metal layers <NUM> and <NUM>.

When the potential difference formed between the pair of metal layers <NUM> and <NUM> as described above reaches a large numerical value exceeding a safety range considering the specification of the battery module <NUM> due to an issue such as overcharging, etc., mobility cations present inside the polymer electrolyte forming the EAP layer <NUM> move in the direction of the negatively charged first metal layer <NUM> while hydrated in water. In this case, an osmotic pressure is caused by an imbalance in the ion concentration between the first metal layer <NUM> and the second metal layer <NUM>, which increases an amount of water molecules toward the negatively charged first metal layer <NUM>, and thus the bending deformation occurs in the current blocking member <NUM> in the direction toward the second metal layer <NUM>.

For such a shape deformation of the current blocking member <NUM> and a resulting operation of the switch <NUM>, the first metal layer <NUM> faces the switch <NUM> and is connected to the negative electrode of the battery module <NUM>, and the second metal layer <NUM> is connected to the positive electrode of the battery module <NUM> on the contrary thereto.

In addition, both ends of the connecting rod <NUM> are fixed to the first metal layer <NUM> and the switch <NUM>, respectively, and are formed of a non-conductive material. This is because if the connecting rod <NUM> has conductivity, the first metal layer <NUM> is connected to both the positive electrode and the negative electrode of the battery module <NUM> such that the current blocking member <NUM> may cause the bending deformation.

Meanwhile, the magnitude of the voltage that may cause the shape deformation of the current blocking member <NUM> varies depending on the type of the polymer electrolyte constituting the EAP layer <NUM> applied to the current blocking member <NUM>.

That is, the reference value of the voltage mentioned in the present specification may vary according to the type of the polymer electrolyte applied, and accordingly, a suitable polymer electrolyte may be selected according to the safety voltage range of each of the battery modules <NUM> constituting the battery pack to which the current blocking member <NUM> is applied, thereby quickly blocking the current when an event such as overcharging of the battery pack occurs.

Next, a modification of the connection structure of the current blocking member <NUM> and the switch <NUM> shown in <FIG> will be described with reference to <FIG>.

<FIG> is a diagram showing a modification of the connection structure of the current blocking member <NUM> shown in <FIG> and a connecting plate.

Referring to <FIG>, both ends of the connecting rod <NUM> may be hinged to the upper surface of the switch <NUM> and the first metal layer <NUM>, respectively. As such, when the connecting rod <NUM> is hinged to the switch <NUM> and the current blocking member <NUM>, a relative rotation between the switch <NUM>, the current blocking member <NUM>, and the connecting rod <NUM> is possible. Therefore, when a free end of the current blocking member <NUM> moves upward due to a bending deformation of the current blocking member <NUM>, a free end of the switch <NUM> may also move upward smoothly without a shape deformation, such as bending, of the connecting rod <NUM>.

As described above, the battery pack according to the present disclosure is configured to perform an on/off operation of the switch <NUM> that electrically connects between the battery modules <NUM> adjacent to each other by using the current blocking member <NUM> that causes the bending deformation according to the voltage of the battery module <NUM>, thereby securing safety in the use of the battery pack.

Claim 1:
A battery pack comprising:
a battery module assembly comprising a first battery module and a second battery module;
a first connector (<NUM>) connected to a first electrode (<NUM>) of the first battery module;
a second connector (<NUM>) connected to a second electrode (<NUM>) of the second battery module and spaced apart from the first connector (<NUM>);
a switch (<NUM>) configured to connect the first connector (<NUM>) and the second connector (<NUM>); and
a current blocking member (<NUM>) connected to one side of the switch (<NUM>) in a longitudinal direction,
wherein one side of the switch (<NUM>) in the longitudinal direction is formed as a free end to be in contact with the first connector (<NUM>) and said one side of the switch (<NUM>) configured to release a contact state between the switch (<NUM>) and the first connector (<NUM>) by a bending deformation of the current blocking member (<NUM>), and
wherein the other side of the switch (<NUM>) in the longitudinal direction is formed as a fixed end fixed to the second connector (<NUM>),
wherein one side of the current blocking member (<NUM>) in the longitudinal direction is a free end of which position is changeable by the bending deformation, and
wherein the other side of the current blocking member (<NUM>) is a fixed end directly or indirectly fixed to the battery module or a ground, and
the current blocking member (<NUM>) is connected to the switch (<NUM>) by a connecting rod (<NUM>) and the current blocking member (<NUM>) causes the bending deformation when voltage applied to both surfaces is equal to or greater than a reference value and is connected to the switch (<NUM>) by the connecting rod (<NUM>) to move the switch (<NUM>) to perform an off operation upon bending deformation.