KR20220068018A - Pouch type secondary battery - Google Patents

Abstract

A pouch-type secondary battery according to one embodiment of the present invention comprises: a pouch case including a main chamber for accommodating an electrode assembly; and a supplemental electrolyte kit arranged on at least one side of the main chamber, wherein the supplemental electrolyte kit includes: a storage unit having a first space in which a supplemental electrolyte is stored, and a second space separated from the first space by a stopper; an injection unit providing a path for moving the supplemental electrolyte to the main chamber; and a valve for controlling movement of gas in the main chamber to the second space by being opened and closed at a specific pressure value. The pouch-type secondary battery according to the present invention can include a supplementary electrolyte kit for supplementing an electrolyte that is depleted without increasing a thickness of a pouch case and securing an additional space.

Description

Pouch-type secondary battery {POUCH TYPE SECONDARY BATTERY}

The present invention relates to a pouch-type secondary battery including a supplementary electrolyte kit, and more specifically, to cope with an increase in pressure inside the pouch case and depletion of electrolyte due to gas generated in the process of using the secondary battery, supplementary electrolyte is accommodated. and a supplementary electrolyte kit, wherein the supplementary electrolyte is directed to a pouch-type secondary battery having a structure that can move from the supplementary electrolyte kit to the space in which the electrode assembly is disposed under certain conditions.

Secondary batteries capable of charging and discharging are widely used as energy sources or auxiliary power devices for mobile devices. In addition, the secondary battery is an electric vehicle (EV), a hybrid electric vehicle (HEV), and a plug-in hybrid electric vehicle that are being proposed as a solution to air pollution such as conventional gasoline and diesel vehicles using fossil fuels. It is also attracting attention as a power source such as (Plug-In HEV). Recently, in order to increase the driving distance of an electric vehicle, the development of a secondary battery with a higher energy density is required.

Conventionally, nickel-based secondary batteries such as nickel-cadmium batteries and nickel-hydrogen batteries have been used as types of secondary batteries, but have a high operating voltage, have a capacity about three times that of the nickel-based secondary batteries, and have a higher energy density per unit weight. The use of high lithium secondary batteries is rapidly increasing. A lithium secondary battery includes an electrode assembly having a structure in which a positive electrode plate and a negative electrode plate to which a positive electrode active material and a negative electrode active material are applied, respectively, are disposed with a separator interposed therebetween, an outer case for accommodating the electrode assembly, and an electrolyte solution impregnated in the electrode assembly. .

According to the shape of the external case, lithium secondary batteries are classified into can-type secondary batteries in which the electrode assembly is built into a metal can, and pouch-type secondary batteries in which the electrode assembly is built in a pouch case of a metal laminate sheet. It has the advantage of being inexpensive, high energy density, and easy to construct a large-capacity battery pack through series or parallel connection.

In general, in the lithium secondary battery, an electrolyte solution is decomposed as a side reaction during charging to generate gas. In addition, the electrolyte may be denatured by repeated charging and discharging. In particular, it is necessary to prevent lithium from precipitating on the surface of the anode, so-called lithium-plating (Li-plating) needs to be prevented. When lithium is precipitated, it causes a side reaction with the electrolyte and changes the kinetic balance of the secondary battery, which causes secondary battery deterioration such as capacity loss, and also affects the lifespan of the secondary battery and a safety problem in which the overcharge control function is lost. because there is As the amount of the electrolyte that can contribute to the electrochemical reaction decreases over time due to the decomposition and denaturation of the electrolyte, the charge/discharge efficiency and capacity retention ratio of the secondary battery are lowered, so that the secondary battery is replaced is needed

Therefore, as a pouch-type secondary battery that can replenish the electrolyte that is depleted during the use of the lithium secondary battery, the thickness of the battery cell does not increase and an additional member is not provided when assembling a module/pack, and the replenishment injection timing of the electrolyte can be adjusted. There is a high need for a pouch-type secondary battery.

KR 10-2010-0051403 A

The present invention is to solve the above problems, maintaining the thickness of the battery cell and providing a pouch-type secondary battery having a supplementary electrolyte kit for replenishing the depleted electrolyte without requiring additional space in the secondary battery aim to do

A pouch-type secondary battery according to an embodiment of the present invention includes a pouch case including a main chamber for accommodating an electrode assembly and a replenishment electrolyte kit disposed on at least one side of the main chamber, wherein the replenishment electrolyte kit is for replenishment A storage unit including a first space in which the electrolyte is stored and a second space separated from the first space by a stopper, an injection unit providing a passage through which the replenishment electrolyte moves to the main chamber; and a valve for controlling movement of the gas of the main chamber to the second space by being opened and closed at a specific pressure value.

In the pouch-type secondary battery according to an embodiment of the present invention, when the valve is opened, the gas enters the second space, and the pressure received by the replenishing electrolyte is increased by the force of the gas pressing the stopper, so that the injection unit The supplementary electrolyte may be supplied to the main chamber.

In the pouch-type secondary battery according to an embodiment of the present invention, the replenishment electrolyte kit may be formed on a folding surface on which the pouch case is folded.

In the pouch-type secondary battery according to an embodiment of the present invention, the supplementary electrolyte kit is formed along a folding surface on which the pouch case is folded and a sealing surface adjacent to the folding surface.

In the pouch-type secondary battery according to an embodiment of the present invention, the storage unit may be formed in the form of a tube.

In the pouch-type secondary battery according to an embodiment of the present invention, the storage unit may be made of any one of polypropylene, polyethylene, or a combination thereof.

In the pouch-type secondary battery according to an embodiment of the present invention, the stopper may be in close contact with the inner surface of the storage unit and may be movable by pressure.

In the pouch-type secondary battery according to an embodiment of the present invention, the stopper may be formed of a rubber material.

In the pouch-type secondary battery according to an embodiment of the present invention, the valve may be a solenoid valve.

In the pouch-type secondary battery according to an embodiment of the present invention, the valve may be opened at 3.5 kgf/cm ² or more and closed at 1.5 kgf/cm ² or less.

The pouch-type secondary battery according to an embodiment of the present invention may further include a BMS (Battery Management System) sensing terminal connected to the valve.

The pouch-type secondary battery according to an embodiment of the present invention may further include a compression pad connected to the BMS sensing terminal and disposed on the outer surface of the pouch case to sense a change in volume of the pouch case.

In the pouch-type secondary battery according to an embodiment of the present invention, the injection unit may be formed of a syringe capable of only moving the replenishment electrolyte from the first space to the main chamber direction.

As mentioned above, the pouch-type secondary battery according to the present invention includes a supplementary electrolyte kit for replenishing the depleted electrolyte without increasing the thickness of the pouch case and securing additional space.

Therefore, when a specific pressure value is formed due to the generation of gas in the main chamber, as the valve is opened, the gas flows into the replenishment electrolyte kit, pressure is applied to the replenishment electrolyte, and the replenishment electrolyte is supplied to the main chamber of the pouch case.

Such supplemental electrolyte supply prevents deterioration of battery performance, prevents denaturation of electrolyte, and in particular, prevents lithium-plating phenomenon in which lithium is deposited on the surface of the anode to ensure long lifespan and stability of secondary batteries. have.

1 is a view showing a method in which a conventional basic pouch case is folded;
2A and 2B are plan cross-sectional views of a pouch-type secondary battery according to an embodiment of the present invention;
3 is a side cross-sectional view of a pouch-type secondary battery according to an embodiment of the present invention; and
4 is a flowchart illustrating a driving method of a valve according to an embodiment of the present invention.

The objects, specific advantages and novel features of the present invention will become more apparent from the following detailed description and preferred embodiments taken in conjunction with the accompanying drawings. In the present specification, in adding reference numbers to the components of each drawing, it should be noted that only the same components are given the same number as possible even though they are indicated on different drawings. In addition, terms such as "one side", "the other side", "first", "second" etc. are used to distinguish one component from another component, and the component is limited by the terms not. Hereinafter, in describing the present invention, detailed descriptions of related known technologies that may unnecessarily obscure the gist of the present invention will be omitted.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings, wherein like reference numerals indicate like members.

1 shows a state in which a pouch case basically used in the prior art is folded.

The secondary battery (1) of the present invention is a pouch-type secondary battery (1) in which the electrode assembly (a) is built into the pouch case (100). Referring to FIG. 1 , the pouch-type secondary battery 1 is sealed while one side of the pouch case 100 is folded and the other side is sealed. The folded surface of the pouch case 100 is referred to as a folding surface 120 , and the remaining surface to be sealed is referred to as a sealing surface 130 .

2A to 2B are plan cross-sectional views illustrating a pouch-type secondary battery 1 according to an embodiment of the present invention.

The pouch-type secondary battery 1 according to an embodiment of the present invention is disposed on at least one side of the pouch case 100 including the main chamber 110 accommodating the electrode assembly a and the main chamber 110 . and a replenishment electrolyte kit 200 that becomes, and the replenishment electrolyte kit 200 is separated from the first space 211 by the first space 211 and the stopper 213 in which the replenishment electrolyte (s) is stored. A storage unit 210 including a second space 212 to be, the replenishment electrolyte (s) injection unit 220 to provide a passage to move to the main chamber (110); and a valve 230 that controls movement of the gas in the main chamber 110 to the second space 212 by being opened and closed at a specific pressure value.

Referring to FIGS. 2A and 2B , in the pouch-type secondary battery 1 of the present invention, it can be seen that the supplementary electrolyte kit 200 is disposed on one side of the pouch case 100 . The pouch case 100 of the present invention includes a main chamber 110 accommodating the electrode assembly (a). The main chamber 110 accommodates the electrode assembly (a) and the electrolyte, and also accommodates gas generated by decomposition of the electrolyte as a side reaction during charging of the secondary battery.

Replenishment electrolyte kit 200 is disposed on at least one side of the main chamber (110). It may be disposed on one side of the main chamber 110 as shown in FIG. 2A , and may be disposed on one side of the main chamber 110 as shown in FIG. 2B and formed in a shape extending in the other direction.

The replenishment electrolyte kit 200 includes a storage unit 210 , an injection unit 220 , and a valve 230 .

The storage unit 210 may be formed to extend along the folding surface 120 as shown in FIG. 2A , or may be formed to extend along the folding surface 120 and the sealing surface 130 as shown in FIG. 2B . The storage unit 210 includes a first space 211 and a second space 212 , the first space 211 and the second space 212 are separated by a stopper 213 . The first space 211 contains the replenishing electrolyte (s), and the second space 212 is formed as an empty space and gas enters from the main chamber 110 as the valve 230 to be described later is opened. will come The second space 212 accommodates the replenishment electrolyte (s). A mechanism by which the replenishment electrolyte (s) enters the main chamber 110 will be described later.

The injection unit 220 provides a passage through which the supplementary electrolyte (s) moves to the main chamber 110 .

The valve 230 opens and closes at a specific pressure value. The specific pressure value refers to a pressure applied to the pouch case 100 due to generation of gas in the main chamber 110 . The valve 230 is disposed on a path communicating the main chamber 110 and the second space 212 . Accordingly, the valve 230 controls the movement of the gas in the main chamber 110 to the second space 212 .

In the pouch-type secondary battery 1 according to an embodiment of the present invention, when the valve 230 is opened, the gas enters the second space 212 , and the gas is subjected to a force pressing the stopper 213 . As a result, the pressure received by the replenishment electrolyte (s) is increased so that the injection unit 220 may supply the replenishment electrolyte (s) to the main chamber 110 .

The supplementary electrolyte kit 200 of the present invention supplies the supplementary electrolyte (s) to the main chamber 110 in response to a pressure change due to gas generation in the main chamber 110 . When the pressure in the main chamber 110 is increased to form a specific pressure value, the valve 230 is opened. Accordingly, the gas in the main chamber 110 enters the second space 212 through the valve 230 . That is, as the volume of gas in the main chamber 110 expands to the second space 212 , the pressure of the main chamber 110 is lowered, and the pouch case 100 is torn or gas leaks due to the gas pressure. Reduces the probability of venting. Also, the gas entering the second space 212 presses the stopper 213 . The pressurized stopper 213 pressurizes the replenishment electrolyte (s), and the pressure of the first space 211 increases so that the injection unit 220 supplies the replenishment electrolyte (s) to the main chamber 110 .

In addition, as the stopper 213 moves to the first space 211 , the volume of the second space 212 increases and more gas flows into the second space 212 , and accordingly, the The gas pressure is lowered. At this time, when the pressure of the main chamber 110 is returned to below a specific pressure, the valve 230 is closed again and the supply of the supplementary electrolyte (s) through the injection unit 220 is also stopped.

In addition, when the pressure in the main chamber 110 increases again in the process of using the secondary battery 1, the opening and closing of the valve 230 as above is repeated, and accordingly, the replenishment electrolyte remaining in the first space 211 ( s) may be supplied back to the main chamber 110 or the process in which the supply is stopped may be repeated. Therefore, it is possible to effectively manage the internal pressure caused by the generation of gas in the battery 1 and to continuously supply the depleted electrolyte.

2A to 2B are plan sectional views showing a pouch-type secondary battery 1 according to an embodiment of the present invention, and FIG. 3 is a side sectional view showing a pouch-type secondary battery 1 according to an embodiment of the present invention. do.

In the pouch-type secondary battery 1 according to an embodiment of the present invention, the supplementary electrolyte kit 200 may be formed on the folding surface 120 on which the pouch case 100 is folded.

In the pouch-type secondary battery 1 according to an embodiment of the present invention, the supplementary electrolyte kit 200 includes a folding surface 120 on which the pouch case 100 is folded and a sealing surface 130 adjacent to the folding surface 120 . ) is formed according to

Referring to FIG. 2A , the electrolyte kit 200 for replenishment of the pouch-type secondary battery 1 of the present invention is shown to be formed on the folding surface 120 . As described above, the folding surface 120 refers to the folding surface of the pouch case 100 as the folding surface 120 and is also indicated in FIG. 1 . That is, since the replenishment electrolyte kit 200 is formed on the folding surface 120 , the replenishment electrolyte kit 200 can be formed in the pouch case 100 without the need to secure an additional space in the pouch case 100 . Replenishment electrolyte kit 200 in order to be formed on the folding surface 120, the storage unit 210 may be formed so as to extend long in the longitudinal direction of the folding surface (120). A kit 200-shaped groove may be formed on the folding surface 120 in order to facilitate placing the supplementary electrolyte kit 200 on the folding surface 120, or the kit 200 is formed so that the folding surface surrounds the folding surface. However, the shape is not limited thereto.

Referring to FIG. 2B , it is shown that the electrolyte kit 200 for replenishment of the pouch-type secondary battery 1 of the present invention is formed along the folding surface 120 and the sealing surface 130 adjacent to the folding surface 120 . The sealing surface 130 refers to the remaining surface that is sealed except for the folding surface 120 in the pouch case 100 as described above, and is also indicated in FIG. 1 . Unlike FIG. 2A , the storage unit 210 may be formed to extend from the folding surface 120 to the sealing surface 130 . The reason that the storage unit 210 is formed to be extended in this way is that the volume of the second space 212 can be secured, so that more gas in the main chamber 110 can move to the second space 212 . It may be more advantageous to prevent gas venting. In addition, since more replenishment electrolyte (s) can be stored in the first space 211, the number of times that the replenishment electrolyte (s) is supplied can be increased, so that the cycle of use of the secondary battery 1 can be further increased.

Referring to FIG. 3 , a side cross-sectional view of the secondary battery 1 of the present invention cut along the line A-A' of FIGS. 2A and 2B can be seen. In FIG. 3 , a cross-section of the storage unit 210 formed on the folding surface 120 of the present invention can be seen. That is, the storage unit 210 is disposed on one side of the pouch case 110 while being surrounded by the folding surface 120 .

In the pouch-type secondary battery 1 according to an embodiment of the present invention, the storage unit 210 may be formed in a tube shape.

In the pouch-type secondary battery 1 according to an embodiment of the present invention, the storage unit 210 may be made of any one of polypropylene, polyethylene, or a combination thereof.

The storage unit 210 of the present invention may be formed in the form of a tube. In addition, the storage unit 210 may be made of any one of polypropylene, polyethylene, or a combination thereof. Therefore, the storage unit 210 may be formed of a material having a certain rigidity and securing heat resistance. Accordingly, the storage unit 210 can withstand the heat generated during the manufacturing process or use of the secondary battery 1, and can be designed to withstand external shocks to protect the supplementary electrolyte (s).

In the pouch-type secondary battery 1 according to an embodiment of the present invention, the stopper 213 may be in close contact with the inner surface of the storage unit 210 and moveable by pressure.

In the pouch-type secondary battery 1 according to an embodiment of the present invention, the stopper 213 may be formed of a rubber material.

The stopper 213 of the present invention divides the first space 211 and the second space 212 . In addition, the stopper 213 is in close contact with the inner surface of the storage unit 210 so that the electrolyte solution (s) for replenishment of the first space 211 cannot be moved to the second space 212, and flows into the second space 212. It is formed so that it can be moved by the pressure of the gas.

The stopper 213 of the present invention may be formed of a rubber material, and therefore, due to the nature of the material of the stopper 213 , it is easy to adhere to the storage unit 210 , and since it is not completely coupled to the storage unit 210 , it is can be moved

4 is a flowchart illustrating a driving method of the valve 230 according to an embodiment of the present invention.

In the pouch-type secondary battery 1 according to an embodiment of the present invention, the valve 230 may be a solenoid valve.

In the pouch-type secondary battery according to an embodiment of the present invention, the valve may be opened at 3.5 kgf/cm ² or more and closed at 1.5 kgf/cm ² or less.

The valve 230 of the present invention may be a solenoid valve, and the solenoid valve is an electromagnetic valve. When electricity passes, the flange rises to open the valve, and when electricity is cut off, the valve is automatically closed by the weight of the flange. The valve 230 control can be implemented as an automated system connected to a battery management system (BMS), and a description thereof will be made in detail below.

Referring to FIG. 4 , the actuation mechanism of the valve 230 of the present invention can be seen. The valve 230 is opened when the pressure is increased due to the gas in the main chamber 110 and the specific pressure is 3.5 kgf/cm ² or more. By opening the valve 230 , the gas enters the second space 212 , and the electrolyte for replenishment (s) is supplied to the main chamber 110 . Thereafter, as the gas moves to the second space 212 , when a specific pressure is formed to be 1.5 kgf/cm ² or less, the valve 230 is closed again. Whenever the secondary battery 1 runs out of electrolyte while repeating this process, the supplementary electrolyte (s) can be supplied from the supplementary electrolyte kit 200 . The setting of the specific pressure value as above is in accordance with the design specifications of the pouch case 110 , and the internal pressure limit of the pouch case 100 of the secondary battery 1 is formed at a level of 3 to 5 kgf/cm ² . In order to reduce the possibility of venting or damage to the pouch case 100 due to an increase in internal pressure of the pouch case 100, the valve 230 may be opened when the specific pressure is 3.5 kgf/cm ² or more.

The pouch-type secondary battery 1 according to an embodiment of the present invention may further include a BMS (Battery Management System) sensing terminal connected to the valve 230 .

In the pouch-type secondary battery 1 according to an embodiment of the present invention, a compression pad connected to the BMS sensing terminal and disposed on the outer surface of the pouch case 100 to detect a change in volume of the pouch case 100 . may further include.

A BMS sensing terminal may be connected to the valve 230 of the present invention. Accordingly, the control of the valve 230 by the BMS may be performed as in the algorithm of FIG. 4 . The BMS sensing terminal detects a pressure change in the main chamber 110 due to gas generation. The BMS sensing terminal may be formed in a wired or wireless manner, and in the wireless case, it communicates with the BMS device wirelessly, and in the wired case, a tab (t) extending from the valve 230 to the outside of the pouch case 100 is formed Therefore, it may be connected to the BMS device, but the connection method is not limited thereto.

A method for the BMS sensing terminal to measure a specific pressure may be achieved by a compression pad. The compression pad is disposed on the outer surface of the pouch case 100 to detect a change in volume of the pouch case 100 . The compression pad is connected to the BMS sensing terminal, so information on the sensed change is transmitted to the BMS sensing terminal and the BMS device, and based on this information, the pressure in the main chamber 110 is specified to open and close the valve 230 decide whether

When constructing the pouch-type secondary battery module, the pouch-type secondary batteries 1 are stacked, and the compression pad may be attached between the pouch-type secondary batteries 1 , and accordingly, it is attached to the upper and lower surfaces of the outer side of the pouch case 110 . can be Accordingly, the compression pad is subjected to pressure due to a change in the volume of the pouch case 110 . The valve 230 may use a compression pad as a method of measuring the pressure, but is not limited thereto.

In the pouch-type secondary battery according to an embodiment of the present invention, the injection unit 220 is formed of a syringe capable of only moving the replenishment electrolyte solution (s) from the first space 211 to the main chamber 110 direction. can be

The injection unit 220 may be formed as a one-way syringe so that the electrolyte in the main chamber 110 does not flow back into the first space 211 . Accordingly, the injection unit 220 may be formed as a syringe, thereby enabling only the replenishment of the electrolyte solution (s) to move from the first space 211 to the main chamber 110 direction.

Although the present invention has been described in detail through specific examples, it is intended to describe the present invention in detail, and the present invention is not limited thereto, and by those of ordinary skill in the art within the technical spirit of the present invention It will be clear that the transformation or improvement is possible.

All simple modifications and variations of the present invention fall within the scope of the present invention, and the specific scope of protection of the present invention will be clarified by the appended claims.

1: pouch type secondary battery
s : replenishment electrolyte
a: electrode assembly
t : tab
100: pouch case
110: main chamber
120: folding side
130: sealing surface
200: replenishment electrolyte kit
210: storage unit
211: first space
212: second space
213: stopper
220: injection part
230: valve

Claims (13)

a pouch case including a main chamber accommodating the electrode assembly; and
Containing; replenishment electrolyte kit disposed on at least one side of the main chamber;
The replenishment electrolyte kit,
a storage unit including a first space in which the supplementary electrolyte is stored and a second space separated from the first space by a stopper;
an injection unit providing a passage through which the supplementary electrolyte moves to the main chamber; and
Containing, a pouch-type secondary battery comprising a; valve for controlling the movement of the gas of the main chamber to the second space by opening and closing at a specific pressure value. The method according to claim 1,
When the valve is opened, the gas enters the second space, and the pressure received by the replenishment electrolyte increases by the force of the gas pressing the stopper, so that the injection unit supplies the replenishment electrolyte to the main chamber, a pouch type secondary battery. 3. The method according to claim 2,
The replenishment electrolyte kit,
A pouch-type secondary battery formed on a folding surface on which the pouch case is folded. 3. The method according to claim 2,
The replenishment electrolyte kit,
A pouch-type secondary battery formed along a folding surface on which the pouch case is folded and a sealing surface adjacent to the folding surface. 5. The method of claim 3 or 4,
The storage unit is made in the form of a tube, pouch-type secondary battery. 6. The method of claim 5,
The storage unit is made of any one of polypropylene, polyethylene, or a combination thereof, a pouch-type secondary battery. 6. The method of claim 5,
The stopper is in close contact with the inner surface of the storage unit and is movable by pressure, a pouch-type secondary battery. 8. The method of claim 7,
The stopper is formed of a rubber material, a pouch-type secondary battery. 5. The method of claim 3 or 4,
The valve is
A pouch-type secondary battery comprising a solenoid valve. 10. The method of claim 9,
The valve is opened at 3.5 kgf/cm ² or more and is closed at 1.5 kgf/cm ² or less, a pouch-type secondary battery. 10. The method of claim 9,
A pouch-type secondary battery further comprising a BMS (Battery Management System) sensing terminal connected to the valve. 11. The method of claim 10,
A pouch-type secondary battery connected to the BMS sensing terminal and disposed on an outer surface of the pouch case to further include a compression pad configured to sense a change in volume of the pouch case. 5. The method of claim 3 or 4,
The injection unit is formed of a syringe capable of only moving the replenishment electrolyte from the first space to the main chamber direction, a pouch-type secondary battery.

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