KR100955233B1 - Multilayered electric double layer capacitor - Google Patents

Abstract

The present invention relates to a multilayer type electric double layer capacitor that can be used even at a high temperature. The unit cells of the capacitors are stacked and placed in a single case, so that the energy density and output density characteristics can be better than that of capacitors connected in series. In addition, the case of the electric double layer capacitor is made of SPCC cold-rolled steel sheet and PE coated on the inner surface thereof to withstand the high temperature of the outside and to minimize the heat transfer. In addition, the case is formed with a fitting groove is formed on a portion of the surface in contact with the elastic body, the elastic body is a laminated type to reduce the ESR of the laminated cell, characterized in that the same shape as the fitting groove is formed so that the fitting groove can be fitted. An electric double layer capacitor.

Stacked, Electrical Double Layer, Capacitors

Description

Multilayer Electric Double Layer Capacitors {MULTILAYERED ELECTRIC DOUBLE LAYER CAPACITOR}

The present invention relates to a multilayer type electric double layer capacitor that can be used even at high temperatures, and more particularly, to stack unit cells in a single case to have a density characteristic superior to connecting capacitors in series, and a case of an electric double layer capacitor. By using a material other than the commonly used aluminum material to withstand the external high temperature and to minimize the heat transfer, to form a fitting groove of a certain shape on the case and to be fitted to the fitting groove in the elastic body The present invention relates to a multilayer type electric double layer capacitor capable of reducing the ESR of a stacked cell by forming the same shape as that described above.

Electric double layer capacitor (ELDC) refers to an energy storage device having a much higher capacity than a capacitor or an electrolyte capacitor, and is also called a supercapacitor or ultracapacitor. An electric double layer capacitor is a power source that collects a lot of energy and emits high energy for tens of seconds or minutes, and is a useful component that can fill a performance characteristic area that a conventional capacitor and a secondary battery cannot accommodate. An electric double layer capacitor has intermediate characteristics of a capacitor having a dielectric and a secondary battery in energy density, output density, and cycle characteristics.

The characteristics of the electric double layer capacitors are summarized as follows: ① It does not cause overcharge / discharge, which simplifies the electric circuit and provides a factor to reduce the price. ② It is possible to grasp the residual capacity from the voltage. ③ It shows a wide endurance temperature characteristic. It is composed of environmentally friendly materials, and therefore has advantages that are not found in capacitors or secondary batteries.

When electric double layer capacitors are classified by their capacity, they can be classified into small-capacity products (1F), medium-capacity products (1-100F class), and large-capacity products (100-5000F class). The current demand for small-capacity products is intensifying competition due to the low price of primary batteries or secondary batteries such as lithium batteries, but the power market such as memory backup of real-time functions of high-end models or mobile phones such as GSM phones It is expanding. In addition, memory backup is mainly used, but as the performance becomes more advanced, the tendency to adopt the electric double layer capacitor for the purpose of supplementing the load of the battery is increasing.

Electric double layer capacitors can be classified into coin type, cylinder type and angular type according to their external size. As shown in FIG. 1, the coin-type electric double layer capacitor 10 has a pair of sheet-like activated carbon electrodes 12 disposed with the separator 11 therebetween, and infiltrate the electrolyte solution with these electrodes. It is sealed by the upper and lower metal cases 14 and 15 and the packing 13 in the made state. In general, the rated voltage of one cell of the coin-type electric double layer capacitor 10 represents 2.5V, but the contact voltage of the two cells represents a rated voltage of 5.5V.

Conventionally, in order to increase the voltage by using a coin type electric double layer capacitor, each capacitor was connected in series and used as a single module. If it is used as a module, there is a convenience in manufacturing, but there is a problem such as a disadvantage of the performance degradation of the module due to the increase in the weight of the case and a problem such as an imbalance between capacitors needs to be improved.

In addition, the outer case of the electric double layer capacitor is generally made of aluminum. However, when the case is made of aluminum, since it can only endure the external temperature of 60 ℃ ~ 70 ℃ usually there is a problem that can not withstand high temperature, there is a need to improve this.

The present invention has been created by the necessity as described above, by using a stacking technology of unit cells to configure a module to form a module by showing the energy density and output density characteristics superior to connecting the capacitors in series have.

In addition, through the stacking technology of unit cells, it is possible to reduce the connection resistance, which is a problem when the capacitors are connected in series, so the purpose of the present invention is to reduce the degradation of the output characteristics according to the reduction of ESR (Equivalent Series Resistance).

Another object of the present invention is to improve the prior art by making an electric double layer capacitor by changing the material and shape of the outer case to withstand high temperatures and to minimize heat transfer.

Technical problems to be achieved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

In order to solve the above problems, the laminated electrical double layer according to an aspect of the present invention is made of SPCC cold rolled steel sheet and its inner surface is a hollow case with a PE coating, and a gasket having an inner space and an opening end. ; An electrode unit including a positive electrode and a negative electrode disposed in the inner space; A separator disposed in the inner space separating the positive electrode and the negative electrode; A current collector formed on the electrode portion and disposed at the opening end; And a plurality of unit cells including an electrolyte stored in the inner space and absorbed in the electrode unit and connected to the plurality of unit cells in series, and an elastic body contacting the bottom surface of the stack cell and the stack cell disposed in the case. And a cathode lead wire connected to the current collector disposed on the bottom surface of the stacked cell and drawn out of the case, the cathode lead wire connected to the case and connected to the case, and drawn out of the case, the anode lead wire and the cathode lead wire. It is connected to support the terminal having a terminal plate disposed on the lower surface.

According to another aspect of the present invention, the electric double layer capacitor has a fitting groove formed on a portion of the case in contact with the elastic body, and the elastic body is formed in the same shape as the fitting groove so that the elastic body can be fitted into the fitting groove. It is characterized in that it is provided.

The outer casing of the electric double layer capacitor is made of SPCC cold rolled steel sheet and PE coated on the inside thereof, thereby providing an electric double layer capacitor that can withstand high temperatures.

In addition, by stacking the unit cells of the capacitor in a single case, it can exhibit better energy density and output density characteristics than connecting the capacitors in series. The stacking technology can reduce the connection resistance, which is a problem when the capacitors are connected in series, so there is no deterioration in output characteristics due to the reduction of ESR (Equivalent Series Resistance).

In addition, it is possible to further reduce the ESR by pressing the lamination cell by inserting an elastic body serving as a packing material in the case into the fitting groove of the case.

Hereinafter, an embodiment of a stacked type electric double layer capacitor 30 having a material and a shape of a case 31 and a shape of an elastic body 36 according to the present invention will be described with reference to the accompanying drawings.

Specific details of other embodiments are included in the detailed description and the accompanying drawings. Advantages and features of the present invention, and methods for achieving them will be apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, only the present embodiments to make the disclosure of the present invention complete, and common knowledge in the art to which the present invention pertains. It is provided to fully inform the person having the scope of the invention, which is defined only by the scope of the claims. Like reference numerals refer to like elements throughout. In the drawings, the thicknesses of layers, films, or regions are exaggerated for clarity.

3 is a diagram illustrating a stacked cell 20 in which three unit cells are stacked in a vertical direction. In the embodiment of the present invention, three unit cells are used, but in practice, three or more unit cells may be used.

Referring to FIG. 2, the stacked cell 20 disposed inside the case 31 of the stacked type electric double layer capacitor 30 includes a gasket 26 having an inner space and an open end portion; An electrode unit 23 including a positive electrode 21 and a negative electrode 22 disposed in the inner space; A separator 24 disposed in the inner space separating the positive electrode 21 and the negative electrode 22; A current collector 25 formed on the electrode portion 23 and disposed at the opening end; And three unit cells including an electrolyte stored in the inner space and absorbed by the electrode unit 23.

The gasket 26 is a frame for encapsulating the electrolyte and maintaining the unit cell structure, and has an inner space and an open end. An open end is an open cross section that is not blocked by another. The gasket 26 may use a sheet-like rubber material, for example butyl rubber, which has mechanical strength and is electrochemically stable.

The electrode portion 23 composed of the positive electrode 21 and the negative electrode 22 is disposed in the inner space of the gasket 26. The positive electrode 21 and the negative electrode 22 of the electrode part 23 use activated carbon, and the electrode material, the carbon conductive material, and the polymer binder are made of a slurry and applied to the current collector 25 to manufacture the electrode. can do.

The separator 24 separating the positive electrode 21 and the negative electrode 22 of the electrode part 23 is a thin film material having a hollow hole through which ions pass to prevent a short circuit caused by contact between the electrodes.

 The electrolyte is stored in the interior space of the gasket 26 and the electrolyte may use an ionic electrolyte. For use at a high temperature of about 85 ° C., which is one of the main objects of the present invention, it is preferable to use the material of the electrolyte as the ionic electrolyte.

The current collector 25 may generally be made of a rubber sheet having a high conductivity of about 5 S · cm ⁻¹ . Preferably, it may be made of Ni and the current collector 25 located at the bottom of the stacked cell 20 may be connected to the anode lead wire 34 to be described later.

3 is a cross-sectional view of the stacked type electric double layer capacitor 30.

The multilayer type electric double layer capacitor 30 is made of a SPCC cold rolled steel sheet, and an inner surface thereof is a hollow case 31 having a PE coating; A stacked cell 20 disposed inside the case 31; An elastic body 36 for pressing the laminated cell 20 in contact with a lower surface of the stacked cell 20; A positive electrode lead wire 34 connected to the current collector 25 located on the bottom surface of the stacked cell 20 and drawn out of the case 31; A cathode lead wire 35 in contact with the elastic body 36 and connected to the case 31 and drawn out of the case 31; The terminal plate 37 is connected to support the positive lead wire 34 and the negative lead wire 35 and is disposed on the lower surface of the elastic body 36.

The case 31 is made of SPCC cold rolled steel sheet and its inner surface is PE coated. SPCC is made of steel plate, and the Japanese JIS standard consists of C (0.12% or less), Mn (0.50% or less), P (0.040% or less), and S (0.045% or less). . When the case 31 is composed of a SPCC cold rolled steel sheet can be used even at a high temperature of about 85 ℃ and can minimize the heat transfer. However, when the degree of high temperature exposure time is long, the effect of the coating of the inside of the case 31 composed of SPCC cold rolled steel plate with PE (Poly Ethylene) may be more significant. PE may have various forms such as HDPE, LDPE, LLDPE, VLDPE, blend polymer, copolymer polymer, and the like.

The stacked cell 20 is disposed on the upper surface 32 inside the case. That is, the current collector 25 on the top surface of the stacked cell 20 including a plurality of unit cells may be disposed in contact with the top surface that is not open in the case 31.

The anode lead wire 34 is connected to the current collector 25 located on the bottom surface of the stacked cell 20 and drawn out of the case 31. The anode lead wire 34 may be drawn out to the outside through the elastic body 36. The positive lead wire 34 may be supported by the terminal plate 37 and drawn out to the outside through the terminal plate 37, and may be drawn out to the outside without being connected to the case 31 by the insulator 39. The insulator 39 may be formed to surround the anode lead wire 34 at a portion where the anode lead wire 34 passes outside of the case 31.

In general, the elastic body 36 composed of butyl rubber is disposed on the lower surface of the stacked cell 20 to pressurize the stacked cell 20 so that the electrolyte of the stacked cell 20 does not flow. As the electrolyte does not flow, there is no problem in realizing the voltage originally intended to be obtained, generally a voltage of about 2.1 V per unit cell.

To this end, the case 31 has a fitting groove 38 formed on a part of the surface in contact with the elastic body 36, and has the same shape as the fitting groove 38 so that the elastic body 36 can be engaged with the fitting groove 38. Is formed. The same shape as the fitting groove 38 formed in the elastic body 36 than the inner diameter of the fitting groove 38 formed in the case 31 has a smaller outer diameter so that the fitting groove 38 can fit snugly into the fitting groove 38. The fitting groove 38 serves as a kind of support for maintaining the pressing force when the elastic body 36 presses the stacked cells 20. The fitting groove 38 thus serves to enable pressurization easily and firmly without the aid of any other support. This serves to reduce the contact resistance that can be increased as the unit cells are stacked.

The fitting groove 38 may have various shapes in which the elastic body 36 may be fitted to the case 31. For example, it may have a shape that comes out of the case 31 in a convex ellipse or a circle. Preferably, the case 31 may have a shape that is concave in an elliptical or circular shape in the inner direction of the case 31.

The negative lead 35 may be formed from a surface in contact with the elastic body 36 and may be led out of the case 31 past the terminal plate 37. The negative lead 35 drawn from the elastic body 36 may have a T-shape to securely fix the terminal plate 37. The negative lead 35 is connected to the case 31. The case 31 in contact with the current collector 25 located on the upper surface of the stacked cell 20 has a negative electrode, and the negative electrode lead wire 35 is connected with the case 31 to have a negative electrode.

The terminal plate 37 is formed on the lower surface of the elastic body 36 and serves to support the positive lead wire 34 and the negative lead wire 35. The terminal plate 37 may be composed of a double layer of SPCC cold rolled steel sheet and bakelite material.

Specific examples and comparative examples are summarized in Table 1.

Example Comparative example Case (31) SPCC + PE Coating aluminum Fitting groove (38) ○ ㅧ Electrode part 23 Activated carbon Activated carbon Electrolyte Ionic electrolyte Ionic electrolyte Current collector (25) Ni Ni Gasket (26) Butyl rubber Butyl rubber

EXAMPLE

Case 31 is made of SPCC cold-rolled steel sheet material and the inner surface of the PE coating. In the case 31 and the elastic body 36 made of a butyl rubber material, a fitting groove 38 having a shape recessed into the inside of the case 31 was made. The electrode portion 23 is composed of activated carbon, the electrolyte is an ionic electrolyte, the current collector 25 is Ni, and the gasket 26 is made of butyl rubber.

One unit cell represents approximately 2.7V and may have a voltage of approximately 8.1V when three unit cells are stacked in series. In practice, the maximum voltage is 8.3V, but the rated voltage is lowered so that the voltage is approximately 6.3V, so that the temperature can be increased as the voltage decreases. The size of the electric double layer capacitor was 18 mm in diameter and 20 mm in height.

The initial characteristic value was 1.0F and the ESR value was measured as 8 ohm at 1kHz. Experimental conditions were tested at a temperature of 85 ℃ with a voltage of 6.3V for 1,000 hours. The value of the result of the experiment under the above experimental condition, that is, the characteristic value after the high temperature load was measured as capacity of 0.85F, ESR value of 11 ~ 13 ohm at 1kHz.

[Comparative Example]

Three coin-shaped cells with aluminum cases were connected in series. The case was made in the form of a round empty case with no fitting grooves. The elastomer was also inserted into the case in the form of a circle. Other conditions were tested under the same conditions.

The initial characteristic value was 1.0F and the ESR value was measured as 30 ohm at 1kHz. Experimental conditions were tested at a temperature of 70 ℃ with a voltage of 5.5V for 1,000 hours. The value of the result of the experiment under the above experimental condition, that is, the characteristic value after the high temperature load was measured as capacity of 0.7F, ESR value of 60 ohm at 1kHz.

Comparing the examples with the comparative example it can be seen that the case of the embodiment of the present invention is not only small capacity reduction rate but also small resistance increase value even after the high temperature load at a high temperature compared with the conventional comparative example.

As described above, according to the electric double layer capacitor according to the embodiment of the present invention, the outer case 31 is made of SPCC cold-rolled steel sheet and PE coated on the inside so that it can withstand high temperatures outside and minimize the heat transfer effect. Do it.

In addition, when the elastic cell 36, which acts as a packing material, fits into the fitting groove 38 of the case 31 inside the case 31 to press the stacked cell 20, the unit cell is connected in series. This reduces the connection resistance in question, ie ESR.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to the above embodiments but may be manufactured in various forms, and having ordinary skill in the art to which the present invention pertains. It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without changing the technical spirit or essential features of the present invention. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

      1 is a perspective view of a coin type electric double layer capacitor generally used in the related art.

2 is a cross-sectional view of a stacked cell disposed inside a stacked type electric double layer capacitor according to the present invention.

3 is a cross-sectional view of a stacked type electric double layer capacitor according to the present invention.

4 is a perspective view of a stacked type electric double layer capacitor according to the present invention.

* Explanation of symbols for main parts of the drawings

10: coin type electric double layer capacitor 11: separator

12: activated carbon electrode 13: packing

14: metal case (+) 15: metal case (-)

20: stacked cell 21: positive electrode

22: negative electrode 23: electrode portion

24: separation plate 25: current collector

26: gasket

30: multilayer electric double layer capacitor 31: case

32: upper surface inside the case 33: coating material

34: positive lead wire 35: negative lead wire

       36: elastic body 37: terminal plate

38: fitting groove 39: insulator

Claims (5)

A gasket having an inner end and an inner space for containing the ionic electrolyte; An electrode unit including a positive electrode and a negative electrode disposed in the inner space; A separator disposed in the inner space separating the positive electrode and the negative electrode; A current collector formed on the electrode portion and disposed at the opening end; And a stacked cell in which a plurality of unit cells including an electrolyte stored in the inner space and absorbed in the electrode unit are connected in series. The lamination cell is disposed inside, made of SPCC cold rolled steel sheet to block heat transfer from the outside to the lamination cell, the inner surface of which is coated with polyethylene (PE), and a hollow part formed with fitting grooves on some surfaces Case of form; An elastic body that is engaged with the fitting groove of the case and contacts the lower surface of the stack cell to press the stack cell so that the electrolyte does not flow; A positive electrode lead wire connected to the current collector disposed on the bottom surface of the stacked cell and drawn out of the case; A negative electrode lead wire which is in contact with the elastic body and connected to the case and is drawn out of the case; And And a terminal plate connected to support the positive electrode lead and the negative electrode lead and disposed on the lower surface of the elastic body. delete The method of claim 1, The fitting groove is a multilayer type electric double layer capacitor, characterized in that the recessed shape into the inside of the case. The method of claim 1, The fitting groove is a multilayer type electric double layer capacitor, characterized in that the convex shape coming out of the case. delete

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