KR102086589B1 - Electrode materials, electrochemical device comprising the same and method for manufacturing the same - Google Patents

Abstract

The present invention relates to an electrode material used as an electrode active material such as an electric double layer capacitor (EDLC), an electrochemical device including the same, and a method of manufacturing the same. The present invention provides an activated carbon having a specific surface area of 1500 m 2 / g or more, an average particle size of 2 to 20 µm, and a tap density of 0.2 to 0.8 g / cm 3; And a carbon material having a specific surface area of 1 to 20 m 2 / g, an average particle size of 3 to 20 μm, and a tap density of 0.5 to 1.5 g / cm 3, and a method of manufacturing the same. The present invention also provides an electrochemical device comprising the electrode material as an electrode active material. According to the present invention, it has excellent electrical properties and long-term reliability. In addition, coke, a byproduct generated in the petroleum refining process, may be usefully used as an electrode resource such as an electric double layer capacitor (EDLC).

Description

ELECTRODE MATERIALS, ELECTROCHEMICAL DEVICE COMPRISING THE SAME AND METHOD FOR MANUFACTURING THE SAME

The present invention relates to an electrode material, an electrochemical device including the same, and a method of manufacturing the same, and more particularly, an electrode material which can be applied as an electrode active material such as an electric double layer capacitor to have excellent electrical characteristics and long-term reliability, and the like. It relates to an electrochemical device comprising and a method of manufacturing the same.

Electrochemical devices have higher energy density and can be repeatedly charged / discharged than general batteries, and thus are highly demanded in various fields. For example, hybrid capacitors such as Electric Double Layer Capacitors (EDLC), Lithium ion secondary batteries, and Lithium ion Capacitors that utilize their advantages. And so on. Among these, the electric double layer capacitor (EDLC) has a large capacity per unit volume and can be rapidly charged / discharged, and thus is useful as a memory backup small power supply such as a PC and a large power supply such as an electric vehicle or a hybrid vehicle.

Most electrochemical devices use activated carbon as an electrode active material. Activated carbon has a high specific surface area and is useful as an electrode material. For example, the capacity of the electric double layer capacitor EDLC is determined according to the amount of charge accumulated in the electric double layer, and the amount of charge increases as the specific surface area of the electrode increases. Accordingly, the activated carbon has a high specific surface area due to the porous structure, so that the electrode can be increased in capacity and energy density can be improved. Electric double layer capacitors (EDLC) and the like mostly use activated carbon having a specific surface area of 1500 m 2 / g or more.

Generally, activated carbon is produced by carbonizing a carbon raw material (carbon precursor) at high temperature and then activating it with a porous structure. At this time, in the activation step, an alkali activator such as potassium hydroxide (KOH) is mainly mixed with the carbon raw material, and then heated in an inert gas atmosphere to infiltrate and react the alkali metal between the carbon crystal layers to form fine pores. . Activated carbon obtained by such alkali activation has a large specific surface area and uniform particle size, which is useful as an electrode material such as an electric double layer capacitor (EDLC). For example, Japanese Patent Laid-Open Publication No. 2009-260177, Japanese Patent Laid-Open Publication No. 2010-245482, and the like, related technologies are presented.

Activated carbon is a carbon raw material (carbon precursor) and a product that activates a phenol resin and a product that activates a coconut shell (palm shell), apricot seed, rice husk, etc., is widely used as an electrode of an electric double layer capacitor (EDLC). For example, Korean Patent No. 10-0348499 discloses a method of manufacturing activated carbon using chaff, and Korean Patent No. 10-0342069 forms a plate by mixing a binder or the like with chaff activated carbon. The manufacturing method of the electrode manufactured by this is shown. In addition, Korean Patent No. 10-1105715 discloses a method of manufacturing an electrode using a phenol resin-based activated carbon and a coconut shell-based activated carbon.

However, activated carbon produced using coconut shell has high resistance to impurities and high content of impurities. In addition, the activated carbon prepared by using a phenol resin has a relatively good resistance property compared to a coconut shell, but has a disadvantage of being expensive. Accordingly, in manufacturing the electrode, an electrically conductive conductive material is added to the activated carbon. For example, in the case of an electric double layer capacitor (EDLC), a composition for an electrode is obtained by mixing particulate activated carbon, a conductive material electrically connecting the activated carbon particles, and a binder for bonding them. This is coated on a metal current collector and rolled to produce an electrode. In this case, carbon black is mainly used as the conductive material. By the addition of such a conductive material, the electrical conductivity may be improved, thereby improving resistance characteristics.

However, the composition for electrodes according to the prior art has a problem that the content of the conductive material is increased for the resistance characteristics, in which case the content of the activated carbon is relatively small, the capacitance is lowered. In addition, long-term reliability is low. That is, as the use time of the device increases, there is a problem in that long-term reliability, such as a decrease in capacity and an increase in resistance, is lowered.

On the other hand, coke, which is a by-product of oil refinery generated in the process of refining of petroleum, is generally not used to produce an electrode material such as an electric double layer capacitor (EDLC). The coke cannot increase the specific surface area which directly affects the capacity of the electric double layer capacitor (EDLC) and the like, because the content of impurities is high and electrical characteristics are inferior.

Japanese Patent Laid-Open No. 2009-260177 Japanese Patent Laid-Open No. 2010-245482 Republic of Korea Patent No. 10-0348499 Republic of Korea Patent No. 10-0342069 Republic of Korea Patent No. 10-1105715

Accordingly, an object of the present invention is to provide an electrode material which can be used as an electrode active material such as an electric double layer capacitor (EDLC) and can have excellent electrical properties and long-term reliability, and an electrochemical device including the same.

In addition, the present invention is to provide a method for producing an electrode material that can be used as coke (cokes) generated during the refining process of petroleum as a raw material, and can be treated under specific process conditions to have excellent electrical properties and long-term reliability. There is a purpose.

The present invention to achieve the above object,

Activated carbon having a specific surface area of at least 1500 m 2 / g, an average particle size of 2 to 20 µm, and a tap density of 0.2 to 0.8 g / cm 3; And

Provided is an electrode material comprising a carbon material having a specific surface area of 1 to 20 m 2 / g, an average particle size of 3 to 20 μm, and a tap density of 0.5 to 1.5 g / m 3.

In this case, the electrode material according to the present invention may include 50 to 95% by weight of activated carbon and 5 to 50% by weight of carbon material.

The present invention also provides an electrochemical device comprising the electrode material of the present invention.

In addition, the present invention,

Preparing activated carbon having a specific surface area of 1500 m 2 / g or more, an average particle size of 2 to 20 μm, and a tap density of 0.2 to 0.8 g / cm 3;

Preparing a carbon material having a specific surface area of 1 to 20 m 2 / g, an average particle size of 3 to 20 μm, and a tap density of 0.5 to 1.5 g / cm 3; And

It provides a method for producing an electrode material comprising the step of mixing the activated carbon and the carbon material prepared above.

In addition, the present invention,

Preparing activated carbon;

Preparing a carbon material; And

Mixing the prepared carbon with the carbon material;

Preparing the activated carbon,

A carbonization process of carbonizing coke at a temperature of 300 ° C to 800 ° C;

A grinding step of grinding the carbonized coke;

An activation process of mixing the pulverized coke with an activator and then heating the activated coke at 500 ° C to 1000 ° C;

A cleaning / drying process of cleaning and drying the activated coke activated carbon; And

It provides a method for producing an electrode material comprising a heat treatment step of heat-treating the washed and dried coke activated carbon at a temperature of 500 ℃ ~ 1200 ℃.

In addition, the present invention,

Preparing activated carbon;

Preparing a carbon material; And

Mixing the prepared carbon with the carbon material;

Preparing the carbon material,

A first heat treatment step of firstly heat treating the raw material at a temperature of 500 ° C. to 900 ° C .;

A pulverizing process of pulverizing the first heat treated coke; And

It provides a method for producing an electrode material comprising a second heat treatment step of secondary heat treatment of the pulverized coke at a temperature of 800 ℃ to 1300 ℃.

According to the present invention, it has excellent electrical properties and long-term reliability. In addition, coke, a byproduct generated in the petroleum refining process, may be usefully used as an electrode resource such as an electric double layer capacitor (EDLC).

1 is a graph showing powder resistance of particulate electrode materials according to Examples and Comparative Examples of the present invention.
Figure 2 is a graph showing the capacity retention rate (%) with time (h) at 2.7V of the EDLC cell according to the Examples and Comparative Examples of the present invention.
3 is a graph showing a resistance increase rate (%) with time (h) at 2.7V of the EDLC cell according to the embodiment and the comparative example of the present invention.

Hereinafter, the present invention will be described in detail.

The electrode material according to the invention is a mixture in powder form, which comprises activated carbon and a carbon material. The activated carbon and the carbon material are each selected from those having the following physical properties.

The activated carbon is selected from those having a specific surface area of 1500 m 2 / g or more, an average particle size of 2 to 20 µm (micrometer), and a tap density of 0.2 to 0.8 g / cm 3. The carbon material is selected from those having a specific surface area of 1 to 20 m 2 / g, an average particle size of 3 to 20 µm, and a tap density of 0.5 to 1.5 g / cm 3.

The activated carbon is a porous material carbonized and activated from a carbon raw material (activated carbon precursor), and the activated carbon is not limited as long as it has the above physical properties, and the raw material is not particularly limited.

Activated carbon is more advantageous in terms of energy storage characteristics and output characteristics as the specific surface area is larger. For this purpose, activated carbon is selected from those having a specific surface area of at least 1500 m 2 / g. Activated carbon preferably has a specific surface area of 1800 m 2 / g or more, and more preferably 1900 m 2 / g or more. However, if the specific surface area of activated carbon is too large, the electrode density may be lowered. For example, when applied as an electrode such as an electric double layer capacitor (hereinafter, referred to as 'EDLC'), when the specific surface area of activated carbon is too large, the electrode density may be lowered and thus the capacitance per unit volume (F / cc) may drop. . In view of this point, the activated carbon preferably has a specific surface area of 1800 to 2500 m 3 / g, and more preferably 1800 to 2200 m 2 / g.

In addition, the average particle size of the activated carbon may affect energy storage and resistance characteristics. If the average particle size of the activated carbon is less than 2 μm, for example, energy storage characteristics may be lowered. And if the average particle size of the activated carbon exceeds 20㎛, for example, the resistance characteristics may be inferior. In view of this, the activated carbon is selected from those having an average particle size distribution of 2 to 20 µm. Activated carbon preferably has an average particle size distribution of, for example, 5 to 15 µm.

In addition, the tap density of the activated carbon may affect the capacitance (F / cc) and the resistance characteristics. If the tap density of the activated carbon is less than 0.2 g / cm 3, for example, the resistance characteristics and the like may deteriorate. And when the tap density of activated carbon exceeds 0.8 g / cm <3>, electrostatic capacity (F / cc) etc. may become low, for example. In view of this, activated carbon is selected from those having a tap density of 0.2 to 0.8 g / cm 3. Activated carbon preferably has a tap density of 0.25 to 0.45 g / cm 3.

The carbon material is carbonized carbon raw material (carbon precursor), which is not limited as long as it has the physical properties as described above, the raw material is also not particularly limited.

The carbon material having the above physical properties improves electrical characteristics and long-term reliability by mixing with activated carbon. For example, the specific surface area of the carbon material may affect the capacitance (F / cc) and the resistance characteristics. When the specific surface area of the carbon material is less than 1 m 2 / g, for example, the capacitance (F / cc) can be lowered. And when the specific surface area of a carbon material exceeds 20 m <2> / g, the improvement effect, such as a resistance characteristic, for example may be insignificant. In view of this point, the carbon material is selected from those having a specific surface area of 1 to 20 m 2 / g, and preferably selected from those having a specific surface area of 5 to 12 m 2 / g.

In addition, when the average particle size of the carbon material is less than 3㎛, it may adversely affect the capacitance (F / cc), for example. When the average particle size of the carbon material exceeds 20 μm, for example, an improvement effect such as resistance characteristics may be insignificant. In consideration of this, the carbon material is used having an average particle size of 1 ~ 20㎛, preferably preferably having an average particle size of 5 ~ 15㎛.

In addition, when the tap density of the carbon material is less than 0.5 g / cm 3, for example, improvement effects such as resistance characteristics may be insignificant. And when the tap density of the carbon material exceeds 1.5g / ㎥, for example, it can be separated from the activated carbon when preparing a slurry for forming the electrode can resist workability. In consideration of such resistance characteristics and mixing with activated carbon, the carbon material is selected from those having a tap density of 0.5 to 1.5 g / cm 3, and preferably having a tap density of 0.8 to 1.2 g / cm 3.

In the present invention, the measuring method of each physical property is not particularly limited. Specific surface area and average particle size are based on measurements widely used in the art. For example, the specific surface area may be in accordance with the Brunauer Emanett and Teller method (BET method) using the nitrogen (N ₂ ) adsorption amount, and the average particle size may be in accordance with the laser diffraction method. The tap density is based on the tap density measurement method applied in general powder-related fields, for example, by putting powder (activated carbon or carbon material) into a volume measuring container (e.g., a measuring cylinder) and applying vibration According to the method of measuring the weight of the injected powder (activated carbon or carbon material) divided by volume.

In addition, the electrode material according to the present invention may include, for example, 50 to 95% by weight of activated carbon and 5 to 50% by weight of carbon based on the total weight of the electrode material (mixture of activated carbon and carbon material). At this time, when the content of the carbon material is less than 5% by weight, the effect of improving the electrical properties such as resistance characteristics and long-term reliability may be insignificant. In addition, when the content of the carbon material exceeds 50% by weight, the content of activated carbon is relatively low, and thus the capacitance per unit volume (F / cc), energy storage characteristics, and output characteristics may be lowered. In view of this point, the electrode material according to the present invention preferably contains 55 to 90% by weight of activated carbon and 10 to 45% by weight of carbon material.

According to the present invention, the electrode activity is improved by the mixing of the two powder materials, that is, by the mixture of activated carbon and carbon material having specific properties as described above, and excellent electrical properties are realized. In particular, a high capacitance (F / cc) per unit volume is realized and has a low resistance. In addition, long-term reliability of electrochemical devices (EDLC, etc.) can be achieved. For example, even when the device is continuously driven for a long time, the capacitance (F / cc) and the resistance characteristics do not change significantly.

The electrode material (mixture of activated carbon and carbon material) according to the present invention is usefully used as an electrode active material such as an electrochemical device. For example, existing activated carbon constituting an electrode such as EDLC can be replaced.

On the other hand, the electrochemical device according to the present invention includes the electrode material of the present invention as described above as an electrode active material. In the present invention, the electrochemical device is not particularly limited as long as it is a device capable of converting chemical energy into electrical energy, for example, EDLC (electric double layer capacitor), pseudo capacitor (Pseudo Capacitor), lithium ion battery, lithium polymer battery , And hybrid capacitors incorporating these, and the like.

Hereinafter, the EDLC will be described as an example of the electrochemical device of the present invention.

In accordance with an exemplary form of the invention, the electrochemical device can be selected from EDLCs comprising electrodes (anodes and cathodes) and separators interposed between the electrodes, each of which is in turn a plurality of components. Can be stacked. In addition, the EDLC can be selected from cylindrical (winding), square (box), coin, and the like, and the shape thereof is not limited.

At this time, the electrode (anode and cathode) comprises at least one electrode composition layer, the electrode composition layer comprises the electrode material (mixture of activated carbon and carbon material) according to the present invention as an electrode active material. In addition, the electrode may further include a current collector and / or a conductive adhesive layer. For example, the electrode may have a laminated structure including a current collector on a thin film and an electrode composition layer formed on at least one surface of the current collector. In addition, the electrode may be further formed a separate conductive adhesive layer between the current collector and the electrode composition layer. The current collector can be selected from a metal foil, for example from aluminum (Al), copper (Cu), titanium (Ti), nickel (Ni), stainless steel (SUS) or alloys thereof. It may be composed of a selected metal thin film.

In addition, the electrode composition layer may be formed by rolling an electrode composition including an electrode material (electrode active material), a binder, and a conductive material of the present invention onto a sheet or by rolling on a current collector.

The binder may be adhesive and may be selected, for example, from those commonly used in the art. In addition, the binder may comprise a conductive polymer. The binder is, for example, polytetrafluoroethylene (PTFE), carboxymethyl cellulose (CMC), polyvinylpyrrolidone (PVP), styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVDF), polyethylene ( One or more selected from PE), polypropylene (PP), polyvinyl alcohol (PVA), and the like may be used, but is not limited thereto.

The conductive material may have electrical conductivity, and may also be selected, for example, from those commonly used in the art. The conductive material may be, for example, carbon black, acetylene black, graphite, graphene, carbon nanotubes (CNT), carbon nanofibers (CNF), titanium oxide and ruthenium oxide. One or more selected from powders such as these may be used.

In addition, the electrode composition may further include a solvent as the case may be. The solvent may be included as a diluent for coatability in preparing the electrode, for example when preparing the electrode by coating on the current collector. Such a solvent may be selected from water, an organic solvent, and the like, which may be volatilized by heat or may be naturally volatilized.

The electrode composition may include 70 to 92% by weight of the electrode material (mixture of activated carbon and carbon material), 5 to 15% by weight of the binder, and 2 to 20% by weight of the conductive material, based on the total weight of the composition. In this case, as described above, the electrode material may be mixed with 50 to 95% by weight of activated carbon and 5 to 50% by weight of carbon material, preferably 55 to 90% by weight of activated carbon and 10 to 45% by weight of carbon based on the total electrode material. Can be. And the solvent is mixed as needed, for example, based on 100 parts by weight of the electrode material may be mixed in 5 to 500 parts by weight.

On the other hand, the electrode material according to the present invention can be produced by various methods. Specifically, the activated carbon and the carbon material is not particularly limited as long as it can have the above physical properties. The activated carbon and the carbon material may be manufactured as follows using cokes generated in the refining process of petroleum according to an exemplary embodiment of the present invention.

Hereinafter, the manufacturing method of the electrode material concerning this invention is demonstrated.

The method for producing an electrode material according to the present invention includes the steps of preparing activated carbon, preparing a carbon material, and mixing the manufactured activated carbon with the carbon material. In this case, the step of preparing the activated carbon includes a process of obtaining activated carbon having a specific surface area of 1500 m 2 / g or more, an average particle size of 2 to 20 μm, and a tap density of 0.2 to 0.8 g / cm 3. In addition, the step of preparing the carbon material includes a process for producing a carbon material having a specific surface area of 1 to 20 m 2 / g, an average particle size of 3 to 20 μm, and a tap density of 0.5 to 1.5 g / cm 3. do.

The specific embodiment of each step is described as follows. According to the present invention, the production of activated carbon and carbon material which can be usefully used as an electrode active material using coke generated in the process of refining petroleum according to the present invention is implemented. In addition, the produced activated carbon and the carbon material have the properties as described above.

1. Preparation of Activated Carbon

The production of activated carbon may include (1) a carbonization process for carbonizing coke (first firing), (2) a pulverization process for pulverizing the carbonized coke, and (3) an activation process for activating the pulverized coke (second). Primary firing), (4) a cleaning / drying step of washing and drying the activated coke activated carbon, and (5) a heat treatment step (third firing) of heat treating the washed and dried coke activated carbon. The description of each process is as follows.

(1) carbonization process

First, the coke is carbonized. At this time, the coke used as a starting material (activated carbon precursor) is not limited, and may be selected from, for example, green cokes, which are by-products generated in the refining process of petroleum.

The coke is taken, for example, in the form of particles, lumps or sludge and carbonized (primary firing) at a temperature of 300 ° C to 800 ° C. Carbonization time is not limited. The carbonization time may vary depending on the carbonization temperature, which may be, for example, 30 minutes to 5 hours, more specifically 1 to 3 hours. And in carbonization, a heating furnace (carbonization furnace) maintains an inert atmosphere. In the present invention, the inert atmosphere may be capable of preventing oxidation, which may be selected from, for example, a gas atmosphere such as nitrogen (N ₂ ), argon (Ar) and / or helium (He). The carbonization process removes impurities such as volatiles present in the raw material while carbonizing the coke.

(2) grinding process

The carbonized coke is pulverized. The carbonized coke is ground to a size of, for example, 50 μm or less. For example, it may be ground to a size of 1 to 20㎛, more specifically 5 to 15㎛ as a uniform size. The grinding method is not particularly limited and may be, for example, a method such as a jet mill, a ball mill, a rotary mill, a vibration mill, or the like.

(3) activation process

The ground coke powder is activated to be porous. Activation is performed by mixing the pulverized coke powder with an activator and then heating (secondary firing) to 500 ° C ~ 1000 ° C. The activation time, that is, the time for heating after mixing the coke powder and the activator is not limited. The activation time may vary depending on the activation temperature, which may be, for example, 10 minutes to 4 hours. The activation time may be, for example, 30 minutes to 2 hours in detail. By this activation process, the coke powder is reformed into porous with a large number of pores.

The activator is not limited. The activator may be capable of increasing the specific surface area by modifying the coke to porous. The activator may be selected from alkali metal compounds and the like, and specific examples thereof may include one or more selected from potassium hydroxide (KOH), sodium hydroxide (NaOH), and the like.

Further, in the above activation process, the mixing ratio of the pulverized coke powder and the activator is not particularly limited, but for example, a weight ratio of 1: 0.1 to 10 (that is, pulverized coke powder: activator = 1: 0.1 to 10) Weight ratio) to activate the mixture. For example, the pulverized coke powder and the activator may be activated by mixing in a weight ratio of 1: 2 to 4.

(4) cleaning / drying process

The activated coke activated carbon is washed and dried.

The cleaning process is for removing impurities present in the coke activated carbon, which may be selected from, for example, one selected from alkali cleaning and acid cleaning, or a combination thereof. In the washing step, when an alkali metal compound (KOH, etc.) is used as the activator in the activation step, at least an acid wash (impregnated in an acid washing solution) is performed to remove the alkali metal compound (KOH, etc.) together with the removal of impurities present in the raw material. It may include. Under the present circumstances, acid aqueous solution, such as hydrochloric acid and a sulfuric acid, can be used as an acid washing liquid, for example. Through such acid washing, iron components contained in the coke raw material may also be removed.

In addition, the washing process may further include washing with water (distilled water or the like). At this time, the washing step may be repeated one or more times, for example, 1 to 5 times the acid washing and washing with water. And the coke activated carbon may have a pH range of 5.5 to 8.5 after washing.

After the cleaning as described above to remove the moisture present in the coke activated carbon through drying. Drying is not specifically limited, For example, it can advance through hot air drying of 60 degreeC or more, or natural drying.

(5) heat treatment process

Next, the washed / dried coke activated carbon is heat treated (third firing).

At this time, in the present invention, the heat treatment process (third firing) acts as an important factor such as physical properties and electrical properties of the coke activated carbon. According to the present invention, in the production of activated carbon, the starting material is coke, but the carbonization (primary firing) and activation (secondary firing) are performed as described above, and then the heat treatment (third firing) is further performed. It progresses and has the outstanding resistance characteristic (low resistance). In addition, the coke activated carbon has a characteristic that varies depending on the temperature conditions of the heat treatment, and has characteristics such as excellent resistance characteristics and excellent long-term reliability characteristics, that is, low capacity reduction rate in a specific temperature range.

Specifically, the activated coke activated carbon is cleaned / dried, and then heat-treated, but when heat-treated at a temperature of 500 ℃ ~ 1200 ℃, the surface functional groups and the like present in the coke activated carbon is effectively physically modified to remove the high quality Has characteristics. At this time, when the heat processing temperature is less than 500 degreeC, it is hard to have the outstanding resistance characteristic etc., for example. When the heat treatment temperature exceeds 1200 ° C, it is difficult to maintain the specific surface area to the maximum, and even in this case, it is difficult to have excellent resistance characteristics. Therefore, when the heat treatment temperature is 500 ° C to 1200 ° C, it maintains a high specific surface area, has high capacitance, and at the same time has excellent resistance characteristics. In consideration of this point, the heat treatment temperature is preferably 600 ° C to 1000 ° C, more preferably 700 ° C to 900 ° C.

The heat treatment is performed in an inert atmosphere such as nitrogen (N ₂ ), argon (Ar), helium (He) gas, or the like. The heat treatment time is not particularly limited. The heat treatment time may vary depending on the heat treatment temperature, but may be, for example, 10 minutes to 5 hours. For example, heat treatment may be performed for 30 minutes to 3 hours.

In addition, the manufacturing step of the activated carbon may further include a classification process according to an exemplary form. In the classification step, the heat treated coke activated carbon may be classified to obtain activated carbon having a uniform particle size. The classification process can be carried out, for example, by passing through a sieve. Through this classification process, for example, it is preferable to obtain coke activated carbon having a particle size of 35 μm or less, more specifically an average particle size of 2 to 20 μm.

In addition, the manufacturing of the activated carbon may optionally further include a second grinding process of pulverizing the heat treated coke activated carbon according to another exemplary form. Specifically, agglomeration may occur during the activation process and the heat treatment process, thereby increasing the size of the particles. In order to increase the uniform particle size and specific surface area, the second grinding process may be performed. At this time, the second grinding step is carried out after the heat treatment step, specifically, between the heat treatment step and the classification step, the grinding method is as described above.

According to the production of activated carbon through the above process, it is possible to produce activated carbon that can implement excellent resistance characteristics (low resistance) and the like with high capacitance (F / cc) from the coke. And the prepared coke activated carbon has the physical properties as described above. In addition, the manufactured coke activated carbon has excellent resistance characteristics, and thus can reduce the content of conductive materials (carbon black, etc.) in the preparation of the electrode composition, and can increase the content of activated carbon, thereby providing excellent energy storage characteristics and output characteristics. And high capacitance (F / cc).

2. Manufacture of carbon material

The manufacturing step of the carbon material may include (a) a first heat treatment step of primary heat treatment of coke, (b) a pulverization process of pulverizing the heat treated coke, and (c) a second heat treatment process of secondary heat treatment of the pulverized coke. And (d) includes a de-ironing process for removing the iron component of the carbonized coke carbon. In addition, the manufacturing step of the carbon material, as the (a) proceeds before the first heat treatment process, may further comprise a coarse grinding process for coarse grinding coke. The description of each process is as follows.

(a) first heat treatment process

Primary heat treatment by applying heat to the coke. At this time, the coke used as a starting material is as described above for the activated carbon, it may be selected from, for example, green coke (green cokes) generated in the process of refining petroleum. Primary heat treatment may proceed after coarse grinding of coke as described above. At this time, the coarse grinding may be pulverized coke to have a size of 200㎛ or more. The coarse grinding may be performed by, for example, a disk mill or a ball mill.

The coke is first heat treated at a temperature of 500 ° C. to 900 ° C. This primary heat treatment is a pretreatment process, thereby removing impurities such as volatile matter contained in the coke raw material. At this time, when the primary heat treatment (pretreatment) temperature is less than 500 ° C, impurity removal efficiency may decrease. And when the primary heat treatment temperature is too high exceeding 900 ℃, the degree of carbonization of the raw material is large, which is not preferable. In consideration of this point, the first heat treatment may proceed at a temperature of 600 ℃ ~ 800 ℃. The primary pretreatment time is not limited. The first heat treatment time may vary depending on the temperature, which may be, for example, 30 minutes to 5 hours, more specifically, 1 to 3 hours. In the first heat treatment, the heating furnace may use rotary equipment such as rotary kiln, and proceeds in an inert atmosphere such as nitrogen (N ₂ ) or argon (Ar) gas.

(b) grinding process

The primary heat treatment (pretreatment) coke is pulverized. The primary heat treated coke is ground to a size of, for example, 80 μm or less. As a specific example, it is ground to have an average particle size of 0.1 to 40 μm, more specifically 3 to 20 μm as a uniform size. The grinding method is not particularly limited, and this may be performed by, for example, a jet mill, a ball mill, a rotary mill, a vibration mill, or the like.

(c) second heat treatment process

Next, the pulverized coke powder is subjected to a second heat treatment.

Secondary heat treatment is carried out at a temperature of 800 ℃ to 1300 ℃. By this secondary heat treatment, substantial carbonization of the coke powder proceeds. In addition, in the present invention, the secondary heat treatment temperature acts as an important factor for the physical properties and electrical properties of the carbonaceous material made of coke. At this time, if the secondary heat treatment temperature is less than 800 ° C, for example, it is difficult to exhibit excellent resistance characteristics. And when the carbonization temperature exceeds 1300 ℃, it is difficult to implement a high capacitance (F / cc) and the like, in this case, the density is high and the compatibility with activated carbon is poor. In view of this point, it is preferable that the secondary heat treatment temperature is 900 ° C to 1200 ° C.

The secondary heat treatment is performed in an inert atmosphere such as nitrogen (N ₂ ) or argon (Ar) gas, for example, and the heat treatment time is not particularly limited. The heat treatment time may vary depending on the temperature, which may be, for example, 30 minutes to 5 hours. Heat treatment is preferably carried out for 1 to 3 hours, for example.

(d) Deviation  fair

The iron component of the second heat treatment (carbonized) coke carbon is removed. Such a degassing process needs to be able to remove the iron component contained in the coke carbon, and various methods can be considered. For example, a method using a magnet or the like may be considered.

In addition, the manufacturing step of the carbon material may further include a classification process according to an exemplary form. In this case, the classification process may be performed before or after the degassing process. The classification step may be performed by classifying the carbonized coke carbon to obtain carbon having a uniform particle size. The classification process can be carried out, for example, by passing through a sieve. Through this classification process, for example, it is preferable to obtain carbon having a particle size of 40 μm or less, more specifically an average particle size of 3 to 20 μm.

According to the manufacture of the carbon material including the above process, it is possible to produce a carbon material having a good quality from the coke. That is, it can be used in combination with activated carbon to produce a carbon material capable of realizing excellent resistance characteristics and the like with high capacitance (F / cc). And the carbon material produced has the properties as described above.

3. Mixed

The activated carbon prepared as described above and the carbon material are mixed. The mixing method is not limited, and the activated carbon and the carbon material may be mixed uniformly. And when mixing, it is possible to mix 50 to 95% by weight of activated carbon and 5 to 50% by weight of carbon material, and more specifically, for example, 55 to 90% by weight of activated carbon and 10 to 45% by weight of carbon material may be mixed. The mixed electrode material is usefully used as an electrode active material such as EDLC as described above.

According to the present invention described above, it is possible to have excellent electrical characteristics, long-term reliability and the like. In addition, coke, a byproduct generated in the petroleum refining process, may be usefully used as an electrode resource such as EDLC.

Hereinafter, the Example and comparative example of this invention are illustrated. The following examples and comparative examples are provided only to assist the understanding of the present invention, whereby the technical scope of the present invention is not limited.

[Examples and Comparative Examples]

Activated Carbon Production Example  1-1 to 1-6>

Activated carbon was manufactured by the following process using green cokes generated during the refining of petroleum.

(a) carbonization

First, green cokes were prepared as raw materials, and then they were put into a heating furnace. And after maintaining a heating furnace in nitrogen gas atmosphere, it heated up at the temperature increase rate of 5 degree-C / min, and carbonized for 2 hours at the temperature of 550 degreeC.

(b) grinding

The carbonized coke was put into a jet mill grinder and ground.

(c) activation

The pulverized coke powder was mixed with KOH (alkali activator) and then charged into an activation furnace. At this time, the pulverized coke powder and KOH were mixed at a weight ratio of 1: 3. After maintaining the activation furnace in a nitrogen gas atmosphere, the temperature was raised at a temperature increase rate of 5 ° C./min and activated at a temperature of 700 ° C. for 1 hour.

(d) cleaning / drying

The activated coke activated carbon powder was washed three times with impregnation of dipping in an aqueous hydrochloric acid solution and washing with distilled water as one cycle. This washing was brought to pH 6, followed by hot air drying.

(e) heat treatment

The cleaned / dried coke activated carbon powder was placed in a rotary kiln. And after maintaining the rotary cologne in a nitrogen gas atmosphere, the temperature was heated to a temperature increase rate of 5 ℃ / min and heat-treated. At this time, the heat treatment time was all the same as 1 hour, the heat treatment temperature was different according to each preparation example as shown in the following [Table 1].

(f) grinding / classifying

The heat treated coke activated carbon was pulverized by a vibration mill grinder, and then passed through a sieve to obtain coke activated carbon powder having an average particle size distribution of about 8 μm.

For the activated carbon according to the respective production examples, the specific surface area (m 2 / g), average particle size (μm), oxygen functional group content (meq / g), tap density (g / cm 3) and resistance (mΩ) in the following manner ) Was evaluated. The results are shown in the following [Table 1].

In Table 1 below, MSP is an activated carbon that is widely used for EDLC electrodes, and is a commercially available product (manufactured by Kuraray Co., Japan, MSP-20) manufactured using a phenol resin system. In Table 1 below, Preparation Example 1-1 is manufactured using green cokes generated during the refining process of petroleum as described above, but is coke activated carbon not subjected to heat treatment after cleaning / drying.

<Evaluation method>

(1) Specific Surface Area-N ₂ BET method using adsorption (by Japan, BEL JAPAN product, model name BEL SORP-MINI II measuring equipment)

(2) Oxygen functional group content (meq / g)-The content of the oxygen functional group present in activated carbon was analyzed by titration method. The weight of activated carbon was measured and measured by adding 0.1 mol / L NaOH solution. (Japan, product of HIRANUMA, model name COM-555 measuring equipment)

(3) Tap density-10 g of activated carbon was added to the measuring cylinder, and then mounted on a tap density measuring device (Model ATD-200, manufactured by INTEC, Korea). Thereafter, the test was performed by setting the number of test times to 3000 times, and then reading the scale of the measuring cylinder, and calculating the weight (10 g) of the activated activated carbon divided by the measuring cylinder scale (ml = cm 3).

(4) Resistance-Activated charcoal powder was put into a sealed container, pressure of 5 MPa was applied, and measured using a powder resistance measuring instrument (HANRM, Korea, model name HPRM-100).

<Evaluation of Physical Properties and Resistance of Activated Carbon by Heat Treatment> Activated carbon
Psalter Heat treatment temperature
[℃] Specific surface area
[㎡ / g] Oxygen Functional Content
[meq / g] Tap density
[g / cm 3] Resistance characteristics
[mΩ, 5MPa] Remarks MSP - 2015 0.79 0.28 26.9 MSP activated carbon Preparation Example 1-1 No 2010 0.44 0.33 28.1

Coke activated carbon Preparation Example 1-2 600 1970 0.31 0.34 27.4 Preparation Example 1-3 700 1910 0.25 0.35 26.8 Preparation Example 1-4 800 1830 0.13 0.37 26.4 Preparation Example 1-5 900 1710 Not detected (N / A) 0.40 26.0 Preparation Example 1-6 1000 1600 Not detected (N / A) 0.45 25.2

As shown in [Table 1], it can be seen that the coke activated carbon has different physical and resistance properties such as specific surface area, oxygen functional content, and tap density depending on the heat treatment temperature. In particular, when heat-treated at a temperature of 700 ° C. or higher (Manufacture Examples 1-3 to 1-6), it can be seen that it has better resistance characteristics (lower resistance value) than conventional MSP (phenolic resin activated carbon). It can also be seen that the oxygen functional group content is significantly lowered. However, since the specific surface area decreases as the temperature increases, it can be seen that heat treatment by raising the temperature above 1000 ° C. is not preferable because it adversely affects the capacity.

<Carbon material Production Example  2-1 to 2-9>

Using green cokes generated during the refining of petroleum, a carbon material was manufactured by the following process.

(a) coarse grinding

First, green cokes were prepared as raw materials, and then, the raw cokes were put into a disc mill grinder and coarsely pulverized to have a size of about 350 μm or more.

(b) Primary heat treatment (pretreatment)

The coarse coke was introduced into a rotary kiln. After maintaining the rotary cologne in a nitrogen gas atmosphere, the temperature was raised at a temperature increase rate of 5 ° C./min and heat-treated (pretreatment) at a temperature of 750 ° C. for 2 hours.

(c) fine grinding

The pretreated coke was milled into a jet mill grinder.

(d) secondary heat treatment (carbonization)

The pulverized coke powder was put into a heating furnace. And after maintaining a heating furnace in nitrogen gas atmosphere, it heated up at the temperature increase rate of 5 degree-C / min, and secondary heat processing (carbonization). At this time, the heat treatment time was the same as 2 hours, but in the case of heat treatment temperature was different according to each preparation example as shown in the following [Table 2].

(e) Classification and deviations

The secondary heat treated (carbonized) carbon material was passed through a sieve to obtain a carbon material powder having an average particle size distribution of about 12 μm. After passing through a sieve, the iron component was removed using a magnetic separator.

For the carbon material according to each of the above production examples, the specific surface area (m 2 / g), tap density (g / cm 3), and resistance (mΩ) were evaluated in the following manner. The results are shown in the following [Table 2].

<Evaluation method>

(1) Specific Surface Area-N ₂ BET method using adsorption (by Japan, BEL JAPAN product, model name BEL SORP-MINI II measuring equipment)

(2) Tap density-After putting 100 g of carbon material into the measuring cylinder, it was mounted on tap density measuring equipment (Model ATD-200, manufactured by INTEC, Korea). Thereafter, the test was performed by setting the number of test times to 3000 times, and then reading the scale of the measuring cylinder, and calculating the weight (100 g) of the carbon material injected by dividing by the measuring cylinder scale (ml = cm 3).

(3) Resistance-The carbonaceous powder was put in a closed container, 5 MPa was applied, and then measured using a powder resistance measuring instrument (HANRM, Korea, model name HPRM-100).

<Evaluation of Physical and Resistance Properties of Carbon Materials According to Secondary Annealing Temperatures> Carbon material
Psalter Secondary heat treatment temperature
[℃] Specific surface area
[㎡ / g] Tap density
[g / ㎥] Resistance characteristics
[mΩ, 5MPa] Preparation Example 2-1 800 2.9 0.60 17.7 Preparation Example 2-2 900 2.6 0.61 15.3 Preparation Example 2-3 1000 2.5 0.63 14.2 Preparation Example 2-4 1100 2.2 0.65 13.9 Preparation Example 2-5 1200 2.2 0.67 13.8 Preparation Example 2-6 1300 2.0 0.71 13.3

As shown in [Table 2], it can be seen that physical properties such as specific surface area and tap density of carbon material vary depending on the secondary heat treatment (carbonization) temperature. In particular, it can be seen that the resistance characteristics have good resistance characteristics as the heat treatment temperature is increased. This is because the crystallinity of the material increases with increasing temperature. However, when the temperature exceeds 1300 ° C., the density is too high, so that the mixing property due to the density difference when mixing with activated carbon decreases. Therefore, it was found that when the heat treatment at a temperature between 900 ° C and 1200 ° C has excellent resistance characteristics (low resistance value) and good mixing properties.

Manufacturing

1. Electrode Manufacturing

First, an electrode active material (electrode material), a binder, and a conductive material were placed in a vessel with a stirrer, and mixed and stirred to obtain a slurry-like electrode composition. Based on the total weight of the electrode composition (100% by weight), the electrode active material is 85.0% by weight, the binder is polytetrafluoroethylene (PTFE) 3.0% by weight, carboxymethyl cellulose (CMC) 1.6% by weight, styrene-butadiene rubber (SBR) 3.0 weight% and 0.4 weight% of polyvinylpyrrolidone (PVP) were mixed and used (binder total amount: 8.0 weight%), and 7.0 weight% of carbon black was used for the electrically conductive material.

In this case, in the case of the electrode active material (electrode material), the coke activated carbon and the carbon material prepared above were used in a mixed manner, but were different according to the examples and the comparative examples. Specifically, as shown in the following [Table 3], according to the Examples and Comparative Examples, the type of activated carbon and carbon material and their mixing ratio (% by weight) were different.

Then, the electrode composition (slurry) according to each of the above examples and comparative examples was pressed onto a thin film of aluminum (Al) with a roller to obtain an electrode sheet having an electrode composition layer laminated on one surface of the thin film of aluminum (Al), and then titrated. Cut to size.

2. EDLC  Cell manufacturing

The cylindrical EDLC cell was manufactured by the normal process using the obtained electrode sheet. Specifically, first, a separator (nonwoven fabric) was interposed between the two obtained electrode sheets, and then a cylindrical shape was wound. After winding, taping was finished, and then impregnated in the electrolyte (LiPF ₆ ) to prepare EDLC cells (18pi) according to the Examples and Comparative Examples.

3. Electrical characteristic evaluation

For each EDLC cell according to each of the above-described examples and comparative examples, the capacitance (F / cc) and resistance (mΩ) per unit volume at a voltage of 2.7 V were measured, and the results are shown in the following [Table 3]. Indicated.

<Evaluation of Electrical Characteristics of EDLC Cells (@ 2.7V)>
Remarks Electrode active material (electrode material)
capacitance
[F / cc]
Resistance characteristics
[mΩ] Activated carbon (% by weight) Carbon material (% by weight) Example 1 Preparation Example 1-3 (85) Preparation Example 2-3 (15) 17.8 12.0 Example 2 Preparation Example 1-3 (70) Preparation Example 2-3 (30) 17.4 11.2 Example 3 Preparation Example 1-3 (60) Preparation 2-3 (40) 16.5 10.6 Comparative Example 1 MSP (100) - 14.6 16.8 Comparative Example 2 Preparation Example 1-1 (100) - 14.8 15.5

As shown in Table 3 above, it can be seen that when the activated carbon and the carbon material are mixed as the electrode active material, both the capacitance (F / cc) and the resistance characteristics are superior to those when the activated carbon is used alone.

Looking specifically, it can be seen that when the activated carbon alone (Comparative Examples 1 and 2), the capacitance (F / cc) is somewhat good, but the resistance is very high. On the other hand, when using a mixture of activated carbon and a carbon material, it can be seen that the resistance characteristics as well as the capacitance (F / cc) is very excellent.

4. Evaluation of Resistance Characteristics of Electrode Materials

1 is a graph illustrating powder resistance of the electrode active material (electrode material) in powder form used in each of the above Examples and Comparative Examples, which is a graph showing resistance characteristics according to pressure (Mpa).

As shown in FIG. 1, the mixture of activated carbon and carbon material (Examples 1 to 3) has better resistance characteristics (lower resistance value) than activated carbon alone (Comparative Examples 1 and 2), and in particular, the pressure MPa is It can be seen that as the resistance is increased, the resistance characteristic is improved.

5. Long-term Reliability Assessment

On the other hand, for the EDLC cells according to Examples 1 to 3 and the EDLC cells according to Comparative Examples 1 and 2, capacity retention (%) and resistance increase rate (H) with time (h) compared to initial performance. ,%) Were evaluated. The results are shown in Figures 2-3.

2 is a graph showing the evaluation results of the capacity retention rate (%), which is an evaluation result at 2.7V. 3 is a graph showing evaluation results of the resistance increase rate (%), which is an evaluation result at 2.7V.

In this case, as an electrode active material (electrode material), Example 1 is 85% by weight of coke activated carbon + 15% by weight of coke carbon material, Example 2 is 70% by weight of coke activated carbon + 30% by weight of coke carbon material, Example 3 is a test piece in which 60 wt% of coke activated carbon + 40 wt% of the heat treated coke carbon material were used. In Comparative Example 1, 100% by weight of phenol resin-based activated carbon MSP-20, and Comparative Example 2 were test pieces in which 100% by weight of coke activated carbon was used.

As shown in FIGS. 2 to 3, it can be seen that the cell according to the embodiments does not have a large change rate even after a long period of time while maintaining a high capacity and a low resistance compared to the cell according to the comparative examples. This means having long term reliability.

Claims (10)

Activated carbon having a specific surface area of 1500 to 2500 m 3 / g, an average particle size of 2 to 20 μm, and a tap density of 0.2 to 0.8 g / cm 3; And
A carbon material having a specific surface area of 1 to 20 m 2 / g, an average particle size of 3 to 20 μm, and a tap density of 0.5 to 1.5 g / cm 3,
Electrode material comprising 55 to 90% by weight of the activated carbon and 10 to 45% by weight of the carbon material.
The method of claim 1,
The said activated carbon has an specific surface area of 1800-2200m <2> / g, The electrode material characterized by the above-mentioned.
delete An electrochemical device comprising the electrode material according to claim 1.
Preparing activated carbon having a specific surface area of 1500 to 2500 m 2 / g, an average particle size of 2 to 20 μm, and a tap density of 0.2 to 0.8 g / cm 3;
Preparing a carbon material having a specific surface area of 1 to 20 m 2 / g, an average particle size of 3 to 20 μm, and a tap density of 0.5 to 1.5 g / cm 3; And
Mixing the prepared carbon with the carbon material;
The mixing step is a method of producing an electrode material for mixing 55 to 90% by weight activated carbon and 10 to 45% by weight carbon material.
The method of claim 5,
Preparing the activated carbon,
A carbonization process of carbonizing coke at a temperature of 300 ° C to 800 ° C;
A grinding step of grinding the carbonized coke;
An activation process of mixing the pulverized coke with an activator and then heating the activated coke at 500 ° C to 1000 ° C;
A cleaning / drying process of cleaning and drying the activated coke activated carbon; And
And a heat treatment step of heat treating the washed and dried coke activated carbon at a temperature of 500 ° C to 1200 ° C.
The method of claim 5,
Preparing the carbon material,
A first heat treatment step of firstly heat treating the coke at a temperature of 500 ° C to 900 ° C;
A pulverizing process of pulverizing the first heat treated coke;
A second heat treatment step of performing second heat treatment on the pulverized coke at a temperature of 800 ° C. to 1300 ° C .; And
A method of producing an electrode material, characterized in that it comprises a de-ironing step of removing the iron component of the secondary heat treated coke carbon.
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