TWI511923B - Activated carbon microspheres with high specific surface area for electrode sheet and capacitor and method of manufacturing the same - Google Patents

Description

Activated carbon microsphere for high specific surface area of electrode sheet and capacitor and manufacturing method thereof

The present invention relates to an activated carbon microsphere and a method for producing the same, and more particularly to an activated carbon microsphere for a high specific surface area of an electrode sheet and a capacitor, and a method for producing the same.

Electric Double Layer Capacitors (EDLC) is an energy storage device between a battery and a common capacitor. It usually has a large capacitance, mainly because the electric double layer capacitor separates the charge. Way to store energy. The larger the area where the charge is stored or the smaller the distance at which the charge is isolated, the larger the capacitance. Therefore, electric double-layer capacitors have great application value and market potential in many fields such as electric vehicles, hybrid vehicles, special trucks, electric power, railways, telecommunications, defense, and consumer electronics.

Current double layer capacitors typically utilize a porous carbon-based electrode material to achieve a large stored charge area. For example, since activated carbon is a material having both a high specific surface area and electrical conductivity, it can be used as a porous carbon-based electrode material. Wherein a surface area per unit weight (specific surface area; units of m ² / g) and be storable capacity, and when the specific surface area is larger, the larger the capacitance will be stored.

However, the activated carbon currently produced by the general process usually cannot have the characteristics of high specific capacitance and high specific surface area at the same time, or the expensive cost is required to achieve the high specific capacitance and high specific surface area of the activated carbon. .

In view of the above, there is a need to provide an activated carbon microsphere for a high specific surface area of an electrode sheet and a capacitor and a method of manufacturing the same to overcome various problems faced by conventional processes.

Therefore, one aspect of the present invention provides a method for producing activated carbon microspheres having a high specific surface area, which is subjected to a drying step of a mesophase carbon microsphere containing a γ-resin before the activation process. The content of the γ-resin is made less than 0.5% by weight, whereby high specific surface area activated carbon microspheres are formed.

Next, another aspect of the present invention is to provide an activated carbon microsphere having a high specific surface area which is obtained by the above method. The obtained high specific surface area activated carbon microspheres have excellent specific surface area and specific capacitance values.

Furthermore, another aspect of the present invention provides an electrode sheet characterized in that the electrode sheet contains the aforementioned activated carbon microspheres.

Further, still another aspect of the present invention provides a capacitor characterized in that the capacitor includes the aforementioned electrode sheet.

According to the above aspect of the invention, a high specific surface area is proposed Method for producing carbon microspheres. In one embodiment, first, mesocarbon microbeads are provided, and mesophase carbon microspheres comprise a gamma-resin.

Next, a drying step is performed to heat the aforementioned mesocarbon microbeads at a temperature greater than 410 ° C to 550 ° C for 8 to 12 hours.

Subsequently, the intermediate phase carbon microspheres in the drying step are subjected to an activation process to form activated carbon microspheres, wherein the content of the γ-resin in the mesophase carbon microspheres is less than 0.5% by weight.

According to an embodiment of the present invention, the content of the γ-resin in the mesophase carbon microspheres is 0.05 to 0.4% by weight.

According to an embodiment of the present invention, the content of the γ-resin in the mesophase carbon microspheres is 0.05 to 0.3% by weight.

According to an embodiment of the invention, the drying step is to heat the mesocarbon microbeads at a temperature of 420 ° C to 500 ° C for 8 to 10 hours.

According to an embodiment of the invention, the drying step heats the mesocarbon microbeads at a temperature of 420 ° C to 450 ° C for 8 hours.

According to an embodiment of the present invention, the activation process further comprises performing a mixing step of mixing the activator with the mesocarbon microbeads of the drying step to form a mixture; and heating the mixture under a nitrogen atmosphere. The temperature was raised to 520 ° C at a heating rate of 1 ° C / min to 5 ° C / min at 10-40 ° C for 1.5 hours, and then the temperature was raised to 900 ° C at this temperature rising rate and held at a temperature for 4 hours to form activated carbon microspheres.

According to an embodiment of the invention, the activator is an alkali metal or alkaline earth hydroxide.

According to an embodiment of the invention, the activator is lithium hydroxide (LiOH), sodium carbonate (Na ₂ CO ₃ ), zinc chloride (ZnCl ₂ ), phosphorus pentoxide (P ₂ O ₅ ), potassium carbonate (K). ₂ CO ₃ ), calcium hydroxide [Ca(OH) ₂ ], potassium phosphate (K ₃ PO ₄ ), water vapor (H ₂ O), carbon dioxide (CO ₂ ), potassium hydroxide (KOH), sodium hydroxide ( NaOH) or ferrous sulfate (FeSO ₄ ).

According to an embodiment of the invention, the weight percentage of the mesophase carbon microspheres to the activator is 1:3.

According to an embodiment of the invention, after the activation process, at least the post-activation treatment step of the activated carbon microspheres is further included.

According to an embodiment of the invention, the post-activation treatment step comprises treating the activated carbon microspheres with steam; performing an acid washing step on the activated carbon microspheres; and performing a hot water washing step on the activated carbon microspheres.

According to an embodiment of the invention, the activated carbon microspheres in the post-activation treatment step have a specific surface area of at least 2800 m ² /g and a specific capacitance of at least 180 F/g.

According to an embodiment of the invention, the activated carbon microspheres in the post-activation treatment step have a specific surface area of at least 2837 m ² /g and a specific capacitance of at least 185 F/g.

According to another aspect of the present invention, a high specific surface area activated carbon microsphere is further produced by the above method.

According to still another aspect of the present invention, an electrode sheet comprising the aforementioned high specific surface area activated carbon microspheres is further proposed.

According to still another aspect of the present invention, a capacitor is further provided which comprises the aforementioned electrode sheet.

Applying the invention to the high specific surface area of the electrode sheet and the capacitor Carbon microspheres and a method for producing the same, which are the steps of drying the mesocarbon microbeads to reduce the content of the γ-resin in the mesophase carbon microspheres, thereby forming the activated carbon microspheres formed after the activation process It has a high specific surface area and a high specific capacitance, and overcomes the expensive process of the conventional process.

100‧‧‧ method

110‧‧‧Procedures for providing mesophase carbon microspheres

120‧‧‧Drying steps

130‧‧‧Activating process to obtain activated carbon microspheres

The above and other objects, features, advantages and embodiments of the present invention will become more <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; Part of the manufacturing process of the ball.

As described above, the present invention provides a method for producing activated carbon microspheres having a high specific surface area, which is to heat the mesocarbon microbeads at a temperature greater than 410 ° C to 550 ° C before the mesophase carbon microspheres are activated. The content of the γ-resin contained in the mesocarbon microbeads is less than 0.5% by weight to 12 hours, thereby greatly increasing the specific surface area and specific capacitance of the formed activated carbon microspheres.

Referring to FIG. 1 , a partial manufacturing flow diagram of a high specific surface area activated carbon microsphere according to an embodiment of the present invention is shown. In one embodiment of the method 100 of the present invention, first, as shown in step 110, mesophase carbon microspheres (GMP: Green Mesophase Powder) are provided, the mesophase carbon microspheres comprising a γ-resin. In one example, the above-described suitable carbon microspheres can be, for example, commercially available mesophase pitch carbon microspheres, wherein the mesophase pitch carbon microspheres have at least 60% (v/v) without any carbonization treatment. Intermediate phase It is preferred that the layer structure and quinoline insoluble (hereinafter referred to as QI) are more than 95% (w/w) or more. Next, in an example, the γ-resin is defined as a resin having a volatilization temperature of 200 ° C to 400 ° C.

After step 110 of providing mesocarbon microbeads, a drying step 120 is performed which heats the mesocarbon microbeads for a period of 8 to 12 hours at a temperature greater than 410 °C to 550 °C. It is worth mentioning that usually the mesophase carbon microspheres γ-resin will react with the activator, so that the amount of activator used is increased. Therefore, when the drying step 120 is performed, if the temperature is less than or equal to 410 ° C, the γ-resin in the mesocarbon microbeads cannot be effectively volatilized, so that the amount of the activator used is increased; if the temperature is greater than 600 ° C, the intermediate phase is caused. The carbon microspheres are easily carbonized, so that the crystallinity of the mesocarbon microbeads themselves is improved without compromising the activation effect of the subsequent activation process 130. In one embodiment, the drying step 120 can heat the mesocarbon microbeads for 8 to 10 hours at a temperature of 420 ° C to 500 ° C. In one example, the drying step 120 can be to heat the mesocarbon microbeads at a temperature of 420 ° C to 450 ° C for 8 hours.

Thereafter, the mesocarbon microbeads subjected to the drying step 120 are subjected to an activation process 130 to form activated carbon microspheres, wherein the content of the γ-resin in the mesophase carbon microspheres is less than 0.5% by weight. When the content of the γ-resin in the mesophase carbon microspheres is more than 0.5% by weight, the γ-resin will consume a large amount of the activator, resulting in an increase in the use cost of the activator. In one embodiment, the gamma-resin may be present in the intermediate phase carbon microspheres in an amount of from 0.05 to 0.4 weight percent. In one example, the gamma-resin may be present in the intermediate phase carbon microspheres in an amount from 0.05 to 0.3 weight percent.

In an embodiment, the activation process 130 can include performing a mixing step and a heating step. The mixing step is to mix the activator with the mesocarbon microbeads of the drying step 120. Next, the above mixture is subjected to a heating step, which is heated from 10-40 ° C at a temperature increase rate of 1 ° C / min to 5 ° C / min to a temperature of 520 ° C and held for 1.5 hours under nitrogen atmosphere, and then the temperature is raised. The temperature was raised to 900 ° C and held for 4 hours to form activated carbon microspheres. In one embodiment, the activator can be an alkali metal or alkaline earth hydroxide. In one example, the activating agent may include, but are not limited to, lithium hydroxide (of LiOH), sodium carbonate (Na ₂ CO _3), zinc chloride (ZnCl _2), phosphorus pentoxide (P ₂ O _5), potassium carbonate ( K ₂ CO ₃ ), calcium hydroxide (Ca(OH) ₂ ), potassium phosphate (K ₃ PO ₄ ), water vapor (H ₂ O), carbon dioxide (CO ₂ ), potassium hydroxide (KOH), sodium hydroxide (NaOH) or ferrous sulfate (FeSO ₄ ). In another illustration, the weight percentage of mesophase carbon microspheres to activator can be 1:3.

According to an embodiment of the invention, after the activation process 130, the activated carbon microspheres are further selectively subjected to a post-activation treatment step. In one example, a suitable post-activation treatment step can include, but is not limited to, a treatment step of treating the activated carbon microspheres with steam, followed by a pickling step and a hot water washing step on the activated carbon microspheres. The aforementioned steam treatment, pickling, and hot water washing can be carried out by a conventional method.

In one example, the activated carbon microspheres after the post-activation treatment step have a specific surface area of at least 2800 m ² /g and a specific capacitance of at least 180 F/g. In one example, the activated carbon microspheres after the post-activation treatment step have a specific surface area of at least 2837 m ² /g and a specific capacitance of at least 185 F/g.

It is worth mentioning that usually the mesophase carbon microspheres γ-resin will react with the activator, so that the amount of activator used is increased. The invention is first introduced The metaphase carbon microspheres are subjected to a drying step 120 to volatilize the gamma-resin originally present in the mesocarbon microbeads, after which the activation process 130 is performed to form activated carbon microspheres. Therefore, the γ-resin in the activated carbon microspheres is lowered, thereby also reducing the amount of the activator used, so that the manufacturing cost can be reduced, and the activated carbon microspheres formed later can have a high specific surface area and a high specific capacitance value. .

Secondly, since the material of the mesophase carbon microspheres is easily carbonized at 600 ° C or higher, the mesophase carbon microspheres themselves are improved in crystallinity and are not easily activated, so in the drying step 120, the temperature is greater than 410 ° C to 550 ° C. The mesophase carbon microspheres are heated to avoid carbonization. It is to be noted that the so-called non-activation is referred to herein because the activation process of the mesocarbon microbeads is such that the mesocarbon microbeads have a porous structure so that the mesocarbon microbeads have a high specific surface area. However, if the mesophase carbon microspheres undergo a carbonization reaction, the activator may be difficult to react with the carbonized mesocarbon microbeads to form a porous structure during the activation process, so that the mesophase carbon microspheres cannot be further formed to have a high specific surface area. Porous structure.

The following examples are used to illustrate the application of the present invention, and are not intended to limit the present invention. Those skilled in the art can make various changes without departing from the spirit and scope of the present invention. Retouching.

Example 1

First, the mesophase carbon microsphere G (green mesophase powder, GMP; GP-24; fix carbon>90%; volatile matter 8 ± 2%; QI is ≧ 95%, average particle size (D ₅₀ ) is 25 μm; Steel Carbon Chemical Co., Ltd., Republic of China) was heated at 420 ° C for 12 hours to remove the γ-resin contained therein to form mesocarbon microbeads DG.

Next, the mesophase carbon microspheres DG and potassium hydroxide (KOH; purity 95%; Taiwan Paper Co., Ltd., Republic of China) are formed into a mixture at a weight ratio of 1:3, and the mixture is further subjected to a heating step. Under a nitrogen atmosphere, the temperature is raised from 520 ° C to 520 ° C at a heating rate of 1 ° C / min to 5 ° C / min using a two-stage linear heating method and held at a temperature of 1.5 hours. °C and holding for 4 hours to obtain activated carbon microspheres.

Next, a post-activation treatment step of reacting water vapor with activated carbon microspheres, performing filtration, pickling, hot water washing, and the like to obtain activated carbon microspheres is performed.

Comparative example 1

The preparation method of the first embodiment is different in that the comparative example 1 provides mesophase carbon microspheres BG (China Steel Carbon Chemical Co., Ltd., Republic of China), which adds a partial low softening point to the mesocarbon microbeads G. Mesophase carbon microspheres are formed, and the mesocarbon microbeads BG are not subjected to a drying step.

Comparative example 2

The preparation method of the first embodiment was different in that the comparative example 2 was to provide the mesocarbon microbeads G, and the drying step was not performed.

Evaluation method

The performance and the activated carbon microspheres of Comparative Examples 1 to 2 were subjected to a plurality of performance tests. The test items are as follows:

1. Evaluation of γ-resin and β-resin content

The content of γ-resin and β-resin in the mesocarbon microbeads was measured using a commercially available thermogravimetric analyzer (Perkin Elmer SII, Pyris Diamond TG/DTA) at a temperature rise of about 20 ° C per minute, wherein the β-resin was It is defined as a resin having a volatilization temperature of more than 400 ° C to 600 ° C, and the results obtained are shown in Table 1 below.

2. Evaluation of specific surface area, total pore volume and average pore size

The specific surface area (BET; m ² /g), average pore diameter (nm), and total pore volume (cm ³ ) of activated carbon microspheres were measured using a commercially available pore size analyzer (Micromeritics, model ASAP2020), and the results are as shown in Table 1 above. Shown.

3. Evaluate the specific capacitance value

First, 3.2 g of activated carbon microspheres, 13.4 g of methylpyrrolidone, 0.6 g of polyvinylidene fluoride, 0.2 g of conductive carbon black and 0.004 g of a subsequent accelerator were prepared into an activated carbon slurry having a viscosity of about 3500 cps, and tested using a commercially available viscometer (Brookfiled LVDV viscometer). The parameters were 10 rpm, No. 64 rotor, shear rate of 2.1 / sec, and the resulting viscosity test results.

Next, the activated carbon slurry obtained above was applied onto a 30 μm-thick aluminum foil, and baked at a temperature of 150 ° C for 10 minutes to form an activated carbon electrode sheet, and the activated carbon electrode sheet was cut into two areas of 1.327 each. Square test piece of square centimeter, two circular test pieces with polypropylene (PP) separator and electrolyte with a concentration of 1M (electrolyte is tetraethylammonium tetrafluoroborate (Et ₄ NBF ₄ ); solvent is carbonic acid Propylene ester (PC)) to form the same test capacitor as the international standard specification CR2032.

Then, electrochemically, the current/volt electrochemical scan was performed at a scan rate of 10 mV/s, and the specific capacitance values of the respective test capacitors were obtained by integration, and the results obtained are shown in Table 1 above.

As is apparent from the results of the first table, the activated carbon microspheres of Example 1 have a specific surface area of at least 2800 m ² /g and a high specific capacitance value of at least 180 F/g, which is the object of the present invention, wherein the activated carbon of Example 1 The microspheres further have a specific surface area of at least 2837 m ² /g and a high specific capacitance value of at least 185 F/g. However, the specific surface area and specific capacitance values of the carbon microspheres of Comparative Example 1 and Comparative Example 2 were both smaller than that of Example 1.

It should be noted that the present invention describes a high specific surface area active carbon microsphere for an electrode sheet and a capacitor of the present invention, and a method for producing the same, by using a specific material, a process, a reaction condition, an analytical method, or a specific instrument as an example. However, it is to be understood by those skilled in the art that the present invention is not limited thereto, and the high specific surface area activated carbon microspheres for the electrode sheets and capacitors of the present invention are not deviated from the spirit and scope of the present invention. The method of manufacture and its methods of manufacture can also be carried out using other materials, processes, reaction conditions, analytical methods or instruments.

It can be seen from the above embodiments of the present invention that the activated carbon microspheres for high specific surface area of the electrode sheet and the capacitor and the method for manufacturing the same have the advantages of using a drying step to remove the content of the γ-resin, in addition to being effective in reducing In addition to the amount of activator, the specific surface area and specific capacitance of the activated carbon microspheres can be increased, and thus applied to the electrode sheets and capacitors.

While the invention has been described above in terms of several embodiments, it is not intended to limit the scope of the invention, and the invention may be practiced in various embodiments without departing from the spirit and scope of the invention. The scope of protection of the present invention is defined by the scope of the appended claims.

100‧‧‧ method

110‧‧‧Procedures for providing mesophase carbon microspheres

120‧‧‧Drying steps

130‧‧‧Activating process to obtain activated carbon microspheres

Claims (14)

A method for producing high specific surface area activated carbon microspheres comprising: providing a mesophase carbon microsphere which is an intermediate phase layer having at least 60% (v/v) without any carbonization treatment The structure, the quinoline insoluble (QI) is greater than 95% (w/w) and contains more than 0.5% by weight of the γ-resin; and a drying step is performed at a temperature greater than 410 ° C to 550 ° C for the middle The carbon microspheres are heated for 8 to 12 hours; and the intermediate carbon microspheres subjected to the drying step are subjected to an activation process to form the activated carbon microspheres, wherein the activation process further comprises: performing a mixing step, mixing An activator and the mesocarbon microbeads through the drying step to form a mixture; and a heating step of the mixture under a nitrogen atmosphere at 10 ° C to 1 ° C / min The temperature was raised to 520 ° C at a temperature increase rate of 5 ° C / min and held at a temperature of 1.5 hours, and then heated to 900 ° C at the temperature increase rate and held for 4 hours to form the activated carbon microspheres, and wherein the γ-resin was active. One of the carbon microspheres is less than 0.5% by weight, by the activity The activated carbon microspheres of the post-treatment step have a specific surface area of at least 2800 m ² /g and a specific capacitance of at least 180 F/g. The method for producing a high specific surface area activated carbon microsphere according to claim 1, wherein the content of the γ-resin in the mesocarbon microbead is 0.05 to 0.4% by weight. The method for producing a high specific surface area activated carbon microsphere according to claim 1, wherein the content of the γ-resin in the mesocarbon microbead is 0.05 to 0.3% by weight. The method for producing a high specific surface area activated carbon microsphere according to claim 1, wherein the drying step heats the mesocarbon microbeads at a temperature of 420 ° C to 500 ° C for 8 to 10 hours. The method for producing a high specific surface area activated carbon microsphere according to claim 1, wherein the drying step heats the mesocarbon microbeads at a temperature of 420 ° C to 450 ° C for 8 hours. The method for producing a high specific surface area activated carbon microsphere according to the first aspect of the invention, wherein the activator is an alkali metal or alkaline earth hydroxide. The method for producing high specific surface area activated carbon microspheres according to claim 1, wherein the activator is lithium hydroxide (LiOH), sodium carbonate (Na ₂ CO ₃ ), zinc chloride (ZnCl ₂ ) Phosphorus pentoxide (P ₂ O ₅ ), potassium carbonate (K ₂ CO ₃ ), calcium hydroxide (Ca(OH) ₂ ), potassium phosphate (K ₃ PO ₄ ), water vapor (H ₂ O), carbon dioxide (CO ₂ ), potassium hydroxide (KOH), sodium hydroxide (NaOH) or ferrous sulfate (FeSO ₄ ). High specific surface area activity as described in item 1 of the patent application The method for producing carbon microspheres, wherein the weight ratio of the mesocarbon microbeads to the activator is 1:3. According to the method for producing a high specific surface area activated carbon microsphere according to claim 1, in the activation process, at least a post-activation treatment step is performed on the activated carbon microsphere. The method for producing a high specific surface area activated carbon microsphere according to claim 9, wherein the post-activation treatment step comprises: treating the activated carbon microsphere with steam; and performing pickling on the activated carbon microsphere. a step; and performing a hot water washing step on the activated carbon microspheres. The method for producing a high specific surface area activated carbon microsphere according to claim 9, wherein the activated carbon microspheres subjected to the post-activation treatment step have a specific surface area of at least 2837 m ² /g and a specific capacitance value of at least 185F/g. A high specific surface area activated carbon microsphere obtained by the method according to any one of claims 1 to 11. An electrode sheet characterized in that the electrode sheet contains activated carbon microspheres having a high specific surface area as described in claim 12 of the patent application. A capacitor characterized in that the capacitor comprises the electrode sheet as described in claim 13 of the patent application.