Composite activated supercapacitor carbon preparation method and material

Abstract

The invention discloses a composite activated supercapacitor carbon preparation method and a material, which are characterized in that biomass is used as a raw material, alkali or phosphoric acid is firstly used for primary activation pore-forming, then activating agent recovery and elution are carried out, water vapor is used as an activating agent for secondary activation pore-forming, washing is carried out with a dilute acid solution and pure water for multiple times, and drying is carried out; and crushing to a specified required particle size, and carrying out high-temperature reduction treatment to finally obtain the super-capacitor carbon. Compared with a single water vapor activation method, the yield of the super-capacitor carbon obtained by the technical scheme is improved by 20-40%, the electrochemical performance is equivalent to that of the super-capacitor carbon obtained by the single water vapor activation method, and the raw material cost is effectively reduced; compared with a single potassium hydroxide activation method, equipment corrosion is reduced, and the equipment production cost is effectively reduced.

Description

Technical Field

[0001] The invention relates to the field of supercapacitor carbon, and in particular to a preparation method and material of composite activated supercapacitor carbon. Background Art

[0002] At present, the preparation of supercapacitor carbon materials basically uses water vapor or potassium hydroxide as an activator, and the raw materials are mainly high-purity organic raw materials such as coconut shells and petroleum coke. Among them, the water vapor activation method has a high activation temperature of 850-950°C, and requires multi-stage activation treatment. The yield of the prepared supercapacitor carbon is low, and the cost of raw materials and fuel is high; the potassium hydroxide activation method is under high-temperature activation conditions, and potassium hydroxide is highly corrosive, which has very large corrosion to equipment and containers. Therefore, it is also easy to introduce a large amount of impurities, and a large amount of refining and purification treatment is required, which greatly increases the production cost. Therefore, in order to reduce the production cost of supercapacitor carbon, a method with a higher activation yield and lower equipment use cost should be adopted.

[0003] The application number is ZL201611191927.3, "A method for recovering KOH and refining activated carbon in a process for preparing super activated carbon by KOH activation". The amount of potassium hydroxide used in the activation process is 3-4 times the amount of raw materials; the recovery process of potassium hydroxide after activation is complicated and the operation is difficult; the high temperature and high concentration of potassium hydroxide activation conditions are extremely corrosive to production equipment, and a large amount of metal ion impurities are introduced, making production more complicated; all of these have greatly increased production costs.

[0004] The "Method for Producing Supercapacitor Activated Carbon by Full Physical Method" with application number CN201711474455.7 uses coconut shell as raw material, first adopts segmented low-temperature carbonization, and then uses combustible gas and water vapor to activate it under high temperature and high pressure conditions. The production equipment has a complex structure and extremely high requirements.

[0005] The "System and Method for Preparing Straw Microwave Hydrothermal-Based Supercapacitor Activated Carbon Electrode Materials" with application number CN201910823170.2 uses a combination of microwave low-temperature acidic hydrothermal and high-temperature alkaline activation for straw. The production equipment has a complex structure, and the output requires secondary processing and collection, which increases the production cost.

[0006] The "Process for Preparing Petroleum Coke-Based High Specific Surface Area Activated Carbon" with application number CN201911417737.2 uses petroleum coke to prepare activated carbon, and also has the problems existing in the existing activated carbon production process, including the complex potassium hydroxide recovery process, and the strong corrosion of production equipment under high temperature and high concentration potassium hydroxide activation conditions. The "Two-Activation Industrial Preparation Method for Highly Conductive Coconut Shell Activated Carbon for Supercapacitors" with application number CN201910075207.8 uses a two-reduction activation process to prepare activated carbon from coconut shells from the perspective of removing surface groups and improving the surface activity of activated carbon, and the production process is complex. Summary of the invention

[0007] In view of this, the purpose of the present invention is to provide a method and material for preparing composite activated supercapacitor carbon.

[0008] In order to achieve the above technical objectives, the technical solution adopted by the present invention is:

[0009] In a first aspect, the present invention provides a method for preparing a composite activated supercapacitor carbon, comprising:

[0010] The biomass raw material and the activator are stirred and mixed according to a preset ratio to form a first precursor;

[0011] Performing a primary activation and pore formation on the first precursor to obtain a primary activated material;

[0012] Performing gradient recovery washing on the primary activated material to obtain a first washed activated material;

[0013] adding a first acid solution to the first washed activated material for washing to obtain a second washed activated material;

[0014] adding pure water to the second washed activated material for washing to obtain a third washed activated material, and dehydrating and drying the third washed activated material to obtain a primary dried material;

[0015] Perform secondary activation and pore forming on the primary dried material to obtain secondary activated material;

[0016] adding a second acid solution to the secondary activated material for washing to obtain a fourth washed activated material;

[0017] adding pure water to the fourth washed activated material for washing to obtain a fifth washed activated material, and dehydrating and drying the fifth washed activated material to obtain a secondary dried material;

[0018] The secondary dried material is crushed to obtain a first carbon material;

[0019] The first carbon material is protected by an inert gas and subjected to a high-temperature reduction treatment to obtain a second carbon material, wherein the second carbon material is supercapacitor carbon.

[0020] In some embodiments, the activator may be selected from potassium hydroxide, sodium hydroxide, zinc chloride, phosphoric acid, and the like.

[0021] In some embodiments, the temperature of the primary activation pore-forming process is 350-750°C.

[0022] In some embodiments, the mass fraction of the first acid solution and / or the second acid solution is 2-20%, and the solution temperature is 60-120° C. The acid solution is one or more of hydrofluoric acid, hydrochloric acid, nitric acid, and sulfuric acid.

[0023] In some embodiments, adding a first acid solution to a first washing and activation material for washing to obtain a second washing and activation material comprises:

[0024] Add the first acid solution to the first washed activated material and wash it 3-5 times to obtain a second washed activated material;

[0025] Pure water is added to the second washed activated material for washing to obtain a third washed activated material, and the third washed activated material is filtered, dehydrated, and dried to obtain a primary dried material comprising:

[0026] Pure water is added to the second washed activated material to wash until the pH is 6-7, and washing is stopped to obtain a third washed activated material, which is then dried at a drying temperature in the range of 110-150° C. for 3-6 hours.

[0027] In some embodiments, adding a second acid solution to the secondary activated material for washing to obtain a fourth washed activated material comprises:

[0028] Add the second acid solution to the secondary activated material and wash it 3-5 times to obtain a fourth washed activated material;

[0029] Adding pure water to the fourth washed activated material for washing to obtain a fifth washed activated material, filtering, dehydrating and drying the fifth washed activated material to obtain a secondary dried material includes:

[0030] Pure water is added to the fourth washed activated material to wash until the pH value is 6-7, and washing is stopped to obtain a fifth washed activated material, which is then dried at a drying temperature in the range of 110-150° C. for 3-6 hours.

[0031] In some embodiments, the primary dried material is subjected to secondary activation and pore formation to obtain the secondary activated material, which comprises:

[0032] The primary dried material is subjected to secondary activation and pore-forming by using water vapor at a temperature range of 800-1000°C, and the time for the secondary activation and pore-forming is 1-2.5 hours.

[0033] In some embodiments, the particle size of the first carbon material is D50=6-8 μm;

[0034] The first carbon material is protected by an inert gas and subjected to a high-temperature reduction treatment to obtain a second carbon material comprising:

[0035] The first carbon material is protected by an inert gas and subjected to a reduction treatment at a temperature ranging from 600 to 800° C. The reduction treatment time is 1.5 to 3 hours to obtain a second carbon material.

[0036] In a second aspect, the present invention provides a composite activated supercapacitor carbon material, which is prepared by the preparation method described in the first aspect.

[0037] By adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0038] (1) The two-step activation method has a higher product yield than the single steam activation method, with a yield of 8-10%, which can effectively reduce the cost of raw materials.

[0039] (2) Compared with the supercapacitor carbon produced by a single potassium hydroxide activation method, the supercapacitor carbon avoids the use of activators that are corroded by strong alkalis, avoids the use of expensive metal production equipment that is resistant to high temperature and strong alkali corrosion, and reduces the corrosion of the production equipment, thereby effectively reducing the production cost.

[0040] (3) The technical solution of the present invention first performs a primary activation to obtain a developed pore structure, and the primary activation yield is extremely high, reaching 50-70%, and then uses water vapor as an activator to perform a secondary activation. The secondary activation is performed on the basis of the primary activation and the pore structure is regulated. The supercapacitor carbon produced has a stable microporous structure, higher capacitance and better cycle performance, and exhibits superior comprehensive electrochemical performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0042] Figure 1 The present invention is a flow chart of a method for preparing a composite activated supercapacitor carbon. DETAILED DESCRIPTION

[0043] The present invention will be further described in detail below in conjunction with the accompanying drawings and examples. It is particularly noted that the following examples are only used to illustrate the present invention, but are not intended to limit the scope of the present invention. Similarly, the following examples are only partial embodiments of the present invention rather than all embodiments, and all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present invention.

[0044] See also Figure 1 In a first aspect, the present invention provides a method for preparing a composite activated supercapacitor carbon, comprising:

[0045] S1, stirring and mixing the biomass raw material and the activator according to a preset ratio to form a first precursor;

[0046] S2, performing a primary activation and pore formation on the first precursor to obtain a primary activated material;

[0047] S3, performing gradient recovery washing on the primary activated material to obtain a first washed activated material;

[0048] S4, adding the first acid solution to the first washed activated material for washing to obtain a second washed activated material;

[0049] S5, adding pure water to the second washed activated material for washing to obtain a third washed activated material, and dehydrating and drying the third washed activated material to obtain a primary dried material;

[0050] S6, performing secondary activation and pore forming on the primary dried material to obtain a secondary activated material;

[0051] S7, adding the second acid solution to the secondary activated material for washing to obtain a fourth washed activated material;

[0052] S8, adding pure water to the fourth washed activated material for washing to obtain a fifth washed activated material, and dehydrating and drying the fifth washed activated material to obtain a secondary dried material;

[0053] S9, crushing the secondary dried material to obtain a first carbon material;

[0054] S10, using an inert gas to protect the first carbon material and performing a high-temperature reduction treatment to obtain a second carbon material, wherein the second carbon material is supercapacitor carbon.

[0055] The activators usually used are potassium hydroxide, sodium hydroxide, zinc chloride and phosphoric acid.

[0056] In some embodiments, the temperature of the primary activation pore-forming process is 350-750°C.

[0057] In some embodiments, the mass fraction of the first acid solution and / or the second acid solution is 2-20%, and the solution temperature is 60-120° C. The acid solution is one or more of hydrofluoric acid, hydrochloric acid, nitric acid, and sulfuric acid.

[0058] In some embodiments, adding a first acid solution to a first washing and activation material for washing to obtain a second washing and activation material comprises:

[0059] Add the first acid solution to the first washed activated material and wash it 3-5 times to obtain a second washed activated material;

[0060] Adding pure water to the second washed activated material for washing to obtain a third washed activated material, and dehydrating and drying the third washed activated material to obtain a primary dried material comprises:

[0061] Pure water is added to the second washed activated material to wash until the pH is 6-7, and washing is stopped to obtain a third washed activated material, which is then dried at a drying temperature in the range of 110-150° C. for 3-6 hours.

[0062] In some embodiments, adding a second acid solution to the secondary activated material for washing to obtain a fourth washed activated material comprises:

[0063] Add the second acid solution to the secondary activated material and wash it 3-5 times to obtain a fourth washed activated material;

[0064] Adding pure water to the fourth washed activated material for washing to obtain a fifth washed activated material, filtering, dehydrating and drying the fifth washed activated material to obtain a secondary dried material includes:

[0065] Pure water is added to the fourth washed activated material to wash until the pH value is 6-7, and washing is stopped to obtain a fifth washed activated material, which is then dried at a drying temperature in the range of 110-150° C. for 3-6 hours.

[0066] In some embodiments, the primary dried material is subjected to secondary activation and pore formation to obtain the secondary activated material, which comprises:

[0067] The primary dried material is subjected to secondary activation and pore-forming by using water vapor at a temperature range of 800-1000°C, and the time for the secondary activation and pore-forming is 1-2.5 hours.

[0068] In some embodiments, the particle size of the first carbon material is D50=6-8 μm;

[0069] The first carbon material is protected by an inert gas and subjected to a high-temperature reduction treatment to obtain a second carbon material comprising:

[0070] The first carbon material is protected by an inert gas and subjected to a reduction treatment at a temperature ranging from 600 to 800° C. The reduction treatment time is 1.5 to 3 hours to obtain a second carbon material.

[0071] In a second aspect, the present invention provides a composite activated supercapacitor carbon material, which is prepared by the preparation method described in the first aspect.

[0072] The supercapacitor carbon material was made into a button-type capacitor for performance testing. At a current density of 50mA / g, the obtained material mass specific capacity reached 109F / g, while the material volume specific capacity reached 54.5F / cm3. The material tap density can reach 0.401g / mL, and the material yield of the whole process is 5.7%.

[0073] Example 1

[0074] S101: After the biomass raw material and the activator are uniformly stirred, they are transported to an activation furnace for primary carbonization at a carbonization temperature of 200° C. to obtain a first precursor;

[0075] S102: Passing the first precursor through a rotary kiln at a temperature of 450-650° C. to perform primary activation and pore formation to obtain a primary activated material;

[0076] S103: purifying and drying the primary activated material by gradient recovery washing;

[0077] S104: putting the fifth washed activated material into an activation furnace at 900° C., reacting with water vapor for 2 hours, and taking out the secondary dried material after cooling;

[0078] S105: crushing the secondary dried material to obtain a first carbon material with a particle size of D50=6-8 um;

[0079] S106: Finally, the supercapacitor carbon material is obtained by high temperature reduction treatment at 650°C for 2h.

[0080] The supercapacitor carbon material was made into a button-type capacitor for performance testing. At a current density of 50mA / g, the obtained material mass specific capacity reached 115F / g, while the material volume specific capacity reached 56.8F / cm3. The material's tap density could reach 0.42g / mL, which was better than that of the material prepared by the steam method. The material yield of the whole process was 9.6%.

[0081] Comparative Example 1

[0082] S201: putting the biomass raw material into a carbonization furnace for pre-carbonization treatment;

[0083] S202: putting the pre-carbonized first precursor into an activation furnace at 950° C. and reacting it with water vapor for 5 hours to obtain a primary activated material;

[0084] S203: purifying and drying the primary activated material using a washing system;

[0085] S204: crushing the secondary dried material to obtain a particle size of D50=6-8um;

[0086] S205: Finally, the supercapacitor carbon material is obtained by high temperature reduction treatment at 650°C for 2h.

[0087] The supercapacitor carbon material was made into a button-type capacitor for performance testing. At a current density of 50mA / g, the obtained material mass specific capacity reached 109F / g, while the material volume specific capacity reached 54.5F / cm3. The material tap density can reach 0.401g / mL, and the material yield of the whole process is 5.7%.

[0088] By comparing Example 2 with Comparative Example 1, it can be seen that the supercapacitor carbon material prepared in Example 2 has higher mass specific capacity, tap density and whole process material yield, better performance and lower production cost.

[0089] In summary, the supercapacitor carbon material prepared by the present invention has a higher activation yield and a lower material cost.

[0090] Different from the prior art, the above technical scheme adds an activator to the biomass raw material, and stirs and mixes it according to a preset ratio to form a first precursor, performs a first activation and pore formation on the first precursor, and then performs gradient recovery and washing to achieve the recycling and reuse of the activator, reduce the production cost, use acid solution and pure water for multiple washing and drying, and then perform secondary activation and pore formation to obtain a secondary activated material, and repeat the acid solution and pure water for multiple washing and drying to form a secondary drying material, and the secondary drying material is crushed, and then subjected to high-temperature reduction treatment to form supercapacitor carbon. In this process, compared with the supercapacitor carbon produced by conventional steam activation method, the yield of supercapacitor carbon shown in this technical scheme can be increased by 15-20%, and the prepared supercapacitor carbon material has the same performance as the material obtained by steam activation method, effectively reducing the production cost of supercapacitor carbon, and easy to promote industrialization; compared with the potassium hydroxide activation method, the method steps shown in this technical scheme are less corrosive to the equipment, reducing the corrosion of the production equipment and reducing the production cost.

[0091] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0092] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, server, or network device, etc.) or a processor (processor) to perform all or part of the steps of each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0093] The above descriptions are only some embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any equivalent device or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for preparing composite activated supercapacitor carbon, characterized in that: include: The biomass raw material and the activator are stirred and mixed according to a preset ratio, and kneaded to form a first precursor; Performing a primary activation and pore formation on the first precursor to obtain a primary activated material; Performing activator recovery washing on the primary activated material to obtain a first washed activated material; adding a first acid solution to the first washed and activated material for washing to obtain a second washed and activated material; adding pure water to the second washed activated material for washing to obtain a third washed activated material, and filtering, dehydrating and drying the third washed activated material to obtain a primary dried material; Performing secondary activation and pore formation on the primary dried material to obtain a secondary activated material; adding a second acid solution to the secondary activated material for washing to obtain a fourth washed activated material; adding pure water to the fourth washed activated material for washing to obtain a fifth washed activated material, and dehydrating and drying the fifth washed activated material to obtain a secondary dried material; Crushing the secondary dried material to obtain a first carbon material; The first carbon material is protected by an inert gas and subjected to a high-temperature reduction treatment to obtain a second carbon material, wherein the second carbon material is the supercapacitor carbon.

2. The method for preparing composite activated supercapacitor carbon according to claim 1, characterized in that: The activators usually used are potassium hydroxide, sodium hydroxide, zinc chloride and phosphoric acid.

3. The method for preparing composite activated supercapacitor carbon according to claim 1, characterized in that: The temperature of the primary activation pore-forming is 350-750°C.

4. The method for preparing composite activated supercapacitor carbon according to claim 1, characterized in that: The mass fraction of the first acid solution and / or the second acid solution is 2-20%, and the solution temperature is 60-120° C. The acid solution is one or more of hydrofluoric acid, hydrochloric acid, nitric acid, and sulfuric acid.

5. The method for preparing composite activated supercapacitor carbon according to claim 1 or 4, characterized in that: Adding a first acid solution to the first washing and activation material for washing to obtain a second washing and activation material comprises: Adding the first acid solution to the first washed activated material and washing it 3-5 times to obtain the second washed activated material; The method of adding pure water to the second washed activated material for washing to obtain a third washed activated material, and dehydrating and drying the third washed activated material to obtain a primary dried material comprises: Pure water is added to the second washed activated material to wash until the pH value is 6-7, and washing is stopped to obtain the third washed activated material, which is then dried at a drying temperature in the range of 110-150° C. for 3-6 hours.

6. The method for preparing composite activated supercapacitor carbon according to claim 1 or 4, characterized in that: Adding a second acid solution to the secondary activated material for washing to obtain a fourth washed activated material comprises: Add the second acid solution to the secondary activated material and wash it 3-5 times to obtain the fourth washed activated material; Adding pure water to the fourth washed activated material for washing to obtain a fifth washed activated material, and dehydrating and drying the fifth washed activated material to obtain a secondary dried material comprises: Pure water is added to the fourth washed activated material for washing until the pH value is 6-7, and washing is stopped to obtain the fifth washed activated material, which is then dried at a drying temperature in the range of 110-150° C. for 3-6 hours.

7. The method for preparing composite activated supercapacitor carbon according to claim 1, characterized in that: The primary dried material is subjected to secondary activation and pore formation to obtain the secondary activated material, comprising: The primary dried material is subjected to secondary activation and pore formation by using water vapor at a temperature range of 800-1000° C. The time for the secondary activation and pore formation is 1-2.5 hours.

8. The method for preparing composite activated supercapacitor carbon according to claim 1, characterized in that: The particle size D50 of the first carbon material is 6-8 μm; The first carbon material is protected by an inert gas and subjected to a high-temperature reduction treatment to obtain a second carbon material, comprising: The first carbon material is protected by an inert gas and subjected to a reduction treatment at a temperature ranging from 600 to 800° C. for a reduction treatment time of 1.5 to 3 hours to obtain the second carbon material.

9. A composite activated supercapacitor carbon material, characterized in that: The supercapacitor carbon material is prepared by the preparation method according to any one of claims 1 to 8.

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