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CN-121983442-A - Directional preparation process of porous structure of composite electrode of supercapacitor

CN121983442ACN 121983442 ACN121983442 ACN 121983442ACN-121983442-A

Abstract

The invention discloses a directional preparation process of a porous structure of a composite electrode of a super capacitor, which relates to the technical field of super capacitors and comprises the following steps of mixing MXene dispersion liquid, a nitrogen-doped carbon source, a metal organic frame precursor and a pore structure guiding agent according to a preset proportion, stirring and adding a crosslinking modifier and a surfactant to prepare a precursor composite solution; injecting the composite solution into a mould to form an oriented ice crystal template, obtaining an oriented porous aerogel skeleton, obtaining a graded porous carbonization intermediate, immersing the carbonization intermediate into a precursor solution containing transition metal salt and chalcogen element source, performing hydrothermal reaction to form a heterojunction, and constructing a conductive enhancement layer and hydrophilic functional groups through plasma or chemical vapor deposition treatment to obtain the target structure. According to the invention, a directional hierarchical porous structure is constructed, the combination of component interfaces is optimized, the conductivity, the ion transmission efficiency and the structural stability are improved, the process is controllable and easy to scale, the prepared electrode material has excellent comprehensive performance, and the high-performance energy storage requirement is met.

Inventors

  • HUANG YUMING
  • Su Xuehai
  • YANG HUI

Assignees

  • 蜂窝活性炭有限公司

Dates

Publication Date
20260505
Application Date
20260116

Claims (10)

  1. 1. The directional preparation process of the porous structure of the supercapacitor composite electrode is characterized by comprising the following steps of: s1, preparing a precursor solution, namely mixing an MXene dispersion liquid, a nitrogen-doped carbon source, a metal organic frame precursor and a pore structure guiding agent according to a preset proportion, and adding a crosslinking modifier and a surfactant under stirring to prepare a uniform and stable precursor composite solution; S2, molding a directional ice template, namely injecting the precursor composite solution into a mold, directionally solidifying by adopting a unidirectional freezing technology, and controlling the freezing speed to be 0.5-10mm/min and the freezing temperature to be-196 ℃ to-40 ℃; S3, freeze drying and demoulding, namely freeze drying the directionally solidified sample for 12-72 hours at the temperature of-80 ℃ to-40 ℃ and the vacuum degree of 1-50Pa, and removing the ice crystal template by sublimation to obtain a precursor aerogel framework of the directionally arranged pore channels; S4, performing heat treatment and carbonization activation, namely placing the precursor aerogel framework in protective atmosphere, heating to 600-1000 ℃ at a heating rate of 1-10 ℃ per minute, carbonizing for 1-6 hours, and then introducing activating gas to activate for 0.5-3 hours at 700-900 ℃ to obtain a carbonized intermediate with a hierarchical porous structure; s5, in-situ growth and compounding, namely immersing a carbonization intermediate into a precursor liquid containing transition metal salt and chalcogen element source, and carrying out hydrothermal reaction for 4-24 hours at 120-220 ℃ to enable the transition metal chalcogen compound to grow in situ on the inner wall of the directional pore canal to form a heterojunction composite structure; S6, performing surface modification treatment, namely performing plasma surface modification or chemical vapor deposition treatment on the heterojunction composite structure, and constructing a conductive enhancement layer and hydrophilic functional groups on the surface of the pore canal to obtain the supercapacitor composite electrode porous structure.
  2. 2. The process for directionally preparing the porous structure of the composite electrode of the supercapacitor according to claim 1, wherein in the step S1, the concentration of the MXene dispersion liquid is 0.5-20mg/mL, and the MXene is selected from The nitrogen-doped carbon source is one or more selected from melamine, dicyandiamide, urea, polydopamine, polyaniline and chitosan, the addition amount is 50-500% of the mass of MXene, the metal organic framework precursor is one or more selected from ZIF-8, ZIF-67, MIL-88, uiO-66 and HKUST-1, and the addition amount is 20-300% of the mass of MXene.
  3. 3. The directional preparation process of the porous structure of the supercapacitor composite electrode according to claim 1, wherein in the step S1, the pore structure guiding agent is one or more selected from polyvinyl alcohol, polyethylene glycol, polyethylene oxide, sodium carboxymethyl cellulose and sodium alginate, the concentration is 0.1-10wt%, the crosslinking modifier is one or more selected from glutaraldehyde, epichlorohydrin, citric acid, boric acid and genipin, the mass ratio of the crosslinking modifier to the pore structure guiding agent is 0.01-0.5:1, and the surfactant is one or more selected from sodium dodecyl sulfate, cetyltrimethylammonium bromide, triton X-100 and tween 80, and the addition amount is 0.01-2% of the total mass of the precursor composite solution.
  4. 4. The directional preparation process of the supercapacitor composite electrode porous structure according to claim 1 is characterized in that in the step S2, a one-way freezing technology adopts a bottom freezing mode, namely, a precursor composite solution is injected into a columnar mold with an opening at the top, the bottom of the mold is a high heat conduction metal plate, the side wall of the mold is a heat insulation material, the bottom of the mold is contacted with a cold source, the cold source is selected from one of a liquid nitrogen cold bath, a dry ice-ethanol cold bath, a semiconductor refrigerating sheet and a program temperature control freezing table, the temperature of the cold source is controlled to be between-196 ℃ and-40 ℃, and the contact area of the cold source and the mold or the power of the cold source are regulated.
  5. 5. The directional preparation process of the supercapacitor composite electrode porous structure according to claim 1, wherein in the step S3, a gradient heating program is adopted for freeze drying treatment, wherein the first stage is kept for 4-12 hours under the conditions of-80 ℃ to-60 ℃ and the vacuum degree of 1-10Pa, the second stage is kept for 4-24 hours at the rate of 0.5-2 ℃ to-40 ℃ to-30 ℃ and the vacuum degree of 5-20Pa, the third stage is kept for 4-24 hours at the rate of 1-5 ℃ to 0-25 ℃ and the vacuum degree of 10-50Pa, and finally the directional porous aerogel framework with the porosity of 85-98% and the pore diameter of 5-200 mu m is obtained.
  6. 6. The directional preparation process of the supercapacitor composite electrode porous structure according to claim 1, wherein in the step S4, the protective atmosphere is selected from one of nitrogen, argon and a mixed gas of nitrogen and hydrogen, the volume fraction of hydrogen in the mixed gas is 3-10%, the carbonization treatment adopts a sectional heating program, the temperature is raised to 300-400 ℃ at a rate of 1-3 ℃ per minute, the temperature is kept for 0.5-2 hours for pre-carbonization, the temperature is raised to 600-1000 ℃ at a rate of 2-5 ℃ per minute, the temperature is kept for 1-6 hours for complete carbonization, the activating gas is selected from one or more of carbon dioxide, water vapor and ammonia, the flow rate is 50-500mL per minute, the micropore diameter of a carbonized intermediate is 0.5-2nm, the mesopore diameter is 2-50nm, the macropore diameter is 50nm-200 mu m, and the specific surface area is 500-3000m 2 /g after carbonization activation.
  7. 7. The directional preparation process of the supercapacitor composite electrode porous structure according to claim 1, wherein in the step S5, the transition metal salt is selected from one or more of cobalt salt, nickel salt, iron salt, molybdenum salt, tungsten salt and manganese salt, the concentration in the precursor solution is 0.01-1mol/L, the chalcogen source is selected from one or more of thiourea, thioacetamide, selenium powder, selenocysteine, tellurium powder and sodium telluride, the molar ratio of the chalcogen source to the transition metal salt is 1-10:1, the precursor solution further comprises a structure regulator, the structure regulator is selected from one or more of hexamethylenetetramine, urea, ammonium fluoride and oxalic acid, the concentration is 0.05-2mol/L, and the transition metal chalcogen compound is nano-sheet, nano-flower or nano-wire after the hydrothermal reaction.
  8. 8. The directional preparation process of the supercapacitor composite electrode porous structure according to claim 1, wherein in the step S6, the plasma surface modification treatment comprises the steps of adopting oxygen plasma to treat for 10-300S, adopting radio frequency power for 50-300W and adopting oxygen flow for 10-100sccm, or adopting nitrogen plasma to treat for 10-300S, adopting radio frequency power for 50-300W and adopting nitrogen flow for 10-100sccm, wherein the oxygen content of the treated surface is 5-20at% and the nitrogen content is 2-15at%.
  9. 9. The directional preparation process of the supercapacitor composite electrode porous structure according to claim 1, wherein in the step S6, the chemical vapor deposition treatment comprises placing the heterojunction composite structure in a reaction chamber, introducing a mixed gas of carbon source gas and hydrogen, wherein the carbon source gas is one or more of methane, ethylene, acetylene and benzene, the flow rate is 5-100sccm, the hydrogen flow rate is 50-500sccm, and the deposition is carried out for 5-60min at 800-1100 ℃.
  10. 10. The directional preparation process of the supercapacitor composite electrode porous structure according to claim 1, wherein the prepared porous structure has the performance parameters of 70-95% of directional pore canal orientation degree, 5-100 μm of pore canal diameter, 0.5-10mm of pore canal length, 800-2500m 2 /g of specific surface area, 0.5-3.0cm 3 /g of pore volume, 300-800F/g of specific capacitance under the current density of 1A/g and 70-95% of capacitance retention under the current density of 50A/g in a three-electrode system and 6MKOH electrolyte, and the capacitance retention is more than 90% after 10000 times of circulation under the current density of 10A/g.

Description

Directional preparation process of porous structure of composite electrode of supercapacitor Technical Field The invention relates to the technical field of super capacitors, in particular to a directional preparation process of a porous structure of a composite electrode of a super capacitor. Background The super capacitor is used as a novel energy storage device, and has wide application prospect in the fields of new energy automobiles, smart grids, portable electronic equipment and the like by virtue of the advantages of high charge and discharge rate, long cycle life, environmental friendliness and the like. The electrode material is used as a core component of the supercapacitor, the structural design of the electrode material directly determines the capacitance performance, the ion transmission efficiency and the cycling stability, and the development of the electrode material with high specific surface area, reasonable pore structure and excellent conductivity becomes the core direction of industry research. At present, development of electrode materials of super capacitors has advanced to some extent, but still faces a plurality of technical bottlenecks. Firstly, the design of a pore structure is unreasonable, most of traditional electrode materials are of random porous structures, and a pore channel system which is arranged in a directional mode is lacked, so that an ion transmission path is tortuous, diffusion resistance is high, capacitance attenuation is serious under high current density, and high-power energy storage requirements are difficult to meet. Meanwhile, the single pore size cannot give consideration to ion storage and transmission efficiency, the specific surface area of the micropore-rich material is high, but the ion diffusion is slow, the ion transmission speed of the macroporous material is fast, but the storage capacity is limited, and the collaborative design of the hierarchical pore structure still needs to be optimized. Second, the conductivity and structural stability of the electrode material are difficult to balance. In the process of compounding conductive components such as MXene, carbon materials and the like with energy storage components such as metal organic frames, transition metal compounds and the like, the phenomenon of agglomeration is easy to occur due to poor interface compatibility, electron transmission is blocked, and in the long-term charge and discharge cycle of a composite structure, capacitance attenuation is easy to occur due to volume expansion and structural collapse, and the cycle stability is insufficient. In addition, most composite electrode materials have poor surface hydrophilicity and poor electrolyte wettability, so that ion migration rate is further restricted, and the performance of capacitance is affected. Furthermore, the existing preparation process has obvious limitations. The traditional porous material preparation methods such as a template method, a foaming method and the like are difficult to accurately regulate and control the directionality and the size distribution of the pore canal, have complex process and higher cost, and are not beneficial to large-scale production. The directional pore canal preparation technology, such as an ice template method, can realize the directional arrangement of pore canals, but is easy to collapse pore structures in the processes of freezing rate control and ice crystal sublimation, so that the porosity and structural integrity of the material are reduced, and meanwhile, the subsequent carbonization, activation and composite modification processes lack collaborative design, so that synchronous optimization of pore structures, electrical conductivity and energy storage performance is difficult to realize. Finally, the overall performance of the electrode material is to be improved. The existing product has the problems of low specific capacitance, insufficient high-rate performance, short cycle life and the like, and is difficult to meet the dual requirements of high-end energy storage scenes on the energy density and the power density of the device. Therefore, a preparation process capable of precisely constructing a directional hierarchical porous structure, optimizing combination of component interfaces and improving conductivity and stability is developed, breakthrough of the comprehensive performance of the electrode material of the supercapacitor is realized, and the preparation process becomes a technical problem to be solved urgently in the current industry and has important significance in promoting industrialized application of the supercapacitor. Disclosure of Invention The invention provides a directional preparation process of a porous structure of a supercapacitor composite electrode, which aims to solve the problems in the prior art. In order to achieve the purpose, the invention adopts the following technical scheme that the directional preparation process of the porous structure of