CN111924843A

CN111924843A - Method for modifying biomass-derived carbon by cyanide and application of method in potassium storage field

Info

Publication number: CN111924843A
Application number: CN202010835166.0A
Authority: CN
Inventors: 柳伟; 高翔; 周峻安
Original assignee: Ocean University of China
Current assignee: Ocean University of China
Priority date: 2020-08-19
Filing date: 2020-08-19
Publication date: 2020-11-13
Anticipated expiration: 2040-08-19
Also published as: CN111924843B

Abstract

The invention provides a method for preparing a cyanide modified porous carbon material by taking marine biological waste artemia shells as raw materials and using the synergistic effect of KOH, phytic acid and metal cobalt salt thereof, and the method is applied to potassium ion capacitors and potassium ion batteries. The method comprises the steps of adding ball-milled artemia shells into phytic acid, fully soaking and uniformly stirring the ball-milled artemia shells, then adding cobalt acetate, forming a cross-linked network with the artemia shells and the phytic acid due to the complexation of amino groups of proteins in biomass and phosphate groups of the phytic acid, finally carrying out freeze drying treatment, carrying out KOH activation and high-temperature carbonization on a freeze-dried sample at 800 ℃, and then cleaning the sample to prepare the three-dimensional porous cyanide modified carbon nano material.

Description

Method for modifying biomass-derived carbon by cyanide and application of method in potassium storage field

Technical Field

The invention belongs to the field of electrochemical energy storage devices, and provides a cyanide modified porous carbon material prepared from biological waste artemia shells serving as raw materials by using the synergistic effect of KOH, phytic acid and metal salts, and application of the cyanide modified porous carbon material in a potassium ion battery and a potassium ion hybrid capacitor.

Background

Today's demand for new energy technology breakthrough in society is becoming more and more intense, especially for large stationary energy applications, which also require energy materials with more abundant reserves and lower costs. Nowadays, for commercialization of lithium ion batteries, there is a contradiction that the demand for lithium batteries for electronic devices and electric vehicles in the future is further enhanced in response to the increase in price and shortage of lithium, and uneven distribution of lithium production places. These contradictions lay the foundation for the deep research of the technology (such as sodium ion batteries and potassium ion batteries) for finding alternatives and continuously supplying batteries. In contrast, the abundance of sodium (23000 ppm) and the abundance of potassium (17000 ppm) in the earth are quite sufficient, and potassium ion batteries and sodium ion batteries possess similar electrochemical reaction mechanisms as lithium ion batteries, similar redox potentials, and both potassium ion batteries and sodium ion batteries are promising candidates from the viewpoint of finding alternative batteries for large-scale energy storage of lithium ion batteries.

One significant advantage of potassium ion batteries over lithium ion batteries and sodium ion batteries is that potassium ions have a relatively weak lewis acidity and have a smaller solvation structure than lithium and sodium ions from the point of view of acid-base soft-hard binding. Therefore, the conductivity of potassium ions in the electrolyte is far greater than that of lithium ions and sodium ions, and meanwhile, the desolvation barrier of the potassium ions is much smaller, so that the potassium ions can diffuse in the SEI film more quickly. In addition, for most negative electrode materials, the intercalation potential of potassium ions is relative to K⁺K is approximately equal to 0.2V, while a hard carbon negative electrode is in a sodium ion battery with respect to Na⁺the/Na is approximately equal to 0.05V, resulting in a low possibility of metal deposition during oxidation of the negative electrode, so that the potassium ion battery is also superior to the sodium ion battery in safety. Another advantage is that potassium does not alloy when in contact with an aluminum plate at lower voltages, which can be achieved by using an Al current collector for the negative electrodeReplacing Cu saves the cost of the battery. However, this technology is still in a development stage, and thus various scientific and engineering improvements are required. For example, potassium ions that are frequently intercalated/deintercalated during charge/discharge possess large ionic radii, which may cause damage to the positive electrode material, resulting in low battery capacity, poor rate capability, poor cyclability, and sometimes even no electrochemical activity. Another significant disadvantage is that the active material is relatively heavy, resulting in a relatively low energy density performance. Therefore, these problems require the design and development of an electrode material suitable for a potassium ion battery.

This patent is based on ocean crustacean's unique structure to ocean abandonment living beings artemia shell is as the raw materials, utilizes freeze-drying, and the regulation and control of living beings derived carbon material realization interlamellar spacing and surface functional group and defect are regulated and control to high temperature chemical activation technique. The three-dimensional hierarchical porous carbon material modified by cyanide is obtained, has a long-range disordered short-range ordered structure, and can obtain excellent electrochemical performance in a potassium ion battery and a potassium ion capacitor.

Disclosure of Invention

The invention aims to provide a method for preparing a cyanide modified hierarchical porous carbon material by taking artemia shells as a raw material and applying the carbon material to a potassium ion battery through freeze drying pretreatment and chemical high-temperature activation. And the material is applied to the cathode material of the potassium ion battery to assemble the potassium ion battery energy storage device. In order to solve the technical problem, the technical scheme adopted by the invention is as follows:

firstly, soaking the ball-milled artemia shells in phytic acid solution, stirring for 30min, and then adding cobalt acetate to carry out a crosslinking reaction. After freeze drying, the hierarchical porous carbon material is obtained through the synthesis steps of high-temperature carbonization-chemical activation pickling and the like. And mixing the obtained carbon negative electrode material, conductive acetylene black and a binder according to the ratio of 8:1:1, and coating the mixture on an Al sheet to prepare the negative electrode sheet of the battery. And assembling the negative plate and the potassium block into a potassium ion battery in a glove box filled with argon, and testing the cycle performance and the rate performance of the potassium ion battery in a blue-electricity system.

Compared with the prior art, the invention has the beneficial effects that:

(1) the invention utilizes the marine organism crustacean biological waste as a raw material to prepare the hierarchical porous carbon material, has low price and rich resources, and provides a solution for solving the problem of marine pollution caused by excessive pollution of the biological waste. The waste crustacean organisms are recycled, the utilization degree of the biological waste is greatly improved, and the operation cost is low. Meanwhile, the porous carbon obtained after activation has a stable hierarchical three-dimensional network, a pore structure uniformly distributed and a specific surface beneficial to ion adsorption, and the defect regulation and the cyanide modification in the carbon material endow the material with different potassium storage performance. By combining the advantages, when the biologically-derived carbon material is applied to a battery material, the porous structure of the biologically-derived carbon material is beneficial to rapid infiltration of electrolyte, rapid diffusion of ions and construction of a high conductive network, and plays an essential important role in obtaining excellent potassium ion storage capacity.

(2) According to the invention, the crustacean biomass is pretreated by adopting phytic acid surface complexation, phosphate radicals in the phytic acid and amino groups in chitin and protein are crosslinked, and cobalt ions are further introduced to be continuously complexed with the rest of the phosphate radicals, so that a large number of three-dimensional network structures of artemia shells for adsorbing the cobalt ions are obtained. The method introduces a large amount of cobalt ions, influences the graphitization degree of carbon, enables disordered hard carbon to still maintain a carbon material with partially existing nano graphite domains but overall disordered after being activated, and introduces KOH activation later, so that the biological derived carbon has large specific surface area, developed porosity and abundant nitrogen and oxygen doping, and the prepared cyanide modified carbon material has a plurality of ion adsorption active sites, so that the cyanide modified carbon material has extraordinary adsorption capacity performance and metal ion intercalation performance caused by the improvement of the graphitization degree, and also generates a plurality of unsaturated alkynyl groups while cyanide is generated, and the synergistic effect of the material characteristics is combined to enable the carbon material to have excellent performance in a potassium ion battery.

(3) The crustacean biologically-derived carbon improved by the technology has excellent potassium ion storage capacity, the preparation process is simple, no pollution is caused to the environment basically, the industrial production is expected to be realized under the situation of urgent need of large-scale production of alkali metal batteries, and then the excellent energy-power density and the overlong circulation stability performance are displayed in the formed potassium ion battery, so that the crustacean biologically-derived carbon has a certain development prospect on how to relieve the problem of current energy supply tension.

Drawings

Fig. 1 is a Scanning Electron Microscope (SEM) photograph of the graded porous carbon material obtained in example 1.

Fig. 2 is a Scanning Electron Microscope (SEM) photograph of the hierarchical porous carbon material obtained in example 2.

Fig. 3 is a Scanning Electron Microscope (SEM) photograph of the hierarchical porous carbon material obtained in example 3.

FIG. 4 is an infrared spectroscopy test of the porous carbon nanomaterial prepared in example 1 of the present invention.

Fig. 5 shows the rate capability of the half-cell when the porous carbon nanomaterial prepared in embodiment 1 of the present invention is used as an anode material of a potassium ion cell.

Fig. 6 shows the large current cycling performance of the half-cell when the porous carbon nanomaterial prepared in example 1 of the present invention is used as the anode material of the potassium ion cell.

Fig. 7 shows the charge and discharge performance of the porous carbon nanomaterial prepared in example 1 of the present invention as a potassium ion capacitor.

Detailed Description

The invention will now be described with reference to the following specific examples, but is not limited to the examples.

Example 1

Collecting artemia shells from seawater, weighing 0.5 g of artemia shells, putting the artemia shells into 35ml of 1mol/L phytic acid aqueous solution, stirring for 30min to enable surface functional groups of biomass to fully perform a complexing reaction with phosphate radicals of phytic acid, adding 0.05M of 5ml of cobalt acetate aqueous solution, then stirring for 30min, and performing freeze drying for 72h after full reaction. And putting the freeze-dried product and 1 g of potassium hydroxide into a mortar for grinding for 10 min to ensure that the artemia shell freeze-dried product and KOH powder are uniformly mixed. Finally, the mixture was placed in a graphite crucible under argon as an inert gasIn a tubular heating furnace for a natural gas at 3 ℃ for min^-1The temperature is raised to 900 ℃ at the temperature raising rate, and the temperature is kept for 3 hours for calcination and activation. And naturally cooling to room temperature, and taking out the calcined sample. With 1 mol. L^-1And removing impurities from metal impurities in the product by using a hydrochloric acid solution, cleaning the product for three times by using ethanol and deionized water, finally cleaning the product to be neutral, collecting the product, and drying the water in a drying oven at 60 ℃ to obtain a black powder product.

Example 2

The process of this example is essentially the same as example 1, except that cobalt acetate is replaced with ammonium molybdate which has relatively weak catalytic graphitization ability, and as can be seen from the SEM of FIG. 2, the final product produces much molybdenum carbide which is insoluble in hydrochloric acid, but the porous network structure of biochar is still well developed.

Example 3

The method of this example does not adopt the KOH activation treatment in example 1, but selects Zncl₂The activation treatment, followed by the treatment was the same as in example 2. As can be seen from the SEM of fig. 3, with the replacement of the activator, the resulting pore structure is less abundant than before, and the carbon network is also less developed than the network of KOH activated crosslinks.

Application example 1

Uniformly mixing the porous carbon material obtained after calcination and activation treatment, conductive acetylene black (Super P) and a binder (polyvinylidene fluoride) in a mass ratio of 8:1:1, dispersing the prepared slurry and carbon powder by using a 1-methyl-2-pyrrolidone (NMP) solution to obtain a black viscous liquid, and finally coating the black viscous liquid on an aluminum foil to prepare the electrode plate. Assembling in a glove box filled with argon, and assembling into a potassium ion half-cell by using a porous carbon negative electrode material and a potassium block, wherein the electrolyte used is 0.8 mol.L^-1KPF of₆Dissolved in EC/DEC electrolyte. Finally, the electrochemical performance was tested in a blue work station. The results are shown in FIGS. 4 to 5.

From the infrared of fig. 4, it can be seen that the porous carbon has cyanide and alkynyl groups, represents a rich defect structure and rich surface functional groups, and has extremely excellent adsorption ability for potassium ions, from the viewpoint of half of fig. 5The battery rate performance can be verified at 0.1A g^-1Has a small current density of 350 mAh g^-1High reversible capacity of (2), even at a high current density of 10A g^-1Can also have 100 mAh g at the current density of^-1And at 2A g^-1Can maintain 230 mAh g in 3000 cycles under the high current density^-1High reversible capacity and long cycle life.

Application example 2

Uniformly mixing the porous carbon material obtained after calcination and activation treatment, conductive acetylene black (Super P) and a binder (polyvinylidene fluoride) according to the mass ratio of 7:1.5:1.5, dispersing the prepared slurry and carbon powder by using a 1-methyl-2-pyrrolidone (NMP) solution to obtain black viscous liquid, and finally coating the black viscous liquid on an aluminum foil to prepare the electrode plate. The method comprises the following steps of performing assembly operation in a glove box filled with argon, assembling a potassium ion half-cell by using a porous carbon negative electrode material and a potassium block, then performing pre-embedding of potassium by using a blue electric work station, taking an electrode plate embedded with potassium in advance as a negative electrode, taking a porous carbon electrode plate without pre-embedding activation as a positive electrode, wherein the mass ratio of the positive active material to the negative active material is 1: 0.5 assembling potassium ion capacitors, electrochemical performance testing was performed on the capacitors using the chenghua 660E electrochemical workstation, and the test results are shown in fig. 7.

As can be seen from fig. 7, the cyclic voltammetry curve of the potassium ion capacitor is similar to a rectangle, which illustrates that the potassium ion capacitor assembled by the electrode sheet obtained in example 1 mainly exhibits surface-controlled electric double layer capacitance, and the constant current charging and discharging curve of the potassium ion capacitor is substantially triangular, and at the same time, can perform long-time discharging, which illustrates that the device has high energy density while having high power density. As can be seen from fig. 7, the potassium ion capacitor assembled by the electrode sheet of example 2 was at 2A g according to the constant current charge and discharge test^-1Can reach 107.6F g at current density^-1When the current density increased to 10A g^-1While the capacitor still has 46.3F g^-1The cyanide modified porous carbon is proved to have better rate capability. As can be seen from fig. 7, the electrode sheet of example 1 has very high rate capability and excellent rate capabilityCapacity, which satisfies both the demand for high energy density and high power density devices.

Claims

1. The application of the method for preparing the porous carbon nano material by taking artemia cysts as a raw material and activating the artemia cysts with KOH and phytic acid in the field of potassium storage is characterized by comprising the following steps:

(a) screening of biomass precursors: the marine biomass has good hydrophilicity and is beneficial to processing treatment; artemia, an important bait in fish farming, is a representative species in most high-salt regions in life, consumes about 1.8 million tons of artemia for various prawn or fish feeds worldwide each year, but the capsule shell is always treated as waste, and is considered as an ideal precursor for designing nano materials due to a large amount of chitin and protein contained in the capsule shell; (b) pretreatment: cleaning artemia shell with distilled water, drying at 80 deg.C for 24 hr, ball milling at 300rpm for 6 hr, and adding 67wt% HNO₃Performing medium ultrasonic treatment for 80min, and cleaning and drying to obtain a final product; (c) mixing: self-assembling a certain amount of artemia cysts and cobalt phytate acetate in an aqueous solution, and performing freeze drying treatment after the self-assembly is completed to obtain a green flaky substance; (d) carbonizing: grinding and mixing the green flaky substance and KOH according to a certain proportion, putting the mixture into a corundum porcelain boat, introducing argon-hydrogen mixed gas into a tubular furnace for carbonization, taking out a sample after the temperature is reduced to room temperature, washing the sample with dilute hydrochloric acid solution, washing the sample with deionized water to be neutral, and drying the washed sample to obtain black powder.

2. The method for producing a biomass carbon material according to claim 1, characterized in that: in the step a, the artemia shell biomass is rich in reserves, low in utilization rate at present, has a three-dimensional hierarchical porous structure, can obtain a honeycomb carbon structure with rich pores after activation treatment, and the obtained carbon material contains rich elements for doping because the crustacean biomass contains a large amount of protein and chitosan, can reduce the binding energy with potassium ions, and can realize higher rate performance by improving the wettability with electrolyte.

3. The method for producing a biomass-derived carbon material according to claim 1, wherein: in the step b, 0.5 g of ball-milled artemia shells are taken, 35mL of artemia shells with the concentration of 1 mol.L are measured^-1Mixing and stirring the phytic acid aqueous solution in a beaker for 30min to ensure that Van der Waals bonding between organic macromolecular functional groups on the surface of artemia cysts and phosphate radicals of phytic acid is sufficient, further mixing and adding 5ml of 0.05M cobalt acetate aqueous solution to ensure that the phosphate radicals are complexed with cobalt ions, stirring for 30min, fully reacting, and freeze-drying for 72 h.

4. The method for producing a biocarbon material as claimed in claim 1, wherein: in the step c, the carbonizing-activating temperature of the artemia shell subjected to freeze drying is 900 ℃, the heating rate is 3 ℃/min, the constant temperature time is 1-3h, and 1 mol.L of the cooled sample is used^-1Washing with hydrochloric acid for 2h, and then washing with water and ethanol to neutrality.

5. The method for regulating the morphology and doping of artemia shell biochar as recited in claims 1-4, wherein: the artemia shell biomass has a rich pore structure and contains a large amount of chitosan chitin and protein, phytic acid is fully infiltrated into artemia shells through electrostatic combination of surface functional groups and phytic acid phosphate radicals, cobalt ions are further introduced to complex the cobalt ions with the phytic acid, electrostatic self-assembly is realized, after KOH is activated, simple substance cobalt and KOH perform cutting modification on carbon, and cyanide modification can be realized, so that the artemia shell biomass can obtain an N, O element doping with a large specific surface area and a hierarchical porous structure, a cobalt-catalyzed graphitizing region is combined with a disorderly region caused by element doping, and the artemia shell biomass can be used as an electrode material of a potassium ion battery and a potassium ion capacitor and shows excellent potassium storage performance.