CN114530601A - Preparation method of boron-doped porous carbon material and application of boron-doped porous carbon material in potassium ion battery - Google Patents

Preparation method of boron-doped porous carbon material and application of boron-doped porous carbon material in potassium ion battery Download PDF

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CN114530601A
CN114530601A CN202111648413.7A CN202111648413A CN114530601A CN 114530601 A CN114530601 A CN 114530601A CN 202111648413 A CN202111648413 A CN 202111648413A CN 114530601 A CN114530601 A CN 114530601A
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boron
carbon material
porous carbon
doped porous
ion battery
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蒋岚
卢宪露
刘乔
李侃
杨为佑
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Ningbo University of Technology
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/054—Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Abstract

The invention belongs to the technical field of energy storage materials, and particularly relates to a preparation method of a boron-doped porous carbon material and application of the boron-doped porous carbon material in a potassium ion battery. The boron-doped porous carbon material with a rich pore structure is prepared by using water-soluble organic acid as a carbon source compound and combining a pore-forming agent for boron doping and performing freeze drying and high-temperature calcination.

Description

Preparation method of boron-doped porous carbon material and application of boron-doped porous carbon material in potassium ion battery
Technical Field
The invention belongs to the technical field of energy storage materials, and particularly relates to a preparation method of a boron-doped porous carbon material and application of the boron-doped porous carbon material in a potassium ion battery.
Background
In recent years, the widespread application of lithium ion batteries in electronic devices and electric vehicles accelerates the consumption of lithium resources, and in the face of the decreasing lithium reserves, other materials are required to replace or partially replace the application of lithium in battery materials so as to meet the increasing demands of electric automobiles and energy storage systems. The sodium element and the potassium element in the same main group with the lithium element have the same chemical properties as the lithium element, and the working principle of the lithium ion battery is basically consistent with that of the lithium ion battery, so that the attention of researchers is attracted.
Sodium element has abundant reserves, but the radius of sodium ions is larger, and the sodium ions have higher oxidation-reduction potential, so that the sodium ions are difficult to be embedded into negative electrode materials such as graphite, and the commercial application is difficult to realize. Compared with sodium element, potassium has lower oxidation-reduction potential, can be embedded into graphite and has the theoretical specific capacity of 273 mAh/g. The potassium ion battery has the following advantages: (1) compared with a lithium ion battery, the lithium ion battery has rich reserves and lower cost; (2) the Lewis acid of the potassium ions is weak, smaller solvated ions can be formed, and the lithium ion battery has higher ion mobility and ion conductivity than the lithium ions and the sodium ions, and is favorable for improving the power characteristic of the potassium ion battery; (3) aluminum foil can be used as a negative current collector in the full cell instead of copper foil, so that the production cost is reduced.
However, the radius of potassium ion (0.138nm) is larger than that of sodium ion (0.102nm) and lithium ion (0.076nm), so that the rapid intercalation/deintercalation in the carbon material is difficult to realize, and simultaneously, huge volume change is easily caused in the charging and discharging process, so that the structure of an active substance is damaged, the capacity of a battery is rapidly reduced, the service life and the cycling stability are poor, and adverse effects are brought to the electrochemical performance. At present, the exploration of high-performance potassium ion batteries still depends on the reasonable design of a negative electrode material, and carbon materials in various forms are popular due to the advantages of low cost, no toxicity, no harm and the like.
Chinese patent CN109742384A discloses a method for using biomass porous carbon as a potassium ion battery cathode, which comprises the steps of performing ball milling and mixing on a biomass raw material and specific salt particles, then performing high-temperature reaction in the air, and washing, separating and purifying to obtain a porous carbon material. The scanning electron microscope picture can see the pore structures which are uniformly distributed, but the high-temperature reaction is carried out in the air atmosphere, the formed carbon material can be partially oxidized into carbon dioxide to be consumed, so that the carbon yield is low, and the post-treatment process is complicated and tedious due to the use of acid washing and multiple separation and purification.
Chinese patent CN107275578A discloses a method for manufacturing a potassium ion battery cathode by using a nitrogen-doped porous carbon material, which comprises the steps of adding a carbon source compound into a nitrogen source solution, continuously stirring to obtain a white product, carrying out high-temperature reaction in an inert atmosphere after freeze drying, and carrying out separation and purification to obtain the nitrogen-doped porous carbon material. The pore structures which are uniformly distributed can be seen in a scanning electron microscope picture, but the post-treatment process involves multiple times of separation and purification and is complex and tedious.
Disclosure of Invention
The invention aims to solve the problem that the specific capacity and the cycling stability of a potassium ion battery are incompatible, provide a boron-doped porous carbon material as a potassium ion battery cathode material, and improve the cycling performance and the rate capability of the potassium ion battery.
The preparation method of the boron-doped porous carbon material comprises the following steps:
(1) dissolving a carbon source compound, a boron-containing compound and a pore-forming agent in water, and freeze-drying;
(2) and calcining the freeze-dried sample at high temperature in an inert atmosphere, cooling to room temperature, washing with water, filtering and drying to obtain the boron-doped porous carbon material.
In the preparation method of the boron-doped porous carbon material, after high-temperature calcination, the carbon source compound is carbonized, and the pore-forming agent is removed, so that a porous structure is formed.
Further, the carbon source compound is one or more of tartaric acid, oxalic acid, malic acid and citric acid, and citric acid is preferred.
Further, the boron-containing compound is one or more of boric acid, phenylboronic acid, boron oxide, sodium borohydride and sodium perborate, and boric acid is preferred.
Further, the pore-foaming agent is one or more of lithium chloride, sodium chloride and potassium chloride, and preferably sodium chloride.
Further, the molar ratio of the carbon source compound to the boron-containing compound to the pore-forming agent is 1: (1.5-1.8): (14-18), preferably 1: (1.7-1.8): (14-15). The carbon source compound and the pore-foaming agent are reasonable in proportion, so that the carbon source compound can be well coated on the pore-foaming agent template, and a uniform pore structure is formed. The proportion of the boron-containing compound is controlled, so that the proper boron doping amount can be obtained, and the electrochemical properties such as the specific capacity of the material and the like can be improved.
Further, the freeze drying temperature is-80 to-70 ℃, the high-temperature calcining temperature is 700 to 800 ℃, and the time is 2 to 4 hours.
Further, the inert atmosphere is one of argon, helium and nitrogen, and the purity is 99.99%.
The carbon source compound in the method is common water-soluble organic acid, and can be compounded with the pore-foaming agent in a molecular level relative to carbon sources such as glucose and the like to form a hierarchical porous structure, so that the volume change caused in the electrochemical reaction process can be relieved, and the structural stability and the ion transmission rate of the potassium ion battery can be improved. Boron doping can introduce a large number of active sites, so that the interlayer spacing is enlarged, the embedding and the separation of potassium ions are facilitated, the conductivity of the material is improved, the transmission of electrons and ions in the charge-discharge reaction process is accelerated, and the multiplying power performance of the material is improved. Meanwhile, a water-soluble pore-forming agent is selected, firstly, the water-soluble pore-forming agent is melted and flows at high temperature, so that a communicated structure is formed in the material, and the material is washed and removed after high-temperature calcination, so that a communicated porous structure is finally formed, the ion transmission rate is further improved, the volume change caused by the electrochemical reaction process is relieved, and the electrochemical performance of the material is improved.
The potassium ion battery provided by the invention comprises a counter electrode, a negative electrode, a diaphragm and electrolyte, wherein the counter electrode is metal potassium, and the negative electrode comprises the boron-doped porous carbon material prepared by the preparation method.
The porous structure of the boron-doped porous carbon material can relieve volume change caused by an electrochemical reaction process, the stability of the battery is improved, a large number of active sites can be introduced by boron doping, the interlayer spacing is enlarged, the specific capacity of the material is improved, the rapid de-intercalation of potassium ions is facilitated, the conductivity of the material is improved by the boron doping, and the transport of electrons and ions is promoted. The boron-doped porous carbon material is used as the negative electrode material of the potassium ion battery, so that the specific capacity and other electrochemical performance parameters of the potassium ion battery are improved, and the good cycling stability of the battery is kept.
The invention provides a preparation method of a potassium ion battery, which comprises the following steps:
(1) cutting the metal potassium to be used as a counter electrode;
(2) dissolving a boron-doped porous carbon material, a conductive material and a binder in a mixed solution of water and ethanol, mixing the materials into uniform slurry, coating the slurry on a current collector, drying the slurry, and preparing a negative pole piece by using a punching machine;
(3) and assembling the negative electrode cover, the counter electrode, the diaphragm, the electrolyte, the negative electrode plate, the elastic sheet and the positive electrode cover in an inert atmosphere glove box to prepare the potassium ion battery.
Further, the mass ratio of the boron-doped porous carbon material, the conductive material and the binder in the step (2) is (80-90): (5-10): (5-10).
Further, the mass ratio of water to ethanol in the mixture of water and ethanol in the step (2) is (3-5): 1, the mass ratio of a mixed solution of water and ethanol to the boron-doped porous carbon material is (8-12): 1.
for slurry formed by dissolving the boron-doped porous carbon material in water and ethanol, if the concentration of the slurry is too low, the fluidity is high, the slurry is difficult to be coated on a current collector in a fixed form, and if the concentration of the slurry is too high, the viscosity is high, the fluidity is low, and the slurry is difficult to be uniformly coated on the current collector.
Further, the load capacity of the boron-doped porous carbon material on the negative electrode plate in the step (2) is 0.85-1.8 mg/cm2。
The specific capacity of the battery is smaller when the loading capacity of the negative pole piece is lower, but with the increase of the loading capacity, the thickness of the electrode is thickened, the diffusion rate of ions is slowed, the rate capability is lowered, and the electrode material is broken due to larger volume change in the electrochemical reaction process, so that the capacity of the battery is attenuated.
The conductive material in the step (2) is not particularly limited, and may be one or more of common conductive materials in a potassium ion battery, such as acetylene black, conductive carbon black, graphene, carbon nanotubes and carbon fibers.
Further, the binder in the step (2) is one or more of polyvinylidene fluoride, polytetrafluoroethylene, styrene butadiene rubber, sodium carboxymethylcellulose, polyvinyl alcohol and fluorinated rubber, and preferably sodium carboxymethylcellulose.
Further, the current collector in the step (2) is one of an aluminum foil and a copper foil.
Further, the diaphragm in the step (3) is a cellulose paper diaphragm.
Further, the electrolyte in the step (3) is a solution formed by dissolving potassium bis (fluorosulfonyl) imide (KFSI) in ethylene glycol dimethyl ether (DME), and the concentration is 2-4 mol/L. According to the invention, a glycol dimethyl ether (DME) solution of potassium bis (fluorosulfonyl) imide (KFSI) with the concentration of 2-4 mol/L is selected as an electrolyte, so that the transmission of metal cations is facilitated, and a uniform solid electrolyte interface film is formed in a proper concentration range, so that the performance of the potassium ion battery is improved. The DME solution containing 2-4 mol/L KFSI is prepared in a glove box, and specifically, 2-4 mol KFSI is dissolved in 1L ethylene glycol dimethyl ether and stirred uniformly.
Further, the step (3) is assembled in an inert atmosphere glove box to form the potassium ion battery, and the whole assembly process must be carried out in the glove box with water and oxygen content lower than 0.1ppm, because the electrolyte and the metal potassium are extremely sensitive to water and oxygen and have great influence on the performance of the battery.
Compared with the prior art, the technical scheme of the invention has the following beneficial effects:
(1) the carbon source compound is water-soluble organic acid, and can be combined with a pore-foaming agent in a molecular level relative to carbon sources such as glucose and the like to form a hierarchical porous structure, so that the volume change caused in the electrochemical reaction process is relieved, and the structural stability and the ion transmission rate of the potassium ion battery are improved;
(2) boron doping can introduce a large number of active sites, so that the interlayer spacing is enlarged, the embedding and the separation of potassium ions in the charge-discharge reaction process of the potassium ion battery are accelerated, and the multiplying power performance of the potassium ion battery is improved;
(3) the boron doping can accelerate the transmission of electrons and ions in the charge-discharge reaction process, improve the conductivity of the material and optimize the rate capability of the potassium ion battery;
(4) selecting a water-soluble pore-foaming agent, firstly melting and flowing at high temperature to form a communicated structure in the material, and removing the communicated structure by washing after high-temperature calcination to finally form a mutually communicated porous structure, thereby further improving the ion transmission rate, relieving the volume change in the charge-discharge process and improving the electrochemical performance of the material;
(5) the raw materials are common compounds, the preparation method is simple and efficient, no post-treatment is involved, and the method is suitable for industrial production and application.
Drawings
FIG. 1 is a scanning electron micrograph of a boron-doped porous carbon material obtained in example 1;
FIG. 2 is a transmission electron micrograph of the boron-doped porous carbon material obtained in example 1;
FIG. 3 is an X-ray photoelectron spectrum of the boron-doped porous carbon material obtained in example 1;
FIG. 4 is a Raman spectrum of the boron-doped porous carbon material obtained in example 1;
FIG. 5 is a test chart of specific surface area of the boron-doped porous carbon material obtained in example 1: (a) adsorption/desorption curves; (b) an aperture distribution map;
FIG. 6 is a graph showing the change of ion diffusion coefficient during the charge and discharge of the potassium ion battery obtained in example 1;
FIG. 7 shows the sweep rate of 0.2mVs in the potassium ion battery obtained in example 1-1A cyclic voltammetry curve (a) and a constant current charging and discharging curve (the current density is 100mA/g) (b);
FIG. 8 is a graph showing rate performance of the potassium ion battery obtained in example 1;
FIG. 9 is a graph showing cycle characteristics of the potassium ion battery obtained in example 1;
FIG. 10 is a graph showing rate performance of the potassium ion battery obtained in comparative example 1;
fig. 11 is a graph showing cycle performance of the potassium ion battery obtained in comparative example 1.
Detailed Description
The technical solutions of the present invention are further described and illustrated in the following specific embodiments and the accompanying drawings, it should be understood that the specific embodiments described herein are only for the purpose of facilitating understanding of the present invention, and are not intended to limit the present invention specifically. And the drawings used herein are for the purpose of illustrating the disclosure better and are not intended to limit the scope of the invention. The raw materials used in the examples of the present invention are those commonly used in the art, and the methods used in the examples are those conventional in the art, unless otherwise specified.
Example 1
The preparation method of the boron-doped porous carbon material comprises the following steps:
(1) mixing citric acid monohydrate, boric acid and sodium chloride in a ratio of 1: 1.5: 14 in a molar ratio of water so that the concentration of sodium chloride is 167g/L, and freeze-drying the obtained solution at-80 ℃;
(2) calcining the freeze-dried sample at 750 ℃ for 2h under the atmosphere of argon, and naturally cooling to room temperature; subsequently, the manufactured powder was washed with deionized water to remove excess sodium chloride from the product; and finally, carrying out vacuum filtration on the solution, and drying the filtered solid at 80 ℃ to obtain the boron-doped porous carbon material. .
The preparation method of the potassium ion battery of the embodiment is as follows:
(1) cutting the metal potassium to be used as a counter electrode;
(2) the boron-doped porous carbon material, acetylene black, sodium carboxymethylcellulose, water and ethanol are uniformly mixed according to the mass ratio of 8:1:1:64:14, then the mixture is coated on a copper foil, the copper foil is dried for 8 hours at 80 ℃, a punching machine is used for preparing a wafer with the diameter of 12mm and used as a negative pole piece, and the load capacity of the boron-doped porous carbon material on the copper foil is 1.2mg/cm2；
(3) Assembling the negative electrode cover, the counter electrode, the cellulose paper diaphragm, the electrolyte, the negative electrode plate, the elastic sheet and the positive electrode cover in sequence in an inert atmosphere glove box to prepare the 2032 type button potassium ion battery.
The electrolyte is ethylene glycol dimethyl ether (DME) solution of potassium bis (fluorosulfonyl) imide (KFSI), and the concentration of the solution is 3 mol/L.
Example 2
The difference between the embodiment 2 and the embodiment 1 is that the preparation method of the boron-doped porous carbon material is different, and the specific steps are as follows:
(1) mixing citric acid monohydrate, boric acid and sodium chloride in a ratio of 1: 1.8: 14 is dissolved in water, the concentration of sodium chloride is 167g/L, and the sodium chloride is frozen and dried at the temperature of minus 75 ℃;
(2) calcining the freeze-dried sample at 750 ℃ for 3h under the atmosphere of argon, and naturally cooling to room temperature; subsequently, the manufactured powder was washed with deionized water to remove excess sodium chloride from the product; and finally, carrying out vacuum filtration on the solution, and drying the filtered solid at 80 ℃ to obtain the boron-doped porous carbon material. .
Example 3
The difference between the embodiment 3 and the embodiment 1 lies in that the preparation method of the boron-doped porous carbon material is different, and the specific steps are as follows:
(1) mixing citric acid monohydrate, boric acid and sodium chloride in a ratio of 1: 1.5: dissolving 18 mol% of sodium chloride in water, wherein the concentration of sodium chloride is 167g/L, and freeze-drying at-70 ℃;
(2) calcining the freeze-dried sample at 800 ℃ for 2h under the argon atmosphere, and naturally cooling to room temperature; subsequently, the manufactured powder was washed with deionized water to remove excess sodium chloride from the product; and finally, carrying out vacuum filtration on the solution, and drying the filtered solid at 80 ℃ to obtain the boron-doped porous carbon material. .
Comparative example 1
Comparative example 1 differs from example 1 only in that no boric acid is added.
Comparative example 2
Comparative example 2 differs from example 1 only in that no sodium chloride was added.
FIG. 1 is a scanning electron micrograph of a boron-doped porous carbon material according to example 1, and FIG. 2 is a drawing of an embodimentExample 1 transmission electron microscopy of a boron-doped porous carbon material shows that the boron-doped porous carbon material has an ultrathin porous structure as shown in fig. 1 and 2(a), and shows that the prepared boron-doped porous carbon material is an amorphous carbon material as shown in fig. 2 (b). FIG. 3 is an X-ray photoelectron spectrum of the boron-doped porous carbon material of example 1, demonstrating the incorporation of boron into the porous carbon material. FIG. 4 is a Raman spectrum of the boron-doped porous carbon material of example 1, which shows that boron doping introduces a large number of active sites and has a high ID/IGFig. 5 is a graph (a) and a pore size distribution graph (b) of the boron-doped porous carbon material in example 1, further illustrating that the porous carbon has a rich void structure and is a mesoporous material, fig. 6 is a graph of a change in ion diffusion coefficient during charging and discharging of the potassium ion battery in example 1, and it can be seen that potassium ions have a higher diffusion coefficient, which illustrates that boron doping can improve the conductivity of the material and promote diffusion of the potassium ions, and fig. 7 is a graph of a sweep rate of the potassium ion battery in example 1 of 0.2mVs-1The cyclic voltammetry curve and the constant current charging and discharging curve (a) and the constant current charging and discharging curve (b) with the current density of 100mA/g can be seen to form good correspondence, the first charging and discharging curve is different because the first charging and discharging generates irreversible boundary reaction and generates stable solid electrolyte interface film, the later curves are basically overlapped to show that the battery has good cyclic stability, FIG. 8 is the multiplying power performance diagram of the potassium ion battery in example 1, and the specific capacity can be seen to be reduced from 440mAh/g when the current density is increased from 100mA/g to 1000mA/g, and the current density is recovered to 100mA/g, the specific capacity is increased to 440mAh/g again, thereby proving that the battery has good multiplying power performance, FIG. 9 is the cyclic performance diagram of the potassium ion battery in example 1, and shows the cyclic stability of the potassium ion battery under high current density, the battery can be stably circulated for 2000 circles, the reversible specific capacity is as high as 330mAh/g, the specific capacity retention rate is as high as 120%, and the coulomb efficiency in the circulation process is as high as 100%.
Fig. 10 is a graph of the rate capability of the potassium ion battery obtained in comparative example 1, and it can be seen that when the current density is changed from 100 to 1000mA/g, the specific capacity is changed from 280 to 140mAh/g, and the current density is restored to 100mA/g, the specific capacity is increased to 210mAh/g again, which proves that the potassium ion battery obtained in the comparative example has a lower specific capacity and a poorer rate capability, and fig. 11 is a graph of the cycle capability of the potassium ion battery obtained in comparative example 1, which shows that the cycle stability and the coulombic efficiency of the potassium ion battery under the high current density are higher, and the reversible specific capacity of the battery is only 150mAh/g after 2000 cycles, and the fluctuation of the specific capacity change in the cycle process is larger, which indicates that the cycle stability and the specific capacity of the potassium ion battery constructed by the porous carbon material in the comparative example are not ideal enough.
TABLE 1 data table of cycle performance and rate performance for examples and comparative examples
Figure BDA0003446007500000071
Figure BDA0003446007500000081
Table 1 shows that, compared with example 1, in example 2, after the amount of boron doping in the porous carbon material is increased, more active sites can be introduced, the interlayer spacing is enlarged, which is beneficial to accelerating the intercalation and deintercalation of potassium ions in the charge and discharge reaction process of the potassium ion battery, and at the same time, accelerating the transmission of electrons and ions in the charge and discharge reaction process, improving the conductivity and specific capacity of the material, and optimizing the rate capability of the potassium ion battery. In the embodiment 3, the content of the pore-forming agent is increased, the formed pore structure is more, the ion transmission rate is also accelerated, the volume change in the charge and discharge process can be relieved, and the rate capability and the cycle performance of the material are improved. Compared with the prior art, the method has the advantages that boron doping is not carried out in a comparative example 1, the formed porous carbon material is poor in conductivity, the rate capability is reduced, a pore-foaming agent is not added in the comparative example 2, the porosity of the material is reduced, the buffering effect on the volume in the charging and discharging process is reduced, the ion transmission rate is also slowed, and the cycle performance and the rate capability of the material are reduced. Therefore, the boron doping can accelerate the transmission of electrons and ions in the charge-discharge reaction process, the multiplying power performance of the material is effectively improved, the pore-forming agent forms a porous structure in the material, the ion transmission rate is further improved, the volume change in the charge-discharge process is relieved, and the electrochemical performance of the material is improved.
Finally, it should be noted that the specific examples described herein are merely illustrative of the spirit of the invention and do not limit the embodiments of the invention. Those skilled in the art may now make numerous modifications of, supplement, or substitute for the specific embodiments described, all of which are not necessary or desirable to describe herein. While the invention has been described with respect to specific embodiments, it will be appreciated that various changes and modifications may be made without departing from the spirit and scope of the invention, as defined by the appended claims.

Claims (10)

1. A preparation method of a boron-doped porous carbon material is characterized by comprising the following steps:
(1) dissolving a carbon source compound, a boron-containing compound and a pore-forming agent in water, and freeze-drying;
(2) and calcining the sample subjected to freeze drying at high temperature in an inert atmosphere, cooling to room temperature, washing with water, filtering and drying to obtain the boron-doped porous carbon material.
2. The method according to claim 1, wherein the carbon source compound is one or more of tartaric acid, oxalic acid, malic acid, and citric acid.
3. The method according to claim 1, wherein the boron-containing compound is one or more of boric acid, phenylboronic acid, boron oxide, sodium borohydride and sodium perborate.
4. The method according to claim 1, wherein the pore-forming agent is one or more of lithium chloride, sodium chloride and potassium chloride.
5. The method for preparing a boron-doped porous carbon material according to claim 1, wherein the molar ratio of the carbon source compound, the boron-containing compound and the porogen is 1: (1.5-1.8): (14-18).
6. The method for preparing the boron-doped porous carbon material as claimed in claim 1, wherein the temperature for freeze-drying in the step (1) is-80 to-70 ℃, the temperature for high-temperature calcination in the step (2) is 700 to 800 ℃, and the time is 2 to 4 hours.
7. A potassium ion battery comprising a counter electrode, a negative electrode, a separator and an electrolyte, wherein the negative electrode comprises the boron-doped porous carbon material prepared by the method for preparing a boron-doped porous carbon material according to any one of claims 1 to 6.
8. The method of claim 7, comprising the steps of:
(1) cutting the metal potassium to be used as a counter electrode;
(2) dissolving a boron-doped porous carbon material, a conductive material and a binder in a mixed solution of water and ethanol, mixing the materials into uniform slurry, coating the slurry on a current collector, drying the slurry, and preparing a negative pole piece by using a punching machine;
(3) and assembling the negative electrode cover, the counter electrode, the diaphragm, the electrolyte, the negative electrode plate, the elastic sheet and the positive electrode cover in an inert atmosphere glove box to prepare the potassium ion battery.
9. The method for preparing the potassium ion battery according to claim 8, wherein the mass ratio of the boron-doped porous carbon material, the conductive material and the binder in the step (2) is (80-90): (5-10): (5-10), the load capacity of the boron-doped porous carbon material on the negative electrode piece is 0.85-1.8 mg/cm2。
10. The method for preparing a potassium ion battery according to claim 8, wherein the electrolyte is a solution of potassium bis (fluorosulfonyl) imide dissolved in ethylene glycol dimethyl ether, and the concentration is 2-4 mol/L.
CN202111648413.7A 2021-12-30 2021-12-30 Preparation method of boron-doped porous carbon material and application of boron-doped porous carbon material in potassium ion battery Pending CN114530601A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115140734A (en) * 2022-06-22 2022-10-04 长江师范学院 Preparation method and application of heteroatom-doped biomass porous carbon material
CN116425154A (en) * 2023-03-28 2023-07-14 广东工业大学 Porous carbon material and preparation method and application thereof
CN116854070A (en) * 2023-06-21 2023-10-10 浙江大学 Preparation method of microporous-rich high-sulfur-doped porous carbon, product and application thereof

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115140734A (en) * 2022-06-22 2022-10-04 长江师范学院 Preparation method and application of heteroatom-doped biomass porous carbon material
CN116425154A (en) * 2023-03-28 2023-07-14 广东工业大学 Porous carbon material and preparation method and application thereof
CN116854070A (en) * 2023-06-21 2023-10-10 浙江大学 Preparation method of microporous-rich high-sulfur-doped porous carbon, product and application thereof

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