A modified phenolic resin-based hard carbon material and its preparation method and application

Abstract

The present invention discloses a modified phenolic resin-based hard carbon material and its preparation method and application, belonging to the technical field of phenolic resin-based hard carbon materials. The present invention creatively uses aldehyde-containing, oxygen-rich glucuronolactone to replace formaldehyde in traditional methods, and uses 1,2,4-pyrogallol containing three phenolic hydroxyl groups, two of which are in the ortho position, to replace phenol in traditional methods. The provided method is easy to prepare thermosetting phenolic resin, and has the advantages of low cost, non-toxicity and pollution-free. The prepared modified phenolic resin-based hard carbon material has a suitable specific surface area, abundant micropores and a larger graphitized interlayer spacing. The specific surface area of the modified phenolic resin-based hard carbon material is 451.51m 2 / g, and the micropore volume is 0.217cm 3 / g; the prepared modified phenolic resin-based hard carbon material is used as the negative electrode material of sodium ion battery, with an initial coulombic efficiency of 86.44%, a platform capacity of 232.8mAh / g at a current density of 0.05A / g, and a capacity retention rate of 83.71% after stable circulation for 1000 cycles with a coulombic efficiency of 99.97% at a current density of 1A / g.

Description

Technical Field

[0001] The present invention relates to the technical field of phenolic resin-based hard carbon materials, in particular to a modified phenolic resin-based hard carbon material and a preparation method and application thereof. Background Art

[0002] Phenolic resins have excellent high-temperature resistance, chemical resistance, and bonding strength, and are widely used. Due to their simple preparation process, high residual carbon rate, and easily regulated structure, they have long been considered high-quality carbon precursors. Thermoplastic phenolic resins (hydrogen-rich and oxygen-deficient) readily graphitize above 1000°C, forming soft carbon materials. However, thermosetting phenolic resins (oxygen-rich and hydrogen-deficient) are difficult to graphitize above 1000°C due to the large amount of oxygen present, forming hard carbon materials. These materials can be used as negative electrode materials for sodium-ion batteries.

[0003] Traditional phenolic resin is formed by the condensation of phenol and formaldehyde under the catalysis of acid or alkaline. However, phenol is expensive and is a Class 3 carcinogen announced by the World Health Organization's International Agency for Research on Cancer. Formaldehyde is a Class 1 carcinogen announced by the World Health Organization's International Agency for Research on Cancer. During the production process, they pose a great threat to human life, health and safety.

[0004] Sodium-ion batteries are considered to be an effective supplement to lithium-ion batteries because of their similar working principles. Hard carbon materials are considered to be the most promising sodium-ion battery negative electrode materials because of their good low-voltage platform and sodium storage capacity. However, there are still problems such as low specific capacity, low coulombic efficiency and poor cycle stability. Although some technologies have been used to improve these problems, they often cannot take all three into account. Summary of the Invention

[0005] The purpose of the present invention is to provide a modified phenolic resin-based hard carbon material and its preparation method and application, so as to solve the problems of high preparation cost of phenolic resin-based hard carbon materials, great threat to the life, health and safety of workers during the preparation process, and low specific capacity, low coulombic efficiency and poor cycle stability of the currently prepared phenolic resin-based hard carbon materials as battery negative electrode materials.

[0006] To achieve the above object, the present invention provides a method for preparing a modified phenolic resin-based hard carbon material, comprising the following steps:

[0007] S1. Introducing metal ions into phenolic aldehyde, adding a surfactant and 25% to 30% ammonia water to the solvent in sequence, mixing, adding 1,2,4-benzenetriol, and adding glucuronolactone after dissolving, stirring and reacting; adding metal ion salt to the solution after the reaction is completed, and continuing the reaction;

[0008] S2, preparing a modified phenolic resin-based material, placing the solution obtained after the reaction in step S1 into a polytetrafluoroethylene liner, moving it into a hydrothermal autoclave for reaction, and filtering, washing, and drying the product to obtain a modified phenolic resin-based material;

[0009] S3. Prepare a modified phenolic resin-based hard carbon material, transfer the prepared phenolic resin-based material to a corundum porcelain boat, and react in a high-temperature tube furnace under an argon atmosphere to obtain a modified phenolic resin-based hard carbon material.

[0010] Preferably, in step S1, the solvent is one or both of deionized water and ethanol, and the surfactant is one of polyethylene glycol and ethylene glycol.

[0011] Preferably, in step S1, the mass volume ratio of the solvent: surfactant: ammonia water: 1,2,4-benzenetriol: glucuronolactone: metal ion salt is 60 mL: 0.25 mL: 0-3 mL: 1.5 g: 3 g: 0.4 g.

[0012] Preferably, the metal ion salt in step S1 is one of zinc acetate, zinc chloride and zinc sulfate.

[0013] Preferably, in step S1, the metal ion salt is added and the mixture is stirred and reacted for 12 hours.

[0014] Preferably, the hydrothermal reaction conditions in step S2 are 180° C. and 24 hours.

[0015] Preferably, the reaction conditions in the argon atmosphere in step S3 are: heating to 900° C. at 5° C. / min, keeping warm for 1 hour, and then heating to 1300° C. at 2° C. / min and keeping warm for 3 hours.

[0016] A modified phenolic resin-based hard carbon material prepared by the method for preparing the modified phenolic resin-based hard carbon material as described above.

[0017] An application of the modified phenolic resin-based hard carbon material as described above in a sodium ion battery, wherein the modified phenolic resin-based hard carbon material serves as a negative electrode of the sodium ion battery.

[0018] Therefore, the present invention provides a modified phenolic resin-based hard carbon material and its preparation method and application, and its specific technical effects are as follows:

[0019] (1) The present invention creatively uses aldehyde-containing, oxygen-rich glucuronolactone to replace formaldehyde in traditional methods. The method provided by the present invention is easy to prepare thermosetting phenolic resin. Moreover, as a glucose metabolite, glucuronolactone has the advantages of low cost, non-toxicity and pollution-free.

[0020] (2) The present invention uses 1,2,4-pyrogallol, which contains three phenolic hydroxyl groups, two of which are in the ortho position, to replace the phenol in the traditional method, which is conducive to forming a coordination compound with metal ions and realizing ion doping. In addition, 1,2,4-pyrogallol is not one of the three types of carcinogens, which can reduce the harm to the human body during the production process;

[0021] (3) The modified phenolic resin-based hard carbon material prepared by the method provided by the present invention has a suitable specific surface area, abundant micropores and a larger graphitized interlayer spacing. The specific surface area of the modified phenolic resin-based hard carbon material is 451.51 m 2 / g, and the micropore volume is 0.217cm 3 / g;

[0022] (4) The modified phenolic resin-based hard carbon material prepared by the present invention is used as the negative electrode material of the sodium ion battery, which has an initial coulombic efficiency of 86.44%, a platform capacity of 232.8 mAh / g at a current density of 0.05 A / g, and a capacity retention rate of 83.71% after stable circulation for 1000 cycles with a coulombic efficiency of 99.97% at a current density of 1 A / g. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments of the present invention. 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 any creative labor.

[0024] Figure 1 FTIR graph of the phenolic resin synthesized in Example 1;

[0025] Figure 2 1 is the XPS graph of the phenolic resin synthesized in Example 1;

[0026] Figure 3 The TGA curves of the phenolic resins synthesized in Example 1, Comparative Example 1-1, and Comparative Example 1-2 are shown;

[0027] Figure 4 These are SEM images of the phenolic resin-based hard carbon materials prepared in Example 1 and Comparative Example 1-1; wherein parts a) and b) are SEM images of the phenolic resin-based hard carbon materials prepared in Comparative Example 1-1; parts c) and d) are SEM images of the phenolic resin-based hard carbon materials prepared in Example 1;

[0028] Figure 5 XRD patterns of phenolic resin-based hard carbon materials prepared in Example 1 and Comparative Example 1-1;

[0029] Figure 6 This is the GCD curve of the sodium ion battery prepared in Example 2 at a current density of 0.05 A / g;

[0030] Figure 7 This is a bar graph comparing the slope capacity and platform capacity of the first cycle charging curve of the sodium ion batteries prepared in Example 2 and Comparative Example 2-1 at a current density of 0.05 A / g;

[0031] Figure 8 The figure is a graph showing the cycle number-specific capacity / coulombic efficiency curve of the sodium ion batteries prepared in Example 2, Comparative Example 2-1 and Comparative Example 2-2 at a current density of 1 A / g. DETAILED DESCRIPTION

[0032] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.

[0033] In order to make the purpose, technical solutions and advantages of the present application clearer, more thorough and more complete, the technical solutions of the present invention are clearly and completely described below through the accompanying drawings and Examples. The following detailed description is an explanation of the embodiments and is intended to provide further details of the present invention. Unless otherwise specified, all technical terms used in the present invention have the same meaning as those generally understood by those skilled in the art to which the application belongs.

[0034] The instruments, equipment, reagents and materials used in the examples were obtained from commercial sources.

[0035] Example 1

[0036] A modified phenolic resin-based hard carbon material is prepared, and the specific steps are as follows:

[0037] (1) Add 0.25 mL of polyethylene glycol and 0.5 mL of 28% ammonia water to 60 mL of deionized water and stir to mix. Then add 1.5 g of 1,2,4-benzimidazole and dissolve it. Then add 3 g of glucuronolactone and stir at 50 °C for 2 h. After the time is up, add 0.4 g of zinc acetate and continue stirring for 12 h.

[0038] (2) The solution after stirring in step (1) was transferred to a 100 mL polytetrafluoroethylene liner, hydroheated at 180°C for 24 h, the hydrothermal product was filtered, washed with deionized water, and dried at 60°C for 24 h to obtain a phenolic resin-based material.

[0039] The Fourier transform infrared absorption spectrum (FTIR) of the obtained phenolic resin-based material is as follows: Figure 1 As shown in the figure, the results show that 1,2,4-benzenetriol is combined with glucuronolactone to successfully synthesize phenolic resin materials. The X-ray photoelectron spectroscopy (XPS) of the obtained phenolic resin-based materials is shown in the figure. Figure 2As shown, the results show that Zn was successfully introduced into the phenolic resin via Zn-O coordination.

[0040] (3) The obtained phenolic resin-based material was transferred to a corundum porcelain boat, and in a high-temperature tube furnace, the temperature was raised to 900°C at 5°C / min under an argon atmosphere, kept warm for 1 hour, and then raised to 1300°C at 2°C / min and kept warm for 3 hours to obtain a modified phenolic resin-based hard carbon material.

[0041] Comparative Example 1-1

[0042] A phenolic resin-based hard carbon material is prepared, and the specific steps are as follows:

[0043] (1) Add 0.25 mL of polyethylene glycol and 0.5 mL of 28% ammonia water to 60 mL of deionized water and stir to mix. Then add 1.5 g of 1,2,4-benzenetriol and dissolve it. Then add 3 g of glucuronolactone and stir at 50°C for 2 h.

[0044] (2) The solution after stirring in step (1) was transferred to a 100 mL polytetrafluoroethylene liner, hydroheated at 180°C for 24 h, the hydrothermal product was filtered, washed with deionized water, and dried at 60°C for 24 h to obtain a phenolic resin-based material.

[0045] (3) The obtained phenolic resin-based material was transferred to a corundum porcelain boat, and in a high-temperature tube furnace, the temperature was raised to 900°C at a rate of 5°C / min under an argon atmosphere, kept warm for 1 hour, and then raised to 1300°C at a rate of 2°C / min and kept warm for 3 hours to obtain a phenolic resin-based hard carbon material.

[0046] Comparative Example 1-2

[0047] A glucuronolactone-based hard carbon material is prepared in the following steps:

[0048] (1) Add 0.25 mL of polyethylene glycol and 0.5 mL of 28% ammonia water to 60 mL of deionized water and stir until evenly mixed. Then add 3 g of glucuronolactone and stir at 50°C for 2 h.

[0049] (2) The solution after stirring in step (1) was transferred to a 100 mL polytetrafluoroethylene liner, hydroheated at 180°C for 24 h, the hydrothermal product was filtered, washed with deionized water, and dried at 60°C for 24 h to obtain the glucuronide material.

[0050] (3) The obtained glucuronide material was transferred to a corundum porcelain boat, and in a high-temperature tube furnace, under an argon atmosphere, the temperature was raised to 900°C at a rate of 5°C / min and kept warm for 1 hour, and then the temperature was raised to 1300°C at a rate of 2°C / min and kept warm for 3 hours to obtain a glucuronide-based hard carbon material.

[0051] The materials (carbonized precursor materials) obtained in step (2) of Example 1, step (2) of Comparative Example 1-1 and step (2) of Comparative Example 1-2 were subjected to thermogravimetric analysis (TGA). The results are as follows: Figure 3 As shown, the results show that the carbon yield of Example 1 and Comparative Example 1-1 is improved, further indicating that glucuron-lactone and 1,2,4-benzenetriol undergo a polymerization reaction to form a phenolic resin material.

[0052] The scanning electron microscope (SEM) photos of the phenolic resin-based hard carbon material obtained in Example 1 and Comparative Example 1-1 are as follows: Figure 4 As shown, parts a) and b) are SEM images of the phenolic resin-based hard carbon material prepared in Comparative Example 1-1; parts c) and d) are SEM images of the phenolic resin-based hard carbon material prepared in Example 1. A comparison between parts a) and c) and between parts b) and d) shows that the Zn introduced by Zn-O coordination plays a pore-forming role during the carbonization process, increasing the porosity, increasing the specific surface area, and exposing more active sites.

[0053] The X-ray diffraction (XRD) analysis of the phenolic resin-based hard carbon materials obtained in Example 1 and Comparative Example 1-1 showed the following results: Figure 5 As shown, the phenolic resin-based hard carbon materials prepared in Example 1 and Comparative Example 1-1 both exhibit typical hard carbon characteristics. In comparison, the left shift of the broad peak position indicates that the Zn introduced by Zn-O coordination increases the interlayer spacing of graphitization during the carbonization process, which is conducive to better diffusion dynamics.

[0054] Example 2

[0055] The modified phenolic resin-based hard carbon material prepared in Example 1 was assembled into a sodium ion battery, and the energy storage potential and cycle stability tests were performed as follows: the modified phenolic resin-based hard carbon material prepared in Example 1 was used as the active material of the positive electrode, the sodium sheet was used as the negative electrode, the electrolyte was a 1MNaF6 diethylene glycol dimethyl ether (DIGLYME) solution, and the battery was assembled using a model 2032 button cell in an argon-protected glove box to obtain a sodium ion battery.

[0056] The prepared sodium ion battery was tested at a current density of 0.05 A / g, and its GCD curve was as follows: Figure 6 As shown in Figure 2, under the appropriate specific surface area, the modified phenolic resin as a negative electrode material for sodium ion batteries has an initial coulombic efficiency of 86.44%. The slope capacity and platform capacity comparison bar graph of the first cycle charging curve is shown in Figure 2. Figure 7 As shown, the cycle number-specific capacity / Coulombic efficiency curve at a current density of 1A / g is as follows Figure 8 shown.

[0057] Comparative Example 2-1

[0058] The phenolic resin-based hard carbon material prepared in Comparative Example 1-1 was used as the active material for the positive electrode, the sodium sheet was used as the negative electrode, and the electrolyte was a 1M NaF6 diethylene glycol dimethyl ether (DIGLYME) solution. The battery was assembled using a 2032 button cell in an argon-protected glove box. The battery was tested at a current density of 0.05 A / g. The slope capacity and plateau capacity comparison bar graph of the first cycle charging curve is shown in the figure below. Figure 7 As shown, the cycle number-specific capacity / Coulombic efficiency curve at a current density of 1A / g is as follows Figure 8 shown.

[0059] Depend on Figure 7 It can be seen that the phenolic resin-based hard carbon material prepared in Example 2 has a larger porosity due to the pore-forming effect, and has more sodium storage sites, which is conducive to generating more sodium storage capacity.

[0060] Comparative Example 2-2

[0061] The glucuronolactone-based hard carbon prepared in Comparative Example 1-2 was used as the active material for the positive electrode, the sodium sheet was used as the negative electrode, and the electrolyte was a 1M NaF6 diethylene glycol dimethyl ether (DIGLYME) solution. The battery was assembled using a model 2032 button cell in an argon-protected glove box. The test was conducted at a current density of 0.05 A / g. The cycle number-specific capacity / coulombic efficiency curve at a current density of 1 A / g is shown in FIG. Figure 8 shown.

[0062] Depend on Figure 8 From the comparison, it can be seen that at the current density of 1 A / g, the number of cycles of Example 2 and Comparative Example 2-1 can both reach 1000 cycles, while Comparative Example 2-2 has only close to 800 cycles, indicating that the phenolic resins synthesized in Example 2 and Comparative Example 2-1 have a stable cross-linked structure and are retained after forming hard carbon to form a stable carbon skeleton. At the same time, Example 2 has a higher cycle specific capacity after pore formation, and still has a specific capacity of 83.71% 232 mAh / g after 1000 cycles.

[0063] Therefore, the present invention creatively uses aldehyde-containing, oxygen-rich glucuronolactone to replace formaldehyde in the traditional method, and uses 1,2,4-benzenetriol containing three phenolic hydroxyl groups, two of which are in the ortho position, to replace phenol in the traditional method. The provided method is easy to prepare thermosetting phenolic resin, has the advantages of low cost, non-toxicity and pollution-free; the prepared modified phenolic resin-based hard carbon material has a suitable specific surface area, abundant micropores and a larger graphitized interlayer spacing. The specific surface area of the modified phenolic resin-based hard carbon material is 451.51 m 2 / g, and the micropore volume is 0.217cm 3 / g; The modified phenolic resin-based hard carbon material prepared by the present invention is used as the negative electrode material of the sodium ion battery, which has an initial coulombic efficiency of 86.44%, a platform capacity of 232.8 mAh / g at a current density of 0.05 A / g, and a capacity retention rate of 83.71% after stable circulation for 1000 cycles with a coulombic efficiency of 99.97% at a current density of 1 A / g.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a modified phenolic resin-based hard carbon material, characterized in that: The steps include: S1. Introducing metal ions into phenolic aldehyde, adding a surfactant and 25-30% ammonia water to the solvent in sequence, mixing, adding 1,2,4-pyrogallol, and adding glucuronolactone after dissolving, stirring and reacting; adding metal ion salt to the solution after the reaction is completed, and continuing the reaction; S2, preparing a modified phenolic resin-based material, placing the solution obtained after the reaction in step S1 into a polytetrafluoroethylene liner, moving it into a hydrothermal autoclave for reaction, and filtering, washing, and drying the product to obtain a modified phenolic resin-based material; S3, preparing a modified phenolic resin-based hard carbon material, transferring the prepared phenolic resin-based material to a corundum porcelain boat, and reacting it in a high-temperature tube furnace under an argon atmosphere to obtain a modified phenolic resin-based hard carbon material; In step S1, the mass volume ratio of solvent: surfactant: ammonia water: 1,2,4-pyrogallol: glucuronolactone: metal ion salt is 60 mL: 0.25 mL: 0-3 mL: 1.5 g: 3 g: 0.4 g; after adding the metal ion salt, the reaction is stirred for 12 hours; the metal ion salt is one of zinc acetate, zinc chloride, and zinc sulfate; The hydrothermal reaction conditions in step S2 are 180° C. for 24 h; The reaction conditions in the argon atmosphere in step S3 are: heating to 900° C. at 5° C. / min, keeping the temperature for 1 hour, and then heating to 1300° C. at 2° C. / min and keeping the temperature for 3 hours.

2. The method for preparing a modified phenolic resin-based hard carbon material according to claim 1, wherein: In step S1, the solvent is one or both of deionized water and ethanol, and the surfactant is one of polyethylene glycol and ethylene glycol.

3. A modified phenolic resin-based hard carbon material prepared by the method for preparing a modified phenolic resin-based hard carbon material according to claim 1 or 2.

4. Use of the modified phenolic resin-based hard carbon material according to claim 3 in a sodium ion battery, characterized in that: The modified phenolic resin-based hard carbon material is used as the negative electrode of a sodium ion battery.

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