A supramolecular-derived hard carbon material, its preparation method and application, and sodium-ion batteries.

Abstract

This invention relates to the field of electrode materials technology, and more particularly to a supramolecular-derived hard carbon material, its preparation method and application, and sodium-ion batteries. The invention provides a method for preparing a supramolecular-derived hard carbon material, comprising the following steps: first, mixing an oxygen-containing carbon source aqueous solution and a nitrogen source small molecule aqueous solution to obtain a small molecule cluster solution; second, mixing the small molecule cluster solution with a metal ion aqueous solution for coordination to obtain a supramolecular precursor; and third, subjecting the supramolecular precursor to pre-oxidation and carbonization sequentially to obtain the supramolecular-derived hard carbon material. The supramolecular-derived hard carbon material exhibits high reversible capacity, excellent rate performance, and long-term cycling stability.

Description

Technical Field

[0001] This invention relates to the field of electrode materials technology, and in particular to a supramolecular-derived hard carbon material, its preparation method and application, and sodium-ion batteries. Background Technology

[0002] Sodium-ion batteries have shown broad application prospects in large-scale energy storage and other fields due to the abundance of sodium resources, low cost, good safety performance, and the ability to use aluminum foil as the negative electrode current collector. However, the large radius of sodium ions leads to relatively low reversible capacity and cycle stability of their electrode materials. The negative electrode material is a key component determining the performance of sodium-ion batteries. Hard carbon, due to its large interlayer spacing and abundant defect sites, is considered the most commercially promising negative electrode material for sodium-ion batteries, but it still suffers from problems such as low initial coulombic efficiency, limited specific capacity, and insufficient rate performance. Summary of the Invention

[0003] In view of this, the purpose of this invention is to provide a supramolecular-derived hard carbon material, its preparation method and application, and a sodium-ion battery. The supramolecular-derived hard carbon material exhibits high reversible capacity, excellent rate performance, and long cycle stability.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing supramolecular-derived hard carbon materials, comprising the following steps: An aqueous solution containing oxygen-containing carbon source and an aqueous solution containing small nitrogen molecules are first mixed to obtain a solution of small molecule clusters. The small molecule cluster solution is mixed with an aqueous metal ion solution for coordination to obtain a supramolecular precursor. The supramolecular precursor is subjected to pre-oxidation and carbonization in sequence to obtain the supramolecular-derived hard carbon material.

[0005] Preferably, the concentration of the oxygen-containing carbon source aqueous solution is 0.025~0.5 mol / L; The concentration of the nitrogen source small molecule aqueous solution is 0.025~0.5mol / L; The concentration of the aqueous solution containing the metal ions is 0.0625~0.5 mol / L.

[0006] Preferably, the oxygen-containing carbon source in the oxygen-containing carbon source aqueous solution includes one or more of resorcinol, terephthalic acid, trimesic acid and tannic acid; The nitrogen source small molecules in the aqueous solution include one or more of melamine, urea, ethylenediamine, and pyridine; The metal ions in the aqueous solution include Al. 3+ Fe 3+ and Zn 2+One or more of them.

[0007] Preferably, the molar ratio of the oxygen-containing carbon source and the nitrogen source small molecules is 1:1; The molar ratio of the oxygen-containing carbon source to the metal ions is 1:(0.125~1).

[0008] Preferably, after the first mixing, the mixture further includes stirring, and the stirring time is 10-60 minutes; The coordination is carried out under stirring conditions, and the stirring time is 30~120 minutes.

[0009] Preferably, the pre-oxidation temperature is 200~350℃, the holding time is 1~3h, and the heating rate to the pre-oxidation temperature is 1~3℃ / min.

[0010] Preferably, the carbonization temperature is 700~1200℃, the holding time is 1~3h, and the heating rate to the carbonization temperature is 2~5℃ / min.

[0011] The present invention also provides supramolecular-derived hard carbon materials prepared by the preparation method described in the above technical solution.

[0012] This invention also provides the application of the supramolecular-derived hard carbon material described in the above technical solution in sodium-ion batteries.

[0013] The present invention also provides a sodium-ion battery, comprising a positive electrode, a negative electrode, a separator and an electrolyte, wherein the negative electrode active material comprises a supramolecular-derived hard carbon material. The supramolecular-derived hard carbon material is the supramolecular-derived hard carbon material described in the above technical solution.

[0014] This invention provides a method for preparing supramolecular-derived hard carbon materials, comprising the following steps: firstly mixing an oxygen-containing carbon source aqueous solution and a nitrogen source small molecule aqueous solution to obtain a small molecule cluster solution; secondly mixing the small molecule cluster solution with a metal ion aqueous solution for coordination to obtain a supramolecular precursor; and sequentially pre-oxidizing and carbonizing the supramolecular precursor to obtain the supramolecular-derived hard carbon material.

[0015] Compared with the prior art, the technical solution of the present invention has the following beneficial effects: 1) This invention, by mixing an aqueous solution of oxygen-containing carbon source and an aqueous solution of nitrogen source small molecules and then adding the mixture to an aqueous solution of metal ions, can achieve the design of the composition and microstructure of supramolecular precursors, thereby controlling the pore structure and heteroatom doping type and content of hard carbon materials; 2) The uniformly distributed N and O heteroatoms in the supramolecular precursor can be in-situ doped during carbonization without the need for additional dopants, which effectively improves the sodium storage capacity and electronic conductivity of hard carbon materials. 3) The preparation method described does not require the use of toxic organic solvents, conforms to the concept of green chemistry, and is easy to scale up for production; 4) The supramolecular-derived hard carbon material prepared by the method described above has abundant heteroatom doping sites, and exhibits high reversible capacity, excellent rate performance and long cycle stability when used in sodium-ion batteries. 5) The preparation method uses a wide range of raw materials, all of which are common industrial raw materials, with low cost and good prospects for industrial application. Attached Figure Description

[0016] Figure 1 The XRD patterns of the supramolecular-derived hard carbon materials described in Examples 1 (1#), 4 (4#), 1 (5#), 6 (7#), and 7 (8#) are shown. Figure 2 XPS images of the supramolecular-derived hard carbon materials described in Example 1 (1#), Comparative Example 1 (5#), Example 6 (7#), and Example 7 (8#); Figure 3 The rate performance curves of sodium-ion half-cells prepared from the supramolecular-derived hard carbon materials described in Example 1 and Comparative Example 1 are shown. Figure 4 The rate performance curves of sodium-ion half-cells prepared from the supramolecular-derived hard carbon materials described in Examples 6 and 7 are shown. Figure 5 The cycling performance curve of the sodium-ion half-cell prepared from the supramolecular-derived hard carbon material described in Example 1 is shown. Detailed Implementation

[0017] This invention provides a method for preparing supramolecular-derived hard carbon materials, comprising the following steps: An aqueous solution containing oxygen-containing carbon source and an aqueous solution containing small nitrogen molecules are first mixed to obtain a solution of small molecule clusters. The small molecule cluster solution is mixed with an aqueous metal ion solution for coordination to obtain a supramolecular precursor. The supramolecular precursor is subjected to pre-oxidation and carbonization in sequence to obtain the supramolecular-derived hard carbon material.

[0018] In this invention, unless otherwise specified, all raw materials used in the preparation are commercially available products well known to those skilled in the art.

[0019] This invention involves first mixing an aqueous solution of an oxygen-containing carbon source and an aqueous solution of a nitrogen source containing small molecules to obtain a solution of small molecule clusters.

[0020] In this invention, the concentration of the oxygen-containing carbon source aqueous solution is preferably 0.025~0.5 mol / L, more preferably 0.025 mol / L, 0.05 mol / L, 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, 0.25 mol / L, 0.3 mol / L, 0.35 mol / L, 0.4 mol / L, 0.45, or 0.5 mol / L. In embodiments of this invention, the concentration of the oxygen-containing carbon source aqueous solution can be 0.1 mol / L, 0.025 mol / L, or 0.15 mol / L.

[0021] In this invention, the oxygen-containing carbon source in the aqueous solution preferably includes one or more of resorcinol, terephthalic acid, trimesin, and tannic acid. When the oxygen-containing carbon source is two or more of the above-mentioned specific selections, this invention does not impose any special limitation on the ratio of the above-mentioned specific substances. In the embodiments of this invention, the oxygen-containing carbon source is specifically tannic acid or trimesin.

[0022] In this invention, the concentration of the nitrogen source small molecule aqueous solution is preferably 0.025~0.5 mol / L, more preferably 0.025 mol / L, 0.05 mol / L, 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, 0.25 mol / L, 0.3 mol / L, 0.35 mol / L, 0.4 mol / L, 0.45, or 0.5 mol / L. In embodiments of this invention, the concentration of the nitrogen source small molecule aqueous solution can be 0.1 mol / L, 0.025 mol / L, or 0.15 mol / L.

[0023] In this invention, the nitrogen source small molecule in the aqueous solution preferably includes one or more of melamine, urea, ethylenediamine, and pyridine. When the nitrogen source small molecule is two or more of the above-mentioned specific selections, this invention does not have a special limitation on the ratio of the above-mentioned specific substances, and they can be mixed in any ratio. In the embodiments of this invention, the nitrogen source small molecule is specifically ethylenediamine monohydrate or melamine.

[0024] In this invention, the molar ratio of the oxygen-containing carbon source in the oxygen-containing carbon source aqueous solution to the nitrogen source small molecule in the nitrogen source small molecule aqueous solution is preferably 1:1.

[0025] The present invention does not impose any special limitations on the first mixing process, and any process known to those skilled in the art can be used.

[0026] After the first mixing is completed, the present invention preferably includes stirring, and the stirring time is preferably 10-60 min, more preferably 10 min, 20 min, 30 min, 40 min, 50 min or 60 min. In an embodiment of the present invention, the stirring time can be 20 min.

[0027] In this invention, during the stirring process, the oxygen-containing carbon source and nitrogen source small molecules will form small molecular clusters under the action of hydrogen bonds.

[0028] After obtaining the small molecule cluster solution, the present invention mixes the small molecule cluster solution with a metal ion aqueous solution for coordination to obtain a supramolecular precursor.

[0029] In this invention, the concentration of the metal ion aqueous solution is preferably 0.0625~0.5 mol / L, more preferably 0.0625 mol / L, 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, 0.25 mol / L, 0.3 mol / L, 0.35 mol / L, 0.4 mol / L, 0.45 mol / L, or 0.5 mol / L. In embodiments of this invention, the concentration of the metal ion aqueous solution is specifically 0.0625 mol / L, 0.125 mol / L, or 0.5 mol / L.

[0030] In this invention, the metal ions in the aqueous solution preferably include Al. 3+ Fe 3+ and Zn 2+ One or more of the above-selected metal ions; when the metal ions are two or more of the above-selected substances, the present invention does not have any special limitation on the specific ratio of the substances. In the present invention, the substance providing the metal ions is preferably a soluble metal salt. The present invention does not have any special limitation on the type of soluble metal salt, and any type well known to those skilled in the art can be used.

[0031] In this invention, the molar ratio of the oxygen-containing carbon source to the metal ions is preferably 1:(0.125~1), more preferably 1:0.125, 1:0.25, 1:0.5, 1:0.75 or 1:1. In embodiments of this invention, the molar ratio of the oxygen-containing carbon source to the metal ions is specifically 1:0.125, 1:1 or 1:0.25.

[0032] In this invention, the second mixing is preferably performed by adding an aqueous solution of metal ions dropwise to the solution of small molecule clusters; this invention does not impose any special limitations on the process of adding the aqueous solution of metal ions, and any process known to those skilled in the art can be used.

[0033] In this invention, the coordination is preferably carried out under stirring conditions, and the stirring time is preferably 30-120 min, more preferably 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min or 120 min. In an embodiment of this invention, the stirring time can be 60 min.

[0034] In this invention, during the stirring process, metal ions coordinate with small molecular clusters to form a larger, more stable and ordered three-dimensional network structure.

[0035] After the coordination is completed, the present invention preferably includes sequential filtration and drying. The present invention does not impose any special limitations on the filtration process; any process well-known to those skilled in the art can be used. In the present invention, the drying method is preferably freeze-drying. The present invention does not impose any special limitations on the freeze-drying process; any process well-known to those skilled in the art can be used.

[0036] In this invention, the oxygen-containing carbon source, nitrogen source small molecules and metal ions self-assemble in an aqueous phase through non-covalent bonding interactions (such as hydrogen bonds, coordination bonds, π-π interactions) to form a three-dimensional ordered supramolecular precursor, in which heteroatoms (N, O) and metal ions are uniformly distributed.

[0037] After obtaining the supramolecular precursor, the present invention performs pre-oxidation and carbonization on the supramolecular precursor in sequence to obtain the supramolecular-derived hard carbon material.

[0038] In this invention, the pre-oxidation is preferably carried out in an air atmosphere, and the pre-oxidation temperature is preferably 200~350℃, more preferably 200℃, 250℃, 300℃ or 350℃; the holding time is preferably 1~3h, more preferably 1h, 1.5h, 2.0h, 2.5h or 3.0h; the heating rate to the pre-oxidation temperature is preferably 1~3℃ / min, more preferably 1℃ / min, 1.5℃ / min, 2.0℃ / min, 2.5℃ / min or 3℃ / min. In an embodiment of this invention, the pre-oxidation temperature is specifically 200℃, the holding time is specifically 2h, and the heating rate to the pre-oxidation temperature is specifically 1℃ / min.

[0039] In this invention, controlling the pre-oxidation conditions within the above-mentioned range ensures efficient reaction with oxygen in the air and avoids structural collapse due to excessively high temperatures.

[0040] In this invention, the carbonization is preferably carried out in a protective atmosphere, preferably a high-purity argon atmosphere; the carbonization temperature is preferably 700~1200℃, more preferably 700℃, 800℃, 900℃, 1000℃, 1100℃ or 1200℃; the holding time is preferably 1~3h, more preferably 1h, 1.5h, 2.0h, 2.5h or 3h; the heating rate to the carbonization temperature is preferably 2~5℃ / min, more preferably 2℃ / min, 3℃ / min, 4℃ / min or 5℃ / min. In an embodiment of this invention, the carbonization temperature is specifically 700℃ or 900℃, the holding time is specifically 2.0h, and the heating rate to the carbonization temperature is specifically 2℃ / min.

[0041] In this invention, controlling the carbonization conditions within the above-mentioned range can ensure complete conversion to amorphous carbon while retaining sufficient heteroatom doping, and avoid pore structure collapse caused by excessively high temperature.

[0042] After the carbonization is completed, the present invention preferably includes cooling, and the cooling is preferably natural cooling.

[0043] The present invention also provides supramolecular-derived hard carbon materials prepared by the preparation method described in the above technical solution.

[0044] This invention also provides the application of the supramolecular-derived hard carbon material described in the above technical solution in sodium-ion batteries.

[0045] The present invention also provides a sodium-ion battery, comprising a positive electrode, a negative electrode, a separator and an electrolyte, wherein the negative electrode active material comprises a supramolecular-derived hard carbon material. The supramolecular-derived hard carbon material is the supramolecular-derived hard carbon material described in the above technical solution.

[0046] The present invention does not impose any special limitations on the types of positive electrode, separator and electrolyte, and any types well known to those skilled in the art can be used.

[0047] In this invention, the negative electrode preferably comprises a negative electrode current collector and a negative electrode material layer coated on the surface of the negative electrode current collector. In this invention, the negative electrode current collector is preferably copper foil. In this invention, the negative electrode material layer preferably comprises a negative electrode active material, a conductive agent, and a binder; the negative electrode active material is preferably the supramolecular-derived hard carbon material described in the above technical solution; this invention does not impose any special limitations on the types of conductive agents and binders, and types well known to those skilled in the art can be used. This invention does not impose any special limitations on the ratio of the active material, conductive agent, and binder, and ratios well known to those skilled in the art can be used.

[0048] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0049] Example 1 Dissolve 3.4 g (2 mmol) of tannic acid in 20 mL of deionized water to obtain an aqueous solution of tannic acid (concentration of 0.1 mol / L). 120.2 mg (2 mmol) of ethylenediamine was dissolved in 20 mL of deionized water to obtain an aqueous solution of ethylenediamine (concentration of 0.1 mol / L). An aqueous solution of ethylenediamine was added dropwise to the tannic acid solution and stirred for 20 min to obtain a small molecule cluster solution. Add ferric chloride aqueous solution (40.5 mg FeCl3 (0.25 mmol), dissolved in 4 mL of deionized water) dropwise to the small molecule cluster solution. 3+ With a concentration of 0.0625 mol / L, after stirring for 60 min, the mixture was filtered and freeze-dried sequentially to obtain supramolecular precursors (tannic acid, ethylenediamine, and Fe). 3+ The molar ratio is 1:1:0.125). The supramolecular precursor was placed in a muffle furnace and heated to 200°C at a heating rate of 1°C / min in air atmosphere. After pre-oxidation for 2 hours, it was transferred to a tube furnace and heated to 700°C at a heating rate of 2°C / min in high-purity argon atmosphere. After carbonization for 2 hours, it was naturally cooled to room temperature to obtain supramolecular-derived hard carbon material.

[0050] Example 2 Dissolve 3.4 g (2 mmol) of tannic acid in 20 mL of deionized water to obtain an aqueous solution of tannic acid (concentration of 0.1 mol / L). 120.2 mg (2 mmol) of ethylenediamine was dissolved in 20 mL of deionized water to obtain an aqueous solution of ethylenediamine (concentration of 0.1 mol / L). An aqueous solution of ethylenediamine was added dropwise to the tannic acid solution and stirred for 20 min to obtain a small molecule cluster solution. Add ferric chloride aqueous solution (81 mg FeCl3 (0.5 mmol), dissolved in 4 mL of deionized water) dropwise to the small molecule cluster solution. 3+ With a concentration of 0.125 mol / L, after stirring for 60 min, the mixture was filtered and freeze-dried sequentially to obtain supramolecular precursors (tannic acid, ethylenediamine, and Fe). 3+The molar ratio is 1:1:0.25). The supramolecular precursor was placed in a muffle furnace and heated to 200°C at a heating rate of 1°C / min in air atmosphere. After pre-oxidation for 2 hours, it was transferred to a tube furnace and heated to 700°C at a heating rate of 2°C / min in high-purity argon atmosphere. After carbonization for 2 hours, it was naturally cooled to room temperature to obtain supramolecular-derived hard carbon material.

[0051] Example 3 Dissolve 3.4 g (2 mmol) of tannic acid in 20 mL of deionized water to obtain an aqueous solution of tannic acid (concentration of 0.1 mol / L). 120.2 mg (2 mmol) of ethylenediamine was dissolved in 20 mL of deionized water to obtain an aqueous solution of ethylenediamine (concentration of 0.1 mol / L). An aqueous solution of ethylenediamine was added dropwise to the tannic acid solution and stirred for 20 min to obtain a small molecule cluster solution. Add ferric chloride aqueous solution (324 mg FeCl3 (2 mmol), dissolved in 4 mL of deionized water) dropwise to the small molecule cluster solution. 3+ With a concentration of 0.5 mol / L, after stirring for 60 min, the mixture was filtered and freeze-dried sequentially to obtain supramolecular precursors (tannic acid, ethylenediamine, and Fe). 3+ The molar ratio is 1:1:1). The supramolecular precursor was placed in a muffle furnace and heated to 200°C at a heating rate of 1°C / min in air atmosphere. After pre-oxidation for 2 hours, it was transferred to a tube furnace and heated to 700°C at a heating rate of 2°C / min in high-purity argon atmosphere. After carbonization for 2 hours, it was naturally cooled to room temperature to obtain supramolecular-derived hard carbon material.

[0052] Example 4 Dissolve 3.4 g (2 mmol) of tannic acid in 80 mL of deionized water to obtain an aqueous solution of tannic acid (concentration of 0.025 mol / L). 120.2 mg (2 mmol) of ethylenediamine was dissolved in 80 mL of deionized water to obtain an aqueous solution of ethylenediamine (concentration of 0.025 mol / L). An aqueous solution of ethylenediamine was added dropwise to the tannic acid solution and stirred for 20 min to obtain a small molecule cluster solution. Add 40.5 mg FeCl3 (0.25 mmol) aqueous solution, dissolved in 4 mL of deionized water, dropwise to the solution of the small molecule clusters. 3+ With a concentration of 0.0625 mol / L, after stirring for 60 min, the mixture was filtered and freeze-dried sequentially to obtain supramolecular precursors (tannic acid, ethylenediamine, and Fe). 3+The molar ratio is 1:1:0.125). The supramolecular precursor was placed in a muffle furnace and heated to 200°C at a heating rate of 1°C / min in air atmosphere. After pre-oxidation for 2 hours, it was transferred to a tube furnace and heated to 700°C at a heating rate of 2°C / min in high-purity argon atmosphere. After carbonization for 2 hours, it was naturally cooled to room temperature to obtain supramolecular-derived hard carbon material.

[0053] Example 5 Dissolve 3.4 g (2 mmol) of tannic acid in 20 mL of deionized water to obtain an aqueous solution of tannic acid (concentration of 0.1 mol / L). 120.2 mg (2 mmol) of ethylenediamine was dissolved in 20 mL of deionized water to obtain an aqueous solution of ethylenediamine (concentration of 0.1 mol / L). An aqueous solution of ethylenediamine was added dropwise to the tannic acid solution and stirred for 20 min to obtain a small molecule cluster solution. Add 40.5 mg FeCl3 (0.25 mmol) aqueous solution, dissolved in 4 mL of deionized water, dropwise to the solution of the small molecule clusters. 3+ With a concentration of 0.0625 mol / L, after stirring for 60 min, the mixture was filtered and freeze-dried sequentially to obtain supramolecular precursors (tannic acid, ethylenediamine, and Fe). 3+ The molar ratio is 1:1:0.125). The supramolecular precursor was placed in a muffle furnace and heated to 200°C at a heating rate of 1°C / min in air atmosphere. After pre-oxidation for 2 hours, it was transferred to a tube furnace and heated to 900°C at a heating rate of 2°C / min in high-purity argon atmosphere. After carbonization for 2 hours, it was naturally cooled to room temperature to obtain supramolecular-derived hard carbon material.

[0054] Example 6 Dissolve 1.5 g (12 mmol) of melamine in 80 mL of deionized water to obtain an aqueous melamine solution (concentration of 0.15 mol / L). Dissolve 2.52 g (12 mmol) of pyromellitic acid in 80 mL of deionized water to obtain an aqueous solution of pyromellitic acid (concentration of 0.15 mol / L). The melamine aqueous solution was added dropwise to the pyromellitic acid aqueous solution and stirred for 20 min to obtain a small molecule cluster solution. Ferric chloride aqueous solution (243 mg FeCl3, 1.5 mmol) was added dropwise to the small molecule cluster solution and dissolved in 24 mL of deionized water. 3+With a concentration of 0.0625 mol / L, after stirring for 60 min, the mixture was filtered and freeze-dried sequentially to obtain the supramolecular precursor (pyromellitic acid, melamine, and Fe). 3+ The molar ratio is 1:1:0.125). The supramolecular precursor was placed in a muffle furnace and heated to 200°C at a heating rate of 1°C / min in air atmosphere. After pre-oxidation for 2 hours, it was transferred to a tube furnace and heated to 700°C at a heating rate of 2°C / min in high-purity argon atmosphere. After carbonization for 2 hours, it was naturally cooled to room temperature to obtain supramolecular-derived hard carbon material.

[0055] Example 7 Dissolve 1.5 g (12 mmol) of melamine in 80 mL of deionized water to obtain an aqueous melamine solution (concentration of 0.15 mol / L). Dissolve 2.52 g (12 mmol) of pyromellitic acid in 80 mL of deionized water to obtain an aqueous solution of pyromellitic acid (concentration of 0.15 mol / L). The melamine aqueous solution was added dropwise to the pyromellitic acid aqueous solution and stirred for 20 min to obtain a small molecule cluster solution. Ferric chloride aqueous solution (243 mg FeCl3, 1.5 mmol) was added dropwise to the small molecule cluster solution and dissolved in 24 mL of deionized water. 3+ With a concentration of 0.0625 mol / L, after stirring for 60 min, the mixture was filtered and freeze-dried sequentially to obtain the supramolecular precursor (pyromellitic acid, melamine, and Fe). 3+ The molar ratio is 1:1:0.125). The supramolecular precursor was placed in a muffle furnace and heated to 200°C at a heating rate of 1°C / min in air atmosphere. After pre-oxidation for 2 hours, it was transferred to a tube furnace and heated to 900°C at a heating rate of 2°C / min in high-purity argon atmosphere. After carbonization for 2 hours, it was naturally cooled to room temperature to obtain supramolecular-derived hard carbon material.

[0056] Comparative Example 1 Dissolve 3.4 g (2 mmol) of tannic acid in 20 mL of deionized water to obtain an aqueous solution of tannic acid (concentration of 0.1 mol / L). 120.2 mg (2 mmol) of ethylenediamine was dissolved in 20 mL of deionized water to obtain an aqueous solution of ethylenediamine (concentration of 0.1 mol / L). An aqueous solution of ethylenediamine was added dropwise to the tannic acid solution and stirred for 20 min to obtain a small molecule cluster solution. Add 40.5 mg FeCl3 (0.25 mmol) aqueous solution, dissolved in 4 mL of deionized water, dropwise to the solution of the small molecule clusters. 3+ With a concentration of 0.0625 mol / L, after stirring for 60 min, the mixture was filtered and freeze-dried sequentially to obtain supramolecular precursors (tannic acid, ethylenediamine, and Fe). 3+ The molar ratio is 1:1:0.125). The supramolecular precursor was placed in a tube furnace and heated to 700°C at a heating rate of 2°C / min under a high-purity argon atmosphere. It was then carbonized for 2 hours and naturally cooled to room temperature to obtain a supramolecular-derived hard carbon material.

[0057] Test Example 1 Figure 1 The XRD patterns of the supramolecular-derived hard carbon materials described in Examples 1 (1#), 4 (4#), Comparative Example 1 (5#), 6 (7#), and 7 (8#) are provided by [the relevant authority]. Figure 1 It can be seen that the XRD curves of the supramolecular-derived hard carbon materials described in Examples 1, 4, 6 and 7 and Comparative Example 1 show a bulging peak at 25~26°, and the synthesized samples are all amorphous hard carbon structures. Figure 2 XPS images of the supramolecular-derived hard carbon materials described in Example 1 (1#), Comparative Example 1 (5#), Example 6 (7#), and Example 7 (8#), generated by... Figure 2 It can be seen that the supramolecular-derived hard carbon materials described in Example 1 and Comparative Example 1 retain high levels of O doping and low levels of N doping, which is attributed to the fact that the O content in tannic acid is much higher than the N content in the same molar amount of ethylenediamine. The supramolecular-derived hard carbon materials described in Examples 6 and 8 exhibit high levels of nitrogen and oxygen doping, which is due to the presence of the same amounts of O and N elements in the same molar amounts of pyromellitic acid and melamine.

[0058] Test Example 2 The supramolecular-derived hard carbon materials, conductive agents (specifically Super P), and binders (specifically polyvinylidene fluoride PVDF) described in Examples 1, 6, and 7 and Comparative Example 1 were mixed in N-methylpyrrolidone at a mass ratio of 8:1:1 to obtain coating slurries. After the coating slurry is coated onto the surface of the copper foil, it is dried in a vacuum oven at 120°C for 24 hours and then cut into electrode sheets with a diameter of 12 mm. A sodium-ion half-cell was assembled using a sodium metal sheet as the negative electrode, a NaPF6 DME solution (concentration of 0.8 mol / L) as the electrolyte, and GF / F glass fiber as the separator. The sodium-ion half-cell was then tested. Figure 3The rate performance curves of sodium-ion half-cells prepared from the supramolecular-derived hard carbon materials described in Example 1 and Comparative Example 1 are shown (charge and discharge current densities are 0.05 A·g, respectively). -1 0.1A·g -1 0.2A·g -1 0.5A·g -1 1A·g -1 2A·g -1 5A·g -1 10A·g -1 and 0.1A·g -1 ),Depend on Figure 3 It can be seen that the sodium-ion half-cell prepared from the supramolecular-derived hard carbon material described in Example 1 has a performance of 0.05~10 A g. -1 The current densities exhibited values ​​of 303, 292, 280, 265, 250, 236, 212, and 195 mA·h·g, respectively. -1 The sodium-ion half-cell prepared from the supramolecular-derived hard carbon material described in Comparative Example 1 exhibited a high sodium storage specific capacity, while the sodium-ion half-cell prepared from the supramolecular-derived hard carbon material described in Comparative Example 1 only showed 224, 211, 198, 172, 163, 149, 120 and 98 mA·h·g. -1 The sodium storage specific capacity indicates that the pre-oxidation process has a positive effect on the pore structure and heteroatom retention rate of supramolecular-derived hard carbon materials; Figure 4 The rate performance curves of sodium-ion half-cells prepared from the supramolecular-derived hard carbon materials described in Examples 6 and 7 are shown (charge and discharge current densities are 0.05 A·g, respectively). -1 0.1A·g -1 0.2A·g -1 0.5A·g -1 1A·g -1 2A·g -1 5A·g -1 and 10A·g -1 ),Depend on Figure 4 It can be seen that the sodium-ion half-cell prepared by the supramolecular-derived hard carbon material described in Example 6 exhibits higher sodium storage specific capacity at different current densities, indicating that the carbonization temperature of 700℃ can better preserve the active sites for sodium storage. Figure 5 The cycling performance curve of the sodium-ion half-cell prepared from the supramolecular-derived hard carbon material described in Example 1 (charge-discharge current density is 1 A·g) is shown. -1 ),Depend on Figure 5 It can be seen that the sodium-ion half-cell prepared from the supramolecular-derived hard carbon material described in Example 1 has a charge / discharge current density of 1 A·g -1Under certain conditions, the capacity showed almost no decay after 400 cycles, confirming its excellent structural stability. Furthermore, the in-situ doped heteroatoms also exhibited high electrochemical reversibility.

[0059] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing supramolecular-derived hard carbon materials, characterized in that, Includes the following steps: An aqueous solution containing oxygen-containing carbon source and an aqueous solution containing small nitrogen molecules are first mixed to obtain a solution of small molecule clusters. The small molecule cluster solution is mixed with an aqueous metal ion solution for coordination to obtain a supramolecular precursor. The supramolecular precursor is subjected to pre-oxidation and carbonization in sequence to obtain the supramolecular-derived hard carbon material.

2. The preparation method according to claim 1, characterized in that, The concentration of the oxygen-containing carbon source aqueous solution is 0.025~0.5mol / L; The concentration of the nitrogen source small molecule aqueous solution is 0.025~0.5mol / L; The concentration of the aqueous solution containing the metal ions is 0.0625~0.5 mol / L.

3. The preparation method according to claim 1 or 2, characterized in that, The oxygen-containing carbon source in the oxygen-containing carbon source aqueous solution includes one or more of resorcinol, terephthalic acid, trimesic acid, and tannic acid. The nitrogen source small molecules in the aqueous solution include one or more of melamine, urea, ethylenediamine, and pyridine; The metal ions in the aqueous solution include Al. 3+ Fe 3+ and Zn 2+ One or more of them.

4. The preparation method according to claim 3, characterized in that, The molar ratio of the oxygen-containing carbon source and nitrogen source small molecules is 1:1; The molar ratio of the oxygen-containing carbon source to the metal ions is 1:(0.125~1).

5. The preparation method according to claim 1, characterized in that, After the first mixing, stirring is also included, and the stirring time is 10-60 minutes; The coordination is carried out under stirring conditions, and the stirring time is 30~120 minutes.

6. The preparation method according to claim 1, characterized in that, The pre-oxidation temperature is 200~350℃, the holding time is 1~3h, and the heating rate to the pre-oxidation temperature is 1~3℃ / min.

7. The preparation method according to claim 1, characterized in that, The carbonization temperature is 700~1200℃, the holding time is 1~3h, and the heating rate to the carbonization temperature is 2~5℃ / min.

8. The supramolecular-derived hard carbon material prepared by the preparation method according to any one of claims 1 to 7.

9. The application of the supramolecular-derived hard carbon material of claim 8 in sodium-ion batteries.

10. A sodium-ion battery, comprising a positive electrode, a negative electrode, a separator, and an electrolyte, characterized in that, The negative electrode active material includes supramolecular-derived hard carbon materials; The supramolecular-derived hard carbon material is the supramolecular-derived hard carbon material as described in claim 8.

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