Preparation method and application of phosphorus-doped hard carbon material for sodium ion battery

Abstract

The application belongs to the technical field of carbon materials, and provides a preparation method and application of phosphorus-doped hard carbon material for sodium ion batteries, which comprises the following steps: sodium aspartate, sodium polyphosphate, zinc phytate and maleic anhydride are ball-mixed in a mass ratio of 15-25:2-10:0.5-2:10-20, then heat preservation is carried out at 250-350 DEG C in air for 1-3h, then the mixture is transferred into a protective gas atmosphere furnace for carbonization at 1100-1300 DEG C for 1-5h, and a phosphorus-doped hard carbon material is obtained. The hard carbon material prepared by the method has higher battery capacity and stability.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of carbon materials, and relates to a preparation method and application of phosphorus-doped hard carbon material for sodium ion batteries. BACKGROUND

[0002] Lithium ion batteries are widely concerned due to high energy density, long service life and environmental friendliness, but with the large-scale application of electric vehicles and energy storage power stations, the demand for lithium resources has also greatly increased. Lithium resource shortage and uneven distribution have also begun to emerge as a bottleneck problem restricting the development of lithium ion batteries. In contrast, sodium in sodium ion batteries as charge carriers for energy storage is in the same group as lithium, and has cost and resource advantages, making it the best substitute for lithium ion batteries. Among the negative electrode materials available for sodium ion batteries, carbon negative electrodes have lower potential, higher capacity, stable physical and chemical properties, and low cost, and become the first choice for commercial development of sodium ion batteries. However, the current commercial graphite negative electrode material cannot be applied in sodium ion batteries, and its sodium storage capacity is too low, and the energy density is far from the existing commercial lithium ion batteries, so it is necessary to develop new carbon negative electrode materials.

[0003] Among various carbon materials, amorphous carbon materials show better performance. Amorphous carbon materials include soft carbon and hard carbon, and hard carbon as a negative electrode of sodium ion batteries has a higher capacity, and the large interlayer spacing and porous structure of hard carbon material can alleviate the volume expansion during the reaction, which is beneficial to the commercialization of sodium ion batteries. However, hard carbon material as a negative electrode of sodium ion batteries also has some problems, such as low battery capacity and poor stability, which seriously hinder the industrial application of hard carbon-based negative electrode materials.

[0004] Therefore, it has important value to develop a hard carbon material for sodium ion batteries, which has rich pore structure, excellent sodium storage performance, high battery specific capacity and good battery stability. SUMMARY

[0005] The application provides a preparation method of phosphorus-doped hard carbon material for sodium ion batteries, which is simple in preparation process, easy to operate, and has good application value. The prepared hard carbon material has higher battery capacity and stability.

[0006] The technical scheme of the application is as follows:

[0007] The application provides a preparation method of phosphorus-doped hard carbon material for sodium ion batteries, which is simple in preparation process, easy to operate, and has good application value. The prepared hard carbon material has higher battery capacity and stability.

[0008] The aspartic acid sodium, sodium polyphosphate, zinc phytate and maleic anhydride are ball-mixed in a mass ratio of 15-25:2-10:0.5-2:10-20, then heat-treated at 250-350 DEG C for 1-3h in air, then transferred to a furnace with protective gas atmosphere at 1100-1300 DEG C for carbonization, heat-treated for 1-5h, to obtain the phosphorus-doped hard carbon material.

[0009] As some preferred embodiments of the present application, the mass ratio of the aspartic acid sodium, sodium polyphosphate, zinc phytate and maleic anhydride is 18-22:3-6:0.5-1.5:13-18.

[0010] As some preferred embodiments of the present application, the mass ratio of the aspartic acid sodium, sodium polyphosphate, zinc phytate and maleic anhydride is 20:5:1:15.

[0011] As some preferred embodiments of the present application, the sodium polyphosphate is selected from one or a mixture of several of sodium tripolyphosphate, sodium hexametaphosphate and sodium dodecametaphosphate.

[0012] As some preferred embodiments of the present application, the sodium polyphosphate is sodium hexametaphosphate.

[0013] As some preferred embodiments of the present application, the protective gas is selected from nitrogen, helium or argon.

[0014] As some preferred embodiments of the present application, the rotation speed of the ball-milling is 350-550 rpm, and the ball-milling time is 1.5-2.5h.

[0015] As some preferred embodiments of the present application, after the ball-mixing, the temperature is raised to 250-350 DEG C at a rate of 2-5 DEG C / min and kept for 1-3h.

[0016] As some preferred embodiments of the present application, the carbonization process specifically comprises: constantly flowing the protective gas at a rate of 6-10 mL / min, raising the temperature to 1100-1300 DEG C at a rate of 2-5 DEG C / min and keeping for 1-5h, and naturally cooling to room temperature.

[0017] The second aspect of the present application provides a hard carbon material obtained by the above method.

[0018] The third aspect of the present application provides the application of the hard carbon material prepared by the preparation method of the hard carbon material.

[0019] The working principle and beneficial effects of the present application are as follows:

[0020] 1、The four of sodium aspartate, sodium polyphosphate, zinc phytate and maleic anhydride in the application are a mutual interaction mechanism to form a battery negative electrode material with high capacity, and the mutual interaction between the four is as follows:

[0021] (1) Sodium aspartate and maleic anhydride are polymerized at high temperature to form macromolecular polymers, and the carbon residue is increased, and at the same time, sodium aspartate is used to remain sodium in the pore structure of hard carbon during the preparation of the material, which can provide the initial capacity of the battery and improve the battery capacity;

[0022] (2) The material is treated in an air atmosphere because oxygen molecules in the air at 250-350 DEG C can induce the polymerization of sodium aspartate and maleic anhydride, increase the polymerization degree, and in addition, the material can be etched under a high-temperature air atmosphere to form a defect structure, which is beneficial to the storage of sodium ions;

[0023] (3) The action of sodium polyphosphate is that it can dope phosphorus to increase the phosphorus doping amount, and it is resistant to high temperature, which can reduce the loss of phosphorus at high temperature, thereby improving the battery capacity and stability of the negative electrode material; secondly, it can in-situ dope sodium, so that sodium can be sealed in the closed pore structure to improve the sodium capacity; thirdly, sodium polyphosphate can play a role in wrinkle at high temperature to form more defect sites to improve the sodium storage capacity of the battery.

[0024] (4) The zinc in zinc phytate can be chelated with sodium aspartate containing nitrogen and maleic anhydride containing oxygen to play the role of a crosslinking agent, and the phytate group is polymerized at high temperature to form a macromolecule containing phosphorus to improve the decomposition temperature and facilitate in-situ doping of phosphorus, in addition, the zinc ions in zinc phytate are coated inside during the polymerization process, and are volatilized at high temperature to form pores, which has a pore-forming effect, and the pores are closed after high-temperature carbonization, and the closed pores leave sodium ions in the pores, which can improve the battery capacity.

[0025] 2、The porous hard carbon doped with phosphorus provided by the application has a higher phosphorus doping amount, high battery capacity and stability, which is verified by experiments.

[0026] 3、The preparation method of the phosphorus-doped hard carbon provided by the application has a wide source of raw materials, low price, simple preparation process and good application value. BRIEF DESCRIPTION OF DRAWINGS

[0027] The application will be further described in detail below in combination with the drawings and specific embodiments.

[0028] Figure 1 is the XPS peak fitting diagram of phosphorus elements in the hard carbon material obtained in Example 1 of the application.

[0029] Figure 2 is the XPS peak fitting diagram of nitrogen elements in the hard carbon material obtained in Example 1 of the application.

[0030] Figure 3 This is the adsorption-desorption curve of the hard carbon material obtained in Example 1 of the present invention.

[0031] Figure 4 This is a SEM image of the hard carbon material obtained in Example 1 of the present invention. Detailed Implementation

[0032] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention. Unless otherwise specified, all raw materials, reagents, instruments and equipment used in the present invention can be purchased on the market or prepared by existing methods. Wherein:

[0033] Sodium aspartate was purchased from Aladdin Reagent, product number L193085-500g;

[0034] Sodium polyphosphate, specifically sodium hexametaphosphate, was purchased from Aladdin Reagents, catalog number S165313-500g;

[0035] Zinc phytate was purchased from Aladdin Reagent, product number Z304250-25g;

[0036] Maleic anhydride was purchased from Aladdin Reagents, catalog number M116389-500g.

[0037] Example 1

[0038] A method for preparing phosphorus-doped hard carbon material for sodium-ion batteries includes the following steps:

[0039] Sodium aspartate, sodium polyphosphate, zinc phytate, and maleic anhydride were ball-milled in a mass ratio of 20:5:1:15 for 2 hours at a speed of 500 rpm. The mixture was then heated to 300°C in air at a rate of 3°C / min and held for 2 hours. The mixture was then transferred to a nitrogen atmosphere furnace and carbonized at 1200°C at a rate of 4°C / min by continuously introducing nitrogen at a rate of 8 mL / min and holding for 2 hours. The mixture was then allowed to cool naturally to room temperature to obtain phosphorus-doped hard carbon material.

[0040] The hard carbon material obtained in this embodiment was characterized by XPS, SEM, specific surface area, and pore size distribution, such as... Figures 1-4 As shown, by Figures 1-2 It can be seen that the final hard carbon material contains phosphorus and nitrogen elements, with a phosphorus content of 9.5 at% and a nitrogen content of 6.7 at%. Figure 3It can be seen that there are mesoporous, macroporous and microporous structures in the hard carbon material, indicating that the material has a multi-level pore structure. Figure 4 It can be seen that the prepared hard carbon material has a rich pore structure.

[0041] Example 2

[0042] Sodium aspartate, sodium polyphosphate, zinc phytate and maleic anhydride were ball-mixed in a mass ratio of 15:10:0.5:20, the rotation speed of ball milling was 350 rpm, the ball milling time was 2.5 h, then it was heated to 350°C at a rate of 2°C / min in air and kept for 1 h, then it was transferred to a nitrogen atmosphere furnace, nitrogen was constantly introduced at a rate of 10 mL / min, heated to 1300°C at a rate of 2°C / min and kept for 1 h, and then naturally cooled to room temperature to obtain a phosphorus-doped hard carbon material.

[0043] Example 3

[0044] Sodium aspartate, sodium polyphosphate, zinc phytate and maleic anhydride were ball-mixed in a mass ratio of 25:2:2:10, the rotation speed of ball milling was 550 rpm, the ball milling time was 1.5 h, then it was heated to 250°C at a rate of 5°C / min in air and kept for 3 h, then it was transferred to a nitrogen atmosphere furnace, nitrogen was constantly introduced at a rate of 6 mL / min, heated to 1100°C at a rate of 5°C / min and kept for 5 h, and then naturally cooled to room temperature to obtain a phosphorus-doped hard carbon material.

[0045] Example 4

[0046] Sodium aspartate, sodium polyphosphate, zinc phytate and maleic anhydride were ball-mixed in a mass ratio of 18:6:1.5:13, the rotation speed of ball milling was 400 rpm, the ball milling time was 2 h, then it was heated to 300°C at a rate of 3°C / min in air and kept for 2 h, then it was transferred to a nitrogen atmosphere furnace, nitrogen was constantly introduced at a rate of 8 mL / min, heated to 1200°C at a rate of 3°C / min and kept for 3 h, and then naturally cooled to room temperature to obtain a phosphorus-doped hard carbon material.

[0047] Example 5

[0048] Sodium aspartate, sodium polyphosphate, zinc phytate and maleic anhydride were ball-mixed in a mass ratio of 22:3:0.5:18, the rotation speed of ball milling was 400 rpm, the ball milling time was 2 h, then it was heated to 300°C at a rate of 3°C / min in air and kept for 2 h, then it was transferred to a nitrogen atmosphere furnace, nitrogen was constantly introduced at a rate of 8 mL / min, heated to 1200°C at a rate of 3°C / min and kept for 3 h, and then naturally cooled to room temperature to obtain a phosphorus-doped hard carbon material.

[0049] Comparative Example 1

[0050] A preparation method of a phosphorus-doped hard carbon material for a sodium ion battery, comprising the following steps:

[0051] Sodium aspartate, sodium polyphosphate and maleic anhydride with a mass ratio of 20:5:15 are ball-mixed, the rotation speed of ball-milling is 500 rpm, the ball-milling time is 2 h, then the temperature is raised to 300°C at a rate of 3°C / min in air, and then the temperature is raised to 1200°C at a rate of 4°C / min in a nitrogen atmosphere furnace for carbonization, the temperature is kept for 2 h, and then the temperature is naturally lowered to room temperature, to obtain the phosphorus-doped hard carbon material.

[0052] Comparative Example 2

[0053] A preparation method of a phosphorus-doped hard carbon material for a sodium ion battery, comprising the following steps:

[0054] Sodium aspartate, zinc phytate and maleic anhydride with a mass ratio of 20:1:15 are ball-mixed, the rotation speed of ball-milling is 500 rpm, the ball-milling time is 2 h, then the temperature is raised to 300°C at a rate of 3°C / min in air, and then the temperature is raised to 1200°C at a rate of 4°C / min in a nitrogen atmosphere furnace for carbonization, the temperature is kept for 2 h, and then the temperature is naturally lowered to room temperature, to obtain the phosphorus-doped hard carbon material.

[0055] Comparative Example 3

[0056] A preparation method of a phosphorus-doped hard carbon material for a sodium ion battery, comprising the following steps:

[0057] Sodium aspartate, sodium polyphosphate, zinc chloride and maleic anhydride with a mass ratio of 20:5:1:0.8:15 are ball-mixed, the rotation speed of ball-milling is 500 rpm, the ball-milling time is 2 h, then the temperature is raised to 300°C at a rate of 3°C / min in air, and then the temperature is raised to 1200°C at a rate of 4°C / min in a nitrogen atmosphere furnace for carbonization, the temperature is kept for 2 h, and then the temperature is naturally lowered to room temperature, to obtain the phosphorus-doped hard carbon material.

[0058] Comparative Example 4

[0059] A preparation method of a phosphorus-doped hard carbon material for a sodium ion battery, comprising the following steps:

[0060] Sodium aspartate, sodium polyphosphate, zinc phytate and maleic anhydride with a mass ratio of 20:5:1:15 were ball-mixed at a rotation speed of 500 rpm for 2 h, then transferred into a nitrogen atmosphere furnace, and carbonized at 1200℃ at a rate of 4℃ / min under a constant nitrogen flow of 8 mL / min, and then naturally cooled to room temperature to obtain the phosphorus-doped hard carbon material.

[0061] Comparative Example 5

[0062] A method for preparing a phosphorus-doped hard carbon material for sodium ion batteries, comprising the following steps:

[0063] Sodium aspartate, sodium polyphosphate and zinc phytate with a mass ratio of 20:5:1 were ball-mixed at a rotation speed of 500 rpm for 2 h, then heated to 300℃ at a rate of 3℃ / min in air for 2 h, then transferred into a nitrogen atmosphere furnace, and carbonized at 1200℃ at a rate of 4℃ / min under a constant nitrogen flow of 8 mL / min, and then naturally cooled to room temperature to obtain the phosphorus-doped hard carbon material.

[0064] Comparative Example 6

[0065] A method for preparing a phosphorus-doped hard carbon material for sodium ion batteries, comprising the following steps:

[0066] Sodium L-glutamate, sodium polyphosphate, zinc phytate and maleic anhydride with a mass ratio of 20:5:1:15 were ball-mixed at a rotation speed of 500 rpm for 2 h, then heated to 300℃ at a rate of 3℃ / min in air for 2 h, then transferred into a nitrogen atmosphere furnace, and carbonized at 1200℃ at a rate of 4℃ / min under a constant nitrogen flow of 8 mL / min, and then naturally cooled to room temperature to obtain the phosphorus-doped hard carbon material.

[0067] Comparative Example 7

[0068] A method for preparing a phosphorus-doped hard carbon material for sodium ion batteries, comprising the following steps:

[0069] Sodium aspartate, sodium polyphosphate, zinc phytate and citraconic anhydride with a mass ratio of 20:5:1:15 were ball-mixed at a rotation speed of 500 rpm for 2 h, then heated to 300℃ at a rate of 3℃ / min in air for 2 h, then transferred into a nitrogen atmosphere furnace, and carbonized at 1200℃ at a rate of 4℃ / min under a constant nitrogen flow of 8 mL / min, and then naturally cooled to room temperature to obtain the phosphorus-doped hard carbon material.

[0070] Performance test

[0071] (1) Nitrogen adsorption-desorption experiment

[0072] The specific surface area of the hard carbon materials obtained in the above-mentioned examples 1-5 and comparative examples 1-5 was characterized by a nitrogen adsorption-desorption analyzer (ASAP2420), and the obtained results are shown in Table 1.

[0073] (2) Battery charge-discharge cycle test

[0074] Preparation of working electrode: the hard carbon materials prepared in examples 1-5 and comparative examples 1-5 were mixed and ground with acetylene black and polyvinylidene fluoride at a mass ratio of 8:1:1, and then N-methylpyrrolidone was added dropwise during grinding to prepare a slurry, the slurry was uniformly coated on a copper box and heated and dried to obtain a working electrode.

[0075] Preparation of electrolyte: the electrolyte was a mixed solution of EC: DMC: EMC at a volume ratio of 1:2:2, and the concentration of solute NaPF6 was 1.5M.

[0076] Test: glass microfiber separators, sodium metal sheets as reference electrodes, working electrodes, CR2032 battery shells, and gaskets were placed in an argon-filled glove box to assemble a half-cell. The assembled button cell was subjected to current charge-discharge cycle test by a LAND CT2001A battery test system at a large current of 10A / g, wherein the stability refers to the battery capacity retention rate after 1000 cycles, and the test results are shown in Table 1.

[0077]

[0078] As can be seen from Table 1, when the hard carbon material prepared by the present application is used as the negative electrode of a sodium ion battery, the specific capacity of the battery is significantly improved, which can reach 323mAh / g, and the preparation method is simple, easy to operate, and suitable for industrial application.

[0079] The above is only a preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a phosphorus-doped hard carbon material for a sodium-ion battery, characterized by, The method comprises the following steps: Sodium aspartate, sodium polyphosphate, zinc phytate and maleic anhydride are ball-mixed in a mass ratio of 15-25:2-10:0.5-2:10-20, then incubated in air at 250-350℃ for 1-3h, then transferred to a furnace with a protective gas atmosphere at 1100-1300℃ for carbonization, incubated for 1-5h, to obtain a phosphorus-doped hard carbon material.

2. The method for preparing phosphorus-doped hard carbon material for sodium-ion battery according to claim 1, characterized in that, The mass ratio of sodium aspartate, sodium polyphosphate, zinc phytate and maleic anhydride is 18-22:3-6:0.5-1.5:13-18. 3.The method for preparing a phosphorus-doped hard carbon material for a sodium-ion battery according to claim 1, characterized in that, The sodium polyphosphate is selected from one or a mixture of several of sodium tripolyphosphate, sodium hexametaphosphate and sodium dodecametaphosphate.

4. The method for preparing a phosphorus-doped hard carbon material for sodium-ion batteries according to claim 1, characterized in that, The sodium polyphosphate is sodium hexametaphosphate.

5. The method for preparing a phosphorus-doped hard carbon material for sodium-ion batteries according to claim 1, characterized in that, The protective gas is selected from nitrogen, helium or argon.

6. The method for preparing a phosphorus-doped hard carbon material for sodium-ion batteries according to claim 1, characterized in that, The rotation speed of the ball mill is 350-550rpm, and the ball milling time is 1.5-2.5h.

7. The method for preparing a phosphorus-doped hard carbon material for sodium-ion batteries according to claim 1, characterized in that, After ball-mixing, the temperature is raised to 250-350℃ at a rate of 2-5℃ / min and then kept for 1-3h. 8.The method for preparing a phosphorus-doped hard carbon material for a sodium-ion battery according to claim 1, characterized in that, The carbonization process specifically comprises: continuously introducing a protective gas at a rate of 6-10mL / min, raising the temperature to 1100-1300℃ at a rate of 2-5℃ / min and then keeping for 1-5h, and naturally cooling to room temperature.

9. A hard carbon material obtained by the method of any one of claims 1-8.

10. Use of a hard carbon material prepared according to the method of any one of claims 1 to 8, characterized in that, A negative electrode material for sodium ion batteries.

Images