Metal organic compound coated sodium ion battery hard carbon negative electrode material and preparation method thereof

Abstract

The invention discloses a metal organic compound coated sodium ion battery hard carbon negative electrode material and a preparation method thereof, and the preparation method comprises the following steps: S1, carrying out two-step acid pickling treatment on pulverized coal, and then washing and drying; s2, dissolving the pulverized coal subjected to impurity removal and a metal organic compound according to a certain proportion, uniformly stirring, washing with water, and drying; s3, carrying out low-temperature pre-carbonization treatment on the mixed powder in an inert atmosphere; and S4, further performing high-temperature carbonization on the carbonized sample in the step S3 in an inert atmosphere to obtain the modified hard carbon negative electrode material. According to the metal organic compound coated hard carbon negative electrode material prepared by the preparation method, the sodium storage performance of coal-based hard carbon is greatly improved, and the metal organic compound coated hard carbon negative electrode material has relatively high specific capacity, excellent rate capability, low cost, simple preparation process and relatively high application value.

Description

Technical Field

[0001] The present invention belongs to the technical field of sodium ion battery negative electrode materials, and in particular relates to a metal organic compound coated sodium ion battery hard carbon negative electrode material and a preparation method thereof. Background Art

[0002] With the current social and environmental problems and energy crisis becoming increasingly serious, the development of new technologies for clean and renewable energy has become urgent, and advanced energy storage technologies are also ushering in further development. Although lithium-ion batteries dominate the energy storage market with their significant advantages of high energy density and long cycle life, their inherent defects have seriously hindered their further practical application, including poor safety and insufficient lithium resources, making it difficult to meet people's long-term demand for energy. Compared to lithium, sodium is abundant in nature and inexpensive. Therefore, sodium-ion batteries have received widespread attention from all walks of life in recent years and have become a powerful supplement to lithium-ion batteries.

[0003] Currently, sodium-ion battery anode materials are primarily carbon-based. Hard carbon materials, with their significant advantages such as abundant raw materials, low cost, simple preparation process, and good cycle stability, are currently one of the top choices for the commercialization of sodium-ion batteries. However, hard carbon anode materials still suffer from low sodium storage capacity and poor rate performance, which are not conducive to the further application of sodium-ion batteries. Therefore, how to use lower-cost and more environmentally friendly precursor materials to prepare hard carbon anode materials with excellent performance for sodium-ion batteries is an important challenge that urgently needs to be solved. Summary of the Invention

[0004] Purpose of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a metal organic compound coated hard carbon negative electrode material for sodium ion batteries and a preparation method thereof. The metal organic compound coated hard carbon negative electrode material has a granular porous structure, which enables the sodium ion battery to have excellent charge capacity and excellent rate performance.

[0006] Solution

[0007] The present invention provides a method for preparing a metal organic compound-coated hard carbon negative electrode material for a sodium ion battery, characterized by comprising the following steps:

[0008] S1: The pulverized coal is subjected to a two-step acid washing treatment, followed by water washing and drying to remove impurities, wherein the particle size of the pulverized coal is 50-200 μm;

[0009] S2: dissolving the impurity-removed coal powder and the metal organic compound in ethanol, stirring them evenly, then washing them with water and drying them to obtain a mixed powder;

[0010] S3 pre-carbonizes the mixed powder at low temperature under an inert atmosphere;

[0011] S4: further carbonizing the carbonized sample in step S3 at a high temperature under an inert atmosphere to obtain a modified hard carbon negative electrode material;

[0012] The particle size of the metal organic compound coated hard carbon negative electrode material is 50-150 μm, and the specific surface area is 301.7 m 2 / g.

[0013] Organometallic compounds are metal organic compounds containing carbonyl groups.

[0014] Preferably, the metal organic compound containing a carbonyl group is a transition metal compound of acetylacetone, a late transition metal compound of acetylacetone or a Group 13 metal compound of acetylacetone.

[0015] More preferably, the metal organic compound containing a carbonyl group is at least one of manganese acetylacetonate, iron acetylacetonate, cobalt acetylacetonate, nickel acetylacetonate, zinc acetylacetonate and aluminum acetylacetonate.

[0016] In step S1, during the pickling process, the selected acid is one or more of hydrochloric acid, nitric acid, sulfuric acid, and hydrofluoric acid, and the temperature of the pickling treatment is 40-70°C.

[0017] In step S2, the mass ratio of coal powder to metal organic compound is 5-20:1, and the reaction time is 4-8 hours.

[0018] In step S3, the temperature of the low-temperature pre-carbonization treatment is 400-700°C, the pre-carbonization time is 1-3 hours, and the pre-carbonization heating rate is 1-5°C / min.

[0019] In step S4, the temperature of the high-temperature carbonization treatment is 800-1400° C., the carbonization time is 2-4 hours, the carbonization heating rate is 1-5° C. / min, and the cooling rate is 1-5° C. / min.

[0020] In steps S3 and S4, the inert atmosphere is one of nitrogen and argon.

[0021] The present invention also provides a metal organic compound coated hard carbon negative electrode material for sodium ion batteries prepared according to the above method.

[0022] Beneficial effects

[0023] The metal organic compound coated sodium ion battery hard carbon negative electrode material of the present invention has the following technical effects:

[0024] (1) The granular porous hard carbon material of the present invention can provide a large number of active sites for the storage of sodium ions during the charge and discharge process, which helps to obtain a higher capacity;

[0025] (2) The present invention uses metal organic compound derived carbon to coat the hard carbon material, which is beneficial to reducing the structural defects on the surface of the material, thereby improving the first-cycle coulomb efficiency; at the same time, the presence of metal ions in the coating layer has a certain improvement on the conductivity of the material;

[0026] (3) The present invention provides a method for obtaining a hard carbon negative electrode material for sodium ion batteries with high capacity and outstanding rate performance. It is low-cost, has a simple preparation process, is environmentally friendly, and has high application value and significance. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a scanning electron microscope image of the metal organic compound-coated hard carbon negative electrode material for sodium ion batteries prepared in Example 1 of the present invention;

[0028] Figure 2 This is the X-ray diffraction pattern of the metal organic compound-coated hard carbon negative electrode material for sodium ion batteries prepared in Example 3 of the present invention;

[0029] Figure 3 This is a rate performance diagram of the hard carbon negative electrode materials prepared in Examples 2 and 3 of the present invention and Comparative Example 1. DETAILED DESCRIPTION

[0030] The following will clearly and completely describe the concept and technical effects of the present invention in conjunction with the embodiments to fully understand the purpose, features, and effects of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without inventive effort are all within the scope of protection of the present invention.

[0031] Example 1

[0032] This embodiment provides a metal organic compound coated sodium ion battery hard carbon negative electrode material and a preparation method thereof, the preparation method specifically comprising the following steps:

[0033] (1) The pulverized coal is treated with hydrochloric acid and hydrofluoric acid to remove impurities, the temperature is controlled at 40°C, and then washed with water and dried;

[0034] (2) adding the impurity-removed coal powder and manganese acetylacetonate in a mass ratio of 5:1 into 40 ml of ethanol, stirring for a sufficient time to fully dissolve, then washing with water and drying;

[0035] (3) The mixed powder was heated to 400 °C in a nitrogen atmosphere for low-temperature pre-carbonization treatment, with a holding time of 1 h and a heating rate of 1 °C / min;

[0036] (4) The carbonized sample in step (3) is further heated to 800°C under a nitrogen atmosphere for high-temperature carbonization, with a holding time of 2 h, a heating rate of 3°C / min, and a cooling rate of 5°C / min to obtain a hard carbon negative electrode material for a sodium ion battery.

[0037] Example 2

[0038] This embodiment provides a metal organic compound coated sodium ion battery hard carbon negative electrode material and a preparation method thereof, the preparation method specifically comprising the following steps:

[0039] (1) The pulverized coal is treated with hydrochloric acid and hydrofluoric acid to remove impurities, the temperature is controlled at 50°C, and then washed with water and dried;

[0040] (2) Add the decontaminated coal powder and ferric acetylacetonate in a mass ratio of 10:1 to 40 ml of ethanol, stir for a sufficient time to fully dissolve, then wash with water and dry;

[0041] (3) The mixed powder was heated to 450 °C in a nitrogen atmosphere for low-temperature pre-carbonization treatment, with a holding time of 1.5 h and a heating rate of 1 °C / min;

[0042] (4) The carbonized sample in step (3) is further heated to 1000°C under a nitrogen atmosphere for high-temperature carbonization, with a holding time of 2 h, a heating rate of 3°C / min, and a cooling rate of 2°C / min to obtain a hard carbon negative electrode material for a sodium ion battery.

[0043] Example 3

[0044] This embodiment provides a metal organic compound coated sodium ion battery hard carbon negative electrode material and a preparation method thereof, the preparation method specifically comprising the following steps:

[0045] (1) The pulverized coal is treated with hydrochloric acid and hydrofluoric acid to remove impurities, the temperature is controlled at 60°C, and then washed with water and dried;

[0046] (2) adding the decontaminated coal powder and cobalt acetylacetonate in a mass ratio of 15:1 to 40 ml of ethanol, stirring for a sufficient time to fully dissolve, then washing with water and drying;

[0047] (3) The mixed powder was heated to 500 °C in a nitrogen atmosphere for low-temperature pre-carbonization treatment, with a holding time of 2 h and a heating rate of 2 °C / min;

[0048] (4) The carbonized sample in step (3) is further heated to 1200°C in a nitrogen atmosphere for high-temperature carbonization, with a holding time of 3 h, a heating rate of 2°C / min, and a cooling rate of 2°C / min to obtain a hard carbon negative electrode material for a sodium ion battery.

[0049] Example 4

[0050] This embodiment provides a metal organic compound coated sodium ion battery hard carbon negative electrode material and a preparation method thereof, the preparation method specifically comprising the following steps:

[0051] (1) The pulverized coal is treated with hydrochloric acid and hydrofluoric acid to remove impurities, the temperature is controlled at 70°C, and then washed with water and dried;

[0052] (2) adding the decontaminated coal powder and nickel acetylacetonate in a mass ratio of 10:1 to 40 ml of ethanol, stirring for a sufficient time to fully dissolve, and then washing with water and drying;

[0053] (3) The mixed powder was heated to 600 °C in a nitrogen atmosphere for low-temperature pre-carbonization treatment, with a holding time of 2.5 h and a heating rate of 2 °C / min;

[0054] (4) The carbonized sample in step (3) was further heated to 1400°C in a nitrogen atmosphere for high-temperature carbonization, with a holding time of 2.5 h, a heating rate of 2°C / min, and a cooling rate of 2°C / min to obtain a hard carbon negative electrode material for a sodium ion battery.

[0055] Example 5

[0056] This embodiment provides a metal organic compound coated sodium ion battery hard carbon negative electrode material and a preparation method thereof, the preparation method specifically comprising the following steps:

[0057] (1) The pulverized coal is treated with hydrochloric acid and hydrofluoric acid to remove impurities, the temperature is controlled at 50°C, and then washed with water and dried;

[0058] (2) Add the decontaminated coal powder and zinc acetylacetonate in a mass ratio of 15:1 to 40 ml of ethanol, stir for a sufficient time to fully dissolve, then wash with water and dry;

[0059] (3) The mixed powder was heated to 550 °C in a nitrogen atmosphere for low-temperature pre-carbonization treatment, with a holding time of 3 h and a heating rate of 3 °C / min;

[0060] (4) The carbonized sample in step (3) was further heated to 1000°C under a nitrogen atmosphere for high-temperature carbonization, with a holding time of 3.5 h, a heating rate of 3°C / min, and a cooling rate of 2°C / min to obtain a hard carbon negative electrode material for a sodium ion battery.

[0061] Example 6

[0062] This embodiment provides a metal organic compound coated sodium ion battery hard carbon negative electrode material and a preparation method thereof, the preparation method specifically comprising the following steps:

[0063] (1) The pulverized coal is treated with hydrochloric acid and hydrofluoric acid to remove impurities, the temperature is controlled at 60°C, and then washed with water and dried;

[0064] (2) Add the decontaminated coal powder and aluminum acetylacetonate in a mass ratio of 20:1 to 40 ml of ethanol, stir for a sufficient time to fully dissolve, then wash with water and dry;

[0065] (3) The mixed powder was heated to 700 °C in a nitrogen atmosphere for low-temperature pre-carbonization treatment, with a holding time of 2 h and a heating rate of 3 °C / min;

[0066] (4) The carbonized sample in step (3) was further heated to 800°C in a nitrogen atmosphere for high-temperature carbonization, with a holding time of 4 h, a heating rate of 5°C / min, and a cooling rate of 5°C / min to obtain a hard carbon negative electrode material for a sodium ion battery.

[0067] Example 7

[0068] This embodiment provides a metal organic compound coated sodium ion battery hard carbon negative electrode material and a preparation method thereof. The only difference from Example 3 is that the hydrochloric acid in the first step is replaced by nitric acid, and the other steps are exactly the same as Example 3.

[0069] Example 8

[0070] This embodiment provides a metal organic compound coated sodium ion battery hard carbon negative electrode material and a preparation method thereof. The only difference from Example 4 is that the 10:1 in the second step is replaced with 15:1, and the other steps are exactly the same as Example 4.

[0071] Comparative Example 1

[0072] A metal organic compound coated sodium ion battery hard carbon negative electrode material and a preparation method thereof, comprising the steps of:

[0073] (1) The pulverized coal is treated with hydrochloric acid and hydrofluoric acid to remove impurities, the temperature is controlled at 60°C, and then washed with water and dried;

[0074] (2) The pulverized coal after impurities removal was heated to 500°C in an argon atmosphere for low-temperature pre-carbonization treatment, with a holding time of 2 h and a heating rate of 2°C / min;

[0075] (3) The obtained powder was further heated to 1200°C in an argon atmosphere for high-temperature carbonization, with a holding time of 3 h, a heating rate of 2°C / min, and a cooling rate of 2°C / min to obtain a hard carbon negative electrode material for sodium ion batteries.

[0076] Comparative Example 2

[0077] A metal organic compound coated sodium ion battery hard carbon negative electrode material and a preparation method thereof, comprising the steps of:

[0078] (1) The pulverized coal is treated with hydrochloric acid and hydrofluoric acid to remove impurities, the temperature is controlled at 60°C, and then washed with water and dried;

[0079] (2) The pulverized coal after impurities removal was heated to 600°C in an argon atmosphere for low-temperature pre-carbonization treatment, with a holding time of 2.5 h and a heating rate of 2°C / min;

[0080] (3) The obtained powder was further heated to 1400°C in an argon atmosphere for high-temperature carbonization, with a holding time of 3 h, a heating rate of 2°C / min, and a cooling rate of 2°C / min to obtain a hard carbon negative electrode material for sodium ion batteries.

[0081] Performance Testing

[0082] Test Example 1

[0083] The sodium ion battery hard carbon negative electrode material prepared in Example 1 was observed by scanning electron microscopy (FESEM, JSM-6700F); the specific image is as follows Figure 1 shown.

[0084] like Figure 1 As shown, the metal organic compound coated hard carbon negative electrode material has a large number of pores and its particle size is relatively large, ranging from 50 to 150 μm.

[0085] Test Example 2

[0086] The sodium ion battery hard carbon negative electrode material prepared in Example 3 was subjected to X-ray diffraction (SHIMADZU XRD-7000) testing; the experimental conditions were as follows: copper target (λ = 0.1518 nm), 2θ angle range of 5 to 80°; XRD pattern as shown Figure 2 shown.

[0087] from Figure 2 It can be seen from the XRD pattern in that the prepared metal organic compound coated hard carbon negative electrode material has peaks near 25° and 43°, which are typical diffraction peaks of carbon materials.

[0088] Test Example 3

[0089] The hard carbon negative electrode materials prepared in Examples 2, 3 and Comparative Example 1 were assembled into CR2032 button batteries for rate performance testing; the test temperature was 30°C, and the test current densities were 0.03, 0.05, 0.1, 0.3, 0.5, 1.0 and 2.0 A / g, respectively; the rate performance curve is shown in FIG. Figure 3 shown.

[0090] from Figure 3 As can be seen from the results, compared with Comparative Example 1, Examples 2 and 3 have higher specific charge capacities. In particular, Example 3 achieves an initial capacity of 184 mAh / g at a current density of 0.03 A / g, and even has a specific capacity of 116 mAh / g at a high current density of 2.0 A / g, which is approximately 1.42 times that of Comparative Example 1. The above data show that metal organic compound-coated coal-based hard carbon anode materials have higher specific charge capacity and excellent rate performance.

[0091] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for preparing a metal organic compound coated hard carbon negative electrode material for sodium ion batteries, characterized in that: The following steps are involved: S1: The pulverized coal is subjected to a two-step acid washing treatment, followed by water washing and drying to remove impurities; wherein the particle size of the pulverized coal is 50-200 μm; S2: dissolving the impurity-removed coal powder and the metal organic compound in ethanol, stirring them evenly, then washing with water and drying them to obtain a mixed powder; S3 pre-carbonizes the mixed powder at low temperature under an inert atmosphere; S4: further carbonizing the carbonized sample in step S3 at a high temperature under an inert atmosphere to obtain a modified hard carbon negative electrode material; The particle size of the metal organic compound coated hard carbon negative electrode material is 50-150 μm, and the specific surface area is 301.7 m 2 / g.

2. The preparation method according to claim 1, wherein the metal organic compound is a metal organic compound containing a carbonyl group.

3. The preparation method according to claim 2, wherein the metal organic compound containing a carbonyl group is a transition metal compound of acetylacetone, a post-transition metal compound of acetylacetone, or a Group 13 metal compound of acetylacetone.

4. The preparation method according to claim 3, characterized in that The metal organic compound containing carbonyl is at least one of manganese acetylacetonate, iron acetylacetonate, cobalt acetylacetonate, nickel acetylacetonate, zinc acetylacetonate and aluminum acetylacetonate.

5. The preparation method according to claim 1, characterized in that In step S1, during the pickling process, the acid is one or more of hydrochloric acid, nitric acid, sulfuric acid, and hydrofluoric acid, and the pickling temperature is 40-70°C.

6. The preparation method according to any one of claims 1 to 5, characterized in that In step S2, the mass ratio of coal powder to metal organic compound is 5-20:1, and the reaction time is 4-8 hours.

7. The preparation method according to claim 1, characterized in that In step S3, the temperature of the low-temperature pre-carbonization treatment is 400-700°C, the pre-carbonization time is 1-3 hours, and the pre-carbonization heating rate is 1-5°C / min.

8. The preparation method according to claim 1, characterized in that In step S4, the temperature of the high-temperature carbonization treatment is 800-1400° C., the carbonization time is 2-4 hours, the carbonization heating rate is 1-5° C. / min, and the cooling rate is 1-5° C. / min.

9. The preparation method according to claim 1, characterized in that In steps S3 and S4, the inert atmosphere is one of nitrogen and argon.

10. A metal organic compound-coated hard carbon negative electrode material for sodium ion batteries prepared according to the method of any one of claims 1 to 9.

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