Preparation method and application of high-sulfur pyrolysis-based sodium ion battery negative electrode material

Abstract

The application discloses a preparation method and application of high-sulfur coke-based sodium ion battery negative electrode material and relates to the technical field of new energy electronic materials. The method comprises the following steps: (1) mixing and immersing crushed high-sulfur coke with a copper chloride solution according to a certain proportion; after the immersion is completed, the high-sulfur coke is extracted, washed until the filtrate is neutral, and dried; (2) performing two-stage heat treatment on the high-sulfur coke obtained in the step (1) in an argon gas environment; (3) performing acid pickling on the high-sulfur coke obtained in the step (2) after being cooled; after the acid pickling, the high-sulfur coke is extracted, washed until the filtrate is neutral, and dried; (4) performing ball milling on the material obtained in the step (3), and thus the high-sulfur coke-based sodium ion battery negative electrode material is prepared. The sodium ion battery assembled by using the high-sulfur coke-based sodium ion battery negative electrode material has improved electrochemical performance through the use of the copper chloride soaking and two-time heating processes.

Description

Technical Field

[0001] This invention relates to the field of new energy electronic materials technology, and in particular to a method for preparing and applying a sodium-ion battery anode material. Background Technology

[0002] Sodium-ion batteries are rechargeable batteries that use sodium ions as charge carriers. Compared to traditional lithium-ion batteries, the main advantages of sodium-ion batteries are the abundance, low cost, and wide distribution of sodium resources. The working principle of sodium-ion batteries is similar to that of lithium-ion batteries, storing and releasing energy through the movement of sodium ions between the positive and negative electrodes. Due to the larger volume of sodium ions, the energy density of sodium-ion batteries is generally lower than that of lithium-ion batteries. However, in the field of large-scale energy storage, sodium-ion batteries show great potential due to their cost advantages and safety. With technological advancements, the performance of sodium-ion batteries is gradually improving, and they are expected to play an important role in the future energy storage market.

[0003] The current state of research on sodium-ion battery anode materials indicates that carbon-based materials have become the main research direction due to their abundant resources, low cost, high reversible capacity, and good cycle stability. Hard carbon materials, with their well-developed nanopores and inter-particle voids, increase the active sites for sodium ion storage, and the pore adsorption effect can improve the rate performance of carbon materials. Soft carbon materials have higher carbon content and commercial potential, but the tendency for graphitization during high-temperature carbonization can affect sodium ion storage. In addition to carbon materials, researchers are also exploring non-carbon materials such as titanium-based compounds, alloy materials, metal compounds, and organic compounds. Although these materials have high theoretical specific capacity, their cycle performance is poor due to problems such as low conductivity, large volume change, and easy pulverization. Current research focuses on improving the first-cycle coulombic efficiency, improving voltage hysteresis, and cycle stability.

[0004] High-sulfur petroleum coke, referred to as high-sulfur coke in this invention, is a byproduct of petroleum refining, typically containing a sulfur content of 3% wt or higher. This coke appears as a dark brown, porous, irregularly shaped solid, resembling a sponge, and is therefore sometimes called sponge coke. Due to its high sulfur content, high-sulfur coke is primarily used in chemical production or as fuel in industries such as metal casting and glass manufacturing. In the electrochemical industry, the relatively low-cost high-sulfur coke has not yet achieved high-value-added applications.

[0005] For example, Chinese patent CN115818617B discloses a method for preparing anode active materials for sodium-ion batteries using high-sulfur coke. High-sulfur coke and transition metal salts are pre-ammoniated and roasted in an ammonia-containing atmosphere, then calcined under negative pressure, followed by washing and drying to obtain a high-sulfur-based anode active material. The sulfur content in the high-sulfur coke is 3.5~8 wt.%; the weight ratio of high-sulfur coke to transition metal salt is 100:2~20; the temperature of the ammoniation and roasting stage is 500~700℃; the calcination temperature is 800~1200℃; the transition metal salt is at least one of iron salt, cobalt salt, nickel salt, and manganese salt; the volume content of ammonia in the ammonia-containing atmosphere is 5~20%; the ammoniation and roasting stage is carried out under normal pressure; the ammoniation and roasting time is 2~6 hours; the negative pressure is 20~500 Pa; and the calcination time is 2~4 hours. The battery assembled with the electrode material prepared by this method has a maximum specific capacity of 276 mAh / g and a capacity retention rate of 93.3% after 500 cycles.

[0006] Therefore, there is an urgent need to develop a new method for preparing high-sulfur coke-based sodium-ion battery anode materials to achieve high initial coulombic efficiency and high cycle retention rate in sodium-ion batteries. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a method for preparing and applying a high-sulfur coke-based sodium-ion battery anode material. The preparation scheme for the sodium-ion battery anode material provided by this invention utilizes a specific processing technology to prepare a high-performance sodium-ion battery anode material. Sodium-ion batteries using this anode material as the electrode exhibit initial coulombic efficiency and high cycle retention; thus expanding the application of high-sulfur coke in the electrochemical field.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A method for preparing a high-sulfur coke-based sodium-ion battery anode material, characterized by comprising the following steps:

[0010] (1) Mix the crushed high-sulfur coke with copper chloride solution in a certain proportion and impregnate it; after impregnation, filter and wash until the filtrate is neutral and dry it;

[0011] (2) The high-sulfur coke obtained in step (1) is subjected to two-stage heat treatment in an argon gas environment. The first stage of heat treatment involves rapidly heating the coke to 900~1100℃ and holding it at that temperature for a period of time. The second stage of heat treatment involves heating the coke to 2200~3000℃ again, based on the temperature reached in the first stage of heat treatment, and holding it at that temperature for a period of time.

[0012] (3) After cooling the high-sulfur coke obtained in step (2), it is acid washed with hydrochloric acid. After acid washing, it is filtered, washed until the filtrate is neutral, and then dried.

[0013] (4) The material obtained from step (3) is ball-milled to a particle size of 5~10μm to obtain the high-sulfur coke-based sodium-ion battery anode material.

[0014] Furthermore, the copper chloride solution contains 10% to 30% copper chloride by mass.

[0015] Furthermore, the particle size of the high-sulfur coke after crushing in step (1) is 0.05~0.1mm.

[0016] Furthermore, in step (1), the mass ratio of high-sulfur coke to copper chloride solution is 1:2 to 1:6.

[0017] Furthermore, in step (1), the immersion time of the high-sulfur coke in the copper chloride solution is 10 to 15 hours.

[0018] Furthermore, in step (2), the heating rate of the first stage of rapid heat treatment is 10~50℃ / min.

[0019] Furthermore, in step (2), after the first stage of heat treatment is heated to the target temperature, the holding time is 1 to 2.5 hours.

[0020] Furthermore, in step (2), after the second stage of heat treatment is heated to the target temperature, the holding time is 2 to 4 hours.

[0021] The present invention also provides a high-sulfur coke-based sodium-ion battery anode material, which is prepared using the above-described method.

[0022] This invention also provides an application of a high-sulfur coke-based sodium-ion battery anode material, which is used as an anode active material in the preparation of sodium-ion batteries.

[0023] By adopting the above technical solution, this invention, as an example, has the following advantages and positive effects compared with the prior art:

[0024] The high-sulfur coke-based sodium-ion battery anode material prepared by the preparation method provided by the present invention produces a sodium-ion battery with high discharge capacity and cycle retention rate, with a capacity retention rate of 94.1% after 1000 cycles.

[0025] The preparation method provided by this invention employs rapid heating to calcine high-sulfur coke, causing it to crack and generate pores, and removing organic sulfur phases from the high-sulfur coke that are difficult to match the requirements of sodium-ion batteries; wherein, the addition of copper chloride further promotes sulfur removal at high temperature, and the final desulfurization rate can reach 95.3%;

[0026] The preparation method provided by the present invention shrinks the pores through high-temperature treatment, thereby increasing the closed-pore ratio. The resulting material has a low specific surface area and is suitable for use as a negative electrode material for sodium-ion batteries.

[0027] The material prepared by the method provided by this invention has high discharge capacity and high capacity retention, and expands the application of high-sulfur coke in the field of electrochemistry. These characteristics and advantages make it a promising candidate for use as a negative electrode material for sodium-ion batteries. Attached Figure Description

[0028] Figure 1 The charge-discharge curve of a sodium-ion battery made from the high-sulfur coke-based sodium-ion battery anode material prepared in Example 5 is provided for the present invention. Detailed Implementation

[0029] The preparation method and application of the high-sulfur coke-based sodium-ion battery anode material disclosed in this invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] Techniques, methods, and apparatus known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and apparatus should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0031] Explanation of technical terms:

[0032] Specific capacity (mAh / g): refers to the electrical energy that a unit mass of battery material can store and release, usually expressed in milliampere-hours per gram. Specific capacity is one of the important indicators for evaluating battery performance, reflecting the energy density and energy storage capacity of a battery under specific conditions.

[0033] First-cycle coulombic efficiency (CCOE) is the ratio of the amount of electricity released during discharge to the amount of electricity input during charging in the first charge-discharge cycle of a battery. It is usually expressed as a percentage. CCOE is an important indicator for evaluating battery performance and cycle stability, especially in rechargeable batteries such as lithium-ion and sodium-ion batteries.

[0034] Capacity retention after 1000 cycles: This refers to the ratio of the battery's remaining capacity to its initial capacity after 1000 charge-discharge cycles. This metric reflects the battery's performance stability and durability after prolonged use, and is usually expressed as a percentage. Example 1

[0035] It should be noted that the sulfur content of the high-sulfur coke used in the embodiments of the present invention is 4-8 wt%.

[0036] The high-sulfur coke raw material was crushed in a crusher and then sieved using a screening machine. 10g of high-sulfur coke particles with a median particle size of 0.05mm were collected for later use. 6g of copper chloride was weighed and dissolved in 24g of deionized water, stirred until completely dissolved, yielding a 20wt% copper chloride solution. 10g of the high-sulfur coke particles were immersed in the copper chloride solution, stirred until homogeneous, and stirred continuously for 12 hours. After immersion, the mixture was filtered using a Buchner funnel. After filtration, the high-sulfur coke particles were rinsed with deionized water to remove the copper chloride solution from the particle surface until the filtrate was neutral. The filtered high-sulfur coke particles were then dried in an oven.

[0037] The dried high-sulfur coke particles were placed in a high-temperature tubular furnace, and argon gas was introduced. The temperature was increased to 1000℃ at a rate of 30℃ / min and held for 2 hours; then increased to 2500℃ at a rate of 2℃ / min and held for 3 hours. After heat treatment, the high-sulfur coke particles were cooled and placed in a Buchner funnel. They were first rinsed with hydrochloric acid, then with deionized water until the filtrate was neutral. After filtration, the filtrate was dried in an oven. The resulting material was then ball-milled at 300 rpm for 2 hours to obtain the high-sulfur coke-based sodium-ion battery anode material.

[0038] The high-sulfur coke-based sodium-ion battery anode material prepared in this embodiment was assembled into a sodium-ion battery in an argon-filled glove box and its electrochemical performance was tested. The specific capacity of the hard carbon anode material reached 291.2 mAh / g, the initial coulombic efficiency was 85.7%, and the capacity retention rate was 94.1% after 1000 cycles. Example 2

[0039] The high-sulfur coke raw material was crushed in a crusher and sieved through a screening machine. 10g of high-sulfur coke particles with a median particle size of 0.05mm were collected for later use. 5g of copper chloride was weighed and dissolved in 45g of deionized water. The solution was stirred until completely dissolved, yielding a 10wt% copper chloride solution. 10g of high-sulfur coke particles were immersed in the copper chloride solution, stirred until homogeneous, and stirred continuously for 10 hours. After immersion, the mixture was filtered using a Buchner funnel. After filtration, the high-sulfur coke particles were rinsed with deionized water to remove the copper chloride solution from the particle surface until the filtrate was neutral. The filtered high-sulfur coke particles were then dried in an oven.

[0040] The dried high-sulfur coke particles were placed in a high-temperature tubular furnace, and argon gas was introduced. The temperature was increased to 1000℃ at a rate of 30℃ / min and held for 2 hours; then increased to 2800℃ at a rate of 2℃ / min and held for 4 hours. After heat treatment, the high-sulfur coke particles were cooled and placed in a Buchner funnel. They were first rinsed with hydrochloric acid, then with deionized water until the filtrate was neutral. After filtration, the filtrate was dried in an oven. The resulting material was then ball-milled at 300 rpm for 2 hours to obtain the high-sulfur coke-based sodium-ion battery anode material.

[0041] The high-sulfur coke-based sodium-ion battery anode material prepared in this embodiment was assembled into a sodium-ion battery in an argon-filled glove box and its electrochemical performance was tested. The specific capacity of the hard carbon anode material reached 287.7 mAh / g, the initial coulombic efficiency was 80.3%, and the capacity retention rate was 94.2% after 1000 cycles. Example 3

[0042] The high-sulfur coke raw material was crushed in a crusher and sieved through a screening machine. 10g of high-sulfur coke particles with a median particle size of 0.1mm were collected for later use. 10g of copper chloride was weighed and dissolved in 40g of deionized water, stirred until completely dissolved, yielding a 20wt% copper chloride solution. The 10g of high-sulfur coke particles were then immersed in the copper chloride solution, stirred until homogeneous, and stirred continuously for 14 hours. After immersion, the mixture was filtered using a Buchner funnel. After filtration, the high-sulfur coke particles were rinsed with deionized water to remove the copper chloride solution from the particle surface until the filtrate was neutral. The filtered high-sulfur coke particles were then dried in an oven.

[0043] The dried high-sulfur coke particles were placed in a high-temperature tubular furnace, and argon gas was introduced. The temperature was increased to 900℃ at a rate of 10℃ / min and held for 1.5 hours; then increased to 3000℃ at a rate of 2℃ / min and held for 3 hours. After heat treatment, the high-sulfur coke particles were cooled and placed in a Buchner funnel. They were first rinsed with hydrochloric acid, then with deionized water until the filtrate was neutral. After filtration, the filtrate was dried in an oven. The resulting material was then ball-milled at 300 rpm for 2 hours to obtain the high-sulfur coke-based sodium-ion battery anode material.

[0044] The high-sulfur coke-based sodium-ion battery anode material prepared in this embodiment was assembled into a sodium-ion battery in an argon-filled glove box and its electrochemical performance was tested. The specific capacity of the hard carbon anode material reached 284.3 mAh / g, the initial coulombic efficiency was 82.3%, and the capacity retention rate was 93.4% after 1000 cycles. Example 4

[0045] The high-sulfur coke raw material was crushed in a crusher and sieved through a screening machine. 10g of high-sulfur coke particles with a median particle size of 0.05mm were collected for later use. 10g of copper chloride was weighed and dissolved in 40g of deionized water, stirred until completely dissolved, yielding a 20wt% copper chloride solution. The 10g of high-sulfur coke particles were immersed in the copper chloride solution, stirred until homogeneous, and stirred continuously for 12 hours. After immersion, the mixture was filtered using a Buchner funnel. After filtration, the high-sulfur coke particles were rinsed with deionized water to remove the copper chloride solution from the particle surface until the filtrate was neutral. The filtered high-sulfur coke particles were then dried in an oven.

[0046] The dried high-sulfur coke particles were placed in a high-temperature tubular furnace, and argon gas was introduced. The temperature was raised to 1100℃ at a rate of 40℃ / min and held for 2.5 hours; then raised to 2200℃ at a rate of 2℃ / min and held for 2 hours. After heat treatment, the high-sulfur coke particles were cooled and placed in a Buchner funnel. They were first rinsed with hydrochloric acid, then with deionized water until the filtrate was neutral. After filtration, the filtrate was dried in an oven. The resulting material was then ball-milled at 300 rpm for 2 hours to obtain the high-sulfur coke-based sodium-ion battery anode material.

[0047] The high-sulfur coke-based sodium-ion battery anode material prepared in this embodiment was assembled into a sodium-ion battery in an argon-filled glove box and its electrochemical performance was tested. The specific capacity of the hard carbon anode material reached 298.9 mAh / g, the initial coulombic efficiency was 79.8%, and the capacity retention rate was 92.5% after 1000 cycles. Example 5

[0048] The high-sulfur coke raw material was crushed in a crusher and sieved through a screening machine. 10g of high-sulfur coke particles with a median particle size of 0.05mm were collected for later use. 10g of copper chloride was weighed and dissolved in 40g of deionized water, stirred until completely dissolved, yielding a 20wt% copper chloride solution. The 10g of high-sulfur coke particles were immersed in the copper chloride solution, stirred until homogeneous, and stirred continuously for 12 hours. After immersion, the mixture was filtered using a Buchner funnel. After filtration, the high-sulfur coke particles were rinsed with deionized water to remove the copper chloride solution from the particle surface until the filtrate was neutral. The filtered high-sulfur coke particles were then dried in an oven.

[0049] The dried high-sulfur coke particles were placed in a high-temperature tubular furnace, and argon gas was introduced. The temperature was increased to 1000℃ at a rate of 30℃ / min and held for 2 hours; then increased to 2500℃ at a rate of 2℃ / min and held for 3 hours. After heat treatment, the high-sulfur coke particles were cooled and placed in a Buchner funnel. They were first rinsed with hydrochloric acid, then with deionized water until the filtrate was neutral. After filtration, the filtrate was dried in an oven. The resulting material was then ball-milled at 300 rpm for 2 hours to obtain the high-sulfur coke-based sodium-ion battery anode material.

[0050] The high-sulfur coke-based sodium-ion battery anode material prepared in this embodiment was assembled into a sodium-ion battery in an argon-filled glove box and its electrochemical performance was tested. The specific capacity of the hard carbon anode material reached 297.8 mAh / g, the initial coulombic efficiency was 82.6%, and the capacity retention rate was 94.1% after 1000 cycles.

[0051] Comparative Example

[0052] The raw material, high-sulfur coke, was crushed in a crusher and then sieved through a screening machine. 10g of high-sulfur coke particles with a median particle size of 0.05mm were collected for later use. The 10g of high-sulfur coke particles were placed in a Buchner funnel, rinsed with deionized water, and then dried in an oven after filtration.

[0053] The dried high-sulfur coke particles were placed in a high-temperature tubular furnace, argon gas was introduced, and the temperature was raised to 1000℃ at a rate of 5℃ / min and held for 2 hours; then the temperature was raised to 2500℃ at a rate of 2℃ / min and held for 3 hours. After heat treatment, the high-sulfur coke particles were cooled, placed in a Buchner funnel, and washed with deionized water until the filtrate was neutral. After filtration, the filtrate was placed in an oven to dry. After drying, the resulting material was ball-milled at 300 rpm for 2 hours to obtain the high-sulfur coke-based sodium-ion battery anode material.

[0054] The high-sulfur coke-based sodium-ion battery anode material prepared in this comparative example was assembled into a sodium-ion battery and its electrochemical performance was tested. The specific capacity of this hard carbon anode material reached 261.5 mAh / g, the initial coulombic efficiency was 70.1%, and the capacity retention rate after 1000 cycles was 83.8%. See Table 1 for a performance comparison of the sodium-ion batteries obtained in Example 5 and the comparative example.

[0055]

[0056] As can be seen from the table above, due to the use of copper chloride impregnation and two-stage heat treatment processes in this invention, the sodium-ion battery assembled from the high-sulfur coke-based sodium-ion battery anode material prepared in Example 5 has a higher specific capacity, a higher initial coulombic efficiency, and a better capacity retention rate, indicating that the battery has better charge-discharge performance and energy storage performance.

[0057] See Figure 1The figure shows the charge-discharge curves of a sodium-ion battery made from the high-sulfur coke-based sodium-ion battery anode material prepared in Example 5 of this invention. As can be seen from the figure, the discharge curve of this sodium-ion battery has a steep initial section, indicating that the battery can be charged relatively quickly. During the discharge process, the charge-discharge plateau is wide, indicating that the battery has voltage stability and can provide continuous current output. The discharge curve of this battery remains stable near the cutoff voltage, which can effectively protect the battery.

[0058] The high-sulfur coke-based sodium-ion battery anode material provided by this invention can be used in the preparation of sodium-ion batteries. In addition, this material can also be applied in electric vehicles, energy storage systems, and portable electronic devices.

[0059] Other technical features are described in the preceding embodiments and will not be repeated here.

[0060] In the foregoing description, the disclosure of this invention is not intended to limit itself to these aspects. Rather, within the scope of the objectives of this disclosure, components can be selectively and operationally combined in any number. All technical, scientific, or other terms are to be understood by those skilled in the art, unless they are defined to the contrary. Public terms found in dictionaries should not be interpreted in the context of the relevant technical documents in an overly idealistic or impractical manner, unless expressly defined as such in this disclosure. Any modifications or alterations made by those skilled in the art based on the foregoing disclosure are within the scope of the claims.

Claims

1. A method for preparing a high-sulfur pyrro l-based sodium-ion battery anode material, characterized in that The method comprises the steps of: (1) mixing and impregnating the crushed high-sulfur coke with a copper chloride solution according to a certain proportion; after the impregnation is completed, the mixture is filtered, washed until the filtrate is neutral, and dried; (2) performing two-stage heat treatment on the high-sulfur coke obtained in step (1) in an argon gas environment, wherein the first-stage heat treatment is rapidly heated to 900-1100 DEG C, and the second-stage heat treatment is heated to 2200-3000 DEG C based on the temperature reached in the first-stage heat treatment, and the mixture is kept at the temperature for a period of time; (3) cooling the high-sulfur coke obtained in step (2) after the roasting, and then performing acid washing with hydrochloric acid; after the acid washing, the mixture is filtered, washed until the filtrate is neutral, and dried; (4) ball-milling the material obtained in step (3) to a particle size of 5-10 μm, thereby obtaining a high-sulfur coke-based sodium-ion battery negative electrode material.

2. The method of claim 1, wherein: The mass fraction of copper chloride in the copper chloride solution is 10%-30%.

3. The method of claim 1, wherein: The particle size of the crushed high-sulfur coke in step (1) is 0.05-0.1 mm.

4. The method of claim 1, wherein: The mass ratio of the high-sulfur coke to the copper chloride solution in step (1) is 1:2-1:

6.

5. The method of claim 1, wherein: The impregnation time of the high-sulfur coke in the copper chloride solution in step (1) is 10-15 hours.

6. The method of claim 1, wherein: The heating rate of the first-stage heat treatment in step (2) is 10-50 DEG C / min.

7. The method of claim 1, wherein: After the first-stage heat treatment in step (2) is heated to the target temperature, the mixture is kept at the temperature for 1-2.5 hours.

8. The method of claim 1, wherein: After the second-stage heat treatment in step (2) is heated to the target temperature, the mixture is kept at the temperature for 2-4 hours.

9. A high-sulfur pyrro!idinium-based sodium-ion battery anode material, characterized in that: The material is prepared according to the preparation method in any one of claims 1-8.

10. Use of a high-sulfur pyrrolium-based sodium-ion battery anode material prepared according to the method of any one of claims 1-8, characterized in that: The material is used as a negative electrode active material to prepare a sodium-ion battery.

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