Pyrolytic carbon black-molybdenum disulfide composite material and preparation method and application thereof

Abstract

The embodiment of the invention provides a pyrolytic carbon black-molybdenum disulfide composite material and a preparation method and application thereof.The preparation method comprises the steps that waste tire rubber powder is subjected to pyrolysis carbonization treatment twice in different gas environments, and pyrolytic carbon black to be treated is obtained; placing the to-be-treated pyrolytic carbon black in deionized water, and performing ultrasonic dispersion treatment to obtain a pyrolytic carbon black suspension; sequentially adding a solution containing molybdenum ions and a solution containing sulfur ions into the pyrolytic carbon black suspension to obtain a first mixed solution containing molybdenum disulfide; and carrying out hydrothermal reaction on the first mixture, and then carrying out separation and extraction to anchor the molybdenum disulfide on the surface of the to-be-treated pyrolytic carbon black, thereby obtaining the composite material. The waste tire rubber powder is used as a raw material, after two times of pyrolysis and carbonization in different gas environments, MoS is anchored on the surface of carbon black in cooperation with a hydrothermal reaction, volume expansion and agglomeration of MoS are effectively inhibited, the conductivity of the composite material can be improved, and the cycle and rate performance can be optimized.

Description

Technical Field

[0001] This disclosure relates to the field of power battery technology, and in particular to pyrolytic carbon black-molybdenum disulfide composite materials, their preparation methods, and applications. Background Technology

[0002] Against the backdrop of a growing global energy crisis and environmental problems, efficient energy storage technology has become crucial for supporting the large-scale application of renewable energy. Sodium-ion batteries, due to their abundant and widely distributed sodium resources, low cost, and electrochemical performance similar to lithium-ion batteries, are considered one of the most promising candidate technologies for next-generation large-scale energy storage. As a core component of sodium-ion batteries, the performance of the anode material directly determines the battery's energy density, cycle life, and rate capability. Therefore, developing high-performance, low-cost sodium-ion battery anode materials has become a key research focus.

[0003] Transition metal sulfides, with their abundant resources, excellent safety performance, and high theoretical specific capacity, have shown broad application prospects in the field of sodium-ion battery anode materials. Among them, molybdenum disulfide (MoS2) has become a research hotspot in this field due to its unique two-dimensional layered graphene-like crystal structure. In its crystal structure, Mo atoms are bonded to the upper and lower S atoms through strong covalent bonds to form an S-Mo-S sandwich structure, while adjacent sandwiches are connected by relatively weak van der Waals forces. This structural feature gives MoS2 a large interlayer spacing, providing ample channels for the insertion and extraction of sodium ions. At the same time, its theoretical specific capacity is as high as 670 mAh・g⁻¹, far exceeding that of traditional carbon-based anode materials, laying the foundation for improving the energy density of sodium-ion batteries.

[0004] However, when MoS2 is used as an anode material for sodium-ion batteries, the following problems exist: During charge-discharge cycles, MoS2 undergoes significant volume expansion due to the repeated insertion and extraction of sodium ions, leading to electrode structure cracking and pulverization, thus compromising electrode integrity. Due to the weak interlayer van der Waals forces, MoS2 nanosheets are prone to aggregation and accumulation during preparation and charge-discharge processes, which not only reduces sodium ion transport channels and active sites but also exacerbates the volume expansion effect, ultimately resulting in a significant decrease in battery cycle performance and rate performance. MoS2 itself has low inherent conductivity, significantly hindering electron transport efficiency within the electrode and affecting sodium ion diffusion kinetics, further limiting the battery's rate charge-discharge capability. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of this disclosure is to provide pyrolytic carbon black-molybdenum disulfide composite materials, their preparation methods and applications, and to solve the problems in the related technologies.

[0006] The first aspect of this disclosure provides a method for preparing a pyrolytic carbon black-molybdenum disulfide composite material, comprising:

[0007] Waste tire rubber powder was subjected to two pyrolysis and carbonization treatments under different gas environments to obtain pyrolytic carbon black to be treated;

[0008] The pyrolytic carbon black to be treated was placed in deionized water and then subjected to ultrasonic dispersion treatment to obtain a pyrolytic carbon black suspension.

[0009] A solution containing molybdenum ions and a solution containing sulfur ions are added sequentially to the pyrolytic carbon black suspension to obtain a first mixed solution containing molybdenum disulfide.

[0010] After the first mixture is subjected to a hydrothermal reaction, it is separated and extracted to anchor the molybdenum disulfide onto the surface of the pyrolytic carbon black to be treated, thereby obtaining a composite material.

[0011] In the first aspect of the embodiment, the two-stage pyrolysis and carbonization treatment of waste tire rubber powder under different gas environments to obtain pyrolytic carbon black includes:

[0012] The waste tire rubber powder is placed in a tube furnace under an inert atmosphere and heated to the first target temperature, then kept at a constant temperature and cooled to room temperature to obtain preliminary pyrolytic carbon black.

[0013] The preliminary pyrolytic carbon black is placed in an acidic mixed solution and stirred, filtered, washed with water and dried to remove inorganic impurities from the preliminary pyrolytic carbon black, thereby obtaining purified pyrolytic carbon black.

[0014] The purified pyrolytic carbon black is placed again in a tube furnace under a mixed inert atmosphere and heated to the second target temperature, then kept at a constant temperature and cooled to room temperature to obtain the pyrolytic carbon black to be treated.

[0015] In the first aspect of the embodiment, the amount of waste tire rubber powder used is 5-10g, the first target temperature is 700℃-800℃, the second target temperature is 700℃-800℃, the constant temperature time is 2-4 hours, and the heating rate of the tubular furnace in both instances is 5~10℃·min. -1 .

[0016] In the first aspect of the embodiment, the pyrolysis carbonization treatment is performed at 5~10 °C·min. -1 The temperature is raised to 700-800℃ and then held at that temperature for 2-4 hours.

[0017] In the first aspect of the embodiment, when the amount of waste tire rubber powder is 5-10g, the step of sequentially adding a mixed solution containing molybdenum ions and sulfur ions to the pyrolytic carbon black suspension to obtain a first mixed solution containing molybdenum disulfide includes:

[0018] The pyrolytic carbon black suspension was placed on a magnetic stirrer, and 0.177 g of ammonium molybdate tetrahydrate solution was added and stirred to dissolve the molybdenum ions.

[0019] 0.228 g of thiourea was added to a mixed solution containing molybdenum ions and stirred to dissolve, thus obtaining the first mixed solution containing molybdenum disulfide.

[0020] In an embodiment of the first aspect, the process of separating and extracting the first mixed fusion after hydrothermal reaction includes centrifugation, rinsing, and drying; wherein the centrifugation and rinsing are performed alternately using deionized water and ethanol.

[0021] In an embodiment of the first aspect, the hydrothermal reaction is carried out at a temperature of 160-200°C for 16-24 hours.

[0022] In an embodiment of the first aspect, the ultrasonic dispersion treatment takes 20-30 minutes.

[0023] The second aspect of this disclosure provides a pyrolytic carbon black-molybdenum disulfide composite material, wherein it is prepared by the preparation method described in any one of the first aspects above.

[0024] The third aspect of this disclosure provides the use of a pyrolytic carbon black-molybdenum disulfide composite material prepared by the preparation method described in any one of the first aspects above, wherein it is used as a negative electrode material for sodium-ion batteries.

[0025] The beneficial effects of this disclosure are: using waste tire rubber powder as raw material, after two pyrolysis and carbonization processes in different gas environments, combined with hydrothermal reaction, MoS2 is anchored on the surface of carbon black, which effectively inhibits the volume expansion and agglomeration of MoS2, and can also improve the electrical conductivity of composite materials and optimize cycle and rate performance. Attached Figure Description

[0026] Figure 1 A schematic diagram illustrating the overall process of preparing a pyrolytic carbon black-molybdenum disulfide composite material according to an embodiment of this disclosure is shown.

[0027] Figure 2 This diagram illustrates the overall process flow of step S1 in the preparation method of pyrolytic carbon black-molybdenum disulfide composite material in one embodiment of this disclosure.

[0028] Figure 3 This diagram illustrates the overall process flow of step S3 in the preparation method of pyrolytic carbon black-molybdenum disulfide composite material in one embodiment of this disclosure.

[0029] Figure 4 A scanning electron microscope (SEM) image of the composite material in the pyrolytic carbon black-molybdenum disulfide composite material of one embodiment of the present disclosure is shown.

[0030] Figure 5 A transmission electron microscope (TEM) image of the composite material in the pyrolytic carbon black-molybdenum disulfide composite material of one embodiment of the present disclosure is shown.

[0031] Figure 6 The diagram illustrates the cycle performance of a pyrolytic carbon black-molybdenum disulfide composite material used as a negative electrode in a sodium-ion battery, according to one embodiment of this disclosure.

[0032] Figure 7 The diagram shows the specific capacity performance curve of Example 1 in one embodiment of this disclosure after 100 cycles.

[0033] Figure 8 The diagram shows the specific capacity performance curve of Example 2 in one embodiment of this disclosure after 100 cycles.

[0034] Figure 9 The diagram shows the specific capacity performance curve of Example 3 in one embodiment of this disclosure after 100 cycles.

[0035] Figure 10 The diagram shows the specific capacity performance curve of Example 4 in one embodiment of this disclosure after 100 cycles.

[0036] Figure 11 The diagram shows the specific capacity performance curve of Example 5 in one embodiment of this disclosure after 100 cycles.

[0037] Figure 12 The first-cycle specific capacity of 0.1 A·g⁻¹ and the 100-cycle specific capacity of 2 A·g⁻¹ are shown in one embodiment of this disclosure, namely Examples 1-5. Detailed Implementation

[0038] The following specific examples illustrate the implementation of this disclosure. Those skilled in the art can easily understand other advantages and effects of this disclosure from the information disclosed herein. This disclosure can also be implemented or applied through other different specific embodiments, and various details in this disclosure can be modified or changed according to different viewpoints and application modules without departing from the spirit of this disclosure. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this disclosure can be combined with each other.

[0039] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings, so that those skilled in the art to which this disclosure pertains can readily implement it. This disclosure may be embodied in many different forms and is not limited to the embodiments described herein.

[0040] In this disclosure, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic represented in connection with that embodiment or example is included in at least one embodiment or example of this disclosure. Furthermore, the specific features, structures, materials, or characteristics represented may be combined in any suitable manner in any one or a group of embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples represented in this disclosure, as well as the features of those different embodiments or examples.

[0041] Furthermore, the terms "first" and "second" are used for illustrative purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the representation of this disclosure, "a set" means two or more, unless otherwise explicitly specified.

[0042] For the purpose of clarity, devices unrelated to the description are omitted, and the same or similar components throughout the specification are given the same reference numerals.

[0043] Throughout this specification, when it is said that a device is "connected" to another device, this includes not only "direct connection" but also "indirect connection" by placing other components in between. Furthermore, when it is said that a device "comprises" a certain constituent element, unless otherwise stated otherwise, this does not exclude other constituent elements, but rather implies that other constituent elements may be included.

[0044] While the terms first, second, etc., are used in some examples herein to refer to various elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another. For example, first interface and second interface, etc., are used. Furthermore, as used herein, the singular forms “a,” “an,” and “the” are intended to also include the plural forms unless the context indicates otherwise. It should be further understood that the terms “comprising,” “including,” indicate the presence of features, steps, operations, elements, modules, items, kinds, and / or groups, but do not exclude the presence, occurrence, or addition of one or more other features, steps, operations, elements, modules, items, kinds, and / or groups. The terms “or” and “and / or” as used herein are interpreted as inclusive, or mean any one or any combination thereof. Thus, “A, B, or C” or “A, B, and / or C” means “any one of: A; B; C; A and B; A and C; B and C; A, B, and C.” Exceptions to this definition will only occur if the combination of elements, functions, steps, or operations is inherently mutually exclusive in some way.

[0045] The technical terms used herein are for reference only to specific embodiments and are not intended to limit the scope of this disclosure. The singular form used herein includes the plural form unless the statement explicitly indicates otherwise. The word "comprising" as used in this specification means to specify a particular characteristic, region, integer, step, operation, element, and / or component, and does not exclude the presence or addition of other characteristics, regions, integers, steps, operations, elements, and / or components.

[0046] Although not explicitly defined, all terms, including technical and scientific terms used herein, shall have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. Terms defined in commonly used dictionaries shall be further interpreted as having a meaning consistent with the relevant technical literature and the message of the present disclosure, and shall not be over-interpreted as having an ideal or overly formulaic meaning unless otherwise defined.

[0047] In the industrialization of sodium-ion batteries, the performance and cost of anode materials are the core limiting factors. Among related technologies, carbon-based anode materials suffer from problems such as low actual specific capacity, high energy consumption at high temperatures, high cost, and difficulty in large-scale production. Although transition metal sulfides (such as MoS2) have high theoretical specific capacity and suitable interlayer spacing for sodium ion insertion and extraction, they are prone to nanosheet aggregation, significant volume expansion during charge and discharge, and low inherent conductivity, requiring additional conductivity modification. Alloy materials, on the other hand, suffer from extremely poor cycle stability due to severe volume expansion.

[0048] Meanwhile, a large amount of waste tires are generated globally each year. Traditional disposal methods (such as landfill and incineration) not only occupy land resources but also release toxic substances such as polycyclic aromatic hydrocarbons and dioxins, causing soil and air pollution; while the high-value utilization of its solid byproducts (waste tire rubber powder) has always been an industry challenge. In related technologies, it is mostly used as a low-end filler (such as road paving and rubber recycling), with low added value.

[0049] To address the aforementioned technical problems, one embodiment of this disclosure provides a method for preparing a pyrolytic carbon black-molybdenum disulfide composite material. This method uses carbon black, a solid byproduct of waste tires, and MoS2 as core raw materials, and anchors MoS2 nanosheets onto the surface of the pyrolytic carbon black through a hydrothermal process. The introduction of pyrolytic carbon black significantly enhances the electrical conductivity of the composite material. Its inherent three-dimensional cross-linked structure forms an interactive network with the MoS2 nanosheets, synergistically accelerating the electron and ion transport rates. The strong interaction between the two materials effectively reduces the aggregation of MoS2 nanosheets, providing more active sites for sodium ion storage. Simultaneously, the addition of MoS2 significantly improves the sodium storage capacity of the composite material, enabling it to exhibit excellent electrochemical performance when applied as a negative electrode in sodium-ion batteries.

[0050] Specifically, in Figure 1In the embodiments, the preparation method includes:

[0051] Step S1: The waste tire rubber powder is subjected to two pyrolysis and carbonization treatments under different gas environments to obtain the pyrolysis carbon black to be treated.

[0052] Figure 2 The example details step S1, which aims to remove volatile organic compounds and inorganic impurities from waste tire rubber powder, ultimately obtaining pyrolytic carbon black with superior purity and structural properties. Specifically:

[0053] Step S11: Place the waste tire rubber powder in a tube furnace under an inert atmosphere and heat it to the first target temperature, then keep it at a constant temperature and cool it to room temperature to obtain preliminary pyrolytic carbon black.

[0054] Waste tire rubber powder is loaded into a magnetic boat, which is then placed in a tube furnace. The tube furnace is heated at a set rate until the temperature inside reaches 700°C. After reaching the target temperature, it is kept constant for a period of time before cooling begins. Argon gas is introduced as a protective atmosphere throughout the pyrolysis, constant temperature, and cooling processes to prevent the rubber powder from burning or oxidizing. After the tube furnace cools naturally to room temperature, the solid product in the magnetic boat is removed, which is the preliminary pyrolytic carbon black, namely CBP-800.

[0055] Optionally, an inert atmosphere (such as N2 or Ar) is used to prevent the rubber from oxidizing and burning. If oxygen is present, carbon will be oxidized to CO2 / CO and lost, and carbon black cannot be formed; an inert atmosphere only allows the organic components (hydrocarbons) to undergo thermal decomposition, generating small molecule organics (such as methane and tar) and volatilizing, leaving behind the carbon skeleton, i.e., the initial carbon black.

[0056] Step S12: The preliminary pyrolytic carbon black is placed in an acidic mixed solution and stirred, filtered, washed with water and dried to remove inorganic impurities from the preliminary pyrolytic carbon black and obtain purified pyrolytic carbon black.

[0057] Specifically, in some embodiments, to remove inorganic impurities (such as zinc oxide, calcium carbonate, silicon dioxide, etc.) from CBp-800, the CBp-800 sample is subjected to combined acid washing in hydrochloric acid (HCl) and hydrofluoric acid (HF), respectively. After acid washing, the sample is filtered to separate the carbon black solid from the acid solution. During the filtration process, the pH value of the filtrate is continuously monitored. When the pH value of the filtrate reaches 7.0 (neutral), washing is stopped. Finally, the purified carbon black sample is placed in an oven and dried overnight to obtain purified pyrolytic carbon black, i.e., TCBp-800.

[0058] The purpose of stirring is to ensure sufficient contact between the pyrolytic carbon black and the mixed acid, preventing undissolved impurities and improving impurity removal efficiency. Filtration separates the purified pyrolytic carbon black from the acid solution containing impurities, preventing impurities from re-adhering to the carbon black surface. Water washing removes residual acid and impurity ions, preventing the formation of salt impurities (such as CaCl2 crystals) after drying. Blow-air drying removes moisture, preparing for the next stage of secondary pyrolysis (if water is introduced into the tube furnace, evaporation at high temperatures may damage the carbon black structure and affect pyrolysis efficiency).

[0059] Step S13: Place the purified pyrolytic carbon black in a tube furnace under a mixed inert atmosphere again and heat it to the second target temperature. After maintaining the temperature, cool it to room temperature to obtain the pyrolytic carbon black to be treated.

[0060] Specifically, the dried TCBp-800 is reloaded into the magnetic boat and placed in a tube furnace. The tube furnace is heated at a set heating rate. When the furnace temperature reaches the target temperature, the atmosphere is switched to an argon / hydrogen (Ar / H2) mixed atmosphere and kept constant at this atmosphere and target temperature for a period of time. After the constant temperature is reached, heating is stopped, and the tube furnace is allowed to cool to room temperature. The product in the magnetic boat is then removed, which is the final pyrolytic carbon black, i.e., PCBp.

[0061] Optionally, the amount of waste tire rubber powder used is 5-10g, the first target temperature is 700℃-800℃, the second target temperature is 700℃-800℃, the holding time is 2-4 hours, and the heating rate of the tubular furnace in both heating cycles is 5~10℃·min. -1 .

[0062] Specifically, regarding the initial amount of rubber powder, under the premise that other conditions such as tube furnace temperature, constant temperature time, and heating rate are as consistent as possible, by comparing the yield and purity of pyrolytic carbon black with amounts of 10g and 5g, it can be determined whether the amount of rubber powder used will affect the production efficiency and cleanliness of carbon black due to differences in material bulk density and heating uniformity.

[0063] With fixed parameters such as the amount of adhesive powder, isothermal time, and heating rate, the pore structure (pore size distribution, porosity) and conductivity (resistance value) of carbon black under pyrolysis conditions of 700℃ and 800℃ were compared on a tube furnace temperature gradient. The temperature difference may affect the rate of escape of organic volatiles and the degree of graphitization of carbon matrix, thereby changing the porous characteristics and electronic conductivity of carbon black.

[0064] By comparing the impurity removal effect (residual impurity content after acid washing) and crystal order of carbon black under 2h and 4h holding times in a tube furnace, it can be verified whether a longer holding time can more fully remove organic volatiles and make carbon atoms more regularly arranged, thus clarifying the optimization boundary of holding time for carbon black purity and crystal structure.

[0065] By observing the particle morphology (particle size and surface smoothness under scanning electron microscopy) and agglomeration degree (particle aggregation distribution) of carbon black during heating rate gradients of 5℃ / min and 10℃ / min, we can investigate whether the heating rate will cause carbon black particles to break or agglomerate due to local overheating and differences in the degree of volatile matter release, and thus clarify the influence of rate on the microstructure of carbon black.

[0066] Step S2: The pyrolytic carbon black to be treated is placed in deionized water and then subjected to ultrasonic dispersion treatment to obtain a pyrolytic carbon black suspension.

[0067] Specifically, the pyrolytic carbon black to be treated is first placed in deionized water. Deionized water is chosen to avoid the interaction between ions (such as calcium and magnesium ions) or impurities in ordinary water and the surface of the pyrolytic carbon black, thus preventing the introduction of new impurities or affecting the dispersion stability of the carbon black. Subsequently, the mixed solution is subjected to ultrasonic dispersion treatment. The "cavitation effect" generated by the high-frequency vibration of ultrasound (i.e., the rapid generation and collapse of tiny bubbles in the liquid, releasing strong impact force) breaks the agglomerates formed by van der Waals forces between particles in the dry state of the pyrolytic carbon black to be treated, so that the carbon black particles are uniformly dispersed in the deionized water in the form of monodisperse or small aggregates, and finally a uniformly dispersed pyrolytic carbon black suspension is obtained.

[0068] Preferably, the ultrasonic dispersion treatment time is 20-30 minutes. If the treatment time is less than 20 minutes, the ultrasonic energy is insufficient to fully break down the carbon black agglomerates, and large, undispersed agglomerated particles may remain in the suspension, potentially leading to uneven performance in subsequent applications (such as stress concentration when preparing composite materials or conductivity fluctuations when preparing electrodes). If the treatment time exceeds 30 minutes, on the one hand, it increases the energy consumption of the ultrasonic equipment and the processing time, increasing costs; on the other hand, prolonged ultrasonic treatment may cause the temperature of deionized water to rise, and even cause slight damage to the microstructure of some carbon black particles (such as porous frameworks) due to excessive impact, thus affecting its subsequent performance. Therefore, a treatment time of 20-30 minutes can ensure sufficient dispersion of carbon black while avoiding energy waste and particle structure damage, ensuring the dispersion stability of the suspension and the structural integrity of the carbon black itself.

[0069] The ultrasonic time gradient was set according to the "single variable principle." With fixed pyrolytic carbon black dosage, deionized water volume, ultrasonic power, and other conditions, the effect of ultrasonic duration on PCBp dispersion uniformity and molybdenum disulfide anchoring was obtained by comparing 20 min and 30 min.

[0070] Step S3: A solution containing molybdenum ions and a solution containing sulfur ions are sequentially added to the pyrolytic carbon black suspension to obtain a first mixed solution containing molybdenum disulfide. The purpose is to introduce molybdenum and sulfur sources into the pyrolytic carbon black suspension, so that molybdenum disulfide (MoS2) can be generated in situ through subsequent reactions.

[0071] Optionally, in Figure 3 In this embodiment, when the amount of waste tire rubber powder is 5-10g, the step of sequentially adding a mixed solution containing molybdenum ions and sulfur ions to the pyrolytic carbon black suspension to obtain a first mixed solution containing molybdenum disulfide includes:

[0072] Step S31: Place the pyrolytic carbon black suspension on a magnetic stirrer and add 0.177g of ammonium molybdate tetrahydrate solution for stirring and dissolution to obtain the molybdenum ions.

[0073] The pyrolytic carbon black suspension was placed on a magnetic stirrer, and 0.177 g of ammonium molybdate tetrahydrate ((NH4)2MoO4・4H2O) solution was added and stirred until completely dissolved. Ammonium molybdate tetrahydrate is a commonly used soluble molybdenum source, which can dissociate into molybdenum ions such as MoO4²⁻ in aqueous solution. Magnetic stirring ensures that the molybdenum ions are uniformly dispersed in the suspension, making full contact with the pyrolytic carbon black particles and avoiding excessively high local concentrations.

[0074] Step S32: Add 0.228g of thiourea to the mixed solution containing molybdenum ions and stir to dissolve, to obtain the first mixed solution containing molybdenum disulfide.

[0075] 0.228 g of thiourea (CS(NH2)2) was added to a mixed solution containing molybdenum ions, and stirring continued until dissolved to obtain a first mixed solution containing molybdenum disulfide. Thiourea, acting as a sulfur source, decomposes under subsequent reaction conditions (such as heating) to produce S²⁻, which reacts with molybdenum ions in a stoichiometric ratio of Mo:S = 1:2 to generate MoS2. The ratio of 0.177 g of ammonium molybdate tetrahydrate to 0.228 g of thiourea precisely matches the composition ratio of MoS2 (molar ratio Mo:S ≈ 1:2), ensuring a complete reaction and reducing raw material waste or impurity residue. Magnetic stirring was continuously applied in this step to ensure uniform dissolution of thiourea and mixing with molybdenum ions and pyrolytic carbon black, providing conditions for the uniform formation and loading of MoS2 subsequently.

[0076] Step S4: After hydrothermal reaction of the first mixed solution, separation and extraction are performed to anchor the molybdenum disulfide onto the surface of the pyrolytic carbon black to be treated, thus obtaining a composite material. The hydrothermal reaction induces molybdenum ions and sulfur ions in the first mixed solution to generate molybdenum disulfide (MoS2) in situ, which is then stably anchored onto the surface of the pyrolytic carbon black to be treated. Impurities are then removed through separation and extraction, ultimately yielding a pure MoS2 / pyrolytic carbon black composite material.

[0077] Specifically, the first mixed solution containing molybdenum disulfide obtained in step S3 is transferred to a hydrothermal reactor for hydrothermal reaction. The hydrothermal reaction is typically carried out in a high-temperature, high-pressure, closed environment (optionally, the temperature is set to 120-200℃ and the reaction time to 24 hours, depending on experimental requirements). The high-temperature, high-pressure environment activates molybdenum ions (from ammonium molybdate tetrahydrate) and sulfur ions (from thiourea decomposition) in the first mixed solution, allowing them to react fully at a stoichiometric ratio (Mo:S≈1:2) to generate MoS2 with a specific crystal structure. The surface of pyrolytic carbon black has a porous structure and active sites. During the hydrothermal reaction, the generated MoS2 nanosheets adhere tightly to the surface of the pyrolytic carbon black through van der Waals forces, electrostatic interactions, or chemical bonding, preventing MoS2 from detaching during subsequent use and forming a structurally stable composite system.

[0078] After the hydrothermal reaction, the system inside the reactor contains MoS2 / pyrolytic carbon black composite material, unreacted molybdenum / sulfur sources (such as residual ammonium molybdate tetrahydrate and thiourea), and water-soluble impurities, which need to be separated and purified through a process of "centrifugation → rinsing → drying". Specifically, the solid-liquid separation is as follows: the mixed system after the hydrothermal reaction is poured into a centrifuge tube, and high-speed centrifugation causes the denser MoS2 / pyrolytic carbon black composite material particles to settle to the bottom of the tube. The supernatant (containing unreacted raw materials and impurities) can be directly poured off and removed, achieving preliminary solid-liquid separation.

[0079] First, add deionized water to the centrifuged solid precipitate, shake to mix, and then centrifuge again, repeating this process multiple times. Deionized water dissolves and removes residual water-soluble impurities (such as unreacted molybdate ions, thiourea decomposition products, and ammonium salts). Then, replace the deionized water with ethanol, performing the same "add ethanol → shake → centrifuge" operation multiple times. This further cleanses residual trace water-soluble impurities and reduces the impact of moisture on the composite material structure during subsequent drying (e.g., preventing particle agglomeration due to moisture evaporation).

[0080] After obtaining the finished product, the solid precipitate after rinsing is transferred to an oven or vacuum drying oven and dried for 4-8 hours to remove residual ethanol and water, finally obtaining a dry and pure MoS2 / pyrolytic carbon black composite material.

[0081] Optionally, the hydrothermal reaction is carried out at a temperature of 160-200°C for 16-24 hours.

[0082] Specifically, the hydrothermal time gradient was set according to the principle of a single variable. Under fixed conditions such as hydrothermal temperature, reactant concentration (ratio of molybdenum source to sulfur source), and reactor filling degree, the effect of hydrothermal reaction time on the growth of MoS2 nanosheets was specifically verified by comparing 18h and 24h.

[0083] Example 1

[0084] (1) Material preparation: 10g of waste tire rubber powder was placed in a magnetic boat and placed in a tube furnace. The temperature was raised to 700℃ at a heating rate of 5℃·min⁻¹, held at the temperature for 2h, and then cooled. Argon gas was introduced throughout the process for protection. After cooling to room temperature, preliminary pyrolytic carbon black (CBp-800) was obtained. CBp-800 was then subjected to acid washing in 1M hydrochloric acid (HCl) and 10% hydrofluoric acid (HF) to remove impurities. The mixture was filtered until the pH of the filtrate was 7.0, and then dried overnight in an oven to obtain purified pyrolytic carbon black (TCBp-800). TCBp-800 was placed in a magnetic boat again and heated to 700℃ in a tube furnace at a heating rate of 5℃·min⁻¹. The temperature was held at the temperature for 2h in an argon / hydrogen mixed atmosphere. After cooling to room temperature, the pyrolytic carbon black to be treated (PCBp) was obtained.

[0085] Add 50 mg of PCBp to 30 mL of deionized water, sonicate for 20 min until uniformly dispersed, transfer to a magnetic stirrer, add 0.177 g of ammonium molybdate tetrahydrate, stir for 15 min to dissolve, then add 0.228 g of thiourea, continue stirring for 15 min, transfer to a hydrothermal reactor, and react at 200 °C for 18 h. After the reaction is complete, wash with deionized water and ethanol alternately by centrifugation, and dry in an oven overnight to obtain the PCBp-MoS2 composite material.

[0086] (2) Battery assembly and testing: Electrode material (PCBp-MoS2), conductive carbon black (Super-P) and binder (PVDF) are mixed in a mass ratio of 8:1:1. N-methylpyrrolidone (NMP) is added. After ball milling for 4 hours, the mixture is coated onto copper foil, vacuum dried at 80°C for 12 hours, cut into electrode sheets with a diameter of 8 mm, and the active material loading is calculated by weighing.

[0087] Assemble the CR2025 half-cell in an argon-filled glove box (oxygen and water content ≤0.01ppm) in the following order: positive electrode shell → electrode plate → electrolyte → separator → sodium metal sheet (12mm in diameter, self-rolled) → gasket → spring plate → negative electrode shell. After sealing, let it stand for 12 hours. The electrolyte is 1M NaClO4 dissolved in ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) in a volume ratio of 1:1:1, containing 2% fluoroethylene carbonate (FEC).

[0088] Test results: Figure 4 , Figure 5 , Figure 6 as well as Figure 7 The examples all illustrate the growth and effects of MoS2 nanosheets under the experimental conditions of Example 1. Among them, Figure 4 Scanning electron microscopy images show that MoS2 nanosheets are uniformly grown on the surface of pyrolytic carbon black; Figure 5 Transmission electron microscopy images confirm that the hydrothermal method successfully generated MoS2 nanosheets on the surface of carbon black; Figure 6The cycle performance diagram shows the composite material used as the negative electrode in a sodium-ion battery.

[0089] Example 2

[0090] (1) Material preparation: 5g of waste tire rubber powder was placed in a magnetic boat and heated to 800℃ in a tube furnace at 5℃·min⁻¹, held at the temperature for 2h, and cooled to room temperature under argon protection to obtain CBp-800. After acid washing with 1MHCl and 10%HF, filtration to pH=7.0, and drying in an oven, TCBp-800 was obtained. TCBp-800 was heated to 800℃ at 10℃·min⁻¹, held at the temperature for 2h in an argon / hydrogen mixed atmosphere, and cooled to obtain PCBp.

[0091] 50 mg of PCBp was added to 30 mL of deionized water and dispersed by sonication for 30 min. Then, 0.177 g of ammonium molybdate tetrahydrate was added and stirred for 15 min, followed by 0.228 g of thiourea and stirring for another 15 min. The mixture was then transferred to a hydrothermal reactor and reacted at 200 °C for 18 h. After alternating centrifugation with deionized water and ethanol and drying in an oven, the PCBp-MoS2 composite material was obtained.

[0092] (2) Battery assembly and testing are the same as those in Example 1.

[0093] Example 3

[0094] (1) Material preparation: 5g of waste tire rubber powder was placed in a magnetic boat and heated to 800℃ in a tube furnace at 5℃·min⁻¹, held at the temperature for 4h, and cooled to room temperature under argon protection to obtain CBp-800. After acid washing with 1MHCl and 10%HF, filtration to pH=7.0, and drying in an oven, TCBp-800 was obtained. TCBp-800 was heated to 800℃ at 5℃·min⁻¹, held at the temperature for 4h in an argon / hydrogen mixed atmosphere, and cooled to obtain PCBp.

[0095] 50 mg of PCBp was added to 30 mL of deionized water and dispersed by sonication for 30 min. Then, 0.177 g of ammonium molybdate tetrahydrate was added and stirred for 15 min, followed by 0.228 g of thiourea and stirring for another 15 min. The mixture was then transferred to a hydrothermal reactor and reacted at 200 °C for 18 h. After alternating centrifugation with deionized water and ethanol and drying in an oven, the PCBp-MoS2 composite material was obtained.

[0096] (2) Battery assembly and testing are the same as those in Example 1.

[0097] Example 4

[0098] (1) Material preparation: 5g of waste tire rubber powder was placed in a magnetic boat and heated to 800℃ in a tube furnace at 10℃·min⁻¹, held at the temperature for 4h, and cooled to room temperature under argon protection to obtain CBp-800. After acid washing with 1MHCl and 10%HF, filtration to pH=7.0, and drying in an oven, TCBp-800 was obtained. TCBp-800 was heated to 800℃ at 10℃·min⁻¹, held at the temperature for 4h in an argon / hydrogen mixed atmosphere, and cooled to obtain PCBp.

[0099] 50 mg of PCBp was added to 30 mL of deionized water and dispersed by sonication for 30 min. Then, 0.177 g of ammonium molybdate tetrahydrate was added and stirred for 15 min, followed by 0.228 g of thiourea and stirring for another 15 min. The mixture was then transferred to a hydrothermal reactor and reacted at 200 °C for 18 h. After alternating centrifugation with deionized water and ethanol and drying in an oven, the PCBp-MoS2 composite material was obtained.

[0100] (2) Battery assembly and testing are the same as those in Example 1.

[0101] Example 5

[0102] (1) Material preparation: 5g of waste tire rubber powder was placed in a magnetic boat and heated to 800℃ in a tube furnace at 10℃·min⁻¹, held at the temperature for 4h, and cooled to room temperature under argon protection to obtain CBp-800. After acid washing with 1MHCl and 10%HF, filtration to pH=7.0, and drying in an oven, TCBp-800 was obtained. TCBp-800 was heated to 800℃ at 10℃·min⁻¹, held at the temperature for 4h in an argon / hydrogen mixed atmosphere, and cooled to obtain PCBp.

[0103] 50 mg of PCBp was added to 30 mL of deionized water and dispersed by sonication for 30 min. Then, 0.177 g of ammonium molybdate tetrahydrate was added and stirred for 15 min. Next, 0.228 g of thiourea was added and stirred for 15 min. The mixture was then transferred to a hydrothermal reactor and reacted at 200 °C for 24 h. After washing with deionized water and ethanol by alternating centrifugation and drying in an oven, the PCBp-MoS2 composite material was obtained.

[0104] (2) Battery assembly and testing are the same as those in Example 1.

[0105] Combination Figure 12 The data in the table shown are compared with the specific capacity performance curves of each embodiment after 100 cycles. Figures 7-11 The detailed analysis of the test results of Examples 1-5 and the reasons why Example 1 is preferred are as follows:

[0106] from Figure 12It can be seen that the specific capacity of the 0.1A・g⁻¹ in Example 1 is 374.97mAh・g⁻¹ in the first cycle and 347.9mAh・g⁻¹ in the 100-cycle cycle with 2A・g⁻¹, with a capacity retention rate of 92.78%.

[0107] correspond Figure 7 The specific capacity performance curve of Example 1 after 100 cycles showed a small fluctuation at the beginning and then quickly stabilized. After 100 cycles, the capacity did not decrease significantly and remained at 384.7 mAh・g⁻¹.

[0108] Although the corresponding embodiment 2 Figure 8 In Example 2, the specific capacity performance curve after 100 cycles was relatively stable throughout, but Example 2 showed... Figure 12 The specific capacity of 0.1A・g⁻¹ in the first cycle was 365.74mAh・g⁻¹, and after 100 cycles it was 338.47mAh・g⁻¹, with a retention rate of 92.54%. Compared with Example 1, its retention rate is not as stable.

[0109] exist Figure 9 In the embodiments, the 100-cycle specific capacity performance curve of Embodiment 3 shows initial fluctuation followed by stabilization, combined with... Figure 12 It can be seen that Example 3 ( Figure 9 The first lap showed the highest specific capacity (395.62 mAh・g⁻¹), and after 100 laps it was 365.23 mAh・g⁻¹, with a retention rate of 92.32%, which is not as good as the capacity retention rate of Example 1.

[0110] exist Figure 10 In the embodiments, the 100-cycle specific capacity performance curve of Embodiment 4 fluctuated drastically, with capacity repeatedly fluctuating and performance stability being extremely poor. Figure 12 In Example 4, the specific capacity was 388.74 mAh・g⁻¹ in the first cycle, but only 331.86 mAh・g⁻¹ after 100 cycles, with a retention rate of 85.37%, which was the lowest among all examples.

[0111] exist Figure 11 In the embodiments, the specific capacity performance curve of Example 5 after 100 cycles initially fluctuated but then tended to stabilize. Figure 12 It can be seen that the specific capacity of Example 5 in the first cycle is 366.03 mAh・g⁻¹, and the specific capacity after 100 cycles is 338.03 mAh・g⁻¹, with a retention rate of 92.35%. In comparison, Example 1 is still higher than Example 5.

[0112] In summary, Example 1 is the optimal choice not only because of its retention rate over 100 cycles. Figure 12 It is a leader in the field; moreover, it is prepared using 10g of waste tire rubber powder, resulting in higher resource utilization efficiency, and it also references... Figure 4 as well as Figure 5It can be seen that the MoS2 nanosheets in Example 1 are uniformly dispersed on the carbon black surface and have a tight interfacial bond.

[0113] In another embodiment of this disclosure, a pyrolytic carbon black-molybdenum disulfide composite material is provided, wherein it is prepared by the preparation method described in any of the above embodiments.

[0114] In another embodiment of this disclosure, the use of a pyrolytic carbon black-molybdenum disulfide composite material prepared based on the preparation method described in any of the above embodiments is provided, wherein it is used as a negative electrode material for sodium-ion batteries.

[0115] The high conductivity and porous structure of pyrolytic carbon black can improve the electron transport efficiency of the electrode and alleviate the volume expansion during charging and discharging. The layered structure of molybdenum disulfide and its high theoretical sodium storage capacity can provide sufficient sodium ion insertion / extraction sites, ensuring the energy density of the battery. It also provides a new option for sodium-ion battery electrode materials, which helps to promote its technological development in low-cost, large-scale energy storage scenarios.

[0116] The above embodiments are merely illustrative of the principles and effects of this disclosure and are not intended to limit this disclosure. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this disclosure. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this disclosure should still be covered by the protection scope of this disclosure.

Claims

1. A method for preparing a pyrolytic carbon black-molybdenum disulfide composite material, characterized in that, include: Waste tire rubber powder was subjected to two pyrolysis and carbonization treatments under different gas environments to obtain pyrolytic carbon black to be treated; The pyrolytic carbon black to be treated was placed in deionized water and then subjected to ultrasonic dispersion treatment to obtain a pyrolytic carbon black suspension. A solution containing molybdenum ions and a solution containing sulfur ions are added sequentially to the pyrolytic carbon black suspension to obtain a first mixed solution containing molybdenum disulfide. After the first mixture is subjected to a hydrothermal reaction, it is separated and extracted to anchor the molybdenum disulfide onto the surface of the pyrolytic carbon black to be treated, thereby obtaining a composite material.

2. The preparation method according to claim 1, characterized in that, The process of subjecting waste tire rubber powder to two pyrolysis carbonization treatments under different gas environments to obtain pyrolytic carbon black includes: The waste tire rubber powder is placed in a tube furnace under an inert atmosphere and heated to the first target temperature, then kept at a constant temperature and cooled to room temperature to obtain preliminary pyrolytic carbon black. The preliminary pyrolytic carbon black is placed in an acidic mixed solution and stirred, filtered, washed with water and dried to remove inorganic impurities from the preliminary pyrolytic carbon black, thereby obtaining purified pyrolytic carbon black. The purified pyrolytic carbon black is placed again in a tube furnace under a mixed inert atmosphere and heated to the second target temperature, then kept at a constant temperature and cooled to room temperature to obtain the pyrolytic carbon black to be treated.

3. The preparation method according to claim 2, characterized in that, The amount of waste tire rubber powder used is 5-10g, the first target temperature is 700℃-800℃, the second target temperature is 700℃-800℃, the holding time is 2-4 hours, and the heating rate of the tubular furnace in both cases is 5~10℃·min. -1 .

4. The preparation method according to claim 1 or 2, characterized in that, The pyrolysis carbonization treatment conditions are 5~10℃·min -1 The temperature is raised to 700-800℃ and then held at that temperature for 2-4 hours.

5. The preparation method according to claim 1, characterized in that, When the amount of waste tire rubber powder used is 5-10g, the step of sequentially adding a mixed solution containing molybdenum ions and sulfur ions to the pyrolytic carbon black suspension to obtain a first mixed solution containing molybdenum disulfide includes: The pyrolytic carbon black suspension was placed on a magnetic stirrer, and 0.177 g of ammonium molybdate tetrahydrate solution was added and stirred to dissolve the molybdenum ions. 0.228 g of thiourea was added to a mixed solution containing molybdenum ions and stirred to dissolve, thus obtaining the first mixed solution containing molybdenum disulfide.

6. The preparation method according to claim 1, characterized in that, The process of separating and extracting the first mixture after hydrothermal reaction includes centrifugation, rinsing, and drying; wherein centrifugation and rinsing are performed alternately using deionized water and ethanol.

7. The preparation method according to claim 1, characterized in that, The hydrothermal reaction is carried out at a temperature of 160-200°C for 16-24 hours.

8. The preparation method according to claim 1, characterized in that, The ultrasonic dispersion treatment takes 20-30 minutes.

9. A pyrolytic carbon black-molybdenum disulfide composite material, characterized in that, Prepared by the preparation method described in any one of claims 1-8.

10. The use of the pyrolytic carbon black-molybdenum disulfide composite material prepared by the preparation method according to any one of claims 1-8, characterized in that, Used as a negative electrode material in sodium-ion batteries.

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