Preparation method and application of carbon-coated hydroxyapatite-loaded zinc compound composite material

Abstract

The invention discloses a preparation method and application of a carbon-coated hydroxyapatite-loaded zinc compound composite material, and belongs to the technical field of aqueous zinc ion batteries. The method comprises the following steps: mixing a zinc source, an organic ligand containing carboxyl and hydroxyl, sulfide and a polar organic solvent, and stirring and heating to react; adding hydroxyapatite into the mixed solution, transferring the mixed solution into a reaction kettle, carrying out segmented temperature control reaction, carrying out suction filtration, and drying to obtain a solid reactant with an accordion-like structure; and placing the deposited carbon precursor and the accordion-like structure solid reactant in different heating areas, and carrying out carbon deposition in an argon atmosphere in a double-temperature-area independent temperature control manner to obtain the carbon-coated hydroxyapatite loaded zinc compound composite material. According to the invention, the accordion-like composite material is prepared by means of sulfide regulation, hydroxyapatite connection and organic carbon deposition, and has excellent specific capacity and good cycle stability in the zinc ion battery.

Description

Technical Field

[0001] This invention belongs to the field of aqueous zinc-ion battery technology, specifically relating to a method for preparing and applying a zinc compound composite material supported on carbon-coated hydroxyapatite. Background Technology

[0002] With the energy crisis and severe environmental changes, people have higher expectations for renewable energy. Research on lithium-ion batteries has increased significantly in recent years, but lithium resources and safety issues remain key concerns. Aqueous zinc-ion batteries have gained widespread attention due to their low cost, high safety, environmental friendliness, and high specific capacity. However, the zinc anode in aqueous zinc-ion batteries undergoes dendrite growth and hydrogen evolution reactions during cycling, leading to reduced cycle stability and even battery failure.

[0003] Metal-organic frameworks have the advantages of large specific surface area and high porosity, and can provide Zn 2+ The storage sites. In current research, the synthesis of metal-organic frameworks mostly uses ligands with single groups. Ligands such as terephthalic acid and trimesolic acid contain only a single carboxyl group, making further modification after connection with the metal source very difficult; during electrochemical testing, the acidity of the electrolyte cannot be neutralized, resulting in hydrogen evolution reaction. Chinese patent document CN119101250A discloses the preparation of MOF-5W material and its application in improving the performance of aqueous zinc-ion batteries through the channel confinement effect. Terephthalic acid and sodium hydroxide are added to a solution to form solution A, and zinc acetate dihydrate is added to a solution to form solution B. After mixing and reacting the two solutions, MOF-5W powder is obtained, and after activation, MOF-5W material is obtained. The activation temperature of MOF-5W powder is only 200℃ for 2h, the purpose of which is only to remove solvent molecules, without changing the problem of poor conductivity of MOF material itself; and the synthesized MOF-5W has a long rice grain morphology, and the rough surface will cause uneven nucleation, leading to the formation of zinc dendrites in the initial nucleation region. Chinese patent document CN118867104A discloses a method for preparing a metal-organic framework (MOF) coating for an aqueous zinc-ion battery anode. The method involves mixing zinc ions, dimethylimidazole, and a regulator. After the reaction, a ZIF-8 precursor solution is centrifuged to obtain a precipitate. An organic solvent and a suitable binder are added to form a colloid, which is then coated onto the zinc anode and dried and cooled. Finally, the electrode is subjected to high-temperature treatment in an inert atmosphere to fully polymerize the oligomers and optimize the coating crystal structure. This method integrates electrode material preparation and electrode coating processes, using ZIF-8 monomers as the active material. However, it still cannot avoid the inherent poor conductivity of MOF materials. Furthermore, the material obtained by this method exhibits cracks during the coating process, and its electrochemical performance in zinc-ion battery testing needs improvement.

[0004] In aqueous zinc-ion batteries, metal-organic frameworks (MOFs) suffer from poor electrode material conductivity and unsatisfactory rate performance, necessitating surface modification of the electrode materials. Recent research has focused on constructing artificial interface layers on zinc anodes to induce zinc deposition. Hydroxyapatite, due to its alkalinity after hydrolysis, is used for surface modification, neutralizing acidic electrolytes and inhibiting dendrite growth. Furthermore, the calcium in hydroxyapatite can exchange ions with zinc, inducing zinc deposition and improving electrochemical performance. Chinese patent document CN118712319A discloses a zinc anode protective layer, its preparation method, and its application. The raw materials for the zinc anode protective layer include hydroxyapatite nanowires and sulfonated polyether ether ketone (PEEK). This method involves spin-coating sulfonated PEEK onto the zinc anode surface using hydroxyapatite nanowires as a framework. Without a substrate material for support, it fails to provide migration sites and energy storage sites for electrolyte ions in zinc-ion batteries. Zinc ions are more easily deposited on the coating surface, leading to a loss of protective effect and hindering the improvement of electrochemical performance. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing and applying a carbon-coated hydroxyapatite-supported zinc compound composite material. The method involves the directional growth of carboxyl and hydroxyl-containing ligands and metal salts in a polar solvent using sulfides to form sheet-like materials. The nucleation sites of hydroxyapatite are then used to connect with the hydroxyl / carboxyl groups in the sheet-like materials to form an accordion-like structure. Finally, an organic carbon layer is deposited on the surface of the material using chemical vapor deposition to obtain the final composite material. This composite material has the advantages of a smooth surface and hierarchical porosity. The organic carbon coating layer effectively isolates Zn from the electrolyte, suppressing side reactions. The addition of hydroxyapatite connects the sheet-like materials and acts as a bulk dopant, forming a multi-level porous structure that promotes the adsorption and migration of electrolyte ions and buffers volume changes during the electrochemical process. During the electrochemical reaction, the coating layer isolates the electrode material from acidic ions in the electrolyte. If a small amount of acidic ions penetrate the coating layer, they are neutralized by hydroxyapatite, further suppressing the hydrogen evolution reaction, thereby significantly improving the specific capacity and cycle stability of the battery.

[0006] To achieve the objective of this invention, a method for preparing a zinc compound composite material supported on carbon-coated hydroxyapatite is provided, comprising the following steps: (1) Mix the zinc source, organic ligands containing carboxyl and hydroxyl groups, sulfide and polar organic solvent, stir and heat to react, and obtain mixture A; (2) Add hydroxyapatite to mixture A to form mixture B. Transfer mixture B to a reaction vessel for segmented temperature-controlled reaction, filter and dry to obtain a solid reactant with an accordion-like structure. (3) The carbon deposition precursor is placed in the direction of the gas inlet of the tube furnace, and the accordion-like solid reactant is placed in the direction of the gas outlet of the tube furnace. Under the argon atmosphere, carbon deposition is carried out by using a dual-temperature zone independent temperature control method to obtain a carbon-coated zinc compound composite material loaded with hydroxyapatite.

[0007] Preferably, in step (1), the zinc source is one of zinc nitrate, zinc acetate, and zinc chloride; the organic ligand containing carboxyl and hydroxyl groups is one of p-hydroxybenzoic acid, 3,4-dihydroxybenzoic acid, 4-hydroxyphenylacetic acid, and p-hydroxyphenylpropionic acid; the sulfide is one of zinc sulfide and sodium sulfide; the polar organic solvent is one of N,N-dimethylformamide and dimethyl sulfoxide; the molar ratio of zinc source, organic ligand containing carboxyl and hydroxyl groups, and sulfide is 0.5~3:1:0.05~0.3; and the concentration of zinc source in polar organic solvent is 0.2~0.5 mol / L.

[0008] Preferably, in step (1), the stirring and heating temperature is 50~80℃ and the time is 30~60min.

[0009] Preferably, in step (2), the particle size of hydroxyapatite is nanoscale, and the molar ratio of hydroxyapatite to zinc source is 0.02~0.1:1; the temperature and time of the segmented temperature-controlled reaction are as follows: first react at 60~90℃ for 60~120min, and then continue to heat to 140~180℃ for 12~24h; the solvent for filtration and cleaning is one of ethanol and methanol; the drying temperature is 80~120℃ and the time is 6~12h.

[0010] Preferably, in step (3), the carbon deposition precursor is one of melamine, 1-naphthylamine, and urea; the mass ratio of the carbon deposition precursor to the accordion-like solid reactant is 0.5~0.8:1; the independent temperature control method of the dual temperature zones is as follows: first, the accordion-like solid reactant is heated to 600~750℃ at a rate of 2~5℃ / min and held for 30~60min, then cooled to 400~500℃ at a rate of 3~5℃ / min and held continuously; then the carbon deposition precursor is heated to 750~900℃ at a rate of 5~10℃ / min and held for 120~240min.

[0011] The present invention also provides the application of the carbon-coated hydroxyapatite-supported zinc compound composite material prepared by the above method in aqueous zinc-ion batteries.

[0012] Compared with the prior art, the present invention has the following advantages: 1. The present invention provides a method for preparing a carbon-coated hydroxyapatite-supported zinc-containing compound composite material. Sulfide-induced lamellar substrate structure is formed, and under the coordination effect of hydroxyapatite and bulk doping, an accordion-like structure is formed. Finally, an organic carbon layer is deposited on the surface to form the composite material. The composite material has a smooth surface, effectively isolating Zn from the electrolyte and suppressing side reactions. The accordion-like structure provides hierarchical porous ion transport channels and reduces volume change, effectively adsorbing Zn during electrochemical testing. 2+ It also suppresses the shuttle effect, thereby promoting the specific capacity and cycle performance of zinc-ion batteries.

[0013] 2. This invention induces the formation of a sheet-like substrate structure through the addition of sulfides. The solvent forms solvated ions with the sulfides through solvation, which combine with metal ions to form a coordination structure, slowing down the nucleation process. The addition of polar organic solvents can also promote the ionization of hydroxyl / carboxyl ligands into highly active oxygen-containing groups, accelerating the multidentate chelation with metal ions, increasing the interlayer spacing of nucleation molecules, and promoting the migration of electrolyte ions. The addition of sulfides adsorbs onto high-performance interfaces, inhibiting the vertical growth of nucleation molecules. TEM observation shows that the (002) interplanar spacing of the material is 0.21 nm, which is less than the theoretical interplanar spacing of 0.26 nm, confirming that the addition of sulfides plays a role in inhibiting vertical growth. The inventors found that the composite material obtained without the addition of sulfides has a polyhedral structure and cannot inhibit vertical growth. When the amount of sulfides added is too large, the number of active sites provided by the sulfides increases, and the edges of the material tend to be in a stable closed state during the reaction, forming a sheet-like structure with a certain thickness of stacked layers. Compared with accordion-like materials, this material has fewer active sites and stores less electrolyte ions with lower capacity during electrochemical processes.

[0014] 3. This invention utilizes the addition of hydroxyapatite to induce nucleation followed by bulk doping in accordion-like materials, and the hydroxyl and carboxyl groups in the organic ligands provide more nucleation sites. This invention selects organic ligands possessing both carboxyl and hydroxyl groups for the reaction. Ligands with different functional groups form structural units with lower symmetry during the connection with hydroxyapatite, tending towards irregular connections to exhibit an accordion-like structure. The close packing of the lamellar layers effectively utilizes hydroxyapatite, resulting in accordion-like materials that effectively adsorb and migrate electrolyte ions during electrochemical reactions, thus enhancing electrochemical performance. During the low-temperature reaction stage, calcium ions in hydroxyapatite preferentially combine with carboxyl groups on the surface of the lamellar structure to form ionic bonds. At the same time, phosphorus-oxygen bonds on the surface of hydroxyapatite form a hydrogen bond network with hydroxyl groups on the surface of the lamellar structure. Hydroxyapatite nanoparticles act as heterogeneous nucleation sites, adsorbing onto the edges of the lamellar structure and inducing the directional stacking of the lamellar structure. As the reaction temperature increases, zinc ions and calcium ions undergo a substitution reaction to form a bulk doping effect, resulting in a multi-level distributed porous structure. This yields a composite material mainly composed of micropores and mesopores, thereby improving the conductivity of the material. The inventors discovered that when conventional carboxyl-type organic ligands are used, the material surfaces have the same coordination form, and the strong attraction between the groups will spontaneously form stacked layers. The addition of hydroxyapatite will connect the material edges, inhibiting some of the fully enclosed stacking. The resulting materials are mostly irregular structures. These materials have different adsorption strengths of electrolyte ions during electrochemical processes, and the coating layer has low adsorption on the surface of the irregular structure, which leads to a decrease in electrochemical performance. Without the addition of hydroxyapatite during the synthesis process, the sheet-like material spontaneously grows along the edges, resulting in a spherical composite material composed of sheets. With the addition of hydroxyapatite, the nucleation and connection process occurs at low temperatures, and the process of rapid ion migration and structural growth occurs as the temperature rises. If only the high-temperature reaction stage is carried out, without the nucleation and pre-anchoring of the low-temperature stage, the reaction rate is fast, and hydroxyapatite will form spindle-shaped connections in different directions in the material. If only the low-temperature reaction is carried out, the material will remain in the initial nucleation and connection stage and cannot be subsequently doped, resulting in a mixed phase. The irregularity of the coating layer on the surface of the mixed phase will accelerate the combination of hydroxyapatite inside the material with hydrogen ions released during the reaction, accelerate the degradation of material performance, and cause irreversible reactions.

[0015] 4. This invention uses a nitrogen-containing organic carbon source and achieves functionalization through adsorption at defect sites via material activation, carbon source pyrolysis, and directional deposition. A carbon layer is uniformly coated onto the surface of the accordion-like structure, filling surface defects and suppressing side reactions. First, the accordion-like material is activated, removing hydroxyl groups to create oxygen-containing vacancies. Then, the carbon precursor is heated at high temperature, causing a pyrolysis reaction. The resulting gaseous carbon migrates to a low-temperature region under the influence of airflow. In the low-temperature region, nitrogen functionalization occurs at the oxygen vacancies of the accordion-like material, and the carbon spreads directionally to form a uniform coating with a thickness of 7.19~8.37 nm. The organic carbon coating effectively isolates zinc from the electrolyte and mitigates volume changes, improving cycle stability. The inventors discovered that the absence of a carbon source prevents material defects from being coated, resulting in weak adsorption of electrolyte ions and poor performance during electrochemical reactions. Furthermore, in traditional coating processes, the organic carbon gradually vaporizes at high temperatures, resulting in limited coating amount and performance improvement in the composite material.

[0016] 6. The carbon-coated hydroxyapatite-supported zinc compound composite material prepared according to this invention was assembled into an aqueous zinc-ion battery for electrochemical performance testing. At a current density of 0.2C, the capacity reached 435.67~493.79 mAh / g, and after 200 cycles at a current density of 1C, the capacity retention was 93.87~95.63%. These data indicate that the carbon-coated hydroxyapatite-supported zinc compound composite material prepared according to this invention exhibits excellent specific capacity and good cycle stability in zinc-ion batteries. Attached Figure Description

[0017] Figure 1 The SEM image of the carbon-coated hydroxyapatite-supported zinc compound composite material prepared in Example 1; Figure 2 SEM images of the carbon-coated hydroxyapatite-supported zinc compound composites prepared in Comparative Examples 1-6; Figure 3 The XRD patterns of the carbon-coated hydroxyapatite-supported zinc compound composites prepared in Example 1 and Comparative Example 4 are shown. Figure 4 The TEM spectrum of the carbon-coated hydroxyapatite-supported zinc compound composite material prepared in Example 1; Figure 5 The FTIR spectrum of the carbon-coated hydroxyapatite-supported zinc compound composite material prepared in Example 1; Figure 6 The BET spectrum of the carbon-coated hydroxyapatite-supported zinc compound composite material prepared in Example 1 is shown below. Figure 7The capacity retention versus coulombic efficiency curves of the carbon-coated hydroxyapatite-supported zinc compound composite material prepared in Example 1 after 200 cycles at a current density of 1C. Detailed Implementation

[0018] The specific implementation of the present invention will be further described below with reference to the accompanying drawings and examples, but the implementation and protection of the present invention are not limited thereto. Example 1

[0019] (1) Mix 20 mmol zinc nitrate, 10 mmol 4-hydroxyphenylacetic acid, 2 mmol zinc sulfide and 60 mL N,N-dimethylformamide, stir at 70 °C for 45 min to obtain mixture A; (2) Add 0.6 mmol of hydroxyapatite to mixture A to form mixture B. Transfer mixture B to a reaction vessel and react at 80°C for 90 min. Then raise the temperature to 170°C and react for 18 h. After filtration and washing with ethanol, dry at 100°C for 8 h to obtain a solid reactant with an accordion-like structure. (3) 1.4g of melamine was placed in quartz crucible No. 1 and placed in the middle of the thermocouple in the direction of the gas inlet of the tube furnace (OTF-1200X-Ⅱ); 2g of accordion-like solid reactant was placed in quartz crucible No. 2 and placed in the middle of the thermocouple in the direction of the gas outlet of the tube furnace. Carbon deposition was carried out under an argon atmosphere using an independent temperature control method with the following parameters: first, the area of ​​quartz crucible No. 2 was heated to 650℃ at 2℃ / min and held for 45min, and then cooled to 400℃ at 3℃ / min; then the area of ​​quartz crucible No. 1 was heated, starting at the time when quartz crucible No. 2 cooled to the target temperature, and heated to 900℃ at 5℃ / min and held for 180min to obtain a carbon-coated hydroxyapatite-supported zinc compound composite material. Example 2

[0020] (1) Mix 10 mmol zinc acetate, 10 mmol 3,4-dihydroxybenzoic acid, 1.5 mmol zinc sulfide and 40 mL dimethyl sulfoxide, and stir at 50 °C for 60 min to obtain mixture A; (2) Add 0.5 mmol of hydroxyapatite to mixture A to form mixture B. Transfer mixture B to a reaction vessel and react at 90°C for 70 min. Then raise the temperature to 140°C and react for 24 h. After cleaning with methanol, dry at 120°C for 6 h to obtain a solid reactant with an accordion-like structure. (3) 1.6g of 1-naphthylamine was placed in quartz crucible No. 1 and placed in the middle of the thermocouple in the direction of the gas inlet of the tube furnace (OTF-1200X-Ⅱ); 2g of accordion-like solid reactant was placed in quartz crucible No. 2 and placed in the middle of the thermocouple in the direction of the gas outlet of the tube furnace. Carbon deposition was carried out under an argon atmosphere using an independent temperature control method with the following parameters: first, the No. 2 quartz crucible area was heated to 700℃ at 5℃ / min and held for 30min, and then cooled to 450℃ at 5℃ / min; then the No. 1 quartz crucible area was heated, starting at the time when the No. 2 quartz crucible cooled to the target temperature, and heated to 850℃ at 6℃ / min and held for 200min to obtain a carbon-coated hydroxyapatite-supported zinc compound composite material. Example 3

[0021] (1) Mix 30 mmol zinc chloride, 10 mmol p-hydroxybenzoic acid, 3 mmol sodium sulfide and 60 mL N,N-dimethylformamide, stir at 80 °C for 30 min to obtain mixture A; (2) Add 0.6 mmol of hydroxyapatite to mixture A to form mixture B. Transfer mixture B to a reaction vessel and react at 60°C for 120 min. Then raise the temperature to 180°C and react for 12 h. After filtration and washing with ethanol, dry at 80°C for 12 h to obtain a solid reactant with an accordion-like structure. (3) Place 1g of urea into the No. 1 quartz crucible and place the No. 1 quartz crucible in the middle of the thermocouple in the direction of the gas inlet of the tube furnace (OTF-1200X-Ⅱ); place 2g of accordion-like solid reactant into the No. 2 quartz crucible and place the No. 2 quartz crucible in the middle of the thermocouple in the direction of the gas outlet of the tube furnace. Carbon deposition was carried out under an argon atmosphere using an independent temperature control method with the following parameters: first, the No. 2 quartz crucible area was heated to 650℃ at 2℃ / min and held for 45min, and then cooled to 400℃ at 3℃ / min; then the No. 1 quartz crucible area was heated, starting at the time when the No. 2 quartz crucible cooled to the target temperature, and heated to 900℃ at 5℃ / min and held for 180min to obtain a carbon-coated hydroxyapatite-supported zinc compound composite material. Example 4

[0022] (1) Mix 10 mmol zinc nitrate, 20 mmol 3,4-dihydroxybenzoic acid, 1 mmol sodium sulfide and 50 mL N,N-dimethylformamide, stir at 80 °C for 50 min to obtain mixture A; (2) Add 1 mmol of hydroxyapatite to mixture A to form mixture B. Transfer mixture B to a reaction vessel and react at 70°C for 100 min. Then raise the temperature to 150°C and react for 20 h. After cleaning with methanol, dry at 90°C for 10 h to obtain a solid reactant with an accordion-like structure. (3) 1.2g of 1-naphthylamine was placed in quartz crucible No. 1 and placed in the middle of the thermocouple in the direction of the gas inlet of the tube furnace (OTF-1200X-Ⅱ); 2g of accordion-like solid reactant was placed in quartz crucible No. 2 and placed in the middle of the thermocouple in the direction of the gas outlet of the tube furnace. Carbon deposition was carried out under an argon atmosphere using an independent temperature control method with the following parameters: first, the No. 2 quartz crucible area was heated to 600℃ at 3℃ / min and held for 60min, and then cooled to 500℃ at 3℃ / min; then the No. 1 quartz crucible area was heated, starting at the time when the No. 2 quartz crucible cooled to the target temperature, and heated to 750℃ at 8℃ / min and held for 220min to obtain a carbon-coated hydroxyapatite-supported zinc compound composite material. Example 5

[0023] (1) Mix 30 mmol zinc nitrate, 10 mmol 4-hydroxyphenylacetic acid, 1.5 mmol sodium sulfide and 80 mL dimethyl sulfoxide, and stir at 70 °C for 35 min to obtain mixture A; (2) 1.5 mmol of hydroxyapatite was added to mixture A to form mixture B. Mixture B was transferred to a reaction vessel and reacted at 80°C for 60 min. The temperature was then raised to 160°C and reacted for 14 h. After ethanol filtration and washing, the mixture was dried at 110°C for 8 h to obtain a solid reactant with an accordion-like structure. (3) 1.4g of melamine was placed in quartz crucible No. 1 and placed in the middle of the thermocouple in the direction of the gas inlet of the tube furnace (OTF-1200X-Ⅱ); 2g of accordion-like solid reactant was placed in quartz crucible No. 2 and placed in the middle of the thermocouple in the direction of the gas outlet of the tube furnace. Carbon deposition was carried out under an argon atmosphere using an independent temperature control method with the following parameters: first, the area of ​​quartz crucible No. 2 was heated to 650℃ at 5℃ / min and held for 50min, and then cooled to 400℃ at 5℃ / min; then the area of ​​quartz crucible No. 1 was heated, starting at the time when quartz crucible No. 2 cooled to the target temperature, and heated to 900℃ at 9℃ / min and held for 140min to obtain a carbon-coated hydroxyapatite-supported zinc compound composite material. Example 6

[0024] (1) Mix 10 mmol zinc acetate, 20 mmol p-hydroxyphenylpropionic acid, 2 mmol zinc sulfide and 50 mL N,N-dimethylformamide, and stir at 60 °C for 40 min to obtain mixture A; (2) Add 0.4 mmol of hydroxyapatite to mixture A to form mixture B. Transfer mixture B to a reaction vessel and react at 60°C for 80 min. Then raise the temperature to 170°C and react for 16 h. After filtration and washing with ethanol, dry at 100°C for 12 h to obtain a solid reactant with an accordion-like structure. (3) 1.2g of urea was placed in quartz crucible No. 1 and placed in the middle of the thermocouple in the direction of the gas inlet of the tube furnace (OTF-1200X-Ⅱ); 2g of accordion-like solid reactant was placed in quartz crucible No. 2 and placed in the middle of the thermocouple in the direction of the gas outlet of the tube furnace. Carbon deposition was carried out under an argon atmosphere using an independent temperature control method with the following parameters: first, the area of ​​quartz crucible No. 2 was heated to 700℃ at 2℃ / min and held for 55min, and then cooled to 450℃ at 5℃ / min; then the area of ​​quartz crucible No. 1 was heated, starting at the time when quartz crucible No. 2 cooled to the target temperature, and heated to 800℃ at 7℃ / min and held for 160min to obtain a carbon-coated hydroxyapatite-supported zinc compound composite material. Example 7

[0025] (1) Mix 20 mmol zinc chloride, 10 mmol p-hydroxybenzoic acid, 2 mmol zinc sulfide and 70 mL dimethyl sulfoxide, stir at 50 °C for 55 min to obtain mixture A; (2) 1.5 mmol of hydroxyapatite was added to mixture A to form mixture B. Mixture B was transferred to a reaction vessel and reacted at 90°C for 110 min. Then the temperature was raised to 180°C and reacted for 22 h. After being filtered and washed with methanol, it was dried at 90°C for 6 h to obtain a solid reactant with an accordion-like structure. (3) 1.6g of melamine was placed in quartz crucible No. 1 and placed in the middle of the thermocouple in the direction of the gas inlet of the tube furnace (OTF-1200X-Ⅱ); 2g of accordion-like solid reactant was placed in quartz crucible No. 2 and placed in the middle of the thermocouple in the direction of the gas outlet of the tube furnace. Carbon deposition was carried out under an argon atmosphere using an independent temperature control method with the following parameters: first, the area of ​​quartz crucible No. 2 was heated to 750℃ at 3℃ / min and held for 35min, and then cooled to 500℃ at 4℃ / min; then the area of ​​quartz crucible No. 1 was heated, starting at the time when quartz crucible No. 2 cooled to the target temperature, and heated to 850℃ at 5℃ / min and held for 240min to obtain a carbon-coated hydroxyapatite-supported zinc compound composite material. Comparative Example 1

[0026] No sulfides were added in this comparative example. Specifically, 20 mmol of zinc nitrate, 10 mmol of 4-hydroxyphenylacetic acid, and 60 mL of N,N-dimethylformamide were mixed and stirred at 70°C for 45 min to obtain mixture A. All other steps were the same as in Example 1. Comparative Example 2

[0027] In this comparative example, the organic ligand used is a single-group ligand: terephthalic acid. Specifically, 20 mmol of zinc nitrate, 10 mmol of terephthalic acid, 2 mmol of zinc sulfide and 60 mL of N,N-dimethylformamide were mixed and stirred at 70°C for 45 min to obtain mixture A; all other processes were the same as in Example 1. Comparative Example 3

[0028] In this comparative example, the amount of sulfide added was 5 mmol, that is: 20 mmol zinc nitrate, 10 mmol 4-hydroxyphenylacetic acid, 5 mmol zinc sulfide and 60 mL N,N-dimethylformamide were mixed and stirred at 70°C for 45 min to obtain mixture A. All other processes were the same as in Example 1. Comparative Example 4

[0029] In this comparative example, step (2) does not involve the addition of hydroxyapatite. That is, the mixture A is transferred to the reactor and reacted at 80°C for 90 min, then heated to 170°C for 18 h, and after being cleaned by ethanol filtration, it is dried at 100°C for 8 h to obtain a solid reactant with an accordion-like structure. All other steps are consistent with the process in Example 1. Comparative Example 5

[0030] In this comparative example, the reaction in step (2) of the reactor only uses the second stage of 170°C reaction for 18 hours, that is: 0.6 mmol of hydroxyapatite is added to the mixture A to form mixture B, mixture B is transferred to the reactor and reacted at 170°C for 18 hours, and after ethanol filtration and washing, it is dried at 100°C for 8 hours to obtain a solid reactant with an accordion-like structure. All other processes are consistent with those in Example 1. Comparative Example 6

[0031] In this comparative example, the reaction in step (2) of the reactor only uses the first stage of 80°C reaction for 90 min, that is: 0.6 mmol of hydroxyapatite is added to the mixture A to form mixture B, mixture B is transferred to the reactor and reacted at 80°C for 90 min, and after ethanol filtration and washing, it is dried at 100°C for 8 h to obtain a solid reactant with an accordion-like structure. All other processes are consistent with those in Example 1. Comparative Example 7

[0032] In this comparative example, step (3) does not involve adding a carbon deposition precursor. Specifically, 2g of an accordion-like solid reactant is placed in a second quartz crucible, which is then positioned between thermocouples at the outlet of a tube furnace (OTF-1200X-Ⅱ). Calcination is performed under an argon atmosphere using independent temperature control. The parameters are: in the second quartz crucible area, the temperature is increased at 2℃ / min to 650℃ and held for 45min to obtain the final composite material. All other steps are consistent with those in Example 1. Comparative Example 8

[0033] In this comparative example, step (3) does not involve carbon deposition to coat the material. Instead, a traditional method is used: 1.4g of melamine and 2g of accordion-like solid reactant are dispersed in an ethanol solution, dried, and then calcined. Specifically, 1.4g of melamine and 2g of accordion-like solid reactant are dispersed in an ethanol solution and placed in a No. 2 quartz crucible. After drying, the No. 2 quartz crucible is placed between thermocouples in the direction of the gas outlet of a tube furnace (OTF-1200X-Ⅱ). Calcination is carried out under an argon atmosphere using independent temperature control. The parameters are: in the No. 2 quartz crucible area, the temperature is increased to 650℃ at a rate of 2℃ / min and held for 45min to obtain the final composite material. All other processes are consistent with those in Example 1.

[0034] The prepared carbon-coated hydroxyapatite-supported zinc compound composite material was applied to an aqueous zinc-ion battery. Using a scraping method, the active material, acetylene black and PVDF were weighed at a mass ratio of 8:1:1, NMP was added and stirred into a viscous slurry, which was then scraped onto copper foil. After drying, the φ12 electrode sheet was cut using a slicer. The zinc-ion battery was assembled in a glove box and electrochemical tests were performed after standing for 2-4 hours.

[0035] Using the aforementioned electrode sheet as the negative electrode, and a conventional MnO2 positive electrode with zinc intercalation to form a zinc-containing positive electrode, a GF / F glass fiber membrane was selected as the separator. The electrolyte was 2M ZnSO4 + 0.1M MnSO4. A CR2032 type zinc-ion battery was assembled for electrochemical testing. Constant current charge-discharge curve (GCD) test conditions: voltage window 1.0~1.9 V (Vs Zn 2+ / Zn), current densities of 0.2 C, 0.5 C, 1 C, 1.5 C, and 2 C. Capacity retention was tested after 200 cycles at a current density of 1 C.

[0036] The performance of the electrode materials obtained from the examples and comparative examples is summarized in Table 1 below.

[0037]

[0038] Figure 1 and Figure 2The images show the SEM spectra of the carbon-coated hydroxyapatite-supported zinc compound composites prepared in Examples 1 and Comparative Examples 1-6, respectively. Example 1 yielded an accordion-like composite material formed by close-packed lamellar structures, indicating that the accordion-like composite material was obtained under the influence of polar solvent dispersion, sulfide traction, and hydroxyapatite bonding. The close packing of the lamellar layers effectively utilizes hydroxyapatite, and organic carbon can be uniformly coated on the surface, forming a hierarchical porous structure dominated by micropores and mesopores, similar to an accordion-like material. This allows for effective adsorption and migration of electrolyte ions during electrochemical reactions, promoting improved electrochemical performance. Comparative Example 1 did not add sulfides, and the material grew normally along the vertical direction, resulting in a polyhedral material. Comparative Example 2 used ligands with only carboxyl groups; the addition of hydroxyapatite connected the lamellar structures at the edges, and the same coordination forms on the material surface spontaneously formed layer-by-layer stacking, resulting in a material that was mostly irregular polyhedral. Comparative Example 3 added excessive sulfides. When hydroxyapatite is added to connect the sheet-like materials, the number of active sites increases, making it more inclined to connect the layers and form stacked sheet-like materials. Compared with accordion-like materials, this material has fewer active sites and stores less electrolyte ions and has a lower capacity during electrochemical processes. In Comparative Example 4, no hydroxyapatite was added to connect the sheet-like materials. The sheet-like materials spontaneously connected and grew along the edges, resulting in a spherical composite material composed of sheet-like materials. The irregular stacking of the materials led to uneven charge migration during electrochemical processes, resulting in reduced capacity and cycle performance. Comparative Example 5 did not undergo a low-temperature reactor reaction and lacked the low-temperature connection of hydroxyapatite to the sheet-like materials. As the temperature rapidly increased, the ionic activity increased, and the irregular connection direction between the materials resulted in a spindle-shaped structure. The uneven charge migration caused a decrease in performance. Comparative Example 6 did not undergo a high-temperature reactor reaction. After the sheet-like structures were connected, they did not undergo a growth process, resulting in a mixed-phase material. This caused the material surface to have weak charge attraction, resulting in reduced capacity and cycle performance.

[0039] Figure 3 The XRD patterns of the carbon-coated hydroxyapatite-supported zinc compound composites prepared in Example 1 and Comparative Example 4 are shown. The composite material obtained in Example 1 corresponds well to the characteristic peaks of zinc oxide and hydroxyapatite. Comparative Example 4 did not add hydroxyapatite, but the material obtained corresponds to the characteristic peaks of zinc oxide, proving that the carbon-coated hydroxyapatite-supported zinc compound composite material was successfully synthesized by this method. In Example 1, the diffraction peaks are broad, and the diffraction angles corresponding to (002) and (101) show a rightward shift. According to the Scherrer equation, the interplanar spacing is inversely proportional to the diffraction angle. The decrease in the interplanar spacing corresponding to (002) and (101) inhibits the growth of the material along the C-axis, proving that the addition of hydroxyapatite is a bulk doping agent.

[0040] Figure 4The image shows the TEM spectrum of the carbon-coated hydroxyapatite-supported zinc compound composite material prepared in Example 1. The accordion-like material was activated to form oxygen vacancies, and the carbon precursor was decomposed and migrated to the low-temperature region for deposition under the action of airflow. Organic carbon deposition yielded a uniform coating layer with an average thickness of 7.84 nm. The interplanar spacings corresponding to the (002) and (101) crystal planes were 0.21 nm and 0.26 nm, respectively, which were both smaller than the theoretical interplanar spacings of 0.26 nm and 0.28 nm. The results were consistent with the XRD data, indicating that the carbon-coated hydroxyapatite-supported zinc compound composite material was successfully synthesized.

[0041] Figure 5 The FT-IR spectrum of the carbon-coated hydroxyapatite-supported zinc compound composite material prepared in Example 1 is shown at 441 cm⁻¹. -1 The absorption peak at 575 cm⁻¹ corresponds to the Zn-O bond stretching vibration peak; -1 The absorption peak at 606 cm⁻¹ is due to the stretching vibration of the Ca-O bond after calcium and hydroxyl linkage and calcium substitution of zinc; -1 and 637cm -1 The absorption peak at 1051 cm⁻¹ corresponds to the bending vibration of the PO bond. -1 and 1103cm -1 The absorption peak at 1016 cm⁻¹ corresponds to the stretching vibration of the PO bond; -1 and 1124cm -1 The absorption peak at 1195 cm⁻¹ corresponds to the S=O stretching vibration; -1 The absorption peak at 1620 cm⁻¹ corresponds to the CN stretching vibration; -1 The absorption peak at 3441 cm⁻¹ corresponds to the HOH bending vibration in free water. -1 The broad absorption peak at the specified location corresponds to the hydrogen bonds between hydroxyapatite links. These results indicate that sulfides enter the material interior and play a role in morphology regulation. The characteristic peaks of hydroxyapatite and organic carbon coating are evident, and nitrogen-containing organic carbon also exhibits significant carbon and nitrogen characteristic peaks in the composite material, proving the successful synthesis of a carbon-coated hydroxyapatite-supported zinc compound composite material.

[0042] Figure 6 The BET and pore size distribution spectra of the carbon-coated hydroxyapatite-supported zinc compound composite material prepared in Example 1 are shown. The pore size distribution of Example 1 is a typical hierarchical porous structure distribution. The peak intensity and peak width of the micropores and mesopores account for a large proportion. This indicates that the composite material can not only ensure that electrolyte ions react inside the material and inhibit dendrite growth and hydrogen evolution reaction, but also provide ion channels for electrolyte ion migration and improve electrochemical reaction efficiency.

[0043] Figure 7The curves showing the capacity retention versus coulombic efficiency of the carbon-coated hydroxyapatite-supported zinc compound composite material in Example 1 after 200 cycles at a current density of 1C are obtained by... Figure 7 As shown in Table 1, the specific capacity of the material in Example 1 is 493.79 mAh / g at a current density of 0.2C. The specific capacity gradually decreases with increasing current density, reaching 253.26 mAh / g at a current density of 2C. After 200 cycles at a current density of 1C, the capacity retention is 95.63%, demonstrating excellent cycling stability.

[0044] The data in Table 1 show that, compared to the performance of Comparative Examples 1-8, the specific capacity of the carbon-coated hydroxyapatite-supported zinc compound composites in the examples is improved, with a capacity retention rate of 93.87-95.63%. Example 1, after induction of the lamellar structure, hydroxyapatite bonding, and organic carbon coating, yielded a material with multiple nucleation sites and a smooth surface. During the electrochemical reaction, the coating layer isolates the electrode material from the acidic ions of the electrolyte, and the hydroxyapatite neutralizes the acidic ions penetrating the coating layer, inhibiting hydrogen evolution. The hierarchical porous structure also enhances the ion shuttle effect and controls volume changes during the electrochemical reaction. The materials obtained in the comparative examples have different morphologies and more obvious defects, resulting in poor electrochemical performance after testing. These results indicate that the carbon-coated hydroxyapatite-supported zinc compound composites possess excellent electrochemical performance and cycle stability in aqueous zinc-ion batteries.

[0045] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. The description of the above embodiments can help understand the principles and methods of the present invention. However, the above embodiments are not unique and should not be construed as limiting the present invention. At the same time, those skilled in the art can make flexible changes to the specific implementation methods and application scope based on the principles and methods of the present invention.

Claims

1. A method for producing a carbon-coated hydroxyapatite-supported zinc compound composite material, characterized by comprising: a step of mixing a zinc compound, a hydroxyapatite, and a carbon source; a step of heating the mixture obtained in the above step; and a step of mixing the mixture obtained in the above step with a solvent. The method comprises the following steps: (1) mixing a zinc source, an organic ligand containing carboxyl and hydroxyl groups, a sulfide and a polar organic solvent, stirring and heating to react to obtain a mixed solution A; (2) adding hydroxyapatite into the mixed solution A to form a mixed solution B, and transferring the mixed solution B into a reaction kettle to perform a staged temperature control reaction, and then performing filtration and drying to obtain a solid reaction product with an accordion-like structure; (3) placing a carbon deposition precursor at the gas inlet of a tube furnace and placing the solid reaction product with the accordion-like structure at the gas outlet of the tube furnace; under an argon atmosphere, a double-temperature-zone independent temperature control method is adopted to perform carbon deposition to obtain a carbon-coated hydroxyapatite loaded zinc compound composite material.

2. The method for preparing a carbon-coated hydroxyapatite supported zinc compound composite material according to claim 1, characterized by, In the step (1), the zinc source is one of zinc nitrate, zinc acetate and zinc chloride; the organic ligand containing carboxyl and hydroxyl groups is one of p-hydroxybenzoic acid, 3,4-dihydroxybenzoic acid, 4-hydroxyphenylacetic acid and p-hydroxyphenylpropionic acid; the sulfide is one of zinc sulfide and sodium sulfide; the polar organic solvent is one of N,N-dimethylformamide and dimethyl sulfoxide; the molar ratio of the zinc source, the organic ligand containing carboxyl and hydroxyl groups and the sulfide is 0.5-3:1:0.05-0.3; and the concentration of the zinc source in the polar organic solvent is 0.2-0.5 mol / L.

3. The method for preparing a carbon-coated hydroxyapatite supported zinc compound composite material according to claim 1, characterized by, In the step (1), the stirring and heating temperature is 50-80 DEG C, and the time is 30-60 min.

4. The method for preparing a carbon-coated hydroxyapatite supported zinc compound composite material according to claim 1, characterized by, In the step (2), the particle size of the hydroxyapatite is nanoscale, and the molar ratio of the hydroxyapatite to the zinc source is 0.02-0.1:1; the temperature and time of the staged temperature control reaction are: first reacting at 60-90 DEG C for 60-120 min, then continuously heating to 140-180 DEG C for 12-24 h; the solvent for the filtration and washing is one of ethanol and methanol; the drying temperature is 80-120 DEG C, and the time is 6-12 h.

5. The method of claim 1, wherein the carbon-coated hydroxyapatite supported zinc compound composite is prepared by the steps of: (a) mixing a zinc compound, a hydroxyapatite, and a carbon source; (b) heating the mixture to a temperature of 600 to 1,000°C; and (c) cooling the mixture to room temperature. In the step (3), the carbon deposition precursor is one of melamine, 1-naphthylamine and urea; the mass ratio of the carbon deposition precursor to the solid reaction product with the accordion-like structure is 0.5-0.8:1; the double-temperature-zone independent temperature control method is: first heating the solid reaction product with the accordion-like structure to 600-750 DEG C at a rate of 2-5 DEG C / min, and then maintaining the temperature for 30-60 min, and then decreasing the temperature to 400-500 DEG C at a rate of 3-5 DEG C / min and maintaining the temperature; then heating the carbon deposition precursor to 750-900 DEG C at a rate of 5-10 DEG C / min, and maintaining the temperature for 120-240 min.

6. Use of a carbon-coated hydroxyapatite supported zinc compound composite material produced by the production method according to any one of claims 1 to 5, characterized in that, The carbon-coated hydroxyapatite loaded zinc compound composite material is applied to a zinc ion aqueous battery.

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