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

Abstract

The application discloses a preparation method and application of a carbon-coated hydroxyapatite loaded zinc compound composite, and belongs to the technical field of aqueous zinc ion batteries. A zinc source, an organic ligand containing carboxyl and hydroxyl, a sulfide and a polar organic solvent are mixed, stirred and heated for reaction; hydroxyapatite is added to a mixed solution and transferred into a reaction kettle for staged temperature control reaction, and is subjected to suction filtration and drying to obtain a solid reaction product with a concertina-like structure; a carbon deposition precursor and the solid reaction product with the concertina-like structure are placed in different heating areas, carbon deposition is carried out in an argon atmosphere by adopting a double-temperature-zone independent temperature control mode, and the carbon-coated hydroxyapatite loaded zinc compound composite is obtained. The concertina-like composite is prepared by adopting the mode of sulfide regulation, hydroxyapatite connection and organic carbon deposition, and has excellent specific capacity and good cycle stability in a zinc ion battery.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aqueous zinc-ion batteries, and particularly relates to a preparation method and application of a carbon-coated hydroxyapatite loaded zinc compound composite material. BACKGROUND

[0002] With the energy crisis and the worsening of the environment, people have more expectations for renewable energy. In recent years, more and more researches have been conducted on lithium-ion batteries, but the lithium resources and safety issues have always been the focus of attention. Aqueous zinc-ion batteries have been widely concerned due to their low cost, high safety, environmental friendliness and high specific capacity. However, the zinc negative electrode of the aqueous zinc-ion battery undergoes dendrite growth and hydrogen evolution reaction during the cycle process, resulting in reduced cycle stability of the battery, and even battery failure.

[0003] Metal organic frameworks have the advantages of large specific surface area and high porosity, and can provide Zn 2+ storage sites. In the current research, the synthesis of metal organic frameworks mostly uses single group ligands. The ligands such as terephthalic acid and trimesic acid only contain a single carboxyl group, and it is very difficult to modify them again after connecting with the metal source. During the electrochemical test, the acidity of the electrolyte cannot be neutralized, and hydrogen evolution reaction will occur. The Chinese patent document with publication number CN119101250A discloses the preparation of MOF-5W material and its application in improving the performance of aqueous zinc-ion batteries through channel restriction effect. Terephthalic acid and sodium hydroxide are added to the solution to form solution A, and zinc acetate dihydrate is added to the solution to form solution B. After mixing the two solutions and reacting, MOF-5W powder is obtained, and after activation, MOF-5W material is obtained. The activation temperature of the MOF-5W powder is only 200℃ for 2h, and the purpose is only to remove the solvent molecules, and the problem of poor conductivity of the MOF material itself is not changed. Moreover, the synthesized MOF-5W has a long rice shape, and the surface is not smooth, which will cause uneven nucleation and lead to the formation of zinc dendrites in the initial nucleation area. The Chinese patent document with publication number CN118867104A discloses a preparation method of a metal organic framework coating for constructing an aqueous zinc-ion battery negative electrode. Zinc ions, dimethyl imidazole and a regulator are mixed, and after reaction, the ZIF-8 precursor solution is centrifuged to obtain a precipitate. An organic solvent and an appropriate amount of binder are mixed into a colloid, which is coated on the zinc negative electrode and dried and cooled. Finally, the electrode is treated at high temperature in an inert atmosphere to fully polymerize the oligomers and optimize the coating crystal type. This method combines electrode material preparation and electrode coating process, and the active material is ZIF-8 monomer, which still cannot avoid the problem of poor conductivity of the MOF material itself. Moreover, the material obtained by this method will have cracks during the coating process, and the electrochemical performance needs to be improved in the zinc-ion battery test.

[0004] In the application of metal organic frameworks in aqueous zinc ion batteries, there are problems of poor conductivity of electrode materials and unsatisfactory rate performance of batteries, and the electrode materials need to be surface modified. In recent years, there are more studies on constructing an artificial interface layer on the zinc negative electrode to induce zinc deposition. Hydroxyapatite is applied in surface modification due to its alkaline hydrolysis, can be neutralized with the acidic electrolyte, and can inhibit the growth of dendrites; calcium in hydroxyapatite can also exchange ions with zinc, induce zinc deposition to improve the electrochemical performance. The Chinese patent document with publication number CN118712319A discloses a zinc anode protective layer and its preparation method and application. The raw materials of the zinc anode protective layer include hydroxyapatite nanowires and sulfonated polyether ether ketone. The method is to spin-coat sulfonated polyether ether ketone on the surface of the zinc anode by taking hydroxyapatite nanowires as the skeleton, which cannot provide migration sites and energy storage sites for electrolyte ions in zinc ion batteries without a substrate material as support; zinc ions are more likely to deposit on the surface of the coating, thereby causing the coating to lose its protective effect and hindering the improvement of electrochemical performance. SUMMARY

[0005] The purpose of the present application is to provide a preparation method and application of carbon-coated hydroxyapatite-loaded zinc compound composite material. The carboxyl and hydroxyl-containing ligand and metal salt are grown into sheet-shaped materials in a polar solvent by sulfide directional regulation, then the nucleation sites of hydroxyapatite are connected with the hydroxyl / carboxyl in the sheet-shaped material to form a material with an accordion-like structure, and finally a layer of organic carbon is coated on the surface of the material by chemical vapor deposition to obtain the final composite material. The composite material has the advantages of smooth surface and hierarchical porous structure, and the coating layer formed by the organic carbon can effectively isolate Zn from the electrolyte and inhibit the occurrence of side reactions; the addition of hydroxyapatite has the effects of connecting sheet-shaped materials and bulk doping, forming a multi-level distributed pore structure, promoting the adsorption and migration of electrolyte ions, and buffering the volume change in the electrochemical process; during the electrochemical reaction process, the electrode material and the acidic ions in the electrolyte are isolated by the coating layer, and if there are a small amount of acidic ions penetrating the coating layer, they are neutralized by the hydroxyapatite, further inhibiting the occurrence of hydrogen evolution reaction, thereby significantly improving the specific capacity and cycle stability of the battery.

[0006] In order to achieve the purpose of the present application, a preparation method of carbon-coated hydroxyapatite-loaded zinc compound composite material is provided, which comprises the following steps:

[0007] (1) Mix zinc source, carboxyl and hydroxyl-containing organic ligand, sulfide and polar organic solvent, stir and heat to react to obtain mixed solution A;

[0008] (2) Add hydroxyapatite to mixed solution A to form mixed solution B, and transfer mixed solution B to a reaction kettle for staged temperature control reaction, and then perform suction filtration and drying to obtain a solid reaction product with an accordion-like structure;

[0009] (3) The deposition carbon precursor is placed in the direction of the gas inlet of the tube furnace, and the solid reactant with an accordion-like structure is placed in the direction of the gas outlet of the tube furnace; carbon deposition is carried out in an argon atmosphere by adopting a double-temperature-zone independent temperature control mode, and a carbon-coated hydroxyapatite loaded zinc compound composite material is obtained.

[0010] Preferably, in the step (1), the zinc source is one of zinc nitrate, zinc acetate and zinc chloride; the organic ligand containing carboxyl and hydroxyl 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 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.

[0011] Preferably, in the step (1), the temperature of the stirring and heating is 50-80 DEG C, and the time is 30-60 min.

[0012] Preferably, 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 segmented temperature control reaction are as follows: first, reaction at 60-90 DEG C for 60-120 min, then, continue to heat to 140-180 DEG C for 12-24 h; the solvent for the washing by filtration is one of ethanol and methanol; the drying temperature is 80-120 DEG C, and the time is 6-12 h.

[0013] Preferably, in the step (3), the deposition carbon precursor is one of melamine, 1-naphthylamine and urea; the mass ratio of the deposition carbon precursor to the solid reactant with an accordion-like structure is 0.5-0.8:1; and the double-temperature-zone independent temperature control mode is as follows: first, heat the solid reactant with an accordion-like structure to 600-750 DEG C at a rate of 2-5 DEG C / min, and keep the temperature for 30-60 min, then, cool to 400-500 DEG C at a rate of 3-5 DEG C / min and keep the temperature; and then, heat the deposition carbon precursor to 750-900 DEG C at a rate of 5-10 DEG C / min, and keep the temperature for 120-240 min.

[0014] The application further provides an application of the carbon-coated hydroxyapatite loaded zinc compound composite material prepared by the above method, which is applied in a water-based zinc ion battery.

[0015] Compared with the prior art, the application has the following beneficial effects:

[0016] 1. The preparation method of the carbon-coated hydroxyapatite loaded zinc-containing compound composite material provided by the application, sulfide induces the formation of a flaky substrate structure, under the coordination of hydroxyapatite and bulk doping, a material with an accordion-like structure is formed, and finally a layer of organic carbon is deposited on the surface to form a composite material. The surface of the composite material is smooth, effectively isolates Zn from the electrolyte to inhibit side reactions, the accordion-like structure can provide a hierarchical porous ion transport channel and reduce the volume change, effectively adsorbs Zn and inhibits the shuttle effect during the electrochemical test, thereby promoting the specific capacity and cycle performance of the zinc ion battery. 2+

[0017] 2. The addition of sulfide induces the formation of a flaky substrate structure, and the solvent will form a solvated ion with the sulfide through solvation, combine with metal ions to form a coordination structure to slow down the nucleation process, and the addition of polar organic solvents can also promote the ionization of hydroxyl / carboxyl ligands into high-activity oxygen-containing groups, accelerate the multidentate chelation with metal ions, increase the interlayer spacing of nucleation molecules, and promote the migration of electrolyte ions; the addition of sulfide will be adsorbed on the high-performance interface to inhibit the growth of nucleation molecules in the vertical direction, and through TEM, it can be observed that the (002) crystal face spacing of the material is 0.21 nm, which is less than the theoretical crystal face spacing 0.26, confirming that the addition of sulfide plays a role in inhibiting the growth in the vertical direction. The inventors found that the composite material obtained without adding sulfide is a polyhedral structure and cannot inhibit the growth in the vertical direction; when the amount of sulfide added is too large, the number of active sites provided by the sulfide increases, and the edge of the material tends to a stable closed state during the reaction process, forming a flaky structure with a certain thickness. Compared with the accordion-like material, the active sites of this material are reduced, and the stored electrolyte ions are less during the electrochemical process, resulting in low capacity.

[0018] ​3、The application plays the role of nucleation first and then phase doping by adding hydroxyapatite to the accordion-like material, and the hydroxyl and carboxyl groups in the organic ligand can provide more nucleation sites. The application selects an organic ligand with both carboxyl and hydroxyl groups for reaction, and the ligand with different functional groups forms a lower structural unit with a lower symmetry during the connection with hydroxyapatite, tends to irregular connection, and thus exhibits an accordion-like structure. The close packing of the lamellar structure can effectively utilize the hydroxyapatite, and the obtained accordion-like material effectively adsorbs and migrates electrolyte ions during the electrochemical reaction, thereby promoting the improvement of electrochemical performance. During the low-temperature reaction stage, calcium ions in the hydroxyapatite preferentially combine with the carboxyl groups on the surface of the lamellar structure to form ionic bonds, and the phosphorus-oxygen bonds on the surface of the hydroxyapatite form a hydrogen bond network with the hydroxyl groups on the surface of the lamellar structure. The hydroxyapatite nanoparticles act as heterogeneous nucleation points, are adsorbed on the edges of the lamellar structure, and induce directional stacking of the lamellar structure. As the reaction temperature increases, a displacement reaction occurs between zinc ions and calcium ions to form a body phase doping effect, a hierarchical pore structure is formed, and a composite material mainly composed of micropores and mesopores is obtained, thereby improving the conductivity of the material. The inventors have found that if a conventional carboxyl ligand is used as the organic ligand, the same coordination form on the surface of the material and the strong attraction between the groups will spontaneously form layer-by-layer stacking. The addition of hydroxyapatite will connect at the edges of the material, inhibit a part of the fully closed layer-by-layer stacking, and obtain a material with irregular structure. These materials have different adsorption strengths of electrolyte ions during the electrochemical process, and the coating layer has low adsorption on the surface of the irregular structure, thereby causing a decrease in electrochemical performance. If no hydroxyapatite is added during the synthesis process, the lamellar material spontaneously grows along the edges to obtain a spherical composite material composed of lamellar structures. With the addition of hydroxyapatite, the nucleation connection process occurs at a low temperature, and the temperature increase is a process of rapid ion migration and structure growth. If only the high-temperature reaction stage is performed without the nucleation pre-anchoring in the low-temperature stage, the reaction rate is fast, and the hydroxyapatite will form a shuttle-shaped connection in different directions. If only the low-temperature reaction is performed, the material stays in the initial nucleation connection stage and cannot perform subsequent lattice doping, thereby obtaining a mixed phase. The irregularity of the coating layer on the surface of the mixed phase can accelerate the combination of the hydroxyapatite in the material with hydrogen ions released during the reaction, accelerate the performance decay of the material, and cause an irreversible reaction.

[0019] 4、The nitrogen-containing organic carbon source is selected, adsorption is realized at defect sites through material activation, carbon source cracking and directional deposition, a carbon layer is uniformly coated on the surface of the accordion-like structure, defects on the surface of the material can be filled, and occurrence of side reactions can be inhibited. First, the accordion-like material is activated, and hydroxyl groups are removed to form oxygen vacancies; then, the deposition carbon precursor is heated at high temperature, the precursor cracks, gaseous carbon migrates to a low-temperature zone under the action of gas flow, and the low-temperature zone is adsorbed on the oxygen vacancies of the accordion-like material to form nitrogen functionalization and directional spreading to form uniform coating, and the thickness of the coating layer is 7.19-8.37 nm. The coating layer formed by the organic carbon can effectively isolate zinc from the electrolyte and also can relieve volume change and improve cycle stability. The inventors find that no carbon source will cause defects of the material to be unable to be coated, electrolyte ions adsorbed in the electrochemical reaction process are not firm, and the performance is poor; and in the traditional coating process, the organic carbon will gradually gasify at high temperature, the coating amount of the composite material is small, and the performance improvement is limited.

[0020] 6、The carbon-coated hydroxyapatite loaded zinc compound composite material prepared by the application is assembled into a water-based zinc ion battery for electrochemical performance test. The capacity can reach 435.67-493.79 mAh / g at a current density of 0.2 C, and the capacity retention rate is 93.87-95.63% after 200 cycles at a current density of 1 C. The above data show that the carbon-coated hydroxyapatite loaded zinc compound composite material prepared by the application has excellent specific capacity and good cycle stability in the zinc ion battery. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The SEM spectrum of the carbon-coated hydroxyapatite loaded zinc compound composite material prepared for Example 1 is shown in the figure;

[0022] Figure 2 The SEM spectrum of the carbon-coated hydroxyapatite loaded zinc compound composite material prepared for Comparative Examples 1-6 is shown in the figure;

[0023] Figure 3 The XRD spectrum of the carbon-coated hydroxyapatite loaded zinc compound composite material prepared for Example 1 and Comparative Example 4 is shown in the figure;

[0024] Figure 4 The TEM spectrum of the carbon-coated hydroxyapatite loaded zinc compound composite material prepared for Example 1 is shown in the figure;

[0025] Figure 5 The FTIR spectrum of the carbon-coated hydroxyapatite loaded zinc compound composite material prepared for Example 1 is shown in the figure;

[0026] Figure 6 The BET spectrum of the carbon-coated hydroxyapatite loaded zinc compound composite material prepared for Example 1 is shown in the figure;

[0027] Figure 7 The capacity retention rate and the curve of coulombic efficiency of the carbon-coated hydroxyapatite supported zinc compound composite prepared in Example 1 at a current density of 1C for 200 cycles. DETAILED DESCRIPTION

[0028] The specific implementation of the present application is further illustrated below in conjunction with the drawings and examples, but the implementation and protection of the present application are not limited thereto. Example 1

[0029] (1) 20 mmol of zinc nitrate, 10 mmol of 4-hydroxyphenylacetic acid, 2 mmol of zinc sulfide and 60 mL of N,N-dimethylformamide were mixed, stirred at 70°C for 45 min to obtain a mixed solution A;

[0030] (2) 0.6 mmol of hydroxyapatite was added to the mixed solution A to form a mixed solution B, and the mixed solution B was transferred to a reaction kettle for reaction at 80°C for 90 min, and then the temperature was raised to 170°C for reaction for 18 h. After cleaning by ethanol filtration, drying at 100°C for 8 h, a solid reaction product with a concertina-like structure was obtained;

[0031] (3) 1.4 g of melamine was placed in a first quartz crucible, and the first quartz crucible was placed in the middle of the thermocouple in the gas inlet direction of the tube furnace (OTF-1200X-II). 2 g of the solid reaction product with a concertina-like structure was placed in a second quartz crucible, and the second quartz crucible was placed in the middle of the thermocouple in the gas outlet direction of the tube furnace. Carbon deposition was carried out under an argon atmosphere by independent temperature control. The parameters were as follows: first for the second quartz crucible region, 2°C / min to 650°C for 45 min, 3°C / min to 400°C; then for the first quartz crucible region, the starting time was the time when the second quartz crucible was reduced to the target temperature, 5°C / min to 900°C for 180 min, to obtain a carbon-coated hydroxyapatite supported zinc compound composite. Example 2

[0032] (1) 10 mmol of zinc acetate, 10 mmol of 3,4-dihydroxybenzoic acid, 1.5 mmol of zinc sulfide and 40 mL of dimethyl sulfoxide were mixed, stirred at 50°C for 60 min to obtain a mixed solution A;

[0033] (2) 0.5 mmol of hydroxyapatite was added to the mixed solution A to form a mixed solution B, and the mixed solution B was transferred to a reaction kettle for reaction at 90°C for 70 min, and then the temperature was raised to 140°C for reaction for 24 h. After cleaning by methanol filtration, drying at 120°C for 6 h, a solid reaction product with a concertina-like structure was obtained;

[0034] (3) Put 1.6 g of 1-naphthylamine into a first quartz crucible, and place the first quartz crucible in the middle of the thermocouple in the gas inlet direction of the tube furnace (OTF-1200X-II); put 2 g of the accordion-like structure solid reactant into a second quartz crucible, and place the second quartz crucible in the middle of the thermocouple in the gas outlet direction of the tube furnace. Under an argon atmosphere, carbon deposition is carried out in an independent temperature control manner, and the parameters are as follows: first, the region of the second quartz crucible, 5 ℃ / min to 700 ℃, 30 min, 5 ℃ / min to 450 ℃; then, the region of the first quartz crucible, the starting time is the time when the second quartz crucible is reduced to the target temperature, 6 ℃ / min to 850 ℃, 200 min, to obtain a carbon-coated hydroxyapatite loaded zinc compound composite material. Example 3

[0035] (1) Mix 30 mmol of zinc chloride, 10 mmol of p-hydroxybenzoic acid, 3 mmol of sodium sulfide, and 60 mL of N,N-dimethylformamide, stir at 80 ℃ for 30 min, to obtain a mixed solution A;

[0036] (2) Add 0.6 mmol of hydroxyapatite to the mixed solution A to form a mixed solution B, and transfer the mixed solution B to a reaction kettle, react at 60 ℃ for 120 min, then heat to 180 ℃ for 12 h, ethanol filtration and washing, and then dry at 80 ℃ for 12 h, to obtain an accordion-like structure solid reactant;

[0037] (3) Put 1 g of urea into a first quartz crucible, and place the first quartz crucible in the middle of the thermocouple in the gas inlet direction of the tube furnace (OTF-1200X-II); put 2 g of the accordion-like structure solid reactant into a second quartz crucible, and place the second quartz crucible in the middle of the thermocouple in the gas outlet direction of the tube furnace. Under an argon atmosphere, carbon deposition is carried out in an independent temperature control manner, and the parameters are as follows: first, the region of the second quartz crucible, 2 ℃ / min to 650 ℃, 45 min, 3 ℃ / min to 400 ℃; then, the region of the first quartz crucible, the starting time is the time when the second quartz crucible is reduced to the target temperature, 5 ℃ / min to 900 ℃, 180 min, to obtain a carbon-coated hydroxyapatite loaded zinc compound composite material. Example 4

[0038] (1) Mix 10 mmol of zinc nitrate, 20 mmol of 3,4-dihydroxybenzoic acid, 1 mmol of sodium sulfide, and 50 mL of N,N-dimethylformamide, stir at 80 ℃ for 50 min, to obtain a mixed solution A;

[0039] (2) 1 mmol hydroxyapatite was added into the mixed solution A to form a mixed solution B, and the mixed solution B was transferred into a reaction kettle to react at 70°C for 100 min, and then the temperature was increased to 150°C to react for 20 h. After being cleaned by methanol extraction and filtration, and dried at 90°C for 10 h, an accordion-like structure solid reactant was obtained;

[0040] (3) 1.2 g of 1-naphthylamine was placed into a first quartz crucible, and the first quartz crucible was placed in the middle of a thermocouple in the direction of the gas inlet of a tube furnace (OTF-1200X-II). 2 g of the accordion-like structure solid reactant was placed into a second quartz crucible, and the second quartz crucible was placed in the middle of a thermocouple in the direction of the gas outlet of the tube furnace. Carbon deposition was carried out in an argon atmosphere by using independent temperature control. The parameters were as follows: first, the second quartz crucible region was heated at a rate of 3°C / min to 600°C and kept for 60 min, and then cooled at a rate of 3°C / min to 500°C; then, the first quartz crucible region was heated at a rate of 8°C / min to 750°C and kept for 220 min, starting at the time when the second quartz crucible was cooled to the target temperature, to obtain a carbon-coated hydroxyapatite supported zinc compound composite material. Example 5

[0041] (1) 30 mmol of zinc nitrate, 10 mmol of 4-hydroxyphenylacetic acid, 1.5 mmol of sodium sulfide and 80 mL of dimethyl sulfoxide were mixed to obtain a mixed solution A, which was stirred at 70°C for 35 min;

[0042] (2) 1.5 mmol of hydroxyapatite was added into the mixed solution A to form a mixed solution B, and the mixed solution B was transferred into a reaction kettle to react at 80°C for 60 min, and then the temperature was increased to 160°C to react for 14 h. After being cleaned by ethanol extraction and filtration, and dried at 110°C for 8 h, an accordion-like structure solid reactant was obtained;

[0043] (3) 1.4 g of melamine was placed into a first quartz crucible, and the first quartz crucible was placed in the middle of a thermocouple in the direction of the gas inlet of a tube furnace (OTF-1200X-II). 2 g of the accordion-like structure solid reactant was placed into a second quartz crucible, and the second quartz crucible was placed in the middle of a thermocouple in the direction of the gas outlet of the tube furnace. Carbon deposition was carried out in an argon atmosphere by using independent temperature control. The parameters were as follows: first, the second quartz crucible region was heated at a rate of 5°C / min to 650°C and kept for 50 min, and then cooled at a rate of 5°C / min to 400°C; then, the first quartz crucible region was heated at a rate of 9°C / min to 900°C and kept for 140 min, starting at the time when the second quartz crucible was cooled to the target temperature, to obtain a carbon-coated hydroxyapatite supported zinc compound composite material. Example 6

[0044] (1) 10 mmol zinc acetate, 20 mmol p-hydroxybenzoic acid, 2 mmol zinc sulfide and 50 mL N,N-dimethylformamide were mixed, stirred at 60°C for 40 min to obtain a mixed solution A;

[0045] (2) 0.4 mmol hydroxyapatite was added into the mixed solution A to form a mixed solution B, and the mixed solution B was transferred into a reaction kettle to react at 60°C for 80 min, then the temperature was increased to 170°C to react for 16 h. After ethanol filtration and washing, drying at 100°C for 12 h, a solid reaction product with accordion-like structure was obtained;

[0046] (3) 1.2 g urea was placed in a first quartz crucible, and the first quartz crucible was placed in the middle of the thermocouple in the gas inlet direction of the tube furnace (OTF-1200X-II). 2 g of the solid reaction product with accordion-like structure was placed in a second quartz crucible, and the second quartz crucible was placed in the middle of the thermocouple in the gas outlet direction of the tube furnace. Under argon atmosphere, carbon deposition was carried out by independent temperature control. The parameters were as follows: first, the second quartz crucible region was heated at 2°C / min to 700°C and kept for 55 min, then cooled at 5°C / min to 450°C; then, the first quartz crucible region was heated at 7°C / min to 800°C and kept for 160 min, starting at the time when the second quartz crucible was cooled to the target temperature, to obtain a carbon-coated hydroxyapatite supported zinc compound composite material. Example 7

[0047] (1) 20 mmol zinc chloride, 10 mmol p-hydroxybenzoic acid, 2 mmol zinc sulfide and 70 mL dimethyl sulfoxide were mixed, stirred at 50°C for 55 min to obtain a mixed solution A;

[0048] (2) 1.5 mmol hydroxyapatite was added into the mixed solution A to form a mixed solution B, and the mixed solution B was transferred into a reaction kettle to react at 90°C for 110 min, then the temperature was increased to 180°C to react for 22 h. After methanol filtration and washing, drying at 90°C for 6 h, a solid reaction product with accordion-like structure was obtained;

[0049] (3) 1.6 g melamine was placed in a first quartz crucible, and the first quartz crucible was placed in the middle of the thermocouple in the gas inlet direction of the tube furnace (OTF-1200X-II). 2 g of the solid reaction product with accordion-like structure was placed in a second quartz crucible, and the second quartz crucible was placed in the middle of the thermocouple in the gas outlet direction of the tube furnace. Under argon atmosphere, carbon deposition was carried out by independent temperature control. The parameters were as follows: first, the second quartz crucible region was heated at 3°C / min to 750°C and kept for 35 min, then cooled at 4°C / min to 500°C; then, the first quartz crucible region was heated at 5°C / min to 850°C and kept for 240 min, starting at the time when the second quartz crucible was cooled to the target temperature, to obtain a carbon-coated hydroxyapatite supported zinc compound composite material. Comparative Example 1

[0050] In the present comparative example, no sulfide is added, i.e. 20 mmol of zinc nitrate, 10 mmol of 4-hydroxyphenylacetic acid and 60 mL of N,N-dimethylformamide are mixed, stirred at 70°C for 45 min to obtain a mixed solution A, and the other processes are consistent with those of Example 1. Comparative Example 2

[0051] In the present comparative example, the organic ligand is selected as a single group ligand, i.e. terephthalic acid, i.e. 20 mmol of zinc nitrate, 10 mmol of terephthalic acid, 2 mmol of zinc sulfide and 60 mL of N,N-dimethylformamide are mixed, stirred at 70°C for 45 min to obtain a mixed solution A, and the other processes are consistent with those of Example 1. Comparative Example 3

[0052] In the present comparative example, the amount of sulfide added is 5 mmol, i.e. 20 mmol of zinc nitrate, 10 mmol of 4-hydroxyphenylacetic acid, 5 mmol of zinc sulfide and 60 mL of N,N-dimethylformamide are mixed, stirred at 70°C for 45 min to obtain a mixed solution A, and the other processes are consistent with those of Example 1. Comparative Example 4

[0053] In the present comparative example, no hydroxyapatite is added in step (2), i.e. the mixed solution A is transferred into a reaction kettle, reacted at 80°C for 90 min, then the temperature is increased to 170°C for 18 h, and then ethanol is used to filter and wash, and then dried at 100°C for 8 h to obtain a solid reaction product with a concertina-like structure, and the other processes are consistent with those of Example 1. Comparative Example 5

[0054] In the present comparative example, only the second stage of 170°C for 18 h is used for the reaction in the reaction kettle in step (2), i.e. 0.6 mmol of hydroxyapatite is added to the mixed solution A to form a mixed solution B, the mixed solution B is transferred into a reaction kettle, reacted at 170°C for 18 h, and then ethanol is used to filter and wash, and then dried at 100°C for 8 h to obtain a solid reaction product with a concertina-like structure, and the other processes are consistent with those of Example 1. Comparative Example 6

[0055] In the present comparative example, only the first stage of 80°C for 90 min is used for the reaction in the reaction kettle in step (2), i.e. 0.6 mmol of hydroxyapatite is added to the mixed solution A to form a mixed solution B, the mixed solution B is transferred into a reaction kettle, reacted at 80°C for 90 min, and then ethanol is used to filter and wash, and then dried at 100°C for 8 h to obtain a solid reaction product with a concertina-like structure, and the other processes are consistent with those of Example 1. Comparative Example 7

[0056] In the comparative example, step (3) does not add a deposited carbon precursor, i.e., 2 g of the solid reaction substance with an accordion-like structure is placed in the second quartz crucible, and the second quartz crucible is placed in the middle of the thermocouple in the gas outlet direction of the tube furnace (OTF-1200X-II). In an argon atmosphere, the calcination is performed in an independent temperature control manner, and the parameters are as follows: the second quartz crucible region is heated at a rate of 2 ℃ / min to 650 ℃ and maintained for 45 min, and the final composite material is obtained. The other processes are consistent with those of Example 1. Comparative Example 8

[0057] In the comparative example, step (3) does not add a deposited carbon precursor, i.e., 2 g of the solid reaction substance with an accordion-like structure is placed in the second quartz crucible, and the second quartz crucible is placed in the middle of the thermocouple in the gas outlet direction of the tube furnace (OTF-1200X-II). In an argon atmosphere, the calcination is performed in an independent temperature control manner, and the parameters are as follows: the second quartz crucible region is heated at a rate of 2 ℃ / min to 650 ℃ and maintained for 45 min, and the final composite material is obtained. The other processes are consistent with those of Example 1.

[0058] The prepared carbon-coated hydroxyapatite supported zinc compound composite material is applied to a water-based zinc ion battery. The active material, acetylene black and PVDF are weighed in a mass ratio of 8:1:1, added to NMP and stirred into a thick slurry, and then scraped onto a copper foil. After drying, the φ12 electrode sheet is cut using a slicing machine. The zinc ion battery is assembled in a glove box, and the electrochemical test is performed after standing for 2-4 h.

[0059] The above electrode sheet is used as the negative electrode, the positive electrode is a conventional MnO2 positive electrode, the separator is a GF / F glass fiber separator, and the electrolyte is 2M ZnSO4+0.1M MnSO4. The CR2032 type zinc ion battery is assembled and subjected to electrochemical test. The galvanostatic charge-discharge curve (GCD) test conditions are as follows: voltage window 1.0-1.9 V (Vs Zn 2+ / Zn), current density 0.2 C, 0.5 C, 1 C, 1.5 C and 2 C. The capacity retention rate is tested at a current density of 1 C after 200 cycles.

[0060] The performance of the electrode material obtained from the examples and comparative examples is shown in Table 1.

[0061]

[0062] Figure 1 and Figure 2The SEM spectra of the carbon-coated hydroxyapatite supported zinc compound composite materials prepared in Example 1 and Comparative Examples 1-6, respectively, Example 1 obtained a sheet structure of accordion-like composite material formed by dense packing, indicating that under the action of polar solvent dispersion, sulfide traction and hydroxyapatite connection, an accordion-like composite material was obtained, the dense packing of the sheet layer can effectively utilize the hydroxyapatite, and the organic carbon can also be uniformly coated on the surface to form a multi-level pore structure and an accordion-like material mainly with micropores and mesopores, which can effectively adsorb and migrate electrolyte ions during the electrochemical reaction, promoting the improvement of electrochemical performance; Comparative Example 1 does not add sulfide, and the material grows normally along the vertical direction to obtain a polyhedral material; Comparative Example 2 selects a ligand with only a carboxyl group, the addition of hydroxyapatite will connect the edge part of the sheet structure, and the same coordination form on the surface of the material will spontaneously form layer-by-layer stacking to obtain a material mostly in the form of irregular polyhedron; Comparative Example 3 adds an excess of sulfide, and the active sites increase when the hydroxyapatite connects the sheet material, which is more inclined to connect between the sheet structures to form a sheet material with sheet layer stacking, the active sites of this material are reduced compared with the accordion-like material, and the capacity for storing electrolyte ions during the electrochemical process is low; Comparative Example 4 does not add hydroxyapatite to connect the sheet material, and the sheet material spontaneously grows along the edge to obtain an accordion-like composite material composed of sheet materials, the irregular accumulation of the material leads to uneven charge migration during the electrochemical process, and the capacity and cycle performance are reduced; Comparative Example 5 does not undergo a low-temperature reaction kettle reaction, and lacks the low-temperature connection of the hydroxyapatite to the sheet material, with the rapid increase of temperature, the ion activity is enhanced, the connection direction between the materials is irregular to obtain a shuttle-shaped structure, and the uneven charge migration causes the performance to decrease; Comparative Example 6 does not undergo a high-temperature reaction kettle reaction, and the sheet structure is not subjected to a growth process after connection to obtain a mixed-phase material, which causes the surface of the material to be not firmly attracted to the charge, and the capacity and cycle performance are reduced.

[0063] Figure 3 The XRD spectra of the carbon-coated hydroxyapatite supported zinc compound composite materials prepared in Example 1 and Comparative Example 4, the composite material obtained in Example 1 can well correspond to the characteristic peaks of zinc oxide and hydroxyapatite, Comparative Example 4 does not add hydroxyapatite to obtain a material corresponding to the characteristic peaks of zinc oxide, proving that the carbon-coated hydroxyapatite supported zinc compound composite material is successfully synthesized by the method. In Example 1, the diffraction peak is wide, and the diffraction angle at (002), (101) appears right shift phenomenon, through the Scherrer formula, the interplanar distance is inversely proportional to the diffraction angle, the interplanar distance corresponding to (002), (101) is reduced, the growth of the material along the C axis is inhibited, and it is proved that the addition of hydroxyapatite and bulk doping.

[0064] Figure 4TEM 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 deposited and migrated to the low-temperature zone under the action of gas flow to deposit, and the organic carbon deposition obtained a uniform coating layer with an average thickness of 7.84 nm, the interplanar spacing of the (002) and (101) crystal planes was 0.21 nm and 0.26 nm, both of which were smaller than the theoretical interplanar spacing of 0.26 nm and 0.28 nm, which was consistent with the XRD data, indicating that the carbon-coated hydroxyapatite supported zinc compound composite material was successfully synthesized.

[0065] Figure 5 FT-IR spectrum of the carbon-coated hydroxyapatite supported zinc compound composite material prepared in Example 1, the absorption peak at 441 cm -1 corresponds to the Zn-O bond stretching vibration peak; the absorption peak at 575 cm -1 is the calcium and hydroxyl connection and the Ca-O bond stretching vibration peak after calcium replaces zinc; the absorption peaks at 606 cm -1 and 637 cm -1 correspond to the bending vibration of P-O bond, the absorption peaks at 1051 cm -1 and 1103 cm -1 correspond to the stretching vibration of P-O bond; the absorption peaks at 1016 cm -1 and 1124 cm -1 correspond to the S=O stretching vibration; the absorption peak at 1195 cm -1 corresponds to the C-N stretching vibration; the absorption peak at 1620 cm -1 corresponds to the H-O-H bending vibration in free water, and the wide absorption peak at 3441 cm -1 corresponds to the hydrogen bond between the hydroxyapatite connections. From the above results, it can be shown that the sulfide enters the material interior to play a role in morphology control, the hydroxyapatite and organic carbon layer coating characteristic peaks are obvious, and the nitrogen-containing organic carbon also has obvious carbon-nitrogen characteristic peaks in the composite material, proving that the carbon-coated hydroxyapatite supported zinc compound composite material is successfully synthesized.

[0066] Figure 6 BET and pore size distribution spectrum of the carbon-coated hydroxyapatite supported zinc compound composite material prepared in Example 1, the pore size distribution of Example 1 is a typical hierarchical porous structure distribution, and the peak intensity and peak width of the micropore and mesopore are large, which indicates that the composite material not only can ensure that the electrolyte ions react inside the material, inhibit the growth of dendrites and the occurrence of hydrogen evolution reaction, but also can provide ion channels for the migration of electrolyte ions, and improve the efficiency of electrochemical reaction.

[0067] Figure 7The capacity retention rate and coulombic efficiency curve of the carbon-coated hydroxyapatite supported zinc compound composite material in Example 1 at a current density of 1C for 200 cycles are shown in Figure 2. Figure 7 It can be found from Table 1 that the specific capacity of the material in Example 1 at a current density of 0.2C is 493.79 mAh / g, and the specific capacity gradually decreases with the increase of the current density, and the specific capacity at a current density of 2C is 253.26 mAh / g. The capacity retention rate for 200 cycles at a current density of 1C is 95.63%, and the material has excellent cycle stability.

[0068] It can be found from the data in Table 1 that the specific capacity of the carbon-coated hydroxyapatite supported zinc compound composite material in the examples is improved compared with the performance of Comparative Examples 1-8, and the capacity retention rate is 93.87-95.63%. After the sheet structure induction, hydroxyapatite connection, and organic carbon coating of Example 1, the material with multiple nucleation sites and smooth surface is obtained. The coating layer separates the electrode material from the acidic ions in the electrolyte during the electrochemical reaction, and the hydroxyapatite can also neutralize the acidic ions that penetrate the coating layer to inhibit the hydrogen evolution reaction. The multi-level porous structure can also improve the ion shuttling effect and control the volume change during the electrochemical reaction. The materials obtained in the comparative examples have different morphologies and obvious defects, and the electrochemical performance is poor. The above results show that the carbon-coated hydroxyapatite supported zinc compound composite material has excellent electrochemical performance and cycle stability in aqueous zinc ion batteries.

[0069] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described, however, as long as the combinations of the technical features do not contradict each other, they should be considered within the scope of the present disclosure. The above examples are used to help understand the principles and methods of the present disclosure. However, the above examples are not unique and should not be construed as limiting the present disclosure. Meanwhile, based on the principles and methods of the present disclosure, those skilled in the art can make flexible changes in specific embodiments and application ranges.

Claims

1. A method for preparing a carbon-coated hydroxyapatite-supported zinc compound composite material, characterized in that, Includes 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 reactor 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 an argon atmosphere, carbon deposition is carried out by a dual-temperature zone independent temperature control method to obtain a carbon-coated zinc compound composite material supported by hydroxyapatite. In step (1), the molar ratio of zinc source, organic ligand containing carboxyl and hydroxyl groups, and sulfide is 0.5~3:1:0.05~0.3; the concentration of zinc source in polar organic solvent is 0.2~0.5 mol / L. In step (2), 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 raise the temperature to 140~180℃ for 12~24h. In step (3), the mass ratio of the carbon deposition precursor to the accordion-like solid reactant is 0.5~0.8:1; the dual-temperature zone independent temperature control method 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, and then cooled to 400~500℃ at a rate of 3~5℃ / min and held continuously. The carbon precursor is then heated to 750-900℃ at a rate of 5-10℃ / min and held for 120-240min.

2. The method for preparing the carbon-coated hydroxyapatite-supported zinc compound composite material according to claim 1, characterized in that, 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; and the polar organic solvent is one of N,N-dimethylformamide and dimethyl sulfoxide.

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

4. The method for preparing the carbon-coated hydroxyapatite-supported zinc compound composite material according to claim 1, characterized in that, In step (2), the particle size of hydroxyapatite is in the nanometer range, and the molar ratio of hydroxyapatite to zinc source is 0.02~0.1:

1.

5. The method for preparing the carbon-coated hydroxyapatite-supported zinc compound composite material according to claim 1, characterized in that, In step (3), the carbon deposition precursor is one of melamine, 1-naphthylamine, and urea.

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

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