Sulfide porphyrin-based covalent triazine composite cathode material and preparation method and application thereof

Abstract

The present invention discloses a sulfided porphyrin-based covalent triazine composite positive electrode material and a preparation method and application thereof. The porphyrin-based covalent triazine composite positive electrode is prepared by the following method: (1) using bipyrrole and p-cyanobenzaldehyde to react to obtain a porphyrin-based monomer; (2) using the porphyrin-based monomer obtained in step (1) to mix with anhydrous zinc chloride in a vacuum quartz tube for sintering reaction and post-treatment to obtain a target porphyrin-based covalent triazine polymer; (3) after being mixed with elemental sulfur and vacuum sintered; (4) the obtained material is made into a composite positive electrode equipped with an all-solid-state battery. The porphyrin-based covalent triazine framework material prepared by the ion melting method of the present invention has a high specific surface area. When used as a cathode material for lithium-ion batteries, it has the advantages of high capacity, good rate performance, etc., and has a good application prospect in new high-performance organic electrode materials.

Description

Technical Field

[0001] The invention belongs to the technical field of new energy, and in particular relates to a sulfided porphyrin-based covalent triazine composite positive electrode material and a preparation method and application thereof. Background Art

[0002] As environmental awareness in various countries gradually increases, electric vehicles are increasingly sought after by people. The market has also put forward new requirements and expectations for high-performance batteries. Solid-state batteries have many advantages such as high safety factor, high energy density, simple packaging, and wide operating temperature range, and are considered to be the next generation of electrochemical energy storage components with very good prospects. Lithium-sulfur batteries have been widely studied in recent years. In all-solid-state lithium-sulfur batteries, the conversion of sulfur does not involve the generation and movement of soluble polysulfides, so the problem of polysulfide shuttle effect can be fundamentally solved. On the other hand, the inherent rigidity and non-flammability of solid electrolytes can greatly reduce the risk of combustion and significantly improve battery safety. However, the practical application of all-solid-state lithium-sulfur batteries is still a huge challenge. The cathode materials used in traditional lithium-sulfur solid-state batteries are generally ternary lithium, lithium iron phosphate, lithium cobalt oxide and lithium manganese oxide. However, these cathode materials have poor compatibility with sulfide solid electrolyte materials, poor stability, and low energy density. The literature on the reported sulfurized materials as all-solid-state battery cathodes generally has problems such as low sulfur content, low sulfur utilization, and poor cycle performance.

[0003] CN202111005664 reported a high-density metallized covalent triazine polymer based on porphyrin and pyrimidine, and its preparation method and application, which is applied in the field of catalytic conversion of carbon dioxide. Summary of the invention

[0004] The object of the present invention is to provide a sulfided porphyrin-based covalent triazine composite cathode material and a preparation method and application thereof. The object of the present invention is achieved through the following technical solutions:

[0005] The present invention provides a porphyrin sulfide-based covalent triazine composite positive electrode material, and a method for preparing the positive electrode material comprises the following steps:

[0006] S1, reacting bispyrrole with p-cyanobenzaldehyde under the protection of an inert gas to obtain a porphyrin-based monomer;

[0007] S2, combining the porphyrin-based monomer of step S1 with a metal element to form a metal porphyrin complex;

[0008] S3, reacting the metal porphyrin complex of step S2 with zinc chloride to obtain a covalent triazine polymer;

[0009] S4, sintering the covalent triazine polymer of step S3 with sublimated sulfur to obtain a sulfided porphyrin-based covalent triazine material;

[0010] S5. Mix the porphyrin sulfide covalent triazine material obtained in step S4 with a sulfide solid electrolyte and conductive carbon and perform ball milling to obtain the porphyrin sulfide covalent triazine composite positive electrode material.

[0011] In step S2, the metal element includes one or more of Ni, Zn, Cu, Ru, Pt, and Co elements.

[0012] Step S3 specifically comprises reacting the metal porphyrin complex of step S2 with anhydrous zinc chloride at 300-500° C. in a vacuum quartz tube to obtain a crude covalent triazine polymer product, and purifying the covalent triazine polymer.

[0013] In step S4, the covalent triazine polymer of step S3 and sublimated sulfur are sintered at 150-300° C. for 1-6 hours under vacuum conditions to obtain a sulfided porphyrin-based covalent triazine material, wherein the mass ratio of the sublimated sulfur to the covalent triazine polymer is 1:1-3:1. If the sulfur content is too low, the theoretical capacity cannot be exerted. If the sulfur content is too high, the long-cycle performance is affected, and the capacity is rapidly decayed in the later stage of the cycle, and the stability decreases instead of increases.

[0014] In step S5, the sulfide solid electrolyte includes Li 5.5 PS 4.5 Cl 1.5 , Li 6 PS 5 Cl, Li 10 G 2 S 12 , Li 9.5 4Si 1.74 P 1.44 S 11.7 Cl 0.3 , Li 10 SnP 2 S 12 One or more of the following.

[0015] In step S5, the conductive carbon includes one or more of conductive carbon black, carbon nanotubes, graphene, graphite sheets, and activated carbon fibers.

[0016] The structural formula of the covalent triazine polymer is as follows:

[0017]

[0018] Where: M is a metal element, Represents a repeating structural unit.

[0019] The application of the composite positive electrode material in an all-solid-state battery also falls within the protection scope of the present invention.

[0020] An all-solid-state battery comprising the composite positive electrode material also falls within the protection scope of the present invention.

[0021] The negative electrode active material of the all-solid-state battery includes a carbon series material, a Si-containing carbon series material or an olivine structure transition metal material; the carbon series material is artificial graphite, natural graphite, hard carbon or graphene, and the olivine structure transition metal material includes Li 4 Ti 5 O 12 、LiNbTi 2 O 7 wait.

[0022] As another embodiment of the present invention, a method for preparing an all-solid-state battery using porphyrin sulfide covalent triazine as a positive electrode material comprises the following steps:

[0023] (1) Bis-pyrrole reacts with p-cyanobenzaldehyde under inert gas protection to obtain a crude porphyrin monomer product, which is then purified by chromatography to obtain a pure sample. The porphyrin monomer is then combined with various metals (Ni, Zn, Cu, Ru, Pt, etc.) to form a metal porphyrin complex. A pure sample is then purified by chromatography to obtain a pure sample.

[0024] (2) reacting the obtained porphyrin-based monomer with anhydrous zinc chloride in a vacuum quartz tube at 300-500° C. to obtain a crude covalent triazine polymer product, and performing a series of purification to obtain a purified covalent triazine polymer.

[0025] (3) The covalent triazine polymer purified by column chromatography is sintered with sublimed sulfur at 150-300° C. for 1-6 h under vacuum conditions to obtain a sulfided porphyrin-based covalent triazine material.

[0026] (4) The obtained sulfide porphyrin covalent triazine material, sulfide solid electrolyte, and conductive carbon VGCF are mixed and ball-milled on a planetary ball mill for 1-3 hours to obtain a composite positive electrode.

[0027] (5) Apply the composite positive electrode to the assembly of all-solid-state batteries.

[0028] Preferably, in the all-solid-state battery using porphyrin-based covalent triazine as the positive electrode material, the weight of the solid electrolyte in the composite positive electrode part of the all-solid-state battery accounts for 40wt% of the total weight.

[0029] Covalent triazine framework (CTF) is a type of microporous polymer with narrow pore size distribution, extremely high specific surface area (up to 3000m 2g-1) and medium conductivity. Sulfur is one of the most abundant elements. More than 70 million tons of elemental sulfur are produced each year as a byproduct of the hydrodesulfurization process in the petroleum refining industry. The technical solution of the present invention is to introduce sulfur into covalent triazine to prepare sulfurized covalent triazine, which has broad prospects for application in all-solid-state batteries. The basic reaction formula of the present invention is as follows:

[0030]

[0031] The key point of this application is to use a sulfide porphyrin-based triazine composite positive electrode material to assemble an all-solid-state battery; through the triazine material with an ultra-large specific surface area and a porous structure to compound more sulfur and provide more channels for lithium ion migration during battery use, the lithium ion deposition is made more uniform. Traditional sulfur-carbon materials cannot compound more sulfur and provide channels for ion migration. The present invention has excellent energy density and cycle life, as well as good compatibility with sulfide solid electrolytes. Because it benefits from the formation of well-restricted sulfur substances in the micropores, the bonding of sulfur to the framework, and the good electronic and ionic conductivity of the framework. Our research results prove that the all-solid-state battery with this sulfide porphyrin-based covalent triazine as the positive electrode material has excellent energy density and cycle life, as well as good compatibility with sulfide solid electrolytes. It is expected to promote further research in this field.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. The prepared composite cathode material is applied to all-solid-state batteries, which improves the cycle stability of the battery;

[0034] 2. The introduction of sulfide electrolyte during the preparation of the positive electrode improves the overall electrochemical performance of the battery; the ultra-high sulfur content matches the sulfide solid electrolyte to assemble a solid-state battery with good cycle stability;

[0035] 3. When preparing positive electrode active materials, a porphyrin rigid skeleton is used to increase the specific surface area of ​​the material;

[0036] 4. The prepared material is porous, providing a channel for ion migration, making lithium ion deposition more uniform and improving electrochemical performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Capacity performance comparison diagram of Example 1 and Comparative Example 1;

[0038] Figure 2 Capacity performance comparison chart of Example 1 and Comparative Example 2. DETAILED DESCRIPTION

[0039] The present invention is described in detail below in conjunction with embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, some adjustments and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0040] Example 1

[0041] (1) Preparation of sulfidated porphyrin-based covalent triazine composite cathode materials

[0042] A: 500 mg of p-cyanobenzaldehyde, 400 mg of bispyrrole, 1 mL of boron trifluoride etherate (mass concentration 48%), and 500 mL of distilled chloroform were placed in a three-necked flask. The mixture in the flask was degassed with Ar gas for 20 minutes, reacted under inert gas for 2 hours, and then dichlorodicyanobenzoquinone (4.15 g) was added to quench the reaction. The product was then evaporated to remove the solvent and subjected to column chromatography to obtain a purple product, which was the porphyrin-based monomer.

[0043] B: Take 550 mg of the porphyrin monomer obtained in step A, 30 mL of redistilled chloroform, 20 mL of saturated cobalt nitrate hexahydrate, and 15 mL of methanol to react to obtain a metal porphyrin complex, and purify it by column chromatography to obtain a pure sample of the metal porphyrin complex;

[0044] C: 100 mg of the metal porphyrin complex prepared in step B and 1000 mg of anhydrous zinc chloride were placed in a quartz tube and ground and mixed evenly. The tube was sealed in vacuum and sintered at 350° C. for 40 h. After purification, a pure sample of covalent triazine polymer was obtained.

[0045] D: 300 mg of sublimated sulfur and covalent triazine polymer were placed in a quartz tube at a ratio of 3:1 and sintered at 300 °C for 3 h to obtain the sulfide triazine material;

[0046] E: The porphyrin sulfide covalent triazine material obtained in step D is reacted with a sulfide solid electrolyte (Li 5.5 PS 4.5 Cl 1.5 ), the conductive carbon VGCF is mixed and ball-milled on a planetary ball mill at a mass ratio of 5:4:1 for 1-3 hours to obtain the sulfided porphyrin-based covalent triazine composite positive electrode material.

[0047] (2) Preparation of Co-coordinated porphyrin-based triazine all-solid-state batteries.

[0048] Apply composite positive electrodes to the assembly of all-solid-state batteries.

[0049] a. Combining sulfide porphyrin-based covalent triazine composite cathode material, conductive carbon material VGCF and sulfide solid electrolyte material (Li 5.5 PS4.5 Cl 1.5 ) in a mass ratio of 5:1:4, grind them evenly to obtain positive electrode active material powder, disperse the positive electrode active material powder in a 5% polyvinylidene fluoride-N-methylpyrrolidone solution (4 mL), stir evenly and apply it on an aluminum foil to obtain a positive electrode sheet;

[0050] b. Sulfide solid electrolyte material (Li 5.5 PS 4.5 Cl 1.5 ) is placed in a tablet pressing mold to obtain a solid electrolyte sheet (thickness controlled at 100-500μm) used to assemble the battery. Then the positive electrode sheet is placed on one side of the solid electrolyte sheet and pressed. Finally, lithium foil is attached to the other side of the solid electrolyte to form a sandwich structure all-solid-state battery.

[0051] Example 2

[0052] (1) Preparation of sulfidated porphyrin-based covalent triazine composite cathode materials

[0053] A: 500 mg of p-cyanobenzaldehyde, 400 mg of bispyrrole, 1 mL of boron trifluoride etherate (mass concentration 48%), and 500 mL of distilled chloroform were placed in a three-necked flask. The mixture in the flask was degassed with Ar gas for 20 minutes, reacted under inert gas for 2 hours, and then dichlorodicyanobenzoquinone (4.15 g) was added to quench the reaction. The product was then evaporated to remove the solvent and subjected to column chromatography to obtain a purple product, which was the porphyrin-based monomer.

[0054] B: 550 mg of the porphyrin monomer obtained in step A, 10 mL of saturated ruthenium dodecacarbonyl solution, and 15 mL of DMF were placed in a reaction flask. The mixture in the flask was degassed with Ar gas for 20 minutes and then reacted at 80° C. to obtain a metal porphyrin complex. A pure sample was obtained after purification by column chromatography.

[0055] C: 100 mg of the metal porphyrin complex prepared in step B and 1000 mg of anhydrous zinc chloride were placed in a quartz tube and ground and mixed evenly. The tube was sealed in vacuum and sintered at 350° C. for 40 h. After purification, a pure sample of covalent triazine polymer was obtained.

[0056] D: 300 mg of sublimated sulfur and covalent triazine polymer were sintered in a quartz tube at 300°C for 3 h in a ratio of 1:1 to obtain the sulfided triazine material.

[0057] E: The obtained sulfide porphyrin covalent triazine material, sulfide solid electrolyte, and conductive carbon VGCF were mixed and ball-milled on a planetary ball mill at a mass ratio of 5:4:1 for 1-3 hours to obtain a composite positive electrode.

[0058] (2) Preparation of Ru-coordinated porphyrin-triazine all-solid-state batteries.

[0059] Apply composite positive electrodes to the assembly of all-solid-state batteries.

[0060] a. The positive electrode material, the conductive carbon material VGCF and the prepared sulfide solid electrolyte material are mixed in a mass ratio of 5:1:4, and the positive electrode active material powder is obtained after being evenly ground. The positive electrode active material powder is dispersed in a 5% polyvinylidene fluoride-N-methylpyrrolidone solution (4 mL), stirred evenly and then coated on an aluminum foil to obtain a positive electrode sheet.

[0061] b. Place the prepared sulfide solid electrolyte material in a sheet pressing mold and press to obtain the electrolyte sheet (thickness controlled at 100-500μm) used for assembling the battery, then place the positive electrode sheet on one side of the solid electrolyte sheet and press it. Finally, attach lithium foil to the other side of the solid electrolyte and press it into a sandwich structure all-solid-state battery.

[0062] Example 3

[0063] The difference between this embodiment and embodiment 1 is that:

[0064] Step B: adding zinc nitrate tetrahydrate to the reaction to prepare a Zn-coordinated porphyrin-triazine composite positive electrode material, and assembling an all-solid-state battery;

[0065] Step B is specifically as follows: 550 mg of porphyrin monomer, 30 mL of redistilled chloroform, 20 mL of saturated zinc nitrate tetrahydrate and 15 mL of methanol are reacted to obtain a metal porphyrin complex, and a pure sample of the metal porphyrin complex is obtained after purification by column chromatography.

[0066] Example 4

[0067] The difference between this embodiment and embodiment 1 is that:

[0068] In step B, nickel nitrate pentahydrate is added to the reaction to prepare a Ni-coordinated porphyrin-based triazine composite positive electrode material, and an all-solid-state battery is assembled.

[0069] Step B is specifically as follows: 550 mg of porphyrin monomer, 30 mL of redistilled chloroform, 20 mL of saturated nickel nitrate pentahydrate and 15 mL of methanol are reacted to obtain a metal porphyrin complex, and a pure sample of the metal porphyrin complex is obtained after purification by column chromatography.

[0070] Example 5

[0071] The difference between this embodiment and embodiment 1 is that:

[0072] In step B, copper nitrate hexahydrate is added to the reaction to prepare a Cu-coordinated porphyrin-based triazine composite positive electrode material, and an all-solid-state battery is assembled.

[0073] Step B is specifically as follows: 550 mg of porphyrin monomer, 30 mL of redistilled chloroform, saturated copper nitrate hexahydrate (20 mL), and 15 mL of methanol are reacted to obtain a metal porphyrin complex, and a pure sample of the metal porphyrin complex is obtained after purification by column chromatography.

[0074] Example 6

[0075] The difference between this embodiment and embodiment 1 is that:

[0076] In step B, platinum nitrate is added to the reaction to prepare a Pt-coordinated porphyrin-based triazine composite positive electrode material, and an all-solid-state battery is assembled.

[0077] Step B is specifically as follows: 550 mg of porphyrin monomer, 30 mL of redistilled chloroform, 20 mL of saturated platinum nitrate solution and 15 mL of methanol are reacted to obtain a metal porphyrin complex, and a pure sample of the metal porphyrin complex is obtained after purification by column chromatography.

[0078] Comparative Example 1

[0079] The specific steps of the preparation method of the full battery are as follows:

[0080] (1) Preparation of metal-free porphyrin-based triazine all-solid-state batteries

[0081] A: 500 mg of p-cyanobenzaldehyde, 400 mg of bispyrrole, 1 mL of boron trifluoride etherate (mass concentration 48%), and 500 mL of distilled chloroform were placed in a three-necked flask. The mixture in the flask was degassed with Ar gas for 20 minutes, reacted under inert gas for 2 hours, and then dichlorodicyanobenzoquinone (4.15 g) was added to quench the reaction. The product was then evaporated to remove the solvent and subjected to column chromatography to obtain a purple product, which was the porphyrin-based monomer.

[0082] B: 100 mg of the porphyrin-based monomer of step A and 1000 mg of anhydrous zinc chloride were placed in a quartz tube and ground and mixed evenly. The tube was sealed in vacuum and sintered at 350° C. for 40 h, and then purified to obtain a pure sample covalent triazine polymer;

[0083] C: 300 mg of sublimated sulfur and covalent triazine polymer were placed in a quartz tube at a mass ratio of 3:1 and sintered at 300°C for 3 h to obtain a sulfide triazine material;

[0084] D: The obtained sulfide porphyrin covalent triazine material, sulfide solid electrolyte, and conductive carbon VGCF were mixed and ball-milled on a planetary ball mill at a mass ratio of 5:4:1 for 1-3 hours to obtain a composite positive electrode.

[0085] E: Application of the composite positive electrode to the assembly of an all-solid-state battery (assembly process is the same as in Example 1)

[0086] Comparative Example 2

[0087] The difference between this comparative example and Example 1 is that in step C, the mass ratio of sublimated sulfur to covalent triazine polymer is 1:1.

[0088] Performance Testing

[0089] The capacity of the all-solid-state batteries prepared in Example 1 and Comparative Examples 1-2 was tested.

[0090] from Figure 1 It can be seen from the capacity performance diagram that the capacity of the porphyrin-based triazine positive electrode material without metal coordination (calculated based on the total mass of the positive electrode material) reaches 108mAh / g. However, the cycle stability is not good. The capacity of the porphyrin-based triazine positive electrode material with metal coordination (calculated based on the total mass of the positive electrode material) is roughly the same as the former, but the stability is greatly improved, indicating that doping metal has a beneficial effect on improving the stability of this type of battery.

[0091] from Figure 2 It can be seen from the capacity performance diagram that high sulfur content plays a great role in improving the performance of the whole battery, and both stability and capacity performance are greatly improved. Of course, this is the result of the joint promotion of high sulfur content and metal doping. In general, the all-solid-state battery with sulfide porphyrin-based covalent triazine as the positive electrode material prepared by the present invention has excellent energy density and cycle life, as well as good compatibility with sulfide solid electrolytes. It benefits from the formation of well-confined sulfur substances in the micropores, the bonding of sulfur to the framework, and the good electronic and framework ionic conductivity.

[0092] In summary, the present invention discloses a preparation method of a porphyrin-based covalent triazine and its application in lithium-ion batteries. The porphyrin-based covalent triazine framework material is prepared by the following method: (1) using bipyrrole and p-cyanobenzaldehyde to react to obtain a porphyrin-based monomer; (2) using the porphyrin-based monomer obtained in step (1) to mix with anhydrous zinc chloride in a vacuum quartz tube for sintering reaction and post-treatment to obtain a target porphyrin-based covalent triazine polymer; (3) after being mixed with elemental sulfur and vacuum sintered; (4) the obtained material is made into a composite positive electrode equipped with an all-solid-state battery. The porphyrin-based covalent triazine framework material prepared by the ion melting method of the present invention has a high specific surface area. When used as a cathode material for lithium-ion batteries, it has the advantages of high capacity and good rate performance, and has a good application prospect in new high-performance organic electrode materials.

[0093] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A sulfided porphyrin-based covalent triazine composite cathode material, characterized in that: The preparation method of the positive electrode material comprises the following steps: S1, reacting bispyrrole with p-cyanobenzaldehyde under the protection of an inert gas to obtain a porphyrin-based monomer; S2, combining the porphyrin-based monomer of step S1 with a metal element to form a metal porphyrin complex; the metal element includes one of Ni, Zn, Cu, Ru, Pt, and Co; S3, reacting the metal porphyrin complex of step S2 with zinc chloride to obtain a covalent triazine polymer; S4, sintering the covalent triazine polymer of step S3 with sublimated sulfur to obtain a sulfided porphyrin-based covalent triazine material; the mass ratio of the sublimated sulfur to the covalent triazine polymer is 1:1-3:1; S5. Mix the porphyrin sulfide covalent triazine material of step S4 with a sulfide solid electrolyte and conductive carbon and perform ball milling to obtain the porphyrin sulfide covalent triazine composite positive electrode material.

2. The composite positive electrode material according to claim 1, characterized in that Step S3 specifically comprises reacting the metal porphyrin complex of step S2 with anhydrous zinc chloride at 300-500° C. under vacuum conditions to obtain a crude covalent triazine polymer product, and purifying the covalent triazine polymer.

3. The composite positive electrode material according to claim 1, characterized in that: Step S4 specifically comprises sintering the covalent triazine polymer of step S3 with sublimated sulfur under vacuum conditions at 150-300° C. for 1-6 hours to obtain a sulfided porphyrin-based covalent triazine material.

4. The composite positive electrode material according to claim 1, characterized in that In step S5, the sulfide solid electrolyte includes Li 5.5 PS 4.5 Cl 1.5 、Li6PS5Cl、Li 10 GeP2S 12 , Li 9.5 4Si 1.74 P 1.44 S 11.7 Cl 0.3 , Li 10 SnP2S 12 One or more of the following.

5. The composite positive electrode material according to claim 1, characterized in that: In step S5, the conductive carbon includes one or more of conductive carbon black, carbon nanotubes, graphene, graphite sheets, and activated carbon fibers.

6. The composite positive electrode material according to claim 1, characterized in that: The structural formula of the covalent triazine polymer is as follows: Where: M is a metal element, Represents a repeating structural unit.

7. Use of the composite cathode material as described in any one of claims 1 to 6 in an all-solid-state battery.

8. An all-solid-state battery comprising the composite cathode material according to any one of claims 1 to 6.

9. The all-solid-state battery according to claim 8, characterized in that: The negative electrode active material of the all-solid-state battery includes a carbon series material, a Si-containing carbon series material or an olivine structure transition metal material; the carbon series material is artificial graphite, natural graphite, hard carbon or graphene, and the olivine structure transition metal material includes Li4Ti5O 12 、LiNbTi2O7.

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