Use of a p-type organic polymer in a fluoride ion battery

Abstract

This invention discloses the application of a p-type organic polymer in fluoride-ion batteries. The p-type organic polymer is polypyrrole, which serves as the positive electrode active material in the fluoride-ion battery, enabling the reversible insertion and extraction of fluoride ions through a reversible redox reaction. This invention constructs a complete fluoride-ion secondary battery system by using the p-type organic polymer polypyrrole as the positive electrode active material, together with a fluoride-ion electrolyte and a negative electrode. The reversible redox reaction of the p-type organic polymer polypyrrole to achieve the reversible insertion and extraction of fluoride ions (anions) significantly improves the structural collapse problem caused by inorganic electrode materials and enhances cycle stability.

Description

Technical Field

[0001] This invention relates to the field of fluorine-ion battery technology, and more specifically to the application of a p-type organic polymer in fluorine-ion batteries. Background Technology

[0002] Fluorine-ion batteries are a type of battery based on fluorine ions (F₂O₃). - This refers to a novel secondary battery system involving insertion / extraction or conversion reactions between the positive and negative electrodes. With the rapid development of portable electronic devices and electric vehicles, the energy density of existing lithium-ion batteries is gradually approaching its theoretical limit. Resources such as lithium and cobalt are scarce, and safety issues exist; therefore, there is an urgent need to develop new high-energy-density energy storage technologies.

[0003] Fluorine-ion batteries, thanks to the high electronegativity, low atomic weight, and small ionic radius of fluorine, can provide high energy density as a charge carrier—its theoretical volumetric energy density can reach 5000 Wh / L, far exceeding that of traditional lithium-ion batteries. Furthermore, fluorine is far more abundant in the Earth's crust than lithium, offering a resource security advantage; simultaneously, the negative electrode design fundamentally solves the dendrite growth problem, resulting in good safety and an operating temperature range from room temperature to 170 °C, adapting to various application scenarios. Based on these advantages, fluorine-ion batteries are considered one of the core candidate directions for next-generation energy storage technology.

[0004] However, the development of fluoride-ion batteries still faces many challenges, especially the development of cathode materials. Existing cathode materials mainly include conversion-type inorganic materials (such as metal fluorides CuF2, BiF3, FeF3, etc.) and intercalation-type inorganic materials (such as LaSrMnO4, La...). 1.2 Sr 1.8 Layered materials such as Mn3O7, La2NiO4, and La2CoO4 are used. However, conversion electrodes are usually accompanied by huge volume expansion, which leads to the destruction of the electrode structure, poor cycle stability, and slow reaction kinetics, limiting their practical application. Intercalation electrodes can avoid the volume expansion problem of conversion reactions, but have limited capacity, and fluoride ion intercalation may cause destruction of the layered structure.

[0005] Therefore, the development of new high-performance cathode materials is of great significance for promoting the development of fluoride-ion batteries. Summary of the Invention

[0006] This invention addresses the shortcomings of existing technologies by providing an application of p-type organic polymers in fluoride-ion batteries. By using p-type organic polymer polypyrrole as the positive electrode active material, a complete fluoride-ion secondary battery system is constructed together with fluoride-ion electrolyte and negative electrode. The p-type organic polymer polypyrrole achieves reversible insertion and extraction of fluoride ions (anions) through reversible redox reactions, effectively avoiding the structural collapse problem caused by inorganic conversion electrode materials and improving cycle stability.

[0007] To address the aforementioned technical problems, this invention provides an application of a p-type organic polymer in fluorine-ion batteries. The p-type organic polymer is polypyrrole, which serves as the positive electrode active material of fluorine-ion batteries and enables the reversible insertion and extraction of fluorine ions through a reversible redox reaction.

[0008] This invention utilizes the p-type organic polymer polypyrrole as a positive electrode active material in fluoride-ion batteries. Through electrochemical oxidation, it loses electrons, acquires a positive charge, and adsorbs / intercalates anions. Leveraging its intrinsic property of reversibly storing anions, it enables reversible intercalation and deintercalation of fluoride ions, thus functioning as a positive electrode active material in fluoride-ion batteries. This significantly avoids the structural collapse problems associated with inorganic conversion electrode materials and improves cycle stability. Specifically, polypyrrole possesses a highly conductive framework, structural adaptability to anion entry and exit, and rapid pseudocapacitive dynamics; the unique electron cloud density of the nitrogen atom in the pyrrole ring is closely related to that of fluoride ions (F... - ) Formation of specific ion-dipole interactions (N + -HF - ).

[0009] Furthermore, the microstructure of the positive electrode active material is nanotube-shaped or nanorod-shaped. Preferably, the particle size of the nanospheres is 50-500 nm, and the diameter of the nanotubes or nanorods is 50-500 nm with an aspect ratio of 5-50.

[0010] Furthermore, the positive electrode active material is prepared by a template method, specifically by mixing pyrrole monomer, template agent and oxidant in a solvent, carrying out a polymerization reaction and removing the template agent.

[0011] Furthermore, the oxidant is ferric chloride and / or ammonium persulfate.

[0012] Furthermore, the molar ratio of the template agent, pyrrole monomer and oxidant is (0.001-1):1:(0.5-3), and the polymerization temperature is 0-50℃; the template agent is methyl orange.

[0013] Furthermore, the fluorine-ion battery includes a positive electrode, a negative electrode, and an electrolyte, wherein the positive electrode includes the p-type organic polymer.

[0014] Furthermore, the electrolyte comprises a fluoride salt and an organic solvent; the fluoride salt is selected from one or more of cesium fluoride, tetramethylammonium fluoride, tetraethylammonium fluoride, tetrapropylammonium fluoride, tetrabutylammonium fluoride, benzyltrimethylammonium fluoride, potassium fluoride, sodium fluoride, and ammonium fluoride; the organic solvent is selected from one or more of ethylene glycol, glycerol, tetrahydrofuran, and bis(2,2,2-trifluoroethyl) ether.

[0015] Furthermore, the positive electrode is obtained by coating a positive electrode slurry onto a positive electrode current collector, the positive electrode slurry comprising the aforementioned positive electrode active material, conductive agent, binder, and dispersant. Preferably, the positive electrode current collector is selected from one or more of titanium foil, aluminum foil, stainless steel foil, carbon-coated aluminum foil, carbon paper, and carbon cloth.

[0016] Furthermore, the mass ratio of the positive electrode active material, conductive agent, and binder is (6-8):(1-3):(1-3).

[0017] Furthermore, the active material of the negative electrode includes one or more of lead, lead fluoride, lead-carbon composite, and a composite of lead fluoride and carbon.

[0018] The beneficial effects of this invention are:

[0019] This invention applies a polypyrrole p-type organic polymer electrode material to a fluoride-ion battery. When the polymer loses electrons (is oxidized) and generates holes (p-doping), fluoride ions from the surrounding environment (electrolyte) are inserted into the polymer bulk phase to maintain electroneutrality. When the polymer is reduced (discharged), the polymer backbone regains electroneutrality, and the fluoride ions diffuse back into the electrolyte, thereby realizing the charge-discharge process and achieving the desired fluoride ion (F) doping effect. - This provides a new direction for cathode materials of fluoride-ion batteries by enabling reversible storage and avoiding the problems of unstable structure of conversion inorganic materials and low capacity of intercalated inorganic materials.

[0020] This invention applies molecularly modified p-type organic polymers to the cathode of fluoride-ion batteries. Specifically designed to address the intrinsic characteristics of fluoride ions (smallest radius 1.33 Å, strongest electronegativity 4.0, and highest charge-to-mass ratio), the invention further enhances the electrochemical performance of organic polymer electrode materials in fluoride-ion batteries. By using a template method to prepare polypyrrole nanospheres or nanorods, the invention effectively overcomes the common problem of slow reaction kinetics in fluoride-ion batteries. Compared to unmodified polymer electrode materials, the specific capacity and other electrochemical properties of fluoride-ion batteries are further improved, opening a new path for developing high-energy-density, long-cycle-life room-temperature fluoride-ion batteries.

[0021] This invention enables the selection of fluoride salt and anode material systems that match p-type organic polymer cathode materials, forming a complete fluoride-ion secondary battery technology solution. It features simple operation, low cost, and safety and stability, and has good prospects for industrial application. Attached Figure Description

[0022] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 These are microscopic morphology images of polypyrrole prepared in Example 1 and Comparative Example 1 of this invention;

[0024] Figure 2 This is a cycle performance diagram of the fluorine-ion battery obtained in Example 1 of the present invention;

[0025] Figure 3 This is a cycle performance diagram of the fluorine-ion battery obtained in Comparative Example 1 of the present invention;

[0026] Figure 4 This is a cycle performance diagram of the fluorine-ion battery obtained in Comparative Example 2 of the present invention;

[0027] Figure 5 This is a cycle performance diagram of the fluorine-ion battery obtained in Comparative Example 3 of the present invention. Detailed Implementation

[0028] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] This embodiment relates to the application of a p-type organic polymer in a fluoride-ion battery. The p-type organic polymer is polypyrrole, which serves as the positive electrode active material in the fluoride-ion battery. Through a reversible redox reaction, it enables the reversible insertion and extraction of fluoride ions. This embodiment applies the p-type organic polymer polypyrrole as the positive electrode active material in a fluoride-ion battery. Through an electrochemical oxidation process, it loses electrons, acquires a positive charge, and adsorbs / inserts anions. Utilizing its intrinsic characteristic of reversibly storing anions, it can achieve the reversible insertion and extraction of fluoride ions, thus functioning as the positive electrode active material in the fluoride-ion battery. This effectively avoids the structural collapse problem caused by inorganic conversion electrode materials and improves cycle stability.

[0030] In a preferred embodiment, the microstructure of the positive electrode active material is nanotube-shaped or nanorod-shaped. Preferably, the particle size of the nanospheres is 50-500 nm, and the diameter of the nanotubes or nanorods is 50-500 nm with an aspect ratio of 5-50.

[0031] In a preferred embodiment, the positive electrode active material is prepared by a template method, specifically by mixing pyrrole monomer, template agent, and oxidant in a solvent, carrying out a polymerization reaction, and then removing the template agent. The oxidant is ferric chloride and / or ammonium persulfate; the molar ratio of the template agent, pyrrole monomer, and oxidant is (0.001-1):1:(0.5-3), and the polymerization temperature is 0-50℃; the template agent is methyl orange.

[0032] In a preferred embodiment, the fluorine-ion battery includes a positive electrode, a negative electrode, and an electrolyte, wherein the positive electrode comprises the aforementioned p-type organic polymer. The electrolyte comprises a fluoride salt and an organic solvent; the fluoride salt is selected from one or more of cesium fluoride, tetramethylammonium fluoride, tetraethylammonium fluoride, tetrapropylammonium fluoride, tetrabutylammonium fluoride, benzyltrimethylammonium fluoride, potassium fluoride, sodium fluoride, and ammonium fluoride; the organic solvent is selected from one or more of ethylene glycol, glycerol, tetrahydrofuran, and bis(2,2,2-trifluoroethyl) ether.

[0033] In a preferred embodiment, the positive electrode is obtained by coating a positive electrode slurry onto a positive electrode current collector. The positive electrode slurry includes the aforementioned positive electrode active material, conductive agent, binder, and dispersant. Preferably, the positive electrode current collector is selected from one or more of titanium foil, aluminum foil, stainless steel foil, carbon-coated aluminum foil, carbon paper, and carbon cloth. The mass ratio of the positive electrode active material, conductive agent, and binder is (6-8):(1-3):(1-3).

[0034] In a preferred embodiment, the active material of the negative electrode includes one or more of lead, lead fluoride, lead-carbon composite, and a composite of lead fluoride and carbon.

[0035] Example 1

[0036] This embodiment relates to a method for preparing a fluorine-ion secondary battery using spherical polypyrrole as the positive electrode active material, comprising the following steps:

[0037] (1) Preparation of rod-shaped polypyrrole: 0.049 g of methyl orange was added to 25 ml of deionized water and stirred until completely dissolved. Then, 0.1 ml of pyrrole monomer was added dropwise at 5°C. 0.487 g of anhydrous ferric chloride was dissolved in 5 ml of deionized water and slowly added dropwise to the above solution. After 12 h of reaction, a black powder was obtained by filtration. Then, it was washed with deionized water to remove unreacted monomers, excess oxidants and oligomers. The washed product was then placed in an oven (60°C) and dried for 12 h to obtain rod-shaped polypyrrole, denoted as PPy-NT.

[0038] (2) Preparation of positive electrode: Rod-shaped polypyrrole, Ketjen black (conductive agent), and polyvinylidene fluoride (binder) were mixed at a mass ratio of 7:2:1. N-methylpyrrolidone (NMP) was added and ground evenly to form a slurry with a spherical polypyrrole concentration of 20 mg / mL. The slurry was coated on titanium foil, vacuum dried at 80 °C for 12 h, and punched into round sheets with a diameter of 12 mm to obtain the positive electrode; wherein the active material loading was approximately 0.6 mg / cm³. 2 .

[0039] (3) Preparation of fluoride ion electrolyte

[0040] Tetramethylammonium fluoride and ethylene glycol were stirred at a molar ratio of 1:1 in an argon-filled glove box at room temperature for 6 h until completely dissolved to obtain a fluoride ion electrolyte.

[0041] (4) Battery assembly

[0042] Assemble CR2032 coin cells in an argon-filled glove box: use the positive electrode prepared in step (2) as the working electrode, and mix Pb:PbF2:Kejtien Black (conductive agent):polyvinylidene fluoride (binder) in a mass ratio of 4:4:1:1. Use NMP as a solvent to form a slurry, which is then coated onto titanium foil as the negative electrode material. Use glass fiber as the separator, and use the fluoride ion electrolyte prepared in step (3) as the electrolyte. After the assembled battery has been left to stand for 8 hours, perform electrochemical tests.

[0043] Comparative Example 1

[0044] The difference between this comparative example and Example 1 is that no template agent is added in step (1), and polypyrrole powder, denoted as PPy, is prepared as the positive electrode active material; other steps and parameters remain unchanged.

[0045] Comparative Example 2

[0046] The difference between this comparative example and Comparative Example 1 is that step (1) is replaced with the preparation of polyaniline, and step (2) is replaced with polypyrrole with an equal mass of polyaniline, while other steps and parameters remain unchanged;

[0047] The preparation method of polyaniline is as follows: 0.93 g of aniline monomer solution is added to a prepared hydrochloric acid solution (1 mol / L) and placed in a two-necked flask. Then, 2.28 g of ammonium persulfate solution is slowly added dropwise to the flask. Under nitrogen protection and stirring, the reaction system is placed at a predetermined temperature (ice bath) to ensure complete polymerization. The mixture is then filtered under reduced pressure and washed several times with anhydrous ethanol and deionized water until the filtrate is colorless and neutral. The filter cake is vacuum dried at 65 °C for 12 h and then ground into powder to obtain polyaniline powder, denoted as PANI.

[0048] Comparative Example 3

[0049] The difference between this comparative example and comparative example 2 is that step (1) is replaced with the preparation of cross-linked aniline, and step (2) is replaced with an equal mass of cross-linked aniline, while other steps and parameters remain unchanged;

[0050] The preparation method of cross-linked aniline is as follows: 0.921 ml of phytic acid was added to 2 ml of deionized water and stirred for 2 min. Then, 0.458 ml of aniline (ANI) was added, and the mixture was continuously stirred until completely dissolved. 0.06125 g of triphenylamine (TPA) was added to the mixed solution at a triphenylamine:aniline molar ratio of 0.05:1 and stirred until completely dissolved. The sample was then placed in an environment of 2-8 ℃ and refrigerated for 10 minutes for later use. Subsequently, 2.86 g of ammonium persulfate was dissolved in 10 ml of deionized water for later use. Then, 0.845 ml of the ammonium persulfate solution was added to the refrigerated aniline / triphenylamine mixed solution, mixed thoroughly, and transferred to a nitrogen-protected environment of 2-8 ℃ for polymerization for 12 h. The mixture was removed and washed with deionized water and alcohol, and then centrifuged. Finally, the sample was placed in a vacuum oven set to 60 ℃ to obtain cross-linked aniline powder, denoted as PANI-TPA.

[0051] Figure 1 shows the morphology of polypyrrole PPy obtained in Comparative Example 1 and nanorod polypyrrole PPy-NT obtained in Example 1. It can be seen that the polypyrrole obtained in Comparative Example 1 exhibits a spherical particle microstructure with a particle size of approximately 50-500 nm; while the nanorod polypyrrole prepared using the template exhibits a distinct rod-shaped microstructure with a diameter of approximately 50-500 nm and an aspect ratio of 5-50.

[0052] The performance of the fluoride-ion batteries obtained in Example 1 and Comparative Examples 1-3 was tested:

[0053] Constant current charge-discharge test: conducted on the Newway multi-channel battery testing system, with a voltage window of 0-0.8 V vs. Pb / PbF2 and a current density of 20 mA / g. The initial discharge capacity and capacity retention after 100 cycles were tested.

[0054] Cyclic voltammetry tests were performed on an electrochemical workstation (CHI660E) at a scan rate of 0.2–1.0 mV / s and a voltage window of 0–1.0 V.

[0055] Figure 2 The diagram shows the cycling performance of the fluorine-ion battery obtained in Example 1. Using polypyrrole nanorods (PPy-NT) as the positive electrode material, its initial discharge capacity was increased to 113 mAh / g, and the capacity retention rate was 61% after 100 cycles.

[0056] Figure 3The diagram shows the cycling performance of the fluorine-ion battery obtained in Comparative Example 1. Using conventional polypyrrole powder as the positive electrode material, its initial discharge capacity was only 82 mAh / g, and the capacity retention rate after 100 cycles was 54%. Compared with the fluorine-ion battery obtained in Example 1, the capacity and stability decreased to a certain extent. The results indicate that the electrochemical performance of the fluorine-ion battery with the molecularly modified polymer electrode material was significantly improved.

[0057] Figure 4 The graph shows the cycle performance of the fluorine-ion battery obtained in Comparative Example 2. Using conventional polyaniline (PANI) as the positive electrode material, its initial discharge capacity is only 33 mAh / g, and the capacity retention rate after 100 cycles is 34%. It can be seen that, although it is a p-type polymer, the fluorine-ion battery obtained by using polyaniline as the positive electrode material has poor performance.

[0058] Figure 5 The circuit performance diagram of the fluorine-ion battery obtained in Comparative Example 3 is shown. Triphenylamine cross-linked polyaniline (PANI-TPA) was used as the positive electrode material. Its initial discharge capacity was increased to 78 mAh / g, and the capacity retention rate after 100 cycles was 51%. Compared with polyaniline, although the capacity and stability were improved to some extent, it was far inferior to the fluorine-ion battery obtained by the rod-shaped polypyrrole positive electrode material in Example 1.

[0059] In summary, this invention applies polypyrrole p-type organic polymer electrode materials to fluoride-ion batteries, achieving the goal of fluoride ion (F... - This technology enables reversible storage of fluoride ions and avoids the structural instability of conversion-type inorganic materials and the low capacity of intercalated inorganic materials, providing a new direction for cathode materials in fluoride-ion batteries. Specifically designed to address the intrinsic characteristics of fluoride ions (minimum radius 1.33 Å, strongest electronegativity 4.0, and highest charge-to-mass ratio), polypyrrole is used to prepare nanospheres or nanorods, effectively overcoming the common problem of slow reaction kinetics in fluoride-ion batteries. Compared to unmodified polymer electrode materials, the electrochemical performance, such as specific capacity, of fluoride-ion batteries is further improved, opening a new path for developing high-energy-density, long-cycle-life room-temperature fluoride-ion batteries.

[0060] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. Use of a p-type organic polymer in a fluoride ion battery, characterized in that, The p-type organic polymer is polypyrrole, which serves as the positive electrode active material for fluoride-ion batteries and enables the reversible insertion and extraction of fluoride ions through a reversible redox reaction. The microstructure of the positive electrode active material is nanotube-shaped or nanorod-shaped, with a diameter of 50-500 nm and an aspect ratio of 5-50.

2. The application of the p-type organic polymer as described in claim 1 in fluoride-ion batteries, characterized in that, The positive electrode active material is obtained by mixing pyrrole monomer, template agent and oxidant in a solvent, carrying out a polymerization reaction and removing the template agent.

3. The application of the p-type organic polymer as described in claim 2 in fluoride-ion batteries, characterized in that, The molar ratio of the template agent, pyrrole monomer and oxidant is (0.001-1):1:(0.5-3), and the polymerization temperature is 0-50℃.

4. The application of the p-type organic polymer as described in claim 2 in fluorine-ion batteries, characterized in that, The oxidant is ferric chloride and / or ammonium persulfate.

5. The application of the p-type organic polymer as described in claim 1 in fluoride-ion batteries, characterized in that, The fluorine-ion battery includes a positive electrode, a negative electrode, and an electrolyte, wherein the positive electrode comprises the p-type organic polymer.

6. The application of the p-type organic polymer as described in claim 5 in fluorine-ion batteries, characterized in that, The electrolyte comprises a fluoride salt and an organic solvent; the fluoride salt is selected from one or more of cesium fluoride, tetramethylammonium fluoride, tetraethylammonium fluoride, tetrapropylammonium fluoride, tetrabutylammonium fluoride, benzyltrimethylammonium fluoride, potassium fluoride, sodium fluoride, and ammonium fluoride.

7. The application of the p-type organic polymer as described in claim 5 in fluoride-ion batteries, characterized in that, The positive electrode is obtained by coating a positive electrode slurry onto a positive electrode current collector. The positive electrode slurry includes the aforementioned positive electrode active material, conductive agent, binder, and dispersant.

8. The application of the p-type organic polymer as described in claim 7 in fluorine-ion batteries, characterized in that, The mass ratio of the positive electrode active material, conductive agent, and binder is (6-8):(1-3):(1-3).

9. The application of the p-type organic polymer as described in claim 5 in fluorine-ion batteries, characterized in that, The active material of the negative electrode includes one or more of lead, lead fluoride, lead-carbon composite, and lead fluoride-carbon composite.

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