Composite electrode material and preparation method and application thereof

Abstract

The application relates to the technical field of electrode materials, and particularly discloses a composite electrode material, a preparation method and application thereof. The composite electrode material is designed by combining an inner rigid high-conductive framework with an outer porous active coating layer, structural and electrochemical synergistic effects among components are fully exerted, the diffusion path of electrolyte ions is effectively shortened, the finally-prepared composite electrode material can realize high specific capacitance output, and excellent rate response and long-life cycle stability are exhibited. The composite electrode material can be used in various energy storage devices such as symmetric supercapacitors and hybrid supercapacitors, and is suitable for scenes with strict requirements on energy density, power density and cycle life such as hybrid electric vehicles, pure electric vehicles, aerospace, smart grids and portable electronic devices.

Description

Technical Field

[0001] This invention relates to the field of electrode materials technology, specifically to a composite electrode material, its preparation method, and its application. Background Technology

[0002] Supercapacitors, also known as electrochemical capacitors, are a novel energy storage device that bridges the gap between traditional physical capacitors and rechargeable batteries. They combine the advantages of high power density and rapid charging / discharging of traditional capacitors with the relatively high energy density of rechargeable batteries. Furthermore, supercapacitors exhibit exceptionally long cycle life, excellent low-temperature performance, high safety, and environmental friendliness. Therefore, supercapacitors demonstrate enormous application potential and a broad market prospect in numerous cutting-edge and civilian fields, including start-stop systems and energy recovery in new energy vehicles, backup power supplies for portable electronic products, power compensation in smart grids, and rail transportation. They are currently one of the core research hotspots in the field of new energy materials and devices.

[0003] Despite the numerous advantages of supercapacitors, their relatively low energy density remains a core bottleneck restricting their wider application. Currently, commercially available electrode materials are primarily carbon-based, such as activated carbon. While these materials possess good conductivity and excellent cycle stability, their theoretical specific capacitance is low, making it difficult to meet the demands of high energy density. On the other hand, pseudocapacitive materials, represented by transition metal oxides, sulfides, and conductive polymers, generally suffer from low intrinsic conductivity and sluggish ion transport kinetics. More critically, during long-term charge-discharge cycles, these materials often undergo dramatic volume expansion and severe structural pulverization, leading to enormous internal stress within the electrode and subsequent shedding of active material, resulting in extremely poor cycle life and rate performance.

[0004] Therefore, developing novel composite electrode materials that combine high specific capacitance and long-term cycling stability has become a pressing technical challenge in the field of supercapacitor technology. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a composite electrode material, its preparation method and application.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing a composite electrode material includes the following steps: S1. Preparation of titanium dioxide / activated carbon composite materials Titanium source, citric acid and activated carbon were added to water and ultrasonically dispersed evenly. Then, the mixture was transferred to a hydrothermal reactor for hydrothermal reaction. After the reaction was completed, the mixture was washed and dried to obtain a titanium dioxide / activated carbon composite material.

[0007] In this step, the mass ratio of titanium source, citric acid and activated carbon is 1-3:2-4:5-10.

[0008] In this step, the titanium source is selected from tetrabutyl titanate or tetraethyl titanate.

[0009] In this step, the temperature of the hydrothermal reaction is 150-180℃, for example, 150℃, 160℃, 170℃, or 180℃ can be selected; the time of the hydrothermal reaction is 6-12h, for example, 6h, 7h, 8h, 9h, 10h, 11h, or 12h can be selected, but it is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0010] In this step, titanium dioxide particles are attached to the surface and pore structure of activated carbon using a hydrothermal method to obtain a titanium dioxide / activated carbon composite material.

[0011] S2. Preparation of titanium nitride / activated carbon composite materials The titanium dioxide / activated carbon composite material was calcined in an ammonia atmosphere and then cooled to room temperature to obtain the titanium nitride / activated carbon composite material.

[0012] In this step, the calcination temperature is 700-900℃, for example, 700℃, 720℃, 750℃, 780℃, 800℃, 820℃, 850℃, 880℃, or 900℃ can be selected; the calcination time is 1-2h, for example, 1h, 1.5h, or 2h can be selected, but it is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0013] Although titanium dioxide has a certain degree of structural stability, its intrinsic electronic conductivity is extremely low. In this step, titanium dioxide is converted into titanium nitride by calcination in an ammonia atmosphere. Titanium nitride and activated carbon together construct a three-dimensional network framework with both high conductivity and high mechanical strength. This rigid framework can not only provide a fast electron transport channel in the subsequent charge and discharge process, but also effectively resist the mechanical stress brought about by charge and discharge due to the excellent mechanical structure of titanium nitride, thereby improving the rate performance and long-term cycle stability of the electrode material.

[0014] S3. Preparation of composite precursor materials Nickel and manganese salts were dissolved in anhydrous methanol, and then titanium nitride / activated carbon composite material was added and dispersed evenly. 2-methylimidazole solution was added and the mixture was stirred to react. Subsequently, the mixture was aged, centrifuged, washed, and dried to obtain the composite precursor material.

[0015] In this step, the ratio of nickel salt, manganese salt, titanium nitride / activated carbon composite material and 2-methylimidazole is 1-2 mmol: 1-2 mmol: 0.1-0.2 g: 8-16 mmol.

[0016] In this step, the nickel salt is selected from nickel acetate or nickel nitrate.

[0017] In this step, the manganese salt is selected from manganese acetate.

[0018] In this step, the solvent in the 2-methylimidazole solution is anhydrous methanol.

[0019] In this step, a nickel-manganese metal-organic framework layer is grown in situ on the surface of a titanium nitride / activated carbon framework to obtain a composite precursor material.

[0020] S4. Preparation of composite electrode materials The composite precursor material is placed in a tube furnace and carbonized under an argon atmosphere to obtain the composite electrode material.

[0021] In this step, the carbonization reaction temperature is 750-850℃, for example, 750℃, 760℃, 770℃, 780℃, 790℃, 800℃, 810℃, 820℃, 830℃, 840℃, or 850℃ can be selected; the carbonization reaction time is 2-4 hours, for example, 2 hours, 2.5 hours, 3 hours, 3.5 hours, or 4 hours can be selected, but it is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0022] In this step, the composite precursor material is carbonized at high temperature under an argon atmosphere to obtain the final composite electrode material. During the carbonization process, the 2-methylimidazolium ligand in the MOF undergoes pyrolysis, transforming into a nitrogen-doped porous carbon structure. Simultaneously, nickel and manganese are doped into the porous carbon structure. The introduction of nickel provides abundant redox reaction sites, while the introduction of manganese modulates the local electronic structure of the system, further enhancing electrochemical activity. Furthermore, the porous carbon structure acts as a buffer matrix, effectively absorbing and accommodating the volume expansion and structural stress generated by the highly active nickel-manganese particles during long-cycle charge-discharge, preventing the active material from pulverizing and flaking off.

[0023] The present invention provides a composite electrode material prepared by the above preparation method.

[0024] The present invention also provides the application of the above-mentioned composite electrode material in the preparation of supercapacitor electrode materials.

[0025] Compared with the prior art, the present invention has the following beneficial effects: (1) The composite electrode material provided by the present invention fully utilizes the structural and electrochemical synergistic effect between the components by combining the inner rigid high conductivity skeleton with the outer porous active coating layer, effectively shortening the diffusion path of electrolyte ions, so that the final composite electrode material can achieve high specific capacitance output while exhibiting excellent rate response and long life cycle stability.

[0026] (2) Although titanium dioxide has a certain structural stability, its intrinsic electronic conductivity is extremely low. In this invention, titanium dioxide is converted into titanium nitride by calcination in an ammonia atmosphere. Titanium nitride and activated carbon together construct a three-dimensional network skeleton with both high conductivity and high mechanical strength. This rigid skeleton can not only provide a fast electron transport channel in the subsequent charging and discharging process, but also effectively resist the mechanical stress brought by charging and discharging due to the excellent mechanical structure of titanium nitride, thereby improving the rate performance and long-term cycle stability of the electrode material.

[0027] (3) The composite electrode material provided by the present invention can be used in various energy storage devices such as symmetrical supercapacitors and hybrid supercapacitors, and is suitable for scenarios with stringent requirements for energy density, power density and cycle life, such as hybrid electric vehicles, pure electric vehicles, aerospace, smart grids, and portable electronic devices. Detailed Implementation

[0028] The present invention will be further described in detail below through specific preferred embodiments, but the present invention is not limited to the following embodiments.

[0029] It should be noted that, unless otherwise specified, all chemical reagents involved in this invention were purchased through commercial channels.

[0030] Example 1 A method for preparing a composite electrode material includes the following steps: S1. Add 1g tetrabutyl titanate, 2g citric acid and 5g activated carbon to 150mL water, disperse evenly by ultrasonication, and then transfer to a hydrothermal reactor for hydrothermal reaction. The hydrothermal reaction temperature is 150℃ and the hydrothermal reaction time is 12h. After the reaction is completed, wash and dry to obtain titanium dioxide / activated carbon composite material. S2. 5g of titanium dioxide / activated carbon composite material was calcined in an ammonia atmosphere at a temperature of 900℃ for 1h, and then cooled to room temperature to obtain titanium nitride / activated carbon composite material. S3. Dissolve 0.249 g nickel acetate tetrahydrate and 0.245 g manganese acetate tetrahydrate in 20 mL anhydrous methanol, then add 0.1 g titanium nitride / activated carbon composite material, disperse evenly, add 20 mL of 0.4 mol / L 2-methylimidazole solution, stir and react at room temperature for 1 h, age for 24 h, centrifuge to collect the precipitate, wash with anhydrous methanol and deionized water alternately 4 times, and vacuum dry at 60 °C for 8 h to obtain the composite precursor material; S4. Place the composite precursor material in a tube furnace and carry out a carbonization reaction under an argon atmosphere. The carbonization reaction temperature is 800℃ and the carbonization reaction time is 3h, thus obtaining the composite electrode material.

[0031] Example 2 A method for preparing a composite electrode material includes the following steps: S1. Add 3g tetrabutyl titanate, 4g citric acid and 10g activated carbon to 150mL of water, disperse evenly by ultrasonication, and then transfer to a hydrothermal reactor for hydrothermal reaction. The hydrothermal reaction temperature is 180℃ and the hydrothermal reaction time is 6h. After the reaction is completed, wash and dry to obtain titanium dioxide / activated carbon composite material. S2. 5g of titanium dioxide / activated carbon composite material was calcined in an ammonia atmosphere at a temperature of 900℃ for 1h, and then cooled to room temperature to obtain titanium nitride / activated carbon composite material. S3. Dissolve 0.249 g nickel acetate tetrahydrate and 0.245 g manganese acetate tetrahydrate in 20 mL anhydrous methanol, then add 0.15 g titanium nitride / activated carbon composite material, disperse evenly, add 20 mL of 0.4 mol / L 2-methylimidazole solution, stir and react at room temperature for 1 h, age for 24 h, centrifuge to collect the precipitate, wash with anhydrous methanol and deionized water alternately 4 times, and vacuum dry at 60 °C for 8 h to obtain the composite precursor material; S4. Place the composite precursor material in a tube furnace and carry out a carbonization reaction under an argon atmosphere. The carbonization reaction temperature is 800℃ and the carbonization reaction time is 3h, thus obtaining the composite electrode material.

[0032] Example 3 A method for preparing a composite electrode material includes the following steps: S1. Add 2g tetrabutyl titanate, 3g citric acid and 8g activated carbon to 150mL water, disperse evenly by ultrasonication, and then transfer to a hydrothermal reactor for hydrothermal reaction. The hydrothermal reaction temperature is 180℃ and the hydrothermal reaction time is 6h. After the reaction is completed, wash and dry to obtain titanium dioxide / activated carbon composite material. S2. 5g of titanium dioxide / activated carbon composite material was calcined in an ammonia atmosphere at a temperature of 800℃ for 1.5h, and then cooled to room temperature to obtain titanium nitride / activated carbon composite material. S3. Dissolve 0.249 g nickel acetate tetrahydrate and 0.245 g manganese acetate tetrahydrate in 20 mL anhydrous methanol, then add 0.2 g titanium nitride / activated carbon composite material, disperse evenly, add 20 mL of 0.4 mol / L 2-methylimidazole solution, stir and react at room temperature for 1 h, age for 24 h, centrifuge to collect the precipitate, wash with anhydrous methanol and deionized water alternately 4 times, and vacuum dry at 60 °C for 8 h to obtain the composite precursor material; S4. Place the composite precursor material in a tube furnace and carry out a carbonization reaction under an argon atmosphere. The carbonization reaction temperature is 800℃ and the carbonization reaction time is 3h, thus obtaining the composite electrode material.

[0033] Comparative Example 1 A method for preparing a composite electrode material includes the following steps: S1. Dissolve 0.249 g nickel acetate tetrahydrate and 0.245 g manganese acetate tetrahydrate in 20 mL anhydrous methanol, then add 0.1 g activated carbon and disperse evenly. Add 20 mL of 0.4 mol / L 2-methylimidazole solution, stir and react at room temperature for 1 h, age for 24 h, centrifuge to collect the precipitate, wash with anhydrous methanol and deionized water alternately 4 times, and vacuum dry at 60 °C for 8 h to obtain the composite precursor material. S2. The composite precursor material is placed in a tube furnace and carbonized under an argon atmosphere. The carbonization temperature is 800℃ and the carbonization time is 3h, thus obtaining the composite electrode material.

[0034] Compared to Example 1, no loading treatment was performed on the activated carbon in Comparative Example 1.

[0035] Comparative Example 2 A method for preparing a composite electrode material includes the following steps: S1. Add 1g tetrabutyl titanate, 2g citric acid and 5g activated carbon to 150mL water, disperse evenly by ultrasonication, and then transfer to a hydrothermal reactor for hydrothermal reaction. The hydrothermal reaction temperature is 150℃ and the hydrothermal reaction time is 12h. After the reaction is completed, wash and dry to obtain titanium dioxide / activated carbon composite material. S2. Dissolve 0.249 g of nickel acetate tetrahydrate and 0.245 g of manganese acetate tetrahydrate in 20 mL of anhydrous methanol, then add 0.1 g of titanium dioxide / activated carbon composite material and disperse evenly. Add 20 mL of 0.4 mol / L 2-methylimidazole solution, stir and react at room temperature for 1 h, age for 24 h, centrifuge to collect the precipitate, wash with anhydrous methanol and deionized water alternately 4 times, and vacuum dry at 60 °C for 8 h to obtain the composite precursor material. S3. Place the composite precursor material in a tube furnace and carry out a carbonization reaction under an argon atmosphere. The carbonization reaction temperature is 800℃ and the carbonization reaction time is 3h, thus obtaining the composite electrode material.

[0036] Compared to Example 1, Comparative Example 2 involves loading titanium dioxide onto activated carbon.

[0037] Comparative Example 3 A method for preparing a composite electrode material includes the following steps: S1. Add 1g tetrabutyl titanate, 2g citric acid and 5g activated carbon to 150mL water, disperse evenly by ultrasonication, and then transfer to a hydrothermal reactor for hydrothermal reaction. The hydrothermal reaction temperature is 150℃ and the hydrothermal reaction time is 12h. After the reaction is completed, wash and dry to obtain titanium dioxide / activated carbon composite material. S2. 5g of titanium dioxide / activated carbon composite material was calcined in an ammonia atmosphere at a temperature of 900℃ for 1h, and then cooled to room temperature to obtain titanium nitride / activated carbon composite material. S3. Dissolve 0.249 g of nickel acetate tetrahydrate in 20 mL of anhydrous methanol, then add 0.1 g of titanium nitride / activated carbon composite material, disperse evenly, add 20 mL of 0.4 mol / L 2-methylimidazole solution, stir and react at room temperature for 1 h, age for 24 h, centrifuge to collect the precipitate, wash with anhydrous methanol and deionized water alternately 4 times, and vacuum dry at 60 °C for 8 h to obtain the composite precursor material; S4. Place the composite precursor material in a tube furnace and carry out a carbonization reaction under an argon atmosphere. The carbonization reaction temperature is 800℃ and the carbonization reaction time is 3h, thus obtaining the composite electrode material.

[0038] Compared to Example 1, Comparative Example 3 did not have manganese loaded on the composite electrode material.

[0039] The composite electrode materials prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance tests, as detailed below: Composite electrode material, carbon black, and polyvinylidene fluoride were mixed at a mass ratio of 85:8:7. A mixed solvent of anhydrous ethanol and N-methylpyrrolidone (volume ratio 3:1) was added and ground into a uniform slurry. This slurry was then coated onto the surface of pretreated nickel foam (1 cm × 2 cm, after soaking in 1 mol / L HCl for 30 min to remove the oxide layer, washing and drying with water) (coating amount 1 mg / cm²). After vacuum drying at 80 °C for 12 h, the electrode was pressed at 10 MPa for 40 s to obtain the working electrode. Then, two identical working electrodes were used as the positive and negative electrodes, with a polypropylene membrane (Celgard 3501) as the separator and 6 mol / L KOH electrolyte. The electrodes were encapsulated in an argon glove box using a CR2032 button cell battery case. The electrochemical performance test results are shown in Table 1.

[0040] Table 1. Electrochemical performance test results for different groups

[0041] Finally, it should be noted that the above embodiments do not limit the present invention in any way. Those skilled in the art can make modifications and improvements based on the present invention. Therefore, any modifications or improvements made without departing from the spirit of the present invention are within the scope of protection claimed by the present invention.

Claims

1. A method for preparing a composite electrode material, characterized in that, Includes the following steps: S1. Add titanium source, citric acid and activated carbon to water, disperse evenly by ultrasonication, and then transfer to a hydrothermal reactor for hydrothermal reaction. After the reaction is completed, wash and dry to obtain titanium dioxide / activated carbon composite material. S2. The titanium dioxide / activated carbon composite material was calcined in an ammonia atmosphere and then cooled to room temperature to obtain the titanium nitride / activated carbon composite material. S3. Dissolve nickel salt and manganese salt in anhydrous methanol, then add titanium nitride / activated carbon composite material, disperse evenly, add 2-methylimidazole solution, stir to react, and then age, centrifuge, wash and dry to obtain composite precursor material; S4. Place the composite precursor material in a tube furnace and carry out a carbonization reaction under an argon atmosphere to obtain the composite electrode material.

2. The preparation method according to claim 1, characterized in that, In step S1, the mass ratio of titanium source, citric acid and activated carbon is 1-3:2-4:5-10.

3. The preparation method according to claim 1, characterized in that, In step S1, the hydrothermal reaction temperature is 150-180℃, and the hydrothermal reaction time is 6-12h.

4. The preparation method according to claim 1, characterized in that, In step S2, the calcination temperature is 700-900℃ and the calcination time is 1-2h.

5. The preparation method according to claim 1, characterized in that, In step S3, the ratio of nickel salt, manganese salt, titanium nitride / activated carbon composite material and 2-methylimidazole is 1-2 mmol: 1-2 mmol: 0.1-0.2 g: 8-16 mmol.

6. The preparation method according to claim 1, characterized in that, In step S3, the nickel salt is selected from nickel acetate or nickel nitrate; the manganese salt is selected from manganese acetate.

7. The preparation method according to claim 1, characterized in that, In step S4, the carbonization reaction temperature is 750-850℃, and the carbonization reaction time is 2-4 hours.

8. The composite electrode material prepared by the preparation method according to any one of claims 1-7.

9. The application of the composite electrode material as described in claim 8 in the preparation of supercapacitor electrode materials.

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