A highly conductive polymer electrode material, its preparation method and application

Abstract

The present invention belongs to the field of preparation of organic battery materials. Specifically, the present invention discloses a highly conductive polymer electrode material, a preparation method thereof, and an application thereof. Through molecular structure design, the highly conductive polymer electrode material of the present invention prepares a polymer by a method combining solvothermal treatment and heat treatment, increasing the number of conjugated rings in the polymer structure, greatly improving the conjugation performance of the polymer, making the electron circulation and conductivity better. The introduction of nitrogen atoms in the structure provides more redox active sites, increasing the intrinsic conductivity of the material, enabling it to be directly used as an electrode material without any conductive additives.

Description

Technical Field

[0001] The present invention belongs to the field of preparation of organic battery materials, and particularly relates to a highly conductive polymer organic electrode material, a preparation method thereof, and an application thereof. Background Art

[0002] Developing large-scale energy storage devices to cooperate with smart grids to store fluctuating renewable clean energy and match the power supply demands at different times and regions has become an urgent problem to be solved. Rechargeable aqueous batteries are considered an ideal choice for the next generation of large-scale energy storage devices due to their advantages such as low cost, environmental friendliness, and high safety, and have become one of the hot research topics in many countries and regions.

[0003] Currently, the electrode materials of aqueous batteries usually use inorganic materials constructed by metal oxides. However, the extensive use of such materials has brought difficulties in the manufacturing and recycling processes. Therefore, organic materials containing only elements such as carbon, hydrogen, and oxygen and having characteristics such as sustainability and environmental friendliness have become one of the hotspots of global attention, especially in the development potential in the field of energy storage of aqueous batteries as electrode materials. However, the poor conductivity of organic compounds severely limits their electrochemical behavior. To provide satisfactory electron transfer, a large amount of conductive carbon black is generally added during the preparation process (usually 30% is added). Refer to the patent application with the publication number CN111048323B, which discloses a carbon material-based metal oxide electrode and a preparation method thereof. The addition of carbon black will cause an increase in the overall mass of the material, resulting in the inability to reflect the capacity and a significant decrease in the utilization rate of active substances. Summary of the Invention

[0004] Object of the Invention: How to improve the conductivity of polymer materials so that they can be directly used as electrode materials without any conductive additives is particularly important. Considering the above problems, to solve the problem that a large amount of conductive additives need to be added during the use of organic electrode materials due to poor conductivity, the present invention provides a polymer material that can be used to prepare organic electrode materials without adding conductive additives through a solvothermal combined heat treatment method. Through molecular structure design, the intrinsic conductivity of the organic material itself is increased, so that it has good specific capacity and cycle stability without adding conductive additives and can be used as an electrode material.

[0005] Technical Solution:

[0006] In the first aspect, the present invention provides a highly conductive polymer material, and the chemical structural formula of the polymer material is shown as follows:

[0007]

[0008]

[0009] Among them, 1 < n < 21.

[0010] In a second aspect, the present invention also provides a preparation method of a polymer organic electrode material, and the polymer organic electrode material is obtained by the following preparation process:

[0011] Mix aminophenazine and acid anhydride, and ball-mill for 2 hours under an inert atmosphere to obtain a mixed powder A;

[0012] Dissolve the mixed powder A in an organic solvent, and configure it into a mixed solution B after ultrasonic stirring to make it completely dispersed; preferably, a catalyst MnO2 is added during the ultrasonic stirring process;

[0013] React the mixed solution B at a temperature of 120 °C for 5 h for prepolymerization, then raise the temperature to 200 °C and react for 7 hours to obtain a reaction solution C;

[0014] Centrifuge, wash, and freeze-dry the reaction solution C in sequence to obtain a precursor D;

[0015] Place the precursor D under a nitrogen atmosphere, heat it to 180 °C at a rate of 5 °C / min, and keep it warm for 5 h to further remove the solvent remaining during the centrifugation and washing processes and some monomers that were not removed before; then further raise the temperature to 300 °C and keep it warm for 8 h to improve the polycrystalline structure in the polymer structure and increase the regularity, and then naturally cool to room temperature to obtain the electrode material.

[0016] Furthermore, the acid anhydride is 1,4,5,8-naphthalenetetracarboxylic dianhydride;

[0017] Furthermore, the molar ratio of aminophenazine to acid anhydride is (0.3 - 1.5):2;

[0018] Furthermore, the organic solvent is N,N-dimethylformamide;

[0019] Furthermore, in the washing step after centrifuging the reaction solution C, the washing liquids used are N-methylpyrrolidone, ethanol, and deionized water in sequence, and each washing liquid is used for washing 2 times to remove unreacted monomers.

[0020] Furthermore, the specific process of freeze-drying the reaction solution C after centrifugation and washing in sequence is: place the product obtained after centrifugation and washing in a freeze-dryer for freeze-drying, first freeze the material in a quick-freezing bin, and then transfer it to a drying bin for sublimation dehydration. The freeze-drying time is 12 - 18 hours and the temperature is 0 °C.

[0021] As a preferred embodiment of the preparation method of the present invention, the aminophenazine is 2,3-diaminophenazine, and the synthesis reaction equation of the polymer organic electrode material of the present invention is as follows:

[0022]

[0023] As a preferred embodiment of the preparation method of the present invention, the aminophenazine is 1,2-diaminophenazine, and the synthesis reaction equation of the polymer organic electrode material of the present invention is as follows:

[0024]

[0025] As a preferred embodiment of the preparation method of the present invention, the aminophenazine is 1,3-diaminophenazine, and the synthesis reaction equation of the polymer organic electrode material of the present invention is as follows:

[0026]

[0027] As a preferred embodiment of the preparation method of the present invention, the aminophenazine is 1,4-diaminophenazine, and the synthesis reaction equation of the polymer organic electrode material of the present invention is as follows:

[0028]

[0029] In a third aspect, the present invention also provides an application of the polymer organic electrode material as a negative electrode material for an aqueous battery.

[0030] As a preferred embodiment of the above application, the specific operation steps of the application of the polymer organic electrode material as a negative electrode material for an aqueous battery include: mixing and grinding the above polymer organic electrode material and a binder to obtain a slidable slurry, uniformly coating the slurry on a conductive carbon paper, and drying for 8-10 hours to obtain a negative electrode of the aqueous battery. Further preferably, the binder is polyvinylidene fluoride.

[0031] Principle of the invention: Through molecular structure design, the present invention for the first time prepares a polymer with high conductivity by a solvothermal method combined with a heat treatment method. By controlling the temperature step by step during the reaction process and applying a protective gas nitrogen, nitrogen atoms are successfully introduced into the molecular structure to provide more active sites, thereby improving the intrinsic conductivity of the material, so that it can be used as an electrode material without adding a conductive additive.

[0032] Based on the above technology, the beneficial advantages of the present invention are as follows: The highly conductive polymer organic electrode material of the present invention forms a π-conjugated aromatic compound through the introduction of nitrogen atoms and the extension of the conjugated system, generating multiple active sites, namely the C=N double bond and C=O double bond in the structure, reducing the molecular energy gap, improving the intrinsic conductivity of the material, and enabling it to be directly used as an electrode material; at the same time, the raw materials are easily obtained, and large-scale production is expected to be achieved, thus having good application prospects. Description of the Drawings

[0033] Figure 1 It is a scanning electron microscope image of the polymer organic electrode material prepared in Example 1 of the present invention;

[0034] Figure 2 It is an infrared spectrum diagram of the polymer organic electrode material prepared in Example 1 of the present invention;

[0035] Figure 3 It is an X-ray diffraction spectrum diagram of the polymer organic electrode material powder prepared in Example 1 of the present invention;

[0036] Figure 4 It is a cyclic voltammetry curve (CV) diagram of the electrode sheet made of the polymer organic electrode material based on Example 1 at different scanning rates;

[0037] Figure 5 It is a galvanostatic charge-discharge curve (GCD) diagram of the electrode sheet made of the polymer organic electrode material based on Example 1 at different current densities;

[0038] Figure 6 It is a mass specific capacity comparison diagram of the electrode sheets made of the polymer organic electrode materials based on Examples 1-5 at a current density of 1 A / g; -1

[0039] Figure 7 It is a rate performance diagram of the electrode sheet made of the polymer organic electrode material based on Example 1 at different current densities;

[0040] Figure 8 It is a cycling performance diagram of the electrode sheet made of the polymer organic electrode material based on Example 1 at a current density of 10 A / g; -1

[0041] Figure 9 It is a specific capacity comparison diagram of the electrode sheets made of the polymer organic electrode materials based on Examples 1, 6-8 at different current densities;

[0042] Figure 10 It is a comparison diagram of the specific capacities of the electrode sheets made of the polymer organic electrode material of Example 1 and the electrode sheets made of the polymer organic electrode materials of Comparative Examples 1-3 at a current density of 1 A / g; -1Capacity comparison diagram under current density;

[0043] Figure 11 It is the energy gap diagram of the lowest unoccupied molecular orbital (LUMO) and the highest occupied molecular orbital (HOMO) of different polymers obtained by Gaussian calculation. Detailed implementation mode

[0044] In order to make the technical solution, invention purpose, etc. of the present invention clearer, the present invention will be further described below in conjunction with preferred embodiments and comparative examples.

[0045] Example 1

[0046] The polymer organic electrode material described in the present invention is prepared by the following method:

[0047] Step S1, mix 420 mg of 2,3-diaminophenazine with 536 mg of 1,4,5,8-naphthalenetetracarboxylic dianhydride, and ball mill for 2 hours under a nitrogen atmosphere to obtain mixed powder A.

[0048] Step S2, first place 956 mg of mixed powder A in 35 ml of N,N-dimethylformamide, add the catalyst MnO2, and perform ultrasonic dispersion in hot water at 60 °C. The specific ultrasonic dispersion time is 10 minutes and the frequency is 60 Hz to obtain mixed solution B.

[0049] Step S3, then transfer 35 mL of mixed solution B to a reaction kettle, first perform pre-polymerization at 120 °C for 5 hours, then raise the temperature to 200 °C and react for 7 hours to obtain reaction solution C.

[0050] Step S4, first filter the reaction solution C multiple times to remove the catalyst, and then perform centrifugal washing on the reaction solution C with a large amount of N,N-dimethylformamide, water, and ethanol. The centrifugal washing speed is 10,000 revolutions per minute for 5 minutes; place the centrifuged substance in a freeze dryer at 0 °C and a vacuum degree of 110 k, and freeze dry for 12 hours to obtain product precursor D.

[0051] Step S5, finally place the precursor D in a quartz crucible for encapsulation, and place the encapsulated crucible horizontally in a vacuum tube furnace under a nitrogen atmosphere. Starting from room temperature of 25 °C, raise the temperature to 180 °C at a rate of 5 °C / min and keep it warm for 5 hours to remove unreacted monomer impurities; then further raise the temperature to 300 °C and keep it warm for 8 hours to improve the polycrystalline structure in the polymer structure and increase the regularity, and then naturally cool to room temperature to obtain the polymer organic electrode material.

[0052] Figure 1 It is the scanning electron microscope image of the polymer organic electrode material powder prepared by the solvothermal reaction. Obvious spherical structures can be seen from the figure.

[0053] Figure 2 is the infrared spectrum of the polymer organic electrode material powder, where the characteristic peak at 1680 cm -1 corresponds to the C=O bond in the polymer molecular structure; the characteristic peak at 1475 cm -1 corresponds to the C=N bond in the structure.

[0054] Figure 3 is the X-ray diffraction pattern of the polymer organic electrode material powder. The pattern shows that there are sharp peaks in the range of 10-70°, and a broad peak near 26° (different π-π stacking distances). The sharp peaks indicate that the polymer has a good crystalline structure.

[0055] Example 2

[0056] Different from Example 1, the molar ratio of 1,4,5,8-naphthalenetetracarboxylic dianhydride to 2,3-diaminophenazine is 0.5:1, and the other conditions remain unchanged.

[0057] Example 3

[0058] Different from Example 1, the molar ratio of 1,4,5,8-naphthalenetetracarboxylic dianhydride to 2,3-diaminophenazine is 1:0.5.

[0059] Example 4

[0060] Different from Example 1, the molar ratio of 1,4,5,8-naphthalenetetracarboxylic dianhydride to 2,3-diaminophenazine is 1.5:1.

[0061] Example 5

[0062] Different from Example 1, the molar ratio of 1,4,5,8-naphthalenetetracarboxylic dianhydride to 2,3-diaminophenazine is 1:2, and the reaction time is 48 hours.

[0063] Example 6

[0064] Different from Example 1, the aminophenazine is 1,2-diaminophenazine, and the molar ratio to 1,4,5,8-naphthalenetetracarboxylic dianhydride is 1:1.

[0065] Example 7

[0066] Different from Example 1, the aminophenazine is 1,3-diaminophenazine, and the molar ratio to 1,4,5,8-naphthalenetetracarboxylic dianhydride is 1:1.

[0067] Example 8

[0068] Different from Example 1, the aminophenazine is 1,4-diaminophenazine, and the molar ratio to 1,4,5,8-naphthalenetetracarboxylic dianhydride is 1:1.

[0069] Comparative Example 1

[0070] Different from Example 1, the reaction kettle containing the mixed solution B was pre-polymerized at 120 °C for 5 hours, then the temperature was raised to 180 °C, and the reaction time was 48 hours.

[0071] Comparative Example 2

[0072] Different from Example 1, the reaction kettle containing the mixed solution B was pre-polymerized at 120 °C for 5 hours, then the temperature was raised to 190 °C, and the reaction time was 48 hours.

[0073] Comparative Example 3

[0074] Different from Example 1, the reaction kettle containing the mixed solution B was pre-polymerized at 120 °C for 5 hours, then the temperature was raised to 210 °C, and the reaction time was 48 hours.

[0075] The polymer organic electrode materials prepared in Examples 1-8 were made into electrode sheets, and the relevant electrochemical properties of the electrode sheets were tested. The specific test methods are as follows:

[0076] Weigh 9 mg of the electrode materials prepared in Examples 1-6 and 1 mg of the binder respectively, mix them, and ball-mill them for 1.5 hours to obtain the mixed powder E. Then place E in a mortar, add 3-4 drops of N-methylpyrrolidone, and grind it into a slurry with no particles on the surface and capable of sliding evenly along the inner wall of the mortar. Coat the slurry on the carbon paper and dry it in vacuum at 60 °C for 8 hours to make an electrode sheet.

[0077] The electrochemical test methods for the polymer organic electrodes prepared in Comparative Examples 1-3 are the same as those in Examples 1-8.

[0078] Based on the electrode sheets made of the polymer organic electrode materials prepared in Examples 1-8 of the present invention, electrochemical tests were carried out in a 1M H2SO4 electrolyte using a three-electrode system. It was found that they had good electrochemical properties.

[0079] Figure 4 It is a cyclic voltammetry (CV) diagram of the electrode sheet made of the polymer organic electrode material based on Example 1 at different scan rates. Two obvious oxidation-reduction peaks can be seen in the figure, further indicating that the organic compound has multiple reactive sites.

[0080] Figure 5 It is a galvanostatic charge-discharge curve (GCD) diagram of the electrode sheet made of the polymer organic electrode material based on Example 1 at different current densities. It can be seen that obvious charge-discharge platforms appear in the GCD diagram, which correspond to the oxidation-reduction peaks in the CV diagram. At the same time, it can be seen that the current density is 1A g -1When it is, the specific capacity of the highly conductive polymer organic electrode can reach 207 mA h / g -1 , even at a high current density of 20 A / g -1 , it still has a high specific capacity of 114.6 mA h / g -1 .

[0081] Figure 6 Figure showing the mass specific capacity comparison of the electrode sheets made from the polymer organic electrode materials of Examples 1 - 5 at a current density of 1 A / g -1 . It can be seen from the figure that when the ratio of anhydride to phenazine is 1:1, the prepared electrode material has the best electrochemical performance.

[0082] Figure 7 Figure showing the rate performance of the electrode sheets made from the polymer organic electrode material of Example 1 at different current densities. It can be seen that for the polymer electrode material prepared by this method, its specific capacity is considerable under both high and low current density working conditions.

[0083] Figure 8 It can be seen that after 700 cycles at a current density of 10 A / g -1 , the capacity of the electrode sheet made from the polymer organic electrode material of Example 1 hardly decays, showing good stability.

[0084] Figure 9 Figure showing the specific capacity comparison of the electrode sheets made from the polymer organic electrode materials of Example 1, Examples 6 - 8 at different current densities. From the figure, it can be seen that when 2,3 - diamino - phenazine is used as the amino - phenazine, the electrode sheet made from the obtained organic electrode material has the highest specific capacity.

[0085] Figure 10 Figure showing the specific capacity comparison of the electrode sheets made from the organic electrode materials obtained at different reaction temperatures at a current density of 1 A / g -1 . It can be seen from the figure that the optimal reaction temperature is 200 °C.

[0086] Figure 11 Figure showing the energy gap between the lowest unoccupied molecular orbital (LUMO) and the highest occupied molecular orbital (HOMO) of different polymers obtained by Gaussian calculation. The smaller this value, the better the electron affinity of the material, that is, the better the conductivity. Figure 11 The sources of other polymer materials involved in

[0087] Among them, PTO-4PZ is from the public literature Sun Tianjiang, Zhang Weijia, Nian Qingshun, et al. Proton-insertion dominated polymer cathode for high-performance aqueous zinc-ion battery. Chemical Engineering Journal, 2023;

[0088] Among them, PDPZ is from the public literature Shi Minjie, Wang Renyuan, Li Lingyun, et al. Redox-Active Polymer Integrated with MXene for Ultra-Stable and Fast Aqueous Proton Storage. Advanced Functional Materials, 2022.

[0089] Among them, P-Q is from the public literature Zhu Meihua, Zhao Li, Ran Qing, et al. Bioinspired Catechol-Grafting PEDOT Cathode for an All-Polymer Aqueous Proton Battery with High Voltage and Outstanding Rate Capacity. [J]. Advanced science (Weinheim, Baden-Wurttemberg, Germany), 2021, 9(4): e2103896-e2103896.

[0090] Among them, AN-TA is from the public literature Lakshmi K C S, Vedhanarayanan B, Cheng HY, et al. Molecularly engineered organic copolymers as high capacity cathode materials for aqueous proton battery operating at sub-zero temperatures [J]. Journal of Colloid and Interface Science, 2022, 619: 123-131.

[0091] Both the capacity and cycle retention rate of the present invention exhibit greater advantages. The maximum discharge specific capacity reaches 207 mA h / g. -1 , and the capacity basically does not decay after 700 cycles. Even at a current density of 20 A / g -1 , without adding conductive additives, it still has a specific capacity of 114 mA h / g -1 , which is incomparable to most polymers. The capacity and rate performance of the electrode sheet made of the polymer material provided by the present invention also have great advantages. From the electrochemical test results, the present invention has indeed achieved an increase in the intrinsic conductivity of the organic material, enabling it to be used as an electrode material without adding conductive additives, greatly improving the utilization rate of the material. At the same time, through calculation, the energy gap between the lowest unoccupied molecular orbital (LUMO) and the highest occupied molecular orbital (HOMO) of the polymer organic electrode material PI-DAP prepared in Example 1 of the present invention is 2.53 eV. This is much lower than the energy gaps of other polymers, indicating its good electron affinity and conjugation performance, providing a way to improve the conductivity.

Claims

1. A highly conductive polymer electrode material, characterized in that, The chemical structural formula of the high-conductivity polymer electrode material is as follows: ， Wherein, n is a positive integer and 1 < n < 21.

2. The preparation method of the highly conductive polymer electrode material according to claim 1, characterized in that, The preparation method includes the steps of: mixing aminophenazine and acid anhydride, and ball-milling for 2 hours under an inert atmosphere to obtain a mixed powder A; dissolving the mixed powder A in an organic solvent, and ultrasonically stirring to completely disperse it to prepare a mixed solution B; reacting the mixed solution B at 120 °C for 5 h for prepolymerization, then raising the temperature to 200 °C and reacting for 7 hours to obtain a reaction solution C; centrifuging, washing, and freeze-drying the reaction solution C to obtain a precursor D; placing the precursor D under a nitrogen atmosphere, heating it to 180 °C at a rate of 5 °C / min, holding for 5 h, then further heating to 300 °C, holding for 8 h, and then naturally cooling to room temperature to obtain the electrode material.

3. The preparation method of the highly conductive polymer electrode material according to claim 2, characterized in that, The acid anhydride is 1,4,5,8-naphthalenetetracarboxylic dianhydride.

4. The preparation method of the highly conductive polymer electrode material according to claim 2, wherein The molar ratio of the aminophenazine to the acid anhydride is (0.3 - 1.5):

2.

5. The preparation method of the highly conductive polymer electrode material according to claim 2, characterized in that, The organic solvent is N,N-dimethylformamide.

6. The preparation method of the highly conductive polymer electrode material according to claim 2, wherein The aminophenazine is 2,3-diaminophenazine, and the synthesis reaction equation of the high-conductivity polymer electrode material is as follows: 。 7. The preparation method of the highly conductive polymer electrode material according to claim 2, wherein The aminophenazine is 1,2-diaminophenazine, and the synthesis reaction equation of the high-conductivity polymer electrode material of the present invention is as follows: 。 8. The preparation method of the highly conductive polymer electrode material according to claim 2, characterized in that, The aminophenazine is 1,3-diaminophenazine, and the synthesis reaction equation of the high-conductivity polymer electrode material of the present invention is as follows: 。 9. The preparation method of the highly conductive polymer electrode material according to claim 2, characterized in that, The aminophenazine is 1,4-diaminophenazine, and the synthesis reaction equation of the high-conductivity polymer electrode material of the present invention is as follows: 。 10. Application of the high-conductivity polymer electrode material described in claim 1 as a negative electrode material for an aqueous battery.

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