Bipolar small organic molecule positive electrode material with stable hydrogen bonds, preparation method and application

Abstract

The invention provides a bipolar organic micromolecular positive electrode material with stable hydrogen bonds, a preparation method and application, and the preparation method comprises the following steps: weighing # imgabs0 # conductive agent and adhesive, adding a solvent, uniformly grinding to obtain slurry, uniformly coating a current collector with the slurry, and drying to obtain the positive electrode material.

Description

Technical Field

[0001] The invention relates to the technical field of chemical power sources, and in particular to a hydrogen-bond-stabilized bipolar organic small molecule positive electrode material, a preparation method and an application thereof. Background Art

[0002] In the context of the urgent pursuit of sustainable energy solutions, the development of practical and economical energy storage devices has become a core strategy to solve the contemporary energy crisis and environmental protection issues. Aqueous zinc-ion batteries are regarded as an important candidate for future energy storage technology due to their unique advantages of high theoretical capacity and low redox potential, showing great application potential. However, the development of zinc batteries still faces severe challenges such as slow kinetics, limited capacity and poor cycle stability, which seriously restrict the full performance of their performance.

[0003] Given that the energy storage efficiency of aqueous zinc-ion batteries is highly dependent on the interaction between redox-active motifs and charge carriers, designing and optimizing cathode materials with multiple active sites has become a key path to improving battery performance. In this context, organic small molecules have rapidly emerged in the field of zinc-organic batteries due to their advantages such as resource renewability, structural designability, and functional customizability, providing new possibilities for achieving efficient energy storage.

[0004] Among the many different types of organic cathode materials, bipolar organic compounds cleverly combine the high capacity characteristics of n-type organics with the high discharge voltage advantages of p-type organics, effectively overcoming the limitations of a single type of material and providing a fast and stable solution for zinc ion storage. However, such materials still face problems such as poor solubility resistance, insufficient structural stability, and low conductivity in practical applications, resulting in sluggish reaction kinetics and shortened cycle life, limiting the further development of zinc-organic batteries. To overcome this challenge, it is urgent to design bipolar organic cathode materials with high stability and high density of redox active sites. Summary of the invention

[0005] The present invention is made to solve the above problems, and aims to provide a hydrogen-bond-stabilized bipolar organic small molecule positive electrode material, a preparation method and an application thereof, which has high stability and high-density bipolar redox group active sites.

[0006] The present invention provides a method for preparing a hydrogen-bond-stabilized bipolar organic small molecule positive electrode material, which has the following characteristics:

[0007] Weigh A conductive agent and a binder are mixed with a solvent and uniformly ground to obtain a slurry, the slurry is uniformly coated on a current collector, and the positive electrode material is obtained after drying.

[0008] The method for preparing the hydrogen-bond-stabilized bipolar organic small molecule positive electrode material provided by the present invention may also have the following characteristics: wherein, The mass ratio of the conductive agent to the adhesive is (6-7):(2-3):1.

[0009] The method for preparing the hydrogen-bond-stabilized bipolar organic small-molecule positive electrode material provided by the present invention may also have the following characteristics: wherein the drying temperature is 70-90° C. and the drying time is 10-14 h.

[0010] The method for preparing the hydrogen-bond-stabilized bipolar organic small-molecule positive electrode material provided by the present invention may also have the following characteristics: wherein the conductive agent is any one of graphite, carbon black or acetylene black.

[0011] The method for preparing the hydrogen-bond-stabilized bipolar organic small molecule positive electrode material provided by the present invention may also have the following characteristics: wherein the binder is polytetrafluoroethylene, and the solvent is any one of N-methylpyrrolidone, dimethylformamide or ethanol.

[0012] The method for preparing the hydrogen-bond-stabilized bipolar organic small molecule positive electrode material provided by the present invention may also have the following characteristics: wherein the current collector is any one of titanium foil, nickel mesh, titanium mesh, stainless steel mesh or carbon paper.

[0013] The present invention also provides a hydrogen-bond-stabilized bipolar organic small molecule positive electrode material, which has the following characteristics: it is prepared by a method for preparing a hydrogen-bond-stabilized bipolar organic small molecule positive electrode material.

[0014] The present invention also provides an application of a hydrogen-bond-stabilized bipolar organic small molecule positive electrode material in assembling a positive electrode of an aqueous zinc ion battery.

[0015] In the application of the hydrogen-bond-stabilized bipolar organic small molecule positive electrode material provided by the present invention in assembling the positive electrode of an aqueous zinc ion battery, the following characteristics may also be provided: wherein the hydrogen-bond-stabilized bipolar organic small molecule positive electrode material is used as the positive electrode of the battery, a high-purity commercial zinc foil with a zinc content of ≥99.99% is used as the negative electrode, filter paper or glass fiber is used as the filter paper, a separator is placed between the positive electrode and the negative electrode, and after being arranged, it is placed in a battery shell, and then an electrolyte is added.

[0016] In the application of the hydrogen bond stabilized bipolar organic small molecule positive electrode material provided by the present invention in assembling the positive electrode of an aqueous zinc ion battery, it can also have the following characteristics: wherein the electrolyte is one or more of Zn(CF3SO3)2, ZnCl2 or ZnSO4 aqueous solutions.

[0017] Functions and Effects of the Invention

[0018] According to the hydrogen-bond-stabilized bipolar organic small molecule positive electrode material, preparation method and application involved in the present invention, the present invention introduces the p-type -NH motif and the n-type C=O group with high redox activity into the organic positive electrode material, which can not only promote the reversible electrochemical process, but also significantly improve the reaction kinetics rate. At the same time, by constructing an intermolecular hydrogen bond network, the structural stability of the organic molecule can be significantly enhanced, the capacity loss can be reduced, and the durability of the charge transfer can be ensured. In addition, the extended π-conjugated molecular structure can effectively promote the delocalization of electrons between molecules, improve the overall conductivity of the material, and accelerate charge storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a scanning electron micrograph of 5,12-dihydroquinolin[2,3-b]acridine-7,14-dione;

[0020] Figure 2 Schematic diagram of hydrogen bonding of 5,12-dihydroquinolin[2,3-b]acridine-7,14-dione organic small molecule;

[0021] Figure 3 is the band gap of 5,12-dihydroquinolin[2,3-b]acridine-7,14-dione;

[0022] Figure 4 This is a rate performance diagram of the aqueous zinc-organic battery in Example 1 of the present invention;

[0023] Figure 5 This is a cycle stability diagram of the aqueous zinc-organic battery in Example 1 of the present invention at a current density of 2 A / g;

[0024] Figure 6 This is a rate performance diagram of the aqueous zinc-organic battery in Example 2 of the present invention;

[0025] Figure 7 This is a rate performance diagram of the aqueous zinc-organic battery in Example 3 of the present invention;

[0026] Figure 8 This is a cycle stability diagram of the aqueous zinc-organic battery in Example 3 of the present invention at a current density of 2 A / g. DETAILED DESCRIPTION

[0027] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0028] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the following examples and drawings specifically describe a hydrogen-bond-stabilized bipolar organic small molecule positive electrode material, preparation method and application of the present invention.

[0029] Example 1

[0030] The method for preparing a hydrogen-bond-stabilized bipolar organic small molecule positive electrode material of this embodiment comprises the following steps:

[0031] 0.03g 0.015 g of acetylene black conductive agent and 0.005 g of polytetrafluoroethylene binder were mixed in a mass ratio of 6:3:1, and 70 μL of N-methylpyrrolidone was added and ground for 30 min to obtain a slurry. The slurry was evenly coated on a titanium foil current collector with a diameter of 1.2 cm using a blade, with a mass loading of 2.8 mg cm –1 , and then placed in a vacuum oven at 80°C for 12 hours to obtain the positive electrode material.

[0032] In this embodiment, the prepared battery positive electrode is further used to assemble an aqueous zinc-organic battery, as follows:

[0033] The prepared battery positive electrode is used as the positive electrode, and high-purity commercial zinc foil (zinc content ≥ 99.99%) is used as the negative electrode. A GE-Whatman glass fiber separator is placed between the positive and negative electrodes. After arranging, it is placed in a CR2032 button battery shell, and then 3M Zn(CF3SO3)2 electrolyte is added to assemble an aqueous zinc-organic battery.

[0034] The raw materials used in this example are all commercially available reagent grade products.

[0035] In this embodiment, the prepared aqueous zinc-organic battery was also subjected to electrochemical performance testing, including: testing the device energy storage performance by using a CHI660E electrochemical workstation. Cycling and rate performance tests were performed on a LAND CT2001A battery testing system. The voltage window was 0.2–1.6V.

[0036] Figure 1 is a scanning electron microscope image of 5,12-dihydroquinolino[2,3-b]acridine-7,14-dione in Example 1 of the present invention.

[0037] like Figure 1 As shown, 5,12-dihydroquinolin[2,3-b]acridine-7,14-dione organic small molecule has a regular rod-like geometric morphology.

[0038] Figure 2 Schematic diagram of hydrogen bonding of the hydrogen-bond-stabilized 5,12-dihydroquinolino[2,3-b]acridine-7,14-dione organic small molecule in Example 1 of the present invention.

[0039] like Figure 2 As shown, the hydrogen-bond-stabilized 5,12-dihydroquinolin[2,3-b]acridine-7,14-dione organic small molecule designed in this embodiment has a nitrogen heterocycle π-conjugated aromatic structure and contains multiple redox-active carbonyl / imine sites, which can form an NH···O type hydrogen bond network.

[0040] Figure 3 is the energy band gap of 5,12-dihydroquinolino[2,3-b]acridine-7,14-dione in Example 1 of the present invention.

[0041] like Figure 3 As shown, 5,12-dihydroquinolinato[2,3-b]acridine-7,14-dione has an ultra-low energy band gap of 1.97 eV, which is much lower than most organic electrode materials, indicating that this organic small molecule has high electrical conductivity, which is beneficial to its better charge transfer efficiency and lower kinetic hindrance when used in batteries to promote redox reactions.

[0042] Figure 4 This is a rate performance diagram of a zinc-organic battery assembled with a 5,12-dihydroquinolin[2,3-b]acridine-7,14-dione organic small molecule positive electrode, a zinc foil negative electrode and a Zn(CF3SO3)2 aqueous electrolyte in Example 1 of the present invention.

[0043] like Figure 4 As shown, the aqueous zinc-organic battery prepared in this embodiment has a specific capacity of more than 212 mAh / g when charged and discharged at 0.2 A / g, and a rate capacity of more than 146 mAh / g when charged and discharged at 10 A / g, showing high specific capacity storage performance.

[0044] Figure 5 This is a cycle stability diagram of a zinc-organic battery assembled with a 5,12-dihydroquinolin[2,3-b]acridine-7,14-dione organic small molecule positive electrode, a zinc foil negative electrode and a Zn(CF3SO3)2 aqueous electrolyte at a current density of 2A / g in Example 1 of the present invention.

[0045] like Figure 5 As shown, the capacity retention rate of the aqueous zinc-organic battery prepared in this example after 20,000 cycles of charge and discharge is 71.2%, which has excellent cycle stability.

[0046] Example 2

[0047] In this example, based on the preparation conditions of Example 1, 0.03 g 0.015g acetylene black conductive agent and 0.005g polytetrafluoroethylene adhesive are replaced with: 0.035g 0.01g graphite conductive agent and 0.005g polytetrafluoroethylene binder.

[0048] In this embodiment, the prepared aqueous zinc-organic battery was subjected to electrochemical performance testing, including: testing the device energy storage performance through a CHI660E electrochemical workstation. Cycling and rate performance tests were performed on a LAND CT2001A battery testing system, with a voltage window of 0.2–1.6V.

[0049] Figure 6 Graph showing the rate performance of the aqueous zinc-organic battery in Example 2 of the present invention. Figure 6 As shown, the aqueous zinc-organic battery prepared in this embodiment has a specific capacity of more than 200 mAh / g when charged and discharged at 0.2 A / g, and a rate capacity of more than 131 mAh / g when charged and discharged at 10 A / g, showing a high specific capacity storage performance.

[0050] Example 3

[0051] In this embodiment, based on the preparation conditions of Example 1, when the prepared battery positive electrode is used to assemble an aqueous zinc-organic battery, the aqueous zinc-organic battery electrolyte is replaced with ZnSO4.

[0052] Figure 7 : is a rate performance diagram of the aqueous zinc-organic battery in Example 3 of the present invention. Figure 7 As shown, the aqueous zinc-organic battery prepared in this embodiment has a specific capacity of more than 206 mAh / g when charged and discharged at 0.2 A / g, and a rate capacity of 121 mAh / g when charged and discharged at 10 A / g.

[0053] Figure 8 Graph 3 is a graph of the cycle stability of the aqueous zinc-organic battery at a current density of 2A / g in Example 3 of the present invention. Figure 8 As shown, the capacity retention rate of the aqueous zinc-organic battery prepared in this embodiment after 20,000 cycles of charge and discharge is 68.3%, and the cycle stability is good.

[0054] Functions and Effects of the Embodiments

[0055] According to the hydrogen-bond-stabilized bipolar organic small molecule positive electrode material, preparation method and application involved in the present invention, the present invention introduces the p-type -NH motif and the n-type C=O group with high redox activity into the organic positive electrode material, which can not only promote the reversible electrochemical process, but also significantly improve the reaction kinetics rate. At the same time, by constructing an intermolecular hydrogen bond network, the structural stability of the organic molecule can be significantly enhanced, the capacity loss can be reduced, and the durability of the charge transfer can be ensured. In addition, the extended π-conjugated molecular structure can effectively promote the delocalization of electrons between molecules, improve the overall conductivity of the material, and accelerate charge storage.

[0056] It is a heterocyclic organic molecule containing nitrogen and oxygen elements, which can form a stable NH···O type hydrogen bond network between molecules. At the same time, the π-conjugated planar structure is highly extended, which not only helps to improve the material's anti-solubility in electrolyte solutions, but also promotes the efficient dispersion of electrons in the entire molecular skeleton, thereby effectively reducing the kinetic energy barrier in the redox reaction process, improving the charge transfer efficiency, and improving battery performance.

[0057] When used as the positive electrode active material of aqueous zinc-organic batteries, it can react with Zn in the electrolyte. 2 + / CF3SO3 - The battery assembled by alternating coordination has a specific capacity of more than 212 mAh / g when charged and discharged at 0.2 A / g, and a rate capacity of more than 146 mAh / g when charged and discharged at 10 A / g, showing high specific capacity storage performance. At the same time, the capacity retention rate after 20,000 cycles of charge and discharge is more than 70%, showing high specific capacity, energy density and excellent cycle stability. The prepared positive electrode material can achieve mixed anion-cation co-coordination during the electrochemical reaction, in which the two n-type carbonyl groups couple with the cations at a lower potential, and the two imine groups coordinate with the anions in the high potential range. This not only achieves fast redox reaction kinetics, which is beneficial to a significant increase in battery capacity, but also can effectively inhibit the dissolution of the positive electrode material and improve battery stability.

[0058] The main raw materials for preparing the positive electrode material of the present invention are widely available, low in cost and environmentally friendly. The entire system electrode and electrolyte preparation process is carried out at room temperature and pressure, and the operation is simple, safe and pollution-free.

[0059] Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for preparing a hydrogen-bond-stabilized bipolar organic small molecule cathode material, characterized in that: The steps include: Weigh A conductive agent and a binder are mixed with a solvent and uniformly ground to obtain a slurry, and the slurry is uniformly coated on a current collector and dried to obtain a positive electrode material.

2. The method for preparing the hydrogen-bond-stabilized bipolar organic small molecule cathode material according to claim 1, characterized in that: in, Said The mass ratio of the conductive agent to the adhesive is (6-7):(2-3):

1.

3. The method for preparing the hydrogen-bond-stabilized bipolar organic small molecule cathode material according to claim 1, characterized in that: in, The drying temperature is 70-90° C., and the drying time is 10-14 hours.

4. The method for preparing the hydrogen-bond-stabilized bipolar organic small molecule cathode material according to claim 1, characterized in that: in, The conductive agent is any one of graphite, carbon black or acetylene black.

5. The method for preparing the hydrogen-bond-stabilized bipolar organic small molecule cathode material according to claim 1, characterized in that: in, The adhesive is polytetrafluoroethylene, and the solvent is any one of N-methylpyrrolidone, dimethylformamide or ethanol.

6. The method for preparing the hydrogen-bond-stabilized bipolar organic small molecule cathode material according to claim 1, characterized in that: in, The current collector is any one of titanium foil, nickel mesh, titanium mesh, stainless steel mesh or carbon paper.

7. The hydrogen-bond-stabilized bipolar organic small molecule cathode material according to claim 1, characterized in that: The material is prepared by the method for preparing a hydrogen-bond-stabilized bipolar organic small molecule positive electrode material according to any one of claims 1 to 6.

8. Use of a hydrogen-bond-stabilized bipolar organic small molecule positive electrode material according to claim 7 in assembling a positive electrode of an aqueous zinc ion battery.

9. The use of a hydrogen bond-stabilized bipolar organic small molecule positive electrode material according to claim 8 in assembling a positive electrode of an aqueous zinc ion battery, characterized in that: in, The hydrogen-bond-stabilized bipolar organic small molecule positive electrode material is used as the battery positive electrode, a high-purity commercial zinc foil with a zinc content of ≥99.99% is used as the negative electrode, filter paper or glass fiber is used as filter paper, a separator is placed between the positive electrode and the negative electrode, and after being arranged, it is placed in a battery shell and then an electrolyte is added.

10. The use of a hydrogen bond-stabilized bipolar organic small molecule positive electrode material according to claim 9 in assembling a positive electrode of an aqueous zinc ion battery, characterized in that: in, The electrolyte is one or more of Zn(CF3SO3)2, ZnCl2 or ZnSO4 aqueous solutions.

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