Bipolar organic cathode material and its preparation method and application

Abstract

The present invention relates to a bipolar organic positive electrode material and its preparation method and application, belonging to the technical field of positive electrode material preparation. The structural formula of the bipolar organic positive electrode material of the present invention is #imgabs0# where n≥1. The bipolar organic positive electrode material of the present invention has both phenanthrenequinone and phenazine structures, both of which can be used as energy storage units, have bipolar characteristics, and can store Na + With PF6 ‑ Therefore, the bipolar organic cathode material of the present invention has excellent electrochemical properties. When used as the positive electrode of sodium ion batteries, it exhibits high specific capacity, stable cycling, and excellent rate performance, and has broad application prospects. In addition, the preparation process of the bipolar organic cathode material of the present invention has a simple synthesis route and can be obtained through a single-step synthesis.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparation of positive electrode materials, and relates to a bipolar organic positive electrode material and a preparation method and application thereof. Background Art

[0002] With the rapid development of electronic products, electric vehicles, and energy storage power stations, the demand for batteries has surged. In this trend, sodium-ion batteries (SIBs) are expected to replace and complement lithium-ion batteries, enabling new battery systems for large-scale energy storage. Consequently, there is an urgent need to identify and develop SIB cathode materials with high specific capacity, stable cycling, high energy density, and low cost.

[0003] The practical application of inorganic electrode materials is restricted by the limited reserves of transition metals and the structural instability caused by the insertion and removal of large-radius sodium ions. In contrast, organic materials are abundant in source, inexpensive, insensitive to the size of metal ions, and can accommodate large-radius sodium ions, which is conducive to the rapid insertion / removal of sodium ions. In addition, the structure of organic molecules is flexible, easy to control, and has the advantages of strong designability. However, most organic materials still have the problems of easy solubility during circulation and low electronic conductivity, which hinder their practical application. Through molecular engineering design and optimization of molecular structure, it is expected to obtain high-energy-density electrode materials, thereby preparing high-efficiency sodium-ion batteries.

[0004] Organic electrode materials (OEM) are abundant in reserves, environmentally friendly, and their performance can be adjusted through structural modification. Unlike inorganic materials, organic materials have less structural changes during charge and discharge, and can adapt to the insertion and removal of ions of various sizes (such as metal ions and anions). Bipolar organics have the properties of both n-type and p-type materials, and can be reduced or oxidized at the same time, respectively accepting cations (Li + 、Na + or K + etc.) or anions (PF6 - 、ClO4 - or TFSI-, etc.). Therefore, their applications can be expanded from traditional rocking chair batteries to dual-ion batteries. Furthermore, bipolar materials can serve as both the cathode and anode in organic symmetrical batteries, which can reduce material costs and simplify battery manufacturing. However, organic electrode materials generally still have the following disadvantages: the solubility of organic substances in the electrolyte during charge and discharge may reduce the stability of dual-ion batteries.

[0005] Therefore, it is necessary to further study bipolar organic cathode materials in order to solve the above problems. Summary of the Invention

[0006] In view of this, one of the objects of the present invention is to provide a bipolar organic positive electrode material; a second object of the present invention is to provide a method for preparing a bipolar organic positive electrode material; a third object of the present invention is to provide an application of a bipolar organic positive electrode material in a sodium ion battery.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] 1. A bipolar organic cathode material, the structural formula of which is as follows:

[0009] Where n≥1.

[0010] Preferably, n is an integer greater than or equal to 1.

[0011] 2. A method for preparing the above-mentioned bipolar organic cathode material, the method comprising the following steps:

[0012] (1) 2,7-dibromophenanthrene-9,10-dione, 5,10-dihydrophenazine, 2-dicyclohexylphosphino-2',6'-diisopropoxy-1,1'-biphenyl (Ruphos), chloro(2-dicyclohexylphosphino-2',6'-diisopropoxy-1,1'-biphenyl)(2-amino-1,1'-biphenyl-2-yl)palladium(II) (Ruphos Pd G2) and sodium tert-butoxide were placed in a glove box, xylene was added to dissolve the mixture under an argon atmosphere, and the mixture was uniformly mixed to obtain a mixture;

[0013] (2) heating the mixture to 100-130° C. and then heating under reflux for 12-36 hours, then heating to 130-160° C. and then heating under reflux for 36-60 hours, and cooling to room temperature after the reaction is completed;

[0014] (3) The solution after the reaction in step (2) is filtered under reduced pressure to obtain a solid crude product, which is washed and then vacuum dried to obtain a dark brown solid, which is the bipolar organic cathode material (PQPZ).

[0015] Preferably, in step (1), the molar ratio of 2,7-dibromophenanthrene-9,10-dione, 5,10-dihydrophenazine, 2-dicyclohexylphosphino-2',6'-diisopropoxy-1,1'-biphenyl (Ruphos), chloro(2-dicyclohexylphosphino-2',6'-di-isopropoxy-1,1'-biphenyl)(2-amino-1,1'-biphenyl-2-yl)palladium(II) (Ruphos Pd G2) and sodium tert-butoxide is 1:0.8~1.2:0.02~0.06:0.02~0.06:3.0~7.0.

[0016] Preferably, in step (3), the washing is specifically: washing with toluene, deionized water, methanol, dichloromethane and acetone in sequence.

[0017] Preferably, in step (3), the vacuum drying is specifically: drying at 60-100° C. for 12-36 hours.

[0018] 3. Application of the above-mentioned bipolar organic cathode materials in sodium ion batteries.

[0019] The beneficial effects of the present invention are as follows: The present invention discloses a bipolar organic cathode material, the structural formula of which is Where n≥1. The bipolar organic cathode material of the present invention has both phenanthrenequinone and phenazine structures, both of which can be used as energy storage units, and has bipolar characteristics, and can store Na + With PF6 - Therefore, the bipolar organic cathode material of the present invention has excellent electrochemical properties. When used as the positive electrode of sodium ion batteries, it exhibits high specific capacity, stable cycling, and excellent rate performance, and has broad application prospects. In addition, the preparation process of the bipolar organic cathode material of the present invention has a simple synthesis route and can be obtained through a single-step synthesis.

[0020] Other advantages, objects, and features of the present invention will be described in part in the following description and, in part, will be apparent to those skilled in the art upon examination of the following description or may be learned from practice of the present invention. The objects and other advantages of the present invention may be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below with reference to the accompanying drawings, in which:

[0022] Figure 1 This is the infrared spectrum of the bipolar organic cathode material (polymer PQPZ) prepared in Example 1;

[0023] Figure 2 This is a thermal field emission scanning electron microscope image of the bipolar organic cathode material (polymer PQPZ) prepared in Example 1;

[0024] Figure 3 This is the X-ray diffraction pattern of the bipolar organic cathode material (polymer PQPZ) prepared in Example 1;

[0025] Figure 4 The cycle test results of the button cell using the bipolar organic cathode material (polymer PQPZ) prepared in Example 1 as the cathode material are shown in FIG.

[0026] Figure 5 The rate performance test results of a button cell test using the bipolar organic cathode material (polymer PQPZ) prepared in Example 1 as the cathode material are shown.

[0027] Figure 6 The cyclic voltammetry curve test results of the button cell test using the bipolar organic positive electrode material (polymer PQPZ) prepared in Example 1 as the positive electrode material. DETAILED DESCRIPTION

[0028] The following describes the embodiments of the present invention by means of specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0029] Example 1

[0030] A bipolar organic cathode material, the specific preparation method is as follows:

[0031] (1) 366.01 mg of 2,7-dibromophenanthrene-9,10-dione, 150 mg of 5,10-dihydrophenazine, 14.4 mg of 2-dicyclohexylphosphino-2',6'-diisopropoxy-1,1'-biphenyl (Ruphos), 19.2 mg of chloro(2-dicyclohexylphosphino-2',6'-diisopropoxy-1,1'-biphenyl)(2-amino-1,1'-biphenyl-2-yl)palladium(II), and 392.6 mg of sodium tert-butoxide were placed in a 200 mL dry Schlenk bottle, placed in a glove box, and 60 mL of xylene was added with a syringe under an argon atmosphere to dissolve the mixture, and mixed uniformly to obtain a mixture;

[0032] (2) The mixture was heated to 120°C and then heated under reflux for 24 h, then heated to 140°C and then heated under reflux for 48 h. After the reaction was completed, the mixture was cooled to room temperature;

[0033] (3) The solution after the reaction in step (2) was filtered under reduced pressure to obtain a solid crude product, which was washed (washed with toluene, deionized water, methanol, dichloromethane and acetone in sequence) and then vacuum dried (dried at 80°C for 24 hours) to obtain 232 mg of dark brown solid (yield 51.3%), which is a bipolar organic positive electrode material (polymer PQPZ).

[0034] Example 2

[0035] A bipolar organic cathode material, the specific preparation method is as follows:

[0036] (1) 366.01 mg of 2,7-dibromophenanthrene-9,10-dione, 218.67 mg of 5,10-dihydrophenazine, 28.0 mg of 2-dicyclohexylphosphino-2',6'-diisopropoxy-1,1'-biphenyl, 46.6 mg of chloro(2-dicyclohexylphosphino-2',6'-diisopropoxy-1,1'-biphenyl)(2-amino-1,1'-biphenyl-2-yl)palladium(II) (Ruphos Pd G2), and 672.7 mg of sodium tert-butoxide were placed in a 200 mL dry Schlenk bottle, placed in a glove box, and 80 mL of xylene was added with a syringe under an argon atmosphere to dissolve the mixture, and the mixture was mixed uniformly to obtain a mixture;

[0037] (2) The mixture was heated to 100°C and then heated under reflux for 12 h, then heated to 130°C and then heated under reflux for 36 h. After the reaction was completed, the mixture was cooled to room temperature;

[0038] (3) The solution after the reaction in step (2) was filtered under reduced pressure to obtain a solid crude product, which was washed (washed with toluene, deionized water, methanol, dichloromethane and acetone in sequence) and then vacuum dried (dried at 60°C for 12 hours) to obtain 232 mg of dark brown solid (yield 51.3%), which is a bipolar organic positive electrode material (polymer PQPZ).

[0039] Example 3

[0040] A bipolar organic cathode material, the specific preparation method is as follows:

[0041] (1) 366.01 mg of 2,7-dibromophenanthrene-9,10-dione, 145.78 mg of 5,10-dihydrophenazine, 9.33 mg of 2-dicyclohexylphosphino-2',6'-diisopropoxy-1,1'-biphenyl, 15.53 mg of chloro(2-dicyclohexylphosphino-2',6'-diisopropoxy-1,1'-biphenyl)(2-amino-1,1'-biphenyl-2-yl)palladium(II) and 288.3 mg of sodium tert-butoxide were placed in a 200 mL dry Schlenk bottle, placed in a glove box, and 40 mL of xylene was added with a syringe under an argon atmosphere to dissolve the mixture, and the mixture was mixed uniformly to obtain a mixture;

[0042] (2) The mixture was heated to 130°C and then heated under reflux for 36 h, then heated to 160°C and then heated under reflux for 60 h. After the reaction was completed, the mixture was cooled to room temperature;

[0043] (3) The solution after the reaction in step (2) was filtered under reduced pressure to obtain a solid crude product, which was washed (washed with toluene, deionized water, methanol, dichloromethane and acetone in sequence) and then vacuum dried (dried at 100°C for 36 hours) to obtain 232 mg of dark brown solid (yield 51.3%), which is a bipolar organic positive electrode material (polymer PQPZ).

[0044] Performance Testing

[0045] Figure 1 This is the infrared spectrum of the bipolar organic cathode material (polymer PQPZ) prepared in Example 1. Figure 1 It can be seen that the bipolar organic cathode material (polymer PQPZ) prepared in Example 1 has a peak at 1672 cm -1 and 1272cm -1 Characteristic peaks appear at , which are attributed to the vibration of the C=O group and the CN bond on the benzene ring, respectively, indicating that the bipolar organic cathode material (polymer PQPZ) was successfully prepared in Example 1.

[0046] Figure 2 This is a thermal field emission scanning electron microscope image of the bipolar organic cathode material (polymer PQPZ) prepared in Example 1. Figure 2 It can be observed that the bipolar organic cathode material (polymer PQPZ) prepared in Example 1 is a block aggregate with a particle size between 0.5 and 2 μm.

[0047] Figure 3 The X-ray diffraction pattern of the bipolar organic cathode material (polymer PQPZ) prepared in Example 1 is shown in FIG. Figure 3 It can be seen that the bipolar organic cathode material (polymer PQPZ) prepared in Example 1 has two broad diffraction peaks at 15° and 19°, indicating that the bipolar organic cathode material (polymer PQPZ) prepared in Example 1 exhibits an amorphous morphology.

[0048] The bipolar organic cathode material (polymer PQPZ) prepared in Example 1 was used as the cathode material (together with Ketjen black conductive agent and PVDF binder to form the cathode), metallic sodium was used as the anode material, and 1M NaPF6 in DIGLYME was used as the electrolyte to assemble into a button cell. The following performance tests were performed on the button cell:

[0049] Figure 4 The results of the cycle test of the button cell using the bipolar organic positive electrode material (polymer PQPZ) prepared in Example 1 as the positive electrode material are shown in FIG. Figure 4It can be seen that the bipolar organic cathode material (polymer PQPZ) electrode prepared in Example 1 has a discharge specific capacity of 270 mAh / g in the first cycle, which is close to the theoretical value. After 300 cycles, PQPZ still maintains a significant specific capacity of 243 mAh / g, with a retention rate of up to 90%.

[0050] Figure 5 The rate performance test results of the button cell test using the bipolar organic positive electrode material (polymer PQPZ) prepared in Example 1 as the positive electrode material are shown in FIG. Figure 5 It can be seen that the bipolar organic cathode material (polymer PQPZ) prepared in Example 1 has discharge capacities of 252 mAh / g, 216 mAh / g, 191 mAh / g, 179 mAh / g, 165 mAh / g, 152 mAh / g, and 146 mAh / g at 0.5C, 1C, 2C, 3C, 5C, 8C, and 10C, respectively (1C = 277 mA / g). When the current density is reduced to 0.5C, the discharge capacity reaches 220 mAh / g.

[0051] Figure 6 The cyclic voltammetry curve test results of the button cell test using the bipolar organic positive electrode material (polymer PQPZ) prepared in Example 1 as the positive electrode material. Figure 6 It can be seen that in the first cycle, at 1.0~4.0V(vs.Na + Four different reversible redox peaks were observed in the potential range of Na / Na, among which the first and second redox peaks were located at 1.6 / 2.1 V and 2.4 / 2.6 V, respectively, corresponding to Na + The third and fourth redox peaks, located at 2.93 / 3.06 V and 3.72 / 3.82 V, respectively, are associated with the anion insertion and extraction processes. The CV curves for the second to fourth cycles overlap well, demonstrating that the bipolar organic cathode material (polymer PQPZ) prepared in Example 1 possesses excellent redox stability and reversibility.

[0052] In summary, the present invention discloses a bipolar organic cathode material, the structural formula of which is Where n≥1. The bipolar organic cathode material of the present invention has both phenanthrenequinone and phenazine structures, both of which can be used as energy storage units, and has bipolar characteristics, and can store Na + With PF6 -Therefore, the bipolar organic cathode material of the present invention has excellent electrochemical properties. When used as the positive electrode of sodium ion batteries, it exhibits high specific capacity, stable cycling, and excellent rate performance (at a current density of 0.5C, the reversible specific capacity can reach 270mAh / g), showing broad application prospects. In addition, the preparation process of the bipolar organic cathode material of the present invention is simple and can be obtained through a single-step synthesis.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions, which should all be included in the scope of the claims of the present invention.

Claims

1. Bipolar organic cathode material, characterized in that The structural formula of the bipolar organic cathode material is as follows: Where n≥1.

2. The method for preparing the bipolar organic cathode material according to claim 1, characterized in that: The preparation method comprises the following steps: (1) placing 2,7-dibromophenanthrene-9,10-dione, 5,10-dihydrophenazine, 2-dicyclohexylphosphino-2',6'-diisopropoxy-1,1'-biphenyl, chloro(2-dicyclohexylphosphino-2',6'-diisopropoxy-1,1'-biphenyl)(2-amino-1,1'-biphenyl-2-yl)palladium(II) and sodium tert-butoxide in a glove box, adding xylene to dissolve the mixture under an argon atmosphere, and mixing the mixture to obtain a mixture; (2) heating the mixture to 100-130° C. and then heating under reflux for 12-36 hours, then heating to 130-160° C. and then heating under reflux for 36-60 hours, and cooling to room temperature after the reaction is completed; (3) The solution after the reaction in step (2) is filtered under reduced pressure to obtain a solid crude product, which is washed and then vacuum dried to obtain a dark brown solid, which is the bipolar organic positive electrode material.

3. The preparation method according to claim 2, characterized in that In step (1), the molar ratio of the 2,7-dibromophenanthrene-9,10-dione, 5,10-dihydrophenazine, 2-dicyclohexylphosphino-2',6'-diisopropoxy-1,1'-biphenyl, chloro(2-dicyclohexylphosphino-2',6'-di-isopropoxy-1,1'-biphenyl)(2-amino-1,1'-biphenyl-2-yl)palladium(II) and sodium tert-butoxide is 1:0.8-1.2:0.02-0.06:0.02-0.06:3.0-7.

0.

4. The preparation method according to claim 2, characterized in that In step (3), the washing is specifically: washing with toluene, deionized water, methanol, dichloromethane and acetone in sequence.

5. The preparation method according to claim 2, characterized in that In step (3), the vacuum drying is specifically: drying at 60-100° C. for 12-36 hours.

6. Use of the bipolar organic cathode material according to claim 1 in sodium ion batteries.

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