Bipolar organic positive electrode material and preparation method and application thereof

Abstract

The invention relates to a bipolar organic positive electrode material and a preparation method and application thereof, and belongs to the technical field of preparation of positive electrode materials. The structural formula of the bipolar organic positive electrode material is # imgabs0 #, wherein n is greater than or equal to 1. The bipolar organic positive electrode material simultaneously has phenanthrenequinone and phenazine structures, can be used as energy storage units, has the characteristic of bipolar, and can store Na < + > and PF6 <-> at the same time, so that the bipolar organic positive electrode material has good electrochemical performance, and can be used as a positive electrode of a sodium ion battery. The material shows high specific capacity, stable circulation and excellent rate capability, and has a wide application prospect. In addition, in the preparation process of the bipolar organic positive electrode material, the synthetic route is simple, and the bipolar organic positive electrode material can be obtained through one-step synthesis.

Description

Technical Field

[0001] The 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. Under this trend, sodium-ion batteries (SIBs) are expected to become a substitute and supplement for lithium-ion batteries and a new battery system for large-scale energy storage. Therefore, people are in urgent need of seeking and developing SIBs cathode materials with high specific capacity, stable cycle, high energy density and low cost.

[0003] The practical application of inorganic electrode materials is limited by the limited reserves of transition metals and the structural instability caused by the insertion and extraction 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 organic molecular structure is flexible, easy to regulate, and has the advantages of strong designability. However, most organic materials still have the problems of easy dissolution during circulation and low electronic conductivity, which hinders their practical application. Through molecular engineering design and optimization of molecular structure, it is expected to obtain high-energy density electrode materials, thereby preparing efficient sodium-ion batteries.

[0004] Organic electrode materials (OEM) are abundant, 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, accepting cations (Li + 、Na + or K + etc.) or anions (PF6 - 、ClO4 - or TFSI-, etc.). Therefore, their application can be extended from conventional rocking chair batteries to dual-ion batteries. On the other hand, bipolar materials can be used as cathode and anode of organic symmetric batteries at the same time, which can reduce material costs and simplify the battery manufacturing process. But in general, organic electrode materials still have the following disadvantages: the solubility of organic substances in the electrolyte during charging and discharging 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; the second object of the present invention is to provide a method for preparing a bipolar organic positive electrode material; the 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 positive electrode material, the structural formula of the bipolar organic positive electrode material 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 preparation method comprising the following steps:

[0012] (1) placing 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 in a glove box, adding xylene to dissolve under an argon atmosphere, and mixing to obtain a mixture;

[0013] (2) heating the mixture to 100-130° C. and then heating under reflux for 12-36 h, further heating the mixture to 130-160° C. and then heating under reflux for 36-60 h, and cooling the mixture 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 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 specifically comprises: 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 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 positive electrode 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 positive electrode material of the present invention has good electrochemical properties, and when used for the positive electrode of a sodium ion battery, it exhibits high specific capacity, stable cycle and excellent rate performance, and has broad application prospects. In addition, the preparation process of the bipolar organic positive electrode material of the present invention has a simple synthesis route and can be obtained by only one-step synthesis.

[0020] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can 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 in conjunction with the accompanying drawings, wherein:

[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 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 positive electrode material (polymer PQPZ) prepared in Example 1 as the positive electrode material;

[0026] Figure 5 The rate performance test results obtained by testing a button cell using the bipolar organic positive electrode material (polymer PQPZ) prepared in Example 1 as the positive electrode material;

[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 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 only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0029] Example 1

[0030] A bipolar organic positive electrode 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'-di-isopropoxy-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 by syringe under argon atmosphere to dissolve, and mixed to obtain a mixture;

[0032] (2) heating the mixture to 120° C. and refluxing for 24 h, then heating to 140° C. and refluxing for 48 h, and cooling to room temperature after the reaction;

[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 24h) to obtain 232mg of dark brown solid (yield 51.3%), which is a bipolar organic cathode material (polymer PQPZ).

[0034] Example 2

[0035] A bipolar organic positive electrode 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'-di-isopropoxy-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 by syringe under argon atmosphere to dissolve, and mixed to obtain a mixture;

[0037] (2) heating the mixture to 100° C. and refluxing for 12 h, then heating to 130° C. and refluxing for 36 h, and cooling to room temperature after the reaction;

[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 positive electrode 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'-di-isopropoxy-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, 40 mL of xylene was added with a syringe under an argon atmosphere to dissolve, and mixed to obtain a mixture;

[0042] (2) heating the mixture to 130° C. and then heating under reflux for 36 h, then heating to 160° C. and then heating under reflux for 60 h, and cooling to room temperature after the reaction;

[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 h) 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 is the X-ray diffraction pattern of the bipolar organic cathode material (polymer PQPZ) prepared in Example 1. 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 positive electrode material (polymer PQPZ) prepared in Example 1 was used as the positive electrode material (together with Ketjen black conductive agent and PVDF binder to form the positive electrode), metallic sodium was used as the negative electrode material, and 1M NaPF6 in DIGLYME was used as the electrolyte to assemble into a button cell, and the button cell was subjected to the following performance tests:

[0049] Figure 4 The following are the cycle test results of the button cell using the bipolar organic positive electrode material (polymer PQPZ) prepared in Example 1 as the positive electrode material. Figure 4It can be seen that the discharge specific capacity of the bipolar organic positive electrode material (polymer PQPZ) electrode prepared in Example 1 in the first cycle is 270 mAh / g, 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. Figure 5 It can be seen that the discharge capacities of the bipolar organic cathode material (polymer PQPZ) prepared in Example 1 at 0.5C, 1C, 2C, 3C, 5C, 8C and 10C are 252mAh / g, 216mAh / g, 191mAh / g, 179mAh / g, 165mAh / g, 152mAh / g, 146mAh / g (1C = 277mA / g), respectively. When the current density drops to 0.5C, the discharge specific capacity is 220mAh / 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 1.6 / 2.1 V and 2.4 / 2.6 V, corresponding to Na + The third and fourth redox peaks are located at 2.93 / 3.06V and 3.72 / 3.82V, respectively, belonging to the anion insertion and extraction process. The CV cycle curves from the second to the fourth cycle overlap well, indicating that the bipolar organic cathode material (polymer PQPZ) prepared in Example 1 has good 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 good electrochemical properties. When used for the positive electrode of a sodium ion battery, it exhibits high specific capacity, stable cycle and excellent rate performance (at a current density of 0.5C, the reversible specific capacity can reach 270mAh / g), 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 by only one-step synthesis.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. 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 solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. Bipolar organic cathode materials, It is 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, It is 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'-di-isopropoxy-1,1'-biphenyl)(2-amino-1,1'-biphenyl-2-yl)palladium(II) and sodium tert-butoxide in a glove box, adding xylene to dissolve under an argon atmosphere, and mixing to obtain a mixture; (2) heating the mixture to 100-130° C. and then heating under reflux for 12-36 h, further heating the mixture to 130-160° C. and then heating under reflux for 36-60 h, and cooling the mixture 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, It is 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, It is characterized in that In step (3), the washing specifically comprises: washing with toluene, deionized water, methanol, dichloromethane and acetone in sequence.

5. The preparation method according to claim 2, It is 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.

Images