阅读说明：本技术 聚[降冰片烯1,4-二甲基联萘醌]及制备方法和应用 (Poly [ norbornene 1, 4-dimethyl dinaphthoquinone ] and preparation method and application thereof ) 是由 杨继兴 石叶青 许运华 孙鹏飞 于 2019-09-23 设计创作，主要内容包括：本发明公开了聚[降冰片烯1,4-二甲基联萘醌]及制备方法和应用。制备过程包括：萘醌和四环庚烷在良溶剂中反应,反应结束后经浓缩、柱色谱分离、旋蒸、真空干燥,得到纯单体；单体溶解于良溶剂中,在催化剂作用下聚合,用乙烯基乙醚终止,用不良溶剂沉淀、洗涤、过滤、真空干燥,得到聚合物。该聚合物合成简便,原料易得,聚合效率高,聚合度分布窄。且该聚合物与石墨烯原位复合的电极应用于锂电池的正极材料,在较高的倍率2C(1C＝216.2mA/g)下,循环500圈后,容量保持率高达75.6％,稳定性大为提升；在电流密度从0.1C增加到2C时容量能保持80.4％,表现出优良的倍率性能。(The invention discloses poly [ norbornene 1, 4-dimethyl dinaphthoquinone ] and a preparation method and application thereof. The preparation process comprises the following steps: naphthoquinone and tetracycloheptane react in a good solvent, and after the reaction is finished, the pure monomer is obtained through concentration, column chromatographic separation, rotary evaporation and vacuum drying; dissolving the monomer in good solvent, polymerizing under the action of catalyst, terminating with vinyl ether, precipitating with poor solvent, washing, filtering, and vacuum drying to obtain the polymer. The polymer has the advantages of simple synthesis, easily obtained raw materials, high polymerization efficiency and narrow polymerization degree distribution. The polymer and graphene in-situ composite electrode is applied to a positive electrode material of a lithium battery, and after 500 cycles under high multiplying power of 2C (1C: 216.2mA/g), the capacity retention rate is up to 75.6%, and the stability is greatly improved; the capacity can be kept at 80.4% when the current density is increased from 0.1C to 2C, and excellent rate performance is shown.)

1. The structural formula of the poly [ norbornene 1, 4-dimethyl dinaphthoquinone ] is as follows:

wherein n is the degree of polymerization.

2. The poly [ norbornene 1, 4-dimethyldinaphthoquinone ] of claim 1]The method is characterized in that the monomer is norbornene 1, 4-dimethyl naphthoquinone, and the nuclear magnetic hydrogen spectrum of the monomer is characterized in that:¹H NMR(CDCl₃,298K)δ:8.09-8.86(m,2H),7.73-7.71(m,2H),6.29-6.02(s,2H),3.10-3.03(d,2H),2.90-2.94(d,2H),1.56-0.96(m,1H；m,1H)ppm。

3. a process for producing poly [ norbornene 1, 4-dimethyldinaphthoquinone ] according to claim 1; the method is characterized by comprising the following steps:

(1) synthesis of norbornene 1, 4-dimethyl naphthoquinone: in an inert atmosphere, naphthoquinone and tetracycloheptane react in a good solvent, and after the reaction is finished, the naphthoquinone and tetracycloheptane are concentrated, separated by column chromatography, evaporated in a rotary manner and dried in vacuum to obtain a pure monomer; wherein the feeding amount molar ratio of the naphthoquinone to the tetracycloheptane is 1: 1-1.5: 1;

(2) synthesis of poly [ norbornene 1, 4-dimethyl-dinaphthoquinone ]: dissolving the monomer in the step (1) in a good solvent under an inert atmosphere, and adding Grubbs third-generation catalyst dichloro [1, 3-bis (2,4, 6-trimethylphenyl) -2-imidazolidinylidene ] (benzylidene) bis (3-bromopyridine) ruthenium; the molar ratio of the monomer to the catalyst is 100: 1-200: 1; the polymerization was terminated with vinyl ether; precipitating with poor solvent, washing, filtering, and vacuum drying to obtain poly [ norbornene 1, 4-dimethyl-naphthoquinone ].

4. The method of claim 3, wherein the inert atmosphere is high purity nitrogen or argon 99.999%.

5. The method as set forth in claim 3, wherein in the step 1): the reaction temperature is 110-115 ℃, and the reaction time is 90 hours; the good solvent is toluene; the filler used for column chromatography is neutral alumina, and the eluent is petroleum ether and ethyl acetate in a volume ratio of 8: 1; the vacuum drying temperature is 50 ℃, and the drying time is 12 h.

6. The method as claimed in claim 3, wherein in said step 2): the good solvent is tetrahydrofuran, and the poor solvent is anhydrous methanol; the reaction temperature is 25 ℃, and the reaction time is 5 hours; the vacuum drying temperature is 50 ℃, and the drying time is 24 h.

7. A preparation method of a poly [ norbornene 1, 4-dimethyl dinaphthoquinone ]/graphene composite electrode; the method is characterized by comprising the following steps:

(1) in-situ compounding of poly [ norbornene 1, 4-dimethyldinaphthoquinone ] and graphene: dissolving the synthesized norbornene 1, 4-dimethyl naphthaquinone in a good solvent under an inert atmosphere, adding graphene into the solvent, performing ultrasonic treatment to uniformly disperse the graphene, and adding Grubbs third-generation catalyst dichloro [1, 3-bis (2,4, 6-trimethylphenyl) -2-imidazolidinylidene ] (benzylidene) bis (3-bromopyridine) ruthenium; the molar ratio of the monomer to the catalyst is 100: 1-200: 1; the mass ratio of the monomer to the graphene is 2: 1; the polymerization was terminated with vinyl ether; precipitating with a poor solvent, washing, filtering and drying in vacuum to obtain a poly [ norbornene 1, 4-dimethyl dinaphthoquinone ]/graphene compound;

(2) preparing a poly [ norbornene 1, 4-dimethyl dinaphthoquinone ]/graphene composite electrode material: uniformly grinding the poly [ norbornene 1, 4-dimethyl dinaphthoquinone ]/graphene compound in the step (1), then adding a binder solution, uniformly grinding and mixing, blade-coating the slurry on an aluminum foil, drying at room temperature, rolling into a circular positive plate, and carrying out vacuum drying on the electrode plate; wherein the mass ratio of the composite to the binder is 9: 1.

8. The method as claimed in claim 7, wherein in the step 1): the good solvent is tetrahydrofuran, and the poor solvent is anhydrous methanol; the reaction temperature is 25 ℃, and the reaction time is 5 hours; thickness of graphene used: 0.55-3.74 nm, diameter: 0.5-3 μm, and the number of layers is less than 10; the ultrasonic time is 30min, and the power is 1000W; the vacuum drying temperature is 50 ℃, and the drying time is 24 h.

9. The method as claimed in claim 7, wherein in said step 2): the adhesive solution is a sodium alginate aqueous solution with the concentration of 15g/mL, the blade coating thickness of the slurry is 10 mu m, and the diameter of the circular positive plate is 9 mm; the drying temperature is 100 ℃, and the drying time is 5 h.

Technical Field

The invention belongs to the technical field of organic carbonyl electrode materials, and particularly relates to poly [ norbornene 1, 4-dimethyl dinaphthoquinone ], a preparation method thereof and application thereof as an electrode material.

Background

Lithium Ion Batteries (LIBs) have enjoyed great success in portable electronic products due to their advantages of high energy density, high voltage and long cycle life, becoming the first choice candidates for Electric Vehicle (EV) batteries, and LIBs are also being considered for smart grid storage applications. Therefore, development of low-cost, high-specific energy and high-safety LIBs is a must path to meet market demand. Meanwhile, the large-scale application of LIBs raises concerns about resources and environmental issues. LiCoO is mainly used in the existing LIBs₂、LiFePO₄And nickel-cobalt-manganese ternary materials, etc., the element storage capacity is very limited and too expensive. In addition, the conventional inorganic compounds are limited in safety and environmental protection, and may not provide a high-quality rechargeable battery for more application fields at low cost.

Organic electrode materials are considered as candidate materials for next-generation energy storage systems due to their sustainability, flexibility and the like, and have the advantages of structural designability, oxidation-reduction potential adjustability, multi-electron reaction characteristics and the like. However, organic small molecule materials dissolve severely in organic electrolytes as redox active electrodes of batteries, causing their actual capacity to be much smaller than their theoretical value and decay rapidly. Common organic carbonyl micromolecules such as benzoquinone, naphthoquinone and the like have very poor cycle life, slow reaction kinetics and low charge-discharge efficiency, and data show that the charge-discharge efficiency is almost 0 after the organic carbonyl micromolecules are cycled for about 50 times. Most of the derivatives based on benzoquinone and naphthoquinone reported at present are difficult to synthesize, the reduction of platform voltage causes great capacity reduction, and polymerization is difficult to control due to the high activity characteristic of quinone micromolecules, so that active polymerization cannot be realized, and the size of molecular weight cannot be effectively controlled. If the molecular weight is too small, the solubility cannot be suppressed, and if the molecular weight is too large, the conductivity of the material is lowered.

Disclosure of Invention

In order to solve the problems, by means of molecular structure design, a norbornene structure is introduced into a naphthoquinone structure, the solubility of naphthoquinone can be reduced by expanding the molecular structure and enhancing conjugation, the naphthoquinone structure almost reaches the theoretical capacity, the capacity is kept at 75.6% after circulation for 500 times, the platform voltage is maintained at about 2.5-2.7V, and the capacity and the voltage are not greatly reduced. Meanwhile, the four-membered ring structure between the norbornene and the naphthoquinone can promote in-situ ring-opening metathesis active polymerization, the polymerization efficiency reaches 100%, the polymerization degree distribution is about 1.2, the size of the polymerization degree is effectively controlled, the oligomer with the molecular weight of about 20000 is prepared, and the influence distribution of the molecular weight on the solubility and the conductivity is effectively balanced; and the presence of chain entanglement in the polymer further reduces the solubility of the compound; and further adopting in-situ polymerization to fully combine the conductive agent and the active substance, and preparing the uniform poly [ norbornene 1, 4-dimethyldinaphthoquinone ]/graphene composite electrode, wherein the composite electrode material as a positive electrode material of a lithium metal battery (half battery) shows high stability and high-rate electrochemical characteristics.

The technical scheme of the invention is as follows:

the structural formula of the poly [ norbornene 1, 4-dimethyl dinaphthoquinone ] is as follows:

wherein n is the degree of polymerization;

monomeric nuclear magnetic hydrogen spectrum characterization of polymer I:¹H NMR(CDCl₃,298K)δ：8.09-8.86(m,2H),7.73-7.71(m,2H),6.29-6.02(s,2H),3.10-3.03(d,2H),2.90-2.94(d,2H),1.56-0.96(m,1H；m,1H)ppm。

the invention relates to a preparation method of poly [ norbornene 1, 4-dimethyl dinaphthoquinone ]; the method comprises the following steps:

(1) synthesis of norbornene 1, 4-dimethyl-dinaphthoquinone: in an inert atmosphere, naphthoquinone and tetracycloheptane react in a good solvent, and after the reaction is finished, the naphthoquinone and tetracycloheptane are concentrated, separated by column chromatography, evaporated in a rotary manner and dried in vacuum to obtain a pure monomer; wherein the feeding amount molar ratio of the naphthoquinone to the tetracycloheptane is 1: 1-1.5: 1;

(2) synthesis of poly [ norbornene 1, 4-dimethyl-dinaphthoquinone ]: dissolving the monomer in the step (1) in a good solvent under an inert atmosphere, and adding Grubbs third-generation catalyst dichloro [1, 3-bis (2,4, 6-trimethylphenyl) -2-imidazolidinylidene ] (benzylidene) bis (3-bromopyridine) ruthenium; the molar ratio of the monomer to the catalyst is 100: 1-200: 1; the polymerization was terminated with vinyl ether; precipitating with poor solvent, washing, filtering, and vacuum drying to obtain poly [ norbornene 1, 4-dimethyl-naphthoquinone ];

the reaction equation is as follows:

the inert atmosphere is high-purity nitrogen or high-purity argon 99.999%.

The reaction temperature in the step 1) is 110-115 ℃, and the reaction time is 90 h.

The good solvent used in the step 1) is toluene.

The filler used in the step 1) for column chromatography is neutral alumina, and the eluent used is petroleum ether and ethyl acetate in a volume ratio of 8: 1.

The vacuum drying temperature in the step 1) is 50 ℃, and the drying time is 12 h.

The good solvent used in the step 2) is tetrahydrofuran; the poor solvent is anhydrous methanol.

The reaction temperature in the step 2) is 25 ℃, and the reaction time is 5 h.

The vacuum drying temperature in the step 2) is 50 ℃, and the drying time is 24 h.

The prepared poly [ norbornene 1, 4-dimethyldinaphthoquinone ] and graphene are compounded in situ to prepare the poly [ norbornene 1, 4-dimethyldinaphthoquinone ]/graphene composite electrode material; the method comprises the following steps:

(1) in-situ compounding of poly [ norbornene 1, 4-dimethyldinaphthoquinone ] and graphene: dissolving the synthesized norbornene 1, 4-dimethyl dinaphthoquinone in a good solvent under an inert atmosphere, adding graphene into the solvent, performing ultrasonic treatment to uniformly disperse the graphene, and adding Grubbs third-generation catalyst dichloro [1, 3-bis (2,4, 6-trimethylphenyl) -2-imidazolidinylidene ] (benzylidene) bis (3-bromopyridine) ruthenium; the molar ratio of the monomer to the catalyst is 100: 1-200: 1; the mass ratio of the monomer to the graphene is 2: 1; (ii) a The polymerization was terminated with vinyl ether; precipitating with a poor solvent, washing, filtering and drying in vacuum to obtain a poly [ norbornene 1, 4-dimethyl dinaphthoquinone ]/graphene compound;

(2) preparing a poly [ norbornene 1, 4-dimethyl dinaphthoquinone ]/graphene composite electrode material: uniformly grinding the poly [ norbornene 1, 4-dimethyl dinaphthoquinone ]/graphene compound in the step (1), then adding a binder solution, uniformly grinding and mixing, blade-coating the slurry on an aluminum foil, drying at room temperature, rolling into a circular positive plate, and carrying out vacuum drying on the electrode plate; wherein the mass ratio of the composite to the binder is 9: 1.

The inert atmosphere is high-purity nitrogen or high-purity argon 99.999%.

The good solvent used in the step 1) is tetrahydrofuran; the poor solvent is anhydrous methanol.

The reaction temperature in the step 1) is 25 ℃, and the reaction time is 5 h.

The graphene in the step 1) has a thickness: 0.55-3.74 nm, diameter: 0.5-3 μm, and the number of layers is less than 10.

The ultrasonic time in the step 1) is 30min, and the power is 1000W.

The vacuum drying temperature in the step 1) is 50 ℃, and the drying time is 24 h.

The binder solution in the step 2) is 15g/mL sodium alginate aqueous solution, the slurry is coated with 10 μm in blade coating thickness, the diameter of the round positive plate is 9mm, the drying temperature is 100 ℃, and the drying time is 5 hours.

The assembly and test conditions of the button cell for testing the electrode material in the invention are as follows: the battery is assembled in a glove box filled with argon, wherein the water and oxygen contents are lower than 0.1 ppm; the button cell is CR2032, a lithium metal sheet is adopted as a negative electrode, a diaphragm is Celgard 2025 of polyolefin, and an electrolyte used is 2M 1, 3-Dioxolane (DOL)/ethylene glycol dimethyl ether (DME) (1/1, v/v) solvent of bis (trifluoromethane) sulfimide Lithium (LiTFSI); the electrochemical performance test is carried out in a Land 2001A battery test system, and the test voltage window is 1.5-3.5V; the test comprises the cycle performance test of the poly [ norbornene 1, 4-dimethyl dinaphthoquinone ]/graphene composite electrode material under the current density of 0.1C; testing the multiplying power performance of the poly [ norbornene 1, 4-dimethyl dinaphthoquinone ]/graphene composite electrode material under the current densities of 0.1C,0.3C,0.5C,0.7C,1.0C and 2.0C; and testing the long-cycle stability of the poly [ norbornene 1, 4-dimethyl dinaphthoquinone ]/graphene composite electrode material under a higher current density of 2C.

The effects of the present invention are explained as follows:

the invention relates to a preparation method of poly [ norbornene 1, 4-dimethyl dinaphthoquinone ] and an application of the poly [ norbornene 1, 4-dimethyl dinaphthoquinone ] as an electrode material. The poly [ norbornene 1, 4-dimethyl dinaphthoquinone ] is simple and convenient to synthesize, and the raw materials are cheap and easy to obtain; the ring-opening metathesis active polymerization can be realized, the polymerization efficiency reaches 100%, the polymerization degree distribution is about 1.2, and the size of the polymerization degree is effectively controlled, so that the oligomer with the molecular weight of about 20000 is prepared; in addition, the poly [ norbornene 1, 4-dimethylnaphthoquinone ]/graphene composite electrode material is successfully prepared, the preparation process is simple, the cost is low, the uniformity of the obtained electrode material is good, the influence of the molecular weight on the solubility and the conductivity is effectively balanced when the material is used as the positive electrode of the lithium ion battery, the theoretical capacity of the material is almost reached, the capacity attenuation is small after the 2C (1C: 216.2mA/g) is cycled for 500 times under high current density, the platform voltage is maintained to be about 2.5-2.7V, and the capacity and the voltage are not greatly reduced. The battery test results show that: (1) the electrochemical performance of the poly [ norbornene 1, 4-dimethyl dinaphthoquinone ]/graphene composite electrode material is superior to that of a common small-molecular carbonyl compound electrode material; (2) under the condition of higher multiplying power (2C), after 500 cycles, the poly [ norbornene 1, 4-dimethyl dinaphthoquinone ]/graphene composite electrode material has the capacity retention rate as high as 75.6%, and the stability is greatly improved; (3) the poly [ norbornene 1, 4-dimethyl dinaphthoquinone ]/graphene composite electrode material can keep 80.4% of capacity when the current density is increased from 0.1C to 2C, and shows excellent rate performance. Therefore, compared with the traditional inorganic metal compound electrode material and the common quinone polymer organic electrode material, the composite electrode material has the advantages of simple preparation and good cycle performance and rate performance; the composite electrode material greatly inhibits the dissolution of naphthoquinone, has high capacity and voltage, and is expected to be used as a cathode material of a next-generation organic battery.

Drawings

FIG. 1 is a nuclear magnetic hydrogen spectrum of norbornene 1, 4-dimethyldinaphthoquinone synthesized in example 1;

FIG. 2 is a nuclear magnetic hydrogen spectrum comparison graph of poly [ norbornene 1, 4-dimethylbinaphthoquinone ] and norbornene 1, 4-dimethylbinaphthoquinone synthesized in example 1;

FIG. 3(a) is an SEM photograph of a poly [ norbornene 1, 4-dimethyldinaphthoquinone ]/graphene composite electrode prepared in example 1;

FIG. 3(b) is an SEM photograph of the poly [ norbornene 1, 4-dimethyldinaphthoquinone ]/graphene composite electrode prepared in example 2;

FIG. 4 is a graph of the cycling performance at 0.1C of the poly [ norbornene 1, 4-dimethyldinaphthoquinone ]/graphene composite electrode material prepared in example 1;

FIG. 5 is a graph of rate capability of the poly [ norbornene 1, 4-dimethyldinaphthoquinone ]/graphene composite electrode material prepared in example 1;

FIG. 6 is a graph of the long cycle performance at 2C of the poly [ norbornene 1, 4-dimethyldinaphthoquinone ]/graphene composite electrode material prepared in example 1.

Detailed Description

The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. It should be understood that various changes and modifications can be made by those skilled in the art after reading the teachings herein, and such equivalents also fall within the scope of the invention as defined by the appended claims.