阅读说明：本技术 一种钼酸锰纳米花/石墨烯三维结构及高比容超级电容器性能提升方法 (Manganese molybdate nanoflower/graphene three-dimensional structure and high-specific-volume supercapacitor performance improvement method ) 是由 孙嬿 李春生 朱珠 毛子旺 殷公社 杨晨 王笛笛 曾康钰 陈嘉巧 于 2021-02-19 设计创作，主要内容包括：本发明专利提供了一种钼酸锰纳米花/石墨烯三维结构及高比容超级电容器性能提升方法,以石墨烯、50wt％硝酸锰水溶液及钼酸铵为反应原料,蒸馏水为溶剂,三己基十四烷基氯化膦离子液体为结构导向剂；利用常压微波辐射技术制备钼酸锰纳米花/石墨烯三维复合材料(MnMoO-4/GN)。本专利的创新点在于：经过微波辐射处理后的石墨烯为单分散的纳米片,其表面官能团减少,利于钼酸锰小尺寸材料的可控生长；所得产物的X射线衍射图(XRD)、扫描电子显微镜图(SEM)、透射电子显微镜图(TEM)分析结果均充分表明本发明专利所述方法能够得到复合程度好、结晶度高、形貌规整的钼酸锰纳米花/石墨烯三维复合材料,是一种具有优良电化学性能的超级电容器电极材料。(The invention provides a method for improving the performance of a manganese molybdate nanoflower/graphene three-dimensional structure and a high specific volume supercapacitor, which takes graphene, 50 wt% of manganese nitrate aqueous solution and ammonium molybdate as reaction raw materials, distilled water as a solvent and trihexyltetradecyl phosphine chloride ionic liquid as a structure directing agent; by using normal pressure microwave radiation technologyPreparation of manganese molybdate nanoflower/graphene three-dimensional composite material (MnMoO) 4 GN). The innovation point of this patent lies in: the graphene subjected to microwave radiation treatment is a monodisperse nanosheet, the surface functional groups of the nanosheet are reduced, and controllable growth of the manganese molybdate small-size material is facilitated; the analysis results of an X-ray diffraction pattern (XRD), a Scanning Electron Microscope (SEM) and a Transmission Electron Microscope (TEM) of the obtained product fully show that the manganese molybdate nanoflower/graphene three-dimensional composite material with good composite degree, high crystallinity and regular morphology can be obtained by the method disclosed by the invention, and the manganese molybdate nanoflower/graphene three-dimensional composite material is a supercapacitor electrode material with excellent electrochemical performance.)

1. The invention provides a method for improving the performance of a manganese molybdate nanoflower/graphene three-dimensional structure and a high-specific-volume supercapacitor, which respectively takes graphene, a 50 wt% manganese nitrate aqueous solution and ammonium molybdate as reaction raw materials and distilled water as a solvent; ionic liquid: trihexyltetradecylphosphine chloride, CAS No.: 258864-54-9, molecular formula isIs a structure directing agent; pure-phase MnMoO prepared by using ionic liquid structure directing agent assisted microwave radiation method₄The specific synthesis steps of the nano flower/graphene composite electrode material are as follows:

firstly, taking 0.0010-10.0000 g of graphene powder sold by aladdin company, wherein the product number is 12011201, and the specific surface area is 750m²(ii)/g; placing the graphene powder in a 25-250 mL quartz round-bottom flask, then adding 10-100 mL distilled water, and fully stirring for 3-5 min to obtain a mixed suspension; then transferring the quartz round-bottom flask into a normal-pressure microwave reactor with a reflux device, wherein the model is improved American PJ21C-AU, the frequency is 2450MHz, the power is 200-1400W, the mixed suspension is continuously heated for 1-10 h at 70-100 ℃, the normal reflux ensures that the reaction volume is kept consistent in the reaction process, and finally black graphene slurry is obtained; SEM test shows that the material is a lamellar network interconnection structure with the thickness of 25 nm;

secondly, naturally cooling the black graphene slurry obtained in the first step to room temperature, adding 5.0000-15.0000 g of analytically pure ammonium molybdate white powder into the black graphene slurry, and stirring for 0.5-3.0 h to obtain a uniform suspension for later use;

thirdly, under the condition of strong stirring, adding 10-150 mL of distilled water into 5-30 mL of 50 wt% manganese nitrate aqueous solution, and fully stirring for 0.5-1.5 h, wherein the density is 1.5126 g/mL; adding 0.0010-10.0000 g of a structure directing agent of trihexyltetradecyl phosphonium chloride into the solution, and stirring for 0.5-1.5 h to obtain a uniform solution;

fourthly, adding the uniform solution obtained in the third step into the uniform suspension obtained in the second step, placing the uniform suspension into a quartz round-bottom flask, then transferring the uniform suspension into the normal-pressure microwave reactor in the first step, wherein the frequency is 2450MHz, the power is 200-1400W, and continuously reacting for 1-10 hours at the temperature of 70-100 ℃;

fifthly, naturally cooling the product obtained in the fourth step to room temperature, centrifuging for 1-3 min in a high-speed centrifuge with the speed of 5000-10000 r/min, and washing with distilled water3-5 times, drying the washed product in a drying oven at 50-80 ℃ for 5-20 hours to obtain pure-phase MnMoO₄A nanoflower/graphene composite electrode material; the XRD, SEM and TEM analysis results of the sample all prove that the MnMoO is pure-phase MnMoO for the supercapacitor₄The nanoflower/graphene three-dimensional electrode material has a good energy storage effect in a super capacitor.

[ technical field ]: the invention discloses a target product mainly applied to the field of energy storage materials, and particularly relates to a method for improving the performance of a manganese molybdate nanoflower/graphene three-dimensional structure and a high-specific-volume supercapacitor.

[ technical background ]: aiming at the characteristics of periodicity and instability of clean energy such as solar energy, tidal energy, wind energy and the like, the development of high-performance energy storage equipment can promote the human society to make full use of the clean energy, so that the outstanding problems of excessive consumption of petrochemical resources, further deterioration of ecological environment and the like can be relieved. Supercapacitors have been widely used in various fields such as electric cars, wearable devices, buses, tracks, etc. due to the characteristics of high power density, fast charging speed, long cycle life, wide operating temperature range, high safety factor, etc. (Binoy K. Saikia, Santhi Maria Benoy, Mousumi Bora, et al. A. brity review on super capacitor Energy storage and utilization of natural carbon resources as the same electronic materials [ J ]. Fuel cells.2020, 282: 118796; Ander Gonz lez, Eider Goikole, Jon Andoni Barrena, et al. review subcaparators: Technologies and materials [ J ]. rechargeable state and 1189: 1189).

The manganese molybdate being a molybdateA significant branch; molybdenum and manganese elements can respectively provide excellent redox activity and conductivity, the internal synergistic effect of the molybdenum and the manganese elements enables the material to have better electrochemical performance than a single metal oxide, and the material is one of common electrode materials of a super capacitor (Yang Lu, Menglong ZHao, Rongjie Luo, et al₄ nanotubes as high-performance electrodes for asymmetric supercapacitors[J]Journal of Solid State electrochemistry.2017, 22 (3): 657-666). At present, manganese molybdate serving as an electrode material of a super capacitor has the main problems of low actual specific capacitance and unsatisfactory rate performance; therefore, finding a suitable way to manipulate the material structure to improve the electrochemical performance of manganese molybdate is the basis for its commercial application.

The manganese molybdate is compounded with other materials and is one of effective ways for improving the electrochemical performance of the manganese molybdate. The graphene is a novel sp2 hybridized carbon material and has excellent chemical stability, electronic conductivity, toughness and mechanical strength; after the graphene material is compounded with manganese molybdate, the electron and ion conduction dynamics can be effectively optimized, and the specific capacitance and rate performance of the manganese molybdate can be further improved (Huaixin Wei, Jun Yang, Yufei Zhang, et al₄ hollow spheres as long-life and high-rate anodes for lithium-ion batteries[J].Journal of Colloid and Interface Science.2018，524：256-262.)。

The invention provides a method for improving the performance of a manganese molybdate nanoflower/graphene three-dimensional structure and a high specific volume supercapacitor, which comprises the steps of firstly carrying out microwave treatment on graphene with a high specific surface area, wherein the treated graphene is a monodisperse nanosheet, so that surface functional groups are reduced, and the controllable growth of active substances is facilitated; then, the manganese molybdate nano flower/graphene three-dimensional composite material (MnMoO) is prepared by using ammonium molybdate and manganese nitrate as a molybdenum source and a manganese source respectively, using distilled water as a solvent and using trihexyltetradecyl phosphine chloride as a structure directing agent through a microwave radiation technology₄GN). The small particle size of the obtained product can be seen through an X-ray diffraction pattern (XRD pattern), a scanning electron microscope pattern (SEM pattern) and a transmission electron microscope pattern (TEM pattern) of the target product,The dispersion degree is good, the appearance is regular, and the MnMoO related to the invention patent is fully proved₄The synthesis method of the/GN composite material can prepare high-quality target products and has scientificity, practicability and novelty.

[ summary of the invention ]: the main contents of the patent of the invention are respectively as follows: (1) firstly, a graphene reaction raw material is pretreated by utilizing a microwave radiation technology, the obtained graphene is a monodisperse nanosheet, surface functional groups are reduced, and controllable growth of an inorganic material is facilitated; (2) the electrochemical performance of the graphene and manganese molybdate material can be effectively improved under the internal synergistic effect of the graphene and manganese molybdate material, so that the specific volume and rate performance of the supercapacitor are improved; (3) the strong vibration of polar molecules and ions in the microwave irradiation process enables reactants to be heated uniformly inside and outside, and the reaction efficiency is effectively improved; (4) from the perspective of environmental protection, the microwave irradiation technology does not generate harmful waste in the whole process of preparing materials, has high reaction rate and strong controllability on the size and the shape of products, and provides a feasible technical route for the preparation of other materials.

[ technical solution of the present invention ]: the invention provides a method for improving the performance of a manganese molybdate nanoflower/graphene three-dimensional structure and a high specific volume supercapacitor, which respectively takes graphene, 50 wt% of manganese nitrate aqueous solution and ammonium molybdate as reaction raw materials, distilled water as a solvent, trihexyltetradecyl phosphine chloride, CAS number: 258864-54-9, molecular formula isIs a structure directing agent; pure-phase MnMoO prepared by using ionic liquid structure directing agent assisted microwave radiation method₄The specific synthesis steps of the nano flower/graphene composite electrode material are as follows:

firstly, taking 0.0010-10.0000 g of graphene powder sold by aladdin company, wherein the product number is 12011201, and the specific surface area is 750m²(ii)/g; placing the graphene powder in a 25-250 mL quartz round-bottom flask, then adding 10-100 mL distilled water, and fully stirring for 3-5 min to obtain a mixed suspension; the quartz round bottom flask was then transferred to an atmospheric microwave reactor with reflux unit, model modifiedPJ21C-AU, the frequency is 2450MHz, the power is 200-1400W, the mixed suspension is continuously heated for 1-10 h at 70-100 ℃, the reaction volume is normally kept consistent by refluxing in the reaction process, and finally black graphene slurry is obtained; SEM test shows that the material is a lamellar network interconnection structure with the thickness of 25 nm;

secondly, naturally cooling the black graphene slurry obtained in the first step to room temperature, adding 5.0000-15.0000 g of ammonium molybdate into the black graphene slurry, and stirring for 0.5-3.0 h to obtain a uniform suspension for later use;

thirdly, under the condition of strong stirring, adding 10-150 mL of distilled water into 5-30 mL of 50 wt% manganese nitrate aqueous solution, and fully stirring for 0.5-1.5 h, wherein the density is 1.5126 g/mL; adding 0.0010-10.0000 g of a structure directing agent of trihexyltetradecyl phosphonium chloride into the solution, and stirring for 0.5-1.5 h to obtain a uniform solution;

fourthly, adding the uniform solution obtained in the third step into the uniform suspension obtained in the second step, placing the uniform suspension into a quartz round-bottom flask, then transferring the uniform suspension into the normal-pressure microwave reactor in the first step, wherein the frequency is 2450MHz, the power is 200-1400W, and continuously reacting for 1-10 hours at the temperature of 70-100 ℃;

fifthly, naturally cooling the product obtained in the fourth step to room temperature, centrifuging the product in a high-speed centrifuge with the speed of 5000-10000 r/min for 1-3 min, washing the product with distilled water for 3-5 times, and drying the washed product in an oven with the temperature of 50-80 ℃ for 5-20 h to obtain pure-phase MnMoO₄A nanoflower/graphene composite electrode material; the XRD, SEM and TEM analysis results of the sample all prove that the MnMoO is pure-phase MnMoO for the supercapacitor₄The nanometer flower/graphene three-dimensional electrode material.

[ advantages and effects of the invention ]: the invention relates to a method for improving the performance of a manganese molybdate nanoflower/graphene three-dimensional structure and a high-specific-volume supercapacitor, which has the following advantages: (1) the molybdenum in the earth crust has rich reserves, wider distribution and low price, and can be used as an electrode material of a super capacitor; (2) the graphene reaction raw material is pretreated by a microwave radiation technology, the obtained graphene is a monodisperse nanosheet, surface functional groups are reduced, controllable growth of a composite material is facilitated, and therefore the composite uniformity of a product is improved; (3) the manganese molybdate nanoflower/graphene three-dimensional composite material is prepared by combining a microwave radiation method, reactants are heated inside and outside simultaneously and are heated uniformly, the reaction is full, and the efficiency is improved; (4) the method for preparing the manganese molybdate nanoflower/graphene three-dimensional composite material can obtain a target product with high crystallinity, good dispersity and regular morphology, and provides guidance for synthesis of other materials.

Drawings

FIG. 1 is MnMoO₄Scanning Electron Microscope (SEM) image of black graphene paste of nanoflower/graphene three-dimensional electrode material sample 1

FIG. 2 shows MnMoO₄Low-magnification SEM image of nanoflower/graphene three-dimensional electrode material sample 1

FIG. 3 is MnMoO₄High-power SEM image of nanoflower/graphene three-dimensional electrode material sample 1

FIG. 4 is MnMoO₄Transmission Electron Microscope (TEM) image of nanoflower/graphene three-dimensional electrode material sample

Detailed Description

The following embodiments and effects of the present invention are further described with reference to the following examples:

EXAMPLE 1 preparation of MnMoO₄Nanoflower/graphene three-dimensional electrode material sample 1

First, 5.8162g of graphene powder sold by the company aladdin, having a cat number of 12011201 and a specific surface area of 750m was taken²(ii)/g; placing the graphene powder in a 50mL quartz round-bottom flask, then adding 25mL distilled water, and fully stirring for 5min to obtain a mixed suspension; then transferring the quartz round-bottom flask into a normal-pressure microwave reactor with a reflux device, wherein the model is improved American PJ21C-AU, the frequency is 2450MHz, the power is 1000W, continuously heating the mixed suspension at 100 ℃ for 2h, refluxing in the reaction process to normally ensure that the reaction volume is kept consistent, and finally obtaining black graphene slurry; SEM test shows that the material is a lamellar network interconnection structure with the thickness of 25nm (shown in figure 1); secondly, naturally cooling the black graphene slurry obtained in the first step to room temperature, and adding 10.5920g of molybdenum into the black graphene slurryStirring ammonium for 1h to obtain a uniform suspension for later use; under the condition of intense stirring, adding 60mL of distilled water into 14.2mL of 50 wt% manganese nitrate aqueous solution, and fully stirring for 0.5h, wherein the density is 1.5126 g/mL; 2.5000g of a structure directing agent of trihexyltetradecylphosphine chloride is added into the solution, and the solution is stirred for 1 hour to obtain a uniform solution; then adding the uniform solution obtained in the third step into the uniform suspension obtained in the second step, placing the uniform suspension into a quartz round-bottom flask, then transferring the uniform suspension into the normal-pressure microwave reactor in the first step, wherein the frequency is 2450MHz, the power is 1000W, and continuously reacting for 2 hours at 100 ℃; finally, naturally cooling the product obtained in the fourth step to room temperature, centrifuging for 1min in a high-speed centrifuge with 9000r/min, washing for 3 times by using distilled water, and drying the washed product in an oven at 60 ℃ for 10h to obtain pure-phase MnMoO₄A nanoflower/graphene composite electrode material; the standard card number corresponding to the XRD pattern of the product is JCPDS 50-1284, the spectrogram has no impurity peak, the peak appearance is corresponding well, and the phase is high purity; FIGS. 2 to 3 are SEM images of three-dimensional composite electrode materials: in the figure, the nanometer flower-shaped manganese molybdate material is embedded on a graphene sheet layer network interconnection structure and is uniformly distributed; manganese molybdate high-magnification Transmission Electron Microscopy (TEM) shows that: the lattice fringes of the manganese molybdate material are clear, and the crystal face index of XRD corresponding to the horizontal plane of the nanosheet is (-101); further proving the experimental conclusion that XRD is a high-purity phase; the single nanosheet display material of the TEM has high crystallinity, small particle size and regular morphology. Experimental tests show that: by adopting the technical route, high-purity MnMoO can be obtained₄The nanoflower/graphene three-dimensional electrode material is a super capacitor electrode material with excellent electrochemical performance.

Comparative example 1: publication No. CN 107459063B (publication No. 2019.10.29) provides a preparation method:

(1) dissolving manganese acetate tetrahydrate with the concentration of 0.05-1 mol/L in ethanol or ethylene glycol under stirring to obtain a mixed solution A;

(2) dissolving sodium molybdate dihydrate with the concentration of 0.05-1 mol/L in ethanol or ethylene glycol under stirring to obtain a mixed solution B;

(3) mixing and stirring the mixed solution A and the mixed solution B according to the volume ratio of 1: 1-2 for 15 minutes, transferring the mixed solution A and the mixed solution B into a reaction kettle, and sealing the reaction kettle; fully reacting at 120-180 ℃ for 3 hours, and then performing suction filtration, washing and drying on the mixture;

(4) calcining the product obtained in the step (3) at the temperature of 400-700 ℃, wherein the calcining time is 4-6 hours, and cooling to room temperature to obtain a manganese molybdate micro-nano material;

the method is characterized in that the prepared manganese molybdate micro-nano material is in a silkworm cocoon shape and mainly comprises small nano particles and filamentous manganese molybdate, and the discharge specific capacity is 942.2mAh g^-1The charging specific capacity is 710.9mAh g^-1。

The invention discloses a method for improving the performance of a manganese molybdate nanoflower/graphene three-dimensional structure and a high-specific-volume supercapacitor. As in example 1: EXAMPLE 1 preparation of MnMoO₄Nanometer flower/graphene three-dimensional electrode material sample 1. First, 5.8162g of graphene powder sold by the company aladdin, having a cat number of 12011201 and a specific surface area of 750m was taken²(ii)/g; placing the graphene powder in a 50mL quartz round-bottom flask, then adding 25mL distilled water, and fully stirring for 5min to obtain a mixed suspension; then transferring the quartz round-bottom flask into a normal-pressure microwave reactor with a reflux device, wherein the model is improved American PJ21C-AU, the frequency is 2450MHz, the power is 1000W, continuously heating the mixed suspension at 100 ℃ for 2h, refluxing in the reaction process to normally ensure that the reaction volume is kept consistent, and finally obtaining black graphene slurry; SEM test shows that the material is a lamellar network interconnection structure with the thickness of 25nm (shown in figure 1); secondly, naturally cooling the black graphene slurry obtained in the first step to room temperature, adding 10.5920g of ammonium molybdate into the black graphene slurry, and stirring for 1h to obtain a uniform suspension for later use; under the condition of intense stirring, adding 60mL of distilled water into 14.2mL of 50 wt% manganese nitrate aqueous solution, and fully stirring for 0.5h, wherein the density is 1.5126 g/mL; 2.5000g of a structure directing agent of trihexyltetradecylphosphine chloride is added into the solution, and the solution is stirred for 1 hour to obtain a uniform solution; adding the homogeneous solution obtained in the third step into the homogeneous suspension obtained in the second step, placing the homogeneous suspension in a quartz round-bottom flask, and transferring the round-bottom flask to the atmospheric pressure microwave reactor in the first stepThe reaction rate is 2450MHz, the power is 1000W, and the reaction lasts for 2h at 100 ℃; finally, naturally cooling the product obtained in the fourth step to room temperature, centrifuging for 1min in a high-speed centrifuge with 9000r/min, washing for 3 times by using distilled water, and drying the washed product in an oven at 60 ℃ for 10h to obtain pure-phase MnMoO₄A nanoflower/graphene composite electrode material; the standard card number corresponding to the XRD pattern of the product is JCPDS 50-1284, the spectrogram has no impurity peak, the peak appearance is corresponding well, and the phase is high purity; FIGS. 2 to 3 are SEM images of three-dimensional composite electrode materials: in the figure, the nanometer flower-shaped manganese molybdate material is embedded on a graphene sheet layer network interconnection structure and is uniformly distributed; manganese molybdate high-magnification Transmission Electron Microscopy (TEM) shows that: the lattice fringes of the manganese molybdate material are clear, and the crystal face index of XRD corresponding to the horizontal plane of the nanosheet is (-101); further proving the experimental conclusion that XRD is a high-purity phase; the single nanosheet display material of the TEM has high crystallinity, small particle size and regular morphology. Experimental tests show that: by adopting the technical route, high-purity MnMoO can be obtained₄The nanoflower/graphene three-dimensional electrode material is a super capacitor electrode material with excellent electrochemical performance.

The invention relates to a microwave radiation method for preparing MnMoO₄The fundamental difference between the nano flower/graphene three-dimensional electrode material and the manganese molybdate material prepared in the patent with the publication number of CN 107459063B is that: the graphene powder with high chemical stability and electronic conductivity is compounded with the manganese molybdate material, so that the electronic conductivity and the cycling stability of the manganese molybdate material are effectively improved, the electrochemical performance of the material is obviously improved due to the internal synergistic effect of the graphene powder and the manganese molybdate material, compared with a hydrothermal method, the microwave radiation method has the advantages of more concentrated energy, higher efficiency of synthesized products and controllable whole process, and a new idea is provided for the synthesis of the material.