CN112174203A

CN112174203A - Preparation method of antimony vanadate and graphene composite material

Info

Publication number: CN112174203A
Application number: CN202011057472.2A
Authority: CN
Inventors: 易先辉; 鲁兵安
Original assignee: Fujian Strait Graphene Industry Technology Research Institute Co ltd
Current assignee: Fujian Strait Graphene Industry Technology Research Institute Co ltd
Priority date: 2020-09-30
Filing date: 2020-09-30
Publication date: 2021-01-05

Abstract

The invention discloses a preparation method of antimony vanadate and graphene composite material, which comprises the steps of reducing graphene oxide, ammonium metavanadate and antimony trichloride, synthesizing and preparing uniformly dispersed antimony vanadate nanoparticles on reduced graphene oxide nanosheets by a one-step solvothermal method, and coating the antimony vanadate nanoparticles with the reduced graphene oxide to form the sandwich-shaped nanometer-structure antimony vanadate and graphene composite material. The antimony vanadate and graphene negative electrode material provided by the invention has excellent electrochemical performance when being used as a negative electrode of a potassium ion battery: a) high capacity; b) high rate capability c) good cycle performance.

Description

Preparation method of antimony vanadate and graphene composite material

Technical Field

The invention relates to a battery cathode material, in particular to a preparation method of an antimony vanadate and graphene composite material.

Background

Potassium ion battery (PIB) has become the predominant energy storage system due to its low cost and abundant potassium resource advantages. However, its low capacity greatly hinders its rapid development. High capacity PIB positive electrode materials (e.g., KVPO) are currently under development₄F and prussian blue) have made significant progress. However, most studies of anode materials have only achieved less than 300mA h g, in addition to two high capacity potassium anodes based on alloyed/converted potassium anodes^-1Low capacity of (2). Alloy-based cathodes acting through alloying/dealloying mechanisms, e.g. antimony, phosphorus and tin phosphide Sn4P₃And is considered to be one of the promising electrode materials for high capacity PIB. However, during operation of the battery, the particle material pulverization, delamination problems and continuously formed new surfaces due to the large volume expansion of the alloying materials result in rapid capacity fade of the battery. For example, black phosphorus/C (black phosphorus: C ═ 1: 1), although its capacity is up to 433.2mAh g^-1But at 50mA g^-1The current density can only be maintained for 50 cycles, and the capacity retention rate is only 61%. On the other hand, another high-capacity anode that benefits from multiple electron transfer processes in the conversion reaction, i.e., an anode based on conversion, has also attracted considerable attention. However, the development of the electrode is greatly hindered by the problems of high operating voltage and large voltage hysteresis due to poor reversibility of the conversion reaction. Therefore, solving the above problems and extending the life of the anode are major challenges in developing high capacity potassium anodes.

Few studies have reported that both alloying and converted potassium storage reaction mechanisms exist to achieve high capacity and long life negative electrode materials of PIB. In the face of larger potassium ions, there is still a need for more research on conversion/alloy coexistence based potassium ion battery anodes. Therefore, research and development of a potassium ion battery anode material based on such realization of high capacity and long cycle life through a novel potassium storage mechanism by coexistence of alloying and conversion is urgently required.

Disclosure of Invention

Aiming at the problems, the invention provides a preparation method of an antimony vanadate and graphene composite material.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows: the invention provides a preparation method of an antimony vanadate and graphene composite material, which comprises the steps of reducing graphene oxide, ammonium metavanadate and antimony trichloride, synthesizing and preparing uniformly dispersed antimony vanadate nanoparticles on reduced graphene oxide nanosheets by a one-step solvothermal method, and coating the antimony vanadate nanoparticles with the reduced graphene oxide to form the sandwich-shaped nanometer-structure antimony vanadate and graphene composite material.

Further, the antimony vanadate and graphene composite material comprises graphene nanosheets and antimony vanadate nanoparticles; the antimony vanadate nanoparticles are uniformly distributed on the surface of the graphene nanosheet, and the graphene nanosheet is coated with the antimony vanadate nanoparticles.

From the above description of the structure of the present invention, compared with the prior art, the present invention has the following advantages: the antimony vanadate and graphene negative electrode material provided by the invention has excellent electrochemical performance when being used as a negative electrode of a potassium ion battery: a) high capacity; b) high rate capability c) good cycle performance.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

fig. 1 is a schematic diagram of a preparation process of antimony vanadate and graphene provided by the present invention.

FIG. 2 is a representation of the microscopic morphology of antimony vanadate and graphene provided by the present invention.

Fig. 3 is a structural feature analysis of antimony vanadate and graphene provided by the present invention.

Fig. 4 is a diagram of electrochemical performance of antimony vanadate and graphene provided by the invention as a negative electrode of a potassium ion battery.

Fig. 5 is an XRD and XPS characterization chart of antimony vanadate and graphene provided by the present invention.

Fig. 6 is an SEM characterization diagram of antimony vanadate and graphene in different states after different cycles according to the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The invention provides an antimony vanadate and graphene composite material. The antimony vanadate and graphene composite material comprises a graphene nanosheet and antimony vanadate nanoparticles; the antimony vanadate nanoparticles are uniformly distributed on the surface of the graphene nanosheet, and the graphene nanosheet is coated with the antimony vanadate nanoparticles; the graphene is Reduced Graphene Oxide (RGO). The antimony vanadate and graphene composite material serving as the negative electrode of the potassium ion battery realizes potassium ion storage through a potassium ion storage reaction mechanism coexisting in alloying/conversion reaction.

The preparation method of the antimony vanadate and graphene composite material is shown in figure 1: using graphene oxide, ammonium metavanadate (NH)₄VO₃) And antimony trichloride (SbCl)₃) As a main raw material, antimony vanadate nanoparticles are uniformly dispersed on reduced graphene oxide nanosheets only through one-step solvothermal synthesis, and are coated by the reduced graphene oxide to form sandwich-shaped nano-structured antimony vanadate and reduced graphene oxide, namely antimony vanadate and RGO.

The microscopic morphology characterization of antimony vanadate and RGO is shown in fig. 2, a is a structural schematic diagram of antimony vanadate and RGO, showing the concept that antimony vanadate nanoparticles are uniformly dispersed on reduced graphene oxide nanosheets. Scanning Electron Microscopy (SEM) of fig. 2b and 2c confirmed that the antimony vanadate nanoparticles were successfully dispersed on the reduced graphene oxide nanoplatelets and were uniformly distributed. Microscopic morphological studies of this material were performed by High Resolution Transmission Electron Microscopy (HRTEM), d-e clearly showing that antimony vanadate is covered by several layers of Reduced Graphene Oxide (RGO) nanoplates, forming a sandwich-like nanostructure, consistent with the SEM structure. FIG. 2f shows that the measured interplanar spacing was 0.192nm, corresponding to the antimony vanadate (110) crystal plane. The unique mixed structure of antimony vanadate and RGO is beneficial to the rapid permeation of electrolyte, enhances the electron transmission and reduces the electrode polarization. In addition, the reduced graphene oxide nanosheets may form a network, thereby improving the electrochemical stability of the electrode.

The structural characteristic analysis of antimony vanadate and RGO is shown in figure 3, and the a XRD pattern can show that the sample has good crystallinity. The prominent diffraction peaks at 27.420 °, 35.093 °, 53.546 ° and 67.251 ° were consistent with the standard XRD of antimony vanadate. In addition, since the intensity of the diffraction peak of RGO is relatively weak, a peak derived from RGO is not observed in the XRD pattern. The XPS spectrum of b shows four main elements belonging to Sb, V, C and O. The high resolution spectrum of Sb 3d of c shows that the two broad peaks at the typical features of Sb 3d5/2 and Sb 3d3/2, respectively, are at 531.1 and 540.5eV, respectively, confirming the presence of Sb3 in antimony vanadate and RGO materials⁺. The high resolution V2 p spectrogram shown as d shows that the binding energies of the two peaks are 517.1eV (V2 p3/2) and 524.4eV (V2 p1/2), respectively, corresponding to V5⁺. The antimony vanadate and RGO materials provided by the invention have the expected valence change of the cathode material of the potassium ion battery.

And assembling the potassium ion button cell by taking the antimony vanadate and the RGO provided by the invention as a negative electrode and taking the potassium foil as a counter electrode, and circulating at room temperature to perform electrochemical test. Electrochemical performance is shown in FIG. 4, where a shows s at a scan rate of 0.1mV^-1Voltage ranges between 0.01V and 3V (vs K/K +), Cyclic Voltammetry (CV) curves for antimony vanadate and RGO electrodes. The electrode showed a strong oxidation/reduction peak, corresponding to the redox reaction of V. Three reduction peaks appear in the first scan, two narrow at 0.68 and 0.76V and one broad at 0.40V due to Solid Electrolyte Interface (SEI) formation and chemical changes of the material to accommodate K⁺Notably, the subsequent CV curve is slightly different from the first CV curve due to the conversion and alloying chemical reactions that occur at the electrode during the first cycle. In addition, good overlapping of subsequent CV curves indicates that the electrochemical reaction of the antimony vanadate and RGO electrode provided by the invention has high reversibility. The antimony vanadate and RGO charge/discharge curves of b show that the plateau of the discharge curve matches the result of the CV curve, demonstrating the process of sylation occurring in the electrode. Antimony vanadate and RGThe O electrode showed an initial potassification capacity of up to 1461.7mAh g^-1The initial Coulombic Efficiency (CE) was only 29.2%. The low CE of the initial cycle may be partly due to the formation of the SEI layer. It can be seen that the 20 th discharge curve is consistent with the 50 th discharge curve, and even the 100 th discharge curve, indicating that antimony vanadate and RGO electrodes have high cycling stability. c at 100mA g^-1The long-term cycling performance at current densities of (a) shows that antimony vanadate and RGO can provide discharge capacities of up to 447.9mAh g-1 in the second cycle, maintaining 210.1mAh g-1 after 500 cycles (corresponding to an average capacity decay rate of only 0.106% per cycle), indicating that antimony vanadate and RGO have excellent cycling stability. Due to the unique advantages of the new potassium storage mechanism and the formation of SEI in this electrode, the corresponding CE of antimony vanadate and RGO reached 99% quickly after the first few cycles, and remained high thereafter. The rate capability of antimony vanadate and RGO under different current densities is shown as d, and the current densities are 100, 200, 500 and 1000mA g^-1The discharge capacities were 407, 339, 192, and 118mAh g, respectively^-1When the current density returns to 500mA g^-1Then, the discharge capacity was restored to 172mAh g^-1And the left and the right show that the electrode has excellent rate performance. e, average capacity fade per cycle, specific capacity and cycling performance of antimony vanadate and RGO are compared to other disclosed negative electrodes, including those based on alloyed negative electrodes (Sn)₄P₃/C, BP/C (black phosphorus/C), Sn-C), negative electrodes based on conversion (CuO, CF (for Co)₃O₄-Fe₂O₃/C，MoS₂And SnO₂And C), a negative electrode (SnS) based on a conversion alloy₂-RGO coating). e and the results in table 1 below show that antimony vanadate and RGO have the highest reversible capacity and the best cycling stability, with cycle times as high as 500.

The chemical state changes of the antimony vanadate and the RGO electrode in the potassium/potassium removing process are researched, and the reaction mechanism of potassium ion storage is known. A in FIG. 5Bit XRD showed that the peak intensities of antimony vanadate and RGO sharply decrease upon the first discharge to 0.5V. At the same time, two new peaks appear at 29.6 ° and 34.7 °, corresponding to K, respectively₃VO₄And K³And (5) Sb. When fully discharged to 0.01V, the final product contains K₃VO₄，K₃+xVO₄And K₃And (5) Sb. The peak intensity is gradually increased during the discharge process and is not decreased until the next charging process. This is probably due to the fact that the cation radius of vanadium, a transition metal, increases because it is due to the insertion of potassium into the crystal lattice, which leads to a decrease in valence, and the repulsive force between layers cannot be decreased with the increase in potassium ions. In addition, the 27.4 ° initial peak corresponding to antimony vanadate and RGO (110) did not appear during the next charge/discharge process. This indicates that the conversion reaction process of the electrode was completed in the first potassium process and the electrochemical reaction was reconstructed. The valence changes in different states were investigated by high resolution XPS spectroscopy, and the initial electrode contained Sb as shown by b and d³⁺And V⁵⁺If the electrode is fully discharged (to 0.01V; vs K/K +), then Sb⁰Can well fit Sb 3d_3/2The peak in the spectrum at 539.3 eV. Two narrow peaks in d, one of which is located at the point assigned to V⁴⁺V2 p of_3/2516.8eV, V³⁺The peak at 516.4.0eV can be well fitted, confirming V in antimony vanadate⁵⁺The valence state of (a) is significantly lower. This indicates K₃VO₄Has electrochemical activity. When the electrode is charged to 3.0V (vs K/K +), the peak of Sb 3d shift can be divided into two peaks, at 540.0eV and 539.4eV, respectively, assigned to Sb³⁺And Sb⁰。Sb³⁺Has a peak intensity and a peak area much lower than those of Sb⁰Showing that Sb³⁺Predominate in the electrodes. In the V2 p spectrum, the peak at 517.0eV indicates that V has been recovered⁵⁺. This novel potassium storage mechanism is more clearly expressed as shown in c. During the first discharge, antimony vanadate and RGO and K⁺Reacting to form elements Sb and K₃VO₄. Elements Sb and K⁺Reaction to form K₃Sb，K₃VO₄In subsequent reactions with separate conversionIs K_3+xVO₄It was confirmed that alloying/conversion reaction occurred. The alloying reaction and the conversion reaction together contribute to a high capacity. K_3+xVO₄The structural strain caused by the alloying reaction can be effectively buffered.

To verify the structural stability of antimony vanadate and RGO, they were studied at 100mA g^-1The morphology change during charge and discharge cycles at current density was observed with SEM for the electrodes at different cycling conditions. It is evident that the morphology of the material has hardly changed after two cycles. As shown in fig. 6, d, e and f, the morphology of the material remained unchanged over long periods of time, even up to 600 cycles, and the nanoparticles were clearly visible in the corresponding SEM images, both in the charged and discharged state. The result shows that the microstructures of the antimony vanadate and the RGO material can not be changed even if the charge and discharge cycles are repeated for a long time, and the method for combining the alloying reaction and the conversion reaction in the negative electrode of the potassium ion battery can effectively solve the problems of electrode material pulverization and layering caused by the charge and discharge processes of the electrode material, and has great contribution to the cycle stability of the potassium ion battery.

In conclusion, the antimony vanadate and the graphene provided by the invention are prepared into uniformly dispersed antimony vanadate nanoparticles on the reduced graphene oxide by a simple one-step solvothermal method. Antimony vanadate is coated by the reduced graphene oxide nanosheets to form a sandwich-like nanostructure, and the unique mixed structure can enable electrolyte to better permeate, so that the rate capability is further improved. The antimony vanadate and the graphene provided by the invention have alloying reaction and conversion reaction together, and the two reactions participate in electrochemical reaction together, so that the capacity can be further improved; while both reactions may promote each other to maintain structural integrity. Therefore, the antimony vanadate and the graphene show excellent electrochemical performance as the negative electrode material of the potassium ion battery: 1) high capacity, at 100mA g^-1Has 447.9mAh g at current density^-1High reversible discharge capacity (approaching calculated theoretical capacity 566mAh g^-1) (ii) a 2) Long service life: at 100mA g^-1210.1mAh g is still kept after 500 times of charge-discharge circulation under current density^-1The discharge capacity of (a) is high,equivalent to an average capacity fade rate per cycle of only 0.106%; 3) high rate performance of 100, 200, 500, 1000mAg^-1Reversible capacity at current density of 407, 339, 192 and 118mAh g respectively^-1When the current density is recovered to 500mA g^-1Then, the reversible capacity was restored to 172mAh g^-1。

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims

1. A preparation method of antimony vanadate and graphene composite material is characterized in that uniformly dispersed antimony vanadate nanoparticles are prepared on reduced graphene oxide nanosheets through reduction of graphene oxide, ammonium metavanadate and antimony trichloride and one-step solvothermal synthesis, and the antimony vanadate nanoparticles are coated by the reduced graphene oxide to form the sandwich-shaped nanometer-structure antimony vanadate and graphene composite material.

2. The method for preparing an antimony vanadate and graphene composite material according to claim 1, wherein the method comprises the following steps: the antimony vanadate and graphene composite material comprises a graphene nanosheet and antimony vanadate nanoparticles; the antimony vanadate nanoparticles are uniformly distributed on the surface of the graphene nanosheet, and the graphene nanosheet is coated with the antimony vanadate nanoparticles.