Graphene / ZnSe composite microrod and preparation method and application thereof
By using graphene/ZnSe composite microrods in the negative electrode material of lithium-ion batteries, the volume changes, insufficient conductivity and agglomeration of ZnSe during charging and discharging are solved, and the structural stability and electrochemical performance of the electrode are significantly improved.
Patent Information
- Application Number
- CN202510309402.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-17
- Publication Date
- 2025-06-20
AI Technical Summary
ZnSe has problems in the negative electrode materials of lithium-ion batteries, such as structural damage, insufficient conductivity, low charge transfer efficiency, and prone to agglomeration, resulting in reduced active area.
By mixing graphene oxide with surfactant-modified ZIF-8 nanoparticles and using a multi-step synthesis process, the uniform loading of ZIF-8 nanoparticles in the three-dimensional space of graphene-based micron rods and their in-situ selenization conversion were achieved, and graphene/ZnSe composite micron rods were prepared.
This method effectively alleviates the volume change of ZnSe during charging and discharging, reduces agglomeration phenomenon, and improves conductivity, thereby significantly improving the structural stability, cycle life and rate performance of the electrode.
Smart Images
Figure CN120172359A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of anode materials, and particularly to a graphene / ZnSe composite micro-rod and its preparation method and application. Background Art
[0002] In the research field of anode materials for lithium-ion batteries, transition metal selenides are gradually becoming a popular choice for a new generation of high-performance anode materials due to their high theoretical specific capacity and excellent electrical conductivity. Specifically, the metal-selenium bond in transition metal selenides can effectively promote the insertion and extraction of lithium ions, enabling them to exhibit good reversibility and high ion transport rate during charge and discharge processes. In addition, the diversity of selenide structures provides a broad space for the regulation of electrochemical properties, and researchers can further optimize their performance through structural design and element doping. Among many transition metal selenide materials, zinc selenide (ZnSe) has attracted much attention due to its unique advantages such as high theoretical specific capacity, rich resource reserves, low cost, and good chemical stability. However, as an anode material for lithium-ion batteries, ZnSe faces several challenges in practical applications. First, ZnSe will undergo severe volume expansion and contraction during charge and discharge, which may lead to the destruction of the electrode structure and the shedding of active materials, thereby affecting the cycle performance and capacity retention rate of the battery. Second, although ZnSe has relatively high electrical conductivity, as a semiconductor material, there is still a large gap compared with materials such as graphite, acetylene black, and carbon nanotubes, resulting in low charge transfer efficiency, which in turn causes electrode polarization and energy loss, limiting its performance under high-rate charge and discharge conditions. In addition, ZnSe particles are prone to agglomeration in the electrode material, further reducing its active area and electrochemical stability. Therefore, how to design a ZnSe-based composite material that can effectively alleviate volume changes, reduce agglomeration phenomena, and improve electrical conductivity has important research value and practical significance. Summary of the Invention
[0003] The purpose of the present invention is to propose a graphene / ZnSe composite micro-rod and its preparation method and application in view of the above deficiencies of the prior art.
[0004] The first object of the present invention is to provide a preparation method of a graphene / ZnSe composite micro-rod, comprising the following steps:
[0005] S1: Dropwise add an aqueous surfactant solution into a ZIF-8 suspension, stir and react, and centrifuge, separate, and dry to obtain surfactant-modified ZIF-8 particles;
[0006] S2: Inject a mixed slurry composed of a graphene oxide solution and a surfactant-modified ZIF-8 dispersion into a rotating turntable of a coagulation bath containing an ethylenediamine solution through a syringe to obtain a composite gel micro-rod suspension;
[0007] S3: Hydrothermally react the composite gel micro-rod suspension and then naturally cool it to room temperature;
[0008] S4: Filter the micro-rod slurry after cooling in step S2, wash it with a volatile organic solvent to obtain a graphene / MOF composite micro-rod mixed slurry, and then dry and grind it to obtain a powder of RGO / surface-activity-modified ZIF-8 composite micro-rods;
[0009] S5: Calcinate selenium powder and the powder of RGO / surface-activity-modified ZIF-8 composite micro-rods in an inert atmosphere to obtain the corresponding graphene / ZnSe composite micro-rods.
[0010] Furthermore, in step S1, the surfactant aqueous solution is an aqueous solution prepared from one of sodium dodecyl sulfate, sodium dioctyl sulfosuccinate, sodium polystyrene sulfonate, and citric acid. Its aqueous solution concentration is 0.01 - 10 M and the volume is 5 - 50 ml; in step S1, stir and react for 1 - 6 hours and dry it in an oven at 60 - 120 °C; the suspension concentration is 20 - 400 mg / ml, and the volume ratio of the suspension to the surfactant aqueous solution is 10 - 200:5 - 50.
[0011] Furthermore, in step S2, the coagulation bath solution is prepared by injecting ethylenediamine into an ethanol / water mixed solution. The volume ratio of ethylenediamine to the ethanol / water mixed solution is 5 - 20:500 - 1000; in the ethanol / water mixed solution, the volume ratio of ethanol to water is 1 - 3:3 - 1.
[0012] Furthermore, in step S2, the solvent in the graphene oxide solution is one of water, N,N-dimethylformamide (DMF), and N-methyl-2-pyrrolidone (NMP), and the concentration is 5 - 45 mg / ml; surface-activity-modified ZIF-8 is ultrasonically dispersed in deionized water to form its dispersion.
[0013] Furthermore, in step S2, the syringe is a screw-thread syringe with a volume of 5 - 100 ml, and the matching needle is a 100 - 200 mm long needle with an inner diameter of the needle between 50 - 550 μm, and the injection speed is controlled between 0.1 - 3.0 ml / min.
[0014] Furthermore, in step S3, the hydrothermal reaction is carried out at 80 - 150 °C for 3 - 24 hours.
[0015] Further, in step S4, the volatile organic solvent is acetone, and it is filtered and washed with a 100-1000 mesh filter screen, and the filtration and washing are repeated 2-4 times; subsequently, the obtained composite micro-rod mixed slurry is transferred to a polytetrafluoroethylene container and dried in an oven at 60-120 °C, and then quickly ground with a micro grinder for 5-120 seconds to obtain RGO / surface-activity-modified ZIF-8 composite micro-rod powder; the composite micro-rod mixed slurry is obtained after filtering and washing with acetone and adding 10-150 ml of acetone.
[0016] Further, in step S5, the mass ratio of the selenium powder to the RGO / surface-activity-modified ZIF-8 composite micro-rod powder is 5-30:1; it is calcined at 300-900 °C for 1-10 h; they are respectively placed in porcelain boats with a front-back spacing of 2-10 cm in a tube furnace for calcination, and the porcelain boat containing the selenium powder is placed upstream of the gas flow in the tube furnace, and the ark containing the surface-activity-modified ZIF-8 composite micro-rod powder is placed downstream of the gas flow in the tube furnace; the inert atmosphere is one of nitrogen, argon or a hydrogen-argon atmosphere.
[0017] The second object of the present invention is to provide a graphene / ZnSe composite micro-rod prepared by the preparation method as described above.
[0018] The third object of the present invention is to provide an application of the graphene / ZnSe composite micro-rod as described above, which is used as a negative electrode material for a lithium ion battery.
[0019] The present invention uses graphene oxide (GO) and ZIF-8 nanoparticles treated with a surfactant to form a slurry, uses an ethylenediamine solution as a coagulation bath, and through a multi-step synthesis process of wet spinning, hydrothermal reaction, solvent exchange and high-temperature selenization reaction, realizes the uniform loading of ZIF-8 nanoparticles in the three-dimensional space of the graphene-based micro-rod and its in-situ selenization conversion, and prepares a graphene / ZnSe composite micro-rod powder material. The ZnSe particles in the product are overall in the form of collapsed nano rhombic dodecahedrons and are uniformly dispersed and encapsulated in the graphene micro-rod framework structure.
[0020] In the graphene / ZnSe composite micro-rod powder material prepared by the present invention, the ultra-high specific surface area and good mechanical flexibility of graphene provide a stable and uniformly dispersed support carrier for ZnSe, effectively alleviating the aggregation and severe volume fluctuations of ZnSe nanoparticles during charge and discharge processes, thereby significantly improving the structural stability and cycle life of the electrode. In addition, the unique micro-rod framework constructed by graphene forms a continuous three-dimensional conductive network, which can significantly improve the charge transport performance of the electrode on the basis of ensuring good wettability of the electrolyte, greatly reducing the interfacial resistance and charge transfer impedance of the composite material, thereby enhancing the rate performance and cycle stability of the electrode. Finally, the high conductivity and high thermal conductivity of graphene not only help to improve the overall conductive efficiency of the electrode, but also can effectively disperse the current density and reduce local overheating phenomena, further extending the service life of the battery.
[0021] By adjusting the mass ratio between graphene oxide and surfactant-modified ZIF-8, the present invention can achieve the preparation of graphene / ZnSe composite micro-rods with different loadings, enabling the composition and properties of the composite material to be flexibly adjusted according to specific application requirements and adapting to different design requirements of lithium-ion battery anode materials.
[0022] In summary, the graphene / ZnSe composite micro-rod powder material simultaneously solves the core problems of volume effect, insufficient conductivity, and particle aggregation of ZnSe during the application of lithium-ion battery anode materials, significantly improving the conductivity of the composite electrode, effectively alleviating the volume effect of ZnSe during charge and discharge processes, and enhancing lithium-ion transport and electrolyte penetration, thereby greatly improving the cycle stability and rate performance of the electrode and demonstrating excellent structural advantages and electrochemical properties.
[0023] The preparation of graphene / ZnSe composite micro-rods is not only innovative in structural design, but also provides a new idea for solving the key problems in the application of ZnSe as a lithium-ion battery anode material. By optimizing the composite method of graphene and ZnSe, not only can the synergistic effect of the two be fully exerted, but also it can provide an important reference for the development of future new high-performance battery materials. Description of the Drawings
[0024] Figure 1 is the Zeta potential diagram of the ZIF-8 particle suspension before and after being modified by sodium dodecyl sulfate (SDS);
[0025] Figure 2 is the scanning electron microscope photograph of the RGO / ZnSe composite micro-rods;
[0026] Figure 3 is the scanning electron microscope photograph of the RGO / ZIF-600 composite micro-rods;
[0027] Figure 4It is the scanning electron microscope photograph of CZIF-Se-600 powder;
[0028] Figure 5 It is the X-ray diffraction pattern of RGO / ZIF-600 and RGO / ZnSe composite micro-rods;
[0029] Figure 6 It is the comparison chart of long-term cycling performance of CZIF-Se-600, RGO / ZIF-600 and RGO / ZnSe micro-rod composite electrodes. Specific embodiments
[0030] The following are specific embodiments of the present invention and in combination with the accompanying drawings, the technical solutions of the present invention will be further described, but the present invention is not limited to these embodiments.
[0031] Example 1
[0032] The preparation process of graphene / ZnSe composite micro-rods is as follows:
[0033] First, prepare surfactant-modified ZIF-8 nanoparticles: Synthesize dry powder of ZIF-8 according to existing methods (such as: J.Mater.Chem.A, 2019, 7, 11016; Nano Energy, 2023, 111, 108401), weigh 1-3 g of ZIF-8 nanoparticles from it, and under the condition of ultrasonic oscillation, disperse it in 50-100 ml of deionized water as solution A; Prepare an aqueous solution of sodium dodecyl sulfate (SDS) with a molar concentration of 0.1-2.0 M and a volume of 10-20 ml as solution B; Under the condition of magnetic stirring, slowly drop solution B into the ZIF-8 dispersion (in solution A), and continuously stir and react for 2-3 hours to ensure that the SDS surfactant is fully adsorbed on the surface of ZIF-8 particles; Finally, centrifuge and collect the SDS-modified ZIF-8 particles at a rotation speed of 4000-6000 rpm, and dry them in an oven at 60-80 °C for later use.
[0034] Weigh 2.5 g of the SDS-modified ZIF-8 nanoparticle powder with an electronic balance, add it to a test tube containing 10 ml of deionized water, and ultrasonically oscillate until it is completely dissolved. Subsequently, slowly pour the suspension into 50 ml of a graphene oxide solution with a concentration of 9.7 mg / ml, and ultrasonically oscillate again to ensure uniform mixing, thus preparing a composite slurry for later use. At the same time, inject 5 ml of ethylenediamine into a mixed solution composed of 200 ml of deionized water and 300 ml of ethanol to prepare a coagulation bath solution.
[0035] Place a crystallization dish with a diameter of 180 mm on an automatic horizontal turntable, add about 100 ml of coagulation bath solution, and adjust the rotation speed to 110 - 160 rpm. Use a plastic syringe to draw about 15 ml of the pre - mixed and homogeneous graphene oxide / SDS - modified ZIF - 8 composite slurry. After switching to a long injection needle with a length of 150 - 180 mm, adjust the needle direction to be tangent to the rotation direction of the turntable. The inner diameter of the needle is between 100 - 350 μm, and control the injection speed at 0.5 - 2 ml / min. Under the combined action of shear force, ionic cross - linking and coordination, the graphene oxide / SDS - modified ZIF - 8 composite slurry cross - links and coordinates with ethylenediamine in the solution and self - assembles in the coagulation bath to form composite gel micro - rods.
[0036] Transfer the obtained gel micro - rod mixture to a 500 - ml autoclave and carry out a hydrothermal reaction at 80 - 120 °C for 12 hours. After the reaction is completed, cool it naturally to room temperature. Filter the cooled micro - rods with gauze and rinse them repeatedly with acetone. Then redisperse them in a small amount of acetone and dry them in an oven at 80 - 120 °C. After drying, use a micro - grinder to grind them quickly for 10 - 60 seconds to obtain the RGO / SDS - modified ZIF - 8 composite micro - rod powder.
[0037] Subsequently, using selenium powder as the selenium source, weigh 20 - 25 g of selenium powder and spread it flat in a porcelain boat and place it upstream of the gas flow in a tube furnace; weigh 0.8 - 1.0 g of the RGO / surface - active - modified ZIF - 8 composite micro - rod powder and spread it flat in a porcelain boat, place it 3 - 5 cm away from the selenium - powder porcelain boat downstream of the gas flow, and calcine it at 600 °C for 3 h in an argon atmosphere. Finally, the corresponding graphene / ZnSe composite micro - rods are obtained, marked as RGO / ZnSe.
[0038] For comparison, without adding selenium powder, directly calcine at 600 °C (other conditions remain unchanged) to obtain the composite micro - rods marked as RGO / ZIF - 600; and the powder obtained by high - temperature selenization of the same mass of pure ZIF - 8 nanoparticle powder is marked as CZIF - Se - 600.
[0039] Figure 1 Figure shows the Zeta potential diagram of the ZIF - 8 particle suspension before and after modification with sodium dodecyl sulfate (SDS). Figure 1 As shown, the results of the Zeta potential diagram show that the surface of ZIF - 8 particles changes from typical positive charge to significant negative charge after SDS modification, thus avoiding obvious agglomeration when mixed with the graphene oxide solution, and a stable and uniform composite slurry can be generated.
[0040] Figure 2 Figure is the scanning electron microscope photo of the RGO / ZnSe composite micro - rods; Figure 3 Figure is the scanning electron microscope photo of the RGO / ZIF - 600 composite micro - rods;Figure 4 This is the scanning electron microscope image of CZIF-Se-600 powder. The results of scanning electron microscopy (SEM) Figure 2 and Figure 3 ) show that the as-prepared RGO / ZnSe and RGO / ZIF-600 composite micro-rods are all in the shape of micro-rods as a whole, with a typical flaky wrinkled structure of graphene (RGO) on the surface. The nanoparticles in the products are uniformly distributed on the RGO micro-rod framework, with uniform particle sizes (all between 60 - 280 nm), and the overall shape is a collapsed rhombic dodecahedron without obvious agglomeration. At the same time, as Figure 4 shown, the directly high-temperature selenized ZIF-8 nanoparticles obtained are directly sintered and agglomerated into large micro-particles, and the high-temperature fusion grain boundaries can be clearly seen. Further, combined with the corresponding X-ray powder diffraction (XRD) patterns Figure 5 ), it shows that the diffraction peaks of the RGO / ZIF-600 and RGO / ZnSe composite materials coincide with the diffraction peaks of standard ZnO and ZnSe respectively, further confirming that the collapsed rhombic dodecahedron nanoparticles in the composite materials are highly crystalline ZnO and ZnSe nanoparticles respectively. In contrast, although the ZIF-8 nanoparticles can be completely converted into ZnSe powder through direct high-temperature selenization, the agglomeration between nanoparticles and high-temperature fusion cannot be avoided during the calcination process.
[0041] Figure 6 This is the comparison chart of the long-term cycling performance of the CZIF-Se-600, RGO / ZIF-600 and RGO / ZnSe micro-rod composite electrodes; as Figure 6 shown, compared with the CZIF-Se-600 and RGO / ZIF-600 based composite electrodes, the RGO / ZnSe micro-rod based composite electrode shows significantly higher specific capacity, higher rate performance and better cycling stability. This indicates that the RGO / ZnSe micro-rods can effectively alleviate the volume effect of ZnSe during charge and discharge by uniformly dispersing and encapsulating the ZnSe nanoparticles converted from in-situ selenization of ZIF-8 within the graphene micro-framework, significantly reducing the interfacial resistance, accelerating the lithium-ion transport and electrolyte penetration, thereby greatly improving the cycling stability and rate performance of the electrode, and further revealing the significant structural advantages and electrochemical performance advantages of the RGO / ZnSe composite micro-rods in the design of anode materials for lithium-ion batteries.
[0042] Example 2
[0043] The difference between this embodiment and Specific Example 1 is that the corresponding surfactant solution is changed from a 0.1 - 0.5 M sodium dodecyl sulfate solution to a 0.05 - 0.3 M sodium polystyrene sulfonate (PSS) solution.
[0044] Example 3
[0045] The difference between this embodiment and the specific Example 1 is that the corresponding calcination temperature is changed to 500 °C and the calcination time is changed to 8 h.
[0046] For those not covered above, the prior art applies.
[0047] Although some specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and not for limiting the scope of the present invention. Those skilled in the art to which the present invention pertains can make various modifications or supplements to the described specific embodiments or use similar means for substitution, but will not deviate from the direction of the present invention or exceed the scope defined by the appended claims. Those skilled in the art should understand that any modification, equivalent replacement, improvement, etc. made to the above embodiments based on the technical essence of the present invention shall be included in the protection scope of the present invention.
Claims
1. A method for preparing graphene / ZnSe composite microrods, characterized in that: The following steps are involved: S1: adding a surfactant aqueous solution dropwise into the ZIF-8 suspension, stirring for reaction, centrifuging and drying to obtain surfactant-modified ZIF-8 particles; S2: injecting a mixed slurry consisting of a graphene oxide solution and a surfactant-modified ZIF-8 dispersion into a rotating turntable containing a coagulation bath of an ethylenediamine solution through a syringe to obtain a composite gel microrod suspension; S3: subjecting the composite gel microrod suspension to a hydrothermal reaction and then naturally cooling to room temperature; S4: filtering the cooled microrod slurry in step S3, washing it with a volatile organic solvent to obtain a graphene / MOF composite microrod mixed slurry, and then drying and grinding it to obtain RGO / surface active modified ZIF-8 composite microrod powder; S5: calcining selenium powder and RGO / surfactant-modified ZIF-8 composite microrod powder in an inert atmosphere to obtain graphene / ZnSe composite microrods.
2. The preparation method according to claim 1, characterized in that: In step S1, the surfactant aqueous solution is an aqueous solution selected from the group consisting of sodium dodecyl sulfate, sodium dioctyl sulfosuccinate, sodium polystyrene sulfonate, and citric acid, and the aqueous solution concentration is 0.01-10M and the volume is 5-50ml. In step S1, the reaction is stirred for 1 to 6 hours and dried in an oven at 60-120°C. The concentration of the suspension is 20-400mg / ml, and the volume ratio of the suspension to the surfactant aqueous solution is 10-200:5-50.
3. The preparation method according to claim 1, characterized in that: In step S2, the coagulation bath solution is prepared by injecting ethylenediamine into an ethanol / water mixed solution, wherein the volume ratio of ethylenediamine to the ethanol / water mixed solution is 5-20:500-1000; and in the ethanol / water mixed solution, the volume ratio of ethanol to water is 1-3:3-1.
4. The preparation method according to claim 1, characterized in that: In step S2, the solvent in the graphene oxide solution is one of water, N,N-dimethylformamide, and N-methyl-2-pyrrolidone, and the concentration is 5-45 mg / ml; the surfactant-modified ZIF-8 is ultrasonically dispersed in deionized water to form its dispersion.
5. The preparation method according to claim 1, characterized in that: In step S2, the needle tube is a screw-mouth needle tube with a volume of 5-100 ml, a matching needle head of 100-200 mm in length, an inner diameter of the needle head of 50-550 μm, and an injection speed controlled between 0.1-3.0 ml / min.
6. The preparation method according to claim 1, characterized in that: In step S3, the hydrothermal reaction is carried out at 80-150° C. for 3-24 hours.
7. The preparation method according to claim 1, characterized in that: In step S4, the volatile organic solvent is acetone, which is filtered and washed with a 100-1000 mesh filter screen, and the filtration and washing are repeated 2-4 times; then, the obtained composite microrod mixed slurry is transferred to a polytetrafluoroethylene container and dried in an oven at 60-120°C, and quickly ground using a micro grinder for 5-120 seconds to obtain RGO / surfactant-modified ZIF-8 composite microrod powder; the composite microrod mixed slurry is obtained after filtration and washing with acetone and adding 10-150 ml of acetone.
8. The preparation method according to claim 1, characterized in that: In step S5, the mass ratio of the selenium powder and the RGO / surfactant-modified ZIF-8 composite microrod powder is 5-30:1; calcined at 300-900°C for 1-10h; placed in porcelain boats with a front-to-back spacing of 2-10cm in a tubular furnace for calcination, the porcelain boat containing the selenium powder is placed upstream of the airflow in the tubular furnace, and the boat containing the surfactant-modified ZIF-8 composite microrod powder is placed downstream of the airflow in the tubular furnace; the inert atmosphere is one of nitrogen, argon or hydrogen-argon atmosphere.
9. A graphene / ZnSe composite microrod prepared by the preparation method according to any one of claims 1 to 8.
10. An application of the graphene / ZnSe composite microrod according to claim 9, characterized in that: Used as negative electrode material for lithium-ion batteries.