Active electrode material with high-density structure and preparation method thereof
Through the combination of hydrothermal synthesis and self-shrinkage assembly, active electrode materials with high density structures were prepared, which solved the problem of low energy density of zinc ion capacitors, significantly improved their capacity and energy density, and simplified the process flow.
Patent Information
- Application Number
- CN202411466342.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-21
- Publication Date
- 2025-02-28
AI Technical Summary
The low energy density of existing zinc ion capacitors limits their performance in miniaturization applications.
The method of combining hydrothermal synthesis and self-shrinkage assembly was used to prepare an active electrode material with a high density structure. The method includes hydrothermal reaction of the graphene oxide solution, followed by heat shrinkage and ball milling, and finally sieve to obtain the active electrode material.
The capacity and energy density of zinc ion capacitors are improved, while simplifying the synthesis process of electrode materials, making the operation relatively simple.
Smart Images
Figure CN119542036A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to an active electrode material with a high-density structure and a preparation method thereof, belonging to the technical field of electrochemical energy storage. Background Art
[0002] In recent years, the problems of energy depletion and greenhouse effect caused by excessive consumption of non-renewable resources have become increasingly serious, which urgently requires some green energy and efficient energy storage devices to replace them. At the same time, the development of portable and implantable electronic products has focused on miniaturization, which further stimulates the huge demand for high-performance miniaturized energy storage devices. Zinc-ion micro-hybrid capacitors are a new type of electrochemical energy storage device developed in recent years, which has the characteristics of miniaturization, high energy density and high power density. However, low energy density remains the main challenge in the development of high-performance micro zinc-ion capacitors. Therefore, the development of an active electrode material with a high-density structure will improve the energy density of zinc-ion capacitors.
[0003] At present, the electrode materials used in commercial zinc ion capacitors are mostly manganese-based oxides such as activated carbon and manganese dioxide (MnO2), which have limited effect on improving the energy density of zinc ion capacitors. In recent years, graphene and its oxides have attracted much attention due to their low price and good performance. Among them, the preparation methods of reduced graphene oxide mainly include chemical reduction, thermal reduction and other reduction methods. Chemical reduction is a commonly used method for preparing reduced graphene oxide. This method involves the use of a reducing agent to remove oxygen-containing groups on the surface of graphene oxide, thereby restoring its conjugated structure and conductivity. The thermal reduction method removes oxygen-containing groups on the surface of graphene oxide by high-temperature treatment, which can effectively restore the conjugated structure of graphene. Other reduction methods include electrochemical reduction, photocatalytic reduction, etc. With the in-depth study of them, the use of reduced graphene oxide as an electrode material has significantly improved the energy density of zinc ion capacitors. However, the existing preparation methods are complex, and the performance of electrode materials still needs to be further improved. Summary of the invention
[0004] In view of this, the object of the present invention is to provide an active electrode material with a high-density structure and a preparation method thereof. An active electrode material that can improve the capacity and energy density of a zinc ion capacitor is prepared by combining hydrothermal synthesis with self-shrinkage assembly. The method uses a commercial graphene oxide solution as a material, hydrothermally synthesizes and reduces graphene oxide, and then prepares an active electrode material by heating, shrinking, and ball milling. The active electrode material has a high tap density, and after being assembled into a micro zinc ion capacitor device, the capacity and energy density of the micro zinc ion capacitor can be significantly improved.
[0005] To achieve the above objectives, the technical solution of the present invention is as follows.
[0006] A method for preparing an active electrode material with a highly dense structure, the method comprising the following steps:
[0007] (1) placing a monolayer graphene oxide solution into a reactor for hydrothermal reaction to obtain a reduced graphene oxide block;
[0008] (2) heating and shrinking the reduced graphene oxide block at 90 to 110° C. for 7 to 8 hours;
[0009] (3) crushing and grinding the reduced graphene oxide block after heating and shrinking into powder, and then ball milling;
[0010] (4) After the ball milling is completed, the reduced graphene oxide powder is sieved to obtain an active electrode material with a highly dense structure.
[0011] Preferably, in step (1), the mass fraction of the single-layer graphene oxide solution is 0.9% to 1%.
[0012] Preferably, in step (1), during the hydrothermal process, the hydrothermal synthesis is firstly carried out at 90 to 100° C. for 2.5 to 3 hours, and then at 170 to 190° C. for 5 to 7 hours.
[0013] Preferably, in step (3), during ball milling, the ball-to-material ratio is 2 to 3:1, the rotation speed is 100 to 150 rpm, and the time is 1 to 2 days.
[0014] Preferably, in step (4), a 0.1 mm standard mesh screen is used for sieving to screen out reduced graphene oxide powder having a pore size less than 0.1 mm.
[0015] An active electrode material with a highly dense structure is prepared by the above method.
[0016] Preferably, the tap density of the electrode material is 0.9 to 1 g / cm 3 .
[0017] A miniature zinc ion capacitor, wherein the electrode material of the capacitor adopts the active electrode material with a high-density structure described in the present invention.
[0018] Beneficial Effects
[0019] The active electrode material of the present invention has a high tap density, can exert good electrical conductivity, and improves the capacity and energy density of the zinc ion capacitor. At the same time, the synthesis preparation process of the present invention is simple to operate, and the active electrode material is prepared by hydrothermal synthesis technology and self-shrinkage assembly technology, which greatly simplifies the synthesis process of the electrode material. In addition, this preparation method can prepare electrode materials in batches, providing broad practical application prospects for electrode materials. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 This is a physical picture of the reduced graphene oxide block after hydrothermal synthesis in Example 1.
[0021] Figure 2 This is a physical picture of the reduced graphene oxide block after heating and shrinkage in Example 1.
[0022] Figure 3 This is a physical picture of the reduced graphene oxide after ball milling in Example 1.
[0023] Figure 4 This is a physical picture of the reduced graphene oxide powder after screening in Example 1.
[0024] Figure 5 This is a physical picture of the graphite paper coated with sticky mud after drying in Example 1.
[0025] Figure 6 This is a physical picture of the graphite paper coated with the viscous slurry in Example 1 after being etched under the laser to produce the interdigitated electrodes.
[0026] Figure 7 This is a physical picture of the interdigital electrodes of zinc foil etched by laser in Example 1.
[0027] Figure 8 This is a physical picture of the zinc ion microcapacitor assembled in Example 1.
[0028] Fig. 9 This is a performance diagram of the assembled zinc ion microcapacitor tested using linear cyclic voltammetry (CV) in Example 1.
[0029] Fig.10 This is a performance diagram of the assembled zinc ion microcapacitor tested using constant current charge and discharge (GCD) in Example 1.
[0030] Fig.11 This is a physical picture of the reduced graphene oxide block after hydrothermal synthesis in Example 2.
[0031] Fig.12 This is a physical picture of the reduced graphene oxide block after heating and shrinkage in Example 2.
[0032] Fig.13 This is a performance diagram of the assembled zinc ion microcapacitor tested using constant current charge and discharge (GCD) in Example 2.
[0033] Fig.14 This is a physical picture of the reduced graphene oxide block after hydrothermal synthesis in Example 3.
[0034] Fig.15This is a physical picture of the reduced graphene oxide block after heating and shrinkage in Example 3.
[0035] Fig.16 This is a performance diagram of the assembled zinc ion microcapacitor tested using constant current charge and discharge (GCD) in Example 3. DETAILED DESCRIPTION
[0036] The present invention will be further described in detail below in conjunction with specific embodiments.
[0037] Example 1
[0038] (1) A single-layer graphene oxide solution (mass fraction of 0.9%) was placed in a 50 ml reactor, and hydrothermally synthesized at 95° C. for 3 hours and then at 180° C. for 6 hours to obtain a reduced graphene oxide block, such as Figure 1 As shown;
[0039] (2) taking the reduced graphene oxide block synthesized above, placing it in an oven for heating and shrinking (heating and shrinking at 100° C. for 8 hours), and obtaining a reduced graphene oxide block after heating and shrinking, such as Figure 2 As shown;
[0040] (3) The reduced graphene oxide block after heating and shrinkage in the above (2) was crushed and manually ground into a powder, and then ball milled with a ball mill at a ball-to-material ratio of 2:1, a rotation speed of 100 rpm, and a ball milling time of one day to obtain reduced graphene oxide in a powdery state, such as Figure 3 As shown;
[0041] (4) The reduced graphene oxide after ball milling is taken out and screened with a 0.1 mm standard mesh screen to screen out the reduced graphene oxide powder with a pore size less than 0.1 mm, thus obtaining the required active electrode material, such as Figure 4 As shown;
[0042] (5) The active electrode material synthesized in the above (4) is mixed with a conductive agent ketone black and a binder polyvinylidene fluoride (PVDF) in a ratio of 8:1:1 (wherein 200 mg of reduced graphene oxide electrode material, 25 mg of conductive agent ketone black and 25 mg of binder PVDF), and an appropriate amount of organic solvent N-methylpyrrolidone (NMP) is added, and the mixture is ground to obtain a uniform viscous slurry;
[0043] (6) The uniform viscous slurry prepared in (5) was evenly applied on both sides of a 50 μm thick graphite paper using a 400 μm thick doctor blade and dried in a vacuum oven for 24 hours;
[0044] (7) The dried graphite paper coated with the sticky slurry prepared in (6) above (such as Figure 5As shown) are placed under laser etching to produce interdigitated electrodes (such as Figure 6 ), and the interdigitated electrodes (shown in Fig. Figure 7 As shown) assembled into zinc ion microcapacitors (as shown Figure 8 As shown), the electrolyte is zinc trifluoromethanesulfonate (Zn(CF3SO3)2) electrolyte;
[0045] (8) The assembled zinc ion microcapacitors were tested on an electrochemical workstation (CHI760E, Chenhua) for performance. Linear cyclic voltammetry (CV) and constant current charge and discharge (GCD) tests were performed. The performances were as follows: Fig. 9 and Fig.10 shown.
[0046] Example 2
[0047] (1) A monolayer graphene oxide solution (mass fraction of 0.96%) was placed in a 50 ml reactor, and hydrothermally synthesized at 90° C. for 3 hours and then at 180° C. for 6 hours to obtain a reduced graphene oxide block, such as Fig.11 As shown;
[0048] (2) taking the reduced graphene oxide block synthesized above, placing it in an oven for heating and shrinking (heating and shrinking at 90° C. for 8 hours), and obtaining a reduced graphene oxide block after heating and shrinking, such as Fig.12 As shown;
[0049] Steps (3) to (8) are the same as in Example 1, and the performance test of the assembled zinc ion microcapacitor is completed. Fig.13 shown.
[0050] Example 3
[0051] (1) A single-layer graphene oxide solution (mass fraction of 0.9%) was placed in a 50 ml reactor, and hydrothermally synthesized at 100° C. for 2.5 hours and then at 180° C. for 6 hours to obtain a reduced graphene oxide block, such as Fig.14 As shown;
[0052] (2) taking the reduced graphene oxide block synthesized above, placing it in an oven for heating and shrinking (heating and shrinking at 110° C. for 7 hours), and obtaining a reduced graphene oxide block after heating and shrinking, such as Fig.15 As shown;
[0053] Steps (3) to (8) are the same as in Example 1, and the performance test of the assembled zinc ion microcapacitor is completed. Fig.16 shown.
[0054] In summary, the invention includes but is not limited to the above embodiments. Any equivalent substitution or partial improvement made under the spirit and principle of the invention shall be deemed to be within the protection scope of the invention.
Claims
1. A method for preparing an active electrode material with a highly dense structure, characterized in that: The method steps include: (1) placing a monolayer graphene oxide solution into a reactor for hydrothermal reaction to obtain a reduced graphene oxide block; (2) heating and shrinking the reduced graphene oxide block at 90 to 110° C. for 7 to 8 hours; (3) crushing and grinding the reduced graphene oxide block after heating and shrinking into powder, and then ball milling; (4) After the ball milling is completed, the reduced graphene oxide powder is sieved to obtain an active electrode material with a highly dense structure.
2. The method for preparing an active electrode material with a high-density structure according to claim 1, characterized in that: In step (1), the mass fraction of the single-layer graphene oxide solution is 0.9% to 1%.
3. The method for preparing an active electrode material with a high-density structure according to claim 1 or 2, characterized in that: In step (1), during the hydrothermal process, the hydrothermal synthesis is firstly carried out at 90-100° C. for 2.5-3 hours, and then at 170-190° C. for 5-7 hours.
4. The method for preparing an active electrode material with a high-density structure according to claim 1, characterized in that: In step (3), during ball milling, the ball-to-material ratio is 2 to 3:1, the rotation speed is 100 to 150 rpm, and the time is 1 to 2 days.
5. The method for preparing an active electrode material with a high-density structure according to claim 1, characterized in that: In step (4), a 0.1 mm standard mesh screen is used for sieving to screen out reduced graphene oxide powder with a pore size less than 0.1 mm.
6. An active electrode material with a highly dense structure, characterized in that: It is prepared by the method according to any one of claims 1 to 5.
7. The active electrode material with a high-density structure according to claim 6, characterized in that: The tap density of the electrode material is 0.9 to 1 g / cm 3 .
8. A miniature zinc ion capacitor, characterized in that: The electrode material of the capacitor adopts an active electrode material with a high-density structure as described in claim 6 or 7.