Preparation method of matryoshka-like porous carbon material and application of matryoshka-like porous carbon material to high-performance potassium ion hybrid capacitor

Abstract

This invention belongs to the field of supercapacitor technology. It discloses a method for preparing a Russian nesting doll-shaped porous carbon material and its application in a high-performance potassium-ion hybrid capacitor. The method includes simultaneously adding dihydrazine malonate and potassium hydroxide in a 1:1 molar ratio to a ball mill, grinding and aerating for at least 30 minutes, and transferring the resulting powder into a tube furnace under a N2 atmosphere at 2... o C min ‑1 Heating rate to 800 o C was calcined for 0.5 hours to obtain the carbonized product, which was then treated with deionized water and HCl (1 mol L). ‑1 The carbonized products were washed multiple times and freeze-dried for two days to obtain the final product. A potassium-ion hybrid capacitor assembled using Russian nesting doll-shaped porous carbon as the negative electrode and activated carbon as the positive electrode exhibits high energy density, ultra-high power output, and long cycle life, highlighting the superiority of the Russian nesting doll-shaped porous structure. This invention is simple to operate and environmentally friendly, and provides important guidance for the design of three-dimensional pore structures, especially multi-channel pore structures.

Description

Technical Field

[0001] This invention belongs to the field of supercapacitor technology. Specifically, it relates to the technical field of potassium-ion hybrid capacitors. More particularly, it relates to a method for preparing a Russian nesting doll-like porous carbon material and its application in high-performance potassium-ion hybrid capacitors. Background Technology

[0002] High-energy-density lithium-ion batteries and high-power-density supercapacitors are widely used as the primary energy source for modern portable electronics and electric vehicles. Typically, alkali metal batteries can meet the energy density requirements of electric vehicles but cannot meet the requirements for short-term charging. Supercapacitors, however, exhibit the opposite situation. In short, electronic devices with high energy density, high power density, and long cycle life are becoming increasingly urgent. Hybrid-ion capacitors are a novel type of storage device that combines battery-type and capacitor-type electrodes, meeting requirements while providing high energy at high power without sacrificing lifespan. Among them, potassium-ion hybrid capacitors have attracted much attention due to their low cost, shell abundance far exceeding that of lithium, and lower redox potential. In particular, hydrated K ions have the smallest Stokes radius (3.6 Å), while Li ions have a lower Stokes radius. + and Na + The smallest Stokes radii (4.8 Å and 4.6 Å) indicate that hydrated K ions possess strong transport properties in aqueous solutions. More notably, aqueous electrolyte charging devices meet the inherent requirements of safety and low cost, but suffer from low capacity. Despite some progress, reports on aqueous potassium ion hybrid capacitors remain scarce.

[0003] In recent years, carbonaceous materials have become a research hotspot in potassium ion systems due to their diverse structures, low cost, good physical / chemical stability, large specific surface area, and excellent electrolyte channels. Based on this, dual-carbon potassium ion hybrid capacitors (DC-PIHCS) using carbon materials as both cathode and anode have emerged as a promising alternative due to their extremely low total equipment cost and competitive Kk ratio. + Storage performance and inherent long-term cycle stability make it the most promising for industrial applications. However, the undeniable fact is that a larger K... + radius (K) + Li is 1.38. + The presence of a cation species (Na₂O₃, Na₂O₃, Na₂O₃) significantly hinders the intercalation behavior of the anode material, leading to slow kinetics and insufficient power density. Worse still, the significant volume expansion (up to 60%) causes carbon framework structural failure and significant capacity degradation, which is detrimental to extending lifetime. To address these challenges, developing suitable host materials with satisfactory performance is crucial for DC-PIHCS. To overcome these obstacles, cation species (Na₂O₃, Na ... + K + Al 3+Pre-intercalation is an important strategy that enables carbon anodes to accommodate large-sized K atoms. + This promotes carrier dynamics and ensures structural stability. Furthermore, the pore structure also affects K... + The migration behavior of potassium ions is a key factor. It has been reported that carbon-based anode materials with porous structures can withstand large volumetric strains, providing a good pathway for rapid mass transport and exposing a large number of active sites for alkali metal ion storage. This is typically followed by a large surface area, usually contributed by the porous framework, which may contribute to improved reversible capacity and rate performance due to adsorption storage mechanisms. Inevitably, a large specific surface area often leads to a wide operating voltage range and a limited initial coulombic efficiency, thus limiting practical performance. Controlling pore size is another effective method to optimize the potassium storage performance of carbonaceous materials. Studies have shown that electronic properties related to pore size are important for potassium storage behavior, such as capacity, stability, and rate capability.

[0004] Various pore structure engineering techniques, such as top-down (e.g., mechanical cutting and (electro)chemical exfoliation) and bottom-up (e.g., supramolecular self-assembly and growth on hard templates / substrates), are employed to design porous carbons with well-defined pore nanostructures. However, controlling pore structures is fraught with challenges, as most pores are limited to relatively disordered or monomorphic models due to the often random working of the activators and templates used to form pores. Compared to monomorphic models, pore structures in nanopores, such as Russian doll-like pores, can lead to improved physicochemical properties due to enhanced accessibility of active centers and spatiotemporal control in an independent three-dimensional space. To date, Russian doll structures have mainly focused on coordination compounds, in-plane fullerenes, etc., but are relatively rare in nanopore structures. Although carbon with multimodal pore structures is easy to conceive, such fine structures are considered a formidable synthetic challenge. By employing simple nanostructure engineering strategies, it is hoped that ideal porous carbons with controllable porosity and ordered structures can be developed.

[0005] Based on the above analysis, the problems and shortcomings of the existing technology are as follows: In the field of potassium ion hybrid capacitors, a large K... + The radius significantly hinders the intercalation behavior of the anode material, resulting in slow kinetics and insufficient power density. Significant volume expansion (up to 60%) leads to carbon framework failure and significant capacity degradation.

[0006] The difficulty in solving the above problems and defects lies in the fact that controlling the pore structure is a formidable synthetic challenge. Since the activators and templates used to form pores are usually random, most pores are limited to relatively disordered or monolithic models.

[0007] The significance of addressing the above problems and shortcomings is that, compared to a single mode, the Russian nesting doll-like pores, due to enhanced accessibility of active centers and spatiotemporal control in an independent three-dimensional space, can lead to improved physicochemical properties. By employing simple nanostructure engineering strategies, it is hoped that ideal porous carbon anodes with controllable porosity and ordered structures can be developed for realizing aqueous potassium-ion hybrid capacitors with high energy density, high power density, excellent cycle stability, and high safety. Summary of the Invention

[0008] To overcome the problems existing in related technologies, this invention provides a method for preparing Russian nesting doll-shaped porous carbon materials and their application in high-performance potassium ion hybrid capacitors.

[0009] This invention is achieved as follows: the preparation method of the Russian nesting doll porous carbon material includes:

[0010] First, add dihydrazine malonate and potassium hydroxide to a ball mill at a 1:1 molar ratio, and grind and blow oxygen for more than 30 minutes.

[0011] The resulting powder was transferred into a tube furnace and incubated at 2°C for 2 min under a N2 atmosphere. -1 The product was heated to 800℃ and calcined for 0.5 hours to obtain a carbonized product.

[0012] Then use deionized water and HCl (1 mol L). -1 The carbonized products were washed multiple times and then freeze-dried for two days to obtain the final K. + Pre-intercalated Russian nesting doll porous carbon material.

[0013] Another object of the present invention is to assemble a hybrid potassium-ion capacitor device, wherein the device uses Russian nesting doll porous carbon material as the negative electrode and activated carbon as the positive electrode, and the separator and electrolyte used are glass fiber membrane and 30 mol / L electrolyte, respectively. -1 CH3COOK.

[0014] Combining all the above technical solutions, the advantages and positive effects of this invention are as follows:

[0015] Choosing dihydrazine malonate as the carbon source is advantageous because it has a high heteroatom content (66.67 wt%) and a low boiling point (554 wt%). o C) and self-generated layered stacking characteristics. Abundant porous structures can be generated during the fluidized bed carbonization process using potassium hydroxide as an activator. The final sample exhibits a pre-intercalated structure and novel Russian doll-like pores. Appropriate pre-intercalation facilitates the insertion and diffusion of potassium ions, while the increased interlayer spacing alleviates the relatively bulky K+. +The volume expansion induced by embedding improves structural stability and coulombic efficiency; the interconnected carbon layers with hierarchical porosity ensure structural integrity while accommodating different K values. + This invention enhances ion storage kinetics and improves highly reversible characteristics. Furthermore, the aqueous potassium-ion hybrid capacitor based on Russian nesting doll-shaped porous carbon materials and activated carbon exhibits high energy density, ultra-high power output, and long cycle life. Moreover, this invention provides a feasible approach for designing Russian nesting doll-shaped pores, offering significant guidance for the design of three-dimensional pore structures, particularly multi-channel pore structures, and opening up opportunities for applying porous carbon anodes to aqueous potassium-ion hybrid capacitors. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a flowchart of the preparation method of the Russian nesting doll porous carbon material provided in the embodiments of the present invention.

[0018] Figure 2 This is a scanning electron microscope image of the prepared material provided in the embodiments of the present invention.

[0019] Figure 3 This is a pore size distribution diagram of the material prepared according to the embodiments of the present invention.

[0020] Figure 4 This is an X-ray photoelectron spectrum of the prepared material provided in the embodiments of the present invention.

[0021] Figure 5 This is a schematic diagram of the assembly of the aqueous potassium ion hybrid capacitor prepared according to the embodiments of the present invention, and the corresponding Regone plots of energy density and power density characterization. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0023] To address the problems existing in the prior art, this invention provides a method for preparing porous carbon anode materials and their application in high-performance potassium-ion hybrid capacitors. The invention is described in detail below with reference to the accompanying drawings.

[0024] like Figure 1As shown, the method for preparing the porous carbon anode material provided by the present invention includes the following steps:

[0025] S101: Dihydrazine malonate and potassium hydroxide are added to the ball mill at a 1:1 molar ratio, followed by grinding and aeration for more than 30 minutes;

[0026] S102: The obtained powder is transferred into a tube furnace and heated under a nitrogen atmosphere at 2... o C min -1 Heating rate to 800 o C was then calcined for 0.5 hours to obtain the carbonized product;

[0027] S103: Then, use deionized water and HCl (1 mol L). -1 The carbonized product was washed multiple times and then freeze-dried for 2 days to obtain the final product.

[0028] The method for preparing porous carbon anode materials provided by this invention can also be implemented using other steps by those skilled in the art. Figure 1 The method for preparing porous carbon anode material provided by the present invention is merely a specific embodiment.

[0029] The invention will be further described below with reference to experimental data and results.

[0030] Figure 2 This is a scanning electron microscope image of the prepared material provided in the embodiments of the present invention.

[0031] Figure 3 This is a pore size distribution diagram of the material prepared according to the embodiments of the present invention.

[0032] Figure 4 This is an X-ray photoelectron spectrum of the prepared material provided in the embodiments of the present invention.

[0033] Figure 5 The energy density and power density Regon plots are for characterizing the performance of the aqueous potassium ion hybrid capacitor prepared according to the embodiments of the present invention.

[0034] This invention demonstrates, through scanning electron microscopy (SEM) images, that porous carbon possesses a highly abundant pore structure, and through pore size distribution maps, reveals the simultaneous presence of micropores, mesopores, and macropores. X-ray photoelectron spectroscopy (XPS) indicates a high oxygen content and the successful introduction of potassium. The assembled aqueous potassium-ion hybrid capacitor provides 157.29 Wh / kg. -1 Its ultra-high energy density, and up to 14 kW kg -1 Excellent power density output.

[0035] The above description is merely a specific embodiment of the present invention intended to demonstrate the practical application of the technical solution provided by the present invention, and should not be construed as a limitation on the scope of protection of the present invention. However, the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by any person skilled in the art within the scope of the technology disclosed in the present invention, within the spirit and principles of the present invention, should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a Russian nesting doll-shaped porous carbon material, characterized in that, The method includes simultaneously adding dihydrazine malonate and potassium hydroxide in a 1:1 molar ratio to a ball mill, grinding and aerating for at least 30 minutes, and then transferring the resulting powder into a tube furnace and incubating at 2 °C for at least 1 minute under a N2 atmosphere. -1 The mixture was heated to 800 °C and calcined for 0.5 hours to obtain a carbonized product, which was then treated with deionized water and 1 mol L... -1 The carbonized product was washed multiple times with an HCl solution and then freeze-dried to obtain the final product.

2. The method for preparing a Russian nesting doll-shaped porous carbon material as described in claim 1, characterized in that, The carbonization product was treated with deionized water and 1 mol L -1 The HCl solution was washed multiple times and then freeze-dried for 2 days to obtain the final product.

3. An electrode, characterized in that, The electrode is prepared by the method of the Russian nesting doll-shaped porous carbon material according to any one of claims 1 to 2, characterized in that the Russian nesting doll-shaped porous carbon material, acetylene black and polyvinylidene fluoride are dispersed in 1-methyl-2-pyrrolidone solvent at a mass ratio of 8:1:1, and then the mixture is coated on copper foil to prepare the electrode material.

4. An electrode assembly using the electrode material described in claim 3 as the negative electrode and activated carbon as the positive electrode, 30 mol L... -1 CH3COOK is used as a potassium-ion mixed capacitor device with electrolyte.

5. An electric vehicle energy system equipped with the potassium-ion hybrid capacitor of claim 4.

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