CN110277557A - Preparation method and sodium storage performance of multi-element doped, high specific surface area, fibrous biocarbon materials - Google Patents

Abstract

The invention provides a method for preparing a sodium ion battery electrode material by using carbonized marine biological material as a precursor. Its biggest feature is that the multi-element doped fibrous bio-carbon electrode material is obtained only through simple pre-carbonization and carbonization treatment without adding an activator. In the preparation method, the pretreated shark bone was first calcined at 500 °C for 2 h for pre-carbonization in the atmosphere of _N2 , and then carbonized at 900 °C for 2 h. The obtained product is acid-washed, washed with deionized water until neutral, and dried. The biocarbon material prepared by the method has the characteristics of multi-element doping, high specific surface area and fibrous structure, and the method has the advantages of low cost, simplicity and easy mass production. At the same time, the material exhibits excellent electrochemical performance as an electrode material for sodium-ion batteries.

Description

Preparation method and storage of multi-element doped, high specific surface area, fibrous biocarbon materials Sodium Properties

technical field

The invention belongs to the field of chemical energy materials, and provides a method for preparing multi-element doped, high specific surface area, fibrous biological carbon materials by carbonization at high temperature. Doped, high specific surface area, fibrous bio-carbon material, which can be used as a negative electrode for sodium-ion batteries.

Background technique

Lithium-ion batteries have the advantages of high energy density and long cycle life and occupy an important position in the fields of portable electronic devices and new energy vehicles. However, lithium reserves on Earth are limited and unevenly distributed. With the rapid development of the new energy field and the electric vehicle industry, the development of lithium-ion batteries is bound to be severely restricted by the shortage of lithium resources. Therefore, research and development of secondary batteries with extensive resources and low price that can replace lithium-ion batteries to meet the rapidly growing demand for energy storage has become a hot research topic at home and abroad.

Metal sodium, which has similar physical and chemical properties to lithium, is abundant in reserves, widely distributed, and inexpensive. Therefore, the development of sodium-ion batteries in energy storage has attracted much attention in recent years. As one of the main electrode materials for current sodium-ion batteries, carbon materials have attracted extensive attention due to their high specific surface area, tunable pore structure, excellent electrical conductivity, environmental friendliness, and low cost. In order to improve the performance of carbon materials, chemical activation and heteroatom doping are usually adopted. The method is as follows: the sample to be treated is mixed with an activator (mainly including: KOH, NaOH, K ₂ CO ₃ , Na ₂ CO ₃ , KHCO ₃ , NaHCO ₃ , etc.), heated for a second time under the protection of inert gas, and treated for a certain period of time , the obtained sample was washed many times to obtain a porous carbon structure. The activated carbon material has increased the number of pore sizes and widened the pore size distribution, but the activation has serious damage to the precursor morphology. Second, the activation treatment requires secondary heating, and needs to be heated to a higher temperature, and various chemical activators need to be mixed in the activation process, which may cause pollution to the environment. Another method is to increase the carbon layer spacing by doping heteroatoms in the carbon matrix and improve the insertion and migration of sodium ions in carbon materials, which can effectively improve the sodium storage performance of carbon materials. However, the doping process requires additional introduction of doping reagents and high temperature treatment, which increases the cost.

At present, using cheap biomass waste resources as precursors to prepare carbon materials by pyrolysis carbonization technology has become a very promising method. During the evolution of billions of years, biomass has built a variety of biological structures, which provides a good template for the preparation of porous carbon materials; at the same time, biomass often contains a variety of elemental components, and these heteroatoms are used in the high-temperature carbonization process. It can directly enter the carbon matrix and realize the in-situ doping of heteroatoms in the carbon matrix. Therefore, this patent selects shark bone as the precursor, and prepares N, P, S, O multi-element, high specific surface area, fibrous carbon materials through direct pyrolysis, showing excellent electrochemical performance.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to prepare the carbon material by a simple method with the help of the unique composition and structure of biomass, and make it have better sodium storage performance.

In order to solve the above-mentioned technical problems, the technical scheme adopted in the present invention is:

Take an appropriate amount of _pretreated shark bone, put it into a porcelain boat, and continuously heat up in an N atmosphere, carbonize the precursor, and cool down to obtain a carbon material sample. The sample is washed with dilute hydrochloric acid and/or deionized water to remove impurities, and when the solution is neutral, a fibrous carbon material with high specific surface area and multi-element doped is obtained after drying.

Compared with the prior art, the beneficial effects of the present invention are embodied in:

(1) Marine biomass - shark bone, as a precursor, has the characteristics of easy availability, strong renewable ability, and low price;

(2) In the process of obtaining the electrode material, no activator is added, and the fibrous carbon material with high specific surface area and multi-element doping is only obtained by heating. This simple synthetic route has low production cost, is environmentally friendly and pollution-free, and can be produced in large quantities;

(3) The obtained electrode material exhibits excellent electrochemical performance when applied to the electrode of sodium ion battery.

Description of drawings

FIG. 1 is a scanning electron microscope (SEM) photograph of the multi-element doped, high specific surface area, fibrous carbon material obtained in Example 1.

2 is the nitrogen adsorption-desorption curve of the multi-element doped, high specific surface area, fibrous carbon material obtained in Example 1.

3 is the pore size distribution curve of the multi-element doped, high specific surface area, fibrous carbon material obtained in Example 1.

4 is the X-ray photoelectron spectroscopy (XPS) curve of the multi-element doped, high specific surface area, fibrous carbon material obtained in Example 1.

FIG. 5 is the charge-discharge curve of the multi-element doped, high specific surface area, fibrous carbon material obtained in Example 1 in Application Example 1 at a current density of 0.2Ag ⁻¹ .

Figure 6 shows the multi-element doped, high specific surface area, fibrous carbon material obtained in Example 1. In the application example, 0.2Ag ^-1 , 0.5Ag ^-1 , 1Ag ^-1 , 2Ag ^-1 , 5Ag ^-1 , 10Ag ^-1 current density charge-discharge curve.

FIG. 7 is a charge-discharge curve of the multi-element doped, high specific surface area, fibrous carbon material obtained in Example 1 in Application Example 2 at a current density of 0.2 Ag ⁻¹ .

Detailed ways

The present invention will now be described with reference to the following specific examples, but not limited thereto.

Example 1

The purchased shark bone was boiled in 1M NaOH heated to 90°C for 1 hour, until the flesh on the surface of the shark bone was detached, and a bright white and smooth shark bone was obtained. The shark bone was washed and dried in an oven to obtain a precursor. The dried precursor was placed in a magnetic boat, heated to 500°C at a rate of 2°C min ^-1 in a nitrogen atmosphere, kept at this temperature for 2h, and then continued to heat up to 900°C for 2h. The product was taken out after natural cooling. The product was washed with 3M hydrochloric acid at room temperature for 24 hours, then fully washed with deionized water to remove impurities, and dried at 80 °C to obtain a multi-doped, high specific surface area, fibrous carbon material.

Application example 1

After mixing the obtained sample, conductive agent Super P, and binder (sodium carboxymethyl cellulose, CMC) in a mass ratio of 8:1:1, add water to fully grind, and evenly drop it onto the copper sheet to make an electrode sheet . In this experiment, the performance test is carried out by assembling CR2032 button-type sodium-ion battery cells. In a glove box filled with Ar gas, five items of electrode sheet, separator, lithium sheet, gasket and spring sheet are packaged in a certain order in a certain order. In the battery case, the EC/DEC solution of 1 mol/L NaClO ₄ was added dropwise as the electrolyte. The constant current charge-discharge curve is tested on the blue electricity test system (CT2001A), and the test results are shown in Figure 5 and Figure 6.

As can be seen from Figure 5, in the constant current charge-discharge test of 0.2Ag ^-1 , the multi-element doped, high specific surface area, fibrous carbon material prepared by the present invention is implemented through this process, and the product's first sodium intercalation capacity is 3140.5mAh g ^-1 , the reversible sodium removal capacity is 707mAhg ^-1 , and the discharge capacities after the second and tenth cycles are 665.1mAhg ^-1 and 637.5mAhg ^-1 , respectively, showing a particularly excellent sodium storage performance.

It can be seen from Fig. 6 that the discharge specific capacities are 601mAhg ^- 1 at different current densities of 0.2Ag ^-1 , 0.5Ag ^-1 , 1Ag ^-1 , 2Ag ^-1 , 5Ag ^-1 , 10Ag ^-1 , respectively. 446mAhg ^-1 , 365.4mAhg ^-1 , 282mAhg ^-1 , 212.6mAhg ^-1 , 150.1mAhg ^-1 , showing excellent sodium storage performance.

Application example 2

This application case is the same as application example 1, the difference is that the electrolyte is replaced by the EC/DEC solution of 1 mol/L NaClO ₄ with the DIGLYME solution of 1 mol/L NaCFSO ₃ . As shown in Figure 7, in the constant current charge-discharge test of 0.2Ag ^-1 , the multi-doped, high specific surface area, fibrous carbon material prepared by the present invention is implemented through this process, and the product's first sodium intercalation capacity is 964.2mAh g ^-1 , the reversible sodium removal capacity is 748.3mAhg ^-1 , and the discharge capacities after the second and tenth cycles are 679.3mAhg ^-1 and 651.4mAhg ^-1 , respectively. The cycle Coulomb efficiency increased from 22.51% to 77.6%. While maintaining a particularly high discharge specific capacity, the first cycle Coulomb efficiency increased suddenly.

Claims (6)

1. a kind of method for preparing the biological carbon material of multi-element doping, high-specific surface area, threadiness using shark bone, feature exist In including following step:

(a) raw material selected by is the ocean class fish-bone based on shark bone；

(b) pre-process: shark bone at room temperature for a period of time, for removing the pulp adhered on shark bone, dry by alkali cleaning The smooth shark bone presoma of brilliant white is obtained afterwards；

(c) carbonization and carbonization in advance: the presoma after drying is put into tube furnace, under an inert atmosphere with certain heating Rate is warming up to suitable pre- carburizing temperature, and held for some time, then raises temperature to carbonization temperature and is carbonized；

(d) it cleans: calcined sample is cleaned, sufficiently cleaning removes impurity in dilute hydrochloric acid, deionized water respectively, After solution is washed till neutrality, dry in an oven.

2. the preparation method of the biological carbon material of multi-element doping according to claim 1, high-specific surface area, threadiness, It is characterized in that: in stepb, using marine biomass-shark bone as presoma, being not added with any activator.

3. the preparation method of the biological carbon material of multi-element doping according to claim 1, high-specific surface area, threadiness, It is characterized in that: in step c, in N₂Atmosphere under, pre- carburizing temperature be 500 DEG C, carbonization temperature be 800 ~ 1100 DEG C, heating speed Rate is 2 DEG C of min^-1, soaking time 2h.

4. the preparation method of the biological carbon material of multi-element doping according to claim 1, high-specific surface area, threadiness, Be characterized in that: in step d, sample cleans 24-48h with 3M hydrochloric acid at room temperature after cooling.

5. the preparation method of the biological carbon material of -4 multi-element dopings, high-specific surface area, threadiness according to claim 1, It is characterized in that any activator is not used, obtains a kind of multi-element doping, high-specific surface area, threadiness biology only by calcining Carbon material.

6. the preparation method of the biological carbon material of multi-element doping described in -5, high-specific surface area, threadiness according to claim 1, It is characterized by: the fibrous carbon material can be applied to the negative electrode material of sodium-ion battery, and show as excellent storage sodium performance.