CN115522244B - Preparation method of high-safety sodium storage material based on antimony-bismuth nano array - Google Patents

Abstract

The invention provides a preparation method of a high-safety sodium storage material based on an antimony-bismuth nano array, and belongs to the field of novel chemical power sources. The main point is to solve the practical problem that the existing negative electrode material cannot achieve both high capacity and long-cycle stability. The main scheme includes that a rice spike-shaped nano wall array structure with uniform heterogeneous interface distribution grows on a copper substrate, bi, sb and Se are simultaneously combined into the nano wall in the electrodeposition process, so that an array structure of SbBi alloy with uniform dispersed phases and metal selenide Bi ₂Se₃ and Sb ₂Se₃ is formed, the heterogeneous interfaces among different phases are uniformly distributed in the whole structure, na ⁺ diffusion is facilitated, electron conduction is promoted, and the rate capability of the material is improved. The self-supporting three-dimensional structure brings extra buffer space, can alleviate side effects brought by severe volume expansion, and greatly improves the structural stability of the whole nano array, thereby effectively prolonging the cycle life of the material.

Description

A method for preparing a highly safe sodium storage material based on antimony-bismuth nanoarray

Technical Field

The present invention belongs to the field of preparation of negative electrode materials for sodium ion batteries and novel chemical power sources for battery applications, and specifically relates to a method for preparing a highly safe sodium storage material based on an antimony-bismuth nanoarray.

Background technique

As my country proposes its dual carbon goals (carbon peak and carbon neutrality) to address climate change, it becomes increasingly important to seek renewable green and clean energy. Lithium-ion batteries are considered one of the most successful energy storage devices at present. Due to the increasing demand in recent years, the problem of lithium resource depletion has arisen. Therefore, it has become an urgent issue to find an alternative energy storage battery system with more abundant reserves, lower prices, and similar working principles to lithium-ion batteries, and sodium ions have become a potential choice. Although sodium ions have cost and resource advantages, their practical application still faces many challenges due to their large ion radius and high potential. One of the key challenges is the lack of high-capacity and high-stability negative electrode materials.

Among the numerous negative electrode materials, materials with alloying sodium storage mechanism, such as antimony-based materials (Sb: 660 mAh g ^-1 , _{Sb2Se3 :} 670 mAh g ^-1 ), have attracted much attention due to their high theoretical capacity and suitable sodium storage potential (~0.4 V). However, due to the alloying/de-alloying reaction mechanism of multi-electron transfer, the volume of antimony materials changes severely (~390%) during the charge and discharge process, which easily generates large structural stress, causing the active materials to pulverize and fall off and lose electrical contact with the current collector, resulting in the inactivation of the electrode materials. In addition, pulverization will expose more active interfaces and cause the continuous formation of SEI film, which will consume sodium ions and reduce the cycle performance.

The conventional method to alleviate the volume expansion of antimony-based materials during sodium storage and improve the cycle stability is to compound antimony with conductive carbon, but this method is complicated and has poor capacity performance. For example, the Chinese patent (application number: 201911110217.7) prepared a nitrogen-doped antimony-carbon composite material with a discharge capacity of only 325 mAh g ^-1 after 100 cycles at a current of 0.5 A mg ^-1 . In addition to compounding with carbon materials, combining binary alloys with other elements is also one of the methods to improve the stability of antimony-based materials. The introduction of a second metal can serve as a buffer layer to reduce the volume change during the electrode cycle. For example, the Chinese patent (CN201611002285.8) introduced inactive Cu to form a binary alloy with antimony, and in situ generated unbonded antimonide copper on the surface of a copper foil. Although the material did not show obvious attenuation after 100 cycles, its reversible capacity was low. A Chinese patent (CN201680005500.1) discloses a bismuth-antimony negative electrode for a rechargeable sodium-ion battery pack, whose first de-sodiumization capacity is 428 mAh g ^-1 , and the capacity decays to 113 mAh g ^-1 after 50 cycles, and the stability performance is poor.

Summary of the invention

The purpose of the present invention is to solve the practical problem that existing negative electrode materials cannot achieve both high capacity and long cycle stability.

In order to solve the above technical problems, the present invention adopts the following technical means:

The preparation method based on antimony/bismuth self-supporting nanoarray comprises the following steps:

Step 1: Place the copper sheet in alcohol, dilute oxalic acid, and deionized water in turn, then ultrasonicate in alcohol and dry for later use;

Step 2: Mix 20 mL of water, 30 mL of alcohol and 50 mL of ethylene glycol. Then add 0.025 mol/L of antimony chloride (SbCl ₃ ), 0.02 mol/L of bismuth chloride (BiCl ₃ ), 0.005-0.015 mol/L of selenious acid (H ₂ SeO ₃ ) and 0.28 mol/L of ethylenediamine hydrochloride (C ₂ H ₉ ClN ₂ ), and stir the solution thoroughly on a magnetic stirring table to obtain solution A.

Step 3: Place the dried copper sheet as the working electrode in the electrolytic cell of the three-electrode system, add the solution A prepared in step 2, and react for 20 minutes at a constant current of 4-8 mA cm ^-2 . After the deposition is completed, take it out and further wash it with deionized water and alcohol to obtain a self-supporting nanoarray with antimony-bismuth alloy and antimony selenide/bismuth;

Step 4: placing the copper sheet deposited with the reactants in step 3 into a tube furnace for mild heat treatment, and annealing at 200°C for 1 hour to obtain the final composite nanoarray product, wherein the optimal composite nanoarray product is a rice-ear-shaped nanowall array structure SbBi-Bi ₂ Se ₃ -Sb ₂ Se ₃ (SbBi-Se) with uniform heterogeneous interface distribution;

The present invention also provides an application of an antimony bismuth selenide/bismuth self-supporting nanoarray, wherein an antimony bismuth alloy and an antimony bismuth selenide/bismuth composite material self-supporting nanoarray is used as a negative electrode of a sodium ion battery to be assembled into a button battery, and a temperature sensor is introduced to detect temperature when assembling the button battery.

The method for preparing the secondary battery comprises the following steps:

Step 1: Assemble button cell: assemble the negative electrode cover, spring, gasket, metal sodium sheet, diaphragm, electrolyte, array electrode, temperature sensor, and positive electrode cover in sequence. The sealing pressure is 40-60 kgf cm ^-2 , and the compaction time is 5-10 s.

In the process of electrodeposition _{, since Sb, Bi and Se sources are added to the electrolyte at the same time for co-deposition, the optimal sample obtained is composed of three phases of evenly distributed SbBi, Bi2Se3 and Sb2Se3 . At the} same time, there are a large number of heterogeneous interfaces between the three phases, which can maximize the advantages of these interfaces, enhance the efficiency of sodium ion and electron transmission, and maintain the stability of the electrode structure. In addition, since the array electrode has a three-dimensional nanowall structure, it can not only buffer the volume expansion during the charge and discharge process, but also eliminate the need for the use of conductive agents and binders during electrode preparation, simplifying the battery assembly process, avoiding the introduction of inactive substances, and improving the energy density of the electrode. It is a sodium ion battery negative electrode material with application potential.

In summary, due to the adoption of the above technical solution, the present invention has at least the following advantages:

The present invention uses constant current electrodeposition technology to directly grow a nano-array structure having a composite material of antimony bismuth (SbBi) alloy, bismuth selenide (Bi ₂ Se ₃ ), and antimony selenide (Sb ₂ Se ₃ ) on a copper substrate. By introducing the corresponding high-capacity selenide into the SbBi alloy, a higher capacity can be provided for the electrode. At the same time, the heterogeneous interface between the selenide and the alloy is utilized to induce the generation of a built-in electric field, thereby improving the transmission efficiency of charges and electrons and enhancing the structural stability of the material. The electrode is detected in real time using an implantable temperature sensor, and it is found that it has a stable operating temperature and a small temperature fluctuation, which reflects a higher safety.

Second, the array is grown directly on a metal copper sheet without the need for additional conductive agents and adhesives. The electrode preparation method is simple and easy to operate. The required equipment is simple and easy to control, and can be mass-produced industrially.

3. The three-dimensional ordered nanowall structure provides a channel for the rapid transmission of sodium ions and a buffer space for volume expansion, thereby improving the cycling stability of the electrode.

4. The evenly distributed multiphase heterogeneous interface increases the diffusion rate of sodium ions and enhances the electronic conductivity, making the electrode exhibit better rate performance.

5. The introduction of built-in temperature sensor The in-situ test results show that the SbBi-Se array does not show obvious temperature fluctuations during the cycle process and has high safety.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a scanning electron microscope image of the sample obtained in Example 1;

FIG2 is a scanning electron microscope image of the sample obtained in Example 2;

FIG3 is a scanning electron microscope image of the sample obtained in Example 3;

FIG4 is a scanning electron microscope image of the sample obtained in Example 4;

FIG5 is a scanning electron microscope image of the sample obtained in Example 5;

FIG6 is a transmission electron microscope image of the sample obtained in Example 1;

FIG7 is the X-ray diffraction pattern obtained in Examples 1 and 5;

FIG8 is an X-ray photoelectron spectrum of the sample obtained in Example 1;

FIG9 is a comparison of the cycles obtained in Examples 1 and 5;

FIG10 shows different rate cycles obtained in Examples 1 and 5;

FIG11 is the temperature sensor data obtained in Examples 1 and 5;

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with the implementation modes and the accompanying drawings.

Example 1

A 0.5 cm × 2 cm copper sheet was placed in alcohol, dilute oxalic acid, and deionized water in turn, and then ultrasonicated in alcohol for 15 minutes and dried for later use; 20 mL of water, 30 mL of alcohol, and 50 mL of ethylene glycol were mixed to form solution A. 0.025 M antimony chloride (SbCl ₃ ), 0.02 M bismuth chloride (BiCl ₃ ), 0.01 M selenious acid (H ₂ SeO ₃ ) and 0.28 M ethylenediamine hydrochloride (C ₂ H ₉ ClN ₂ ) were placed in solution A and stirred thoroughly on a magnetic stirring table; the dried copper sheet was used as the working electrode and placed in an electrolytic cell of a three-electrode system, and the prepared electrolyte was added. The reaction was carried out at a constant current of 5.2 mA cm ^-2 for 20 minutes. After the deposition was completed, the copper sheet was taken out and further cleaned with deionized water and alcohol for 15 minutes; the deposited copper sheet was placed in a tube furnace for mild heat treatment and annealed at 200 ºC under argon for 1 hour to obtain an antimony bismuth-bismuth selenide-selenide composite material (SbBi-Se) nanoarray with uniform heterogeneous interface distribution.

The obtained materials are assembled into a button battery, which is composed of a negative electrode cover, a spring, a gasket, a metal sodium sheet, a diaphragm, an electrolyte, an array electrode, a temperature sensor, and a positive electrode cover. The sealing pressure is 40-60 kgf cm ^-2 , the compaction time is 5-10 s, and the electrolyte is 1 M NaPF ₆ in dimethyl ether.

After the assembled battery was left to stand for 8 hours, the charge and discharge test was carried out in the voltage window of 0.01-2.5 V. The results in Figure 5 show that the reversible capacity of the SbBi-Se electrode reached 525 mAh g ^-1 at a current density of 0.21 A g ^-1 . Figure 6 shows that 94% of the capacity can be retained after 100 cycles at a current density of 0.7 A g ^-1 . In addition, the electrode also exhibits excellent rate performance, with reversible specific capacities of 516, 512, 499 and 480 mAh g ^-1 at current densities of 0.35, 0.7, 1.4 and 3.5 A g ^-1 , respectively, and high cycle stability is maintained at each current density.

Example 2

The method for cleaning the copper sheet in Example 1 was used to prepare the copper sheet for deposition, and the same electrolyte as in Example 1 was used as the deposition solution. In contrast, a current density of 4 mA cm ^-2 different from that in Example 1 was used for deposition, and samples with different morphologies were obtained. The morphology of the deposited sample showed a layer of granular film, and there was no 3D structural void space like in Example 1 to allow free deformation of the electrode during the sodium storage cycle, and the penetration of the electrode liquid was limited, which was not conducive to improving stability.

Example 3

The method for cleaning the copper sheet in Example 1 was used to prepare the copper sheet for deposition, and the same electrolyte as in Example 1 was used as the deposition solution. In contrast, a current density different from that in Example 1, 8 mA cm ^-2 , was used for deposition to obtain samples with different morphologies. The samples exhibited a certain lamellar structure, but a large portion of the material was agglomerated. Compared with Example 1, the samples under this condition were not as neat, regular, and arranged with void spaces as in Example 1. The agglomeration of the samples would affect the further storage of the material, and was therefore not conducive to improving stability.

Example 4

The method for cleaning the copper sheet in Example 1 was used to prepare the copper sheet for deposition, and an electrolyte almost the same as that in Example 1 was used as the deposition solution, with the difference being that 0.015 M selenious acid (H ₂ SeO ₃ ) was used, and samples with different morphologies were obtained. The samples exhibited a structure similar to that of Example 1, with the difference being that the deposited samples under this condition had only a small amount of voids, and most of them grew together. A large amount of thin film phenomena would increase the barrier to charge transfer and limit the penetration of the electrolyte, so the structure was not conducive to sodium storage.

Example 5

The copper sheet for deposition was prepared by the method of cleaning the copper sheet in Example 1, and an electrolyte almost the same as that in Example 1 was used as a deposition solution, except that 0.005 M selenious acid (H ₂ SeO ₃ ) was used. Finally, the morphology was observed.

Example 6

The copper sheet for deposition was prepared by the method of cleaning the copper sheet in Example 1, and an electrolyte almost the same as that in Example 1 was used, except that 0 M selenious acid (H ₂ SeO ₃ ) was used as the deposition solution. The dried copper sheet was placed in an electrolytic cell of a three-electrode system and the prepared electrolyte was added. The reaction was carried out for 20 minutes at a constant current of 6.6 mA cm ^-2 . After the deposition was completed, the copper sheet was taken out and further washed with deionized water and alcohol for 15 minutes. The deposited copper sheet was placed in a tube furnace for mild heat treatment and annealed at 200 ºC under argon for 1 hour to obtain a binary alloy. The deposited sample showed the shape of a granular film. In comparison, the unique structure grown in Example 1 will be more conducive to sodium storage.

In order to verify its sodium storage performance, the obtained material was assembled into a button cell for performance testing as in Example 1. The results in Figure 10 show that the reversible specific capacities at current densities of 0.35, 0.7, 1.4 and 3.5 A g ^-1 are 382, 334, 299 and 263 mAh g ^-1 , respectively.

FIG1 is a scanning electron microscope image of the uniform heterogeneous interface distribution nanowall array obtained in Example 1, which shows a rice-ear-shaped nanowall array structure at the top. The successful preparation of SbBi-Se is illustrated by the transmission electron microscope in FIG6, the X-ray diffraction pattern in FIG7 and the X-ray photoelectron spectrum in FIG8. FIG9 is a comparison of the charge and discharge cycles obtained in Examples 1 and 5. It can be found that Example 1 exhibits better cycle stability, with 94% of the capacity retained after 100 cycles at a current density of 0.7 A g ^-1 . In addition, the results in FIG10 show that the electrode also exhibits excellent rate performance, with reversible specific capacities of 516, 512, 499 and 480 mAh g ^-1 at current densities of 0.35, 0.7, 1.4 and 3.5 A g ^-1 , respectively, and maintains a high cycle stability at each current density. FIG11 is the temperature sensor data of Examples 1 and 5. During the long-term temperature test, the electrode of Example 1 is very stable, with no obvious temperature fluctuations, showing a high safety potential.

Claims (4)

1. A method for preparing a high-safety sodium storage material based on antimony-bismuth nanoarray, characterized in that it comprises the following steps: Step 1: Place the copper sheet in alcohol, dilute oxalic acid, and deionized water in turn, then ultrasonicate it in alcohol, and dry it for later use; Step 2: Mix 20 mL of water, 30 mL of alcohol and 50 mL of ethylene glycol, then add 0.025 mol/L of antimony salt, 0.02 mol/L of bismuth salt, 0.005 - 0.015 mol/L of selenium source and 0.28 mol/L of ethylenediamine hydrochloride, and stir the solution thoroughly on a magnetic stirring table to obtain solution A. Step 3: The dried copper sheet is used as a working electrode, placed in an electrolytic cell of a three-electrode system, and the solution A prepared in step 2 is added, and the reaction is carried out at a constant current of 4-8 mA cm ^-2 for 20 minutes. After the deposition is completed, the copper sheet is taken out and further washed with deionized water and alcohol to obtain a copper sheet with an antimony-bismuth alloy and an antimony selenide/bismuth self-supporting nanoarray; Step 4: Place the copper sheet deposited with the reactants in step 3 into a tube furnace for mild heat treatment and anneal at 200 ºC in argon for 1 hour to obtain the final composite nanoarray product. 2. A method for preparing a high-safety sodium storage material based on an antimony-bismuth nanoarray according to claim 1, characterized in that the antimony salt is antimony chloride, the bismuth salt is bismuth chloride, and the selenium source is selenious acid. 3. The method for preparing a high-safety sodium storage material based on antimony-bismuth nanoarray according to claim 1, characterized in that the condition in step 4 is 200 ºC and the heating rate is 2 ºC min ^-1 . 4. A battery, characterized in that the composite nanoarray product prepared by the method for preparing a high-safety sodium storage material based on antimony-bismuth nanoarray according to any of claims 1 to 3 is used as the negative electrode of the sodium ion battery.