A nanowire structured square tellurium-zinc ion battery positive electrode material, a preparation method and application thereof

Abstract

The application relates to a preparation method of a nanowire structure square acid tellurium zinc ion battery positive electrode material, which comprises the following steps: ultrasonic mixing of tellurium dioxide and square acid to form a white mixed dispersion liquid and pre-reaction by heating; hydrothermal reaction of the mixed dispersion liquid to obtain a crude product; centrifugalization, washing and drying of the crude product to obtain a preliminary product; soaking of the preliminary product into a zinc salt solution for stirring reaction, suction filtration and drying to obtain a final product. The application also relates to a nanowire structure square acid tellurium zinc ion battery positive electrode material and application thereof in a zinc ion battery positive electrode. The nanowire structure square acid tellurium positive electrode material is beneficial to the increase of the contact area of the tellurium positive electrode material and an electrolyte, the promotion of electrochemical reaction kinetics, the complete reaction of the electrode material, the increase of energy density, the avoidance of the problem of the decrease of cycle performance caused by the volume change of the electrode material in the electrochemical reaction process, wide application prospect of the prepared material in the zinc ion battery positive electrode, and the increase of the energy density and cycle stability of the battery.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of preparation of positive electrode materials of zinc ion batteries, and particularly relates to a nanowire structure tetrabutylammonium tetrafluoroborate zinc ion battery positive electrode material and a preparation method and application thereof. BACKGROUND

[0002] In today's society, the continuous consumption of traditional fossil energy is not only not conducive to sustainable development, but also has serious pollution problems for the environment, and new energy and energy storage systems are urgently needed. Batteries have become the focus of attention in recent years due to their efficient energy storage and conversion functions. As the most widely used battery at present, lithium ion batteries have fully played their roles in many fields of human social life. However, lithium ion batteries also have certain environmental pollution and serious safety problems, and are prone to explosion and other dangers. With the continuous strengthening of the concepts of green development and safety, zinc ion batteries with low pollution, low cost and excellent safety using aqueous electrolyte have stood out in the field of energy storage devices and received more and more attention. Metal zinc is abundant in resources, has a low redox potential, uses a safe electrolyte, is non-flammable, non-toxic and has a high theoretical capacity, and thus has great application potential.

[0003] Although zinc ion batteries have many advantages as described above, the energy density problem of zinc ion batteries is still a key factor restricting their practical application. The energy density of zinc ion batteries is mainly determined by the positive electrode material. For example, the capacity of the commonly used MnO2 positive electrode material is about 300 mAh g -1 (calculated based on the mass of active substance MnO2), and the capacity is only 150 mAh g -1 at high rate, and the overall energy density of the device is not high. Although vanadium-based positive electrode materials have higher specific capacity, the voltage window is small and the cycle performance is often poor. Therefore, exploring new zinc ion battery positive electrode materials with more excellent and comprehensive performance is of great significance for promoting the development and practical application of zinc ion batteries.

[0004] In recent years, tellurium-based materials such as tellurium dioxide (TeO2) and telluride (XTe) have been tried to be applied as positive electrode materials for aqueous zinc ion batteries due to their unique physical and chemical properties, and related research has been conducted. The main advantage of TeO2 as a positive electrode material is its 6-electron reaction (Te is converted between +4 valence and -2 valence), which has a higher energy density and can effectively improve the low energy density of aqueous zinc ion batteries, and has great potential. However, TeO2 is mostly in a large block shape and has poor compatibility with electrolyte, and when used as a positive electrode material, it is often difficult to fully react, resulting in a decrease in energy density. Moreover, the electrochemical reaction process is accompanied by a large volume change, causing the electrode material to fall off from the current collector material, and the cycle stability of the battery is poor.

[0005] Therefore, it is necessary to design and regulate the microstructure of TeO2 materials to improve their electrochemical performance when used as cathode materials. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art, provide a nanowire structured zinc telluride cathode material for zinc-ion batteries and its preparation method, and apply it to cathode materials in zinc-ion batteries to improve battery performance.

[0007] The technical problem solved by this invention is achieved through the following technical solution:

[0008] A method for preparing a nanowire-structured zinc telluride-based positive electrode material for a battery, comprising the following steps:

[0009] S1. Take an appropriate amount of tellurium dioxide and squaric acid solid powder and disperse them in an appropriate amount of deionized water. Sonicate the mixture until a white mixed dispersion is formed, and heat the resulting mixed dispersion to carry out a pre-reaction.

[0010] S2. Transfer the heated mixture and dispersion from S1 to a hydrothermal reactor, control the ratio of the total volume of the dispersion to the volume of the reactor, control the reaction temperature, and adjust the reaction time to carry out the hydrothermal reaction and obtain the crude product.

[0011] S3. Centrifuge the crude product, vacuum filter it with a Buchner funnel and filter membrane, wash it with distilled water, and dry it in an oven to obtain the preliminary product.

[0012] S4. Prepare a zinc salt solution of a certain concentration, immerse the preliminary product obtained in S3 in the zinc salt solution and stir, filter after stirring and wash with a small amount of alcohol, heat to dry and grind to obtain nanowire structure zinc telluride battery cathode material.

[0013] Furthermore, the molar concentrations of tellurium dioxide and squaric acid in the mixed dispersion of S1 are 0.5–1 mol / L and the concentration ratio is 1:1–1:3.

[0014] Furthermore, the pre-reaction temperature of S1 is 90–95°C, and the pre-reaction time is 3–6 h.

[0015] Furthermore, the total volume of the dispersion in S2 is 20% to 40% of the total volume of the reactor, the hydrothermal reaction temperature is 120 to 150°C, and the hydrothermal reaction time is 12 to 18 hours.

[0016] Furthermore, the centrifugation speed of S3 is 6000 rpm, and the centrifugation time is 12 min.

[0017] Furthermore, the zinc salt in S4 is any one of zinc sulfate, zinc chloride, zinc tetrafluoroborate, and zinc trifluoromethanesulfonate, and the concentration of the zinc salt solution is 1-2 mol / L, with a stirring time of 24 h.

[0018] A nanowire-structured zinc telluride-squash ion battery cathode material is prepared using the method described above.

[0019] An application of the nanowire-structured zinc telluride squaric acid cathode material prepared by the aforementioned method in zinc-ion battery cathodes involves mixing and grinding the nanowire-structured zinc telluride squaric acid cathode material with Ketjen black and polyvinylidene fluoride at a mass ratio of 7:2:1 until homogeneous. N-methylpyrrolidone is then added until the viscosity is appropriate. The resulting viscous dispersion is then diluted to 3 mg / cm³. 2 The loading amount is uniformly coated on conductive carbon cloth, dried in a vacuum oven at 60°C for 12 hours, and then cut into circular pieces with a diameter of 10 mm to prepare the positive electrode material electrode sheet.

[0020] The advantages and beneficial effects of this invention are as follows:

[0021] 1. The nanowire structure cathode material of the present invention enables the electrode material to have a larger contact area with the electrolyte, resulting in a more complete electrochemical reaction and avoiding the problem of slow and uneven reaction kinetics inside bulk electrode materials. At the same time, the nanowire structure can also avoid capacity decay caused by volume changes during the electrochemical reaction. Zinc-ion batteries prepared with this cathode material can have higher specific capacity and better cycle stability.

[0022] 2. The cathode material prepared by this invention is a novel tellurium cathode material, which is beneficial to obtain a zinc-ion battery cathode with higher energy density by promoting the electrochemical reaction of tellurium, thereby improving the energy density of zinc-ion batteries.

[0023] 3. This invention prepares a novel cathode material with a nanowire structure from tellurium materials, such as tellurium dioxide, which are usually in a large bulk structure. This unique structure is beneficial to increasing the specific surface area of ​​the electrochemical reaction of tellurium cathode materials and enhancing diffusion kinetics, while avoiding the problem that it is difficult for bulk tellurium materials to react quickly and completely.

[0024] 4. The tellurium squartz cathode material with a unique nanowire structure prepared by this invention has high discharge specific capacity and high cycle stability when used as a cathode in zinc-ion batteries. Attached Figure Description

[0025] Figure 1 This is a scanning electron microscope image of tellurium dioxide and squaric acid raw materials used in this invention;

[0026] Figure 2These are scanning electron microscope (SEM) images of different positions of the nanowire-structured zinc telluride-squash battery cathode material prepared in Example 2 of this invention.

[0027] Figure 3 This is a transmission electron microscope (TEM) image of the nanowire-structured zinc telluride-squash battery cathode material prepared in Example 2 of this invention.

[0028] Figure 4 This is a scanning electron microscope image of the nanowire-structured zinc telluride-squash battery cathode material prepared in Example 4 of this invention;

[0029] Figure 5 This is an X-ray diffraction pattern of the nanowire-structured zinc telluride ion battery cathode material and raw materials prepared in Example 2 of this invention;

[0030] Figure 6 These are cyclic voltammetry curves of zinc-ion batteries using the cathode materials prepared in Example 2 and Comparative Example 1 of this invention.

[0031] Figure 7 These are charge-discharge curves of zinc-ion batteries using the cathode materials prepared in Example 2 and Comparative Example 1 of this invention.

[0032] Figure 8 This is a comparison chart of the cycle stability of zinc-ion batteries prepared with positive electrode materials in Example 2 and Comparative Example 1 of the present invention. Detailed Implementation

[0033] The present invention will be further described in detail below through specific embodiments. The following embodiments are merely descriptive and not limiting, and should not be used to limit the scope of protection of the present invention.

[0034] Example 1

[0035] (1) Add 3.19 g of tellurium dioxide and 1.14 g of squaric acid solid powder to a 50 mL beaker, and then add 20 mL of water for dispersion. After ultrasonic dispersion of the mixture for 30 min, heat to 90 °C and maintain for 3 h for pre-reaction.

[0036] (2) Transfer the final mixed dispersion obtained in step (1) to a 50 mL hydrothermal reactor. After preheating the oven to 150°C and maintaining it for 10 min, place the reactor in the oven for hydrothermal reaction for 12 h.

[0037] (3) The crude product obtained from the hydrothermal reaction in step (2) is centrifuged at a speed of 6000 rpm for 12 min. The centrifuged product is then filtered through a Buchner funnel and a polyamide filter membrane, washed with distilled water, and dried in an oven at 60°C to obtain the preliminary product.

[0038] (4) Prepare 20 mL of zinc sulfate solution with a concentration of 2 mol / L. Soak the preliminary product obtained in step (3) in the zinc salt solution and stir magnetically for 24 h. After stirring, filter again and wash with a small amount of alcohol. Heat, dry and grind to obtain the final product.

[0039] Example 2

[0040] (1) Add 3.19g of tellurium dioxide and 2.28g of squaric acid solid powder to a 50mL beaker, and then add 20mL of water for dispersion. After ultrasonically dispersing the mixture for 30min, heat it to 90℃ and maintain it for 3h for pre-reaction.

[0041] (2) Transfer the final mixed dispersion obtained in step (1) to a 50 mL hydrothermal reactor. After preheating the oven to 150°C and maintaining it for 10 min, place the reactor in the oven for hydrothermal reaction for 12 h.

[0042] (3) The crude product obtained from the hydrothermal reaction in step (2) is centrifuged at a speed of 6000 rpm for 12 min. The centrifuged product is then filtered through a Buchner funnel and a polyamide filter membrane, washed with distilled water, and dried in an oven at 60°C to obtain the preliminary product.

[0043] (4) Prepare 20 mL of zinc sulfate solution with a concentration of 2 mol / L. Soak the preliminary product obtained in step (3) in the zinc salt solution and stir magnetically for 24 h. After stirring, filter again and wash with a small amount of alcohol. Heat, dry and grind to obtain the final product.

[0044] Application examples

[0045] A water-based zinc-ion battery uses tellurium squartz cathode material with a nanowire structure obtained in Example 2 as the positive electrode material. The tellurium squartz cathode material is mixed with Ketjen black and polyvinylidene fluoride at a mass ratio of 7:2:1 and ground until homogeneous. N-methylpyrrolidone is added until the viscosity is appropriate. The resulting viscous dispersion is uniformly coated onto conductive carbon cloth with a loading of approximately 3 mg / cm³. 2 After drying at 60°C for 12 hours in a vacuum oven, the material is cut into 10mm diameter discs to prepare positive electrode sheets. The prepared positive electrode sheets are then assembled in the following order to prepare a zinc-ion battery: positive electrode shell—positive electrode—glass fiber separator (with zinc salt electrolyte added)—negative electrode—spacer—spring sheet—negative electrode shell.

[0046] Example 3

[0047] (1) Add 3.19g of tellurium dioxide and 2.28g of squaric acid solid powder to a 50mL beaker, and then add 20mL of water for dispersion. After ultrasonically dispersing the mixture for 30min, heat it to 90℃ and maintain it for 3h for pre-reaction.

[0048] (2) Transfer the final mixed dispersion obtained in step (1) to a 50 mL hydrothermal reactor. After preheating the oven to 150°C and maintaining it for 10 min, place the reactor in the oven for hydrothermal reaction for 18 h.

[0049] (3) The crude product obtained from the hydrothermal reaction in step (2) is centrifuged at a speed of 6000 rpm for 12 min. The centrifuged product is then filtered through a Buchner funnel and a polyamide filter membrane, washed with distilled water, and dried in an oven at 60°C to obtain the preliminary product.

[0050] (4) Prepare 20 mL of zinc sulfate solution with a concentration of 2 mol / L. Soak the preliminary product obtained in step (3) in the zinc salt solution and stir magnetically for 24 h. After stirring, filter again and wash with a small amount of alcohol. Heat, dry and grind to obtain the final product.

[0051] Example 4

[0052] (1) Add 3.19g of tellurium dioxide and 2.28g of squaric acid solid powder to a 50mL beaker, and then add 20mL of water for dispersion. After ultrasonically dispersing the mixture for 30min, heat it to 90℃ and maintain it for 3h for pre-reaction.

[0053] (2) Transfer the final mixed dispersion obtained in step (1) to a 50 mL hydrothermal reactor. After preheating the oven to 120°C and maintaining it for 10 min, place the reactor in the oven for hydrothermal reaction for 12 h.

[0054] (3) The crude product obtained from the hydrothermal reaction in step (2) is centrifuged at a speed of 6000 rpm for 12 min. The centrifuged product is then filtered through a Buchner funnel and a polyamide filter membrane, washed with distilled water, and dried in an oven at 60°C to obtain the preliminary product.

[0055] (4) Prepare 20 mL of zinc sulfate solution with a concentration of 2 mol / L. Soak the preliminary product obtained in step (3) in the zinc salt solution and stir magnetically for 24 h. After stirring, filter again and wash with a small amount of alcohol. Heat, dry and grind to obtain the final product.

[0056] Comparative Example 1

[0057] (1) Add 3.19g of tellurium dioxide solid powder to a 50mL beaker, and then add 20mL of water to disperse it. After ultrasonically dispersing the mixture for 30min, heat it to 90℃ and keep it for 3h.

[0058] (2) Transfer the final mixed dispersion obtained in step (1) to a 50 mL hydrothermal reactor. After preheating the oven to 150°C and maintaining it for 10 min, place the reactor in the oven for hydrothermal reaction for 12 h.

[0059] (3) The crude product obtained from the hydrothermal reaction in step (2) is centrifuged at a speed of 6000 rpm for 12 min. The centrifuged product is then filtered through a Buchner funnel and a polyamide filter membrane, washed with distilled water, and dried in an oven at 60°C to obtain the preliminary product.

[0060] (4) Prepare 20 mL of zinc sulfate solution with a concentration of 2 mol / L. Soak the preliminary product obtained in step (3) in the zinc salt solution and stir magnetically for 24 h. After stirring, filter again and wash with a small amount of alcohol. Heat, dry and grind to obtain the final product.

[0061] The raw materials tellurium dioxide and squaric acid, as well as the prepared nanowire-structured tellurium squaric acid cathode material, were characterized using an S-4800 cold field emission scanning electron microscope (SEM). SEM images were obtained, such as... Figure 1 As shown, (a) is tellurium dioxide and (b) is squaric acid. It can be seen that the initial tellurium dioxide and squaric acid are both random and large-sized lumps.

[0062] And such Figure 2 As shown in the scanning electron microscope images at two different locations, the tellurium squaric acid cathode material prepared using the method of Example 2 of this invention exhibits significantly different nanowire structures, and its size is also significantly reduced. This unique microstructure facilitates more complete contact between the cathode material and the electrolyte, promotes electrochemical reaction kinetics, and ensures a more complete reaction of the cathode material. Simultaneously, this microstructure also avoids problems such as electrode material damage and detachment caused by volume changes before and after the electrochemical reaction process, thus improving the cycle stability of the battery.

[0063] The microstructure of the prepared nanowire-structured tellurium squaric acid cathode material was further characterized using a JEM-2100F transmission electron microscope. Figure 3 As shown, this further demonstrates the unique nanowire structure of the tellurium cathode material prepared in Example 2.

[0064] Figure 4 This is a scanning electron microscope image of the nanowire-structured tellurium squaric acid cathode material prepared in Example 4. It can be seen that although Example 4 also obtained a nanowire structure compared to Example 2, the nanowire structure is less distinct. This may be due to the lower reaction temperature in Example 4 compared to Example 2.

[0065] Example 2 and its main raw materials, tellurium dioxide and squaric acid, were characterized using a D8 Advanced X-ray diffractometer. Figure 5 As shown, new characteristic peaks appeared in Example 2, and the peak ratio also changed significantly, which also confirms the transformation of the obtained cathode material structure.

[0066] Cyclic voltammetry curves of zinc-ion batteries using the materials prepared in Example 2 and Comparative Example 1 as positive electrodes were characterized using a CHI660e electrochemical workstation. Figure 6 As shown, compared to Comparative Example 1, the cyclic voltammetry curve of the nanowire-structured tellurium squaric acid cathode material prepared in Example 2 has a larger area and a smaller peak position shift. This indicates that thanks to this unique nanowire structure, the electrochemical reaction proceeds more fully and exhibits faster kinetics.

[0067] The charge-discharge performance of zinc-ion batteries using the materials prepared in Example 2 and Comparative Example 1 as positive electrodes was characterized using a Neware BTS-5V 10mA battery testing instrument. Figure 7 As shown, thanks to the unique nanowire structure of the tellurium squaric acid cathode in Example 2, the zinc-ion battery assembled in Example 2 has a higher discharge specific capacity than Comparative Example 1, at 2Ag -1 The current density can reach nearly 500 mAh g -1 The result was significantly higher than that of the zinc-ion battery in Comparative Example 1, which is consistent with the aforementioned cyclic voltammetry results.

[0068] The cycle stability of zinc-ion batteries using the materials prepared in Example 2 and Comparative Example 1 as positive electrodes was characterized using a Neware BTS-5V 10mA battery testing instrument. Figure 8 As shown, it can be clearly seen that the specific capacity of Example 2 remains stable during continuous cycling, and the cycling stability is significantly better than that of Comparative Example 1. This is due to the effective mitigation of the volume expansion problem of the electrode during charging and discharging by the unique nanowire structure.

[0069] Although embodiments and drawings of the present invention have been disclosed for illustrative purposes, those skilled in the art will understand that various substitutions, variations and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. A method for preparing a nanowire-structured zinc telluride-squash ion battery cathode material, characterized in that: The steps of the method are as follows: S1. Take an appropriate amount of tellurium dioxide and squaric acid solid powder and disperse them in an appropriate amount of deionized water. Sonicate the mixture until a white mixed dispersion is formed, and heat the resulting mixed dispersion to carry out a pre-reaction. S2. Transfer the heated mixture and dispersion from S1 to a hydrothermal reactor, control the ratio of the total volume of the dispersion to the volume of the reactor, control the reaction temperature, and adjust the reaction time to carry out the hydrothermal reaction and obtain the crude product. S3. Centrifuge the crude product, vacuum filter it with a Buchner funnel and filter membrane, wash it with distilled water, and dry it in an oven to obtain the preliminary product. S4. Prepare a zinc salt solution of a certain concentration, immerse the preliminary product obtained in S3 in the zinc salt solution and stir, filter after stirring and wash with a small amount of alcohol, heat to dry and grind to obtain nanowire structure zinc telluride battery cathode material. The molar concentrations of tellurium dioxide and squaric acid in the mixed dispersion of S1 are 0.5–1 mol / L and the concentration ratio is 1:1–1:

3. The pre-reaction temperature of S1 is 90-95℃, and the pre-reaction time is 3-6h; The total volume of the dispersion in S2 is 20% to 40% of the total volume of the reactor, the hydrothermal reaction temperature is 120 to 150°C, and the hydrothermal reaction time is 12 to 18 hours.

2. The method for preparing the nanowire-structured zinc telluride ion battery cathode material according to claim 1, characterized in that: The centrifugation speed of S3 is 6000 rpm, and the centrifugation time is 12 min.

3. The method for preparing the nanowire-structured zinc telluride-squash ion battery cathode material according to claim 1, characterized in that: The zinc salt in S4 is any one of zinc sulfate, zinc chloride, zinc tetrafluoroborate, and zinc trifluoromethanesulfonate, and the concentration of the zinc salt solution is 1-2 mol / L, with a stirring time of 24 h.

4. A nanowire-structured zinc telluride-squash ion battery cathode material, characterized in that: It is prepared by the method described in any one of claims 1 to 3.

5. The application of a nanowire-structured zinc telluride nanoparticle battery cathode material prepared by the method according to any one of claims 1 to 3 in the cathode of a zinc-ion battery, characterized in that: The nanowire-structured zinc telluride-1-ion battery cathode material was mixed and ground uniformly with Ketjen black and polyvinylidene fluoride at a mass ratio of 7:2:

1. N-methylpyrrolidone was added until the viscosity was appropriate. The resulting viscous dispersion was then diluted to 3 mg / cm³. 2 The loading amount is uniformly coated on conductive carbon cloth, dried in a vacuum oven at 60°C for 12 hours, and then cut into circular pieces with a diameter of 10 mm to prepare the positive electrode material electrode sheet.

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