Iron-doped tricobalt tetraoxide positive electrode material, preparation method thereof and application thereof in zinc-based alkaline batteries

Abstract

The application belongs to the technical field of battery positive electrode materials, and particularly relates to application of iron-doped cobaltic oxide positive electrode material in zinc-based alkaline batteries. Cobalt nitrate, iron nitrate and hexamethylenetetramine are added into deionized water and stirred, the obtained mixed solution is moved into a reaction kettle, a pretreated conductive substrate is vertically immersed in the solution, after hydrothermal reaction, the substrate is taken out and vacuum dried, a sample loaded with a precursor is placed in a muffle furnace for calcination, and iron-doped cobaltic oxide positive electrode material is obtained. The iron-doped cobaltic oxide positive electrode material is applied in zinc-based alkaline batteries, and it can be concluded from electrochemical tests that the iron-doped cobaltic oxide material has a higher specific capacity compared with original cobaltic oxide. The synthesis process is simple, environment-friendly and low in price, and the iron-doped cobaltic oxide material is expected to become a new type of energy storage device.

Description

Technical Field

[0001] This invention belongs to the field of battery cathode material technology, and specifically relates to an iron-doped cobalt tetroxide cathode material, its preparation method, and its application in zinc-based alkaline batteries. Background Technology

[0002] The rapid depletion of fossil fuels necessitates the search for sustainable energy sources. Successful application of fluctuating and intermittent renewable energy requires reliable and efficient energy storage. Batteries have achieved significant success as an energy storage strategy. For example, lithium-ion batteries have been successfully commercialized due to their high energy density and stability. However, many issues, such as high cost (approximately $90,000 per ton), potential hazards, and health risks, remain unresolved. Besides lithium-ion batteries, zinc-based batteries have attracted considerable attention in recent years due to the abundance and low cost of zinc, its inherent safety, and high theoretical capacity. To date, Zn-Mn, Zn-NiO, and Zn-Ag batteries have been extensively explored. The charging and discharging process involves oxidation and reduction reactions of metallic zinc and active materials. However, their actual capacity is not attractive due to insufficient theoretical capacity and low utilization of cathode materials. For example, the working capacity of a Zn-Ni battery is only 165 mAh / g, only 46% of the theoretical value (360 mAh / g), resulting in a low energy density (228 Wh / kg). Among zinc-based batteries, Zn-Co batteries have recently made significant progress. Cobalt-based materials are considered promising electrode materials due to their high theoretical capacity, high potential, high redox activity, and good reversibility. However, their actual capacity is far lower than the theoretical capacity due to limitations in low conductivity and small specific surface area. Cobalt oxide (Co3O4), as a transition metal oxide, can be used as a cathode material, exhibiting a high theoretical capacity of 446 mAh / g and an operating voltage as high as 1.8 V in alkaline batteries. Even with these achievements, the utilization of the active material is still insufficient (below 50%) considering the theoretical capacity of Co3O4, resulting in wasted capacity. In addition to using alkaline electrolytes, zinc batteries assembled from Co(III)-rich Co3O4 can operate at 2 V with a capacity of 205 mAh / g using a mild electrolyte. In contrast, the zinc potential in the alkaline electrolyte (-1.22 V vs SHE) is lower than that in the mild electrolyte (-0.76 V vs SHE), which allows for the possibility of higher battery voltages. Furthermore, in mild electrolytes, the hydrogen evolution reaction and the formation of inactive zinc hydrates are more severe, leading to poor reversibility of the Zn electrode. Therefore, the theoretical capacity of Co3O4 in alkaline electrolytes is almost twice that of mild solutions. For this reason, we chose an alkaline solution as the electrolyte and prepared a zinc-based alkaline battery. Summary of the Invention

[0003] The purpose of this invention is to provide an application of iron-doped cobalt tetroxide cathode material in zinc-based alkaline batteries, which significantly improves the specific capacity of the zinc-based alkaline batteries.

[0004] The technical solution adopted in this invention is as follows: an iron-doped cobalt tetroxide cathode material, the preparation method of which includes the following steps: cobalt nitrate, ferric nitrate, and hexamethylenetetramine are added to deionized water, stirred and dissolved, and stirred for another 1 hour. The resulting mixed solution is then transferred to a reaction vessel, and pre-treated nickel foam is vertically immersed in the solution for hydrothermal reaction. After the reaction, the sample is removed and vacuum dried to obtain a sample loaded with the precursor. Finally, the obtained product is placed in a muffle furnace for calcination to obtain the iron-doped cobalt tetroxide cathode material.

[0005] Preferably, in the above-mentioned iron-doped cobalt tetroxide cathode material, the molar ratio of cobalt nitrate: hexamethylenetetramine: ferric nitrate is 1:1:0.1-1.

[0006] Preferably, in the above-mentioned iron-doped cobalt tetroxide cathode material, the hydrothermal reaction is carried out at 120°C for 16 hours.

[0007] Preferably, in the above-mentioned iron-doped cobalt tetroxide cathode material, the vacuum drying is performed by drying at 60°C for 12 hours in a vacuum drying oven.

[0008] Preferably, in the above-mentioned iron-doped cobalt tetroxide cathode material, the calcination is carried out in a muffle furnace at 450°C for 2 hours.

[0009] This invention provides the application of an iron-doped cobalt tetroxide cathode material in zinc-based alkaline batteries.

[0010] A zinc-based alkaline battery based on iron-doped cobalt tetroxide cathode material is prepared by cutting iron-doped cobalt tetroxide cathode and zinc anode sheets respectively, then clamping the cathode and anode sheets in an electrode clamp and placing them in an electrolytic cell with electrolyte, with the top of the electrode material flush with the electrolyte, thus forming an iron-doped cobalt tetroxide zinc-based alkaline battery.

[0011] Preferably, the conductive substrate is one of nickel foam, copper foam, or carbon cloth.

[0012] Preferably, the electrolyte is one of potassium hydroxide, sodium hydroxide, or calcium hydroxide.

[0013] The beneficial effects of this invention are:

[0014] 1. This invention designs a zinc-based alkaline battery based on iron-doped cobalt tetroxide cathode material. It has the following advantages: cobalt and iron atoms are adjacent in the periodic table and have similar ionic radii, oxidation states, and physicochemical properties. Furthermore, the doping of iron atoms does not cause significant distortion of the Co3O4 lattice. The synthesis method is also low-cost, environmentally friendly, and allows for controllable morphology.

[0015] 2. In this invention, the zinc-based alkaline battery assembled with iron-doped cobalt tetroxide cathode material has a specific capacity that increases by 149.53 mAh / g after iron doping, reaching a specific capacity of 171.97 mAh / g, which is about 7.7 times greater than that of the original cobalt tetroxide cathode material.

[0016] 3. The materials selected in this invention have excellent pseudocapacitive properties, and are also inexpensive, environmentally friendly, and recyclable. They also possess high theoretical specific capacitance and excellent stability. Attached Figure Description

[0017] Figure 1 This is the XRD pattern of the cobalt tetroxide and iron-doped cobalt tetroxide electrode sheets prepared according to the present invention.

[0018] Figure 2 This is the SEM spectrum of the iron-doped cobalt tetroxide electrode sheet prepared according to the present invention.

[0019] Figure 3 This is a comparison of the cyclic voltammetry curves of the iron-doped cobalt tetroxide zinc-based alkaline battery prepared according to the present invention.

[0020] Figure 4 This is a comparison chart of the specific capacity of the iron-doped cobalt tetroxide zinc-based alkaline battery prepared according to the present invention. Detailed Implementation

[0021] Example 1

[0022] (I) Iron-doped cobalt tetroxide cathode material, prepared by the following method:

[0023] 1.5 g of cobalt nitrate and 1.5 g of hexamethylenetetramine were weighed and dissolved separately in 30 mL of distilled water. After mixing, ferric nitrate with a cobalt to iron molar ratio of 1:0.4 was added, and the mixture was magnetically stirred for 1 h at room temperature to ensure thorough mixing. The thoroughly mixed solution was transferred to a stainless steel hydrothermal reactor lined with polytetrafluoroethylene. Nickel foam (3 cm × 4 cm) was soaked in hydrochloric acid to remove the oxide layer, and then washed sequentially with acetone and deionized water to remove impurities. The treated nickel foam was then vertically immersed in the solution in the reactor and sealed. The reactor was kept at 120 °C for 16 h. After the reactor had completely cooled to room temperature, the nickel foam was removed and repeatedly rinsed with deionized water and anhydrous ethanol to remove residual reactants and unloaded nanoparticle fragments. It was then dried in a vacuum drying oven at 60 °C for 12 h to obtain a sample loaded with the precursor. Finally, the obtained product was calcined in a muffle furnace at 450 °C for 2 h to prepare the Fe-Co3O4 electrode sheet grown on the nickel foam.

[0024] (II) Testing

[0025] Figure 1 These are the XRD spectra of the iron-doped cobalt tetroxide cathode material and the cobalt tetroxide cathode material prepared according to this invention. Figure 1 As can be seen, the XRD pattern of the sample did not show significant changes after Fe doping, and the shift of individual peaks indicates that Fe ions were successfully doped into Co3O4.

[0026] Figure 2 This is the SEM spectrum of the iron-doped cobalt tetroxide cathode material prepared according to this invention. Figure 2 As can be seen, iron-doped cobalt tetroxide grows uniformly on the nickel foam conductive substrate, and the morphology of the sample does not change significantly.

[0027] Example 2

[0028] The preparation method of iron-doped cobalt tetroxide cathode material is as follows:

[0029] 3g of cobalt nitrate and 3g of hexamethylenetetramine were weighed and dissolved separately in 30mL of distilled water. After mixing, ferric sulfate with a cobalt to iron molar ratio of 1:0.1 was added, and the mixture was magnetically stirred for 2 hours at room temperature to ensure thorough mixing. The thoroughly mixed solution was transferred to a stainless steel hydrothermal reactor lined with polytetrafluoroethylene. Nickel foam (3cm × 4cm) was soaked in hydrochloric acid to remove the oxide layer, and then washed sequentially with acetone and deionized water to remove impurities. The treated nickel foam was then vertically immersed in the solution in the reactor and sealed. The reactor was kept at 150℃ for 12 hours. After the reactor had completely cooled to room temperature, the nickel foam was removed and repeatedly rinsed with deionized water and anhydrous ethanol to remove residual reactants and unloaded nanoparticle fragments. It was then dried in a vacuum drying oven at 60℃ for 12 hours to obtain a sample loaded with the precursor. Finally, the obtained product was calcined in a muffle furnace at 450℃ for 2 hours to prepare the Fe-Co3O4 electrode sheet grown on the nickel foam.

[0030] Example 3

[0031] The preparation method of iron-doped cobalt tetroxide cathode material is as follows:

[0032] 1.5 g of cobalt chloride and 1.5 g of hexamethylenetetramine were dissolved separately in 30 mL of distilled water. After mixing, ferric chloride with a cobalt to iron molar ratio of 1:0.2 was added, and the mixture was magnetically stirred for 1 h at room temperature to ensure thorough mixing. The thoroughly mixed solution was transferred to a stainless steel hydrothermal reactor lined with polytetrafluoroethylene. Nickel foam (3 cm × 4 cm) was soaked in hydrochloric acid to remove the oxide layer, and then washed with acetone and deionized water sequentially to remove impurities. The treated nickel foam was then vertically immersed in the solution in the reactor and sealed. The reactor was kept at 150 °C for 20 h. After the reactor had completely cooled to room temperature, the nickel foam was removed and repeatedly rinsed with deionized water and anhydrous ethanol to remove residual reactants and unloaded nanoparticle fragments. It was then dried in a vacuum drying oven at 60 °C for 12 h to obtain a sample loaded with the precursor. Finally, the obtained product was calcined in a muffle furnace at 450 °C for 2 h to prepare the Fe-Co3O4 electrode sheet grown on the nickel foam.

[0033] Example 4

[0034] The preparation method of iron-doped cobalt tetroxide cathode material is as follows:

[0035] 3g of cobalt nitrate and 3g of hexamethylenetetramine were dissolved separately in 30mL of distilled water. After mixing, ferric nitrate with a cobalt to iron molar ratio of 1:0.5 was added, and the mixture was magnetically stirred at room temperature for 2 hours to ensure thorough mixing. The thoroughly mixed solution was transferred to a stainless steel hydrothermal reactor lined with polytetrafluoroethylene. Nickel foam (3cm × 4cm) was soaked in hydrochloric acid to remove the oxide layer, followed by washing with acetone and deionized water to remove impurities. The treated nickel foam was then vertically immersed in the solution in the reactor and sealed. The reactor was kept at 120℃ for 16 hours. After the reactor had completely cooled to room temperature, the nickel foam was removed and repeatedly rinsed with deionized water and anhydrous ethanol to remove residual reactants and unloaded nanoparticle fragments. It was then dried in a vacuum drying oven at 60℃ for 12 hours to obtain a sample loaded with the precursor. Finally, the obtained product was calcined in a muffle furnace at 450℃ for 2 hours to prepare the Fe-Co3O4 electrode sheet grown on the nickel foam.

[0036] Example 5

[0037] The preparation method of iron-doped cobalt tetroxide cathode material is as follows:

[0038] 1.5 g of cobalt chloride and 1.5 g of hexamethylenetetramine were weighed and dissolved separately in 30 mL of distilled water. After mixing, ferric chloride with a cobalt to iron molar ratio of 1:0.6 was added, and the mixture was magnetically stirred at room temperature for 1.5 h to ensure thorough mixing. The thoroughly mixed solution was transferred to a stainless steel hydrothermal reactor lined with polytetrafluoroethylene (PTFE). Nickel foam (3 cm × 4 cm) was soaked in hydrochloric acid to remove the oxide layer, followed by washing with acetone and deionized water to remove impurities. The treated nickel foam was then vertically immersed in the solution in the reactor and sealed. The reactor was kept at 120 °C for 16 h. After the reactor had completely cooled to room temperature, the nickel foam was removed and repeatedly rinsed with deionized water and anhydrous ethanol to remove residual reactants and unloaded nanoparticle fragments. The sample was then dried in a vacuum drying oven at 60 °C for 12 h to obtain the precursor-loaded sample. Finally, the obtained product was placed in a muffle furnace and calcined at 450°C for 2 hours to prepare Fe-Co3O4 electrode sheets grown on nickel foam.

[0039] Example 6

[0040] The preparation method of iron-doped cobalt tetroxide cathode material is as follows:

[0041] 3g of cobalt nitrate and 3g of hexamethylenetetramine were dissolved separately in 30mL of distilled water. After mixing, ferric sulfate with a cobalt to iron molar ratio of 1:0.8 was added, and the mixture was magnetically stirred at room temperature for 2 hours to ensure thorough mixing. The thoroughly mixed solution was transferred to a stainless steel hydrothermal reactor lined with polytetrafluoroethylene. Nickel foam (3cm × 4cm) was soaked in hydrochloric acid to remove the oxide layer, followed by washing with acetone and deionized water to remove impurities. The treated nickel foam was then vertically immersed in the solution in the reactor and sealed. The reactor was kept at 150℃ for 12 hours. After the reactor had completely cooled to room temperature, the nickel foam was removed and repeatedly rinsed with deionized water and anhydrous ethanol to remove residual reactants and unloaded nanoparticle fragments. It was then dried in a vacuum drying oven at 60℃ for 12 hours to obtain a sample loaded with the precursor. Finally, the obtained product was calcined in a muffle furnace at 450℃ for 2 hours to prepare the Fe-Co3O4 electrode sheet grown on the nickel foam.

[0042] Example 7

[0043] The preparation method of iron-doped cobalt tetroxide cathode material is as follows:

[0044] 1.5 g of cobalt chloride and 1.5 g of hexamethylenetetramine were dissolved separately in 30 mL of distilled water. After mixing, ferric nitrate with a cobalt to iron molar ratio of 1:1 was added. The mixture was magnetically stirred for 1 hour at room temperature to ensure thorough mixing. The thoroughly mixed solution was transferred to a stainless steel hydrothermal reactor lined with polytetrafluoroethylene. Nickel foam (3 cm × 4 cm) was soaked in hydrochloric acid to remove the oxide layer, followed by washing with acetone and deionized water to remove impurities. The treated nickel foam was then vertically immersed in the solution in the reactor and sealed. The reactor was kept at 120 °C for 16 hours. After the reactor had completely cooled to room temperature, the nickel foam was removed and repeatedly rinsed with deionized water and anhydrous ethanol to remove residual reactants and unloaded nanoparticle fragments. It was then dried in a vacuum drying oven at 60 °C for 12 hours to obtain a sample loaded with the precursor. Finally, the obtained product was calcined in a muffle furnace at 450 °C for 2 hours to prepare the Fe-Co3O4 electrode sheet grown on the nickel foam.

[0045] Example 8

[0046] A method for preparing a zinc-based alkaline battery using iron-doped cobalt tetroxide as the cathode material is as follows:

[0047] The Fe-Co3O4 positive electrode and zinc negative electrode obtained in Example 1 were cut separately. The positive electrode and negative electrode were then clamped together and placed in an electrolytic cell with electrolyte. The top of the electrode material was flush with the electrolyte, thus forming an iron-doped cobalt tetroxide zinc-based alkaline battery.

[0048] (I) The preparation method is as follows:

[0049] Preparation of zinc-based alkaline batteries using iron-doped cobalt tetroxide cathode material as the cathode: The iron-doped cobalt tetroxide cathode material Fe-Co3O4 cathode and the zinc anode are cut into 1×1cm pieces respectively. The cathode and anode are clamped in an electrode clamp and placed in an electrolytic cell with 3M potassium hydroxide electrolyte. The top of the electrode material is flush with the electrolyte, thus obtaining the iron-doped cobalt tetroxide zinc-based alkaline battery.

[0050] (II) Performance Testing

[0051] The comparative example uses cobalt tetroxide electrode sheet material as the positive electrode material to prepare a zinc-based alkaline battery containing cobalt tetroxide positive electrode material as described above.

[0052] Figure 3 These are the cyclic voltammetry curves of zinc-based alkaline batteries assembled from the iron-doped cobalt tetroxide cathode material and the cobalt tetroxide cathode material prepared in this invention, respectively. Figure 3 As can be seen, the iron-doped cobalt tetroxide cathode material obtained in Example 2, after iron doping, did not show a significant hydrogen evolution trend in its cyclic voltammetry curve at around 1.9V, but had a clear voltage plateau, and its capacity was greater than that of the original cobalt tetroxide cathode material.

[0053] Figure 4 This is a specific capacity diagram of zinc-based alkaline batteries assembled using the iron-doped cobalt tetroxide cathode material and the cobalt tetroxide cathode material prepared in this invention, respectively. Figure 4 As can be seen, the iron-doped cobalt tetroxide cathode material obtained in Example 2 has a specific capacity that increases by 149.53 mAh / g after iron doping, reaching a specific capacity of 171.97 mAh / g, which is about 7.7 times greater than that of the original cobalt tetroxide cathode material.

Claims

1. A zinc-based alkaline battery based on iron-doped cobalt tetroxide cathode material, characterized in that, The invention includes an iron-doped cobalt tetroxide cathode material. The preparation method of the iron-doped cobalt tetroxide cathode material includes the following steps: 3 g of cobalt nitrate and 3 g of hexamethylenetetramine are dissolved in 30 mL of distilled water. After mixing, ferric sulfate with a cobalt to iron molar ratio of 1:0.1 is added. The mixture is magnetically stirred at room temperature for 2 h to ensure thorough mixing. The thoroughly mixed solution is transferred to a stainless steel hydrothermal reactor lined with polytetrafluoroethylene. A 3 cm × 4 cm piece of nickel foam is soaked in hydrochloric acid to remove the oxide layer, then washed sequentially with acetone and deionized water to remove impurities. The treated nickel foam is then vertically immersed in the solution in the reactor, sealed, and treated at 150°C for 12 h. After the reactor has completely cooled to room temperature, the nickel foam is removed and repeatedly rinsed with deionized water and anhydrous ethanol to remove residual reactants and unloaded nanoparticle fragments. Finally, it is dried in a vacuum drying oven at 60°C for 12 hours. h, a sample loaded with the precursor is obtained, and finally the obtained product is placed in a muffle furnace and calcined at 450℃ for 2h to prepare Fe-Co3O4 cathode material grown on nickel foam.

2. The zinc-based alkaline battery based on iron-doped cobalt tetroxide cathode material according to claim 1, characterized in that, The method for preparing a zinc-based alkaline battery based on iron-doped cobalt tetroxide cathode material includes the following steps: iron-doped cobalt tetroxide foam nickel cathode material and negative zinc sheet are cut separately, and then the cathode electrode sheet and negative zinc sheet are clamped in an electrode clamp and placed in an electrolytic cell with electrolyte. The top of the electrode material is flush with the electrolyte to obtain an iron-doped cobalt tetroxide zinc-based alkaline battery.

3. The zinc-based alkaline battery based on iron-doped cobalt tetroxide cathode material according to claim 2, characterized in that, The electrolyte is one of potassium hydroxide, sodium hydroxide, or calcium hydroxide.

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