High-entropy hydrotalcite composite array electrode and preparation method and application thereof
By growing CuO nanowire arrays in situ on foam copper and preparing Cu2O@NiFeCoMnCr-LDHs high entropy hydrotalcite array electrodes in combination with hydrothermal method, the problems of low efficiency and poor stability of zinc-air batteries were solved, and efficient and stable battery performance was achieved.
Patent Information
- Application Number
- CN202510573261.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-04
- Publication Date
- 2025-08-08
AI Technical Summary
The low efficiency and poor stability of zinc-air batteries are mainly due to the slow kinetics of oxygen reduction reaction and oxygen evolution reaction, which leads to catalyst corrosion and affects the overall performance of the battery.
High-entropy hydrotalcite composite array electrodes were used to grow CuO nanowire arrays in situ on foam copper as sacrificial templates, and Cu2O and high-entropy hydrotalcite composite array electrodes were prepared in combination with hydrothermal method to improve the conductivity and stability of the material.
The high energy efficiency (more than 80%) and long cycle stability (more than 2000 hours) of zinc-air batteries have been achieved, and the problem of insufficient efficiency and stability in the prior art has been solved.
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Abstract
Description
Technical Field
[0001] The invention relates to a high-entropy hydrotalcite composite array electrode and a preparation method and application thereof, belonging to the field of new energy materials. Background Art
[0002] As the global population grows and the dependence on fossil fuels increases, fossil energy resources are becoming increasingly depleted. To address the growing energy demand and increasing environmental concerns, the exploration of renewable energy and advanced energy storage devices has attracted widespread research interest. New, clean and efficient electrochemical energy storage and conversion devices, including fuel cells, metal-air batteries, and water electrolysis, are being explored. Among them, zinc-air batteries (ZABs) have become a strong contender for future energy storage applications due to their low cost, environmental compatibility, excellent safety, and high theoretical energy density.
[0003] While primary ZABs have been successfully commercialized in hearing aids and emergency power supplies, the widespread application of rechargeable secondary ZABs remains very limited. Rechargeable ZABs charge and discharge via the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) processes at the cathode, requiring a bifunctional air electrode to accelerate their slow reaction rates. However, the sluggish OER / ORR reaction kinetics prevent zinc-air battery efficiency from exceeding the 65% efficiency bottleneck. Furthermore, the harsh oxidative potentials involved in the charging process can induce electrochemical oxidation of the bifunctional catalyst, corroding its ORR active sites and accelerating their deactivation, which can severely impact battery stability. Therefore, the key to improving the efficiency and stability of ZABs lies in the development of efficient air cathode materials.
[0004] To this end, the present invention provides a high-entropy hydrotalcite composite array electrode and a preparation method and application thereof. Summary of the Invention
[0005] To address the low efficiency and poor stability of current zinc-air batteries, this invention provides a high-entropy hydrotalcite composite array electrode, its preparation method, and its application in zinc-air batteries. The high-entropy hydrotalcite (Cu2O@NiFeCoMnCr-LDHs) array electrode is fabricated using CuO nanowires grown in situ on copper foam as a sacrificial template. The assembled battery achieves energy efficiency exceeding 80% and cycle stability exceeding 2000 hours.
[0006] The specific technical solutions of the present invention are as follows:
[0007] One of the purposes of the present invention is to provide a method for preparing a high entropy water-stone composite array electrode, the method comprising the following steps:
[0008] Step 1: Using chemical oxidation to grow CuO nanowire arrays on the surface of copper foam: First, prepare the modification solution. Weigh sodium hydroxide and dissolve it in deionized water. After stirring to dissolve, slowly add ammonium persulfate and mix well to form an alkaline oxidizing solution. Immerse a piece of pretreated copper foam in the above solution. During the reaction, persulfate ions decompose in a strong alkaline environment to produce oxidative free radicals, which drive the selective oxidation of the copper surface to form Cu(OH)2 nanowire arrays. After the reaction is completed, rinse with deionized water three times to remove residual reagents. The resulting self-supporting electrode is placed in a nitrogen-protected tube furnace and converted to CuO through heat treatment. After natural cooling, a CuO array is formed on the surface of the copper foam.
[0009] It should be emphasized that in order to ensure that a CuO array can be formed on the surface of the foamed copper, the present invention first uses a mixed aqueous solution of sodium hydroxide and ammonium persulfate as a pre-modification liquid. The purpose of this step is to reconstruct the surface functionalization. From the metal substrate to the oxide array, sodium hydroxide and ammonium persulfate synergistically oxidize: in a strong alkaline environment, ammonium persulfate acts as an oxidant to trigger the oxidation reaction of copper. This reaction selectively oxidizes the copper surface, avoids excessive corrosion of the substrate, and forms a uniform Cu(OH)2 precursor layer. And morphology control is performed: alkaline conditions inhibit the lateral diffusion of copper ions, promote the vertical growth of Cu(OH)2, and form a nanowire array.
[0010] It is further specified that the copper foam substrate used in step 1 needs to be pretreated before use. Pretreatment of the copper foam: cut the copper foam into 3×3 cm pieces and ultrasonically clean it in acetone for 10 minutes. Then soak it in a dilute HCl solution for 10 minutes to remove the surface oxide layer, and then wash it with anhydrous ethanol and deionized water. The purpose of the copper foam pretreatment is to construct an electrode / catalyst substrate material with high activity and high stability through physical and chemical synergy. The ultrasonic cleaning with acetone is intended to dissolve organic pollutants: using acetone as a polar solvent, it can effectively remove grease, dust and organic additives remaining from the processing adsorbed on the surface of the copper foam. It also modifies the hydrophobic surface: after the acetone evaporates, a low surface energy interface is formed, which inhibits the abnormal adhesion of bubbles during the subsequent pickling process. The soaking with dilute HCl is intended to dissolve oxides, inhibit excessive corrosion and activate the surface state.
[0011] It is further defined that the concentration of sodium hydroxide in the modification solution in step 1 is 2.0 to 3.0 mol / L, and the concentration of ammonium persulfate is 0.05 to 0.15 mol / L.
[0012] It is further defined that the immersion time of the oxidation process of the copper foam in step 1 is 10-15 minutes, and the immersion temperature is room temperature.
[0013] Step 2: Using the CuO nanowire array as a sacrificial template, a CuO and high-entropy hydrotalcite composite array material was prepared via a hydrothermal method. A metal salt solution and urea were dissolved in deionized water and stirred until completely dissolved. The sample obtained in Step 1 was placed in this solution and a high-entropy hydrotalcite composite array electrode was prepared via a hydrothermal method.
[0014] In order to prepare a high-entropy hydrotalcite nanoarray electrode with regular morphology, the present invention uses a CuO nanowire array as a sacrificial template to synthesize a composite electrode of Cu2O and high-entropy hydrotalcite. The constructed 3D array electrode can expose more active sites, which is conducive to sufficient contact between the electrode, electrolyte and gas, and improves conductivity.
[0015] It should be emphasized that, considering the high requirements of zinc-air batteries for air cathode OER activity and stability, the high-entropy hydrotalcite prepared in this invention is based on nickel-iron hydrotalcite as the core. The construction of high-entropy structure improves the activity and stability of electrode materials.
[0016] It is further defined that the metal salt solutions in step 1 are in an equimolar ratio.
[0017] It is further defined that the number of metal types described in step 1 is more than 5, wherein the fixed metals are NiCl2·6H2O and FeCl2·4H2O, and the others are transition metals.
[0018] It is further defined that the hydrothermal temperature in step 1 is 60-150° C. and the hydrothermal time is 6-12 h.
[0019] A second object of the present invention is to provide an application of the high-entropy hydrotalcite composite material as an air positive electrode in a zinc-air battery.
[0020] The advantages and beneficial effects of the present invention are:
[0021] (1) The high-entropy hydrotalcite material prepared by the present invention has high entropy properties, which can reduce the band gap of LDHs and improve their conductivity. In addition, due to the entropy stabilization effect and slow diffusion effect, the structural stability of the material is improved, which helps to improve the overall performance of zinc-air batteries.
[0022] (2) The high-entropy hydrotalcite material prepared by the present invention has a unique array structure, exhibits good electrical conductivity, is in situ grown on a foam copper substrate, has a strong structure, can improve material stability, and avoids the coating process of powder materials and the additional addition of adhesives.
[0023] (3) The battery assembled with high-entropy hydrotalcite as the air cathode exhibits high energy efficiency and stability. The material undergoes a Faradaic oxygen reduction reaction of the metal during charge and discharge, thus exhibiting properties similar to zinc-air and zinc-metal hybrid batteries.
[0024] (4) The high entropy hydrotalcite array electrode provided by the present invention has a simple preparation method, low cost, and universal applicability, and can be used to construct high entropy hydrotalcites of different metal types. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 This is the X-ray powder diffraction pattern of high entropy Cu2O@NiFeCoMnCr-LDHs material;
[0026] Figure 2 This is the scanning electron microscope image of high entropy Cu2O@NiFeCoMnCr-LDHs;
[0027] Figure 3 Transmission electron microscopy image of high entropy Cu2O@NiFeCoMnCr-LDHs;
[0028] Figure 4 EDS image of high entropy Cu2O@NiFeCoMnCr-LDHs;
[0029] Figure 5 This is a comparison chart of the stability of zinc-air batteries of high entropy Cu2O@NiFeCoMnCr-LDHs and Pt / C+RuO2. DETAILED DESCRIPTION
[0030] The present invention is further described below with reference to examples. These examples are merely for illustrating the method of the present invention and have no limitation on the scope of application of the present invention.
[0031] Example 1: The preparation of a high entropy Cu2O@NiFeCoMnCr-LDHs composite material of this embodiment is completed by the following steps:
[0032] Step 1: Cut the copper foam into 3×3cm small pieces and wash them in acetone ultrasonic for 10 minutes to remove the grease, dust and residual organic additives adsorbed on the surface of the copper foam and modify the hydrophobic surface to inhibit the abnormal attachment of bubbles in the subsequent pickling process. Then, in diluted HCl (3mol·L -1 ) solution for 10 minutes to dissolve oxides, inhibit over-corrosion, and activate the surface state. Then rinse with anhydrous ethanol and deionized water.
[0033] Step 2: Immerse the pretreated copper foam from step 1 in a solution of sodium hydroxide (25g) and ammonium persulfate (5.705g) for 10 minutes to reconstruct the surface functionalization. In a strong alkaline environment, ammonium persulfate acts as an oxidant to induce the conversion of Cu to Cu(OH)2, forming a uniform Cu(OH)2 nanowire precursor layer and controlling the morphology. The alkaline conditions inhibit the lateral diffusion of copper ions and promote the vertical growth of Cu(OH)2 to form a nanosheet array. After washing and drying, heat treatment is performed in a N2 atmosphere. The temperature is increased from room temperature to 190°C at a gradient of 1°C / min and maintained at 190°C for 1 hour to convert Cu(OH)2 to CuO, thereby forming a CuO array on the surface of the copper foam.
[0034] Step 3: Synthesis of a high-entropy hydrotalcite array electrode using copper oxide nanowires as a sacrificial template: Equimolar amounts (0.5 mmol) of nickel chloride, ferrous chloride, cobalt chloride, chromium chloride, manganese chloride, and urea (2.5 mmol) were dissolved in 50 ml of deionized water and stirred for 30 minutes to form a clear solution. The CuO nanowires obtained in Step 2 were then immersed in this solution and placed in a Teflon-lined stainless steel autoclave for reaction at 120°C for 10 hours. After cooling to room temperature, the sample was removed and rinsed three times with deionized water to remove loose nanoparticles or residues (e.g., unreacted materials), ensuring that only a layer of material tightly bonded to the substrate remained. The sample was then dried in a vacuum oven at 60°C for 3 hours.
[0035] Example 2: This example provides a Cu2O@NiFe-LDHs self-supporting electrode. The difference from Example 1 is that the hydrotalcite prepared is NiFe-LDHs of two metals. The preparation method includes the following steps:
[0036] Step 1: Cut the copper foam into 3×3cm small pieces and wash them in acetone ultrasonic for 10 minutes to remove the grease, dust and residual organic additives adsorbed on the surface of the copper foam and modify the hydrophobic surface to inhibit the abnormal attachment of bubbles in the subsequent pickling process. Then, in diluted HCl (3mol·L -1 ) solution for 10 minutes to dissolve oxides, inhibit over-corrosion, and activate the surface state. Then rinse with anhydrous ethanol and deionized water.
[0037] Step 2: Immerse the pretreated copper foam from step 1 in a solution of sodium hydroxide (25g) and ammonium persulfate (5.705g) for 10 minutes to reconstruct the surface functionalization. In a strong alkaline environment, ammonium persulfate acts as an oxidant to induce the conversion of Cu to Cu(OH)2, forming a uniform Cu(OH)2 nanowire precursor layer and controlling the morphology. The alkaline conditions inhibit the lateral diffusion of copper ions and promote the vertical growth of Cu(OH)2 to form a nanosheet array. After washing and drying, heat treatment is performed in a N2 atmosphere. The temperature is increased from room temperature to 190°C at a gradient of 1°C / min and maintained at 190°C for 1 hour to convert Cu(OH)2 to CuO, thereby forming a CuO array on the surface of the copper foam.
[0038] Step 3: Synthesis of a high-entropy hydrotalcite array electrode using copper oxide nanowires as a sacrificial template: Equimolar amounts (0.5 mmol) of nickel chloride, ferrous chloride, and urea (2.5 mmol) were dissolved in 50 ml of deionized water and stirred for 30 minutes to form a clear solution. The CuO nanowires obtained in Step 2 were then immersed in this solution and placed in a Teflon-lined stainless steel autoclave for reaction at 120°C for 12 hours. After cooling to room temperature, the sample was removed and rinsed three times with deionized water to remove loose nanoparticles or residues (e.g., unreacted material), ensuring that only the layer of material tightly bonded to the substrate remained. The sample was then dried in a vacuum oven at 60°C for 3 hours.
[0039] Example 3: This example provides a CF@NiFeCoMnCr-LDHs self-supporting electrode. The difference from Example 1 is that the copper oxide array is not grown in the material preparation, and high entropy hydrotalcite is directly hydrothermally grown on the foamed copper. The preparation method includes the following steps:
[0040] Step 1: Cut the copper foam into 3×3cm small pieces and wash them in acetone ultrasonic for 10 minutes to remove the grease, dust and residual organic additives adsorbed on the surface of the copper foam and modify the hydrophobic surface to inhibit the abnormal attachment of bubbles in the subsequent pickling process. Then, in diluted HCl (3mol·L -1 ) solution for 10 minutes to dissolve oxides, inhibit over-corrosion, and activate the surface state. Then rinse with anhydrous ethanol and deionized water.
[0041] Step 2: Synthesis of high-entropy hydrotalcite using the treated copper foam as a support: Equimolar amounts (0.5 mmol) of nickel chloride, ferrous chloride, cobalt chloride, chromium chloride, manganese chloride, and urea (2.5 mmol) were dissolved in 50 ml of deionized water and stirred for 30 minutes to form a clear solution. The treated copper foam obtained in Step 1 was then immersed in this solution and placed in a Teflon-lined stainless steel autoclave for reaction at 120°C for 12 hours. After cooling to room temperature, the sample was removed and rinsed three times with deionized water to remove loose nanoparticles or residues (such as unreacted material), ensuring that only a layer of material tightly bonded to the substrate remained. The sample was then dried in a vacuum oven at 60°C for 3 hours.
[0042] The following tests were performed to verify the beneficial effects of the present invention:
[0043] 1. X-ray Diffraction (XRD) Analysis: Irradiating a sample with sufficiently energetic X-rays excites the substances within the sample, producing secondary fluorescence X-rays. The position of the diffraction angle (peak) allows for qualitative analysis of the compound. The peaks of the high-entropy Cu2O@NiFeCoMnCr-LDHs composite material provided by this invention are consistent with those on a standard card, exhibiting characteristic peaks for each component.
[0044] 2. Scanning electron microscope test: Scan the sample surface with an electron beam through SEM to observe and analyze the surface morphology of the sample, and assist XRD test to confirm that the product has been successfully synthesized.
[0045] 3. Transmission electron microscopy test: Use an electron beam to penetrate the sample and form a high-resolution microscopic image to observe the microstructure of the sample at the atomic level, and combine scanning electron microscopy and XRD tests to determine whether the product has been successfully synthesized.
[0046] IV. OER Performance Testing: Using a Chenhua testing system, a three-electrode system was constructed to test OER performance. Polarization curves were measured using the three electrode materials prepared in the above examples as working electrodes, a mercury oxide electrode as a reference electrode, and a carbon rod as a counter electrode.
[0047] 5. Battery cycle stability test: In order to investigate the effect of high entropy Cu2O@NiFeCoMnCr-LDHs material in zinc-air battery application, the stability of zinc-air battery was tested according to the following method. The test process is as follows: high entropy Cu2O@NiFeCoMnCr-LDH and Pt / C+RuO2 loading amount is 0.5mg·cm -2 The hydrophobic carbon cloth was used as the positive electrode of the zinc-air battery, the polished zinc sheet was used as the negative electrode of the zinc-air battery, and 6M KOH and 0.2M zinc acetate aqueous solution were used as electrolytes to assemble the zinc-air battery. The blue battery test system was used at room temperature and the current density was set to 10 mA cm-2 The cycling stability test was conducted with a charge time of 20 minutes and a discharge time of 20 minutes per cycle. Compared to the traditional Pt / C and RuO2-based zinc-air battery positive electrode, which has a stability of only 400 hours, the high-entropy Cu2O@NiFeCoMnCr-LDH composite zinc-air battery has a stability of 2500 hours.
Claims
1. A preparation method and application of a high entropy hydrotalcite composite array material, characterized in that: The steps include: Step 1: The copper foam was ultrasonically cleaned in acetone, then soaked in a diluted HCl solution to remove the surface oxide layer, and then washed with anhydrous ethanol and deionized water. Step 2: Immerse the pretreated copper foam from Step 1 in a mixture of sodium hydroxide and ammonium persulfate for in-situ oxidation, resulting in vertically grown Cu(OH)2 nanowires on the copper foam. After washing and drying, the foam is heat-treated under a protective atmosphere to convert it into CuO nanowires. Step 3: Using the CuO nanowires obtained in step 2 as a carrier, a high-entropy hydrotalcite composite array was synthesized by a hydrothermal method: the CuO nanowires were immersed in a mixed solution of equimolar metal salts and urea, and then the mixed solution was transferred to a polytetrafluoroethylene-lined stainless steel autoclave for a hydrothermal reaction to obtain a high-entropy hydrotalcite composite array electrode.
2. The preparation method according to claim 1, wherein: The concentration of diluted HCl in step 1 is 3 mol·L -1 .
3. The preparation method according to claim 1, wherein: The concentration of the sodium hydroxide in step 2 is 2.0-3.0 mol / L; the concentration of the ammonium persulfate is 0.05-0.15 mol / L.
4. The preparation method according to claim 1, wherein: The soaking reaction time in step 2 is 10 to 15 minutes.
5. The preparation method according to claim 1, wherein: The protective gas for the heat treatment in step 2 is N2 atmosphere, the heat treatment temperature is 190°C, the temperature is increased from room temperature to 190°C at a heating rate of 1°C / min, and the holding time is 1h.
6. The preparation method according to claim 1, wherein: The equimolar amount of the metal salt in step 3 is 0.5 mmol.
7. The preparation method according to claim 1, wherein: There are five kinds of metal salts in step 3, two of which are fixed metals Ni and Fe, and the other three are not limited.
8. The preparation method according to claim 1, wherein: The metal salts described in step 3 are all chlorides.
9. The preparation method according to claim 1, wherein: The amount of urea used in step 3 was 2.5 mmol.
10. The preparation method according to claim 1, characterized in that: The hydrothermal temperature in step 3 is 120° C. and the time is 10 h.
11. A high entropy hydrotalcite composite array, characterized in that: A high-entropy hydrotalcite composite array electrode is prepared using the preparation method according to any one of claims 1 to 10. The high-entropy hydrotalcite composite array electrode is composed of Cu2O and high-entropy hydrotalcite and presents a nanorod array morphology of stacked nanosheets.
12. An application of the high entropy hydrotalcite composite array according to claim 11, characterized in that: It is used as an air positive electrode to assemble zinc-air batteries to break through the energy efficiency and cycle life of zinc-air batteries.