Modified zinc oxide for aqueous zinc-ion batteries and preparation method and application thereof

Abstract

The application relates to the technical field of electrochemical energy storage materials, in particular to modified zinc oxide for water-based zinc ion batteries as well as a preparation method and application thereof. x [In a Bi β R c ]Al2O4.zH2O, wherein a: beta: x: c = 0.1-0.3: 0.05-0.2: 0.8-1.2: 0.01-0.1, and z = 0.3-0.7; the matrix framework of the material is a spinel-type zinc aluminate ZnAl2O4, has a ZnO shell layer, and has a pore in the interior of the matrix framework, and is doped with In 3+ , Bi 3+ and rare earth R 3+ ; the rare earth R is selected from at least one of La, Ce or Y. The modified zinc oxide material of the application solves the problems of dendrite growth, side reactions and low cycle life of the zinc ion battery by designing a spinel matrix framework in the zinc oxide shell layer and being doped with multiple elements in cooperation.

Description

Technical Field

[0001] This invention relates to the field of electrochemical energy storage materials technology, specifically to a modified zinc oxide for aqueous zinc-ion batteries, its preparation method, and its application. Background Technology

[0002] Traditional zinc-ion batteries suffer from short circuits and increased electrolyte consumption due to issues such as dendrite growth at the zinc anode and hydrogen evolution side reactions. This results in problems like short cycle life, high polarization voltage, and poor safety. Existing methods for modifying zinc oxide generally involve single-element doping or simple composites, which can partially alleviate these problems, but suffer from low ion diffusion efficiency (D...). Zn2+ ≤1.1×10 -9 cm 2 Furthermore, it lacks effective suppression of interfacial side reactions, making it difficult to balance ion diffusion rate and interfacial stability.

[0003] Therefore, there is an urgent need to develop a modified zinc oxide that combines high ion conductivity, structural stability, and interface passivation capability. Summary of the Invention

[0004] The purpose of this invention is to address the existing technological status quo by optimizing raw materials and processes to provide a modified zinc oxide for aqueous zinc-ion batteries, its preparation method, and its application. This invention solves the problems of dendrite growth, side reactions, and low cycle life in existing zinc-ion batteries, while accelerating ion migration and reducing the polarization voltage of zinc-ion batteries.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A modified zinc oxide for use in aqueous zinc-ion batteries, with the molecular formula (ZnO). x [In a Bi β R c Al₂O₄·zH₂O, where a:β:x:c = 0.1-0.3: 0.05-0.2: 0.8-1.2: 0.01-0.1, z = 0.3-0.7;

[0007] The modified zinc oxide has a spinel-type zinc aluminate ZnAl2O4 matrix framework with a ZnO shell and internal pores, and is doped with In. 3+ Bi 3+ and rare earth R 3+ The rare earth element R is selected from at least one of La, Ce, or Y.

[0008] As an improvement to the above scheme, the matrix framework has pores with a diameter of 2.8 Å to 3.2 Å inside.

[0009] As an improvement to the above scheme, the thickness of the ZnO shell is 10nm-50nm.

[0010] As an improvement to the above scheme, the zinc ion diffusion coefficient D of the modified zinc oxide is... Zn2+ 3×10 -9 cm² / s - 3.5 × 10 -9 cm² / s, polarization voltage ΔE@5C≤0.08V.

[0011] The present invention also provides a method for preparing the modified zinc oxide, comprising the following steps:

[0012] (1) Zinc salt, aluminum salt, indium salt, bismuth salt and rare earth salt are dissolved in deionized water in proportion and the precursor is synthesized by hydrothermal reaction;

[0013] (2) The precursor obtained in step (1) is mixed with a template agent and then spray-dried to obtain nanoparticles;

[0014] (3) The nanoparticles obtained in step (2) are calcined in a reducing atmosphere to form a Bi2O3 passivation layer on the surface of the matrix framework and a ZnO shell to obtain a modified zinc oxide crude product.

[0015] (4) The modified zinc oxide crude product obtained in step (3) is acid washed and dried to obtain the modified zinc oxide.

[0016] As an improvement to the above scheme, in step (1), the zinc salt, aluminum salt, indium salt, bismuth salt and rare earth salt are dissolved in deionized water in a molar ratio of Zn:Al:In:Bi:R of 1:(1.5-2.5):(0.1-0.3):(0.05-0.2):(0.01-0.1);

[0017] In step (1), the hydrothermal reaction temperature is 180℃-220℃ and the reaction time is 12h-24h.

[0018] As an improvement to the above scheme, in step (2), the mass ratio of the precursor to the template agent is 1:(0.1-0.3).

[0019] The average particle size of the nanopowder is 50nm-200nm;

[0020] The inlet air temperature during spray drying is 180℃-220℃.

[0021] As an improvement to the above scheme, in step (3), the nanopowder obtained in step (2) by calcination under a reducing atmosphere specifically includes:

[0022] In a mixed atmosphere of N2 and H2, the temperature is increased to 800℃-1000℃ at a heating rate of 5℃ / min-15℃ / min and held for 2h-4h; wherein the volume ratio of N2 to H2 is 8:1-10:1.

[0023] The thickness of the Bi2O3 passivation layer is <5nm.

[0024] As an improvement to the above scheme, in step (4), the modified zinc oxide crude product obtained in step (3) is subjected to acid washing, water washing, and drying, specifically including:

[0025] The modified zinc oxide crude product was acid-washed with an acid solution, then washed with deionized water until neutral, and finally vacuum dried.

[0026] The acid solution has a molar concentration of 0.05 mol / L to 0.3 mol / L, the solid-liquid ratio of the modified zinc oxide crude product to the acid solution is 1:(40-60), and the pickling time is 20 min to 60 min.

[0027] The present invention also provides an aqueous zinc-ion battery, wherein the negative electrode of the aqueous zinc-ion battery is modified zinc oxide for aqueous zinc-ion batteries;

[0028] The electrolyte of the aqueous zinc-ion battery contains ZnSO4 and MnSO4.

[0029] Implementing this invention has the following beneficial effects:

[0030] In this invention, the modified zinc oxide material uses spinel-type zinc aluminate ZnAl2O4 formed by introducing Al as a matrix framework. The spinel-type zinc aluminate ZnAl2O4 has a cubic crystal system (space group Fd-3m). 2+ Occupying the tetrahedral interstices, Al 3+ Occupying the octahedral interstices, the matrix has internal channels that allow for precise matching of Zn. 2+ Size, construct three-dimensional ion transport channels to accelerate ion migration, and by doping In within the matrix framework. 3+ Bi 3+ and rare earth R 3+ Atomic-level doping of In optimizes ion transport pathways and suppresses dendrite growth and side reactions. 3+ Doping can induce lattice distortion, forming electron hopping channels and increasing conductivity (5.3 × 10⁻⁶). -3 S / cm); Bi 3+ Doping can form a Bi2O3 nanolayer, inhibiting Zn oxidation and hydrogen evolution reaction; rare earth R 3+ Doping can reduce the density of Zn through 4f-3d orbital hybridization. 2+By desolvating the ZnO shell, its surface hydrophilicity can be controlled, thereby reducing the polarization voltage of the zinc-ion battery. Attached Figure Description

[0031] Figure 1 The above are the SEM test results (magnification 5500x) of the modified zinc oxide obtained in Example 1 of this invention.

[0032] Figure 2 The above are the SEM test results (magnification 20000x) of the modified zinc oxide obtained in Example 1 of this invention. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with specific examples. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0034] To address the aforementioned problems, the first aspect of this invention provides a modified zinc oxide for aqueous zinc-ion batteries, with the molecular formula (ZnO). x [In a Bi β R c The modified zinc oxide has a spinel-type zinc aluminate ZnAl2O4·zH2O matrix framework with a ZnO shell and internal pores, and is doped with In. 3+ Bi 3+ and rare earth R 3+ .

[0035] In this invention, the modified zinc oxide material uses spinel-type zinc aluminate ZnAl2O4 formed by introducing Al as a matrix framework. The spinel-type zinc aluminate ZnAl2O4 has a cubic crystal system (space group Fd-3m). 2+ Occupying the tetrahedral interstices, Al 3+ Occupying the octahedral interstices, the matrix has internal channels that allow for precise matching of Zn. 2+ Size, construct three-dimensional ion transport channels to accelerate ion migration, and by doping In within the matrix framework. 3+ Bi 3+ and rare earth R 3+ Atomic-level doping of In optimizes ion transport pathways and suppresses dendrite growth and side reactions. 3+ Doping can induce lattice distortion, forming electron hopping channels and increasing conductivity (5.3 × 10⁻⁶). -3 S / cm); Bi3+ Doping can form a Bi2O3 nanolayer, inhibiting Zn oxidation and hydrogen evolution reaction; rare earth R 3+ Doping can reduce the density of Zn through 4f-3d orbital hybridization. 2+ Desolvation energy. The ZnO shell can regulate its surface hydrophilicity, thereby reducing the polarization voltage of zinc-ion batteries.

[0036] Specifically, a:β:x:c = 0.1-0.3:0.05-0.2:0.8-1.2:0.01-0.1. Where a is the mole fraction of In, the dopant element, in spinel-type zinc aluminate. 3+ Partially replaces Al 3+ Introducing electronic defects reduces battery polarization. Simultaneously, In possesses a high hydrogen evolution overpotential, which can suppress the hydrogen evolution side reaction on the Zn anode surface in aqueous electrolytes, extending cycle life. However, if the α value is too large, it can lead to the precipitation of In₂O₃ impurity phase, damaging the spinel framework and reducing structural stability. β represents the molar fraction of Bi, the dopant element, in spinel-type zinc aluminate. 3+ The large ionic radius can broaden the spinel lattice channels and promote Zn 2+ The diffusion of Bi, and the strong oxygen affinity of Bi can form a Bi-O-Zn interface layer, inhibiting dendrite growth. If the β value is too large, it is easy to segregate at the grain boundaries, forming an insulating layer, which in turn increases the interface impedance. c is the mole fraction of rare earth element R in spinel-type zinc aluminate, R 3+ Large ionic radii occupy interstitial spaces or surface sites, suppressing lattice distortion during cycling and reducing side reactions in electrodes and electrolytes. However, excessively high c-values ​​may lead to lattice stress cracking due to ionic radius mismatch. x represents the molar ratio of the zinc oxide phase, controlling the ratio of the ZnO shell to the spinel matrix. When x < 0.8, the ZnO shell is too thin, providing insufficient interfacial protection; when x > 1.2, the matrix proportion decreases, resulting in lower ion channel density. z represents the molar fraction of bound water in the modified zinc oxide. Bound water can stabilize surface hydroxyl groups through hydrogen bonding, inhibiting hydrogen evolution reactions. If z = 0, the hydrogen evolution overpotential decreases by 150 mV, exacerbating side reactions.

[0037] In some embodiments, a = 0.1-0.3; β = 0.05-0.2; c = 0.01-0.1; x = 0.8-1.2; z = 0.3-0.7.

[0038] Preferably, the rare earth element R is selected from at least one of La, Ce, or Y, forming La 3+ Ce 3+ Y 3+ The ionic radius has a lattice mismatch of <0.5% with spinel, and it can interact with Zn through its 4f orbitals. 2+ 3d orbital hybridization of Zn 2+The desolvation energy decreases from 1.2 eV to 0.8 eV and below. It should be noted that the 1.2 eV and 0.8 eV desolvation energies are DFT calculated values. If the rare earth element R is chosen to be a rare earth other than La, Ce, or Y, such as Nd, the capacity retention after 2000 cycles will decrease to 85% or below, and the polarization voltage will increase to 0.15 V or even higher.

[0039] Furthermore, the matrix framework contains channels with a pore size of 2.8 Å to 3.2 Å. In this case, the pore size of the spinel matrix can be compared with that of hydrated Zn. 2+ The radius is highly adapted, promoting the construction of unobstructed three-dimensional ion transport channels, enabling Zn... 2+ diffusion coefficient D Zn2+ Upgraded to 3×10 -9 cm² / s - 3.5 × 10 -9 Within the cm² / s range, compared to traditional zinc oxide materials, the zinc ion diffusion coefficient D... Zn2+ Increase by more than 200%.

[0040] Furthermore, the thickness of the ZnO shell is 10nm-50nm, which can further extend the cycle stability of the aqueous zinc-ion battery, increase capacity, and reduce polarization voltage, ensuring that the polarization voltage at 5C is no greater than 0.08V. If the thickness of the ZnO shell is <10nm, the coverage of the spinel-type zinc aluminate ZnAl2O4 matrix framework is incomplete, leading to an increase in the side reaction rate of approximately 30%. If the thickness of the ZnO shell is >50nm, the zinc ion diffusion path is prolonged, resulting in an increase in the polarization voltage of the aqueous zinc-ion battery of approximately 85%. In some embodiments, when the thickness of the ZnO shell is 60nm, the polarization voltage of the aqueous zinc-ion battery increases to 0.15V. Exemplarily, the thickness of the ZnO shell is 10nm, 15nm, 20nm, 25nm, 30nm, 35nm, 40nm, 45nm, or 50nm, but is not limited to these.

[0041] A second aspect of the present invention also provides a method for preparing modified zinc oxide, comprising the following steps:

[0042] (1) Zinc salt, aluminum salt, indium salt, bismuth salt and rare earth salt are dissolved in deionized water in proportion and the precursor is synthesized by hydrothermal reaction;

[0043] (2) The precursor obtained in step (1) is mixed with a template agent and then spray-dried to obtain nanoparticles;

[0044] (3) The nanoparticles obtained in step (2) are calcined in a reducing atmosphere to form a Bi2O3 passivation layer on the surface of the matrix framework and a ZnO shell to obtain a modified zinc oxide crude product.

[0045] (4) The modified zinc oxide crude product obtained in step (3) is acid washed and dried to obtain the modified zinc oxide.

[0046] Specifically, in step (1), the metal ions in zinc salt, aluminum salt, indium salt, bismuth salt and rare earth salt can be hydrolyzed under hydrothermal conditions to form hydroxy complexes, which are then dehydrated and condensed to form a precursor containing a mixture of metal hydroxides and basic salts, and the precursor is induced to form a layered or spinel precursor structure.

[0047] Furthermore, the zinc salt, aluminum salt, indium salt, bismuth salt, and rare earth salt are dissolved in deionized water in a Zn:Al:In:Bi:R molar ratio of 1:(1.5-2.5):(0.1-0.3):(0.05-0.2):(0.01-0.1) to ensure that each metal ion enters the precursor lattice in a preset ratio, preventing the segregation of dopant elements during subsequent synthesis. Exemplary ratios can be 1:1.5:0.1:0.05:0.01, 1:2.5:0.1:0.05:0.01, 1:2:0.2:0.1:0.05, 1:2.5:0.3:0.2:0.1, 1:1.5:0.1:0.2:0.1, 1:1.5:0.3:0.05:0.01, 1:1.5:0.1:0.05:0.1, but are not limited to these.

[0048] Optionally, the hydrothermal reaction temperature is 180℃-220℃, and the reaction time is 12h-24h. Understandably, after the hydrothermal reaction is completed, the precursor can be obtained by sequential centrifugation and drying.

[0049] Specifically, in step (2), after the precursor and template agent are mixed, the template agent coats the precursor particles as a pore-forming agent and organizes the aggregation of particles. Then, after spray drying, the mixture of precursor and template agent can be atomized into droplets, and the moisture evaporates instantly in hot air. The template agent and precursor in the droplets quickly self-assemble, and the template agent forms pores through phase separation during the drying process.

[0050] Preferably, the average particle size of the nanoparticles obtained in step (2) is 50nm-200nm, which can further improve the specific capacity of the aqueous zinc-ion battery and extend its cycle life. If the average particle size of the nanoparticles is too large, the polarization will increase due to the extended diffusion path of zinc ions. For example, the average particle size of the nanoparticles obtained in step (2) is 50nm, 70nm, 90nm, 100nm, 120nm, 140nm, 160nm, 180nm, or 200nm, but is not limited to these.

[0051] Furthermore, the mass ratio of the precursor to the template agent is 1:(0.1-0.3), which can control the pore size of the channels inside the matrix framework. The template agent includes, but is not limited to, a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer (P123).

[0052] In some embodiments, the inlet air temperature during spray drying is 180℃-220℃, which allows the moisture on the droplet surface to evaporate rapidly, forming a semi-solid shell. This promotes the full migration of the template agent and the diffusion and segregation of metal ions within the droplets, ensuring the uniform distribution of dopant elements during subsequent calcination. It also promotes the formation of nanoparticles with specific particle sizes, further improving the capacity, rate capability, and cycle life of aqueous zinc-ion batteries.

[0053] Specifically, in step (3), the nanoparticles obtained by calcining step (2) under a reducing atmosphere specifically include:

[0054] In a mixed atmosphere of N2 and H2, the temperature is increased to 800℃-1000℃ at a heating rate of 5℃ / min-15℃ / min and held for 2h-4h.

[0055] In this step, during the initial calcination stage, the hydroxides and basic salts in the nanoparticles decompose upon heating into ZnO, Al2O3, and doped oxides In2O3, Bi2O3, and R2O3. Subsequently, at 800℃-1000℃, ZnO and Al2O3 react to form spinel-type zinc aluminate ZnAl2O4, while Bi2O3, which did not enter the spinel phase, remains in the spinel phase. 3+ During calcination, the ZnO diffuses to the surface. In a reducing atmosphere, some Bi2O3 can be reduced to Bi2O2 or metallic Bi nanoclusters. These substances are then re-oxidized during cooling, forming a dense, nanometer-thick Bi2O3 passivation layer on the spinel phase surface. Simultaneously, Zn is in excess relative to Al in the precursor, and the remaining excess ZnO migrates from the interior of the particles to the surface, forming an independent ZnO phase. The reducing atmosphere accelerates the diffusion of ZnO, thereby forming a continuous, dense, and uniformly thick ZnO shell on the surface of the spinel phase ZnAl2O4 and the Bi2O3 passivation layer.

[0056] Controlling the heating rate to 5℃ / min-15℃ / min ensures that the decomposition of nanoparticles is gradual, promotes uniform spinelization, and ensures the continuity and density of the ZnO shell and Bi2O3 passivation layer.

[0057] Optionally, in a mixed atmosphere of N2 and H2, the volume ratio of N2 to H2 is 8:1-10:1, which can moderately introduce vacancies, promote ZnO migration and Bi segregation, and form an ideal ZnO shell and Bi2O3 passivation layer.

[0058] Furthermore, the thickness of the Bi₂O₃ passivation layer is <5 nm, which can suppress Zn oxidation and hydrogen evolution reactions, reducing the corrosion current density of the aqueous zinc-ion battery to 1.3 × 10⁻⁶. -7 A / cm 2 Compared to pure zinc anodes, this can reduce the size by two orders of magnitude.

[0059] Specifically, in step (4), the modified zinc oxide crude product obtained in step (3) is subjected to acid washing, water washing, and drying, specifically including:

[0060] The modified zinc oxide crude product was acid-washed with an acid solution, then washed with deionized water until neutral, and finally vacuum dried.

[0061] In this step, acid washing of the modified zinc oxide crude product can remove impurities such as Bi2O3 particles and basic carbonates attached to the ZnO shell, while also enhancing the hydrophilicity of the ZnO shell, further improving zinc ion transport efficiency, and reducing desolvation ability; subsequent drying can precisely adjust the z value in the molecular formula and optimize its electrochemical performance.

[0062] Preferably, the molar concentration of the acid solution is 0.05 mol / L-0.3 mol / L, the solid-liquid ratio of the modified zinc oxide crude product to the acid solution is 1:(40-60), and the pickling time is 20 min-60 min. If the molar concentration of the acid solution is too high, it will cause partial dissolution of the spinel matrix, which will lead to an increase in corrosion current and a shortened cycle life.

[0063] Optionally, the modified zinc oxide crude product can be acid-washed using ultrasound at room temperature, which has good results. The acid solution can be hydrochloric acid solution, nitric acid solution, etc.

[0064] Furthermore, the drying temperature is 50℃-70℃, and the time is 10h-14h.

[0065] This invention achieves a breakthrough in the performance of zinc-ion battery anode materials through multiple adjustments to the molecular formula, pore size, ZnO shell thickness, and doping elements. These materials combine high energy density, long cycle life, and safety, providing key material support for large-scale energy storage applications.

[0066] A third aspect of the present invention also provides an aqueous zinc-ion battery, wherein the negative electrode of the aqueous zinc-ion battery is modified zinc oxide; and the electrolyte of the aqueous zinc-ion battery contains ZnSO4 and MnSO4.

[0067] In this invention, the modified zinc oxide is used as the negative electrode of an aqueous zinc-ion battery, which enables the battery to achieve a specific capacity of over 800 mAh / g at 0.2C and retain over 90% of its capacity after 2000 cycles. The resulting aqueous zinc-ion battery is suitable for applications such as grid-scale energy storage and flexible electronic devices, offering high cost-effectiveness and environmental friendliness.

[0068] Optionally, in the electrolyte, the molar concentration of ZnSO4 is 1.5 mol / L-2.5 mol / L, and the molar concentration of MnSO4 is 0.05 mol / L-0.2 mol / L.

[0069] The present invention will be further described below with reference to specific embodiments:

[0070] Example 1

[0071] This embodiment provides a modified zinc oxide for aqueous zinc-ion batteries, with the molecular formula (ZnO). 0.9 [In 0.2 Bi 0.1 La 0.05 Al₂O₃•0.5H₂O. Its preparation method is as follows:

[0072] (1) With a molar ratio of Zn:Al:In:Bi:La=1:2:0.2:0.1:0.05, Zn(NO3)2•6H2O, Al(NO3)3•9H2O, In(NO3)3, Bi(NO3)3, and La(NO3)3 were dissolved in deionized water, and then hydrothermal reaction was carried out at a constant temperature of 200℃ for 18h. Finally, the precursor was obtained by centrifugation and drying.

[0073] (2) The precursor and template agent P123 were mixed at a mass ratio of 1:0.2, the air inlet temperature was controlled at 200℃, and the nanoparticles with an average particle size of 120nm were obtained by spray drying.

[0074] (3) Under a mixed atmosphere of N2 and H2 with a volume ratio of 9:1, the temperature was raised to 950℃ at a heating rate of 10℃ / min to calcine the nanoparticles, forming a Bi2O3 passivation layer on the surface of the matrix framework and a ZnO shell layer, thus obtaining the modified zinc oxide crude product.

[0075] (4) The modified zinc oxide crude product was acid-washed by ultrasonication at room temperature for 30 min with 0.1 mol / L hydrochloric acid solution, and the solid-liquid ratio was controlled at 1:50. Then it was washed with deionized water until pH=7, and finally vacuum dried at 60℃ for 12 h to obtain the modified zinc oxide.

[0076] The modified zinc oxide obtained in Example 1 was scanned by SEM, and the test results are shown in [Figure 1]. Figure 1 , Figure 2 .

[0077] Depend on Figure 1 and Figure 2 As can be seen, the modified zinc oxide obtained by the above preparation method in this application uses spinel-type zinc aluminate ZnAl2O4 as the matrix framework, has a ZnO shell on the surface, and has channels inside the matrix framework. At the same time, the surface of the spinel-type zinc aluminate is also covered with dot-like, plate-like, and irregular crystals, indicating that In is doped in the spinel-type zinc aluminate. 3 + Bi 3+ and rare earth La 3+ .

[0078] Example 2

[0079] This embodiment provides a modified zinc oxide for aqueous zinc-ion batteries, with the molecular formula (ZnO). 0.9 [In 0.2 Bi 0.1 La 0.05 Al₂O₃•0.5H₂O. Its preparation method is basically the same as in Example 1, except that:

[0080] In step (2), the air inlet temperature is controlled at 220°C, and nanoparticles with an average particle size of 200 nm are obtained by spray drying.

[0081] Example 3

[0082] This embodiment provides a modified zinc oxide for aqueous zinc-ion batteries, with the molecular formula (ZnO). 0.9 [In 0.2 Bi 0.1 La 0.05 Al₂O₃•0.5H₂O. Its preparation method is basically the same as in Example 1, except that:

[0083] Step (4) The modified zinc oxide crude product was acid-washed by ultrasonication at room temperature for 30 min using 0.5 mol / L hydrochloric acid solution.

[0084] Comparative Example 1

[0085] This comparative example provides a conventional zinc oxide with a purity of 99.0%.

[0086] Comparative Example 2

[0087] This comparative example provides a modified zinc oxide for aqueous zinc-ion batteries, with the molecular formula (ZnO). 0.9 [In 0.2 Bi 0.1 Nd 0.05 Al2O3•0.5H2O. Its preparation method is the same as in Example 1.

[0088] Application example:

[0089] The zinc oxide obtained in Examples 1-3 and Comparative Examples 1-2 was used as the negative electrode of an aqueous zinc-ion battery, and manganese-based oxide (MnO2) was used as the positive electrode. The electrolyte was a mixture of ZnSO4 and 0.1 mol / L MnSO4.

[0090] The performance of the obtained aqueous zinc-ion battery was tested, as follows:

[0091] 1. Specific capacity: The battery under test is subjected to constant current charge-discharge test at a rate of 0.2C, and its specific capacity is calculated;

[0092] 2. Cyclic performance: The battery under test is subjected to a cycle performance test at a rate of 0.1C until the capacity decays to 80% of the initial capacity. The number of cycles and the capacity retention rate after the target number of cycles (2000 cycles) are recorded, and the polarization differential pressure is calculated.

[0093] 3. Polarization voltage: When performing cyclic testing at a 5C rate, record the voltage after the target number of cycles (2000 times) and calculate the polarization voltage.

[0094] 4. Corrosion current: The corrosion current was tested after a target number of cycles (2000 cycles) by fitting the potentiodynamic polarization curve using the Tafel extrapolation method.

[0095] The test results are shown in Table 1.

[0096] Table 1. Test results of the examples and comparative examples

[0097]

[0098] As can be seen from the above results, the modified zinc oxide in this invention uses spinel-type zinc aluminate ZnAl2O4 formed by Al as the matrix framework. The outer layer of the matrix framework has a ZnO shell. Through multiple controls of molecular formula, pore size, ZnO shell thickness, doping elements and acid washing process, it has high energy density, long cycle life and safety, with a specific capacity of 820mAh / g, a capacity retention rate of 92% after 2000 cycles and a polarization voltage as low as 0.08V.

[0099] The technical features of the embodiments described above can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A method for preparing modified zinc oxide for aqueous zinc-ion batteries, characterized in that, Includes the following steps: (1) Zinc salt, aluminum salt, indium salt, bismuth salt and rare earth salt are dissolved in deionized water in proportion and the precursor is synthesized by hydrothermal reaction; (2) The precursor obtained in step (1) is mixed with a template agent and then spray-dried to obtain nanoparticles; (3) The nanoparticles obtained in step (2) are calcined in a reducing atmosphere to form a Bi2O3 passivation layer on the surface of the matrix framework and a ZnO shell layer, thus obtaining a modified zinc oxide crude product. (4) The modified zinc oxide crude product obtained in step (3) is acid washed and dried to obtain the modified zinc oxide; The molecular formula of the modified zinc oxide is (ZnO). x [In a Bi β R c Al₂O₄·zH₂O, where a:β:x:c = 0.1-0.3: 0.05-0.2: 0.8-1.2: 0.01-0.1, z = 0.3-0.7; The modified zinc oxide has a spinel-type zinc aluminate ZnAl2O4 matrix framework with a ZnO shell and internal pores, and is doped with In. 3+ Bi 3+ and rare earth R 3+ Rare earth element R is selected from at least one of La, Ce, or Y. In step (1), the zinc salt, aluminum salt, indium salt, bismuth salt and rare earth salt are dissolved in deionized water in a molar ratio of Zn:Al:In:Bi:R of 1:(1.5-2.5):(0.1-0.3):(0.05-0.2):(0.01-0.1); In step (1), the hydrothermal reaction temperature is 180℃-220℃ and the reaction time is 12h-24h.

2. The method for preparing modified zinc oxide for aqueous zinc-ion batteries according to claim 1, characterized in that, The matrix framework has pores with a diameter of 2.8 Å to 3.2 Å inside.

3. The method for preparing modified zinc oxide for aqueous zinc-ion batteries according to claim 1, characterized in that, The thickness of the ZnO shell is 10nm-50nm.

4. The method for preparing modified zinc oxide for aqueous zinc-ion batteries according to claim 1, characterized in that, The zinc ion diffusion coefficient D of the modified zinc oxide Zn2+ 3×10 -9 cm² / s - 3.5 × 10 -9 cm² / s, polarization voltage ΔE@5C≤0.08V.

5. The method for preparing modified zinc oxide for aqueous zinc-ion batteries as described in claim 1, characterized in that, In step (2), the mass ratio of the precursor to the template agent is 1:(0.1-0.3). The average particle size of the nanopowder is 50nm-200nm; The inlet air temperature during spray drying is 180℃-220℃.

6. The method for preparing modified zinc oxide for aqueous zinc-ion batteries as described in claim 1, characterized in that, In step (3), the nanoparticles obtained in step (2) are specifically calcined under a reducing atmosphere, including: In a mixed atmosphere of N2 and H2, the temperature is increased to 800℃-1000℃ at a heating rate of 5℃ / min-15℃ / min and held for 2h-4h; wherein the volume ratio of N2 to H2 is 8:1-10:

1. The thickness of the Bi2O3 passivation layer is <5nm.

7. The method for preparing modified zinc oxide for aqueous zinc-ion batteries as described in claim 1, characterized in that, In step (4), the modified zinc oxide crude product obtained in step (3) is subjected to acid washing, water washing, and drying, specifically including: The modified zinc oxide crude product was acid-washed with an acid solution, then washed with deionized water until neutral, and finally vacuum dried. The acid solution has a molar concentration of 0.05 mol / L to 0.3 mol / L, the solid-liquid ratio of the modified zinc oxide crude product to the acid solution is 1:(40-60), and the pickling time is 20 min to 60 min.

8. An aqueous zinc-ion battery, characterized in that, The negative electrode of the aqueous zinc-ion battery is prepared using modified zinc oxide for aqueous zinc-ion batteries according to any one of claims 1-7. The electrolyte of the aqueous zinc-ion battery contains ZnSO4 and MnSO4.

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