KR102475398B1 - Cathod for zinc-ion batteries, the manufacturing method thereof and zinc-ion batteries comprising the same - Google Patents

Abstract

The present invention relates to a positive electrode for a zinc-ion battery, a manufacturing method thereof, and a zinc-ion battery including the same, wherein the positive electrode for a zinc-secondary battery according to the present invention includes a metal-doped metal oxide, wherein the metal oxide , It includes at least one shape selected from the group consisting of nanorods, nanotubes, nanoneedles, and nanowires.

Description

Anode for zinc-ion battery, manufacturing method thereof, and zinc-ion battery including the same

The present invention relates to a positive electrode for a zinc-ion battery, a manufacturing method thereof, and a zinc-ion battery including the same.

Environmental concerns and energy concerns over the use of fossil fuels have generated increasing interest in generating electrical energy using renewable energy sources such as solar and wind. However, the output of solar and wind power is not stable and constant on a regular basis due to unexpectedly varied environmental and geographic conditions. To efficiently utilize variable renewable and clean energy, large-scale electrical energy storage (EES) systems that can achieve high energy/power densities and excellent cycling stability are needed.

As the most common energy storage device, lithium-ion batteries (LIBs) are expected to be the solution. However, the use of lithium has disadvantages of low safety, limited supply, uneven distribution and high cost. In this regard, rechargeable batteries, especially water-based batteries based on earth-abundant Al, Mg and Zn, have attracted attention because they use low-cost and safe aqueous electrolytes. Among them, zinc-ion batteries (ZIBs) have low cost, non-toxicity, high theoretical specific capacity of 820 mA hg ^-1 , relatively low redox potential of -0.76 V relative to standard hydrogen electrode and They are attracting increasing attention as a reasonable alternative to LIBs because they offer excellent electrochemical stability in aqueous electrolytes due to their high overpotential for hydrogen evolution.

In addition, ZIBs operate through a two-electron transport mechanism, resulting in higher energy densities compared to Li-ion or Na-ion cells. Nevertheless, ZIBs are often hampered by cathode materials that exhibit limited specific capacity and poor rate performance. Although positive electrode materials for ZIBs have been actively reported so far, the low specific capacity of ~50 mA ^hg for Prussian blue analogs, which can be an important factor limiting practical applications, and Mn ²⁺ dissolution and dissolution during cycling. Therefore, it still suffers from poor energy storage performance degradation such as fast specific capacity fading and low rate performance for manganese-based anodes.

In order to solve the above problems, the present invention provides a positive electrode for a zinc-ion battery having an increased electroactive site, improved electrical conductivity, high specific capacity, high rate performance and high cycling stability, a manufacturing method thereof, and a zinc-ion battery including the same. is to provide

However, the problem to be solved by the present invention is not limited to those mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

A positive electrode for a zinc-secondary battery according to an embodiment of the present invention includes a metal-doped metal oxide, wherein the metal oxide is at least one selected from the group consisting of nanorods, nanotubes, nanoneedles, and nanowires. contain one shape.

In one embodiment, the metal is silver (Ag), copper (Cu), nickel (Ni), aluminum (Al), iron (Fe), cobalt (Co), tantalum (Ta), tungsten (W), Molybdenum (Mo) Niobium (Nb), Antimony (Sb), Tin (Sn), Hafnium (Hf), Silicon (Si), Palladium (Pd), Titanium (Ti), Zirconium (Zr), Calcium (Ca), Germanium Including at least one selected from the group consisting of (Ge), gallium (Ga), indium (In), ruthenium (Ru), tellurium (Te), chromium (Cr), vanadium (V) and titanium (Ti) it may be

In one embodiment, the metal may be 0.5 at% to 15 at% of the metal oxide.

In one embodiment, the metal oxide is V ₂ O ₅ , V ₆ O ₁₃ , ZnO, MgO, SnO ₂ , WO ₃ , Al ₂ O ₃ , Fe ₂ O ₃ , Fe ₃ O ₄ , NiO, TiO ₂ , MnO ₂ , Mn ₂ O ₃ , Mn ₃ O ₄ , CuO, Cu ₂ O, Co ₃ O ₄ , CeO ₂ , In ₂ O ₃ , ZrO ₂ , Cr ₃ O ₄ , Pr ₆ O ₁₁ , Nd ₂ O ₃ , Sm ₂ O ₃ , Eu ₂ O ₃ , Gd ₂ O ₃ , Tb ₄ O ₇ , Dy ₂ O _{3 ,} Ho ₂ O 3 , Er 2 O ₃ , Yb ₂ O ₃ , Lu _{2 O 3} , Zn ₂ SnO ₄ , LaCoO ₃ , LaMnO ₃ , LaFeO ₃ , LaNiO ₃ , LaCuO ₃ , NiCo ₂ O ₄ , Ca ₂ Mn ₃ O ₈ , Ag ₂ V ₄ O ₁₁ , InTaO ₄ , InTaO ₄ , Ga ₂ O ₃ , CaCu ₃ Ti ₄ O ₁₂ , Ag ₃ PO ₄ , BaTiO ₃ , NiTiO ₃ , SrTiO ₃ , Nb ₂ O ₅ , B ₂ O ₃ Sr ₂ Nb ₂ O ₇ , Sr ₂ Ta ₂ O _{7 ,} La _1-x Sr _x CoO ₃ , La It may include one or more selected from the group consisting of _1-x Sr _x MnO ₃ and Ba _0.5 Sr _0.5 Co _0.8 Fe _0.2 O _3-δ .

In one embodiment, the metal oxide may have a diameter of 1 nm to 50 nm, a length of 100 nm to 800 nm, and an aspect ratio of 1:100 to 50:800.

A method of manufacturing a cathode for a zinc-secondary battery according to another embodiment of the present invention includes preparing a nanofiber template by electrospinning a polymer; Preparing a metal-doped nanofiber template by immersing the nanofiber template in a dispersion solution in which a doped metal and a metal oxide precursor are dissolved; and drying and heat-treating the metal-doped nanofiber template.

In one embodiment, the step of preparing a nanofiber template by electrospinning the polymer, a polymer solution in which the polymer is dissolved in a solvent is applied at an applied voltage of 1 kV to 20 kV and 0.01 L h ^-1 to 10 L h ^- At a feed rate of ¹ , a nanofiber template is prepared by electrospinning by positioning the distance between the needle tip and the current collector at 5 cm to 15 cm, and the polymer is polyvinylpyrrolidone (PVP), poly polyvinylidene fluoride (PVDF), polyvinyl alcohol (PVA), polyvinyl acetate (PVAc), polystyrene (PS), polymethyl methacrylate (PMMA), Poly(n-butyl acrylate) (PBA), polyacrylonitrile (PAN), polyaniline (PANi), polyacrylic acid (PAA), polyester-amide (polyester-amides; PEA), polyethylene (PE), polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), polyurethane (PU), polychloroprene, It includes at least one selected from the group consisting of polyisoprene and polybutadiene, and the solvent is N, N-dimethylformamide, phenol, acetone, toluene, tetrahydrofuran, distilled water, ethanol, methanol , It may include at least one selected from the group consisting of propanol, butanol, isopropanol, and alcohol-based substances.

In one embodiment, the step of preparing a metal-doped nanofiber template by immersing the nanofiber template in a dispersion solution in which the doped metal and metal oxide precursor are dissolved, wherein the doped metal and metal oxide precursor are dissolved in distilled water. After immersing the nanofiber template in the prepared dispersion solution for 30 minutes to 5 hours, the metal-doped nanofiber template may be filtered using a mesh net.

In one embodiment, the doped metal is silver (Ag), copper (Cu), nickel (Ni), aluminum (Al), iron (Fe), cobalt (Co), tantalum (Ta), tungsten (W) , Molybdenum (Mo) Niobium (Nb), Antimony (Sb), Tin (Sn), Hafnium (Hf), Silicon (Si), Palladium (Pd), Titanium (Ti), Zirconium (Zr), Calcium (Ca), At least one selected from the group consisting of germanium (Ge), gallium (Ga), indium (In), ruthenium (Ru), tellurium (Te), chromium (Cr), vanadium (V) and titanium (Ti) The metal oxide precursor includes acetate, chloride, acetylacetonate, nitrate, methoxide, ethoxide, butoxide, isopropoxide, sulfate, oxytriisopropoxide, (ethyl or cetylethyl) It may include a metal salt having at least one form selected from the group consisting of hexanoate, butanoate, ethylamide and amide.

In one embodiment, the step of drying and heat-treating the metal-doped nanofiber template, after drying the metal-doped nanofiber template in a temperature range of 40 ℃ to 90 ℃ for 5 minutes to 2 hours, 500 It may be heat treatment for 30 minutes to 10 hours at a temperature range of ℃ to 800 ℃.

A zinc-secondary battery according to another embodiment of the present invention includes a positive electrode for a zinc-secondary battery according to an embodiment of the present invention; zinc-anode for secondary batteries; a separator interposed between the zinc-secondary battery positive electrode and the zinc-secondary battery negative electrode; and an electrolyte.

The positive electrode for a zinc-secondary battery according to the present invention has increased electroactive sites, improved electrical conductivity, high specific capacity, high rate performance and high cycling stability.

The metal doping effect of the anode for a zinc-secondary battery according to an embodiment of the present invention can provide an increased number of electroactive sites and improved electrical conductivity in a metal oxide matrix, which provides high capacity and excellent electrical conductivity for a zinc-secondary battery. Provided speed performance. In addition, the nanorod structure can exhibit improved ion-dispersion kinetics to provide long cycle life with cycling stability. These electrochemical results and insight into the Zn ion storage mechanism can be realized as a sustainable next-generation energy storage system.

1 is a cross-sectional view of a positive electrode for a zinc-secondary battery according to the present invention.
2 is a flowchart illustrating a manufacturing process of a positive electrode for a zinc-secondary battery according to an embodiment of the present invention.
3 is a schematic diagram showing a selective growth process of Fe-doped V ₂ O ₅ having a rod-like structure as an advanced cathode for a zinc ion battery (ZIB) according to an embodiment of the present invention.
4 is a view showing morphological characteristics of bare V ₂ O ₅ , 1Fe-V ₂ O ₅ , 5Fe-V ₂ O ₅ and 10Fe-V ₂ O ₅ according to an embodiment of the present invention.
5 shows XRD patterns of bare V ₂ O ₅ , 1Fe-V ₂ O ₅ , 5Fe-V ₂ O ₅ and 10Fe-V ₂ O ₅ according to an embodiment of the present invention.
6 shows TEM results of bare V ₂ O ₅ , 1Fe-V ₂ O ₅ , 5Fe-V ₂ O ₅ and 10Fe-V ₂ O ₅ according to an embodiment of the present invention.
7 shows summarized lattice parameter results of bare V ₂ O ₅ , 1Fe-V ₂ O ₅ , 5Fe-V ₂ O ₅ and 10Fe-V ₂ O ₅ according to an embodiment of the present invention.
8 shows a Williamson-Hall plot of bare V ₂ O ₅ , 1Fe-V ₂ O ₅ , 5Fe-V ₂ O ₅ and 10Fe-V ₂ O ₅ according to an embodiment of the present invention.
9 to 12 show XPS spectra of bare V ₂ O ₅ , 1Fe-V ₂ O ₅ , 5Fe-V ₂ O ₅ and 10Fe-V ₂ O ₅ according to embodiments of the present invention.
13 to 16 are views showing electrochemical kinetic characteristics of bare V ₂ O ₅ , 1Fe-V ₂ O ₅ , 5Fe-V ₂ O ₅ and 10Fe-V ₂ O ₅ according to embodiments of the present invention.
17 is a galvanic charge-discharge curve of bare V ₂ O ₅ , 1Fe-V ₂ O ₅ , 5Fe-V ₂ O ₅ and 10Fe-V ₂ O ₅ at a current density of 0.5 A g ^-1 according to an embodiment of the present invention. .
18 is a galvanic charge-discharge curve of two devices composed of 5Fe-V ₂ O ₅ connected in series according to an embodiment of the present invention.
19 shows 0.4-1.6 V and 0.5-2.0 A g ^-1 of bare V ₂ O ₅ , 1Fe-V ₂ O ₅ , 5Fe-V ₂ O ₅ and 10Fe-V ₂ O ₅ , respectively, according to an embodiment of the present invention. It is a diagram showing the comparative rate performance at the potential and current density of
20 is a diagram showing the comparative performance of 5Fe-V ₂ O ₅ including the previously reported performance of ZIB.
21 is a current density of 1.3 mA g ^-1 for up to 160 cycles of bare V ₂ O ₅ , 1Fe-V ₂ O ₅ , 5Fe-V ₂ O ₅ and 10Fe-V ₂ O ₅ according to an embodiment of the present invention. It is a diagram showing the cycling stability of the fabricated ZIB.
22 is EIS of (b) bare V ₂ O ₅ , (c) 1Fe-V ₂ O ₅ , (d) 5Fe-V ₂ O ₅ and (e) 10Fe-V ₂ O ₅ according to an embodiment of the present invention. it's a spectrum
23 is a diagram showing a Ragone plot comparing energy and power densities of 5Fe-V ₂ O ₅ according to an embodiment of the present invention with those of previously reported rechargeable batteries.
24 is a schematic representation of the advantages of 5Fe—V ₂ O ₅ including a combination of increased number of electroactive sites, improved electrical conductivity, and improved ionic diffusion kinetics according to an embodiment of the present invention.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. However, since various changes can be made to the embodiments, the scope of the patent application is not limited or limited by these embodiments. It should be understood that all changes, equivalents or substitutes to the embodiments are included within the scope of rights.

Terms used in the examples are used only for descriptive purposes and should not be construed as limiting. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, terms such as "include" or "have" are intended to designate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but one or more other features It should be understood that the presence or addition of numbers, steps, operations, components, parts, or combinations thereof is not precluded.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the art to which the embodiment belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and unless explicitly defined in the present application, they should not be interpreted in an ideal or excessively formal meaning. don't

In addition, in the description with reference to the accompanying drawings, the same reference numerals are given to the same components regardless of reference numerals, and overlapping descriptions thereof will be omitted. In describing the embodiment, if it is determined that a detailed description of a related known technology may unnecessarily obscure the gist of the embodiment, the detailed description will be omitted.

In addition, in describing the components of the embodiment, terms such as first, second, A, and B may be used. These terms are only used to distinguish the component from other components, and the nature, order, or order of the corresponding component is not limited by the term.

Components included in one embodiment and components including common functions will be described using the same names in other embodiments. Unless stated to the contrary, descriptions described in one embodiment may be applied to other embodiments, and detailed descriptions will be omitted to the extent of overlap.

A positive electrode for a zinc-secondary battery according to an embodiment of the present invention includes a metal-doped metal oxide, wherein the metal oxide is at least one selected from the group consisting of nanorods, nanotubes, nanoneedles, and nanowires. contain one shape.

The positive electrode for a zinc-secondary battery according to the present invention has increased electroactive sites, improved electrical conductivity, high specific capacity, high rate performance and high cycling stability.

Preferably, the metal oxide may have an elongated shape having an aspect ratio, and more preferably, may have a nanorod shape.

In one embodiment, the metal is silver (Ag), copper (Cu), nickel (Ni), aluminum (Al), iron (Fe), cobalt (Co), tantalum (Ta), tungsten (W), Molybdenum (Mo) Niobium (Nb), Antimony (Sb), Tin (Sn), Hafnium (Hf), Silicon (Si), Palladium (Pd), Titanium (Ti), Zirconium (Zr), Calcium (Ca), Germanium Including at least one selected from the group consisting of (Ge), gallium (Ga), indium (In), ruthenium (Ru), tellurium (Te), chromium (Cr), vanadium (V) and titanium (Ti) it may be

Preferably, the metal may include iron (Fe).

In one embodiment, the metal may be 0.5 at% to 15 at% of the metal oxide. When the metal is less than 0.5 at% of the metal oxide, the metal doping effect is insignificant, and when the metal is more than 15 at%, slow ion diffusion occurs during nucleation during formation of a metal-doped metal oxide, and a metal that serves as a metal doping source The presence of ions can lead to nanosizing of the primary structure.

In one embodiment, the metal oxide is V ₂ O ₅ , V ₆ O ₁₃ , ZnO, MgO, SnO ₂ , WO ₃ , Al ₂ O ₃ , Fe ₂ O ₃ , Fe ₃ O ₄ , NiO, TiO ₂ , MnO ₂ , Mn ₂ O ₃ , Mn ₃ O ₄ , CuO, Cu ₂ O, Co ₃ O ₄ , CeO ₂ , In ₂ O ₃ , ZrO ₂ , Cr ₃ O ₄ , Pr ₆ O ₁₁ , Nd ₂ O ₃ , Sm ₂ O ₃ , Eu ₂ O ₃ , Gd ₂ O ₃ , Tb ₄ O ₇ , Dy ₂ O _{3 ,} Ho ₂ O 3 , Er 2 O ₃ , Yb ₂ O ₃ , Lu _{2 O 3} , Zn ₂ SnO ₄ , LaCoO ₃ , LaMnO ₃ , LaFeO ₃ , LaNiO ₃ , LaCuO ₃ , NiCo ₂ O ₄ , Ca ₂ Mn ₃ O ₈ , Ag ₂ V ₄ O ₁₁ , InTaO ₄ , InTaO ₄ , Ga ₂ O ₃ , CaCu ₃ Ti ₄ O ₁₂ , Ag ₃ PO ₄ , BaTiO ₃ , NiTiO ₃ , SrTiO ₃ , Nb ₂ O ₅ , B ₂ O ₃ Sr ₂ Nb ₂ O ₇ , Sr ₂ Ta ₂ O _{7 ,} La _1-x Sr _x CoO ₃ , La It may include one or more selected from the group consisting of _1-x Sr _x MnO ₃ and Ba _0.5 Sr _0.5 Co _0.8 Fe _0.2 O _3-δ .

Preferably, the metal may include vanadium oxide, and more preferably, may be vanadium pentoxide (V ₂ O ₅ ).

1 is a schematic diagram of a positive electrode for a zinc-secondary battery according to an embodiment of the present invention.

Referring to FIG. 1 , the zinc-positive electrode 100 for a secondary battery according to an embodiment of the present invention may be Fe-doped V ₂ O ₅ nanorods.

In one embodiment, the metal oxide has a diameter of 1 nm to 50 nm, 1 nm to 40 nm, 1 nm to 30 nm, 1 nm to 20 nm, 1 nm to 10 nm, 1 nm to 20 nm, 1 nm to 30 nm, 1 nm to 40 nm, 10 nm to 50 nm, 10 nm to 40 nm, 10 nm to 30 nm, 10 nm to 20 nm, 20 nm to 50 nm, 20 nm to 40 nm, 20 nm to 30 nm nm, 30 nm to 50 nm, 30 nm to 40 nm, or 40 nm to 50 nm.

In one embodiment, the metal oxide has a length of 100 nm to 800 nm, 100 nm to 700 nm, 100 nm to 600 nm, 100 nm to 500 nm, 100 nm to 400 nm, 100 nm to 300 nm, 100 nm to 200 nm, 200 nm to 800 nm, 300 nm to 800 nm, 400 nm to 800 nm, 500 nm to 800 nm, 600 nm to 800 nm, 700 nm to 800 nm, 200 nm to 800 nm, 200 nm to 700 nm, 200 nm to 600 nm, 200 nm to 500 nm, 200 nm to 400 nm, 200 nm to 300 nm, 300 nm to 800 nm, 300 nm to 700 nm, 300 nm to 600 nm, 300 nm to 500 nm, 300 nm to 400 nm, 400 nm to 800 nm, 400 nm to 700 nm, 400 nm to 600 nm, 400 nm to 500 nm, 500 nm to 800 nm, 500 nm to 700 nm, 500 nm to 600 nm, 600 nm to 800 nm, 600 nm to 700 nm, or 700 nm to 800 nm.

In one embodiment, the metal oxide has an aspect ratio of 1:100 to 50:800, 10:100 to 50:800, 20:100 to 50:800, 30:100 to 50:800, or 40:100 to 50: It may be 800.

Preferably, the metal oxide may have a diameter of 30 nm to 50 nm, a length of 500 nm to 800 nm, and an aspect ratio of 30:500 to 50:800.

The metal doping effect of the anode for a zinc-secondary battery according to an embodiment of the present invention can provide an increased number of electroactive sites and improved electrical conductivity in a metal oxide matrix, which provides high capacity and excellent electrical conductivity for a zinc-secondary battery. Provided speed performance. In addition, the nanorod structure can exhibit improved ion-dispersion kinetics to provide long cycle life with cycling stability. These electrochemical results and insight into the Zn ion storage mechanism can be realized as a sustainable next-generation energy storage system.

A method of manufacturing a cathode for a zinc-secondary battery according to another embodiment of the present invention includes preparing a nanofiber template by electrospinning a polymer; Preparing a metal-doped nanofiber template by immersing the nanofiber template in a dispersion solution in which a doped metal and a metal oxide precursor are dissolved; and drying and heat-treating the metal-doped nanofiber template.

2 is a flowchart illustrating a manufacturing process of a positive electrode for a zinc-secondary battery according to an embodiment of the present invention.

Referring to FIG. 2, a method for manufacturing a cathode for a zinc-secondary battery according to an embodiment of the present invention includes preparing a nanofiber template step 210, preparing a metal-doped nanofiber template step 220, and drying and heat treatment steps. (230).

In one embodiment, the nanofiber template preparation step 210 is a step of preparing a nanofiber template by electrospinning a polymer.

In one embodiment, in the step of preparing the nanofiber template by electrospinning the polymer, the polymer solution in which the polymer is dissolved in a solvent is 1 kV to 20 kV, 3 kV to 20 kV, 5 kV to 20 kV, 7 kV to 20 kV, 10 kV to 20 kV, 13 kV to 20 kV, 15 kV to 20 kV, 17 kV to 20 kV, 1 kV to 17 kV, 1 kV to 15 kV, 1 kV to 13 kV, 1 kV to Applied voltages of 10 kV, 1 kV to 7 kV, 1 kV to 5 kV, 1 kV to 3 kV and 0.01 L h ^-1 to 10 L h ^-1 , 0.01 L h ^-1 to 7 L h ^-1 , 0.01 L h ^-1 to 5 L h ^-1 , 0.01 L h ^-1 to 3 L h ^-1 , 0.01 L h ^-1 to 1 L h ^-1 , 0.05 L h ^-1 to 10 L h ^-1 , 0.1 L h ^{- 1} to 10 L h ^-1 , 0.3 L h ^-1 to 10 L h ^-1 , 0.5 L h ^-1 to 10 L h -1 , 1 L h ^-1 to 10 L ^{h -1 ,} 3 L h ^-1 to At a supply rate of 10 L h ^-1 , 5 L h ^-1 to 10 L h ^-1 or 7 L h ^-1 to 10 L h ^-1 , the distance between the needle tip and the current collector is 5 cm to 15 cm, 7 cm to 15 cm, 8 cm to 15 cm, 10 cm to 15 cm, 13 cm to 15 cm, 5 cm to 13 cm, 5 cm to 10 cm, or 5 cm to 7 cm, and electrospinning to form a nanofiber template may be preparing

In one embodiment, the polymer is polyvinylpyrrolidone (PVP), polyvinylidene fluoride (PVDF), polyvinyl alcohol (PVA), polyvinyl acetate (polyvinyl acetate); PVAc), polystyrene (PS), polymethyl methacrylate (PMMA), poly(n-butyl acrylate) (PBA), polyacrylonitrile (PAN) ), polyaniline (PANi), polyacrylic acid (PAA), polyester-amides (PEA), polyethylene (PE), polyvinyl chloride (PVC), polyvinylidene It may include at least one selected from the group consisting of polyvinylidene chloride (PVDC), polyurethane (PU), polychloroprene, polyisoprene, and polybutadiene.

Preferably, the polymer may be polyacrylonitrile (PAN).

In one embodiment, the solvent is at least selected from the group consisting of N, N-dimethylformamide, phenol, acetone, toluene, tetrahydrofuran, distilled water, ethanol, methanol, propanol, butanol, isopropanol, and alcohol-based substances. It may include any one.

Preferably, the solvent may be N,N-dimethylformamide.

In one embodiment, the step of preparing a metal-doped nanofiber template (220) is to prepare a metal-doped nanofiber template by immersing the nanofiber template in a dispersion solution in which a doped metal and a metal oxide precursor are dissolved. to be.

In one embodiment, the step of preparing a metal-doped nanofiber template by immersing the nanofiber template in a dispersion solution in which the doped metal and metal oxide precursor are dissolved, wherein the doped metal and metal oxide precursor are dissolved in distilled water. After immersing the nanofiber template in the prepared dispersion solution for 30 minutes to 5 hours, the metal-doped nanofiber template may be filtered using a mesh net.

In one embodiment, the doped metal is silver (Ag), copper (Cu), nickel (Ni), aluminum (Al), iron (Fe), cobalt (Co), tantalum (Ta), tungsten (W) , Molybdenum (Mo) Niobium (Nb), Antimony (Sb), Tin (Sn), Hafnium (Hf), Silicon (Si), Palladium (Pd), Titanium (Ti), Zirconium (Zr), Calcium (Ca), At least one selected from the group consisting of germanium (Ge), gallium (Ga), indium (In), ruthenium (Ru), tellurium (Te), chromium (Cr), vanadium (V) and titanium (Ti) may include

In one embodiment, the metal oxide precursor is acetate, chloride, acetylacetonate, nitrate, methoxide, ethoxide, butoxide, isopropoxide, sulfate, oxytriisopropoxide, (ethyl or It may include a metal salt having at least one form selected from the group consisting of cetylethyl)hexanoate, butanoate, ethylamide, and amide.

In one embodiment, drying and heat treatment step 230 is a step of drying and heat treatment of the metal-doped nanofiber template.

In one embodiment, the step of drying and heat-treating the metal-doped nanofiber template, after drying the metal-doped nanofiber template in a temperature range of 40 ℃ to 90 ℃ for 5 minutes to 2 hours, 500 It may be heat treatment for 30 minutes to 10 hours at a temperature range of ℃ to 800 ℃.

A zinc-secondary battery according to another embodiment of the present invention includes a positive electrode for a zinc-secondary battery according to an embodiment of the present invention; zinc-anode for secondary batteries; a separator interposed between the zinc-secondary battery positive electrode and the zinc-secondary battery negative electrode; and an electrolyte.

In one embodiment, the positive electrode for a zinc-secondary battery may include the positive electrode for a zinc-secondary battery according to an embodiment of the present invention.

In one embodiment, the negative electrode material for the zinc-secondary battery may be obtained by mixing a negative electrode active material, a conductive material, and a binder.

In one embodiment, the conductive material may include at least one selected from the group consisting of natural graphite, artificial graphite, ketjen black, cokes, carbon black, carbon nanotubes, and graphene.

In one embodiment, the binder is a thermoplastic resin, for example, a fluororesin such as polyvinylidene fluoride, polytetrafluoroethylene, tetrafluoroethylene, vinylidene fluoride copolymer, hexafluoride propylene; It may include at least one selected from the group consisting of; and polyolefin resins such as polyethylene and polypropylene.

In one embodiment, the negative electrode material may be coated on the negative electrode current collector to form a negative electrode. The anode current collector may be a conductor such as Al, Ni, or stainless. Applying the negative electrode material on the negative electrode current collector may use pressure molding or a method of making a paste using an organic solvent, etc., then applying the paste on the current collector and press to fix it.

In one embodiment, the organic solvent is an amine-based solvent such as N,N-dimethylaminopropylamine or diethyltriamine; ethers such as ethylene oxide and tetrahydrofuran; ketone systems such as methyl ethyl ketone; esters such as methyl acetate; It may contain an aprotic polar solvent such as dimethylacetamide or N-methyl-2-pyrrolidone.

In one embodiment, applying the paste on the positive electrode current collector may be performed using, for example, a gravure coating method, a slit die coating method, a knife coating method, or a spray coating method.

In one embodiment, a separator may be disposed between the zinc-secondary battery positive electrode and the zinc-secondary battery negative electrode. Such a separator may include at least one selected from the group consisting of a porous film made of a material such as a polyolefin resin such as polyethylene or polypropylene, a fluororesin, or a nitrogen-containing aromatic polymer, a nonwoven fabric, or a woven fabric.

In one embodiment, the thickness of the separator is preferably thinner as long as mechanical strength is maintained in that the volumetric energy density of the battery increases and the internal resistance decreases.

In one embodiment, the thickness of the separator may be, for example, about 5 μm to about 200 μm, and preferably, about 5 μm to about 40 μm.

Hereinafter, the present invention will be described in more detail by examples and comparative examples.

However, the following examples are only for illustrating the present invention, and the content of the present invention is not limited to the following examples.

Reasonable utilization of renewable energy sources has become a global issue due to fossil fuel prices and increased energy demand, and since zinc sources are abundant, rechargeable aqueous zinc ion batteries (ZIBs) are considered as large-scale energy storage devices, and ZIBs are reliable and reliable. safety, environmental friendliness and high specific capacity. Nevertheless, the limited electroactive sites and low electrical conductivity of vanadium oxide (V ₂ O ₅ )-based anodes for ZIBs inevitably destabilize the energy storage reaction, impeding zinc ion diffusion and electron transfer.

An example of the present invention reports iron (Fe)-doped V ₂ O ₅ having a nanorod structure using an electrospun polyacrylonitrile fiber template to lower the insertion energy and diffusion barrier of zinc ions. They exhibited a high energy density of 540 W h kg ⁻¹ at a power density of 600 W kg ⁻¹ and excellent specific capacity retention of 85% even after up to 160 cycles. The Fe-doping effect of the V ₂ O ₅ matrix with the nanorod architecture promotes the overall energy storage performance by providing rich contact with the electrolyte, increasing the electrical conductivity, and shortening the ion diffusion distance during the electrochemical process. Embodiments of the present invention provide strategies for designing next-generation high-performance energy storage devices.

Vanadium is an abundantly present element in the earth's crust, and its low cost, multiple oxidation states, and excellent stability stimulate the research of vanadium-based compounds as anode materials for ZIBs. Improvements in the performance of vanadium pentoxide (V ₂ O ₅ ) for ZIBs have been developed recently, but the main factors that improve them when putting them to practical use are their low energy density and low rate performance. This is because the limited electroactive sites and low electrical conductivity of V ₂ O ₅ -based anodes for ZIBs are not high enough.

A unique effort to achieve many electroactive sites and enhanced electrical conductivity of V ₂ O ₅ -based anodes can employ a doping technique that builds the crystal structure and electronic properties of ZIBs. This doping technique is one of the most efficient solutions to improve electrochemical performance. Due to the structural openness or flexibility of V ₂ O ₅ , the geometry can be efficiently changed by doping metal ions into the matrix by adjusting the layer spacing and rearrangement to positively affect the structure, electrical conductivity and ion diffusion. Therefore, in order to improve the performance of ZIBs, a synthetic approach to the doping technology of V ₂ O ₅ -based anodes, elemental selectivity, and even the discovery of electrochemical mechanisms must be realized.

3 is a schematic diagram showing a selective growth process of Fe-doped V ₂ O ₅ having a rod-like structure as an advanced anode for a zinc ion battery (ZIB) according to an embodiment of the present invention ((a) an electrospun fiber template; ( b) Precursor soaked template (c) Rod-like structured Fe-doped V ₂ O ₅ (d) Packed aqueous ZIB).

As shown in FIG. 3 in an embodiment of the present invention, iron (Fe)-doped V ₂ O ₅ nanorods uniquely designed as high-grade anodes for ZIBs were prepared as polyacrylonitrile (PAN) fiber templates as a corresponding sol solution. was produced through electrospinning, and the template was immersed in a solvent in which iron and vanadium precursors were dissolved, and then taken out. After that, drying and annealing (600 ° C.) were performed to complete the process. First, the doping effect can provide an increased number of electroactive sites and improved electrical conductivity in the V ₂ O ₅ matrix, which provides contrast capacity and excellent rate performance for ZIB. In addition, the unique nanorod structure exhibits improved ion diffusion kinetics, providing long cycle life with remarkable cycling stability. These surprising electrochemical results and insight into the Zn-ion storage mechanism can be realized as a next-generation sustainable energy storage system.

Experiment

Fe-doped V ₂ O ₅ nanorods were successfully synthesized using the electrospun PAN fiber template method. First, PAN (Mw = 150,000 g mol ^-1 ) was dissolved in N,N-dimethylformamide (DMF) to prepare a polymetric solution. During the electrospinning process, the applied voltage and feed rate were maintained at ~10 kV and 0.4 L h ^-1 , respectively, and the distance between the needle tip and aluminum foil as a current collector was positioned at 10 cm to form a PAN fiber template. A sol solution for impregnation with a template was prepared by dissolving 1.2 g of vanadium(IV) oxide sulfate hydrate, iron(III) chloride hexahydrate in 40 ml deionized (DI) water as a doping agent. To investigate the Fe-doping effect on the produced V ₂ O ₅ nanorods, the atomic percentages of Fe to V were adjusted to 0.0 at%, 1 at%, 5 at%, and 10 at%, respectively, where bare V ₂ O ₅ , 1Fe-V ₂ O ₅ , 5Fe-V ₂ O ₅ and 10Fe-V ₂ O ₅ . Then, the PAN fiber template was immersed in the sol solution for 3 h and then filtered using a mesh net. After drying at 80 °C, the sol-treated PAN fiber template was annealed at 600 °C for 8 hours in an air atmosphere to form four types of Fe-doped V ₂ O ₅ nanorods.

measurement

Structural and morphological characteristics of the prepared samples were evaluated by field emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscope (HR-TEM, KBSI Gwangju Center), respectively. investigated through The distribution of the elements was confirmed by analyzing the high-resolution transmission electron microscope (EDS) mapping. The crystal structure and chemical bonding state were determined by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS, AXIS ultra-delay line detector equipped with an Al K _α Xray source, respectively). KBSI Daedeok headquarters) was used for analysis. The electrical and optical behaviors of the fabricated electrodes were measured using a Hall effect measurement system and ultraviolet-visible spectroscopy (Perkim-Elmer, Lambda-35), respectively.

The electrochemical performance is a coin-constructed V ₂ O ₅ -based electrode as the anode, zinc metal as the cathode, glass fiber paper as the separator and 3M zinc trifluoromethanesulfonate (Zn(CF ₃ SO ₃ ) ₂ ) as the electrolyte. The electrode slurry for the positive electrode was prepared by mixing polyvinylidene difluoride (PVDF) and Ketjen Black in N-Methyl 2-pyrrolidine. It was prepared by coating the current collector after mixing at a ratio of 7: 2: 1. The resulting electrode was dried at 100 ° C. To investigate the electrochemical behavior, a voltage of 5 mV was applied in the frequency range of 10 ⁵ to 10 ^-2 Hz. Electrochemical impedance spectroscopy (EIS) was performed by applying an AC signal, and cyclic voltammetry (CV) was performed using a potentiostat/galvanostat at a scan rate of 1 mV s ^-1 . Before the charge-discharge test, the activation process was performed by CV at a scan rate of 1 mV s ⁻¹ The high-speed performance was 0.5 mA g ⁻¹ , 0.7 mA g ⁻¹ , 1.0 mA g ⁻¹ , 1.3 mA g ^-1 , 1.5 mA g ^-1 , 1.7 mA g ^-1 and 2.0 mA g ^-1 at different current densities and at voltages ranging from 0.4 V to 1.6 V. The cycling stability was 1.3 mA g ^-1 observed up to 160 cycles at current densities of

Results and discussion

4 is a view showing morphological characteristics of bare V ₂ O ₅ , 1Fe-V ₂ O ₅ , 5Fe-V ₂ O ₅ and 10Fe-V ₂ O ₅ according to an embodiment of the present invention. FE-SEM images of (a) bare V ₂ O ₅ , (b) 1Fe-V ₂ O ₅ , (c) 5Fe-V ₂ O ₅ , (d) 10Fe-V ₂ O ₅ , bare V ₂ O ₅ and Structure and composition of 5Fe-V ₂ O ₅ : (e, g), low-magnification HR-TEM images of bare V ₂ O ₅ and 5Fe-V ₂ O ₅ : (f, h) and high-magnification HR-TEM images (g, h); (i) Elemental distribution of 5Fe-V ₂ O ₅ .

4(a) to (d) are SEM images of all samples. Referring to Figure 4 (a) to Figure 4 (d), the change in the shape of the product was clearly shown according to the atomic ratio of the Fe source. As expected, utilization of the PAN fiber template formed nanorod-like structures due to continuous directional nuclei growth along the c-axis. It is noted that the larger the amount of Fe source, the smaller the diameter of the product (bare V ₂ O ₅ : 565.4-1,122.9 nm, 1Fe-V ₂ O ₅ : 468.3-755.9 nm, 5Fe-V ₂ O ₅ : 235.8-561.1 nm). This can lead to nanosizing of the one-dimensional (1D) structure as a result of slow ion diffusion during nucleation and subsequent growth by the presence of Fe ions that act as Fe doping sources for V ₂ O ₅ .

In the case of 10Fe-V ₂ O ₅ , the nanosizing effect is mitigated as the diameter (586.8-1,383.0 nm) similar to that of bare V ₂ O ₅ despite the use of a larger amount of Fe source. This may be due to the unexpected formation of Fe-related compounds to limit Fe doping to the V ₂ O ₅ phase. TEM results were compared between bare V ₂ O ₅ and 5Fe-V ₂ O ₅ to clearly show the correlation between the nanosizing effect and Fe doping. As a result of confirming that the diameter of 5Fe-V ₂ O ₅ (Fig. 4 (g)) is smaller than that of bare V ₂ O ₅ (Fig. 4 (e)), a notable factor is 5Fe compared to bare V ₂ O ₅ -V ₂ O ₅ is the extended (110) interplanar spacing. This may be a result of Fe ³⁺ comprising as a doped matrix an ionic radius (0.64 Å) higher than that of V ⁵⁺ (0.54 Å) in V ₂ O ₅ . This actually shows a uniform distribution of Fe elements with V and O in the nanorod-shaped products in elemental mapping of 5F-V ₂ O ₅ . Therefore, the optimized nanorod architecture of Fe-doped V ₂ O ₅ can benefit Zn ion dynamics during electrochemical reactions due to shortened diffusion distance due to efficient coupling between them.

5 shows XRD patterns of bare V ₂ O ₅ , 1Fe-V ₂ O ₅ , 5Fe-V ₂ O ₅ and 10Fe-V ₂ O ₅ according to an embodiment of the present invention.

Referring to FIG. 5, the characteristic diffraction peaks of bare V ₂ O ₅ emitted at 15.39 °, 20.29 °, 26.16 ° and 31.03 ° are, respectively, without a secondary phase, orthorhombic V ₂ O ₅ phase (JCPDS card No. 77-2418) coincide with the (020), (001), (110) and (031) planes.

6 shows TEM results of bare V ₂ O ₅ , 1Fe-V ₂ O ₅ , 5Fe-V ₂ O ₅ and 10Fe-V ₂ O ₅ according to an embodiment of the present invention.

As confirmed in FIG. 6 , the peak shift to a lower angle that can ensure successful Fe doping into V ₂ O ₅ due to the distinct ionic radius difference between Fe ³⁺ and V ⁵⁺ is bare V ₂ O ₅ and 5Fe-V ₂ O ₅ .

7 shows summarized lattice parameter results of bare V ₂ O ₅ , 1Fe-V ₂ O ₅ , 5Fe-V ₂ O ₅ and 10Fe-V ₂ O ₅ according to an embodiment of the present invention.

Referring to FIG. 7 , the accelerated degree of Fe doping causes a gradual expansion of all lattice parameters for the V ₂ O ₅ matrix. It can be inferred that these changes form FeO ₆ octahedra in the V ₂ O ₅ structure, where Fe doping is likely to be performed between the VO ₅ slabs and provide additional active sites for Zn ion storage. can In addition, the extended lattice parameter can affect the lattice strain (ε) associated with the structural distortion obtained by the William-Hall method, as shown in [Equation 1]:

[Equation 1]

where β is the full width at half maximum of the diffraction peak, θ is Bragg's angle, k is the shape factor, λ is the X-ray wavelength, and D is the particle size.

8 shows a Williamson-Hall plot of bare V ₂ O ₅ , 1Fe-V ₂ O ₅ , 5Fe-V ₂ O ₅ and 10Fe-V ₂ O ₅ according to an embodiment of the present invention.

Referring to FIG. 8, ε determined by the slope of the linear fit in the relationship of (β cosθ) versus (4 sinθ) is different (bare V ₂ O ₅ : 0.378%, 1Fe-V ₂ O ₅ : 0.395%, and Compared to 10Fe-V ₂ O ₅ : 0.389 %), it shows a lower value (0.408%) in 5Fe-V ₂ O ₅ , which indicates that the improved Fe doping in V ₂ O ₅ is due to the presence of defects in the V ₂ O ₅ matrix. This can be the main evidence that the lattice distance of ZIB can be extended, thus providing an improved electroactive site that can be expected to improve the specific specific capacity of ZIB.

The chemical bonding state of all samples is analyzed by XPS analysis to analyze the F-doping effect in detail.

9 to 12 show XPS spectra of bare V ₂ O ₅ , 1Fe-V ₂ O ₅ , 5Fe-V ₂ O ₅ and 10Fe-V ₂ O ₅ according to embodiments of the present invention.

FIG. 9 is V 2p _3/2 , FIG. 10 is bare V ₂ O ₅ , 1Fe- V ₂ O ₅ , 5Fe- V ₂ O ₅ and 10Fe- V ₂ O ₅ O 1 s, respectively, and FIG. 11 is an electrical conductivity diagram. 12 is the XPS spectrum representing the photon energy showing ( ahν ) ² versus the optical band gap.

The V 2 p _3/2 XPS spectra of all samples (FIG. 9) are ~ 516.21 eV, corresponding to the binding energies of V ⁴⁺ , V ⁵⁺ and satellites, respectively, for V ₂ O ₅ [XRD1]; It has three characteristic peaks at ~ 517.36 eV and ~ 518.31 eV. Increasing the atomic ratio of the Fe source to 5 at% increases the V ⁴⁺ /V ⁵⁺ area ratio. This is an efficient channel for intercalation/extraction of Zn ions by creating oxygen vacancies ( V _o ) due to the occupancy of the V ⁵⁺ site by Fe ³⁺ , resulting in an extra dopant energy level that makes the electrode It can be seen as improving the electrical conductivity of (FIG. 12) [XPS1].

VO (~530.16 eV), -OH (~531.00 eV) and -H ₂ O peaks (~532.15 eV) common among the samples are only 1Fe-V ₂ O ₅ and _5Fe -VO in the O 1s XPS spectrum. Only ₅ has an additional characteristic peak (FIG. 10). This is related to the presence of oxygen vacancies formed by the Fe-doping effect in V ₂ O ₅ , and 1Fe-V ₂ O ₅ (0.28 for V _o /VO) to 5Fe-V ₂ O ₅ (0.33 for V _o /VO). This may be a factor in increasing electrical conductivity by providing additional carriers for electron movement. The Fe-doping level increases with an increase in the used atomic ratio of the Fe source. This effect also causes a change in the optical bandgap ( E _g ) between the samples calculated by the relation of absorption coefficient ( α ) versus incident photon energy [Equation 2]. do.

[Equation 2]

( αhv ) ² = D ( hv - E _g ) ⁿ (2)

where h is Plank's constant, v is the photon frequency, and D is a constant. ( αhv ) By extrapolation of the linear region between ² and hv , E _g records a narrowed trend in bare V ₂ O ₅ and 5Fe-V ₂ O ₅ (see FIG. 11), and V ₂ O ₅ valence band It serves as another evidence _of Vo formed as a result of the Fe-doping effect that causes the excitation of . However, in the case of 10Fe-V ₂ O ₅ , E _g broadens compared to 5Fe-V ₂ O ₅ and a clear absorption is observed at 430.0-540.0 nm, indicating that the formation of Fe-O related phases is due to excessive use of the Fe source. It can be shown that it is affected by impurities with use and consequently the electrical conductivity is lowered. Therefore, these definitions can be expected to successfully demonstrate the optimized effect of Fe doping on V ₂ O ₅ , greatly activating the performance of ZIBs such as specific specific capacity, retention and rate performance.

The electrochemical kinetic properties of bare V ₂ O ₅ , 1Fe-V ₂ O ₅ , 5Fe-V ₂ O ₅ and 10Fe-V ₂ O ₅ are evaluated by EIS analysis.

13 to 16 are views showing electrochemical kinetic characteristics of bare V ₂ O ₅ , 1Fe-V ₂ O ₅ , 5Fe-V ₂ O ₅ and 10Fe-V ₂ O ₅ according to embodiments of the present invention.

Fig. 13 is a Nyquist plot, Fig. 14 is the relationship between Z _real and ω ^-1/2 , Fig. 15 is a zinc ion diffusion coefficient, and Fig. 16 is a cyclic voltammetry at a scan rate of 1 mV s -1 in the potential range of 0.4 to 1.6 V. is the law (CV) curve.

The Nyquist plot of FIG. 13 shows charge-transfer resistance ( R _ct ) and ion diffusion behavior (Warburg impedance) by a semicircle in a high-frequency region and a slope in a low-frequency region, respectively. The smaller semicircle for 5Fe-V ₂ O ₅ demonstrates a superior charge transfer process compared to other semicircles, as the electrical conductivity of the electrode induced by V _o is enhanced due to the occupancy of the V ⁵⁺ site by Fe ³⁺ . . Besides, 5Fe-V ₂ O ₅ shows the steepest slope (lowest Warburg impedance), demonstrating excellent Zn ion diffusion ability, indicating that the optimized nanorod architecture provides nanosizing effect with short diffusion distance. In addition, the Warburg impedance coefficient ( σ _w ) and the Zn-ion diffusion coefficient of (D) were calculated using [Equation 3] and [Equation 4]:

[Equation 3]

[Equation 4]

where R _e represents the type of total electrode resistance, D is the diffusion coefficient of Zn-ions, R is the gas constant, T is the temperature, A is the electrode area, n is the number of electrons per molecule, F is the Faraday constant, and C is the molar concentration of Zn ions. The σ _w values of bare V ₂ O ₅ , 1Fe-V ₂ O ₅ , 5Fe-V ₂ O ₅ and 10Fe-V ₂ O ₅ in the relationship between Z _real and ω ^-1/2 shown in FIG. 5b are 43.3, respectively. Ω cm ² s ^-1/2 , 38.1 Ω cm ² s ^-1/2 , 23.1 Ω cm ² s ^-1/2 and 39.9 Ω cm ² s ^-1/2 The diffusion coefficients of Zn-ions for the fabricated battery were 0.18 cm ² s ^-1 , 0.23 cm ² s ^-1 , 0.64 cm ² s ^-1 and 0.21 Х 10-12 cm ² s ^-1 , respectively, as shown in Fig. 5c. turned out to be

CV curves of all cells are presented in FIG. 16 . Two pairs of reduction/oxidation peaks can be clearly observed at 0.55/0.71 V and 0.97/1.20 V, which are caused by Zn ²⁺ insertion/desorption. In particular, 5Fe-V ₂ O ₅ shows the largest CV region due to the extended lattice distance of V ₂ O ₅ caused by the Fe-doping effect, indicating an increase in the number of electroactive sites during cycling. These results suggest that the Zn-ion diffusion performance, electrical conductivity and electroactive site of 5Fe-V ₂ O ₅ are improved by the optimized Fe doping effect in the V ₂ O ₅ nanorod structure, potentially in terms of specific capacity, high rate and long-term cycling. indicates that the electrochemical performance is potentially improved.

To investigate the zinc storage properties of bare V ₂ O ₅ , 1Fe-V ₂ O ₅ , 5Fe-V ₂ O ₅ and 10Fe-V ₂ O ₅ as anodes, zinc foil and 3M Zn (CF ₃ SO ₃ ) ₂ were prepared, respectively. , used as cathode and electrolyte to fabricate coin-type cells in ambient air.

17 is a galvanic charge-discharge curve of bare V ₂ O ₅ , 1Fe-V ₂ O ₅ , 5Fe-V ₂ O ₅ and 10Fe-V ₂ O ₅ at a current density of 0.5 A g ^-1 according to an embodiment of the present invention. .

The constant current charge-discharge curves of all ZIBs at a current density of 0.5 A g ^-1 and a voltage in the range of 0.4 to 1.6 V are shown in FIG. 17 . An obvious plateau can be identified during the charging and discharging process consistent with the CV results. Also, similar discharge/charge times were obtained for the galvanostatic charge/discharge curves, suggesting high Coulombic efficiencies associated with highly reversible zinc ion insertion/desorption processes.

18 is a galvanic charge-discharge curve of two devices composed of 5Fe-V ₂ O ₅ connected in series according to an embodiment of the present invention.

Referring to FIG. 18, in order to confirm applicability to electronic devices, two ZIBs composed of 5Fe-V ₂ O ₅ anodes were connected in series. The charge/discharge voltage range obviously doubles when the two devices are connected in series. We also demonstrated that the connected ZIB can successfully power a yellow Light Emitting Diode (LED).

19 shows 0.4-1.6 V and 0.5-2.0 A g ^-1 of bare V ₂ O ₅ , 1Fe-V ₂ O ₅ , 5Fe-V ₂ O ₅ and 10Fe-V ₂ O ₅ , respectively, according to an embodiment of the present invention. It is a diagram showing the comparative rate performance at the potential and current density of

Specific capacitance values of ZIB were calculated in the current density range of 0.5 A g ^-1 to 2.0 A g ^-1 , and the results are shown in FIG. 19 . 5Fe-V ₂ O ₅ can reach the highest specific capacity of 422 mAh g ^-1 at a current density of 0.5 A g ^-1 . This is due to the effect of the extended lattice distance on the Fe-doped V ₂ O ₅ matrix to provide increased electroactive sites.

In addition, as the current density increased from 0.5 A g ^-1 to 2.0 A g ^-1 , the specific capacity of 5Fe-V ₂ O ₅ decreased to 256 mAh g ^-1 , but it maintained the best rate performance among various ZIBs. This result can be attributed to the following reasons: (i) enhanced Zn-ion diffusion ability obtained from the nanosizing effect of the nanorod structure with short diffusion distance and (ii) Fe ³⁺ , which exhibits enhanced electron transfer at high-speed current density. Increased electrical conductivity due to supply of V _o formed by occupancy of V ⁵⁺ sites by V .

20 is a diagram showing the comparative performance of 5Fe-V ₂ O ₅ including the previously reported performance of ZIB.

As shown in FIG. 20 , the excellent rate performance of 5Fe-V ₂ O ₅ was demonstrated compared to that of a previously reported ZIB composed of a V ₂ O ₅ anode.

21 is a current density of 1.3 mA g ^-1 for up to 160 cycles of bare V ₂ O ₅ , 1Fe-V ₂ O ₅ , 5Fe-V ₂ O ₅ and 10Fe-V ₂ O ₅ according to an embodiment of the present invention. This is a diagram showing the cycling stability of the fabricated ZIB.

Long-term cycling test results at a current density of 1.3 A g ⁻¹ for up to 160 cycles are shown in FIG. Here, specific capacity retention of bare V ₂ O ₅ , 1Fe-V ₂ O ₅ , 5Fe-V ₂ O ₅ and 10Fe-V ₂ O ₅ are 44%, 67%, 85% and 62%, respectively.

22 is EIS of (b) bare V ₂ O ₅ , (c) 1Fe-V ₂ O ₅ , (d) 5Fe-V ₂ O ₅ and (e) 10Fe-V ₂ O ₅ according to an embodiment of the present invention. it's a spectrum

In addition, EIS measurements performed after a long cycling test verified that 5Fe-V ₂ O ₅ (FIG. 22 (c)) maintained initial ion diffusion performance even after cycling. On the other hand, the ion diffusion ability of bare V ₂ O ₅ (FIG. 22 (a)), 1Fe-V ₂ O ₅ (FIG. 22 (b)), and 10Fe-V ₂ O ₅ (FIG. 22 (d)) was tested by cycling. It was confirmed that there was a significant decrease after This result demonstrates improved Zn-ion diffusion kinetics by nanosizing nanorods with efficient electrolyte-ion contact and provides excellent long-term cycling stability. Therefore, Fe doping into the V ₂ O ₅ matrix to increase the overall energy storage performance of ZIBs is very advantageous for designing advanced structures for zinc ion insertion/desorption processes.

23 is a diagram showing a Ragone plot comparing energy and power densities of 5Fe-V ₂ O ₅ according to an embodiment of the present invention with those of previously reported rechargeable batteries.

The energy and power densities of 5Fe-V ₂ O ₅ are compared with those of other energy storage devices reported by the Ragone plot of FIG. 23 . It shows a maximum energy density of 540 W h kg ^-1 at ^{a power density of 600 W kg -1 and a maximum energy density of 392 W h kg -1 at a} power density of 2,400 W kg -1 . This is a much higher figure than previously reported lithium-ion, sodium-ion, aluminum-ion, magnesium-ion and potassium-ion batteries.

24 is a schematic representation of the advantages of 5Fe—V ₂ O ₅ including a combination of increased number of electroactive sites, improved electrical conductivity, and improved ionic diffusion kinetics according to an embodiment of the present invention.

As schematically shown in Figure 24, the above result can be largely attributed to the following three reasons:

(i) The increased number of electroactive sites is obtained by extending the lattice distance of the Fe-doped V ₂ O ₅ matrix.

(ii) Supply of V _O by occupation of V ⁵⁺ sites by Fe ³⁺ may provide enhanced electrical conductivity.

(iii) Improved ion diffusion kinetics is achieved by the novel structure of the nanorod structure with nanosizing effect.

An embodiment of the present invention reports Fe-doped V ₂ O ₅ nanorods through the electrospun PAN fiber template method to improve the overall ion and electron transport performance of ZIBs. Batteries fabricated using 5 at% of the atomic percentile of Fe in V in the V ₂ O ₅ matrix had 422 mAh g ^-1 and 256 mAh g -1 at current densities of 0.5 A g ^-1 and 2.0 A g ^-1 , respectively ^{. 1} has been shown to achieve a high specific capacity. The excellent long-term cycling stability of 85% after 160 cycles was maintained with very stable ion diffusion capacity even after cycling tests. The reasons for the improvement in energy storage performance are as follows:

(i) an increase in the number of electroactive sites provided by the extended lattice distance of the Fe-doped V ₂ O ₅ matrix leading to a high specific capacity (ii) the number of V ⁵⁺ sites by Fe ³⁺ to create oxygen vacancies. Enhanced electrical conductivity provided by occupancy improves electron transport, resulting in improved rate performance, and (iii) improved ionic diffusion kinetics lead to superior cycling stability, resulting in a unique nanosizing effect of the Fe-doped V ₂ O ₅ nanorod architecture. is achieved by

Thus, examples of the present invention show that Fe-doped V ₂ O ₅ nanorods can provide promising strategies and insights for the design of next-generation energy storage devices.

As described above, although the embodiments have been described with limited drawings, those skilled in the art can apply various technical modifications and variations based on the above. For example, the described techniques may be performed in an order different from the method described, and/or components of the described system, structure, device, circuit, etc. may be combined or combined in a different form than the method described, or other components may be used. Or even if it is replaced or substituted by equivalents, appropriate results can be achieved.

Therefore, other implementations, other embodiments, and equivalents of the claims are within the scope of the following claims.

100: zinc - anode for secondary battery

Claims (11)

metal-doped metal oxides;
including,
The metal oxide includes at least one shape selected from the group consisting of nanorods, nanotubes, nanoneedles, and nanowires,
The metal is iron (Fe),
The metal oxide is V ₂ O ₅ ,
Which contains oxygen vacancies due to the occupation of the V ⁵⁺ site by Fe ³⁺ ,
Zinc-anode for secondary batteries.
delete According to claim 1,
The metal is 0.5 at% to 15 at% of the metal oxide,
Zinc-anode for secondary batteries.
delete According to claim 1,
The metal oxide has a diameter of 1 nm to 50 nm, a length of 100 nm to 800 nm, and an aspect ratio of 1: 100 to 50: 800,
Zinc-anode for secondary batteries.
preparing a nanofiber template by electrospinning a polymer;
Preparing a metal-doped nanofiber template by immersing the nanofiber template in a dispersion solution in which a doped metal and a metal oxide precursor are dissolved; and
drying and heat-treating the metal-doped nanofiber template;
including,
The method of manufacturing a positive electrode for a zinc-secondary battery of claim 1.
According to claim 6,
The step of preparing a nanofiber template by electrospinning the polymer,
A polymer solution in which the polymer is dissolved in a solvent is supplied at an applied voltage of 1 kV to 20 kV and a supply rate of 0.01 L h ⁻¹ to 10 L h ⁻¹ , and the distance between the needle tip and the current collector is 5 cm to 15 cm. Positioning and electrospinning to prepare a nanofiber template,
The polymer is polyvinylpyrrolidone (PVP), polyvinylidene fluoride (PVDF), polyvinyl alcohol (PVA), polyvinyl acetate (PVAc), polystyrene PS), polymethyl methacrylate (PMMA), poly(n-butyl acrylate) (PBA), polyacrylonitrile (PAN), polyaniline; PANi), polyacrylic acid (PAA), polyester-amides (PEA), polyethylene (PE), polyvinyl chloride (PVC), polyvinylidene chloride (PVDC) ), at least one selected from the group consisting of polyurethane (PU), polychloroprene, polyisoprene and polybutadiene,
The solvent includes at least one selected from the group consisting of N, N-dimethylformamide, phenol, acetone, toluene, tetrahydrofuran, distilled water, ethanol, methanol, propanol, butanol, isopropanol, and alcohol-based substances. sign,
Zinc-method for manufacturing a cathode for a secondary battery.
According to claim 6,
Preparing a metal-doped nanofiber template by immersing the nanofiber template in a dispersion solution in which the doped metal and metal oxide precursor are dissolved,
After immersing the nanofiber template in a dispersion solution in which the doped metal and metal oxide precursor are dissolved in distilled water for 30 minutes to 5 hours, the metal-doped nanofiber template is filtered using a mesh net,
Method for manufacturing a cathode for a zinc-secondary battery.
According to claim 6,
The doping metal is silver (Ag), copper (Cu), nickel (Ni), aluminum (Al), iron (Fe), cobalt (Co), tantalum (Ta), tungsten (W), molybdenum (Mo) niobium (Nb), Antimony (Sb), Tin (Sn), Hafnium (Hf), Silicon (Si), Palladium (Pd), Titanium (Ti), Zirconium (Zr), Calcium (Ca), Germanium (Ge), Gallium Contains at least one selected from the group consisting of (Ga), indium (In), ruthenium (Ru), tellurium (Te), chromium (Cr), vanadium (V) and titanium (Ti),
The metal oxide precursor is acetate, chloride, acetylacetonate, nitrate, methoxide, ethoxide, butoxide, isopropoxide, sulfate, oxytriisopropoxide, (ethyl or cetylethyl) hexanoate , Butanoate, comprising a metal salt having at least one form selected from the group consisting of ethylamide and amide,
Method for manufacturing a cathode for a zinc-secondary battery.
According to claim 6,
Drying and heat-treating the metal-doped nanofiber template,
After drying the metal-doped nanofiber template at a temperature range of 40 ° C to 90 ° C for 5 minutes to 2 hours,
Heat treatment for 30 minutes to 10 hours in the temperature range of 500 ℃ to 800 ℃,
Method for manufacturing a cathode for a zinc-secondary battery.
The zinc-positive electrode for a secondary battery according to claim 1;
zinc-anode for secondary batteries;
a separator interposed between the zinc-secondary battery positive electrode and the zinc-secondary battery negative electrode; and
electrolytes;
including,
Zinc-secondary battery.

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