KR20160022103A - Electrode active material for magnesium battery, electrode and magnesium battery comprising the same, and method of preparing the electrode active material for magnesium battery - Google Patents

Abstract

Provided are: an electrode active material for a magnesium battery comprising hydrated manganese-based composite oxide of a laminated nanosheet structure represented by chemical formula 1; an electrode comprising the same and a magnesium battery; and a producing method of the electrode active material for the magnesium battery. The electrode active material for the magnesium battery has improved capacity, improved charge and discharge voltage and improved lifespan properties. In the chemical formula 1, x, y, z, M, and MI are the same as defined in the specification.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode active material for a magnesium battery, an electrode and a magnesium battery including the electrode active material, and an electrode active material for the magnesium battery,

An electrode including the electrode active material, a magnesium battery, and a method for producing the electrode active material for the magnesium battery.

In recent years, there has been a growing interest in materials for electric storage batteries.

The magnesium battery has been actively studied because it is environmentally friendly, has excellent price competitiveness, and has a high energy storage characteristic as compared with conventional lithium batteries, lead batteries, nickel-cadmium batteries, nickel-hydrogen batteries and nickel-zinc batteries.

Unlike lithium ions, magnesium ions generated during magnesium charging and discharging have high electric charge characteristics with two electric charges. However, when the magnesium ion is inserted into an electrode active material, for example, a positive electrode active material, strong electrostatic interactions with the elements constituting the positive electrode active material, for example, anions, may occur. As a result, the diffusion rate of magnesium ions is lowered and the actual capacity is lowered, and the charge / discharge voltage and lifetime characteristics may be deteriorated.

Accordingly, there is a demand for an electrode active material for a magnesium battery having an improved capacity, an improved charge / discharge voltage, and an improved life span, an electrode and a magnesium battery including the same, and a method for manufacturing the electrode active material for the magnesium battery.

One aspect is to provide an electrode active material for a magnesium battery having an improved capacity, an improved charging / discharging voltage, and improved lifetime characteristics.

Another aspect is to provide an electrode comprising the electrode active material.

According to another aspect of the present invention, there is provided a magnesium battery including the electrode active material as a cathode active material.

Another aspect is to provide a method for producing an electrode active material for a magnesium battery having improved capacity, improved charging / discharging voltage, and improved lifetime characteristics.

According to one aspect,

There is provided an electrode active material for a magnesium battery comprising a hydrated manganese composite oxide having a layered nanosheet structure represented by the following Formula 1:

[Chemical Formula 1]

M _x Mn _{1 -y} (MI) _y O ₂ .zH ₂ O

In this formula,

0 &lt; x < 1, 0 < y &

M is at least one metal selected from Mg ^{2 +} , Ca ^{2 +} , Na ⁺ , K ⁺ , and Zn ^{2 +}

MI is a transition metal.

According to another aspect,

There is provided an electrode for a magnesium battery comprising the above-mentioned electrode active material.

According to another aspect,

A positive electrode comprising the above-described electrode active material as a positive electrode active material:

cathode; And

A magnesium battery including an electrolyte is provided.

According to another aspect,

Preparing a nanostructured spinel-type manganese oxide; And

There is provided a method for producing an electrode active material for a magnesium battery, which comprises the steps of: preparing a hydrated manganese composite oxide having a layered nanosheet structure by an electrochemical synthesis method of a spinel-type manganese oxide having a nanostructure;

According to an aspect of the present invention, there is provided a magnesium battery having improved capacity, improved discharge voltage, and improved lifespan characteristics by including a hydrated manganese composite oxide having a layered nanosheet structure represented by Formula 1 as an electrode active material.

FIG. 1 is a graph showing the results of the electrochemical synthesis of a cathode active material of a magnesium-burnetite hydrated manganese composite oxide having a layered nanosheet structure according to Example 1 in a spinel structure Mn ₃ O ₄ cathode active material according to Production Example 1 And the phase is changed according to the temperature.
2A is a graph showing the relationship between the Mn &lt; ₃ &gt; O &lt; ₄ &gt; It is a scanning electron microscope (SEM) image.
FIG. 2B is a graph showing the relationship between the weight ratio of the positive electrode active material of the magnesium-burnettite hydrated manganese composite oxide of the layered nanosheet structure according to Example 1 It is a scanning electron microscope (SEM) image.
FIG. 2C is a graph showing the relationship between the mass of the positive electrode active material of the magnesium-burnetite-type manganese-based complex oxide of the layered structure or the layered- It is a scanning electron microscope (SEM) image.
3 is an X-ray diffraction (XRD) spectrum of the positive electrode active material according to Example 1 and Comparative Example 2. FIG.
4 is a graph showing Nyquist plots and interfacial resistance for magnesium batteries containing 0 M, 0.5 M, 2 M, 5 M, and 10 M concentrations of water in the electrolyte.
5 is a graph showing charging / discharging voltages for specific capacities of the magnesium battery according to Example 2 and Comparative Example 4. FIG.
6 is a graph showing lifetime characteristics of a magnesium battery according to Example 2 and Comparative Example 4. FIG.
7 is a schematic diagram of a magnesium cell according to one embodiment.

Hereinafter, an electrode active material for a magnesium battery, an electrode and a magnesium battery including the electrode active material, and a method for producing the electrode active material for a magnesium battery according to an embodiment of the present invention will be described in detail. The present invention is not limited thereto, and the present invention is only defined by the scope of the following claims.

An electrode active material for a magnesium battery according to an aspect includes a hydrated manganese composite oxide having a layered nanosheet structure represented by the following Formula 1:

[Chemical Formula 1]

M _x Mn _{1 -y} (MI) _y O ₂ .zH ₂ O

In this formula,

0 <x? 1, 0? Y? 1, and 0 <z? 1,

M may be a ^{Mg 2 +, Ca 2 +,} Na +, K +, Zn ² and at least one metal selected from ^+,

MI can be a transition metal.

Magnesium cells generally include an anode, a cathode, and an electrolyte. The magnesium battery discharges electrons from the cathode to an external circuit at the time of discharging, and a reaction occurs in which the generated magnesium cations are stored in the anode through the electrolyte (oxidation reaction). The magnesium cations are discharged from the anode at the time of charging, Plating is carried out, and the electron-withdrawing reaction (reduction reaction) takes place.

At this time, a chalcogen compound such as Mg _{1 .03} Mn _{0 .97} SiO ₄ , MoS ₂ , or WSe ₂ or the like capable of reversible migration of the magnesium cation can be used as a general electrode active material of the magnesium battery, for example, However, when the chalcogen compound is used as a cathode active material, there is a problem that the working potential of the magnesium battery including the chalcogen compound is lower than ² V (vs. Mg / Mg ^{2 +} ).

The electrode active material for a magnesium battery according to an embodiment of the present invention may include a hydrated manganese composite oxide having a layered nanosheet structure represented by Formula 1 and may have a high reversible capacity and may include an electrode active material for a magnesium battery The working potential of the magnesium battery can be increased to ² V (vs. Mg / Mg ^{2 +} ) or more. As a result, the magnesium battery can have an improved capacity, an improved charge / discharge voltage, and improved lifetime characteristics.

The manganese-based composite oxide may be represented by, for example, the following formula (2)

(2)

Mg _u Mn _{1 -v} (MII) _v O ₂ .wH ₂ O

In this formula,

0 < u < 1, 0 &lt; v &lt;

MII may be at least one transition metal selected from Co, Ni, Fe, and Cu.

The hydrated manganese-based complex oxide may be a magnesium-burntite-type compound.

The hydrated manganese-based complex oxide may include a monoclinic crystal structure, a mesoporous crystal structure, a hexagonal crystal structure, or a combination thereof.

The hydrated manganese complex oxide may have a layered nanosheet structure with a thickness of 1 nm to 50 nm. For example, the hydrated manganese complex oxide may have a layered nanosheet structure with a thickness of 5 nm to 40 nm. For example, the hydrated manganese complex oxide may have a layered nanosheet structure having a thickness of 7 nm to 30 nm. The thickness of the layer of the hydrated manganese composite oxide can be confirmed from a scanning electron microscope (SEM) image described later.

And the layered nanosheet structure having a layer interval of 5 to 20 angstroms of the hydrated manganese composite oxide. For example, the manganese-based composite oxide may have a layered nanosheet structure with a layer interval of 5 to 15 Å. For example, the manganese-based composite oxide may have a layered nanosheet structure having a layer interval of 5 to 12 Å. The layer interval of the hydrated manganese composite oxide is measured by Bragg's 2? Angle and half width from the result of an X-ray diffraction (XRD) spectrum described later, and the Bragg angle and half width are measured from the half width to the surface interval (d ₀₀₁ ) Can be obtained from the Bragg equation using a 2? Angle.

Generally, in a magnesium battery, when magnesium cations generated during discharging are inserted into an electrode active material, for example, a positive electrode active material, strong electrostatic interactions with anions among the constituent elements of the positive electrode active material may occur . As a result, the ionic conductivity of the magnesium battery may be lowered, and the interface reaction resistance between the electrolyte and the electrode, for example, the anode may be increased to cause an overvoltage and a discharge capacity to be lowered.

The intermetallic compound-based composite oxide may contain crystal water between the layers. The crystal number can block the electrostatic interaction between the magnesium cation (Mg ^&lt; ^{2 + &} gt ^; ) and the anions constituting the positive electrode active material. The magnesium-containing compound can maximize the performance of the magnesium-burnettite-type compound by lowering the interface energy between the electrode and the anode, for example, the anode and the electrolyte. Therefore, the magnesium battery including the compound has an improved capacity, Voltage, and improved lifetime characteristics.

FIG. 1 is a graph showing the relationship between the electrode active material of Mn ₃ O ₄ of spinel structure according to Production Example 1, for example, the electrode of a magnesium-burned site hydrated manganese composite oxide having a layered nanosheet structure according to Example 1, And is a schematic diagram showing that the phase is changed by an electrochemical synthesis method with an active material, for example, a cathode active material.

The hydrated manganese-based complex oxide may be a phase-changed product by an electrochemical synthesis method. The Mn ₃ O ₄ electrode active material of the spinel structure according to Preparation Example 1, for example, the cathode active material has almost no reversible activity, and its capacity is almost zero. However, in the hydrated manganese composite oxide according to an embodiment of the present invention, the electrode active material, for example, the positive electrode active material has reversible activity due to the phase change and the layer interval is widened to 4.97 Å to 7.39 Å Thereby enabling the magnesium battery including the electrode active material, for example, the positive electrode active material, to have improved capacity, improved charge / discharge voltage, and improved lifetime characteristics.

The electrode active material for a magnesium battery may further include a carbonaceous material. The carbon material may form a composite with the electrode active material for the magnesium battery. The content of the carbonaceous material may be 0.1 wt% to 30 wt% with respect to the total weight of the electrode active material for the magnesium battery. The content of the carbonaceous material may be, for example, 0.1 wt% to 25 wt% with respect to the total weight of the electrode active material for the magnesium battery. The content of the carbonaceous material may be, for example, 0.1% by weight to 20% by weight based on the total weight of the electrode active material for a magnesium battery.

The electrode active material for the magnesium battery may be a cathode active material.

The electrode for a magnesium battery according to another aspect includes the above-described electrode active material.

According to another aspect of the present invention, there is provided a magnesium battery comprising: a positive electrode comprising the above-described electrode active material as a positive electrode positive electrode active material; cathode; And an electrolyte; .

The magnesium battery may be a primary battery or a secondary battery, and the magnesium secondary battery may be prepared, for example, as follows.

First, the anode can be prepared, for example, as follows.

For example, a cathode active material composition comprising a cathode active material including a hydrated manganese composite oxide having a layered nanosheet structure represented by Formula 1, a conductive material, a binder, and a solvent is prepared. The positive electrode active material composition is directly coated on the metal current collector to produce a positive electrode plate. Alternatively, the cathode active material composition may be cast on a separate support, and then the film peeled from the support may be laminated on the metal current collector to produce a cathode plate. The anode is not limited to those described above, but may be in a form other than the above.

The positive electrode may further include a conventional positive electrode active material in addition to the positive electrode active material.

For example, conventional conventional cathode active materials include oxides of metals selected from the group consisting of scandium, ruthenium, titanium, vanadium, molybdenum, chromium, manganese, iron, cobalt, nickel, copper, lead, tungsten, zirconium, Or a halide; And a magnesium complex metal oxide.

For example, at least one of Co ₃ O ₄ , Mn ₂ O ₃ , Mn ₃ O ₄ , MoO ₃ , PbO ₂ , Pb ₃ O ₄ , RuO ₂ , V ₂ O ₅ , WO ₃ , TiS ₂ , VS ₂ , ZrS ₂ , Mo ₃ O ₄ , Mo ₆ S ₈ , MoB ₂ , TiB ₂ , or ZrB ₂ may be used, but the present invention is not limited thereto. In addition, examples of the magnesium composite metal oxide include Mg (M _{1 - x} A _x ) O ₄ (0? _X ? 0.5, M is Ni, Co, Mn, Cr, V, Fe, , Si, Cr, V, C, Na, K, or Mg) may be used.

As the conductive material, a carbon material having a high specific surface area such as carbon black, activated carbon, acetylene black, or a mixture of two or more of graphite fine particles may be used. Further, electroconductive fibers such as fibers produced by carbonizing vapor-grown carbon or pitch (by-products such as petroleum, coal, coal tar and the like) at high temperature and carbon fibers prepared from acrylic fibers (polyacrylonitrile) . Carbon fiber and a carbon material having a high specific surface area can be used simultaneously. The use of the carbon fiber and the carbon material having a high specific surface area simultaneously can further improve the electric conductivity. Further, a metal-based conductive material having a lower electrical resistance than that of the cathode active material can be used as a material which does not dissolve in the charge and discharge range of the anode. For example, a corrosion-resistant metal such as titanium or gold, a carbide such as SiC or WC, or a nitride such as Si ₃ N ₄ or BN can be used, but not limited thereto, and any material that can be used as a conductive material in the related art Do.

Examples of the binder include vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethylmethacrylate, polytetrafluoroethylene and mixtures thereof, and styrene butadiene rubber-based polymers But are not limited thereto and can be used as long as they can be used as binders in the art.

As the solvent, N-methylpyrrolidone, acetone, water or the like may be used, but not limited thereto, and any solvent which can be used in the technical field can be used.

The metal current collector is not limited to a material, a shape, a manufacturing method, and the like, and a stable material can be used electrochemically. The metal current collector may be an aluminum foil having a thickness of 10 to 100 탆, an aluminum punched foil having a thickness of 10 to 100 탆, a hole diameter of 0.1 to 10 mm, an expanded metal, a foamed metal plate and the like. As the material of the metal current collector, besides aluminum, stainless steel, titanium and the like can also be used.

The content of the positive electrode active material, the conductive material, the binder and the solvent is a level commonly used in a magnesium battery. One or more of the conductive material, the binder and the solvent may be omitted depending on the use and configuration of the magnesium battery.

The working potential of the cathode active material may be 2.0 V to 4.0 V (vs. Mg / Mg ^{2 +} ). For example, the working potential of the cathode active material may be 2.5 V to 4.0 V (vs. Mg / Mg ^{2 +} ). The cathode active material may have a high charge / discharge capacity even under a high voltage within the above range.

Next, the cathode is prepared.

In the magnesium battery, the negative electrode may include magnesium metal, a magnesium-based alloy, a magnesium intercalating compound, or a carbon-based material. However, the negative electrode is not limited thereto and may be used as an anode active material in the art. Or can absorb / release magnesium.

Since the negative electrode determines the capacity of the magnesium battery, the negative electrode may be, for example, magnesium metal. Examples of the magnesium-based alloy include alloys of aluminum, tin, indium, calcium, titanium, vanadium, and the like and magnesium.

For example, the negative electrode may be used in a variety of forms such as a film, a sheet, a foil, a net, a porous body, a foam, a nonwoven fabric, and the like.

When a magnesium alloy or a magnesium alloy is used for the negative electrode active material, at least a part of the battery container is made of magnesium metal or magnesium alloy, which is an anode active material, Can be combined. Even when the battery case is made of magnesium metal or the like, magnesium metal and the like are mostly inert in the air, and therefore handling and safety are excellent. Therefore, a magnesium secondary battery having a battery case having a negative electrode can reduce the weight of the battery as compared with a lithium secondary battery, and thus a magnesium secondary battery having excellent energy density, output density, and the like can be obtained.

When an anode active material other than a magnesium metal or a magnesium alloy is used, a carbon-based material having a graphene structure or the like can be used. A mixed cathode of a material such as graphite and graphitic carbon, a mixed cathode of a carbon-based material and a metal or an alloy, and a composite cathode may be used. Examples of the carbon-based material include natural graphite, artificial graphite, mesophase carbon, expanded graphite, carbon fiber, vapor grown carbon fiber, pitch-based carbonaceous material, needle coke, petroleum coke, A carbonaceous material such as polyacrylonitrile-based carbon fiber and carbon black, or an amorphous carbon material synthesized by thermal decomposition of a cyclic hydrocarbon or a cyclic oxygen-containing organic compound of a 5-membered ring or a 6-membered ring.

In the case where the negative electrode active material is in powder form, the negative electrode can be produced as follows. The negative electrode can be produced in the same manner as the positive electrode except that the negative electrode active material is used instead of the positive electrode active material. The conductive agent, binder and solvent in the negative electrode active material composition may be the same as those in the case of the positive electrode.

For example, a negative electrode active material composition is prepared by mixing a negative electrode active material, a conductive agent, a binder, and a solvent, and directly coated on the copper current collector to produce a negative electrode plate. Alternatively, the negative electrode active material composition may be cast on a separate support, and the negative electrode active material film peeled from the support may be laminated on a copper current collector to produce a negative electrode plate.

As the negative electrode current collector, any current collector can be used without being limited to material, shape, manufacturing method, and the like. For example, a copper foil having a thickness of 10 to 100 탆, a copper perforated foil having a thickness of 10 to 100 탆, a hole diameter of 0.1 to 10 mm, an expanded metal, a foamed metal plate and the like can be used. As the material of the negative electrode current collector, besides copper, stainless steel, titanium, nickel and the like can be used.

The content of the negative electrode active material, the conductive agent, the binder and the solvent is a level commonly used in a magnesium battery.

Next, a separator is prepared.

The magnesium battery may further include a separator interposed between the anode and the cathode.

The separator is not limited as long as it can withstand the use environment of the magnesium battery. For example, the separator may be formed of a nonwoven fabric made of polypropylene material or a nonwoven fabric made of polyphenylene sulfide material, a porous nonwoven fabric made of an olefin resin such as polyethylene or polypropylene Film may be exemplified, and two or more kinds of these may be used in combination.

The separator may have a low resistance against the ion movement of the electrolyte and an excellent electrolyte wettability. For example, glass fiber, polyester, Teflon, polytetrafluoroethylene (PTFE), or a combination thereof, and may be nonwoven fabric or woven fabric.

For example, the separator may be produced according to the following method.

A polymer resin, a filler and a solvent are mixed to prepare a separator composition. The separator composition may be directly coated on the anode active material layer and dried to form a separator. Alternatively, after the separator composition is cast and dried on a support, a separator film peeled off from the support may be laminated on the negative active material layer to form a separator.

The polymer resin used in the production of the separator is not particularly limited, and any material used for the binder of the electrode plate may be used. For example, polyethylene, polypropylene, vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethyl methacrylate or mixtures thereof may be used. As the filler used in the production of the separator, inorganic particles and the like can be used, and the solvent is capable of dissolving the polymer resin and forming pores in the polymer resin upon drying, so long as it is generally used in the related art .

Further, the separator may be separately manufactured by another publicly known method and laminated on the anode active material layer. For example, a dry manufacturing method in which a microporous film is formed by forming a film by melting and extruding polypropylene or polyethylene, annealing at a low temperature to grow a crystal domain, and then stretching in this state to extend an amorphous region Can be used. For example, a film obtained by mixing a low-molecular material such as a hydrocarbon solvent with polypropylene, polyethylene, or the like, and then forming a film, and then a solvent or a small molecule is gathered to form an island phase, A wet production method of forming a microporous membrane by removing a solvent or a low molecular weight using another volatile solvent may be used.

The separator may additionally contain additives such as non-conductive particles, other fillers, and fiber compounds for the purpose of controlling strength, hardness and heat shrinkage. For example, the separator may further include inorganic particles. By further including the inorganic particles, the oxidation resistance of the separator is improved, and deterioration of the battery characteristics can be suppressed. The inorganic particles may be alumina (Al ₂ O ₃ ), silica (SiO ₂ ), titania (TiO ₂ ), or the like. The average particle diameter of the inorganic particles may be 10 nm to 5 占 퐉. When the average particle diameter is less than 10 nm, the crystallinity of the inorganic particles is lowered and the effect of addition is insignificant. When the average particle diameter exceeds 5 탆, dispersion of the inorganic particles may be difficult.

The separator may have a multi-layer structure including one or more polymer layers for the purpose of increasing the tear strength and mechanical strength. For example, a polyethylene / polypropylene laminate, a polyethylene / polypropylene / polyethylene laminate, a nonwoven fabric / polyolefin laminate, and the like.

Next, the electrolyte is prepared.

The electrolyte is a liquid containing magnesium in an ionic state, and the magnesium salt to be an electrolyte is dissolved in a solvent. The electrolyte may comprise an organic electrolyte using an organic solvent, or an aqueous electrolyte using water as a solvent.

The electrolyte of the magnesium battery according to one embodiment may be an aqueous electrolyte. Examples of the magnesium salt which can be used as the electrolyte include Mg (OH) ₂ , MgSO ₄ , MgCl ₂ , Mg (NO ₃ ) ₂ and the like, but not limited thereto, and if they can be used as a water soluble magnesium salt Everything is possible. Mg (OH) ₂ or MgSO ₄ may be used as the electrolyte in order to prevent the deterioration (i.e., oxidation) of the negative electrode in a negative electrode using a magnesium metal or a magnesium alloy as a negative electrode active material. In the case of a water-based electrolyte, the electrolyte concentration may be a saturated concentration or a concentration close to that, in order to increase the conductivity of the electrolyte.

Since the aqueous electrolyte does not use an organic solvent, there is an advantage that the solvent does not burn.

4 is a graph showing Nyquist plots and interfacial resistance in the case where water of 0 M, 0.5 M, 2 M, 5 M, and 10 M is contained in an electrolyte of a magnesium battery.

Referring to FIG. 4, it can be seen that as the concentration of water in the electrolyte of the magnesium battery increases from the concentration of 0M to the concentration of 10M, the interface resistance between the electrolyte and the anode gradually decreases. From the above results, it is believed that the manganese-based complex oxide according to an embodiment of the present invention includes crystalline water in the interlayer, so that it is possible to achieve a low interface resistance between the electrolyte and the anode in addition to the effect of the aqueous electrolyte.

On the other hand, an organic electrolyte may be included to constitute a magnesium secondary battery having a high output density depending on the case.

In the organic electrolyte, as the magnesium salts used as an _{electrolyte, Mg (BF 4) 2,} Mg (PF 6) 2, Mg (ClO 4) 2, Mg (CF 3 SO 3) 2, Mg (AsF 6) 2 , etc. Can be used.

As the organic solvent in the organic electrolyte, an aprotic organic solvent may be used. For example, the organic electrolyte for a magnesium secondary battery may include at least one selected from the group consisting of dimethyl ether, diethyl ether, dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, ethylene carbonate, propylenecarbonate, , Methyl acetate, ethyl acetate, n-propyl acetate, dimethylacetate, methyl propionate, ethyl propionate,? -Butyrolactone, decanolide, valerolactone, mevalonolactone, Caprolactone, dibutyl ether, tetraglyme, diglyme, polyethylene glycol dimethyl ether, dimethoxyethane, 2-methyltetrahydrofuran, 2,2-dimethyltetrahydrofuran, 2,5-dimethyltetrahydrofuran , Cyclohexanone, triethylamine, triphenylamine, triethylphosphine oxide But are not limited to, at least one organic solvent selected from the group consisting of hydrochloric acid, nitric acid, phosphoric acid, nitric acid, phosphoric acid, phosphoric acid, phosphoric acid, Anything that can be done is possible.

The concentration of the electrolyte in the organic electrolyte may be 0.001M to 10M. If the concentration is low, the conductivity is lowered, and if the concentration is high, the viscosity becomes too high and low-temperature characteristics may be deteriorated. The electrolyte may further include a flame retardant such as phosphorous ester or phosphorous acid ester.

As shown in FIG. 7, the magnesium battery 1 includes an anode 3, a cathode 2, and a separator 4. The positive electrode 3, the negative electrode 2 and the separator 4 described above are wound or folded and accommodated in the battery case 5. Subsequently, an aqueous electrolyte is injected into the battery case 5 and sealed with a cap assembly 6, thereby completing the magnesium battery 1. The battery case may have a cylindrical shape, a rectangular shape, a thin film shape, or the like. For example, the magnesium battery may be a large-sized thin-film battery. The magnesium battery may be a magnesium ion battery.

A separator may be disposed between the anode and the cathode to form a battery structure. The battery structure is laminated in a bi-cellular structure, then impregnated with an aqueous electrolyte, and the obtained result is received in a pouch and sealed, thereby completing a magnesium polymer battery.

In addition, a plurality of battery structures may be stacked to form a battery pack, and such a battery pack may be used for all devices requiring a high capacity. For example, a notebook, a smart phone, an electric vehicle, and the like.

In addition, the magnesium battery is excellent in storage stability and thermal stability, and thus can be used in an energy storage system (ESS), an electric vehicle (EV), and the like. For example, a hybrid vehicle such as a plug-in hybrid electric vehicle (PHEV).

According to another aspect of the present invention, there is provided a method of manufacturing an electrode active material for a magnesium battery, comprising: preparing a nanostructured spinel-type manganese oxide; And a step of preparing a hydrated manganese-based composite oxide having the layered nanosheet structure by electrochemical synthesis of the nanostructured spinel-type manganese oxide.

The nanostructured spinel-type manganese oxide may be prepared by hydrothermal synthesis, microwave synthesis, ultrasonic synthesis, liquid phase synthesis or solid phase synthesis.

For example, hydrothermal synthesis may be used to produce the spinel-type manganese oxide of the nanostructure. The spinel-type manganese oxide having a nanostructure may be prepared by, for example, putting the spinel-type manganese oxide precursor and a solvent in a reactor and maintaining the reactor in an electric furnace at 160 ° C to 210 ° C for 1 hour to 24 hours, Followed by filtration and drying.

The electrochemical synthesis method may be a galvanostactic method or a cycle voltametry method. The electrochemical synthesis can be carried out, for example, by a galvanostactic method or a cyclic voltammetry at a current density of 10 to 1000 mA / g in a voltage range of -1.0 V to 1.0 V (vs. Ag / Ag ⁺ ) To produce a phase change of the spinel-type manganese oxide of the nanostructure through repeated charge-discharge.

For example, the current density is a theoretical capacity of a hydrated manganese composite oxide of a layered nanosheet structure. When the C-rate is set based on the theoretical capacity of 230 mAh / g when Mg ^{2 +} ions are implanted, 5C. &Lt; / RTI &gt;

The charge-discharge cycle range may be, for example, from 1 cycle to 500 cycles, for example from 1 cycle to 300 cycles, for example from 1 cycle to 100 cycles, for example, Can be from 1 cycle to 50 cycles, for example from 1 cycle to 30 cycles.

The electrode active material prepared by the electrochemical synthesis method may have a layered structure having a thinner thickness than the electrode active material prepared by a chemical synthesis method such as an oxidation reaction using an oxidizing agent or a reduction reaction using a reducing agent, The capacity, charge / discharge voltage, and lifetime characteristics of the magnesium battery including the electrode active material produced by the electrochemical synthesis method can be improved.

The present invention will be described in more detail with reference to the following examples and comparative examples. It should be noted, however, that the examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[Example]

(Production of cathode active material)

Manufacturing example  One: Spinel  Structural Mn ₃ O ₄ Cathode active material manufacturing

10 mmol of Mn (CH ₃ COO) ₂ .4H ₂ O (Mn (Ac) ₂ ) was dissolved in 100 mL of absolute ethanol. The mixture was then stirred until a clear solution and the inner wall was transferred to a Teflon-lined stainless steel autoclave coated with Teflon. The autoclave was maintained in an electric furnace at a heating rate of 10 DEG C / min at 160 DEG C for 8 hours and then cooled to room temperature. After separating the precipitated resulting in a centrifuge and distilled water, and then washed several times with ethanol, under an atmosphere at 60 ℃ for 24 hours, heat-treated dried to produce a positive electrode active material of Mn ₃ O ₄ of spinel structure having an octahedral form of 100nm size .

Example  1: a magnesium-magnesium alloy having a layered nanosheet structure; Burnett Site Type  Sign Language( hydrated ) Preparation of cathode active material of manganese composite oxide

The positive electrode active material of a spinel structure of the Mn ₃ O ₄ according to Preparation Example 1, a conductive material, ketjen black (Ketjen black), polyvinylidene fluoride (PVdF) to NMP (N- methyl in a weight ratio of 60:20:20 in a binder Pyrrolidone) and mixed to prepare a cathode active material slurry. The slurry was brush-coated to a thickness of 250 to 300 mu m on a current collector made of stainless steel (SUS 304) mesh, dried in a vacuum oven at 70 DEG C for 6 hours, cut into a size of 10 mm x 10 mm, .

The positive electrode plate was disposed as a working electrode in a Teflon container and a magnesium foil having a thickness of 100 mu m was cut into a size of 30 mm x 10 mm with a counter electrode and Ag / AgCl Electrode and a 1M MgSO ₄ aqueous solution was used as the electrolyte. The interior of the Teflon container was an argon atmosphere and sealed to block the air.

The capacitor of the three electrode cell is subjected to a voltage range of -1.0 V to 1.0 V (vs. Ag / Ag ⁺ ) and a current density of 10 to 1000 mA / g using a galvanostatic method, When the C-rate is set based on the theoretical capacity of 230 mAh / g when Mg ^{2 +} ions are inserted as the theoretical capacity of the hydrated manganese composite oxide of the structure, the charge and discharge are repeated up to 50 cycles at 2C, spinel structure, Mn ₃ O positive electrode active material layer of the nano-sheet structure ₄ according to the magnesium-Burnett - type sign Language (hydrated) manganese composite oxide of Mg _{0 .05} MnO ₂ · 0.94H ₂ O phase with the positive electrode active material of the composition ( phase.

Comparative Example  1: layered Burnett Site Type  Preparation of cathode active material of manganese oxide

After 10 mmol of KMnO ₄ salt was dissolved in 100 ml of distilled water, 50 ml of 1 M NaOH was added thereto. The mixture was stirred for 1 hour, 10 mmol of H ₂ O ₂ was added thereto and mixed at room temperature to precipitate manganese oxide. The precipitated manganese oxide was stored at room temperature for 24 hours, and then the residual distilled water was removed to prepare a manganese oxide having a burnet structure.

Comparative Example  2: Magnesium-containing layer structure of layered nanosheet structure Burnett Site Type  Preparation of cathode active material for manganese composite oxide

Example 1 mg of the layered structure of the nanosheets - Burnett - Type Sign Language (hydrated) manganese composite oxide of Mg _{0 .05} MnO ₂ · heat-treating the positive electrode active material of the composition at 300 ℃ 0.94H ₂ O for 5 h layered nano A cathode active material having a Mg _0.05 MnO ₂ composition of a magnesium-burned site type manganese composite oxide having a sheet structure was prepared.

 (Preparation of magnesium battery)

Example  2: Preparation of magnesium battery

Ketjen black as a conductive material, and polyvinylidene fluoride (PVdF) as a binder were added to NMP (N-methylpyrrolidone) in a weight ratio of 70:10:20 and mixed with the cathode active material according to Example 1, To prepare a cathode active material slurry. The slurry was tape-coated to a thickness of 200 탆 on an aluminum current collector having a thickness of 15 탆, dried in a vacuum oven at 120 캜 for 2 hours, and cut into a circle having a diameter of 12 mm to prepare a positive electrode plate.

The positive electrode plate was disposed as a working electrode in a Teflon container, a magnesium foil having a thickness of 100 mu m was used as a counter electrode, an Ag / AgCl electrode was used as a reference electrode, A 3-electrode system was constructed using an organic electrolyte in which 0.5 M Mg (ClO ₄ ) ₂ was dissolved in AC (acetonitrile). The interior of the Teflon container was an argon atmosphere and sealed to block the air.

Comparative Example  3: Preparation of magnesium battery

A magnesium battery was prepared in the same manner as in Example 2, except that the cathode active material according to Comparative Example 1 was used in place of the cathode active material according to Example 1.

Comparative Example  4: Manufacture of magnesium battery

A magnesium battery was produced in the same manner as in Example 2, except that the cathode active material according to Comparative Example 2 was used in place of the cathode active material according to Example 1.

Evaluation example  1: Scanning electron microscope ( SEM ) Image evaluation

SEM images of the cathode active material according to Production Example 1, Example 1, and Comparative Example 1 were observed. The observed results are shown in Figs. 2A to 2C. The scanning electron microscope (SEM) used in the observation was JSM-7600F from JEOL.

Referring to FIG. 2A, the Mn ₃ O ₄ cathode active material of the spinel structure according to Production Example 1 exhibits an irregular polyhedral shape such as a tetrahedron and an octahedron.

Referring to FIG. 2B, the cathode active material of the magnesium-burnettite type hydrated manganese composite oxide having the layered nanosheet structure according to Example 1 is a thin sheet such as a thin paper, and has a large space between layers and layers Respectively. In addition, it can be confirmed that the cathode active material of the magnesium-burnettite hydrated manganese composite oxide having the layered nanosheet structure according to Example 1 has a layered nanosheet structure with a thickness of about 11 nm.

Referring to FIG. 2C, the positive electrode active material of the magnesium-burnsite-type manganese composite oxide having the layered structure according to Comparative Example 1 has a thin layer having a thickness greater than that of the positive electrode active material layer according to Example 1, As shown in FIG. In addition, it can be confirmed that the cathode active material of the magnesium-burnetite-type manganese composite oxide of the layer-like structure according to Comparative Example 1 is a layer-like structure having a thickness of about 11 nm.

Evaluation example  2: XRD  evaluation

X-ray diffraction (XRD) experiments were performed on the cathode active material according to Example 1 and Comparative Example 2. The experimental results are shown in Fig. 3 and Table 1 below. The XRD device used in the experiment was a CuK-alpha characteristic X-ray wavelength of 1.541 Å.

Specifically, the peak of the (001) plane and the peak of the (101) plane of the cathode active material according to Example 1 and Comparative Example 2 were observed by the X-ray diffraction (XRD) test and are shown in FIG.

3, the surface spacing d ₀₀₁ of the cathode active material according to Example 1 was 7.39 Å, and the surface spacing d ₁₀₁ of the cathode active material according to Comparative Example 2 was 4.97 Å. As a result, it can be seen that the layer spacing of the cathode active material according to Example 1 is kept wider than the layer spacing of the cathode active material according to Comparative Example 2.

Evaluation example  3: Charging and discharging  Characteristic Experiment Evaluation

The magnesium batteries according to Example 2 and Comparative Example 4 were charged and discharged at a constant current of 1 / 10C in a voltage range of 2.5V to 4.2V versus Li / Li ⁺ at room temperature. Thereafter, charge and discharge were continued until the tenth cycle, and the discharge voltage and the discharge capacity in each cycle were measured. The results are shown in Fig. 5, Fig. 6, and Table 1, respectively.

At this time, the average discharge voltage was obtained by integrating discharge curves in the graph of electric capacity (x axis) -voltage (y axis) and dividing the integral value by the maximum discharge capacity. The lifetime characteristic was evaluated by calculating the capacity retention (%) from the following equation (1).

[Equation 1]

Capacity retention (%) = [(Discharge capacity in 10th cycle / Discharge capacity in 1st cycle)] x 100

division In the first cycle, the discharge capacity (mAh / g) In the tenth cycle, the discharge capacity (mAh / g) Capacity retention rate (%) Average discharge voltage (V, vs Li / Li ⁺ ) Example 2 240 150 62 3.28 Comparative Example 4 180 60 33 3.2

5, 6, and Table 1, it can be seen that the magnesium battery according to Example 2 has a higher average discharge voltage in the second cycle than the magnesium battery according to Comparative Example 4. It can be seen from the above that the magnesium battery according to Example 2 has a reduced overvoltage as compared with the magnesium battery according to Comparative Example 4.

It can also be seen that the magnesium battery according to Example 2 has higher discharge capacity in the first cycle, discharge capacity in the tenth cycle, and capacity retention ratio than the magnesium battery according to Comparative Example 4. Particularly, it can be seen that the discharge capacity of the magnesium battery according to Example 2 is maintained substantially even until the 30th cycle. It can be seen from these results that the lifetime characteristics of the magnesium battery according to Example 2 are improved compared to the magnesium battery according to Comparative Example 4. [

1: magnesium battery, 2: negative electrode, 3: positive electrode,
4: separator, 5: battery case, 6: cap assembly,
^{10: Mn 2 +, 11:} Mn 3 +, 12: O,
13: Mg, 14: Mn ^{4 +}

Claims (20)

An electrode active material for a magnesium battery comprising a hydrated manganese composite oxide having a layered nanosheet structure represented by the following formula (1)
[Chemical Formula 1]
M _x Mn _{1 -y} (MI) _y O ₂ .zH ₂ O
In this formula,
0 &lt; x < 1, 0 < y &
M is at least one metal selected from Mg ^{2 +} , Ca ^{2 +} , Na ⁺ , K ⁺ , and Zn ^{2 +}
MI is a transition metal. The electrode active material for a magnesium battery according to claim 1, wherein the hydrated manganese composite oxide is represented by the following formula (2)
(2)
Mg _u Mn _{1 -v} (MII) _v O ₂ .wH ₂ O
In this formula,
0 < u < 1, 0 &lt; v &
MII is at least one transition metal selected from Co, Ni, Fe, and Cu. The electrode active material according to claim 1, wherein the hydrated manganese composite oxide is a magnesium-burnite-type compound. The electrode active material according to claim 1, wherein the hydrated manganese composite oxide comprises a monoclinic crystal structure, a mesoporous crystal structure, a hexagonal crystal structure, or a combination thereof. The electrode active material according to claim 1, wherein the hydrated manganese composite oxide is a layered nanosheet structure having a thickness of 1 nm to 50 nm. The electrode active material for a magnesium battery according to claim 1, wherein the hydrated manganese composite oxide has a layered nanosheet structure with a layer interval of 5 to 20 angstroms. The electrode active material for a magnesium battery according to claim 1, wherein the manganese-based composite oxide contains crystal water between the layers. 8. The electrode active material according to claim 7, wherein the crystal number interrupts electrostatic interactions between the magnesium cation (Mg ^&lt; ^{2 + &} gt ^; ) and the anions constituting the positive electrode active material. The electrode active material for a magnesium battery according to claim 1, wherein the hydrated manganese composite oxide is a result of a phase change by an electrochemical synthesis method. The electrode active material for a magnesium battery according to claim 1, wherein the electrode active material for a magnesium battery further comprises a carbonaceous material. The electrode active material for a magnesium battery according to claim 10, wherein the content of the carbonaceous material is 0.1 wt% to 30 wt% with respect to the total weight of the electrode active material for a magnesium battery. The electrode active material according to claim 1, wherein the electrode active material for a magnesium battery is a positive electrode active material. An electrode for a magnesium battery comprising the electrode active material according to any one of claims 1 to 11. A positive electrode comprising the electrode active material according to any one of claims 1 to 11 as a positive electrode active material;
cathode; And
Electrolyte; &Lt; / RTI &gt; 15. The magnesium battery according to claim 14, wherein the working potential of the cathode active material is 2.0 V to 4.0 V (vs. Mg / Mg ^{2 +} ). 15. The magnesium battery according to claim 14, wherein the electrolyte is an aqueous electrolyte. Preparing a nanostructured spinel-type manganese oxide; And
The method for producing an electrode active material for a magnesium battery according to claim 1, wherein the spinel-based manganese oxide having the nanostructure is produced by an electrochemical synthesis method to produce a hydrated manganese-based complex oxide having a layered nanosheet structure according to claim 1. The method of claim 17, wherein the nanostructured spinel-type manganese oxide is produced by hydrothermal synthesis, microwave synthesis, ultrasonic synthesis, liquid phase or solid phase. 18. The method of claim 17, wherein the electrochemical synthesis method is a galvanostactic method or a cycle voltametry method. 18. The method of claim 17, wherein the electrochemical synthesis is carried out by repeated charging / discharging in a voltage range of -1.0 V to 1.0 V (vs. Ag / Ag ⁺ ) by a galvanostactic method or a cyclic voltammetry method. A method for producing an electrode active material for a magnesium battery, which causes a phase change of a spinel-type manganese oxide having a nanostructure.

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