KR101993462B1 - Polymer-magnesium ion conductive material, method for preparing the same, magnesium ion conductive polymer film comprising the same, and magnesium battery comprising the magnesium ion conductive polymer film - Google Patents

Abstract

The present invention relates to a polymer-magnesium ion conductor, a method for producing the same, a magnesium ion conductive polymer membrane including the same, and a magnesium battery including the magnesium ion conductive polymer membrane, wherein the polymer-magnesium ion conductor includes a polymer and a magnesium salt do.
The polymer-magnesium ion conductor exhibits excellent magnesium ion conductivity and can be improved in battery characteristics when it is applied as an electrolyte of a battery, particularly a magnesium battery.

Description

TECHNICAL FIELD The present invention relates to a polymer-magnesium ion conductor, a method for producing the same, a magnesium ion conductive polymer membrane including the same, and a magnesium battery including the magnesium ion conductive polymer membrane. BACKGROUND ART [0002] THE SAME, AND MAGNESIUM BATTERY COMPRISING THE MAGNESIUM ION CONDUCTIVE POLYMER FILM}

The present invention relates to a polymer-magnesium ion conductor having excellent magnesium ion conductivity, a method for producing the same, a magnesium ion conductive polymer membrane including the same, and a magnesium battery including the magnesium ion conductive polymer membrane.

Renewable energy, which is attracting attention as a future alternative energy source, requires an energy storage system (EES) capable of efficiently storing and supplying electricity to the power grid to improve power quality and efficiency .

As a device for storing energy for such an electric power storage system, a lithium battery, for example, a lithium ion secondary battery, has been attracting attention. However, lithium ion batteries have limitations in terms of the resource uniformity of lithium, high cost, and stability for storage of energy for large capacity power storage systems in terms of stability such as explosion risk when exposed to air.

In addition, lead acid batteries used as alternatives are 25% of the unit cost per unit energy density compared to lithium ion secondary batteries, but they are compensated for by the deterioration of lifetime during deep charge / discharge and the low lifetime within 5 years The cost of maintaining and repairing is incurred. Restriction of lead use and recycling obligation are applied by the Restriction of Hazardous Substances (EEE) (RoHS) Restriction of Hazardous Substances in EEE .

However, unlike lithium, magnesium used in magnesium batteries can be obtained from a large amount of brine and minerals, which is inexpensive, eco-friendly and easy to handle. In addition, the capacity per unit volume of magnesium is very high as 3,833 mAh / ㎤ compared to 2,061 mAh / ㎤ per unit volume of lithium, and it is superior in stability compared to lithium. Therefore, development potential for magnesium battery as a device for storing energy for large- very big.

However, unlike lithium ion, magnesium ion has a high electric charge characteristic with two charges, and strong Coulomb interaction occurs with the electrode active material, for example, the elements constituting the cathode active material when inserted into the cathode active material The diffusion rate of magnesium ions is slowed down. As a result, the actual capacity is lowered and the reversibility, initial efficiency, and discharge voltage are lowered.

Accordingly, there is a demand for development of materials for magnesium batteries, particularly magnesium ion conductors, which can exhibit excellent magnesium ion conductivity even under a high voltage, as an apparatus for storing energy for a large-capacity power storage system.

An object of the present invention is to provide a polymer-magnesium ion conductor having excellent magnesium ion conductivity for solving the above-mentioned problems of the prior art.

Another object of the present invention is to provide a method for producing the polymer-magnesium ion conductor.

Another object of the present invention is to provide a magnesium ion conductive polymer membrane including the polymer-magnesium ion conductor.

Still another object of the present invention is to provide an electrochemical device including the polymer-magnesium ion conductor, and a magnesium battery.

According to an embodiment of the present invention, there is provided a polymer-magnesium ion conductor including a polymer and a magnesium salt.

The polymer may be selected from the group consisting of polyalkyl (meth) acrylates, polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoroethylene (HFP) Lt; / RTI >

The polymer may be polymethylmethacrylate (PMMA).

The magnesium salt may be included in an amount of 5 to 50% by weight based on the total weight of the polymer-magnesium ion conductor.

The magnesium salts are the _{Mg (ClO 4) 2, MgCF} 2 SO 2, Mg (CF 3 SO 3) 2, Mg (BF 4) 2, Mg (PF 6) 2, Mg (AsF 6) 2 , and combinations thereof And the like.

According to another embodiment of the present invention, there is provided a process for preparing a polymer-containing solution, comprising the steps of preparing a polymer-containing solution by dissolving the polymer in an organic solvent, and mixing the salt solution prepared by dissolving the magnesium salt in an organic solvent with the polymer- , And a method for producing a polymer-magnesium ion conductor.

According to another embodiment of the present invention, there is provided a liquid crystal display comprising: first and second polymer matrices facing each other; And a magnesium ion conductive polymer layer positioned between the first and second polymer matrices, wherein the magnesium ion conductive polymer layer comprises the polymer-magnesium ion conductor.

The first and second polymer matrices may each independently include a polyolefin-based polymer.

The polymer-magnesium ion conductor may be included in an amount of 0.1 to 10% by weight based on the total weight of the magnesium ion conductive polymer film.

According to another embodiment of the present invention, there is provided an electrochemical device including the magnesium ion conductive polymer membrane.

According to another embodiment of the present invention, there is provided a magnesium battery including the magnesium ion conductive polymer membrane.

The polymer-magnesium ion conductor according to the present invention exhibits excellent magnesium ion conductivity by the magnesium salt bonded to the polyalkyl (meth) acrylate-based polymer. Accordingly, when the polymer-magnesium ion conductor is applied to an electrochemical device, particularly a magnesium battery, the charging / discharging efficiency and the capacity characteristics can be improved.

FIG. 1 is a schematic view illustrating a change in an electric field applied to a polymer-magnesium ion conductor according to an embodiment of the present invention. Referring to FIG.
2 is a schematic view schematically illustrating a structure of a magnesium ion conductive polymer membrane including a polymer-magnesium ion conductor according to an embodiment of the present invention.
3 is a schematic diagram schematically showing a cell configuration for evaluating the magnesium ion conductivity in Experimental Example 1. FIG.

Hereinafter, the present invention will be described in more detail.

The polymer-magnesium ion conductor according to an embodiment of the present invention includes a polymer and a magnesium salt.

Wherein the polymer is selected from the group consisting of polyalkyl (meth) acrylates, polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), and polyvinylidene fluoride-hexafluoroethylene (HFP) One or a mixture of two or more. More specifically, considering the remarkable effect of improving the magnesium ion conductivity and cycle characteristics by the combination with the magnesium salt, the polyalkyl (meth) acrylate may be polymethyl methacrylate (PMMA) have.

FIG. 1 is a diagram schematically showing a change in the polymer-magnesium ion conductor when an electric field is applied thereto. Referring to FIG. 1, the polymer has an ion coordinating function in the polymer, so that adjacent chains and ions can cooperatively coordinate. It can be bonded by the coordination exchange process between the magnesium ion and the polymer chain to exhibit the conductivity to the magnesium ion.

More specifically, the magnesium salt is _{Mg (ClO 4) 2, MgCF} 2 SO 2, Mg (CF 3 SO 3) 2, Mg (BF 4) 2, Mg (PF 6) 2 or Mg (AsF _{6) 2} or the like And any one or a mixture of two or more thereof may be used.

The magnesium salt may be contained in an amount of 5 to 50% by weight based on the total weight of the polymer-magnesium ion conductor. When the content of the magnesium salt is less than 5% by weight, it is difficult to exhibit sufficient magnesium ion conductivity.

The polymer-magnesium ion conductor may include a step of dissolving the polymer in an organic solvent to prepare a polymer-containing solution (step 1), and a step of mixing the salt solution prepared by dissolving the magnesium salt in an organic solvent with the polymer-containing solution (Step 2). ≪ / RTI >

In the above production method, the kind and content of the polymer and the magnesium salt usable in the production of the polymer-containing solution and the salt solution are the same as those described above.

Examples of the organic solvent usable in the preparation of the polymer-containing solution and the salt solution include an alcohol-based solvent such as methanol, ethanol, propanol, isopropanol, butanol or isobutanol; Ether solvents such as diethyl ether, dipropyl ether, dibutyl ether, butyl ethyl ether, or tetrahydrofuran; Alcohol ether solvents such as ethylene glycol, propylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and ethylene glycol monobutyl ether; Ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone or cyclohexanone; Amide solvents such as N-methyl-2-pyrrolidinone, 2-pyrrolidinone, N-methylformamide or N, N-dimethylformamide; A sulfoxide-based solvent such as dimethylsulfoxide or diethylsulfoxide; Diethylsulfone, or tetramethylene sulfone; Nitrile solvents such as acetonitrile or benzonitrile; Amine-based solvents such as alkylamines, cyclic amines or aromatic amines; Ester solvents such as methyl butyrate, ethyl butyrate and propyl propionate; Carboxylic acid ester solvents such as ethyl acetate and butyl acetate; Aromatic hydrocarbon solvents such as benzene, ethylbenzene, chlorobenzene, toluene or xylene; Aliphatic hydrocarbon solvents such as hexane, heptane or cyclohexane; Halogenated hydrocarbon solvents such as chloroform, tetrachlorethylene, carbon tetrachloride, dichloromethane or dichloroethane; A carbonate-based solvent such as propylene carbonate, ethylene carbonate, dimethyl carbonate, dibutyl carbonate, ethyl methyl carbonate or dibutyl carbonate; And nitro-based solvents such as nitromethane and nitrobenzene. Any one or a mixture of two or more of them may be used. The organic solvent may be used in an appropriate amount in consideration of the concentration and fairness of the polymer-containing solution and the salt solution.

According to the above-described production method, a polymer-magnesium ion conductor in which a magnesium salt is bonded to a polymer can be easily produced. Also, the polymer-magnesium ion conductor produced according to the above-described production method can exhibit more excellent magnesium ion conductivity by uniformly and stably bonding the magnesium salt to the polymer.

The polymer-magnesium ion conductor itself may be applied to an electrochemical device requiring magnesium ion conductivity, or may be applied in the form of a complex structure depending on required functions and the like.

According to another embodiment of the present invention, there is provided a magnesium ion conductive polymer membrane including the polymer-magnesium ion conductor.

Specifically, the magnesium ion conductive polymer membrane may include first and second polymer matrices positioned opposite to each other; And a magnesium ion conductive polymer layer positioned between the first and second polymer matrices, wherein the magnesium ion conductive polymer layer includes the polymer-magnesium ion conductor.

2 is a schematic cross-sectional view illustrating the structure of a magnesium ion conductive polymer membrane according to an embodiment of the present invention. FIG. 2 is an illustration for illustrating the present invention, but the present invention is not limited thereto.

2, the magnesium ion conductive polymer membrane 100 according to an embodiment of the present invention includes first and second polymer matrices 10 and 20 positioned opposite to each other, Layer structure in which the magnesium-ion conductive polymer layer 30 including the polymer-magnesium ion conductor (not shown) is located between the first and second polymer matrices.

In the magnesium ion conductive polymer membrane, the first and second polymer matrices are located on both sides of the magnesium ion conductive polymer layer 30 and serve as a support. The first and second polymer matrices may have a low resistance to ion migration of magnesium. Specifically, the first and second polymer matrices may each independently comprise a polyolefin-based polymer such as polyethylene or polypropylene; glass fiber; Polyester; Polyacrylonitrile; And fluorine-based polymers such as polytetrafluoroethylene (PTFE), vinylidene fluoride / hexafluoropropylene copolymer and polyvinylidene fluoride (PVDF). Among these, more specifically, polyolefin- And more particularly polyethylene.

At least one of the first and second polymer matrices may be porous, and the polymer-magnesium ion conductor may be included in the pores of the first or second polymer matrix depending on the method of manufacturing the magnesium ion conductive polymer membrane .

Meanwhile, the magnesium ion conductive polymer layer includes a polymer-magnesium ion conductor, which is the same as described above.

In addition to the polymer-magnesium ion conductor, the magnesium ion conductive polymer layer may further include conventional additives.

In addition, the thickness of the magnesium ion conductive polymer layer is not particularly limited, and may be suitably adjusted in accordance with required physical properties according to application fields of the magnesium ion conductive polymer membrane.

In the magnesium ion conductive polymer membrane, the polymer-magnesium ion conductor may be included in an amount of 0.1 to 10% by weight based on the total weight of the magnesium ion conductive polymer membrane. If the content of the polymer-magnesium ion conductor in the magnesium ion conductive polymer membrane is less than 0.1 wt%, the magnesium ion conductivity of the magnesium ion conductive polymer membrane may be insignificant.

The magnesium ion conductive polymer membrane having the above structure is obtained by disposing a magnesium ion conductive polymer layer containing a polymer-magnesium ion conductor on a polymer matrix of any one of the first and second polymer matrices, ≪ / RTI >

Here, the magnesium ion conductive polymer layer may be formed by applying a composition containing a polymer-magnesium ion conductor, drying the composition, applying the composition on a separate support, and drying the magnesium ion conductive polymer layer to form a first or second And then transferred to a polymer matrix.

The composition comprising the polymer-magnesium ion conductor may be prepared by dissolving a polyalkyl (meth) acrylate-based polymer in an organic solvent to prepare a solution containing a polymer and a salt solution prepared by dissolving a magnesium salt in an organic solvent Wherein the preparation of each solution is the same as described above for the preparation of the polymer-magnesium ion conductor.

The step of applying the composition containing the polymer-magnesium ion conductor is not particularly limited, and may be carried out using a conventional slurry coating method such as bar coating or doctor blade coating.

The magnesium ion conductive polymer membrane as described above can be applied to various electrochemical devices requiring magnesium ion conductivity. In particular, when applied to a magnesium battery, life characteristics and capacity characteristics of the battery can be improved.

According to another aspect of the present invention, there is provided a magnesium battery including the magnesium ion conductive polymer membrane. The magnesium battery may be a primary battery or a secondary battery. Hereinafter, the case where the magnesium battery is a secondary battery will be mainly described, but the present invention is not limited thereto.

Specifically, the magnesium battery includes a cathode including a cathode active material disposed opposite to each other, a cathode including the anode active material, and a magnesium ion conductive polymer film interposed between the cathode and the anode. Here, in the magnesium ion conductive polymer membrane, the first and second polymer matrices may serve as a separator, and the magnesium ion conductive polymer layer may serve as a solid electrolyte.

The cathode and the anode may each have a conductive lead member for collecting a current generated during the operation of the battery, and the lead member may guide current generated in the anode and the cathode to the cathode terminal and the cathode terminal, respectively.

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

For example, a cathode active material composition in which a cathode active material, a conductive material, a binder, and a solvent are mixed 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 cathode active material may be any material capable of intercalating / deintercalating magnesium, and may be selected from the group consisting of scandium, ruthenium, titanium, vanadium, molybdenum, chromium, manganese, iron, cobalt, nickel, Oxides, sulfides or halides of metals selected from the group consisting of tungsten, zirconium and zinc; 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, polymethyl methacrylate, polytetrafluoroethylene and mixtures thereof, and styrene butadiene rubber-based polymers May be used, but the present invention is not limited thereto, and any material that can be used as a binder in the art can be used.

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. The material of the metal current collector may be stainless steel, titanium, etc. in addition to aluminum.

The content of the positive electrode active material, the conductive material, the binder and the solvent in the positive electrode 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.

Next, the cathode is prepared.

In the magnesium battery, the negative electrode may include, but is not necessarily limited to, a magnesium metal, a magnesium metal-based alloy, a magnesium intercalating compound, or a carbon-based material as an anode active material and may be used as an anode active material As long as it can contain magnesium or can intercalate / deintercalate magnesium, it can be used.

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 formed of magnesium in the form of a metal having a thickness of 3 to 500 μm, and may be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric.

When the magnesium battery uses magnesium metal or magnesium alloy as the negative electrode active material, integration of the negative electrode and the case, that is, at least a part of the case is formed of magnesium metal or magnesium alloy as the negative electrode active material, You can combine them. Even when the case is constituted by the magnesium metal or the like, magnesium metal and the like are mostly inert in the air, and therefore handling and safety are excellent. Therefore, the magnesium battery in which the case has the negative electrode can reduce the weight of the battery compared to the lithium secondary battery, and thus a magnesium battery having excellent energy density, output density, and the like can be obtained.

When an anode active material other than the magnesium metal or the 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 or graphitic carbon, a mixed cathode of a carbon-based material and a metal or an alloy, or a composite cathode may be used. Examples of the carbon-based material include natural graphite, artificial graphite, mesophase carbon, expanded graphite, carbon fiber, vapor growth carbon fiber, pitch-based carbonaceous material, and the like, which can electrochemically intercalate / deintercalate magnesium ions, Carbonaceous materials such as needle coke, petroleum coke, polyacrylonitrile-based carbon fibers and carbon black, amorphous carbon materials synthesized by thermal decomposition of cyclic hydrocarbons or cyclic oxygen-containing organic compounds of 5-membered rings or 6-membered rings, etc. Can be used.

When the negative electrode active material is in powder form, the negative electrode may be prepared as follows. The negative electrode may be manufactured in the same manner as the positive electrode except that the negative electrode active material is used instead of the positive electrode active material. In the negative electrode active material composition, the conductive material, binder, and solvent may be the same as those used for the positive electrode.

For example, a negative electrode active material composition is prepared by mixing a negative electrode active material, a conductive material, a binder, and a solvent, and then 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 the material, the shape, the manufacturing method, and the like. For example, a copper foil having a thickness of 10 to 100 占 퐉, a copper perforated foil having a thickness of 10 to 100 占 퐉, a hole diameter of 0.1 to 10 mm, an expanded metal, a foamed metal plate and the like can be used. The anode current collector may be made of stainless steel, titanium, nickel or the like in addition to copper.

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

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

Manufacturing example  One

Polymethyl methacrylate was dissolved in acetonitrile to a concentration of 1 M to prepare a polymer-containing solution. Separately by dissolving Mg (ClO _{4) 2} in acetonitrile in a concentration of 1M to prepare a salt solution. The PMMA polymer-Mg ion conductor was synthesized by mixing the prepared polymer-containing solution and the salt solution.

Example  One

The solution containing the polymer ion conductor prepared in Preparation Example 1 was uniformly coated on a polyethylene film using a doctor blade. A polyethylene film was coated thereon and the magnesium ion conductive polymer membrane was hardened overnight at 80 캜.

Experimental Example  One

The magnesium ion conductivity of the magnesium ion conductive polymer membrane prepared in Example 1 was evaluated.

Specifically, as shown in Fig. 2, one of the cells (A) is immersed in an electrolytic solution prepared by dissolving a copper metal electrode in 1 M Cu (NO ₃ ) ₂ and 1 M Mg (ClO ₄ ) ₂ in water, The other electrode (B) was immersed in an electrolytic solution prepared by dissolving a zinc metal electrode in 1 M Zn (NO ₃ ) ₂ and 1 M Mg (ClO ₄ ) ₂ in water. The magnesium ion produced in Example 1 After the conductive polymer membrane was positioned, a galvanostatic current of 3 mA was applied for 20 hours so that the Zn electrode was oxidized and the Cu electrode was reduced.

After completion of the experiment, the two electrolyte solutions were subjected to elemental analysis by ICP. The results are shown in Table 1 below. At this time, Ba ion was also measured to confirm the reliability of the experiment.

(Unit: wt%) Mg Cu Zn Ba (Zn, Mg) solution 0.31 0.003 1.8 <0.0001 (Cu, Mg) solution 0.46 3.7 0.055 <0.0001

As a result, it can be confirmed that Cu and Zn ions are not mixed. From this, it can be seen that only the Mg ions migrated through the magnesium ion conductive membrane manufactured according to the present invention.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, Of the right.

Claims (11)

delete delete delete delete delete delete First and second polymer matrices facing each other; And
And a magnesium ion conductive polymer layer positioned between the first and second polymer matrices,
Wherein the magnesium ion conductive polymer layer comprises a polymer-magnesium ion conductor including a polymer and a magnesium salt,
The polymer may be selected from the group consisting of polyalkyl (meth) acrylates, polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoroethylene (HFP) , &Lt; / RTI &gt;
Wherein the polymer-magnesium ion conductor is contained in an amount of 0.1 to 10 wt% based on the total weight of the magnesium ion conductive polymer membrane. 8. The method of claim 7,
Wherein the first and second polymer matrices each independently comprise a polyolefin-based polymer. delete An electrochemical device comprising the magnesium ion conductive polymer membrane according to claim 7. A magnesium battery comprising the magnesium ion conductive polymer membrane according to claim 7.

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