KR20150143289A - Separator for metal air battery, metal air battery including the same, manufacturing method of separator for metal air battery and manufacturing method of metal air battery - Google Patents

Abstract

The present invention relates to a separator for a metal air battery, the metal air battery including the same, a method to manufacture a separator for the metal air battery, and a method to manufacture the metal air battery. The separator for the metal air battery comprises: a separator body; and a porous layer including a catalyst prepared on at least one surface of the separator body.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a separator for a metal air cell, a metal air cell including the separator, a method for manufacturing a separator for a metal air battery, and a method for manufacturing a metal air battery. METHOD OF METAL AIR BATTERY}

This specification claims the benefit of Korean Patent Application No. 10-2014-0072486 filed with the Korean Intellectual Property Office on Jun. 13, 2014, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a separator for a metal air cell, a metal air cell including the separator, a method for manufacturing a separator for a metal air battery, and a method for manufacturing a metal air battery.

BACKGROUND ART Batteries are widely used as means for supplying power to electronic devices. In particular, rechargeable batteries are currently affecting the entire industry including notebooks, mobile phones, and automobiles. Recently, a boom of a smart device is taking place, and since the most inconvenient time in actual use is the use time, development of a high capacity battery is required.

Research and development of metal air cells have been attempted as a technology capable of replacing metal batteries in accordance with these demands.

Hereinafter, lithium air cells will be mainly described, but other metal air cells also act on a similar principle.

Lithium-air batteries are lithium-metal batteries that use lithium and air as their cathode and anode materials, respectively. During the discharge, lithium metal in the cathode is oxidized and oxygen in the air of the anode is reduced so that chemical energy is converted into electrical energy. .

The lithium air battery includes an anode, a cathode, an electrolyte provided between the anode and the cathode, and a separator.

Among them, the separator has a great influence on the stability and performance of the lithium air cell, and a porous substrate having a fine pore structure has been used so as to exhibit a good permeability to electrolyte.

However, lithium dendrite generated due to incomplete charge / discharge reaches the anode through the pores of the separator, which may cause an internal short-circuit. Such short-circuiting of the battery due to the lithium dendrite is considered to be the biggest threat to ensure the stability of the battery.

Korean Patent Publication No. 10-2013-0001170

The present invention provides a separator for a metal air cell, a metal air cell including the separator, a method for manufacturing a separator for a metal air battery, and a method for manufacturing a metal air battery.

One embodiment of the present disclosure provides a separator for a metal air cell, comprising a separator body, and a porous layer comprising a catalyst provided on at least one side of the separator body.

Another embodiment of the present disclosure is directed to a positive electrode comprising: a positive electrode; cathode; And a separator for the metal air cell and an electrolyte disposed between the anode and the cathode.

In another embodiment, the catalyst comprises a material that facilitates an oxygen reduction reaction or an oxygen oxidation reaction.

Another embodiment of the present disclosure provides a method of manufacturing a separator for a metal air cell, comprising coating a composition comprising a catalyst on at least one side of the separator body.

Another embodiment of the present invention provides a method of manufacturing a metal air cell including the steps of assembling a separator for a positive electrode, a negative electrode, and the metal air battery, and injecting an electrolyte between the positive electrode and the negative electrode.

The separator for a metal air battery according to one embodiment of the present invention improves the reactivity of the battery and can prevent short-circuiting of the battery due to the metal dendrites.

Accordingly, the metal air battery including the separator may have an overvoltage drop and an improved cycle characteristic.

FIG. 1 illustrates a porous layer formed on a surface of a separator body according to an embodiment of the present invention. Referring to FIG.
Fig. 2 is a schematic view of a lithium air cell, which is an example of a metal air cell.
3 is a schematic view illustrating the structure of a metal air cell according to an embodiment of the present invention.
FIG. 4 is a graph showing charge / discharge curves of lithium air cells according to Examples and Comparative Examples. FIG.
5 is a graph showing changes in cycle life according to charging and discharging of lithium air cells according to Examples and Comparative Examples.

It should be noted that only the parts necessary for understanding the embodiments of the present invention will be described below, and the description of other parts will be omitted so as not to obscure the gist of the present invention.

Also, unless otherwise defined, all terms including the technical and scientific terms used herein may be used in a sense that is commonly understood by one of ordinary skill in the art to which this application belongs. Also, commonly used predefined terms are not ideally or excessively interpreted unless explicitly defined otherwise.

Hereinafter, the present invention will be described in more detail. However, the scope of the invention is not limited thereto.

According to one embodiment of the present invention, a separator for a metal air battery includes a separator body and a porous layer including a catalyst provided on at least one side of the separator body. The porous layer including the catalyst provided in the separator main body participates in the electrochemical reaction occurring on the electrode surface to reduce the overvoltage of the reaction, thereby improving the cycle life of the battery including the separator.

The separator body can be used without limitation, as long as it is used as a separation membrane for metal air cells in the art.

According to an embodiment of the present invention, the separator for a metal air battery is a separator for a lithium air battery.

According to one embodiment of the present disclosure, the separator body may be made of a porous substrate, wherein the porous substrate is selected from the group consisting of high density polyethylene, low density polyethylene, linear low density polyethylene, ultra high molecular weight polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, And at least one selected from the group consisting of an ester, a polyacetal, a polycarbonate, a polyimide, a polyamide, a polyether ketone, a polyether sulfone, a polyphenylene oxide, a polyphenylene sulfide and a polyethylene naphthalene / RTI > According to one embodiment of the present disclosure, a glass fiber series, polyethylene (PE), polypropylene (PP), or a copolymer of polyethylene and polypropylene may be used as the separator body.

In this specification, the catalyst means a material which is applied to control the reaction rate of charging or discharging of the metal air cell. For example, the catalyst may include an oxygen reduction reaction or an oxygen oxidation reaction promoting material. From the viewpoint that the catalyst facilitates the oxygen reduction reaction or the oxygen oxidation reaction, it is preferable that the porous layer containing the catalyst is provided on the surface of the separation membrane body facing the air electrode.

The catalyst may be in the form of particles, and the particles may be porous.

Examples of the catalyst include a metal or a metal oxide. As the metal that can be used as the catalyst, noble metals such as Au, Ag, Pt, Pd, Ir, Os, Rh and Ru can be used. As the metal oxide, Co ₃ O ₄ , Al ₂ O ₃ , MnO ₂ , Can be used. As the catalyst, a single substance may be used, or two or more substances may be used together.

Meanwhile, when the separation membrane is included in the lithium air cell, a noble metal catalyst such as Pt, Ag, and Ru can be used. In view of cost and the like, it is preferable to use metal oxides such as Co ₃ O ₄ and MnO ₂ .

When a metal or a metal oxide is used as a catalyst, a metal or a metal oxide has a high electron mobility to receive and release electrons, so that an oxygen reduction reaction (ORR) and an oxygen evolution reaction (OER) . Also, the kinetics of the reaction in the catalyst is rapid, increasing the overall reaction rate of the electrode.

According to one embodiment of the present disclosure, the porous layer further comprises a binder in addition to the catalyst. The binder serves to help organically link the catalyst.

According to one embodiment of the present disclosure, the binder has a weight mass ratio of less than 30% in the porous layer.

According to one embodiment of the present disclosure, the catalyst is included at 70 wt% or more based on the total weight of the porous layer.

According to one embodiment of the present invention, the specific surface area of the catalyst may be from 0.1 m ² / g to 100 m ² / g. According to another embodiment, the specific surface area of the catalyst may be from 1 m ² / g to 100 m ² / g.

According to one embodiment of the present disclosure, the thickness of the porous layer may be between 30 nm and 100 탆. Also, the thickness of the porous layer may be 1 탆 to 30 탆.

According to one embodiment of the present disclosure, the porosity of the porous layer may be at least 50%. In this case, the discharge capacity increases with the increase of the reaction area and the decomposition reaction of the reactant is easy.

The porosity of the porous layer may be 50% or more, and if necessary, the porosity of the porous layer may be 80% or more.

According to one embodiment of the present disclosure, the porous layer can be produced by coating a composition comprising a catalyst on at least one side of the membrane body. At this time, the composition may include a solvent in addition to the catalyst, and the kind of the solvent may be employed without limitation as long as it is known in the art. Non-limiting examples of the solvent include N-methyl-2-pyrrolidone (NMP). The composition may further include a binder as required, and a non-limiting example of the binder is polyvinylidene fluoride (PVdF).

The method of coating the composition is not particularly limited, and any method known in the art can be used. For example, a vacuum filtration method, a dipping method, a screen printing method, or the like may be used, but the present invention is not limited thereto.

Porosity can be imparted to the separator body when the composition is coated on the separator body by using porous particles, by using the viscosity of the composition, or by using an additive.

After the composition is coated on the separator main body, it may be dried at a temperature of 100 ° C or more and 150 ° C or less. The drying may be vacuum drying. When the temperature is less than 100 ° C, it is difficult to completely evaporate moisture, and residual moisture in the electrode may adversely affect electrode performance.

After the composition is coated on the separator main body, drying may be performed for 12 hours or more.

After the composition is coated on the separator main body, vacuum drying may be performed at a temperature of 100 ° C or more and 150 ° C or less for 12 hours or more.

Another embodiment of the present disclosure provides a metal air cell comprising the above-described separator for a metal air cell.

According to one embodiment of the present disclosure, the negative electrode active material of the metal air battery may be, but is not limited to, lithium, zinc, magnesium or aluminum.

According to one embodiment of the present invention, the metal air battery may be a lithium air battery.

Another embodiment provides a metal air secondary battery comprising the above-described separator for a metal air battery.

According to one embodiment of the present invention, the metal air secondary battery may be a lithium ion secondary battery.

A metal air cell according to an embodiment of the present disclosure may have a conventional configuration of a metal air battery, except that it includes a separator according to the above-described embodiments. For example, the metal air battery includes a positive electrode; cathode; And a separator provided between the anode and the cathode and an electrolyte. At this time, if a porous layer including a catalyst is provided only on one side of the separation membrane, it is preferable that the porous layer is disposed so as to face the anode (air electrode).

3 schematically shows a structure of a metal air cell according to an embodiment of the present invention.

The anode, the cathode, and the electrolyte may be those known in the art.

The cathode discharges metal ions upon discharge and can accommodate metal ions upon charging, and the anode reduces oxygen upon discharging and releases oxygen upon charging.

According to one embodiment of the present invention, the negative electrode may include a negative electrode active material selected from the group consisting of a lithium metal, a lithium metal-based alloy, a lithium compound, and a lithium intercalation material.

The lithium metal-based alloy may be an alloy of lithium and a metal selected from the group consisting of Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, .

The lithium compound is formed of a material capable of reacting with lithium ions to form a lithium-containing compound reversibly, and a material capable of reacting with lithium ions to form a lithium-containing compound is, for example, tin oxide, titanium nitrate, Or < / RTI >

The lithium insertion material means a material capable of reversibly intercalating or deintercalating lithium ions, for example, crystalline carbon, amorphous carbon, or a mixture thereof.

The thickness of the negative electrode is not particularly limited, but the thickness of the negative electrode may be 50 占 퐉 or more. The upper limit of the thickness of the negative electrode is not particularly limited, but it is preferably as thick as possible. However, considering the possibility of commercialization, the thickness of the negative electrode may be from 50 μm to 500 μm.

The anode uses oxygen as an active material, and a conductive material can be used as the anode.

According to one embodiment of the present disclosure, the conductive material is porous.

The anode may be made of a porous carbon-based material, a metallic conductive material, an organic conductive material, or the like, but is not limited thereto, and any material having porosity and conductivity may be used without limitation. The carbon-based material may be, for example, carbon black, graphite, carbon fibers, graphene, activated carbon, and the like. As the metallic conductive material, metal fiber, metal mesh or the like may be used, and metallic powder such as copper, silver, aluminum, nickel and the like may be included. As the organic conductive material, a polyphenylene derivative or the like can be used. The conductive materials may be used alone or in combination.

According to one embodiment of the present disclosure, the anode may further include a binder. The binder may include a thermosetting resin or a thermoplastic resin. For example, polyethylene, polypropylene, polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, propylene-tetrafluoroethylene copolymer, ethylene-acrylic acid copolymer, etc. may be used alone or in combination But is not limited thereto.

The thickness of the positive electrode is not particularly limited, but the thickness of the positive electrode may be 10 탆 to 100 탆. Specifically, the thickness of the anode may be 20 占 퐉 to 60 占 퐉.

According to one embodiment of the present disclosure, the electrolyte is a non-aqueous electrolyte comprising an ionizable lithium salt and an organic solvent.

For example, the solvent of the non-aqueous electrolyte is selected from the group consisting of carbonates such as ethylene carbonate (EC) and propylene carbonate (PC), chain carbonates such as diethyl carbonate, ethers such as 1,2-dioxane, nitriles such as acetonitrile And amides may be used, but the present invention is not limited thereto. One or more of these may be used in combination.

Examples of the lithium salt include LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ , LiN (SO ₂ C ₂ F ₅ ) ₂ , Li (CF ₃ SO ₂ ) ₂ N, LiC ₄ F ₉ SO ₃ , LiClO ₄ , _{LiAlO 2, LiAlCl 4, LiF,} LiBr, LiCl, LiI , and _{LiB (C 2 O 4) 2} , LiCF 3 SO 3, LiN (SO 2 CF 3) 2 (Li-TFSI), LiN (SO 2 C 2 F 5 ) ₂ and LiC (SO ₂ CF _3), but it may use one or two or more selected from the group consisting of _3, and the like. The concentration of the lithium salt may be in the range of 0.1 to 2.0 M. When the concentration of the lithium salt is within the above range, the electrolyte has appropriate conductivity and viscosity, and therefore, it can exhibit excellent electrolyte performance, and lithium ions can effectively move.

The shape of the metal air cell is not limited, and may be, for example, a coin shape, a flat plate shape, a cylindrical shape, a horn shape, a button shape, a sheet shape or a laminate shape. It is also possible to apply it to a large-sized battery such as an electric automobile.

The metal air cell can be used for both metal primary batteries and metal secondary batteries. In addition, the present invention can be applied to a large-sized battery for use in electric vehicles and the like.

Another embodiment of the present disclosure provides a method of manufacturing a separator for a metal air cell as described above, comprising coating a composition comprising a catalyst on at least one side of the separator body.

According to another aspect of the present invention, there is provided a method of manufacturing a metal air cell including the steps of assembling the separator for a metal air battery and injecting an electrolyte between the anode and the cathode.

Hereinafter, the present invention will be described in detail with reference to examples and comparative examples. However, the scope of the present specification is not limited to the above-described embodiments.

<Examples>

1. Preparation of membrane

The catalyst MnO ₂ (Sigma Aldrich) having a specific surface area of 1 m ² / g to 10 m ² / g and a binder polyvinylidene fluoride (PVdF) were mixed in a weight ratio (wt.%) Of 80:20, -2-pyrrolidone (NMP) was added in an amount of 10% based on the solid content to prepare a catalyst slurry. Thereafter, a catalyst slurry was coated on one surface of a glass fiber (G / F) separation membrane (Whatman) to coat the catalyst slurry by a doctor blade coating method to form a uniform film and dried in a 120 ° C vacuum oven for 12 hours to form a porous layer Was prepared. At this time, the porosity of the porous layer was 62%, and the thickness of the porous layer was 50 to 60 탆.

2. Production of cathode (cathode)

A Ketjen black 600JD carbon material and a binder polyvinylidene fluoride (PVdF) were mixed at a weight ratio (wt.%) Of 80:20, followed by addition of solvent N-methyl-2-pyrrolidone (NMP) A positive electrode slurry was prepared. Then, a cathode slurry was coated on a carbon paper (Toray TGP-H-030) punched with a diameter of 19 phi and dried in a vacuum oven at 120 캜 for 12 hours to prepare a cathode. The loading amount is 0.5 mg / cm ² , and the anode thickness is 20 탆.

3. Electrolyte and cathode

The electrolytic solution was prepared by mixing 1M LiTFSI electrolytic salt and tetraethylene glycol dimethyl ether (TEGDME) solvent and water treatment to have a water content of less than 10 ppm. In the case of the negative electrode, lithium metal having a thickness of 150 μm was used by tapping at a size of 16 phi.

<Comparative Example>

The same positive electrode, electrolyte, and negative electrode were used, except that the glass fiber (G / F) separator used in the examples was used without any treatment.

<Experimental Example>

The electrochemical experiments were carried out using a 2032 coin cell and a coin cell with a hole for introducing external oxygen was used. The experiment was carried out with a coin cell in a separate kit. Charging and discharging of the metal air battery was confirmed cell cycle (cycle) life by limiting the capacity of 1,000mAh / g _c, the current was applied to the 100 mAh / g _c. The voltage was limited in the 2 V to 4.5 V range.

As a result of charging / discharging the prepared coin cell, the charge / discharge curve as shown in Fig. 4 was obtained. 4, in the case of the initial charging / discharging curve, the charging / discharging curves of the comparative example and the comparative example did not show a large opening difference, and the comparative example was confirmed to have a slightly low charging overvoltage. However, as the cycle progresses, it can be seen that the initial heavy overvoltage of the embodiment is drastically lowered, and even in the case of the comparative example, the initial heavy overvoltage is slightly lowered. In all of the examples and comparative examples, it was confirmed that the cycle life was continuously progressed by the charge and discharge type as in the tenth cycle shown in FIG.

The cycle life of the coin cell fabricated according to Examples and Comparative Examples is shown in the graph of FIG. In the case of charging / discharging at a capacity of 1,000 mAh / g _c , the capacity maintenance was three times as high as that of the comparative example, and in the comparative example, capacity deterioration was constant, (= Charge capacity / discharge capacity x 100) was maintained at 100%.

As a result, it can be confirmed that the embodiment using the separation membrane including the porous layer including the catalyst exhibits the effect of lowering the overvoltage and improving the cycle life, compared with the case where the conventional glass fiber separation membrane is used without further treatment.

10: cathode
11: cathode collector
12: Negative electrode active layer
20: anode
21: anode collector
22: cathode active layer
30: Membrane

Claims (14)

Separator body, and
And a porous layer including a catalyst provided on at least one surface of the separator main body. The method according to claim 1,
Wherein the catalyst comprises an oxygen reduction reaction or an oxygen oxidation reaction promoting material. The method according to claim 1,
Wherein the catalyst comprises at least one selected from the group consisting of Au, Ag, Pt, Pd, Ir, Os, Rh, Ru, Co ₃ O ₄ , Al ₂ O ₃ and MnO ₂ . The method according to claim 1,
Wherein the porous layer further comprises a binder in addition to the catalyst. The method according to claim 1,
Wherein the content of the catalyst is 70 wt% or more based on the total weight of the porous layer. The separator for a metal air battery according to claim 1, wherein the specific surface area of the catalyst is 0.1 m ² / g to 100 m ² / g. The method according to claim 1,
Wherein the porosity of the porous layer is 50% or more. The method according to claim 1,
Wherein the porous layer has a thickness of 30 nm to 100 탆. The separator for a metal air battery according to any one of claims 1 to 8, wherein the separator for a metal air cell is a separator for a lithium air battery. anode; cathode; And a separator for a metal air cell and an electrolyte according to any one of claims 1 to 8 provided between the positive electrode and the negative electrode. The method of claim 10,
Wherein the porous layer of the separator is disposed to face the anode. 11. The metal air cell as claimed in claim 10, wherein the metal air cell is a lithium air battery. The method of any one of claims 1 to 8, comprising coating a composition comprising a catalyst on at least one side of the membrane body. An anode, a cathode, and a separator for a metal air battery according to any one of claims 1 to 8; And injecting an electrolyte between the anode and the cathode.

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