KR20120011322A - Lithium air battery - Google Patents

Abstract

PURPOSE: A lithium air battery is provided to restrain the decomposition of solid electrolyte due to discharging products, thereby improving the durability of an electrode, and having high energy density. CONSTITUTION: A lithium air battery comprises a negative electrode capable of charging and discharging lithium ions, a lithium ion conductive solid electrolyte membrane, aqueous electrolyte, and a positive electrode including oxygen as positive electrode active material. The aqueous electrolyte comprises lithium hydroxide and lithium halide. The lithium halide comprises one or more selected from a group consisting of LiF, LiCl, LiBr, and LiI. The lithium ion conductive solid electrolyte is formed between the positive electrode and the negative electrode, and formed on one surface of the negative electrode.

Description

Lithium air battery {Lithium air battery}

The present invention relates to a lithium air battery, and has a high energy density and a lithium air battery capable of maintaining electrical characteristics even for long time use.

It is known that a lithium air battery includes a cathode capable of occluding / discharging lithium ions, a cathode including an oxygen redox catalyst using oxygen in the air as a cathode active material, and a lithium ion conductive medium provided between the anode and the cathode. have.

The theoretical energy density of the lithium air battery is 3000 Wh / kg or more, which corresponds to approximately 10 times the energy density of the lithium ion battery. In addition, lithium air batteries are environmentally friendly and can provide improved safety than lithium ion batteries.

Such a lithium air battery may use an aqueous electrolyte and a non-aqueous electrolyte as the lithium ion conductive medium. The non-aqueous electrolyte may include an organic solvent including lithium salts, and the aqueous electrolyte may include water including a salt.

In one embodiment, a problem to be solved is to provide a lithium air battery having improved electrical characteristics by preventing damage to the electrode due to by-products generated in the electrolyte.

One aspect of the present invention for solving the above problems,

A negative electrode capable of storing / releasing lithium ions;

Lithium ion conductive solid electrolyte membrane;

Aqueous electrolytes; And

A positive electrode having oxygen as a positive electrode active material;

The aqueous electrolyte provides a lithium air battery containing lithium hydroxide and lithium halide.

According to one embodiment, the lithium halide may include one or more selected from the group consisting of lithium fluoride (LiF), lithium chloride (LiCl), recess bromide (LiBr) and lithium iodide (LiI).

According to one embodiment, the lithium ion conductive solid electrolyte membrane is interposed between the negative electrode and the positive electrode, is formed on one surface of the negative electrode.

According to one embodiment, the lithium ion conductive solid electrolyte membrane comprises a glass-ceramic solid electrolyte containing metal ions.

According to one embodiment, the lithium ion conductive solid electrolyte membrane may further comprise a polymer solid electrolyte.

According to one embodiment, the lithium ion conductive solid electrolyte membrane may include a stack of glass-ceramic solid electrolyte and polymer solid electrolyte.

According to one embodiment, the lithium halide may be included in the range of about 0.1% to about 100% of the saturation concentration with respect to the aqueous electrolyte.

According to one embodiment, the lithium halide may be included in the range of about 10% to 100% of the saturation concentration with respect to the aqueous electrolyte.

According to one embodiment, the aqueous electrolyte may include lithium chloride in an amount of about 1 part by weight to about 83 parts by weight based on 100 parts by weight of water.

According to one embodiment, the negative electrode may include a lithium metal, a lithium metal based alloy, or a lithium intercalating compound.

According to one embodiment, the anode may comprise a porous carbon-based material.

According to one embodiment, a separator may be further provided between the solid electrolyte membrane and the positive electrode.

According to one embodiment, the anode may further comprise a catalyst for the reduction of oxygen.

According to one embodiment, the aqueous electrolyte may be interposed between the lithium ion conductive solid electrolyte membrane and the positive electrode using oxygen as the positive electrode active material.

According to one embodiment, some or all of the aqueous electrolyte may be present in a form impregnated in the positive electrode.

According to one embodiment, the lithium air battery may further include a non-aqueous electrolyte between the negative electrode capable of storing / releasing lithium ions and a lithium ion conductive solid electrolyte membrane.

In a lithium air battery using an aqueous electrolyte, it is possible to suppress the decomposition of the solid electrolyte due to the discharge product to improve durability of the electrode, thereby improving the life characteristics of the lithium air battery having a high energy density.

1 is a photograph showing the surface of an untreated solid electrolyte membrane.
2 is a photograph showing the surface of a solid electrolyte membrane treated with lithium chloride.
3 is a photograph showing the surface of a solid electrolyte membrane treated with lithium hydroxide.
4 is a schematic view showing the structure of a lithium air battery according to one embodiment.
5 is a graph showing the electrical characteristics results of the cell measured in Experimental Example 2.

According to one embodiment, a lithium air battery includes a negative electrode capable of storing and releasing lithium ions; Lithium ion conductive solid electrolyte membrane; Aqueous electrolytes; And a cathode including oxygen as the cathode active material, wherein the aqueous electrolyte includes lithium hydroxide and lithium halide.

Lithium air cells may use an aqueous electrolyte and a non-aqueous electrolyte as electrolytes, and when an aqueous electrolyte is used, it exhibits a reaction mechanism such as the following scheme:

<Scheme 1>

4Li + O ₂ + 2H ₂ O-> 4LiOH E ^o = 3.45 V

That is, in the process where lithium generated from the negative electrode meets and oxidizes with oxygen of the positive electrode, water supplied from the aqueous electrolyte participates in the reaction, thereby producing lithium hydroxide.

The lithium hydroxide thus produced is present in a dissolved state in the aqueous electrolyte, and its concentration gradually increases in the aqueous electrolyte as the depth of discharge increases.

The hydroxyl group dissociated in the produced lithium hydroxide reacts with the metal ions contained in the lithium ion conductive solid electrolyte membrane used to protect the negative electrode, as shown in Formula 1, thereby damaging the structure of the electrolyte membrane.

<Formula 1>

In the formula, M represents a metal ion contained in the solid electrolyte membrane.

That is, the lithium ion conductive solid electrolyte membrane is formed on the surface of the negative electrode to serve as a protective film to protect the water contained in the aqueous electrolyte from directly reacting with the lithium contained in the negative electrode. Lithium hydroxide, which is a reaction product, causes the resistance of the solid electrolyte membrane to increase as its interfacial structure is changed and its components are changed. As a result, a decrease in conductivity results in deterioration of battery performance.

However, dissolving lithium halides in the aqueous electrolyte decreases the dissociation degree of LiOH, thereby decreasing the pH of the solution.

FIG. 1 shows the surface of lithium-aluminum-titanium-phosphate (LATP), which is a type of lithium ion conductive solid electrolyte membrane, and FIG. 2 shows the surface state of the solid electrolyte after being left in a 1M LiCl solution for 3 weeks. Shows the surface state after leaving the solid electrolyte for 3 weeks in 1M LiOH solution. In the LATP solid electrolyte left in the LiOH solution, a large amount of by-products were generated on the surface of the hydroxy group of LiOH with the metal ions of the solid electrolyte, but the by-product of the LATP solid electrolyte left in LiCl generated little by-product. It can be seen.

Therefore, it can be seen that decomposition of the lithium ion conductive solid electrolyte membrane can be suppressed by including the lithium halide in the aqueous electrolyte. As such, the lithium halide included in the aqueous electrolyte may include lithium fluoro (LiF), lithium chloride (LiCl), recess bromide (LiBr), and lithium iodide (LiI), which may be used alone or in combination of two or more. It can be mixed and used.

Since these lithium halides are present in a dissolved state in the aqueous electrolyte, they may be present at high concentrations, for example up to a saturated concentration. As an example of the saturation concentration, 0.27g may be dissolved in 100ml of water at 18 ° C for lithium fluoride, 83.2g may be dissolved in 100ml of water at 20 ° C for lithium chloride, and 20 ° C at 20 ° C for lithium bromide 166.7 g may be dissolved in 100 ml of water, and in the case of lithium iodide, 343 g may be dissolved in 100 ml of water at 20 ° C.

The lithium halide may be present, for example, in an amount of about 0.1% to about 100%, or about 10% to about 100% of the saturation concentration. For example, when lithium chloride is present at 50% of saturation concentration, it means that 41.6g is dissolved in 100ml of water at 20 ℃, and when 100% of saturation concentration is present at 100 ℃ of water. 83.2 g is dissolved.

Lithium chloride as an example of the lithium halide may be present in the aqueous electrolyte in an amount of about 1 part by weight to about 83 parts by weight per 100 parts by weight of water, and lithium fluoride may be present in an amount of about 0.01 to about 0.27 parts by weight per 100 parts by weight of water. Lithium bromide may be present in an amount of about 1 to about 166 parts by weight per 100 parts by weight of water, and lithium iodide may be present in an amount of about 1 to 433 parts by weight per 100 parts by weight of water.

The lithium ion conductive solid electrolyte membrane protected by the lithium halide contains metal ions and is located between the negative electrode and the positive electrode. In addition, since only lithium ions pass through, it serves as a protective film for protecting lithium contained in the negative electrode from water. As such a lithium ion conductive solid electrolyte membrane, an inorganic material containing lithium ion conductive glass, lithium ion conductive crystal (ceramic or glass-ceramic), or a mixture thereof can be exemplified. In consideration of chemical stability, the lithium ion conductive solid electrolyte membrane may include an oxide.

Since the high ion conductivity is obtained when the lithium ion conductive solid electrolyte membrane contains a large amount of lithium ion conductive crystals, for example, the lithium ion conductive crystal may be, for example, 50 wt% or more and 55 wt% based on the total weight of the solid electrolyte membrane. Or at least 55% by weight.

Examples of the lithium ion conductive crystals include a crystal having a perovskite structure having lithium ion conductivity such as Li ₃ N, LISICON, La _0.55 Li _0.35 TiO _3, and LiTi ₂ P ₃ O ₁₂ having a NASICON structure. Or glass-ceramic to precipitate these crystals can be used.

Examples of the lithium ion conductive crystal include Li _{1 + x + y} (Al, Ga) _x (Ti, Ge) _2-x Si _y P _3-y O ₁₂ (where O ≦ _x ≦ 1 and O ≦ y ≤ 1, for example, 0 ≤ x ≤ 0.4, 0 <y ≤ 0.6, or 0.1 ≤ x ≤ 0.3, 0.1 <y ≤ 0.4). When the crystal is a crystal that does not contain a grain boundary that inhibits ion conduction, the crystal is glass in terms of conductivity. For example, the glass-ceramic has almost no pores or grain boundaries that interfere with ion conduction, so that the glass-ceramic may have high ion conductivity and excellent chemical stability.

Examples of the lithium ion conductive glass-ceramic include lithium-aluminum-germanium-phosphate (LAGP), lithium-aluminum-titanium-phosphate (LATP), lithium-aluminum-titanium-silicon-phosphate (LATSP), and the like. have.

For example, when the mother glass has a Li ₂ O—Al ₂ O ₃ —TiO ₂ —SiO ₂ —P ₂ O ₅ system composition, and the crystallization is carried out by heat treatment of the glass, the main crystal phase at this time is Li _{1 + x. + y} Al _x Ti _2-x Si _y P _3-y O ₁₂ (0 ≦ x ≦ 1, O ≦ _y ≦ 1), where x and y are, for example, 0 ≦ x ≦ 0.4, or 0 < y ≦ 0.6, or 0.1 ≦ x ≦ 0.3, and 0.1 <y ≦ 0.4.

Here, the hole or grain boundary which impedes ion conduction is a hole which reduces the conductivity of the whole inorganic material containing lithium ion conductive crystal to the value of 1/10 or less with respect to the conductivity of the lithium ion conductive crystal itself in the said inorganic material. Or ion conductivity inhibiting substances such as grain boundaries.

The glass-ceramic is a material obtained by precipitating a crystal phase in a glass phase by heat-treating the glass. The glass-ceramic refers to a material composed of an amorphous solid and a crystal, and in addition, a material in which all the glass phases are phase-transformed into a crystal phase, for example, It may contain a material having a crystal amount (crystallinity) of 100% by mass. And even in the case of 100% crystallized material, in the case of glass-ceramic, there are almost no holes between the crystal grains and in the crystals.

Since the lithium ion conductive solid electrolyte membrane includes a large amount of the glass ceramic, and thus high ion conductivity can be obtained, the lithium ion conductive solid electrolyte membrane may include 80 wt% or more of lithium ion conductive glass ceramic in the lithium ion conductive solid electrolyte membrane. In order to obtain conductivity, the lithium ion conductive glass ceramic may be included in an amount of 85 wt% or more or 90 wt% or more.

The Li ₂ O component included in the glass-ceramic provides a Li ⁺ ion carrier and is a useful component for obtaining lithium ion conductivity. In order to obtain a good ion conductivity can be more easily illustrates the content of the Li ₂ O component is 12% or higher, 13% or more, or 14%. On the other hand, when the content of the Li ₂ O component is too large, the thermal stability of the glass is easily deteriorated, and the conductivity of the glass ceramic is also easily lowered. Therefore, the upper limit of the Li ₂ O component is 18%, 17% or 16%. It can have a value.

The Al ₂ O ₃ component included in the glass-ceramic can improve the thermal stability of the ^moglass , while Al ³⁺ ions are dissolved in the crystal phase, which is effective in improving the lithium ion conductivity. In order to obtain this effect more easily, it can be illustrated that the lower limit of the content of the Al ₂ O ₃ component is 5%, 5.5% or 6%. However, when the content of the Al ₂ O ₃ component exceeds 10%, the thermal stability of the glass tends to deteriorate, and the conductivity of the glass ceramic tends to be lowered, so the upper limit of the content of the Al ₂ O ₃ component is 10. It may be illustrated that it is%, 9.5%, or 9%.

The TiO ₂ component included in the glass-ceramic contributes to the formation of glass, is also a constituent of the crystalline phase, and is a useful component in the glass and the crystal. It can be illustrated that the lower limit of the content of the TiO ₂ component is 35%, 36%, or 37% for the purpose of glassization, and for the crystal phase to be precipitated from the glass as a main phase to obtain high ionic conductivity more easily. On the other hand, when the content of the TiO ₂ component is too large, the thermal stability of the glass tends to deteriorate easily, and the conductivity of the glass ceramic is also easily lowered, so the upper limit of the TiO ₂ component content is 45%, 43%, or 42. It can illustrate that it is%.

The SiO ₂ component included in the glass-ceramic can improve the meltability and thermal stability of the ^moglass , while Si ⁴⁺ ions are dissolved in the crystal phase, thereby contributing to the improvement of the lithium ion conductivity. In order to obtain this effect more fully, the lower limit of the SiO ₂ component content may be 1%, 2%, or 3%. However, when the content of the SiO ₂ component is too large, the conductivity tends to be lowered. Therefore, the upper limit of the content of the SiO ₂ component may be 10%, 8% or 7%.

The P ₂ O ₅ component contained in the glass-ceramic is a component useful for forming glass, and is also a constituent of the crystalline phase. Content is less than 30% of the P ₂ O ₅ component, there can be mentioned that it is difficult to screen the glass, the content is 30% the lower limit of the P _2O 5 ingredient, 32%, or 33% a. On the other hand, when the content of the P ₂ O ₅ component exceeds 40%, the crystal phase hardly precipitates from the glass, and it becomes difficult to obtain desired characteristics, so the upper limit of the content of the P ₂ O ₅ component is 40%, 39%. Or 38%.

In the case of the above composition, the molten glass can be cast to obtain glass easily, and the glass ceramic having the crystal phase obtained by heat treatment of the glass can have a high lithium ion conductivity of 1x10 ^-3 S · cm ^-1 . Will be.

In addition to the above composition, if a glass ceramic having a similar crystal structure is used, the Al ₂ O ₃ component may be replaced by the Ga ₂ O ₃ component, the TiO ₂ component may be replaced by the GeO ₂ component, or a part or the whole thereof may be substituted. . In addition, in the manufacture of the glass ceramic, other raw materials may be added in a small amount so as not to significantly deteriorate the ionic conductivity in order to lower the melting point or improve the stability of the glass.

The lithium ion conductive solid electrolyte membrane as described above may further include a polymer solid electrolyte component in addition to the glass-ceramic component. Such a polymer solid electrolyte is a lithium salt doped polyethylene oxide, the lithium salt is LiN (SO ₂ CF ₂ CF ₃ ) ₂ , LiBF ₄ , LiPF ₆ , LiSbF ₆ , LiAsF ₆ , LiClO ₄ , LiCF ₃ SO ₃ , LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ , LiC (SO ₂ CF ₃ ) ₃ , LiN (SO ₃ CF ₃ ) ₂ , LiC ₄ F ₉ SO ₃ , LiAlCl ₄ , and the like. It can be illustrated.

The polymer solid electrolyte may form a stack structure with the glass-ceramic, and the glass-ceramic may be interposed between the first polymer solid electrolyte and the second polymer solid electrolyte including the component.

The lithium ion conductive solid electrolyte membrane as described above is formed on one surface of the negative electrode capable of storing / discharging lithium ions to protect the negative electrode from reacting with the aqueous electrolyte and to pass only lithium ions.

As the negative electrode capable of storing / releasing lithium ions, a lithium metal, a lithium metal-based alloy, a lithium intercalating compound, or the like may be used. Examples of the lithium metal-based alloys include alloys of aluminum, tin, magnesium, indium, calcium, titanium, vanadium and lithium.

The lithium air battery according to one embodiment may further include a non-aqueous electrolyte between the negative electrode capable of storing and releasing lithium ions as described above and a lithium ion conductive solid electrolyte membrane, and the non-aqueous electrolyte may include the lithium air. The ions involved in the electrochemical reaction of the battery may serve as a medium for moving.

In addition, an organic solvent containing no water may be used as the non-aqueous electrolyte, and the non-aqueous organic solvent may be a carbonate-based, ester-based, ether-based, ketone-based, organosulfur solvent, or organic phosphorus ( organophosphorous solvents or aprotic solvents may be used. Examples of the carbonate solvent include dimethyl carbonate (DMC), diethyl carbonate (DEC), ethylmethyl carbonate (EMC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), and methylethyl carbonate. (MEC), ethylene carbonate (EC), propylene carbonate (PC), fluoroethylene carbonate (FEC), butylene carbonate (BC) and the like may be used, and the ester solvent may be methyl acetate, ethyl acetate, n- Propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, γ-butyrolactone, decanolide, valerolactone, mevalonolactone, caprolactone, and the like may be used. Can be. Examples of the ether solvent include dibutyl ether, tetraglyme, diglyme, dimethoxyethane, 2-methyltetrahydrofuran, and tetrahydrofuran. As the ketone solvent, cyclohexanone may be used have. In addition, methanesulfonyl chloride and p-trichloro-n-dichlorophosphoryl monophosphazene may be used as the organic sulfur-based and organophosphorus-based solvents. As a magnetic solvent, nitriles, such as R-CN (R is a C2-C20 linear, branched, or ring-shaped hydrocarbon group and may contain a double bond aromatic ring or an ether bond), dimethylformamide Amides, such as dioxolane sulfolanes, such as 1, 3- dioxolane, etc. can be used.

The non-aqueous organic solvents may be used singly or in combination of one or more. If one or more of the non-aqueous organic solvents are used in combination, the mixing ratio may be appropriately adjusted depending on the performance of the desired battery. .

The non-aqueous organic solvent may include a lithium salt, and the lithium salt may be dissolved in an organic solvent to serve as a source of lithium ions in the battery, for example, lithium between the negative electrode and the lithium ion conductive solid electrolyte membrane. It can serve to promote the movement of ions. 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 , LiN (C _x F _{2x + 1} SO ₂ ) (C _y F _{2y + 1} SO ₂ ), where x and y are natural numbers, LiF, LiBr, LiCl, LiI and LiB (C ₂ O ₄ ) ₂ (lithium bis (oxalato) borate (LiBOB) may be used one or two or more selected from the group consisting of. The concentration of the lithium salt may be used within the range of 0.1 to 2.0M. When the concentration of the salt is included in the above range, since the electrolyte has an appropriate conductivity and viscosity, it can exhibit excellent electrolyte performance, and lithium ions can move effectively.

The non-aqueous organic solvent may further include other metal salts in addition to lithium salts, for example, AlCl ₃ , MgCl ₂ , NaCl, KCl, NaBr, KBr, CaCl _2, and the like.

On the other hand, as the positive electrode having oxygen as the positive electrode active material, any material having porosity and conductivity can be used without limitation. For example, a carbon-based material having porosity can be used. As such carbon-based materials, carbon blacks, graphites, graphenes, activated carbons, carbon fibers and the like can be used.

A catalyst for reducing oxygen may be added to the anode, and the catalyst may be a noble metal catalyst such as platinum, gold, silver, palladium, ruthenium, rhodium, or osmium, manganese oxide, iron oxide, cobalt oxide, nickel oxide, or the like. The same oxide catalyst or organometallic catalyst such as cobalt phthalocyanine can be used.

It is also possible to arrange a separator between the anode and the cathode. Such a separator is not limited as long as it can withstand the range of use of the lithium air battery, and for example, polymer nonwoven fabric such as polypropylene nonwoven fabric or polyphenylene sulfide nonwoven fabric, and olefin resin such as polyethylene or polypropylene. The porous film of the can be illustrated, It is also possible to use 2 or more types together.

An aqueous electrolyte is present between a cathode formed on one surface of the lithium ion conductive solid electrolyte membrane and an anode including oxygen as an active material. The aqueous electrolyte includes water as a main solvent and lithium halides. In addition, depending on the reaction mechanism of the lithium air battery, lithium hydroxide is present with a varying concentration in the aqueous electrolyte.

Such an aqueous electrolyte is described as being interposed between the lithium ion conductive solid electrolyte membrane and the positive electrode, but it is also possible that some or all of the aqueous electrolyte is present in a form impregnated in the positive electrode structure due to the characteristics of the liquid rather than solid. When the separator is present, it may be present in the form impregnated with the separator.

As used herein, the term "air" is not limited to atmospheric air, and may include a combination of gases including oxygen, or pure oxygen gas. The broad definition of this term “air” can be applied to all applications, for example air cells, air anodes and the like.

The lithium air battery may be used in both a lithium primary battery and a lithium secondary battery. In addition, the shape is not specifically limited, For example, a coin type, a button type, a sheet type, lamination | stacking type, a cylindrical shape, a flat shape, a horn shape, etc. can be illustrated. The present invention can also be applied to large batteries used in electric vehicles.

An example of the said lithium air battery is shown typically in FIG. The lithium air battery 10 includes a positive electrode 13 having oxygen formed in the first current collector 12 as an active material, and a negative electrode 15 capable of storing / releasing lithium adjacent to the second current collector 14. An aqueous electrolyte 18 is interposed therebetween, and a lithium ion conductive solid electrolyte membrane 16 is formed on one surface of the negative electrode 15. A separator (not shown) may be disposed between the solid electrolyte membrane 16 and the anode 13.

Hereinafter, the present invention will be described in more detail with reference to Examples, but is not limited thereto.

Comparative Example 1

Lithium hydroxide was added to 5 M in 20 mL of water, and the pH of the solution was measured with a pH meter.

Example 1

After adding lithium chloride to 1M in 20mL of water, lithium hydroxide was added to 5M and the pH of the solution was measured with a pH meter.

Example 2

After adding lithium chloride to 3M in 20mL of water, lithium hydroxide was added to 5M and the pH of the solution was measured with a pH meter.

Example 3

After adding lithium chloride to 5M in 20mL of water, lithium hydroxide was added to 5M and the pH of the solution was measured with a pH meter.

Example 4

After adding lithium chloride to 8M in 20mL of water, lithium hydroxide was added to 5M and the pH of the solution was measured with a pH meter.

Example 5

After adding lithium chloride to 10M in 20mL of water, lithium hydroxide was added to 5M and the pH of the solution was measured with a pH meter.

Example 6

After adding lithium chloride to 15M in 20mL of water, lithium hydroxide was added to 5M and the pH of the solution was measured with a pH meter.

Example 7

After saturating lithium chloride in 20 mL of water, lithium hydroxide was added to 5 M and the pH of the solution was measured with a pH meter.

Experimental Example 1

The pH measurement results of Comparative Example 1 and Examples 1 to 7 are shown in Table 1 below.

division LiOH concentration (M) LiCl concentration (M) pH Comparative Example 1 5 0 14.03 Example 1 5 One 11.73 Example 2 5 3 11.37 Example 3 5 5 10.72 Example 4 5 8 9.96 Example 5 5 10 9.36 Example 6 5 15 8.55 Example 7 5 saturation 8.14

As can be seen in Table 1, it can be seen that the pH is lowered by increasing the concentration of LiCl in Examples 1 to 7. Through this result, it can be seen that the dissociation degree of 5M sodium hydroxide solution is lowered by the addition of LiCl.

Preparation Example 1 Lithium Ion Conductive Polymer Electrolyte Membrane

Reagents were reagent grade LiTFSI (Lithium bis (trifluoromethanesulfonyl) imide, Aldrich), PEO (Polyethylene oxide, molecular weight ~ 600,000, Aldrich) and ACN (Acetonitrile, Aldrich). 0.5 g of LiTFSI was dissolved in 50 mL acetonitrile, and 1.4 g of PEO was added thereto and stirred for 12 hours. The solution was then added to a PTFE dish, dried at 40 ^° C. for 24 hours under nitrogen gas, and vacuum dried at 150 ^° C. for 24 hours to obtain a lithium ion conductive polymer electrolyte membrane, which was then 1.5 cm × 1.5 cm in size. Cut.

Preparation Example 2: Protected Lithium Anode

Punch a 1cm x 1cm in the center of a 5cm x 5cm polypropylene coated aluminum film (200 ㎛) and close the hole with a 1.4cm x 1.4cm LATP film (150㎛ thick, Ohara corporation) using an adhesive. An aluminum film was made with a portion of LATP. New aluminum film of 5 cm x 5 cm, copper current collector (thickness 20 μm), lithium foil (1.4 cm x 1.4 cm, thickness 100 μm), lithium ion conductive polymer electrolyte membrane prepared in Preparation Example 1, aluminum prepared above The films were laminated and vacuum heated to obtain a protected lithium cathode of aluminum pouch type.

Example 8

Both lithium hydroxide and lithium chloride were saturated in 20 mL of water. A 1 cm x 1 cm sized LATP solid electrolyte membrane was immersed in the saturated solution, and left at 50 ° C. for 3 weeks.

Example 9

Lithium hydroxide was added to 0.01 M in 20 mL of water, and lithium chloride was saturated. A 1 cm x 1 cm sized LATP solid electrolyte membrane was immersed in the saturated solution, and left at 50 ° C. for 3 weeks.

Example 10

Lithium hydroxide was added to 0.001 M in 20 mL of water, and lithium chloride was saturated. A 1 cm x 1 cm sized LATP solid electrolyte membrane was immersed in the saturated solution, and left at 50 ° C. for 3 weeks.

Comparative Example 2

Lithium hydroxide was added at 0.01 M to 20 mL of water. 1 cm x 1 cm sized LATP solid electrolyte membrane was immersed in the solution, and left to stand at 50 ℃ for 3 weeks.

Comparative Example 3

Lithium hydroxide was added at 0.001M to 20 mL of water. 1 cm x 1 cm sized LATP solid electrolyte membrane was immersed in the solution, and left to stand at 50 ℃ for 3 weeks.

Comparative Example 4

Lithium hydroxide was added to 1 M in 20 mL of water. 1 cm x 1 cm sized LATP solid electrolyte membrane was immersed in the solution, and left to stand at 50 ℃ for 1 week.

Comparative Example 5

Lithium hydroxide was added to 1 M in 20 mL of water. The solution was immersed in a 1 cm x 1 cm size of LATP solid electrolyte membrane, and left for 6 months at 50 ℃.

Experimental Example 2

The resulting LATP films of Examples 8 to 10 and Comparative Examples 2 to 5 were washed with clean water and dried, and then coated with 100 nm thick gold on both sides by sputtering. Subsequently, an aluminum pouch type symmetrical cell using a copper foil as a current collector was prepared, the conductivity was measured at 25 ° C., and the results are shown in Table 2 below.

division LiOH concentration (M) LiCl concentration (M) Conductivity (25 ℃, Scm ^-1 ) Example 8 saturation saturation 2.28 X 10 ^-4 Example 9 0.01 saturation 2.30 X 10 ^-4 Example 10 0.001 saturation 2.30 X 10 ^-4 Comparative Example 2 0.01 0 1.40 X 10 ^-4 Comparative Example 3 0.001 0 1.76 X 10 ^-4 Comparative Example 4 One 0 2.30 X 10 ^-5 Comparative Example 5 One 0 5.20 X 10 ^-7 Untreated LATP - - 2.37 X 10 ^-4

As can be seen from the description of Table 2, in Comparative Examples 2 to 5 in which only lithium hydroxide is present, the conductivity of the solid electrolyte is decreased due to the reaction between the lithium hydroxide and the solid electrolyte membrane, but lithium chloride together with lithium hydroxide In the added Examples 8 to 10 it can be seen that the conductivity is almost reduced.

Experimental Example 3

The protected lithium negative electrode lithium obtained in Preparation Example 2 as the negative electrode, 1 M LiCl as the aqueous electrolyte, and platinum black (Pt-Black) as the positive electrode at a temperature of 60 ° C., 0.1, 0.2, 0.3, 0.4 and 0.5 mA / cm ² The potential difference over time for the lithium electrode at the current density of was measured and shown in FIG. 5. As shown in Fig. 5, it can be seen that a sufficient potential difference is obtained at various current densities.

Lithium air battery 10 First collector 12
Positive Electrode Using Oxygen as Active Material 13 Second Current Collector 14
Cathode that can occlude / discharge lithium 15
Aqueous Electrolyte 18
Lithium Ion Conductive Solid Electrolyte Membrane 16

Claims (16)

A cathode capable of storing and releasing lithium ions;
Lithium ion conductive solid electrolyte membrane;
Aqueous electrolytes; And
A positive electrode having oxygen as a positive electrode active material;
The lithium air battery, wherein the aqueous electrolyte includes lithium hydroxide and lithium halide. The method of claim 1,
Lithium air battery that the lithium halide comprises at least one selected from the group consisting of lithium fluoride (LiF), lithium chloride (LiCl), recess bromide (LiBr) and lithium iodide (LiI). The method of claim 1,
The lithium ion conductive solid electrolyte membrane is interposed between the negative electrode and the positive electrode, the lithium air battery is formed on one surface of the negative electrode. The method of claim 1,
And the lithium ion conductive solid electrolyte membrane is a glass-ceramic solid electrolyte containing metal ions. The method of claim 4, wherein
The lithium ion conductive solid electrolyte membrane further comprises a polymer solid electrolyte. The method of claim 1,
Wherein said lithium ion conductive solid electrolyte membrane comprises a laminate of a glass-ceramic solid electrolyte and a polymer solid electrolyte. The method of claim 1,
And the lithium halide is included in the range of about 0.1% to about 100% of the saturated concentration with respect to the aqueous electrolyte. The method of claim 1,
And the lithium halide is included in the range of about 10% to 100% of the saturation concentration with respect to the aqueous electrolyte. The method of claim 1,
Wherein said aqueous electrolyte comprises lithium chloride in an amount of about 1 part by weight to about 83 parts by weight based on 100 parts by weight of water. The method of claim 1,
Lithium air battery that the negative electrode comprises a lithium metal, lithium metal-based alloy, or a lithium intercalating compound (lithium intercalating compound). The method of claim 1,
Lithium air battery that the anode comprises a porous carbon-based material. The method of claim 1,
A lithium air battery further comprising a separator between the solid electrolyte membrane and the positive electrode. The method of claim 1,
Lithium air battery that the anode further comprises an oxygen reduction catalyst. The method of claim 1,
And the aqueous electrolyte is interposed between a lithium ion conductive solid electrolyte membrane and a positive electrode having oxygen as a positive electrode active material. The method of claim 1,
Part or all of the aqueous electrolyte is impregnated in the positive electrode lithium battery. The method of claim 1,
The lithium air battery further comprises a non-aqueous electrolyte between the negative electrode capable of storing and releasing lithium ions and a lithium ion conductive solid electrolyte membrane.

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