KR20130112315A - The method for charging of lithium air battery module - Google Patents

Abstract

PURPOSE: A charging method of a lithium air battery improves charging energy efficiency by reducing charging and discharging overvoltage. CONSTITUTION: A charging method of a lithium air battery comprises a step of charging a lithium air battery; and a step of discharging the lithium air battery by current at a standard current or less. The charging step comprises a step of charging the lithium air battery with constant current until the voltage of the lithium air battery reaches a standard voltage; and a step of charging the lithium air battery until the current of the lithium air battery reaches the standard current when the voltage of the lithium air battery reaches the standard voltage. [Reference numerals] (AA) Start; (BB,DD,FF,HH) No; (CC,EE,GG,II) Yes; (JJ) End; (S410) Connect external power device?; (S420) Charge with constant current; (S430) Applied voltage = standard voltage?; (S440) Charge with constant voltage; (S450) Applied current = standard current?; (S460) Discharging; (S470) Charging capacity <= standard capacity?; (S480) Complete charging

Description

The method for charging of lithium air battery module

The present disclosure relates to a lithium air battery and a charging method of a lithium air battery.

It is known that a lithium air battery has a cathode capable of intercalating / deintercalating lithium ions, a cathode containing oxygen as an anode active material and containing an oxidation-reduction catalyst of oxygen, and a lithium ion conductive medium between the anode and the cathode have.

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

In the conventional lithium air battery, polarization occurs due to high overvoltage during charge and discharge, and the energy efficiency during charge and discharge is significantly lower than that of a lithium ion battery.

Various catalysts were used to lower the charge / discharge overvoltage, but the decrease in charge / discharge overvoltage was not sufficient. Accordingly, there is a need for a method capable of improving charge and discharge energy efficiency by reducing the charge and discharge overvoltage.

The present disclosure provides a lithium air battery and a charging method thereof, in which energy efficiency is remarkably improved by reducing charge and discharge overvoltage.

A charging method of a lithium air battery according to one type of the present invention includes the steps of charging the lithium air battery; And discharging the lithium air battery at a current equal to or less than a reference value.

The reference value may be equal to or less than a minimum current when the lithium air battery discharges through a load.

In addition, the charging may include: charging at a constant current until the voltage of the lithium air battery reaches a reference voltage; And when the voltage of the lithium air battery reaches a reference voltage, charging until the current of the lithium air battery becomes a reference current at the reference voltage.

The reference value may be equal to or less than the reference current.

In addition, the reference value may be a value between the constant current and the reference current.

The reference value may be 0.5 mA / cm ² or less.

In addition, in the discharging step, the lithium air battery may be discharged until the capacity of the lithium air battery reaches a reference capacity.

The lithium air battery includes a cathode including lithium, a cathode using oxygen as a cathode active material, and an organic electrolyte, and the organic electrolyte includes an organic compound capable of absorbing and releasing electrons accompanying an electrochemical reaction. can do.

In addition, the organic compound may include a conjugated structure (conjugated system).

In addition, the organic compound may include an aromatic hydrocarbon ring.

In addition, the organic compound may include a quinone compound.

The organic compound is 1,2-benzoquinone, 1,4-benzoquinone, 1,2-naphthoquinone, 2,3-naphthoquinone, 1,4-naphthoquinone, 1,2-anthra Quinone, 2,3-anthraquinone, 1,4-anthraquinone, 9,10-anthraquinone, 1,2-pyrenedione, 4,5-pyrenedione, 1,2-coronedione, 1,2 , 5,6-coronetetranon, and 1,2,5,6,9,10-coronenehexanone chloranil (tetrachloro- p- benzoquinone), Lawson (Lawsone, 2-Hydroxy-1,4 -naphthoquinone), DDQ (2,3-Dichloro-5,6-dicyano-1,4-benzoquinone), tetrafluoro-1,4-benzoquinone, 7,7,8,8-tetracyanoquinomidimethane And 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane.

In addition, the organic electrolyte may include a salt of an alkali metal or an alkaline earth metal.

In addition, the negative electrode may include a lithium metal, a lithium metal based alloy, or a lithium intercalating compound.

The anode may also comprise a conductive material.

In addition, the conductive material may include a porous carbon-based material.

The disclosed lithium air battery includes an organic compound capable of absorbing and releasing electrons accompanying an electrochemical reaction, thereby reducing charge and discharge overvoltage of the lithium air battery and improving energy efficiency.

By pre-discharging when charging the disclosed lithium air battery, it is possible to secure an active interface during discharge.

1 is a view schematically showing a lithium air battery according to an embodiment of the present invention.
2 illustrates a structure of a lithium air battery according to another embodiment.
3 is a schematic view of a battery pack including a lithium air battery according to an embodiment of the present invention.
4 is a flowchart illustrating a charging method of a battery pack including a lithium air battery according to an exemplary embodiment of the present invention.
5 is a result of measuring the voltage gain in the absence of pre-discharge.
6 is a result of measuring the voltage gain when there is a pre-discharge.

Hereinafter, with reference to the accompanying drawings, it will be described in detail with respect to the disclosed lithium air battery. In the following drawings, the same reference numerals refer to the same components, the size of each component in the drawings may be exaggerated for clarity and convenience of description.

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.

1 is a view schematically showing a lithium air battery 10 according to an embodiment of the present invention. Referring to FIG. 1, a lithium air battery 10 includes an anode 11 including oxygen in air as a cathode active material and including a redox catalyst of oxygen, a cathode 12 capable of occluding / discharging lithium ions, and an anode ( 11) and a first electrolyte 13 which is a lithium ion conductive medium.

The positive electrode 11 is formed on a first current collector (not shown) and uses oxygen as an active material. In addition, the negative electrode 12 is formed on a second current collector (not shown) and can store / release lithium. As the current collector, a porous body such as a mesh or mesh shape may be used to rapidly diffuse oxygen, and porous metal plates such as stainless steel, nickel, and aluminum may be used, but the present invention is not limited thereto. Anything that can be used is possible. The current collector may be coated with an oxidation-resistant metal or alloy coating to prevent oxide.

On the other hand, a conductive material may be used as the positive electrode 11 using oxygen as the positive electrode active material. The conductive material may be porous. Therefore, any positive electrode active material can be used as long as it has the porosity and conductivity, for example, a carbon-based material having a porosity can be used. Examples of such carbon-based materials include carbon blacks, graphites, graphenes, activated carbons, and carbon fibers. As the cathode active material, a metal conductive material such as a metal fiber or a metal mesh may be used. Further, as the cathode active material, a metallic powder such as copper, silver, nickel, or aluminum may be used. Polyphenylene derivatives, and the like can be used. The conductive materials may be used alone or in combination.

Catalysts for oxidation / reduction of oxygen may be added to the anode 11, and as such catalysts, noble metal catalysts such as platinum, gold, silver, palladium, ruthenium, rhodium, and osmium, manganese oxide, iron oxide, and cobalt Oxide-based catalysts such as oxides, nickel oxides, and the like, or organometallic catalysts such as cobalt phthalocyanine may be used, but are not necessarily limited thereto, and may be used as long as they can be used as oxidation / reduction catalysts for oxygen in the art.

In addition, the catalyst may be supported on a carrier. The carrier may be an oxide, zeolite, clay mineral, carbon, or the like. The oxide may include one or more oxides such as alumina, silica, zirconium oxide, and titanium dioxide. Or an oxide comprising at least one metal selected from Ce, Pr, Sm, Eu, Tb, Tm, Yb, Sb, Bi, V, Cr, Mn, Fe, Co, Ni, Cu, . The carbon may be carbon blacks such as ketjen black, acetylene black, tan black, lamp black, graphite such as natural graphite, artificial graphite, expanded graphite, activated carbon, carbon fibers, etc., but is not necessarily limited thereto. Anything that can be used as a carrier in the field is possible.

The anode 11 may further include a binder. The binder may include a thermoplastic resin or a thermosetting resin. For example, it is possible to use polyethylene, polypropylene, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), styrene-butadiene rubber, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, vinylidene fluoride- Vinylidene fluoride-fluorotetrafluoroethylene copolymers, vinylidene fluoride-chlorotrifluoroethylene copolymers, ethylene-tetrafluoroethylene copolymers, polychlorotrifluoroethylene, vinylidene fluoride-pentafluoropropylene lower copolymer, propylene-tetrafluoroethylene Ethylene-chlorotrifluoroethylene copolymers, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymers, vinylidene fluoride-perfluoromethyl vinyl ether-tetrafluoroethylene copolymers, ethylene -Acrylic acid copolymer, and the like can be used alone or in combination, but the present invention is not limited thereto. Anything that can be used as a binder in the art is possible.

For example, the cathode 11 may be mixed with the oxygen oxidation / reduction catalyst, a conductive material, and a binder, and then, by adding an appropriate solvent to prepare a cathode slurry, and then apply and dry the surface of a current collector, or optionally improve electrode density. It can be prepared by compression molding on the current collector. In addition, the anode 11 may optionally include lithium oxide. Alternatively, the oxygen oxidation / reduction catalyst may be optionally omitted.

The negative electrode 12 capable of occluding and releasing lithium may include lithium metal, an alloy based on lithium metal, or a material capable of occluding and releasing Li, but the present invention is not limited thereto. The negative electrode 12 determines the capacity of the lithium air battery 10. The lithium metal-based alloy may be, for example, an alloy of aluminum, tin, magnesium, indium, calcium, germanium, antimony, bismuth, lead, and lithium.

The second electrolytes 25 and 13 may be aqueous electrolytes or non-aqueous electrolytes. Alternatively, the second electrolytes 25 and 13 may be formed by mixing the aqueous electrolyte and the non-aqueous electrolyte. In the case where the second electrolytes 25 and 13 are aqueous electrolytes, the reaction mechanism is the same as in Scheme 1 below.

[Reaction Scheme 1]

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

And,

When the second electrolyte 25, 13 is a non-aqueous electrolyte, the reaction mechanism may be represented as in Scheme 2 below.

[Reaction Scheme 2]

4Li + O ₂ ↔ 2Li ₂ O E ^o = 2.91V

2Li + O ₂ ↔ Li ₂ O ₂ E ^o = 3.10 V

The non-aqueous electrolyte may include an aprotic solvent. As the aprotic solvent, for example, a carbonate-based, ester-based, ether-based, ketone-based, amine-based or phosphine-based solvent may be used.

In addition, as an aprotic solvent, nitriles, such as R-CN (R is a C2-C20 linear, branched, or ring-shaped hydrocarbon group, and may include a double bond aromatic ring or an ether bond) , Amides such as dimethylformamide, and dioxolane sulfolanes such as 1,3-dioxolane and the like can also be used.

As the aprotic solvent, each solvent may be used alone or in combination of two or more solvents.

In addition, the non-aqueous electrolyte may include an ionic liquid. The ionic liquid in a straight-chain or branched substituted or unsubstituted ammonium ground, imidazolium, pyrrolidinium pyridinium, piperidinium cations and _{^{PF 6 -, BF 4 -,}} CF 3 SO 3 -, (CF 3 SO ^{_{2) 2 N -, (C}} 2 F 5 SO 2) 2 N -, (CN) 2 N - may be used are compounds composed of an anion, such as.

The non-aqueous electrolyte may include salts of alkali metals and / or alkaline earth metals. The salt of the alkali metal and / or alkaline earth metal may be dissolved in an organic solvent to serve as a source of alkali metal and / or alkaline earth metal ions in the battery 10. The salt of the alkali metal and / or alkaline earth metal, for example, may serve to promote the movement of alkali metal and / or alkaline earth metal ions between the positive electrode 11 and the negative electrode 12.

The salt anion contained in the non-aqueous electrolyte is _{^{PF 6 -, BF 4 -,}} SbF 6 -, AsF 6 -, C 4 F 9 SO 3 -, ClO 4 -, AlO 2 -, AlCl 4 -, C x F _{2x +1} SO ₃ ^- (where, x is a natural _{number), (C x F 2x +} 1 SO 2) (C y F 2y + 1 SO 2) N - ( wherein, x and y are natural numbers), and It may include at least one selected from the group consisting of halides.

2 illustrates a structure of a lithium air battery 20 according to another embodiment.

Referring to this, the anode 11, the cathode 12 disposed to be spaced apart from the cathode 12, the first electrolyte 13, the first electrolyte 13, and the cathode disposed between the anode 11 and the cathode 12. And a second electrolyte 25 disposed between the protective film 24 and the cathode 12. In FIG. 2, the cathode 12, the second electrolyte 25, and the protective film 24 may be collectively referred to as a protective cathode. Since the positive electrode 11, the negative electrode 12, and the first electrolyte 13 shown in FIG. 2 correspond to the positive electrode 11, the negative electrode 12, and the first electrolyte 13 shown in FIG. Omit.

The second electrolyte 25 may be a non-aqueous electrolyte.

The protective film 24 is at least one selected from an inorganic solid electrolyte membrane, a polymer solid electrolyte membrane, a gel polymer electrolyte, and a lithium ion conductive solid electrolyte membrane.

The inorganic solid electrolyte membrane may be, for example, Cu ₃ N, Li ₃ N, or LiPON.

Examples of the polymer solid electrolyte membrane include a polyethylene oxide membrane and the like.

The polymer solid electrolyte membrane may be prepared by mixing a lithium ion conductive polymer and a lithium salt, for example.

The lithium salt may be 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.

As the lithium ion conductive polymer, polyethylene oxide, polyacrylonitrile, polyester, or the like is used.

The lithium ion conductive solid electrolyte membrane may include at least one selected from the group consisting of an inorganic substance and a polymer solid electrolyte component.

 The lithium ion conductive solid electrolyte membrane may be a glass-ceramic solid electrolyte or a laminated structure of a glass-ceramic solid electrolyte and a polymer solid electrolyte. Such a lithium ion conductive solid electrolyte membrane will be described in more detail below.

As said lithium ion conductive solid electrolyte membrane, the inorganic substance containing lithium ion conductive glass, lithium ion conductive crystal (ceramic or glass-ceramic), or a mixture thereof can be illustrated. 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.

As the lithium ion conductive crystal, Li ₃ N, LISICON acids, La _{0 .55 0 .35} TiO ₃ Li LiTi having a lithium ion having a conductive perovskite (perovskite) crystal having a structure, such as a NASICON-type structure ₂ P ₃ O ₁₂ , 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 0 ≤ y ≤ 0.4). When the crystal is a crystal containing no crystal grain boundary which inhibits ion conduction, it 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 moglass has a Li ₂ O—Al ₂ O ₃ —TiO ₂ —SiO ₂ —P ₂ O ₅ system composition and is crystallized by heat treatment of the moglass, 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. x and y are specifically 0.1 ≦ x ≦ 0.3 and 0.1 ≦ y ≦ 0.4.

Here, the pores and grain boundaries that impede ion conduction are pores that reduce the conductivity of the entire inorganic material including lithium ion conductive crystals to a value of 1/10 or less with respect to the conductivity of the lithium ion conductive crystal itself in the 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 include a material having a crystallinity (crystallinity) of 100% by weight. And even in the case of 100% crystallized material, in the case of glass-ceramic, there are almost no pores 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 lithium ion conductive solid electrolyte membrane may further include a polymeric 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 membrane may form a laminate structure with the glass-ceramics, and the glass-ceramic may be interposed between the first polymer solid electrolyte containing the component and the second polymer solid electrolyte.

The lithium ion conductive solid electrolyte membrane may be used as a single layer or a multilayer membrane.

The operation principle of the lithium air battery 10, 20 is as follows. During discharge, lithium derived from the cathode 12 meets oxygen introduced from the anode 11 to form lithium oxide, and oxygen is reduced (oxygen reduction reaction: ORR). In addition, when charging, lithium oxide is reduced and oxygen is oxidized (oxygen evolution reaction: OER).

On the other hand, even after the lithium air battery 10, 20 is completely charged, undecomposed Li ₂ O ₂ or an electrolyte decomposition product surrounds the catalyst or electrochemically active interface of the positive electrode 11. Thus, an overvoltage is formed at the next discharge.

Therefore, the lithium air battery 10 and 20 according to the embodiment can increase the capacity and reduce the charge / discharge polarization (= charge voltage-discharge voltage) by adding an organic compound to the electrolyte.

As the organic compound in the organic electrolyte participates in the electrode reaction, the reaction area of the electrode reaction may be extended to the interfacial reaction between the electrode and the organic compound and the interfacial reaction between the organic compound and Li ₂ O ₂ .

In addition, since the properties of the interface change, the interface resistance also changes. Therefore, a remarkable increase in the electrode reaction rate, that is, a reversible electrode reaction becomes possible, compared to the conventional lithium air battery, the overvoltage during charge and discharge can be significantly reduced.

The organic compound may occlude and release electrons accompanying an electrochemical reaction and form a red-ox couple by oxidation and reduction reactions accompanying the occlusion and release of electrons. That is, it may be involved in the electron transfer of the electrode reaction while alternately repeating the oxidized state and the reduced state.

The organic compound and the organic electrolyte including the same may serve as a mediator that mediates some or all of electron transfer between the anode 11 and the lithium oxide in the discharge process. The lithium oxide may be Li ₂ O, Li ₂ O _{2 and the} like. Lithium oxide in the present specification means all kinds of lithium oxide including lithium peroxide.

The reduction potential of the organic compound is 2.5 to 3.5V with respect to lithium metal, and may be included in the charge / discharge voltage range of the lithium air battery 10 and 20. That is, the reduction and oxidation of the organic compound may occur in the discharge process of the lithium air battery 10, 20. The organic compound has a reduction potential within a charge and discharge voltage range of the lithium air battery 10, 20, for example, a voltage range of 2.5 to 3.5V with respect to lithium metal, and maintains a stable state in an organic electrolyte. All can be used regardless of chemical structure.

Hereinafter, the organic compound and the organic electrolyte including the same will be described in more detail by explaining the mechanism involved in the electron transfer in the charge and discharge process, which is intended to help the understanding of the present invention to limit the scope of the present invention to the scope of this description It is not intended to be.

For example, in the discharge process of the lithium air battery 10, 20, the organic compound receives electrons to the anode 11 at a lower voltage than lithium oxide and is first reduced. Subsequently, the reduced organic compound transfers electrons to oxygen molecules and primary lithium oxide dissolved in the electrolyte, and is oxidized to be regenerated into the original organic compound. Oxygen molecules and lithium oxides that receive electrons from the reduced organic compounds become oxygen reduction products or secondary lithium oxides. Subsequently, the regenerated organic compound receives electrons from the anode 11 and is reduced again. As such, the average discharge voltage at the time of discharge may be increased by reducing the moving distance between the oxygen supplied from the air and the produced primary lithium oxide electrode through the electron transfer.

In addition, the organic compound may play a role of stabilizing the interface of the lithium oxide through the interaction (interaction) weakly coordinated to the surface of the lithium oxide, such as Li ₂ O ₂ . For example, the terminal oxygen of 1,4-benzoquinone or the terminal cyano group of 7,7,8,8-tetracyanoquinodimethane may be weakly coordinated with lithium of Li ₂ O ₂ . As the interface of the lithium oxide is stabilized as described above, the average charging voltage during charging may be reduced.

The organic compound may include a double bond and / or a triple bond in the molecule. The double bond may include a double bond between carbon and carbon, a double bond between carbon and oxygen, a double bond between nitrogen and nitrogen, and the triple bond may include a triple bond between carbon and nitrogen. However, it is not necessarily limited to this range and may be any double bond and / or triple bond that can be used in the art.

In addition, the organic compound may include a conjugated system (conjugated system). The conjugated structure refers to a system in which double bonds and single bonds are alternately connected, or p-orbitals are continuously connected and overlapped by having p-orbitals available to contiguous atoms. The conjugated structure is a structure capable of deolocalization of electrons. Delocalization of the -electrons stabilizes the compound including the conjugated structure. Therefore, the complex compound including the ligand including the conjugated structure can maintain a stable state during oxidation and / or reduction. For example, benzene, thiophene, etc. are mentioned.

The organic compound may include a quinone compound. The quinone-based compound includes quinones and quinone derivatives.

The term "derivative" means that one or more substituents are linked to the compound or the like listed above, and the substituents are -F; -Cl; -Br; -CN; -NO2 -OH; C1-C60 alkyl group unsubstituted or substituted with -F, -Cl, -Br, -CN, -NO2 or -OH Unsubstituted or C1-C60 alkyl group, -F, -Cl, -Br, -CN, -NO2 or C5-C60 cycloalkyl group unsubstituted or substituted with -OH or C1-C60 alkyl group, C2-C60 heterocycloalkyl group unsubstituted or substituted with -F, -Cl, -Br, -CN, -NO2 or -OH C5-C60 aryl group and unsubstituted or C1-C60 alkyl group substituted with alkyl group, -F, -Cl, -Br, -CN, -NO2 or -OH, -F, -Cl, -Br, -CN, -NO2 Or one or more selected from the group consisting of C2-C60 heteroaryl groups substituted with -OH.

The aryl group is a monovalent group having an aromatic ring system, and may include two or more ring systems, and the two or more ring systems may exist in a bonded or fused form with each other. The heteroaryl group refers to a group in which at least one carbon in the aryl group is substituted with at least one selected from the group consisting of N, O, S, and P. Meanwhile, a cycloalkyl group refers to an alkyl group having a ring system, and the heterocycloalkyl group refers to a group in which at least one carbon of the cycloalkyl group is substituted with at least one selected from the group consisting of N, O, S and P. The fused aromatic ring or fused heteroaromatic ring may be present in fused form with the base ring and include two or more ring systems, and the two or more ring systems may be present in a bonded or fused form with each other. In addition, the heteroaromatic ring refers to a ring in which at least one carbon in the aromatic ring is substituted with at least one selected from the group consisting of N, O, S, and P.

Alternatively, a slight discharge may be performed after charging the lithium air battery 10 and 20 to activate an interfacial reaction of undecomposed Li ₂ O ₂ or an electrolyte decomposition product.

3 is a schematic diagram of a battery pack 100 including a lithium air battery according to an embodiment of the present invention.

Referring to FIG. 3, the battery pack 100 according to an embodiment of the present invention includes a battery unit 110 including one or more lithium air batteries 10 and 20 capable of charging and discharging, and the battery unit 110. External terminals (P +, P-) for electrically connecting an external power supply or a load, the control unit 120, the control unit 120 for controlling the charge and discharge of the battery unit 110 according to the state of charge of the battery unit 110 The charging and discharging control unit 130, the control unit 120 or the charge and discharge control unit 130 to control the electrical connection between the battery unit 110 and the external terminals (P +, P-) by receiving a signal from the In order to prevent the over current flowing through the battery unit 110, the battery unit 110 is positioned on the large current path of the battery unit 110, and electrical connection between the battery unit 110 and the external terminals P + and P− is performed. It may include a protection unit 140 for blocking, a discharge unit 150 for discharging the battery unit 110 by a specific current.

The battery unit 110 may include at least one lithium air battery 10 or 20 illustrated in FIG. 1 or 2. When there are a plurality of lithium air batteries 10, they may be connected in series, in parallel or in parallel.

The controller 120 measures the voltage of the battery unit 110 when the external power supply is electrically connected to the external terminals P + and P-, and charges the battery unit 110 when the measured voltage is smaller than the voltage at full charge. And controls the components of the battery pack so that the battery unit 110 is discharged when the load is electrically connected to the external terminal.

The charge / discharge control unit 130 may include a charge FET device (not shown) and a discharge FET device (not shown). Under the control of the controller 120, either the charge FET device or the discharge FET device is driven to allow the battery unit 110 to be charged or discharged. For example, the charging FET device may be driven when the battery unit 110 is charged, and the discharge FET device may be driven when the battery unit 110 is discharged.

The external terminals P + and P- are connected to the battery unit 110 in parallel, and include the positive terminal P + and the negative terminal P-. The external terminals P + and P- electrically connect the battery unit 110 to an external power supply or a load so that the battery unit 110 can perform charging or discharging. In more detail, when the external power supply device is connected to the external terminals P + and P-, the battery unit 110 performs charging, and when the load is connected to the external terminals P + and P-. The battery unit 110 performs a discharge.

4 is a flowchart illustrating a charging method of a battery pack 100 including a lithium air battery according to an exemplary embodiment of the present invention.

Referring to FIG. 4, when an external power supply device is connected to the external terminals P + and P−, the controller 120 charges the battery unit 110 in a constant current manner. For example, a constant rectification is applied to the battery unit 110 by increasing the voltage applied to the battery unit 110 stepwise or gradually. When the voltage applied to the battery unit 110 becomes the reference voltage, the controller 120 maintains the voltage applied to the battery unit 110 as the reference voltage until the current applied to the battery unit 110 becomes the reference current. The current applied to the battery unit 110 is reduced stepwise or gradually. Thus, when the current applied to the battery unit 110 becomes a reference current, the controller 120 discharges the battery unit 110.

When discharging the battery unit 110, the controller 120 may discharge the battery unit 110 with a current equal to or less than a reference value. The current below the reference value may be a constant current. Hereinafter, a current below the reference value is called a discharge current. The discharge current may be equal to or less than the constant current or less than the reference current when the battery unit 110 is charged. Alternatively, the discharge current may be a value between the constant current and the reference current when charging the battery unit 110. Alternatively, the discharge current may be equal to or less than the minimum current when the battery pack is discharged while the battery pack is connected to the load. For example, the discharge current may be 0.5 mA / cm ² or less.

Here, the discharge current may be performed while the external power supply is connected to the external terminals P + and P-. That is, when the current applied to the battery unit 110 becomes the reference current, the controller 120 stops driving of the charge FET device and drives driving of the discharge FET device. In the discharge FET device, the battery unit 110 is discharged by discharging the current in the battery unit 110 to the discharge unit. As described above, the discharge in a state where the load is not connected to the external terminals P + and P- is referred to as pre-discharge.

The discharge to the discharge current is performed until the charging capacity of the battery unit 110 becomes the reference capacity. Here, the reference capacity may be 99% to 90% of the charging capacity at the time of full charge when the battery unit 110 is fully charged. Alternatively, the discharge may be performed for a predetermined time to discharge the discharge current.

As such, when the current applied to the battery unit 110 becomes the reference current, the battery unit 110 is discharged with the discharge current to remove Li ₂ O ₂ , LiO _2, or an accessory attached to the active interface of the lithium known battery 10. As a result, overvoltage of the battery unit 110 can be prevented during discharge.

The present invention will be described in more detail by way of the following examples and comparative examples. However, the examples are provided to illustrate the present invention, and the scope of the present invention is not limited only to these examples.

 (Production of Organic Electrolyte)

Example 1

Tetramethylene glycol dimethyl ether (TEGDME) 1M Li (CF 3 SO 2) 2 N (Lithium bis (trifluoromethylsulphonyl) amine, LiTFSI) and 10mM 1,2-benzoquinone was added to the organic electrolyte was prepared.

Comparative Example 1

An organic electrolyte in which 1M Li (CF 3 SO 2) 2 N (Lithium bis (trifluoromethylsulphonyl) amine, LiTFSI) was dissolved in tetramethylene glycol dimethyl ether (TEGDME) was prepared.

Evaluation Example 1: Evaluation of Charge and Discharge Characteristics

The lithium air battery containing the electrolytes prepared in Example 1 and Comparative Example 1 at 60 ° C. at 1 atm was discharged to 2 V (vs. Li) at a constant current of 1 mA / cm 2 and then charged to 4.7 V at the same current. The insecticide capacity efficiency during charging and discharging is defined by the following equation.

&Quot; (1) &quot;

Insect capacity efficiency [%] = [charge capacity] / [discharge capacity] × 100

In the above formula, the charge capacity is the charge capacity at the 4.7V cutoff voltage at the time of charging, and the discharge capacity is the discharge capacity at the 2.0V cutoff voltage at the time of discharge.

As a result, the insecticide capacity efficiency and the discharge voltage of Example 1 were respectively 42% and 2.32V, and the insecticide capacity efficiency and the discharge voltage of Comparative Example 1 were 16% and 2.17V, respectively. Therefore, it can be seen that the charge capacity efficiency and the discharge voltage are significantly improved.

Next, look at the performance of a lithium known battery according to the presence of discharge after charging.

A tetraglyme solution of 1M LiTFSI was prepared to prepare a lithium air battery including a first electrolyte. In Example 2, the lithium air battery was discharged to 1.7 V (vs. Li) at a constant current of 1 mA / cm ² at 60 ° C. at 1 atmosphere. And thereby it was charged again at 4.2 V after charging to 4.2 V with a constant current of 1mA / cm ² with a constant voltage up to 0.2 mA / cm ² and then discharged at 0.2mA / cm ^2. On the contrary, in Comparative Example 2, the lithium air battery was discharged to 1.7 V (vs. Li) at a constant current of 1 mA / cm ² at 60 ° C. at 1 atmosphere. In addition, as to charge up to 4.2 V with a constant current of 1mA / cm ² Discharge of 0.2mA / cm ² does not perform. This charging and discharging was repeatedly performed.

5 is a result of measuring the voltage gain when there is no pre-discharge, Figure 6 is a result of measuring the voltage gain when there is a pre-discharge. As shown in FIG. 5, in Comparative Example 2 without pre-discharge, the voltage gain decreased as the number of charge / discharge increases. However, as shown in Fig. 6, in Example 2 with pre-discharge, the voltage gain was maintained at 2V or more even though the number of charge and discharge increased and the voltage gain decreased.

10, 20: lithium air battery cell
11: anode 12: cathode
13: first electrolyte 24: protective film
25: second electrolyte 100: battery pack
110: battery unit 120: control unit
130: charge and discharge control unit 140: protection unit
150: discharge part

Claims (16)

In the charging method of a lithium air battery,
Charging the lithium air battery; And
Discharging the lithium air battery at a current of less than the reference value; charging method of a lithium air battery comprising a. The method of claim 1,
The reference value is a charging method of a lithium air battery that is less than or equal to the minimum current when the lithium air battery discharges through a load. The method of claim 1,
The charging step,
Charging with a constant current until the voltage of the lithium air battery reaches a reference voltage; And
When the voltage of the lithium air battery reaches a reference voltage, charging until the current of the lithium air battery at the reference voltage becomes a reference current; charging method of a lithium air battery comprising a. The method of claim 3, wherein
And the reference value is less than the reference current. The method of claim 3, wherein
And the reference value is a value between the constant current and the reference current. The method of claim 1,
The reference value is a charging method of a lithium air battery is 0.5mA / cm ² or less. The method of claim 1,
The discharging step,
A charging method for a lithium air battery that discharges the lithium air battery until the capacity of the lithium air battery becomes a reference capacity. The method of claim 1,
The lithium air battery,
A negative electrode containing lithium, a positive electrode using oxygen as a positive electrode active material, and an organic electrolyte,
A charging method of a lithium air battery comprising an organic compound capable of occluding and releasing electrons accompanying an electrochemical reaction. The method of claim 8,
The organic compound charging method of a lithium air battery comprising a conjugated (conjugated system). The method of claim 8,
The organic compound is a charging method of a lithium air battery containing an aromatic hydrocarbon ring. The method of claim 8,
The organic compound is a charging method of a lithium air battery containing a quinone-based compound. The method of claim 8,
The organic compound is 1,2-benzoquinone, 1,4-benzoquinone, 1,2-naphthoquinone, 2,3-naphthoquinone, 1,4-naphthoquinone, 1,2-anthraquinone, 2 , 3-anthraquinone, 1,4-anthraquinone, 9,10-anthraquinone, 1,2-pyrenedione, 4,5-pyrenedione, 1,2-coronedione, 1,2,5, 6-Coronenetetranon, and 1,2,5,6,9,10-Coronenehexanone chloranil (chloranil, tetrachloro- p- benzoquinone), Lawson (Lawsone, 2-Hydroxy-1,4-naphthoquinone) , DDQ (2,3-Dichloro-5,6-dicyano-1,4-benzoquinone), tetrafluoro-1,4-benzoquinone, 7,7,8,8-tetracyanoquinomimethane, and 2 A method for charging a lithium air battery comprising at least one selected from the group consisting of 3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinomimethane. The method of claim 8,
The organic electrolyte is a charging method of a lithium air battery containing a salt of an alkali metal or alkaline earth metal. The method of claim 8,
The negative electrode is a lithium metal, a lithium metal-based alloy, or a lithium intercalating compound (lithium intercalating compound) method of charging a lithium air battery. The method of claim 8,
The anode is a charging method of a lithium air battery containing a conductive material. 16. The method of claim 15,
The conductive material is a charging method of a lithium air battery containing a porous carbon-based material.

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