KR20190089775A - Secondary battery having positive electrode comprising organic acid metal salt - Google Patents

Abstract

Provided is a metal ion secondary battery. The metal ion secondary battery comprises: a positive electrode including a positive electrode active material capable of reverse insertion and detachment of active metal ions and an organic acid metal salt which is an organic acid salt of the active metal; a negative electrode having a negative electrode active material; and an electrolyte. The battery performance can be enhanced by enhancing an initial charge capacity of the metal ion secondary battery.

Description

[0001] The present invention relates to a secondary battery having a positive electrode containing a metal organic acid salt,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a secondary battery, and more particularly, to a next-generation secondary battery.

The secondary battery refers to a battery that can be charged repeatedly as well as discharged. In a typical lithium secondary battery of the secondary battery, lithium ions contained in the positive electrode active material are transferred to the negative electrode through the electrolyte and then inserted (filled) into the layered structure of the negative electrode active material. Then, lithium ions, which have been inserted into the layered structure of the negative electrode active material, It works through the principle of returning to the anode (discharging). Such a lithium secondary battery is currently commercialized and is being used as a small power source for a cellular phone, a notebook computer, and the like, and it is expected that the lithium secondary battery will also be usable as a large power source such as a hybrid car, and the demand is expected to increase.

However, the composite metal oxide, which is mainly used as a cathode active material in a lithium secondary battery, contains a rare metal element such as lithium and may not meet the increase in demand. Accordingly, a next-generation secondary battery using a metal having a rich and cheap supply as a cathode active material has been studied. As an example of such a next-generation secondary battery, there has been studied a sodium secondary battery using sodium ion, Korean Patent Laid-Open Publication No. 2012-0133300 discloses a sodium secondary battery using Na _x MnPO ₄ F (0 <x ≤ 2) Lt; / RTI &gt;

However, such a sodium secondary battery cathode active material generally has a low content of sodium in the crystal structure or a high content of inactive sodium. In this case, when the battery is composed of a full cell having no sodium ion source at the cathode, sufficient initial charge capacity can not be exhibited. Such a problem may also occur when another next-generation metal-ion secondary battery is configured as a full cell.

Accordingly, an object of the present invention is to provide a next generation metal ion secondary battery in which the initial charging capacity is greatly improved.

According to an aspect of the present invention, there is provided a metal ion secondary battery. The metal ion secondary battery includes: a cathode containing a cathode active material capable of reversibly intercalating and desorbing active metal ions and an organic acid metal salt as an organic acid salt of the active metal; A negative electrode having a negative electrode active material; And an electrolyte.

The active metal ion may be a sodium ion, a potassium ion, a zinc ion, or a magnesium ion. The negative electrode active material may be a carbon material. The metal organic acid salt may be a metal carboxylate salt which is a carboxylate salt of the active metal or a metal sulfonate salt which is a carboxylate salt of the active metal.

The metal polycarboxylate salt may be a metal aminopolycarboxylate salt represented by the following formula (1).

[Chemical Formula 1]

A - xMm ^+. (N-mx) H

Wherein A is an aminopolycarboxylate having 2 or 5 carboxyl groups, M is an active metal ion, Na, K, Zn, or Mg, m is an oxidation number of an active metal ion, N is 1 or 2, and n is 2 to 5 in terms of the number of carboxyl groups contained in the aminopolycarboxylate, and x is an integer of 1 to 5 It is an integer.

Wherein M is Na, K, Zn, or Mg, n is an integer of 1 to 4 when M is Na or K, and M is Zn or Mg N may be 1 or 2.

According to an aspect of the present invention, there is provided a metal ion secondary battery. The metal ion secondary battery includes an electrode containing an active material capable of reversibly intercalating and desorbing active metal ions and an organic acid metal salt as an organic acid salt of the active metal.

According to the present invention, the active metal ion contained in the metal organic acid salt can serve as a source of active metal ion during the initial charging process of the battery. In this case, the initial charge capacity of the metal ion secondary battery can be improved and the battery performance can be improved.

FIG. 1 is a cyclic voltammetry graph for a reverse battery according to Comparative Example A2.
FIG. 2 shows an X-ray diffraction (XRD) pattern of an anode according to Comparative Example A2 and an anode after it was fully charged by applying a voltage of 4.5 V to a battery according to Comparative Example A2.
FIG. 3 is a graph showing the results of FT-IR spectroscopy for positive electrodes after applying 3.83 V, 3.86 V, 4.2 V, and 4.5 V in the process of charging the electrode according to Comparative Example A3 and the electrode according to Comparative Example A3, IR pattern.
4 shows the charging / discharging curve for the half-cell according to Comparative Example A2 using the positive electrode according to Comparative Example A2.
Fig. 5 shows the charging / discharging curve for the half-cell according to Comparative Example A1 using the positive electrode according to Comparative Example A1.
FIG. 6 shows charge / discharge curves for a half-cell according to a half cell preparation example A1 using a cathode according to cathode production example A1.
FIG. 7 shows charging / discharging curves for the reversible batteries according to the examples A 1, A 2, and A 3 using the positive electrode according to the positive electrode manufacturing examples A 1, A 2, and A 3.
8 is a cyclic voltammetry graph for a half-cell according to the half-cell comparative example B2.
FIG. 9 shows SEM and EDS mapping results for the electrode (a) according to the anode comparison example B2 and the anode (b) after the full charge of the half-cell according to the comparator B2 of the comparator B2 having the anode as the anode.
10 shows a charge / discharge curve for a half-cell according to Comparative Example B2 using a positive electrode according to Comparative Example B2.
FIG. 11 is a graph showing the relationship between an open circuit voltage (OCV), 3.89 V, 3.92 V, 4.03 V, and 3.9 V in the process of charging a half-cell according to Comparative Example B3 comprising an anode according to Comparative Example B3, And an FT-IR pattern for anodes after applying 4.5V.
12 shows the charging / discharging curve for the half-cell according to Comparative Example B1 of the half-cell using the positive electrode according to Comparative Example B1 and the half-cell according to the half-cell preparation example B1 using the positive electrode according to the positive electrode manufacturing example B1.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. Like reference numerals designate like elements throughout the specification.

In this specification, the term " on top of another layer " means that not only these layers are directly in contact but also another layer (s) is located between these layers.

A metal ion secondary battery according to an embodiment of the present invention includes an anode, a cathode, and an electrolyte disposed therebetween. Such a secondary battery can perform a charging process in which metal ions move from the anode to an anode through an electrolyte and a discharging process in which metal ions move from the cathode to the anode through the electrolyte, .

In this embodiment, the active metal ion may be a sodium ion, a potassium ion, a zinc ion, or a magnesium ion. The metal ion secondary battery using the non-lithium metal ion as the active metal ion is also called a non-lithium secondary battery. However, the present invention is not limited to this, and the metal ion secondary battery according to this embodiment can be applied to a lithium ion secondary battery.

anode

The anode may have a cathode active material layer containing a cathode material. At this time, the cathode material may contain a cathode active material capable of reversible insertion and desorption of active metal ions and an organic acid metal salt, which is an organic acid salt of the active metal.

When the active metal ion is a sodium ion, the cathode active material may be a sodium transition metal oxide or a crystalline material containing no sodium. The sodium-free crystalline material may be, for example, phosphorus [beta] -FeOOH. Wherein the sodium transition metal oxide is at ^least _{one selected from the group} consisting of Na _x [M ¹ _{1 -yz} M ² _y M ³ _z ] O _{2 -α} A _α (0 <x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z <1, 0 ≦ 0.1, M ¹ , M ² and M ³ are Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nd, Mo, Tc, Ru, Rh, Pd, Pb, A, N, O, F, or S). As an example, Na _x FeO ₂ , Na _x MnO ₂ , Na _x NiO ₂ , Na _x CoO ₂ , Na _x CrO ₂ , Na _x Ni _0.5 Mn _0.5 O ₂ (0 <x? 1), and the like. As an example, x may be 0.4 to 0.7.

When the active metal ion is potassium ion, the cathode active material may be nickel hexacyanoferrate or copper hexacyanoferrate. In the case where the active metal ions are magnesium ions, the positive electrode active material is _{Mg x Mo 6 S 8-y} Se y (y = 0,1, or _{2), α-MnO 2,} MoS 2, WSe 2, TiS _2, or Lt; / RTI &gt; When the active metal ion is a zinc ion, the cathode active material may be? -MnO ₂ , Na _0.95 MnO ₂ , or NiOOH.

The metal organic acid salt may be a metal carboxylate salt which is a carboxylate salt of the active metal or a metal sulfonate salt which is a sulfonate salt of the active metal.

The metal carboxylate salt may be a metal polycarboxylate salt having a plurality of carboxylate groups and an active metal ion in one molecule. As an example, the metal polycarboxylate salt may be a metal aminopolycarboxylate salt represented by the following formula (1).

[Chemical Formula 1]

A - xMm ^+. (N-mx) H

In Formula 1, A may be an aminopolycarboxylate containing two or five carboxyl groups. M is an active metal ion, which can be Na, K, Zn, or Mg. m is an oxidation number of the active metal ion, and may be 1 or 2, depending on the kind of the active metal ion. n may be 2 to 5 as the number of carboxyl groups contained in the aminopolycarboxylate, and x may be an integer of 1 to 5 within the range of n-mx satisfying 0 or more.

Examples of the aminopolycarboxylate include ethylene diamine tetra acetate (EDTA), diethylene triamine penta acetate (DTPA), ethylene glycol-bis (2-aminoethylether) -N, N, N ' , IDA (2,2'-azanediyldiacetate), NTA (2,2 ', 2''-nitrilotriacetate), BAPTA (1,2-bis (o-aminophenoxy) ethane-N, N, N'N'-tetraacetate ), DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate), NOSA (2,2 ', 2 "- (1,4,7-triazanonane-1,4,7 -triyl) triacetate, Nicotianamine, EDDHA (2- [2- [2-Hydroxy-1- (2-hydroxyphenyl) -2-oxoethyl] amino] ethylamino] -2- (2-hydroxyphenyl) , But is not limited thereto.

For example, when the metal organic acid salt is EDTA-xM (x is 1 to 4 when M is Na or K, x is 1 to 2 when M is Zn or Mg) or the metal organic acid salt (Diethylene Triamine Pentacetic Acid) -nM (n is 1 to 5 when M is Na or K, and n is 1 or 2 when M is Zn or Mg). In one example, when the active metal ion is sodium, the metal carboxylate salt may be EDTA-4Na or DTPA-5Na. The active metal ion contained in the metal organic acid salt may serve as a source of active metal ions during the initial charging of the battery. In this case, the initial charge capacity of the metal ion secondary battery can be improved and the battery performance can be improved. The amount of the metal organic acid salt to be added may be 1 to 50 parts by weight, specifically 3 to 40 parts by weight, based on 100 parts by weight of the cathode active material, but is not limited thereto and varies depending on whether the cathode active material contains an active metal ion .

The cathode material may further include a conductive material. The conductive material may be a carbon material such as natural graphite, artificial graphite, coke, carbon black, carbon nanotube, and graphene. The conductive material may be contained in an amount of 2 to 20 parts by weight based on 100 parts by weight of the cathode active material.

The cathode material may further include a binder. The binder may be a thermoplastic resin such as polyvinylidene fluoride, polytetrafluoroethylene, tetrafluoroethylene, vinylidene fluoride copolymer, fluorine resin such as propylene hexafluoride, and / or a polyolefin resin such as polyethylene or polypropylene . &Lt; / RTI &gt; The binder may be contained in an amount of 2 to 20 parts by weight based on 100 parts by weight of the cathode active material.

The positive electrode material may be coated on the positive electrode collector to form a positive electrode active material layer on the positive electrode collector. The positive electrode current collector may be a conductive material such as Al, Ni, or stainless steel. The positive electrode material may be applied on the positive electrode collector by a method such as a pressing method using a paste or an organic solvent, applying the paste on a current collector, and pressing and fixing the paste. Examples of the organic solvent include amine-based solvents such as N, N-dimethylaminopropylamine and diethyltriamine; Ethers such as ethylene oxide and tetrahydrofuran; Ketone type such as methyl ethyl ketone; Esters such as methyl acetate; Aprotic polar solvent such as dimethylacetamide, N-methyl-2-pyrrolidone and the like. The paste may be applied on the positive electrode current collector using, for example, a gravure coating method, a slit die coating method, a knife coating method, or a spray coating method.

cathode

The negative electrode material includes a negative electrode active material, which is a metal, a metal alloy, a metal oxide, a metal fluoride, a metal sulfide, and a natural graphite, which are capable of intercalating / deintercalating or converting the active metal ion Carbon material such as graphite, coke, carbon black, carbon nanotube, and graphene. However, when the secondary battery is composed of a full cell, the negative electrode may include a carbon material as a negative electrode active material.

The negative electrode material may further include a conductive material and / or a binder. At this time, the conductive material may be a carbon material such as natural graphite, artificial graphite, coke, carbon black, carbon nanotube, and graphene. The binder may be a thermoplastic resin such as polyvinylidene fluoride, polytetrafluoroethylene, tetrafluoroethylene, vinylidene fluoride copolymer, fluorine resin such as propylene hexafluoride, and / or a polyolefin resin such as polyethylene or polypropylene .

The negative electrode material may be coated on the negative electrode collector to form the negative electrode active material layer on the negative electrode collector.

Electrolyte

The electrolyte may be a mixture of a salt of the active metal ion and an organic solvent.

If the active metal ions are sodium, salts of the active metal ions _{NaClO 4, NaPF 6, NaAsF 6} , NaSbF 6, NaBF 4, NaCF 3 SO 3, NaN (SO 2 CF 3) 2, lower aliphatic carboxylic acid Sodium salt, NaAlCl ₄ , and the like, or a mixture of two or more thereof may be used. Among them, it is preferable to use an electrolyte containing fluorine. Examples of the organic solvent include propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, isopropyl methyl carbonate, vinylene carbonate, 4- Carbonates such as trifluoromethyl-1,3-dioxolan-2-one and 1,2-di (methoxycarbonyloxy) ethane; 1,2-dimethoxyethane, 1,3-dimethoxypropane, pentafluoropropylmethylether, 2,2,3,3-tetrafluoropropyldifluoromethylether, tetrahydrofuran, 2-methyltetrahydro Ethers such as furan; Esters such as methyl formate, methyl acetate and? -Butyrolactone; Nitriles such as acetonitrile and butyronitrile; Amides such as N, N-dimethylformamide and N, N-dimethylacetamide; Carbamates such as 3-methyl-2-oxazolidone; Sulfur-containing compounds such as sulfolane, dimethylsulfoxide, and 1,3-propanesultone; Or an organic solvent in which a fluorine-substituted group is further introduced may be used. When the active metal ion is zinc, the salt of the active metal ion may be ZnSO ₄ .7H ₂ O, ZnCl ₂ , Zn (NO ₃ ) ₂ .6H ₂ O, C ₂ F ₆ O ₆ S ₂ Zn, , Or two types may be used in combination. However, without being limited thereto, salts of active metal ions may use one of the known materials.

Alternatively, a solid electrolyte may be used. The solid electrolyte may be an organic solid electrolyte such as a polymer compound of a polyethylene oxide system, a polymer compound containing at least one or more of a polyorganosiloxane chain or a polyoxyalkylene chain. A so-called gel type electrolyte in which a non-aqueous electrolyte is supported on the polymer compound may also be used. On the other _{hand, Na 2 S-SiS 2,} Na 2 S-GeS 2, NaTi 2 (PO 4) 3, NaFe 2 (PO 4) 3, Na 2 (SO 4) 3, Fe 2 (SO 4) 2 (PO 4 ), Fe ₂ (MoO ₄ ) _3, and the like may be used. In some cases, the safety of the secondary battery can be enhanced by using these solid electrolytes. Further, the solid electrolyte may serve as a separator to be described later, in which case a separator may not be required.

Separator

A separator may be disposed between the anode and the cathode. Such a separator may be a material having a form such as a porous film made of a material such as a polyolefin resin such as polyethylene or polypropylene, a fluororesin or a nitrogen-containing aromatic polymer, a nonwoven fabric or a woven fabric. The thickness of the separator is preferably as thin as long as the mechanical strength is maintained in that the volume energy density of the battery is high and the internal resistance is small. The thickness of the separator may generally be about 5 to 200 mu m, and more specifically, 5 to 40 mu m.

Manufacturing Method of Secondary Battery

A secondary battery can be manufactured by stacking an anode, a separator, and a cathode in this order to form an electrode group, if necessary, the electrode group is rolled up and stored in a battery can, and the electrode group is impregnated with a non-aqueous electrolyte. Alternatively, the positive electrode, the solid electrolyte, and the negative electrode may be laminated to form an electrode group, and if necessary, the electrode group may be rolled up and stored in a battery can to manufacture a secondary battery.

Hereinafter, exemplary embodiments of the present invention will be described in order to facilitate understanding of the present invention. It should be understood, however, that the following examples are intended to aid in the understanding of the present invention and are not intended to limit the scope of the present invention.

[Experimental Examples; Examples]

&Lt; Preparation Examples &

Cathode Production Example A1: Production of cathode containing EDTA · 4Na

EDTA · 4Na (Ethylene Diamine Tetraacetic Acid Tetrasodium) as a cathode active material, carbon black as a conductive material, and PVdF (polyvinylidene fluoride) as a binder were mixed in a weight ratio of 60: 20: 10: (N-methyl-2-pyrrolidone), followed by mixing. The mixture was coated on an aluminum foil as a current collector to have a thickness of 100 μm to form a cathode active material layer on the aluminum foil. The electrode comprising the coated positive electrode active material layer was dried.

Anode Preparation Example A2: Preparation of positive electrode containing EDTA · 4Na

A positive electrode was prepared in the same manner as in Production Example A1 of Al cathode except that β-FeOOH, EDTA · 4Na, carbon black and PVdF were used in a weight ratio of 50: 30: 10: 10.

Cathode Preparation Example A3: Preparation of positive electrode containing EDTA · 4Na

A positive electrode was prepared in the same manner as in Production Example A1 of Al cathode except that the weight ratio of β-FeOOH, EDTA · 4Na, carbon black, and PVdF was used in a weight ratio of 40:40:10:10.

Bipolar Comparative Example A1

A cathode was prepared in the same manner as in Production Example A1 of Al cathode except that β-FeOOH, carbon black, and PVdF as cathode active materials except EDTA · 4Na were mixed in NMP at a weight ratio of 80:10:10.

Bipolar Comparative Example A2

A cathode was prepared in the same manner as in Production Example A1 of Al cathode except that EDTA · 4Na, carbon black, and PVdF except for β-FeOOH, which is a cathode active material, were mixed in NMP at a weight ratio of 80:10:10.

Bipolar Comparative Example A3

A cathode was prepared in the same manner as in Production Example A1 of Al cathode except that EDTA · 4Na, carbon black, and PVdF except for β-FeOOH as a cathode active material were mixed in NMP at a weight ratio of 89: 10: 1.

Examples of reversal electrode production examples A1, A2, and A3

A glass filter was used as a separator, and NaPF ₆ as an electrolyte and propylene carbonate (PC, 98 vol) as an organic solvent were used as the positive electrode according to any one of the anode production examples A1, A2, and A3, %) And fluoroethylene carbonate (FEC, 2vol.%) Were used to prepare an R2032-size half-cell.

Comparative Examples A1, A2, and A3

Anodes The same procedure as in Preparation Example A1 was used to prepare a semi-conductive paper, except that the positive electrode according to any one of Comparative Examples A1, A2, and A3 was used.

Anode Preparation Example B1: Preparation of cathode containing DTPA 占 5Na

The solvent in a weight ratio of 10: positive electrode active material in Na _0.44 MnO _2, a metal organic acid salt of DTPA · 5Na (Diethylene Triamine Pentaacetic Acid Pentasodium), conductive recognition of carbon black, and a binder of PVdF (polyvinylidene fluoride), 72: 8: 10 N-methyl-2-pyrrolidone (NMP), and the mixture was coated on an aluminum foil as a current collector to have a thickness of 100 μm to form a cathode active material layer on the aluminum foil. The electrode comprising the coated positive electrode active material layer was dried.

Bipolar Comparative Example B1

A cathode was prepared in the same manner as in Preparation Example B1, except that Na _0.44 MnO ₂ , a cathode active material except DTPA · 5Na, carbon black, and PVdF were mixed in NMP at a weight ratio of 80:10:10.

Bipolar Comparative Example B2

A positive electrode was prepared in the same manner as in Preparation Example B1, except that DTPA · 5Na, carbon black, and PVdF except for the Na _0.44 MnO ₂ cathode active material were mixed in NMP at a weight ratio of 80:10:10.

Bipolar Comparative Example B3

A positive electrode was prepared in the same manner as in Preparation Example B2, except that DTPA · 5Na, carbon black, and PVdF were mixed in NMP at a weight ratio of 87: 10: 3.

Example 1

A glass filter was used as a separator, and NaPF ₆ as an electrolyte and propylene carbonate (PC, 98 vol.%) As an organic solvent and fluoroethylene carbonate (PC) were used as an organic solvent, (FEC, 2 vol.%) Was used to prepare an R2032-size half-cell.

Comparative Examples B1, B2, and B3

A half cell was manufactured using the same method as in the case of the half cell preparation example B1, except that the positive electrode according to any one of the above cathode comparison examples B1, B2, and B3 was used.

The above Preparation Examples and Comparative Examples are summarized in the following table.

anode Half Anode Production Example A1 (weight ratio: 60: 20 : 10: 10) ,? -FeOOH, EDTA ? 4Na , carbon black, PVdF Half cell production example A1 Anode Production Example A2 (weight ratio: 50: 30 : 10: 10) ,? -FeOOH, EDTA ? 4Na , carbon black, PVdF Secondary battery production example A2 Anode Production Example A3 (weight ratio: 40: 40 : 10: 10) ,? -FeOOH, EDTA ? 4Na , carbon black, PVdF Half cell production example A3 Bipolar Comparative Example A1 ? -FeOOH, carbon black, PVdF (weight ratio: 80:10:10) Comparative Example A1 Bipolar Comparative Example A2 EDTA · 4Na , carbon black, PVdF (weight ratio: 80:10:10) Comparative Example A2 Bipolar Comparative Example A3 EDTA占N Na , carbon black, PVdF (weight ratio: 89 : 10: 1) Comparative Example A3 Anode Preparation Example B1 Na _0.44 MnO ₂ , DTPA · 5Na , carbon black, PVdF (weight ratio: 72: 8: 10: 10) Example 1 Bipolar Comparative Example B1 Na _0.44 MnO ₂ , carbon black, PVdF (weight ratio: 80:10:10) Comparative Example B1 Bipolar Comparative Example B2 DTPA · 5Na , carbon black, PVdF (weight ratio: 80:10:10) Comparative Example B2 Bipolar Comparative Example B3 DTPA 占) Na , carbon black, PVdF (weight ratio: 87 : 10: 3) Comparative Example B3

&Lt; Charging / discharging characteristics test of battery &

After the battery was stabilized for a day, the battery was charged at a current density of 30 mA / g and a voltage range of 1.1-4.3 V, and discharge was performed. However, we gave a downtime of about 10 minutes between charging and discharging.

FIG. 1 is a cyclic voltammetry graph for a reverse battery according to Comparative Example A2. This is a result obtained by cyclic voltammetry with a voltage of 1.5-4.3 V applied to the anode at 0.5 mV / s after stabilizing the battery according to Comparative Example A2 for one day.

Referring to FIG. 1, when the voltage applied to the electrode (working electrode, positive electrode) according to Comparative Example A2 is increased to about 4 V, the current flowing to the electrode according to Comparative Example A2 rapidly increases . However, in the process of reducing the applied voltage to 1.5 V, it can be seen that there is almost no change in the current flowing through the electrode according to the anode comparison example A2.

From this, it can be seen that EDTA · 4Na is rapidly oxidized when a voltage of about 4 V is applied to an electrode containing positive electrode active material A2, ie, an electrode containing EDTA · 4Na without containing β-FeOOH as a positive electrode active material. This may mean that Na ⁺ ions are desorbed from EDTA · 4Na. However, in the process of reducing the applied voltage to 1.5 V in the electrode according to the anode comparison example A2, no current peak appeared, and it was understood that the desorbed Na ⁺ ions could not bind again with the EDTA.

FIG. 2 shows an X-ray diffraction (XRD) pattern of an anode according to Comparative Example A2 and an anode after it was fully charged by applying a voltage of 4.5 V to a battery according to Comparative Example A2.

2, Fresh EDTA-4Na according to Comparative Example A2 shows very different XRD peaks. However, after charging (Charged EDTA-4Na), most of the existing peaks disappear, It can be confirmed that new peaks having a width are generated. Some of these new peaks have been identified as peaks for C ₃ N and some others that are not clearly identified (assumed to be EDTA-4Na in amorphous state). From this, it can be seen that EDTA-4Na completely decomposes and changes to carbon-related peaks after full charge.

FIG. 3 is a graph showing the results of FT-IR spectroscopy for positive electrodes after applying 3.83 V, 3.86 V, 4.2 V, and 4.5 V in the process of charging the electrode according to Comparative Example A3 and the electrode according to Comparative Example A3, IR pattern.

3, Fresh EDTA-4Na according to Comparative Example A3 contains EDTA · 4Na, carbon black, and PVdF in a weight ratio of 89: 10: 1. The peak of the FT-IR pattern Can be estimated to be mainly due to EDTA · 4Na. However, when 3.83 V (1 step) is applied to this electrode, the peaks disappear gradually and disappear completely after 3.86 V (2 step) is applied. From this, it can be confirmed once again that EDTA-4Na is decomposed in the charging process and completely decomposed after complete charging.

4 shows the charging / discharging curve for the half-cell according to Comparative Example A2 using the positive electrode according to Comparative Example A2.

Referring to FIG. 4, the reversed battery according to Comparative Example A2 showed a charging capacity of about 430 mAh / g in the first cycle of charging, but the discharge capacity was insignificant. Thus, charging in the second cycle And the discharge did not occur.

Referring to FIGS. 1 and 4 simultaneously, the anode according to Comparative Example A2, that is, the cathode containing EDTA · 4Na without containing β-FeOOH as the cathode active material sufficiently supplies Na ⁺ ions during the charging process, It can be seen that it does not absorb the supplied Na ⁺ ions again because it contains no active material.

Fig. 5 shows the charging / discharging curve for the half-cell according to Comparative Example A1 using the positive electrode according to Comparative Example A1.

Referring to FIG. 5, a battery having an anode containing β-FeOOH, which is a cathode active material without EDTA · 4Na, exhibits an initial charge capacity of about 4 mAh / g due to insufficient charging in the first cycle . This was understood to be due to the absence of a sodium ion source in the anode. On the other hand, the battery exhibited a discharge capacity of about 180 mAh / g, which was understood to be due to the supply of sodium ions from the negative electrode, which is a sodium metal.

FIG. 6 shows charge / discharge curves for a half-cell according to a half cell preparation example A1 using a cathode according to cathode production example A1.

Referring to FIG. 6, a battery having a positive electrode containing β-FeOOH as a positive electrode active material and containing an EDTA · 4Na was sufficiently charged in the first cycle to exhibit a charge capacity of about 109 mAh / g and a charge capacity of about 200 mAh / The discharge capacity of the discharge cell. Comparing this with the result according to FIG. 5, it can be seen that the initial discharge capacity was increased slightly in addition to the large increase in the initial charge capacity. It was assumed that EDTA · 4Na served as a source of Na + ions during the charging process.

FIG. 7 shows charging / discharging curves for the reversible batteries according to the examples A 1, A 2, and A 3 using the positive electrode according to the positive electrode manufacturing examples A 1, A 2, and A 3.

Referring to FIG. 7, it can be seen that as the amount of EDTA-4Na added increases, the capacity to be charged gradually increases. However, the amount of the electrode active material is reduced in the case of the positive electrode preparation example A3 using a large amount of additive, for example, 40 wt% or more of EDTA-4Na, so that the discharge capacity of the electrode material tends to be slightly reduced. From these results, it can be understood that the usable amount of the additive in the electrode is preferably less than about 40 wt% and preferably not more than 30 wt%.

8 is a cyclic voltammetry graph for a half-cell according to the half-cell comparative example B2. This is a result obtained by stabilizing the battery according to Comparative Example B2 for one day and then applying cyclic voltammetry with a voltage of 1.5-4.3 V at 0.2 mV / s to the anode.

Referring to FIG. 8, when the voltage applied to the electrode (working electrode, anode) according to the anode comparison example B2 is increased to about 3.61 V, the current flowing through the electrode according to the anode comparison example A2 rapidly As shown in FIG. However, in the process of reducing the applied voltage to 1.5 V, it can be seen that there is almost no change in the current flowing through the electrode according to the anode comparison example B2.

From this, it can be seen that DTPA · 5Na is rapidly oxidized when a voltage of about 3.6 V is applied to an electrode containing DTPA · 5Na without the electrode according to Comparative Example B2, ie, Na _0.44 MnO ₂ , which is a cathode active material have. This may mean that Na ⁺ ions are desorbed from DTPA · 5Na. However, in the process of decreasing the applied voltage to 1.5 V to the electrode according to the anode comparison example B2, no current peak appeared, and it was understood that the desorbed Na ⁺ ions could not bind again with DTPA.

FIG. 9 shows SEM and EDS mapping results for the electrode (a) according to the anode comparison example B2 and the anode (b) after the full charge of the half-cell according to the comparator B2 of the comparator B2 having the anode as the anode.

Referring to FIG. 9, it can be seen that a large amount of Na elements of DTPA-5Na was detected on the electrode (a) according to the anode comparative example B2. However, it can be confirmed that only a very small amount of Na elements (about 2% of (a)) was detected in the anode (b) after being completely charged. From this, it can be seen that when the electrode containing DTPA-5Na as a positive electrode additive is charged, Na ions are released from the anode.

10 shows a charge / discharge curve for a half-cell according to Comparative Example B2 using a positive electrode according to Comparative Example B2.

Referring to FIG. 10, the reversed battery according to Comparative Example B2 showed a charging capacity of about 375 mAh / g in the first cycle charging process, but the discharging capacity was insignificant. As a result, And the discharge did not occur.

8 and 10, the anode according to Comparative Example B2, that is, the anode containing DTPA-5Na without containing the cathode active material sufficiently supplies Na ⁺ ions during the charging process, but contains the cathode active material It is not possible to absorb the supplied Na ⁺ ions again.

FIG. 11 is a graph showing the relationship between an open circuit voltage (OCV), 3.89 V, 3.92 V, 4.03 V, and 3.9 V in the process of charging a half-cell according to Comparative Example B3 comprising an anode according to Comparative Example B3, And an FT-IR pattern for anodes after applying 4.5V.

11, the electrode according to Comparative Example B3 (OCV state, step 1) contains DTPA · 5Na, carbon black, and PVdF in a weight ratio of 87: 10: 3, and the FT- The peaks are presumably attributed mainly to DTPA · 5Na. However, when 3.89 V (step 2) and 3.92 V (step 3) are applied to this electrode, the peaks of the FT-IR pattern gradually disappear as the applied pressure increases. After the application of 4.03 V (step 4) You can see that it disappears completely. From this, it can be confirmed that DTPA · 5Na is decomposed in the charging process and completely decomposed after complete charging.

12 shows the charging / discharging curve for the half-cell according to Comparative Example B1 of the half-cell using the positive electrode according to Comparative Example B1 and the half-cell according to the half-cell preparation example B1 using the positive electrode according to the positive electrode manufacturing example B1.

Referring to FIG. 12, a battery (Comparative Battery B1, Bare Na _0.44 MnO ₂ ) having a positive electrode containing Na _0.44 MnO ₂ as a cathode active material without containing DTPA · 5Na, had a current density of about 81 mAh / g. &lt; / RTI &gt; The battery exhibited a discharge capacity of about 109 mAh / g, which was greater than the initial charge capacity, which was understood to be due to the supply of sodium ions from the negative electrode, which is a sodium metal.

On the other hand, a battery (Half Battery Production Example B1, Na _0.44 MnO ₂ / DTPA · 5Na 10 wt%) having a positive electrode containing DTPA · 5Na in addition to Na _0.44 MnO ₂ as a cathode active material was about 115 mAh / g and a discharge capacity of about 109 mAh / g. It was found that the initial charge capacity was greatly increased when compared with the battery (Comparative Example B1, Bare Na _0.44 MnO ₂ ) having a positive electrode containing Na _0.44 MnO ₂ as a cathode active material without containing DTPA · 5Na have. It was assumed that DTPA · 5Na served as a source of Na + ions during the charging process.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, This is possible.

Claims (13)

A positive electrode containing a positive electrode active material capable of reversible insertion and desorption of active metal ions and an organic acid metal salt as an organic acid salt of the active metal;
A negative electrode having a negative electrode active material; And
(JP) METAL ION SECONDARY BATTERY COMPRISING ELECTROLYTE. The method according to claim 1,
Wherein the active metal ion is a sodium ion, a potassium ion, a zinc ion, or a magnesium ion. The method according to claim 1,
Wherein the negative electrode active material is a carbon material. The method according to claim 1,
Wherein the metal organic acid salt is a metal carboxylate salt which is a carboxylate salt of the active metal or a metal sulfonate salt which is a carboxylate salt of the active metal. 5. The method of claim 4,
Wherein the metal polycarboxylate salt is a metal aminopolycarboxylate salt represented by the following Formula 1:
[Chemical Formula 1]
A - xMm ^+. (N-mx) H
In Formula 1,
A is an aminopolycarboxylate containing 2 or 5 carboxyl groups,
M is an active metal ion, Na, K, Zn, or Mg, m is an oxidation number of an active metal ion, 1 or 2 depending on the kind of the active metal ion,
n is 2 to 5 in terms of the number of carboxyl groups contained in the aminopolycarboxylate,
n-mx is an integer of 1 to 5 within a range satisfying 0 or more. 5. The method of claim 4,
Wherein M is Na, K, Zn, or Mg, n is 1 to 4 when M is Na or K, and M is Zn or Mg, wherein said metal organic acid salt is Ethylene Diamine Tetraacetic Acid and n is 1 to 2. &lt; RTI ID = 0.0 &gt; 5. The method of claim 4,
Wherein the metal organic acid salt is DTPA (Diethylene Triamine Pentacetic Acid) -nM wherein M is Na, K, Zn, or Mg, n is 1-5 when M is Na or K, n Lt; RTI ID = 0.0 &gt; 1 &lt; / RTI &gt; An electrode comprising an active material capable of reversible insertion and desorption of an active metal ion and an organic acid metal salt as an organic acid salt of the active metal. 9. The method of claim 8,
Wherein the active metal ion is a sodium ion, a potassium ion, a zinc ion, or a magnesium ion. 9. The method of claim 8,
Wherein the metal organic acid salt is a metal carboxylate salt which is a carboxylate salt of the active metal or a metal sulfonate salt which is a carboxylate salt of the active metal. 11. The method of claim 10,
Wherein the metal polycarboxylate salt is a metal aminopolycarboxylate salt represented by the following Formula 1:
[Chemical Formula 1]
A - xMm ^+. (N-mx) H
In Formula 1,
A is an aminopolycarboxylate containing 2 or 5 carboxyl groups,
M is an active metal ion, Na, K, Zn, or Mg, m is an oxidation number of an active metal ion, 1 or 2 depending on the kind of the active metal ion,
n is 2 to 5 in terms of the number of carboxyl groups contained in the aminopolycarboxylate,
n-mx is an integer of 1 to 5 within a range satisfying 0 or more. 9. The method of claim 8,
Wherein M is Na, K, Zn, or Mg, n is 1 to 4 when M is Na or K, and M is Zn or Mg, wherein said metal organic acid salt is Ethylene Diamine Tetraacetic Acid and n is 1 to 2. &lt; RTI ID = 0.0 &gt; 9. The method of claim 8,
Wherein the metal organic acid salt is DTPA (Diethylene Triamine Pentacetic Acid) -nM wherein M is Na, K, Zn, or Mg, n is 1-5 when M is Na or K, n Lt; RTI ID = 0.0 &gt; 1 &lt; / RTI &gt;

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