KR20160032773A - Electrolyte solution comprising sulfur dioxide based gallium inorganic electrolyte and sodium-sulfur dioxide secondary battery having the same - Google Patents

Abstract

The present invention relates to an electrolyte solution including sulfur dioxide based gallium-based inorganic electrolyte and a sodium-sulfur dioxide (Na-SO_2) secondary battery having the same. The present invention is to increase general energy efficiency of the battery by improving extreme polarization generated when the sodium-sulfur dioxide secondary battery is tested. According to the present invention, the sodium-sulfur dioxide secondary battery includes a negative electrode made of an inorganic material, a positive electrode made of a carbon material, and sulfur dioxide-based inorganic electrolyte. The electrolyte includes sulfur dioxide based gallium-based inorganic electrolyte produced by injecting SO_2 gas into a mixture of NaX and GaX_3. X includes a halogen-based compound, saturated hydrocarbon (R) including C1-C20, unsaturated hydrocarbon (R) including C1-C20, and OR or SR.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic solution containing a sulfur-based gallium-based inorganic electrolyte and a sodium-sulfur dioxide secondary battery having the same,

The present invention relates to a sodium-based secondary battery, and more particularly sodium having suppressed polarization and electrolytic solution and him including a gallium-based mineral of sulfur dioxide based on having a more stable electrochemical characteristics as the electrolyte-sulfur (Na-SO ₂ ) Secondary battery.

As consumers' demands have changed due to digitization and high performance of electronic products, market demand is changing due to the development of batteries with high capacity due to thinness, light weight and high energy density. In addition, in order to cope with future energy and environmental problems, hybrid electric vehicles, electric vehicles, and fuel cell vehicles are being actively developed.

Lithium secondary batteries have been put to practical use as batteries that can be miniaturized and lightweight and can be recharged with a high capacity, and are used in portable electronic devices such as portable video cameras, mobile phones, and notebook personal computers and communication devices. The lithium secondary battery is composed of an anode, a cathode, and an electrolyte. The lithium secondary battery is used to transfer energy while reciprocally moving both electrodes, such as lithium ions discharged from the cathode active material through charging, This is possible.

Recently, research on sodium-based secondary batteries using sodium instead of lithium has been reexamined. Since sodium is abundant in resource reserves, secondary batteries can be manufactured at low cost if sodium secondary batteries can be manufactured instead of lithium.

As described above, sodium-based secondary batteries are useful, but conventional sodium metal-based secondary batteries such as NAS (Na-S battery) and ZEBRA (Na-NiCl ₂ battery) can not be used at room temperature, There is a problem in battery safety due to the use of liquid sodium and positive electrode active material in the battery and degradation of battery performance due to corrosion problem. On the other hand, recently, a sodium ion battery using sodium ion decontamination has been actively studied, but their energy density and lifetime characteristics are still poor. Therefore, there is a demand for a sodium-based secondary battery which is usable at room temperature and is excellent in energy density and lifetime characteristics.

In order to solve this problem, a sodium-sulfur dioxide (Na-SO ₂ ) secondary battery has been introduced. The sodium-sulfur dioxide secondary battery is a new battery system that can be used as a power source for large-capacity power storage by using a material at room temperature molten salt as an electrolyte, which greatly improves the low energy density of existing lithium secondary batteries.

In particular, the sodium-sulfur dioxide secondary battery is a new battery system with the advantage of lowering the price to less than one-half of that of existing lithium secondary batteries by using low-cost sodium.

However, the polarization due to the severe hysteresis phenomenon of the charge / discharge voltage of the sodium-sulfur dioxide secondary battery lowers the overall energy efficiency of the battery, resulting in a decrease in the overall performance of the battery. And sulfur dioxide is strong, so that it is not easy to desorb sulfur dioxide.

Korean Registered Patent No. 10-1254613 (Apr.

Accordingly, it is an object of the present invention to provide an electrolyte solution containing a sulfur dioxide-based gallium-based inorganic electrolyte capable of improving the overall energy efficiency of a battery by improving a serious polarization phenomenon occurring in the evaluation of a battery of a conventional sodium-sulfur dioxide secondary battery, - a sulfur dioxide secondary battery.

In order to achieve the above object, the present invention provides a sodium-sulfur dioxide secondary battery comprising an anode of an inorganic material containing sodium, a cathode of a carbonaceous material and an electrolyte. The electrolytic solution contains a sulfur dioxide-based gallium-based inorganic electrolyte prepared by injecting SO ₂ gas into a mixture of NaX and GaX ₃ . X is a halogen-containing compound, saturated hydrocarbon (R) having C1-C20, unsaturated hydrocarbon (R) having C1-C20, OR or SR.

In the sodium-sulfur dioxide secondary battery according to the present invention, the molar ratio of NaX and GaX ₃ may be 2.0: 1.0 to 1.0: 2.0.

In the sodium-sulfur dioxide secondary battery according to the present invention, the sulfur dioxide-based gallium-based inorganic electrolyte may be NaGaCl ₄ -xSO ₂ (1.5? X? 3.0).

In the sodium-sulfur dioxide secondary battery according to the present invention, the electrolyte may further include an aluminum-based inorganic electrolyte based on sulfur dioxide.

In the sodium-sulfur dioxide secondary battery according to the present invention, the sulfur-based aluminum-based inorganic electrolyte may be NaAlCl ₄ -xSO ₂ (1.5? X? 3.0).

Sodium According to an embodiment of the invention sulfur dioxide a secondary battery, the electrolytic solution may be a mixture of NaGaCl ₄ -xSO ₂ and NaAlCl ₄ -xSO _2.

The present invention also provides a sodium-sulfur dioxide secondary battery comprising an electrolyte containing a sulfur-dioxide-based gallium-based inorganic electrolyte prepared by injecting SO ₂ gas into a mixture of NaX and GaX ₃ .

The present invention also provides an electrolyte for a sodium-sulfur dioxide secondary battery comprising a sulfur dioxide-based gallium-based inorganic electrolyte prepared by injecting SO ₂ gas into a mixture of NaX and GaX ₃ . Wherein X comprises a halogen-based compound, saturated hydrocarbon (R) having C1-C20, unsaturated hydrocarbon (R) having C1-C20, OR or SR.

In the electrolyte for a sodium-sulfur dioxide secondary battery according to the present invention, the mixture of NaX and GaX ₃ may be NaGaX ₄ .

In the electrolyte for a sodium-sulfur dioxide secondary battery according to the present invention, the mixture of NaX and GaX ₃ may be NaGaCl ₄ mixed with NaCl and GaCl ₃ .

According to the present invention, by using a gallium-based inorganic electrolyte based on sulfur dioxide which can chelate sulfur dioxide with an electrolyte for a sodium-sulfur dioxide secondary battery and has weak binding force, It is possible to improve the overall energy efficiency of the battery by improving the polarization phenomenon.

1 is a view for explaining a sodium-sulfur dioxide secondary battery according to the present invention.
2 is a graph showing an evaluation of SO ₂ storage characteristics of a sodium-sulfur dioxide secondary battery according to Examples and Comparative Examples of the present invention.
3 is a graph showing the battery characteristics of a sodium-sulfur dioxide secondary battery according to Examples and Comparative Examples of the present invention.
4 is a graph showing the horizontal characteristics of a sodium-sulfur dioxide secondary battery according to Examples and Comparative Examples of the present invention.

In the following description, only parts necessary for understanding embodiments of the present invention will be described, and descriptions of other parts will be omitted to the extent that they do not disturb the gist of the present invention.

The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary meanings and the inventor is not limited to the meaning of the terms in order to describe his invention in the best way. It should be interpreted as meaning and concept consistent with the technical idea of the present invention. Therefore, the embodiments described in the present specification and the configurations shown in the drawings are merely preferred embodiments of the present invention, and are not intended to represent all of the technical ideas of the present invention, so that various equivalents And variations are possible.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view for explaining a sodium-sulfur dioxide secondary battery according to the present invention.

1, the sodium-sulfur dioxide secondary battery 100 of the present invention includes a carbon anode 2, a sodium-containing cathode 3, and a sulfur dioxide-based inorganic electrolyte 1, and further includes a case 4 . At this time, the sulfur dioxide-based inorganic electrolyte (1) contains a gallium-based inorganic electrolyte as a sulfur dioxide-based inorganic electrolyte.

Here, the anode 2 is made of a porous carbon material. This anode (2) provides a place where the oxidation-reduction reaction of the sulfur dioxide-based inorganic electrolyte takes place. The carbon material constituting the anode 2 may contain one or two or more different kinds of elements depending on the case. The term Lee Jong Won refers to nitrogen (N), oxygen (O), boron (B), fluorine (F), phosphorus (P), sulfur (S), and silicon (Si). The content of the hetero-element is 0 to 20 at%, preferably 5 to 15 at%. When the content of heteroatom is less than 5 at%, the effect of increasing the capacity by adding the heteroatom is insignificant. When the content of 15 atomic percent or more is exceeded, the electrical conductivity of the carbon material and the ease of electrode formation are decreased.

Further, the anode 2 may further contain metal chloride, metal fluoride or metal bromide in the porous carbon material.

Wherein the metal chloride is _{CuCl 2, CuCl, NiCl 2,} FeCl 2, FeCl 3, CoCl 2, MnCl 2, CrCl 2, CrCl 3, VCl 2, VCl 3, ZnCl 2, ZrCl 4, NbCl 5, MoCl 3, MoCl 5 , RuCl ₃ , RhCl ₃ , PdCl ₂ , AgCl, and CdCl ₂ . For example, the anode 2 may include a carbon material and CuCl ₂ in a certain weight ratio of the porosity. CuCl ₂ reacts with sodium ions while changing the oxidation number of Cu at the time of charging and discharging, so that the discharge product of Cu and NaCl is obtained, and CuCl ₂ is reversibly reversed upon charging. The content of the metal chloride in the anode 2 may be from 50 to 100 wt% or from 60 to 99 wt%, preferably from 70 to 95 wt% for the purpose of compounding additional elements for improving the characteristics of the anode 2.

Metal fluoride is _{CuF 2, CuF, NiF 2,} FeF 2, FeF 3, CoF 2, CoF 3, MnF 2, CrF 2, CrF 3, ZnF 2, ZrF 4, ZrF 2, TiF 4, TiF 3, NbF 5, AgF ₂ , SbF ₃ , GaF ₃ , and NbF ₅ . For example, the anode 2 may comprise a porous carbon material and a constant weight ratio of CuF ₂ . CuF ₂ reacts with sodium ions while changing the oxidation number of Cu at the time of charging and discharging, thereby obtaining discharge products of Cu and NaCl, and reversibly reformation of CuF ₂ upon charging. The content of the metal fluoride in the anode 2 may be 50 to 100 wt% or 60 to 99 wt%, preferably 70 to 95 wt% for the purpose of compounding additional elements for improving the characteristics of the anode 2.

And metal bromide is _{CuBr 2, CuBr, NiBr 2,} FeBr 2, FeBr 3, CoBr 2, MnBr 2, CrBr 2, ZnBr 2, ZrBr 4, ZrBr 2, TiBr 4, TiBr 3, NbBr 5, AgBr, SbBr 3 , GaBr ₃ , NbBr ₅ , BiBr ₃ , MoBr ₃ , SnBr ₂ , WBr ₆ and WBr ₅ . For example, the anode 2 may comprise a porous carbonaceous material and a constant weight ratio of CuBr ₂ . CuBr ₂ reacts with sodium ions while changing the oxidation number of Cu at the time of charging and discharging, thereby obtaining a discharge product of Cu and NaCl, and the CuBr ₂ is reversibly reversed upon charging. The content of the metal bromide in the anode 2 may be in the range of 50 to 100 wt% or 60 to 99 wt%, preferably 70 to 95 wt% in order to improve the properties of the anode 2, etc. .

The cathode 3 can be made of a sodium metal, an alloy containing sodium, an intermetallic compound containing sodium, a carbon material containing sodium, an inorganic material containing sodium, or the like. The inorganic material may include at least one of an oxide, a sulfide, a phosphide, a nitride, and a fluoride. The content of the cathode material in the cathode 3 may be 60 to 100 wt%.

A sulfur dioxide-based inorganic electrolyte (1) used as an electrolyte and an anode reaction active material is a gallium-based inorganic electrolyte (hereinafter referred to as a gallium-based inorganic electrolyte) capable of chelation but weakly binding to sulfur dioxide use.

Gallium inorganic electrolyte contains a NaX, GaX _3, and SO _2. Where X may be a ligand, for example, a variety of ligands including halogen compounds, saturated or unsaturated hydrocarbons (R), OR, SR, etc. having C1 to C20. Specifically, a ligand is ^{-COOH, -COO -, -CHO, -NH} 2, -SH, -OH, -SO 3 H, -SO 3 -, -C (= NH) -, -CONH 2, -CN, -CS ₂ H, -CS ₂ ^- , a halide group (-Cl, -F, -Br, etc.), a pyridine group, and a pyrazine group.

Wherein the molar ratio of NaX to GaX ₃ may be 2.0: 1.0 to 1.0: 2.0.

For example, the gallium-based inorganic electrolyte may be composed of NaGaCl ₄ (solute) and SO ₂ (solvent). NaGaCl ₄ -xSO ₂ can be prepared by injecting SO ₂ gas into a mixture of NaCl and GaCl ₃ (or a salt of NaGaCl ₄ alone).

The electrolyte of NaGaCl ₄ -xSO _{2 has} a molar ratio (x) of SO ₂ to NaGaCl ₄ of 0.5 to 10, preferably 1.5 to 3.0. When the SO ₂ content molar ratio (x) is lowered to less than 1.5, there is a problem that the electrolyte ion conductivity decreases, and when the molar ratio (x) exceeds 3.0, the vapor pressure of the electrolyte increases.

On the other hand, the gallium-based inorganic electrolyte can be used alone as the sulfur dioxide-based inorganic electrolyte (1), but it can be used together with other sulfur dioxide-based inorganic electrolytes. For example, in addition to NaGaCl ₄ used as a solute, NaAlCl ₄ , Na ₂ CuCl ₄ , Na ₂ MnCl ₄ , Na ₂ CoCl ₄ , Na ₂ NiCl ₄ , Na ₂ ZnCl ₄ and Na ₂ PdCl ₄ can be used together with NaGaCl ₄ . That is, NaGaCl ₄ and NaAlCl ₄ can be used together. In this case, they can be used as a mixture of NaGaCl ₄ -nSO ₂ and NaAlCl ₄ -nSO ₂ .

The case 4 may be provided between the anode 2 and the cathode 3 so as to surround the structure in which the sulfur dioxide-based inorganic electrolytic solution 1 is disposed. A signal line connected to the anode 2 and a signal line connected to the cathode 3 may be disposed on one side of the case 4. The shape and size of the case 4 may be determined according to the field to which the sodium-sulfur dioxide secondary battery 100 is applied. The material of the case 4 may be made of a nonconductive material. When the insulator for enclosing the positive electrode 2 and the negative electrode 3 is provided, the case 4 may also be formed of a conductive material.

The sodium-sulfur dioxide secondary battery 100 using the gallium-based inorganic electrolyte according to the present invention can be used at a temperature of 50 ° C to 300 ° C and a current of 0.001C to 1000C. The electrode density of the sodium-sulfur dioxide secondary battery 100 according to the present invention is 0.01 mg / cm ² to 100 mg / cm ² , and the electrolyte injection amount is 10 ug to 1 g. The sodium-sulfur dioxide secondary battery 100 according to the present invention may be manufactured in various forms such as various battery types such as a coin cell, a beaker cell, a pouch cell, a cylindrical cell, and a square cell.

In order to evaluate the characteristics of the sodium-sulfur dioxide secondary battery 100 using the gallium-based inorganic electrolyte according to the present invention, a gallium-based inorganic electrolyte was prepared as follows.

As an example, NaCl and GaCl ₃ were mixed at a ratio of 1.1: 1.0 mole, and SO ₂ gas was injected to prepare a gallium-based inorganic electrolyte.

As a comparative example, a sulfur dioxide-based aluminum-based inorganic electrolyte (hereinafter referred to as 'aluminum-based inorganic electrolyte') in which SO ₂ was injected was prepared by mixing NaCl and AlCl ₃ at a ratio of 1.1: 1.0.

The batteries according to Examples and Comparative Examples were produced using the sulfur dioxide-based inorganic electrolytes according to Examples and Comparative Examples as electrolytic solutions. An anode comprising a carbon material 80wt%, the conductive material (ketchun black, 10wt%) and binder (PTFE, 10 wt%), was prepared so that 2.5 mg / cm ^2. A 2032 coin type cell was fabricated by using a cathode of a sodium metal material, a sulfur dioxide inorganic electrolytic solution, and a glass separator using the prepared anode.

Examples and Comparative Examples after preparation of the electrolytic solution was calculated the ratio of SO ₂ in the electrolyte solution over time to confirm that the storage properties of the SO ₂ The results are shown in Figure 2. 2 is a graph illustrating the SO ₂ storage characteristics of a sodium-sulfur dioxide secondary battery according to Examples and Comparative Examples of the present invention.

Referring to FIG. 2, it was confirmed that the gallium-based inorganic electrolyte had excellent initial SO ₂ storage characteristics compared to the aluminum-based inorganic electrolyte.

In addition, the volatilization phenomenon of the initial SO ₂ was observed in the aluminum-based inorganic electrolyte, and it was confirmed that the SO ₂ was stably dissolved in the electrolyte despite the lapse of time in the gallium-based inorganic electrolyte. This means that the compatibility of the gallium-based inorganic electrolyte with SO ₂ is better.

The evaluation results of the battery characteristics of the sodium-sulfur dioxide secondary battery according to Examples and Comparative Examples are shown in Fig. The evaluation conditions were two cycles of charging and discharging at a current density of 2.0 to 4.05 V (vs. Na / Na +) at a constant current of 0.1 C, followed by charging current density of 0.2 C and discharging current density of 0.5 C. And charged / discharged 50 times. Figure 3 shows the first charge / discharge profile.

Referring to FIG. 3, the electrochemical behavior of the electrolyte varies depending on the metal component of the electrolyte solution. That is, the discharge voltage of the NaAlCl ₄ -nSO ₂ electrolyte according to the comparative example is about 3.05 (V), while the discharge voltage of the NaGaCl ₄ -nSO ₂ electrolyte according to the embodiment is 2.75 (V) lower than the discharge voltage.

It is considered that this is due to the change of the actual chemical structure of the electrolyte formed according to the kind of the metal. Aluminum based inorganic electrolytes according to the comparative examples exhibited an overvoltage phenomenon of about 0.80 (V), while the gallium based inorganic electrolytes according to the examples exhibited an electrochemical behavior of 0.35 (V) ) Were observed.

This is due to become, gallium inorganic electrolyte according to an embodiment can be combined with SO _2, but relatively by using a gallium bonding force between the SO ₂ is weak, easy desorption reaction at charging gallium and SO _2, as described above intend .

The results of evaluating the lifetime characteristics of the sodium-sulfur dioxide secondary batteries according to Examples and Comparative Examples are shown in FIG.

Referring to FIG. 4, it was confirmed that the gallium-based inorganic electrolyte according to Example exhibited a capacity of 800 mAh / g or more after initial preparation, and stable lifetime characteristics were expressed thereafter. This is believed to be due to the stable storage characteristics of the gallium-based inorganic electrolyte with SO ₂ . As a result, it was confirmed that the gallium-based inorganic electrolyte effectively contributes to improvement of the overall performance of the battery based on stable lifetime characteristics as well as improvement of the energy efficiency of the sodium-sulfur dioxide secondary battery.

It should be noted that the embodiments disclosed in the present specification and drawings are only illustrative of specific examples for the purpose of understanding, and are not intended to limit the scope of the present invention. It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention are possible in addition to the embodiments disclosed herein.

1: Sulfur dioxide based inorganic electrolyte
2: anode
3: cathode
4: Case
100: Sodium-sulfur dioxide secondary battery

Claims (15)

An anode of an inorganic material containing sodium;
Anode of carbon material;
An electrolytic solution containing a gallium-based inorganic electrolyte based on sulfur dioxide prepared by injecting SO ₂ gas into a mixture of NaX and GaX ₃ ;
≪ / RTI > characterized in that the sodium-sulfur dioxide rechargeable battery comprises a sodium-sulfur dioxide secondary battery.
(X is a halogen-containing compound, saturated hydrocarbon (R) having C1-C20, unsaturated hydrocarbon (R) having C1-C20, OR or SR) The method according to claim 1,
Wherein the molar ratio of NaX and GaX ₃ is 2.0: 1.0 to 1.0: 2.0. The method according to claim 1,
Wherein the sulfur dioxide-based gallium inorganic electrolyte is sodium, characterized in that NaGaCl ₄ -xSO ₂ (1.5≤x≤3.0) - sulfur secondary cell. The method according to claim 1,
Wherein the electrolyte further comprises an aluminum-based inorganic electrolyte based on sulfur dioxide. 5. The method of claim 4,
Wherein the sulfur-based aluminum-based inorganic electrolyte is NaAlCl ₄ -xSO ₂ (1.5? X? 3.0). 6. The method of claim 5,
The electrolyte is sodium, it characterized in that a mixture of NaGaCl ₄ -xSO ₂ and NaAlCl ₄ -xSO ₂ - sulfur secondary cell. A sodium-sulfur dioxide secondary battery comprising an electrolyte containing a sulfur-dioxide-based gallium-based inorganic electrolyte prepared by injecting an SO ₂ gas into a mixture of NaX and GaX ₃ . An electrolyte for a sodium-sulfur dioxide secondary battery comprising a sulfur-dioxide-based gallium-based inorganic electrolyte prepared by injecting SO ₂ gas into a mixture of NaX and GaX ₃ .
(X is a halogen-containing compound, saturated hydrocarbon (R) having C1-C20, unsaturated hydrocarbon (R) having C1-C20, OR or SR) 9. The method of claim 8,
Wherein the molar ratio of NaX and GaX ₃ is 2.0: 1.0 to 1.0: 2.0. 9. The method of claim 8,
Wherein the mixture of NaX and GaX ₃ is NaGaX ₄ . 9. The method of claim 8,
Wherein the mixture of NaX and GaX ₃ is NaGaCl ₄ mixed with NaCl and GaCl ₃ . 9. The method of claim 8,
Wherein the sulfur dioxide-based gallium-based inorganic electrolyte is NaGaCl ₄ -xSO ₂ (1.5? X? 3.0). 9. The method of claim 8,
Wherein the electrolyte further comprises an aluminum-based inorganic electrolyte based on sulfur dioxide. 14. The method of claim 13,
Wherein the sulfur-based aluminum-based inorganic electrolyte is NaAlCl ₄ -xSO ₂ (1.5? X? 3.0). 14. The method of claim 13,
Wherein the electrolyte is a mixture of NaGaCl ₄ -xSO ₂ and NaAlCl ₄ -xSO ₂ (1.5? X? 3.0).

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