KR20190004072A - Solid-electrolyte and manufacturing method for the same, seawater-battery using the same - Google Patents

Abstract

The present invention provides a solid electrolyte for a seawater battery, a manufacturing method thereof, and a seawater battery using the same. The seawater battery comprises: a cathode unit for receiving an anode active material in an inner space of an anode receptor; an anode unit for receiving a cathode active material in an inner space of a cathode receptor; and a solid electrolyte interposed between the cathode unit and the anode unit, and capable of selectively passing sodium ions. In addition, the solid electrolyte comprises: a high density electrolyte layer including a NASICON material; and a porous structure layer integrally laminated on at least one surface of both surfaces of the high density electrolyte layer, including the NASICON material, and having the thickness thicker than that of the high density electrolyte layer and porosity greater than that of the same. By using the solid electrolyte for a seawater battery, the manufacturing method thereof, and the seawater battery using the same, it is possible to improve an electrolyte function of the solid electrolyte, resulting in improving output and performance of the seawater battery.

Description

TECHNICAL FIELD [0001] The present invention relates to a solid electrolyte for a seawater battery, a method for manufacturing the same, and a seawater battery using the same,

The present invention relates to a solid electrolyte for a sea water battery, a method for producing the same, and a method for manufacturing the same. More particularly, the present invention relates to a solid electrolyte for a sea water battery which stores electricity by using seawater (sea water) The present invention relates to a seawater cell.

In modern society, the importance of energy is growing along with technological development. Many researches are being conducted to develop clean energy that can be continuously used without problems of exhaustion and environmental pollution like fossil energy and environment friendly. As a result, solar / light, wind energy, etc., which use the environment, have been developed. However, since the environmentally friendly energy sources described above can not be used because they can not be used in the case of cloudy, windy, or the like, the technology for storing environmentally-friendly energy is also increasing in importance.

A typical energy storage method is a lithium ion battery, which is disadvantageous in that lithium as a raw material is expensive and its amount is limited. Recently, the development of technology for seawater cells has been emphasized as a substitute for lithium ion batteries.

A seawater cell is a type of secondary cell that stores electricity using sodium (Na) that can be easily obtained from seawater (sea water) and provides the stored energy. The surface area of the earth is composed of about 70% of the sea, about 3.5% of which consists of ions, and about 30.6% of the 3.5% ions are present. Therefore, it is one of the important advantages that the sodium ion necessary for the sea water cell can be easily obtained at low cost without worrying about depletion.

However, the output of the seawater cell is greatly influenced by the performance of the sodium ion through the solid electrolyte separating the cathode and the anode. Therefore, the importance of research on solid electrolytes as one of the measures for enhancing the performance of the output of the battery is greatly increasing. Above all, NASICON is mainly used as a solid electrolyte. However, when the thickness of the nacicon is increased in order to increase the structural rigidity of the solid electrolyte, the performance of the solid electrolyte is lowered.

Korean Patent Publication No. 10-2015-0130175 (published date: November 23, 2015)

An object of the present invention is to provide a solid electrolyte for a seawater battery capable of increasing the output of sodium ions between a cathode and an anode, a method for producing the same, and a seawater cell using the same.

According to an aspect of the present invention, there is provided a solid electrolyte for a sea water battery comprising: a high-density electrolyte layer including a NASICON material; And a porous structure layer which is integrally laminated on at least one of both surfaces of the high-density electrolyte layer and has a thickness larger than that of the high density electrolyte layer and a large porosity. The total thickness of the high-density electrolyte layer and the porous structure layer may be 0.8 to 1.2 mm, and the thickness of the high-density electrolyte layer may be 10 to 500 μm. The porous structure layer may be formed on either side of the high-density electrolyte layer to have a two-layer structure. The porosity of the porous structure layer can be formed while the starch mixed with the nacicon material of the porous structure layer is removed in the manufacturing process. The starch may be corn starch.

According to another aspect of the present invention, there is provided a method of manufacturing a solid electrolyte for a sea water battery, comprising the steps of: preparing a powder for a porous structure layer containing a NASICON material and starch; A pellet producing step of pelletizing a powder for a high density electrolyte layer containing the naconic material and a powder for the porous structure layer in a mold for solid electrolyte formation for a sea water battery; The pellet is sintered to form a high density electrolyte layer formed by the powder for high density electrolyte layer and a powder for porous structure layer formed integrally on at least one of both surfaces of the high density electrolyte layer and the starch is removed by sintering, And a sintering step of forming the solid electrolyte for a seawater battery including the porous structure layer.

In the powder manufacturing step, the starch may be corn starch. The powder for the porous structure layer may be blended with the starch in an amount of 20 to 25% by weight based on the nacicon material. In order to form a solid electrolyte for a seawater battery having a two-layer structure in which the porous structure layer is laminated on only one side of the high-density electrolyte layer, the powder for a porous structure layer is first introduced into the mold at a predetermined thickness And a second step of injecting the powder for the high density electrolyte layer into the powder for porous structure layer injected into the mold after the first step and the first step to a certain thickness. In the pellet manufacturing step, when the total thickness of the high-density electrolyte layer and the porous structure layer of the solid electrolyte for a sea water battery is 0.8 to 1.2 mm, the thickness of the high-density electrolyte layer is 10 to 500 μm, The powder for the porous structure layer can be introduced. The sintering step may include a first sintering step of sintering at a temperature of 750 ° C. to 850 ° C. according to a sintering temperature and a second sintering step of raising the sintering temperature to a range of 1000 ° C. to 1500 ° C. after the first sintering step have. The porosity of the porous structure layer may be greater than the porosity of the high-density electrolyte layer. The thickness of the porous structure layer may be greater than the thickness of the high-density electrolyte layer.

According to another aspect of the present invention, there is provided a solid electrolyte for a seawater battery, comprising: a cathode portion containing an anode active material in an inner space of an anode receptor; A cathode portion in which a cathode active material is accommodated in an inner space of a cathode receptacle; And a solid electrolyte interposed between the cathode and the anode, the solid electrolyte being capable of selectively passing sodium ions, wherein the solid electrolyte comprises a high density electrolyte layer including a NASICON material and a high density electrolyte layer And a porous structure layer including the nacicon material and thicker than the high-density electrolyte layer and having a large porosity.

Wherein the pores of the porous structure layer are formed while removing corn starch mixed with the naconic material of the porous structure layer in a manufacturing process; When the thickness of the solid electrolyte layer is 0.8 to 1.2 mm, the thickness of the high-density electrolyte layer is 10 to 500 μm, and the porous structure layer may be laminated on either side of the high-density electrolyte layer in a two- have.

Since the solid electrolyte for a seawater battery of the present invention has a laminated structure composed of a high density electrolyte layer and a porous structure layer, the high density electrolyte layer can be formed thin and the required mechanical strength can be provided by the porous structure layer. Therefore, The performance of the sodium ion can be remarkably improved, and as a result, the output and performance of the seawater cell can be improved.

In addition, the solid electrolyte of the present invention is environmentally friendly and economical because the porous structure layer can have porosity using corn starch, and does not hinder ion conductivity of sodium ions at all.

Further, the solid electrolyte of the present invention can be economically produced by the simultaneous sintering method with little effort and time.

The present invention can simultaneously manufacture and integrate the porous structure layer and the high-density electrolyte layer by a single sintering process.

1 is a schematic block diagram of a seawater cell according to an embodiment of the present invention.
2 is a schematic cross-sectional view of the solid electrolyte for a sea water battery shown in FIG.
3 is a schematic flow chart of a process for manufacturing the solid electrolyte for a sea water battery shown in FIG.
FIG. 4 is a schematic view illustrating a process of charging the sea water cell shown in FIG. 1. FIG.
FIG. 5 is a schematic view illustrating a discharge process of the sea water cell shown in FIG. 1. FIG.

In order to fully understand the present invention, operational advantages of the present invention, and objects achieved by the practice of the present invention, reference should be made to the accompanying drawings and the accompanying drawings which illustrate preferred embodiments of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in order to avoid unnecessarily obscuring the subject matter of the present invention.

1, a seawater cell according to an embodiment of the present invention stores energy by using abundant sodium ions in seawater and provides stored energy, and includes an anode part 10, a cathode part 20 and a solid electrolyte 30 and has an inlet 2 through which external sea water flows into the one side connected to the anode portion 10 and an outlet 4 through which internal sea water is discharged.

Diethyl carbonate as the anode electrode 12 may be accommodated in the inner space of the cathode receiver in the form of paper in the anode portion 10. [ Also, the cathode active material may be contained in the inner space of the cathode receiver. The cathode active material may be a nickel chloride agglomerate. The nickel chloride agglomerates may be mixed together with a liquid molten salt electrolyte, and the liquid molten salt electrolyte may be NaAlCl ₄ .

In the cathode portion 20, sodium metal as the cathode electrode 22 may be accommodated in the inner space of the anode receiver. Also, the anode active material may be accommodated in the inner space of the anode receiver. The anode active material may be a sodium molten solution. In this case, a heating device (not shown) or the like may be provided on the cathode part 20 to maintain the molten state of the sodium molten liquid.

The solid electrolyte 30 may be formed by separating the cathode portion 20 and the anode portion 10 so as to selectively pass only sodium ions between the cathode portion 20 and the anode portion 10, Is interposed between the cathode portion (20) and the anode portion (10). Na ₃ Zr ₂ Si ₂ PO _{12, which} is a NASICON (Na super ion conductor), may be preferably used as the solid electrolyte 30 so as to efficiently transmit sodium ions.

In particular, the solid electrolyte 30 has a multilayer structure, that is, a structure in which the high-density electrolyte layer 32 and the porous structure layer 34 are alternately stacked at least once.

The high-density electrolyte layer 32 is densely formed of the nacicon material for the main purpose of electrolyte function. When the dense electrolyte layer 32 is too thick, the ion conductivity of the sodium ion is deteriorated due to the dense structure, and as a result, the output and performance of the seawater cell are lowered. Therefore, the dense electrolyte layer 32 is formed to have a thickness of several tens to several hundreds of micrometers (t1) Can be more efficient.

The porous structure layer 34 supports the high density electrolyte layer 32 without interfering with the electrolyte function of the high density electrolyte 30 to compensate for the low mechanical strength due to the thin film structural characteristics of the high density electrolyte layer 32 . The porous structure layer 34 is basically made of the NASICON material and may have a porosity larger than that of the high density electrolyte layer 32. The porous structure layer 34 is formed thicker than the high-density electrolyte layer 32 for mechanical stiffness of the solid electrolyte 30. That is, the sodium ion can pass easily without being subjected to a large resistance by the thin thickness t1 of the high density electrolyte layer 32 and the pores 34a of the porous structure layer 34, , That is, the performance can be greatly improved, and at the same time, the solid electrolyte 30 can have a sufficiently sufficient mechanical strength by the total laminate thickness T of the high density electrolyte layer 32 and the porous structure layer 34 . Since the porous structure layer 34 can easily pass through the sodium ion as described above, the porous structure layer 34 may be positioned on the cathode 20 side or the anode 10 side with respect to the high-density electrolyte layer 32 The solid electrolyte 30 can be easily designed.

On the other hand, the pores 34a of the porous structure layer 34 are initially contained in the porous structure layer powder forming the porous structure layer 34 in the manufacturing process of the solid electrolyte 30, . Particularly, it is possible to use starch, in particular, corn starch, which is a natural polymer, as an additive. As a result, the production process of the solid electrolyte 30 can be economical, economical, and environmentally friendly, and the final solid electrolyte 30 The porous structure layer 34 may have a sufficiently large pore size.

The porous structure layer 34 may be formed on at least one of both surfaces of the high-density electrolyte layer 32 to supplement the electrolyte function and mechanical strength of the high-density electrolyte layer 32. That is, the porous structure layer 34 may be stacked on one side or both sides of the high-density electrolyte layer 32 according to the required output, performance, capacity, etc. of the seawater battery of the present invention. In addition, the solid electrolyte 30 may have a structure in which the high-density electrolyte layer 32 and the porous structure layer 34 are alternately stacked one or more times. However, the solid electrolyte 30 has a two-layer structure in which the porous structure layer 34 is laminated only on one of both surfaces of the high-density electrolyte layer 32 in consideration of electrolyte function and mechanical strength, It can be said that it is more reasonable. The total thickness T of the solid electrolyte 30 can be determined according to the required output, performance, capacity, etc. of the seawater battery of the present invention. However, the solid electrolyte 30 may have a diameter of 20 mm and the high- And the total thickness T of the porous structure layer 34 and the porous structure layer 34 is 0.8 to 1.2 mm, the high density electrolyte layer 32 is formed to have a thickness t1 ranging from 10 to 500 μm, Mechanical strength and so on.

The solid electrolyte 30 as described above may be more preferably produced by the co-sintering method as follows.

First, the powder is manufactured (S10). That is, a powder for a high-density electrolyte layer containing a NASICON material is prepared. The powder for the high density electrolyte layer may be made of only the nacicon material, and most of the powder is the nacicon material and may further include a small amount of additives. In addition, the nasikon powder and starch, especially cornstarch, are mixed at a certain ratio to prepare a powder for porous structure layer. The porosity of the porous structure layer 34 should be greater than that of the high-density electrolyte layer 32, and the porosity of the porous structure layer 34 may be easily controlled by the ratio of corn starch mixed with the powder for porous structure layer. That is, depending on the amount of starch mixed into the powder for porous structure layer, the degree of permeation of seawater, sodium ions, etc. through the solid electrolyte 30 is varied. In the case of the porous structure layer powder of the present invention, in consideration of the permeability of seawater, sodium ion, etc., and the overall mechanical stiffness of the solid electrolyte 30, the corn starch is mixed in an amount of about 20 to 25% It can be said that it is efficient. That is, when the total weight of the naconic material of the porous structure layer powder is 100, the weight of the corn starch may be mixed in a ratio of 20 to 25.

Next, a pellet manufacturing step S20 is performed. The pellet forming step S20 may include forming a porous structure layer 34 for forming the porous structure layer 34 in a mold for forming the solid electrolyte 30 for the lamination structure of the solid electrolyte 30. [ And a second step of injecting the high density electrolyte layer powder for forming the high density electrolyte layer 32 onto the porous structure layer powder put into the mold after the first step. The first step and the second step of the pellet production step (S20) may be repeated one or more times, alternately depending on the lamination structure of the solid electrolytes 30, as described above. Preferably, in order to make the solid electrolyte 30 have a two-layer structure as described above, the first process and the second process may be performed in order. At this time, the powder for the high density electrolyte layer and the powder for the porous structure layer are preferably added to a predetermined thickness by appropriately weighting them so that the porous structure layer 34 can be thicker than the high density electrolyte 32.

And the next sintering step (S30). That is, the pellets in the mold are pressurized at a predetermined temperature to form the solid electrolyte 30 in which the high-density electrolyte layer 32 and the porous structure layer 34 are integrally laminated. In detail, the sintering step may be performed while the high-density electrolyte layer 32 and the porous structure layer 34 are firmly bonded to each other. In particular, the porous structure layer 34 may have the porous structure The porosity of the layered powder may be larger than that of the high-density electrolyte layer 32 due to the formation of pores in the place where cornstarch is burnt, melted or evaporated.

At this time, the sintering temperature in the sintering step S30 may be determined according to the thickness of the solid electrolyte 30, the main component of the powder, and the like. In particular, in the case of the present invention, the gas generated by the removal of corn starch from the powder for porous structure layer is easily discharged, but unintentional pores are not formed in the high-density electrolyte layer 32 due to the discharged gas. Therefore, in the case of the present invention, the sintering step (S30) can be divided into various processes depending on the sintering temperature. Preferably, the first sintering process is carried out by sintering the pellets in the mold at about 800 캜 for several hours, that is, at 750 캜 to 850 캜. That is, in the first sintering process, the cornstarch of the powder for high-density structure layer is removed during the sintering process of the powder for porous structure layer and the powder for high-density structure layer which are put into the mold at once and pores are formed in the porous structure layer At the same time, the gas generated in the porous structure layer 34 can be easily discharged through the powder for high-density electrolyte layer still in the sintering process. In this process, the high-density electrolyte layer 32 It is possible to prevent formation of unfavorable pores. The second sintering process after the first sintering process is a finishing and sintering process of the pellets in the mold. The sintering temperature of the pellets in the mold is raised to about 1000 ° C to 1500 ° C to completely sinter the pellets in the mold, ) Can be molded.

As described above, when the solid electrolyte 30 is manufactured by the simultaneous sintering method, the high-density electrolyte layer 32 and the porous structure layer 34 can be manufactured at one time by a single apparatus, The bonding process of the porous structure layer 32 and the porous structure layer 34 is unnecessary and the high density electrolyte layer 32 and the porous structure layer 34 are integrated and the laminated state can be maintained very firmly.

The charging and discharging process of the sea water battery according to one embodiment of the present invention will now be described in detail.

1 and 4, during charging, seawater flows into the anode portion 10 through the inlet 2, and in the anode portion 10, seawater, i.e., water molecules are oxidized And the chloride ion is oxidized to extract sodium ions from the seawater. Sodium ions extracted from the anode part 10 pass through the solid electrolyte 30 and move to the cathode part 20. [ The sodium ions transferred to the cathode portion 20 are reduced to sodium metal. On the other hand, the oxidized seawater in the anode part 10 is desorbed and discharged to the outside through the outflow port. The overall reaction formula of the seawater cell of the present invention at the time of charging is as follows.

_{2NaCl (aq) + H 2 O} (l) -> 2Na (s) + 2HCl (aq) + 1 / 2O 2 (g)

E = 3.94V

Referring to FIGS. 1 and 5, as shown by arrow B in FIG. 1, during discharge, seawater flows from the outside through the outflow port, is used for chemical reaction at the anode portion 10, And is discharged to the outside. Sodium ions are generated from the sodium metal that is the cathode electrode 22 in the cathode portion 20 and pass through the solid electrolyte 30 to the anode portion 10. The overall reaction formula at the time of discharge is as follows.

2NaCl (aq) -> 2Na ( s) + Cl 2 (g)

E = 4.07 V

In the course of charging and discharging the seawater battery according to the present invention, when sodium ions pass through the solid electrolyte 30, the thin thickness t1 of the high density electrolyte layer 32 and the thickness t1 of the porous structure layer 34 The seawater cell of the present invention can have an excellent level of output and performance because it can easily move without large resistance by the pores 34a.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the scope of the present invention is not limited to the disclosed exemplary embodiments. It should also be understood that many modifications and variations are possible without departing from the scope of the invention, as would be understood by one of ordinary skill in the art.

10; Anode part 12; Anode electrode
20; Cathode portion 22; Cathode electrode
30; Solid electrolyte 32; The high density electrolyte layer
34; Porous structure layer 34a; Porous

Claims (15)

A high density electrolyte layer comprising a NASICON material; And
A porous structure layer including the nacicon material and thicker than the high density electrolyte layer and having a large porosity, the porous structure layer being integrally laminated on at least one of the both surfaces of the high density electrolyte layer;
A solid electrolyte for a sea water battery. The method according to claim 1,
Wherein the total thickness of the high density electrolyte layer and the porous structure layer is 0.8 to 1.2 mm, and the thickness of the high density electrolyte layer is 10 to 500 μm. The method according to claim 1,
And the porous structure layer is laminated on only one side of the high-density electrolyte layer to form a two-layer structure. The method according to any one of claims 1 to 3,
Wherein the pores of the porous structural layer are formed while removing starch mixed with the naconic material of the porous structural layer in the manufacturing process. The method of claim 4,
Wherein the starch comprises corn starch. A powder manufacturing step of producing a powder for a porous structure layer containing a NASICON material and starch;
A pellet producing step of pelletizing a powder for a high density electrolyte layer containing the naconic material and a powder for the porous structure layer in a mold for solid electrolyte formation for a sea water battery;
The pellet is sintered to form a high density electrolyte layer formed by the powder for high density electrolyte layer and a powder for porous structure layer formed integrally on at least one of both surfaces of the high density electrolyte layer and the starch is removed by sintering, A sintering step of sintering the solid electrolyte for a seawater battery including the porous structure layer;
Wherein the solid electrolytic solution is a mixture of water and a solvent. The method of claim 6,
Wherein the starch comprises cornstarch in the powder manufacturing step. The method of claim 7,
Wherein the powder for porous structural layer is mixed with the starch in an amount of 20 to 25% by weight based on the nacicon material. The method of claim 6,
In the pellet production step,
Layer structure of a solid electrolyte for a sea water battery in which the porous structure layer is laminated on only one side of the high-density electrolyte layer,
A first step of introducing the powder for porous structure layer into the mold at a predetermined thickness, and a second step of putting the powder for high density electrolyte layer into a predetermined thickness on the powder for porous structure layer put into the mold after the first step, A method for producing a solid electrolyte for a battery. The method according to any one of claims 6 to 9,
In the pellet manufacturing step, when the total thickness of the high-density electrolyte layer and the porous structure layer of the solid electrolyte for a sea water battery is 0.8 to 1.2 mm, the thickness of the high-density electrolyte layer is 10 to 500 μm, And the powder for porous structure layer is charged. The method according to any one of claims 6 to 9,
Wherein the sintering step includes a first sintering step of sintering at a temperature of 750 ° C to 850 ° C according to a sintering temperature and a second sintering step of sintering the sintering temperature to a range of 1000 ° C to 1500 ° C after the first sintering step, A method for producing a solid electrolyte for a battery. The method according to any one of claims 6 to 9,
Wherein the porosity of the porous structure layer is greater than the porosity of the high-density electrolyte layer. The method according to any one of claims 6 to 9,
Wherein the thickness of the porous structure layer is greater than the thickness of the high-density electrolyte layer. A cathode portion in which an anode active material is contained in an inner space of an anode receptor;
A cathode portion in which a cathode active material is accommodated in an inner space of a cathode receptacle;
A solid electrolyte interposed between the cathode and the anode and capable of selectively passing sodium ions;
/ RTI >
The solid electrolyte
A high density electrolyte layer comprising a NASICON material and
And a porous structure layer which is formed integrally on at least one of both surfaces of the high-density electrolyte layer and includes the nacicon material and is thicker than the high-density electrolyte layer and has a large porosity,
Sea water battery. 15. The method of claim 14,
Wherein the pores of the porous structure layer are formed while removing corn starch mixed with the naconic material of the porous structure layer in a manufacturing process;
Wherein the thickness of the high-density electrolyte layer is in the range of 10 to 500 μm when the thickness of the solid electrolyte layer is 0.8 to 1.2 mm, and the porous structure layer is formed of a water- battery.

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