KR101353341B1 - Sodium-sulfur rechargeable battery - Google Patents

Abstract

Overcoming the limitations of securing safety through safety pipes, and improving the safety of the battery, and in order to ensure the safety of the battery by blocking the supply of sodium at the time of electrolyte tube damage, the anode chamber containing sulfur, sodium A battery unit including a cathode electrolyte, a cathode electrolyte, and a cathode electrolyte provided between the cathode chamber and the cathode chamber to selectively move only sodium ions, thereby charging and discharging; A negative electrode container disposed outside the battery unit and containing sodium; It is connected between the negative electrode container and the negative electrode chamber of the battery unit provides a sodium sulfur battery including a sodium supply for distributing sodium to the negative electrode chamber.

Description

[0001] SODIUM-SULFUR RECHARGEABLE BATTERY [0002]

The present invention relates to a sodium sulfur battery. More particularly, the present invention relates to a sodium sulfur battery having enhanced safety.

Generally, a sodium-sulfur battery is developed as a large-capacity power storage battery because of its high energy density, charge / discharge efficiency, self-discharge, and irregular charge / discharge characteristics.

Sodium sulfur batteries use sodium alumina (Na) as the cathode, sulfur (S) as the anode, and beta-alumina ceramics of the solid electrolyte having sodium ion conductivity as the electrolyte. The sodium sulfur battery includes an anode tube enclosing an electrolyte tube and an electrolyte tube. The electrolyte tube has a structure in which a beta-alumina ceramic having a property of passing only sodium ions is formed in a tube shape. The inside of the electrolyte tube is filled with sodium, and sulfur and carbon felt are placed between the electrolyte tube and the positive electrode container. The sodium ion is transferred between the cathode and the anode through the beta alumina, which is an electrolytic tube, to charge and discharge the battery.

In the case of sodium sulfur battery, when the electrolytic tube is broken during operation, the sulfur of the anode flows into the cathode through the breakage portion of the electrolytic tube, and thereby contacts with the sodium of the cathode to cause a rapid chemical reaction.

Sodium and sulfur will produce sodium sulphide upon contact. The sulfide formation reaction is an exothermic reaction in which the enthalpy change is about -380 to -470 KJ / mole at 300 ° C. Therefore, there is a risk that the battery will fire or explode when sulfur in the anode is reacted with a large amount of sodium in the negative electrode. The sodium sulfur cell contains up to about 700-800 g of sodium in the cell, and assumes all sodium and sulfur react, it emits up to about 6 ~ 7 MJ of energy, and the temperature of the cell instantaneously rises above 1000 ℃.

The sodium sulfur battery is installed inside the electrolyte pipe, and a safety pipe is installed to block the inflow of sulfur when the electrolyte pipe breaks. Inside the safety tube, there is installed a negative electrode container containing sodium, and the sodium that is discharged through the hole formed in the lower portion of the negative electrode container is supplied between the safety pipe and the negative electrode container to the gap between the safety pipe and the electrolyte pipe.

The safety tube is a metallic material having a large thermal expansion coefficient and maintains a fine gap with the electrolyte tube. Therefore, the safety tube expands due to a rapid temperature rise due to an exothermic reaction of sulfur and sodium at the time of breakage of the electrolyte tube, and is adhered to the inner surface of the electrolyte tube. As a result, the supply of sodium to the damaged area is blocked to prevent further chemical reaction and heat generation.

However, the above-described conventional structure requires a clearance between the inner circumferential surface of the electrolyte tube and the safety tube over the entire inner circumferential surface of the electrolyte tube in order for the safety tube to function properly.

In order to control all the gaps between the electrolyte pipe and the safety pipe at regular intervals, it is necessary to measure and control the precise numerical values of the electrolytic pipe and the safety pipe, as well as to construct complicated equipment for accurate expansion of the safety pipe. In addition, there is a high possibility that the electrolyte pipe is broken due to the stress generated at the contact portion between the safety pipe and the electrolyte pipe.

In particular, as the temperature around the electrolyte tube breaks up above the melting point of the metal safety tube due to instantaneous mass heat generation when the local electrolyte tube breaks, a large amount of sodium flows from the cathode container into the damaged part and explodes exothermic reaction. It has a fundamental problem causing it.

Accordingly, the present invention provides a sodium sulfur battery that overcomes limitations of a safety structure using a safety tube and can further enhance battery safety.

Further, the present invention provides a sodium sulfur battery which can secure the safety of a battery by originally shutting off the supply of sodium when the electrolyte tube is broken.

To this end, the sodium-

A positive electrode chamber containing sulfur, a negative electrode chamber containing sodium, and a plate-shaped solid electrolyte disposed between the anode chamber and the cathode chamber to selectively move only sodium ions, surrounding the anode chamber and the cathode chamber, and supporting the solid electrolyte, An insulating ring for insulating the negative electrode chamber and a battery unit including a positive electrode plate and a negative electrode plate coupled to the insulating ring to seal the positive electrode chamber and the negative electrode chamber and to collect electrons from the positive electrode chamber and the negative electrode chamber;

A negative electrode container disposed outside the battery unit and containing sodium;

Sodium supply unit connected between the negative electrode container and the negative electrode chamber of the battery unit for distributing sodium to the negative electrode chamber

. ≪ / RTI >

The sodium supply unit may include a transport pipe connected between the cathode container and the cathode chamber to distribute sodium.

The sodium supply unit may include an injection tube connected between the cathode container and the cathode chamber to supply sodium and an outlet tube for recovering sodium.

The sodium supply unit may further include a pump installed in the inlet or outlet pipe to transfer sodium.

The sodium supply unit may further include a control unit for controlling the driving of the pump to adjust the supply amount of sodium.

The control unit may further include a flow meter for detecting the flow rate of sodium.

The control unit may further include a valve for opening and closing the outlet pipe, and a pressure gauge for detecting the pressure inside the injection pipe.

As described above, according to this embodiment, sodium is supplied to the inside of the battery only from the outside of the battery to react with the sulfur, so that a phenomenon in which a large amount of sodium reacts with sulfur when the solid electrolyte breaks down can be fundamentally blocked.

This reduces the risk of battery explosion and increases the safety of the battery.

In addition, by minimizing the size of the cathode chamber, the amount of sodium present in the battery is sufficiently lowered compared with the conventional one, thereby reducing the amount of heat generated by the battery during the breakage of the solid electrolyte and reducing the risk of explosion.

In addition, it is not necessary to finely manage the clearance between the safety tube and the solid electrolyte as compared with the conventional, it is possible to sufficiently secure the safety of the battery without increasing the precision of the parts and assembly, such as safety tube. The manufacturing of the safety tube or the battery assembly process can be made more simply and easily, it is possible to increase the cost competitiveness by lowering the manufacturing cost of the battery.

1 is a cross-sectional view of a sodium sulfur battery according to an embodiment of the present invention.
2 is a cross-sectional view illustrating a sodium sulfur battery according to another embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. It will be apparent to those skilled in the art that the embodiments described below may be modified in various forms without departing from the spirit and scope of the present invention, .

The drawings are schematic and illustrate that they are not drawn to scale. The relative dimensions and ratios of the parts in the figures are shown exaggerated or reduced in size for clarity and convenience in the figures, and any dimensions are merely illustrative and not restrictive.

1 shows a sodium sulfur battery according to this embodiment.

Referring to FIG. 1, the sodium sulfur battery 100 according to the present embodiment includes a battery unit 10 in which charging and discharging is performed, and a negative electrode container 50 and a negative electrode container 50, which are separately provided from the battery unit 10 and accommodate sodium. And a sodium supply unit 60 for distributing sodium between the cell unit 10 and the battery unit 10.

In this embodiment, the battery unit 10 has a flat plate-like structure.

To this end, the battery unit 10 is disposed between the positive electrode chamber 12 containing sulfur, the negative electrode chamber 24 containing sodium, and the positive electrode chamber 12 and the negative electrode chamber 24 so that only sodium ions are present. Insulating the plate-shaped solid electrolyte 16 to selectively move, surrounding the anode chamber 12 and the cathode chamber 24, supporting the solid electrolyte 16, and insulating the anode chamber 12 and the cathode chamber 24. The positive electrode plate 26 and the negative electrode plate coupled to the ring 20 and the insulating ring 20 to seal the positive electrode chamber 12 and the negative electrode chamber 24 and collect electrons from the positive electrode chamber 12 and the negative electrode chamber 24. 28).

The battery unit 10 has a flat plate structure in which the insulating ring 20 and the negative electrode plate 28 and the positive electrode plate 26 of the upper and lower portions of the insulating ring form a side surface and an upper and lower surface. The anode chamber 12 is formed between the anode plate 26, the insulating ring 20, and the solid electrolyte 16. In the anode chamber 12, a felt collector 22 containing sulfur is filled. The felt current collector 22 is, for example, carbon felt having pores formed therein, and sulfur is contained in the pores. An inert gas such as nitrogen gas or argon gas may be filled in the internal space of the anode chamber 12 at a predetermined pressure.

The solid electrolyte 16 is made of beta alumina ceramic capable of passing sodium ions. In the present embodiment, the solid electrolyte 16 has a flat plate shape.

Insulation ring 20 is a ring-shaped structure with a central opening. The insulating ring 20 is made of alpha alumina ceramic to prevent a short between the cathode and the anode. The solid electrolyte 16 is bonded to the open central portion of the insulating ring 20. The insulating ring 20 is bonded at a high temperature using the solid electrolyte 16 and the glass sealant. The upper and lower ends of the insulating ring 20 are respectively covered with a metal negative electrode plate 28 and a positive electrode plate 26 to block the negative electrode chamber and the positive electrode chamber. The negative electrode plate 28 and the positive electrode plate 26 are bonded to the insulating ring through a thermal compression bonding (TCB) process.

The gap between the negative electrode plate 28 and the solid electrolyte 16 forms a negative electrode chamber 24 in which sodium is accommodated. Thus, sodium in the negative electrode container 50 is introduced between the negative electrode plate 28 and the solid electrolyte 16 by the sodium supply part 60 to fill the negative electrode chamber 24.

In this embodiment, the gap between the negative electrode plate 28 and the solid electrolyte 16 can be maintained at a minimum interval so that only sodium necessary for the battery reaction can be accommodated. Accordingly, by reducing the amount of sodium remaining in the battery unit 10 to a minimum level, it is possible to reduce the risk of fire or explosion due to heat generation of the battery. For example, when the gap between the negative electrode plate 28 and the solid electrolyte 16 is maintained at 100 μm, the amount of sodium remaining in the battery unit 10 may be reduced to 1/100 of that of the conventional battery. Can be. Accordingly, the risk of fire or explosion due to heat generation of the battery can be reduced as much as possible.

On the other hand, the battery has a structure in which the negative electrode container 50 is provided separately from the battery unit 10.

The negative electrode container 50 may be disposed immediately adjacent to the battery unit 10. Alternatively, the battery unit 10 may be installed at a position spaced apart from the battery unit 10. The negative electrode container 50 is sufficient to be provided separately to the outside of the battery unit 10 and the installation position is not particularly limited. The cathode container 50 may be made of a metal material, such as aluminum, stainless steel.

The cathode container 50 is filled with sodium inside. In addition, an inert gas such as nitrogen gas or argon gas may be filled in the cathode container at a predetermined pressure. The inert gas creates a pressing force that pushes the sodium in the cathode vessel through the sodium feed.

The sodium supply unit 60 is connected between the negative electrode container 50 and the negative electrode chamber 24 of the battery unit includes a transfer tube 61 for distributing sodium.

As shown in FIG. 1, the transfer pipe 61 of the sodium supply unit 60 is connected to the inside of the cathode chamber 24 through the cathode plate 28.

The sodium supplied to the transfer pipe 61 is supplied to the cathode chamber 24 and filled in the cathode chamber 24. The negative electrode container 50 and the negative electrode chamber 24 are connected through a transfer tube 61, so that the amount of sodium required by the battery reaction is distributed between the negative electrode container and the battery unit through the transfer tube 61.

As such, by separating the negative electrode container from the battery unit and supplying only the amount of sodium necessary for the battery reaction to the battery unit in real time, even if the solid electrolyte is damaged, a large amount of exothermic reaction can be blocked.

In this case, a pump may be further installed in the transfer pipe 61 to distribute sodium. The pump forcibly transfers sodium from the cathode container 50 by the required amount. In addition, if necessary, by forcibly recovering the sodium from the negative electrode chamber to the negative electrode container, so that sodium does not remain in the battery unit when the solid electrolyte breaks. In addition, a flow meter or hydraulic system or valve for sodium supply control may be further installed in the transfer pipe 61. Detailed configuration of the pump, the flow meter, the hydraulic system, the valve will be described later.

On the other hand, Figure 2 shows another embodiment of a sodium sulfur battery.

Except for the structure of the sodium supply in this embodiment, the rest of the configuration is the same as the other embodiments mentioned above. The same reference numerals are used for the same components, and a detailed description thereof will be omitted.

As shown in FIG. 2, the battery 100 includes a battery unit 10 in which charging and discharging is performed, and a negative electrode container 50, a negative electrode container 50, which is provided separately from the battery part 10, and accommodates sodium. And a sodium supply unit 60 for distributing sodium between the battery units 10.

The sodium supply unit 60 is connected between the cathode container 50 and the cathode chamber 24 includes an injection tube 62 for supplying sodium and an outlet tube 64 for recovering sodium.

The injection tube 62 passes through the negative electrode plate 28 and is connected to one end portion of the negative electrode chamber 24. In addition, the outlet pipe 64 is connected to the opposite end of the cathode chamber 24.

The sodium supplied to the injection tube 62 is supplied to the cathode chamber 24, and is recovered to the cathode container 50 through the outlet tube 64 connected to the opposite side of the cathode chamber.

Here, the sodium supply unit 60 may further include a pump 66 installed in the injection tube 62 to transfer sodium in the negative electrode container 50 to the negative electrode chamber 24.

In addition, the present battery has a structure in which the supply amount of sodium is adjusted according to the charge and discharge of the battery unit 10. Accordingly, only the optimum amount of sodium necessary for the battery reaction can be supplied to the negative electrode chamber according to the battery part charging and discharging. The supply amount of sodium is adjusted by controlling the driving of the pump 66.

In the present embodiment, whether or not the supply amount of natrium is appropriate is made by detecting the flow rate of sodium. To this end, the outlet pipe 64 is provided with a flow meter 70 for detecting the flow rate of sodium.

Accordingly, by controlling the pump 66 so as to maintain a constant flow rate of sodium detected in the flow meter 70, the amount of sodium supplied is controlled to supply only the amount of sodium necessary for the battery reaction to the cathode chamber 24. .

Hereinafter, the operation of the sodium sulfur battery according to the embodiment of FIG. 2 will be described. In the embodiment of Figure 1 also only the distribution structure of sodium, the operation is the same.

As shown in FIG. 2, the liquid sodium is transferred from the sodium container 50 filled with sodium to the initial flow rate set through the injection tube 62, and is supplied to the cathode chamber 24 of the battery unit 10. Then, the outlet tube 64 connected to the cathode chamber 24 is returned to the cathode container 50 again. The initial flow rate may be determined by the amount of sodium required for the battery reaction, and the minimum amount of sodium to be supplied to the cathode chamber according to the size or structure of the battery unit. By keeping the initial flow rate constant, only sodium necessary for the battery reaction can be accommodated in the negative electrode chamber.

By the pressure of the inert gas filled in the negative electrode container 50 or by the operation of the pump 66, sodium passes through the injection tube 62 and the gap between the negative electrode plate 28 and the solid electrolyte 16 of the battery unit 10 It is supplied to the cathode chamber 24 formed in the.

According to the driving of the battery, for example, during discharge, sodium ions in the cathode chamber 24 move through the solid electrolyte 16 to the cathode chamber 12. As sodium ions move into the anode chamber 12, the sodium flow rate in the outlet tube 64 decreases at the set initial flow rate. The decrease in the flow rate at the outlet pipe 64 is detected by the flow meter 70. Accordingly, the pump 66 is controlled by as much as the flow rate decrease value detected through the flowmeter 70, that is, the amount of sodium ions moved to the anode chamber 12, thereby additionally adding sodium through the injection tube 62. Supply more). Thus, the sodium flow rate in the outlet pipe 64 is restored to the initial flow rate and maintained.

On the contrary, during charging, since sodium ions generated by decomposition of the sulfide in the anode chamber 12 move to the cathode chamber 24 to form liquid sodium, the sodium flow rate in the outlet tube 64 is increased to be higher than the set initial flow rate. do. The increase in the flow rate at the outlet pipe 64 is detected by the flow meter 70. Accordingly, the pump 66 is controlled by the flow rate increase value detected through the flowmeter 70, that is, the amount of sodium ions moved to the cathode chamber 24, thereby reducing the amount of sodium supplied through the injection pipe 62. Thus, the sodium flow rate in the outlet pipe 64 is restored to the initial flow rate and maintained.

As such, by adjusting the amount of sodium supplied to maintain the flow rate of sodium at the predetermined initial flow rate at the time of charging and discharging the battery unit 10, only the amount of sodium necessary for the battery reaction can be supplied to the negative electrode chamber 24.

Therefore, only a minimum of sodium remains in the battery unit 10, so that a large amount of sodium reacts with sulfur when the solid electrolyte 16 is damaged.

Here, the present battery is a structure for checking the supply amount of sodium according to the charge and discharge of the battery unit 10, a structure using a pressure in addition to the flow rate of sodium can also be applied.

To this end, the battery may include a valve 74 that opens and closes the outlet pipe 64, and a pressure gauge 72 that detects an internal pressure of the injection pipe 62.

Thus, the pressure inside the cathode chamber 24 by sodium which flowed into the cathode chamber 24 through the pressure gauge 72 in the state which closed the outlet pipe 64 by the valve 74 is detected. By controlling the pump 66 according to the pressure value detected by the pressure gauge 72, it is possible to supply only the amount of sodium necessary for the battery reaction.

That is, during discharge, when sodium ions in the cathode chamber 24 are moved to the anode chamber 12, the internal pressure of the cathode chamber 24 is lower than the set initial pressure. The pressure inside the cathode chamber 24 is detected through the pressure gauge 72. Accordingly, the pump 66 may be controlled to further supply sodium to the cathode chamber 24 by the amount of pressure reduction. In accordance with the sodium supply, the pressure inside the cathode chamber 24 is restored to and maintained at the initial pressure. On the contrary, during charging, sodium ions move to the cathode chamber 24 so that the pressure inside the cathode chamber 24 becomes high. This is detected by the pressure gauge 72 and similarly, by controlling the pump 66 in accordance with this value to reduce the supply amount of sodium, the pressure inside the cathode chamber 24 can be restored and maintained at the initial pressure. Therefore, the structure using the hydraulic system is also able to supply only the amount of sodium necessary for the battery reaction to the negative electrode chamber 24 by adjusting the sodium supply amount during the battery unit 10 charging and discharging.

As described above, the present battery can increase the safety of the battery by removing the negative electrode container 50 containing sodium from the battery unit 10 and supplying sodium to the battery unit 10 as necessary.

In addition, in the battery, since the negative electrode container 50 is separated from the battery unit 10, the sodium temperature in the negative electrode container 50 can be kept lower than the driving temperature (about 290 to 350 ° C.) of the battery. Sodium maintains fluidity even at a temperature slightly higher than the melting point of 100 DEG C, so that the battery can be driven even if the temperature of the sodium is sufficiently lowered. When the sodium combustion reaction occurs due to the breakdown of the cathode container 50 by keeping the temperature of sodium low, it is possible to secure additional safety by slowing the reaction compared to the high temperature combustion reaction in terms of reaction rate.

In addition, in the case of the battery of the present embodiment, the battery unit has a flat plate shape, and thus, a plurality of battery units may be stacked to configure a large capacity battery.

While the illustrative embodiments of the present invention have been shown and described, various modifications and alternative embodiments may be made by those skilled in the art. Such variations and other embodiments will be considered and included in the appended claims, all without departing from the true spirit and scope of the invention.

10: battery part 12: anode chamber
16: solid electrolyte 20: insulating ring
24: cathode chamber 50: cathode container
60: sodium supply unit 61: transfer pipe
62: injection pipe 64: outlet pipe
66: pump 70: flow meter
72 pressure gauge 74 valve

Claims (7)

A positive electrode chamber containing sulfur, a negative electrode chamber containing sodium, and a plate-shaped solid electrolyte disposed between the anode chamber and the cathode chamber to selectively move only sodium ions, surrounding the anode chamber and the cathode chamber, and supporting the solid electrolyte, An insulating ring for insulating the negative electrode chamber, a battery unit including a positive electrode plate and a negative electrode plate coupled to the insulating ring to seal the positive electrode chamber and the negative electrode chamber and collecting electrons from the positive electrode chamber and the negative electrode chamber;
A negative electrode container disposed outside the battery unit and containing sodium;
Sodium supply unit connected between the negative electrode container and the negative electrode chamber of the battery unit for distributing sodium to the negative electrode chamber
≪ / RTI > The method of claim 1,
The sodium supply unit is a sodium sulfur battery comprising a transfer pipe connected between the cathode container and the cathode chamber for distributing sodium. The method of claim 1,
The sodium supply unit is connected to the cathode container and the cathode chamber sodium sulfur battery including an inlet tube for supplying sodium and the outlet tube to recover the sodium. The method of claim 3, wherein
Sodium sulfur battery further comprises a pump for transporting the sodium is installed in the inlet or outlet pipe. 5. The method of claim 4,
The sodium supply unit further comprises a control unit for adjusting the supply amount of sodium by controlling the driving of the pump. The method of claim 5, wherein
The adjusting unit includes a sodium sulfur battery comprising a flow meter for detecting the flow rate of sodium. The method of claim 5, wherein
The adjusting unit further comprises a valve for opening and closing the outlet pipe, and a pressure gauge for detecting the pressure inside the injection tube sodium sulfur battery.

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