JPH09251866A - Method of operating battery system using sodium-sulfur battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control a heat radiating quantity from a heat insulating container so as to allow not only a low output operation but also a high output operation and permit electric charge/discharge independently of an outside environmental temperature by regulating a temperature outside of the heat insulating container. SOLUTION: A battery system 1 is constituted such that a predetermined number of module cells are connected in series and in parallel. Each of the module cells is housed in a vacuum heat insulating container 4. The system 1 is air-tightly housed in a vessel 5 made of a heat insulating material having a low-heat insulating property. An exhaust fan 6 and a suction fan 7 are installed on the outer wall of the vessel 5. Furthermore, the system 1 comprises voltage/current monitoring means 9 for detecting a voltage and a current of the module cell so as to control the detected values, module cell control means 10 for detecting a temperature in the module cell so as to control the detected value, and intra-vessel temperature monitoring means 11 for detecting a temperature in the vessel 5 so as to control the detected value. A control computer 8 receives signals indicating a cell resistance, an operating temperature and the like, to thus output a control signal to the control means, based on the values.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for operating a battery system including a sodium-sulfur battery in which molten sodium is used as a cathode active material and molten sulfur is used as an anode active material.

[0002]

2. Description of the Related Art A sodium-sulfur battery has molten metal sodium as a cathode active material on one side and molten sulfur as an anode active material on the other side, and both have selective permeability to sodium ions. A high-temperature secondary battery operated at 300 to 350 ° C., isolated by a beta-alumina solid electrolyte.

A battery system using a sodium-sulfur battery is a module battery in which a predetermined number of unit cells having the above-mentioned structure are connected and housed in a heat insulating container.
Further, it is configured by connecting a predetermined number in series and parallel.

The operation of the battery system using the sodium-sulfur battery is performed by repeating a cycle including a first resting stage, a discharging stage, a second resting stage, and a charging stage. In the discharge stage, the molten sodium releases electrons to become sodium ions, which permeate the solid electrolyte tube and move to the anode side, where they react with sulfur and the electrons that have passed through the external circuit to produce sodium polysulfide,
A voltage of about 2V is generated. On the other hand, at the time of charging, the reaction of generating sodium and sulfur occurs contrary to the discharging. The above-mentioned charging step is an endothermic reaction, whereas the discharging step in which sodium polysulfide is produced from sodium and sulfur is an exothermic reaction.

In the conventional module battery, the amount of heat released from the heat insulating container is set so that the temperature of the battery that rises in the discharging stage drops to the value at the beginning of discharging in the resting stage and the charging stage. I've got a balance.
Therefore, the internal heat generation amount changes with the change of the output power and output time of the module battery, so that the heat radiation amount of the heat insulating container is changed each time. Further, when module batteries having different cell performances are used, the internal heat generation amount also changes, so that the heat radiation amount of the heat insulating container is changed.
Further, when the module battery resistance increases due to the deterioration of the single cell, the heat radiation amount of the heat insulating container is also changed.

[0006]

Therefore, it is necessary to frequently change the setting of the heat radiation amount of the heat insulating container. If such a setting change is not made, the heat radiation amount becomes excessive,
The heating of the heater was made larger and the heat balance was taken. In that case, since energy is consumed by heating the heater, the characteristic of the sodium-sulfur battery that high discharge efficiency is obtained is impaired.

[0007] Further, the heat radiation amount Q from the insulated container from being affected by the temperature T _b of the heat insulating container outside, it is difficult to adjust the heat radiation amount Q, sodium - a problem that inconvenience temperature control sulfur battery occurs was there.

In other words, the heat radiation amount Q from the heat insulating container is Q = Q ₀ (T−, where T is the temperature inside the heat insulating container and Q ₀ is the heat radiation amount at the reference internal temperature T _h and the reference external temperature T _o .
It is represented by T _b ) / (T _h −T _o ). For example, when T _b is high, the heat radiation amount Q becomes small, and there is a risk that the temperature of the sodium-sulfur battery will exceed a certain value during the discharging stage. It was

Further, when T _b is low, the amount of heat radiation Q becomes large, the temperature of the battery is too low to start charging and discharging, or the heater energy for heat retention is too large and the charging / discharging efficiency is high. There was a problem that it was not possible to drive with.

Also, the electric capacity q of the sodium-sulfur battery
Is determined by the amount of sulfur and sodium, q = IT
From (I represents current and T represents discharge time), the product of current and discharge time during discharge is constant. Therefore, when K is a constant, the heat of reaction is represented by K · q. Assuming that the resistance heat generation amount during discharge of the sodium-sulfur battery is Q _d and the heat radiation amount is H _d , the temperature rise of the battery during discharge is (Kq + Q _d −H _d ) / C (C is the heat capacity). It represents.).

By the way, as a method of using a sodium-sulfur battery, the purpose is to cut the peak from the conventional 8-hour rate operation of load leveling (rated operation: operation during 8 hours during the daytime when power demand is high). 4-hour rate operation (double output operation: the value of the discharge current during rated operation is I
_When expressed by _c , discharging is performed with a current of 2I _c . ) Or 2.7
Time constant operation: Assuming (3 times power operation to discharge at a current of similarly 3I _c.), Sodium - resistance calorific value Q _d at the time of discharge of sulfur batteries I ² RT (representing R is resistance.) Therefore, the amount of heat generated by resistance is doubled and 3 times, respectively.
Double.

Now, if T _b is constant, the first resting stage, the discharging stage, the second resting stage, which was possible in the normal operation,
Since it was impossible to reduce the heat balance of one cycle consisting of the charging stage to zero, continuous operation of multiple cycles was not possible, and high output operation was practically difficult.

The present invention has been made in view of such circumstances, and an object of the present invention is to adjust the temperature outside the heat insulating container to control the amount of heat radiated from the heat insulating container to achieve a low output. It is an object of the present invention to provide a method of operating a battery system using a sodium-sulfur battery, which enables not only operation but also high-power operation and is capable of stable discharge and charge regardless of the external environment temperature.

[0014]

That is, according to the present invention, there is provided a method of operating a battery system using a sodium-sulfur battery, wherein a discharging step and a charging step are repeated with a rest step interposed therebetween. , A battery system composed of a plurality of sodium-sulfur batteries, which is housed in a heat-insulating container and further connected in series and in parallel, is housed in a container made of a heat insulating material, and ventilation provided in the container. The apparatus provides a method of operating a battery system using a sodium-sulfur battery that regulates the temperature in the container.

In the present invention, the ventilation device may be an exhaust fan and an intake fan, or may be an intake fan and a ventilation hole.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, sodium-
A battery system using a sulfur battery is operated while being housed in a container made of a heat insulating material provided with a ventilation device.

Each module battery that constitutes the battery system is itself housed in a heat insulating container, but by further hermetically housing the battery system itself in a container made of a heat insulating material, it is possible to restrict the entry and exit of air from the outside. It is possible to prevent a situation in which the heat radiation amount from the heat insulating container changes depending on the outside air temperature.

Further, by providing a ventilation device in the container accommodating the battery system, it is possible to control the temperature outside the heat insulating container, which in turn makes it possible to control the amount of heat radiated from the heat insulating container, and the internal heat generation amount and heat It becomes possible to perform discharge operation while keeping the balance.

Therefore, high-output operation becomes possible, and even in normal operation, when the outside air temperature is low,
By shutting off the outside air to raise the temperature outside the heat-insulating container and reduce the amount of heat released from the heat-insulating container, it is possible to avoid the situation where the heater heating amount during cycle operation is reduced and the discharge efficiency decreases. it can. Further, even when the temperature of the outside air is high, the temperature outside the heat insulating container is lowered by removing the outside air, the amount of heat released from the outside of the heat insulating container is increased, and the temperature after the end of each cycle is returned to the initial temperature, It is possible to avoid an accelerating temperature rise due to continuous operation.

The container that houses the battery system is
It suffices that it has heat resistance of about 150 ° C., and relatively inexpensive materials such as bricks, calcium silicate, styrofoam, and synthetic resins such as urethane are used. Although the thermal insulation of these materials is not so large, the temperature distribution inside each module battery is generally within ± 5 ° C because it is housed in a heat insulating container with excellent thermal insulation. Even if the temperature distribution is small and the temperature distribution in the container that houses the battery system is somewhat large, it does not affect the characteristics of the battery system. When these materials are used as a container, it is necessary to use them with a thickness of about 20 to 100 mm in order to maintain a certain degree of thermal insulation and mechanical strength. However, unlike the insulated container that requires one for each module battery, it is sufficient to prepare one container for the entire battery system. It does not reduce the density.

As the ventilation device, a fan, a ventilation hole having an automatic opening / closing function, or the like is used, but it is preferable to use an exhaust fan and an intake fan together, or to use an intake fan and an ventilation hole together. The ventilation device is preferably operated or stopped automatically according to the temperature outside the heat insulating container, but may be operated manually.

In addition, the CPU or the like is used to control the operation of the ventilator according to the temperature of the battery, the temperature outside the heat insulating container, etc. along with the start or end of charging or discharging of the sodium-sulfur battery, the operation of the heater, etc. You may control.

[0023]

Hereinafter, the present invention will be described in more detail with reference to the illustrated embodiments, but the present invention is not limited to these embodiments.

An example of a battery system operated by the method of the present invention using an exhaust fan and an intake fan as a ventilation device is shown in FIG.

In FIG. 1, a battery system 1
Is configured by connecting 40 to 50 module batteries in series and parallel, and each module battery is housed in a vacuum heat insulating container 4. The vacuum heat insulating container 4 is configured by sealing a heat insulating material between two thin metal plates and sealing the heat insulating material. The battery system 1 is hermetically housed in a container 5 made of a heat insulating material having a low thermal insulation property, and an exhaust fan 6 and an intake fan 7 are installed on the outer wall of the container 5.

In addition, the battery system 1 of FIG. 1 detects the voltage and current of the module battery, detects the temperature inside the module battery and the voltage / current monitoring means 9 for controlling the values, and detects the value. The module battery temperature monitoring means 10 to be controlled and the in-container temperature monitoring means 11 for detecting the temperature in the container 5 and controlling the values by adjusting the operations of the exhaust fan 6 and the intake fan 7 are provided. Values such as battery resistance, operating temperature, outside temperature, and output multiple for rated operation are input to the control computer 8, and control signals are output to the control means based on these values.

FIGS. 2A, 2B and 2C show changes in electric power, voltage, and temperature inside the container and inside the module battery at each operation stage when the above-described battery system 1 is operated under rated conditions. Shown in. 3 (a) shows changes in the electric power, the voltage, and the temperature inside the container and the module battery at each operation stage during the double output operation, respectively.
(B) and (c). The temperature inside the container 5 is maintained at 80 to 100 ° C during rated operation, and 40% during double output operation.
By maintaining the temperature at -60 ° C, the internal heat generation amount during the rated operation and the double output operation are controlled, and the heat balance is set to zero. Further, in a standby state such as Saturdays, Sundays, and holidays when the power storage system is not used, the temperature in the container 5 is set to 120 to 1
By maintaining the temperature at 50 ° C, the electric power of the heater that keeps the inside of the battery warm is reduced. Note that these temperatures need to be appropriately changed depending on the material and thickness of the container 5, the material of the wiring material, and the like.

[0028]

According to the present invention, a battery system using a sodium-sulfur battery is housed in a container made of a heat insulating material, and a ventilation device is installed in the container, so that the temperature inside the container is adjusted. This makes it possible to adjust the temperature of the sodium-sulfur battery by controlling the amount of heat released from the heat insulating container. Therefore, it is possible to perform high-output operation and obtain stable discharge and charge efficiency that is not affected by the external temperature.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a battery system.

2A and 2B are graphs showing a change in the value of electric power at each operation stage during rated operation, a graph showing a change in the value of voltage in FIG. 2, and a temperature inside the container and a temperature inside the module battery. It is a graph which shows the change of.

3A and 3B are graphs showing changes in the value of electric power at each operation stage during double output operation, FIG. 3B is a graph showing changes in the value of voltage, and FIG. 3 is a graph showing changes in temperature of the.

[Explanation of symbols]

1 ... Battery system, 2 ... Module battery, 3 ...
・ Sodium-sulfur battery, 4 ... Vacuum insulation container, 5 ... Container, 6 ... Exhaust fan, 7 ... Intake fan, 8 ... Control computer, 9 ... Voltage / current monitoring means 10 ... Module battery temperature monitoring means, 11 ... In-container temperature monitoring means,
12 ... AC / DC converter.

Claims (3)

[Claims] 1. A method of operating a battery system using a sodium-sulfur battery, wherein a discharging stage and a charging stage are repeated with a rest stage interposed therebetween, the method comprising: a plurality of sodium-sulfur batteries, A battery system comprising a plurality of module batteries connected in series and parallel to each other is housed in a container made of a heat insulating material, and the temperature inside the container is adjusted by a ventilation device provided in the container. A method of operating a battery system using a sulfur battery. 2. The method for operating a battery system using a sodium-sulfur battery according to claim 1, wherein the ventilation device is an intake fan and an exhaust fan. 3. The method of operating a battery system using a sodium-sulfur battery according to claim 1, wherein the ventilation device is an intake fan and a ventilation hole.