JP2005149774A - Module or module assembly of sodium-sulfur battery, and method of detecting depth of discharge of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a module or a module assembly of a sodium-sulfur battery, and a method of detecting depth of discharge of the same. <P>SOLUTION: The module 106 is formed by housing in a keep-warm vessel 102 a battery group 105 formed by electrically connecting a plurality of sodium-sulfur batteries each composed of a negative electrode chamber housing sodium, a positive electrode chamber housing sulfur or/and sodium polysulfide, and a solid electrolyte separating the negative electrode chamber from the positive electrode chamber, or, the module assembly is formed by electrically connecting modules to each other. A voltage measuring device 104 measuring the voltage of a sodium-sulfur battery 100 out of the sodium-sulfur batteries included in the module or the module assembly, of which, a quantity of sulfur included in the positive electrode chamber is smaller than those of the other batteries; or measuring the voltage of the battery group or the module including one or a plurality of batteries containing a smaller quantity of sulfur; is provided. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a sodium-sulfur battery module or module assembly suitable for use in a power storage device, an emergency power supply, an uninterruptible power supply, or an electric vehicle, and a discharge depth detection method thereof.

  Liquid sodium in the negative electrode chamber, positive electrode active material such as sulfur and sodium polysulfide in the positive electrode chamber, and the negative electrode chamber / positive electrode chamber separated by a solid electrolyte made of β-type or β ″ -type beta alumina ceramics Sulfur batteries are attracting attention because of their long life and high energy density, and are expected to be used in power storage devices, emergency power supplies and uninterruptible power supplies, and electric vehicles including hybrid vehicles. When driving, it is common to measure the battery voltage by detecting the battery voltage using the decrease in battery voltage due to the increase in discharge depth, and to control the discharge depth based on this. However, in the conventional detection method, the battery voltage varies due to the characteristic difference between the batteries, the temperature difference between the batteries or the battery temperature changes with time, or the current difference between the parallel batteries varies. If this occurs, there is a problem that the detection accuracy of the depth of discharge by voltage measurement is lowered, which is a particularly serious problem when the capacity of the module or module assembly containing the battery is large. However, the conventional method for detecting the depth of discharge has the drawback that sufficient measurement accuracy cannot be ensured, and if overdischarge occurs due to excessive depth of discharge, the sodium and sulfur contained in sodium polysulfide The ratio increases, the battery container is corroded, the sodium polysulfide is solidified, the battery is deteriorated, and the subsequent operation becomes difficult.

  In order to cope with this problem, as seen in, for example, Japanese Patent Application Laid-Open No. 5-2587779, the discharge depth of some of the batteries constituting the module is made higher than that of other batteries by shifting the position of the discharge depth during operation. A method for detecting the depth of discharge of a module by measuring the voltage of a battery having a large depth of discharge and increasing the depth has been proposed. According to this method, a battery with a large depth of discharge has a merit that it becomes easier to detect the depth of discharge because the voltage drops earlier during discharge than other batteries, but the magnitude of the voltage change with respect to the change in the depth of discharge is advantageous. Is not particularly improved, there remains a problem that the effect of improving the detection accuracy of the depth of discharge by voltage measurement is insufficient.

  It is also possible to measure the voltage of all the sodium sulfur batteries that make up the module or module assembly, and to control the depth of discharge based on the data, but this makes the structure of the voltage measurement device complicated. Thus, there is a drawback that the cost of the battery system increases.

Japanese Patent Laid-Open No. 5-258777

  The present invention provides a sodium-sulfur battery module or module assembly with high discharge depth detection accuracy, and a discharge depth detection method thereof, excluding the above-mentioned drawbacks of the prior art.

  The sodium-sulfur battery module or module assembly of the present invention includes a negative electrode chamber containing sodium, a positive electrode chamber containing sulfur or / and sodium polysulfide, and a solid electrolyte separating the negative electrode chamber / positive electrode chamber. A module in which a battery group in which a plurality of sodium-sulfur batteries are electrically connected is housed in a heat insulating container, or a module assembly in which the modules are electrically connected, which is included in the module or module assembly The amount of sulfur contained in the positive electrode chambers of some of the sodium sulfur batteries is less than the amount of sulfur contained in the positive electrode chambers of other batteries, and the voltage of the sodium sulfur battery having a small amount of sulfur is measured. Or voltage measurement for measuring the voltage of a battery group or module containing one or more sodium-sulfur batteries having a small amount of sulfur. It is characterized in that a location. Note that the amount of sulfur in the positive electrode chamber of the sodium-sulfur battery corresponds to the sum of sulfur contained in the positive electrode chamber and sulfur constituting sodium polysulfide.

  With this structure, a sodium sulfur battery module or a module assembly with high detection accuracy of the depth of discharge is realized.

  Here, all of the plurality of sodium-sulfur batteries constituting the module or module assembly are electrically connected in series, or the battery groups are connected in parallel or in series-parallel, and the module is Or the modules are configured to be connected in parallel or in series and parallel, and the number of sodium sulfur batteries with a small amount of sulfur contained in the battery group or module is parallel. It is desirable for each of the connected battery groups or modules to be equal.

  Further, the depth-of-discharge detection method for the sodium-sulfur battery module or module assembly of the present invention includes a negative electrode chamber containing sodium, a positive electrode chamber containing sulfur or / and sodium polysulfide, and a gap between the negative electrode chamber / positive electrode chamber. A method for detecting the depth of discharge of a module in which a battery group in which a plurality of sodium-sulfur batteries including a separated solid electrolyte are electrically connected is housed in a heat insulating container, or a module assembly in which the modules are electrically connected The depth of discharge detection method of the present invention, wherein the amount of sulfur contained in the positive electrode chamber of some of the sodium sulfur batteries contained in the module or module assembly is greater than the amount of sulfur contained in the positive electrode chambers of other batteries. Decrease and measure the voltage of the sodium sulfur battery with a small amount of sulfur, or one sodium sulfur battery with a small amount of sulfur Measures the voltage of the plurality inclusive battery groups or modules, is characterized by detecting the depth of discharge.

  By this method, a discharge depth detection method with high detection accuracy of the discharge depth of the sodium-sulfur battery module or module assembly is realized.

  Here, all of the plurality of sodium-sulfur batteries constituting the module or module assembly are electrically connected in series, or the battery groups are connected in parallel or in series-parallel to form the module. Or, the modules are configured by connecting the modules in parallel or in series and parallel, and the number of the sodium sulfur batteries with a small amount of sulfur contained in the battery group or module is connected in parallel. It is desirable to be equal in each of the battery groups or modules.

  According to the present invention, it is possible to maintain high detection accuracy of the depth of discharge by measuring the voltage at the time of discharging the battery and measuring the electromotive force, and even when the capacity of the module or module assembly in which the battery is assembled is large. It becomes possible to ensure detection accuracy. Further, even if a temperature difference occurs between the batteries, there is almost no possibility that the batteries are overdischarged, and there is an advantage that the problem of deterioration due to overdischarge of the batteries constituting the module or module assembly does not occur.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 shows an example of the structure of a sodium sulfur battery used in the present invention. In the figure, a bottomed bag tube made of β-type or β ″ -type beta-alumina ceramic is usually used for the sodium ion conductive solid electrolyte 1, but a flat solid electrolyte may be used in some cases. The negative electrode container 2 and the positive electrode container 3 constitute a negative electrode chamber 4 and a positive electrode chamber 5, respectively, together with the solid electrolyte 1, and the materials thereof are Al, Al alloy, Fe, Fe alloy, SUS, or a Co base alloy, Cr / Ordinarily used are those provided with a corrosion-resistant layer mainly composed of Fe alloy, Al / Si alloy, SUS, Cr, C, Mo, etc., and clad material of Al alloy and SUS, etc. The insulating ring 6 is a negative electrode. The container 2 and the positive electrode container 3 are insulated and joined to each other, and the insulating ring 6 is usually made of α-alumina ceramics. Or is integrally sintered with the solid electrolyte 1 using ceramics such as α-alumina or magnesium aluminum spinel, and the negative electrode container 2 or the positive electrode container 3 and the insulating ring 6 are illustrated in FIG. However, a hot press welding method is generally used in which Al or an Al alloy is used as a bonding material, and pressure bonding is performed by heating to a temperature lower than the liquidus temperature or lower than the solidus temperature of the bonding material.

  On the other hand, the sodium container 7 made of SUS or Al alloy installed in the negative electrode chamber 4 contains liquid sodium 8 and is operated by providing the sodium container 7 adjacent to the surface of the solid electrolyte 1. Sometimes the amount of sodium 8 present in the gap between the solid electrolyte 1 and the sodium container 7 can be reduced to ensure safety when the solid electrolyte is broken. Further, the sodium 8 is pushed by gravity or the pressure of an inert gas 9 such as nitrogen gas or Ar gas filled in the sodium container 7, passes through the through-hole 10 provided in the sodium container 7, and the solid electrolyte 1. It is supplied to the gap with the sodium container 7.

  Further, the porous conductive material 11 is housed in the positive electrode chamber 5 and is usually composed of an aggregate of PAN (polyacrylonitrile) -based and pitch-based carbon fibers and carbon particles manufactured by heating at 1300 to 2000 ° C. The The positive electrode chamber 5 is filled with a positive electrode active material 12 made of sulfur or sodium polysulfide, and the positive electrode active material 12 is impregnated in the porous conductive material 11 and contributes to the battery reaction. On the other hand, a porous material 13 is provided between the solid electrolyte 1 and the porous conductive material 11, and the porous material 13 is usually composed of an aggregate of ceramics such as alumina or glass fibers and particles. This porous material 13 has a property of holding an ion conductive active material such as sodium polysulfide constituting the positive electrode active material 12, suppresses an increase in resistance during charging of the sodium sulfur battery, and improves the charge / discharge characteristics of the battery. Has the effect of improving. Here, the amount of sulfur contained in the positive electrode chamber 5 is controlled by adjusting the filling amount of sulfur and sodium polysulfide constituting the positive electrode active material 12. Further, the sulfur amount corresponding to the present invention corresponds to the sum of sulfur contained in the positive electrode chamber 5 and sulfur constituting sodium polysulfide.

FIG. 2 shows an example of discharge characteristics of a sodium-sulfur battery, where the vertical axis indicates the battery voltage during discharge and the horizontal axis indicates the depth of discharge. In addition, the discharge characteristics of different batteries are indicated by 20 and 21. The discharge characteristics 20 is a battery having a small amount of sulfur in the positive electrode chamber 5, and the discharge characteristics 21 is a discharge characteristic of a battery having a large amount of sulfur in the positive electrode chamber 5. Represents. That is, in the sodium-sulfur battery, the discharge depth increases as the sodium 8 in the negative electrode chamber 4 moves into the positive electrode chamber 5 through the solid electrolyte 1. The composition of substance 12 is S →
The battery electromotive force is constant in the range from S to Na ₂ S ₅ , as Na ₂ S ₅ → Na ₂ S ₄ → Na ₂ S _3. The electromotive force is reduced. Since a sodium-sulfur battery is generally operated until the composition of the positive electrode active material is such that the amount of sulfur is less than that of Na ₂ S ₅ , measurement of the battery voltage during discharge or battery voltage when discharge is stopped That is, the depth of discharge can be determined by measuring the electromotive force.

  Here, the battery voltage at the time of discharge is a value obtained by subtracting battery resistance × battery current from the electromotive force. If the discharge depth exceeds a certain value as shown in FIG. 2, the battery voltage at the time of discharge or not shown However, the electromotive force decreases as the depth of discharge increases, and the decrease in battery voltage and electromotive force during discharge starts with a smaller depth of discharge as the amount of sulfur in the positive electrode chamber 5 decreases. Further, the amount of change in battery voltage and electromotive force during discharge with respect to the change in depth of discharge (Ah) increases as the amount of sulfur in the positive electrode chamber 5 decreases, and as a result, the battery voltage and electromotive force during discharge are increased. The detection accuracy of the depth of discharge by measurement is improved. The depth of discharge of the sodium-sulfur battery module or module assembly can be detected by using the measured battery voltage or the relationship between the electromotive force and the depth of discharge.

  Furthermore, when the discharge current of the battery is constant, a change in electromotive force or a change in discharge depth can be easily obtained by measuring the battery voltage during discharge. Moreover, when operating by changing the discharge current, the product of the battery resistance and the discharge current can be added to the measured battery voltage to determine changes in electromotive force and discharge depth. In any of these cases, a battery with a small amount of sulfur has a large change in battery voltage or electromotive force at the time of discharge due to a change in the depth of discharge. The detection accuracy of the depth of discharge is improved by measuring the electromotive force.

  FIG. 3 shows a structural example of the sodium-sulfur battery module 106 of the present invention. In this figure, sodium-sulfur batteries 100 and 101 are the same as those shown in FIG. 1, and as shown in the figure, a plurality of batteries are connected in series and parallel to each other in a heat insulating container 102 made of a heat insulating container or the like. Is stored. Although not shown, a heater for maintaining the sodium sulfur batteries 100 and 101 at the operating temperature is provided in the heat insulating container 102. Here, the amount of sulfur contained in the positive electrode chamber 5 of the sodium sulfur battery 100 is adjusted to be smaller than the amount of sulfur contained in the positive electrode chamber 5 of the sodium sulfur battery 101. In addition, the electrical wiring 103 electrically connects the batteries or between the battery and an external circuit, and the voltage measuring device 104 detects the discharge depth of the sodium sulfur battery by measuring the voltage. Thus, in FIG. 3, the sodium sulfur battery 100 and the plurality of sodium sulfur batteries 101 are connected in series to form a battery string, that is, a series battery group 105, and a plurality of these battery groups are connected in parallel. A battery block is formed, and this battery block and another battery block made of the sodium-sulfur battery 101 are connected in series to form a module 106. Further, the voltage of the sodium sulfur battery 100, that is, the battery voltage and electromotive force at the time of discharging are measured by the voltage measuring device 104, and the depth of discharge is detected.

  4 and 5 show examples of the structure of the sodium-sulfur battery module assembly according to the present invention, and the same reference numerals as those in FIG. 3 denote the same parts.

  In FIG. 4, a module 106 is formed by a battery group 105 in which a plurality of sodium-sulfur batteries 100 and 101 are connected in series, and modules are connected in series so that a plurality of batteries are all connected in series. The voltage of the sodium sulfur battery 100 with a small amount of sulfur is measured, and the depth of discharge is evaluated. As described above, by measuring the voltage of only the battery with a small amount of sulfur, the module or module assembly can be obtained by measuring the voltage of only a part of the battery constituting the module or module assembly, or by measuring the voltage of only a part of the battery constituting the module or module assembly. The overall depth of discharge can be evaluated, and the cost can be reduced by simplifying the voltage measuring device 104. In some cases, the depth of discharge can be evaluated by measuring the voltage of a battery group 105 provided with one or more sodium-sulfur batteries 100 having a small amount of sulfur or a module 106 made of this battery group.

  Here, in the case of voltage measurement of the module, since the electrical wiring for voltage measurement can be attached outside the module, the structure of voltage measurement is simplified compared to the voltage measurement inside the module, and the cost is low. There is an advantage that can be made. Moreover, as the battery group 105 for measuring the voltage, a structure in which a plurality of batteries are connected in series and parallel is possible, but it is desirable to use a battery group connected in series as shown in FIG. 3 and FIG. Therefore, there is an advantage that the current between the batteries included in the battery group to be measured becomes constant and the detection accuracy of the depth of discharge is improved. Further, the same applies to the voltage measurement of the module 106, and it is desirable to use a module composed of a plurality of batteries connected in series as shown in FIG. 4 in order to improve the detection accuracy of the depth of discharge.

Further, when measuring the total voltage of the sodium sulfur batteries 100 and 101, the effect of improving the detection accuracy of the depth of discharge shown in FIG. 2 is reduced, so the number of combinations of the sodium sulfur batteries 100 and 101 is reduced. Optimization is necessary. Here, by increasing the number of sodium-sulfur batteries 100, for example, by making all the batteries constituting the battery group or module whose voltage is measured into the sodium-sulfur battery 100, the detection accuracy of the depth of discharge is improved. On the other hand, when the number of sodium-sulfur batteries 100 increases, there is a drawback that the discharge capacity of the module or the module polymer decreases, and it is desirable to reduce the number of sodium-sulfur batteries 100 as much as possible in order to improve the discharge capacity. In particular, it is desirable not to include the sodium-sulfur battery 100 as a battery group or a module included in a portion where voltage is not measured.

In FIG. 5, modules similar to those shown in FIG. 4 are connected in series and parallel to form a module assembly, and the sodium-sulfur battery 100, which is installed in the module 106 in series with other batteries, The voltage 100 'is measured by the voltage measuring devices 104 and 104', respectively. A plurality of sodium-sulfur batteries 100,
It is also possible to measure 100 'voltage sequentially. Although not shown, a plurality of sodium sulfur batteries 100 and 100 'having a small amount of sulfur are connected in series to form a battery group 105, and the total voltage of the plurality of sodium sulfur batteries 100 and 100' is measured. It is also possible to detect the depth of discharge of the battery, module or module assembly by measuring the voltage of one of the plurality of sodium-sulfur batteries 100 and 100 'connected in series. Furthermore, the voltage measurement device 104 or 104 ′ measures the voltage at the time of charging and discharging of the battery, and based on this, the charge / discharge depth of the module or module assembly is controlled, or the presence or absence of battery damage is detected. It is also possible to measure the electromotive force when the current is stopped to detect the depth of discharge of the battery, module or module assembly.

  In the present invention, since the battery voltage and electromotive force during discharge of the sodium sulfur battery 100 with a relatively small amount of sulfur in the positive electrode chamber 5 are measured, the slope of the battery voltage with respect to the depth of discharge shown in FIG. That is, there is an advantage that the change rate of the battery voltage due to the change of the discharge depth and the change rate of the electromotive force (not shown) become large, and the detection accuracy of the discharge depth can be improved. As a result, the detection accuracy of the depth of discharge by voltage measurement is kept relatively high even when the temperature difference between the batteries or the battery temperature changes with time in the module or module assembly, or the current difference between the parallel batteries occurs. Therefore, it is possible to ensure the detection accuracy of the depth of discharge even when the capacity of the module or module assembly in which the batteries are assembled is large. Moreover, since the battery voltage and electromotive force at the time of discharge of the sodium-sulfur battery 100 having a small amount of sulfur is earlier than that of the other sodium-sulfur battery 101 having a large amount of sulfur, this voltage is measured to discharge the module or the module assembly. If the depth is controlled, even if there is a temperature difference between the batteries, there is almost no possibility of other batteries being overdischarged, and there is no problem of deterioration due to overdischarge of the batteries constituting the module or module assembly. There is also an advantage. In addition, as the sodium sulfur battery 100 with a small amount of sulfur to be used, it is advantageous to use a battery having the same structure as that of other batteries and having only a small amount of sulfur added in terms of simplifying battery manufacture. Depending on the case, the sodium-sulfur battery 100 may be a relatively small battery having a smaller battery volume than other batteries.

  In addition, when battery groups obtained by connecting a plurality of batteries in series or / and in parallel are connected in parallel, or when modules are connected in parallel, sodium containing a small amount of sulfur contained in the battery groups and modules. It is desirable that the number of sulfur batteries 100 be the same for each battery group or module in parallel. For example, as shown in FIG. 3, the number of sodium sulfur batteries 100 with a small amount of sulfur contained in the battery group 105 is set to the same number for each battery group connected in parallel, or a plurality of sodium sulfur batteries 100 as shown in FIG. When the modules are connected in parallel to form a module assembly, the number of sodium sulfur batteries 100 or 100 'with a small amount of sulfur contained in the battery group constituting each module 106 is connected in parallel. The same number is desirable for each module. By doing this, the discharge characteristics of each battery group and each module connected in parallel are almost equal, the currents flowing through each battery group and each module are almost equal, and the difference in discharge depth is less likely to occur. In addition, the characteristics of the module assembly are stabilized, and the detection accuracy of the depth of discharge is improved.

Further, the voltage of the sodium-sulfur battery 100 included in one battery group 105 as shown in FIG. 3 or the voltage of one battery group including the sodium-sulfur battery 100 as shown in FIG. Measuring the voltage of the contained sodium sulfur battery 100 and the voltage of one module 106 comprising the battery group including the sodium sulfur battery 100, that is, a part or all of the batteries constituting one battery group or one module By measuring the battery voltage and electromotive force at the time of discharge, it becomes possible to improve the detection accuracy of the discharge depth of the entire module or the entire module assembly, and the cost can be reduced by simplifying the detection of the discharge depth.

In addition, as shown in FIG. 5, the battery voltage at the time of discharge of each of the battery groups 105, modules 106, etc. connected in parallel with a small amount of sulfur such as the sodium sulfur batteries 100, 100 ′ is measured. In this way, the influence of the difference in current between the battery groups and modules connected in parallel can be measured, and the detection accuracy of the discharge depth of the module or module assembly can be improved.

  Further, in order to particularly increase the measurement accuracy of the depth of discharge, as shown in FIG. 4, all the batteries are connected in series to form a module or a module assembly, and a sodium sulfur battery with a small amount of sulfur contained therein. The voltage of 100 may be measured, and depending on the case, the voltage of a battery group or module partially including the sodium sulfur battery 100 can also be measured. By doing so, since the currents flowing through all the batteries are equal, the detection accuracy of the discharge depth of the module or module assembly is particularly improved. Also, when all the batteries that make up a module or module assembly are connected in series, even if there are temperature differences, electrical resistance differences, sulfur content differences, etc., between the batteries in the module There is no problem that current flows or current difference occurs, and there are advantages that the detection accuracy of the depth of discharge is improved and the efficiency and capacity of the module and module assembly are kept high.

Although it is possible to install a plurality of sodium sulfur batteries 100 with a small amount of sulfur in the battery group or module and measure these voltages, in order to increase the battery capacity of the module or module assembly, It is desirable to reduce the number of sodium-sulfur batteries with a small amount of sulfur as much as possible. As shown in FIG. 4, the number of batteries with a small amount of sulfur contained in the battery group 105 and the module 106 is one, and What is necessary is just to measure a voltage. That is, in the sodium-sulfur battery 100 with a small amount of sulfur, the composition of the positive electrode active material reaches Na ₂ S ₄ and Na ₂ S ₃ earlier as the depth of discharge increases as compared with the sodium-sulfur battery 101 with a large amount of sulfur. As a result, the battery capacity is reduced, and if the number of batteries with a small amount of sulfur is too large, the battery capacity of the module or module assembly is likely to be reduced. It is desirable to reduce the number of sodium-sulfur batteries 100 having a small amount.

  Further, as seen in FIG. 5, in a module assembly in which modules connected in series are connected in parallel and further connected in series, the sodium sulfur battery 100 having a small amount of sulfur in some of the modules connected in series. By measuring the voltage, the depth of discharge of the module assembly can be detected. In this case, the voltage of the sodium-sulfur batteries 100 and 100 'can be measured for each of the battery groups constituting the module of the parallel unit as shown in FIG. 5, but as described with reference to FIG. The voltage may be measured.

  In addition, since the number of batteries to be filled in a module is generally large, although not shown in the figure, a sodium sulfur battery 100 with a small amount of sulfur is inserted into only one of the modules in a parallel unit, and the voltage of the battery is measured. However, all the batteries in the other modules can be the sodium sulfur battery 101 having a large amount of sulfur. In this case, in principle, the discharge characteristics between the parallel modules are different, so the currents flowing in the battery group connected in parallel are slightly different, resulting in a difference in the discharge depth, but when the number of batteries constituting the module is large. The difference in the discharge characteristics between the parallel modules is reduced, so that no problem occurs in detecting the discharge depth of the module assembly. On the other hand, since the number of modules including the sodium-sulfur battery 100 having a small amount of sulfur is reduced, there is an advantage that the capacity of the module assembly is increased.

  Similar effects can be expected in the case of FIG. 3, and when the number of batteries forming the battery group 105 is large, even if the sodium sulfur battery 100 with a small amount of sulfur exists in only one of the battery groups, it is connected in parallel. The difference between the currents of the battery groups, that is, the difference between the currents flowing through each battery group is reduced, and the depth of discharge of the module can be detected accurately by measuring the voltage of the sodium-sulfur battery 100, and the capacity of the module can be kept high. There is. However, in order to particularly improve the detection accuracy of the depth of discharge, it is desirable that the number of sodium sulfur batteries 100 with a small amount of sulfur contained in a plurality of battery groups connected in parallel be equal in each battery group.

As a specific example, as shown in FIG. 4, a module assembly is formed by connecting modules 106 including a battery group 105 in which a plurality of sodium sulfur batteries are connected in series to form a module assembly, and the positive electrode of the sodium sulfur battery 100 in one module. The amount of sulfur contained in the chamber 5 is 10% less than that of the other sodium-sulfur batteries 101, the voltage of the sodium-sulfur battery 100 is measured, and based on this, charging / discharging of the module assembly is controlled, The depth of discharge was detected. As a result, it is possible to detect the depth of discharge relatively accurately even if charging and discharging are repeated or the temperature between modules is different, and since the battery is not overdischarged, the battery is highly reliable, The advantage of being able to extend the life of the body was obtained.

Sectional drawing which shows the structural example of the sodium sulfur battery used for this invention. The characteristic view which shows the discharge characteristic example of the sodium sulfur battery of this invention. The schematic diagram which shows the structural example of the sodium sulfur battery module of this invention. The schematic diagram which shows the structural example of the module assembly of this invention. The schematic diagram which shows the structural example of the module assembly of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Solid electrolyte, 2 ... Negative electrode container, 3 ... Positive electrode container, 4 ... Negative electrode chamber, 5 ... Positive electrode chamber, 6 ... Insulating ring, 7 ... Sodium container, 8 ... Sodium, 9 ... Inert gas, 10 ... Through-hole, DESCRIPTION OF SYMBOLS 11 ... Porous conductive material, 12 ... Positive electrode active material, 13 ... Porous material, 20, 21 ... Discharge characteristic, 100,
DESCRIPTION OF SYMBOLS 100 '... Sodium-sulfur battery with little sulfur amount, 101 ... Sodium-sulfur battery with much sulfur amount, 102 ... Insulation container, 103 ... Electric wiring, 104, 104' ... Voltage measuring device, 105 ... Battery group, 106 ... Module.

Claims (6)

  A plurality of sodium-sulfur batteries including a negative electrode chamber containing sodium, a positive electrode chamber containing sulfur or / and sodium polysulfide, and a solid electrolyte separating the negative electrode chamber / positive electrode chamber were electrically connected. A module in which a battery group is housed in a heat insulating container, or a module assembly in which the modules are electrically connected, and the positive electrode of a part of the sodium-sulfur battery included in the module or module assembly The amount of sulfur contained in the room is made smaller than the amount of sulfur contained in the positive electrode chamber of another battery, and the voltage of the sodium sulfur battery with a small amount of sulfur is measured, or the sodium sulfur battery with a small amount of sulfur is 1 A sodium-sulfur battery module or module comprising a voltage measuring device for measuring the voltage of a battery group or module including one or more batteries Yuru assembly.   2. The sodium sulfur battery module or module assembly according to claim 1, wherein all of the plurality of sodium sulfur batteries constituting the module or module assembly are electrically connected in series.   In Claim 1, the battery groups are connected in parallel or series-parallel to form the module, or the modules are connected in parallel or series-parallel to form the module assembly, A sodium-sulfur battery module or module assembly, wherein the number of sodium sulfur batteries with a small amount of sulfur contained in the battery group or module is the same in each of the battery groups or modules connected in parallel.   A plurality of sodium-sulfur batteries including a negative electrode chamber containing sodium, a positive electrode chamber containing sulfur or / and sodium polysulfide, and a solid electrolyte separating the negative electrode chamber / positive electrode chamber were electrically connected. A method for detecting a depth of discharge of a module in which a battery group is housed in a heat insulation container, or a method for detecting a depth of discharge of a module assembly in which the modules are electrically connected, wherein the sodium contained in the module or module assembly The amount of sulfur contained in the positive electrode chamber of some of the sulfur batteries is less than the amount of sulfur contained in the positive electrode chambers of other batteries, and the voltage of the sodium sulfur battery having a small amount of sulfur is measured, or The depth of discharge is detected by measuring the voltage of a battery group or module containing one or more sodium-sulfur batteries having a low sulfur content. Discharge depth detecting method of the sodium-sulfur battery module or module assembly.   5. The method for detecting the depth of discharge of a sodium sulfur battery module or module assembly according to claim 4, wherein all of the plurality of sodium sulfur batteries constituting the module or module assembly are electrically connected in series. 5. The battery group according to claim 4, wherein the battery groups are connected in parallel or series-parallel to form the module, or the modules are connected in parallel or series-parallel to form the module assembly. Alternatively, the number of sodium sulfur batteries with a small amount of sulfur contained in the module is made equal in each of the battery groups or modules connected in parallel, and the depth of discharge detection method for a sodium sulfur battery module or module assembly is provided. .

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