JP3505111B2 - Operation method of sodium-sulfur battery - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for operating a sodium-sulfur battery, which enables the sodium-sulfur battery to be discharged or charged to an allowable limit without being overdischarged or overcharged.

[0002]

2. Description of the Related Art Sodium-sulfur batteries (hereinafter referred to as "Na
S battery ". ) Is a device for leveling power demand with a large difference between daytime and nighttime, especially as a so-called peak cut power storage device that supplies power during the time when the power demand in the summer is rapidly increasing, or for emergency use during natural disasters. As a power source
Practical applications are expected for various other uses.

The NaS battery is a NaS battery block in which a plurality of unit cells in which a plurality of unit cells are connected in series (hereinafter, referred to as “NaS battery string”) are connected in parallel to form a NaS battery block. Connecting multiple blocks N
It is used as a NaS battery power storage system by forming an aS battery module and forming a circuit together with an inverter and the like.

As a method of operating such a NaS battery module, conventionally, there has been adopted a method in which a charging / discharging cycle of charging for a predetermined time at night and discharging for a predetermined time during the day is repeated every day. Here, as a power source for power storage such as peak cut, it is an operating method that is desirable to discharge or charge current to an allowable limit within a range that does not damage the battery, but such an operating method has been found so far. Not not. Therefore, an operation method has been performed in which a charging / discharging cycle is repeated such that the battery is charged for a predetermined time at night, for example, 10 hours, and discharged for a predetermined time, for example, 8 hours, in a safe range that does not damage the battery.

[0005]

By the way, in the NaS battery, as the discharge progresses, sodium polysulfide (hereinafter, referred to as “Na ₂ S _X ”) is generated on the anode side of each unit cell, and the cathode. When the discharge progresses until the sodium is depleted,
The subsequent charge / discharge becomes impossible. When the discharge progresses and the composition of Na ₂ S _X of the anode becomes Na ₂ S _2.7 , a solid phase is generated at a temperature of 350 ° C. or lower, and further discharge cannot be performed.
Further, there is a problem that metallic sodium does not return to the cathode during charging. Therefore, it is usually used just before the cathode is deficient in sodium or as a composition of Na ₂ S _x , for example, Na.
_The discharge limit is about ₂ S ₃ .

Since the electromotive force of a single cell is determined by the activity of Na ₂ S _X , its value varies depending on the discharge state. However, when the discharge state is shallower than the discharge depth corresponding to Na ₂ S ₅ , the Sulfur is present and held constant at about 2.08 V, which corresponds to the sulfur potential. However, when the depth of discharge becomes deeper than this, the electromotive force gradually decreases, and for example, at the end of discharge, for example, Na
_{At 2} S ₃ , the open circuit voltage is 1.78V.

Therefore, it is considered that discharging can be performed until the single-circuit open circuit voltage reaches 1.8 V. However, in a power supply for power supply, it is actually impossible to stop the discharge during discharging and measure the open circuit voltage. The operating voltage during discharge is
It becomes lower than the open circuit voltage by the product of internal resistance and discharge current,
Since the internal resistance during discharge changes due to various factors such as temperature, it is not possible to grasp the corresponding open circuit voltage from the operating voltage during discharge.

Furthermore, since the internal resistance changes with time due to corrosion of the anode container, it is impossible to grasp the corresponding open circuit voltage from the operating voltage during discharge. As described above, no operating method has been found so far as to at what point from the operating voltage during discharging the discharging can be stopped up to the allowable limit without damaging the battery.

On the other hand, also in the case of charging, similarly, since the internal resistance during charging changes due to various factors, an operating method for charging to an allowable limit without causing damage to the battery due to overcharging has been known.

[0010]

Means for Solving the Problems The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to discharge or charge NaS that can be discharged or charged to an allowable limit without being overdischarged or overcharged. It is to provide a method of operating a battery.

That is, according to the present invention, there is provided an operating method for discharging a sodium-sulfur battery in which a plurality of unit cells are connected in series, in which the temperature during discharging of the sodium-sulfur battery is measured and discharge is performed. The depth is counted, and the discharge is stopped when the operating voltage V across both ends of the sodium-sulfur battery during discharging reaches a correction voltage V _L that takes into account the temperature-dependent correction of the internal resistance and the correction of the discharge depth. A method for operating a sodium-sulfur battery is provided.
Here, the correction voltage V _L is V _L = V _O × N−I × R ₁ × K ₁ ×
It is represented by K ₂ .

Further, according to the present invention, there is provided an operating method for discharging a sodium-sulfur battery, in which a plurality of unit cells formed by connecting a plurality of unit cells in series are further connected in parallel. The temperature of the sulfur battery during discharge is measured, the depth of discharge is counted, and the defective cell is detected.
The operating voltage V across the sodium-sulfur battery during discharging has reached a correction voltage V _L that takes into account the correction of the internal resistance due to the temperature and the depth of discharge, and the correction due to the change in the number of parallels due to the failure of the single battery. A method for operating a sodium-sulfur battery, characterized in that the discharge is stopped at a time point. Here, the correction voltage V _L is V _L = V _O × N−I × R ₁ ×
It is represented by K ₁ × K ₂ × K ₃ .

Further, according to the present invention, there is provided an operating method for discharging a sodium-sulfur battery, which is formed by connecting a plurality of unit cells formed by connecting a plurality of unit cells in series, in parallel with each other. The temperature during discharging of the sulfur battery is measured, the depth of discharge is counted, the defective single battery is detected, and the number of charge / discharge and / or the number of operating days is further counted, and the both ends of the sodium-sulfur battery during discharging are counted. The operating voltage V has reached the correction voltage V _L , in which the correction by the temperature of the internal resistance, the correction by the depth of discharge, the correction by the change in the number of parallels due to the failure of the unit cell, and the correction by the number of charge / discharge and / or the number of operating days are taken into consideration. A method for operating a sodium-sulfur battery, characterized in that the discharge is stopped at a time point. Here the correction voltage V _{L is, V L = V O × N} -I × R 1 × K 1 × K 2 × K 3 ×
(K ₄ or K ₅ or K ₄ × K ₅ )), and R = A × as a correction coefficient K ₄ according to the number of charging / discharging times of the internal resistance and / or a correction coefficient K ₅ according to the number of operating days of the internal resistance. D ^1/2
It is preferable to use the correction coefficient obtained from + R ₁ .

Further, according to the present invention, there is provided an operating method for charging a sodium-sulfur battery, which is formed by connecting a plurality of unit cells in series, wherein the temperature during charging of the sodium-sulfur battery is measured and charging is performed. counting the depth, sodium the - sulfur operating voltage V across the charging of the battery stops charging when it reaches the correction voltage V _H obtained by adding the correction by the correction state of charge according to the temperature of the internal resistance A method for operating a sodium-sulfur battery is provided. Here, the correction voltage V _H is V _H = V _h × N + I × R ₁ × K ₁ ×
It is represented by C.

Further, according to the present invention, there is provided an operating method for charging a sodium-sulfur battery, which is formed by connecting a plurality of unit cells in which a plurality of unit cells are connected in series to each other in parallel. Measure the temperature during charging of the sulfur battery,
The depth of charge is counted, a defective single cell is detected, and the operating voltage V across the sodium-sulfur battery during charging is detected.
However, the charging is stopped when the correction voltage V _H is reached, which takes into account the correction of the internal resistance according to the temperature, the correction of the depth of charge, and the correction of the change in the number of parallels due to the failure of the single battery. Driving method is provided. Here, the correction voltage V _H is V _H = V _h × N + I × R ₁ ×
It is represented by K ₁ × C × K ₃ .

Further, according to the present invention, a plurality of unit cells are provided.
Connect more than one unit cell group connected in series in parallel
Is the operating method for charging a sodium-sulfur battery
Measure the temperature during charging of the sodium-sulfur battery and
The depth of electricity is counted, the defective cell is detected, and
By counting the number of discharges and / or the number of operating days,
The operating voltage V across the lithium-sulfur battery during charging is
Compensation by temperature of part resistance and compensation by depth of charge and unit cell
And charge / discharge frequency
And / or correction voltage V with correction based on the number of operating days_HTo
Naturi, characterized by stopping charging when it reaches
A method of operating a Mu-Sulfur battery is provided. Correction voltage here
Pressure V_HIs V_H= V_hXN + IxR₁× K₁× C × K₃× (K
_FourOr K_FiveOr K_Four× K_Five), Is represented by
Correction coefficient K depending on the number of discharges_FourAnd / or internal resistance operation
Correction coefficient K depending on the number of days_FiveAs R = A × D^{1 / 2}+ Bx
D + R₁It is better to use the correction factor obtained from
Good

Further, according to the present invention, a plurality of unit cells are provided.
Relating to the charging of sodium-sulfur batteries connected in series
The operating method, which is the temperature during charging of the sodium-sulfur battery
Of the battery during the charging of the sodium-sulfur battery.
The operating voltage V between the ends is corrected and charged by the temperature of the internal resistance.
Correction voltage V with the addition of voltage correction_HWhen reached
Sodium-sulfur battery characterized by stopping charging at
A method of operating the pond is provided. Here, the correction voltage V_HIs
V_H= (V_h+ Α) × N + I × R₁× K ₁It is represented by.

Further, according to the present invention, there is provided an operating method for charging a sodium-sulfur battery, which is formed by connecting a plurality of unit cells formed by connecting a plurality of unit cells in series, in parallel with each other. The temperature during charging of the sulfur battery is measured, and a defective single battery is detected, and the operating voltage V across the sodium-sulfur battery during charging is corrected by the internal resistance temperature and the end-of-charge polarization voltage correction. There is provided a method for operating a sodium-sulfur battery, characterized in that the charging is stopped when the correction voltage _VH , which takes into account the correction due to the change in the number of parallels due to the failure of the single battery, is reached. Here, the correction voltage V
_H is represented by V _H = (V _h + α) × N + I × R ₁ × K ₁ × K ₃ .

Further, according to the present invention, there is provided an operating method for charging a sodium-sulfur battery, which is formed by connecting a plurality of unit cells in which a plurality of unit cells are connected in series to each other in parallel. The temperature during charging of the sulfur battery is measured, the defective single battery is detected, and the number of charging / discharging times and / or the number of operating days is further counted, so that the operating voltage V across the sodium-sulfur battery during charging is Charging is stopped at the time when the correction voltage V _H , which takes into account the correction of the internal resistance with temperature, the correction of the polarization voltage at the end of charging, the correction with the change in the number of parallels due to the failure of the unit cell, and the correction with the number of charge / discharge and / or the number of operating days A method for operating a sodium-sulfur battery is provided. Here, the correction voltage V _H is V _H = (V _h
+ Α) × N + I × R ₁ × K ₁ × K ₃ × (K ₄ or K ₅ or K ₄ × K ₅ ), and the correction coefficient K ₄ and / or the operation of the internal resistance depending on the number of charging and discharging of the internal resistance. As the correction coefficient K ₅ based on the number of days, it is preferable to use the correction coefficient obtained from R = A × D ^1/2 + B × D + R ₁ .

Various parameters used in obtaining the correction voltage V _H or V _L in the above-described operating methods of the sodium-sulfur battery are as follows: V _O : discharge end design open circuit voltage of a single battery, N: single battery series Number, I: current,
R ₁ : initial internal resistance, K ₁ : correction coefficient of internal resistance depending on temperature, K ₂ : correction coefficient of internal resistance depending on discharge depth,
K _3: The ratio of the unit cell number group not including a parallel total number a fault cell in the cells groups, K _4: correction coefficient by the number of times of charge and discharge of the internal resistance, K _5: correction coefficient by the driver days internal Resistance, R :
Internal resistance, A and B: constants, D: number of times of charging / discharging (in the case of K ₄ ) or number of operating days (in the case of K ₅ ), V _h : open circuit voltage at the end of charging of single cells, C: depending on the charging depth of the internal resistance Correction coefficient, α (polarization correction voltage after charging): 0.01 V to 0.1
V is shown respectively.

In the NaS battery operating method of the present invention described above, the internal resistance measured after assembly, that is, when the unused NaS battery module is discharged at the rated current for 30 to 60 minutes is referred to as the initial internal resistance. Preferably. Further, the internal resistance measured during the periodic inspection of the sodium-sulfur battery module may be used as the initial internal resistance.
Furthermore, by predicting the amount of change in internal resistance due to various factors,
It is preferable to incorporate the voltage / current control during charging or discharging and perform charging / discharging because more precise control can be performed.

In these inventions, the unit cell or unit cell group is “connected in series” or “connected in parallel”.
Means electrical series connection and parallel connection. Further, as described above, the operating method of the NaS battery of the present invention is the operating method for the NaS battery string and the NaS battery block, and these operating methods are the constituent elements of the NaS battery when operating the NaS battery module. It goes without saying that it can also be used to control strings and / or NaS battery blocks.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, in explaining the operation method of the NaS battery of the present invention, a string 3 in which about 10 unit cells 1 are connected in series as shown in the circuit diagram of FIG. 1A is used. An NaS battery block 4 (10 series × 1) using 100 cells 1 connected in parallel for about 10 rows
0 parallel) is stored in the heat insulating container 2 NaS battery 5
think of.

FIG. 1B is a circuit diagram showing the configuration of the power storage device 6 using the NaS battery 5. The power storage device 6 is a device that discharges or charges the direct current system and the alternating current system of the NaS battery through an inverter, and its configuration is a voltmeter 8 that measures the voltage across the NaS battery 5,
Thermometer 9 for measuring the temperature of NaS battery 5, Ammeter 10 for measuring the current during discharging or charging, Depth counter (not shown) for counting the product of current and discharging time or current and charging time, charging / discharging Number of times (refers to the number of charge / discharge cycles)
A counter (not shown) or a number of operating days counter (not shown) and a detector (not shown) for detecting a failed cell, and information from these various instruments are input into a predetermined calculation formula. It is composed of a control device 15 which calculates based on the above and controls the operation of the inverter.

Next, FIG. 2 shows behaviors of the operating voltage V and the open circuit voltage in one cycle of charging / discharging of the power storage device 6. The open circuit voltage V _a at the start of operation (point a) is the operating voltage V at the start of discharge obtained by dropping the product of the internal resistance R corresponding to the temperature at the start of operation and the current I ₁ at the start of operation at the same time as the start of discharge. _The operating voltage V gradually decreases as the discharge progresses to _b (point b), and the discharge is stopped when the operating voltage V _C at the end of discharge (point c) is reached.

The open circuit voltage V _d at the time of the rest is a voltage that is close to the design open circuit voltage at the end of discharge, and is the product of the discharge end designed open circuit voltage V _O of the unit cell and the number N of series cells (V _O × N). That is, in this case, the voltage is close to 10V _O. The charging operation voltage V _e at the start of operation (point e) at the start of charging is the internal resistance R corresponding to the temperature of the battery at the start of charging.
And the current I ₂ at the start of charging increase. When the charging progresses and the operating voltage V _f at the end of charging is reached (point f), the charging is stopped.

In one cycle of such charging and discharging,
The operating voltage V is the operating voltage V at the end of discharge_CWhether or not
When determining the discharge, first of all
Measure the operating voltage V and the temperature of the battery during discharge at intervals,
Count the depth of discharge. And the initial internal resistance R₁To
As a reference, temperature (correction coefficient due to temperature dependence of internal resistance)
To K₁And ) And the depth of discharge (in the depth of discharge of the internal resistance
Correction coefficient by K₂And ), The internal resistance is₁×
K₁× K₂And the correction voltage V _LTo V_L= V_O× N-
IxR₁× K₁× K₂Ask by. And the operating voltage V
Is the correction voltage V_LWhen the operating voltage V reaches the end of discharge
Operating voltage V_CMeans that you have reached. Also this
The fact is that the operating voltage V is the open circuit voltage V at the end of discharge of the cell._OTo
It means that it has reached.

Here, the correction of the internal resistance due to the temperature will be described in more detail. Figure 3 is the initial internal resistance R _1, the internal resistance R ₁ when was varied battery temperature
The result of measuring the change of is shown. The method of calculating the correction voltage V _L is as described above, but specifically, the temperature T _{(b + 1)} of the battery at the first measurement point (b + 1) after the start of the discharge.
When the internal resistance R _{(b + 1)} corresponding to T _{(b + 1)} is obtained from FIG. 3, the correction coefficient K ₁ of the internal resistance due to the temperature at the measurement point (b + 1) is K ₁ = R _{(b +1)} / R ₁ .

At the next measurement point (b + 2)
Battery temperature T_{(b + 2)}To measure T_{(b + 2)}Internal resistance corresponding to
Anti-R_{(b + 2)}Is calculated from Fig. 3, the measurement point (b + 2)
Correction coefficient K of internal resistance due to temperature₁Is K₁= (R
_{(b + 1)}/ R₁) × (R_{(b +2)}/ R_{(b + 1)}) = R_{(b + 2)}/ R₁When
Become. Below, measure the temperature at each measurement point in sequence,
Calculate the internal resistance corresponding to the
Since the correction coefficient for the partial resistance is calculated and the correction is performed according to the temperature,
is there.

Next, the correction of the internal resistance based on the depth of discharge will be described in detail. The internal resistance R changes as the discharge progresses, because the Na ₂ S _X generated in the anode chamber exhibits different resistance depending on the composition. Since the quality control of each unit cell is strictly performed at the time of production of a practically used NaS battery, the variation in quality among the unit cells is extremely small. Therefore, regarding the correction of the internal resistance depending on the depth of discharge of the battery, it is possible to measure the relationship between the depth of discharge and the internal resistance in a single cell in advance and apply the result to the actual battery.

Therefore, FIG. 4 shows the relationship between the depth of discharge and the internal resistance obtained by measuring with a single cell. As the discharge progresses, the internal resistance gradually rises, reaches a maximum value at the point p, and then decreases, showing a complicated behavior as compared with the temperature dependence of the internal resistance. Here, the active material in the anode chamber at the point p is presumed to be Na ₂ S ₅ .

As described above, after the relationship between the depth of discharge and the internal resistance is measured in advance in the unit cell, the correction voltage V _L is obtained as described above. Specifically, the discharge depth (current × time) is counted with the start of discharge, and the internal resistance r _{(b + 1)} corresponding to the discharge depth at the first measurement point (b + 1) after the start of discharge is obtained from FIG. However, since FIG. 4 shows the values for a single battery, it is necessary to calculate the internal resistance r _{(b + 1)} of the whole battery based on the number of series and parallel numbers of the single battery. Since it can be assumed that the internal resistance of each unit cell has a very approximate value, the correction coefficient K ₂ of the internal resistance due to the depth of discharge at the measurement point (b + 1) is expressed by K ₂ = r _{(b + 1)} / R ₁ . be able to.

Subsequently, the internal resistance r _{(b + 2)} corresponding to the discharge depth at the next measurement point (b + 2) is obtained from FIG. The correction coefficient K ₂ of the internal resistance due to the depth of discharge at the measurement point (b + 2) is K ₂ = (r _{(b + 1)} / R ₁ ) × (r _{(b + 2)} /
r _{(b +} 1)) = a _{r (b + 2) / R} 1. Hereinafter, the internal resistance corresponding to the depth of discharge at each measurement point is sequentially obtained, the correction coefficient of the internal resistance due to the depth of discharge at each measurement point is obtained, and the correction based on the depth of discharge is performed.

As described above, one discharging method in the operating method of the NaS battery of the present invention is an IR drop including a correction based on the initial internal resistance at a predetermined time interval during discharging, with reference to the temperature and the depth of discharge. Of the NaS battery string to the correction voltage V _L obtained by subtracting the corrected IR drop (I × R ₁ × K ₁ × K ₂ ) from the discharge design circuit voltage (V _O × N) of the NaS battery string. The feature is that the discharge is stopped when the operating voltage V during the discharge reaches.

In the case of charging, the method of determining whether or not the operating voltage V at the time of charging has reached the operating voltage V _f at the end of charging can be obtained by the same method as in the case of discharging described above. it can. That is, the temperature during charging of the NaS battery is measured,
Count the charging depth. Based on the initial internal resistance R ₁ , correction by temperature (correction coefficient by temperature dependence of internal resistance is K ₁ ) and correction by depth of charge (correction coefficient by internal charge depth is C). The internal resistance is calculated as R ₁ × K ₁ × C, and the correction voltage V _H at the time of charging is
V _H = V _h × N + I × R ₁ × K ₁ × C Here, it means that the time when the operating voltage V coincides with the correction voltage V _H reaches the operating voltage V _f at the end of charging, that is, the voltage at which charging is stopped, that is, this means that the operating voltage V _f
Means that the designed open circuit voltage V _h at the end of charging of the unit cell is reached.

It should be noted that, as the relationship between the internal resistance and the depth of discharge was examined in obtaining the correction voltage V _L related to discharge, in order to obtain the correction voltage V _H related to charging, the relationship between the internal resistance and the depth of charge was obtained. Need to know in advance. Figure 5
This is the result of measuring the relationship between the internal resistance and the depth of charge by starting charging in a single cell after the operating voltage at the end of discharge is reached. The internal resistance shows a complicated change as the charging progresses, and the state of this change can be used as a basis for calculating the correction voltage V _H.

As described above, one charging method in the operation method of the NaS battery of the present invention is to obtain an IR drop which is corrected at a predetermined time interval during charging with reference to the initial internal resistance and the temperature and the depth of discharge. , Characterized in that charging is stopped when the operating voltage V of the NaS battery string during charging reaches the correction voltage V _{H obtained} by adding IR drop to the open circuit voltage (V _h × N) at the end of charging of the NaS battery string. I am trying.

[0038] Incidentally, by omitting the correction by charging depth, even more charging voltage design open circuit voltage V _h of the cell from 0.01 to 0.
If it is deeply charged in the range of 1 V, it can be deeply charged without damaging the β-alumina tube of the single cell. Such a charge-end polarization correction voltage will be referred to as “α” hereinafter.

That is, the charging method in this case is NaS
For the open circuit voltage (V _h × N) at the end of charging of the battery string,
Predetermined value α in the range of 0.01 to 0.1 V and the number N of unit cells in series
A voltage obtained by adding the product of the initial internal resistance R ₁ in the correction voltage V _H obtained by adding the IR drop obtained by temperature compensation, operating voltage V of the NaS battery strings during charging It is characterized by stopping the charging when it reaches.
Therefore, V _H in this case is V _H = (V _h + α) × N + I
It is expressed as × R ₁ × K ₁ .

Next, an operation method for the NaS battery block 4 shown in FIG. 1 in the case where the unit cell 1 fails for some reason will be described. When the circuit is connected to the circuit including the failed unit cell 1, the NaS string 3 including the failed unit cell becomes an open failure,
Electrically disconnected from the circuit. As a result, the internal resistance of the NaS battery block 4 changes as the number of parallel connections changes. Therefore, when obtaining the correction voltage during discharging or charging, correction due to this factor is necessary.

The correction coefficient K _{3 in} this case is represented by K ₃ = (total number of parallel cell groups) / (number of parallel cell groups not including failed cell). In the case of Figure 1, when all of the cells not failed, when the K ₃ = 10/10 = 1, and the is a single cell fails one becomes K ₃ = 10/9.

In the discharge operation, the initial internal resistance R ₁
The internal resistance is corrected by temperature, the depth of discharge is corrected, and the parallel number is changed, and the operating voltage V across the NaS battery block during discharging reaches the correction voltage V _L. Good to stop. Correction voltage V _L in this _{case, V L = V O × N} -I × R 1 × K 1 × K 2 × K
Given in ₃ .

In other words, in discharging the NaS battery block, the operating method when a failure of a single battery occurs in any of the NaS battery strings, in addition to the correction of the initial internal resistance R ₁ by the temperature and the depth of discharge described above, The IR drop including the correction due to the change in the number of NaS battery strings is also obtained, and the operating voltage V of the NaS battery block is added to the correction voltage V _L obtained by subtracting the IR drop from the discharge end design voltage (V _O × N) of the NaS battery string. It is characterized by stopping the discharge when it reaches.

It should be noted that the charging method when a failure of a single battery occurs in any of the NaS battery strings can be considered in the same manner. That is, the temperature of the NaS battery during charging is measured, the depth of charge is counted, the defective single battery is detected, and the operating voltage V across the NaS battery block during charging is corrected by the temperature of the internal resistance. Charging is stopped when the correction voltage V _H obtained by the correction based on the depth of discharge and the correction based on the change in the parallel number due to the failure of the unit cell is reached. At this time, the correction voltage V _H is V _H = V _h × N
It can be represented by + I × R ₁ × K ₁ × C × K ₃ .

Further, as described above, the correction by the charging depth is omitted, and the charging end polarization correction voltage α (0.01 to 0.1 V) is deeper than the charging voltage design open circuit voltage V _{h of the unit} cell. It is possible to use the correction coefficient K ₃ in the charging method.

The charging method in this case is 0.01 to the designed open circuit voltage (V _h × N) at the end of charge of the NaS battery block.
The voltage obtained by adding the product of the predetermined value in the range of 0.1 V and the number N of cells in series and the temperature of the initial internal resistance R ₁ and the change in the number of parallels due to the failure of the cells are corrected. Correction voltage V obtained by adding the obtained IR drop
Charging may be stopped when the operating voltage V during charging of the NaS battery block reaches _H. Therefore, V in this case
_H is represented by V _H = (V _h + α) × N + I × R ₁ × K ₁ × K ₃ .

Next, an operation method in the case of paying attention to a change in resistance characteristic of the NaS battery with time will be described. A practical NaS battery module can withstand up to about 2500 charge / discharge cycles, and has a useful life of about 15 years. Here, the internal resistance of the battery increases as the charging / discharging cycle progresses or as the number of operating days increases. Therefore, it is preferable to correct the internal resistance based on the number of times of charging and discharging and / or to correct the internal resistance based on the number of operating days.

FIG. 6 shows the relationship between the internal resistance and the number of times of charging and discharging.
FIG. 7 shows the simplified internal resistance during charging and discharging.
It is explanatory drawing which shows a secular change. The internal resistance depends on the number of charge and discharge
The main factor that increases with the number of operating days is the inner surface of the anode container.
Of corrosion of Na, or Na in the anode chamber₂S_XBottom of container
That does not contribute to the battery reaction due to sedimentation to Na ₂S_XOccurrence of
It is estimated that

Therefore, the correction coefficient based on the number of times of charging and discharging the internal resistance is set to K _4, and the correction coefficient based on the number of operating days is set to K ₅
As a result, these values are obtained based on FIGS. 6 and 7, and the correction voltage V _L or V _H is further obtained, and when the operating voltage V during discharging or charging reaches the correction voltage V _L or V _H Stop discharging or charging.

In other words, when the NaS battery module is operated for a long period of time, the internal resistance of the battery changes depending on the charging / discharging cycle or the number of operating days. In addition to the correction due to the change in the number of NaS battery strings when the battery has failed, the IR drop which is corrected according to the charge / discharge cycle and / or the number of operating days is obtained, and the design voltage (V _O × N) at the end of discharge of the NaS battery string is obtained. Therefore, it is preferable to stop the discharge when the operating voltage V of the NaS battery block reaches the correction voltage V _L obtained by subtracting this IR drop.

Here, the correction coefficient K ₄ according to the number of times of charging and discharging
The calculation of the correction coefficient K ₅ based on the number of operating days and / or the number of operating days is conventionally performed as shown in FIG. 7 in which the internal resistance (R) is a linear function in proportion to the elapsed time in both cases of discharging and charging. It was carried out in a simplified manner with the increase in number. Such a method of calculating the correction coefficients K ₄ and K ₅ is sufficiently effective in a short period of a certain range, and has not caused any serious trouble in operation until now. However, in order to establish a more efficient NaS battery operating condition, it is necessary to more accurately grasp the secular change of the internal resistance.

Therefore, as a result of a more precise analysis of the secular change in the internal resistance, more specifically, the relationship between the internal resistance at the time of discharge and the number of operating days is as shown in FIG. 8 (a).
Fig. 8 shows the relationship between the internal resistance and the number of operating days during charging.
As shown in (b), it became clear that they exhibited different behaviors. The relationship between the internal resistance at the time of discharging and the number of times of charging / discharging is represented as in FIG. 8A, and the relationship between the internal resistance at the time of charging and the number of times of charging / discharging is shown in FIG.
(B) It was also clarified that it is expressed in the same manner. Therefore,
It is preferable to obtain a correction coefficient corresponding to each case of charging / discharging, and the correction coefficient K ₄ depending on the number of times of charging / discharging at the time of discharging and / or the correction coefficient K ₅ depending on the number of operating days are as shown in the form of the graph, R = A × D ^1/2 + R ₁ (R: internal resistance, A:
It is preferable to obtain it from a constant, D: number of times of charging and discharging (for K ₄ ) or number of operating days (for K ₅ ), and R ₁ : initial internal resistance.

In this way, the temperature during discharging of the NaS battery is measured, the depth of discharge is counted, the defective unit cell is detected, and the number of charge / discharge or operating days is counted to
The operating voltage V across both ends of the S battery during discharging is corrected by the temperature of the internal resistance, the depth of discharge, the change in the number of parallels due to the defective cell, and the number of charge / discharge and / or the number of operating days. At the time when the correction voltage V _L calculated by
_L is expressed by _{V L = V O × N-} I × R 1 × K 1 × K 2 × K 3 × (K 4 or K ₅ or K ₄ × K _5).

The same applies to charging. Of NaS battery
Measure the temperature during charging, count the charging depth, and
The number of charged and discharged cells and / or the number of operating days
Is counted and the operating voltage across the NaS battery is being charged during charging.
The pressure V is corrected by the temperature of the internal resistance and compensated by the depth of charge.
Correction by positive and change in parallel number and charge / discharge frequency and / or
Is the correction voltage V calculated by performing correction according to the number of operating days_HTo
It is preferable to stop the charging when it reaches. in this case
Correction voltage V_HIs V_H= V_hXN + IxR₁× K₁× C ×
K₃× (K_FourOr K_FiveOr K_Four× K_Five), Is represented by.
Correction factor K here_FourAnd / or K_FiveIs calculated as shown in FIG.
R = A × D shown in (b)^{1 / 2}+ B × D + R₁(R:
Internal resistance, A and B: constant, D: charge / discharge frequency (K_FourPlace
Or driving days (K_FiveIn the case of), R₁: Initial internal resistance
It is preferable to obtain it from (anti).

When charging, the correction based on the charging depth is omitted, and the charging is performed deeper within the range of the charging end polarization correction voltage α of 0.01 to 0.1 V than the charging voltage design open circuit voltage V _{h of the unit} cell. I mentioned earlier that you can. Therefore, even when the correction coefficient K ₄ or K ₅ is used, such an idea can be introduced.

That is, the temperature during charging of the NaS battery is measured, the defective single battery is detected, and the number of charging / discharging times and / or the number of operating days is counted to determine the operating voltage V across the NaS battery during charging. However, when the correction voltage V _H calculated by performing the correction by the temperature of the internal resistance, the polarization correction at the end of charge, the correction by the change in the number of parallels due to the failure of the unit cell, and the correction by the number of charge / discharge and / or the operation days is reached. A method of stopping charging is also preferable. The correction voltage V _{H in} this case is V _H = (V _h
+ Α) × N + I × R ₁ × K ₁ × K ₃ × (K ₄ or K ₅ or K ₄ × K ₅ ).

In the operation method of the NaS battery of the present invention described above, the internal resistance measured after assembly, that is, when the unused NaS battery module is discharged at the rated current for 30 to 60 minutes is taken as the initial internal resistance. It is preferable. This means that as the initial internal resistance of the NaS battery string or NaS battery block, the value obtained by measuring the internal resistance at the time when 30 to 60 minutes have elapsed after starting discharge after being assembled in series and parallel, respectively. It is synonymous with that it is preferable to use.

In the internal resistance initializing means as described above, the initial internal resistance is a specific internal resistance of the unit cell at the time of manufacturing the unit cell, and the initial internal resistance slightly varies with the discharge depth in the initial stage of discharging after the unit cell is manufactured. It was found from the fact that the internal resistance after 30 to 60 minutes from the discharge at the rated current is almost constant and has little fluctuation.

On the other hand, the internal resistance of the NaS battery string and / or the NaS battery block measured during the regular inspection of the NaS battery module may be used as the initial internal resistance. By resetting the secular change of the initial internal resistance after the periodic inspection and setting it as the initial internal resistance reference value, it becomes possible to more accurately perform proper operation control of the NaS battery module at the end of charging or at the end of charging.

In addition, when predicting the amount of change in internal resistance due to various factors and incorporating it in the voltage / current control during charging or discharging, that is, when performing the nth charging / discharging,
By predicting the change in internal resistance due to the number of times of charge and discharge and deterioration over time, and predicting the internal resistance during the nth charge and discharge, and performing charge and discharge control in the set state, safety is not compromised and deep It is possible to charge and discharge up to the depth of discharge and the shallow depth of charge.

[0061]

As described above, according to the operating method of the NaS battery of the present invention, it is possible to discharge or charge the current to the allowable limit without damaging the battery as a power source for power storage such as peak cut. As a result, a power source for storing electric power with high energy density is obtained, construction cost is reduced, and further reduction in electric power cost is realized.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of a NaS battery block, (a) is a circuit diagram showing a configuration of a NaS battery,
(B) is a circuit diagram of a power storage device using a NaS battery.

FIG. 2 is an explanatory diagram showing behaviors of an operating voltage and an open circuit voltage in one cycle of charging / discharging of a device for storing electric power of a NaS battery.

FIG. 3 is an explanatory diagram showing a correlation between internal resistance and temperature in a NaS battery.

FIG. 4 is an explanatory diagram showing a correlation between internal resistance and depth of discharge in a NaS battery.

FIG. 5 is an explanatory diagram showing a correlation between internal resistance and depth of charge in a NaS battery.

FIG. 6 is an explanatory diagram showing a correlation between internal resistance and the number of times of charging and discharging in a NaS battery.

FIG. 7 is an explanatory diagram showing a simplified state of the secular change in internal resistance of a NaS battery.

FIG. 8 (a) of the NaS battery is at the time of discharging,
(B) is an explanatory view showing the relationship between the internal resistance during charging and the number of operating days.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Single battery, 2 ... Insulation container, 3 ... NaS battery string, 4 ... NaS battery block, 5 ... NaS battery, 6 ... Power storage device, 7 ... Inverter, 8 ... Voltmeter, 9 ... Thermometer, 10 ... Ammeter, 15 ... Control device.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ identification code FI H02J 7/00 302 H02J 7/00 302D 7/02 7/02 H (72) Inventor Toshiaki Kuno Suda Town, Mizuho-ku, Nagoya City, Aichi Prefecture No. 2-56 Insulator of Japan Incorporated (72) Inventor Harumi Takagi 2-56 Suda-cho, Mizuho-ku, Nagoya-shi, Aichi Prefecture In-insulator of Japan Incorporated (72) Furuta One, 2 Suda-cho, Mizuho-ku, Nagoya-shi, Aichi No. 56 in Nippon Insulators Co., Ltd. (56) Reference JP-A-8-50930 (JP, A) JP-A-9-322417 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) ) H01M 10/39 H01M 10/44 H01M 10/48

Claims (14)

(57) [Claims] 1. A NAT comprising a plurality of unit cells connected in series.
A method for operating a lithium-sulfur battery discharge, comprising: Measure the temperature of the sodium-sulfur battery during discharge to determine the discharge depth.
Count the degree, Operating voltage across the sodium-sulfur battery during discharge
V is the correction of the internal resistance due to the temperature and the compensation due to the depth of discharge.
Correction voltage V with positive_L(V_L= V_OXN-IxR₁× K
₁× K₂However, V_O: Designed open circuit voltage at discharge end of unit cell,
N: Number of unit cells in series, I: Current, R₁: Initial internal resistance,
K₁: Correction coefficient due to temperature dependence of internal resistance, K ₂: Internal resistance
The discharge is stopped when the
How to operate a sodium-sulfur battery characterized by stopping
Law. 2. A method of operating a sodium-sulfur battery discharge, comprising a plurality of single battery cells connected in series and further connected in parallel, the method comprising: The temperature is measured, the depth of discharge is counted, the defective single cell is detected, and the operating voltage V across the sodium-sulfur battery during discharge is corrected by the internal resistance temperature and the depth of discharge. A correction voltage V _L (V _L = V _O × N−I × R ₁ × K ₁ × K ₂ ×) that takes into account the correction due to the change in the number of parallels due to the failure of the unit cell.
K ₃ , where V _{O is the} open circuit voltage at the end of discharge of the unit cell, N is the number of unit cells in series, I is the current, R _{1 is the} initial internal resistance, K _{1 is the} correction coefficient depending on the temperature of the internal resistance, K ₂ : Correction coefficient of internal resistance depending on the depth of discharge, K ₃ : ratio of the total number of parallel cell groups to the number of cell groups not including the failed cell), sodium-sulfur is characterized in that the discharge is stopped How to operate the battery. 3. A single cell formed by connecting a plurality of cells in series.
Sodium-sulfur battery consisting of multiple ponds connected in parallel
A method for operating a pond discharge, Measure the temperature of the sodium-sulfur battery during discharge to determine the discharge depth.
Counts, detects a failed cell, and then charges and discharges
Count the number of times and / or the number of operating days, Operating voltage across the sodium-sulfur battery during discharge
V is the correction of the internal resistance due to the temperature and the depth of discharge
And charge and discharge due to changes in the number of parallels due to battery and unit cell failure
Corrected voltage with correction based on the number of times and / or the number of operating days
Pressure V_L(V_L= V _OXN-IxR₁× K₁× K₂× K₃× (K_Four
Or K_FiveOr K_Four× K_Five), But V_O: Discharge of single battery
Designed open circuit voltage, N: Number of series cells, I: Current, R₁:
Initial internal resistance, K₁: Correction factor due to temperature dependence of internal resistance
Number, K₂: Correction coefficient of internal resistance according to depth of discharge, K₃:single
The total number of cells in parallel and the number of cells without faulty cells
Ratio of K_Four: Correction coefficient for internal resistance charging / discharging times,
K_Five: When the internal resistance correction coefficient by the number of operating days) is reached
Sodium-sulfur characterized by stopping discharge at a point
How to operate the battery. 4. The correction coefficient K ₄ according to the number of charging / discharging times of the internal resistance and / or the correction coefficient K ₅ according to the number of operating days of the internal resistance is R = A × D ^1/2 + R ₁ (where R: internal resistance ,
_4. The sodium according to claim 3, wherein A is a constant, D is the number of times of charge and discharge (in the case of K ₄ ) or the number of operating days (in the case of K ₅ ), and R _{1 is the} initial internal resistance. How to operate a sulfur battery. 5. An operating method for charging a sodium-sulfur battery, which comprises connecting a plurality of cells in series, wherein the temperature during charging of the sodium-sulfur battery is measured and the depth of charge is counted, The operating voltage V across the sodium-sulfur battery during charging is a correction voltage V _H (V _H = V _{h), which} takes into account the correction of the internal resistance with temperature and the correction of the charging depth.
× N + I × R ₁ × K ₁ × C, where V _{h is the} open circuit voltage at the end of charging of the single cell, N is the number of series cells, I is the current, R _{1 is the} initial internal resistance, and K _{1 is} the temperature of the internal resistance. The method for operating a sodium-sulfur battery is characterized in that charging is stopped when a correction coefficient by dependence, C: correction coefficient by the depth of charge of the internal resistance) is reached. 6. A method for operating a sodium-sulfur battery, which comprises a plurality of unit cells connected in series and further connected in parallel, the method comprising: The operating voltage V between both ends during the charging of the sodium-sulfur battery is measured by measuring the temperature and the charging depth, detecting the defective cell, and correcting the internal resistance by the temperature and the charging depth. Correction voltage V _H (V _H = V _h × N + I × R ₁ × K ₁ × C ×) that takes into account the correction due to the change in the number of parallels due to the failure of the unit cell
K ₃ , where V _{h is the} open circuit voltage at the end of charging of the single cell, N is the number of series cells, I is the current, R _{1 is the} initial internal resistance, K _{1 is} the temperature dependent correction coefficient of the internal resistance, and C is the internal. correction coefficient by the state of charge of the resistor, K _3: sodium, characterized in that to stop the charging when it reaches the ratio) between the unit cell number group not including a parallel total number a fault cell in the cells groups - sulfur battery Driving method. 7. A single cell formed by connecting a plurality of cells in series.
Sodium-sulfur battery consisting of multiple ponds connected in parallel
A driving method for charging a pond, Measure the temperature of the sodium-sulfur battery during charging to determine the charging depth.
Counts, detects a failed cell, and then charges and discharges
Count the number of times and / or the number of operating days, Operating voltage across the sodium-sulfur battery during charging
V is the correction of the internal resistance due to the temperature and the correction of the depth of charge
And charge and discharge due to changes in the number of parallels due to battery and unit cell failure
Corrected voltage with correction based on the number of times and / or the number of operating days
Pressure V_H(V_H= V _hXN + IxR₁× K₁× C × K₃× (K_Four
Or K_FiveOr K_Four× K_Five), But V_h: Battery charging
Designed open circuit voltage, N: Number of series cells, I: Current, R₁:
Initial internal resistance, K₁: Correction factor due to temperature dependence of internal resistance
Number, C: Correction coefficient of internal resistance depending on charging depth, K₃:single
The total number of cells in parallel and the number of cells without faulty cells
Ratio of K_Four: Correction coefficient for internal resistance charging / discharging times,
K_Five: When the internal resistance correction coefficient by the number of operating days) is reached
Sodium-sulfur characterized by stopping charging at points
How to operate the battery. 8. A method for operating a sodium-sulfur battery, which comprises connecting a plurality of cells in series, wherein the temperature during charging of the sodium-sulfur battery is measured to measure the temperature of the sodium-sulfur battery. The operating voltage V between both ends during charging is a correction voltage V _H (V _H = (V _h + α) × N + I) in which correction by the temperature of the internal resistance and polarization correction at the end of charging are taken into consideration.
× R ₁ × K ₁ , where V _{h is the} open circuit voltage at the end of charging of the single battery, α (polarization correction voltage at the end of charging): 0.01 V to 0.1
V, N: number of cells in series, I: current, R ₁ : initial internal resistance, K ₁ : correction coefficient due to temperature dependence of internal resistance).
How to operate a sulfur battery. 9. A method for operating a sodium-sulfur battery, which comprises a plurality of unit cells connected in series and further connected in parallel, comprising: The temperature is measured and the defective single cell is detected, and the operating voltage V across the sodium-sulfur battery during charging is corrected by the temperature of the internal resistance and the polarization voltage at the end of charge correction and the parallel operation due to the failure of the single cell. Corrected voltage V _H (V _H = (V _h + α) × N + I × R ₁ × K, which takes into account the correction due to the change in the number
₁ × K ₃ , where V _{h is the} open circuit voltage at the end of charging of a single cell, α
(Polarization correction voltage after charging): 0.01 V to 0.1 V, N:
Number of series of single cells, I: current, R ₁ : initial internal resistance, K ₁ : correction coefficient due to temperature dependence of internal resistance, K ₃ : total number of parallel single cells and number of single cells without faulty single cells The method for operating a sodium-sulfur battery is characterized in that charging is stopped when the ratio reaches. 10. A method of operating a sodium-sulfur battery, which comprises a plurality of unit cells connected in series and further connected in parallel, the method comprising: The temperature is measured, the defective single cell is detected, and the number of charging / discharging times and / or the number of operating days is further counted, so that the operating voltage V across the sodium-sulfur battery during charging is corrected by the temperature of the internal resistance. And the correction voltage V _H (V _H = (V _h + α) × N + I × R ₁ ) in which the polarization voltage correction at the end of charge and the correction due to the change in the number of parallels due to the failure of the unit cell and the correction according to the number of charge / discharge and / or the number of operating days are taken into consideration. × K ₁ × K ₃ ×
(K ₄ or K ₅ or K ₄ × K ₅ ), where V _{h is the} open circuit voltage at the end of charging of the single cell, α (polarization correction voltage at the end of charging):
0.01V to 0.1V, N: number of single cell series, I: current,
R ₁ : initial internal resistance, K ₁ : correction coefficient of internal resistance due to temperature dependence, K ₃ : ratio of parallel total number of single battery groups to number of single battery groups not including failed cells, K ₄ : charging of internal resistance The method for operating a sodium-sulfur battery is characterized in that the charging is stopped when a correction coefficient according to the number of discharges, K ₅ : a correction coefficient according to the number of operating days of the internal resistance) is reached. 11. A correction coefficient K ₄ according to the number of charging / discharging times of the internal resistance and / or a correction coefficient K ₅ according to the number of operating days of the internal resistance is R = A × D ^1/2 + B × D + R ₁ (where R:
A value obtained from internal resistance, A and B: constants, D: number of times of charging / discharging (for K ₄ ) or number of operating days (for K ₅ ,), R ₁ : initial internal resistance. 7
Or the operating method of the sodium-sulfur battery according to 10. 12. The initial internal resistance is defined as the internal resistance measured at the time of discharging an unused sodium-sulfur battery module at a rated current for 30 to 60 minutes. Item 7. A method for operating a sodium-sulfur battery according to the item. 13. The method for operating a sodium-sulfur battery according to claim 1, wherein an internal resistance measured during a periodic inspection of the sodium-sulfur battery module is used as an initial internal resistance. 14. The charging / discharging according to claim 1, wherein the amount of change in internal resistance is predicted and incorporated into voltage / current control during charging or discharging to perform charging / discharging. How to operate a sodium-sulfur battery.