JPH0654675B2 - Secondary battery device charging / discharging method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a charging / discharging method for a secondary battery device, and more specifically, it uses a power generator using a natural energy source and a secondary battery in combination to achieve stable operation. The present invention relates to a charging / discharging method of a secondary battery device capable of obtaining an output voltage.

(Prior Art) It is easy to obtain these natural energy sources by using solar power generation, wind power generation, etc. using natural energy sources without using fossil fuels such as petroleum as local energy sources. It is extremely useful in various places.
However, because the output of the natural energy source is unstable,
In order to supplement this, a power supply system combined with a secondary battery has been receiving attention. In this case, the charging / discharging time rate of the secondary battery is 20-
30 hours or more is desirable. That is, a battery having a continuous discharge time of 20 to 30 hours or more is required. The electrode active material flow type secondary battery is excellent in economic efficiency because the charge / discharge time rate can be adjusted while the amount of the battery active material is increased / decreased and the electrode part remains as it is, and the liquid is delivered to each electrode. Since the active material can be stored in a common tank,
It is suitable for use in this field without the problem that the charge / discharge depth varies for each battery unit.

An electrode active material flow type secondary battery (a redox flow type secondary battery as a typical example) is used for charging and discharging at a 6th
The change over time in the voltage as shown in the figure is shown. Therefore, when it is difficult for the power generation side and the load side to follow such voltage fluctuations at the time of input / output of the battery, it is necessary to mitigate the fluctuations on the battery side, and for this reason, a trim cell function is provided.

FIG. 4 and FIG. 5 are explanatory views showing a device system used in a charging / discharging method of a conventional secondary battery device in which a solar cell array and a secondary battery are combined. In FIG. 4, electricity generated by the photovoltaic power generation array 3 is sent to the electrode active material flow type battery 1 via the diode 4 for blocking the reverse current. Since the output voltage of the electrode active material flow type battery 1 varies depending on the charging / discharging depth of the battery active material, a flow cell having a voltage trimming function is used in the electrode portion of the battery, and the trimming terminal 2 is switched to output the output voltage. The fluctuation of is reduced. During photovoltaic power generation, a part of the electric power is consumed on the load side through the orthogonal converter 8, and the rest is charged into the battery 1 through the trimming terminal 2 of the battery 1. When sunlight cannot be generated due to the lack of sunlight such as at night, electric power is discharged from the battery 1 and a part of the electric power is sent to the load side through the orthogonal exchanger 8. At this time, the switching of the trimming terminal 2 is controlled so as to reduce the fluctuation of the output voltage.

Next, in the apparatus shown in FIG. 5, two electrode active material flow type batteries (hereinafter, also referred to as cell stacks), that is, a charging-only battery 1a and a discharging-only battery 1b are provided, and the active materials of both stacks are stored in one tank. It can be supplied from. In this device, since charging and discharging are performed in different cell stacks, charging can be performed at a voltage lower than the output voltage of the storage battery, the leakage current of the flow cell can be reduced accordingly, and high charging / discharging efficiency can be obtained.

(Problems to be Solved by the Invention) An object of the present invention is, in an electrode active material flow type secondary battery, a secondary battery that can be charged at a low input voltage and can obtain a stable output voltage. An object is to provide a charging / discharging method for a device. That is, conventionally, two cell stacks were used for low-voltage charging and high-voltage discharging, or one cell stack was used for charging and discharging at approximately the same level of voltage, but in the present invention, good overload characteristics are achieved. By using a cell stack, it is basically intended to perform low voltage charging and high voltage discharging with only one cell stack.

(Means for Solving the Problems) In the present invention, a large number of single cells in which positive and negative electrodes supported in a frame are laminated with a diaphragm are laminated in series with a bipolar partition plate, and a positive electrode and An electrode active material flow type secondary which supplies an electrolyte solution to the negative electrode and also supplies and stores electric power through any of the electrodes or the input / output terminals for current collection provided on the bipolar electrode partition plate for storage and extraction when necessary. In the battery charging / discharging method,
The stacked electrode active material flow type secondary battery is charged by supplying power to a part of the stacked parts through the input / output terminals, while discharging from the secondary battery is performed by the number of stacked parts of the stacked parts. Electric power is taken out from the laminated portion in which the number of laminated layers is increased through the input / output terminal, and the ratio of the number of laminated layers (the number of laminated layers when charging / the number of laminated layers when discharging) is 3/4 or less. And

In the present invention, the current collecting input / output terminal means a terminal for inputting or outputting electric power to the secondary battery. As such an input / output terminal, for example, a current collecting trimming terminal is used. Here, the current-trimming terminal is a metal plate or carbon for current collection for supplying (charging) or extracting (discharging) electric power from any single cell of the terminals forming the cell stack. A plate.

In the present invention, the auxiliary machines refer to subsystems such as a pump and a rebalance system necessary for operating the secondary battery.

Hereinafter, the present invention will be described in more detail with reference to the embodiments shown in the drawings.

(Example) FIGS. 1-3 is explanatory drawing of the secondary battery apparatus used for one Example of this invention. The secondary battery device of FIG. 1 is a combination of a cell stack 1, a solar cell array 3, and a wind power generator 6 having a wind turbine 5. The electric power generated by the solar cell array 3 and the wind power generator 6 is input to the low voltage side terminal (trimming terminal) 2 of the cell stack 1 through the reverse current prevention diode 4 and the rectifying diode 7, respectively, and is charged. The input voltage at this time is generally desired to be 50 V or less, though it depends on the structure and size of the flow cell. On the other hand, the output from the flow cell 1 is taken out from the trimming terminal 2 at a position where it becomes a required voltage of loads and auxiliary devices such as the subsystem 9 and the pump 10 and sent to the orthogonal transformer 8, the pump 10 and the subsystem 9, respectively. To be For example, when it is desired to take out an AC output of 100 V, a DC voltage may be taken out from the trimming terminal on the high voltage side as shown in the drawing, and AC conversion may be performed by the orthogonal switch 8. In this case, since the output voltage of the battery changes as the charge / discharge depth of the battery changes, it is desirable to output from a plurality of trimming terminals through the switch element in order to cope with this.

FIG. 2 is a system diagram including the active material liquid distribution line of the cell stack 1 of FIG. 1, that is, the active material liquid storage tank 11 connected to the subsystem 9 and the pump 10 and the liquid distribution line. . The subsystem 9 is mainly a positive and negative electrode active material monitoring device, which measures the active material concentrations of the positive electrode liquid and the negative electrode liquid to grasp the charging status of the positive and negative electrode active material liquids. A rebalance device 12 is provided for adjusting each other. Examples of the positive electrode active material include hydrochloric acid acidic bromine / bromine ion aqueous solution, and examples of the negative electrode active material include hydrochloric acid acidic chromium trivalent / divalent aqueous solution.

As the monitor device 9, an analyzer using a method such as coulometry (coulometry), voltammetry, potentiometry, or absorptiometry is preferably used.
Hydrogen and bromine gas respectively generated in the negative electrode and the positive electrode of the cell stack 1 are introduced into the rebalance device 12 from the positive electrode active material tank 11a and the negative electrode active material tank 11b, and react there to generate hydrogen bromide. This hydrogen bromide is appropriately returned to the positive electrode liquid tank 11a, the amount of the positive and negative electrode active materials is automatically balanced, and the charging depth can be controlled within an appropriate range in this way.

In general, redox flow type secondary batteries that use chrome divalent and trivalent ions as the negative electrode active material produce hydrogen gas as a by-product as described above, and therefore, when charged, the current efficiency of chrome divalent generation on the negative electrode side is positive. Side, so that the positive electrode active material side becomes overcharged than the negative electrode active material side. Therefore, in this embodiment, a system for reacting bromine and hydrogen to rebalance is provided.

FIG. 3 shows the cell stack 1 shown in FIGS. 1 and 2.
The cell stack 1a for charging and the cell stack 1 for discharging
It is explanatory drawing of the secondary battery device for a test separated into b. The negative electrode and positive electrode active material storage tanks 11a and 11b are provided with respective lines for supplying and circulating the negative electrode and positive electrode active material solutions to the cell stacks 1a and 1b, respectively. In the figure, 13 is a DC power supply, 14 is a load, and 15
Indicates a flow meter, and 16 indicates a stop valve, the solid line indicates the active material liquid line, and the alternate long and short dash line indicates the electric system line.

The number of series cells of the cell stack 1b is 120 cells, and the number of high voltage side trimming terminals is 3 from the stack highest voltage side terminal.
Each cell has 10 trimming terminals, and the number of low-voltage side trimming terminals is 3 from the lowest voltage side (0V side in the case of ground) to the 10th, 13th, and 16th bipolar plates, and the stack 1a dedicated to charging. Was arranged in series with 24 cells, and the charging terminal was also installed on the 20th bipolar plate from the lowest voltage side.

The charge-only stack 1a includes the above-mentioned 120 for discharging.
It is arranged so that the active material solution can be sent in parallel with the cell stack 1b. In addition, a stop valve 16 is provided in the liquid supply line of the charging-only cell stack 1a so that the liquid supply can be stopped if necessary. In such a secondary battery device, 3N hydrochloric acid acidic 1 mol / iron chloride aqueous solution is used as the positive electrode side active material liquid, and 3N hydrochloric acid acidic 1 mol / chromium chloride aqueous solution is used as the negative electrode side active material liquid, and the input voltage is output. The charging / discharging coulombic efficiency was high and stable output voltage was obtained when the trimming terminal was selected so as to be 3/4 or less of the voltage and charging / discharging was performed.

Next, specific examples of the present invention will be described.

Example 1 Using the apparatus shown in FIG. 3, the stop valves 16a and 16b were closed to render the cell stack 1a inoperative, and 3N hydrochloric acid acidic 1 mol / iron chloride aqueous solution and negative electrode side active material solution were used as the positive electrode side active material solution. 3 mol hydrochloric acid acidic / chromium chloride aqueous solution are used respectively, the feed rate is 10 / min, the input voltage from the DC power supply 13 to the cell stack 1b is 24V, and the output voltage of the load 14 from the cell stack 1b is 100V. After 10 hours of charge and discharge, the charge and discharge Coulomb efficiency was as high as 79%, and a stable output voltage was obtained.

Comparative Example 1 Cell stack 1 with stop valves 16a and 16b opened
Using the device shown in FIG. 3 in a state in which a can be operated, the liquid transfer rate is set to 12 / min, and the DC power source 13 is connected to the cell stack 1a
Example 1 except that the input voltage to the load 14 is 24V and the output voltage from the cell stack 1b to the load 14 is 100V.
When charging / discharging was performed in the same manner as above, the charging / discharging Coulomb efficiency was 77%.

Comparative Example 2 When charging and discharging were performed in the same manner as in Example 1 except that the input voltage was 100 V, the charging / discharging Coulomb efficiency was 60%.

The conditions and results of Example 1 and Comparative Examples 1 and 2 are shown in Table 1.

From the results in Table 1, the liquid transfer of the cell stack 1a was stopped,
It can be seen that the charging / discharging Coulombic efficiency is higher in this example in which a smaller input voltage is input. In Comparative Example 1, the pump power consumption is increased due to the liquid feeding of 1a.
Therefore, the net output is lower than that of the first embodiment.

In this embodiment, when the load 14 does not work and only charging is performed, low voltage and large current charging is performed. Therefore, due to the voltage drop due to the cell resistance, the voltage efficiency is high voltage,
Although it tends to be worse than in the case of small current charging, the electrode active material flow type secondary battery generally has a small cell resistance and extremely good overload characteristics, so that the voltage efficiency reduction due to adopting the present invention is a problem. It doesn't. Further, under the situation where the load 14 is working and only discharging is performed, the loss of voltage efficiency is further reduced.

The secondary battery device used for implementing the present invention does not need to have all trimming terminals and input / output terminals in one cell stack. For example, a low voltage side cell stack, an intermediate cell stack, a high voltage side cell It is divided into stacks and so on, and these stacks are electrically coupled in series,
A trimming terminal or an input / output terminal may be provided for each divided portion.

Next, another specific embodiment will be described.

Example 2 Using the apparatus shown in FIG. 3, the stop valves 16a and 16b were closed to bring the cell stack 1a into a non-operating state (only the cell stack 1b was operating), and 1 mol of 3N hydrochloric acid acid as a positive electrode side active material liquid. / Iron chloride aqueous solution, 1 mol of 3N hydrochloric acid acidic / chromium chloride aqueous solution as the negative electrode side active material liquid, respectively, the liquid feed rate was 10 / min, and the input voltage from the DC power supply 13 to the cell stack 1b was 75 V (input Number of cells from terminal lowest voltage side 66), cell stack 1b
When the charging / discharging was performed for 10 hours with the output voltage from the battery to the load 14 being 100 V (the number of cells from the highest voltage side of the output terminal 9), the charging / discharging Coulomb efficiency was 69%, and a stable output voltage was obtained.

Example 3 The input voltage was 65 V (the number of cells from the input terminal lowest voltage side was 5).
When charging / discharging was performed under the same conditions as in Example 2 except that the above condition was 8), the charge / discharge coulomb rate was 71% and a stable output voltage was obtained.

Example 4 The input voltage was 45 V (the number of cells from the lowest voltage side of the input terminal was 4
When charging / discharging was performed under the same conditions as in Example 2 except for 0), the charge / discharge coulomb rate was 73% and a stable output voltage was obtained.

Example 5 The input voltage is 25 V (the number of cells from the input terminal lowest voltage side is 2).
When charging / discharging was performed under the same conditions as in Example 2 except for 1), the charge / discharge coulomb ratio was 79% and a stable output voltage was obtained.

Comparative Example 3 The input voltage was 85 V (the number of cells from the lowest voltage side of the input terminal was 7
When charging / discharging was performed under the same conditions as in Example 2 except for 0), the charge / discharge coulomb rate was 63% and the output voltage fluctuated.

The conditions and results of Examples 2 to 5 and Comparative Example 3 are shown in Table 2.

It can be seen from Table 2 that the charging / discharging efficiency is significantly reduced when the input voltage exceeds 3/4 of the output voltage.

(Effect of the Invention) According to the present invention, the following excellent effects are obtained.

(1) In one liquid flow type battery stack, the leakage current within the stack or between the stacks, that is, the current flowing through the manifold in the stack of the active material liquid and the liquid transfer line between the stacks, which is not involved in the main reaction of the battery, is reduced, Highly efficient charging can be performed.

(2) Electric power for operating auxiliary components such as electric subsystems and pumps can be obtained from one liquid flow type battery stack.

(3) Since the entire device can be put together in one liquid flow type battery stack, the device can be made compact, and the running cost can be reduced by reducing the equipment cost, the pump power for feeding the active material, etc. Can be made.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an outline of a secondary battery device used in the present invention, FIG. 2 is a diagram illustrating an active material solution line of FIG. 1, and FIG. 3 is FIG. 1 and FIG. FIG. 4, FIG. 5 and FIG. 5 in the case where the cell stack of the secondary battery device shown in FIG.
FIG. 6 is an explanatory diagram showing a conventional use example of a secondary battery device combined with conventional natural energy, and FIG. 6 is a diagram showing changes with time in voltage of a redox flow secondary battery during charging and discharging. is there. 1 ... Cell stack, 2 ... Trimming terminal, 3 ...
Photovoltaic cell array, 4 ... Reverse current prevention diode, 5 ...
… Windmill, 6 …… Generator, 7 …… Rectifier diode, 8 ……
Orthogonal exchanger, 9 ... Subsystem, 10 ... Pump, 1
1 ... Active material solution tank, 12 ... Rebalance device.

Claims (2)

[Claims] 1. A plurality of single cells, in which positive and negative electrodes supported in a frame are laminated with a diaphragm interposed therebetween, are laminated in series with a bipolar partition plate to supply an electrolytic solution to a positive electrode and a negative electrode.
In the charging / discharging method of an electrode active material flow type secondary battery, which supplies and stores electric power through an input / output terminal for collecting provided on any of the electrodes or the bipolar electrode partition plate, and extracts the electric power when necessary. The charged electrode active material flow type secondary battery is charged by supplying electric power to a part of the laminated parts through the input / output terminals, while the secondary battery is discharged from the laminated part by the number of laminated parts. It is characterized in that electric power is taken out from the increased number of laminated portions through the input / output terminals, and the ratio of the number of laminated layers (the number of laminated layers during charging / the number of laminated layers during discharging) is 3/4 or less. Method of charging and discharging secondary battery device. 2. The device according to claim 1, wherein a monitor device for detecting the positive electrode and negative electrode active material concentrations of the electrode active material flow type secondary battery, an auxiliary device such as an electrode liquid circulation pump are required. A charging / discharging method for a secondary battery device, which comprises selecting an input / output terminal of the electrode active material flow type secondary battery having a voltage and outputting the power of the auxiliary machinery.