JPH0821404B2 - Secondary battery - Google Patents

Description

TECHNICAL FIELD The present invention relates to a secondary battery in which a battery active material is liquid,
In particular, the present invention relates to a two-component secondary battery that can be charged and discharged for a short time and has excellent maintenance and drivability.

[Conventional technology]

The mainstream of secondary batteries are lead-acid batteries and nickel-cadmium batteries, but in recent years development of new-type secondary batteries such as redox flow type batteries, zinc-chlorine batteries, and zinc-bromine batteries has been underway. . Lead-acid batteries, which are the most widespread among secondary batteries, do not perform deep discharge easily, and are used for so-called short-time charge / discharge that performs continuous continuous charge / discharge at the rated time in a short time, or randomly at a few days per day. It is not suitable for applications in which so-called cycle life is required, in which charge and discharge of cycles are repeated.

On the other hand, redox flow type batteries do not require uniform charging operation or complete discharging operation even when a plurality of redox flow type batteries are stacked, and can be stopped and started immediately in any charging / discharging state and left for a long time. Alternatively, it is known as a battery that can be continuously operated and has the best maintainability. Recently, attention has been paid to the good maintainability of this redox flow battery, and a proposal to use it as an independent power supply system that requires a short time for charging and discharging and high voltage efficiency as a secondary battery for solar battery backup Has been done.

However, the conventional redox flow type secondary battery can cope with random charging / discharging, but it takes a long time to charge / discharge at the rated value and cannot connect high voltage efficiency.

[Problems to be Solved by the Invention]

The object of the present invention is to solve the above-mentioned problems of the prior art, to allow charging / discharging according to the rating within a few hours, to have a cyclo life capable of withstanding several cycles of charging / discharging a day, and to achieve high voltage efficiency. An object of the present invention is to provide a two-component secondary battery that can last.

[Means for solving the problem]

The inventors of the present invention continued to earnestly study redox flow type secondary batteries in order to obtain a maintenance-free secondary battery, and as a result, the total amount of electrolyte solution in the electrolyte circulation system in the redox flow type secondary battery. By increasing the ratio of the amount of electrolytic solution retained in the electrode to the electrode (hereinafter, also referred to as the electrolytic solution retaining ratio of the electrode).
The inventors have found that the voltage efficiency of a flow type battery is remarkably improved and have reached the present invention.

That is, the present invention is a two-part battery having a battery main body containing a transparent electrode that impregnates or circulates the electrolytic solution, a pipe and a liquid feeding means for circulating the electrolytic solution in the battery main body, and a container for storing the electrolytic solution. The secondary battery is characterized in that the amount of the electrolytic solution held by the transmission electrode is 10% or more of the total amount of the electrolytic solution involved in charging and discharging in the electrolytic solution circulation system.

FIG. 1 is a diagram showing a charging / discharging circuit of a redox flow type secondary battery for explaining the principle of the present invention. This circuit comprises a small-sized cell 1, a positive-electrode liquid storage tank 2 and a negative-electrode liquid storage tank 3 for storing electrolyte solutions circulated in the positive electrode and the negative electrode of the small-sized cell 1, respectively, and the positive and negative bipolar liquid storage tanks 2, 3 and the electrolytic solution circulating systems 4 and 5 for connecting the positive electrode and the negative electrode of the small unit cell 1, respectively, and the tube pump 6 commonly provided to the electrolytic solution circulating systems 4 and 5.

In such a redox flow type secondary battery charging / discharging circuit, for example, a cation exchange membrane is used as a diaphragm of a single cell, and a positive electrode and a negative electrode are each 100 mm in length and 10 m in width.
m, 5mm thick carbon felt with 3.5ml of each electrolyte retention (porosity: 0.7), 2% vanadium / trivalent ion active material concentration of 2mol /
Electrolysis of both positive and negative electrodes is performed by changing the total circulating electrolyte volume of the positive and negative electrodes by using the normal sulfuric acid aqueous solution as the negative electrode solution and the 2N sulfuric acid aqueous solution with vanadium tetravalent / 5 valent ion active material concentration of 2 mol /. Change the liquid retention ratio
The operation of charging for 10 minutes and then discharging for 10 minutes was repeated. Electrolyte holding ratio of electrodes and voltage efficiency (ratio to average voltage) ηv
Asked for a relationship. The results are shown in Table 1. At this time, the liquid feed rate of the positive and negative electrodes was 3 ml / min, the energization amount was 400 mV, and the electrolytic cell temperature was 25 ° C.

From Table 1, the electrolyte holding amount of the positive electrode and the negative electrode is kept constant at 3.5 ml respectively, and the total amount of electrolytic solution involved in charging / discharging is narrowed down so that the electrolyte holding ratio of the electrode relative to the total amount of electrolytic solution is relatively large. By doing so, it can be seen that the problem of mixing in the tank disappears, the charging depth of the entire electrolyte solution rises, and the voltage efficiency gradually improves. Further, it can be seen that when the electrolytic solution holding ratio of the electrode is set to 10% or more, the voltage efficiency is significantly increased as compared with the case of less than 10%.

FIG. 2 is a diagram showing the relationship between the electrolytic solution holding ratio of the electrodes and the voltage efficiency ηv. In the figure, the voltage efficiency ηv increases as the electrode electrolyte retention rate increases, and when the electrode electrolyte retention rate becomes 10% or more, the voltage efficiency ηv becomes 80%.
% Or more, and if the electrolytic solution holding ratio of the electrode is 20% or more, ηv becomes high efficiency of 85% or more.

In the present invention, the electrolytic solution holding amount of the electrode means the amount of the electrolytic solution in the electrolytic solution circulation system which is impregnated into the electrode.

In the present invention, the secondary battery configured so that the electrolyte holding ratio of the electrode is 10% or more, for example, using a large electrolyte holding capacity represented by a laminate of carbon fiber felt as an electrode material, Also, for example, by reducing the diameter of the manifold, slits, etc. of the electrolytic solution circulation system, and by using the smallest possible circulation pump, the total internal volume of the electrolytic solution circulation system should be 10% of the electrolytic solution retention amount of the electrode. One example is one in which the electrolytic solution holding ratio of the electrodes is set to 10% or more while suppressing the amount to less than or equal to twice.

In the present invention, the electrolytic solution holding ratio of the electrode is 10% or more, preferably 30% or more. By setting the electrolytic solution holding ratio of the electrode to 10% or more, voltage efficiency becomes high, and charging / discharging according to the rating becomes possible in a short time. If the electrolyte holding ratio of the electrode is less than 10%, the voltage efficiency ηv becomes 80% or less, and the object of the present invention cannot be achieved.

〔Example〕

 Next, the present invention will be described in more detail with reference to Examples.

FIG. 3 is a partial cross-sectional view of a redox flow type secondary battery showing an embodiment of the present invention. In this secondary battery, an electrolytic cell having a positive electrode and a negative electrode and an electrolytic solution circulation system are housed in the same frame. In the figure, this secondary battery includes an electrolytic cell having a positive electrode 11 and a negative electrode 12, which are integrally housed in the same frame, a positive electrode side manifold 14 and a negative electrode 14 for circulating an active material electrolytic solution to the positive electrode 11 and the negative electrode 12, respectively. Side manifold 15, positive electrode liquid reservoir 16 and negative electrode liquid reservoir 17 that store the active material electrolyte, and manual positive and negative electrode electrolyte circulation pumps that circulate the active material electrolyte
The electrolytic cell is mainly composed of 18 and 19, and the electrolytic cell is composed of a plurality of single cells composed of a positive electrode 11 and a negative electrode 12 which are adjacent to each other with a diaphragm 10 therebetween, and the single cells are laminated with a bipolar partition plate 13 interposed therebetween. The ratio of the amount of electrolyte solution retained in the electrode to the total amount of electrolyte solution involved in the electrode reaction is determined by using a stack of 100 mm × 100 mm × 6 mm carbon fiber felt, which has a large electrolytic solution holding capacity, as the electrode, and the manifold and slit. The total internal volume of the electrolytic solution circulation system including the electrolytic solution storage section and the like is adjusted to be 50%.

With this secondary battery, a 2N sulfuric acid aqueous solution having a vanadium divalent / trivalent ion active material concentration of 2 mol / was used as the positive electrode side electrolyte, and a vanadium tetravalent / 5 valent ion active material concentration of 2 mol / was used as the negative electrode liquid. When using a specified sulfuric acid aqueous solution and connecting it to a solar cell and using it as a backup secondary battery, once in a few days, that is, intermittently, the positive and negative electrode electrolyte circulation pumps 18 and 19 were activated to operate in the electrolytic cell. It is maintenance-free except for renewing the active material electrolyte, and there are no problems even after two months have passed. Voltage efficiency ηv
Always showed more than 83%.

According to the present embodiment, the electrolytic solution circulation pumps 18 and 19, the manifolds 14 and 15, and the liquid reservoirs 16 and 17 are made as small as possible, and the electrolysis held in the electrode with respect to the total amount of the electrolytic solution involved in the electrode reaction. Since the ratio of the liquid amount is set to 50%, the voltage efficiency ηv is high, the rated charge / discharge can be performed in a short time, and the cycle life for random charge / discharge is extended. Further, in the conventional redox flow type secondary battery, the cost of the electrolytic solution accounts for a significant proportion of the total cost, which is economically disadvantageous as compared with the lead storage battery, but according to this example, the storage is The amount of electrolyte to be used is much smaller than that of the conventional one, so that the economical efficiency is improved.

〔The invention's effect〕

ADVANTAGE OF THE INVENTION According to this invention, the voltage efficiency of a two-component secondary battery improves, it becomes possible to charge / discharge by a rating in a short time, and the cycle life for random charge / discharge becomes long.

[Brief description of drawings]

FIG. 1 is a diagram showing a charge / discharge circuit of a redox flow type secondary battery, and FIG. 2 is a diagram showing a relationship between an electrode electrolyte retention ratio and voltage efficiency ηv in the redox flow type secondary battery. FIG. 3 is a partial cross-sectional view of a redox flow type secondary battery showing an embodiment of the present invention. 11 …… positive electrode, 12 …… negative electrode, 14 …… positive electrode side manifold,
15 …… Negative side manifold, 16 …… Positive electrode reservoir, 17 ……
Anode liquid reservoir.

Claims (1)

[Claims] 1. A two-part liquid having a battery main body containing a transparent electrode for impregnating or circulating an electrolytic solution, a pipe and a liquid feeding means for circulating the electrolytic solution in the battery main body, and a container for storing the electrolytic solution. In the secondary battery of the formula, the amount of the electrolytic solution held by the transmission electrode is configured to be 10% or more of the total amount of the electrolytic solution involved in charging and discharging in the electrolytic solution circulation system. Liquid secondary battery.