JP6692218B2 - Power storage device - Google Patents

Description

  The present invention relates to power storage devices.

  A power storage device having a unit cell including a positive electrode plate containing a positive electrode active material such as nickel hydroxide, a negative electrode plate containing a hydrogen storage alloy, and a separator sandwiched between the positive electrode plate and the negative electrode plate (“ Nickel-hydrogen secondary battery "is also known). Among them, in nickel-metal hydride secondary batteries for consumer use, oxygen gas generated in the positive electrode plate is consumed in the negative electrode plate to prevent generation of hydrogen gas in the negative electrode plate, thereby suppressing increase in internal pressure and providing a sealed structure. It is possible. Specifically, in a sealed nickel-hydrogen secondary battery for consumer use, when the battery is overcharged from a fully charged state, water is electrolyzed in the positive electrode plate to generate oxygen gas. Oxygen gas generated in the positive electrode plate during overcharging moves to the negative electrode plate and reacts with hydrogen stored in the hydrogen storage alloy of the negative electrode plate to generate water. In this way, electrolysis of water (that is, generation of hydrogen gas) in the negative electrode plate is suppressed. On the other hand, the electric energy supplied to the battery during overcharge due to the electrolysis and formation reaction of water is lost as heat energy.

Therefore, Patent Document 1 discloses a technique in which a hydrogen storage chamber for storing hydrogen gas generated in the negative electrode plate and an oxygen storage chamber for storing oxygen gas generated in the positive electrode plate are provided in the configuration of the nickel-hydrogen secondary battery. Proposed.
According to this technique, a water generation reaction does not occur during overcharge, and hydrogen gas generated in the negative electrode plate and oxygen gas generated in the positive electrode plate can be stored in the hydrogen storage chamber and the oxygen storage chamber, respectively. Further, according to this technique, the stored hydrogen gas and oxygen gas can be converted into electric energy and reused at the time of discharge, so that the energy use efficiency is high.

JP, 2010-15783, A

  However, a large amount of oxygen gas generated in the positive electrode plate during overcharge moves to the negative electrode plate. In Patent Document 1, the capacity of the negative electrode plate is not provided in excess of the capacity of the positive electrode plate (that is, no charge reserve is provided) so that hydrogen is not generated from the negative electrode plate during overcharging, and thus oxygen gas is used. May react with the hydrogen storage alloy. As a result, the negative electrode plate may be damaged or deteriorated by the oxidation of the hydrogen storage alloy.

  The present invention has been made to solve the above problems, and an electric power storage device capable of efficiently storing electric energy supplied during overcharge while suppressing damage or deterioration of a negative electrode plate. The purpose is to provide.

  As a result of intensive studies to solve the above problems, the present inventors have provided a positive electrode flow channel plate that forms a positive electrode liquid flow channel between the positive electrode plate and the positive electrode flow channel plate with a positive electrode active material. It has been found that by circulating the contained positive electrode liquid, it is possible to prevent the positive electrode plate from being overcharged to generate oxygen gas, and have completed the present invention.

That is, the present invention, a positive electrode plate containing a positive electrode active material,
A negative electrode plate containing a hydrogen storage alloy,
Sandwiched between the positive electrode plate and the negative electrode plate, a separator containing an alkaline electrolyte,
A positive electrode flow channel plate for forming a positive electrode liquid flow channel in which a positive electrode liquid containing a positive electrode active material flows, and the positive electrode plate,
A unit cell including a negative electrode flow channel plate for forming a negative electrode gas flow channel through which the negative electrode gas flows, and the negative electrode plate,
The positive electrode liquid channel is connected to a first positive electrode liquid tank and a second positive electrode liquid tank for sending and receiving the positive electrode liquid,
The negative electrode gas flow path is connected to a negative electrode gas storage tank for transmitting and receiving the negative electrode gas, which is an electric power storage device.

  According to the present invention, it is possible to provide a power storage device capable of efficiently storing electric energy supplied during overcharge while suppressing damage or deterioration of the negative electrode plate.

FIG. 3 is a schematic conceptual diagram of the power storage device of the first embodiment. It is a top view of the groove part side of the positive electrode flow path plate. It is an expanded sectional view of the groove part of a positive electrode flow path plate. FIG. 6 is a top view of the groove portion side of the positive electrode flow channel plate for explaining the state in which the magnet or the electromagnet is arranged in the positive electrode flow channel plate so as to be spiral along the flow direction of the positive electrode liquid. FIG. 7 is a top view of the groove portion side of the positive electrode flow channel plate for explaining a state in which a groove portion or a protrusion portion is spirally formed in the positive electrode liquid flow channel along the flow direction of the positive electrode liquid. It is a schematic conceptual diagram of the electric power storage device of Embodiment 3.

  Hereinafter, preferred embodiments of the power storage device of the present invention will be described with reference to the drawings.

Embodiment 1.
FIG. 1 is a schematic conceptual diagram of the power storage device of the present embodiment.
In FIG. 1, a power storage device 1 includes a positive electrode plate 2, a negative electrode plate 3, a separator 4 sandwiched between the positive electrode plate 2 and the negative electrode plate 3, and a positive electrode liquid flow path 5 between the positive electrode plate 2. The unit cell includes a positive electrode flow channel plate 6 that forms the negative electrode flow channel plate 6 that forms the negative electrode gas flow channel 7 between the positive electrode flow channel plate 6 and the negative electrode plate 3. Although not shown, the positive electrode liquid flow path 5 is connected to the first positive electrode liquid tank 9 and the second positive electrode liquid tank 10 via the positive electrode liquid pipe 12, and the negative electrode gas flow path 7 is the negative electrode gas storage. It is connected to the tank 11 via a negative electrode gas pipe 15. A first liquid feed pump 13 is provided in the positive electrode liquid pipe 12 between the positive electrode liquid channel 5 and the first positive electrode liquid tank 9, and the positive electrode between the positive electrode liquid channel 5 and the second positive electrode liquid tank 10 is provided. A second liquid feed pump 14 is provided in the liquid pipe 12.

The positive electrode plate 2 contains a positive electrode active material. The positive electrode active material is not particularly limited, and those known in the art can be used. Examples of the positive electrode active material include Ni (OH) ₂ (nickel hydroxide), NiOOH (nickel oxyhydroxide), LiCoO ₂ (lithium cobalt oxide), and the like. These may be used alone or in combination of two or more. The positive electrode plate 2 preferably contains at least one of nickel hydroxide and nickel oxyhydroxide among various known positive electrode active materials. Here, nickel hydroxide is a positive electrode active material when the power storage device 1 is in a discharged state, and nickel oxyhydroxide is a positive electrode active material when the power storage device 1 is in a charged state.

Further, the positive electrode plate 2 may be a sintered type or a non-sintered type.
The sintered positive electrode plate 2 can be manufactured, for example, as follows. First, a paste containing nickel particles is applied on both main surfaces of a nickel-plated punching metal and sintered at about 1000 ° C. to obtain a sintered plate. Next, after impregnating the sintered plate with the nickel salt solution, the sintered plate is immersed in an alkaline aqueous solution. By repeating the impregnation into the nickel salt solution and the immersion into the alkaline aqueous solution, nickel hydroxide can be supported on the sintered plate.
The non-sintered positive electrode plate 2 can be manufactured by impregnating a nickel porous substrate with a paste containing nickel hydroxide particles, followed by drying and rolling. As the porous substrate, for example, foamed nickel, matte nickel fiber or the like can be used.

The negative electrode plate 3 contains a hydrogen storage alloy. The hydrogen storage alloy is not particularly limited as long as it can store hydrogen, and those known in the art can be used. Examples of hydrogen storage alloys include Mm-Ni-Co-Mn-Al alloys ("Mm" is a mixture of rare earth elements called misch metal), Mm-Mg-Ni-Al alloys ("cobalt". Also referred to as “free alloy”), MmNi ₅ , LaNi _{5, and the} like. These may be used alone or in combination of two or more.
The negative electrode plate 3 can be produced, for example, by molding a hydrogen storage alloy.

The separator 4 is electrically insulating and prevents electrical contact between the positive electrode plate 2 and the negative electrode plate 3. The separator 4 contains (holds) an alkaline electrolyte and is capable of penetrating protons.
As the material of the separator 4, those used in the separator for electrochemical devices can be used. For example, a nonwoven fabric made of polyolefin, a microporous film, or the like can be used as the separator 4. Examples of polyolefins include polyethylene, polypropylene and the like.
The separator 4 may have an ion exchange capacity, and the surface thereof may be subjected to a hydrophilic treatment. The hydrophilic treatment of the separator 4 is not particularly limited, and examples thereof include sulfonation of the surface of the separator 4 and plasma treatment of the surface of the separator 4.

The alkaline electrolyte is not particularly limited, and those known in the art can be used. The alkaline electrolyte preferably has a high ionic conductivity. An example of the alkaline electrolyte is an aqueous solution containing high concentration potassium hydroxide (KOH). The KOH concentration in this aqueous solution is generally about 10 to 40% by mass.
Moreover, the alkaline electrolyte may contain a plurality of hydroxides. For example, the alkaline electrolyte may contain two hydroxides, KOH and sodium hydroxide (NaOH). Further, the alkaline electrolyte may contain three kinds of hydroxides of KOH, NaOH and lithium hydroxide (LiOH).

The positive electrode flow path plate 6 is not particularly limited, but a mold resin plate having conductivity, a carbon plate, a metal plate having alkali resistance (for example, a stainless plate), or the like can be used.
The positive electrode flow channel plate 6 forms a positive electrode liquid flow channel 5 with the positive electrode plate 2, and thus has a groove that can serve as the positive electrode liquid flow channel 5. The groove of the positive electrode flow channel plate 6 can be formed by a known method such as press molding or cutting.
The shape of the groove portion of the positive electrode flow path plate 6 (that is, the shape of the positive electrode liquid flow path 5) is not particularly limited, and various shapes as shown in FIG. 2 can be used. Here, FIG. 2 is a top view of the groove portion side of the positive electrode flow channel plate 6. Since the positive electrode liquid flowing in the positive electrode liquid flow path 5 contains the positive electrode active material and the viscosity of the positive electrode liquid tends to increase, the groove shape of the positive electrode flow path plate 6 is a linear shape with a small pressure loss or a shape similar thereto. Preferably. Note that the shapes of the groove portions shown in FIGS. 2 and 3 are merely examples, and the number and width of the grooves can be appropriately changed. Although not shown in FIG. 2, the groove (positive electrode liquid flow path 5) of the positive electrode flow path plate 6 can be connected to the positive electrode liquid pipe 12 connected to the first positive electrode liquid tank 9 and the second positive electrode liquid tank 10. It looks like this.

The depth of the groove portion (positive electrode liquid flow path 5) of the positive electrode flow channel plate 6 is not particularly limited, but in consideration of the strength of the positive electrode flow channel plate 6 and the like, it is preferable that the depth of the positive electrode flow channel plate 6 is greater than It is 5% to 50%, more preferably 10% to 40%. The thickness of the positive electrode flow channel plate 6 is not particularly limited, but is generally 0.1 mm to 20 mm.
The cross-sectional shape of the groove portion (positive electrode liquid flow path 5) of the positive electrode flow channel plate 6 is not particularly limited, and may be various shapes such as a rectangular shape, a V shape, a trapezoidal shape, and a U shape as shown in FIG. You can Among them, the cross-sectional shape is preferably rectangular, U-shaped, or trapezoidal. The sectional width of the groove is not particularly limited, but is generally 0.1 mm to 10 mm.

  The positive electrode liquid flowing through the positive electrode liquid flow path 5 contains a positive electrode active material. The positive electrode active material contained in the positive electrode liquid is not particularly limited, and those known in the art can be used. The type of the positive electrode active material contained in the positive electrode liquid may be the same as or different from the positive electrode active material contained in the positive electrode plate 2, but is the same as the positive electrode active material contained in the positive electrode plate 2. Is preferred.

The positive electrode liquid is generally a suspension in which the positive electrode active material is dispersed, but it may be in the form of gel. In addition, the positive electrode liquid is generally alkaline.
The positive electrode active material contained in the positive electrode liquid may be particles obtained by crushing sintered nickel hydroxide particles, particles obtained by crushing the porous base material of the non-sintered positive electrode plate 2, or the like. Further, the positive electrode plate 2 may be recovered after repeating charging and discharging, and the positive electrode active material may be taken out and crushed to be reused.

The shape of the positive electrode active material contained in the positive electrode liquid is preferably spherical in consideration of the contact efficiency with the positive electrode plate 2 and the fluidity in the positive electrode liquid. Therefore, the positive electrode active material contained in the positive electrode liquid is preferably spheroidized. The spheroidizing treatment is not particularly limited, but can be performed using a ball mill or the like.
The average particle size of the positive electrode active material contained in the positive electrode liquid is not particularly limited, but is preferably 0.1 μm or more and 1 mm or less. By setting the average particle size of the positive electrode active material to be 0.1 μm or more, the contact efficiency between the positive electrode plate 2 and the positive electrode active material is improved, and the transfer of electrons is facilitated. Further, by setting the average particle size of the positive electrode active material to 1 mm or less, it is possible to suppress problems such as the positive electrode active material being aggregated in the positive electrode liquid flow path 5 to cause clogging. However, this is not the case when the cross-sectional area of the positive electrode liquid flow path 5 is increased.
Here, in the present specification, the “average particle size” means the particle size at an integrated value of 50% in the particle size distribution obtained by the laser diffraction / scattering method.

The positive electrode liquid may further contain a dispersant in order to stabilize the dispersed state of the positive electrode active material. The dispersant is not particularly limited, but is preferably alkali resistant. Examples of alkali-resistant dispersants include carboxymethyl cellulose (CMC), poly-N-vinyl acetamide (PNVA), and the like.
The positive electrode liquid may contain a conductive agent in order to impart conductivity. Examples of the conductive agent include carbon powder and carbon fiber. The conductive agent preferably has an average particle size of 0.1 μm or more and 1 mm or less so as not to impair the fluidity of the positive electrode liquid.

  The negative electrode flow channel plate 8 is not particularly limited, and the same one as the positive electrode flow channel plate 6 can be used. The groove shape of the negative electrode flow path plate 8 (that is, the shape of the negative electrode gas flow path 7) may be the same as or different from the groove shape of the positive electrode flow path plate 6. However, the groove portion (negative electrode gas flow path 7) of the negative electrode flow path plate 8 allows the negative electrode gas to flow, so that the degree of freedom in shape selection is higher than that of the groove portion (positive electrode liquid flow path 5) of the positive electrode flow path plate 6 through which the positive electrode liquid flows. Is high.

The first positive electrode liquid tank 9 and the second positive electrode liquid tank 10 are not particularly limited as long as they are made of a material having alkali resistance and not corroded by the positive electrode liquid. For example, the first positive electrode liquid tank 9 and the second positive electrode liquid tank 10 are preferably made of a material such as fluororesin, fluororubber, and stainless steel.
The first positive electrode liquid tank 9 and the second positive electrode liquid tank 10 may include a stirring device from the viewpoint of suppressing precipitation of the positive electrode active material in the positive electrode liquid.
The first positive electrode liquid tank 9 and the second positive electrode liquid tank 10 may both store the positive electrode liquid at the start of operation of the power storage device 1, or may store the positive electrode liquid in either one. Good. However, it is preferable that the positive electrode liquid is stored in both the first positive electrode liquid tank 9 and the second positive electrode liquid tank 10 so that the operation can be started from either charging or discharging.

  The negative electrode gas storage tank 11 is not particularly limited as long as it is made of a material that does not corrode with negative gas such as hydrogen gas. That is, the negative electrode gas storage tank 11 can be formed from various materials such as metal, resin, rubber, and a composite material of metal and resin as long as it has a negative electrode gas barrier property (for example, hydrogen gas barrier property). When resin or rubber is used, the hydrogen gas barrier property can be enhanced by lining a metal thin film or the like.

  The positive electrode liquid pipe 12 is not particularly limited, but is not particularly limited as long as it is made of a material that has alkali resistance and does not corrode with the positive electrode liquid. For example, the positive electrode liquid pipe 12 may be made of the same material as the first positive electrode liquid tank 9 and the second positive electrode liquid tank 10.

  The first liquid feed pump 13 and the second liquid feed pump 14 are not particularly limited as long as they have alkali resistance and can feed liquid in both directions. For example, when a flexible material such as fluororubber is used for the positive electrode liquid pipe 12, a peristaltic pump is preferable. A peristaltic pump is a pump that pumps a liquid in a pipe by compressing a flexible pipe whose inside is filled with a liquid from the outside with a roller that rotates. Although FIG. 1 shows an example in which two liquid feed pumps (the first liquid feed pump 13 and the second liquid feed pump 14) are used, one liquid feed pump is used if the liquid feed pump has a high liquid feed capacity. A liquid pump may be used.

  The negative electrode gas pipe 15 is not particularly limited as long as it is made of a material that does not corrode with the negative electrode gas such as hydrogen gas. That is, the negative electrode gas pipe 15 can be formed of various materials having a negative electrode gas barrier property (for example, a hydrogen gas barrier property) similarly to the negative electrode gas storage tank 11. For example, carbon fiber reinforced plastic (CFRP) having a lining such as a metal thin film can be used.

In the power storage device 1 having the above characteristics, the reactions represented by the formulas (1) and (2) occur in the negative electrode plate 3 during charging.
M + H ₂ O + e ⁻ → MH + OH ⁻ (1)
2H ₂ O + 2e ⁻ → H ₂ + 2OH ⁻ (2)
In the above formula, M represents a hydrogen storage alloy, and MH represents a hydrogen storage alloy that stores protons (H ⁺ ).
During charging, on the negative electrode plate 3, MH and hydroxide ions (OH ⁻ ) are generated by the reaction of the hydrogen storage alloy (M) with the protons (H ⁺ ) and the electrons (e ⁻ ) as shown in the formula (1). To generate. The reaction of formula (1) proceeds preferentially until there is no hydrogen storage alloy that can react with protons (H ⁺ ) and electrons (e ⁻ ), and then the reaction of formula (2) preferentially proceeds. Hydrogen gas (H ₂ ) generated by the reaction of the formula (2) passes through the negative electrode gas flow path 7 and is sent to the negative electrode gas storage tank 11 through the negative electrode gas pipe 15.

In addition, in the positive electrode plate 2, when at least one of nickel hydroxide (Ni (OH) ₂ ) and nickel oxyhydroxide (NiOOH) is used as the positive electrode active material, it is represented by the formulas (3) and (4) at the time of charging. The reaction that takes place occurs.
Ni (OH) ₂ + OH ⁻ → NiOOH + H ₂ O + e ⁻ (3)
4OH ⁻ → O ₂ + 2H ₂ O + 4e ⁻ (4)
During charging, in the positive electrode plate 2, nickel hydroxide reacts with hydroxide ions to generate nickel oxyhydroxide and water, and at the same time, emits electrons, as shown in formula (3). If the state of charge continues and the reaction of the formula (3) proceeds to decrease the nickel hydroxide, oxygen gas (O ₂ ) will be generated as shown in the formula (4). In the storage device 1, since the positive electrode liquid is circulated in the positive electrode fluid path 5 in contact with the positive electrode plate 2, the positive electrode active material (nickel hydroxide) is constantly supplied, so that the reaction of the formula (4) is less likely to occur. The generation of oxygen gas can be suppressed.

  When the positive electrode liquid is circulated in the positive electrode fluid path 5 during charging, the first liquid feeding pump 13 and the second liquid feeding pump 14 are interlocked with each other, and the positive electrode active material (hydroxylated water) stored in the second positive electrode liquid tank 10 in a discharged state (hydroxylation A positive electrode liquid containing nickel) is fed into the positive electrode fluid path 5. In the positive electrode fluid path 5, the positive electrode active material (nickel hydroxide) in a discharged state contained in the positive electrode liquid comes into contact with the positive electrode plate 2 to cause the reaction of the formula (3). As a result, the reaction of the formula (4) due to the decrease of the positive electrode active material (nickel hydroxide) in the discharged state on the positive electrode plate 2 becomes difficult to occur, so that the charging reaction can be continued while suppressing the generation of oxygen gas. It will be possible. The positive electrode liquid containing the positive electrode active material (nickel oxyhydroxide) that is in a charged state by contacting the positive electrode plate 2 is sent from the positive electrode fluid path 5 to the first positive electrode liquid tank 9.

  The supply amount of the positive electrode liquid from the second positive electrode liquid tank 10 to the positive electrode liquid flow path 5 is not particularly limited, and may be appropriately set according to the target charge amount of the power storage device 1. Among the positive electrode active materials contained in the positive electrode liquid, there is also a positive electrode active material that cannot contact the positive electrode plate 2 and passes through the positive electrode liquid flow path 5 in a discharged state. Therefore, it is calculated from the target charge amount. It is preferable that the amount is larger than the supply amount.

On the other hand, at the time of discharging, the reaction reverse to the above (1) and (2) occurs in the negative electrode plate 3. That is, during discharge, the reactions represented by the formulas (5) and (6) occur in the negative electrode plate 3.
MH + OH ⁻ → M + H ₂ O + e ⁻ (5)
H ₂ + 2OH ⁻ → 2H ₂ O + 2e ⁻ (6)
At the time of discharging, in the negative electrode plate 3, hydrogen stored in the hydrogen storage alloy is released as protons and electrons to generate water.

Further, at the time of discharging, a reaction opposite to the above expressions (3) and (4) occurs in the positive electrode plate 2. That is, during discharge, the reactions represented by the above formulas (7) and (8) occur in the positive electrode plate 2. However, in the power storage device 1 of the present embodiment, since the reaction of the formula (4) is suppressed, the reaction of the formula (8) is hard to occur.
NiOOH + H ₂ O + e ⁻ → Ni (OH) ₂ + OH ⁻ (7)
O ₂ + 2H ₂ O + 4e ⁻ → 4OH ⁻ (8)
During discharge, nickel oxyhydroxide is reduced on the positive electrode plate 2 to produce nickel hydroxide.

  When the positive electrode liquid is circulated in the positive electrode fluid path 5 during discharging, the first liquid feeding pump 13 and the second liquid feeding pump 14 are interlocked with each other, and the positive electrode active material (oxy water) stored in the first positive electrode liquid tank 9 is in a charged state. A positive electrode liquid containing nickel oxide) is fed into the positive electrode fluid path 5. In the positive electrode fluid path 5, the charged positive electrode active material (nickel oxyhydroxide) contained in the positive electrode liquid comes into contact with the positive electrode plate 2 to cause the reaction of the formula (7). Therefore, even if the charged positive electrode active material (nickel oxyhydroxide) in the positive electrode plate 2 is reduced, the charged positive electrode active material (nickel oxyhydroxide) is supplied from the positive electrode liquid, and the discharge reaction is continued. Then, the positive electrode plate 2 can be prevented from being over-discharged. The positive electrode liquid containing the positive electrode active material (nickel hydroxide) that has been brought into a discharged state by contacting with the positive electrode plate 2 is sent from the positive electrode fluid path 5 to the second positive electrode liquid tank 10.

  The supply amount of the positive electrode liquid from the first positive electrode liquid tank 9 to the positive electrode liquid flow path 5 is not particularly limited, and may be appropriately set according to the intended discharge amount of the power storage device 1. Among the positive electrode active materials contained in the positive electrode liquid, there is also a positive electrode active material that cannot contact the positive electrode plate 2 and passes through the positive electrode liquid flow path 5 in a charged state. Therefore, it is calculated from the target discharge amount. It is preferable that the amount is larger than the supply amount.

  The reaction of the formula (2) in which hydrogen gas is generated in the negative electrode plate 3 is an efficient reaction with a small overvoltage, while the reaction of the formula (4) in which oxygen gas is generated in the positive electrode plate 2 has a large overvoltage. Not an efficient reaction. Therefore, in the power storage device 1 accompanied by the generation of oxygen gas during charge / discharge, the charge / discharge efficiency is reduced. On the other hand, the power storage device 1 of the present embodiment can suppress the generation of oxygen gas during charging / discharging, and thus can improve charging / discharging efficiency.

  According to the power storage device 1 of the present embodiment having the above-described characteristics, it is possible to suppress the generation of oxygen gas in the positive electrode plate 2 during charge / discharge, so that the oxygen gas can be combined with the hydrogen storage alloy of the negative electrode plate 3. The reaction can be prevented. Therefore, it is possible to efficiently store the electric energy supplied during overcharge while suppressing damage or deterioration of the negative electrode plate 3.

Embodiment 2.
The basic configuration of the power storage device of the present embodiment is the same as that of power storage device 1 of the first embodiment. Therefore, description of the same or equivalent parts as the contents described in the power storage device 1 of the first embodiment will be omitted, and the same configurations will be denoted by the same reference numerals. The power storage device of the present embodiment has the same basic structure as the schematic conceptual diagram of power storage device 1 of the first embodiment.
The power storage device 1 of the present embodiment differs from the power storage device 1 of the first embodiment in that it further includes means for stirring the positive electrode liquid flowing through the positive electrode liquid flow path 5.
The means for stirring the positive electrode liquid flowing through the positive electrode liquid channel 5 is not particularly limited, and various methods can be used. Among them, the method using a magnet or an electromagnet is preferable because it is easy. By stirring the positive electrode liquid by the means, the positive electrode active material contained in the positive electrode liquid easily comes into contact with the positive electrode plate 2, and oxygen gas is further less likely to be generated in the positive electrode plate 2 during charging.

When the positive electrode liquid flowing through the positive electrode liquid flow path 5 is stirred using a magnet or an electromagnet, the positive electrode liquid further contains ferromagnetic particles. The ferromagnetic particles contained in the positive electrode liquid flowing through the positive electrode liquid flow path 5 are attracted to the magnet or the electromagnet, whereby the positive electrode liquid can be stirred. In particular, if an electromagnet is used, the magnetic force can be switched on and off as needed, so that the positive electrode liquid can be efficiently stirred.
The magnet or electromagnet is not particularly limited, and known ones can be used.
Examples of magnets include ferrite magnets, neodymium magnets, samarium cobalt magnets, and alnico magnets.

The ferromagnetic particles contained in the positive electrode liquid are not particularly limited, but are preferably alkali resistant. An example of the ferromagnetic particles is nickel.
The average particle size of the ferromagnetic particles is not particularly limited, but is preferably 0.1 μm or more and 1 mm or less so as not to impair the fluidity of the positive electrode liquid.

  The method of arranging the magnets or electromagnets is not particularly limited, but it is preferable that the magnets or electromagnets are arranged on the positive electrode flow channel plate 6 so as to be spiral along the flow direction of the positive electrode liquid flowing through the positive electrode liquid flow channel 5. Here, FIG. 4 is a top view of the groove portion side of the positive electrode flow channel plate 6 for explaining a state in which a magnet or an electromagnet is arranged in the positive electrode flow channel plate 6 so as to be spiral along the flow direction of the positive electrode liquid. Shown in. As shown in FIG. 4, the magnets or electromagnets 20 are arranged on the side surface and the bottom surface of the groove of the positive electrode flow path plate 6 so as to be spiral with respect to the flow direction D of the positive electrode liquid. By disposing the magnet or electromagnet 20 on the positive electrode flow plate 6 in this way, when the positive electrode liquid containing the ferromagnetic particles flows along the flow direction D, the ferromagnetic particles in the positive electrode liquid are magnetized or As a result of being attracted to the electromagnet 20, the positive electrode liquid flowing through the positive electrode liquid channel 5 can be stirred. As a result, it is possible to increase the positive electrode active material that comes into contact with and reacts with the positive electrode plate 2 while flowing through the positive electrode liquid flow path 5.

Further, when the magnet or electromagnet 20 is brought into contact with the positive electrode liquid, the ferromagnetic particles may be strongly adhered to the surface of the magnet or electromagnet 20, so it is preferable that the magnet or electromagnet 20 is not directly in contact with the positive electrode liquid.
In order to prevent the magnet or electromagnet 20 from coming into direct contact with the positive electrode liquid, the magnet or electromagnet 20 may be embedded when the positive electrode flow path plate 6 is formed by molding. Further, when the positive electrode flow channel plate 6 is formed by press molding or cutting, from the back surface side (the side where the flow channel is not formed) of the positive electrode flow channel plate 6 (the side where the flow channel is formed). It is also possible to form a space in which the magnet or the electromagnet 20 can be arranged so as not to penetrate into), and to arrange the magnet or the electromagnet 20 therein. Further, when a space for arranging the magnet or electromagnet 20 is formed from the surface side of the positive electrode flow channel plate 6, after the magnet or electromagnet 20 is arranged in the space, a resin or the like is used to cover the positive electrode liquid so as not to come into direct contact therewith. You may.

  Further, in the positive electrode liquid flow channel 5, it is preferable that a groove or a protrusion is formed spirally along the flow direction D of the positive electrode liquid in order to agitate the positive electrode liquid due to the flow channel structure. Here, FIG. 5 is a top view of the groove portion side of the positive electrode flow channel plate 6 for explaining a state in which the groove portion or the protrusion portion is spirally formed in the positive electrode liquid flow channel 5 along the flow direction D of the positive electrode liquid. Show. As shown in FIG. 5, the grooves or protrusions 21 are spirally formed on the side surface and the bottom surface of the groove of the positive electrode flow channel plate 6 with respect to the flow direction D of the positive electrode liquid. By forming the groove or protrusion 21 in the positive electrode liquid flow path 5 as described above, the positive electrode liquid flowing through the positive electrode liquid flow path 5 receives a force to rotate along the groove or protrusion 21, and thus the positive electrode liquid Can be agitated. In particular, by arranging the magnets or electromagnets 20 as shown in FIG. 4 and forming the grooves or protrusions 21 as shown in FIG. 5 in the positive electrode liquid flow path 5, the stirring of the positive electrode liquid can be promoted. It will be possible.

  According to the power storage device 1 of the present embodiment having the above-mentioned characteristics, the positive electrode active material contained in the positive electrode liquid is positively charged by efficiently stirring the positive electrode liquid flowing through the positive electrode liquid flow path 5. It becomes easy to contact the plate 2. As a result, the effect of suppressing the generation of oxygen gas in the positive electrode plate 2 during charging / discharging is increased, and it is possible to further prevent oxygen gas from reacting with the hydrogen storage alloy of the negative electrode plate 3.

Embodiment 3.
The basic configuration of the power storage device of the present embodiment is the same as that of the power storage device 1 of the first and second embodiments. Therefore, description of the same or equivalent parts as the contents described in the power storage device 1 of the first and second embodiments will be omitted, and the same components will be denoted by the same reference numerals.

FIG. 6 is a schematic conceptual diagram of the power storage device of the present embodiment.
In FIG. 6, the power storage device 30 is a laminated body in which two unit cells are electrically connected in series, and a negative electrode current collector plate 31 is located below the laminated body and a positive electrode current collector plate is located above the laminated body. 32 is arranged, which is different from the power storage devices 1 of the first and second embodiments. Although FIG. 6 shows a stacked body in which two unit cells are electrically connected in series, the number of unit cells may be three or more.

The negative electrode current collector plate 31 and the positive electrode current collector plate 32 are not particularly limited, and those known in the art can be used.
In the power storage device 30, two adjacent unit cells are stacked such that the positive electrode flow channel plate 6 of one unit cell and the negative electrode flow channel plate 8 of the other unit cell are in contact with each other. At this time, one flow channel plate is used in place of the adjacent positive flow channel plate 6 and negative flow channel plate 8, and groove portions to be the positive electrode liquid flow channel 5 and the negative electrode gas flow channel 7 are formed on both surfaces of this flow channel plate. You may.

  According to the power storage device 30 of the present embodiment having the above characteristics, the plurality of unit cells are electrically connected in series, so that the charging / discharging efficiency can be improved. That is, the voltage can be increased by electrically connecting a plurality of unit cells in series, and the current can be reduced even when charging and discharging the same power. In particular, since the power loss due to electric resistance is proportional to the square of the current, it is possible to reduce the power loss and increase the charging / discharging efficiency by increasing the number of stacked unit cells connected in series to reduce the current. it can.

The power storage devices 1 and 30 of Embodiments 1 to 3 described above are preferably used as a stationary power storage device for the purpose of power storage of natural energy power generation such as solar power generation and wind power generation. it can. The reason is as follows.
Generally, the maximum input / output (kW) is determined by the installed capacity of natural energy power generation such as solar power generation and wind power generation. However, since renewable energy power generation is easily affected by weather conditions, the amount of power generation (kWh) per unit time is not constant. Therefore, the power storage of the natural energy power generation requires a power storage device having a constant maximum input / output (kW) and a variable storage capacity (kWh). Further, considering that the power storage device used for natural energy power generation is generally a stationary type, it is desirable that the power storage device has a compact configuration.

A sealed secondary battery such as a sealed nickel-hydrogen secondary battery or a sealed lithium-ion secondary battery has a variable storage capacity because the storage capacity is limited by the amount of solid active material filled in the battery. .. In order to increase the storage capacity by using the sealed secondary battery, it is necessary to configure the device from a plurality of unit cells. However, increasing the number of unit cells unnecessarily increases the maximum input / output, and cannot be said to be suitable for storage of renewable energy power generation.
On the other hand, the power storage devices 1 and 30 of Embodiments 1 to 3 include a solid active material (for example, a positive electrode active material and a hydrogen storage alloy in which hydrogen is stored) and a fluid active material (for example, hydrogen gas, Since it is used together with the positive electrode liquid), it is possible to alleviate the restriction on the storage capacity of the solid active material. In addition, by changing the capacities of the first positive electrode liquid tank 9, the second positive electrode liquid tank 10, and the negative electrode gas storage tank 11, it is possible to change the storage capacity while making the main bodies of the power storage devices 1 and 30 compact. it can. Moreover, the power storage devices 1 and 30 of Embodiments 1 to 3 can be used even in a region where the solid active material is overcharged, and have a configuration in which unit cells such as the power storage device 30 of Embodiment 3 are stacked. Also, the increase in the maximum input / output can be mitigated. Therefore, the power storage devices 1 and 30 of Embodiments 1 to 3 are particularly suitable for power storage of natural energy power generation as compared with the sealed secondary battery.

Further, although the output of the natural energy power generation is unstable, it is expected that the use of the power storage devices 1 and 30 of the first to third embodiments will contribute to the leveling of the output of the natural energy power generation. The reason is as follows.
In order to equalize the output of natural energy power generation, short cycle fluctuations (output fluctuations in the cycle of several minutes to tens of minutes) and long cycle fluctuations (output fluctuations in the cycle of tens of minutes to several hours) It is necessary to deal with both. Conventionally, output leveling has been studied by combining a power storage device capable of coping with short cycle fluctuations and a power storage device capable of coping with long cycle fluctuations. On the other hand, in the power storage devices 1 and 30 of Embodiments 1 to 3, since the damage or deterioration of the negative electrode plate 3 can be suppressed, it is possible to increase the area of the electrode plate. By making the electrode plate have a large area, the load characteristics are improved and it becomes possible to cope with short-term fluctuations. Further, by storing electric power as hydrogen gas, it becomes possible to cope with long-term fluctuations.

  A redox flow battery is also known as a variable capacity power storage device. However, the redox flow battery requires liquid storage tanks on both the positive electrode side and the negative electrode side, and it is difficult to make the structure compact. Further, in the redox flow battery, there is a possibility that self-discharge occurs due to the mixing of the two polar liquids, resulting in power loss. On the other hand, in the power storage devices 1 and 30 of Embodiments 1 to 3, the liquid storage tank (first positive electrode liquid tank 9 and second positive electrode liquid tank 10) is provided only on the positive electrode plate 2 side, and the negative electrode plate 3 Since the side is solid and gas, self-discharge does not occur due to the mixing of the bipolar liquids unlike the redox flow battery. Therefore, the power storage devices 1 and 30 of Embodiments 1 to 3 are more suitable for the power storage of the natural energy power generation than the redox flow battery.

  In addition, in the power storage devices 1 and 30 of Embodiments 1 to 3, by lengthening the positive electrode liquid pipe 12 and the negative electrode gas pipe 15, the power storage devices 1 and 30 are provided at a first position apart from the unit cells. The positive electrode liquid tank 9, the second positive electrode liquid tank 10 and the negative electrode gas storage tank 11 may be arranged. Therefore, for example, the configurations of the power storage devices 1 and 30 can be flexibly changed according to conditions such as an installation location and an installation area. This facilitates maintenance and operation of the power storage devices 1 and 30.

  DESCRIPTION OF SYMBOLS 1,30 Electric power storage device, 2 Positive electrode plate, 3 Negative electrode plate, 4 Separator, 5 Positive electrode liquid flow path, 6 Positive electrode flow path plate, 7 Negative gas flow path, 8 Negative flow path plate, 9 1st positive electrode liquid tank, 10 2nd positive electrode liquid tank, 11 negative electrode gas storage tank, 12 positive electrode liquid piping, 13 1st liquid feeding pump, 14 2nd liquid feeding pump, 15 negative electrode gas piping, 20 magnet or electromagnet, 21 groove part or protrusion part, 31 Negative electrode current collector plate, 32 Positive electrode current collector plate, D Flow direction.

Claims (13)

A positive electrode plate containing a positive electrode active material,
A negative electrode plate containing a hydrogen storage alloy,
Sandwiched between the positive electrode plate and the negative electrode plate, a separator containing an alkaline electrolyte,
A positive electrode flow channel plate for forming a positive electrode liquid flow channel in which a positive electrode liquid containing a particulate positive electrode active material flows, and the positive electrode plate,
A unit cell including a negative electrode flow channel plate that forms a negative electrode gas flow channel through which a negative electrode gas that is a negative electrode active material flows,
The positive electrode liquid channel is connected to a first positive electrode liquid tank and a second positive electrode liquid tank for sending and receiving the positive electrode liquid,
The positive electrode liquid flow path includes means for stirring the positive electrode liquid flowing therethrough,
The power storage device, wherein the negative electrode gas flow path is connected to a negative electrode gas storage tank that sends and receives the negative electrode gas. The positive electrode liquid further contains ferromagnetic particles, means for agitating the cathode liquid flowing through the cathode liquid flow path, the power storage device according to claim 1, which is a magnet or an electromagnet. The power storage device according to claim 2 , wherein two or more of the magnets or electromagnets are arranged on the positive electrode flow path plate so as to be spiral along the flow direction of the positive electrode liquid. The power storage device according to claim 2 or 3 , wherein the magnet or the electromagnet is arranged so as not to come into direct contact with the positive electrode liquid. The power storage device according to claim 2 , wherein the ferromagnetic particles are nickel particles. The positive electrode active material contained in the positive electrode active material and the positive electrode liquid is contained in the positive electrode plate, according to claim 1 to 5, characterized in that it contains at least one of the nickel hydroxide and nickel oxyhydroxide The power storage device according to claim 1. The anode gas, power storage device according to any one of claims 1 to 6, wherein the hydrogen gas. Power storage device according to any one of claims 1 to 7, two or more of the unit cell is characterized by being electrically connected in series. The cross-sectional shape of the positive electrode liquid channel, rectangular, power storage device according to any one of claims 1 to 8, characterized in that a U-shaped or trapezoidal. The positive electrode liquid channel, power storage device according to any one of claims 1 to 9, characterized in that said cathode grooves or projections helically along the flow direction of the liquid are formed. Power storage device according to any one of claims 1 to 10, characterized in that used in the power storage of natural energy power generation.   A positive electrode plate containing a positive electrode active material,
  A negative electrode plate containing a hydrogen storage alloy,
  Sandwiched between the positive electrode plate and the negative electrode plate, a separator containing an alkaline electrolyte,
  A positive electrode flow channel plate for forming a positive electrode liquid flow channel in which a positive electrode liquid containing a particulate positive electrode active material flows, and the positive electrode plate,
  A negative electrode flow channel plate for forming a negative electrode gas flow channel through which a negative electrode gas that is a negative electrode active material flows, with the negative electrode plate;
Has a unit cell containing
  The positive electrode liquid flow path includes a first positive electrode liquid tank and a second positive electrode liquid tank for sending and receiving the positive electrode liquid.
Connected to the
  The negative electrode gas flow path is connected to a negative electrode gas storage tank for sending and receiving the negative electrode gas,
  The power storage device, wherein the positive electrode active material contained in the positive electrode plate and the positive electrode active material contained in the positive electrode liquid contain at least one of nickel hydroxide and nickel oxyhydroxide.   A positive electrode plate containing a positive electrode active material,
  A negative electrode plate containing a hydrogen storage alloy,
  Sandwiched between the positive electrode plate and the negative electrode plate, a separator containing an alkaline electrolyte,
  A positive electrode flow channel plate for forming a positive electrode liquid flow channel in which a positive electrode liquid containing a particulate positive electrode active material flows, and the positive electrode plate,
  A negative electrode flow channel plate for forming a negative electrode gas flow channel through which a negative electrode gas that is a negative electrode active material flows, with the negative electrode plate;
Has a unit cell containing
  The positive electrode liquid flow path includes a first positive electrode liquid tank and a second positive electrode liquid tank for sending and receiving the positive electrode liquid.
Connected to the
  The negative electrode gas flow path is connected to a negative electrode gas storage tank for sending and receiving the negative electrode gas,
  The power storage device according to claim 1, wherein the positive electrode liquid flow path has a groove or a protrusion formed in a spiral shape along a flow direction of the positive electrode liquid.

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