JP2015162292A - magnesium primary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnesium primary battery which can be activated by just pouring water therein and is arranged so that the gradient of the concentration of an electrolytic solution when pouring water therein can be suppressed.SOLUTION: A magnesium primary battery comprises: a water-insoluble bag body 51; an electrolyte which allows magnesium ions to elute from a magnesium electrode 15, and enclosed in the water-insoluble bag body; and an enclosure 11. The electrolyte is put in the enclosure 11 previously. The magnesium primary battery is activated as a battery by pouring water into the enclosure 11.

Description

  The present invention relates to a magnesium primary battery including a negative electrode of magnesium or a magnesium alloy.

A magnesium-air battery is known as a magnesium primary battery that can generate electricity when injecting electrolytes such as saline and water in natural disasters, storms and floods, and in environments where AC power is difficult to obtain. (For example, refer to Patent Documents 1 and 2). Patent Document 1 discloses a magnesium air battery in which an electrolyte solution holding sheet is wound around a negative electrode plate made of an Mg alloy plate, and a carbon fiber sheet is wound around the outer periphery of the electrolyte solution holding sheet. A system is disclosed in which an electrolyte solution is supplied from a skirt that protrudes downward from the lower end of the liquid holding sheet.
Patent Document 2 discloses a MnO ₂ air electrode constituting an anode, a metal Mg or Mg alloy cathode facing the electrode, a separator interposed between the anode and the cathode, and an air-introducing porous material. In a portable magnesium-air battery composed of a water-soluble sheet and an electrolyte bag having an electrolyte incorporated in water-soluble paper, the electrolyte is wrapped in water-soluble paper and water is poured into the water instantly. A method is disclosed in which an electrolyte is dissolved to form an electrolytic solution.

JP 2011-181382 A JP 2012-256547 A

However, the method of supplying (injecting) the electrolytic solution prepared from the lower end of the electrolytic solution holding sheet cannot be operated as a battery unless an electrolyte such as sodium chloride is available.
In addition, in the method of wrapping the electrolyte in water-soluble paper and supplying water (water injection), when water is injected, the water-soluble paper melts and the electrolyte is exposed at once, so the concentration gradient of the electrolyte temporarily changes. It gets bigger. Therefore, there is a possibility that the negative electrode near the sodium chloride of the electrolyte is partially corroded. Furthermore, when stored in a humid space, the water-soluble paper melts and the electrolyte is exposed, which may corrode parts in the housing, the negative electrode, and the like.

  The present invention has been made in view of the above-described circumstances, and provides a magnesium primary battery that operates only by pouring water and can suppress a concentration gradient of an electrolytic solution when water is poured. It is aimed.

In order to solve the above-described problems, the present invention provides a water-insoluble bag comprising a non-woven fabric or a woven fabric provided with an electrolyte contained in an electrolyte capable of eluting magnesium ions from a negative electrode of magnesium or a magnesium alloy. A magnesium primary battery is provided, which is preliminarily put in a casing and is operated as a battery by pouring water into the casing.
According to this configuration, the battery operates just by pouring water, and when the water is poured, the electrolyte in the bag gradually dissolves to suppress the concentration gradient of the electrolyte, and the bag is stored when stored. The body can suppress the exposure of the electrolyte and suppress the corrosion of the negative electrode of magnesium or a magnesium alloy.

The main component of the electrolyte is preferably sodium chloride. According to this configuration, the electrolyte is not easily affected by humidity from the viewpoint of deliquescence, and the exposure of the electrolyte during storage is suppressed, and corrosion of the magnesium or magnesium alloy negative electrode or the like is easily suppressed.
The mass of the electrolyte is preferably in the range of 4% to 18% with respect to the mass of water to be poured. According to this configuration, it is possible to efficiently avoid the situation in which the electrolytic solution has a large resistance and the voltage decreases, and the situation in which the electrolyte is saturated and the discharge amount decreases, and the battery performance can be improved.

The bag body may be provided directly below the water inlet of the housing. According to this configuration, the electrolyte in the bag can be quickly dissolved with water from the water inlet, and it becomes easy to take out electricity from the moment of pouring.
The electrolyte may be in the form of powder or granules, and may be disposed at a water immersion height near the upper surface of the electrolyte solution. According to this configuration, the electrolyte can be efficiently dissolved by water injection.

Further, the casing may have a foaming member that foams when in contact with the water, and the foaming member may be magnesium metal or magnesium alloy. According to this configuration, when water is poured, the electrolytic solution can be stirred by the foaming member, the concentration gradient of the electrolytic solution can be suppressed, and a different kind of substance is newly used in the housing. There is no need, and there is also an effect that there is no generation of a substance that affects the discharge reaction.
The foam member may be disposed and fixed below the electrolyte. According to this configuration, the electrolytic solution can be stirred in a lower portion where the concentration tends to be high, and the concentration difference can be effectively eliminated.

Further, the foamed member may be at least one of a flat plate provided with a powdery or lattice-like groove, and a structure where a lattice-like groove is provided on the surface of the negative electrode opposite to the positive electrode. According to this configuration, the foaming action can be generated with a simple configuration.
Further, the negative electrode and the positive electrode may be arranged in the casing without using a separator, and the bag may be provided between the negative electrode and the positive electrode. According to this configuration, it is possible to efficiently perform the discharge reaction to easily secure the battery performance, and it is possible to arrange the bag body by efficiently using the empty space between the negative electrode and the positive electrode.

Further, the negative electrode and the positive electrode may be disposed in the casing without using a separator, and the bag may be provided between the negative electrode and the inner wall of the casing. According to this configuration, the electrolyte can be prevented from immediately moving to the space between the negative electrode and the positive electrode, which is the discharge reaction region, and the concentration unevenness in the discharge reaction region is suppressed, and the discharge reaction caused by the concentration unevenness is suppressed. The influence on can be suppressed.
Moreover, the said housing | casing may be provided with the cover part in which the said water inlet is provided, and you may make it the said bag body attach to the said cover part. According to this configuration, the bag body can be easily attached.

  Further, the present invention includes a housing in which a negative electrode made of magnesium or a magnesium alloy is disposed, and an electrolyte contained in an electrolytic solution in which magnesium ions can be eluted from the negative electrode in the housing, and a solvent for the electrolytic solution Provided is a magnesium primary battery comprising a foaming member that foams by contact with water, wherein the foaming member is made of magnesium metal or a magnesium alloy, and operates as a battery by pouring water into the housing. . According to this configuration, the battery can be operated only by pouring water, and the electrolytic solution can be stirred by the foamed member when water is poured, so that the concentration gradient of the electrolytic solution can be suppressed.

  ADVANTAGE OF THE INVENTION According to this invention, while operating by only pouring water, the magnesium primary battery which can suppress the concentration gradient of the electrolyte solution at the time of pouring water can be provided.

It is a perspective view of the magnesium air battery which concerns on this embodiment. It is the disassembled perspective view which showed the air electrode with the periphery structure. It is the figure which showed the internal structure of the magnesium air battery typically. It is the figure which showed typically the internal structure of the magnesium air battery at the time of disposing a bag body dispersively. It is the figure which showed the discharge curve of Examples 1-3. It is a perspective view of the magnesium air battery which concerns on a modification. It is the figure which showed typically the internal structure of the magnesium air battery which concerns on other embodiment. It is the figure which showed typically the internal structure of the magnesium air battery which concerns on a modification. It is the figure which showed the time change of a voltage. It is the figure which showed the time change of the upper and lower density difference. It is the figure which expanded a part of FIG.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view of a magnesium air battery 10 (magnesium primary battery) according to an embodiment of the present invention.
As shown in FIG. 1, the magnesium-air battery 10 includes a thin rectangular parallelepiped housing (support frame) 11 formed of a synthetic resin material, a rectangular air electrode 13 exposed outside the housing 11, A rectangular magnesium electrode (metal electrode) 15 (FIG. 3) accommodated in the housing 11 is provided. The magnesium-air battery 10 of this configuration is a primary battery in which the air electrode 13 acts as a positive electrode and the magnesium electrode 15 acts as a negative electrode.

FIG. 2 is an exploded perspective view showing the air electrode 13 together with the peripheral configuration.
The air electrode 13 is integrally formed by laminating an air electrode body 31, an insulating porous sheet 33, and a net-like support 35, and the air electrode 13 is provided on the housing 11 via the air electrode side panel 23 having an opening 23A. It is attached to one side. The air electrode 13 is exposed to the outside through the opening 23A of the air electrode side panel 23, and is also exposed to the inside of the housing 11 through an opening (not shown) formed on one side surface of the housing 11. And water permeability.

The air electrode main body 31 is formed by applying a conductive material slurry adjusted to a predetermined viscosity to a current collector and firing it. Specifically, ketjen black powder is used as a conductive material, and this and water are stirred and mixed, and then these are put into an aqueous dispersion of polytetrafluoroethylene (PTFE) used as a binder and stirred and mixed. To prepare a conductive material slurry having a predetermined viscosity. And after apply | coating this slurry to the collector which consists of a foam nickel with a thickness of 1.1 mm, it dries at 100 degreeC, bakes at 270 degreeC, and becomes an air electrode main body.
The periphery of the current collector is coined in advance, and a tab portion 31A (FIG. 2) that extends upward and is connected to the positive electrode terminal 19 is formed in a part of the current collector.

As the conductive material, in addition to the carbon black such as Ketjen Black, carbon whisker, graphite, graphite whisker, activated carbon, carbon nanotube, carbon nanowire, carbon nanohorn and other carbon materials, copper, aluminum and other metal materials, Organic conductive materials such as polyphenylene derivatives can be used.
Moreover, as a catalyst, a catalyst for efficiently performing oxygen reduction / oxidation reaction is preferable, and in addition to the above-described platinum, a metal such as cobalt or manganese dioxide, an oxide, or the like may be used.
As the binder, in addition to the above-mentioned PTFE, fluorine-based resins such as polyvinylidene fluoride, rubbers such as styrene-butadiene rubber, celluloses such as carboxymethylcellulose, and the like can be used.
Further, as the current collector, a metal porous body such as a mesh-like metal, carbon paper using carbon fibers, or the like can be used in addition to the foam metal such as nickel foam.

  The insulating porous sheet 33 is a porous film having a pore diameter of 5 to 40 μm and has water repellency that allows oxygen to permeate and suppresses moisture permeation. In the present embodiment, a porous sheet made of polytetrafluoroethylene (PTFE) is used, and two sheets of this insulating porous sheet are stacked and simultaneously bonded to one surface of the fired air electrode body 31. . The insulating porous sheet is formed to be the same as or slightly larger than the filling application surface excluding the coined portion around the current collector, and the size of the air electrode body 31 in this embodiment is vertical. It is formed to have a thickness of 100 mm, a width of 200 mm, and a thickness of 0.5 mm.

  In addition to the PTFE described above, the insulating porous sheet 33 is, for example, chloroprene, silicone resin, polytrimethylsilylpropyne, polypropylene, polymethylpentene, polyisoprene, polybutadiene, chloroprene, polystyrene, polyethylene, polycarbonate, silicon polycarbonate. A copolymer, polyphenylene sulfide, polyphenylene oxide, polyphenylene sulfide, polyester, or the like can be used.

  The net-like support 35 is made of an expanded metal made of stainless steel. In this embodiment, the reticulated support 35 is an alloy in which chromium and nickel are mixed with iron as a main raw material, and is a strand having a width of 0.6 mm and a fine mesh having a length of 1.7 mm and a width of 2.2 mm. Is. The net-like support 35 is disposed on the outer surface of the insulative porous sheet 33 that is pressure-bonded, and the periphery of the air electrode body 31 is bound together with a binder. Thereby, the air electrode main body 31, the insulating porous sheet 33, and the net-like support body 35 are laminated integrally to form the air electrode 13.

As the net-like support 35, in addition to the above-described expanded metal made of stainless steel, for example, a metal net made of a metal or an alloy, a punching sheet made of a relatively thick synthetic resin such as polytetrafluoroethylene, or the like is used. Can do.
In the present embodiment, the air electrode 13 is attached to the opening 23 </ b> A of the air electrode side panel 23 with a binder so as to expose the mesh support 35. In addition, not only this structure but you may attach so that the air electrode 13 may be pinched | interposed with two synthetic resin panels with an opening part.

As described above, since the mesh support 35 is disposed on the surface in contact with the air via the insulating porous sheet 33, the material of the mesh support 35 can be selected without worrying about corrosion and the like. The degree of freedom can be improved, and the mechanical strength can be maintained even if the thickness of the air electrode 13 is reduced in order to improve the performance. Therefore, there is provided an air electrode 13 that can withstand pressurization by an electrolytic solution and pressure by hydrogen gas and that can be used for a long time without deformation of the air electrode 13 or leakage of the electrolytic solution due to the deformation. it can.
In the present embodiment, the air electrode 13 is formed in a horizontally long shape, but the present invention is not limited to this, and the shape of the air electrode can be freely designed such as being used in a vertically long shape.

FIG. 3 is a diagram showing the internal structure of the magnesium-air battery 10 as viewed from the short side surface, and schematically showing the internal structure of the cross section.
The housing 11 is open at the upper surface, and the upper surface is covered with a rectangular plate-shaped lid 27. A water injection port 27A penetrating the lid 27 up and down is provided at the center in the longitudinal direction of the lid 27, and a valve body 29 for venting gas is detachably provided at the water injection port 27A.
A negative electrode terminal 17 connected to the magnesium electrode 15 is provided at one end portion (right end portion in FIG. 1) of the lid portion 27, and the air electrode 13 is disposed at the other end portion (left end portion in FIG. 1) of the lid portion 27. And a positive electrode terminal 19 extending from the gap between the lid portion 27 and the air electrode side panel 23 is formed. In FIG. 3, the air electrode side panel 23 is omitted.

The magnesium electrode 15 is disposed opposite to the air electrode 13 at a predetermined distance, and is attached to the inner side wall of the long side surface of the housing 11 by adhesion. The magnesium electrode 15 may be attached to the housing 11 via a four-sided frame spacer, or may be attached to the housing 11 by a method other than bonding.
The magnesium electrode 15 is formed of a magnesium alloy having a predetermined composition. In the present embodiment, the magnesium electrode 15 is slightly smaller than the air electrode 13 described above, and is formed to have a length of 90 mm, a width of 190 mm, and a thickness of 1.4 mm. In FIG. 3, symbol HL indicates the upper surface of the electrolytic solution that is filled with water in the housing 11.

When using the magnesium-air battery 10, a water-soluble electrolyte solution capable of eluting magnesium ions from the magnesium electrode 15 is filled between the air electrode 13 and the magnesium electrode 15.
As the electrolytic solution, a sodium chloride aqueous solution containing sodium ions is used from the viewpoint of high safety and conductivity, but it is not particularly limited thereto.

The magnesium-air battery 10 configured as described above has a positive electrode reaction (O ₂ + 2H ₂ O + 4e ⁻⁾ by contacting the air electrode body 31 with oxygen and electrolyte supplied through the insulating porous sheet 33 in the air electrode 13. → 4OH ⁻ ) proceeds, and the negative electrode reaction (Mg → Mg ²⁺ + 2e ⁻ ) proceeds at the magnesium electrode 15 to discharge. The total reaction in the magnesium air battery 10 is Mg + 1 / 2O ₂ + H ₂ O → Mg (OH) ₂ .

By the way, the magnesium-air battery 10 is stored in a state where no electrolyte is present therein, and is used as a primary battery for disaster that is filled with the electrolyte when used as a battery.
In order to improve the function as a primary battery for disasters, in this embodiment, a bag body 51 (FIG. 3) that encloses an electrolyte is provided in the casing 11 immediately below the water inlet 27A. By pouring water as a solvent of the electrolytic solution from the water port 27A, the electrolyte in the bag body 51 is gradually dissolved to become an electrolytic solution. In addition, the code | symbol W has shown the flow of water when pouring water from the water inlet 27A in FIG.

The above-described bag body 51 is formed of a water-insoluble material made of a nonwoven fabric or a woven fabric, so that the electrolyte is not exposed to the outside or leaked out even if it is in various postures such as upside down. It contains sodium chloride, an electrolyte.
More specifically, the bag body 51 has a gap smaller than the particle diameter of sodium chloride, and does not allow solid sodium chloride to pass through, but has water permeability. Specifically, since the particle diameter of sodium chloride is most commonly used at 0.4 mm, the average pore diameter of the bag body 51 is preferably 0.05 mm to 0.3 mm, which is smaller than the particle diameter of the sodium chloride.

  The bag body 51 is preferably made of hydrophilic chemical fibers such as nylon. In this case, a fabric made of a nonwoven fabric or a woven fabric can be easily welded by heat sealing, and the bag body 51 can be easily manufactured. In particular, when a non-woven fabric is used, mass production is facilitated and material costs are easily suppressed. In addition, since chemical fibers are used, it is easy to finely adjust the average pore diameter and strength of the bag body 51, and there are also advantages that degradation can be suppressed over a long period of time compared to the case of using natural fibers. .

In this way, the water-insoluble bag body 51 that encloses the electrolyte in the housing 11 is charged, so that when the water is poured, as compared with the case where the electrolyte is wrapped in water-soluble paper. The electrolyte can be gradually dissolved from the body 51, and an increase in the concentration gradient of the electrolytic solution can be suppressed.
For this reason, it is possible to avoid the uneven reaction of the magnesium electrode 15 that occurs when the concentration gradient of the electrolytic solution rises at once. Moreover, since the bag body 51 is not dissolved by moisture when stored in a humid space, the exposure of the electrolyte can be suppressed, and the electrolyte adheres to the components in the casing 11 and the magnesium electrode 15 to corrode them. It becomes possible to avoid the situation.

The mass in the case of using sodium chloride as the electrolyte is preferably in the range of 4% to 18% with respect to the mass of the poured water. As a result of verification by the inventors, when it is less than 4%, the resistance of the electrolytic solution is increased and the voltage drop is increased, so that it is confirmed that the voltage is low and the power that can be taken out is reduced. On the other hand, when it was more than 18%, sodium chloride was saturated and deposited at the end of discharge, and it was confirmed that the sodium chloride remained in the gap between the cells to inhibit the discharge reaction and could not be discharged.
In addition, when using sodium chloride as said electrolyte, you may include other than sodium chloride. In short, in this case, the main component of the electrolyte may be sodium chloride, and may contain other components.

Next, the layout and the like of the bag body 51 will be described.
First, as shown in FIG. 3, the magnesium-air battery 10 of this configuration has an air electrode 13 and a magnesium electrode 15 arranged without using a separator, and a bag body 51 between the air electrode 13 and the magnesium electrode 15. It is the structure which arranged. According to this configuration, the above-described discharge reaction can be efficiently performed by using no separator, and a wide space SA between the air electrode 13 and the magnesium electrode 15 can be secured. Therefore, it is possible to efficiently arrange the bag body 51 using this empty space SA. In other words, the bag body 51 can be disposed without providing a separate empty space, and an increase in the size of the magnesium-air battery 10 can be avoided.

As shown in FIG. 3, the bag body 51 is provided in the lid portion 27 having the water injection port 27 </ b> A, and is disposed immediately below the water injection port 27 </ b> A and at a height to be immersed near the liquid surface of the electrolytic solution. If the bag body 51 is disposed immediately below the water injection port 27A, the electrolyte in the bag body 51 can be quickly dissolved by the water from the water injection port 27A, and the discharge reaction is started at the moment of water injection, making it easy to take out electricity.
Further, since the bag body 51 is attached to the lid portion 27, the bag body 51 can be easily attached. In this case, it is easy to arrange the bag body 51 so as not to contact the magnesium electrode 15, and it is easy to avoid a situation in which the design of the magnesium electrode 15 and the air electrode 13 is changed to arrange the bag body 51.

Moreover, not only when using the single bag body 51, as shown in FIG. 4, you may distribute and arrange the bag bodies 51 in two places. In the configuration shown in FIG. 4, the bag body 51 is arranged directly below the water inlet 27 </ b> A with a space in the vertical direction, and one bag body 51 is attached in the vicinity of the water inlet 27 </ b> A directly below the water inlet 27 </ b> A having the water inlet 27 </ b> A. The other bag body 51 is attached to the bottom 11T of the housing 11 directly below the water injection port 27A.
According to this configuration, since the plurality of bag bodies 51 are arranged directly below the water injection port 27A, the electrolyte in each bag body 51 can be rapidly dissolved with water from the water injection port 27A. In particular, since the electrolyte can be efficiently dissolved at the start of water injection, it is easy to take out electricity by accelerating the discharge start timing, and it is easy to avoid partial corrosion by reducing the concentration gradient at the start of water injection. In addition, since hydrogen is generated after the discharge is started, the electrolytic solution is agitated by the generation of this hydrogen, and the concentration gradient can be further reduced.

Moreover, since the bag bodies 51 are arranged in a distributed manner, the electrolytic mass per one bag body 51 can be reduced as compared with the case where a single bag body 51 is arranged, and each of the pieces for wrapping a necessary amount of electrolyte. The bag body 51 can be made small. Therefore, even when the empty space SA between the air electrode 13 and the magnesium electrode 15 is narrow, the bag body 51 can be easily arranged in the empty space SA. Further, since the bag body 51 is small, it is easy to dispose it away from the magnesium electrode 15.
In addition, since the bag body 51 is attached to the lid portion 27 and the bottom portion 11T of the housing 11, it is easy to arrange the bag body 51 so as not to contact the magnesium electrode 15. It becomes easier to avoid design changes.

  Subsequently, examples and comparative examples will be described. In the following examples and comparative examples, a magnesium air battery is used, but the present invention is widely applicable to a magnesium primary battery using sodium chloride as an electrolyte. For example, it can be applied to a magnesium lead chloride battery, a magnesium silver chloride battery, a magnesium manganese dioxide battery, and the like.

  In addition, as described above, when the bag bodies 51 are distributed in two places, they may be distributed in the horizontal direction instead of in the vertical direction. In this case, for example, the bag body 51 is arranged so as to be at the position of the dividing line obtained by dividing the housing 11 of FIG. 1 into three in the lateral direction, and the water injection port 27A and the valve body 29 are provided on the upper portion of each bag body 15. Deploy.

Example 1
Using a non-woven fabric made of nylon, 33 g of sodium chloride corresponding to 10% of the electrolyte weight (corresponding to 11% of the amount of water to be poured) is wrapped, and the magnesium is opposed to the magnesium alloy as the negative electrode. The air battery 10 was attached directly below the water injection port 27 </ b> A in the housing 11. Then, after storing for one week in a high-temperature and high-humidity space at a temperature of 40 ° C. and a humidity of 80%, 300 g of water was poured and the cell voltage was measured when discharged at a current density of 25 mA / cm ² .

(Example 2)
Using nylon non-woven fabric, 9.3 g of sodium chloride corresponding to 3% (3.1% with respect to the amount of water to be poured) of the electrolyte is wrapped so as to face the magnesium alloy as the negative electrode. The magnesium-air battery 10 was attached immediately below the water injection port 27A in the housing 11. Then, after storing for one week in a high-temperature and high-humidity space at a temperature of 40 ° C. and a humidity of 80%, 300 g of water was poured and the cell voltage was measured when discharged at a current density of 25 mA / cm ² .

(Example 3)
Using a non-woven fabric made of nylon, 70 g of sodium chloride corresponding to 19% (23% of the amount of water to be poured) with respect to the weight of the electrolyte is wrapped, and the magnesium-air battery is opposed to the magnesium alloy as the negative electrode. It was attached directly below the water injection port 27 </ b> A in the ten cases 11. Then, after storing for one week in a high-temperature and high-humidity space at a temperature of 40 ° C. and a humidity of 80%, 300 g of water was injected, and the cell voltage was measured when discharged at a current density of 25 mA / cm ² .

Example 4
Using a non-woven fabric made of nylon, a magnesium-air battery is wrapped with 33 g of sodium chloride corresponding to 10% (11% with respect to the amount of water to be poured) with respect to the weight of the electrolyte so as to face the magnesium alloy as the negative electrode. It was attached to the bottom part 11T located in the place which is not just under the water injection port 27A in the housing | casing 11 of ten. Then, after storing for one week in a high-temperature and high-humidity space at a temperature of 40 ° C. and a humidity of 80%, 300 g of water was poured and the cell voltage was measured when discharged at a current density of 25 mA / cm ² .

(Comparative Example 1)
Using water-soluble paper, wrapping 33 g of sodium chloride corresponding to 10% of the electrolyte weight (corresponding to 11% of the amount of water to be poured), and facing the magnesium alloy as the negative electrode The air battery 10 was attached directly below the water injection port 27 </ b> A in the housing 11. Then, after storing for one week in a high-temperature and high-humidity space at a temperature of 40 ° C. and a humidity of 80%, 300 g of water was poured and the cell voltage was measured when discharged at a current density of 25 mA / cm ² .

(Comparative Example 2)
The magnesium-air battery 10 does not contain an electrolyte, and is stored in a hot and humid space at a temperature of 40 ° C. and a humidity of 80% for one week. Then, 300 g of a 10% sodium chloride aqueous solution is injected into the electrolyte weight. The cell voltage when discharged at a current density of 25 mA / cm ² was measured.

FIG. 5 shows the discharge curves of Examples 1 to 4. In FIG. 5, symbol f1 indicates the discharge curve of the first example, symbol f2 indicates the discharge curve of the second example, symbol f3 indicates the discharge curve of the third example, and f4 indicates the discharge curve of the fourth example. ing.
In addition to the cell voltage at the time of discharge, Table 1 shows a result of visually confirming whether sodium chloride leaked after storage for one week, and whether or not sodium chloride was deposited at the end of discharge. The results confirmed by the above are also shown.

As shown in Table 1, in Examples 1 to 4, sodium chloride did not leak even after storage for one week. For this reason, even if it is assumed that a plurality of magnesium-air batteries are wrapped and stored together, fully opened in the event of a disaster, and some or all of them are not used immediately, and a week has passed, It turns out that there is no problem.
In other words, even if the magnesium-air battery is not wrapped one by one, there is no problem in use in the above assumption, and it can be provided at a low cost because it is wrapped together.
Moreover, since it will become difficult to receive the influence of external humidity if it is made into the lapping state, in the lapping state, leakage of sodium chloride due to the influence of moisture can be avoided for a longer period of time. By these, it can be said that it is a magnesium air battery suitable for long-term storage.

Moreover, in Example 1, 3, the cell voltage (1.0V or more) equivalent to the magnesium air battery which injects electrolyte solution at the time of use like the comparative example 2 was obtained. From this, the battery can be used if water can be prepared while obtaining battery performance comparable to a magnesium-air battery that injects an electrolyte during use, so that the advantage that it can be used anywhere is obtained. .
However, since Example 3 has more sodium chloride than Example 1 and exceeds 18% with respect to the amount of water to be poured, it was confirmed that sodium chloride was saturated and precipitated at the end of discharge. It was. When sodium chloride is deposited, the discharge reaction is hindered, so the discharge duration is slightly shorter than in Example 1, but the cell voltage is the highest among the five levels (see FIG. 5).

  On the other hand, since Example 2 had less sodium chloride than Example 1 and was less than 4% with respect to the amount of water poured, the cell voltage was as low as 0.7V. When the voltage is low, the electric devices that can be driven are restricted, and the use of the battery is restricted. In other words, the battery of Example 2 may be used when using an electric device with a low voltage.

  Further, in Example 4, compared with Example 1, the position of the bag body 51 wrapped with sodium chloride is not directly below the water inlet 27A, so the electrolyte cannot be dissolved quickly, and electricity is supplied from the moment of water injection. Hard to take out. Therefore, it took a long time for the cell voltage to reach 1.0V. When the voltage is low, the electric devices that can be driven are restricted, and the use of the battery is restricted. In other words, the battery of Example 4 may be used when using an electric device with a low voltage.

On the other hand, in Comparative Example 1, sodium chloride leaked after storage for one week. For this reason, there is a possibility that the components, the negative electrode, and the like in the housing 11 are corroded, which is disadvantageous in terms of storage stability.
Further, in Comparative Example 2, although storage stability and battery performance are obtained, as described above, it is necessary to procure an electrolyte when using the battery, and the use place is restricted.

As described above, in the magnesium-air battery 10 of the present embodiment, an electrolyte capable of eluting magnesium ions from the magnesium electrode 15 is wrapped in a water-insoluble bag body 51 and placed in the housing 11 in advance. 11 is operated as a battery by pouring water into it, so that it operates as a battery simply by pouring water, and when the water is poured, the electrolyte in the bag 51 gradually melts to suppress the concentration gradient. In addition, during storage, the bag body 51 can suppress the exposure of the electrolyte and suppress the corrosion of the magnesium electrode 15 and the like.
Further, since the main component of the electrolyte is sodium chloride, for example, at a temperature of 20 ° C., it does not show deliquescence up to a humidity of 75% and is hardly affected by humidity. This also suppresses the exposure of the electrolyte during storage and makes it easier to suppress corrosion.

Moreover, when the mass of the electrolyte is in the range of 4% to 18% with respect to the mass of the water to be poured, the electrolyte is saturated and the voltage is lowered and the electrolyte is saturated and the discharge amount is small. Can be efficiently avoided, and battery performance can be improved.
Further, when the bag body 51 is provided immediately below the water inlet 27A of the housing 11, the electrolyte in the bag body 51 can be quickly dissolved by the water from the water inlet 27A, and it becomes easy to take out electricity at the moment of water injection. .
In addition, since the electrolyte is powdery or granular and is disposed at a height of water immersion near the upper surface of the electrolytic solution, the electrolyte can be efficiently dissolved by water injection.

Further, the magnesium electrode 15 and the air electrode 13 are arranged without using a separator, and the bag body 51 is provided between the magnesium electrode 15 and the air electrode 13, so that the discharge reaction is efficiently performed to ensure the battery performance. In addition, it is possible to arrange the bag body 51 by efficiently using the empty space SA between the magnesium electrode 15 and the air electrode 13.
Moreover, since the bag body 51 is attached to the lid part 27 provided with the water injection port 27A, the bag body 51 can be easily attached. In this case, it becomes easy to avoid design changes of the magnesium electrode 15 and the air electrode 13 in order to arrange the bag body 51.

  In this embodiment, the case where the bag body 51 that encloses the electrolyte is provided in the upper part in the housing 11 has been described. However, the present invention is not limited thereto, and the bag body 51 is disposed in the lower part in the housing 11 as shown in FIG. May be provided. Even in the case of FIG. 6, the efficiency is lower than in the case of being provided immediately below the water injection port 27 </ b> A, but the electrolyte in the bag body 51 can be dissolved with water from the water injection port 27 </ b> A.

Next, a magnesium air battery 100 (magnesium primary battery) according to another embodiment of the present invention will be described.
FIG. 7 is a diagram showing the internal structure of the magnesium-air battery 100 as viewed from the short side surface, and schematically showing the internal structure of the cross section. In addition, the same code | symbol is attached | subjected to the part similar to the above.
The magnesium-air battery 100 includes a hollow box-shaped casing (support frame) 111 formed by folding a single foldable sheet material in two, overlapping and joining the both side edges and bending the sheet material. ing. The casing 111 is fitted with an air electrode 13 and accommodates a magnesium electrode (metal electrode) 15 so as to face the air electrode 13.

The casing 111 integrally includes a rectangular bottom portion 112, a rectangular front wall portion 113, a rectangular rear wall portion 114, and left and right side wall portions 115. The front wall 113 is provided with a rectangular opening 23A, and the air electrode 13 is disposed in the opening 23A.
The bottom 112 is formed in a downwardly convex V-shape when viewed from the side. The lower end of the magnesium electrode 15 is guided by the inclination of the bottom 112 and fits into the downwardly projecting portion 112A, and the lower end of the magnesium electrode 15 is easily positioned. Further, spaces SF and SR having the same width are provided on both sides of the magnesium electrode 15.

  The lid portion 27 that covers the upper surface portion of the housing 111 is formed by bending the upper ends of the front wall portion 113 and the rear wall portion 114. In this case, the upper end of the front wall portion 113 includes a first bent portion 113F1 that keeps the distance between the magnesium electrode 15 and the air electrode 13 properly, and second bent portions 113F2-1 and 113F2- that sandwich the magnesium electrode 15 from above. 2 to form. In addition, the upper end of the rear wall portion 114 has a first bent portion 114R1 that keeps the distance between the magnesium electrode 15 and the air electrode 13 properly, and second bent portions 114R2-1 and 114R2-2 that sandwich the magnesium electrode 15 from above. And folded to form.

  Here, the second bent portions 113F2-1 and 113F2-2 are provided at different positions in the depth direction of the housing 11, and one second bent portion 113F2-1 is bent in front of the magnesium electrode 15, and the other The second bent portion 113 </ b> F <b> 2-2 is a portion bent beyond the magnesium electrode 15. The second bent portions 114R2-1 and 114R2-2 are also provided at different positions in the depth direction of the housing 11, and the one second bent portion 114R2-2 is bent in front of the magnesium electrode 15 and the other The second bent portion 114 </ b> R <b> 2-1 is a portion bent beyond the magnesium electrode 15. In this way, the upper part of the magnesium electrode 15 can be firmly supported.

The casing 111 is made of a sheet material containing paper. As the sheet material, paper having both surfaces laminated with a heat-fusible resin (for example, polyethylene (PE)), that is, laminated paper (also referred to as double-sided laminated paper) is used. When laminated paper is used for the casing 111, the electrolyte does not ooze out (leak), and is lighter and cheaper than when a metal can or a resin container is used.
The sheet material containing paper in this configuration is a composite of paper and a heat-fusible resin by laminating or the like.
The ratio of the paper in the sheet material is preferably more than 50%. The exterior body 71 having this configuration can be discarded as, for example, paper waste by setting the paper ratio to exceed 50%. As the paper, paper having a relatively thick strength, such as a coated ball, an uncoated ball, a paperboard, and a cardboard, can be suitably used. As the heat-fusible resin, it is possible to form a liquid-tight box by joining sheet materials by heat-sealing, and any resin can be used as long as it can be heat-sealed. However, it is preferable to use a polyolefin resin such as polyethylene, polypropylene, and ethylene-vinyl acetate copolymer. The thickness of the heat-adhesive resin is at least 10 μm, preferably 20 μm or more in order to obtain a sufficient heat-sealed state. The surface on the inner surface side of the exterior body is preferably set to a thickness of 40 μm or more in order to ensure sealing performance.

By the way, when the inventors examined, when the amount of electrolyte and the amount of water injection increased as in the case of a large battery, it took time to completely dissolve the electrolyte. Unevenness occurs in the concentration of the liquid. In this case, due to the specific gravity of fresh water and sodium chloride aqueous solution, a region with a high salinity concentration is formed in the vicinity of the bottom 112 of the casing 111, and in the battery reaction region where the air electrode 13 and the magnesium electrode 15 face each other, If the concentration becomes low and the electrolytic solution is stirred, or the magnesium-air battery 100 is shaken, there is a possibility that a sufficient electromotive force cannot be obtained.
However, a battery structure that allows the inside of the magnesium-air battery 100 to be stirred is hardly considered in practice. In addition, shaking the magnesium-air battery 100 causes a leakage of the electrolyte. In addition, depending on the battery such as a large battery, it may be difficult to shake.
Therefore, in this configuration, as shown in FIG. 7, in addition to the bag body 51 that encloses the electrolyte, a foam member 121 that foams when in contact with water is disposed in the casing 111 of the magnesium-air battery 100. Yes.

  More specifically, the bag body 51 is provided directly below the water injection port 27A in the space SR, that is, in the space between the magnesium electrode 15 and the inner wall surface (rear wall portion 114) of the housing 111. Here, the water injection port 27A is formed by providing a notch in the portion (first bent portion 114R1) of the lid portion 27 formed by bending the upper portion of the rear wall portion 114, and a bag body is formed in the first bent portion 114R1. 51 is suspended and supported. In addition, when the support strength of the bag body 51 is insufficient only by the first bent portion 114R1, the bag body 51 may be attached to another portion of the rear wall portion 114.

As shown in FIG. 7 as an example, the foam member 121 is disposed on the bottom 112 in the space SR, and is on the bottom 112 in the space SR and between the water inlet 27 </ b> A and directly below the bag body 51. Be placed. The material of the foam member 121 is magnesium metal or a magnesium alloy, and at least one of powder or particles formed from this material, or a plate-like or rod-like member is applied. When a plate-like member is applied, it is preferable to increase the surface area as compared with a simple shape by providing a lattice-like groove.
With the above configuration, when water is poured, a foaming action is generated from the moment when the water touches the foam member 121, and the electrolytic solution is agitated to effectively suppress the concentration difference (concentration gradient) of the electrolytic solution. it can. Therefore, it is possible to provide a magnesium-air battery 100 that operates only by pouring water, suppresses the concentration gradient of the electrolyte when pouring water, and can suppress corrosion of the negative electrode and the like during storage. it can.

  Moreover, since the foam member 121 made of magnesium metal or magnesium alloy is used, it is not necessary to newly use a different kind of substance in the casing 111 as a battery constituent member, and the processing waste generated at the time of manufacturing the magnesium electrode 15 is utilized. can do. Moreover, since the reaction product after foaming and the reaction product by discharge are the same, there is no generation of a substance that affects the discharge reaction.

The electrolyte is in the form of powder or particles. The electrolyte is placed in the bag 51 described above, and is arranged at a height to be submerged in the vicinity of the electrolyte surface immediately below the water injection port 27A in the casing 111. The As a result, a part of the electrolyte is dissolved by the water injection, and then the foaming action is generated by the magnesium metal or magnesium alloy for foaming, and the electrolytic solution is stirred to dissolve the remaining electrolyte and eliminate the concentration difference. it can.
In addition, by placing the electrolyte in the bag 51 and placing it in the upper part of the housing 111, the position of the electrolyte can be maintained, and the electrolyte dissolves due to the difference in specific gravity. It can be solved.

  In addition, since the foam member 121 is disposed and fixed in the casing 111 below the electrolyte, the electrolyte in the region where the concentration of the electrolyte is high (the lower region of the casing 111) is efficiently stirred due to the specific gravity. At the same time, it is possible to avoid free movement of magnesium metal or magnesium alloy for foaming due to buoyancy of bubbles. Therefore, as shown in FIG. 7, when the foam member 121 is disposed in the space SR between the magnesium electrode 15 and the inner wall surface (rear wall portion 114) of the casing 111, It can suppress that a magnesium alloy moves to space SF between the magnesium electrode 15 and the air electrode 13 which are discharge reaction areas.

In addition, by using at least one of powder, particles, or a member with an increased surface area compared to a simple shape for magnesium metal or magnesium alloy for foaming purposes, the surface area in contact with water can be improved. It is possible to earn well, and it becomes easy to secure a large number of edges that are easy to foam. In addition, hydrogen is generated by the self-discharge reaction of magnesium, and the electrolytic solution whose concentration is increased downward due to buoyancy can be moved to the upper region where the concentration tends to decrease, and can be moved to the upper discharge reaction region. it can.
Further, the foam member 121 may be provided integrally with the magnesium electrode 15. For example, as shown in FIG. 8, a lattice-like groove may be provided on the surface of the magnesium electrode 15 that does not face the air electrode 13 as the foam member 121. According to this configuration, the surface area of the magnesium electrode 15 that comes into contact with the poured water can be efficiently secured, and the foaming action is efficiently generated by utilizing the edge of the groove of the magnesium electrode 15 during the water injection. Can be made.

Subsequently, examples and comparative examples will be described.
Moreover, the rise of the voltage in a predetermined condition (discharge time 60 minutes, current setting 2A, discharge start within 3 minutes from the start of water injection) was tested, and the result is shown in FIG.
In Example A, a bag-like body 51 provided with a lattice-like groove on the surface opposite to the positive electrode (air electrode 13) of the negative electrode (magnesium electrode 15) and containing sodium chloride (electrolyte) is used as the upper surface of the electrolytic solution. This is the case where it is placed near the flooding height, and is labeled “Negative / Salt”.
Example B is a case where the bag body 51 containing sodium chloride is disposed at a height to be submerged near the upper surface of the electrolytic solution, and the powdery foam member 121 is disposed on the bottom portion 112. “Powder and salt on”.

Example C is a case where the bag body 51 containing sodium chloride and the powdered foam member 121 are arranged on the bottom 112, and are indicated as “under powder / under salt” in the drawing.
Example D is a case in which the bag body 51 containing sodium chloride is disposed at a height to be submerged near the upper surface of the electrolytic solution, and the powdery foam member 121 is disposed immediately below the bag body 51. Inside, it is written as “powder / salt”.
In Example E, a magnesium alloy plate separate from the negative electrode (magnesium electrode 15) is prepared as the foam member 121, the foam member 121 is disposed on the bottom 112, and the bag body 51 containing sodium chloride is obtained. The height of the electrolyte near the top surface of the electrolyte solution is the case where it is disposed above the foam member 121, and is indicated as “under board / on salt” in the figure.

In Example F, a magnesium alloy plate separate from the negative electrode (magnesium electrode 15) is prepared as the foam member 121, and the foam member 121 is disposed immediately below the bag body 51 containing sodium chloride. This is a case where the contained bag body 51 is arranged at a height to be submerged near the upper surface of the electrolytic solution, and is indicated as “on board / on salt” in the drawing.
In addition, the foamed member 121 of Examples E and F uses a magnesium alloy plate provided with lattice-like grooves, and the width of the magnesium alloy plate is substantially the same as that of the negative electrode (magnesium electrode 15), and the height is It was assumed to be much lower than the negative electrode, and was placed in the space SR.

  Comparative example α is a case where an aqueous sodium chloride solution (electrolyte) is injected (indicated as “saline solution” in the figure), and comparative example β is a bag 51 containing sodium chloride near the upper surface of the electrolyte. This is a case where water is poured in and placed at the height of water immersion (indicated as “salt on” in the figure). Further, Comparative Example γ is a case where the bag body 51 containing sodium chloride is placed on the bottom portion 112 and water is poured (indicated as “under salt” in the figure).

According to the studies by the inventors, the speed of rising is “under powder / salt of Example B”, “on board / salt of Example F”, “on powder / salt of Example D”. In this order, “under the plate and salt of Example E”, “negative and salt of Example A”, “saline solution of Comparative Example α”, and “on the salt of Comparative Example β”.
According to the test results, the discharge time until reaching 1 V was 9 minutes 54 seconds for “Example B under powder / on salt”, 16 minutes 24 seconds for “Example F on board / on salt”, “Example D” No. on powder / salt ”was 16 minutes 26 seconds,“ Under plate / salt on Example E ”was 17 minutes 27 seconds,“ Negative / Salt on Example A ”was 18 minutes 44 seconds,“ Comparative Example α No salt solution ”was 22 minutes and 11 seconds, and“ Salt on Comparative Example β ”was 25 minutes and 53 seconds.

In the test results shown in FIG. 9, the comparative example γ in which the sodium chloride-containing bag body 51 is disposed on the bottom 112, and the sodium chloride-containing bag body 51 and the powdered foam member 121 are In Example C disposed on the bottom 112, no practical voltage increase was observed, and 1 V was not reached after a discharge time of 60 minutes. Moreover, a part of sodium chloride remained on the bottom 112 without melting.
However, as shown in FIG. 9, in Example C in which the foamed member 121 was arranged, the voltage rises faster and the voltage value was higher than that in Comparative Example γ. That is, it is clear that the rising characteristics are improved by the foam member 121.

FIG. 10 shows the difference between the upper and lower concentrations (lower concentration−upper concentration), and FIG. 11 shows an enlarged view focusing only on a part of FIG. 10 (on the salt). As a result of examination by the inventors, when the bag body 51 containing sodium chloride is disposed on the bottom 112 (for example, Comparative Example γ), the difference in concentration between the upper and lower portions is increased, the liquid resistance is increased, and the voltage is decreased. The current was likely to be small.
As shown in FIG. 11, from the viewpoint of reducing the difference in concentration between the upper and lower sides, “under board / salt on Example E” is the most advantageous, followed by “on board / on salt in Example F”. The remaining Examples A to D were almost equivalent. Further, in FIG. 11, “on the salt of Comparative Example β” is the most disadvantageous, and it can be seen from this that it is advantageous to dispose the foam member 121.

  As described above, in the present embodiment, the casing 111 has the foamed member 121 that foams by contact with water, and the foamed member 121 is made of magnesium metal or magnesium alloy. In addition, the electrolytic solution can be stirred by the foam member 121, the concentration gradient of the electrolytic solution can be suppressed, and the previous electrolytic solution adjustment work can be eliminated. In addition, it is not necessary to newly use a different kind of substance in the casing 111, and it is possible to utilize the processing waste generated when the magnesium electrode 15 is manufactured, which is advantageous in reducing the material cost. Moreover, since the reaction product after foaming and the reaction product by discharge are the same, the effect that there is no generation | occurrence | production of the substance which affects discharge reaction is also acquired.

  When the foam member 121 is disposed and fixed below the electrolyte, the electrolytic solution can be stirred in the lower portion where the concentration tends to be higher, and the concentration difference can be effectively eliminated. Further, since the foam member 121 is at least one of a powder, a flat plate provided with a lattice-like groove, and a structure where a lattice-like groove is provided on the surface of the negative electrode on the side opposite to the positive electrode, the foaming member 121 has a simple structure. Can be generated.

  As shown in FIGS. 7 and 8, a magnesium electrode 15 and an air electrode 13 are arranged in the casing 111 without using a separator, and the magnesium electrode 15 and the inner wall (rear wall portion) of the casing 111 are arranged. 114), the bag body 51 and the foamed member 121 are provided, so that the magnesium metal or magnesium alloy for use in electrolyte and foaming immediately moves to the space SF between the magnesium electrode 15 and the air electrode 13 which are discharge reaction regions. This makes it easy to suppress density unevenness in the discharge reaction region. Thereby, it is possible to suppress the influence on the discharge reaction caused by the density unevenness.

  When the foam member 121 is disposed, as described above, the electrolytic solution can be actively stirred. Therefore, even if the electrolyte is not wrapped in the bag body 51 and disposed in the housing 111, It becomes possible to suppress the concentration gradient of the electrolytic solution when water is poured.

As mentioned above, although the form for implementing this invention was described, this invention is not limited to above-mentioned embodiment, Various deformation | transformation and a change are possible based on the technical idea of this invention.
For example, as a configuration of each part such as the air electrode 13, a known configuration can be widely applied.
Further, in each of the above-described embodiments, the case where the bag body 51 is provided directly below the water injection port 27A has been described. However, the bag body 51 may be slightly deviated from just below, or may be near the water injection port 27A. In addition, the position where the bag body 51 and the foam member 121 are disposed is changed within a range in which the electrolyte can be gradually dissolved by water from the water injection port 27A even if it is not directly below or near the water injection port 27A. May be.
Moreover, although each above-mentioned embodiment demonstrated the case where sodium chloride was used for electrolyte, it is not restricted to this, You may use the chloride of an alkali metal or an alkaline-earth metal ion.

10, 100 Magnesium air battery (magnesium primary battery)
11, 111 Housing 13 Air electrode (positive electrode)
15 Magnesium electrode (negative electrode)
27 Lid 27A Water injection port (Liquid injection port)
51 Bag body 121 Foam member

Claims (12)

  A negative electrode of magnesium or a magnesium alloy is provided, and an electrolyte contained in an electrolytic solution capable of eluting magnesium ions from the negative electrode is wrapped in a water-insoluble bag made of a nonwoven fabric or a woven fabric and placed in advance in a casing, A magnesium primary battery that operates as a battery by pouring water into a housing.   The magnesium primary battery according to claim 1, wherein a main component of the electrolyte is sodium chloride.   The magnesium primary battery according to claim 1 or 2, wherein a mass of the electrolyte is in a range of 4% to 18% with respect to a mass of water to be poured.   The magnesium primary battery according to any one of claims 1 to 3, wherein the bag is provided directly below a water inlet of the housing.   5. The magnesium primary battery according to claim 4, wherein the electrolyte is powdery or granular, and is disposed at a water immersion height near the upper surface of the electrolyte solution. In the housing, having a foam member that foams by touching the water,
The magnesium primary battery according to claim 1, wherein the foamed member is magnesium metal or a magnesium alloy.   The magnesium primary battery according to claim 6, wherein the foamed member is disposed and fixed below the electrolyte.   The foamed member is at least one of a powdery plate, a flat plate provided with a lattice-like groove, and a configuration in which a lattice-like groove is provided on the surface of the negative electrode opposite to the positive electrode. Item 8. The magnesium primary battery according to Item 6 or 7.   The said housing | casing arrange | positions the said negative electrode and a positive electrode without using a separator, and the said bag body is provided between the said negative electrode and the said positive electrode. Primary magnesium battery described in 1.   The said housing | casing arrange | positions the said negative electrode and a positive electrode without using a separator, The said bag body is provided between the said negative electrode and the inner side wall of the said housing | casing. The magnesium primary battery as described in any one. The housing includes a lid portion provided with the water inlet,
The magnesium primary battery according to any one of claims 1 to 9, wherein the bag is attached to the lid. It has a housing with a negative electrode made of magnesium or magnesium alloy,
In the housing, an electrolyte contained in an electrolyte solution capable of eluting magnesium ions from the negative electrode, and a foaming member that foams by touching water as a solvent of the electrolyte solution,
The said foaming member is magnesium metal or a magnesium alloy, It operate | moves as a battery by pouring water in the said housing | casing, The magnesium primary battery characterized by the above-mentioned.

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