Charging device and charging method

Abstract

In order to provide an easy-to-use charging device and charging method using sand, this charging device comprises: a separator which is provided between a positive electrode and a negative electrode; and a first conductive part in which an electrically conductive substance is mixed into sand containing ions. The electrically conductive substance and the positive electrode are connected, and the electrically conductive substance and the negative electrode are connected. When a voltage is applied between the positive electrode and the negative electrode, negative ions are guided to the positive electrode and positive ions are guided to the negative electrode.

Description

Charging apparatus and charging method

[0001] The present invention relates to a charging device and a charging method that can store electricity using sand.

[0002] In recent years, it has been proposed to incorporate electrically conductive nanoporous carbon into cement, form a network of nanoporous carbon using the fluidity of water, and use concrete as a capacitor (see, for example, Patent Document 1).

[0003] U.S. Publication No. 11512022

[0004] However, Patent Document 1 only proposed storing electricity in concrete to create a capacitor, and did not propose any other applications.

[0005] Therefore, the present invention aims to provide an easy-to-use charging device and charging method using sand.

[0006] The charging device according to claim 1 comprises a separator provided between a positive electrode and a negative electrode, and a first conduction section in which an electrically conductive material is mixed with ion-containing sand, wherein the electrically conductive material is connected to the positive electrode and the electrically conductive material is connected to the negative electrode, and when a voltage is applied between the positive electrode and the negative electrode, anions are guided to the positive electrode and cations are guided to the negative electrode. The charging method according to claim 15 comprises a first conduction section in which an electrically conductive material is mixed with ion-containing sand, a positive electrode, a negative electrode and a separator are provided in the first conduction section, the electrically conductive material is connected to the positive electrode and the electrically conductive material is connected to the negative electrode, and when a voltage is applied between the positive electrode and the negative electrode, anions are guided to the positive electrode and cations are guided to the negative electrode.

[0007] According to the charging device described in claim 1, electricity can be stored using sand mixed with an electrically conductive substance. According to the charging method described in claim 15, electricity can be stored using sand mixed with an electrically conductive substance.

[0008] This is a cross-sectional view showing a container filled with sand and with two copper plates inserted into the sand. This is a cross-sectional view showing a container filled with a mixture of sand and carbon black and with two copper plates inserted into the mixture. This is a schematic diagram showing the process of charging a capacitor using electrodes with an extendable portion. This is a schematic diagram showing an example of the capacitor in Figure 3 being provided with a lid member and a maintenance member. This is a schematic diagram showing an example of the capacitor in Figure 4 being provided with a water supply member. This is a block diagram of a control device for controlling the charging and discharging of the capacitor in this first embodiment. This is a flowchart of this first embodiment. This is a diagram showing a first example in which the amount of electron-conductive material added to the soil is greater in some parts than in others. This is a diagram showing a second example in which the amount of electron-conductive material added to the soil is greater in some parts than in others. This is a diagram showing a third example in which the amount of electron-conductive material added to the soil is greater in some parts than in others.

[0009] (First Embodiment) The first embodiment will be described in detail below with reference to Figures 1 to 7. This first embodiment involves forming conductive sand by mixing an electrically conductive material with sand, and using this conductive sand to provide the capacitor 11 described later. In this first embodiment, the electrically conductive material is a material that has both electron conductivity, which moves electrons, and ionic conductivity, which moves ions. In this first embodiment, a combination of carbon black and binchotan charcoal is used as the electron conductive material, and water-containing sand 2 is used as the ionic conductive material, but it is not limited to this. The vertical direction is shown as the Z direction, and the direction perpendicular to the Z direction in the left-right direction is shown as the X direction. Although not shown, the direction perpendicular to the plane of the paper is the Y direction.

[0010] (Preliminary experiment to confirm the insulating properties of soil) Figure 1 is a cross-sectional view showing a glass container 1 filled with sand 2 and two copper plates 3 inserted into the sand 2. The sand 2 was collected from the coast of Ito City, Shizuoka Prefecture. Note that a container 1 made of resin may be used instead of glass, and any material that has insulating properties may be used. Furthermore, even if the container 1 is made of a material that does not have insulating properties, it may be used in a state in which insulating properties have been given by coating or spraying, for example, an alkylalkoxysilane-based insulating agent or a silanesiloxane-based insulating agent.

[0011] When soil testing was performed on this sand 2, the density of the soil particles was found to be 2.915 g / cm³. ３ The natural water content was 2.1%. The particle size distribution of sand 2 was 1.6% gravel, 97.6% sand, and 0.8% clay.

[0012] A component analysis of this sand 2 revealed that it contained 44.28% silicon dioxide, 20.79% iron oxide, 13.5% aluminum oxide, 9.23% calcium oxide, 5.83% magnesium oxide, and 1.77% sodium oxide. Therefore, calcium ions (Ca), which are electrolytes with a high ionization tendency, were found to be present. ２＋ ) and magnesium ions (Mg ２＋ ) and sodium ions (Na ＋ It was found that ) can be used. Furthermore, if the electrolyte substance in sand 2 is insufficient, calcium ions (Ca ２＋ ), potassium ions (K ＋ ), magnesium ions (Mg ２＋ ), sodium ions (Na ＋ Cations with a high ionization tendency, such as ), can be added to the sand 2 as an electrolyte. When adding an electrolyte to the sand 2, it is preferable to add it as an electrolyte solution obtained by dissolving the electrolyte in water. In this first embodiment, the sand containing ions includes not only the ions originally contained in the sand but also the ions added later.

[0013] When the test leads of the tester were brought into contact with each of the two copper plates 3, no continuity was detected, indicating a non-conductive state. Therefore, conductivity was not confirmed in the sand 2 of this first embodiment.

[0014] (Mixing of sand and electrically conductive material) The aforementioned sand 2 was mixed with an electrically conductive material. As the electrically conductive material, a combination of carbon black and activated carbon was used, but it is not limited to this, and for example, a single carbon-derived material (for example, Binchotan charcoal or activated carbon) may be used as the electrically conductive material. Carbon black is a suitable material for forming a carbon network and, when mixed with sand 2, lowers the internal resistance of sand 2 and increases the electrostatic capacitance of sand 2. Activated carbon is a suitable material for adsorbing and releasing ions. In this first embodiment, acetylene black produced by the thermal decomposition of acetylene was used as the carbon black. However, registered trademark Ketjenblack, in which the primary particles have a hollow shell structure, may be used, or inexpensive activated carbon may be used. In this case, it is preferable to use activated carbon mainly composed of micropores or mesopores.

[0015] Activated carbon can be coarse, fine, or coconut shell activated carbon, but in this first embodiment, fine activated carbon or coconut shell activated carbon will be used from the viewpoint of ion storage and release properties.

[0016] Acetylene black and activated carbon are hydrophobic substances, but they become somewhat more compatible with water after being soaked in water for about a day. In this case, it is preferable to stir them for 10 to 30 minutes immediately after soaking them in water. In this first embodiment, acetylene black and activated carbon were each soaked in water before being mixed with sand 2. This improves the affinity between sand 2, acetylene black, and activated carbon.

[0017] In this case, by stirring acetylene black, binchotan charcoal, and water together, the acetylene black and binchotan charcoal, which form a carbon network, will mix well, and water molecules can be adsorbed into the pores of the binchotan charcoal, allowing for efficient ion storage and release. Alternatively, binchotan charcoal, acetylene black, and water can be stirred together instead of activated carbon, or in addition to activated carbon.

[0018] The amount of acetylene black added is between 5% and less than 20% by weight of sand 2. If the amount of acetylene black added is 5% or more by weight of sand 2, a carbon network can be formed in the sand 2. If the amount of acetylene black added is 20% or more by weight of sand 2, the resistance value of the mixture 4 described later will be further reduced, but considering the price and cost-effectiveness of acetylene black, it is set to less than 20% in this first embodiment.

[0019] The amount of activated carbon added is set to be between 8% and less than 25% by weight of the sand 2. If the amount of activated carbon added is 8% or more by weight of the sand 2, charging using ions from the sand 2 by the capacitor 11 described later becomes possible. The amount of activated carbon added may be 25% or more by weight of the sand 2, but considering the price of activated carbon and cost-effectiveness, it is set to less than 25% in this first embodiment. Also, when using binchotan charcoal instead of activated carbon, the amount of binchotan charcoal added should be between 8% and less than 25% by weight of the sand 2. When using both activated carbon and binchotan charcoal, the combined weight of both activated carbon and binchotan charcoal should be between 8% and less than 25% by weight of the sand 2.

[0020] The amount of activated carbon to be added will vary depending on the properties of sand 2, the amount of electrolytes contained in sand 2, and whether or not electrolytes are added, so the above amount should be used as a guideline. Furthermore, considering the performance of capacitor 11 (charge amount, charging time, etc.) described later, it is preferable that the amount of activated carbon added be greater than the amount of acetylene black added. The amount of acetylene black added may also be determined by considering the internal resistance (several ohms to tens of ohms) when mixed with sand 2. Even when using binchotan charcoal instead of activated carbon, it is preferable that the amount of binchotan charcoal added be greater than the amount of acetylene black added. Furthermore, when using both binchotan charcoal and activated carbon, it is preferable that the combined amount of binchotan charcoal and activated carbon added be greater than the amount of acetylene black added.

[0021] In this first method of application, sand 2, acetylene black, and activated carbon were mixed in a mixer for several minutes (1 to 2 minutes), and then water and electrolyte solution were added to create mixture 4. Depending on the amount of electrolyte solution, the addition of water may be omitted.

[0022] (Experiment to confirm the conductivity of the mixture) Figure 2 is a cross-sectional view showing a state in which the mixture 4 is placed in the container 1 and two copper plates 3 are inserted into the mixture 4.

[0023] When the test leads of the tester were brought into contact with each of the two copper plates 3, the resistance value was about 20 to 30 Ω, and the conductivity of the mixture 4 was confirmed. From this, it was confirmed that a network of electrical conduction by carbon black, which is a carbon-derived material, was formed in the sand 2.

[0024] The reason why the resistance value fluctuates by about 10 Ω is that gas (air) is mixed into the mixture 4 and the contact state of the electrical conduction substances becomes unstable. Therefore, degassing was performed by manually compacting the mixture 4 using a metal push rod, and the resistance value of the mixture 4 was measured again.

[0025] After manual compaction, the resistance value of the mixture 4 became about 18 to 20 Ω, and it was confirmed that the resistance value decreased and the fluctuation of the resistance value decreased. Incidentally, this resistance value can be reduced to about several Ω if the addition amount of carbon black is increased to 10 to 15%.

[0026] In this first embodiment, the mixture 4 is a conductive part in which an electrically conductive carbon network is formed, and a capacitor 11 as an electrostatic charging device that utilizes the ions of the sand 2 is realized using this conductive part. Note that the sand 2 is not limited to sea sand, and may be natural silica sand such as mountain sand or artificial silica sand as long as it contains silicon dioxide as a main component. Further, the sand 2 may be soil particles having a particle size in the range of 0.075 mm to 4.75 mm. Incidentally, the sand 2 may contain a small amount of gravel, silt, or clay.

[0027] (Experiment to confirm energy storage using a mixture) Figure 3 is a schematic diagram showing the charging of a capacitor 11 having the extension portion 6a and extension portion 7a described later, and is shown as a cross-sectional view except for the power supply 8. As shown in Figure 3, after attaching the separator 5 to the container 1, the mixture 4 is added, the positive electrode 6 and the negative electrode 7 are inserted into the mixture 4, and then the mixture 4 is compacted to form the capacitor 11 of this first embodiment. It is preferable to degas the mixture 4 after the positive electrode 6 and the negative electrode 7 have been inserted into the mixture 4. In this case, it is preferable to add the mixture 4 to the container 1 in several batches and degas it each time. In this specification, the positive electrode 6 and the negative electrode 7 are sometimes collectively referred to as electrodes.

[0028] The applicant has found that when the aforementioned mixture 4 is compacted, the adhesion between the mixture 4 and the electrode improves, which in turn lowers the contact resistance between the mixture 4 (especially carbon black) and the electrode, improving the amount of charge stored in the capacitor 11. When compaction is performed along the arrow in Figure 3, a force is applied to the mixture 4 in the vertical Z direction, but a force in the X direction does not easily act on the electrode. For this reason, in this first embodiment, the shape of the electrode was made into an L-shape that intersects the vertical direction so that the vertical force applied to the electrode during compaction is applied to the electrode. Specifically, as shown in Figure 3, the lower end of the positive electrode 6 is bent to form an extended portion 6a, and the lower end of the negative electrode 7 is bent to form an extended portion 7a. In this way, the extended portions 6a and 7a extend in the X direction, which is the direction that intersects the Z direction in which the separator 5 is located.

[0029] Here, the length of the extension portion 6a and extension portion 7a in the X direction can be set arbitrarily as long as they do not interfere with the separator 5. This improves the adhesion between the extension portion 6a and extension portion 7a and the mixture 4, thereby improving the amount of charge stored in the capacitor 11, and consequently increasing the charging energy of the capacitor 11. Here, charging energy is the product of power and charging time. It is preferable to provide extension portions on both the positive electrode 6 and the negative electrode 7, but the extension portion on either one may be omitted. In addition, in this first embodiment, electrodes without extension portions may be used.

[0030] The separator 5 allows the ions in the mixture 4 to pass through by means of the formed carbon network while preventing the positive electrode 6 and the negative electrode 7 from coming into direct contact and short-circuiting. In the present first embodiment, the separator 5 is arranged along the Z direction. Also, in the present first embodiment, as the material of the separator 5, polyolefin resins such as polyethylene and polypropylene, and polyester resins such as polyethylene terephthalate and polybutylene terephthalate can be used. Further, the separator 5 can use cellulose-derived non-woven fabric and paper (such as Japanese paper and kitchen paper).

[0031] Further, the separator 5 may be made of a composite material of cellulose-derived non-woven fabric or paper and polyethylene or glass fiber. The separator 5 is fixed to the container 1 by an insulating tape. Instead of this, it may be sandwiched between insulators and installed in the container 1. Also, as the separator 5, it is preferable to use a hydrophilic material in order to facilitate the passage of ions. The fixing of the separator 5 may be performed by forming a recess in the bottom of the container 1 and using this recess for fixing, or by using an insulating tape for fixing, or by other methods.

[0032] For the positive electrode 6, for example, materials that do not easily undergo a chemical reaction with the ionic substances contained in the sand 2 such as copper, aluminum, platinum, and carbon materials can be used. In the present first embodiment, a copper plate 3 is used. The positive electrode 6 is connected to a carbon network formed by acetylene black. When an electric double layer is formed near the surface of the binchotan charcoal connected to this carbon network, charging is performed at the positive electrode 6 by attracting anions having opposite charges.

[0033] The negative electrode 7 can be made of a material that does not easily react with ionic substances contained in the sand 2, such as copper, aluminum, platinum, or carbon material. In this first embodiment, a copper plate 3 was used. The negative electrode 7 is connected to a carbon network formed of acetylene black. An electric double layer is formed near the surface of the binchotan charcoal connected to this carbon network, causing the negative electrode 7 to be charged by attracting cations with the opposite charge.

[0034] Furthermore, sheet-like carbon fibers may be used as the carbon material for the positive electrode 6 and the negative electrode 7. Carbon fibers are lightweight and strong, making them easy to use electrodes. Also, sheet-like carbon fibers are easier to bend than metal electrodes, making it easier to form the stretched portions 6a and 7a. After adding a mixture 4 of several mm to several cm in size to cover the stretched portions 6a and 7a, degassing by compaction can be performed to improve the adhesion between the electrodes and the mixture 4 and to remove gas from the mixture 4. It is also desirable to perform degassing by compaction when adding more mixture 4 to the container 1 afterward.

[0035] To improve the adhesion between the electrode and the mixture 4, the electrode shape may be made zigzag. By making the electrode shape zigzag, the surface area of ​​the electrode increases, and the contact area between the mixture 4 and the electrode increases, so that more carbon networks come into contact with the electrode, and thus the amount of energy stored in the capacitor 11 can be improved.

[0036] Furthermore, the electrodes may be positioned at an angle to the Z direction. By positioning the electrodes so as to intersect with respect to the Z direction, the length of the electrodes in the mixture 4 can be increased, thereby increasing the contact area between the mixture 4 and the electrodes. For this reason, positioning the electrodes so as to intersect with the Z direction allows more carbon networks to come into contact with the electrodes, thereby improving the amount of energy stored in the capacitor 11.

[0037] The power supply 8 is used when charging the capacitor 11, and a constant voltage power supply, a constant current power supply, etc. can be used. The charging of the capacitor 11 may be either constant voltage charging or constant current charging, but in this first embodiment, charging is performed by constant current charging from the viewpoint of charging efficiency.

[0038] One end of the wiring 9 is connected to the positive electrode 6, and the other end is connected to the + output terminal of the power supply 8. One end of the wiring 10 is connected to the negative electrode 7, and the other end is connected to the - output terminal of the power supply 8.

[0039] (Charge and Discharge Experiment) In this first embodiment, charging was performed at a voltage of 1 V to 3 V using a constant voltage power supply as the power supply 8. When the water content of the mixture 4 is high, charging is performed at 1.2 V or less to prevent the generation of hydrogen. When the water content of the mixture 4 is low, that is, when there is no influence of hydrogen generation, charging is performed at 3 V.

[0040] Depending on the state of the mixture 4, after charging for several minutes or about 5 to 10 minutes, when the wiring 9 and the wiring 10 were connected to a rotation motor (not shown), the rotation motor (not shown) rotated. As a result, it was confirmed that a carbon network of acetylene black was formed in the sand 2 and that the storage and release of ions by the activated carbon, which is an ion adsorbing substance, were occurring. That is, it was confirmed that power storage was possible using the mixture 4.

[0041] Also, the mixture 4 was newly created at the aforementioned weight ratio, and sodium ions (Na ＋ ) were added as an electrolyte. Specifically, several hundred cc of 5% saline was added. Then, in the same manner as described above, charging was performed at a voltage of 1.2 V for the same time (several minutes or about 5 to 10 minutes). After that, when the wiring 9 and the wiring 10 were connected to the rotation motor, the rotation motor rotated longer than the mixture 4 to which no sodium ions (Na ＋ ) were added.

[0042] As electrolytes, calcium ions (Ca ２＋ ), potassium ions (K ＋ ), magnesium ions (Mg ２＋ ), sodium ions (Na＋ Cations with a high ionization tendency, such as sodium ions (Na), can be used. In this first embodiment, the aforementioned sodium ions (Na) can be used. ＋ ) or potassium ions (K ＋ ) shall be used.

[0043] Depending on the composition and amount of mixture 4, as well as the distance between electrodes, sodium ions (Na ＋ ) or potassium ions (K ＋ After adding (a certain component) and charging with a constant current for 30 minutes to several hours, a resistor of several ohms to more than ten ohms was connected, and the voltage and current values ​​at each time interval during discharge were measured to determine the capacitance, which ranged from 800F to 1400F.

[0044] Also, sodium ions (Na ＋ Compared to adding potassium ions (K ＋ Adding potassium ions (K) reduced the internal resistance of mixture 4. ＋ Depending on conditions such as the amount of sodium ions (Na) added, ＋ Compared to adding potassium ions (K ＋ Adding ) resulted in an increase in the capacitance when charging capacitor 11.

[0045] This is sodium ions (Na ＋ The radius of the potassium ion (K ＋ Since it is smaller than the radius of the sodium ion (Na ＋ This is because it is adsorbed by the silicon dioxide on the surface of sand 2.

[0046] In this way, the capacitor 11 can supply more power because its charge increases by adding positive ions. For this reason, the amount of binchotan charcoal or activated carbon added to absorb and release these ions may be determined according to the amount of ions in the mixture 4.

[0047] Furthermore, the applicant has found that the energy storage performance of the capacitor 11 deteriorates if the mixture 4 dries out. The drying of the mixture 4 is predominantly due to natural drying, with a portion due to the thermal energy generated during the charging of the capacitor 11. For this reason, it is preferable to place the mixture 4 in an environment where humidity is easily maintained, or to supply it with a liquid such as water if it dries out. This can prevent deterioration of the energy storage performance of the capacitor 11 or recover the energy storage performance of a capacitor 11 that has deteriorated.

[0048] The effect of degradation on the drying of mixture 4 is also due to potassium ions (K ＋ ) is better, sodium ions (Na ＋ It was found to be less than potassium ions (K ＋ The mobility of sodium ions (Na ＋ This is due to the fact that it is higher than the mobility of potassium ions (K). For this reason, the frequency and amount of liquid supplied to mixture 4 are ＋ ) is better for sodium ions (Na ＋ It can be less than ( ).

[0049] Figure 4 is a schematic diagram showing an example in which a cover member and maintenance member are provided to the capacitor 11 in Figure 3. In Figure 4, in order to avoid making the drawing complex, the power supply 8 is omitted from the illustration, and the wiring 9, wiring 10, and the piping 19, which will be described later, are partially omitted from the illustration.

[0050] The first lid member 17 is a lid that covers the container 1, and in this first embodiment, a circular resin is used. For example, if the container 1 is made of circular resin, a female thread can be formed on the inner surface of the container 1 and a male thread can be formed on the outer surface of the first lid member 17, and the container 1 can be covered by the first lid member 17 by screwing the male and female threads together. Alternatively, the shape of the first lid member 17 may be such that it covers the container 1 from above, and the container 1 and the first lid member 17 may be fastened together with fastening members such as bolts. When fastening members such as bolts are used, the shapes of the container 1 and the first lid member 17 can be any shape such as a rectangle. By providing the first lid member 17, the drying of the mixture 4 can be suppressed.

[0051] The first lid member 17 is provided with a communication hole member 18 that communicates with the outside. In this first embodiment, three communication hole members 18a, 18b, and 18c are formed so as to face the separator 5, the positive electrode 6, and the negative electrode 7, respectively, but the embodiment is not limited to this.

[0052] The communication hole member 18a is a hole for maintaining the separator 5, and in this first embodiment, a pipe 19 for supplying water (for example, distilled water such as pure water) to the separator 5 passes through it. In this first embodiment, water is supplied to the separator 5 because ions become less mobile when the separator 5 dries out.

[0053] The connecting hole member 18b is a hole for passing the first pipe member 20 through which the wiring 9 from the positive electrode 6 passes. The connecting hole member 18c is a hole for passing the second pipe member 21 through which the wiring 10 from the negative electrode 7 passes. PF (Plastic Flexible) pipes can be used as the first pipe member 20 and the second pipe member 21. The lengths of the first pipe member 20 and the second pipe member 21 can be set arbitrarily.

[0054] The second cover member 22 is a cover member provided in correspondence with the communication hole member 18. The second cover member 22a covers the communication hole member 18a and has an opening for the pipe 19 that supplies water (for example, distilled water such as pure water) to the separator 5 to pass through. If it is necessary to prevent rain from seeping in through this opening, the area around the opening can be wrapped with sealing tape or a clay material can be provided.

[0055] The second cover member 22b covers the communication hole member 18b and has an opening for the first pipe member 20 to pass through for the wiring 9 from the positive electrode 6. If it is necessary to prevent rain from seeping in through this opening, the area around the opening can be wrapped with sealing tape or a clay-like material can be provided.

[0056] The second cover member 22c covers the communication hole member 18c and has an opening for the second pipe member 21 to pass through for the wiring 10 from the negative electrode 7. If it is necessary to prevent rain from seeping in through this opening, the area around the opening can be wrapped with sealing tape or a clay material can be provided.

[0057] In this first embodiment, the communication hole member 18 is provided with a female thread, and the second lid member 22 is provided with a male thread that screws into this female thread, thereby engaging the second lid member 22 with the communication hole member 18. If it is necessary to replace at least one of the separator 5, the positive electrode 6, and the negative electrode 7, this can be done with the first lid member 17 removed. At this time, the mixture 4 may also be replaced, or an electrolyte substance may be supplied to the mixture 4.

[0058] It is preferable to supply the electrolyte in solution form, for example, by dissolving it in water. This prevents deterioration of the energy storage performance of the capacitor 11 and allows for the recovery of a capacitor 11 whose energy storage performance has deteriorated. If the first lid member 17 is engaged with the container 1, the electrolyte may be supplied to the mixture 4 using the communication hole members 18a, 18b, and 18c.

[0059] Figure 5 is a schematic diagram showing an example in which a water supply member 12 is provided on the capacitor 11 of Figure 4. In Figure 5, the water supply member 12 is provided on the upper surface of the mixture 4 of Figure 4. The water supply member 12 is also provided near the upper end of the separator 5 so that water can be supplied to the separator 5 as well. In this case, it is preferable to position the water supply member 12 so that it is in contact with the separator 5.

[0060] The water supply component 12 is a superabsorbent polymer with water retention and drainage properties, capable of absorbing and holding several hundred to a thousand times its own weight in water. This superabsorbent polymer gradually releases its moisture as the soil dries, so it can supply moisture to the mixture 4 when it dries out. In this way, by using a superabsorbent polymer with drying responsiveness, the drying of the mixture 4 can be prevented.

[0061] Furthermore, some superabsorbent polymers are temperature-responsive, pH-responsive, or ion-responsive, so you should select the appropriate polymer based on the required responsiveness.

[0062] Alternatively, potassium chloride (KCl) or sodium chloride (NaCl) may be dissolved in water to form an electrolyte solution, and this electrolyte solution may be absorbed by the water supply member 12. This allows the electrolyte solution to be supplied to the mixture 4 and the separator 5.

[0063] Since acetylene black is a hydrophobic substance, if the amount of acetylene black added is high, water and electrolyte solutions may not penetrate the mixture 4 easily. Therefore, it takes time for water and electrolyte solutions from the water supply member 12 provided on the upper surface of the mixture 4 to penetrate downwards (in the -Z direction) of the mixture 4.

[0064] Therefore, in Figure 5, holes 13 are formed in the mixture 4, and a water supply member 12 is also provided in these holes 13. This makes it possible to shorten the time it takes for water or electrolyte solution from the water supply member 12 to penetrate downwards (in the -Z direction) of the mixture 4.

[0065] The number of holes 13 can be set to one or more as desired. The direction in which the holes 13 are formed can also be diagonally downward. In this case, if the holes 13 are formed toward the separator 5 embedded in the mixture 4, water and electrolyte solution can be quickly supplied to the portion of the separator 5 embedded in the mixture 4. In this first embodiment, the holes 13 may be omitted.

[0066] Alternatively, the water supply member 12 may be mixed into the mixture 4. Note that the water supply member 12 may be provided in a capacitor 11 that does not have the first lid member 17 shown in Figure 3, or a hole 13 may be formed to provide the water supply member 12.

[0067] As described above, by supplying water or an electrolyte solution to the mixture 4 and separator 5 from the water supply member 12, it is possible to prevent the mixture 4 and separator 5 from drying out, and by supplying an electrolyte solution to the mixture 4 and separator 5, it is possible to prevent deterioration of the performance of the capacitor 11. It is preferable to periodically supply water or an electrolyte solution to the water supply member 12. Whether to supply water or an electrolyte solution should be determined based on the performance changes of the capacitor 11. For example, if the capacitance of the capacitor 11 tends to decrease with each charge, it is preferable to supply an electrolyte solution to the water supply member 12. The liquid to the water supply member 12 may be supplied using the piping 19.

[0068] Furthermore, the water supply component 12 is not limited to superabsorbent polymers; natural materials such as vermiculite, which possesses both water retention and drainage properties, or coco peat may also be used. In addition, the liquid contained in the water supply component 12 may be a liquid other than water.

[0069] A drying prevention material may be used instead of, or in combination with, the water supply member 12. Examples of drying prevention materials include polyethylene, polypropylene, and polylactic acid.

[0070] Furthermore, burying the capacitor 11 in the ground allows for the utilization of previously unused ground space. Also, if the ground is sandy, such as a beach, using excavated sand to create the mixture 4 can save on the cost of transporting sand.

[0071] Figure 6 is a block diagram of a control device 30 for controlling the charging and discharging of the capacitor 11 in this first embodiment. In this first embodiment, the capacitor 11 is charged using electricity generated by a photovoltaic power generation device 25, but it is not limited to this. Also, a perovskite solar cell may be used as the photovoltaic power generation device 25. In addition, since sand is used in the mixture 4 in this first embodiment, the capacitor 11 may be installed at a solar power plant near the coast, or the capacitor 11 may be charged using electricity generated at an offshore wind power plant.

[0072] The control device 30 includes a power generation side switching unit 31, a power generation power conditioner 32, a voltage conversion unit 33, a charge switch 34, a discharge power conditioner 35, a discharge side switching unit 36, a memory 37, a communication unit 38, and a control unit 39.

[0073] The power generation side switching unit 31 is connected to the photovoltaic power generation device 25 and the control unit 39, and is a switching unit that switches whether to feed the power generated by the photovoltaic power generation device 25 back into the power grid via the power generation power conditioner 32, or to charge the capacitor 11. The power generation side switching unit 31 may be configured to supply power generated by the photovoltaic power generation device 25 to both the power grid and the capacitor 11.

[0074] The power conditioner 32 for power generation has an inverter that converts the DC current output from the solar power generation device 25 into AC current. The power conditioner 32 for power generation also has a function to adjust the output voltage in order to feed power back into the power grid, and a function to disconnect from the power grid in the event of an abnormality such as an earthquake. The power conditioner 32 for power generation feeds power generated by the solar power generation device 25 back into the power grid, but it may also be used to supply power to each element that constitutes the control device 30.

[0075] The voltage conversion unit 33 converts the voltage of the DC current output from the solar power generation device 25 to a voltage suitable for charging the capacitor 11 (for example, from 1V to 1.2V) and outputs it to the charging switch 34.

[0076] The charging switch 34 is an on / off switch. When the switch is on, the solar power generation device 25 charges the capacitor 11, and when the switch is off, the solar power generation device 25 does not charge the capacitor 11. The charging switch 34 is turned off by the control unit 39 when it is necessary to prevent overcharging of the capacitor 11.

[0077] The discharge power conditioner 35 has an inverter that converts the DC current output from the capacitor 11 into AC current. The discharge power conditioner 35 also has a function to adjust the output voltage in order to reverse power flow to the power grid or supply power to the load equipment 40, and a function to disconnect from the power grid in the event of an abnormality such as an earthquake. The function to disconnect from the power grid in the event of an abnormality may be performed by the discharge side switching unit 36.

[0078] The discharge-side switching unit 36 ​​is connectable to both the power grid and the load equipment 40, and is a switching unit that switches between flowing the power generated by the capacitor 11 back into the power grid or supplying it to the load equipment 40. The discharge-side switching unit 36 ​​may also be configured to supply the power generated by the capacitor 11 to both the power grid and the load equipment 40.

[0079] Memory 37 is a non-volatile memory (e.g., flash memory) and stores programs for controlling the charging and discharging of the capacitor 11, and programs for controlling the solar power generation device 25. In addition, memory 37 stores the daily power generation amount of the solar power generation device 25, as well as the daily charge and discharge amounts of the capacitor 11. Memory 37 may also store the charge and discharge amounts on an hourly basis. Furthermore, memory 37 may store programs for supplying power to the load equipment 40 (e.g., a program for supplying water).

[0080] The communication unit 38 is a wireless communication unit that accesses a wide-area network such as the Internet. The communication unit 38 may also use wired communication. In this first embodiment, the communication unit 38 communicates with a host computer located remotely.

[0081] The communication unit 38 communicates, for example, the daily charge and discharge amounts of the capacitor 11 to the host computer. The host computer may also issue an instruction to perform maintenance on the capacitor 11 when it detects a decrease in the charge of the capacitor 11 or when it detects drying of the mixture 4 using a sensor (not shown).

[0082] In this case, the host computer may use parameters such as weather conditions (sunny or rainy), seasons (summer or winter), the time elapsed since the capacitor 11 was installed, and the time elapsed since the last maintenance to determine whether or not to perform maintenance. Maintenance includes at least one of supplying water to the separator 5 that constitutes the capacitor 11 and supplying water or an electrolyte substance to the mixture 4.

[0083] The control unit 39 is equipped with a CPU and controls the solar power generation device 25, as well as the charging and discharging of the capacitor 11. In this first embodiment, the control unit 39 monitors the voltage of the capacitor 11 using a voltmeter (not shown), and if the voltage falls below a lower threshold, it controls the discharge power conditioner 35 to prevent discharge. Alternatively, if the voltage rises above an upper threshold, the control unit 39 may turn off the charging switch 34 to prevent charging of the capacitor 11. As will be described in detail later, the control unit 39 also controls maintenance of the capacitor 11.

[0084] The load equipment 40 is equipment driven by the power stored in the capacitor 11, and in this first embodiment, it is equipment used for maintenance of the capacitor 11, or various lighting equipment. The capacitor 11 may also be configured to supply power to the load equipment 40 at night.

[0085] Equipment used for maintenance of the capacitor 11 includes a sensor (not shown) for detecting the drying of the mixture 4, and equipment (hereinafter referred to as a supply device) for supplying water to the separator 5 and supplying at least one of water and the electrolytic solution to the mixture 4. Multiple pipes 19 may be provided to serve as water supply pipes and electrolytic solution pipes. Spray nozzles may also be provided at the ends of the pipes 19.

[0086] The control of the capacitor 11 and the photovoltaic power generation device 25 by the control unit 39 of this first embodiment, configured as described above, will now be explained. Figure 7 is a flowchart executed by the control unit 39 of this first embodiment. This flowchart is executed when the photovoltaic power generation device 25 is capable of generating power and the capacitor 11 is not being charged.

[0087] (Flowchart) The control unit 39 determines whether it is possible to charge the capacitor 11 (step S1). If the control unit 39 determines that the capacitor 11 does not require maintenance and that the capacitor 11 is not in an overcharged state based on the voltage of the capacitor 11, it determines Yes in step S1 and proceeds to step S2. If the capacitor 11 is overcharged, the control unit 39 determines No in step S1 and repeats the determination in step S1 until the overcharge of the capacitor 11 is resolved.

[0088] Here, we will continue the explanation assuming that the control unit 39 determines that the capacitor 11 requires maintenance and proceeds to step S10.

[0089] In step S10, the control unit 39 performs maintenance on the capacitor 11, which is the implementation of the procedure (step S10). The control unit 39 controls the discharge power conditioner 35 and the discharge-side switching unit 36 ​​to discharge to the load equipment 40. The control unit 39 also uses a supply device, which is one of the load equipment 40, to supply water to the separator 5 and to the mixture 4 with water and the electrolyte solution. Then the control unit 39 returns to step S1. When returning to step S1, the control unit 39 controls the discharge power conditioner 35 and the discharge-side switching unit 36 ​​to stop the discharge to the load equipment 40.

[0090] The control unit 39 makes another determination as to whether it is possible to charge the capacitor 11 (step S1). Since maintenance of the capacitor 11 was performed in step S10, the control unit 39 decides to proceed to step S2.

[0091] The control unit 39 switches the power generation side switching unit 31 to charging the capacitor 11 and also switches the charging switch 34 to ON to start charging the capacitor 11 (step S2).

[0092] As mentioned above, the capacitor 11 can be charged using either constant voltage charging or constant current charging, but constant current charging is preferable considering charging efficiency. When using constant current charging, a current control circuit can be added to supply a constant current between the voltage conversion unit 33 and the capacitor 11. In both cases, charging is performed by applying voltage from the solar power generation device 25.

[0093] The control unit 39 determines whether charging of the capacitor 11 is complete (step S3). When charging of the capacitor 11 is complete, the voltage of the capacitor 11 becomes maximum, while the current flowing through the capacitor 11 becomes minimum (almost zero). Therefore, the control unit 39 can determine whether charging of the capacitor 11 is complete by detecting the voltage of the capacitor 11 or the current flowing through the capacitor 11.

[0094] The control unit 39 continues charging until the capacitor 11 is fully charged, and proceeds to step S4 once the capacitor 11 is fully charged. Here, we assume that the capacitor 11 is fully charged and proceed to step S4. When charging is complete, the control unit 39 switches the power generation side switching unit 31 to reverse power flow to the power grid and switches the charging switch 34 to the OFF position.

[0095] The control unit 39 determines whether power supply to the load device 40 is necessary (step S4). If power supply to the load device 40 is not necessary, the control unit 39 terminates this flowchart; if power supply to the load device 40 is necessary, it proceeds to step S5. Here, we will assume that power supply to the load device 40 is necessary and proceed to step S5.

[0096] The control unit 39 supplies power (discharges) to the load equipment 40 using the capacitor 11 (step S5). The control unit 39 controls the discharge power conditioner 35 and the discharge side switching unit 36 ​​to supply power (discharge) to the load equipment 40 using the capacitor 11.

[0097] The control unit 39 determines whether the power supply (discharge) to the load device 40 by the capacitor 11 can be continued (step S6). The control unit 39 can determine whether the power supply (discharge) to the load device 40 can be continued by monitoring the voltage and current during the discharge of the capacitor 11, or by monitoring the amount of energy consumed relative to the capacitance stored in the capacitor 11.

[0098] To avoid interruption of power supply (discharge) to the load device 40, the control unit 39 can set a threshold value (the voltage value, current value, or energy consumption amount mentioned above) for the termination of the discharge of the capacitor 11, and provide a switching circuit so that when this threshold value is not met, it can switch to supplying power (discharging) to the load device 40 with another capacitor 11.

[0099] Furthermore, if the capacitor 11 is unable to continue supplying power (discharging) to the load device 40, the control unit 39 returns to step S1 and determines whether to recharge the capacitor 11 that can no longer supply power (discharge). Here, it is assumed that power supply can be continued, and the process proceeds to step S7.

[0100] The control unit 39 determines whether it is necessary to supply power (discharge) to the load device 40 by the capacitor 11 (step S7). If it is necessary to supply power (discharge) to the load device 40, the control unit 39 proceeds to step S5 and continues to supply power. On the other hand, if it is not necessary to supply power (discharge) to the load device 40, the control unit 39 terminates this flowchart.

[0101] One possible use for the capacitor 11 is to supply power to coastal aquaculture farms. In this case, the capacitor 11 may be used as a backup power source for the coastal aquaculture farm, or as a power source for nighttime lighting or oxygen supply devices for aquariums.

[0102] As described above, according to this flowchart, the electricity generated by the solar power generation device 25 can be used to charge the capacitor 11 located near the solar power generation device 25 (for example, below the solar panels) and also supplied to the load equipment 40. Therefore, even when there is a request to control the output of the solar power generation device 25, the electricity generated by the solar power generation device 25 can be used effectively.

[0103] Furthermore, while U.S. Patent No. 1,151,2022, listed in the prior art section, discloses the storage of electricity in concrete, it does not disclose how to insulate the reinforcing bars when they are present in the concrete. In contrast, in the first and second embodiments of this invention, the container 1 is made insulating, so there is no problem even if there are metal structures around the container 1.

[0104] (Second Embodiment) The second embodiment will be described below with reference to Figures 8 to 10. Components identical to those in the first embodiment will be denoted by the same reference numerals, and their descriptions will be omitted or simplified.

[0105] The applicant of this application conducted repeated charging experiments of the capacitor 11 and discharge experiments with loads such as resistors connected. They found that by increasing the amount of the electronically conductive material added to the sand 2 in one area compared to other areas, the internal resistance of the capacitor 11 could be reduced, thereby improving the charging efficiency. Charging efficiency is defined as the ratio of the energy actually stored in the capacitor 11 to the energy supplied to it.

[0106] Figure 8 shows a first example in which the amount of electronically conductive material added to the sand 2 is greater in one part than in other parts. The mixture 4 shown in Figure 8 has a first mixed part 4a in which the amount of electronically conductive material added is the same as that of the mixture 4 in Figure 3, and a second mixed part 4b in which the amount of electronically conductive material added is greater than that of the first mixed part 4a. The first mixed part 4a becomes a first conduction part in which an electrically conductive carbon network is formed, and the second mixed part 4b becomes a second conduction part in which an electrically conductive carbon network is formed.

[0107] In the first mixing section 4a, for example, the amount of acetylene black added is 10% by weight of the soil, and the amount of binchotan charcoal or activated carbon added is 15% by weight of the soil. On the other hand, in the second mixing section 4b, for example, the amount of acetylene black added is 15% by weight of the soil, and the amount of binchotan charcoal or activated carbon added is 20% by weight of the soil.

[0108] In this second embodiment, since the extension portions 6a and 7a are provided so as to be in contact with the upper surface of the second mixing portion 4b, ion conductivity is improved and the charging energy can be increased. Also, since the amount of acetylene black, binchotan charcoal, and activated carbon used is less compared to making the entire mixture 4 into the second mixing portion 4b, the cost of manufacturing the mixture 4 can be reduced. In this second embodiment, in order to reduce the cost of manufacturing the mixture 4, the area occupied by the second mixing portion 4b is smaller than the area occupied by the first mixing portion 4a. In addition, the weight of the second mixing portion 4b is lighter than the weight of the first mixing portion 4a.

[0109] As described above, the area occupied by the second mixing section 4b is smaller than the area occupied by the first mixing section 4a, so the amount of acetylene black added may exceed 20% by weight of the soil, and the amount of binchotan charcoal or activated carbon added may exceed 25% by weight of the soil. In this case as well, from the viewpoint of cost, it is preferable that the amount of acetylene black added be about 30% by weight of the soil, and the amount of binchotan charcoal or activated carbon added be about 35% by weight of the soil.

[0110] Furthermore, the second mixing section 4b may be composed of acetylene black and at least one of binchotan charcoal and activated carbon, without the sand 2. In this case, by adding water to the acetylene black and stirring, the acetylene black will coagulate in the water and change from a powder to a lumpy (clumpy) state. The second mixing section 4b can be formed by adding at least one of binchotan charcoal and activated carbon to the lumpy (clumpy) acetylene black. It is preferable to degas the lumpy (clumpy) acetylene black even when sand 2 is not used. Also, since the density of acetylene black is much lower than that of sand 2, the weight of the second mixing section 4b can be made lighter when sand 2 is not used.

[0111] The second mixing section 4b contains potassium ions (K) whether or not sand is used. ＋ ) and sodium ions (Na ＋ It is preferable to add cations with a high ionization tendency, such as ), as an electrolyte substance. Also, potassium ions (K) are also added in the first mixing section 4a. ＋ ) and sodium ions (Na ＋ It is preferable to add cations with a high ionization tendency, such as ), as an electrolyte substance.

[0112] Figure 9 shows a second example in which the amount of electron-conductive material added to the sand 2 is greater in some parts than in others. The mixture 4 shown in Figure 9 has multiple first mixing sections 4a and multiple second mixing sections 4b. The number of first mixing sections 4a and second mixing sections 4b is not limited to two, but may be three or more. Also, the position of the second mixing section 4b in the container 1 is not limited to the bottom and middle of the container 1, but may be located at the top. Furthermore, in Figures 8 and 9, the first mixing section 4a and second mixing section 4b are arranged along the X direction, but this is not the only option. In addition, the second mixing section 4b may be configured without sand 2.

[0113] Figure 10 shows a third example in which the amount of electron-conductive material added to the sand 2 is greater in one part than in other parts. In Figure 10, the first mixing section 4a and the second mixing section 4b are provided along the Z direction. By providing two second mixing sections 4b so as to sandwich the separator 5, the movement of ions through the separator 5 becomes smoother, which improves charging efficiency and also increases the amount of stored energy.

[0114] Furthermore, by providing the second mixing section 4b so as to be in contact with the positive electrode 6 along the Z direction, the reduction reaction of the positive electrode 6 can be carried out efficiently. Similarly, by providing the second mixing section 4b so as to be in contact with the negative electrode 7 along the Z direction, the oxidation reaction of the negative electrode 7 can be carried out efficiently.

[0115] Furthermore, the two second mixing sections 4b that sandwich the separator 5, the second mixing section 4b that contacts the positive electrode 6, and the second mixing section 4b that contacts the negative electrode 7 are not necessarily required, and at least one may be omitted depending on the cost-effectiveness. Also, the second mixing section 4b may be configured without sand 2.

[0116] Even when multiple second mixing sections 4b are provided, the area occupied by the multiple second mixing sections 4b is smaller than the area occupied by the first mixing section 4a. Furthermore, the weight of the multiple second mixing sections 4b is lighter than the weight of the first mixing section 4a.

[0117] In this second embodiment, the water supply member 12 described in the first embodiment may be provided, or a hole 13 may be formed and the water supply member 12 may be provided in this hole 13, or the water supply member 12 may be mixed into the mixture 4. In this second embodiment, the lid member and maintenance member described in the first embodiment may also be provided. In this way, the first embodiment and the second embodiment can be combined as appropriate.

[0118] The embodiments described above are preferred examples of the present invention. However, the invention is not limited thereto, and various modifications are possible without departing from the spirit of the invention. For example, an electronically conductive polymer may be used as the electronically conductive material. A conductive polymer can be used as the conductive polymer. In this case, the conductive polymer may be dissolved in a solvent to liquefy it, or an additive may be added to the conductive polymer to liquefy it.

[0119] 2...Soil 3...Copper plate 4...Mixture 4a...First mixing section 4b...Second mixing section 5...Separator 6...Positive electrode 6a...Extended section 7...Negative electrode 7a...Extended section 11...Capacitor 12...Water supply member 13...Hole 25...Solar power generation device

Claims

1. A charging device comprising a separator provided between a positive electrode and a negative electrode, and a first conductive part in which an electrically conductive material is mixed with ion-containing sand, wherein the electrically conductive material is connected to the positive electrode and the electrically conductive material is connected to the negative electrode, and when a voltage is applied between the positive electrode and the negative electrode, anions are guided to the positive electrode and cations are guided to the negative electrode.

2. The charging device according to claim 1, wherein the electrically conductive material comprises a first carbon material in powder form and a second carbon material different from the first carbon material, and the weight ratio of the second carbon material to the sand is greater than the weight ratio of the first carbon material to the sand.

3. The charging device according to claim 2, wherein the first carbon material is carbon black and the second carbon material is activated carbon or binchotan charcoal.

4. The charging device according to claim 1, wherein at least one of the positive electrode and the negative electrode has an extendable portion that extends in a direction intersecting the direction in which the separator is arranged.

5. The charging device according to claim 1, further comprising a water supply member that supplies liquid to at least one of the first conduction unit and the separator.

6. The electrostatic device according to claim 5, wherein the water supply member is provided with an electrolyte solution obtained by dissolving an electrolyte in the liquid.

7. The charging device according to claim 6, wherein the electrolyte is potassium.

8. The charging device according to claim 1, further comprising a supply device for supplying liquid to at least one of the first conduction unit and the separator.

9. The charging device according to claim 8, further comprising a control device that controls the supply device according to the ions contained in the sand.

10. The charging device according to claim 1, further comprising a second conduction section in which the amount of the electrically conductive material mixed in differs from that of the first conduction section.

11. The charging device according to claim 10, wherein the second conductive part does not contain the sand.

12. The charging device according to claim 10 or claim 11, wherein the second conductive part is provided so as to be in contact with the positive electrode and the negative electrode.

13. The charging device according to claim 10 or claim 11, wherein a plurality of second conductive parts are provided so as to sandwich the first conductive part.

14. The charging device according to claim 10 or claim 11, wherein the second conductive part is provided so as to sandwich the separator.

15. A charging method comprising: mixing an electrically conductive material with ion-containing sand to form a first conductive part; providing a positive electrode, a negative electrode, and a separator in the first conductive part; connecting the electrically conductive material to the positive electrode; and connecting the electrically conductive material to the negative electrode; and, when a voltage is applied between the positive electrode and the negative electrode, guiding anions to the positive electrode and cations to the negative electrode.

16. The charging method according to claim 15, wherein liquid is supplied to at least one of the first conduction part and the separator.

17. The charging method according to claim 16, wherein the liquid is an electrolyte solution containing an electrolyte.

18. The charging method according to claim 15, wherein a second conduction section is provided in which the amount of the electrically conductive material mixed in is different from that of the first conduction section.

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