Chemical current sources with stable and high specific characteristics are one of the most important conditions for the development of communications.
At present, the need of electricity users for communication facilities is covered mainly through the use of expensive galvanic cells or batteries.
Batteries are relatively autonomous sources of power supply, since they need to be periodically charged from the network. Chargers used for this purpose are expensive and not always able to provide a favorable charge regime. So, the Sonnenschein battery, made using dryfit technology and having a mass of 0.7 kg and a capacity of 5 Ah, is charged for 10 hours, and when charging, it is necessary to observe the standard values of current, voltage and charge time. The charge is carried out first at a constant current, then at a constant voltage. For this, expensive program-controlled chargers are used.
Galvanic cells are completely autonomous, but they usually have low power and limited capacity. When the energy stored in them is exhausted, they are disposed of, polluting the environment. An alternative to dry sources are air-metal mechanically recharged sources, some of the energy characteristics of which are given in Table 1.
Table 1- Parameters of some electrochemical systems
|
Electro-chemical system |
Theoretical parameters |
Practically implemented parameters |
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Specific energy, Wh/kg |
Voltage, V |
Specific energy, Wh/kg |
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Air aluminum |
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Air-magnesium |
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Air-zinc |
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Nickel metal hydride |
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Nickel-cadmium |
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Manganese-zinc |
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Manganese-lithium |
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As can be seen from the table, air-metal sources, in comparison with other widely used systems, have the highest theoretical and practical energy parameters.
Air-metal systems were implemented much later, and their development is still less intensive than current sources of other electrochemical systems. However, tests of prototypes created by domestic and foreign firms have shown their sufficient competitiveness.
It is shown that aluminum and zinc alloys can work in alkaline and saline electrolytes. Magnesium - only in salt electrolytes, and its intensive dissolution occurs both during current generation and in pauses.
Unlike magnesium, aluminum dissolves in salt electrolytes only when a current is generated. Alkaline electrolytes are the most promising for zinc electrode.
Air-Aluminum Current Sources (HAIT)
On the basis of aluminum alloys, mechanically rechargeable current sources with an electrolyte based on common salt have been created. These sources are absolutely autonomous and can be used to power not only communication equipment, but also to charge batteries, power various household equipment: radios, televisions, coffee grinders, electric drills, lamps, electric hair dryers, soldering irons, low-power refrigerators, centrifugal pumps, etc. Absolute autonomy of the source allows you to use it in the field, in regions that do not have a centralized power supply, in places of catastrophes and natural disasters.
The HAIT is charged within a matter of minutes, which is necessary for filling the electrolyte and / or replacing the aluminum electrodes. To charge, you need only table salt, water and a supply of aluminum anodes. Air oxygen is used as one of the active materials, which is reduced on carbon and fluoroplastic cathodes. Cathodes are quite cheap, provide the source for a long time and, therefore, have little effect on the cost of the generated energy.
The cost of electricity received in HAIT is determined mainly only by the cost of periodically replaced anodes, it does not include the cost of the oxidizer, materials and technological processes that ensure the performance of traditional galvanic cells and, therefore, it is 20 times lower than the cost of energy received from such autonomous sources as alkaline manganese-zinc elements.
table 2- Parameters of air-aluminum current sources
|
Battery Type |
Battery brand |
Number of elements |
Mass of electrolyte, kg |
Electrolyte storage capacity, Ah |
Weight of anode set, kg |
Anode storage capacity, Ah |
Battery weight, kg |
|
|
Submersible |
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Filled |
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The duration of continuous operation is determined by the amount of current consumed, the volume of electrolyte poured into the cell and is 70 - 100 Ah / l. The lower limit is determined by the viscosity of the electrolyte, at which its free discharge is possible. The upper limit corresponds to a decrease in the characteristics of the cell by 10-15%, however, upon reaching it, to remove the electrolyte mass, it is necessary to use mechanical devices that can damage the oxygen (air) electrode.
The viscosity of the electrolyte increases as it is saturated with a suspension of aluminum hydroxide. (Aluminum hydroxide occurs naturally in the form of clay or alumina, is an excellent product for aluminum production and can be returned to production).
Electrolyte replacement is carried out in a matter of minutes. With new portions of the electrolyte, HAIT can operate until the anode resource is exhausted, which, with a thickness of 3 mm, is 2.5 Ah/cm 2 of the geometric surface. If the anodes are dissolved, they are replaced with new ones within a few minutes.
The self-discharge of HAIT is very low, even when stored with electrolyte. But due to the fact that HAIT can be stored without electrolyte in the interval between discharges, its self-discharge is negligible. The service life of HAIT is limited by the service life of the plastic from which it is made. HAIT without electrolyte can be stored for up to 15 years.
Depending on the requirements of the consumer, HAIT can be modified, taking into account the fact that 1 element has a voltage of 1 V at a current density of 20 mA/cm 2, and the current taken from the HAIT is determined by the area of the electrodes.
The studies of the processes occurring at the electrodes and in the electrolyte, carried out at MPEI(TU), made it possible to create two types of air-aluminum current sources - flooded and immersed (Table 2).
Filled HAIT
Filled HAIT consist of 4-6 elements. The element of the filled HAIT (Fig. 1) is a rectangular container (1), in the opposite walls of which a cathode (2) is installed. The cathode consists of two parts electrically connected into one electrode by a bus (3). An anode (4) is located between the cathodes, the position of which is fixed by guides (5). The design of the element, patented by the authors /1/, allows to reduce the negative impact of aluminum hydroxide formed as the final product, due to the organization of internal circulation. For this purpose, the element in a plane perpendicular to the plane of the electrodes is divided by partitions into three sections. The partitions also act as guide rails for the anode (5). Electrodes are located in the middle section. The gas bubbles released during the operation of the anode raise the hydroxide suspension together with the electrolyte flow, which sinks to the bottom in the other two sections of the cell.
Picture 1- Element scheme
Air is supplied to the cathodes in HAIT (Fig. 2) through the gaps (1) between the elements (2). The end cathodes are protected from external mechanical influences by side panels (3). The tightness of the structure is ensured by the use of a quickly removable cover (4) with a sealing gasket (5) made of porous rubber. The tension of the rubber gasket is achieved by pressing the cover against the HAIT body and fixing it in this state with the help of spring clamps (not shown in the figure). The gas is released through specially designed porous hydrophobic valves (6). The elements (1) in the battery are connected in series. Plate anodes (9), the design of which was developed at MPEI, have flexible current collectors with a connector element at the end. The connector, the mating part of which is connected to the cathode unit, allows you to quickly disconnect and attach the anode when replacing it. When all anodes are connected, the HAIT elements are connected in series. The extreme electrodes are connected to the HAIT borns (10) also by means of connectors.
1 - air gap, 2 - element, 3 - protective panel, 4 - cover, 5 - cathode bus, 6 - gasket, 7 - valve, 8 - cathode, 9 - anode, 10 - boron
Figure 2- Filled HAIT
Submersible HAIT
Submersible HAIT (Fig. 3) is a poured HAIT turned inside out. The cathodes (2) are deployed by the active layer outwards. The capacity of the cell, into which the electrolyte was poured, is divided into two by a partition and serves for separate air supply to each cathode. An anode (1) is installed in the gap through which air was supplied to the cathodes. HAIT is activated not by pouring the electrolyte, but by immersion in the electrolyte. The electrolyte is preliminarily filled in and stored between discharges in the tank (6), which is divided into 6 unconnected sections. A 6ST-60TM battery monoblock is used as a tank.
1 - anode, 4 - cathode chamber, 2 - cathode, 5 - top panel, 3 - skid, 6 - electrolyte tank
Figure 3- Submersible air-aluminum element in the module panel
This design allows you to quickly disassemble the battery, removing the module with electrodes, and manipulate during the filling and unloading of the electrolyte not with the battery, but with a container, the mass of which with electrolyte is 4.7 kg. The module combines 6 electrochemical elements. The elements are attached to the top panel (5) of the module. The mass of the module with a set of anodes is 2 kg. HAIT of 12, 18 and 24 elements was recruited by serial connection of modules. The disadvantages of an air-aluminum source include a rather high internal resistance, low power density, voltage instability during discharge, and a voltage drop when turned on. All these shortcomings are leveled when using a combined current source (CPS), consisting of HAIT and a battery.
Combined current sources
The discharge curve of the “flooded” source 6VAIT50 (Fig. 4) when charging a sealed lead battery 2SG10 with a capacity of 10 Ah is characterized, as in the case of powering other loads, by a voltage dip in the first seconds when the load is connected. Within 10-15 minutes, the voltage rises to the working voltage, which remains constant throughout the entire HAIT discharge. The dip depth is determined by the state of the aluminum anode surface and its polarization.
Figure 4- Discharge curve 6VAIT50 when charging 2SG10
As you know, the process of charging the battery takes place only when the voltage at the source that gives energy is higher than at the battery. The failure of the initial HAIT voltage leads to the fact that the battery begins to discharge at HAIT and, consequently, reverse processes begin to occur on the HAIT electrodes, which can lead to passivation of the anodes.
To prevent unwanted processes, a diode is installed in the circuit between the HAIT and the battery. In this case, the HAIT discharge voltage during battery charging is determined not only by the battery voltage, but also by the voltage drop across the diode:
U VAIT \u003d U ACC + ΔU DIOD (1)
The introduction of a diode into the circuit leads to an increase in voltage both at HAIT and at the battery. The influence of the presence of a diode in the circuit is illustrated in fig. 5, which shows the change in the voltage difference between the HAIT and the battery when the battery is charged alternately with and without a diode in the circuit.
In the process of charging the battery in the absence of a diode, the voltage difference tends to decrease, i.e. reducing the efficiency of HAIT, while in the presence of a diode, the difference, and, consequently, the efficiency of the process tends to increase.
Figure 5- Voltage difference 6VAIT125 and 2SG10 when charging with and without a diode
Figure 6- Change in the discharge currents of 6VAIT125 and 3NKGK11 when the consumer is powered
Figure 7- Change in the specific energy of KIT (VAIT - lead battery) with an increase in the share of peak load
Communication facilities are characterized by energy consumption in the mode of variable, including peak, loads. We modeled such a consumption pattern when powering a consumer with a base load of 0.75 A and a peak load of 1.8 A from a KIT consisting of 6VAIT125 and 3NKGK11. The nature of the change in the currents generated (consumed) by the components of the KIT is shown in fig. 6.
It can be seen from the figure that in the base mode, HAIT provides sufficient current generation to power the base load and charge the battery. In case of peak load, the consumption is provided by the current generated by the HAIT and the battery.
Our theoretical analysis showed that the specific energy of the KIT is a compromise between the specific energy of HAIT and the battery and increases with a decrease in the share of peak energy (Fig. 7). The specific power of KIT is higher than the specific power of HAIT and increases with an increase in the proportion of peak load.
conclusions
New power sources based on the "air-aluminum" electrochemical system with a common salt solution as an electrolyte, with an energy capacity of about 250 Ah and a specific energy of over 300 Wh/kg have been created.
The charge of the developed sources is carried out within several minutes by mechanical replacement of the electrolyte and/or anodes. The self-discharge of the sources is negligible and therefore, before activation, they can be stored for 15 years. Variants of sources have been developed that differ in the way of activation.
The operation of air-aluminum sources during battery charging and as part of a combined source has been studied. It is shown that the specific energy and specific power of the KIT are compromise values and depend on the share of the peak load.
HAIT and KIT based on them are absolutely autonomous and can be used to power not only communication equipment, but also power various household equipment: electric machines, lamps, low-power refrigerators, etc. The absolute autonomy of the source allows it to be used in the field, in regions that do not have a centralized power supply, in places of catastrophes and natural disasters.
BIBLIOGRAPHY
- Patent of the Russian Federation No. 2118014. Metal-air element. / Dyachkov E.V., Kleimenov B.V., Korovin N.V., / / IPC 6 N 01 M 12/06. 2/38. prog. 06/17/97 publ. 08/20/98
- Korovin N.V., Kleimenov B.V., Voligova I.A. & Voligov I.A.// Abstr. Second Symp. on New Mater. for Fuel Cell and Modern Battery Systems. July 6-10. 1997 Montreal. Canada. v 97-7.
- Korovin N.V., Kleimenov B.V. Vestnik MPEI (in press).
The work was carried out within the framework of the program "Scientific research of higher education in priority areas of science and technology"
Candidate of Technical Sciences E. KULAKOV, Candidate of Technical Sciences S. SEVRUK, Candidate of Chemical Sciences A. FARMAKOVSKAYA.
The power plant on air-aluminum elements occupies only a part of the trunk of the car and provides a range of up to 220 kilometers.
The principle of operation of the air-aluminum element.
The operation of the power plant on air-aluminum elements is controlled by a microprecessor.
A small air-aluminum salt electrolyte cell can replace four batteries.
Science and life // Illustrations
Power plant EU 92VA-240 on air-aluminum elements.
Humanity, apparently, is not going to give up cars. Not only that: the Earth's car fleet may soon roughly double - mainly due to the mass motorization of China.
Meanwhile, cars rushing along the roads emit thousands of tons of carbon monoxide into the atmosphere - the same one, the presence of which in the air in an amount greater than a tenth of a percent is fatal to humans. And in addition to carbon monoxide - and many tons of nitrogen oxides and other poisons, allergens and carcinogens - products of incomplete combustion of gasoline.
The world has long been looking for alternatives to the car with an internal combustion engine. And the most real of them is considered an electric car (see "Science and Life" Nos. 8, 9, 1978). The world's first electric vehicles were created in France and England at the very beginning of the 80s of the last century, that is, several years earlier than cars with internal combustion engines (ICE). And the first self-propelled carriage that appeared, for example, in 1899 in Russia was precisely electric.
The traction motor in these electric vehicles was powered by prohibitively heavy lead-acid batteries with an energy capacity of only about 20 watt-hours (17.2 kilocalories) per kilogram. This means that in order to "feed" the engine with a capacity of 20 kilowatts (27 horsepower) for at least an hour, a lead battery weighing 1 ton was required. The amount of gasoline equivalent to it in terms of stored energy is occupied by a gas tank with a capacity of only 15 liters. That is why only with the invention of the internal combustion engine, car production began to grow rapidly, and electric cars were considered a dead end branch of the automotive industry for decades. And only the environmental problems that arose before mankind forced the designers to return to the idea of an electric car.
In itself, the replacement of an internal combustion engine with an electric motor is, of course, tempting: with the same power, the electric motor is lighter in weight and easier to control. But even now, more than 100 years after the first appearance of car batteries, the energy intensity (that is, stored energy) of even the best of them does not exceed 50 watt-hours (43 kilocalories) per kilogram. And therefore, hundreds of kilograms of batteries remain the weight equivalent of a gas tank.
If we take into account the need for many hours of charging batteries, a limited number of charge-discharge cycles and, as a result, a relatively short service life, as well as problems with the disposal of used batteries, then we have to admit that a battery electric car is not yet suitable for the role of mass transport.
However, the moment has come to say that the electric motor can also receive energy from another kind of chemical current sources - galvanic cells. The most famous of them (the so-called batteries) work in portable receivers and voice recorders, in watches and flashlights. The operation of such a battery, like any other chemical current source, is based on one or another redox reaction. And it, as is known from the school chemistry course, is accompanied by the transfer of electrons from atoms of one substance (reducing agent) to atoms of another (oxidizing agent). Such transfer of electrons can be done through an external circuit, for example, through a light bulb, a microcircuit or a motor, and thereby make the electrons work.
To this end, the redox reaction is carried out, as it were, in two stages - it is divided, so to speak, into two half-reactions occurring simultaneously, but in different places. At the anode, the reducing agent gives up its electrons, that is, it is oxidized, and at the cathode, the oxidizer accepts these electrons, that is, it is reduced. The electrons themselves, flowing from the cathode to the anode through an external circuit, do useful work. This process, of course, is not infinite, since both the oxidizing agent and the reducing agent are gradually consumed, forming new substances. And as a result, the current source has to be thrown away. True, it is possible to continuously or from time to time remove the reaction products formed in it from the source, and in return feed more and more new reagents into it. In this case, they play the role of fuel, and that is why such elements are called fuel (see "Science and Life" No. 9, 1990).
The efficiency of such a current source is determined primarily by how well the reagents themselves and their mode of operation are chosen for it. There are no particular problems with the choice of an oxidizing agent, since the air around us consists of more than 20% of an excellent oxidizing agent - oxygen. As for the reducing agent (that is, fuel), the situation with it is somewhat more complicated: you have to carry it with you. And therefore, when choosing it, one must first of all proceed from the so-called mass-energy indicator - the useful energy released during the oxidation of a unit of mass.
Hydrogen has the best properties in this respect, followed by some alkali and alkaline earth metals, and then aluminum. But gaseous hydrogen is flammable and explosive, and under high pressure it can seep through metals. It can be liquefied only at very low temperatures, and it is quite difficult to store it. Alkali and alkaline earth metals are also flammable and, in addition, quickly oxidize in air and dissolve in water.
Aluminum has none of these drawbacks. Always covered with a dense film of oxide, for all its chemical activity, it almost does not oxidize in air. Aluminum is relatively cheap and non-toxic, and its storage does not create any problems. The task of introducing it into the current source is also quite soluble: anode plates are made from fuel-metal, which are periodically replaced as they dissolve.
And finally, the electrolyte. In this element, it can be any aqueous solution: acidic, alkaline or saline, since aluminum reacts with both acids and alkalis, and when the oxide film is broken, it dissolves in water. But it is preferable to use an alkaline electrolyte: it is easier to carry out the second half-reaction - oxygen reduction. In an acidic environment, it is also reduced, but only in the presence of an expensive platinum catalyst. In an alkaline environment, one can get by with a much cheaper catalyst - cobalt or nickel oxide or activated carbon, which are introduced directly into the porous cathode. As for the salt electrolyte, it has a lower electrical conductivity, and the current source made on its basis is about 1.5 times less energy intensive. Therefore, it is advisable to use an alkaline electrolyte in powerful automotive batteries.
However, it also has disadvantages, the main of which is anode corrosion. It goes in parallel with the main - current-generating - reaction and dissolves aluminum, converting it into sodium aluminate with simultaneous release of hydrogen. True, this side reaction proceeds with a more or less tangible speed only in the absence of an external load, which is why air-aluminum current sources cannot, unlike batteries and batteries, be kept charged for a long time in standby mode. The alkali solution in this case has to be drained from them. But on the other hand, with a normal load current, the side reaction is almost imperceptible and the efficiency of aluminum reaches 98%. The alkaline electrolyte itself does not become a waste: after filtering aluminum hydroxide crystals from it, this electrolyte can be poured into the cell again.
There is another drawback in the use of an alkaline electrolyte in an air-aluminum current source: quite a lot of water is consumed during its operation. This increases the concentration of alkali in the electrolyte and could gradually change the electrical characteristics of the cell. However, there is a range of concentrations in which these characteristics practically do not change, and if you work in it, then it is enough to add water to the electrolyte from time to time. Waste in the usual sense of the word is not formed during the operation of an air-aluminum current source. After all, the aluminum hydroxide obtained by the decomposition of sodium aluminate is just white clay, that is, the product is not only absolutely environmentally friendly, but also very valuable as a raw material for many industries.
It is from it, for example, that aluminum is usually produced, first by heating to obtain alumina, and then subjecting the melt of this alumina to electrolysis. Therefore, it is possible to organize a closed resource-saving cycle for the operation of air-aluminum current sources.
But aluminum hydroxide also has independent commercial value: it is necessary in the production of plastics and cables, varnishes, paints, glasses, coagulants for water purification, paper, synthetic carpets and linoleums. It is used in the radio engineering and pharmaceutical industries, in the production of all kinds of adsorbents and catalysts, in the manufacture of cosmetics and even jewelry. Indeed, many artificial gems - rubies, sapphires, alexandrites - are made on the basis of aluminum oxide (corundum) with minor impurities of chromium, titanium or beryllium, respectively.
The cost of "waste" air-aluminum current source is quite commensurate with the cost of the original aluminum, and their mass is three times greater than the mass of the original aluminum.
Why, despite all the listed advantages of oxygen-aluminum current sources, they were not seriously developed for so long - until the very end of the 70s? Just because they were not in demand by technology. And only with the rapid development of such energy-intensive autonomous consumers as aviation and astronautics, military equipment and ground transport, the situation changed.
The development of optimal anode-electrolyte compositions with high energy characteristics at low corrosion rates began, inexpensive air cathodes with maximum electrochemical activity and a long service life were selected, optimal modes were calculated both for long-term operation and for short operation time.
Schemes of power plants were also developed, containing, in addition to the actual current sources, a number of auxiliary systems - supplying air, water, electrolyte circulation and purification, thermal control, etc. Each of them is quite complex in itself, and for the normal functioning of the power plant as a whole a microprocessor control system was required, which sets the operation and interaction algorithms for all other systems. An example of the construction of one of the modern air-aluminum installations is shown in the figure (p. 63): thick lines indicate fluid flows (pipelines), and thin lines indicate information links (signals of sensors and control commands.
In recent years, the Moscow State Aviation Institute (Technical University) - MAI, together with the research and production complex of power sources "Alternative Energy" - NPK IT "Alten" has created a whole range of functional power plants based on air-aluminum elements. Including - experimental installation 92VA-240 for an electric vehicle. Its energy intensity and, as a result, the mileage of an electric car without recharging turned out to be several times higher than when using batteries - both traditional (nickel-cadmium) and newly developed (sodium-sulphur). Some specific characteristics of an electric vehicle on this power plant are shown on the adjacent color tab in comparison with the characteristics of a car and an electric vehicle on batteries. This comparison, however, needs some explanation. The fact is that for the car only the mass of fuel (gasoline) is taken into account, and for both electric vehicles - the mass of current sources as a whole. In this regard, it should be noted that the electric motor has a significantly lower weight than a gasoline one, does not require a transmission, and consumes energy several times more economically. If we take all this into account, it turns out that the real gain of the current car will be 2-3 times less, but still quite large.
The 92VA-240 installation also has other - purely operational - advantages. Recharging air-aluminum batteries does not require an electrical network at all, but boils down to the mechanical replacement of spent aluminum anodes with new ones, which takes no more than 15 minutes. Even easier and faster is the replacement of the electrolyte to remove aluminum hydroxide deposits from it. At the "filling" station, the spent electrolyte is subjected to regeneration and used to refill electric vehicles, and the aluminum hydroxide separated from it is sent for processing.
In addition to an electric mobile power plant based on air-aluminum cells, the same specialists created a number of small power plants (see "Science and Life" No. 3, 1997). Each of these installations can be mechanically recharged at least 100 times, and this number is determined mainly by the service life of the porous air cathode. And the shelf life of these installations in an unfilled state is not limited at all, since there are no capacity losses during storage - there is no self-discharge.
In small power air-aluminum current sources, not only alkali, but also ordinary table salt can be used to prepare the electrolyte: the processes in both electrolytes proceed similarly. True, the energy intensity of salt sources is 1.5 times less than alkaline ones, but they cause much less trouble to the user. The electrolyte in them turns out to be completely safe, and even a child can be trusted to work with it.
Air-aluminum current sources for powering low-power household appliances are already mass-produced, and their price is quite affordable. As for the 92VA-240 automotive power plant, it still exists only in pilot batches. One of its experimental samples with a nominal power of 6 kW (at a voltage of 110 V) and a capacity of 240 ampere-hours costs about 120 thousand rubles in 1998 prices. According to preliminary calculations, after the launch of mass production, this cost will drop to at least 90 thousand rubles, which will make it possible to produce an electric car at a price not much higher than a car with an internal combustion engine. As for the cost of operating an electric car, it is now quite comparable to the cost of operating a car.
The only thing left to do is to make a deeper assessment and extended tests, and then, with positive results, begin trial operation.
The owners of the patent RU 2561566:
The invention relates to energy sources, in particular to air-aluminum current sources.
Known chemical current source (Pat. RU 2127932), in which the replacement of the aluminum electrode is also carried out by opening the battery case, followed by installation of a new electrode.
A disadvantage of the known methods for inserting an electrode into a battery is that the battery must be removed from the power supply circuit for the period of electrode replacement.
A fuel battery is known (application RU 2011127181), in which consumable electrodes in the form of tapes are pulled through the battery case through pressure seals and pressure seals as they are produced using lingering drums, which ensures the input of consumable electrodes into the battery without interrupting the power supply circuit.
The disadvantage of the known method is that the pressure seals and pressure seals do not remove the hydrogen released during operation from the battery.
The technical result of the invention is the provision of automatic insertion of an electrode with an increased working area of the consumable electrode in the fuel cell without interrupting the power supply circuit, an increase in the energy performance of the fuel cell.
The specified technical result is achieved by the fact that the method of introducing a consumable electrode into an air-aluminum fuel cell includes moving the consumable electrode as it is developed inside the fuel cell housing. According to the invention, a consumable electrode is used in the form of an aluminum wire, which is wound on a helical groove of a thin-walled rod made of a dielectric hydrophobic material and one end of which is inserted into the cavity of the thin-walled
the rod through the hole in its lower part, and the consumable electrode is moved by screwing the thin-walled rod into the covers of the fuel cell housing located on both sides of the housing and made of a hydrophobic material, ensuring that the electrolyte is stored inside the fuel cell and the evolving hydrogen is removed from its housing along the screw surfaces of hydrophobic covers.
The movement of the consumable electrode, wound on a thin-walled rod with a helical groove, occurs as a result of screwing it into covers that are made of hydrophobic material (fluoroplastic, ps, polyethylene), while the electrolyte remains inside the fuel cell, and the hydrogen released during operation is removed along the helical surface of the fuel cell body.
The cylindrical generatrix for the consumable electrode is made in the form of a thin-walled rod with a helical groove, on which an electrode of aluminum wire is wound. The rod is made of dielectric hydrophobic material, which allows not to interact with the electrolyte. The rod with an electrode made of aluminum wire increases the active area of the consumable electrode and thus improves the energy characteristics (the amount of current removed) of the air-aluminum fuel cell.
The essence of the invention is illustrated by drawings, where:
in fig. 1 shows an air-aluminum current source;
in fig. 2 - view A in Fig. 1;
in fig. 3 is view B in FIG. 1.
The air-aluminum fuel cell consists of a metal case 1 with holes 2 for passing air to the three-phase boundary, a gas diffusion cathode 3, an electrolyte 4, 2 hydrophobic covers 5 located on both sides of the metal case 1, an electrode in the form of a thin-walled rod 6, aluminum wire 7 wound on a helical groove.
As aluminum wire 7 is consumed, corrosion and passivation of the electrode surface occur, which leads to a decrease in the magnitude of the removed current and the attenuation of the electrochemical process. To activate the process, it is necessary to screw a thin-walled rod with a helical groove, in which a consumable aluminum wire is wound, into hydrophobic caps 5. Hydrogen is released through the helical surfaces of hydrophobic caps 5, while the electrolyte remains inside the metal housing 1 of the fuel cell.
This method makes it possible to automate the process of replacing the anode (consumable electrode) in an air-aluminum current source (HAPS) without interrupting the power supply circuit, as well as removing the hydrogen released during operation.
A method for introducing a consumable electrode into an air-aluminum fuel cell, which includes moving the consumable electrode as it is worn out inside the fuel cell body, characterized in that a consumable electrode is used in the form of aluminum wire, which is wound on a helical groove of a thin-walled rod made of dielectric hydrophobic material and one end which is inserted into the cavity of the thin-walled rod through a hole in its lower part, and the movement of the consumable electrode is carried out by screwing the thin-walled rod into the caps of the fuel cell housing located on both sides of the housing and made of a hydrophobic material, ensuring that the electrolyte is stored inside the fuel cell and removed from it housings of escaping hydrogen along the helical surface of hydrophobic lids.
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The invention relates to solid oxide fuel cells with internal reforming capability. A solid oxide fuel cell typically includes a cathode, an electrolyte, an anode, and a catalyst layer in contact with the anode.
The present invention relates to an alkali cation conducting ceramic membrane having at least a portion of its surface coated with a layer of an organic cation conducting polyelectrolyte that is insoluble and chemically stable in water at basic pH.
The invention relates to chemical current sources with a gas-diffusion air cathode, a metal anode and aqueous electrolyte solutions. SUBSTANCE: metal-air current source contains a body filled with electrolyte, a metal anode placed inside it, gas-diffusion air cathodes located on both sides of the metal anode. At the same time, gas-diffusion air cathodes have central transverse bends and are separated from the metal anode by electrolyte-permeable porous separators made of a material with high ohmic resistance. The metal anode has the shape of a rectangular parallelepiped, conjugated with a wedge, and the wedge rests on the said porous separators. The proposed metal-air current source has an increased specific capacity, stable characteristics and an extended service life, since it allows to increase the ratio of the mass of the dissolving part of the metal anode to the electrolyte volume, and, consequently, the specific energy intensity and operating time of the current source without replacing the metal anode. 10 ill., 2 pr.
SUBSTANCE: invention relates to energy sources, namely to methods for replacing a consumable electrode in an air-aluminum fuel cell without interrupting the power supply circuit. A consumable electrode is used in the form of an aluminum wire, which is wound on a helical groove of a thin-walled rod made of a dielectric hydrophobic material. One end of the wire is inserted into the cavity of the thin-walled rod through a hole in its lower part. The consumable electrode is moved by screwing a thin-walled rod into the covers of the fuel cell housing, located on both sides of the housing and made of a hydrophobic material, ensuring the preservation of the electrolyte inside the fuel cell and removal of the evolving hydrogen from its housing along the helical surface of the hydrophobic covers. EFFECT: increased energy performance of the fuel cell. 3 ill.
She was the first in the world to manufacture an air-aluminum battery suitable for use in a car. A 100 kg Al-Air battery contains enough energy to power a compact passenger car for 3,000 km. Phinergy held a demonstration of the technology with a Citroen C1 and a simplified version of the battery (50 x 500g plates in a case filled with water). The car traveled 1800 km on a single charge, stopping only to replenish water supplies - a consumable electrolyte ( video).
Aluminum won't replace lithium-ion batteries (it doesn't charge from a wall outlet), but it's a great addition. After all, 95% of trips the car makes for short distances, where there are enough standard batteries. An extra battery provides a backup in case the battery runs out or if you need to travel far.
An aluminum air battery generates current by chemically reacting the metal with oxygen from the surrounding air. Aluminum plate - anode. The cell is coated on both sides with a porous material with a silver catalyst that filters CO 2 . Metal elements slowly degrade to Al(OH) 3 .
The chemical formula for the reaction looks like this:
4 Al + 3 O 2 + 6 H 2 O \u003d 4 Al (OH) 3 + 2.71 V
This is not some sensational novelty, but a well-known technology. It has long been used by the military, as such elements provide exceptionally high energy density. But before, engineers could not solve the problem with CO 2 filtration and associated carbonization. Phinergy claims to have solved the problem and already in 2017 it is possible to produce aluminum batteries for electric vehicles (and not only for them).
Tesla Model S lithium-ion batteries weigh about 1000 kg and provide a range of 500 km (in ideal conditions, in reality 180-480 km). Let's say if you reduce them to 900 kg and add an aluminum battery, then the mass of the car will not change. The range from the battery will decrease by 10-20%, but the maximum mileage without charging will increase right up to 3180-3480 km! You can drive from Moscow to Paris, and something else will remain.
In some ways, this is similar to the concept of a hybrid car, but it does not require an expensive and bulky internal combustion engine.
The disadvantage of the technology is obvious - the aluminum-air battery will have to be changed at a service center. Probably once a year or more. However, this is quite a routine procedure. Tesla Motors last year showed how Model S batteries are changed in 90 seconds ( amateur video).
Other disadvantages are the energy consumption of production and, possibly, the high price. The manufacture and recycling of aluminum batteries requires a lot of energy. That is, from an environmental point of view, their use only increases the overall electricity consumption in the entire economy. But on the other hand, consumption is more optimally distributed - it leaves large cities for remote areas with cheap energy, where there are hydroelectric power stations and metallurgical plants.
It is also unknown how much such batteries will cost. Although aluminum itself is a cheap metal, the cathode contains expensive silver. Phinergy does not disclose exactly how the patented catalyst is made. Perhaps this is a complex process.
But for all its shortcomings, the aluminum-air battery still seems like a very convenient addition to an electric car. At least as a temporary solution for the coming years (decades?) until the problem of battery capacity disappears.
Phinergy, meanwhile, is experimenting with a "rechargeable"
The French company Renault proposes to use aluminum-air batteries from Phinergy in future electric vehicles. Let's take a look at their perspectives.
Renault has decided to bet on a new type of battery that could increase the driving range on a single charge by seven times. While maintaining the size and weight of today's batteries. Aluminum-air (Al-air) cells have a phenomenal energy density (8000 W / kg, versus 1000 W / kg for traditional batteries), generating it during the oxidation reaction of aluminum in air. Such a battery contains a positive cathode and a negative anode made of aluminum, and between the electrodes is a liquid water-based electrolyte.
Battery developer Phinergy said it has made great progress in developing such batteries. Their proposal is to use a catalyst made of silver, which makes it possible to effectively use the oxygen contained in ordinary air. This oxygen mixes with the liquid electrolyte and thereby releases the electrical energy contained in the aluminum anode. The main nuance is the “air cathode”, which acts like a membrane in your winter jacket - only O2 passes through, not carbon dioxide.
What is the difference from traditional batteries? The latter have completely closed cells, while Al-air elements need an external element to "trigger" the reaction. An important plus is the fact that the Al-air battery acts like a diesel generator - it produces energy only when you turn it on. And when you “shut off the air” to such a battery, its entire charge remains in place and does not disappear over time, like with conventional batteries.
Al-air batteries use an aluminum electrode during operation, but it can be made replaceable, like a cartridge in a printer. Charging needs to be done every 400 km, it will consist in adding new electrolyte, which is much easier than waiting for a regular battery to charge.
Phinergy has already created an electric Citroen C1, which is equipped with a 25 kg battery with a capacity of 100 kWh. It gives a power reserve of 960 km. With a 50 kW motor (about 67 horsepower), the car reaches speeds of 130 km / h, accelerates to hundreds in 14 seconds. A similar battery is also being tested on the Renault Zoe, but its capacity is 22 kWh, the maximum speed of the car is 135 km / h, 13.5 seconds to “hundreds”, but only 210 km of power reserve.
The new batteries are lighter, half the price of lithium-ion batteries and, in the future, easier to operate than current ones. And so far, their only problem is the aluminum electrode, which is difficult to manufacture and replace. As soon as this problem is solved, we can safely expect an even greater wave of popularity of electric vehicles!
- , 20 Jan 2015
