In order to draw up a diagram of a galvanic cell, it is necessary to understand the principle of its action, structural features.
Consumers rarely pay attention to accumulators and batteries, while these current sources are the most in demand.
What is a galvanic cell? Its circuit is based on an electrolyte. The device includes a small container where the electrolyte is located, adsorbed by the separator material. In addition, the scheme of two galvanic cells assumes the presence. What is the name of such a galvanic cell? The scheme linking two metals together suggests the presence of a redox reaction.
It implies the presence of two plates or rods made of different metals, which are immersed in a strong electrolyte solution. During the operation of this galvanic cell, an oxidation process is carried out on the anode, associated with the return of electrons.
At the cathode - reduction, accompanied by the acceptance of negative particles. There is a transfer of electrons along the external circuit to the oxidizing agent from the reducing agent.
In order to compose electronic circuits galvanic cells, it is necessary to know the value of their standard electrode potential. Let us analyze a variant of a copper-zinc galvanic cell operating on the basis of the energy released during the interaction of copper sulfate with zinc.
This galvanic cell, the scheme of which will be given below, is called the Jacobi-Daniel cell. It includes which is immersed in a solution of copper sulfate (copper electrode), and it also consists of a zinc plate in a solution of its sulfate (zinc electrode). The solutions are in contact with each other, but in order to prevent their mixing, a partition made of a porous material is used in the element.
How does a galvanic cell function, the circuit of which is Zn ½ ZnSO4 ½½ CuSO4 ½ Cu? During its operation, when the electrical circuit is closed, the process of oxidation of metallic zinc occurs.
On its contact surface with a salt solution, the transformation of atoms into Zn2+ cations is observed. The process is accompanied by the release of "free" electrons, which move along the external circuit.
The reaction taking place on the zinc electrode can be represented as follows:
The reduction of metal cations is carried out on a copper electrode. Negative particles that enter here from the zinc electrode combine with copper cations, depositing them in the form of a metal. This process looks like this:
If we add the two reactions discussed above, we get a summary equation that describes the operation of a zinc-copper galvanic cell.
The anode is a zinc electrode, the cathode is copper. Modern galvanic cells and batteries require the use of a single electrolyte solution, which expands the scope of their application, makes their operation more comfortable and convenient.
The most common are carbon-zinc elements. They use a passive carbon current collector in contact with the anode, which is manganese oxide (4). The electrolyte is ammonium chloride used in paste form.
It does not spread, so the galvanic cell itself is called dry. Its feature is the ability to “recover” during operation, which has a positive effect on the duration of their operational period. Such galvanic cells have a low cost, but low power. When the temperature drops, they reduce their efficiency, and when it rises, the electrolyte gradually dries out.
Alkaline elements involve the use of an alkali solution, so they have quite a few applications.
In lithium cells, an active metal acts as an anode, which has a positive effect on the service life. Lithium has a negative therefore, with small dimensions, such elements have a maximum rated voltage. Among the disadvantages of such systems is the high price. Opening lithium current sources is explosive.
The principle of operation of any galvanic cell is based on redox processes occurring at the cathode and anode. Depending on the metal used, the selected electrolyte solution, the service life of the element changes, as well as the value of the rated voltage. Currently, lithium, cadmium galvanic cells with a sufficiently long service life are in demand.
Galvanic cell- this is a chemical current source in which the energy released during the course of a redox reaction on the electrodes is directly converted into electrical energy .
Rice. 9.2. Diagram of a galvanic cell by Daniel - Jacobi
Here I is a glass containing a solution of ZnSO 4 in water with a zinc plate immersed in it; II - a glass containing a solution of CuSO 4 in water with a copper plate immersed in it; III - salt bridge (electrolytic key), which ensures the movement of cations and anions between solutions; IV - voltmeter (needed to measure EMF, but not included in the composition of the galvanic cell).
Standard electrode potential of a zinc electrode. Standard electrode potential of a copper electrode. Since, then zinc atoms will be oxidized:
The electrode at which the reduction reaction takes place or which accepts cations from the electrolyte is called cathode.
Through the electrolytic key, the movement of ions in solution occurs: SO 4 2- anions to the anode, Zn 2+ cations to the cathode. The movement of ions in solution closes electrical circuit galvanic element.
Reactions (a) and (b) are called electrode reactions.
Adding the equations of the processes occurring on the electrodes, we obtain the total equation of the redox reaction occurring in the galvanic cell:
In the general case, the overall equation of the redox reaction occurring in an arbitrary galvanic cell can be represented as:
The Daniel-Jacobi galvanic cell circuit has the form:
Zn | ZnSO 4 || CuSO4 | Cu
The maximum potential difference of the electrodes that can be obtained during the operation of a galvanic cell is called electromotive force(emf) element E. It is calculated according to the formula;
Where n- the number of electrons in the elementary redox act, F is the Faraday number.
The magnitude of the change in the isobaric-isothermal potential of the current-forming reaction under standard conditions? G 0 is related to the equilibrium constant of this reaction TO is equal to the ratio
| (9.6) |
Galvanic cells are primary (single-use) chemical current sources (CSS). Secondary (reusable) HIT are batteries. The processes occurring during the discharge and charging of batteries are mutually inverse.
Galvanic cells in which the electrodes are made of the same metal and immersed in solutions of their salts of different concentrations are called concentration. The function of the anode in such elements is performed by a metal immersed in a salt solution with a lower concentration, for example:
Example 1 Make a diagram of a galvanic cell based on the reaction: Mg + ZnSO 4 = MgSO 4 + Zn. What is the cathode and anode in this element? Write the equations for the processes occurring on these electrodes. Calculate the EMF of the element under standard conditions. Calculate the equilibrium constant for the current-forming reaction.
Low-power sources of electrical energy
To power portable electrical and radio equipment, galvanic cells and batteries are used.
Galvanic cells are one-time sources accumulators- sources of reusable action.
The simplest galvanic cell
The simplest element can be made from two strips: copper and zinc, immersed in water slightly acidified with sulfuric acid. If the zinc is pure enough to be free from local reactions, no noticeable change will occur until the copper and zinc are wired together.
However, the strips have different potentials one with respect to the other, and when they are connected by a wire, it will appear. As this action progresses, the zinc strip will gradually dissolve, and gas bubbles will form near the copper electrode, collecting on its surface. This gas is hydrogen, which is formed from the electrolyte. Electric current flows from the copper strip through the wire to the zinc strip, and from it through the electrolyte back to the copper.
Gradually, the sulfuric acid of the electrolyte is replaced by zinc sulfate, which is formed from the dissolved part of the zinc electrode. Due to this, the voltage of the element is reduced. However, an even greater voltage drop is caused by the formation of gas bubbles on the copper. Both of these actions produce "polarization". Such elements have almost no practical value.
Important parameters of galvanic cells
The magnitude of the voltage given by galvanic cells depends only on their type and device, that is, on the material of the electrodes and the chemical composition of the electrolyte, but does not depend on the shape and size of the cells.
The amount of current that a galvanic cell can supply is limited by its internal resistance.
Very important characteristic galvanic cell is . By electric capacity is meant the amount of electricity that a galvanic or battery cell is able to give off during the entire time of its operation, that is, until the final discharge occurs.
The capacity given by the element is determined by multiplying the discharge current, expressed in amperes, by the time in hours, during which the element was discharged until the onset of a complete discharge. Therefore, the electrical capacity is always expressed in ampere-hours (A x h).
By the value of the capacity of the element, you can also determine in advance how many hours it will work approximately before the onset of a full discharge. To do this, you need to divide the capacitance by the strength of the discharge current allowed for this element.
However, the electrical capacitance is not a strictly constant value. It varies within fairly large limits depending on the conditions (mode) of the element and the final discharge voltage.
If the element is discharged with the maximum current strength and, moreover, without interruptions, then it will give off a much lower capacity. On the contrary, when the same element is discharged with a current of lesser strength and with frequent and relatively long interruptions, the element will give up its full capacity.
As for the effect of the final discharge voltage on the capacitance of the cell, it must be borne in mind that during the discharge of a galvanic cell, its operating voltage does not remain at the same level, but gradually decreases.
Common types of galvanic cells
The most common galvanic cells are manganese-zinc, manganese-air, air-zinc and mercury-zinc systems with salt and alkaline electrolytes. Dry manganese-zinc cells with saline electrolyte have an initial voltage of 1.4 to 1.55 V, the duration of operation at an ambient temperature of -20 to -60 ° C from 7 hours to 340 hours.
Dry manganese-zinc and air-zinc cells with an alkaline electrolyte have a voltage of 0.75 to 0.9 V and an operating time of 6 hours to 45 hours.
Dry mercury-zinc cells have an initial voltage of 1.22 to 1.25 V and an operating time of 24 hours to 55 hours.
Dry mercury-zinc elements have the longest guaranteed shelf life, reaching 30 months.
These are secondary galvanic cells.Unlike galvanic cells, no chemical processes occur in the battery immediately after assembly.
In order for the chemical reactions associated with movement to begin in the battery electric charges, you need to change the chemical composition of its electrodes (and part of the electrolyte) accordingly. This change in the chemical composition of the electrodes occurs under the action of an electric current passed through the battery.
Therefore, in order for the battery to be able to produce electric current, it must first be “charged” with direct electric current from some external current source.
Batteries also compare favorably with conventional galvanic cells in that they can be charged again after being discharged. With good care and under normal operating conditions, batteries can withstand up to several thousand charges and discharges.
Battery device
Currently, lead and cadmium-nickel batteries are most often used in practice. For the former, a solution of sulfuric acid serves as an electrolyte, and for the latter, a solution of alkalis in water. Lead-acid batteries are also called acid, and cadmium-nickel batteries are called alkaline.
The principle of operation of batteries is based on the polarization of electrodes. The simplest acid battery is arranged as follows: these are two lead plates immersed in an electrolyte. As a result of a chemical replacement reaction, the plates are covered with a slight coating of lead sulfate PbSO4, as follows from the formula Pb + H 2 SO 4 \u003d PbSO 4 + H 2.
Acid battery device
This state of the plates corresponds to a discharged battery. If now the battery is turned on for a charge, i.e., connect it to the generator direct current, then in it, due to electrolysis, the polarization of the plates will begin. As a result of the battery charge, its plates are polarized, that is, they change the substance of their surface, and from homogeneous (PbSO 4) they turn into heterogeneous (Pb and Pb O 2).
The battery becomes a current source, with a plate coated with lead dioxide serving as the positive electrode, and a clean lead plate as the negative electrode.
By the end of the charge, the electrolyte concentration increases due to the appearance of additional sulfuric acid molecules in it.
This is one of the features of a lead battery: its electrolyte does not remain neutral and itself participates in chemical reactions during battery operation.
By the end of the discharge, both battery plates are again covered with lead sulfate, as a result of which the battery ceases to be a current source. The battery is never brought to such a state. Due to the formation of lead sulfate on the plates, the electrolyte concentration at the end of the discharge decreases. If the battery is put on charge, then again it is possible to cause polarization in order to put it on discharge again, etc.
There are several ways to charge batteries. The simplest is the normal battery charge, which occurs as follows. Initially, for 5 - 6 hours, the charge is carried out with a double normal current, until the voltage on each battery bank reaches 2.4 V.
The normal charging current is determined by the formula I charge \u003d Q / 16
Where Q - nominal battery capacity, Ah.
After that, the charging current is reduced to a normal value and the charge is continued for 15-18 hours, until signs of the end of the charge appear.
Modern batteries
Cadmium-nickel, or alkaline batteries, appeared much later than lead ones and, in comparison with them, are more advanced chemical current sources. The main advantage of alkaline batteries over lead ones is the chemical neutrality of their electrolyte with respect to the active masses of the plates. Due to this, the self-discharge of alkaline batteries is much less than that of lead-acid batteries. The principle of operation of alkaline batteries is also based on the polarization of electrodes during electrolysis.
To power radio equipment, sealed cadmium-nickel batteries are produced that are operational at temperatures from -30 to +50 ° C and withstand 400 - 600 charge-discharge cycles. These accumulators are made in the form of compact parallelepipeds and discs weighing from a few grams to kilograms.
They produce nickel-hydrogen batteries for power supply of autonomous objects. The specific energy of a nickel-hydrogen battery is 50 - 60 W h kg -1.
Galvanic cell A device that converts chemical energy into electrical energy. One such element is the Daniel–Jacobi element. This element consists of two electrodes: zinc and copper, immersed in the corresponding sulfate solutions, between which there is a porous partition:
When the external circuit is closed, electrons pass from Zn to Cu, and zinc diffuses into copper:
We form an electrochemical circuit:
Anode - negative electrode (left). The cathode is the positive electrode.
To determine the EMF of this element, you need to compare the standard electrode potentials of both electrodes. When recording electrode reactions, it is assumed that the oxidized form is on the left side, and the reduced form is on the right side of the equation.
Where E 0 - electromotive force (EMF) of a galvanic cell, when all reagents are in the standard state.
The cell emf is calculated by subtracting the anode potential from the cathode potential.
The EMF of the element is +0.34 - (-0.76) \u003d 1.1 V; the more the electrode potentials differ from each other, the greater the EMF. If a metal is immersed in a salt solution of a higher concentration, then the potential is non-standard. This means that the concentration and temperature affect the magnitude of the electrode potential. This dependence is expressed V. Nernst equation.
Where P - number of ions;
R is the universal gas constant;
T - temperature;
WITH - concentration of active ions in solution;
F- Faraday number = 96500 V.
HITS- devices that are used to directly convert the energy of a chemical reaction into electrical energy. Hits are used in various fields of technology. In the means of communication: radio, telephone, telegraph; in electrical measuring equipment; they serve as power sources for cars, aircraft, tractors; used to drive starters, etc.
HIT Disadvantages:
1) the cost of substances necessary for work: Pb, Cd, is high;
2) the ratio of the amount of energy that an element can give to its mass is small.
HIT Benefits:
1) Hits are divided into two main groups: reversible (batteries), irreversible (galvanic cells). Batteries can be used repeatedly, since their performance can be restored by passing current in the opposite direction from an external source, and in galvanic cells they can only be used once, since one of the electrodes (Zn in the Daniel-Jacobi cell) is irreversibly consumed;
2) electrolytes absorbed by porous materials are used, they have a greater internal resistance;
3) the creation of fuel cells, during the operation of which cheap substances with low density (natural gas, hydrogen) would be consumed;
4) convenient operation, reliability, high and stable voltage.
Consider the process of technology based on a lead-acid battery with coated electrodes.
General scheme: (–) active substance | electrolyte | active substance (+).
The active substance of the negative electrode is reducing agent donating electrons. During discharge, the negative electrode is an anode, i.e., an electrode on which oxidative processes occur. The active substance of the positive electrode is oxidizer. Active substances - an oxidizing agent and a reducing agent - participate in an electrochemical reaction.
Electrochemical diagram of a lead-acid battery
The active substances of a lead battery are spongy lead and PbO 2 . The creation of active masses in the electrodes is as follows: a paste or a mixture of Pb oxides is applied to the electrically conductive frame of the structure; during the subsequent formation of plates, Pb oxides are converted into active substances. Formation– conversion of uncharged mass into charged mass. Such plates are subdivided depending on the type of frame into spread and lattice. Most batteries are assembled from plastered plates. In their manufacture, a paste of lead oxides is smeared into the cells of profiled gratings 1–7 mm thick, cast from a Pb–Sb alloy. After hardening, the paste is held on the grid, the guarantee of such a battery is 2-3 years. When choosing materials for current collectors of positive battery electrodes, it is important to ensure their practical passivity (while maintaining electrical conductivity) under charging conditions (up to very high potentials with anodic polarization). For this purpose, Pb or its alloys are used in H 2 SO 4 solutions. The body and cover of the HIT can be made of steel or various dielectrics, but in lead-acid batteries, the body is made of ebonite, polypropylene, and glass. The electrolyte in a lead-acid battery can participate in the overall current-generating reaction. For current-carrying taps of the negative electrode, Cu, Ti, Al are used.
3. Regeneration and disposal of HITs
The service life of galvanic cells ends (discharge HIT) after full or partial use of active materials, the performance of which after the discharge can be restored by charging, that is, by passing current in the direction opposite to the direction of the current during discharge: such galvanic cells are called accumulators. The negative electrode, which was the anode when the battery was discharging, becomes the cathode when charged. conditions best use active materials are low current density, high temperatures to normal. Usually the reason for the malfunction of HITs is electrode passivation– a sharp decrease in the rate of the electrochemical process during the discharge, caused by a change in the state of the electrode surface during the discharge due to the formation of oxide layers or salt films. The way to combat passivation is to reduce the true discharge current densities by using electrodes with developed surfaces. The production of HIT is characterized by the use of various toxic substances (strong oxidizing agents, Pb, Hg, Zn, Cd, Ni compounds used in a finely dispersed state; acids, alkalis, organic solvents). To ensure normal working conditions, automation of production processes, rational ventilation systems are provided, including the use of local exhausts from devices with toxic emissions, equipment sealing, replacement of dry methods of processing dusty materials with wet ones, purification of polluted air and gases from aerosols, and industrial wastewater treatment. The massive use of HIT in the national economy is associated with environmental problems. While lead from batteries can mostly be returned to recycling plants by consumers, the disposal of small household primary CPS is not economically viable.
Each Hg-Zn battery provides 5-7 days of hearing aid operation.
Electric vehicles are being developed using HIT instead of internal combustion engines, which poison the atmosphere of cities with exhaust gases. In terms of the degree of negative impact on the environment, galvanic production ranks first. The reason for the extremely negative impact of galvanic production is that in the vast majority of enterprises only 10–30% of heavy metal salts are usefully consumed in the technological processes of coating, while the rest enters the environment with unsatisfactory work. The way out is to minimize the loss of non-ferrous metal salts, that is, to reduce the removal of electrolytes from electroplating baths by parts. This will lead to a decrease in the concentrations and volumes of wastewater and thereby create the necessary conditions for conducting low-waste (MOT) and non-waste (LOT) technologies for applying galvanic coatings. You must first choose the right electrolyte. A fundamental principle of the ILO and BOT is to reduce input chemicals and deliver less poisons at the output of the process.
Homemade galvanic cell for autonomous power supply
Volta element
To power and charge portable electronics in places where there is no power supply, you can successfully use, along with other sources of electricity, the simplest chemical current sources, galvanic cells.
Their use is possible in dachas for long-term residence in the absence of an electrical network, as well as in remote villages where there is either no electricity at all, or constant power outages. In Soviet Russia, chemical current sources or galvanic cells became widespread in amateur radio technology in the middle of the last century, since these sources are easy to manufacture and are made from readily available materials.
Now when portable electronics has become very economical in terms of power consumption, its power from home-made chemical current sources can be very effective, since such current sources were successfully used at the dawn of the development of radio engineering. Then the equipment consumed many times more electricity than modern equipment, and now with the development of energy-saving lighting technology. For example, LED lighting consumes 4-5 times less electricity than conventional light bulbs. Also modern Cell phones, PDAs and other gadgets consume almost nothing more, and even less than the radio equipment of the past decades.
Attention!
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SIMPLE GALVANIC CELL, VOLT ELEMENT
Voltaic column The first chemical current source was invented by the Italian scientist Alessandro Volta in 1800. It was Volta's element - a vessel with salt water with zinc and copper plates lowered into it, connected by wire. Then the scientist assembled a battery of these elements, which was later called the Voltaic Pillar. This invention was subsequently used by other scientists in their research. So, for example, in 1802, the Russian academician V.V. Petrov designed the Voltaic column of 2100 elements to produce an electric arc.
In 1836, the English chemist John Daniel improved the Volta element by placing zinc and copper electrodes in a solution of sulfuric acid. This design became known as the “Daniel element.” In 1859, the French physicist Gaston Plante invented the lead-acid battery. This type of cell is still used in car batteries to this day. In 1865, the French chemist J. Leclanchet proposed his galvanic cell (Leclanchet cell), which consisted of a zinc cup filled with an aqueous solution of ammonium chloride or other chloride salt, in which an agglomerate of manganese (IV) oxide MnO2 with a carbon current lead.
A modification of this design is still used in salt batteries for various household devices. In 1890, in New York, Konrad Hubert, an immigrant from Russia, creates the first pocket electric flashlight. And already in 1896, the National Carbon company began mass production of the world's first dry elements Leklanshe "Columbia". The longest-lived galvanic cell is a zinc-sulfur battery, made in London in 1840. The bell connected to it still works today.
The simplest copper-zinc element consists of two plate electrodes immersed in an electrolyte solution; when immersed in an electrolyte, a potential difference arises between the metals. When a copper plate and a zinc plate are immersed in a sodium chloride solution, a potential difference of about 1 volt occurs, and one element, regardless of size, has a voltage of one volt, and the power of such an element depends on its size and the area of \u200b\u200bthe plates immersed in the electrolyte. To obtain a higher voltage, these elements, like the factory batteries, are connected in series to obtain the desired voltage.
CHARACTERISTICS OF THE COPPER-ZINC ELEMENT
Copper-zinc current sources. The production of these chemical current sources began as early as 1889. Currently, they are produced on a small scale in the form of cells with a capacity of 250 to 1000 Ah. Smooth zinc plates and plates from a mixture of copper oxide, copper and a binder are placed in a glass or metal vessel with a 20% NaOH solution. The elements have a voltage of 0.6-0.7 V and a specific energy of 25-30 Wh/kg. Their advantages include the constancy of the discharge voltage, very low self-discharge, non-failure operation and low price. They were used in signaling and communication systems on railways.
IN real conditions the energy intensity can vary greatly and it depends on the area of the plastic, the purity of the metals and the density of the electrolyte. 20A / h, but in such elements a very small discharge current is small, and the circuit current can be about 100-150mA / h, and the less the connected source consumes, the more the copper-zinc element can generate electricity. An element assembled in a liter jar at a discharge current of 50 mA / h will work from 200 hours to 400 hours or more, but over time the plates oxidize and the voltage drops and as a result the element stops working. To restore the element, it is necessary to replace the electrolyte and clean the plates from oxidation and the element will work again.
The oxidation process depends on the discharge current, the higher it is, the faster the element will fail, but on average, an element in a liter jar before cleaning and recharging, with a discharge current of 50 mA / h, will work for about 3-4 months, and with a discharge current of 2- 5 mA / h will last for a year or more. A simple liter element is not enough to power even a simple miniature radio receiver, and in order to get the desired characteristics, you need to assemble a block of several elements.
Now, basically, all portable electronics are powered by a voltage of 3.6-4.5 volts, and in order to get such numbers, you need to connect 4-5 such elements in series, if you connect 5 liter elements, you get about 3.5-4.8 volt, and the capacity increases to 40-50 A / h, and the discharge current can reach 400-600 mA / h, therefore, such a source can easily cope with powering a small radio or LED flashlight, as well as charging miniature phone batteries for 10-30 hours. But to power high-power LED lights and power modern phones and the CCP such sources will not be enough.
FOR STABLE LONG-TERM AUTONOMOUS POWER SUPPLY FOR PORTABLE ELECTRONICS
you will need something bigger, for example, an element with a capacity as in the figure, a volume of 40-50 liters, for a stable supply of portable indoor LED lamps and other technology. For the manufacture of such a chemical source of electricity, you will not need: 5 copper plates measuring 20x40, and 5 of the same zinc, then you need to solder or press on each plate by bending the corner of the plate, insert the wiring and flatten it with a hammer.
After that, you need to fix the plates through electron-conductive spacers (a wooden block or a plastic tube) to each other, then lower them into containers with electrolyte, this is either a solution of sodium chloride or a solution of ammonia or a solution of sulfuric acid (auto electrolyte), after which we connect the resulting batteries in series, that is the copper plate of one element is connected through wires to the zinc plate of another element. As a result, on one side of the resulting block there remains a copper plate with wiring (+), and on the other, zinc (-). The larger the area of the plates and the better the electrolyte, the higher the efficiency of such a current source.
HOME-MADE COPPER-VITAL ELEMENT
In this homemade design, due to the unavailability of pure zinc, an aluminum electrode was used, but the emf. aluminum is lower than that of zinc, is 0.5 V, that is, one bank gives only 0.5 volts, because of this, the device does not consist of 4 cans for a voltage of 3.5-4 volts, but of 6 to get at least 3.6 volts.
When testing this device, there were no measuring instruments, but as you can see from the photo, the device freely provides the glow of 12 LEDs - the current consumption is 150-200mA, and charges the mobile phone - the consumption current is about 400mA.
When tested, the cell charged a 750mA phone battery in 2.40 minutes.
Approximate specifications batteries of cells, consisting of 6 cans, with a capacity of 0.33 liters: 3.7 Volts, circuit current about 500mA, capacity 25-30A / h.
During the test, the battery of cells worked stably on one tablespoon of vitriol for about 100 hours at a discharge current of about 200 mAh, now the device also works, but the current strength is much less and is about 80 mAh, the vitriol is almost used up, so if you calculate , then you can determine how long the elements will generally work on a certain amount of vitriol, feeding certain devices.
MANUFACTURING ORDER
IN THIS DESIGN, ALUMINUM CANS (BEER) AND OTHER ALUMINUM PRODUCTS WERE USED AS ALUMINUM ELECTRODE.
IF ALUMINUM CANS ARE USED, THEY SHOULD BE CAREFULLY CLEANED FROM THE PROTECTIVE INTERNAL LAYER AND EXTERNAL MARKINGS AS THEY DO NOT PASS CURRENT.
First, the inner surface of the jar is smeared with petroleum jelly or lard at a distance of 3-4 centimeters from the upper edge of the jar, this is done in order to prevent salt crystals from creeping out of the vessel of the element.
Further, in the cylinder, it is necessary to make double cuts on one side to a depth of 4-5 mm, and bend the resulting brackets outward so that the cylinder hangs on them, on the neck of the can, not reaching the bottom of the can by 5 cm, after manufacturing solder to him copper wire, this will be (+).
Next, a diaphragm is made, the diaphragm is made of cardboard, a cylinder is made of cardboard along the length of the can, or 5 cm shorter than the can, and then a cardboard bottom is sewn to it with threads, so that there are no gaps left, and the stitching points are soaked with hot paraffin to seal bottom to prevent liquid from escaping.
Next, several layers of parchment or newsprint are tightly wound onto the cylinder, previously soaked in saline so that there are no air gaps, and after the resulting “glass” is tightly sheathed with a fabric wrapped in several layers for mechanical strength.
Then a ring is glued or sewn onto the top of the diaphragm so that the glass does not fall through, and the attachment points are coated with hot paraffin, a hole is made in the ring through which water is poured into the jar and a stirrer is inserted to stir the vitriol.
Then, a solution of common salt should be poured into the diaphragm and left for several hours, a properly assembled diaphragm should not leak, and its surface should only be wet. -), the zinc cylinder should freely enter the diaphragm, but at the same time be as close as possible to its walls, that is, closer to the copper cylinder, in order to reduce internal resistance, and accordingly increase efficiency.
ELEMENT ASSEMBLY.
In a clean jar, if 0.5 l., Pour a tablespoon of copper sulphate, insert a stirrer, and then install a diaphragm filled with a solution of sodium chloride, then water is poured into the hole that is for the stirrer, and then zinc is inserted into the diaphragm cylinder, after assembly, the element is completely ready for work, it remains to connect the elements in series, like ordinary batteries, and power and charge the devices.
The use of a porous diaphragm is due to the separation of electrolytes, that is, the separation of vitriol crystals and brine from mixing, otherwise the vitriol reacts violently and is consumed too quickly, even when the cell is not used, and the vitriol flow through the diaphragm is uniform and economical, which ensures long work current source-galvanic cell..
Hoopoe by element consists in periodic refueling of vitriol, changing the electrolyte and cleaning the electrodes from oxidation. With a current consumption of about 600mA (cell phone), a battery consisting of 4 half-liter cells will work on one refill of vitriol (4 tablespoons) for about a month, provided that it is used every day for about 6 hours. .When the power drops, it is necessary to periodically stir up the copper sulfate with a stirrer. zinc.
Note. If you replace zinc with aluminum, then you need not 4 or 5 elements, but 6 or 7 connected in series, since the emf. aluminum is lower than that of zinc, and is 0.4-0.6 V.
