Electric battery

Electric battery is a device that converts chemical energy into electrical energy. All batteries are made up of an electrolyte (which can be liquid, solid or pasty), a positive and a negative electrode. The electrolyte is an ionic conductor; while one electrode generates electrons and the other accepts them. By connecting the electrodes to the circuit to be powered, an electric current is produced. Batteries are divided into primary or voltaic, in which the chemical reaction cannot be reversed (non-rechargeable) and secondary or accumulators, in which the reaction is reversible and can be brought to its original state (rechargeable), passing a current through the circuit in the opposite direction to the normal flow of electrons in the battery.

In recent years, solar cells have been developed that produce electricity through a photoelectric conversion process. The source of electricity is a photosensitive semiconductor substance, such as a silicon crystal to which impurities have been added. When light strikes the crystal, electrons from the surface are released to the opposite surface where they are distributed. Solar cells have a very long life and are mainly used in aircraft and space vehicles as a source of electricity.

Summary

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• 1 Mechanism of reactions in a cell
• 2 types of batteries
• 3 Composition of the most common batteries
  • 1Pila voltaica
  • 2 Homemade battery or Daniell battery
• 4Fuente

Mechanism of reactions in a battery

When a metal more active than hydrogen is introduced into an acidic solution, a redox reaction will occur: the metal will oxidize, passing its ions into the solution and the hydrogen ions will be reduced on the surface of the metal, releasing gaseous hydrogen. If another less active metal is introduced into said solution and both are connected by means of a metallic conductor, part of the electrons produced by the oxidation of the more active metal will circulate through the conductor towards the less active metal and will be reduced on its surface. most of the hydrogen ions. The flow of electrons through the conductor constitutes an electric current and can be used to do work such as turning on a light bulb; power a resistor; carry out electrolysis.

battery types

• Primarybattery The most common is the Leclanché battery or dry battery, invented by the French chemist Georges Leclanché in the 1860s . The dry cell used today is very similar to the original invention. The electrolyte is a paste consisting of a mixture of ammonium chloride and zinc chloride . The negative electrode is zinc, just like the battery container, and the positive electrode is a carbon rod surrounded by a mixture of carbon and manganese dioxide . This battery produces an electromotive force of about 1.5 volts.

Another widely used primary battery is the zinc mercuric oxide battery , commonly known as a mercury battery. It can be shaped like a small disc and is used in hearing aids, photoelectric cells, and electric wristwatches. The negative electrode is zinc, the positive electrode is mercuric oxide, and the electrolyte is a potassium hydroxide solution. The mercury battery produces approximately 1.34 V.

The fuel cell is another type of primary cell. It differs from the others in that the chemicals are not inside the stack, but are supplied from outside.

• Secondarybattery 0 accumulator, which can be recharged by reversing the chemical reaction, was invented in 1859 by the French physicist Gastón Planté. Planté’s battery was a lead-acid battery, and is the most widely used today. This battery, which contains three to six cells connected in series, is used in cars, trucks, airplanes, and other vehicles. Its main advantage is that it can produce enough electrical current to start a motor; however, it runs out quickly.

The electrolyte is a diluted solution of sulfuric acid, the negative electrode is lead and the positive electrode is lead dioxide. In operation, the negative lead electrode dissociates into free electrons and positive lead ions. Electrons move through the external electrical circuit and positive lead ions react with sulfate ions in the electrolyte to form lead sulfate.

When the electrons re-enter the cell at the positive lead dioxide electrode, another chemical reaction occurs. Lead dioxide reacts with hydrogen ions in the electrolyte and with electrons to form water and lead ions; the latter will be released into the electrolyte again producing lead sulfate.

A lead-acid battery wears out because the sulfuric acid gradually changes into water and lead sulfate. When recharging the battery, the chemical reactions described above are reversed until the chemicals return to their original condition. A lead-acid battery has a useful life of about four years. Produces about 2 V per battery. Recently, lead-acid batteries have been developed for special applications with a service life of 50 to 70 years.

Another widely used secondary battery is the alkaline battery or nickel-iron battery, devised by the American inventor Thomas Edison around 1900. The operating principle is the same as in the lead-acid battery, but here the negative electrode is made of iron, the positive electrode is nickel oxide, and the electrolyte is a potassium hydroxide solution. The nickel-iron cell has the disadvantage of giving off hydrogen gas during charging. This battery is mainly used in heavy industry. Edison’s battery has a useful life of about ten years and produces approximately 1.15 V.

Another alkaline battery similar to the Edison battery is the nickel -cadmium battery or cadmium battery, in which the iron electrode is replaced by a cadmium one. It also produces 1.15 V and its useful life is about 25 years.

• Solar cellsproduce electricity by a photoelectric conversion process. The source of electricity is a photosensitive semiconductor substance, such as a silicon crystal to which impurities have been added. When light strikes the crystal, electrons are released from the crystal surface and flow to the opposite surface. There they are collected as electrical current .

Solar cells have a very long life and are mainly used in aircraft as a source of electricity for on-board equipment.

• Leclanché type batteries, or Zinc/Carbon (ZN/C), or “dry batteries” Based on the oxidation of zinc in a slightly acid medium, they are composed of metallic zinc, ammonium chloride and manganese dioxide. They are called common batteries. They are used for simple and low consumption devices.
• Alkalinebatteries or DE Zinc / Manganese Dioxide (ZN / MNO2) The difference with the dry battery is the electrolyte used, in this case, potassium hydroxide, instead of ammonium chloride, and the zinc is in powder form. They are long lasting. Almost all of them are shielded, which makes it difficult to spill the constituents. However, this armor has a very long life but its duration is not unlimited.
• Nickel/Cadmium(NI/CD) Batteries They are based on a system made up of nickel hydroxide, potassium hydroxide and metallic cadmium. They have multiple life cycles, presenting the disadvantage of their relatively low tension. They can be recharged up to 1,000 times and last for decades. They do not contain mercury, but cadmium is a metal with toxic characteristics.
• Buttonbatteries They are called like this, batteries of reduced size, flat and round. The electronics market requires more and more of them. They are essential for hearing aids, pacemakers, watches, calculators and precision medical devices. Its composition is varied.
• Mercury Oxide BatteriesThey are the most toxic, they contain 30% approx. of mercury. They must be handled with caution in homes, since their accidental ingestion, which is possible due to their shape and size, can be lethal.
• Zinc-Air BatteriesThey are distinguished by having a large number of tiny holes on their surface. They have a lot of capacity and once in operation their electricity production is continuous. They contain more than 1% mercury, so they present serious residual problems.
• Nickel/Metal Hydride(NI/MH) Batteries These are secondary batteries like the nickel/cadmium ones, but where the cadmium has been replaced by a metallic alloy capable of storing hydrogen, which plays the role of anode. The cathode is nickel oxide and the electrolyte is potassium hydroxide.

The energy density produced by Ni/MH batteries is twice that produced by Ni/CD, at similar operating voltages, so they represent the new generation of rechargeable batteries that will replace the latter.

• Silver Oxide BatteriesThey are small in size, usually button type. They contain approximately 1% mercury, so they have toxic effects on the environment.
• Fuel cellAn electrochemical mechanism in which the energy of a chemical reaction is converted directly into electricity. Unlike the electric cell or battery, a fuel cell does not run out or need to be recharged; it works as long as fuel and oxidant are supplied to it from outside the stack.

A fuel cell consists of an anode into which fuel is injected – commonly hydrogen, ammonia or hydrazine – and a cathode into which an oxidant – usually air or oxygen – is introduced. The two electrodes of a fuel cell are separated by a conductive ionic electrolyte. In the case of a hydrogen-oxygen fuel cell with an alkali metal hydroxide electrolyte, the anode reaction is 2H2 + 4OH- + 4H2O + 4e- and the cathode reaction is O2 + 2H2O + 4e- + 4OH- .

The electrons generated at the anode move through an external circuit containing the charge and pass to the cathode. The OH- ions generated at the cathode are conducted by the electrolyte to the anode, where they combine with hydrogen to form water. The fuel cell voltage in this case is about 1.2 V but it decreases as the load increases. The water produced at the anode must be continually withdrawn to prevent it from flooding the stack. Hydrogen-oxygen fuel cells using ion-exchange membranes or phosphoric acid electrolytes were used in the Gemini and Apollo space programs, respectively. Those of phosphoric acid have a limited use in electrical installations that generate energy.

Composition of the most common batteries

• Zinc/ Carbon : they are the so-called common or special flashlight batteries, they contain very little Mercury, less than 0.01%. It is composed of Carbon, Zinc, Manganese Dioxide and Ammonia Chloride. It can contaminate 3,000 liters of water per unit.
• Alkaline ( Manganese): they are more recent than the previous ones. Its active ingredient is an alkaline compound (Potassium Hydroxide). Its duration is 6 times greater than Zinc / Carbon. It is composed of Manganese Dioxide, Potassium Hydroxide, Zinc paste amalgamated with Mercury (total 1%), Carbon or Graphite. A single alkaline battery can contaminate 175,000 liters of water (more than a man can consume in his entire life).
• Mercury:It was the first battery that was built of the micro or button type. Externally they are made of steel and consist of a Mercury Oxide electrode with Graphite powder, the electrolyte is composed of Potassium Hydroxide embedded in a spongy absorbent material and Zinc paste dissolved in Mercury. It contains between 25 and 30% Mercury. This micropile can contaminate 600,000 liters of water.
• Nickel/Cadmium:This battery has the shape of the classic or alkaline battery, but has the advantage that it can be recharged many times. It is made up of laminated Nickel and Cadmium separated by nylon or polypropylene, all spirally wound. Does not contain Mercury. Its residues are dangerous for the environment, mainly due to the presence of Cadmium.

Voltaic pile

A voltaic cell harnesses electricity from a spontaneous chemical reaction to light a light bulb. The strips of zinc and copper, inside solutions of diluted sulfuric acid and copper sulfate, respectively, act as electrodes. The salt bridge (in this case potassium chloride) allows electrons to flow between the buckets without mixing the solutions. When the circuit between the two systems is complete (as shown on the right), the reaction generates an electrical current. Note that the metal in the zinc strip is consumed (oxidation) and the strip disappears. The copper strip grows as the electrons react with the copper sulfate solution to produce additional metal (reduction). If the bulb is replaced by a battery, the reaction will be reversed.

Home stack or Daniell stack

You need a wide-mouthed glass jar, a piece of clean copper tubing, a strip of zinc or metal pencil sharpener, two electrical cords, a glass of vinegar, an LED (light-emitting diode), which is like a very small light bulb, similar to those that illuminate some Christmas trees, an alarm clock or any other device that works with batteries.

The experiment is set up below:

• The glass jar is filled with vinegar.
• With one end of one of the cables, the pencil sharpener or zinc strip is connected and with one end of the other cable, the copper pipe is connected. Both elements are introduced in the bottle with vinegar.
• The free ends of the two cables are connected either to each LED terminal or to the two poles of the device’s battery holder. Connect the polarity, in the case of the watch, correctly. The positive pole with the copper pipe and the negative pole with the pencil sharpener or zinc strip.
• What happens to the LED?

Explanation: Batteries have two electrodes that are usually two metals (in our case the strip of zinc or magnesium from the pencil sharpener and the copper from the pipe) and an electrolyte, which is the substance that allows electric current to be conducted (in our case is the vinegar). The battery that we are manufacturing has a very low current, so we can only run something that requires very little power, as is the case with the LED.