Electrical accumulator

The electrical accumulator — a chemical current source of reusable action which main specifics are in reversibility of internal chemical processes that provides its repeated cyclic use (through a charge discharge) for accumulation of energy and self-contained power supply of different electrotechnical devices and the equipment.

Operation principle

The operation principle of the accumulator is based on reversibility of chemical reaction. The operability of the accumulator can be recovered by a charge, i.e. transmission of electric current in the direction, the return to the direction of current at discharge. Several accumulators united in one electrical circuit make the rechargeable battery.

Characteristics

The greatest possible useful charge of the accumulator is called the charging capacity, or just capacity. Capacity of the accumulator is the charge given completely by the charged accumulator at discharge up to the smallest allowable voltage. In the SI system the capacity of accumulators is measured in a Coulomb, in practice stand-alone unit — ampere-hour is often used. 1 Ach = 3600 C. Less often on accumulators power capacity — the energy given completely by the charged accumulator at discharge up to the smallest allowable voltage is specified. In the SI system it is measured in joules, in practice stand-alone unit — watt-hour is sometimes used. 1 Vtch = 3600 J.

Electric and utilization properties of the accumulator depend on material of electrodes and composition of electrolyte.

In process of exhaustion of chemical energy tension and current fall, the accumulator ceases to operate. It is possible to charge the accumulator (the battery of accumulators) from any DC power source with big tension at restriction of current. The charge current (in amperes) in 1/10 rated capacities of the accumulator is considered standard (in amperchasa). Many types of accumulators have different restrictions which need to be considered at charging and the subsequent operation, for example NiMH-accumulators are sensitive to a recharge, lithium — to redischarge, tension and temperature. NiCd-and NiMH-accumulators have the so-called memory effect consisting in decrease in capacity in a case when charging is performed at not the completely discharged accumulator. Also these types of accumulators have a noticeable self-discharge, i.e. they gradually lose a charge, even without being connected to loading. Drop recharge can be applied to fight against this effect.

Types of accumulators

• Iron-air accumulator
• Iron-nickel accumulator
• Lanthanum-fluoride accumulator
• Lithium - the iron and sulphidic accumulator
• Lithium - the iron and phosphatic accumulator
• Li-Ion
• Lithium-air accumulator (lithium-air, Li-air)
• Lithium-pol cell
• Lities-fluorine accumulator
• Lities-chlorine accumulator
• Lities-sulfur accumulator
• Sodium-nickel-chloride accumulator
• Sodium-sulfur accumulator
• NiCd
• Nickel-metal-hydride accumulator (NiMH)
• Nickel-zinc accumulator
• Lead-hydrogen accumulator
• Lead acid accumulator
• Silver cadmium accumulator
• Silver zinc accumulator
• Zinc-bromine accumulator
• Zinc-air accumulator
• Zinc-chlorine accumulator
• Nickel-hydrogen accumulator

New technologies

The electric battery from an electric eel

Researchers from the Michigan and Fribourg universities report in 2017 in the article in Nature that they managed to design the current source working by the same principle as electric body of an electric eel. At eels electric bodies consist of a set of cages through which there passes the flow of positive ions of potassium and sodium; as a result each cage has a positively charged pole (directed to the head of fish) and the negatively charged pole (directed to a tail). In each cage voltage about 150 millivolts, but all together, laid one after another, like batteries is created, they generate hundreds and hundreds of volts^[1].

Something similar was made by Michael Mayer and his colleagues. Instead of living cells they used the cells filled with the hydrogel-polymer holding water. Hydrogel holds either pure water, or water with the salts which are breaking up in solution to positive and negative ions in cells. Walls of cells are made of a semipermeable membrane which passes these ions there and back. When cells adjoin with each other, ions begin to move to them in different directions, and there is a voltage.

The electric cells filled with hydrogels with water and salts. photo: Thomas B. H. Schroeder, Anirvan Guha.)

Hydrogels in cells differ in own structure and in composition of solutions which they hold; if to compare to electric cages of eels, then to one cage there correspond four cells (on a photo they are designated in different flowers). One block from four cells gives from 130 to 185 millivolts, in an experiment it was succeeded to make big "battery" of several hundred cells which in the amount gave 110 volts.

But the main cunning here in how the battery was forced to work. Artificial electric cages in one case distributed between two elastic polymeric sheets: imposing sheets at each other, cells could be combined in the necessary order (as on a photo 2). In other option all of them were placed on the same sheet, but so that they could be combined, having put the sheet several times (as on a photo 3). When both sheets squeezed or when squeezed the put sheet, there was a contact between all cells at once – and all cells worked at the same time.

It is supposed that similar batteries can be used for a power supply of different biomedical devices, and, moreover, that such batteries will be able to use natural the state of charge of some internal fabrics and bodies. More flexible and them it is simpler to Ugrepodobnye to make accumulators biocompatible that they did not irritate living cells. A problem, however, that so far tension which they give is not really big though inventors believe that in the near future they will manage to force their batteries to generate current of the same tension, as these electric eels.

Battery spray

Researchers from Rice University in Houston (Rice University) provided in 2016 a prototype of the battery which is put as spray that can cardinally change approach to design of portable electronic devices.

Such battery is loaded and has the same electric characteristics, as Li-ion batteries which are built in all mobile gadgets, but the battery can be applied practically on any surface using the normal sprayer for paint, declared Neelam Singh, the graduate of the university who heads a team of researchers on an extent more than years.

Today Li-ion batteries at all variety of devices where they are used, look approximately equally: these are removable rectangular blocks with electrodes on one end. As these batteries do not bend, they are seriously limited designers of portable devices in the choice of new form factors, especially curved, but now the situation can change. "Batteries of new type will be able to be manufactured direct in the form of that space which remains free in the device", - noted Sing.

The battery is sprayed in the form of five layers: some of which work as the cathode, others as the anode, is also present the polymeric separator. Scientists said that they had problems with selection of paint which initially was not moisture-proof and could be defended, but adding of polymers and introduction of the procedure of heat treatment resolved this issue.

As a result the battery of new type can be evaporated on plastic, metal and even not ceramics. During the experiment the team of scientists raised dust such battery on nine ceramic tiles which is usually used for finishing of bathrooms. These tiles integrated in the rechargeable battery, and their power lasted for 6 business hours of LEDs which they laid out the name of the university - "Rice".

At the moment the command was engaged in patenting of the invention. According to Sing, further work will be carried out over that even не-профессиналы could make such batteries in house conditions from available materials. Besides, developers to hope to interest in the of prototypes of producers of electronics as they consider that production of such batteries at the modern level of development of the industry can be arranged very quickly.

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