Due to the high demand, it is possible to use a wide range of accumulators and batteries that differ in shape, size, capacity, methods of supplying and discharging the substrates and products of electrode reactions and the materials used in them. The most popular among primary cells are, invariably, zinc-carbon and alkaline batteries. These are primary cells - single use. Another type that is becoming more and more popular are rechargeable batteries, i.e. rechargeable batteries. These include lead-acid, nickel-cadmium, nickel-metal hydride or lithium batteries.
Division according to the mode of operation
Due to the way they work, electrochemical cells are classified into three basic groups:
1. The first type of cells (primary): are characterized by the fact that their operation is not caused by prior charging from an external power source. Its functioning is based only on irreversible electrode reactions taking place in them, the direction of which cannot be changed. As a result of the complete conversion of the reactants, the cell is discharged and becomes useless. Primary cells include the popular alkaline and zinc-carbon batteries.
2. Reversible cells: they work in the opposite way to primary cells - they can be charged. The electric current flowing in this process from an external power source transforms the products obtained as a result of discharging into substrates that are ready for reuse. Electricity is converted into chemical energy. One example of a rechargeable cell is a lead acid battery.
3. Fuel cells: the fuel oxidation process takes place in them. This process takes place with a continuous supply of substrates and discharge of the products of electrode reactions.
Classification by application
1. Small-sized: used in portable electrical and electronic equipment, also in toys and household appliances.
2. Industrial: Intended for industrial, professional or electric vehicle use only.
3. Automotive: used in starting - initiating ignition and for supplying electrical systems in vehicles.
Cell structure and composition
The materials in the battery are elements which, by chemical reactions, generate electrons, as is the case, for example, in the reaction of lead and lead (IV) oxide with sulfuric (VI) acid in lead-acid batteries. The battery contains an electrolyte to ensure ionic conductivity. It is a solution containing salts consisting of ions that are transporters of electric charge and the solvent in which they are dissolved. An example of this is zinc-carbon cells. The electrolyte in them is an aqueous solution of zinc chloride. In turn, in alkaline zinc-manganese cells it is thirty percent potassium hydroxide. In order to stabilize the electrolyte, and thus the above-mentioned reactants, the cells consist of matrices which additionally function as electric charge collectors.
Lead-acid batteries
In lead-acid batteries, the active masses of the reactants are placed on grids made of lead alloys. These grids perform the function of a carrier, i.e. the aforementioned matrix, active mass and electric charge collector. In order to prevent a short circuit between the electrodes of opposite electric sign, the anode reagents are separated from the cathode by a separator. It is made of plastics, such as polyethylene, for example, or of special cellulose derivatives. All the mentioned elements are embedded in the housing together with the lead of the electric contacts and the sealing system.
Recycling and disposal
Due to the rational management of raw materials, some of the materials used in the cells should be recycled. However, since virtually all batteries contain substances that are toxic and can contaminate the environment, it is extremely complicated. In accordance with Directive 2006/66 / on batteries and accumulators and waste batteries and accumulators, and repealing Directive 91/157 / EEC and the Act of April 24, 2009. on batteries and accumulators (Journal of Laws 2009, No. 79, item 666), batteries and accumulators classified as hazardous waste should be subjected to a neutralization process and, if possible, recycling. The most easily recovered battery waste is the steel housing, which can be recycled without any major problems. The remaining substances used in batteries can penetrate into groundwater, soil or atmosphere, leading to ecosystem pollution, which in turn can have disastrous consequences for people. That is why it is so important to dispose of the batteries in specially adapted containers. From there, the services that are responsible for it collect them and take care of their safe disposal.
Bibliography:
1. J. Garche, Encyclopedia of electrochemical power sources, Elsevier 2009.
2. A. Czerwiński, Accumulators, batteries, cells, WKŁ, Warsaw 2005.
3. Directive 2006/66 / on batteries and accumulators and waste batteries and accumulators and repealing Directive 91/157 / EEC.
4. The Act of April 24, 2009. on batteries and accumulators (Journal of Laws of 2009, No. 79, item 666).
5. G. Pistoia, Used battery collection and recycling, Elsevier, 2001.
6. DCR Espinosa, AM Bernardes, JAS Tentório, J. Power Sources 2006, 135, 311.
7. Z. Rogulski, A. Czerwiński, J. Power Sources 2006, 159, No. 1, 454.
