1.2 THE PRODUCTION OF ELECTRICITY BATTERIES are devices that produce and store electrical energy obtained by a chemical reaction. Batteries make it possible to use portable appliances or devices everywhere, without the need of plugging them in or using wires and cables. Batteries The components of a battery All batteries consist of one or more cells. A is the basic unit of a battery, and is composed of three fundamental elements, enclosed in a plastic or metal : cell case a positive electrode, called ; cathode a negative electrode, called ; anode an , which can be a liquid or a paste, in which the electrodes are partially immersed. electrolyte How batteries work The electrolyte is a with great conductivity which allows the flow of electrical charge between the cathode and the anode. The two electrodes are generally made of different materials, for example carbon and zinc, and have an end (or ) that extends out of the case. The metal of the anode, reacting with the electrolyte, releases electrons which are caught by the cathode, itself reacting chemically to the electrolyte, too. When the two terminals are connected by a wire, a circuit is formed; the metal electrons will flow through the wire and the current can power any device that is connected to it. When this electrochemical process comes to an end, electrons cannot be produced anymore; as soon as this happens, the battery becomes exhausted and stops powering the devices connected to it. chemical terminal Different types of batteries Batteries can be divided into two big categories: (non-rechargeable), such as: Primary batteries, which are very cheap and employed, for example, in small toys; Zinc-carbon batteries, which provide a good amount of energy, are relatively cheap and are used for motorised toys, shavers, or flashlights; Alkaline and batteries, which have the shape of a small, flat button and are used for watches and . Silver-oxide zinc-air hearing aids (rechargeable), such as: Secondary and batteries, which are typically used in smartphones, tablets and laptops, are quick to recharge and discharge slowly; Lithium-ion (li-ion) lithium-polymer (li-po) batteries (NiMH), which are used, for example, in digital cameras, power drills and in industry; Nickel-metal hydride batteries, which are mainly employed in motor vehicles and for emergency lighting. -acid Lead 1 MORE The lead acid contained in car batteries is a corrosive liquid which is dangerous when it . For this reason, some car manufacturing companies, mainly located in China, are working to produce batteries with a solid electrolyte, to be used along with the traditional liquid electrolyte ones. 1 leaks