1. General battery structure

A battery consists of two different electrodes immersed in a liquid or solid electrolyte. The electrodes themselves are made up of an electronic collector (metal plate, grid or mesh) which serves as an electronic conductor structure, and to which a reactive material, positive or negative, known as "active material", is applied. The liquid electrolyte consists of an ionizable salt dissolved in a suitable solvent or solvent mixture, to form a solution; when solid, several types of electrolyte are possible: either polymer-based, in which an ionizable salt is dissolved, or mineral compounds with mobile ions in their structure. These different electrolytes have ionic conductivity, which can be used to operate a battery.

For practical reasons, the liquid electrolyte is soaked in a fibrous or porous separator that physically separates the electrodes, thus preventing any...