Electrochemistry - General presentation

As a modern science, electrochemistry has provided the materials processing industry with a large number of irreplaceable processes for over a century.

By definition, an electrochemical process for transforming matter differs from a chemical process in that, instead of chemical reagents, electric current is used to achieve the transformation. The term electrolysis, etymologically meaning decomposition by electricity, was introduced to characterize this type of chemical transformation. The operation takes place in an electrolysis cell, in which the substance to be transformed is placed - usually dissolved in a liquid through which current can flow, known as electrolyte - and into which the electrical circuit leading to and from the current flows via two electrodes in contact with the electrolyte.

Avoiding the use of chemical reagents (apart from those used to form the electrolyte) is a priori an undeniable industrial advantage in terms of operating convenience, safety (no need to transport or store chemicals other than those to be transformed and their transformation products), and even economy (insofar as only the consumption of electrical energy, and not the means of transporting it via power lines, needs to be taken into account). On the other hand, electrolytic reactor processes and technology are more complex, which can result in higher investment costs than for chemical reactors, as well as difficulties in running such a reactor continuously in some cases.

Unlike "forced" electrolysis, which consumes electrical energy to produce a chemical transformation, spontaneous electrolytic transformations in a suitably constituted cell produce electrical energy. These cells are sources of electrical current and/or voltage: they are commonly referred to as electric "batteries" or current "accumulators", but today they are known as "electrochemical generators" or even more commonly as electrochemical "batteries" (with a distinction between primary, non-rechargeable batteries, and secondary, rechargeable batteries).