Electric batteries - General presentation

The battery is a non-rechargeable generator (also known as a primary generator), which produces electrical energy from reactions involving chemical species and electrons; it is an electrochemical generator of electricity. The battery is of particular importance to human activity, in that it enables autonomous use of electrical or electronic means and equipment, to which it supplies electrical energy from a reduced, transportable volume of reactive products.

Despite a great deal of work in the field of electrochemistry (the science that deals generally with phenomena occurring at electrodes), we have to admit that it's impossible to expect progress as great as that we're seeing in electronics (microprocessors and information storage systems in particular). For batteries, we can predict a maximum possible improvement of around a factor of 10 in terms of mass energy, compared with conventional salt and alkaline batteries. The practical mass energies of these saline and alkaline batteries are in the range of 50 to 100 Wh/kg, whereas ideally, for the most advanced batteries conceivable we can only expect, in the best of cases, a little over 1,000 Wh/kg at very low rpm.

In a battery, the energy available is proportional to the quantity of active material introduced (but also depends on the nature of the active material), which means that the greater the autonomy required, the greater the mass and volume. However, knowledge of active materials enables us to choose them carefully in order to achieve the best compactness for a given application. On the other hand, ongoing advances in electronic components are reducing power requirements, and it's this point in particular that makes it possible to reduce the size of the energy source through lower consumption.

Significant progress has been made over the last thirty years, as we shall see in the article. However, the desire for over-concentrated energy (high autonomy for low volume and/or mass) inevitably leads us to generators whose energy density can, in some cases, approach that of dynamite; very "fine" management of the operation of these generators is then necessary to avoid any inconvenience during practical use, possibly under abusive conditions. Releasing the energy stored in large batteries of this type too quickly can present a real danger, which needs to be controlled by developing the technical means necessary to achieve a good level of safety for all users.

As far as the environment is concerned, most batteries contain compounds that are generally not very polluting: zinc, carbon, manganese dioxide, lithium, potash, inert polymers, lithium salts and organic solvents such as esters, ethers, etc., rarely containing atoms or functions that lead to toxic products...