The term battery comes from the early days of electricity, when several elements (metal disks or cells) were grouped together to increase the current supplied by the device. In some cases they were arranged one on top of the other, they were piled up; and in other cases they were placed one next to the other, in a battery.
In English, a single term, battery, is used to designate all these devices. On the contrary, in Spain and other countries, the terms battery and accumulator are used for rechargeable lead-acid devices (mainly) and “pila” (single use battery) for the others, whether they are rechargeable or not (alkaline).
In some Spanish-speaking countries, on the other hand, the English procedure is followed and the word battery is used for all types. In these countries, the term accumulator is applied to electrical capacitors or other accumulation devices.
Primary and secondary cells
In countries that do not make the above-mentioned difference, the electricity supply elements are classified into two categories:
Primary cells, which have previously been called non-rechargeable batteries, transform chemical energy into electrical energy, irreversibly (within the limits of practice). When the initial amount of reagents present in the battery is exhausted, the energy cannot be easily restored or returned to the electrochemical cell by electrical means.
Primary cells (single-use or “throwaway”) are used once and discarded; the electrode materials are irreversibly changed during discharge. The most common examples are the non-rechargeable alkaline battery used for flashlights and a multitude of portable devices.
The secondary cells, what have previously been called batteries or rechargeable batteries, which can be recharged without more than reversing the chemical reactions inside them by supplying the cell with electrical energy until the restoration of its original composition.
Secondary (rechargeable) cells can be discharged and recharged several times, because the original composition of the electrodes can be restored by the reverse current. Examples include lead-acid batteries used in vehicles, lithium-ion batteries used in portable electronic devices such as cell phones, tablets and computers, and rechargeable Ni-HM batteries used as an alternative or replacement for alkaline batteries in portable electronic devices that use them, such as digital cameras, toys, portable radios, radio recorders, flashlights, MP3 players and Minidisc players, among others.