Page 58 - Grasp English C1 (Student Book)

Science | How do batteries work?

Batteries are convenient power supplies. They can However, over time, the chemicals in the anode
be as small as a fingernail or as big as a suitcase, and cathode change, and eventually are unable to
and they give a sure and steady supply of electrical supply electrons. That is why there is a limited supply
energy whenever and wherever we need it. So what of power in batteries.
actually is going on inside this handy, portable The most fundamental aspect of a battery is that
power plant?
the anode and a cathode are always made from
A battery creates energy by converting the two different materials. Both must be conductors
chemicals packed inside it to electrical energy. of electricity, but the anode must be a material
The power unit inside a battery, known as a cell, that “likes” to give up electrons, such as zinc, while
has three main parts. There are two electrodes and the cathode is one that “likes” to receive them,
a chemical between them called an electrolyte, such as copper. A common kind of commercial
packed inside a metal or plastic case. The positive battery is the alkaline battery, so-called because
electrode, also called a cathode, is long and thin, the electrolyte is a concentrated alkaline solution
and can be found inside the battery at the positive (potassium hydroxide). The positive electrode is
terminal, shown by the bump on one end of the based on manganese (IV) oxide, and the negative
battery and marked +. The negative electrode, or electrode is made of zinc. Power is created when the
anode, is in the inner case and the bottom of the manganese (IV) oxide is converted into manganese
battery is, marked -. (III) oxide and hydroxyl ions at the positive electrode.
Meanwhile, at the negative electrode, zinc reacts
When you connect a battery’s two electrodes into a
circuit, the electrolyte and electrodes start buzzing with the hydroxyl ions to release the electrons that
with chemical reactions. Gradually, the chemicals power the circuit.
inside the battery are converted into other Rechargeable batteries work by using another
substances. Ions – atoms with too few or too many power source to change the direction of the flow
electrons – build up at the anode. The electrons of electrons, basically pulling the electrons back
repel each other and “want” to go to a place with and restoring the anode and cathode back to their
fewer electrons – the positive terminal or cathode. original state so that the process can be repeated.
But they can’t travel there within the battery These days, many of these are made with a lithium
because the electrolyte is made of a substance iron phosphate anode which gives up ions to a
which prevents electrons from travelling through it. graphite cathode. However, the system is imperfect,
So they travel to the cathode via the circuit, creating and some electrons are never pulled back towards
a flow of electricity. the anode, meaning that the battery’s ability to
recharge degrades over time.

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