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Key facts

Batteries are used to store chemical energy. Placing a battery in a circuit allows this chemical energy to generate electricity which can power device like mobile phones, TV remotes and even cars.

Generally, batteries only store small amounts of energy. More and more mobile devices like tablets, phones and laptops use rechargeable batteries.

Batteries are a non-renewable form of energy but when rechargeable batteries store energy from renewable energy sources they can help reduce our use of fossil fuels and cut down carbon dioxide and greenhouse gas production.

A selection of batteries

Batteries and their impact

Find out why batteries may have a key role to play in making our energy supply greener.

What is a battery?

Diagram illustrating a simple cell

Usually a battery is made up of cells. The cell is what converts the chemical energy into electrical energy.

A simple cell contains two different metals (electrodes) separated by a liquid or paste called an electrolyte. When the metals are connected by wires an electrical circuit is completed.

One metal is more reactive than the other. Negatively-charged electrons flow from the more reactive metal through the wires to the less reactive metal. In the graphic above, electrons flow from the magnesium to the copper. Positively-charged ions flow from the copper through the electrolyte to the magnesium.

Electricity will continue to flow until there is no more magnesium left to react.

How batteries work

Batteries are stores of chemical energy. When being used in portable electrical devices like your phone, they transfer chemical energy into electrical energy.

When a battery stops working, it is because the chemicals in it have been used up. Some batteries are rechargeable and when they are being recharged, electrical energy (from the mains) is transferred back to chemical energy (in the battery) to be used again.

Case study: lemon cells

An experiment to create a simple cell out of a lemon
Image caption,
An experiment to create a simple cell out of a lemon.

You could make your own lemon battery. Put a copper penny (one and two pence pieces work) into the lemon, this will form the positive electrode, and a galvanized zinc nail for the negative electrode.

These can then be attached to a light bulb or buzzer using alligator clips and wires. Three or four lemons are likely to be required to light the bulb. This experiment can be used to explain how a battery works. A battery requires three thingstwo electrodes and an electrolyte.

The electrodes must be different materials with different chemical reactivity to allow electrons to move round the circuit. This movement requires an electrolyte to complete the circuit, provided by the acidic liquid in the lemon. The flow of electricity can be measured using a voltmeter.

Creating different voltages

Different metals produce different voltages in a cell. You can list the different metals in order of the size of the voltage that is made when connected to the same metal. This list is called the electrochemical series. This list is very important for chemists and people who are interested in the reactions of metals.

Other factors affect the size of voltage produced in a cell such as:

  • the type of electrolyte.
  • the concentration of electrolyte.
  • the distance between electrodes.
  • the surface area of the electrodes.

Sustainability

To develop a sustainable future you need to think about meeting today's needs and protecting the聽environment听补苍诲听resources聽for the future.

Although very useful, batteries are not a renewable source of energy. They are made from non-renewable materials such as lithium (used to make rechargeable batteries).

Batteries can also be difficult to recycle as they contain toxic substances.

There is work being done to try and make batteries more sustainable. Scientists are trying to make batteries out of chemicals such as sodium that are more common and more sustainable.

Lithium extraction, Bolivia. Lithium is an essential compound used in the manufacture of rechargeable batteries
Image caption,
Lithium extraction, Bolivia. Lithium is an essential compound used in the manufacture of rechargeable batteries.

Advantages and disadvantages of batteries

Advantages

  • They are portable and have changed how we live and work.
  • Some batteries are a clean method of generating electricity for transport as they do not produce carbon dioxide.
  • Batteries are used to store electricity that is surplus to requirements. This means that energy is not being wasted.

Disadvantages

  • They are expensive to use.
  • They (usually) store only a small amount of energy.
  • They contain finite resources such as precious metals. This is why it is essential that we recycle batteries.
  • Mining precious metals and making batteries produce toxic waste which is dangerous to the environment.
  • They can leak corrosive chemicals (from the electrolyte).

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