THE IDEA

Chemical energy, on demand

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Anode

The negative electrode on discharge: it gives up electrons

➕

Cathode

The positive electrode on discharge: it takes electrons in

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Electrolyte

Lets ions cross between them, but not electrons

A battery splits one chemical reaction in two, so the electrons have to travel through your device to finish it.

CELL OR BATTERY?

One cell, many cells

Cell One anode, one cathode and electrolyte: the basic unit, such as one AA or one 18650

Battery Strictly, several cells joined together, like a 9 V battery (six small cells) or a car pack

Module A group of cells with wiring and sensors, inside a big pack

Pack Modules, cooling, electronics and a case: the thing in a car or phone

In everyday speech any of these is a "battery", but engineers start from the cell.

TWO KINDS

Use once, or charge again

Primary cells, like alkaline AAs, run their reaction once. Secondary cells, like lithium-ion, can be pushed backwards by a charger hundreds or thousands of times.

Rechargeable means the reaction can be run backwards without wrecking the electrodes.

A SHORT HISTORY

From frogs' legs to phones

🕰️

1800 Alessandro Volta stacks zinc and copper discs with brine-soaked cloth: the first battery

1859 Gaston Planté invents the rechargeable lead-acid battery

1866–1950s Leclanché's zinc–carbon cell, then the alkaline cell (Lewis Urry, 1950s)

1970s–1985 Whittingham, Goodenough and Yoshino work out the lithium-ion pieces

1991 Sony sells the first commercial lithium-ion cell; the 2019 Nobel Prize in Chemistry follows

Lithium-ion is young: it has gone from lab to almost everywhere in about 30 years.

EVERYWHERE

Where batteries work

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📱

Portable

Phones, laptops, earbuds, watches and medical implants

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Transport

Electric cars, buses, bikes and scooters, now the biggest market

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Grid

Storing solar and wind power for the evening and smoothing the grid

The same basic cell, scaled from a coin to a shipping container.

UNIT 1 STUDY COMPLETE

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Ready for the Fab Challenge?

You've seen what a cell is made of, how ions and electrons move when it runs, and where batteries came from.