LEAD-ACID

Old, heavy and everywhere

Lead and lead dioxide plates sit in sulfuric acid; both turn into lead sulfate as the cell discharges. About 2 V per cell, six cells for a 12 V car battery. Heavy, at about 30–40 Wh/kg, but cheap and able to give hundreds of amps to a starter motor.

Invented in 1859 and still the cheapest way to start a car.

ALKALINE

The single-use workhorse

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Anode Zinc powder

Cathode Manganese dioxide

Electrolyte Potassium hydroxide (the "alkaline")

Voltage 1.5 V, sloping down as it empties

Cheap, long shelf life, made to be used once.

NICKEL CELLS

NiCd, then NiMH

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☠️

NiCd

Rugged and powerful, but cadmium is toxic and now restricted

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NiMH

A hydrogen-storing alloy instead of cadmium: more capacity, 1.2 V

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Hybrids

NiMH powered early hybrid cars like the first Toyota Prius

NiMH is still the standard rechargeable AA.

NAME IT

Name that chemistry

Voltage, materials and weight give each chemistry away.

Each chemistry still has a job it does best.

SIDE BY SIDE

How they compare

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Lead-acid 2.0 V · about 30–40 Wh/kg · cheapest, very recyclable

NiMH 1.2 V · about 60–120 Wh/kg · safe, tolerant

Alkaline (primary) 1.5 V · single use · long shelf life

Lithium-ion 3.2–3.7 V · about 150–300 Wh/kg · highest energy

Lithium-ion won on voltage and weight, not on price.

UNIT 10 STUDY COMPLETE

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Ready for the Fab Challenge?

You've met the chemistries that came before lithium-ion and seen why they are still around.