The strange science of why old batteries leak

The strange science of why old batteries leak

The chemicals inside batteries which produce electricity also produce hydrogen which can cause the seal to break.

Photo credit: Getty Images

Published: September 12, 2023 at 4:46 pm

Batteries generate electricity by chemical reactions that move electrons from one terminal to the other. Ordinary alkaline batteries use a potassium hydroxide gel as the conductive electrolyte, and the reactions in the gel generate a small amount of hydrogen gas.

Since the battery is sealed, the pressure in the cell gradually builds and eventually causes tiny ruptures along the seams of the metal casing. The potassium hydroxide reacts with CO2 in the air to form a harmless crust of potassium carbonate, but the potassium hydroxide itself is caustic and can cause skin irritation. Take your leaking batteries to the recycling centre in a plastic bag. 

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Asked by: Lucinda Cox, Sussex

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