WHAT IS AN INTERNAL SHORT CIRCUIT?

An internal short circuit inside a battery occurs whenever there is direct electrical contact between the two electrodes (anode and cathode) within the battery that is not caused by the provided electrolyte. Instead, an unwanted and direct connection occurs that bypasses the normal current flow and leads to a rapid and uncontrolled discharge of the battery.

How does this happen?

The causes of an internal short circuit can be manifold:

1. Mechanical damage: If the battery is physically damaged, the partitions that insulate the electrodes from each other can break, causing the short circuit.
2. Manufacturing defects: Manufacturing defects, such as contamination or material defects, can cause the electrodes to accidentally come into contact with each other.
3. Ageing: Over time, the material of the battery can degrade, causing the separating layers between the electrodes to become thinner or even permeable.
4. Overheating: Excessive heat can damage the materials inside the battery and also result in an internal short circuit.

Consequences of an internal short circuit

An internal short circuit can have serious consequences:

• Rapid discharge: The battery discharges very quickly, which can lead to overheating.
• Risk of fire or explosion: With lithium-ion batteries in particular, an internal short circuit can be dangerous due to the rapid development of heat and can potentially lead to thermal propagation and consequently to a fire or explosion.
• Irreparable damage: The short circuit usually results in the battery being irreparably damaged and can no longer be used.

An internal short circuit is a serious problem and can occur in all battery types, although lithium-ion batteries can be particularly susceptible and dangerous due to their high energy density.