When the cell becomes a stalactite cave: Electric car dictionary: Dendrites


Electric car dictionary: dendrites

Status: December 19, 2021

When the cell becomes a stalactite cave: Electric car dictionary: Dendrites-cave

E-car batteries are generally considered to be safe – but they are not entirely without risk

Source: Volvo

E-car batteries very rarely catch fire. In many cases, however, dendrites are the cause.

S.P-X / Cologne. They are the greatest threat to battery safety in electric cars: dendrites. The proliferating deposits can cause short circuits within the battery cells. In extreme cases, there is a risk of fire or explosion.

Lithium-ion batteries are relatively safe, even if problems arise time and again in everyday life given their now extreme number. In some cases, the so-called dendrites are likely to play a role. These stalactite-like growths on the negative electrode, the anode, can arise when the battery is being charged. Actually, the lithium particles floating in the electrolyte should be deposited evenly and in a disciplined manner in the graphite layer of the anode. They do not do this in the event of cell damage or malfunction. Instead, they build small turrets on the surface that can grow over time and eventually reach the cathode. If both electrodes are connected by such a conductive metal arm, there is a short circuit, heat and, in the worst case, fire.

Because the consequences of dendrite formation can be very unpleasant, science and industry are working to better understand the electrochemical processes that lead to growth. And develop solutions. This could consist in an impenetrable membrane between the electrodes, in the exchange of lithium for a less prolific metal or in the switch to solid-state batteries with solid electrolytes. According to the current state of research, charging using current pulses instead of a steady current could also prevent dendrite formation.

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