About overcharging

Overcharge is one of the most difficult safety tests for lithium batteries, so it is necessary to understand the mechanism of overcharge.

When a battery is overcharged, it produces heat and gas.?Heat includes ohmic heat and heat produced by side reactions, of which ohmic heat is dominant.?The first side reaction caused by overcharging is that excessive lithium is embedded into the negative electrode, and lithium dendrites will grow on the surface of the negative electrode.?Second, too much lithium is released from the positive pole, causing the structure to collapse and release oxygen.?Oxygen accelerates the breakdown of the electrolyte, increasing the pressure in the battery until the safety valve opens.?The contact of the active substance with the air produces further heat.

Studies have shown that reducing the amount of electrolyte can significantly reduce heat and gas generation during overcharging.?Other studies have shown that batteries can explode when overcharged without splints or when the safety valve doesn't open properly.?A slight overcharge does not cause thermal runaway, but can lead to a reduction in capacity.