Researchers at Rice University have developed a method to detect dendrite growth in rechargeable lithium batteries and thereby cut off the charge current and avoid a hazardous situation.

Batteries using lithium-metal anodes can be charged much faster and hold about 10 times more energy by volume than batteries using standard lithium-ion anodes; During charging the lithium-infused anodes grow dendrites that will eventually form a devastating short circuit in the cell causing it to heat up and ignite. The researchers have discovered that if an intermediate layer of red phosphorus is introduced in the cell construction, it is the first layer to get penetrated as the dendrites form and the piercing can be detected electrically.

As soon as the layer is damaged, the charge current spikes, which is an indicator of imminent danger. The BMS (battery management system), is designed to recognise this change in charge current and will terminate the charging process before an internal short-circuit develops. The film of red phosphorus has no significant impact on the battery’s electrical properties.

The research team led by James Mitchell built a transparent lithium-metal cell to demonstrate the growth of dendrites. The team used it to show the link between charge current change and penetration of the phosphor layer.
According to the team it will be a simple process to apply the phosphor film during cell manufacture.