Detecting Li Dendrites in a Two‐Electrode Battery System

The use of high-energy-density Li metal anodes in rechargeable batteries is not possible because of dendrite formation that can potentially result in a battery fire. Although so-called dendrite-free Li metal anodes have been reported in many recent publications, Li dendrite growth is still kinetically favorable and it remains a severe safety concern in mass production. Here, a detection system capable of alerting for Li dendrite formation in a two-electrode battery with no additional electrodes required is reported. When dendrites contact a red phosphorous-coated separator, dendrite growth is revealed by a significant voltage change. This can activate a signal through the battery management system, warning of the presence of Li dendrites and leading to shutdown of the battery before the dendrites become dangerous.