Red Phosphorus Could be Key to Bringing Lithium-Metal Batteries to the Market.
Scientists from Rice University have developed a new technique to safely manufacture lithium-metal batteries.
While lithium-metal anodes can hold approximately 10 times more energy by volume than lithium-ion anodes and charge significantly faster, they commonly form dendrites--needle-like growths that often cause the batteries to fail.
A research team led by Rice chemist James Tour, has made test cells coated with red phosphorus on the separator to keep the anode and cathode electrodes apart. The phosphorus can detect the formation of dendrites.
When a dendrite reaches the red phosphorus-coated separator, the battery's charging voltage changes, tipping off the battery management system that it should stop charging.
To test the new technology, the researchers created a transparent test cell with an electrolyte--the liquid or gel-like material between the electrodes and around the separator that allows the battery to produce a current--which is known to accelerate the aging of the cathode, while encouraging dendrites to grow, enabling the researchers to monitor how this happens.
With an ordinary separator, they found that dendrites contact and penetrate the separator with no change in voltage, leading to battery failure. However, the addition of the red phosphorus layer led to a sharp drop in voltage when the dendrites contacted the separator.
In experiments on test batteries, the red phosphorus layer did not significantly affect the normal performance of the batteries.