According to a recent Stanford University study, lithium-metal batteries that are at rest may be able to reverse degradation, which could eventually make them suitable for use in electric vehicles (EVs). Lithium-metal batteries offer higher energy density and reduced weight compared to lithium-ion batteries, which are extensively utilized in EVs today. Despite these benefits, the practicality of lithium-metal batteries is limited due to their rapid degradation after only a few charge cycles. However, researchers found that allowing the batteries to rest without any current running through them can initiate a healing process, reducing the degradation.
Anode composition is the primary distinction between lithium-metal and lithium-ion batteries. Lithium-metal batteries employ electroplated lithium metal as opposed to graphite for its anode, which enables twice as much energy storage in the same amount of area as lithium-ion batteries. A car with lithium-metal batteries could potentially travel 600 miles on a single charge, as opposed to 300 miles for a vehicle with lithium-ion batteries of the same size.
The degradation in lithium-metal batteries is due to the formation of a solid electrolyte interphase (SEI) matrix, which traps lithium ions and prevents them from participating in electrochemical reactions, rendering them “dead.” However, researchers found that when these batteries are completely discharged and rested for just one hour, some of the SEI matrix surrounding the dead lithium dissolves away. This allows the dead lithium to reconnect with the anode when the battery is recharged, effectively reversing the degradation.
While it may not be practical to rest a car’s battery for several hours, battery management software can be adjusted to allow some cells to be fully discharged and rested while others are used. This resting procedure could be scheduled when the vehicle is not in use for an extended period.
Further research is needed to optimize lithium-metal batteries and their resting procedure for road car usage. However, researchers believe that with this technique, these batteries could significantly increase EV cycle life, making them a promising option for future EVs.