Lithium-ion batteries are used to power a wide variety of devices, including smartphones, laptops, tablets, and cameras. Despite their advantages, such batteries do not always retain their performance. Scientists described a new strategy for lithium recovery in an article for the journal Nature Energy.
One of the main reasons for the performance degradation of some batteries is that the lithium they contain sometimes becomes inactive, or “dead”. It can cause a drop in capacitance and thermal runaway. This can ultimately shorten battery life and performance.
Researchers at Zhejiang University of Technology in China and Argonne National Laboratory in the United States have developed a strategy for the recovery of inactive lithium in anodes. The new strategy is based on a chemical reaction known as the redox potential of iodine.
Solid electrolyte interfacial (SEI) is the layer that forms on the anode of lithium-ion batteries during the first few charge cycles. The passivation layer plays a critical role in battery performance, stability and safety.
In a typical lithium-ion battery cell with a conventional graphite anode, the solid electrolyte interfacial (SEI) phase usually consists of LiF combined with Li₂CO₃, alkyl carbonate, and other substances. Recent research has shown that, in lithium metal anode batteries, SEI is mainly composed of Li₂O rather than LiF. In these batteries, changing the volume of the Li-coating can compromise the mechanical integrity and passivation role of the Li₂O-based SEI. This, in turn, can lead to the formation of “dead lithium”.
Through their research, the researchers found that it is the loss of Li in SEI and dead lithium particles that are the main causes of the performance degradation often seen in metal lithium batteries. This observation inspired them to develop a method for the reduction of dead lithium using the redox chemical reaction of iodine.
Scientists were able to create a fully charged battery cell with very little lithium in the anode. This cell had a lifespan of 1000 cycles and achieved a Columbian system’s high efficiency of 99.9%.