Islands of dormant lithium crawl back to their electrodes like worms, replenishing a battery’s capacity and longevity.
Scientists used creep worms to bring “dead” lithium islands back to life, allowing them to reconnect with their electrodes in next-generation lithium metal batteries. This resulted in a roughly 30% increase in battery life.
Researchers from the Department of Energy’s SLAC National Accelerator Laboratory and Stanford University may have discovered a means to rejuvenate rechargeable lithium batteries, possibly extending the range of electric cars and increasing the battery life of next-generation electronic gadgets.
Lithium batteries acquire small islands of inactive lithium that are cut off from the electrodes as they cycle, reducing the battery’s ability to hold charge. However, the researchers realized that by making this “dead” lithium crawl like a worm toward one of the electrodes until it reconnects, they were able to partly reverse the undesired process.
By adding this additional step, they were able to slow down the deterioration of their test battery and extend its life by over 30%.
Stanford postdoctoral scholar Fang Liu, the primary author of a study published Dec. 22 in Nature, stated, “We are currently examining the possible recovery of lost capacity in lithium-ion batteries utilizing an exceptionally rapid draining step.”
A connection has been lost
Rechargeable batteries with less weight, longer lifespan, greater safety, and quicker charging rates than the lithium-ion technology now used in smartphones, laptops, and electric vehicles are the subject of much study. The development of lithium-metal batteries, which can store more energy per volume or weight, is a special priority. In electric automobiles, for example, these next-generation batteries might improve mileage per charge while also taking up less trunk space.
Positively charged lithium ions travel back and forth between the electrodes in both kinds of batteries. Some of the metallic lithium becomes electrochemically inactive over time, resulting in isolated lithium islands that no longer link to the electrodes. This causes capacity loss and is a particular issue with lithium-metal technology and quick charging lithium-ion batteries.
The latest study, on the other hand, showed that the separated lithium could be mobilized and recovered to increase battery life.
Yi Cui, a professor at Stanford and SLAC and investigator with the Stanford Institute for Materials and Energy Study (SIMES), who led the research, stated, “I always thought of isolated lithium as undesirable since it causes batteries to deteriorate and even catch fire.” “However, we’ve figured a how to revive this ‘dead’ lithium by electrically reconnecting it to the negative electrode.”
Not dead, but creeping
Cui’s hypothesis that delivering a voltage to a battery’s cathode and anode may cause an isolated island of lithium to physically travel between the electrodes sparked the research, which his team has now proven with their tests.
A lithium-nickel-manganese-cobalt-oxide (NMC) cathode, a lithium anode, and an isolated lithium island were used to create an optical cell. This test equipment enables them to see what occurs within a battery while it is in use in real time.
They observed that the isolated lithium island wasn’t completely “dead,” but rather reacted to battery activities. When the cell was being charged, the island crawled towards the cathode; when it was being discharged, it crept in the other way.
Cui described it as “like a very sluggish worm that creeps its head forward and draws its tail in to move nanometer by nanometer.” “It transfers in this situation by dissolving on one end and depositing stuff on the other. The lithium worm will finally meet the anode and restore the electrical connection if we keep it going.”
Increasing the length of your life
The findings, which the researchers confirmed with additional test batteries and computer simulations, show how isolated lithium may be retrieved in a real battery by changing the charging technique.
“We discovered that while discharging, we can transport the unattached lithium toward the anode, and that these movements are quicker at larger currents,” Liu added. “So, soon after the battery charges, we added a quick, high-current discharging phase, which transported the separated lithium far enough to reunite it with the anode. This reactivates the lithium, allowing it to participate in the battery’s life.”
“Our results have far-reaching implications for the design and development of more durable lithium-metal batteries,” she said.
Battery Materials Research (BMR), Battery 500 Consortium, and eXtreme Fast Charge Cell Evaluation of Li-ion Batteries (XCEL) initiatives were supported by the DOE Office of Energy Efficiency and Renewable Energy, Office of Vehicle Technologies.