Stanford Researchers Bring “Dead” Lithium Back To Life
One of the key problems with lithium-ion batteries is that, over time, they do lose some of their battery life. This is why recycling them is so important. But what if there was a way to bring them back to life? And by this, I mean make them as good as new without recycling them. What if you could not only bring them back to life but extend the battery’s life by up to 30%?
Researchers at Stanford University along with the Department of Energy’s SLAC National Accelerator Laboratory may have done just that. No, this isn’t the beginning of a zombie horror apocalypse type of story, but it is a potentially revolutionary breakthrough.
Green Car Congress reports that the researchers might have found a way to bring rechargeable lithium batteries back to life with an increased boost to the range of battery life for both EVs and next-generation electronic devices. The study on the work has been published in Nature.
As lithium batteries cycle, they collect these little pockets or islands of inactive lithium that are cut off from the electrodes. This decreases the battery’s capacity to store charge. Think of this as dead lithium. The research team found that they could make the dead lithium practically creep forward like a worm toward one of the electrodes until it reconnects. Kind of like creating a zombie, but without all of the blood and gore, yet with the added benefit of partially reversing an unwanted process.
When an island of dead lithium metal travels to the anode of a battery and reconnects, it is brought back to life and adds electrons to the battery’s current flow and lithium ions for storing charge. Researchers were able to get the island to move by adding lithium metal at one end and dissolving it at the other end, essentially driving the island’s growth in the direction of the anode by adding a short, high-current discharging step just after the battery charges. They found that adding this extra step slowed the degradation of their test battery while increasing its lifetime by almost 30%.
The study was inspired by Professor Yi Cui at Stanford and SLAC. Cui is also an investigator with the Stanford Institute for Materials and Energy Research (SIMES). Cui speculated that applying a voltage to a battery’s cathode and anode could create an isolated island of lithium physically move between the electrodes. This process has now been confirmed by his team.
The team created an optical cell with a lithium-nickel-manganese-cobalt-oxide cathode, a lithium anode, and an isolated lithium island in between. The test device enabled them to track in real-time what happens inside a battery when it is in use. They found that the isolated lithium wasn’t really dead, and that it responded to battery operations. When the cell is being charged, the island slowly moved toward the cathode. When discharging, it crept away in the opposite direction. Cui described it as a slow worm inching by nanometer.
“It’s like a very slow worm that inches its head forward and pulls its tail in to move nanometer by nanometer. In this case, it transports by dissolving away on one end and depositing material to the other end. If we can keep the lithium worm moving, it will eventually touch the anode and reestablish the electrical connection.”
The team validated the results with other test batteries and also with computer simulations. What they show is how isolated lithium in an actual battery can be recovered by modifying the charging protocol. Fang Liu, a postdoctoral fellow at Stanford and lead author, said:
“We found that we can move the detached lithium toward the anode during discharging, and these motions are faster under higher currents. So we added a fast, high-current discharging step right after the battery charges, which moved the isolated lithium far enough to reconnect it with the anode. This reactivates the lithium so it can participate in the life of the battery. Our findings also have wide implications for the design and development of more robust lithium-metal batteries.”
Hopefully, we will see more on this research and how it can be applied to all of our battery-powered devices and vehicles in the coming years.
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