Researchers at the Department of Energy’s SLAC National Accelerator Laboratory and Stanford University believe they have discovered a means to revive rechargeable lithium batteries, which might increase the range of electric cars and battery life in next-generation electronic devices.
As lithium batteries cycle, small islands of inactive lithium form between the electrodes, reducing the battery’s ability to hold charge. However, the researchers found that they could make this “dead” lithium creep like a worm toward one of the electrodes until it reconnects, thereby partially reversing the undesirable process.
“We are now exploring the potential recovery of lost capacity in lithium-ion batteries using an extremely fast discharging step,” said Stanford postdoctoral fellow Fang Liu, the lead author of a study published December 22nd in Nature.
An animation shows how charging and discharging a lithium battery test cell causes an island of “dead,” or detached, lithium metal to creep back and forth between the electrodes. The movement of lithium ions back and forth through the electrolyte creates areas of negative (blue) and positive (red) charge at the ends of the island, which swap places as the battery charges and discharges. Lithium metal accumulates at the negative end of the island and dissolves at the positive end; this continual growth and dissolution causes the back-and-forth movement seen here. SLAC and Stanford researchers discovered that adding a brief, high-current discharging step right after charging the battery nudges the island to grow in the direction of the anode, or negative electrode. Reconnecting with the anode brings the island’s dead lithium back to life and increases the battery’s lifetime by nearly 30%. Credit: Greg Stewart/SLAC National Accelerator Laboratory.