Recovery of isolated lithium through discharged state calendar ageing

• Published in: Nature (London) Vol. 626; no. 7998; pp. 306 - 312
• Main Authors: Zhang, Wenbo, Sayavong, Philaphon, Xiao, Xin, Oyakhire, Solomon T, Shuchi, Sanzeeda Baig, Vilá, Rafael A, Boyle, David T, Kim, Sang Cheol, Kim, Mun Sek, Holmes, Sarah E, Ye, Yusheng, Li, Donglin, Bent, Stacey F, Cui, Yi
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 08.02.2024
• Subjects: Aging; Aging (metallurgy); Calendars; Charging; Chromatography; Circuits; Copper; Corrosion; Cycles; Degradation; Discharge; Electrochemistry; Electrodes; Electrolytes; Electrolytic cells; Gas chromatography; Lithium; Lithium batteries; Lithium-ion batteries; Metals; Protocol; Rechargeable batteries; Recovery; Specific energy; Titration
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/s41586-023-06992-8

Rechargeable Li-metal batteries have the potential to more than double the specific energy of the state-of-the-art rechargeable Li-ion batteries, making Li-metal batteries a prime candidate for next-generation high-energy battery technology . However, current Li-metal batteries suffer from fast cycle degradation compared with their Li-ion battery counterparts , preventing their practical adoption. A main contributor to capacity degradation is the disconnection of Li from the electrochemical circuit, forming isolated Li . Calendar ageing studies have shown that resting in the charged state promotes further reaction of active Li with the surrounding electrolyte . Here we discover that calendar ageing in the discharged state improves capacity retention through isolated Li recovery, which is in contrast with the well-known phenomenon of capacity degradation observed during the charged state calendar ageing. Inactive capacity recovery is verified through observation of Coulombic efficiency greater than 100% on both Li||Cu half-cells and anode-free cells using a hybrid continuous-resting cycling protocol and with titration gas chromatography. An operando optical setup further confirms excess isolated Li reactivation as the predominant contributor to the increased capacity recovery. These insights into a previously unknown pathway for capacity recovery through discharged state resting emphasize the marked impact of cycling strategies on Li-metal battery performance.