美国斯坦福大学崔屹团队报道了通过放电状态日历老化实现孤立锂的回复。相关研究成果发表在2024年2月7日出版的《自然》。

可充电锂金属电池具有将最先进的可充电锂离子电池的比能量提高一倍以上的潜力，使锂金属电池成为下一代高能电池技术的主要候选者。然而，与锂离子电池的对手相比，目前的锂金属电池存在快速循环退化，阻碍了其实际应用。容量退化的主要原因是Li与电化学电路断开，形成孤立的Li。日历老化研究表明，在带电状态下静置会促进活性Li与周围电解质的进一步反应。

该文中，研究发现放电状态下的日历老化通过孤立的Li回复提高了容量保持率，这与在充电状态日历老化期间观察到的众所周知的容量下降现象形成了对比。通过使用混合连续-静置循环方案和滴定气相色谱法在Li||Cu半电池和无阳极电池上观察到大于100%的库仑效率，验证了非活性容量回收率。

操作性光学设置进一步证实了过量的孤立Li再活化是容量恢复增加的主要贡献者。这些对通过放电状态静置进行容量恢复的先前未知途径的见解，强调了循环策略对锂金属电池性能的显著影响。

附：英文原文

Title: Recovery of isolated lithium through discharged state calendar ageing

Author: Zhang, Wenbo, Sayavong, Philaphon, Xiao, Xin, Oyakhire, Solomon T., Shuchi, Sanzeeda Baig, Vil, Rafael A., Boyle, David T., Kim, Sang Cheol, Kim, Mun Sek, Holmes, Sarah E., Ye, Yusheng, Li, Donglin, Bent, Stacey F., Cui, Yi

Issue&Volume: 2024-02-07

Abstract: 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 technology1,2,3. However, current Li-metal batteries suffer from fast cycle degradation compared with their Li-ion battery counterparts2,3, preventing their practical adoption. A main contributor to capacity degradation is the disconnection of Li from the electrochemical circuit, forming isolated Li4,5,6,7,8. Calendar ageing studies have shown that resting in the charged state promotes further reaction of active Li with the surrounding electrolyte9,10,11,12. 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.

DOI: 10.1038/s41586-023-06992-8

Source: https://www.nature.com/articles/s41586-023-06992-8