Dynamic spatial progression of isolated lithium during battery operations

• Published in: Nature (London) 2021-12, Vol.600 (7890), p.659-663
• Main Authors: Liu, Fang, Xu, Rong, Wu, Yecun, Boyle, David Thomas, Yang, Ankun, Xu, Jinwei, Zhu, Yangying, Ye, Yusheng, Yu, Zhiao, Zhang, Zewen, Xiao, Xin, Huang, Wenxiao, Wang, Hansen, Chen, Hao, Cui, Yi
• Format: Article
• Language: English
• Subjects: 639/301; 639/4077; 639/925; Anodes; Batteries; Chemical properties; Dissolution; Electric fields; Electric properties; Electrode polarization; Electrodes; Electrolytes; Electrolytic cells; ENERGY STORAGE; Equilibrium; Humanities and Social Sciences; Lithium; Lithium batteries; Materials; Morphology; multidisciplinary; Science; Science (multidisciplinary); Solid electrolytes; Storage systems
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/s41586-021-04168-w

The increasing demand for next-generation energy storage systems necessitates the development of high-performance lithium batteries 1 – 3 . Unfortunately, current Li anodes exhibit rapid capacity decay and a short cycle life 4 – 6 , owing to the continuous generation of solid electrolyte interface 7 , 8 and isolated Li (i-Li) 9 – 11 . The formation of i-Li during the nonuniform dissolution of Li dendrites 12 leads to a substantial capacity loss in lithium batteries under most testing conditions 13 . Because i-Li loses electrical connection with the current collector, it has been considered electrochemically inactive or ‘dead’ in batteries 14 , 15 . Contradicting this commonly accepted presumption, here we show that i-Li is highly responsive to battery operations, owing to its dynamic polarization to the electric field in the electrolyte. Simultaneous Li deposition and dissolution occurs on two ends of the i-Li, leading to its spatial progression toward the cathode (anode) during charge (discharge). Revealed by our simulation results, the progression rate of i-Li is mainly affected by its length, orientation and the applied current density. Moreover, we successfully demonstrate the recovery of i-Li in Cu–Li cells with >100% Coulombic efficiency and realize LiNi 0.5 Mn 0.3 Co 0.2 O 2 (NMC)–Li full cells with extended cycle life. An electrochemical process stimulates the progression toward the electrode of isolated or ‘dead’ lithium in a battery, recovering its electrical connection, and the effect is demonstrated by increased cycle life.