美国斯坦福大学Cui, Yi团队报道了电池运行期间“”死锂“”的动态空间演变。相关研究成果于2021年12月22日发表在《自然》。
下一代储能系统的需求不断增长需要开发高性能锂电池。不幸的是，由于固体电解质界面和“死锂”（i-Li）的不断生成，当前的锂阳极表现出快速的容量衰减和较短的循环寿命。在大多数试验条件下，锂树枝晶非均匀溶解过程中形成的i-Li会导致锂电池的大量容量损失。由于i-Li失去与集电器的电气连接，因此在电池中，被认为是电化学不活跃或“死”的。
与这一普遍接受的假设相反，研究人员认为，由于i-Li对电解液中的电场具有动态极化，因此i-Li对电池操作具有高度响应性。锂的沉积和溶解同时发生在锂离子电池的两端，导致锂离子电池在充电（放电）过程中向阴极（阳极）方向发展。模拟结果表明，i-Li的生长速率主要受其长度、取向和外加电流密度的影响。此外，研究人员成功地证明了i-Li在Cu–Li电池中的回收率>100%库仑效率，并制备了具有延长循环寿命的LiNi0.5Mn0.3Co0.2O2（NMC）-锂全电池。
附：英文原文
Title: Dynamic spatial progression of isolated lithium during battery operations
Author: 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
Issue&Volume: 2021-12-22
Abstract: The increasing demand for next-generation energy storage systems necessitates the development of high-performance lithium batteries1,2,3. Unfortunately, current Li anodes exhibit rapid capacity decay and a short cycle life4,5,6, owing to the continuous generation of solid electrolyte interface7,8 and isolated Li (i-Li)9,10,11. The formation of i-Li during the nonuniform dissolution of Li dendrites12 leads to a substantial capacity loss in lithium batteries under most testing conditions13. Because i-Li loses electrical connection with the current collector, it has been considered electrochemically inactive or ‘dead’ in batteries14,15. 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 LiNi0.5Mn0.3Co0.2O2 (NMC)–Li full cells with extended cycle life.
DOI: 10.1038/s41586-021-04168-w
Source: https://www.nature.com/articles/s41586-021-04168-w