Operando Observations of SEI Film Evolution by Mass-Sensitive Scanning Transmission Electron Microscopy
Operando Observations of SEI Film Evolution by Mass-Sensitive Scanning Transmission Electron Microscopy
复制标题
通过质量敏感扫描透射电子显微镜对 SEI 膜演化的操作观察
DOI：
10.1002/aenm.201902675
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发表时间：
2019-10-28
影响因子：
27.8
通讯作者：
Chen, Mingwei
中科院分区：
文献类型：
--
作者：
Hou, Chen;Han, Jiuhui;Chen, Mingwei
在锂离子电池和锂金属电池中，作为钝化层在阳极表面上自发形成的固体电解质界面（SEI）在锂的溶解和沉积中起关键作用。SEI膜的形成动力学和失效是决定锂离子电池和锂金属电池的安全性、功率容量和循环寿命的关键因素。由于SEI膜随阳极体积和界面的变化而变化，因此SEI动力学的实验研究具有技术挑战性。这里operando观察报告的SEI的形成，生长，并在高电流密度的故障，通过利用质量敏感的Cs校正的扫描透射电子显微镜。亚纳米尺度的观察揭示了SEI膜的双层混合结构，并证明了在SEI厚度超过电子隧穿机制之后的自由基辅助SEI生长。SEI膜的失效与无机层在与破裂的SEI膜中的电解质直接接触时的快速溶解有关。SEI膜中裂纹的产生是由电极在脱锂过程中的非均匀体积变化引起的。这些微观见解对于理解SEI动力学和开发具有坚固SEI膜形成的高性能阳极具有重要意义。
The solid electrolyte interphase (SEI) spontaneously formed on anode surfaces as a passivation layer plays a critical role in the lithium dissolution and deposition upon discharge/charge in lithium ion batteries and lithium-metal batteries. The formation kinetics and failure of the SEI films are the key factors determining the safety, power capability, and cycle life of lithium ion and lithium-metal batteries. Since SEI films evolve with the volumetric and interfacial changes of anodes, it is technically challenging in experimental study of SEI kinetics. Here operando observations are reported of SEI formation, growth, and failure at a high current density by utilizing a mass-sensitive Cs-corrected scanning transmission electron microscopy. The sub-nano-scale observations reveal a bilayer hybrid structure of SEI films and demonstrate the radical assisted SEI growth after the SEI thickness beyond the electron tunneling regime. The failure of SEI films is associated with rapid dissolution of inorganic layers when they directly contact with the electrolyte in broken SEI films. The initiation of cracks in SEI films is caused by heterogeneous volume changes of the electrodes during delithiation. These microscopic insights have important implications in understanding SEI kinetics and in developing high-performance anodes with the formation of robust SEI films.