Operando Observations of SEI Film Evolution by Mass‐Sensitive Scanning Transmission Electron Microscopy. Issue 45 (28th October 2019)

• Record Type: Journal Article
• Authors: Hou, Chen; Han, Jiuhui; Liu, Pan; Yang, Chuchu; Huang, Gang; Fujita, Takeshi; Hirata, Akihiko; Chen, Mingwei
• Is Part Of: Advanced energy materials. Volume 9:Issue 45(2019)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2019-10-28
• Subjects: liquid cell electron microscopy -- lithium‐ion batteries -- lithium‐metal batteries -- scanning transmission electron microscopy -- solid electrolyte interphase; Energy harvesting -- Materials -- Periodicals; Energy conversion -- Materials -- Periodicals; Energy storage -- Materials -- Periodicals; Photovoltaics -- Periodicals; Fuel cells -- Periodicals; Thermoelectric materials -- Periodicals; 621.31
• DOI: 10.1002/aenm.201902675
• Languages: English
• ISSNs: 1614-6832

Abstract

Abstract: 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. Abstract : Mass‐sensitive scanning transmission electron microscopy is employed to investigate the solid electrolyte interphase (SEI) formation, growth and failure at a high current density in a lithium ion liquid microcell. The operando observations reveal the bilayer hybrid structure of SEI films, demonstrate the radical assisted SEI growth after the SEI thickness beyond the electron tunneling regime, and uncover the dissolution stimulated SEI failure.