Consequences of air exposure on the lithiated graphite SEI

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• 作者：Sara Malmgren ; Katarzyna Ciosek ; Rebecka Lindblad ; Stefan Plogmaker ; Julius K¨¹hn ; H?kan Rensmo ; Kristina Edstr?m ; Maria Hahlin
• 关键词：XPS ; SEI ; Graphite ; Air ; LiPF6
• 刊名：Electrochimica Acta
• 出版年：2013
• 出版时间：30 August, 2013
• 年：2013
• 卷：105
• 期：Complete
• 页码：83-91
• 全文大小：1485 K

文摘

In the present work, consequences of air exposure on the surface composition of one of the most reactive lithium-ion battery components, the lithiated graphite, was investigated using 280-835 eV soft X-ray photoelectron spectroscopy (SOXPES) as well as 1486.7 eV X-ray photoelectron spectroscopy (XPS) (¡«2 and ¡«10 nm probing depth, respectively). Different depth regions of the solid electrolyte interphase (SEI) of graphite cycled vs. LiFePO₄ were thereby examined. Furthermore, the air sensitivity of samples subject to four different combinations of pre-treatments (washed/unwashed and exposed to air before or after vacuum treatment) was explored. The samples showed important changes after exposure to air, which were found to be largely dependent on sample pre-treatment. Changes after exposure of unwashed samples exposed before vacuum treatment were attributed to reactions involving volatile species. On washed, air exposed samples, as well as unwashed samples exposed after vacuum treatment, effects attributed to lithium hydroxide formation in the innermost SEI were observed and suggested to be associated with partial delithiation of the surface region of the lithiated graphite electrode. Moreover, effects that can be attributed to LiPF₆ decomposition were observed. However, these effects were less pronounced than those attributed to reactions involving solvent species and the lithiated graphite.