| AVS 64th International Symposium & Exhibition | |
| Applied Surface Science Division | Thursday Sessions |
| Session AS-ThP |
| Session: | Applied Surface Science Poster Session |
| Presenter: | Chris Moffitt, Kratos Analytical Ltd |
| Authors: | J.D.P. Counsell, Kratos Analytical Limited, UK C. Moffitt, Kratos Analytical Ltd A.J. Pearse, University of Maryland, College Park C.J. Blomfield, Kratos Analytical Limited, UK S.J. Coultas, Kratos Analytical Limited, UK G. Rubloff, University of Maryland, College Park |
| Correspondent: | Click to Email |
Classical lithium ion batteries rely on a liquid electrolyte however there have been significant developments towards replacing liquid electrolytes with solid state thin-films. Thin-film lithium ion batteries offer improved performance by having a higher average output voltage, lighter weights thus higher energy density, and longer cycling life than typical liquid electrolyte batteries [1]. In order to construct a thin film battery it is necessary to fabricate all the battery components, such as an anode, a solid electrolyte, a cathode and current leads into a multi-layered thin film. Lithium phosphorous oxynitride (LiPON) is widely used as the electrolyte in solid state micro-batteries due to low electronic conductivity, increased durability to cycling and ease of preparation.
Here we will use convention surface analysis techniques of XPS and sputter depth profiling to understand the surface and bulk chemistry of LiPON thin films formed via atomic-layer deposition (ALD) [2]. XPS yields quantitative information regarding the elemental composition of the near surface region to a depth of <10 nm. The elemental composition as a function of depth is probed and comparisons are made between conventional monatomic depth profiling and cluster depth profiling. We will also analyse complete battery stacks in their virgin and cycled states and discuss changes in elemental distributions at the interfaces between the electrodes and the solid electrolyte.
We demonstrate that the use of monatomic Ar ions is unsuitable for profiling materials with mobile light elements (Li) as the build-up of positive charge causes migration leading to erroneous depth composition. An alternative is proposed whereby the analyst uses 20 kV high-energy cluster ions in an attempt to mitigate the effects of ion migration and thereby improving confidence in the validity of the results.
[1] Y. Kato, S. Hori, T. Saito, K. Suzuki, M. Hirayama, A. Mitsui, M. Yonemura, H. Iba, R. Kanno, M. Armand, Nat. Energy 2016, 1, 16030.
[2] A. Kozen, A. Pearse, G. Rubloff, C-F Lin, M. Noked, Chem. Mater., 2015, 27, 5324–5331