Bergfeldt, T.

Fischer, J.

Rinke, M.

Seifert, HJ.

Strafela, M.

Ulrich, S.

Seifert, H. J.

KITopen

PortfolioElektrochemische Speicher im SystemZuverlässigkeit und Integration300 °C / 600 °C, 1 hour, 10 Pa Ar/O2 (80:20)-atmosphere Argon working gas pressure: 0.2 Pa to 20 Pa / target power: 100 W   film thickness: ~1.5 µm AP 2.1 Structuring and processing of electrodes  Principal investigators:  S. Ulrich, H. J. Seifert, KIT (IAM-AWP)  Constitution and microstructure of Li-Ni-Mn-Co-O thin film cathodes  1.5 µm thick Li-Ni-Mn-Co-O cathodes have been deposited by r.f. magnetron sputtering from  Li1.25(Ni0.42Mn0.21Co0.37)O2 target. The elemental composition varies with argon working gas pressure (0.2 Pa to 20 Pa)  and was determined by inductively coupled plasma-optical emission spectroscopy (ICP-OES) in combination with carrier gas hot extraction. The microstructure of the films was characterized by X-ray diffraction (XRD) and by micro-Raman spectroscopy at room temperature. The as-deposited films are nanocrystalline and show their highest grade of crystallinity in the range between 0.2 Pa to 0.5 Pa and at 7 Pa. Correlations between process parameter, constitution and microstructure are discussed in detail.  Materials selection: Properties and structure of Li(Ni1/3Mn1/3Co1/3)O2:  Theoretical capacity: 290 mAh/g  Practical capacity: 160-180 mAh/g  Voltage vs. Li: 2.5 V - 4.6 V  Space group: R3m        hexagonal lattice        a = b = 2.867Å c = 14.246 Å         α = β = 90° γ = 120°  Color: black-grey Magnetron sputtering setup: Prof. Dr. B. Scrosati, online lecture, Helmholtz Institute Ulm, 2013 b a Si (001) Li(Ni-Mn-Co)O2 {1.5 µm} {substrate} Deposition parameters:  Annealing parameters:  Results: X-Ray diffraction as dep. Growth rates Raman spectroscopy  as dep. Surface images SEM images after annealing at 600 °C, with cracks Optical microscope images before annealing, free of cracks 0.5 Pa 0.5 Pa 7 Pa 7 Pa Deviation of peak positions and literature value Dashed lines show reflection position reported in literature A1g mode Vibration of O Atoms in LiMO2 Acknowledgment: The authors gratefully acknowledge the financial support by the Helmholtz-Portfolio-project  “Elektrochemische Speicher im System - Zuverlässigkeit und Integration“ Conclusions and Outlook: • Li-Ni-Mn-Co-O thin films were synthesised with different microstructures and elemental compositions. • The X-Ray reflections deviate from positions reported in literature.          The difference is  probably caused by residual stresses or different elemental composition. • At 0.5 Pa and 7 Pa the as deposited films show the highest grade of crystallinity. • Next steps will be annealing in different atmospheres, investigations of the electrochemical behavior, surface modifications with laser and plasma technology, development of an artificial SEI. A1g mode Vibration of O Atoms in LiMO2 2Θ in deg. 2Θ in deg. 2Θ in deg. X-Ray diffraction as dep. Argon working gas pressure in Pa Argon working gas pressure in Pa Raman shift in cm-1 Raman shift in cm-1 Raman shift in cm-1 (before anneling) X-Ray diffraction 0.5 Pa Raman spectroscopy  0.5 Pa Raman spectroscopy  7 Pa ICP-OES and CGHE analysis X-Ray diffraction 7 Pa Additional investigators:  M. Strafela, J. Fischer, M. Rinke, T. Bergfeldt, KIT (IAM-AWP)  

Constitution and microstructure of Li-Ni-Mn-Co-O thin film cathodes

https://publikationen.bibliothek.kit.edu/220102332/3816918

Constitution and microstructure of Li-Ni-Mn-Co-O thin film cathodes

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