Dresden 2017 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 67: SYLI: Symposium Interfacial Challenges in Solid-State Li Ion Batteries - defects, structure and thermodynamics

O 67.1: Vortrag

Mittwoch, 22. März 2017, 10:15–10:30, IFW A

Structure, thermodynamics and Li storage of and in amorphous siliconoxycarbides: insights from first-principle calculations — •Jochen Rohrer and Karsten Albe — FG Materialmodellierung, FB Material- und Geowissenschaften, Technische Universität Darmstadt

Precursor-derived amorphous siliconoxycarbides (SiOC) are attracting increased attention as potential anode material for Li-ion batteries. Capacities of 600 mAh/g and above have been achieved. Furthermore, SiOCs have been reported to be thermodynamically stable relative to the crystalline boundary phases cristobalite, SiC and graphite. On the microscale, SiOCs are well characterized and can be described by regions consisting of amorphous SiO2, graphitic free carbon and mixed ternary regions. The details of the atomic structure within the ternary regions are, however, still under debate.

In this contribution we present strategies to model and determine local atomic characteristics of SiOC using density functional theory calculations. Using cluster models, we systematically investigate the bonding environment of carbon in ternary Si-O-C regions. Thereby we consider various coordinations and the possibility of hydrogen incorporation into the amorphous network [1]. Based on the predicted local C environment, we then design periodic supercell models with variable carbon content, compute thermodynamic stability and investigate Li storage in a way similar to our previous work on Si anodes [2].

[1] J. Rohrer et al., submitted to Int. J. Mater. Res. (Nov 2016).

[2] J. Rohrer and K. Albe, J. Phys. Chem. C 117, 18796 (2013).

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