First-principles calculation of lithium insertion into homogeneous a-SiC2/5O6/5 as high performance anode

NB Liao and BR Zheng and M Zhang and W Xue, RSC ADVANCES, 7, 30559-30563 (2017).

DOI: 10.1039/c7ra05417c

Amorphous silicon oxycarbide is considered as a promising anode material for new generation of lithium-ion batteries, and figuring out the lithiation mechanism is crucial for its application. In this work, first principle calculations are performed to study the atomic structures, formation energy and lithiation voltage of homogeneous SiC2/5O6/5. The interpretation of radial distribution, angular distribution and coordinate number suggests that the Si-O bond tends to break and the Li2O will form at the beginning of lithiation, then the LixO and the LiySi form with increasing Li concentration, which makes a major contribution to the capacity of SiC2/5O6/5. By the Li content dependence of the formation energies curve, the theoretical specific capacity of SiC2/5O6/5 is predicted as 1415 mA h g(-1), which is comparable to the reversible capacity of 900 mA h g(-1) in experiments. Both the formation energies and the voltage curves suggest lithium is preferable in incorporation with SiC2/5O6/5, and this is attributed to the formation of LixO and LiySi.

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