SiCO Ceramics as Storage Materials for Alkali Metals/Ions: Insights on Structure Moieties from Solid‐State NMR and DFT Calculations

Abstract

Polymer‐derived silicon oxycarbide ceramics (SiCO) have been considered as potential anode materials for lithium‐ and sodium‐ion batteries. To understand their electrochemical storage behavior, detailed insights into structural sites present in SiCO are required. In this work, the study of local structures in SiCO ceramics containing different amounts of carbon is presented. 13C and 29Si solid‐state MAS NMR spectroscopy combined with DFT calculations, atomistic modeling, and EPR investigations, suggest significant changes in the local structures of SiCO ceramics even by small changes in the material composition. The provided findings on SiCO structures will contribute to the research field of polymer‐derived ceramics, especially to understand electrochemical storage processes of alkali metal/ions such as Na/Na+ inside such networks in the future.

Structure–property relations of silicon oxycarbides studied using a machine learning interatomic potential

“…Si‐O‐C structures with varying compositions were generated with two different procedures. First, structures were produced to match the expected coordination, that is, fourfold for Si and C and twofold for O 53,54 . Second, an AL procedure, schematically shown in Figure 1, was employed.…”

“…First, structures were produced to match the expected coordination, that is, fourfold for Si and C and twofold for O. 53,54 Second, an AL procedure, schematically shown in Figure 1, was employed. Ternary systems based on the polymer derived (PD), bulk fragment (BF), and isolated atoms (Ats) building units shown in Figure 1(A) were generated and fed into the AL process.…”

The impact of templating and macropores in hard carbons on their properties as negative electrode materials in sodium-ion batteries

“…Nowadays, the most accepted mechanism is the “intercalation-micropore filling” suggested by Stevens et al 17,18 In several small-angle X-ray scattering (SAXS) studies as well as solid-state NMR investigations the sodium clustering inside the closed pores in a quasi-metallic state at potentials around 0 V vs. Na/Na + was observed and discussed as main source of plateau capacity. 19–27…”