20.500.12556/RUL-159399 Structural and chemical analysis of hard carbon negative electrode for Na-ion battery with X-ray Raman scattering and solid-state NMR spectroscopy This study explores the structural changes of hard carbon (HC) negative electrodes in sodium-ion batteries induced by insertion of Na ions during sodiation. X-ray Raman spectroscopy (XRS) was used to record both C and Na K-edge absorption spectra from bulk HC anodes carbonized at different temperatures and at several points during sodiation and desodiation. Comparing the $\pi ^∗/\sigma ^∗$ regions in the C K-edge spectra sp$^2$/sp$^3$ hybridization ratio of material was determined. Higher carbonization temperatures led to increased order in graphitic structure and shorter C–C bond lengths. Sodiation caused a decrease in graphitic layer order due to inserted Na ions. Complementary operando solid state $^{23}$Na nuclear magnetic resonance (ssNMR) studies confirmed the structural changes, while showing pore filling mechanism, which is not observed in ex situ measurements, primarily at higher carbonization temperatures. XRS analysis of Na K-edge spectra revealed systematic variations in the solid electrolyte interface (SEI) composition during cycling. Changes in XRS spectra were attributed to both SEI composition alterations, accompanied by the insertion/adsorption of Na ions at defect sites within the carbon structure. hard carbons X-ray Raman scattering ssNMR Na-ion batteries trdi ogljik Ramanova spektroskopija baterije elektrotehnika ogljik true false true Angleški jezik Slovenski jezik Članek v reviji 2024-07-09 15:07:46 2024-07-09 15:07:53 2025-03-19 13:34:31 0000-00-00 00:00:00 2024 0 0 14 str. Vol. 228, art. 119398 Sep. 2024 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 544.5/.6 1873-3891 10.1016/j.carbon.2024.119398 201116419 1-s2.0-S0008622324006171-main.pdf 1-s2.0-S0008622324006171-main.pdf 1 03C2B3A08A27C3F4302D808711BFE397 dc0915ad8ceadad429c1e7caa93b98975b18580c70469bc88b7e36e226c723af a734f2dc-3df4-11ef-8f74-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=187409 https://www.sciencedirect.com/science/article/pii/S0008622324006171 0 3f4d73ca-3df4-11ef-8f74-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=187408 Fakulteta za matematiko in fiziko Fakulteta za strojništvo 0 0 0