Local Structure and Magnetism of LiFeSi0.01P0.99O4/C as a Cathode Material on Lithium-Ion Battery

Abstract

The oxidation state and local structure of LiFeSi0.01P0.99O4/C composites as a cathode on lithium-ion battery were investigated by Fe K-edge X-ray Absorption Near Edge Spectroscopy (XANES) and Extended X-ray Absorption Fine Structure (EXAFS). The LiFeSi0.01P0.99O4/C sample was prepared by solid-state reaction process. Based on the XANES analysis, the absorption of edge energy (E0) of the sample was 7124.92 eV. In addition, linear combination fitting (LCF) analysis of XANES confirmed the oxidation state of iron mixture of 2+ and 3+ as the effect of silicon doped in LiFePO4. The Fourier Transform (FT) of the Fe K-edge EXAFS fitting analysis showed that the nearest neighbors surrounding atom Fe were the main peak with high intensity that confirmed Fe-O bond; the second and third peak with lower intensity confirmed Fe-P and Fe-Fe bonds, respectively. In addition, the SQUID magnetometer result of LiFeSi0.01P0.99O4/C indicated the antiferromagnetic order temperature of LiFeSi0.01P0.99O4/C at ~51 K with the indication of the presence of impurity and structural distortion.

X-ray Absorption Near Edge Structure (XANES) Spectrum Interpretation for LiFePO4-Silicon Doped Cathode Material

“…Both of these areas show the XANES spectrum characteristics of absorber atom, which is Fe atom in this study. In previous study, the spectrum and peak energy value (E0) of the Fe atom in the LiFeSixP1-xO4/C material for absorption edge area were 7124 -7125 eV (Maghfirohtuzzoimah et al, 2021;Astuti et al, 2021), while the spectrum of the Fe K-edge in Pre-edge area for standard sample and experimental sample is shown in Figure 2.…”

“…FeO, Fe2O3 and FePO4 were use for standard sample to comparison. Furthermore, XANES data were analyzed and fitted using Athena software Muyasaroh et al, 2019;Maghfirohtuzzoimah et al, 2021).…”

“…XANES data was used to get more detailed structural analysis and was analyzed to determine the information of the absorbing atom and its local environment. Furthermore, the pre-edge and main edge of the XANES spectra were analyzed qualitatively using ATHENA software (Husain et al, 2020;Intifadhah et al, 2021;Maghfirohtuzzoimah et al, 2021;Astuti et al, 2021). XANES data was performed to determine the absorption energy, oxidation number conditions and the ratio of oxidation composition (Husain et al, 2020).…”

NaFePO₄ Particles as a Cathode of Sodium Ion-Battery via Sol-Gel Method: A Review on Synthesis

“…LiFePO4 firstly reported by Goodenough et al, is a promising cathode material for Li-ion batteries that is commercialized successfully due to some advantages such as ecofriendly, high safety and high specific energy [5,6]. In addition, the improvement of cyclability of LiFePO4 is a factor to be considered to increase the battery's performance using several strategies such as doping, carbon coating process, and particle size reduction [7][8][9][10].…”

“…Maricite NaFePO4 reaches a capacity of 142 mAh/g (in which 92% of the theoretical value) at the first cycle [19]. The performance of NaFePO4 as a cathode of battery materials can be increased by particle size reduction [8]. There are some types of synthesis route for reducing particle size, such as wet-mixing method [27], ball-milling method [28], and sol-gel method [29] since the synthesis route or the preparation procedure has the significant role.…”