The influence of synthesis conditions on the redox behaviour of LiFePO4 in aqueous solution
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To contribute to the knowledge on the influence of synthesis procedure on the intercalation kinetics of lithium ions into phospho-olivines, LiFePO4/C composite samples (LFPC) were synthesized in two ways, the first one in a sol-gel procedure (SG), and the other in a solid-state reaction (SS). The X-ray diffractograms (XRD) of both samples overlapped with that of pure LiFePO4, taken from the crystallographic database. Scanning electron microscopy pictures indicated the high degree of interparticle sintering, which caused a considerable agglomerate growth. The results of potentiodynamic measurements in aqueous LiNO3 solution revealed that for SS sample, three times higher initial capacity from that of SG one, (amounting to 74 mAh g−1 at 5 mV s−1). However, capacity fade on rising scan rate is much more expressed for SS sample than for SG one. We suggest that a different degree of material utilization due to the incomplete coverage of olivine particles by carbon explains this difference. ...The technique of separation of diffusion and capacitance currents was applied in a kinetic analysis, but it was shown to be inappropriate. We suggest the inapplicability of classic CV theory to the intercalation system accompanied by phase transition. Instead, a model of ohmic resistance determination of process kinetics was considered. LFPC-SS sample delivers three times larger capacity in LiNO3, amounting to 74 mAh g−1 at 1 mV s−1.
Кључне речи:aqueous electrolytes / kinetics of lithium redox behaviour / olivine LiFePO
Извор:Journal of Alloys and Compounds, 2019, 776, 475-485
- Молекуларно дизајнирање наночестица контролисаних морфолошких и физичко-хемијских карактеристика и функционалних материјала на њиховој основи (RS-45004)
- Магнетни и радионуклидима обележени наноструктурни материјали за примене у медицини (RS-45015)
- Синтеза, развој технологија добијања и примена наноструктурних мултифункционалних материјала дефинисаних својстава (RS-45019)
- Bilateral project between Serbia and Slovenia "Developments of novel materials for alkaline-ion batteries"
- Serbian Academy of Sciences and Arts, Project "Electrocatalysis in the contemporary process of energy conversion"
- This is the peer-reviewed version of the article: Georgijević, R., Vujković, M., Gutić, S., Aliefendić, M., Jugović, D., Mitrić, M., Đokić, V., Mentus, S., 2019. The influence of synthesis conditions on the redox behaviour of LiFePO4 in aqueous solution. Journal of Alloys and Compounds 776, 475–485. https://doi.org/10.1016/j.jallcom.2018.10.246