New freeze-drying method for LiFePO4 synthesis |
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Authors: | Verónica Palomares Aintzane Goñi Izaskun Gil de Muro Iratxe de Meatza Miguel Bengoechea Oscar Miguel Teófilo Rojo |
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Affiliation: | 1. Departamento de Química Inorgánica, Universidad del País Vasco UPV/EHU, Apdo. 644, 48080 Bilbao, Spain;2. Departamento de Energía, CIDETEC, P° Miramón 196, Parque Tecnológico de San Sebastián, 20009 San Sebastián, Spain |
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Abstract: | The freeze-drying method is proposed as an effective synthesis process for the obtaining of LiFePO4/C composites. The citric acid is used as a complexing agent and carbon source. After the low temperature annealing, the freeze-dried solution leads to a homogeneous carbon covered LiFePO4 sample. The chemical characterization of the material included ICP and elemental analysis, infrared spectroscopy, X-ray diffraction, magnetic measurements and thermal analysis. SEM and TEM microscopies indicate an aggregate morphology with tiny particles of lithium iron phosphate inside a carbon matrix. Impedance spectroscopy showed a 8.0 × 10−7 S cm−1 conductivity value. Cyclic voltammetry graphics displayed the two peaks corresponding to the Fe(II)/Fe(III) reaction and demonstrated the good reversibility of the material. The specific capacity value obtained at C/40 rate was 164 mAh g−1, with a slight decrease on greater C-rates reaching 146 mAh g−1 at C/1. The capacity retention study has evidenced good properties, with retention over 97% of the maximum values in the first 50 cycles, which allows an effective performance of the freeze-dried sample as cathodic material in lithium-ion batteries. |
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Keywords: | LiFePO4 Synthesis Freeze-drying |
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