Electrospun polycrystalline LixFe0.2Mn0.8PO4/carbon composite fibers for lithium-ion battery

• LixFe0.2Mn0.8PO4/C composite fibers were synthesized based on the electrospinning method.
• The content of lithium of LixFe0.2Mn0.8PO4/C fibers has a strong effect on their electrochemical properties.
• The molecular structure of carbon sources plays an important role in determining the electrochemical properties of composite fibers.

LixFe0.2Mn0.8PO4/C (LixFMP/C, x = 1.2, 1.1, 1.05) composite fibers were successfully prepared by stabilization and calcination of the electrospun fibers from the precursor solution. The structural and morphological characterizations revealed that the LixFe0.2Mn0.8PO4 with high purity was evenly coated with an amorphous carbon layer. Experimental data testified the well-crystalline structure of composite fibers based on the results of the X-ray diffraction (XRD) and selected area electron diffractions (SAED). The galvanostatic charge–discharge measurements indicated that Li1.2Fe0.2Mn0.8PO4 displayed the highest capacity of 174 mA h g−1 at 0.05 C and the best cycling stability. The charge-transfer impedance of LixFe0.2Mn0.8PO4/C was decreased negatively with the content of lithium. It was found that the molecular structure of carbon sources and calcination procedure played key factor in determining the electrochemical properties of the composite fibers. These results suggested that electrospinning should be a promising method for fabricating crystalline LFMP/C composite fibers as electrode materials for lithium-ion battery.

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