Synthesis and characterization of LiFePO4-carbon nanofiber with Ti4 + substitution by electrospinning and thermal treatment

• Ti4 + substituted LiFePO4-CNF composites are prepared.
• Ti4 + at Li or Fe site stabilizes crystal structure and decreases charge transfer resistance.
• Cycling performance and rate capability are improved without destroying olivine structure of LiFePO4.
• Mix-doped nominal LiFe0.96Ti0.02PO4-CNF exhibited optimal electrochemical performance.

Binder-free LiFePO4-carbon nanofiber (LiFePO4-CNF) composites and titanium cation (Ti4 +) substituted LiFePO4-CNF composites are prepared by electrospinning and post-thermal treatment. The morphology, structure, carbon content, metal content and electrochemical performance of the materials are characterized by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), elemental analysis (EA), inductively coupled plasma emission spectroscopy (ICP), charge–discharge tests, and electrochemical impedance spectroscopy (EIS). The results indicated that the doping Ti4 + at the Li or Fe site could stabilize the crystal structure, decrease charge transfer resistance, enhance lithium ion diffusion velocity, and thus improve the cycling performance and the rate capability of the materials without destroying the olivine structure of LiFePO4. In particular, the mix-doped nominal LiFe0.96Ti0.02PO4-CNF composites exhibited the optimal electrochemical performance. Its first discharge capacity was 144.3 mA h g− 1 with 0.5C.