Synthesis and modification of nanocrystalline LiFePO4 as a cathode material for lithium-ion batteries

• A novel nanocrystalline LiFe0.96Ti0.02PO4/C as cathode materials for lithium-ion batteries is synthesized.
• LiFe0.96Ti0.02PO4/C has outstanding conductivity of 1.00×10−1S·cm−1, which may be the highest magnitude of LiFePO4 cathode material.
• We proved that ion doping enhances the diffusion velocity of Li+ to some extent.
• Under 5C rate, LiFe0.96Ti0.02PO4/C has discharge specific capacities of 121.95 mAh·g−1.

Poly-aniline (PANI) coated nano-powder FePO4/PANI was synthesized. LiOH·H2O, FePO4/PANI and polyvinyl alcohol (PVA) were used as the raw materials to synthesize the nanocrystalline LiFePO4 and then it was coated by carbon and doped by titanium. The properties of the samples are investigated using XRD, SEM, TEM and electrochemical methods. Electrochemical measurements were conducted in half cells with nanocrystalline LiFePO4, LiFePO4/C and LiFe0.96Ti0.02PO4/C as cathode materials and lithium metal as the anode. Results have shown that nano-structure helps the doping ion to enter into crystal lattice of LiFePO4 easily and distribute uniformly. LiFe0.96Ti0.02PO4/C has well coating structure with higher crystalline, smaller grain size, higher capacity and better rate performance than other samples.