Electrochemical properties of nanostructured Li2FeSiO4/C synthesized by a simple co–precipitation method

• Nanostructured Li2FeSiO4/C is synthesized by a simple co-precipitation method.
• Thermodynamic calculation provides guidance for the synthesis of pure Li2FeSiO4.
• Li2FeSiO4/C shows high reversible capacity and excellent cycling performance.

Nanostructured Li2FeSiO4/C cathode material is successfully synthesized through a simple co–precipitation method by using Fe3+ salt as iron source and polyethylene glycol as surfactant. Thermodynamic calculation is carried out to get phase predominance diagram as functions of oxygen partial pressure and temperature for Fe–O–C system, which provides effective guidance for synthesis parameter selection of pure phase Li2FeSiO4. The synthesized Li2FeSiO4/C nanoparticles show an average size of 150 nm, which are composed of ultra–small Li2FeSiO4 nanocrystals in 10–25 nm dispersing in amorphous carbon matrix. The in situ formed carbon network and the Li2FeSiO4 nanocrystals provide a fast transport of electron and lithium ion and thus ensure a quick electrode reaction, leading to an excellent electrochemical performance. The synthesized Li2FeSiO4/C exhibits a specific capacity of 190 mAh g−1 at 0.1 C, realizing reversible extraction/insertion of 1.37 Li+, taking into account of 16.1 wt% carbon content in the composite. This work offers a simple, scalable, and low cost approach for the synthesis of high performance Li2FeSiO4/C cathode material for lithium ion batteries.

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