Synthesis of Li2FeSiO4/C nanocomposite via a hydrothermal-assisted sol–gel process

• Porous Li2FeSiO4/C composite is prepared via a hydrothermal assisted sol–gel method.
• The nitrogen-doped carbon layer is uniformly deposited on the surface of Li2FeSiO4.
• The formation mechanism of the porous Li2FeSiO4/C is discussed.
• It delivers an initial discharge capacity of 195.5 mAh·g− 1 at room temperature.

A porous Li2FeSiO4/C composite is synthesized via a hydrothermal-assisted sol–gel method. The porous Li2FeSiO4/C composite consisted of nanoparticles with only 20–30 nm size, surrounded by a nitrogen-doped carbon coating layer. Hydrothermal treatment plays a key role to control the crystallite size of the Li2FeSiO4 particles and to form the porous structure. The Li2FeSiO4/C composite obtained via a hydrothermal treatment exhibited a large surface area (50.2 m2·g− 1), which not only effectively prevents the agglomeration of Li2FeSiO4 particles, but also facilitates fast electron and Li+ transport.More than 1 mol Li+ can be extracted from the Li2FeSiO4/C electrode, which exhibits excellent electrochemical performance with a high discharge capacity of 195.5 mAh·g− 1 at 0.1 C and 127.1 mAh·g− 1 at 5 C (1 C = 166 mA·g− 1). These results illustrate that the porous Li2FeSiO4/C composite is a promising cathode material for lithium ion batteries.