Electrochemical Performance of Li2FeSiO4 as Anode Material for Lithium-ion Batteries

The conventional cathode material Li2FeSiO4 (lithium iron orthosilicate) crystallites are synthesized by a solid state reaction, and used as the anode material for lithium-ion batteries. During the initial discharge, Li2FeSiO4 irreversibly decomposes and transforms. Although the resulted anodes hardly contain Li2FeSiO4 crystal phase, they show nice capacities and well cycling stability. At a current density of 50 mA g−1, the anode exhibits an initial discharge/charge of 799/569 mAh g−1, and keeps a discharge/charge capacity of 550/542 mAh g−1 after 60 cycles with 95.3% charge capacity retention. At a current of 1000 mA g−1, the anode shows a charge capacity of 191 mAh g−1 with 99.5% coulombic efficiency during the 300th cycle. The anode material after 300 cycles presents many microcrystal structures. It is proposed that the Li2FeSiO4 anodes transfer energy via a reversible conversion reaction.