Fabrication and electrochemical characterization of amorphous lithium iron silicate thin films as positive electrodes for lithium batteries

• Thin film deposition of amorphous Li/M(Fe,Mn)/Si/O by r.f. sputtering.
• Good electrochemical performances: 50 mAh g−1 at 2.5 C.
• The films were able to sustain about 300 cycles of charge–discharge.

In this work we reported, for the first time, the preparation by radio frequency sputtering and the electrochemical characterization of Li/M/Si/O thin films (M = Fe, Mn), as positive electrodes for lithium microbatteries. The deposited films were amorphous both in case of pure iron and mixed iron/manganese compositions. The electrochemical performances, in terms of capacity values and coulombic efficiency, were comparable to those currently reported for the corresponding crystalline bulk materials. In particular, capacities of the order of 50 mAh g−1 were obtained at 2.5 C with coulombic efficiency near 90% by using a standard liquid electrolyte. Our preliminary electrochemical results, together with the easiness of preparation, suggested that Li/M/Si/O thin films could be interesting candidates as cathodes in lithium microbatteries.

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