Structure and Electrochemical Characteristics of LiFePO4 as Cathode Material for Lithium-Ion Batteries
To prepare cathode material for lithium batteries, LiFePO4 powder was sputtered using an RF magnetron. Thin LiFePO4 films were obtained on different ~1000 nm thick substrates. The compositional and morphological examination of these films by SEM has shown that on a silicon substrate the annealed nano-crystalline thin film of LiFePO4 material condenses in larger monocrystals (with thin film disappearance), while such a film on the stainless steel substrate coalesces in a uniform nano-structured layer after annealing. As shown by the energy-dispersive X-ray analysis, the annealed film consists of phosphorus, iron, and oxygen in the ratio corresponding to the stoichiometric LiFePO4. Cyclic voltammograms of the LiFePO4 thin layer were obtained with typical red-ox reaction peaks characterizing the electrochemical lithium insertion/extraction reactions in LiFePO4. The obtained thin films have a relatively high charge capacity of 127 mAh g-1.