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.