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Spinel LiFe x Co 2-x O4 samples with 0.25≤x≤1 were synthesized by the sol-gel Pechini method at 300 o C in order to study the impact on their structural and electrochemical properties due to the substitution of Co by Fe. The specific capacity for lithium insertion into the electrode materials depend on lithium diffusion coefficient DLi which in turn depends on the Fe 3+ /(Fe +Co 3+ +Co 4+ ) octahedral cationic ratio. Keywords: Lithium- Ferrites, spinels, diffusion coefficient, Li-ion batteries, sol-gel 1.INTRODUCTION Li-ion batteries possess high energy density compared with Ni-Cd, NiMH, LiAl-FeS2 batteries, they are currently the most popular type of battery for portable electronic devices and they are growing in popularity for defense, automotive (EV,HEV,PHEV), storage systems using solar or wind powers and aerospace applications.Recently published reviews about Li-ion batteries and lithium-air batteries [1-6] emphasize that the energy densities of the current lithium-ion batteries are limited mainly by the inherent low energy density of the available conventional cathode materials. Transition metal oxides consisting of highly oxidized redox couples (Co |
