CONICET | Buscador de Institutos y Recursos Humanos

Rechargable lithium ion batteries are very promising devices as energy storage for electric cars and electric devices. In the several materials under development for use as cathodes in lithium-ion batteries, orthophosphates LiMPO4 (M = Mn, Fe, Co, Ni) structure to olivine are intensively studied as lithium insertion compounds. Among the LiMPO4, lithium iron phosphate, LiFePO4, has been recognized as a promising candidate for Li batteries cathode due to the potential low-cost synthesis, environmental benignity, cycling stability, high theoretical capacity of 170 mAh g−1 and high temperature capability. For LiFePO4, the discharge voltage is about 3.4 V versus Li/Li+ and the capacity fade is small even after several hundred cycles.[1] The problem of this material is low electronic conductivity and low lithium diffusivity. The low conductivity leads to initial capacity loss and poor rate capability. The conductivity problems have been studied by particle optimizing, metal doping, and coating with the electronically conductive materials like carbon, metal and metal oxide. In this work the results for LiFePO4 obtained by solid phase synthesis with mechanical activation are presented. We compared both structural features and electrochemical behavior of materials prepared using different cooking processes, microwave vs. reflow oven under inert atmosphere. The advantage of using microwaves is that, not only the cooking time (minutes instead of hours) are decreased also the need for an inert atmosphere, thus reducing further the production costs of the material. Also we studied the effect of different times of calcinations in the characteristics of the material obtained. It was noted that the materials cooked by microwave have a better electrochemical behavior than those obtained in inert atmosphere furnace, because showing a higher load capacity and higher diffusion constant.