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Abstract: A series of polypyrrole-LiFePO4 (PPy-LiFePO4) composites were synthesised by polymerising pyrrole monomers on the surface of LiFePO4 particles. AC impedance measurements show that the coating of polypyrrole significantly decreases the charge-transfer resistance of LiFePO4 electrodes. The electrochemical reactivity of polypyrrole and PPy-LiFePO4 composites for lithium insertion and extraction was examined by charge/discharge testing. The PPy-LiFePO4 composite electrodes demonstrated an increased reversible capacity and better cyclability, compared to the bare LiFePO4 electrode. [Copyright &y& Elsevier]

Abstract: Spherical LiNi0.75Co0.25O2 compounds were synthesized by sintering spherical Ni0.75Co0.25(OH)2 and LiOH·H2O precursors at various temperatures in an oxygen atmosphere. A pure phase LiNi0.75Co0.25O2 could be identified. SEM observation showed that the LiNi0.75Co0.25O2 particles are spherical in shape and are composed of many small crystals. Magnetic susceptibility measurements reveal that the spherical LiNi0.75Co0.25O2 compounds have a more ordered layered structure than that of non-spherical LiNi0.75Co0.25O2. The spherical LiNi0.75Co0.25O2 cathodes demonstrated a stable electrochemical performance in lithium-ion cells with a high reversible capacity of 167mAh/g and good cyclability. [Copyright &y& Elsevier]

Abstract: For the first time, carbon-mixed LiFePO4 (LFP) cathode materials have been prepared by spray solution technology. Nominal addition of 15 or 20wt.% C was used in order to simulate the industrial practice for preparation of electrode materials. The prepared powders consist of a single LiFePO4 phase: small crystallites with a highly developed surface area, beneficial for the surface electrochemical processes limited by the low Li diffusion. The combination of spray technology and carbon addition increased the specific surface area above 20m2/g at a relatively high sintering temperature (700°C). The initial discharge capacity was up to 140mAh/g compared to 125mAh/g for conventionally prepared (using a solid state reaction) LiFePO4 electrode materials. [Copyright &y& Elsevier]