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Abstract: Carbon-coated lithium iron phosphate (LiFePO4/C) composites were synthesized by conventional mechanical activation (MA) process and also by a modified MA process. Phase-pure particles were obtained of ∼100nm size with a nano-meter thick web of carbon surrounding the particles. The composite prepared by the modified MA process shows good performance as cathode material in lithium cells at room temperature. A high performance was achieved at 0.1C-rate with >96% utilization of the active material. A stable cycle performance even at higher C-rates was achieved with a cathode that has a total carbon content of only 12wt%. The use of the modified MA process to synthesize LiFePO4/C has promise to be an efficient process to decrease the total carbon content of the cathode, resulting in the enhanced energy density. [Copyright &y& Elsevier]

Abstract: Carbon-coated LiFePO4 (LiFePO4/C) composite cathode-active materials of submicron size and phase-pure olivine structure were synthesized by a mechanical activation (MA) process. The conductive carbon coating was achieved by addition of (i) carbon powder directly or (ii) sucrose as the carbon precursor, during synthesis. LiFePO4/C containing 6wt% carbon prepared by the two methods showed good electrochemical properties as cathodes in lithium batteries at room temperature with high active material utilization of >94% at 0.1C rate and stable cycle performance. The sucrose precursor method leads to the formation of a thin, porous and more uniform carbon coating around the particles and results in a slightly higher discharge capacity (∼3%) compared to the other sample. [Copyright &y& Elsevier]

Abstract: The phospho-olivines LiMPO4 (where M denotes Fe, Mn, Co, Ni) have attracted a lot of attention in recent years as potential positive electrode materials for lithium batteries. The solid–solution Li(Mn y Fe1− y )PO4 has been particularly promising since it operates at the desirable cell voltage of 3.4–4.1V vs. Li+/Li. In this work, Li(Mn0.4Fe0.6)PO4 synthesized by a modified mechanical activation method was evaluated for electrochemical performance as the cathode material in lithium metal battery at room temperature. Phase-pure particles of size ∼100nm were prepared with a conductive, thin web of carbon surrounding them, by incorporating carbon powder as additive during the synthesis. Cyclic voltammetry showed the active voltage range of the material which consists of two pairs of redox peaks: 3.47V corresponding to Fe3+/Fe2+ reaction and 4.02V corresponding to Mn3+/Mn2+ reaction. An initial discharge capacity of 139mAh/g and a stable cycling property were attained at 0.1 C-rate, attributed to the small particle size and the effective conductive coating achieved for the material by the efficient synthesis process. [Copyright &y& Elsevier]

Abstract: An efficient synthesis based on mechanical activation (MA) was developed for carbon-coated lithium iron phosphate (LiFePO4/C). The conventional MA process was modified by introducing two initial steps of slurry phase blending of the ingredients and solvent removal by rotary evaporation, so as to get an intimate mixing and homogenous dispersion of conductive carbon in the sample. Phase-pure, nanometer-sized particles of the active material covered with a porous, nanometer-sized web of carbon were obtained. LiFePO4/C exhibited remarkably good electrochemical properties when evaluated as cathodes in room temperature lithium cells. An initial discharge capacity of 166 mAh/g (corresponding to 97.6% of theoretical capacity) was achieved at 0.1 C-rate. A very stable cycle performance was also realized; good capacity retention up to 100 cycles was achieved at different current densities. [Copyright &y& Elsevier]