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Journal of the Electrochemical Society, Vol.159, No.6, A894-A898, 2012
Sol-Gel Synthesis of Nanostructured Li2FeSiO4/C as Cathode Material for Lithium Ion Battery
Nanostructured Li2FeSiO4/C composites have been successfully synthesized by adopting polyethylene glycol (PEG) as the surfactant and L-ascorbic acid as the carbon additive, using a sol-gel method based on the acid-catalyzed hydrolysis/condensation of tetraethoxysilane (TEOS). The Li2FeSiO4/C nanocomposites possess dispersed spherical particles (similar to 50 nm) with narrow particle size distribution, embedded in a continuous carbon matrix. The Li2FeSiO4/C nanocomposites deliver first discharge capacity of 138.2 mAhg(-1) at C/16 and maintain at about 130.4 mAhg(-1) after 40 cycles at various rates at room temperature, which outperform those of Li2FeSiO4/C samples synthesized without PEG. The electrochemical performances of Li2FeSiO4/C were largely enhanced after the introduction of PEG due to the following two aspects. On one hand, the smaller particle size facilitated the shorter diffusion length for lithium ions; On the other hand, the more continuous carbon film coated on the particle surface enhanced the electronic conductivity of the nanocomposites and restrained the side reaction occurring at the electrode-electrolyte interface. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.110206jes] All rights reserved.