In Situ Carbon Coated Li2MnSiO4/C Composites as Cathodes for Enhanced Performance Li-Ion Batteries

An in-situ carbon coated Li2MnSiO4/C composite was synthesized by a nanocomposite gel precursor route using starch as the carbon source. Our approach enabled a uniform coating of amorphous carbon on Li2MnSiO4 with an orthorhombic crystalline structure, which was confirmed by electron microscopy, X-ray diffraction and Raman studies. Conducting-atomic force microscopy (C-AFM) images also revealed the presence of high current interconnected domains in the composite, indicating the ability of the carbon coating to facilitate electron movement. Galvanostatic charge-discharge studies demonstrated outstanding initial charge and discharge capacities, respectively, of 330 and 195 mAh g(-1) at 0.05 C-rate for the composite, and after 30 cycles a reversible capacity of 115 mAh g- I was retained. The electrochemical performance of the neat silicate was dismal (10.6 mAh g(-1) at 0.05 C-rate), which again reiterated the role of carbon in improving the conduction and Li-ion storage capacity of the silicate. An insignificant change in charge transfer resistance, with cycling, as inferred from impedance spectroscopy illustrated that charge transfer and transport processes remain facile with cycling, thus demonstrating Li2MnSiO4/C to be promising cathode Li-ion batteries. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.042212jes] All rights reserved.