Carbon-coated nanophase CaMoO4 as anode material for Li ion batteries
Shaju, K. M.
Rao, G. V. Subba
Chowdari, Bobba V. R.
White, Timothy John
Date of Issue2004
School of Materials Science and Engineering
Pure and carbon (C)-coated CaMoO4 were synthesized by solution precipitation and solgel methods, and their electrochemical properties were studied vs Li by galvanostatic cycling and cyclic voltammetry (CV). Combined X-ray diffraction, SEM, and TEM results revealed the formation of nanocrystalline particles with the scheelite structure, the morphology being a function of the synthetic procedure. TEM of 10% C-coated CaMoO4 shows the amorphous nature of carbon on the crystalline particles with a thickness of 8-12 nm. Galvanostatic data in the voltage range of 0.005-2.5 V up to 50 cycles at a rate of 60 mA/g revealed that the 10% C-coated CaMoO4 gave the highest reversible capacities. At the 20th discharge cycle, the capacity values (mA h/g) are as follows: solution precipitated, 190; sol-gel, 268; 5% C-coated, 401; and 10% C-coated, 508. The latter value corresponds to 3.8 mol of recyclable Li. The improvement in the interparticle electronic conductivity imparted by the C-coating led to superior performance. The Coulombic efficiency for all the compositions is >98%. Galvanostatic cycling results are supplemented by the CV data. A plausible mechanism for charge-discharge cycling has been proposed.
Chemistry of materials
© 2004 American Chemical Society.