Effect of silver addition on the properties of combustion synthesized nanocrystalline LiCoO 2

Abstract

Nanocrystalline (∼50 nm) LiCoO 2 powders containing 0–10 mol% of Ag have been prepared by combustion synthesis using citrate–nitrate combustion route. Thermal analyses show a sharp decomposition of the gel at ∼177 °C for pristine LiCoO 2. With addition of silver, the decomposition becomes sluggish and it completes only above 430 °C. X-ray powder diffraction analyses show an increase in lattice parameter, c, with increasing Ag content suggesting the occupation of Ag within LiCoO 2 interlayer spacings. Transmission electron microscopy indicates diffusion of Ag into LiCoO 2 grains. It has been observed that adding 1.0 mol% silver increases the room temperature electrical conductivity by more than two orders of magnitude (1.5 × 10 −3 S cm −1). Galvanostatic charge–discharge profiles of coin cells fabricated with the synthesized powders show a two-fold enhancement in the discharge capacity for 1.0 mol% Ag-added LiCoO 2 cathode (140 mAh g −1) compared to that for pristine LiCoO 2 (70 mAh g −1).