STUDIES ON PURE AND Co-DOPED LiMn2O4 PREPARED BY NaCl:KCl MOLTEN SALT METHOD

摘要

Pure and Co-doped (0.17) LiMn2O4 are prepared using NaCl:KCl (1:1) eutectic melt at T=700850 ℃. They are characterized by X-ray diffraction (XRD), Rietveld refinement, Scanning Electron Microscopy (SEM), density and BET surface area. Single-phase compounds with cubic spinel structure are obtained in all cases. The lattice parameter (a~8.23A) of LiMn2O4 does not vary with the synthesis temperature, and the Co-doped compound shows a smaller value (a~8.21A). SEM shows 1-5 m sized spherical particles with～20 nm nanosized aggregates. Electrochemical properties are evaluated at ambient (24 ℃) and elevated (50 ℃) temperatures in cells with Li-metal as the counter electrode by cyclic voltammetry (CV), and galvanostatic cycling. CV results show characteristic redox peaks around 3.9/4.1 V and 4.0V/4.2 V vs. Li. Galvanostatic cycling at 0.25 and 1 C-rates in the voltage range, 3.5-4.3V vs. Li up to 100 cycles showed that Co-doping significantly reduces the capacity-fading at 50 刟C in comparison to bare LiMn2O4.