Preparation and characterization of carbon foams-LiCoPO4 composites

The preparation and characterization of composites consisting of carbon foams coated with olivine structured lithium cobalt phosphate is reported. The composites are prepared by a Pechini assisted sol-gel process and treated under different conditions in flowing nitrogen and in flowing air. The structural, morphological and electrochemical properties were found to be dependent upon the annealing conditions as time and atmosphere. After annealing in nitrogen, the formation of the LiCoPO4 phase on the foams is observed at T = 730 degrees C. The photoelectron emission spectra reveal divalent cobalt ions in the composites. The LiCoPO4/foam composites deliver a discharge specific capacity of 100 mAh g(-1), at a discharge rate of C/25 and room temperature. After a pre-annealing in air then the annealing in nitrogen, the voltammetric curves show values of the reduction/oxidation processes at 4.6 V and 5.2 V respectively. The electrochemical measurements revealed a decrease of the capacity fade (similar to 26% at C/10, RT). A plateau in the specific capacity as a function of the potential has been observed. (C) 2011 Elsevier B.V. All rights reserved.