Investigation on LiCoPO4 powders as cathode materials annealed under different atmospheres

• Published in: Journal of solid state electrochemistry Vol. 16; no. 3; pp. 911 - 919
• Main Authors: Dimesso, Lucangelo, Jacke, Susanne, Spanheimer, Christina, Jaegermann, Wolfram
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.03.2012
• Subjects: Analytical Chemistry; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Condensed Matter Physics; Electrochemistry; Energy Storage; Original Paper; Physical Chemistry; Lithium cobalt phosphate; Annealing; Air; Sol–gel; Cathode materials; Nitrogen
• ISSN: 1432-8488; 1433-0768
• DOI: 10.1007/s10008-011-1441-5

An uncomplicated Pechini-assisted sol–gel process in aqueous solutions is used for the synthesis of Li–Co phosphate powders as cathode materials. The powders are annealed under different conditions in flowing nitrogen and in flowing air. The structural, morphological, and electrochemical properties are strongly dependent upon the annealing conditions. After the treatment in air, the X-ray diffraction (XRD) patterns reveal the presence of LiCoPO 4 as a single phase. The morphology of the powders consists of a homogeneous and good interconnected blend of grains with different sizes; the cyclic voltammetry (CV) curves show a very good reversibility with very close values of the mean peak maxima in the cathodic region. The electrochemical measurements deliver a discharge specific capacity of 37 mAhg −1 at a discharge rate of C/25 at room temperature. After annealing in nitrogen, the XRD analysis detects the formation of Li 4 P 2 O 7 and to Co 2 P as secondary phases; the morphological investigation indicated that the LiCoPO 4 particles took shape of prisms with an average size of 2 μm. The CV curves are associated with a large polarization and poor irreversibility. The electrochemical measurements deliver a discharge specific capacity of 42 mAh g −1 at a discharge rate of C/25 at room temperature and lower capacity fade (approx. 35%).