%0 Journal Article %A Jennifer Ludwig %A Dennis Nordlund %A Marca M Doeff %A Tom Nilges %B Journal of Solid State Chemistry %D 2017 %G eng %P 9 - 17 %R 10.1016/j.jssc.2017.01.015 %T Synthesis and characterization of metastable, 20 nm-sized Pna 2 1 -LiCoPO 4 nanospheres %V 248 %8 04/2017 %! Journal of Solid State Chemistry %X

The majority of research activities on LiCoPO4 are focused on the phospho-olivine (space group Pnma), which is a promising high-voltage cathode material for Li-ion batteries. In contrast, comparably little is known about its metastable Pna21 modification. Herein, we present a comprehensive study on the structure–property relationships of 15–20 nm Pna21-LiCoPO4 nanospheres prepared by a simple microwave-assisted solvothermal process. Unlike previous reports, the results indicate that the compound is non-stoichiometric and shows cation-mixing with Co ions on the Li sites, which provides an explanation for the poor electrochemical performance. Co L2,3-edge X-ray absorption spectroscopic data confirm the local tetrahedral symmetry of Co2+. Comprehensive studies on the thermal stability using thermogravimetric analysis, differential scanning calorimetry, and in situ powder X-ray diffraction show an exothermic phase transition to olivine Pnma-LiCoPO4 at 527 °C. The influence of the atmosphere and the particle size on the thermal stability is also investigated.