One-pot coating of LiCoPO/C by a UiO-66 metal-organic framework.

LiCoPO (LCP) is a promising high voltage cathode material but suffers from low conductivity and poor electrochemical properties. These properties can be improved by coating with a conductive carbon layer. Ongoing research is focused on the protective layer with good adhesion and inhibition of electrolyte decomposition reactions. In the present work, we suggest a new robust one-pot procedure, featuring the introduction of UiO-66 metal-organic framework (MOF) nanoparticles during LCP synthesis to create a metal-carbon layer upon annealing. The LiCoPO/C@UiO-66 was synthesized the microwave-assisted solvothermal route, and 147 mA h g discharge capacity was obtained in the first cycle. The MOF acts as a source of both carbon and metal atoms, which improves conductivity. Using X-ray absorption spectroscopy upon cycling, we identify two Co-related phases in the sample and exclude the olivine structure degradation as an explanation for a long-term capacity fade.