A structural and electrochemical study of Ni0.5TiOPO4 synthesized via modified solution route

A modified solution route synthesis of Ni0.5TiOPO4 using less reactive titanium precursor is presented. The Ni0.5TiOPO4 synthesized using this modified route was structurally investigated using the neutron and synchrotron X-ray diffraction measurements. Rietveld refinement of the high quality neutron diffraction data facilitated precise determination of oxygen position in the structure, which gave a clearer picture of the structure. As synthesized Ni0.5TiOPO4 was ball milled to reduce the particle size and then the morphological and electrochemical behaviors of these samples were examined. It was found that ball milling results in reduction of the particle size down from 100 mu m to 2.5 mu m, while increasing the BET specific surface area from under 1 m(2)/g to 2.6 m(2)/g, also resulting in a complete change in the morphology of the sample. Most prominent impact of the reduction in particle size is seen in the electrochemical cycling of Ni0.5TiOPO4. On ball milling, the lithiation plateau usually occurring around 1.2 V vs. Li/Li+, splits into two reaction plateaus, one high potential lithiation plateau at 1.8 V and another one still around 1.2 V vs. Li/Li+. This study details the modified synthesis route; complete structural study of the Ni0.5TiOPO4 synthesized using this route and effect of ball milling on the electrochemistry. (C) 2012 Elsevier Ltd. All rights reserved.