Colloidal synthesis of monodisperse ultrathin LiFePO₄ nanosheets for Li-ion battery cathodes

Lithium-ion conductivity is one of the critical factors in improving the rate capability of LiFePO₄ in lithium-ion batteries. The one-dimensional diffusion pathway of lithium ions slows the charging/discharging rates in the olivine structure of LiFePO₄. Herein, ultrathin LiFePO₄ nanosheets were synthesized using surface-passivating ligands to address the rate capability issue. The thickness direction of the nanosheets is the [010] direction in which the lithium ions are inserted or extracted during cycling. The structural and morphological characterizations were performed via transmission electron microscopy and X-ray diffraction. A thickness of 7.5nm was obtained from the atomic force microscopy height profiles, which is in the scale of twelve unit cells of LiFePO₄. Electrochemical performance test results revealed that the Li-ion batteries had superior rate capability during the charging/discharging process.