Characterization of LiMxFe1–xPO4 (M = Mg, Zr, Ti) Cathode Materials Prepared by the Sol-Gel Method

A series of LiMxFe12xPO4 (M 5 Mg,Zr,Ti) phosphates were synthesized via a sol-gel method. Transmission electron microscopy observations show that LiMxFe12xPO4 particles consist of nanosize crystals, ranging from 40 to 150 nm. High-resolution TEM analysis reveals that a layer of amorphous carbon was coated on the surface of the LiMxFe12xPO4 particles, which substantially increases the electronic conductivity of LiMxFe12xPO4 electrodes. The doped LiMxFe12xPO4 powders are phase pure. Near full capacity ~170 mAh/g! was achieved at the C/8 rate at room temperature for LiMxFe12xPO4 electrodes. The doped LiMxFe12xPO4 electrodes demonstrated better electrochemical performance than that of undoped LiFePO4 at high rate

Synthesis and Characterization of LiFePO4 and LiTi0.01Fe0.99PO4 Cathode Materials

Nanocrystalline LiFePO4 and doped LiTi0.01Fe0.99PO4 powders were synthesized via a sol-gel preparation route. High-resolution tunneling electron microscopy observation and energy dispersive spectroscopy, mapping show the homogeneous distribution of dopant Ti cations in the crystals. Fe and O K -edge X-ray absorption near-edge structure (XANES) measurements show that Ti4+ doping induces an increased unoccupied d-state in LiFePO4, resulting in an enhanced p-type semiconductivity. In situ Fe K -edge XANES measurements of Ti-doped and undoped LiFePO4 electrodes have been performed to determine the change of Fe valence during the lithium intercalation and de-intercalation processes. Both LiFePO4 and doped LiTi0.01Fe0.99PO4 cathodes demonstrate good electrochemical performance

Synthesis and Characterization of LiFePO4 and LiTi0.01Fe0.99PO4 Cathode Materials

Nanocrystalline LiFePO4 and doped LiTi0.01Fe0.99PO4 powders were synthesized via a sol-gel preparation route. High-resolution tunneling electron microscopy observation and energy dispersive spectroscopy, mapping show the homogeneous distribution of dopant Ti cations in the crystals. Fe and O K -edge X-ray absorption near-edge structure (XANES) measurements show that Ti4+ doping induces an increased unoccupied d-state in LiFePO4, resulting in an enhanced p-type semiconductivity. In situ Fe K -edge XANES measurements of Ti-doped and undoped LiFePO4 electrodes have been performed to determine the change of Fe valence during the lithium intercalation and de-intercalation processes. Both LiFePO4 and doped LiTi0.01Fe0.99PO4 cathodes demonstrate good electrochemical performance

Tungsten Disulfide Nanotubes for Lithium Storage

WS2 nanotubes were synthesized by sintering amorphous WS3 at high temperature under flowing hydrogen. High-resolution transmission electron microscopy observation revealed that the as-prepared WS2 nanotubes have an open end with an inner hollow core of about 4.6 nm. We studied the lithium intercalation behavior of WS2 nanotubes. The WS2 nanotubes demonstrated a stable cyclability in a wide voltage range ~0.1-3.1 V vs. Li/Li1). The nanotubes could provide a new class of electrode materials for lithium-ion batteries