We report here a rapid, microwave-solvothermal synthesis of graphene nanosheets within few minutes at <300 °C without requiring highly toxic chemicals with strong reducing properties or reducing gas atmospheres at elevated temperatures. The graphene nanosheets produced are decorated with polyaniline nanocomposites and exhibit high charge storage capacity in lithium ion batteries and electrochemical capacitors.
Nanostructured Li2FeSiO4 and Li2MnSiO4 cathodes have been synthesized by a facile microwave-solvothermal synthesis. To improve crystallinity and enhance electronic conductivity, the resulting samples have been mixed with sucrose and heated at 650 °C for 6 h in argon atmosphere. The Li2MSiO4/C nanocomposites, thus, obtained have been characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, electrochemical measurements, and differential scanning calorimetry. The Li2FeSiO4/C sample exhibits good rate capability and stable cycle life, with discharge capacities of 148 mAh/g at room temperature and 204 mAh/g at 55 °C. Although Li2MnSiO4/C shows higher discharge capacities of 210 mAh/g at room temperature and 250 mAh/g at 55 °C, it suffers from poor rate capability and drastic capacity fade. The disparity in the electrochemical performance and redox behavior between Li2FeSiO4/C and Li2MnSiO4/C can be attributed to the differences in the structural stability of the delithiated phases, Jahn−Teller distortion of Mn3+ ions, Mn dissolution, and electronic conductivity.
A facile microwave-hydrothermal approach has been used to synthesize single-crystalline Fe(3)O(4) nanowires within 15 min at 150 degrees C. The Fe(3)O(4) nanowires, after decorating with carbon, exhibit excellent cyclability and rate performance when employed as an anode in lithium ion batteries.
A facile, high-energy mechanical milling (HEMM) approach has been developed to synthesize carbon-coated olivine LiM1−y
M
y
PO4 (M = Fe, Mn, Co, and Mg) solid solution nanoparticles. A systematic structural and electrochemical characterization of the solid solution series has been carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM), charge−discharge measurements, and galvanostatic intermittent titration technique (GITT). The discharge capacity, voltage profile, and cycle performance of the LiM1−y
M
y
PO4 solid solution cathodes are found to be dependent on the different redox couples involved in the reaction. Equilibrium potentials obtained from GITT and dQ/dV plot reveal a systematic shift in the redox potential of Fe2+/3+, Mn2+/3+, and Co2+/3+ couples in the LiM1−y
M
y
PO4 solid solution compared to their pristine end members (LiMPO4). The shifts in the redox potential are explained on the basis of the changes in the covalency of the M−O bond and M−O−M interaction, and the consequent change in the position of the M2+/3+ redox energy. The self-discharge phenomenon of the Co2+/3+ couple in LiM1−y
Co
y
PO4 has also been investigated by electrochemical impedance spectroscopy.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.