Citric Acid Assisted Sol Gel Research Articles

Fabrication and characterization of nanosized single-crystalline LiNi 0.5Mn 0.5O 2

Layered single-crystalline LiNi 0.5Mn 0.5O 2 nanostructures were synthesized through a citric acid-assisted sol–gel method. The results of XPS match well with the expected stoichiometric formula Ni 0.5 IIMn 0.5 IV. Electrochemical tests show that it delivers a large discharge capacity of 160.7 mA h g −1 vs. Li metal at 0.2 mA cm −2 (voltage window 2.5–4.5 V).

Citric acid-assisted sol–gel synthesis of nanocrystalline LiMn 2O 4 spinel as cathode material

Nanocrystalline LiMn 2O 4 spinel was synthesized by a sol–gel method using citric acid as a chelating agent at the calcination temperature of 600°C for 10 h. The as-prepared LiMn 2O 4 was investigated by a variety of techniques, including X-ray powder diffraction, transmission electron microscopy (TEM), and X-ray photoelectron spectra. TEM images indicated that the average crystallite size is about 40 nm with a fairly narrow size-distribution. Results showed that the calcination temperature and the calcination time played significant roles in the formation of nanocrystalline LiMn 2O 4. A possible mechanism on the formation of the nanocrystallites was also discussed.

Studies of LiNi0.6Co0.4O2 Cathode Material Prepared by the Citric Acid-Assisted Sol-Gel Method for Lithium Batteries

The layered LiNi0.6Co0.4O2 powders were synthesized at low temperature by a sol-gel method using citric acid as a chelating agent. Submicron-sized particles of the precursor were obtained at temperature below 400°C and microcrystalline powders were grown by thermal treatment at 700°C for 4 h in air. The carboxylic-based acid acted such as a fuel, decomposed the homogeneous precipitate of metal complexes at low temperature, and yielded the free impurity LiNi0.6Co0.4O2 single-phase suitable for electrochemical application. The synthesized products have been characterized by structural (XRD, SEM), spectroscopic (FTIR, Raman) and thermal (DTA/TG) analyses. Raman and FTIR measurements provide information on the local environment of the cationic sublattice of LiNi0.6Co0.4O2 solid solution. Electrochemical performance of the synthesized products in rechargeable Li cells were evaluated by employing as cathodes in non-aqueous organic electrolyte mixture of 1M LiPF6 in EC + DMC. The electrochemical behaviour of synthesized LiNi0.6Co0.4O2 is discussed in relation with its synthesis procedure.