EDTA as chelating agent for sol-gel synthesis of spinel LiMn2O4 cathode material for lithium batteries

Abstract

Ethylene diamine tetra-acetic acid (EDTA) was used to prepare spinel LiMn 2 O 4 at 650 °C. The prepared sample by EDTA (E-LiMn 2 O 4 ) is compared with another spinel sample (C-LiMn 2 O 4 ) prepared by citric acid as a common chelating agent at the higher temperature (800 C) adjusted to obtain the same size and shape of the particles as in (E-LiMn 2 O 4 ) sample, as probed by SEM and TEM images. Investigation of both samples by X-ray diffraction showed that both samples have the single phase cubic spinel LiMn 2 O 4 phase with space group Fd-3m. Vibration properties obtained from Raman scattering (RS) and Fourier Transform Infra-Red (FTIR) spectroscopy for both samples are identical with spinel LiMn 2 O 4 structure. 7 Li MAS NMR and XPS spectra show that the amount of Mn 4+ is larger in LiMn 2 O 4 sample prepared by citric acid. LiMn 2 O 4 sample prepared using EDTA as chelating agent has better structural properties, but the improvement of the electrochemical properties is much smaller than the results reported in the literature for lamellar compounds and silicate materials. This is attributed to the features specific to the spinel, which limit both the capacity and cycle ability: dissolution of manganese and Jahn-Teller distortions associated to Mn 3+ ions, that are not modified by the choice of chelating agent.

Facile one step synthesis method of spinel LiMn2O4 cathode material for lithium batteries

“…The lattice parameters of LiMn 2 O 4 calcined at 750 °C and 900 °C were calculated through the least square method using 10 well defined diffraction lines with indexation in the cubic spinel structure and the results are listed in Table 1. The slight increasing in lattice parameter a upon rising the temperature is matched well with our previous work [22] and with result reported by Lee et al., [23]. To describe the variation of the crystallity size and quantify the local lattice strain of the two samples, Scherer's formula and the full width at maximum (FWHM) for different peaks especially (400) peak (because this peak is sensitive to calcinations temperature) are used, the data are summarized in Table 1.…”

“…As the calcinations temperature was getting higher, the main diffraction peaks of cubic spinel phase, such as (111), (311), and (400), were well developed. This means that lithium ions occupied tetrahedral 8 a sites (Wyckoff notation) and manganese occupied octahedral 16 d sites, while oxygen atoms are located at 32 e sites [22]. The lattice parameters of LiMn 2 O 4 calcined at 750 °C and 900 °C were calculated through the least square method using 10 well defined diffraction lines with indexation in the cubic spinel structure and the results are listed in Table 1.…”

Kinetic and Thermodynamic Studies on Synthesis of Mg-Doped LiMn2O4 Nanoparticles

“…This is due to differences in ion radius between Mn 3+ (0.645 Å) and Mn 4+ (0.53 Å) ions. When Mg 2+ is doped at Mn 3+ site of the spinel structure, the number of Mn 4+ ions increases in order to maintain charge balance condition resulting in an increase in average Mn valence ( Figure 6 b), which suppresses Jahn-Teller distortion [ 85 , 86 ]. Therefore, as shown in Figure 6 b, lattice parameter “a” of the unit cell decreased with increasing magnesium content.…”

Estimating the cost and energy demand of producing lithium manganese oxide for Li-ion batteries

“…They used a mixture of lithium acetate, manganese acetate tetrahydrate, and citric acid along with lithium hydroxide monohydrate and manganese nitrate tetrahydrate as raw materials. Hashem et al [17] suggested using lithium and manganese acetate dissolved in distilled water with citric acid and ethylene diamine tetra-acetic acid (EDTA) as fuels for a sol-gel based synthesis of spinel-type LMO. In another sol-gel type synthesis method, Barboux et al [18] proposed to heat an aqueous solution of lithium hydroxide (LiOH) and manganese acetate (Mn(CH3COO)2) in ammonium hydroxide (NH4OH).…”