Study the Effect of Different Temperatures on Structural and Morphological Features of Co-Doped LiMnO۴

The spinel compound of LiCo۰.۵Mn۱.۵O۴ (LCMO) was synthesized as cathode active material for lithium–ion batteries by using sol–gel technique in this study. The substance was subjected to a thermo-gravimetric (TGA) study. The sample was calcined in the air for ۱۲ hours at ۷۰۰, ۸۵۰, and ۱۰۰۰ ᵒC to examine differences in structural and morphological features. The thermogravimetry (DTG) curve of sample was fabricated at ۸۵۰ °C. A loss region took place before ۴۰۰ °C related to the evaporation regarding the adsorbed water molecules and the elimination of oxygen-containing functional groups. The powder crystallized in the phase structure space group Fd⋽m and has a random orientation, according to the XRD measurement. The LCMO powder's surface morphology comprises nano-grains crystallite with a homogeneous coverage of the sample surface and randomly oriented grains. LiCo۰.۵Mn۱.۵O۴ synthesized at ۸۵۰°C was taken after one charge/discharge cycle. The interfacial layer resistance, or Rf, is attributed to the impedance of Li+ ion migration through SEI film. From the EIS measurements, the diameter of the semicircle equal to charge transfer resistance, which is approximately ۷۰۰ Ω. The capacity of the charging and discharging were of ۱۲۱ mAhg-۱ and ۱۲۲ mAhg-۱ delivered by the LiCo۰.۵Mn۱.۵O۴ cathode. Likewise, a columbic efficiency of ۹۴% was obtained for the cathode.

Keywords:

Li ion battery , Spinel cathode , Space group , Discharge Capacity , TGA