Influence of ammonium hydroxide solution on LiMn2O4 nanostructures prepared by modified chemical bath method

Abstract

LiMn2O4 (LMO) powders were prepared by modified chemical bath deposition (CBD) method by varying ammonium hydroxide solution (AHS). The volume of the AHS was varied from 5 to 120mL in order to determine the optimum volume that is needed for preparation of LMO powders. The effect of AHS volume on the structure, morphology, and electrochemical properties of LMO powders was investigated. The X-ray diffraction (XRD) patterns of the LMO powders correspond to the cubic spinel LMO phase. It was found that the XRD peaks increased in intensity with increasing volume of the AHS up to 20mL. The estimated average grain sizes calculated using the XRD patterns were found to be in the order of 66 ± 1nm. It was observed that the estimated average grain sizes increased up to 20mL of AHS. The scanning electron microscopy (SEM) results revealed that the AHS volume does not influence the surface morphology of the prepared nano-powders. Elemental energy dispersive (EDS) analysis mapping conducted on the samples revealed homogeneous distribution of Mn and O for the sample synthesized with 120mL of AHS. The UV–Vis spectra showed a red shift with an increase in AHS up 20mL. The cyclic voltammetry and galvanostatic charge/discharge cycle testing confirmed that 20mL of AHS has superior lithium ion kinetics and electrochemical performance.