Synthesis and electrochemical characterization of duo doped spinels (zinc and praseodymium) for use in lithium rechargeable batteries

Abstract

LiMn₂O₄ and LiZn_xPr_yMn_2−x−yO₄ (x = 0.10–0.24; y = 0.01–0.10) powders have been synthesized by sol–gel method using palmitic acid as chelating agent. The synthesized samples have been subjected to thermo gravimetric and differential thermal analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDAX). The sol–gel route bestows low calcination temperature, shorter heating time, high purity, good control over stoichiometry, small particle size, high surface area, good surface morphology and better homogeneity, The XRD patterns reveal high degree of crystallinity and better phase purity. SEM and TEM images exhibit nano-sized nature particles with good agglomeration. EDAX peaks of Zn, Pr, Mn and O have been confirmed in actual compositions of LiMn₂O₄ and LiZn_xPr_yMn_2−x−yO₄. Charge–discharge studies of pristine spinel LiMn₂O₄ heated at 850 °C delivers discharge capacity of 132 mA h g⁻¹ corresponding to columbic efficiency of 73 % during the first cycle. At the end of 10th cycles, it delivers maximum discharge capacity of 112 mA h g⁻¹ with columbic efficiency of 70 % and capacity fade of 0.15 mA h g⁻¹ cycle⁻¹ over the investigated 10 cycles. Inter alia, all dopants concentrations, LiZn_0.10Pr_0.10Mn_1.80O₄ exhibits the better cycling performance (1st cycle discharge capacity: 130 mA h g⁻¹ comparing to undoped spinel 132 mA h g⁻¹) corresponding to columbic efficiency of 73 % with capacity fade of 0.12 mA h g⁻¹ cycle⁻¹.