Glutamic acid-assisted sol-gel synthesis of multi-doped spinel lithium manganate as cathode materials for lithium rechargeable batteries

LiMn2O4 and LiMgxSnyAlzMn2-x-y-zO4 (x, y, z= Mg, Sn, Al) (x =0.01-0.09; y=0.04-0.1; z = 0.35-0.20) powders have been synthesized via the sol-gel method for the first time using glutamic acid as the chelating agent. The synthesized samples have been subjected to physical and electrochemical characterization. SEM images of parent LiMn2O4 show that the majority of the grains are 1 mu m in size. The LiMg0.01Sn0.04Al0.35Mn1.6O4 and LiMg0.04Sn0.06Al0.30Mn1.6O4 particles present a low degree of agglomeration and the primary particles are 1 mu m in size. TEM images of the spinel LiMn2O4 and LiMgxSnyAlzMn2-x-y-zO4 ascertain that the synthesized particles are nano-sized with uniform surface morphology. The LiMn2O4 samples calcined at 850 degrees C deliver a discharge capacity of 122 mAh g(-1) in the first cycle. Among the compositions investigated. LiMg0.01Sn0.06Al0.30Mn1.6O4 delivers 115 mAh g(-1) in the first cycle and exhibits stable cycling performance with a low capacity fade of 1 mAhg(-1) cycle(-1) over the 10 cycles investigated. (C) 2011 Elsevier Ltd. All rights reserved.