Preparation of LiMn_2O_4 by A Solution Combustion Synthesis Using Acetic Salts and Acetic Acid as Starting Materials

摘要

Spinel LiMn_2O_4 was synthesized by a solution combustion synthesis using lithium and manganese acetate as raw materials and acetic acid as fuel. The phase composition and micro morphology of the as-prepared products were determined by X-ray diffraction (XRD) and scanning electric microscope (SEM). The electrochemical performance of the products was tested by using a coin-type half battery versus lithium metal foil as anode material. XRD analysis suggested that the main phase of the products was LiMn_2O_4, but there was little impurity Mn_2O_3 in the products. The relative content of Mn_2O_3 was decreased gradually when the molar ratio of Li:Mn: acetic acid increased from 0.5:1:0.5 to 0.5:1:2, but increased again when the molar ratio of Li:Mn: acetic acid was 0.5:1:2.5. The purest product could be prepared when the molar ratio of Li:Mn: acetic acid=0.5:1:2. SEM investigation indicated that the typical crystal structure could not be investigated from the as-prepared products, and the particles were badly agglomerated. Electrochemical performance tests indicated that the specific capacity of the purest product was 108mAh/g. After 30 cycles, the capacity faded only 22% at the current density of 50mA/g, and the average charge/discharge efficiency was ～96%. At the current density of 75mA/g, the initial specific capacity of the purest product was only 72mAh/g, but after 30 cycles, the capacity retention was >92%, exhibiting a good cycling performance.