Synthesis of Nano- and Micro-Particles of LiMn2O4: Electrochemical Investigation and Assessment as a Cathode in Li Battery

Abstract

Micro- and nano-particles of LiMn2O4 are synthesized from micro- and nano-particles of MnO2, respectively. Synthesis of MnO2 in the presence of stirrer leads to micro-particles, however, in the presence of ultrasonic waves nano-particles obtained. Both micro- and nano-particles prepared are converted to LiMn2O4. The products are characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and measurement of surface area (BET). The electrochemical properties of these materials as a cathode in a lithium battery are examined by using the cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge/discharge tests. The obtained voltammograms show a pair of oxidation peaks and a pair of reduction peaks with better reversibility for nano-particles. Nyquist plots show lower charge transfer resistance for nano-particles compared with micro-one. Battery charge and discharge test is carried out at different constant currents. It is found that the LiMn2O4 micro- and nano-particles deliver 85 and 146 mAh g−1 (3.0–4.5 V) in the first cycle and 62 and 141 mAh g−1 discharge capacity after 50 cycles, respectively. The micro-particles suffer from capacity fading but the nano-particles show much improved capacity retention (24%). LiMn2O4 nano-particles exhibit the better rate of performance in comparison with the micro-one.