Preparation and Characterization of Ultralong Spinel Lithium Manganese Oxide Nanofiber Cathode via Electrospinning Method

Aim ng at improving the high rate capability of spinel lithium manganese oxide (LiMn 2 O 4 ) cathode, ultralong LiMn 2 O 4 nanofibers are prepared by combination of electrospinning and sol-gel techniques. The effect of processing parameters, including the weight ratio of polyvinylpyrrolidone (PVP) to Li and Mn precursor, calcination temperature and time, on the morphology and the resultant cathode performance of spinel LiMn 2 O 4 nanofiber cathodes have been systematically investigated. Thermal behavior of LiMn 2 O 4 precursor nanofibers is performed on a differential scanning calorimetry-differential thermal analysis (DSC-DTA), indicating the spinel LiMn 2 O 4 began forming at 513 °C. The cathode materials appear porous “network-like” morphology with nanosize in diameter (∼170 nm), microsize in length (∼20 μm) and pure spinel structure, confirmed by scanning electron microscopy (SEM) and X-ray diffractometer (XRD). The ultralong LiMn 2 O 4 nanofiber cathode calcined at 700 °C for 8 h shows highest capacity and best rate capability. Its discharge capacity is 146 mAh g −1 at 0.1 C; more importantly, the discharge capacities are 112 mAh g −1 , 103 mAh g −1 and 92 mAh g −1 at high discharge rates of 10 C, 20 C and 30 C, respectively.