Enhanced rate performance of LiNi_0.5Mn_1.5O₄ fibers synthesized by electrospinning

Spinel LiNi_0.5Mn_1.5O₄ (LNMO) provides a high working potential as a cathode material for lithium-ion batteries. Yet there is a phase transition from cubic to tetragonal structure in LNMO during the ~3V charge/discharge region. To suppress the large volume change and capacity fade inherent with bulk-sized LNMO particles when discharged to below 3.0V, one-dimensional nano-structured LNMO was prepared by an electrospinning method and a subsequent heat treatment. The well-separated nanofiber precursors combat the growth and aggregation of LNMO particles during the heating procedure and lead to improved capacity, better cycling stability, and improved rate capability of the final LMNO nanofibers. The as-prepared LMNO nanofibers have a diameter as thin as 50-100nm, which is the thinnest of this kind of complex compounds that contain multi-transition metal elements produced through the electrospinning method. In coin cell tests of this material at a current density of 27mAg^-1, the initial discharge capacity was 130mAhg^-1 over a voltage range of 3.5-4.8V and 300mAhg^-1 over a voltage range of 2.0-4.8V.