High-performance spinel-rich Li1.5MnTiO4+δ ultralong nanofibers as cathode materials for Li-ion batteries

摘要

Recently, composite materials based on Li-Mn-Ti-O system were developed to target low cost and environmentally benign cathodes for Li-ion batteries. The spinel-layered Li1.5MnTiO4+δ bulk particles showed excellent cycle stability but poor rate performance. To address this drawback, ultralong nanofibers of a Li1.5MnTiO4+δ spinel-layered heterostructure were synthesized by electrospinning. Uniform nanofibers with diameters of about 80?nm were formed of tiny octahedral particles wrapped together into 30?μm long fibers. The Li1.5MnTiO4+δ nanofibers exhibited an improved rate capability compared to both Li1.5MnTiO4+δ nanoparticles and bulk particles. The uniform one-dimensional nanostructure of the composite cathode exhibited enhanced capacities of 235 and 170?mAh g?1 at C/5 and 1?C rates, respectively. Its unique structure provided a large effective contact area for Li+ diffusion, and low charge transfer resistance. Moreover, the layered phase contributed to its capacity in over 3?V region, which increased specific energy (726?Wh?kg?1) compared to the bulk particles (534?Wh?kg?1).