Electrospun titania-based fibers for high areal capacity Li-ion battery anodes

Electrospinning is utilized to prepare composite fiber Li-ion battery anodes containing titania and carbon nanoparticles with a poly (acrylic acid) binder. The electrospun material exhibits a stable charge/discharge capacity with only 5% capacity fade over 450 cycles at 0.5 C. Compared to a conventional slurry cast electrode of the same composition, the electrospun anode demonstrates 4-fold higher capacity retention (31% vs. 7.9%) at a charge/discharge rate of 5 C. Electrospinning is also used to prepare ultrathick anodes (>1 mm) with areal capacities up to 3.9 mAh cm^-2. Notably, the thick electrodes exhibit areal capacities of 2.5 and 1.3 mAh cm^-2 at 1 C and 2 C, respectively. Electrospun anodes with densely packed fibers have a 2 C volumetric capacity which exceeds that of the slurry cast material (21.2 and 17.5 mAh cm^-3, respectively). The excellent performance of the electrospun anodes is attributed to interfiber voids which provide complete electrolyte intrusion, a large electrode/electrolyte interface, and short Li⁺ transport pathways between the electrolyte and titania nanoparticles.