High Performance Nanofiber Electrodes for Li-Ion Batteries Using Particle Polymer Electrospinning

Particle/polymer electrospinning was used to prepare (i) fiber mat anodes containing carbon powder and pol(vinylidene fluoride) and (ii) fiber mat cathodes containing LiCoO₂ nano-particles, carbon powder, and poly(vinylidene fluoride) for Li-ion batteries. Unlike previous work on electrospun LiCoO2 nanofibers prepared using sol-gel chemistry and high temperature processing, the particle/polymer fiber mat cathodes reported here were made thick with a high fiber volume fraction for high areal and volumetric capacities at fast charge/discharge rates (e.g., 0.81 mAh cm^-2 and 62 mAh cm^-3 at 2C) which were much greater than that of a slurry cast cathode of the same composition (0.004 mAh cm^-2 and 0.30 mAh cm^-3 at 2C). Full cells containing a LiCoO₂/C/PVDF fiber mat cathode and C/PVDF fiber mat anode were also prepared and characterized. These electrospun batteries exhibited a high energy density of 144Wh kg^-1 at 0.1C and an areal capacity of 1.03 mAh cm^-2 at 1C. The excellent performance of the electrospun particle/polymer cathodes and anodes is attributed to electrolyte penetration throughout the 3D fiber electrode mats, a large electrode/electrolyte interfacial area, and short Li+ transport pathways between the electrolyte and active material nanoparticles in the radial fiber direction.