High Performance Particle/Polymer Nanofiber Anodes for Li-ion Batteries using Electrospinning

Electrospun nanofiber mats containing carbon nanoparticles in a poly(vinylidene fluoride) binder were prepared and characterized as Li-ion battery anodes. The mats exhibited an initial capacity of 161 mAh g^-1 with 91.7 % capacity retention after 510 cycles at 0.1 C (1 C=372 mA g_carbon^-1). Whereas many nanoscale electrodes are limited to low areal and/or volumetric capacities, the particle/polymer nanofiber anodes can be made thick with a high fiber volume fraction while maintaining good rate capabilities. Thus, a nanofiber anode with a fiber volume fraction of 0.79 exhibits a volumetric capacity of 55 mAh cm^-3 at 2 C, which is twice that of a typical graphite anode. Similarly, thick nanofiber mats with a high areal capacity of 4.3 mAh cm^-2 were prepared and characterized. The excellent performance of electrospun anodes is attributed to electrolyte intrusion throughout the interfiber void space and efficient Li⁺ transport between the electrolyte and carbon nanoparticles in the radial fiber direction. Anode mats: Particle/polymer electrospinning is used to prepare nanofiber Li-ion battery anodes containing carbon nanoparticles and a poly(vinylidene fluoride) binder. Thick, densely-packed nanofiber mats exhibit superior areal and volumetric capacities compared to slurry-cast anodes. The excellent performance of electrospun anodes is attributed to interfiber voids and efficient Li⁺ transport between the electrolyte and carbon nanoparticles.