Optimization of the Thermal Treatment of Electrospun Poly(acrylonitrile) for Flexible, Binderless, and Collectorless Lithium-Ion Carbon Nanofibers Anode

The processing of carbon nanofibers prepared by electrospinning poly(acrylonitrile) and subsequent thermal treatment has been optimized for use as a binderless, flexible, and collectorless anode for lithium ion batteries.  Previous literature has failed to report, and in some instances account for, all aspects of processing as they relate to specific capacity in a comprehensive and systematic study.  Solutions of 12 wt% poly(acrylonitrile) in DMF were used throughout and were electrospun and thermally treated using various approaches.  The highest specific capacity obtained after 10 cycles at a current of 100 mA/g was greater than 550 mAh/g and exhibited Coulombic efficiencies of < 98% after the first cycle.  This specific capacity is <30% higher than previously reported anodes cycled at half of the reported current (50 mA/g) and almost 200 mAh/g higher than the theoretical capacity of pure graphite (372 mAh/g).  Flexible carbon nanofibers prepared by this scalable method have been shown to be a viable binderless and collectorless lithium ion anode material.  Applying these concepts to carbon nano-composite anodes previously reported in literature would further enhance their energy and power densities.