Flexible Nanofiber-Reinforced Solid Polymer Lithium-Ion Battery

Herein, the new concept of an all-nanofiber-reinforced multifunctional battery is developed and demonstrated. The conventional liquid electrolyte, polymer separator, and powder-based cathode are replaced by a nanofiber-enhanced solid polymer electrolyte and carbon nanotube (CNT) fabric conformably coated with an active cathode material. Chemical vapor deposition (CVD) of iron phosphate (FePO4) is selected for the cathode fabrication in this first demonstration. Oxide nanofibers in the polymer electrolyte greatly enhance the electrochemical stability of the electrolyte and resistance to Li dendrite shortening at higher current densities. In addition, the oxide nanofibers increase the polymer mechanical strength and strain by 20-30%. The stand-alone CNT@FePO4 cathode infiltrated with the polymer electrolyte exhibits more than five times higher modulus of toughness than that of the Al current collector. The as-produced structural battery based on these fabricated components exhibits exceptional stability with no signs of performance decay at 50 degrees C, thus demonstrating great promise of the new architecture for a broad range of multifunctional and flexible battery applications.