Iron\nPhosphide Confined in Carbon Nanofibers as a\nFree-Standing Flexible Anode for High-Performance Lithium-Ion Batteries

Abstract

Iron\nphosphide with high specific capacity has emerged as an appealing\ncandidate for next-generation lithium-ion battery anodes. However,\niron phosphide could undergo conversion reactions and generally suffer\nfrom a rapid capacity degradation upon cycling due to its structure\npulverization. Chemomechanical breakdown of iron phosphide due to\nits rigidity has been a challenge to fully realizing its electrochemical\nperformance. To address this challenge, we report here on an enticing\nopportunity: a flexible, free-standing iron phosphide anode with Fe₂P nanoparticles confined in carbon nanofibers may overcome\nexisting challenges. For the synthesis, we introduce a facile electrospinning\nstrategy that enables in situ formation of Fe₂P within\na carbon matrix. Such a carbon matrix can effectively minimize the\nstructure change of Fe₂P particles and protect them from\npulverization, allowing the electrodes to retain a free-standing structure\nafter long-term cycling. The produced electrodes showed excellent\nelectrochemical performance in lithium-ion half and full cells, as\nwell as in flexible pouch cells. These results demonstrate the successful\ndevelopment of iron phosphide materials toward high capacity, light\nweight, and flexible energy storage.