Beschreibung:
Hard carbon nanofibers derived from electrospinning polyacrylonitrile (PAN) features low-cost and simple preparation advantages but possesses low plateau capacity, limiting its application as anode for the sodium ion (Na + ) storage technologies. The main obstacle is the cyclization of PAN during stabilization leads to the formation of ordered carbon structures. Herein, nanofibers anodes with disordered structures and abundant internal nanopores are fabricated by using carboxyl-functionalized PAN. Due to the cyan (–CN) of PAN turns to sodium carboxylate (–COONa) during the functionalized process, the cyclization of stabilization process is limited and realizing a disordered carbon structure. Meanwhile, the formation of –COONa can lead to hard carbon with abundant internal pores, thereby resulting in an extended plateau region during discharging. The optimized PCNFs2-700-1400 anode delivers a satisfactory reversible capacity of 286 mAh/g at 0.02 A/g with an initial coulombic efficiency (ICE) of 73%. The larger plateau capacity of 183 mAh/g is ascribed to the filling of Na+ in the internal pores and insertion in the pseudo-graphitic. This strategy is expected to help enhance the understanding of Na + storage “adsorption-insertion-pore filling” mechanism in PAN-derived hard carbon