Flexible Carbon Nanofibrous Membranes with Adjustable Hierarchical Porous Structure as High-Capacity Anodes for Sodium-Ion Batteries

Preparation of porous carbon nanofibrous membranes with excellent flexibilities and high Na ion storage capabilities to satisfy the demand of wearable energy storage devices remains challenging. Herein, a continuous and flexible porous carbon nanofibrous membrane is developed as anode material for sodium-ion batteries by electrospinning a mixture of polyacrylonitrile (PAN) and ultrafine zeolitic imidazolate framework (ZIF-8) nanoparticles, followed by carbonization at 1200 degrees C. The intrinsic porous crystal structure of ZIF-8 and their decomposition/volatilization at high temperature assist the generation of hierarchical micro-meso pores that are homogeneously dispersed along the nanofibers, resulting in the good flexibility and excellent Na ion storage performance. Through controlling the ZIF-8 content at 45%, the flexible anode enables a superior Na storage capacity of 418 mA h g(-1) at 0.1 A g(-1) with a remarkable plateau capacity of 278 mA h g(-1). The superhigh plateau capacity could be credited to the large amounts of isolated closed micro-meso pores, implying an adsorption-filling sodium-ion storage mechanism. These findings provide some inspiration for the design and construction of advanced porous carbon anode materials for flexible sodium-ion batteries.