Ultra-Thin Hollow Carbon Nanospheres for Pseudocapacitive Sodium-Ion Storage

Abstract

Ultra-thin hollow carbon nanospheres (UTH-CNs) are fabricated for use as anodes of asymmetric sodium ion pseudocapacitors. The similar to 3 nm thick amorphous carbon walls obtained from regenerated silk proteins as a template exhibit a well-defined porous structure suitable for reversible sodium-ion storage. The UTH-CNs show remarkable electrochemical activity with sodium via a pseudocapacitive reaction, delivering a large reversible capacity as well as superior rate performance for more than 1000 cycles. The pseudocapacitors based on UTH-CNs exhibit a capacitance of 186 Fg(-1), a specific energy of 43 Wh kg(-1) and a power density of 10 kW kg(-1). This represents the highest value yet reported for asymmetric sodium-ion storage pseudocapacitors.