Sodium metal hybrid capacitors based on nanostructured carbon materials

In this study, sodium metal hybrid capacitors (SMHCs) composed of a metal anode and capacitive cathode are reported for the first time. The sodium metal anode was designed using catalytic carbon nanotemplates (C-CNTPs) and exhibited highly reversible sodium metal plating/stripping behaviors with an average Coulombic efficiency of similar to 100% over 1000 galvanostatic cycles and significantly low cell-to-cell variations. Further, nanoporous pyroproteins (N-PPts) with a specific surface area of similar to 4216 m(2) g(-1) and pore volume of 1.937 cm(3) g(-1) were fabricated as the capacitive cathode, exhibiting a high specific capacity of 168 mA h g(-1), high rate capability of 0.5-10 A g(-1), and stable cycling performance over 1000 cycles. The SMHCs based on C-CNTPs/N-PPts were operated in a voltage window of 1.0-4.0 V, delivering a high specific energy of similar to 237.7 Wh kg(-1) at similar to 462 W kg(-1) and a maximum power of similar to 4800 W kg(-1) at similar to 66.7 Wh kg(-1). In addition, stable cycling performance was maintained during 500 cycles, with a capacity retention of similar to 82%.