An Ultrafast Rechargeable Hybrid Sodium-Based Dual-Ion Capacitor Based on Hard Carbon Cathodes

Hybrid sodium-based dual-ion capacitors (NDICs), which integrate the advantages of supercapacitors and sodium-ion batteries, have attracted tremendous attention recently. In this work, hybrid sodium-based dual-ion capacitors are successfully developed with nitrogen-doped microporous hard carbon as the cathode and soft carbon as the anode. N-doping is beneficial to the functional groups, porous structure, and electric conductivity of hard carbon. Hybrid NDICs possess a wide voltage range (0.01-4.7 V), high-energy density of 245.7 W h kg(-1) at a power density of 1626 W kg(-1), long cycle life (1000 cycles), and outstanding rate performance.