3D Porous Oxygen-Doped and Nitrogen-Doped Graphitic Carbons Derived from Metal Azolate Frameworks as Cathode and Anode Materials for High-Performance Dual-Carbon Sodium-Ion Hybrid Capacitors.

Abstract

Sodium-ion hybrid capacitors (SIHCs) in principle can utilize the advantages of batteries and supercapacitors and satisfy the cost demand of large-scale energy storage systems, but the sluggish kinetics and low capacities of its anode and cathode are yet to be overcome. Here, a strategy is reported to realize high-performance dual-carbon SIHCs using 3D porous graphitic carbon cathode and anode materials derived from metal-azolate framework-6s (MAF-6s). First, MAF-6s, with or without urea loading, are pyrolyzed to synthesize MAF-derived carbons (MDCs). Then, cathode materials are synthesized via the controlled KOH-assisted pyrolysis of MDCs (K-MDCs). K-MDCs, 3D graphitic carbons, resulting in a record-high surface area (5214m2 g-1 ) being ≈four-fold higher than pristine MAF-6, oxygen-doped sites for high capacity, rich mesopores affording fast ion transport, and high capacity retention over 5000 charge/discharge cycles. Moreover, 3D porous MDC anode materials are synthesized from N-containing MAF-6 and exhibited to allow cycle stability over 5000 cycles. Furthermore, dual-carbon MDC//K-MDC SIHCs with different loadings (3 to 6mgcm-2 ) are demonstrated to achieve high energy densities exceeding those of sodium-ion batteries and supercapacitors. Additionally, it allows an ultrafast-chargeable high power density of 20000Wkg-1 and robust cycle stability overcoming those of a typical battery.