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

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 (5214 m2 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 6 mg cm−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 20000 W kg−1 and robust cycle stability overcoming those of a typical battery.

Keywords

• dual‐carbon sodium‐ion hybrid capacitors
• high energy densities, fast chargeable power densities, and robust cycle stabilities
• metal‐azolate frameworks
• porous nitrogen‐doped graphitic carbon anodes
• ultrahigh surface area porous oxygen‐doped graphitic carbon cathodes