Design of honeycomb-like hierarchically porous carbons with engineered mesoporosity for aqueous zinc-ion hybrid supercapacitors applications

Aqueous zinc-ion hybrid supercapacitors (ZHSCs) have aroused extensive research attention in the field of electrochemical energy storage. However, the practical application of ZHSCs is severely limited by their poor rate performance, which is mainly owing to the large hydrated zinc ions radius and high desolvation free energies. Herein, we have designed an efficient route for the environment-friendly production of 3D honeycomb-like hierarchically porous carbons (HHPCs) with high specific surface and tunable porosity, using commercial magnesium oxide microparticles as a template and potassium bicarbonate as the activator. Different from previous works, the magnesium oxide microparticles displayed not only aggregation-free and low-cost but also good structural stability, which plays key roles to achieve the unique 3D honeycomb-like hierarchically structures. Benefiting from the large surface, high mesopore content, and honeycomb-like hierarchically structures, the HHPC-6 sample demonstrates desired electrochemical performance as the cathode for ZHSCs, with the largest specific capacity up to 147 mAh g−1 at 0.2 A g−1, impressive rate performance (48.3% of capacity retention at 50 A g−1), ultrahigh specific power (40 kW kg−1 at 56.7 Wh kg−1). This strategy will offer a guiding function into the fabrication of nanocarbons for ZHSCs application.