Precisely tuning porosity and outstanding supercapacitor performance of phenolic resin-based carbons via citrate activation

Developing a facile, inexpensive, and efficient approach for preparing porous carbon materials with high electrochemical properties is critical to the commercial viability of supercapacitors (SCs). Herein, a novel hierarchical porous carbon with extraordinary SCs performance is developed via a two-step carbonization process by employing low-temperature self-made phenolic resin as raw materials. Therein, the introduction of citrate is the key to generate distinct configurations and obtain high electrochemical properties. Particularly, the potassium citrate and sodium citrate (mass ratio of 3:1) activated sample (RFN-KNa) exhibits large specific surface area (1089.78 m2 g−1), high nitrogen content (2.91 at.%) and outstanding specific capacitance (280 F g−1 at 1 A g−1). Additionally, the RFN-KNa-based symmetric SCs also possesses ultrahigh energy densities, which are found to be 24.79 Wh kg−1 (at 900.1 W kg−1) and 17.42 Wh kg−1 (at 703.4 W kg−1) in 1 M Na2SO4 and 6 M KOH electrolyte, respectively. Meanwhile, the SCs also displays eminent rate capability and cycle stability. This work offers a new insight for preparing hierarchical porous carbon materials and opens up a new avenue for applying resin materials in the field of energy storage.