Potassium acetate activation strategy for synthesizing multiple heteroatom-doped porous carbons containing 2D nanosheets from polybenzoxazine for supercapacitor applications

Ultrathin 2D porous carbon nanosheets are superior candidates for the electrode of carbon-based supercapacitor (C-SCs), due to its short ion diffusion distance and rapid electron transfer within the 2D layers than particulate carbon. However, most methods for synthesizing 2D nanosheets are complex and time-consuming. So, preparing 2D nanosheets using a simple method is still challenging. In our work, we employed a simple salt-based method to prepare porous carbon containing graphene-like nanosheets (PCCGNs) using sulfur-containing polybenzoxazine as carbon source and potassium acetate (CH3COOK) as an activator. The resulting 2D nanosheets in PCCGNs not only displays a large aspect ratio, a smooth surface with some wrinkle, ultrathin thickness (5 nm), and a larger specific surface area (up to 1425 m2 g−1), but also has a higher concentration of oxygen atoms on the surface by both in-situ and ex-situ strategies. The specific capacitance of PCCGNs-1:4 in the three-electrode system reaches 151F g−1, demonstrating its high electrochemical performance. Also, it has an excellent rate capability (up to 78.1 %), surpassing that of PCs-1:1without nanosheets structure (73.9 %). When assembled into a symmetrical supercapacitor device, PCCGNs show excellent cycling stability. At a power density of 250 W kg−1, the energy density of the capacitor reaches 3.37 Wh kg−1. These results demonstrate PCCGNs is a superior candidate for electrochemical energy storage applications.