Rearrangement of Pore Structure-Enabled Micropore-Dominant N,O Co-Doped Carbon for Ultrafast Charge/Discharge Rate Supercapacitors at Commercial-Scale Mass Loading

N-doped porous carbon materials possess abundant pores and nitrogen functionalities, holding significant potential for supercapacitors. However, achieving precise control of the pore structure to enhance electrochemical performance remains challenging in the large-scale production of commercial electrode materials. Herein, Chinese yam, a rhizome plant rich in dopamine, is selected as the carbon precursor to prepare N,O-codoped hierarchical porous carbon (N/O-PC-3) via a one-step carbonization and activation process. The pore structure is precisely controlled by adjusting the degree of aggregation of zinc-containing hydrolysates in biomass through the synergistic action of ZnCl2 (activating agent) and NH4Cl (nitrogen source). Due to its micropore-dominant pore structure, high nitrogen (10.5 at. %) and oxygen (13.1 at. %) content, along with good electronic conductivity and excellent wettability, N/O-PC-3 exhibits remarkable frequency response, with an ultrahigh rate of up to 5 V s–1 and high gravimetric, volumetric, and areal capacitances of 414 F g–1, 311 F cm–3, and 23.8 μF cm–2 at 1 A g–1, respectively. It also demonstrates excellent rate capability (326 F g–1 at 100 A g–1, 79% capacitance retention). Even at an ultrahigh mass loading of 15 mg cm–2, N/O-PC-3 achieves a high gravimetric capacitance of 223 F g–1. The assembled N/O-PC-3 symmetric supercapacitor delivers an energy density of 22.9 W h kg–1 at a power density of 102.9 W kg–1, making it highly desirable for practical application in energy storage. Additionally, this work offers a straightforward approach to precisely controlling pore structure in carbon materials.

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