Porous carbon derived from biomass represents pivotal electrode materials for electric double-layer capacitors (EDLCs). However, their applications are limited by the low pore utilization and low withstanding voltage (< 2.7 V), which largely hinder the energy density (Eg) of SCs. In this study, fulvic acid-derived porous carbons (FPs) were synthesized through the self-assembly and KOH activation strategy by employing fulvic acid (FA) as the precursor and cationic surfactant PDDA as the soft template. The electrostatic forces between FA and PDDA enable the structural orientation of FA, leading to the formation of stable layered liquid microcrystals. Besides, under the activation process, the decomposition of PDDA contributes to the interconnected pores in FPs. Thus, the obtained sample FP1 exhibits a high specific surface area (2593 m2 g− 1) and high mesopore ratio (48%). Moreover, low oxygen content and stable surface composition promote the withstanding voltage of FPs. In the TEABF4/ PC electrolyte, the sample FP1 is capable of a high voltage of 3.0 V, high-rate capability C10/0.05 of 76.3%, and high energy density of 39 Wh kg− 1.

Biomass-based hierarchical porous carbon with highly connected pores for high energy density EDLCs
    Abstract
    1 Introduction
    2 Experimental
        2.1 The preparation of FPs
        2.2 Electrochemical measurements
    3 Results and discussion
        3.1 The formation mechanism of FPs
        3.2 The microstructure of FPs
        3.3 Microcrystalline structure of FPs
        3.4 Chemical composition of FPs
        3.5 Electrochemical properties of FPs
    4 Conclusion
    Acknowledgements 
    References

• Zejia Chen(Laboratory of New Energy and Environmental Catalysis, School of Biological and Chemical Engineering, Guangxi University of Science and Technology, Liuzhou 545006, Guangxi, China)
• Linze Li(Laboratory of New Energy and Environmental Catalysis, School of Biological and Chemical Engineering, Guangxi University of Science and Technology, Liuzhou 545006, Guangxi, China)
• Jirui Wang(Laboratory of New Energy and Environmental Catalysis, School of Biological and Chemical Engineering, Guangxi University of Science and Technology, Liuzhou 545006, Guangxi, China)
• Jinshi Dong(Laboratory of New Energy and Environmental Catalysis, School of Biological and Chemical Engineering, Guangxi University of Science and Technology, Liuzhou 545006, Guangxi, China)
• Panpan Chang(Laboratory of New Energy and Environmental Catalysis, School of Biological and Chemical Engineering, Guangxi University of Science and Technology, Liuzhou 545006, Guangxi, China) Corresponding author
• Ting Yang(Department of Applied Chemistry, Yuncheng University, Yuncheng 044000, China)
• Jizong Zhang(eFlion Power Incorporated, Shanghai 201306, China)
• Ranran Ding(College of Chemistry and Environment, Hohhot Minzu College, Hohhot 010051, China)