Biomass carbon materials with high rate capacity have great potential to boost supercapacitors with cost effective, fast charging– discharging performance and high safety requirements, yet currently suffers from a lack of targeted preparation methods. Here we propose a facile FeCl3 assisted hydrothermal carbonization strategy to prepare ultra-high rate biomass carbon from apple residues (ARs). In the preparation process, ARs were first hydrothermally carbonized into a porous precursor which embedded by Fe species, and then synchronously graphitized and activated to form biocarbon with a large special surface area (2159.3 m2 g− 1) and high degree of graphitization. The material exhibited a considerable specific capacitance of 297.5 F g− 1 at 0.5 A g− 1 and outstanding capacitance retention of 85.7% at 10 A g− 1 in 6 M KOH, and moreover, achieved an energy density of 16.2 Wh kg− 1 with the power density of 350.3 W kg− 1. After 8000 cycles, an initial capacitance of 95.2% was maintained. Our findings provide a new idea for boosting the rate capacity of carbon-based electrode materials.

    Abstract
    1 Introduction
    2 Experimental section
        2.1 Chemicals and materials
        2.2 Preparation of AR-derived porous carbon
        2.3 Electrochemical characterization
        2.4 Characterization
    3 Results and discussion
        3.1 Characterization of ARs-derived carbon materials
        3.2 Electronic performance of the ARs-derived carbon in a three-electrode system
        3.3 Electronic performance of the assembled symmetrical supercapacitor
    4 Conclusion
    Acknowledgements 
    References

• Qiqi Li(Shandong Key University Laboratory of High Performance and Functional Polymer, School of Chemistry and Materials Science, Ludong University)
• Yingnan Zhang(Shandong Key University Laboratory of High Performance and Functional Polymer, School of Chemistry and Materials Science, Ludong University)
• Ya Song(Shandong Key University Laboratory of High Performance and Functional Polymer, School of Chemistry and Materials Science, Ludong University)
• Huawei Yang(Shandong Key University Laboratory of High Performance and Functional Polymer, School of Chemistry and Materials Science, Ludong University)
• Lixia Yang(Shandong Key University Laboratory of High Performance and Functional Polymer, School of Chemistry and Materials Science, Ludong University)
• Liangjiu Bai(Shandong Key University Laboratory of High Performance and Functional Polymer, School of Chemistry and Materials Science, Ludong University)
• Donglei Wei(Shandong Key University Laboratory of High Performance and Functional Polymer, School of Chemistry and Materials Science, Ludong University)
• Wenxiang Wang(Shandong Key University Laboratory of High Performance and Functional Polymer, School of Chemistry and Materials Science, Ludong University)
• Ying Liang(Shandong Key University Laboratory of High Performance and Functional Polymer, School of Chemistry and Materials Science, Ludong University)
• Hou Chen(Shandong Key University Laboratory of High Performance and Functional Polymer, School of Chemistry and Materials Science, Ludong University)