Phosphorus-doped thick carbon electrode for high-energy density and long-life supercapacitors

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2021-06, Vol.414, p.128767, Article 128767
• Main Authors: Wang, Feng, Cheong, Jun Young, He, Qiu, Duan, Gaigai, He, Shuijian, Zhang, Lin, Zhao, Yan, Kim, Il-Doo, Jiang, Shaohua
• Format: Article
• Language: English
• Subjects: Phosphorus-doping; Phytic acid; Supercapacitor; Thick electrode; Wood
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2021.128767

[Display omitted] •High P-doped (9.24 at%) thick carbon electrodes (CW-P) by phytic acid treatment.•SSC exhibits high capacitance of 4.7F cm−2/206.5F g−1 at 1.0 mA cm−2.•Excellent capacitance retention of 90.5% after 20 000 cycles (@20 mA cm−2).•High energy density up to 0.94 mW h cm−2 (41.2 Wh kg−1).•High power density up to 0.6 mW cm−2 (26.3 W kg−1). Keeping outstanding electrochemical performance under high mass loading is critical to develop functional thick electrodes. Here, we report a high phosphorus-doped wood-derived carbon thick electrode for supercapacitor via phytic acid treatment, which can form hydrogen bonds with cellulose molecules in the wood. The content of phosphorus reaches up to 9.24 at% in carbonized wood with P-doping (CW-P-9.24), higher than most previously reported P-doped carbonaceous materials. CW-P-9.24 electrode (800 μm, 17.17 mg cm−2) exhibits greatly improved electrochemical performance, especially in energy density and cyclic stability. Significantly, the symmetrical supercapacitor device exhibits high areal and specific capacitance of 4.7 F cm−2 and 206.5 F g−1 at 1.0 mA cm−2 with prominent retention of 90.5% through the long-term cycling at 20 mA cm−2 for 20,000 cycles, and 0.94 mW h cm−2 (41.2 Wh kg−1) at power density of 0.6 mW cm−2 (26.3 W kg−1), and possesses excellent volumetric capacitance and energy density of 29.3 F cm−3 and 5.8 Wh cm−3, respectively. The outstanding performance can be attributed to the excellent hierarchical structure, low tortuosity, and high phosphorus doping with fast accessible channels at high current density. The extraordinary performance of CW-P has been elucidated by density functional theory calculations, which confirm the enhanced activity by P-doping. These results demonstrate that the CW-P electrode is promising for practical application in energy storage devices and encourage more investigations for thick electrode.