Sodium-ion supercapacitors based on nanoporous pyroproteins containing redox-active heteroatoms

• Published in: Journal of power sources 2016-10, Vol.329, p.536-545
• Main Authors: Cho, Se Youn, Yoon, Hyeon Ji, Kim, Na Rae, Yun, Young Soo, Jin, Hyoung-Joon
• Format: Article
• Language: English
• Subjects: Activated carbon; Electrode; Nanoporous; Pyroprotein; Silk; Supercapacitor
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2016.08.114

Nanostructured carbon-based materials fabricated via simple methods from renewable bio-resources have great potential in rechargeable energy storage systems. In this study, nanoporous pyroproteins containing a large amount of redox-active heteroatoms (H-NPs) were fabricated from silk fibroin by an in situ carbonization/activation method. The H-NPs have a large surface area of ∼3050 m2 g−1, which is mainly comprised of nanometer-scale pores. Also, these H-NPs have oxygen and nitrogen heteroatoms of 17.4 wt% and 2.9 wt%, respectively. Synergistic sodium ion storage behaviors originate from electrochemical double layer capacitance and pseudocapacitance, leading to very high electrochemical performances of H-NPs in aqueous and non-aqueous electrolyte systems. Sodium-ion supercapacitors (NISs) based on commercial graphite//H-NPs show a high specific power of ∼1900 W kg−1 at ∼77 Wh kg−1. Also, NISs based on commercial hard carbon//H-NPs exhibit a high specific energy of ∼217 Wh kg−1 at ∼42 W kg−1. In addition, outstanding cycling performances over 30,000 cycles are achieved for symmetric NISs. Nanoporous pyroproteins containing a large amount of redox-active heteroatoms (H-NPs) were fabricated from silk fibroin by in situ carbonization/activation method, showing outstanding electrochemical performance. [Display omitted] •Nanostructured pyroproteins (H-NPs) are fabricated by a simple pyrolysis with KOH.•The H-NPs have numerous redox-active heteroatoms for pseudocapacitive charge storage.•The H-NPs also exhibit a high specific surface area of 3050 m2 g−1.•High capacitance of 348 F g−1, low ESR of ∼1.70 Ω and stable 30,000 cycles are achieved.•High energy (217 Wh kg−1) and high power (1900 W kg−1) are achieved.