Biochar activated by oxygen plasma for supercapacitors

JOURNAL OF POWER SOURCES

卷:274

Article

Gupta, Rakesh Kumar¹  Dubey, Mukul¹  Kharel, Parashu³  Gu, Zhengrong²  Fan, Qi Hua¹ 

[1] S Dakota State Univ, Dept Elect Engn & Comp Sci, Brookings, SD 57007 USA

[2] S Dakota State Univ, Dept Agr & Biosyst Engn, Brookings, SD 57007 USA

[3] S Dakota State Univ, Dept Phys, Brookings, SD 57007 USA

关键词: Supercapacitors;    Biochar;    Plasma;    Activation;   

DOI  :  10.1016/j.jpowsour.2014.10.169

来源: Elsevier

【 摘 要 】

Biochar, also known as black carbon, is a byproduct of biomass pyrolysis. As a low-cost, environmental-friendly material, biochar has the potential to replace more expensive synthesized carbon nanomaterials (e.g. carbon nanotubes) for use in future supercapacitors. To achieve high capacitance, biochar requires proper activation. A conventional approach involves mixing biochar with a strong base and baking at a high temperature. However, this process is time consuming and energy inefficient (requiring temperatures >900 degrees C). This work demonstrates a low-temperature (<150 degrees C) plasma treatment that efficiently activates a yellow pine biochar. Particularly, the effects of oxygen plasma on the biochar microstructure and supercapacitor characteristics are studied. Significant enhancement of the capacitance is achieved: 171.4 F g(-1) for a 5-min oxygen plasma activation, in comparison to 99.5 F g(-1) for a conventional chemical activation and 60.4 F g(-1) for untreated biochar. This enhancement of the charge storage capacity is attributed to the creation of a broad distribution in pore size and a larger surface area. The plasma activation mechanisms in terms of the evolution of the biochar surface and microstructure are further discussed. (C) 2014 Elsevier B.V. All rights reserved.

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