Narrow-porous pitch-based carbon fibers of superior capacitance properties in aqueous electrolytes

作者：Torchala K; Kierzek K; Gryglewicz G; Machnikowski J^*

来源：Electrochimica Acta, 2015, 167: 348-356.

DOI：10.1016/j.electacta.2015.03.153

• Pitch-based fibre
• Ammonia activation
• Microporosity
• Electrochemical capacitor
• Aqueous electrolyte
• Capacitance behavior

Two couples of narrow-porous carbons in the form of particulates (PAC) and fibers (ACF) have been prepared by one step carbonization/activation of pitch-based precursors in carbon dioxide or ammonia atmosphere. The activated carbons are assessed as electrode material of EDL capacitor operating in 6 mol L-1 KOH and 0.5 mol L-1 K2SO4 aqueous solutions. Electrochemical measurements show distinctly improved charge propagation in pitch-based ACFs compared to corresponding PACs but also to commercial phenolic resin-based FR15 fibers of very similar porosity characteristics, especially in the sulphate medium. Over twice higher capacitance of ACFs than FR15 in K2SO4 solution (over 90 vs 40 F g(-1) at 1 F g(-1)) is attributed to less distorted basic structural units in pitch-based fibers, and thus facilitating quick penetration of ions along pores. Carbonization/activation treatment in ammonia appears to be a very effective route for enhancing the capacitance without noticeable negative impact of nitrogen and oxygen functionalities with increasing charge rate, current density or frequency. Pitch-based narrowporous active carbon fibers seem to be a very well adapted candidate for use as electrode material of low-to-moderate power capacitor intended to operate in sulphate electrolyte above water decomposition voltage.

• 出版日期2015-6-10