Influences of ions and temperature on performance of carbon nano-particulates in supercapacitors with neutral aqueous electrolytes--颗粒学报PARTICUOLOGY

Chae, J. H., & Chen, G. Z. (2014). Influences of ions and temperature on performance of carbon nano-particulates in supercapacitors with neutral aqueous electrolytes. Particuology, 15, 9–17. https://doi.org/10.1016/j.partic.2013.02.008

Influences of ions and temperature on performance of carbon nano-particulates in supercapacitors with neutral aqueous electrolytes

Jung Hoon Chae, George Zheng Chen^*

Department of Chemical and Environmental Engineering, and Energy and Sustainability Research Division, Faculty of Engineering, University of Nottingham, Nottingham, NG7 2RD, UK

10.1016/j.partic.2013.02.008

Volume 15, August 2014, Pages 9-17

Received 5 December 2012, Revised 25 January 2013, Accepted 7 February 2013, Available online 15 June 2013.

E-mail: george.chen@nottingham.ac.uk

Highlights

• A commercial pigment composed of carbon nanospheres can be used for energy storage.

• The carbon nanospheres exhibit high capacitance in neutral aqueous electrolytes.

• Hydrous radius of the cation determines the measured capacitance.

• Semicircles on AC impedance plots are due to ion transfer crossing the carbon/electrolyte interface.

• Capacitance changes with temperature disagree with classic theory of electrical double layer.

Abstract

A commercial product of carbon nano-particles, Cabot MONACH 1300 pigment black (CMPB), was studied for basic structural information and electrochemical performance in neutral aqueous electrolytes, aiming at applications in supercapacitors. As confirmed by SEM and HRTEM, the CMPB had a hierarchical structure, containing basic 10 nm nano-spheres which combined into ca. 50 nm agglomerates which further aggregated into larger particles of micrometres. The capacitance of this commercial material was found to increase with decreasing the size of hydrous cation (Li⁺ → Na⁺ → K⁺), instead of the cation crystal radius (K⁺ → Na⁺ → Li⁺) when coupled with the same anion (Cl⁻). In electrolytes with the same cation concentration (K⁺), changing the anion from the larger dianion (SO₄²⁻) to the smaller monoanion (Cl⁻) also increased the capacitance at high potential scan rates (>50 mV/s). Increasing electrolyte concentration produced expected effect, including raising the electrode capacitance, but lowering the equivalent series resistance (ESR), charge transfer resistance (CTR), and the diffusion resistance. At higher temperatures, the CMPB exhibited slightly higher capacitance, which does not agree with the Gouy–Chapman theory on electric double layer (EDL). A hypothesis is proposed to account for the capacitance increase with temperature as a result of the CMPB opening up some micro-pores for more ions to access in response to the temperature increase.

Graphical abstract

Keywords

Carbon nano-particles; Supercapacitor; Neutral aqueous electrolytesIonic properties; Electrochemistry

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