期刊
JOURNAL OF POWER SOURCES
卷 279, 期 -, 页码 555-562出版社
ELSEVIER
DOI: 10.1016/j.jpowsour.2015.01.027
关键词
Electrical double-layer capacitors; Aqueous electrolyte; Etching of stainless steel current collectors; Electrochemical impedance spectroscopy; Scanning electron microscopy; Atomic force microscopy
资金
- Foundation for Polish Science (FNP) [WELCOME/2010-4/1]
- European Union Regional Development Fund
- Ministry of Science and Higher Education (Poland) [06/62DSPB/0215]
The main purpose of the study was to increase the surface roughness of stainless steel 301 current collectors by etching, in order to improve the electrochemical performance of electrical double-layer capacitors (EDLC) in 1 mol L-1 lithium sulphate electrolyte. Etching was realized in 1:3:30 (HNO3:HCl:H2O) solution with times varying up to 10 min. For the considered 15 mu m thick foil and a mass loss around 0.4 wt.%, pitting was uniform, with diameter of pits ranging from 100 to 300 nm. Atomic force microscopy (AFM) showed an increase of average surface roughness (Ra) from 5 nm for the as-received stainless steel foil to 24 nm for the pitted material. Electrochemical impedance spectroscopy realized on EDLCs with coated electrodes either on as-received or pitted foil in 1 mol L-1 Li2SO4 gave equivalent distributed resistance (EDR) of 8 Omega and 2 Omega, respectively, demonstrating a substantial improvement of collector/electrode interface after pitting. Correlatively, the EDLCs with pitted collector displayed a better charge propagation and low ohmic losses even at relatively high current of 20 A g(-1). Hence, chemical pitting of stainless steel current collectors is an appropriate method for optimising the performance of EDLCs in neutral aqueous electrolyte. (C) 2015 Elsevier B.V. All rights reserved.
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