Capacitance fading mechanism and structural evolution of conductive polyaniline in electrochemical supercapacitor
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Capacitance fading mechanism and structural evolution of conductive polyaniline in electrochemical supercapacitor Panpan Zhang1 · Xinhua Zhai1 · Hui Huang1,2 · Jianfeng Zhou2 · Xiaobo Li1 · Yapeng He1 · Zhongcheng Guo1,2 Received: 5 March 2020 / Accepted: 15 July 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Aiming to explore the capacitance fading mechanism of the conductive polyaniline (PANI) in supercapacitors, we prepared the PANI film on stainless steel mesh substrate via electropolymerization method. The results reveal that the specific capacitance of PANI film reaches 75.9% and 55.5% retention after 500 and 2000 cycles under 2 A g−1, respectively. The surface morphology, chemical structure, and element content change of PANI film are observed after subjecting to the subsequent certain charge/discharge cycles. As a consequence, we identify the fading mechanism of the capacitance performance of PANI material, which includes the structure evolution and partial degradation. The morphological regularity of polyaniline film gradually deteriorates from the volume expansion/shrinkage in continuous doping/undoping process, accompanying with the increase of surface sulfur element content and decline of C/O output ratio. Besides, the hydrolysis oxidation decomposes the polymer chains, weakening the conjugation interaction between molecular chains and resulting in the partial degradation into the electrolyte. The study provides a comprehensive understanding and strong evidence of the structure evolution, supporting a better design of the conductive PANI electrode materials.
1 Introduction With the rapid development of the technology, drastically depletion of the mineral resources, and deterioration of the environment, it is urgent required to explore efficient energy storage systems [1]. Electrochemical supercapacitors (SCs) possess the features of long cycle life, low maintenance costing, and relatively high power density than batteries [2, 3]. Therefore, SCs have been considered to be one of the prospective alternatives in energy storage systems to meet the high power electronic device market. It is noting that the electrode materials substantially determine the intrinsic performances of the SCs as an important component of the SCs. As one typical electrode material in SCs, conductive polyaniline (PANI) possesses the merits of simple preparation, * Hui Huang [email protected] * Yapeng He [email protected] 1
Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093, China
Kunming Hendera Technology Co. Ltd., Kunming 650106, China
2
low cost, excellent conductivity, higher energy density, and good redox reversibility [4–6]. However, conducting PANI electrode materials commonly suffer from the low mechanical stability and cyclic life. It has been confirmed that the decrease of specific capacitance and the unsatisfactory cyclic stability could be ascribed to the volume expansion/shrinkage features during the
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