Nanocomposites and Nanomaterials

Impedance spectroscopy of capacitor systems based on saccharide-derived porous carbon materials
Mandzyuk V.I.1, Mironyuk I.F.1, Ivanichok N.Ya.1, Rachiy B.I.1
1 Vasyl Stefanyk Precarparhian National University, Shevchenko Street, 57, Ivano-Frankivsk-76018, Ukraine. 
E-mail: volodymyr.mandzyuk@pnu.edu.ua
The electrochemical processes in capacitor systems based on porous carbon materials (PCMs) derived from glucose, lactose, and saccharose at 800 and 1000°C are explored using impedance spectroscopy method. PCMs are characterized the developed porous structure with the maximum specific suface area 652 m2/g and total volume 0.345 cm3/g [1].
Impedance analysis of symetric supercapacitors was carried out using a Metrohm Autolab FRA-2 (Frequency Response Analyzer) at 10-2 ÷ 105 Hz in bias potential range 0 ÷ 1 V. For the obtained impedance hodographs, an equivalent electrical circuit was chosen (Fig. 1), the elements of which characterize the passing of electrochemical processes at the electrode-electrolyte boundary.
	
Fig. 1. The equivalent electrical circuit of capacitor systems.	
In this circuit L1 displays an inductive behavior of the electrochemical system, Rs includes the resistance of the electrolyte, contacts and supply wires. Other elements are responsible for the diffusion processes in the pores of PCM and the accumulation of electric charges at the electrolyte-electrod boundary. In particular, the C2||R2-link is responsible for these processes in the transport pores (macro- and mesopores), СРЕ3|| R3-CPE4-link – in micropores. 
The obtained results indicate the dominance of the double electric layer capacity over the capacity due to the redox-reactions, which confirms the results of galvanostatic and potentiodynamic cycling [2].

1.	Myronyuk І.F., Mandzyuk V.I., Sachko V.M., Gun’ko V.M. Structural features of carbons produced using glucose, lactose, and saccharose // Nanoscale Research Letters.-2016.-11, N 508.-P. 1-9.
2.	Mandzyuk V.I., Myronyuk I.F., Sachko V.M., Rachiy B.I., Kulyk Yu.O., Mykytyn I.M. Structure and electrochemical properties of saccharide-derived porous carbon materials // J. Nano- Electron. Phys.-2018.-10, N 2. – P. 01013-1–01013-6.