IRON OXIDE DEPOSITED ON ACTIVATED CARBON FELT FOR APPLICATIONS AS A SUPERCAPACITOR ELECTRODE A. C. RODRIGUES(1*), E. L. DA SILVA(2), J. S. MARCUZZO(2,4), A. CUÑA(3), E. S. GONÇALVES(1), M. R. BALDAN(2) (1)Instituto
Tecnológico de Aeronáutica, São José dos Campos, SP, Brasil, (2)Instituto Nacional de Pesquisas Espaciais, São José dos Campos, SP, Brasil, (3)Faculdade de Química, Universidade da República (DETEMA), Uruguai,, (4)Faculdade de Tecnologia de São José dos Campos (FATEC) São José dos Campos, SP, Brasil.
*
[email protected] ABSTRACT The activated carbon fibers from polyacrylonitrile (PAN) has high surface area, distribution of appropriate pores for various applications, specially as active material for supercapacitor electrodes. Recent studies show a combination of electric properties, double-layer capacitive and pseudo-capacitive on iron oxide, which are important for electrode supercapacitor. The aim of this work is to characterize the activated carbon felt with iron oxide particles for electrode supercapacitor applications. X-Ray Intensity (a.u)
MATERIAL AND METHODS FCA ADSORPTION Fe(NO3)3 2g/L for 24h
ACF ACF + Fe
10
20
30
40
50
60
Position (2)
Figure 2: X-Ray diffraction of ACF and ACF+Fe. 26° and 44° are typical carbono peaks.
ANALYSIS 4500
X-Ray
Electrochemical
ACF ACF+Fe
4000 3500
• The activated carbon felt was immersed in deionized water and Fe(NO3)3 solution for 24 hours; • The activated carbon felt-iron oxide composite obtained were characterized by x-ray diffraction (XRD), scanning electron microscopy equipped with energy dispersive x-ray (SEM-EDX) and Raman spectroscopy; • The materials were tested as a supercapacitor electrode in a two-electrode Swagelok®-type cell using 2M H2SO4 aqueous solution as electrolyte.
Weight (%)
Raman
80
3000
Intensity (a.u)
SEM - EDX
ACF ACF + Fe
100
2500 2000 1500
60 40 20
1000 500
0
0 1200
1600
2000
2400
2800
0
3200
100
200
300
400
500
Raman Shift (cm-1)
Temperature (°C)
a)
b)
600
700
800
Figure 3: a) Raman spectra of ACF and ACF+Fe, b) TGA curves for ACF and ACF+Fe. ACF ACF+Fe
6000
RESULTS
ACF ACF+Fe
0,25
5000
0,20
-Z" / ohm
-Z" / ohm
4000 3000
0,15
0,10
2000
0,05
1000
0,00
0 -200
Rs
0
200
400
600
800
1000 1200 1400 1600 1800
Z' / ohm
a)
0,0
0,1
Ra 0,2
0,3
0,4
0,5
0,6
Z' / ohm
b)
Figure 4: a) nyquist Diagram for ACF and ACF+Fe, b) detail of region (a).
Figure 1: Activated carbon felt with particles of iron oxide Inset: activated carbon felt.
Sample Rs () Ra () RT () ACF 0,26 0,23 0,49 ACF+Fe 0,22 0,29 0,51 Table 1: values of resistance (Rs, Ra, RT). Ra is the arc resistance, Rs is the electrolyte bulk resistance and RT is total resistance.
CONCLUSION It was observed that activated carbon fiber showed good adsorption capacity for the metal used. The process of adsorption does not change the fiber structure and morphology. The activated carbon fiber have a high specific surface area, this area is related to metallic fraction incorporated into the fiber, about 3,5%wt of Fe and water content. Tests using the electrochemical cell showed a low total resistence (RT) of the activated carbon fibers with Fe particles, which confirms that the studied electrode is very good to be used as supercapacitor.
