binders - copy
TRANSCRIPT
H. Avireddy,a,b P. Arcidiacono,a,c L. Coustana,c and F. Favier,a,c* a ICGM- CNRS- UMR 5253, Equipe AIME, Université Montpellier, 34095, Montpellier, France
b School of Electrical and Electronics Engineering. Centre for Nanotechnology & Advanced Biomaterials, SASTRA
University, 613401, Thanjavur, India c Réseau sur le Stockage Electrochimique de l’Energie (RS2E), FR CNRS 3459, France
* Corresponding author email address: [email protected]
References – Sangmin Lee et al., Journal of Power Sources, 269 (2014), pp-418-423; Keh Chyun et al., Electrochimca Acta, 60 (2012), pp-428-436.
Objectives
Acknowledgements
PVOH
Effect of Various Binders on the Performance
of Supercapacitor Electrodes
To study the effect of commonly used binders such
as PTFE, PVDF and PVOH on the electrochemical
performances of MnO2 electrode based
supercapacitors.
PVOH PVDF PTFE
Binders
Results & Discussions
1M Na2SO4 VS 1 M KOH
Specific capacitance of PVOH was higher in 1M
Na2SO4 compared to that of 1 M KOH whereas
PVDF and PTFE have shown higher specific
capacitance in 1 M KOH compared to 1 M
Na2SO4 at a scan rate of 5 mV/s
Voltage Window
The CV curves also show that the voltage
window in 1 M Na2SO4 (0.85 V) is higher than
that of the voltage in 1 M KOH (0.6 V).
Maximum Specific Capacitance
From CVs (at 5 mV/s scan rate) and
galvanostatic charge-discharge analysis (at 1.2
A/g), the maximum specific capacitance in 1 M
Na2SO4 was shown by the electrode based on
PTFE binder whereas the maximum specific
capacitance in 1 M KOH was shown by the
PVDF binder based electrode.
Electrochemical Impedance Spectroscopy
The ESR, after 1500 galvanostatic charge-
discharge cycles (GCPL), was lowest for the
PVOH binder based electrode in both 1 M
Na2SO4 and 1 M KOH. However, higher ionic
resistance was noted for PVOH binder based
electrode compared to PTFE and PVDF binders
in 1M KOH. This higher ionic resistance may
explain the lower specific capacitance of PVOH
binder based electrode in 1 M KOH.
Specific Capacitance Retention
In general, PVDF binder degrades in alkaline
medium due to dehydroflorination but in the
present study, the PVDF binder in 1 M KOH not
only shows higher specific capacitances (5 mV/s
– 179 F/g; 105 F/g – 1.2 A/g) but also shows
higher specific capacitance retention (97 %) after
1500 cycles compared to PTFE and PVOH
binder based electrodes.
114 129 85 120 45 42
PVDF-MnO2
-CB PTFE-MnO2
-CB
PVOH-MnO2
-CB
Contact Angle
O O O O O O
Authors thank Thierry THAMI for contact angle measurements at Institut Européen des Membranes (Montpellier) and foundation Balard for fellowship
Electrode Composition - MnO2 and carbon black
(CB) to binder in the ratio of 65:35 (In which MnO2
and carbon black were in the ratio of 85 :15).
Loading of electrodes ~ 8 mg/cm
Electrolytes - 1 M KOH and 1 M Na2SO4.
Electrodes Preparation
Binder Ionic resistance
(after GCPL)
Specific Capacitance
(5 mV/s)
Specific Capacitance (200 mV/s)
Specific Capacitance Retention
PTFE-MnO2 –CB - + 0 - PVDF-MnO2 –CB 1 M Na2SO4 + 0 + + PVOH-MnO2 –CB 0 - - - PTFE-MnO2 –CB - 0 + 0 PVDF-MnO2 -CB 1 M KOH 0 + + + PVOH-MnO2 –CB + - - -
PTFE PVDF
Conclusions
Further Works Effect of active material loading on the electrochemical performances of supercapacitor electrodes
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