Electronic Supplementary Material (ESI) for Sustainable Energy & Fuels. This journal is © The Royal Society of Chemistry 2017
Supporting information First report on FeS based 2 V operating flexible solid-state symmetric supercapacitor device Swapnil S. Karade, Pratibha Dwivedi, Sutripto Majumder, Bidhan Pandit, Babasaheb R. Sankapal* Nanomaterials and device laboratory, Department of Physics, Visvesvaraya National Institute of Technology, Nagpur- 440010, Maharashtra (India)
*Corresponding
Author
Dr. Babasaheb R. Sankapal Email:
[email protected],
[email protected] Contact No. : + 91(712)2801170: Fax No.: + 91(712)2223230
Supporting information S1 Supercapacitive studies Flexible stainless steel (FSS) substrates coated with FeS thin films have been used to construct symmetric supercapacitor solid-state device. Cyclic voltammetry (CV) was performed with potential window of 0 to 2 V and capacitance values were calculated using by the following relations [S11-S13]:
𝐶=
1
𝑉𝑓
∫𝐼(𝑉) 𝑑𝑉
𝑣 (𝑉 𝑓 ‒ 𝑉 𝑖 ) 𝑉
2𝐼 𝐶=
(2)
𝑖
∫𝑉 𝑑𝑡
(3)
𝑉2
where, ‘C’ is capacitance, ‘v’ is scan rate, (Vf -Vi) is potential window, ‘I’ is current and the term in integration is the enclosed area under the CV curve. Here, total active electrode mass = 2 × 2.16 mg) to calculate specific capacitance. On the other hand, total volume of the device was considered as V= 0.306 cm3 (3 cm × 3 cm × 0.034 cm) while calculating volumetric capacitance. The specific energy (SE) and specific power (SP) were calculated by using the following relations: 1 𝐶𝑉2 2 𝑆𝐸 = 3.6 𝑆𝑃 =
3600 × 𝐸 ∆𝑡
(4)
(5)
where, ‘V’ is maximum and minimum potential difference during charging and discharging and ‘∆𝑡’ is discharging time.
References [S11] S. Roldan, D. Barreda, M. Granda, R. Menendez, R. Sanatamaria, C. Blanco, An approach to classification and capacitance expressions in electrochemical capacitors technology, Phys. Chem. Chem. Phys., 17 (2015) 1084. [S12] G. Z. Chen, Understanding supercapacitor based on nano-hybrid materials with interfacial conjugation, Prog. Nat. Sci.: Mater Int., 23 (2013) 245. [S13] B. Pandit, D. P. Dubal, P. Gomez-Romero, B. B. Kale, B. R. Sankapal, V2O5 encapsulated MWCNTs in 2D surface architecture: Complete solid-state bendable highly stabilized energy efficient supercapacitor device, Sci. Rep. 7:43430.
Supporting information S2
Figure S2 (a) CV curves with different 1 M electrolytes at fixed scan rate of 100 mV/s (b) Specific capacitance values at different 1 M electrolytes.
Supporting information S3 Fig. S3 (a) shows galvanostatic charge-discharge (GCD) curves at different potential windows ranging from 0.6 to 2 V at constant current of 0.8 mA. It reveals up to 1.2 V there is insignificant change in charge-discharge time. Further increasing potential window, the charging curves tends toward saturation but still working up to 2 V. Fig. S3 (b) depicts the frame of specific capacitance and potential window in which initial decrease in specific capacitance observed up to 1.2 V and further increases and maintain at 3.58 F/g for 2 V; suggests electro-activity of the active electrode and electrolyte still functioning up to 2 V, so that 2 V is an considerable operational potential of the FSC device.
Figure S3 (a) GCD curves with potential variation at constant current of 0.8 mA (b) Variation of specific capacitance with different potential window.
