Flexible Iron Oxide Supercapacitor Electrodes by PhotonicProcessing

Supporting Information

Flexible Iron Oxide Supercapacitor Electrodes by Photonic Processing

Madhu Gaire¹, Najma Khatoon¹, Binod Subedi¹ and Douglas Chrisey¹

1Tulane University, New Orleans, Louisiana, 70118, USA, email: mgaire@tulane.edu

Figure S1. Surface morphological characterization of the as-prepared electrode. SEM images of precursor film before curing (a), after curing (b, c), and after curing and after cycling test

Table S1. Electrode processing parameters.

Figure S3. Calculation of ‘b’ parameter values at various voltages for cathodic (a) and anodic (b) scans.

Figure S2. XRD spectrum of the cured electrode.

Figure S4. Calculation of k1 and k2 values to investigate capacitive and diffusion-controlled capacitance during cathodic (a) and anodic (b) scans.

Figure S5. Calculation of capacitance contribution from surface controlled and diffusion-controlled processes for the sample at (a) 10 and (b) 20 mV/s scan

Electrode material

Electrode preparation time

Electrolyte Specific capacitance (F/g)

Rate capability

Cyclic stability Reference (year)

Amorphous Fe2O3

Not reported 1 M NaOH 178 at 5 mV/s 120 at 100 mV/s

Not reported 1 (2011)

N-rGO/α-Fe2O3 > 12 hours 1 M KOH 268 at 2 A/g 137 at 5 A/g

96 % after 2000 cycles

2 (2015)

α-Fe2O3 > 12 hours 0.5 Na2SO4 193 at 1 A/g 63 at 12 A/g

92 % after 1000 cycles

3 (2014) Figure S6. Charge discharge curves for Fe2O3-rGO at various areal current

densities.

Table S2. Comparison of the processing times and the electrochemical performance of the-as prepared electrode with the already reported iron oxide supercapacitor electrodes.

Fe2O3 nanosheet > 12 hours 1 Li2SO4 173 at 3 A/g 117 at 12 A/g

Not reported 4 (2008)

Fe2O3-graphene > 12 hours 2 M KOH 151.8 at 1 A/g 94 at 16 A/g

86 % after 2000 cycles at 2 A/g

5 (2012)

α-

Fe2O3/graphene

> 24 hours 1 M Na2SO4 306 at 3 A/g 98 at 10 A/g

91 % after 2000 cycles at 5 A/g

6 (2014)

α-Fe2O3

nanotube/rGO

> 24 hours 1 M Na2SO4 181 at 3 A/g 69 at 10 A/g

92 % after 2000 cycles

7 (2012)

Nitrogen doped graphene Fe2O3

> 24 hours 1 M Na2SO4 260 at 2 A/g 110 at 7 A/g

82 % after 1000 cycles at 2 A/g

8 (2014)

Fe2O3/N-rGO > 12 hours 1 M KOH 618 at 0.5 A/g 350 at 10 A/g

57 % after 5000 cycles at 4 A/g

9 (2014)

Fe2O3-rGO several seconds 1 M KOH 179 at 2 A/g 104 at 10 A/g

70 % after 5000 cycles at 2 A/g

this work

1. Kulal, P. M., Dubal, D. P., Lokhande, C. D., & Fulari, V. J. (2011). Chemical synthesis of Fe2O3 thin films for supercapacitor application. Journal of Alloys and Compounds, 509(5), 2567-2571.

2. Liu, H. D., Zhang, J. L., Xu, D. D., Huang, L. H., Tan, S. Z., & Mai, W. J. (2015). Easy one-step hydrothermal synthesis of nitrogen-doped reduced graphene oxide/iron oxide

hybrid as efficient supercapacitor material. Journal of Solid State Electrochemistry, 19(1), 135-144.

3. Shivakumara, S., Penki, T. R., & Munichandraiah, N. (2014). Preparation and electrochemical performance of porous hematite (α-Fe 2 O 3) nanostructures as supercapacitor electrode material. Journal of Solid State Electrochemistry, 18(4), 1057- 1066.

4. Wu, M. S., Lee, R. H., Jow, J. J., Yang, W. D., Hsieh, C. Y., & Weng, B. J. (2008).

Nanostructured iron oxide films prepared by electrochemical method for electrochemical capacitors. Electrochemical and Solid State Letters, 12(1), A1.

5. Wang, D., Li, Y., Wang, Q., & Wang, T. (2012). Nanostructured Fe 2 O 3–graphene composite as a novel electrode material for supercapacitors. Journal of Solid State Electrochemistry, 16(6), 2095-2102.

6. Yang, S., Song, X., Zhang, P., Sun, J., & Gao, L. (2014). Self Assembled ‐ α‐Fe2O3 Mesocrystals/Graphene Nanohybrid for Enhanced Electrochemical Capacitors. Small, 10(11), 2270-2279.

7. Lee, K. K., Deng, S., Fan, H. M., Mhaisalkar, S., Tan, H. R., Tok, E. S., ... & Sow, C. H.

(2012). α-Fe 2 O 3 nanotubes-reduced graphene oxide composites as synergistic electrochemical capacitor materials. Nanoscale, 4(9), 2958-2961.

8. Zhao, P., Li, W., Wang, G., Yu, B., Li, X., Bai, J., & Ren, Z. (2014). Facile hydrothermal fabrication of nitrogen-doped graphene/Fe2O3 composites as high-performance electrode materials for supercapacitor. Journal of alloys and compounds, 604, 87-93.

9. Ma, Z., Huang, X., Dou, S., Wu, J., & Wang, S. (2014). One-pot synthesis of Fe2O3 nanoparticles on nitrogen-doped graphene as advanced supercapacitor electrode materials. The Journal of Physical Chemistry C, 118(31), 17231-17239.

Figure S7. Areal capacitance after various number of charge-discharge cycles.