Supporting Information Mechanically Strong Graphene/Aramid Nanofiber Composite Electrodes for Structural Energy and Power Se Ra Kwon, John Harris, Tianyang Zhou, Dimitrios Loufakis James G. Boyd, and Jodie L. Lutkenhaus*,, Department of Chemical Engineering, Texas A&M University, College Station, TX 77843, United States Department of Materials Science and Engineering, Texas A&M University, College Station, TX 77843, United States Department of Aerospace Engineering, Texas A&M University, College Station, TX 77843, United States *E-mail: jodie.lutkenhaus@tamu.edu S1
Figure S1. (a) Molecular structure of polyaramid PPTA. (b) AFM height images of ANFs drop-cast on mica (inset: digital image of prepared ANFs/DMSO dispersion). S2
Figure S2. (a) Digital image, SEM images of (b) surface and (c) cross-section of GO paper. (d) Digital image, SEM images of (e) surface and (f) cross-section of GO/25wt% ANF composite paper. (g) Digital image, SEM images of (h) surface and (i) cross-section of RGO paper. S3
Figure S3. AFM height images of (a) GO paper, (b) drop-cast ANFs on mica, and (c) GO/ANFs composite paper. Scale bars are 500 nm. S4
Figure S4. XRD patterns of GO, ANFs, and GO/ANF composite films. S5
Table S1. d-spacing and full width at half maximum (FWHM) values of GO and GO/ANF composite films from XRD patterns. 2θ ( ) d-spacing (nm) FWHM GO 12.11 0.73 1.61 GO/5 wt% ANF 11.975 0.738 2.04 GO/10 wt% ANF 11.983 0.738 2.14 GO/25 wt% ANF 12.593 0.702 3.97 S6
Table S2. Results of tensile testing. wt % # t (μm) w (mm) L (mm) Young's modulus (GPa) Ultimate strain (%) Strength (MPa) Toughness (kj/m3) 1 14 1.7 9.3 3.3 1.09 32.6 195.2 RGO 2 14 1.6 6.2 3.8 0.93 35.1 171.5 3 14 1.6 7.3 4.1 0.95 35.6 180.2 average 3.7±0.4 1.0±0.1 34.4±0.1 182.3 ±12 1 15 1.6 7.2 4.2 1.0 39.4 221.8 1 wt% 2 11 1.9 9.1 3.8 1.3 42.3 297.9 3 11 1.6 9.4 3.9 1.2 43.4 298.1 average 4.0±0.2 1.2±0.1 41.7±2.0 272.6±44 1 15 1.9 9.6 8.2 0.79 55.7 241.0 5 wt% 2 15 1.8 8.8 7.8 0.98 62.2 340.0 3 15 1.8 9.4 7.3 0.85 54.6 251.1 average 7.8±0.5 0.87±0.1 57.5±4.1 277.4±55 1 8 1.8 13.8 10.9 0.72 71.2 275.6 10 wt% 2 8 2.2 12.3 9.1 0.68 58.7 211.3 3 8 2.1 13.5 9.2 0.68 60.6 216.7 average 9.7±1.0 0.69±0.02 63.5±6.7 234.5±36 1 10 1.9 10.9 14.4 0.81 109.0 459.1 25 wt% 2 10 2 8.3 13.1 0.78 99.3 393.6 3 10 2 7.6 11.6 0.88 93.4 429.5 average 13.0±1.4 0.82±0.1 100.6±7.9 427.4±33 1 16 2.2 9.7 5.2 2.2 83.4 988.2 ANFs 2 16 1.3 8.3 5.4 2.0 96.8 1087.5 3 16 1.6 8.9 5.2 2.0 76.8 869.9 average 5.3±0.1 2.04±0.1 85.7±10.2 981.8±109 S7
Figure S5. Cyclic voltammograms of RGO/ANF composite electrodes at varying scan rates and with different ANFs composition. (a) RGO, (b) RGO/1 wt% ANF, (c) RGO/5 wt% ANF, (d) RGO/10 wt% ANF, and (e) RGO/25 wt% ANF. S8
Table S3. Specific capacitance at varying scan rates from CV curves. Scan rate (V/s) Specific Capacitance (F/g) TRGO 1 wt% ANF 5 wt% ANF 10 wt% ANF 25 wt% ANF 0.001 226.3 187.4 170.4 144.2 121.8 0.002 217.5 176.2 161.4 140.1 110.0 0.005 199.1 167.3 153.0 135.4 96.9 0.01 179.1 154.2 139.6 125.6 82.8 0.02 159.4 138.3 132.4 116.2 68.7 0.05 122.4 106.2 116.4 98.8 49.0 0.07 104.2 91.7 107.8 90.5 41.4 0.1 84.7 75.9 96.6 80.3 33.5 S9
Table S4. Density of the electrodes as a function of ANFs loading within the composite electrodes. Density (g/cm 3 ) Areal Mass (mg/cm 2 ) RGO 1.4 1.6 RGO/1wt% ANF 1.3 2.1 RGO/5wt% ANF 1.3 2.3 RGO/10wt% ANF 1.0 2.7 RGO/25wt% ANF 0.9 3.0 S10
Figure S6. Volumetric capacitance dependence on potential sweep rate. Figure S7. Energy density of the electrodes as a function of ANFs loading. S11
Figure S8. Ragone plot of (a) specific energy vs specific power and (b) volumetric energy density vs volumetric power density. The specific or volumetric energy (E, Wh/kg or Wh/L) and power (P, W/kg or W/L) of the electrodes were calculated by the equations E = C V! 8 and P = E v V, where C is the specific or volumetric capacitance (F/g or F/cm 3 ) measured by CV, V is the potential window, and v is the scan rate (V/s). S12
Table S5. Specific capacitance and capacitance retention ratio from galvanostatic charge/discharge cycling test at 0.5 A/g. cycle # RGO 1 wt% ANF 5 wt% ANF 10 wt% ANF 25 wt% ANF F/g % F/g % F/g % F/g % F/g % 1 215 100.0 172 100.0 149 100.0 128 100.0 88 100.0 10 194 90.6 162 94.6 145 97.1 121 94.8 85 96.5 50 194 90.1 161 93.6 143 95.9 120 93.5 85 96.0 100 193 89.7 159 92.9 142 95.4 119 92.8 85 96.0 200 190 88.7 158 91.9 141 94.7 117 91.7 84 95.4 300 189 87.9 157 91.3 140 93.6 116 91.0 84 95.3 400 188 87.4 156 90.7 139 93.2 116 90.4 84 95.0 500 188 87.4 155 90.2 138 92.8 115 89.7 83 94.4 600 188 87.6 154 89.9 138 92.7 115 89.8 83 94.4 700 186 86.6 154 89.5 138 92.6 115 89.9 82 93.6 800 185 86.1 153 88.9 137 91.9 114 89.4 82 93.7 900 184 85.8 152 88.8 137 91.6 114 89.2 82 93.5 1000 184 85.8 152 88.6 136 91.4 114 88.8 82 93.3 S13
Table S6. Ashby plot data from Figure 5. Materials Strength (MPa) Specific Capacitance (F/g) Electrochemical Fabrication Method Mechanical RGO/MnO 2 paper 1 8.79 243 Polypyrrole nanofibre/rgo 35 345 paper 2 RGO-Cellulose paper 3 8.67 120 Wire shaped RGO/CNT 385.7 35.9 composite 4 RGO-Polyaniline paper 5 12.6 233 RGO aerogel 6 0.15 128 Vacuum filtration of GO/MnO 2 dispersion, followed by hydrazine reduction Vacuum filtration of Ppy/GO dispersion, followed by HI reduction Vacuum filtration of graphene dispersion through cellulose filter paper Wet spinning of GO/FWCNT dispersion (4:1 wt. ratio), followed by HI reduction In situ anodic electropolymerization of polyaniline film on graphene paper Supercritical CO 2 drying of graphene hydrogel precursors obtained from heating the aqueous mixture of graphene oxide with L-ascorbic acid MWCNT paper 7-8 14.5 104 Spray layer-by-layer assembly of MWNT- NH 3 + /MWNT-COO - ) on carbon paper 7 Electrophoretically deposited on stainless steel susbstrate and liberated from substrate 8 SWCNT-Ppy-CE composite paper 9 68.73 320 Ppy deposited on SWCNT buckypaper by potentioamperometric polymerization, and soaked in cyanate ester solution RGO paper 10-11 132 215 SWCNT paper 12-13 11.2 40.7 Vacuum filtration of chemically reduced grapehene dispersion, followed by dipping in water for solvated graphene film 11 Vacuum filtration of SWNT dispersion 12 Vacuum filtration of chemically reduced graphene dispersion 10 Vacuum filtration of SWNT dispersion 13 S14
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