Supporting Information

High Performance Asymmetric Supercapacitors：New NiOOH

Nanosheet/Graphene Hydrogels and Pure Graphene Hydrogels

School of Chemical and Biomedical Engineering, Nanyang Technological University,

Singapore 637459, Singapore

Figure S1. A digital photograph of hydrogels obtained in various solvents with

different DMF/H2O ratio.

Figure S2. XRD patterns of the pure NiOOH prepared in D6-H1 solvent via a similar

procedure as NiOOH/GS hydrogels except no GO was added.

Figure S3. TEM images of Ni/GS hydrogels (a, b) and Ni(OH)2/GS hydrogels (c, d)

produced by single solvothermal and hydrothermal reactions, respectively.

Figure S4. SEM images of pure NiOOH.

Figure S5. (a, b) The plots of v1/2 vs. i(V)/v1/2 used for calculating k1 and k2 at different

potentials.

According to power law relationship, i= aν for non-diffusion limited processes and

i= aν1/2 for diffusion limited processes. Thus, total current i (V) = k1ν+ k2ν1/2 and i (V)/

ν1/2 = k1ν1/2 + k2.[1-3] Current values at different potentials were calculated from cyclic

voltammogram at different scan rates of 1 to 10 mV s-1. Plots of i/ν1/2 vs. ν1/2 have been

drawn at different potentials and from the straight line obtained value of k1 (slope) and

k2 (intercept) are calculated.

Figure S6. Charge-discharge curves of T-NiOOH/GS.

Figure S7. (a) Nitrogen adsorption and desorption isotherms and (b) BJH pore size

distribution of freeze-dried GS hydrogels.

Figure S8. (a) The survey XPS spectra, (b) C1s spectra and (c) N1s spectra of freeze-

dried GS hydrogels.

Figure S9. (a) The charge-discharge curves and (b) the corresponding specific

capacitance of graphene hydrogels (H-GS) in a two-electrode system.

Figure S10. CV curves of H-NiOOH/GS and H-GS at 20 mV s-1.

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