|Faraday Discuss., 2011, 154|
Additions and corrections
Graphene-based supercapacitors in the parallel-plate electrode configuration: Ionic liquids versus organic electrolytes
Youngseon Shim, Hyung J. Kim and YounJoon Jung
Faraday Discuss., 2012, 154, 249–263 (DOI: 10.1039/c1fd00086a). Amendment published 27th July 2012
After publication of our work on parallel plate supercapacitors, we found an error in charge density of the electrolytes. To be specific, the local charge density and its integrated charge Q(z) were shifted erroneously in the negative z direction by 1 Å in Fig. 4 and 8 of the paper. While the qualitative aspects of our results remain largely unaffected, some quantities, in particular, the electric potential and specific capacitance of the supercapacitors, are influenced by this error. The correct results are presented in Table C1 and Fig. C1–C3 here, which replace Table 1 and Fig. 5, 6 and 9 of our original paper.
Table C1. Results of electric potential drop and specific capacitanceab
For the electrode separation of d = 6.4 nm, the anodic and cathodic potential drops with respect to PZC, ΔΔΦ(+) and ΔΔΦ(–), are calculated to be 2.8 V and –3.6 V for σS = ±0.86 e nm–2, respectively. The smaller BF4– is more efficient in screening the charged electrode at short distances than bulkier EMI+, especially in the case of high surface charge density. This results in anodic capacitance higher than the cathodic value, viz., c(+) = 4.9 μF cm–2 and c(–) = 3.8 μF cm–2. As we reduce the surface charge density to σS = ±0.43 e nm–2, the cathode–anode disparity almost disappears as c(±) = 5.3 μF cm–2. The latter feature is consistent with very recent simulation results of Merlet et al. obtained using a coarse-grained model for EMI+BF4– (C. Merlet, M. Salanne and B. Rotenberg, J. Phys. Chem. C, 2012, 116, 7687). By contrast, the cathode–anode disparity occurs even at σS = ±0.43 e nm–2 in the organic electrolyte.
Electric potentials in the double-sided (this work) and single-sided electrode configurations (Y. Shim, Y. Jung and H. J. Kim, J. Phys. Chem. C, 2011, 115, 23574) are compared in Fig. C3. For both the EMI+BF4– and organic electrolyte cases, the potential near a charged electrode exhibits a similar behavior regardless of the electrode configuration. Analogously, the average charge density (not presented here) shows little dependence on the electrode configuration. The spurious dependence of the potential on the electrode configuration in this work was due to the aforementioned error in the position of charge density there.
The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.
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