Scalable Water‐Based Production of Highly Conductive 2D Nanosheets with Ultrahigh Volumetric Capacitance and Rate Capability

Abstract

Adv. Energy Mater. 2018, 8, 1800227 The measurement methods (i.e., changing the techniques and parameters) used to evaluate the electrochemical performance of the electrode materials could also affect the reported results depending on whether CV or GCD techniques are used.7, 8 In the original article, the specific capacitance values of the electrode materials were reported using the GCD technique only. Here, data on the volumetric capacitance and rate capability of the electrode materials using the CV technique are provided (Table 2). CV and GCD measurements were performed using a VersaSTAT 4 instrument (Princeton Applied Research) equipped with a power booster (specification of ± 20 A and ± 20 V). Although there is a small difference between the capacitance values of the CV and GCD methods, the decreasing tendency of the capacitances as the Gr loading increases are similar for both techniques. The rate capabilities of the electrode materials obtained from the GCD technique are also very close to those of the CV method. A scalable water-based fluid dynamic exfoliation process was reported for preparing highly conductive metallic phase MoS2 and graphene sheets and then free-standing flexible hybrid films were fabricated for the high-volumetric performance of flexible supercapacitor devices. Additional studies on hybrid films were also conducted using organic electrolytes of 1-ethyl-3-methylimidazoluim tetrafluoroborate ([EMIM][BF4]) dissolved in acetonitrile (ACN) to increase the energy density. The energy density value of 564.91 W h kg−1 (1.14 W h cm–3), which was based on the organic electrolytes reported in the original article, resulted from an error in the calculation of the energy density using overcharged GCD curves. A cell voltage of 1 V was used for the aqueous electrolyte instead of 3.5 V for the energy density calculation of the organic electrolyte, thus leading to the incorrect energy density value in the original article. To address this error, the GCD of the supercapacitors was retested (Figure 5f) and the energy densities were recalculated using an integral equation instead of a linear equation (Figures 5g,h). The newly obtained CV and GCD data show stable cell voltages of ≈3.2 V. Based on these new results, the maximum energy density is 122.2 W h kg−1 at 1.4 kW kg−1 (246.9 mW h cm−3 at 2.97 W cm−3). The corrected Figure 5f–h are shown here: The authors apologize for these errors and any confusion they may have caused.