## 3 Results and Discussion
### Self-Discharge Study  
Self-discharge (SD) behavior and voltage holding (VH) capabilities are essential performance factors to consider when evaluating the applicability of supercapacitors for practical applications. After charging, the rapid self-discharging of SCs limits their employability on an industrial scale. Figure 3a shows four 100-cycle GCD measurements for SSC devices from INSC samples, followed by 2 h VH and 2 h SD tests. Figure 3b shows a sequence of GCD (100 cycles), followed by a 2-h VH test for an INSC SSC device. The GCD cycling was done at 1 Ag\({}^{-1}\) from 0 to 1.2 V, and furthermore, VH tests were performed at 1.2 V for 2 h, and SD tests were performed at OCP (open circuit potential), that is, in floating condition. Over two hours, a four-cycle VH test showed almost no internal resistance at the device level. Resistance and diffusion charge redistribution are important factors determining SD in SC devices [19]. The device was examined for SD, VH, and leakage currents, and the results showed that SD mitigation was due to improved nanostructural integrity in the fabricated SSC device. We exhibited a fabricated SSC device for LED illumination to further validate its practical application. Two SSC devices, connected in series, are extremely efficient when used to illuminate red commercial LED lights (Figure 3c). The charge transfer behavior of ions in a layered nanostructure for charge storage is depicted in the scheme in Figure 3d. Excellent electrochemical performances may indeed result from (i) a well-defined layer structure; (ii) the provision of highly accessible interfacial contacts due to the layered facets of 2D In\({}_{2}\)S\({}_{3}\), which allows for greater use of the ion accumulation; and (iii) decreased internal material resistance due to the incorporation of conducting SWCNTs, which results in a shorter electron diffusion length during the charge/discharge process [20]. All electrochemical results substantially support the merits of the developed heterostructure embedded with INSC electrode material as a high-performance supercapacitor application. Mechanical flexibility testing is a crucial step in ensuring the overall performance, robustness, and longevity of a device. This study evaluates the ability of the SC device to maintain its functionality under various bending angles. In particular, the mechanical flexibility testing was performed on a SSC device, and the results are shown in Figure 4a-e. For comparing the electrochemical performance, the CV curves of the SSC device were plotted in Figure 4f at a scan rate of 100 mVs\({}^{-1}\), which revealed the capacitance performance of the device. Essentially, it was observed that the capacitance performance of the SSCdevice did not degrade even when the bending angle was increased from 0\({}^{\circ}\) to 180\({}^{\circ}\), which is a significant deviation from the flat (0\({}^{\circ}\)) condition. Figure 4: (**a**–**e**) Mechanical testing of a fabricated SSC device at various bending states and (**f**) the corresponding CV graph for a fabricated INSC\(-\)based SSC device. Figure 3: (**a**) GCD (100 cycles) + VHT (2 h) + SD (2 h); (**b**) GCD (100 cycles) + VHT (2 h) for an INSC-based SSC device; (**c**) demonstration of commercial red LED illumination; and (**d**) schematic artwork for illustrating electron transmission at the electrode-electrolyte interface in a fabricated symmetric supercapacitor. This finding demonstrates the excellent flexible nature of the fabricated INSC-based SSC device and indicates that the device's capacitance performance remains unaffected even under extreme bending conditions. This, in turn, ensures the device's long-term durability and robustness, as it can maintain its functionality even in challenging environments. Thus, the test of mechanical flexibility plays a vital role in evaluating the performance, robustness, and longevity of a device.