# Lotus Root Type Nickel Oxide-Carbon Nanofibers: A Hybrid Supercapacitor Electrode Material
## 4 Conclusions  
In summary, we generated polymer fibers through electrospinning, incorporating PAN, PS, and Ni sources. Subsequently, we fabricated highly porous lotus root-type hybrid supercapacitor materials comprising NiO and carbon using a straightforward carbonization process. Additionally, the TGA data revealed an optimized material ratio of 45% NiO causing a synergetic advanced electrochemical effect with carbon. Notably, the LCN-45 electrode, constructed with this ratio, demonstrated a higher specific capacitance (39.9 F g\({}^{-1}\)) than materials with alternative ratios at a current density of 0.2 A g\({}^{-1}\). Regarding cycling durability, a capacitance retention rate of 82.6% was demonstrated after approximately 1000 cycles at a current density of 1.0 A g\({}^{-1}\). Likewise, an energy density as high as 2.83 Wh kg\({}^{-1}\) was confirmed at a current density of 1.0 A g\({}^{-1}\). This demonstrates that the hybrid-type LCN-45 material outperforms EDLC, pseudo-materials, and LCN series materials of other ratios. It is believed that the discovery of the optimal ratio for hybrid materials combining metal oxides and carbon will pave the way for the development of high-performance supercapacitors.  
The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/app14072977/s1](https://www.mdpi.com/article/10.3390/app14072977/s1)]([https://www.mdpi.com/article/10.3390/app14072977/s1](https://www.mdpi.com/article/10.3390/app14072977/s1)). Figure S1: (a) Adsorption isotherms and (b) Pore size distribution graphs of LC, LCN-45, and LN; Figure S2: BET plots of LC, LCN series, and LN samples; Figure S3: Specific capacitances of LCN-45 electrode calculated from Figure 6b; Figure S4: Cycle stability of LN electrode at 1.0 A g\({}^{-1}\) (Inset shows the GCD curves of the 1 st and 1000 th cycles); Table S1. Adsorption characteristics of LC, LCN series, and LN.  
Conceptualization, J.K. and J.L.; methodology, J.L., H.R. and T.C.; formal analysis, J.K.; investigation, J.K., H.R. and A.P.; data curation, Y.H.; writing--original draft preparation, J.K. and J.L.; writing--review and editing, Y.H. and S.N.; supervision, Y.S.; project administration, Y.S. All authors have read and agreed to the published version of the manuscript.  
Figure 6: (**a**) Galvanostatic charge–discharge (GCD) curves of the LCN-45 electrode with various current densities from 0.2 to 3 A g\({}^{-1}\). (**b**) Discharge curve from (**a**). (**c**) Ragone plot of LCN-45 electrode. (**d**) Cycling stability for 1000 cycles at 1.0 A g\({}^{-1}\) of the LCN-45 electrode (Inset shows the GCD curves for the 1 st and 1000 th cycles).  
**Funding:** This work was supported by the Gwangju.Jeonnam local EnergyCluster Manpower training of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea government Ministry of Knowledge Economy (No. 2021400000560). This research was funded by the Creative Convergence Research Project under the National Science and Technology Research Council: Development of Ultra-Light/Ultra-Thin Electronic Device Manufacturing Technology with Free-Form Multifunctional Structure, MSIT-No. CAP22082-101.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The data that support the study are available from the corresponding author, Y.S., upon reasonable request. The data are not publicly available due to privacy.  
**Conflicts of Interest:** The authors declare no conflict of interest.