High-Performance Nanostructured Electrodes For Next Generation Supercapacitors

Abstract

Nanostructured electrode materials define the performance ceiling of next-generation supercapacitors, yet the 
relationships that link textural descriptors, charge-transfer kinetics and device-level metrics are seldom 
quantified across a common experimental baseline. This work reports an empirical, data-analytic investigation 
of five electrode systems activated carbon (AC), multi-walled carbon nanotubes (MWCNT), reduced graphene 
oxide (rGO), manganese dioxide/rGO (MnO2/rGO) and nickel cobaltite/rGO (NiCo2O4/rGO) synthesised and 
characterised under identical conditions in 1 M KOH electrolyte using X-ray diffraction, nitrogen sorption, cyclic 
voltammetry, galvanostatic charge discharge (GCD) and electrochemical impedance spectroscopy (EIS). Specific 
capacitance, rate capability, Coulombic efficiency and 10,000-cycle stability were measured in triplicate and 
analysed by one-way analysis of variance (ANOVA), Pearson correlation and multiple linear regression (MLR). 
The specific capacitance at 1 A g−1 spanned a 7.6-fold range, from 156 F g−1 for MWCNT to 1186 F g−1 for 
NiCo2O4/rGO, whereas high-rate retention from 0.5 to 20 A g−1 remained confined between 40.9 % and 50.4 %. 
ANOVA established that electrode chemistry accounts for the dominant share of capacitance variance (F(4,25) 
= 54.08, p < 0.001, η2 = 0.896), while regression identified charge-transfer resistance and the high-frequency 
knee frequency as the strongest predictors of rate behaviour (adjusted R2 = 0.884, p < 0.001). The optimised 
NiCo2O4/rGO asymmetric device delivered 52.3 Wh kg−1 at 800 W kg−1 with 97.6 % retention after 10,000 cycles, 
7.6 times the energy density of the symmetric activated-carbon cell. The analysis demonstrates that 
pseudocapacitive nanoflakes anchored on a conductive rGO scaffold decouple energy density from rate 
capability, yielding a statistically validated design rule for next-generation supercapacitor electrodes.