Effect of RuO₂ Content on the Electrochemical Performance of PPy/WS₂-Based Ternary Supercapacitor Electrodes

A ternary composite electrode comprising polypyrrole (PPy), WS₂ (10 wt%), and varying amounts of RuO₂ (3-15 wt%) was systematically developed to investigate the influence of controlled RuO₂ incorporation on supercapacitor performance. The composites were synthesized via an in situ oxidative polymerization approach, enabling homogeneous integration of crystalline WS₂ nanosheets and RuO₂ nanoparticles within the conductive PPy matrix. Structural, morphological, and diffraction analyses confirmed the coexistence of all three components, revealing improved interfacial coupling, reduced crystallite size, and the formation of interconnected electron transport pathways. The optimized composition exhibited enhanced surface accessibility and facilitated ion diffusion across the electrode–electrolyte interface. Electrochemical evaluation demonstrated that gradual RuO₂ incorporation significantly increased the specific capacitance and rate capability. The optimized electrode delivered a maximum specific capacitance of 407.6 F g^-1 in a three-electrode configuration at 0.5 A g^-1. A symmetric two-electrode device of the same composition achieved 338.0 F g^-1 at 0.5 A g^-1, with excellent cycling stability, retaining stable performance over 2000 charge–discharge cycles. Impedance and kinetic analyses revealed reduced charge-transfer resistance and a transition from predominantly surface-controlled storage in pristine PPy toward a balanced electric double-layer and pseudocapacitive mechanism in the optimized composite. The improved electrochemical behavior is attributed to synergistic interactions among PPy, WS₂, and RuO₂, which collectively enhance electrical conductivity, redox activity, and structural robustness. These findings demonstrate that controlled RuO₂ loading is an effective strategy for engineering high-performance polymer-based supercapacitor electrodes.