Composition-Controlled PPy-WS₂-RuO₂ Ternary Nanocomposites with Enhanced Surface-Controlled Charge Storage for High-Performance Supercapacitors

A composition-controlled ternary polypyrrole/tungsten disulfide/ruthenium oxide (PPy-WS₂-RuO₂) nanocomposite was synthesized via in situ oxidative polymerization for high-performance supercapacitor applications. The WS₂ content was fixed at 10 wt%, while the RuO₂ loading was systematically varied from 3 to 15 wt% to investigate its influence on the structural and electrochemical properties. Structural, morphological, and spectroscopic characterizations confirmed the successful formation of a ternary composite with the homogeneous coexistence of PPy, WS₂, and RuO₂ within the composite framework. Electrochemical measurements performed in 1 M H₂SO₄ demonstrated a strong dependence of charge-storage performance on RuO₂ content. The optimized PWR9 electrode delivered a high specific capacitance of 407.6 F g⁻¹ at 0.5 A g⁻¹ from galvanostatic charge-discharge measurements and 239.3 F g⁻¹ at 10 mV s⁻¹ from cyclic voltammetry. Kinetic analysis based on b-value determination, Dunn's method, and Trasatti analysis revealed a progressive transition from diffusion-controlled to predominantly surface-controlled charge storage with increasing RuO₂ incorporation. Electrochemical impedance spectroscopy further confirmed the reduced charge-transfer resistance of the optimized ternary electrode. The PWR9 electrode retained 78.3% of its initial capacitance after 5000 charge-discharge cycles at 5 A g⁻¹. In a symmetric supercapacitor configuration, the optimized device achieved an energy density of 30 Wh kg⁻¹ at a power density of 800 W kg⁻¹, while maintaining 87.7% capacitance retention after 5000 cycles. These findings demonstrate that the rational engineering of a hierarchical PPy-WS₂-RuO₂ ternary architecture effectively promotes surface-controlled pseudocapacitive charge storage, leading to enhanced electrochemical performance for advanced energy-storage applications.