Hydrothermal Growth of Ce-Mn-Co Trimetallic Oxide-Hydroxides on Carbon Cloth toward Flexible Solid-State Supercapacitors

In recent years, flexible and portable supercapacitors have attracted significant attention as next-generation energy storage devices. However, identifying and fabricating suitable electrode materials remains a major challenge. In this study, a simple hydrothermal method was used to grow Ce-Mn-Co trimetallic oxide-hydroxide structures on a flexible carbon cloth substrate (CC), providing a practical approach for developing high-performance electrodes. Systematic optimization of the Ce:Mn:Co molar ratios showed that the 1:1:1 composition Ce 1 -Mn 1 -Co 1 ) offers superior charge-storage capability, as confirmed by comparative electrochemical evaluations across various ratios. The Ce 1 -Mn 1 -Co 1 @CC electrode outperformed both its binary and other ternary oxide-hydroxide counterparts, delivering a high areal specific capacitance of 220.5 mF/cm 2 at 1.5 mA/cm 2 in 1.0 M Na 2 SO 4 under a three-electrode configuration. This outstanding performance is attributed to the synergistic effects among the Ce, Mn, and Co species. A flexible quasi-solid-state symmetric supercapacitor was subsequently assembled using a PVA/Na 2 SO 4 gel electrolyte. The symmetric Ce 1 -Mn 1 -Co 1 @CC//Ce 1 -Mn 1 -Co 1 @CC device achieved an energy density of 50.3 µWh/cm 2 and a power density of 835.8 µW/cm 2 . The device retained 86% of its initial capacitance after 10000 charge-discharge cycles at 4 mA/cm 2 , demonstrating excellent cycling stability and durability. The device also retained stable electrochemical performance under various bending angles, confirming the mechanical robustness of the flexible architecture. These findings highlight the strong potential of Ce-Mn-Co trimetallic oxide-hydroxide grown on carbon cloth as a high-performance and durable electrode material for next-generation energy storage systems, offering an attractive balance of energy and power densities.