Cerium Selenide Nanopebble/Multiwalled Carbon Nanotube Composite Electrodes for Solid-State Symmetric Supercapacitors

Flexible electronics have gained much interest, amplifying the need for advanced compact, lightweight, and bendable power sources. Present flexible supercapacitive energy-storage devices are restricted by poor mechanical properties, low cyclic stability, and small capacitance. Here, with state-of-the-art technology, cerium selenide nanopebbles are assembled with the aid of a controlled diffusive–capacitive mutualistic approach via a simple chemical method on multiwalled carbon nanotubes (MWCNTs) surfaces to design a hybrid nanostructure. The synthesized material has been well-characterized through structural, surface morphological, and elemental states by X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Benefiting from diffusive–capacitive control, the unique hybrid supercapacitor (SC) electrode delivered an excellent storage capability of 451.4 F/g (@2 mA/cm2) maintaining 70.7% (@4000 cyclic voltammetry (CV) cycles) capacitance retention. More prominently, supreme mechanical bending of the designed solid-state supercapacitor in the symmetric configuration with the help of a poly(vinyl alcohol) (PVA)-LiClO4 gel electrolyte yields 86.9% retention at a bending angle of 175° with improved performance compared to a liquid-configured (84.1%@4000 cycles) supercapacitor maintaining a remarkable capacitance of 128.8 F/g (@2 mV/s) with high power density (2.8–5.6 kW/kg at energy densities of 36.3–14.5 Wh/kg).