Hydrothermally obtained β-MnO2 nanoparticles/activated carbonized coconut fibers composites, electrochemical properties study for future energy storage devices.

[Display omitted] • Composite β -MnO 2 / activated carbonized coconut fibers was hydrothermally prepared. • Electrochemical properties of electrodes made of these materials were studied. • β -MnO 2 electrode shows a C sc value of 155.08 Fg−1 at 1 Ag−1 and 89.49% retention. • The best electrode shows a C sc value of 320.15 Fg−1 at 1 Ag−1 and 90.87% retention. • Symmetric coin cell gains a notable C sc value of 38.1 Fg−1 at 0.5 Ag−1 in 0–1.8 V. Pure β -MnO 2 (M) nanoparticles (Nps) and M Nps/activated carbonized coconut fiber (ACCF) composites (Cps), (M@ACCF Cps), with ACCF loadings 2.5, 5, 10 and 15% were hydrothermally synthesized. The phase, structure and morphology of ACCF, β -MnO 2 Nps and M@ACCF Cps were characterized using X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The chemical surface for oxidation state analysis of samples was studied using X-ray photoelectron spectroscopy (XPS). Specific surface area and pore structure were investigated using a Brunauer, Emmett and Teller (BET) technique. Electrochemical studies revealed a maximum specific capacitance (C sc), 320.15 ± 0.12F g−1, at 1 A g−1 for the M@ACCF10% Cps electrode with the excellent retention, 90.87%, at the 4000th cycle of a GCD test. Symmetric M@ACCF10% Cps coin cells demonstrated an outstanding capacitance value of 38.1 ± 0.2 F g−1 at 0.5 A g−1 over a voltage range of 0.0 – 1.8 V. [ABSTRACT FROM AUTHOR]