It is a reality that the world's growing energy resource consumption will increase the demand for materials made through recycling. The present study focuses on the production of new materials by recycling. The cathode of a discarded commercial Li-ion battery (LiCoO₂) was used to produce a CoS-based supercapacitor electrode material. The leaching of LiCoO₂ was done using 0.1 M H₂SO₄ aided by 1.0 M H₂O₂ at room temperature. After leaching, CoS was precipitated by the addition of Na₂S. For the first time, the precipitation of Co²⁺ ions leached from the cathode material was accomplished utilizing Na₂S as a sulfur source at room temperature and CoS was then used as an electrode material in a coin cell-type supercapacitor. The morphology and properties of the produced CoS were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET), and Mastersizer analyses. The electrode used in the supercapacitor was formed by combining CoS, carbon black, and polyvinylidene fluoride (PVDF) as the binder in varying compositions. The active materials were coated on the graphite foil and an asymmetric-type supercapacitor device was produced using 2 M KOH as the electrolyte. Using cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and electrochemical impedance spectroscopy (EIS) techniques, the electrochemical performances of supercapacitors were evaluated. In cyclic voltammetric analyses, the maximum potential range for supercapacitors was determined as −1.0 V to 1.0 V. The cycling performance of the supercapacitors was measured by CV analyses for 1000 cycles at 200 mV s⁻¹. The highest specific capacitance was obtained from the C80 electrode as 70.5 F g⁻¹ at a 1 A g⁻¹ charge/discharge current density.

Al₂O₃, TiO_2, and Al₂O₃-TiO₂ coatings were deposited on AISI 304 stainless steel plates by the sol–gel dipping technique, and the effects of the coating composition on microstructure, wear, and corrosion characteristics were examined. Tribological features were determined by ball-on-disc sliding tests against an Al₂O₃ ball under a 10 N load, while corrosion properties were evaluated by potentiodynamic polarisation tests performed in 3.5% wt. NaCl solution. γ-Al₂O₃, α-Al₂O_3, and rutile phases were detected in the hybrid coatings. The highest coating thickness was obtained in single Al₂O₃ film and decreased with an increasing amount of TiO₂ nanoparticles. The single Al₂O₃ layer had both the highest wear resistance and the lowest corrosion resistance. Although TiO₂ addition caused an increase in the wear rate, it improved the corrosion resistance of the coating by filling the voids in the Al₂O₃ film. The Al₂O₃-TiO₂ hybrid film with a relative ratio of 6:1 as a candidate for the wear- and corrosion-resistant coating decreased wear and corrosion losses of the 304 substrates by 83% and 97%, respectively.