Electrochemical Supercapacitor Application of Electrochemically Produced Chlorine-Doped Graphene Oxide with Cobalt Sulfide-Based Compounds Produced from Recycling of Spent Li-Ion Batteries

Recycling of LiCoO2 (LCO) based Li-ion batteries for energy storage systems is crucial both environmentally and economically. Reusing active species of LCO cathodes minimizes waste and conserves resources, promoting sustainability in energy storage. We have investigated repurposing cobalt from spent LiCoO2 (LCO) type Li-ion batteries into a cobalt sulfide-based compound (CS), which was then employed as an electrode material in asymmetric supercapacitors. Initially, the LCO cathode compound underwent leaching, resulting in the precipitation of CS utilizing the sulfur source derived from cobalt ions present in the solution. Furthermore, chlorine-doped graphene oxide (Cl-GO) was synthesized via the chronoamperometric method utilizing a 5 M perchloric acid solution. Produced CS and Cl-GO were characterized by using spectroscopic and microscopic techniques. The resulting CS and Cl-GO powders were combined to form the composite positive electrode of coin cell type asymmetric supercapacitors (CCTAS), with graphite powder (GP) utilized in the preparation of the negative electrode. CCTAS were also characterized by using electrochemical techniques such as cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge-discharge. The highest areal capacitance, recorded as 101 mF.cm-2 at a scan rate of 10 mV.s-1, was achieved in the CS/Cl-GO%15//GP CCTAS, with a capacitance retention of approximately 94% observed after 1000 cycles.