To reduce the environmental damage caused by lithium-ion batteries (LIBs) and plastic waste, this study focused on the

synthesis of Li-based (AME) and Co-based (PURE) electrolytes using electrodes recycled from spent LIBs obtained from

cell phones. In addition, graphene (Gr) based supercapacitor (SC) electrodes were developed using recycled high-density

polyethylene as the supporting material. First, reference SCs were made with AME (Gr-AME-SC) and PURE (Gr-PURE-SC)

electrolytes, which exhibited specific capacitance/energy–density of 661.0 F g−1/132.2 W·h kg−1 and 426.1 F g−1/85.2 W·h

kg−1, respectively. Next, the TiO2/MoS2 (TMS) composite was integrated into the SC electrodes, resulting in a 52.5% increase

in specific capacitance for the SC fabricated with AME electrolyte (Gr/TMS-AME-SC) and a 20% increase in capacitance

occurred for the device with PURE electrolyte (Gr/TMS-PURE-SC), respectively. Notably, the Gr/TMS-AME-SC device,

which used the AME electrolyte, exhibited a specific capacitance that was 97% higher than that of the Gr/TMS-PURE-SC

device, which employed the PURE electrolyte. Furthermore, both the Gr/TMS-AME-SC and Gr/TMS-PURE-SC devices

exhibited remarkable electrochemical stability, attributed to the high decomposition voltages of the AME (1.51 V) and PURE

(1.48 V) electrolytes. Additionally, analyses performed using UV–Vis, Raman, and XPS spectroscopies revealed that oxygen

vacancies, together with Ti3+/Ti4+, Mo4+/Mo6+, and S2−/S6+ species, act as redox centers responsible for charge storage

by redox reactions in the SC electrodes. Moreover, this study revealed that exposing the SC made with AME electrolyte to

sunlight for 2 h enhanced the capacitance to the ultimate value of 1361.8 F g−1. Hence, SCs studied here could help to reduce

the environmental pollution because they were fabricated with materials recycled from spent LIBs.