Highly efficient textile supercapacitors made with face masks waste and thermoelectric Ca3Co4O9-δ oxide

We studied the electrochemical performance of solid state supercapacitors (SCs) made with surgical face mask (FM) waste and blister packs recycled from paracetamol packaging. The Ca3Co4O9-delta (CaCo) oxide was also deposited on the SC electrodes to store charge by redox reactions. The CaCo microparticles had a plate-like morphology and had sizes in the range of 1-4 mu m. They also presented a monoclinic phase according to the analysis by the X-ray diffraction. The electrochemical characterization of the face mask-based SCs was carried out and found maximum capacitance/energy density values of 1706.2 F g(-1)/208.4 Wh kg(-1) and 816.8 F g(-1)/99.7 Wh kg(-1) for the SCs made with and without CaCo, respectively. Thus, incorporating the CaCo into the SCs improved the energy density and capacitance by approximate to 108%. The best device made with CaCo also presented a moderate capacitance retention of 82.1% after 1500 cycles of charge/discharge and long discharge times of at least 10 h (at a maximum output voltage of 0.54 V). Additionally, the devices were subjected to pressing conditions by putting on them weights of 0.1-0.5 Kg and their capacitance retention was only reduced by 0.7-1.5%. The analysis by XPS, Absorbance and Raman measurements pointed out that the SCs made with CaCo presented extra redox species of Co2+/Co3+ and oxygen vacancies on their electrodes; therefore, they could store charge by redox reactions. Hence, the results presented here revealed that highly efficient SCs are possible to make from medical waste and this could help to decrease the environmental contamination by plastic residuals.

Automated summary

The study demonstrated that incorporating CaCo oxide into solid state supercapacitors made from surgical face mask waste and blister packs recycled from paracetamol packaging can significantly improve energy density and capacitance. The devices showed high capacitance retention even under pressure conditions, with minimal decrease in capacitance. Analysis also revealed the presence of additional redox species and oxygen vacancies, indicating the ability of the devices to store charge efficiently through redox reactions.