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

• Solid state supercapacitors (SCs) were made using face mask waste and medical blister packs. • Adding the redox material of Ca 3 Co 4 O 9-δ into the SCs enhanced the capacitance by ≈108%. • The presence of Ca 3 Co 4 O 9-δ in the SC electrodes prolonged the discharge times to 10 h. • The redox centers that enthanced the electrochemical performance were the oxygen vacancies and the Co 2+ /Co 3+ species. 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 Ca 3 Co 4 O 9-δ (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 µm. 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 ≈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 Co 2+ /Co 3+ 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.