Acetaminophen: a novel redox-additive for snowballing the energy density of flexible supercapacitors

Increasing the energy density of carbon-based electrodes is one of the important missions in the field of supercapacitors. The best strategy to proliferate the energy density of a supercapacitor is harnessing redox additives with conventional electrolytes. Here, acetaminophen has been adopted as a redox additive with H2SO4 for the first time to increase the energy density of the supercapacitor electrode. The specific capacitance of the electrode increased 2 times after the addition of acetaminophen with H2SO4. A flexible supercapacitor (FSC) was fabricated using polyvinyl alcohol (PVA)/H2SO4 and acetaminophen/PVA/H2SO4 gel electrolytes. The energy density of the FSC with acetaminophen/PVA/H2SO4 (26.4 W h kg(-1)) was similar to 3-fold higher than that with PVA/H2SO4 (7 W h kg(-1)). Due to the reversible redox process of acetaminophen to N-acetyl-p-benzoquinone-imine in H2SO4, the electrochemical performance of the supercapacitor electrodes was boosted. The FSC retained 95% of its original capacitance even after 12 000 cycles. Moreover, the ionic conductivity of the PVA/H2SO4 gel electrolyte increased from 2.6 to 9.6 mS cm(-1) as a result of adding acetaminophen, which might also be the reason for the excellent energy density of FSC.

Automated summary

Using acetaminophen as a redox additive with H2SO4, the energy density of supercapacitor electrodes can be increased. The reversible redox process of acetaminophen enhances the electrochemical performance of the supercapacitor electrodes and increases the ionic conductivity of PVA/H2SO4 gel electrolyte, resulting in excellent energy density of the flexible supercapacitor.