Anti-catalytic strategy to build wide voltage and excellent flexibility symmetric yarn supercapacitors

Yarn-based supercapacitors have garnered significant attention as promising power systems due to the rise of wearable and portable electronics demands. However, persistent challenges including insufficient energy density and poor energy efficiency remain limited their widespread applications. Here, an innovative anti-catalytic strategy is developed, utilizing in-situ growth of S-doped carbon particle array on carbon-based yarn (SC@CBY) to offer electric double-layer capacitive and subsequently electrodeposition homogeneous manganese dioxide (MnO₂) nanosheets to supply pseudo-capacitive (MnO₂-SC@CBY). Driven by the effective and excellent anti-catalytic strategy, the voltage window of Faradaic redox reactions for MnO₂-SC@CBY were well coordinated by hydrolysis process, so that oxygen reduction reaction (OER) and hydrogen evolution reaction (HER) were tremendously restrained at high potential under aqueous electrolytes. Therefore, the as-prepared MnO₂-SC@CBY symmetric yarn supercapacitors feature a broad operating voltage of 1.5 V (far exceeding water splitting 1.23 V), high areal capacitance and energy density (69.1 mF cm^-2 / 1 mA cm^-2; 21.6 μWh cm^-2 / 14.7 mW cm^-2), along with a prolonged cycle lifespan (maintained at 88.97% after 15,000 cycles). More importantly, the assembled yarn supercapacitors can maintain accordant electrochemical performance at various winding conditions, manifesting high flexibility and good practicality of this yarn device. This work offers a novel direction toward symmetric yarn supercapacitors as the power source with high energy density and excellent flexibility.