All-climate aqueous fiber-shaped supercapacitors with record areal energy density and high safety

Flexible fiber-shaped supercapacitors (FSSs) are promising energy storage candidates for wearable electronics. However, most of reported FSSs are operated at room temperature and used the toxic flammable organic electrolyte or corrosive strong acid or base which may have safety hazards especially for wearable textiles directly sticking on the human skin at harsh environmental temperatures. Here we reported a new kind of aqueous symmetric FSSs with high safety and record high areal energy density at wide operating temperature ranging from − 60 °C (14.2 µW h cm−2) to 75 °C (22.9 µW h cm−2) based on aqueous LiCl-PVA based gel electrolyte and core-shell nanocrystalline polymer fiber electrode. The fabricated aqueous FSSs demonstrate high flexibility, high areal/volumetric energy density and stable cycle life at different operating temperatures, showing the potential application in all-climate wearable electronics.