Intrapore-Texturized Vanadia-Hydrate Supercapacitor with Ultrahigh Area-Normalized Capacitance

A pressing need for ultrahigh area‐normalized capacitance emerges from the migration to miniaturized composite supercapacitors. Herein, an advanced electric field‐assisted sol–gel synthesis protocol that allows to obtain ribbon‐like vanadium oxides that preferentially creep along the porous tunnels in a commercially available carbon host of low density is demonstrated. In particular, this design offers 1) to convert the original submicrometer‐sized pore network into hierarchically macroporous yet 3D‐interconnected bicontinuous composite frameworks and 2) to considerably add pseudo‐capacitive functionalities onto a highly conductive carbon cloth backbone. Both are demonstrated by an unprecedented area‐normalized capacitance exceeding 5 F cm−2. Moreover, the as‐designed symmetric supercapacitor is characterized by a maximum area‐normalized cell capacitance in the order of 1 F cm−2, a geometric energy density of 0.34 mW h cm−2, and a geometric power density of 28.3 mW cm−2. These features outperform commercial double‐layer supercapacitors as well as many state‐of‐the‐art composite pseudo‐capacitors and lithium‐ion microbatteries.