High‐Rate and High‐Volumetric Capacitance of Compact Graphene–Polyaniline Hydrogel Electrodes

High-rate and high-volumetric pseudocapacitance is generally considered very challenging to achieve. It is reported that a compact polyaniline–graphene hydrogel film can provide a combination of high-volumetric pseudocapacitance, excellent rate capability, and long cycle life. The pore connectivity, which ensures fast ion transport, and well-maintained nanostructured polyaniline in the compact electrode is the key.