Ultrathin Tape-Supercapacitor with High Capacitance and Durable Flexibility via Repeated In-situ Polymerizations of Polyaniline

Flexible supercapacitors (FSCs) are among the essential power suppliers of flexible electronics, while it is still challenging to achieve the high-performance, flexible, ultrathin and reliable targets concurrently. This work proposes the repeated in-situ chemical solution polymerizations (ICSPs) of polyaniline (PANI) on graphite-coated polyimide tape, and assembles the electrodes into self-encapsulated FSCs. Repeated ICSPs can increase the mass load of PANI and significantly influence its morphological, chemical and crystalline structures, as well as electronic and ionic transports, greatly increasing final energy-storage properties. The tape electrodes show maximum specific capacitances of 1955 mF cm⁻² (1068F g⁻¹) at 0.4 mA cm⁻² and 1089 mF cm⁻² (595F g⁻¹) at 10 mA cm⁻². Tape acts as substrates and packaging simultaneously. Consequently, the self-encapsulated FSCs show ultrathin thickness (∼200 μm), high areal and volumetric capacitances (481 mF cm⁻² and 24F cm⁻³), durable flexibility (retaining a maximum of ∼ 97% after thousands of presses, bends, rolls, folds, twists, beats and even crumples for the FSC that was previously placed at open air over 2 months) and high device reliability. This work provides a prototype for reliable and advanced FSCs.