Occupying in Metal−Organic Frameworks’ Pores: Vein‐Like PANI Cross‐Coupled Hierarchical Porous UiO‐66 Flexible Electrode for Supercapacitor Application

Abstract Although extending conductive polymer chains into the pores of Metal–Organic Frameworks (MOFs) leverages their advantage of high conductivity and ultra‐high surface area for “double‐high” electrode materials, only the surface pores of MOFs bulk can be occupied by conducting polymer by reported methods. To solve these issues, a selective etching and subsequent electrochemical polymerization strategy is employed. First, the hierarchical porous UiO‐66 (HPMOF) is prepared by acetate etching process, creating abundant mesopores and vein‐like channels that facilitate fast mass feeding of aniline monomers during electrochemical polymerization. Then, vein‐like PANI chains intersect HPMOF bulks and cross‐couples with HPMOF networks, which not only ensure that the inner pore surface is accessible to electrons but also dramatically increases surface area and cycle stability of PANI due to the nano‐confined effect. Therefore, the optimized HPMOF‐20h@PANI electrode showcases exceptional electron transport and ion accessibility, as evidenced by a remarkable specific capacitance of 6507 mF cm⁻² at 2 mA cm⁻² and retention of 82.1% capacitance after 5000 cycles. Furthermore, the as‐fabricated soft‐pack symmetric supercapacitor exhibits an energy density of 0.293 mWh cm⁻² at a power density of 1.28 mW cm⁻². This work provides a new route to design flexible “double‐high” electrodes and broadens the horizons in wearable electronics.