Self-supported hierarchical bead-chain graphite felt@FePO4@polyaniline: A flexible electrode for all-solid-state supercapacitors with ultrahigh energy density

The relatively low energy density of all-solid-state flexible supercapacitors (AFSCs) is the major bottleneck for their practical applications. Hence, rational designs and constructions of highly desirable hybrid electrodes with ultrahigh energy densities for AFSCs are critically important but challenging. Herein, we report a design of a novel hierarchical graphite felt (GF)@FePO4@polyaniline (PANI) bead-chain hybrid with three-dimensional networking PANI-coated FePO4 nanorods as beads and high conductive carbon fibers of GF as links. Benefiting from the robust synergistic effect between FePO4 and PANI together with plentiful conductive networks emanating from the intimate contacts among GF, FePO4 and PANI, the GF@FePO4@PANI hybrid exhibits overwhelmingly superior supercapacitive performance to GF@FePO4 and GF@PANI. More strikingly, with GF@FePO4@PANI as the binder-free electrode, the assembled symmetric AFSC device shows an ultrahigh energy density of 90.2 Wh kg(-1) at a power density of 142.9Wkg(-1), and 29.0 Wh kg(-1) even at an elevated power density of 5714.6 Wk g(-1), which are amongst the top of the reported analogous flexible devices. To the best of our knowledge, this is the first report on the fabrication of GF@FePO4@PANI for AFSC applications.