Self-Assembled Binary Organic Granules with Multiple Lithium Uptake Mechanisms toward High-Energy Flexible Lithium-Ion Hybrid Supercapacitors

Lithium-ion hybrid supercapacitors (Li-HSCs), by virtue of synergizing the merits of batteries and supercapacitors, have attracted considerable attention for high-energy/-power energy storage applications. Inorganic transition-metal compounds with pseudocapacitive characteristics have been widely investigated as promising anodes for use in advanced Li-HSCs. Nevertheless, the concept of using eco-friendly and naturally abundant organic compounds as anodes for Li-HSCs has rarely been realized so far, due to their inferior electrical and ionic conductivity and low capacitive activity. Herein, an innovative self-assembly strategy to synthesize uniform binary organic granules as high-capacitive and durable anodes for the construction of high-energy flexible Li-HSCs is reported. The unique architecture of maleic acid@polyvinylidene fluoride (MA@PVDF) granules consisting of ultrafine MA nanocrystals within a PVDF network offers multiple lithium storage mechanisms including two-electron lithiation/delithiation, Li+-ion intercalation/deintercalation within the MA (020) planes, and Li+-ion adsorption/desorption at the MA nanocrystals/electrolyte interface. The as-constructed 4.3 V Li-HSC full cell comprising a MA@PVDF anode and an activated carbon cathode delivers high energy/power densities (158.4 Wh kg(-1)/107.5 W kg(-1) and 70.9 Wh kg(-1)/10750 W kg(-1)), outperforming those of organic anode-based Li/Na-HSCs and the state-of-the-art inorganic hybrid capacitors. The deriving prototype flexible Li-HSC devices manifest exceptional energy output under various deformed conditions and bent-release cycling.