Hybrid energy storage systems have shown great promise for many applications; however, achieving high energy and power densities with long cycle stability remains a major challenge. Here, a strategy to synthesize high-tap density anode and cathode structures that yield ultrahigh performance in hybrid energy storage is reported. First, vinyl acetate monomers are polymerized into molecular sizes via chain reactions controlled by the surface free radicals of graphene and metals. Subsequently, molecular-size polymers are thermally evaporated to construct battery-type anode structures with encapsulated tin metals for high-capacity and stratified graphene pliable pockets (GPPs) for fast charge transfer. Similarly, sulfur particles are attached to GPPs via monomeric polymerization, and capacitor-type hollow GPP (H@GPP) cathode structures are produced by evaporating sulfur, where sublimated S particles yield mesopores for rapid anion movement and micropores for high capacity. Moreover, hybrid full-cell devices with high-tap density anodes and cathodes show high gravimetric energy densities of up to 206.9 Wh kg-1 , exceeding those of capacitors by ≈16-fold, and excellent volumetric energy densities of up to 92.7 Wh L-1 . Additionally, they attain high power densities of up to 23 678 W kg-1 , outperforming conventional devices by a factor of ≈100, and long cycle stability over 10 000 cycles.
Keywords: battery-type anode structures; capacitor-type cathode structures; high energy and power densities; hybrid energy storages; robust cycle stability.
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