Fabrication and morphological effect of waxberry-like carbon for high-performance aqueous zinc-ion electrochemical storage

Promoting and enhancing the transport rate of multivalent electrolyte ions in the pores of electrode is central for constructing high-performance electrochemical devices. Herein, waxberry-like porous carbon with nanosheets packaged by spherical carbon particles is produced by adjusting separation of hydrophilic and hydrophobic parts of carbon source precursors. The carbon particles maintain their original morphology after KOH activation at high temperature, forming tunable pores (pore volume: 0.9386 cm3 g−1) on the surface of stacked nanosheet layers. Benefiting from the synergistic effect of structural features, an interfacial transport of aqueous zinc ions within the carbon electrodes is achieved, endowing the assembled zinc-ion hybrid supercapacitors (ZHSCs) with excellent energy storage performances, including high capacity (122.3 mAh g−1 at 0.1 A g−1), high energy density (97.78 Wh kg−1), large power density (8000 W kg−1), and cycling stability up to 10,000 cycles with capacity retention of 98%. Moreover, the ZHSCs show superior low-temperature performance and operability (78.27 mAh g−1 at −30 °C and three-time cycling stability between −20 and 20 °C without performance degradation). This work presents a new prospect on design and development of aqueous rechargeable zinc-ion energy storage devices that are available for a range of environmental conditions.