Template‐oriented synthesis of boron/nitrogen‐rich carbon nanoflake superstructure for high‐performance Zn‐ion hybrid capacitors

Abstract The rise of Zn‐ion hybrid capacitor (ZHC) has imposed high requirements on carbon cathodes, including reasonable configuration, high specific surface area, multiscale pores, and abundant defects. To achieve this objective, a template‐oriented strategy coupled with multi‐heteroatom modification is proposed to precisely synthesize a three‐dimensional boron/nitrogen‐rich carbon nanoflake‐interconnected micro/nano superstructure, referred to as BNPC. The hierarchically porous framework of BNPC shares short channels for fast Zn 2+ transport, increased adsorption‐site accessibility, and structural robustness. Additionally, the boron/nitrogen incorporation effect significantly augments Zn 2+ adsorption capability and more distinctive pseudocapacitive nature, notably enhancing Zn‐ion storage and transmission kinetics by performing the dual‐storage mechanism of the electric double‐layer capacitance and Faradaic redox process in BNPC cathode. These merits contribute to a high capacity (143.7 mAh g −1 at 0.2 A g −1 ) and excellent rate capability (84.5 mAh g −1 at 30 A g −1 ) of BNPC‐based aqueous ZHC, and the ZHC still shows an ultrahigh capacity of 108.5 mAh g −1 even under a high BNPC mass loading of 12 mg cm −2 . More critically, the BNPC‐based flexible device also sustains notable cyclability over 30,000 cycles and low‐rate self‐discharge of 2.13 mV h −1 along with a preeminent energy output of 117.15 Wh kg −1 at a power density of 163.15 W kg −1 , favoring a creditable applicability in modern electronics. In/ex‐situ analysis and theoretical calculations elaborately elucidate the enhanced charge storage mechanism in depth. The findings offer a promising platform for the development of advanced carbon cathodes and corresponding electrochemical devices.