Boosting Zn‐Ion Storage Behavior of Pre‐Intercalated MXene with Black Phosphorus toward Self‐Powered Systems

Abstract

MXene‐based Zn‐ion capacitors (ZICs) with adsorption‐type and battery‐type electrodes demonstrate high energy storage and anti‐self‐discharge capabilities, potentially being paired with triboelectric nanogenerators (TENGs) to construct self‐powered systems. Nevertheless, inadequate interlayer spacing, deficient active sites, and compact self‐restacking of MXene flakes pose hurdles for MXene‐based ZICs, limiting their applications. Herein, black phosphorus (BP)‐Zn‐MXene hybrid is formulated for MXene‐based ZIC via a two‐step molecular engineering strategy of Zn‐ion pre‐intercalation and BP nanosheet assembly. Zn ions as intercalators induce cross‐linking of MXene flakes with expandable interlayer spacing to serve as scaffolds for BP nanosheets, thereby providing sufficient accessible active sites and efficient migration routes for enhanced Zn‐ion storage. The density functional theory calculations affirm that zinc adsorption and diffusion kinetics are significantly improved in the hybrid. A wearable ZIC with the hybrid delivers a competitive areal energy of 426.3 µWh cm−2 and ultra‐low self‐discharge rate of 7.0 mV h−1, achieving remarkable electrochemical matching with TENGs in terms of low energy loss, matched capacity, and fast Zn‐ion storage. The resultant self‐powered system efficiently collects and stores energy from human motion to power microelectronics. This work advances the Zn‐ion storage of MXene‐based ZICs and their synergy with TENG in self‐powered systems.