A Trifunctional Hydroxylated Borophene-Mediated MXene Enabled Super-Stable and Fast-Kinetics Interface Storage

The high electronic conductivity and tailorable structural properties of MXene materials make them promising candidates for energy storage. However, their poor chemical instability and self-stacking effect greatly limit their application, especially in aqueous systems. Here, using a eutectic etching approach, hydroxylated borophene is used as a trifunctional mediator to construct robust Ti3C2Tx-based MXene/B self-assembled film electrodes for zinc-ion capacitors (ZICs). Due to this mediator, the as-formed strong interfacial binding within the heterostructure can give rise to an integrated modification effect and promote high-efficiency interface energy storage. One is to strengthen the thermodynamic stability of local Ti & horbar;O bonds and inhibit the irreversible degradation of MXene; two is to enlarge the interface space of the MXene electrode and boost the ion transport; three is to improve the interfacial Zn2+ trapping ability without affecting Zn2+ migration on the MXene surface. Thus, the MXene/B electrode exhibits a high areal capacitance (537.9 mF cm-2) at a current density of 0.2 mA cm-2 and an extraordinary cycling stability at 1 mA cm-2, with 99.64% retention after 40 000 cycles, which far surpasses that of most previous reports. This work provides a pathway for overcoming the interface storage limit of MXene electrodes to construct high-performance ZICs. This report highlights the design concept of trifunctional hydroxylated borophene mediated self-assembled heterostructure electrode for zinc ion capacitors, to unlock an efficient interface storage with an unexpectedly 40000-cycle lifespan. Benefited from a multiscale interfacial synergistic effect, an integrated regulation of the self-stacking effect, ion capture capability and thermodynamic stability of Ti & horbar;O bond of the MXene electrode can be achieved. image