Nanoflower-like hollow NiMnCo-OH decorated with self-assembled 2D Ti₃C₂T_x for high-efficiency hybrid supercapacitors

Layered double hydroxides (LDHs) have gained awareness as promising energy materials due to their high electrochemical activity and tunable interlayer characteristics. However, inherent drawbacks limit them to achieve high capacitance. Introducing complementors with high conductivity and stability is an effective strategy for addressing these challenging issues. Therefore, we employed a simple and controllable method to synthesize nanoflower-like hollow NiMnCo-OH@MXene (NMCM) composites by multi-element doping and electrostatic self-assembly strategies. The MXene nanosheets formed a three-dimensional (3D) conductive network, which increased stability and promoted fast charge transport at interfaces. At the same time, the heterogeneous ternary hydroxides inhibited MXene aggregation and provided considerable capacitance. The NMCM showed ultra-long cycling stability of 91.7% after 5000 cycles at 5 A g-1 (compared to the initial specific capacitance) and achieved a capacitance capacity of 232.37 mAh g-1 at 1 A g-1 in a three-electrode device. Furthermore, under 800 W kg-1 power density, the NMCM//Ti3C2 asymmetric device showed an impressive energy density of 54.1 Wh kg-1. This work demonstrates a simple and successful strategy for creating high-performance energy storage devices based on 3D hollow framework electrodes.