In-situ synthesized and induced vertical growth of cobalt vanadium layered double hydroxide on few-layered VCT MXene for high energy density supercapacitors.

Two-dimensional (2D) MXene nanomaterials display great potential for green energy storage. However, as a result of self-stacking of MXene nanosheets and the presence of conventional binders, MXene-based nanomaterials are significantly hindered in their rate capability and cycling stability. We successfully constructed a self-supported stereo-structured composite (TMA-VCT/CoV-LDH/NF) by in-situ growing 2D cobalt vanadium layered double hydroxide (CoV-LDH) vertically on 2D few-layered VCT MXene nanosheets and interconnecting it with Ni foam (NF) with a self-supported structure to act as a binder-free electrode. In addition to inhibiting CoV-LDH aggregation, the highly conductive VCT MXene and CoV-LDH work synergistically to improve charge storage. The specific capacitance of the TMA-VCT/CoV-LDH/NF electrode is 2374 F/g (1187 C/g) at 1 A/g. At the same time, the TMA-VCT/CoV-LDH/NF exhibits excellent stability, retaining 85.3 % of its specific capacitance at 20 A/g after 10,000 cycles. In addition, the hybrid supercapacitor (HSC) is assembled based on positive electrode (TMA-VCT/CoV-LDH/NF) and negative electrode (AC), achieving the maximum energy density of 74.4 Wh kg at 750.3 W kg. TMA-VCT/CoV-LDH/NF has potential as an electrode material for storing green energy. The research strategy provides a development prospect for the construction of novel VCT MXene-based electrode material with self-supported structures.