Constructing crystalline NiCo2O4/amorphous MoNiCo-LDH through high valence Mo doping for high-performance hybrid supercapacitors†

In this work, a crystalline/amorphous electrode material was prepared via a simple method. Specifically, high-valent Mo was introduced to fabricate amorphous MNC-LDH, which was then used to construct crystalline NCO/amorphous MNC-LDH composite materials. The prepared sample exhibited a three-dimensional pompom-like structure composed of ultrathin nanoflakes and a hybrid interface between crystalline and amorphous phases, which benefited its electrochemical performance. The synthesized material showed a specific capacity of 841 C g⁻¹ at 1 A g⁻¹, while retaining 82.3% of its initial capacity at 20 A g⁻¹. The assembled NCO/MNC-LDH//AC HSC device exhibited an energy density of 58 Wh kg⁻¹ when the power density was 850 W kg⁻¹. It is noteworthy that even at a power density of 8500 W kg⁻¹, an energy density of 37.1 Wh kg⁻¹ was maintained. NCO/MNC-LDH//AC retained 76.3% of its initial specific capacitance and 100% coulombic efficiency after 20 000 consecutive charge and discharge cycles, demonstrating excellent cycling stability. Furthermore, the ability of two HSCs connected in series to power small fans and light LEDs in various colors indicated the material's practical application potential. The synthesized NCO/MNC-LDH thus demonstrates promise as a supercapacitor electrode material, providing valuable insights for designing crystalline/amorphous composites in electrochemical energy storage.