To improve Li storage capacity and the structural stability of Ti₃C₂ MXene-based electrode materials for lithium-ion batteries (LIBs), a facile strategy is developed to construct three-dimensional (3D) hierarchical porous Ti₃C₂/bimetal-organic framework (NiCo-MOF) nanoarchitectures as anodes for high-performance LIBs. 2D Ti₃C₂ nanosheets are coupled with NiCo-MOF nanoflakes induced by hydrogen bonds to form 3D Ti₃C₂/NiCo-MOF composite films through vacuum-assisted filtration technology. The morphology and electrochemical properties of Ti₃C₂/NiCo-MOF are influenced by the mass ratio of MOF to Ti₃C₂. Owing to the interconnected porous structures with a high specific surface area, rapid charge transfer process, and Li⁺ diffusion rate, the Ti₃C₂/NiCo-MOF-0.4 electrode delivers a high reversible capacity of 402 mAh g⁻¹ at 0.1 A g⁻¹ after 300 cycles; excellent rate performance (256 mAh g⁻¹ at 1 A g⁻¹); and long-term stability with a capacity retention of 85.7% even after 400 cycles at a high current density, much higher than pristine Ti₃C₂ MXene. The results highlight that Ti₃C₂/NiCo-MOF have great potential in the development of high-performance energy storage devices.

A facile two-step strategy is adopted to construct a free-standing composite paper of MnO₂ nanoflake/polyaniline (PANI) nanorod hybrid nanostructures on reduced graphene oxide (RGO) for flexible supercapacitor electrode application.

In this work, a facile two-step strategy is adopted to construct hierarchical polyaniline/NiCo-layered double hydroxide (PANI/NiCo-LDH) core-shell composite nanofiber networks on carbon cloth (CC). Three-dimensional (3D) porous PANI nanofiber networks are firstly uniformly anchored on CC by in-situ oxidative polymerization, followed by growth of NiCo-LDH nanoflakes on the crosslinked PANI framework via electrochemical deposition. The morphology and electrochemical properties of PANI/NiCo-LDH composites are controlled by the deposition time of LDH. Benefiting from rapid electron transport and ion diffusion, the well-defined PANI/NiCo-LDH hierarchical composite with 200 s deposition of LDH delivers a large capacitance of 1845 F g⁻¹ at 0.5 A g⁻¹ and excellent cycling stability of 82% capacitance retention after 5000 cycles at a very high current density of 10.0 A g⁻¹. Furthermore, an asymmetric supercapacitor (ASC) assembled with PANI/NiCo-LDH as a positive electrode and activated carbon (AC) as a negative electrode exhibits a high capacitance of 147.2 F g⁻¹ in a potential range from 0 to 1.5 V and superior energy density of 46.0 Wh kg⁻¹ at a power density of 351.6 W kg⁻¹.

In this work, a two-step electrodeposition strategy is developed for the synthesis of core-shell Co₃O₄@CoS nanosheet arrays on carbon cloth (CC) for supercapacitor applications. Porous Co₃O₄ nanosheet arrays are first directly grown on CC by electrodeposition, followed by the coating of a thin layer of CoS on the surface of Co₃O₄ nanosheets via the secondary electrodeposition. The morphology control of the ternary composites can be easily achieved by altering the number of cyclic voltammetry (CV) cycles of CoS deposition. Electrochemical performance of the composite electrodes was evaluated by cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance spectroscopy techniques. The results demonstrate that the Co₃O₄@CoS/CC with 4 CV cycles of CoS deposition possesses the largest specific capacitance 887.5 F·g⁻¹ at a scan rate of 10 mV·s⁻¹ (764.2 F·g⁻¹ at a current density of 1.0 A·g⁻¹), and excellent cycling stability (78.1% capacitance retention) at high current density of 5.0 A·g⁻¹ after 5000 cycles. The porous nanostructures on CC not only provide large accessible surface area for fast ions diffusion, electron transport and efficient utilization of active CoS and Co₃O₄, but also reduce the internal resistance of electrodes, which leads to superior electrochemical performance of Co₃O₄@CoS/CC composite at 4 cycles of CoS deposition.

Hierarchical copper oxide @ ternary nickel cobalt sulfide (CuO/Cu₂O@NiCo₂S₄) core-shell nanowire arrays on Cu foam have been successfully constructed by a facile two-step strategy. Vertically aligned CuO/Cu₂O nanowire arrays are firstly grown on Cu foam by one-step thermal oxidation of Cu foam, followed by electrodeposition of NiCo₂S₄ nanosheets on the surface of CuO/Cu₂O nanowires to form the CuO/Cu₂O@NiCo₂S₄ core-shell nanostructures. Structural and morphological characterizations indicate that the average thickness of the NiCo₂S₄ nanosheets is ~20 nm and the diameter of CuO/Cu₂O core is ~50 nm. Electrochemical properties of the hierarchical composites as integrated binder-free electrodes for supercapacitor were evaluated by various electrochemical methods. The hierarchical composite electrodes could achieve ultrahigh specific capacitance of 3.186 F cm⁻² at 10 mA cm⁻², good rate capability (82.06% capacitance retention at the current density from 2 to 50 mA cm⁻²) and excellent cycling stability, with capacitance retention of 96.73% after 2000 cycles at 10 mA cm⁻². These results demonstrate the significance of optimized design and fabrication of electrode materials with more sufficient electrolyte-electrode interface, robust structural integrity and fast ion/electron transfer.