Structural engineering of metal-organic frameworks cathode materials toward high-performance flexible aqueous rechargeable Ni–Zn batteries

Metal-organic frameworks (MOFs) have aroused great attention due to their high porosity, low density, large specific surface area, regular porous channel, adjustable pore size, and multiple topological structure. MOFs featuring above characteristics demonstrate promising prospects for a category of crucial fields such as catalyst, energy-storage, and separation, especially in energy-storage system. However, due to the diversity of pores in MOF materials, it is difficult to take full advantage of the MOF materials to react with electrolyte ions during the charging and discharging process. Herein, by choosing different ligands, a DHTP-Ni-MOF nanoflower arrays (NFAs) with high specific surface area and large pore size were successfully directly grown on carbon nanotube fiber (CNTF) as the cathode to construct a high-performance fiber-shaped aqueous rechargeable (FAR) Ni//Zn batteries. Profiting the superiorities of the DHTP-Ni-MOF, the DHTP-Ni-MOF NFAs/CNTF electrode can deliver an ultrahigh capacity of 0.47 mAh cm⁻² at a high current density of 4 mA cm⁻², and demonstrate an excellent rate capability (0.32 mAh cm⁻² at 80 mA cm⁻²). Importantly, our assembled FAR Ni//Zn batteries exhibit an ultrahigh energy density of 215.01 mWh cm⁻³ at power density of 2.39 W cm⁻³. This approach provides an innovative idea for constructing high-performance flexible aqueous energy-storage devices.