One-pot preparation of La-doped Ni-MOF nanospheres for efficient hybrid supercapacitor electrode material

Abstract

Promoting the inherent conductivity and stability can boost the possible application of most metal-organic frameworks (MOFs) in the energy storage and conversion devices. Herein, La-doped Ni-MOF materials (La-NMF) are achieved via a simple one-pot hydrothermal process, which shows an enhanced electrochemical performance and stability compared with Ni-MOF. The La-NMF electrode with 10 wt% of La doping (La-NMF-0.1) possesses the optimum performance with the specific capacity of 159.9 mA h g −1 at 1 A g −1 , much higher than that of Ni-MOF (100.4 mA h g −1 ). Moreover, the assembled hybrid supercapacitor containing the La-NMF-0.1 positive electrode achieves a high energy density of 38.3 W h kg −1 at a power density of 375 W kg −1 , and remains 86.7% of the capacity retention after 5000 cycles at 5 A g −1 . The density functional theory (DFT) calculation reveals that La doping boosts the electron density at conduction band near Fermi level , which improves the capability of charge transfer and electronic conductivity of materials. The larger surface area , rapider charge transfer and more excellent electronic conductivity endow La-NMF-0.1 with a superior electrochemical performance compared to Ni-MOF. This work provides some insights for design and facile fabrication of the advanced materials in the new energy fields.