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.