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The electrochemical properties of the metal–organic framework (MOF)-based composite as electrode material can be significantly improved by means of partial destruction of the full coordination of linkers to metal ions and replacing with other small ions, which make metal centers become more accostable and consequently more effective for the lithiation/delithiation process. In this paper, F–was chosen to replace some of the benzenedicarboxylate (BDC) linkers because of its better interaction with the Li+than the oxide ion. What’s more, the formed M–F bond promotes the Li+to transfer at the active material interface and protects the surface from HF attacking. The as-synthesized F-doped Mn-MOF electrode maintains a reversible capacity of 927 mA h g–1with capacity retention of 78.5% after 100 cycles at 100 mA g–1and also exhibits a high discharge capacity of 716 mA h g–1at 300 mA g–1and 620 mA h g–1at 500 mA g–1after 500 cycles. Even at 1000 mA g–1, the electrode still maintains a high reversible capacity of 494 mA h g–1after 500 cycles as well as a Coulombic efficiency of nearly 100%, which is drastically increased compared with pure Mn-MOF material as expected.

This study reports a simple synthesis of amorphous nickel tungstate (NiWO4) nanostructure and its application as a novel cathode material for supercapacitors. The effect of reaction temperature on the electrochemical properties of the NiWO4electrode was studied, and results demonstrate that the material synthesized at 70 °C (NiW-70) has shown the highest specific capacitance of 586.2 F g–1at 0.5 A g–1in a three-electrode system. To achieve a high energy density, a NiW-70//activated carbon asymmetric supercapacitor is successfully assembled by use of NiW-70 and activated carbon as the cathode and anode, respectively, and then, its electrochemical performance is characterized by cyclic voltammetry and galvanostatic charge–discharge measurements. The results show that the assembled asymmetric supercapacitor can be cycled reversibly between 0 and 1.6 V with a high specific capacitance of 71.1 F g–1at 0.25 A g–1, which can deliver a maximum energy density of 25.3 Wh kg–1at a power density of 200 W kg–1. Furthermore, this asymmetric supercapacitor also presented an excellent, long cycle life along with 91.4% specific capacitance being retained after 5000 consecutive times of cycling.