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Alloy materials have attracted increasing attentions because they possess superior electrical conductivity which can contribute to excellent electrochemical performance. Herein a dendritic Ni3C alloy material has been prepared by the pyrolysis of nickel acetylacetonate employing oleylamine as a reductant and 1-octadecene or octadecane as the solvent. The current–voltage curves indicating that the electrical conductivity of Ni3C is higher than that of nickel oxide. Electrochemical testing indicates that a high specific capacity of 390 C/g is found in alkaline electrolyte at 0.5 A/g, and deliver excellent rate characteristic as well as cycle life. The excellent electrochemical performance may be attributed to its high electrical conductivity and dendritic nanostructure that can promote diffusion of electrolyte ions. In addition, the AC//Ni3C asymmetric supercapacitor has been assembled at a cell voltages between 0 and 1.6 V, achieving a maximum energy density of 37 Wh/kg (at a power density of 0.3995 kW/kg), and this manifests that the Ni3C alloy is a promising electrode material for electrochemical energy storage.

The Co3O4/Co3V2O8/Ni nanocomposites were rationally designed and prepared by a two-step hydrothermal synthesis and subsequent annealing treatment. The one-dimensional (1D) Co3O4 nanowire arrays directly grew on Ni foam, whereas the 1D Co3V2O8 nanowires adhered to parts of Co3O4 nanowires. Most of the hybrid nanowires were inlayed with each other, forming a 3D hybrid nanowires network. As a result, the discharge capacity of Co3O4/Co3V2O8/Ni nanocomposites could reach 1201.8 mAh/g after 100 cycles at 100 mA/g. After 600 cycles at 1 A/g, the discharge capacity was maintained at 828.1 mAh/g. Moreover, even though the charge/discharge rates were increased to 10 A/g, it rendered reversible capacity of 491.2 mAh/g. The superior electrochemical properties of nanocomposites were probably ascribed to their unique 3D architecture and the synergistic effects of two active materials. Therefore, such Co3O4/Co3V2O8/Ni nanocomposites could potentially be used as anode materials for high-performance Li-ion batteries.

Co-P precursor was prepared by a mechanical alloying method and then is controlled to synthesis of CoP phase through an annealing method. The optimal conditions of ball milling and annealing temperature are investigated. The CoP exhibits higher electrical conductivity than graphite and cobalt oxide, showing excellent pseudocapacitive properties due its high electrical conductivity which can result in a fast electron transfer in high rate charge–discharge possess. The as-obtained CoP electrode achieves a high specific capacitance of 447.5 F/g at 1 A/g, and displays an excellent rate capability as well as good cycling stability. Besides, the asymmetric supercapacitor (ASC) based on the CoP as the positive electrode and activated carbon (AC) as the negative electrode was assembled and displayed a high rate capability (60% of the capacitance is retained when the current density increased from 1 A/g to 12 A/g), excellent cycling stability (96.7% of the initial capacitance is retained after 5000 cycles), and a superior specific energy of 19 Wh/kg at a power density of 350.8 W/kg. The results suggest that the CoP electrode materials have a great potential for developing high-performance electrochemical energy storage devices.

Flower-like Ni3P2O8 and flower-like Fe3P2O8·8H2O have been successfully synthesized by a simple chemical precipitation method. X-ray diffraction (XRD) patterns reveal an amorphous phase formation of nickel phosphate (Ni3P2O8) and pure monoclinic phase of Fe3P2O8·8H2O. The novel flower-like Ni3P2O8 and flower-like Fe3P2O8·8H2O when used for supercapacitor electrode materials exhibit a high specific capacitance (Cm) of 1464 F/g and 200 F/g at a current density of 0.5 A/g, respectively. Eventually, an asymmetric supercapacitor is fabricated using Ni3P2O8 as positive electrode and Fe3P2O8·8H2O as negative electrode. A high specific capacitance of 94 F/g is achieved in the high-voltage region of 0 ∼1.6 V, and a large energy density of 32.6 Wh/kg is delivered at power density of 420 W/kg. The findings demonstrate the important and great potential of developing metal phosphate based materials for supercapacitors.