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In recent years, lithium‐ion batteries (LIBs) are used in a range of energy storage applications, such as mobile phones, electronic devices, and automobiles. Some recent research on LIBs has looked at replacing carbonaceous anode materials with transition metal oxides due to their high theoretical capacity, ranging from 500 to 1000 mAh g−1. In particular, NiO is considered as one of the most promising options due to its high theoretical capacity (718 mAh g−1). Herein, a porous NiO/Ni anode is fabricated via freezing/drying followed by thermal oxidation. The fabricated porous NiO/Ni anode is then characterized using X‐ray diffraction scanning electron microscopy, and energy‐dispersive X‐ray spectroscopy. The cycling performance of the freeze‐cast NiO/Ni anode is evaluated using a half‐coin cell test, and it demonstrates superior electrochemical performance and good cycling stability during the charging/discharging process. The freeze‐cast NiO/Ni anode also exhibits a higher rate performance when compared with that of commercial Ni foam and a conventional graphite anode. It is revealed that the initial crystalline surface oxide layer is amorphized, and the lattice defect density increases in the Ni struts during the lithiation process. However, these microstructure changes did not influence considerably the good electrochemical performance of the material. [ABSTRACT FROM AUTHOR]

Metallic foams show great potential as functional materials, due to their large surface area, low density, good gas permeability, and high strength-to-weight ratio. Owing to the inherent properties of Ni, including relatively high electrical conductivity, catalytic activity, and corrosion resistance, Ni foams are excellent candidate materials in energy applications such as electrodes for batteries and dye-sensitized solar cells, as well as current collectors in solid oxide fuel cells. In this study, we characterized Ni foams made by the freeze casting process using multi-scale morphological and structural characterization techniques, including X-ray computed tomography (XCT), scanning electron microscopy (SEM), and electron backscattered diffraction (EBSD) to study the structure of the Ni foams on the scale of several micrometers to a few millimeters. The multi-scale structural characterization results showed that the freeze casting method was successful in creating Ni foams with uniform directional pores, and the relative densities/solid area fraction and pore distribution of the Ni foams were uniform across different sample thicknesses, which can be fine-tuned by varying the concentration of NiO powder in the slurry during freeze casting. • Ni foam is successfully fabricated via freeze casting. • Ni foam is characterized via multi-scale morphological characterization techniques. • Effect of dispersant on the stability of the Ni slurry suspension is considerable. • Freeze-cast Ni foam shows relatively high twin boundaries fractions. [ABSTRACT FROM AUTHOR]

Porous metals have attracted great attention for their functional and structural applications; however, they often possess limited applicability in their pure form for the areas requiring decent strength and corrosion resistance. In this study, pure copper (Cu), pure nickel (Ni), and Cu–Ni alloy foams with five different compositions are successfully fabricated using freeze casting, resulting in open‐pore structures with varied porosity (from 55% to 75%). Their varied morphologies and crystal sizes are compared, and the lattice parameters and crystal sizes are calculated. The corrosion resistance of the synthesized Cu–Ni alloy foams is superior to those of the pure Cu and Ni foams. The weight loss rate of the Cu7Ni3 alloy foam is six times and five times slower than those of the pure Ni and pure Cu foams in a sulfuric corrosive environment, respectively. The yield strength of Cu7Ni3 alloy foam (53 ± 2% porosity) is 72 ± 2 MPa and its yield strength when normalized by the Gibson‐Ashby model is the largest with a value of up to 852 ± 3 MPa. The elastic modulus and hardness values are varied in the range of 73.4–152.4 GPa and 1.6–4.7 GPa, respectively, depending on the composition of the alloy foam. [ABSTRACT FROM AUTHOR]