High-temperature electrochemical performance of Al-α-nickel hydroxides modified by metallic cobalt or Y(OH)3

Al-α-Ni(OH)2 microspheres are modified with metallic Co and Y(OH)3, respectively, in order to improve the high-temperature electrochemical performance. The microstructure, morphology, and surface chemical state of the as-prepared and the modified Al-α-Ni(OH)2 microspheres are investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS), respectively. Metallic cobalt nanoparticles are distributed on the nanosheets of the microsphere edges. The existence of metallic Co and Y(OH)3 can be further verified from ICP and XPS results. The effect of metallic Co or Y(OH)3 on high-temperature performance of the Al-α-Ni(OH)2 microspheres is measured by galvanostatic charge–discharge experiments and cyclic voltammetric (CV) measurements. The discharge capacities of the Al-α-Ni(OH)2 microspheres, with optimized 5 wt% Co and 1 wt% Y(OH)3, are 283.5 mAh g−1 and 315 mAh g−1, respectively, much higher than that of the as-prepared Al-α-Ni(OH)2 (226.8 mAh g−1) at 0.2 C and 60 °C. Furthermore, the high-rate discharge capability at high temperature can be also improved for both the modified samples.