Synthesis and electrochemical properties of Mn-substituted high-capacity nickel hydroxide

Abstract

Nickel hydroxide is widely used as cathode materials in nickel-metal secondary batteries. In this work, Mn-substituted nickel hydroxide samples with a special α/β mixed phase structure were synthesized by chemical co-precipitation method. The physical properties were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and field emission scanning electron microscopy (FE-SEM). The results show that the structure of the samples and the amount of intercalated anions and water molecules are highly related to the content of the Mn substituted. Their electrochemical performances were characterized by charge/discharge tests and electrochemical cycle tests. The results demonstrate that the Mn-substituted samples with a α/β mixed phase structure perform a much higher discharge capacity than normal β-nickel hydroxide. The specific discharge capacity reaches 330 mAh·g−1 after 50 cycles of charge/discharge in charging rate of 0.2C under ambient temperature. Meanwhile, the samples show no capacity loss in electrochemical cycles, which indicates that the mixed phase nickel hydroxide maintains high structure stability.