Design, Synthesis, and Characterization of Carbon‐Supported β‐Ni(OH)₂ Nanosheets for Miniaturized Nickel–Metal Hydride Batteries

Abstract

Carbon‐supported β‐Ni(OH) 2 nanosheets are prepared for miniaturized nickel–metal hydride batteries. The nanomaterial consists of thin and unfolded nanosheets, which possess a hexagonal crystallographic structure. Its unique structure gives rise to a remarkable specific capability, with 81.5% of the nanomaterial being used in electrical energy storage. Repetitive charge–discharge cycling between charge and discharge cut‐off potentials ( E cut‐off,ch = 1.50 or 1.65 V and E cut‐off,dis = 1.20 V) in aqueous NaOH solution is performed to examine the nanomaterial's specific charge and stability. The results show that the specific capacity gradually decreases upon repetitive charge–discharge cycling but still maintains a significant percentage of its initial value, 54% for E cut‐off,ch = 1.50 V and 43% for E cut‐off,ch = 1.65 V. A transmission electron microscopy analysis of the nanomaterial after the charge–discharge cycling demonstrates that the β‐Ni(OH) 2 nanosheets are less‐organized and distorted. The structural and morphological changes give rise to new features in cyclic voltammetry profiles and charge–discharge curves, and a decrease in the specific capacity of the nanomaterial. The degradation of the specific capacity is attributed to a loss of the initial structure, a reduction of the number of anchoring sites, and weakening of the bond between the β‐Ni(OH) 2 nanosheets and the carbon support.