Abstract: The poor high-temperature performance of the spherical nickel hydroxide becomes the main reason for limitation of use as the positive electrode active material in MH-Ni
battery, especially for the vehicle power. In the present work, different amount of ytterbium hydroxide layers were coated on the surface of the
spherical nickel hydroxide by means of the controlled crystallization. The charge and discharge capacities were studied at room and high temperatures.
The discharge capacity of the ytterbium-coated nickel hydroxide at room temperature was lower than that of the pure nickel hydroxide; however, its
high-temperature performance was much higher than that of the pure spherical nickel hydroxide. The sample coated with 2% ytterbium
hydroxide shows the best performance at 60℃ (1C), its capacity retention can be retained about 92%.

Key words: spherical nickel hydroxide, high-temperature performance, surface coating, ytterbium hydroxide