The effects of carbon nanotubes on the hydrogen storage performance of the alloy electrode for high-power Ni–MH batteries

Abstract

The multi-walled carbon nanotubes (MWNTs) were added to the nickel hydrogen battery negative electrode to prepare high-power CNTs compound nickel hydrogen battery. Their capacity, large-current discharging performance of high-power battery and the cycle life were investigated. It's found that adding carbon nanotubes was greatly advantageous for enhancing the electrochemical performance of the battery as a whole, especially the large-current discharge performance and cycle life. When the weight ratio of the MWNTs in the compound electrode was 0.8%, the overall performance of the battery was the best, which has a highest capacity of 3369 mAh under the condition of 3000 mA charge current and 6000 mA discharge current (2C-rate discharge), and the cycle life surpassed 600 times (97% discharge depth). Especially under the 10C-rate large-current discharge condition (3000 mA charge current and 30000 mA discharge current), its cycle life still surpassed 100 times (75% discharge depth). In 600th cycle, the inner electric resistance of battery without MWNTs is 5 times more than adding 8% MWNTs. The adding of MWNTs can prevent inner resistance from rising, and therefore improve the cycle life of the Ni–MH batteries.