Enhancing the High-Temperature and High-Rate Properties of Nickel Hydroxide Electrode for Nickel-Based Secondary Batteries by Using Nanoscale Ca(OH)2 and γ-CoOOH.

Nanoscale Ca(OH)₂ particles as a novel cathode additive for nickel-based secondary batteries are synthesized by a homogeneous precipitation method. The influence of Ca(OH)₂ additive on the electrochemical performance of two types of nickel electrode (using spherical Ni(OH)₂ and γ-CoOOH@Ni(OH)₂) were evaluated. It is interestingly discovered that nano-Ca(OH)₂ additives can efficiently improve the charge acceptance of both nickel electrodes. Especially, the charge acceptance of the 1.0 wt% nano- Ca(OH)₂@γ-CoOOH@Ni(OH)₂ electrode at 70°C at 5C is over 90% and the discharge capacity can reach about 218 mAh g^-1. These performance enhancements of nickel electrode mainly result from the combined coating with Ca(OH)₂ and γ-CoOOH. The modification of oxygen evolution reaction on the nickel electrode is primarily resulting from the use of Ca(OH)₂ by increasing its potential and suppressing its rate. The observably lower charge transfer resistance of nickel electrode is mainly due to the high conductivity coating of γ-CoOOH. Consequently, the proposed cathode additive is promising for the high-temperature property enhancement of nickel-based rechargeable batteries. [ABSTRACT FROM AUTHOR]