Titanium-doped α-Ni(OH)2 as a cathode material for high-performance nickel-metal hydride batteries

With high theoretical discharge specific capacity, excellent reversibility of electrochemical reaction, and suitable oxygen evolution overpotential, α -Ni(OH) 2 is an auspicious cathode material for alkaline batteries, which supports the development of high-capacity nickel-based batteries. Nevertheless, α -Ni(OH) 2 exhibits substandard structural stability and is susceptible to crystalline transformation, leading to capacity degradation, affecting the battery charge/discharge performance and cycle life. In this study, the TiO 2 -nickel hydroxide (TiO 2 - α -Ni(OH) 2 ) is prepared by high-energy ball milling. Among them, TiO 2 can be uniformly dispersed on the surface of α -Ni(OH) 2 , which can effectively prevent the collapse of the α -phase structure. Benefiting from the unique elemental doping technology, the TiO 2 - α -Ni(OH) 2 composites as a nickel-metal hydride (Ni-MH) battery cathode can release a reversible specific capacity of 390 mAh g −1 at a 2 C rate for 200 cycles. A reversible specific capacity of 210 mAh g −1 is still released after 200 cycles at a 5 C rate. Consequently, TiO 2 - α -Ni(OH) 2 is a promising candidate for high-power Ni-MH batteries.