Electrochemical performance of sealed NiMH batteries using nanocrystalline TiNi-type hydride electrodes

Mechanical alloying (MA) process was used to synthesize nanocrystalline TiNi-type hydrogen storage materials. The electrochemical behavior of these compounds in conditions of their performance in sealed rechargeable nickel–metal hydride batteries are presented and compared with those of Ni–Cd battery. The cells were constructed by the pressing negative and positive electrodes, polyamide separator and KOH (ρ=1.20 g cm−3) as electrolyte solution. The effects of the chemical composition of the nanocrystalline TiNi-type alloy with alkaline solutions were investigated. It was found that the respective replacement of nickel in TiNi by Fe or by Zr improved not only the discharge capacity, but also the cycle life of these electrodes. The results show that the sealed battery using the nanocrystalline TiNi0.75Fe0.25 alloy has a capacity about two times that with of TiNi.