| Title |
Research Paper - Electrometallurgy - : A study on the self - discharge characteristics of sealed Ni - MH batteries with anode using Zr - based Laves phase alloys |
| Authors |
김광섭(Kwang Sup Kim); 이존하(Jon Ha Lee); 김동명(Dong Myung Kim); 이성만(Sung Man Lee); 이기영(Ki Young Lee); 이재영(Jai Young Lee) |
| Abstract |
The self-discharge characteristics of nickel-metal hydride (Ni-MH) batteries with anode using Zr_(0. 8)Ti_(0. 2)Cr_(0. 5)Mn_(0. 2)V_(0. 2)NiMm_(0. 05) and ZrV_(0. 8)Ni_(1. 6) alloys have been investigated in a sealed cell or in a modified sealed cell To separately measure the self-discharge characteristics of the anode and the cathode, a modified sealed cell was employed, in which two more electrodes (Pt, counterelectrode; Hg/HgO, reference electrode) were installed. After 7 days of open circuit storage using Zr_(0. 8)Ti_(0. 2)Cr_(0. 5)Mn_(0. 2)V_(0. 2)NiMm_(0. 05) alloy, the capacity loss was 38%, among which 16% of the capacity loss was irreversible. The irreversible capacity loss is attributed to the oxidation and dissolution reactions of hydriding forming elements of the MH electrode. The reversible self-discharge is due to the evolution of hydrogen from the MH electrode. In the case of ZrV_(0. 8)Ni_(1. 6) alloy, the charge retention for both electrodes was measured at latm and 30℃ in air and it was found that the capacity loss of the anode was greater than that of the cathode after open-circuit storage. From X-ray diffraction and thermal desorption spectroscopy. it was found that the self-discharge of the anode might occur by the evolution of hydrogen from the MH electrode due to the difference between the hydrogen partial pressure in the sealed cell and the equilibrium hydrogen pressure of the MH electrode. |