2008 Volume 76 Issue 11 Pages 802-807
The detailed phase transformation in the charge-discharge process for the nickel hydroxide electrode have been examined by using the high-energy synchrotron X-ray absorption fine structure (XAFS) and X-ray diffraction (XRD). The structural refinement for the β-Ni(OH)2 and the β-NiOOH have been done successfully on the basis of two phase models of the ideal and fault phases. At 0% of SOC, it was found that the sample consisted of 80% of the ideal β-Ni(OH)2 phases and 20% of the fault ones. At 100% of SOC, the ideal and fault β-Ni(OH)2 phases were transformed to the ideal and fault β-NiOOH phases, respectively. It was found that the fault phases contained a larger amount of intercalated potassium ions and H2O (OH−) than the ideal ones. At 150% of SOC, the only ideal β-NiOOH phases was transformed to the ideal γ-NiOOH phases, accompanied by further intercalation of the potassium ions and H2O (OH−) into the interlayer
