X‐ray Fluorescence and SEM Analysis of Cycled NiOOH Electrodes

Abstract

Zinc negative electrodes often contain other metal compounds to minimize shape change during cycling. After cycling in a cell, these materials can be found in the positive nickel hydroxide electrode. Two complementary analytical techniques were used to characterize the distribution and amount of Co, Zn, Ca, and Pb present as components of various compounds in the nickel oxide electrode after cycling. Radioisotope‐induced x‐ray fluorescence was used to quantify the amounts of the elements at various locations across the electrode face, and scanning electron microscopy was used to determine concentration profiles of Zn within the electrode. Selected area analysis showed that the amount of Zn was lowest in areas of the positive electrode which were opposite sections of the zinc negative electrode that experienced the greatest loss of zinc material: the edges. Large amounts of Pb material were found in the positive electrode when that electrode remained on open‐circuit stand after cycling.