Electrochemical quartz crystal microbalance gravimetric and viscoelastic studies of nickel hydroxide battery electrodes

The measurement of theological properties of electrodeposited NiOOH films s imultaneous to cyclic voltammetry using an electrochemical quartz crystal m icrobalance and fast quartz crystal impedance at 10 MHz for thin and thick films are reported. The resulting impedance parameters are analyzed using t he model proposed by Martin and Granstaff for multiple viscoelastic layers on a piezoelectric resonator. Nickel battery oxide films show an inversion in mass-to-charge relation as shown previously by Scherson and Hillman in t he first reduction-oxidation cycles but without appreciable change in their viscoelastic behavior. Changes in the motional resistance are not recovere d in the first cycle during "break in." After hundreds of cycles, NiOOH fil ms undertake an important viscoelastic change, and the aged films become so fter. The oxidized state shows always higher sheer modulus than the reduced state. (C) 2001 The Electrochemical Society. All rights reserved.