Factors affecting voltammetric responses for redox-active solid layers of Li4Ti5O12 coated on electrodes

Abstract

Instead of W. R. McKinnon1) theory based on interaction energy in lattice-gas model, which has been used widely to analyze the charge-discharge curve for electrode materials of lithium ion battery, Laviron's7) and Matsuda's8) theoretical treatments about the cyclic voltammetry (CV) for the electro-active molecular confined on an electrode are applied for clarifying the experimentally accessible physical quantities, i.e. the parameters of electrostatic interaction between redox sites and of electrode kinetics for the Li4Ti5O12 (LTO) solid-state layers. From the width at half height (ΔE9 1/2) of the reversible CV at slowest potential scan-rate, the corresponding attractive force in their active-materials was evaluated as W/RT = 1.64 (4.07 kJ mol -1), being an identical factor for the interaction energy evaluated by the lattice-gas model From the shift of peak potential and the changes of ΔEp 1/2 and peak current for the irreversible CVs against the moderate potential scan-rates, the values of the rate constant (k°s -1) and the transfer coefficients (α) regarding a redox-electrode reaction process were evaluated as 6.7 × 10-3 and 0.47-0.48, respectively. The interaction parameter ΔW‡/RT being related to the kinetics of the electrode process was evaluated as -4.28-4.68.