Oxygen Evolution and Recombination Kinetics Inside Sealed Rechargeable, Ni-Based Batteries

Abstract

The oxygen evolution and recombination kinetics in Ni-based battery systems have been investigated under temperaturecontrolled, steady-state, overcharging conditions within a temperature range of 0-60°C. Theoretical relationships for both reactions have been derived. The mathematical relationships have been confirmed by experiments on sealed rechargeable NiCd batteries. Under steady-state overcharging conditions, the Cd electrode potential was proven to be constant, thereby significantly reducing the complexity of the interpretation of the results. The oxygen evolution reaction was found to be a two-step process at the Ni electrode: two linear Tafel dependencies were found at low and high currents, separated by a transition region at intermediate currents. The oxygen recombination kinetics was found to be first-order in partial oxygen pressure, strongly suggesting that the recombination reaction is purely diffusion-controlled by oxygen, redissolved into the electrolyte, to the Cd electrode surface. For all reactions, activation energies have been determined. The results can directly be applied to aqueous battery models and give more insight into both the overcharging and self-discharge processes occurring in these Ni-based systems.

Battery open-circuit voltage estimation by a method of statistical analysis

“…There are clearly two different slopes in the dependence of α k,1 on I k for low and high values of I k , respectively. The presence of two different slopes is related to the fact that the reaction mechanism of oxygen evolution has two rate-determining steps, see Notten et al [6].…”

“…Therefore we apply a linear regression model for the KL coefficients using only low currents 0.011-0.11A, i.e., the first 5 points in Figure 3. If one is interested in voltage curves corresponding to moderate currents (0.1-0.5A), kinetic equations derived in Notten et al [6] provide a model for interpolation.…”

The Hydrogen Evolution and Oxidation Kinetics during Overdischarging of Sealed Nickel-Metal Hydride Batteries

“…17, one can see that steady-state overdischarging experimental conditions yields valuable and simultaneous information on both the her and hor kinetics. The steady state method was also successfully used by Notten et al 42 to study the oxygen evolution recombination cycle for the NiCd battery. Due to its simplicity it is a very elegant method to study both reactions mechanisms simultaneously.…”

“…First, a change of the rds in a mechanism composed of successive reactions. 37,42 Erdey-Gruz et al showed that a change of the rds in a sequence of consecutive steps will change the slope of the polarization curve differently than for a change of the rds in a sequence of parallel steps. 8 Second, it was shown that one rds could have two Tafel regions with extreme surface coverage of adsorbed atoms ͑when → 0 and → 1͒ as was demonstrated for the case of the Heyrovsky step.…”

The oxygen evolution kinetics in sealed rechargeable NiMH batteries

“…The oer and the oxygen recombination reaction in NiMH are very similar to those of the NiCd system for which the kinetics have recently been studied. Notten and co-workers investigated the kinetics during steady-state overcharging conditions [66] without clarifying, however, the oer mechanism. This contribution gives more insight into the kinetics and mechanism of the oer, occurring inside commercial NiMH batteries under partial charging conditions, by measuring the individual electrode potentials as a function of current.…”