Cumulative Charge as a Workload-Aware Comparison Coordinate for Pulsed High-Current OER Stability
Year: 2026
Type: preprint
Abstract: The interpretation of electrode degradation under dynamic electrolysis is complicated by the fact that degradation rates expressed per unit time depend not only on the degradation response but also on the electrochemical workload imposed during the test. Here, we investigate this effect for porous NiFe OER electrodes operated in an alkaline gas-diffusion-electrode half-cell configuration under pulsed galvanostatic operation at 1-3 A·cm-2. Two pulse protocols, corresponding to 86% and 96% active operation time, were evaluated using 36 electrode tests from two independent deposition batches. Degradation was quantified both per unit elapsed time and per cumulative areal charge using iR-corrected electrode potentials, sample-level regression, random-effects pooling, and batch-aware statistical analysis. In the time domain, the degradation rate increased substantially with current density, from 19.2 ± 4.7 to 53.4 ± 23.6 mV·h-1 for the 86% active-operation protocol. In contrast, the charge-normalized voltage loss remained approximately constant at 5.6-6.2 mV·(kC·cm-2)-1 over 1-3 A·cm-2 for the same protocol. The 96% protocol showed a similar overall reduction in apparent current-density dependence after charge normalization, although the 2 A·cm-2 condition exhibited a distinct deviation. Furthermore, at 3 A·cm-2, increased non-linearity, signal variability, and post-electrolysis structural damage indicated a transition to a failure-prone operating regime in which linear charge-normalized degradation was no longer sufficient to describe electrode behavior. Our results demonstrate that elapsed-time degradation rates can overstate apparent current-density and duty-cycle effects during pulsed high-current electrolysis. The charge-normalized voltage loss therefore provides a useful workload-aware descriptor for comparing degradation within the stable operating regime, while high-current failure processes require separate consideration.
Source: ChemRxiv
Institutions: University of Bern, University of Nevada, Reno
Language: English
Field: Energy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7213446062