Impact of Acetate Additive on PbO2 Plating and Oxygen Evolution in Soluble lead flow Batteries
Soluble lead flow batteries (SLFBs), a potential form of large-scale energy storage, are currently facing the challenge of short cycle life.
We aim to elucidate the effect of acetate additive on SLFBs. We find that the mechanical strength of the PbO2 layer plated by acetate-assisted electrolyte is materially enhanced. These further discoveries are of critical value for further extending cycle life and enabling SLFB technology.
Through electron backscattering diffraction, certain preferred orientations of deposited PbO2 are observed when plated without acetate additive, while random orientations are better preserved when plated with acetate additive. Via Brunauer−Emmett−Teller measurements, we find that porosity and surface area are both comparatively smaller in the acetate-assisted PbO2 deposits, while the rate of oxygen evolution reaction (OER) is shown to be drastically reduced on PbO2 plated with NaOAc-assisted electrolyte. We further propose that the OER pathway is suppressed by the additive due to acetate-ion adsorption at superficial PbO2 sites, and in turn facilitates PbO2 plating.
Through electron back-scattering diffraction, certain preferred orientations of deposited PbO2are observed when plated without acetate additive, while random orientations are better preserved when plated with acetate additive. Acetate-based additives help to reduce large defects and preserve smaller grain formation during PbO2deposition process, and in turn, oxygen evolution is suppressed and coulombic efficiency (CE) of SLFBs over long-term cycling is improved.
Cross-sectional electrodeposits
The SEM images of cross-sectional electrodeposits formed from NaOAc-free and NaOAc-added electrolyte suggest that smaller grain sizes of PbO2 were plated from NaOAc-added electrolyte. Similar grain size reduction effects are found for the PbO2 surface plated with KOAc-added and Ca(OAc)2-added electrolyte,
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Published on : ACS Applied Energy Materials