High-performance alkaline zinc‑manganese flow batteries enabled by an advanced sodium gluconate additive

Alkaline Zn Mn flow batteries (AZMFBs) have emerged as a promising candidate for large-scale energy storage due to their high theoretical energy density, environmental tolerance, and low cost. Nevertheless, the electrochemical stability and cycling performance of AZMFBs are substantially hindered by hydrogen evolution, irreversible zinc deposition, and zinc dendrite formation. This study presents sodium gluconate (SG), a biodegradable and water-soluble organic chelating agent, as an addition in the anolyte to modulate zinc electrodeposition behavior. The impact of SG on the electrochemical performance of the zinc anode is meticulously analyzed using cyclic voltammetry, Tafel analysis, chronoamperometry, and galvanostatic cycling. Results reveal that SG effectively coordinates with Zn 2+ ions, promoting uniform nucleation and suppressing dendritic growth. Furthermore, SG reduces side reactions by stabilizing the electrode-electrolyte interface, resulting in a coulombic efficiency (CE) of 95.6%, an energy efficiency (EE) of 81.4%, and a service life that is double that of pristine batteries. Examination of surface morphology and structure further confirmed that a thick, smooth Zn deposit formed in the presence of SG. This study provides insights into the role of green additives in regulating Zn anodes for Zn-based flow battery systems and offers guidance for the further development of sustainable alkaline Zn-based energy-storage technologies.