Exploiting the Dual Coordination and pH‐Buffering Effects of a Polyprotic Chelate Additive for High‐Performance Aqueous Zinc‐Manganese Batteries

ABSTRACT Aqueous zinc‐manganese batteries represent promising candidates for large‐scale energy storage owing to their intrinsic safety and cost‐effectiveness. However, their practical deployment remains fundamentally constrained by proton‐coupled manganese dissolution chemistry, which triggers severe pH fluctuation and irreversible Mn 3+ disproportionation at the cathode‐electrolyte interface. Herein, we introduce a proton‐coupled coordination chemistry strategy that employs trisodium nitrilotriacetate (NTA‐3Na) as a dual‐functional electrolyte additive. This additive synergistically modulates interfacial pH dynamics and stabilizes reactive Mn 3+ intermediates. Mechanistically, the polyprotic carboxylate framework of NTA‐3Na establishes dynamic acid–base equilibria (NTA 3− /HNTA 2− /H 2 NTA − /H 3 NTA) that constrain electrolyte pH fluctuations from conventional 2.6–5.5 to a stabilized 2.7–4.6 range, effectively suppressing zinc hydroxysulfate (ZHS) parasitic precipitation. Concurrently, density functional theory calculations reveal that NTA 3− exhibits preferential binding affinity toward Mn 3+ over Mn 2+ , Zn 2+ , and H + , enabling in situ construction of a manganese‐rich cathode‐electrolyte interphase (CEI) that kinetically inhibits Mn 3+ disproportionation. The resulting Zn//MnO 2 batteries demonstrate exceptional rate capability (212.6 mAh g −1 at 2 A g −1 ) and superior cycling stability (150.5 mAh g −1 retained after 900 cycles at 1 A g −1 ). This work establishes proton‐coupled coordination chemistry as a versatile paradigm for simultaneously addressing pH instability and transition metal dissolution in aqueous battery systems.