Synergistic electrode/electrolyte optimization enables efficient dissolution-deposition chemistry in Zn-MnO2 batteries

Abstract

Electrolytic Zn-MnO2 batteries based on the MnO2/Mn2+ dissolution/deposition reaction have attracted considerable interest due to their high redox potential and exceptionally high theoretical capacity. However, such systems typically require an acidic environment to initiate the one‑step MnO2/Mn2+ conversion. Herein, high-performance cathode-less Zn-MnO2 batteries are designed. Benefiting from its high surface area and manganese affinity, the aminated Prussian blue analogues (MF@NC‑HA) seed layer provides extra active sites, inducing uniform MnO2 deposition and improving its charge structure. Meanwhile, amino‑acid additives with chelating ability toward Mn2+/Zn2+ are introduced to optimize the cationic solvation structure. Asp lowers the Gibbs free energy of the MnO2 dissolution reaction, thereby enhancing reaction efficiency. The MnO2@HA‑Asp delivers a high areal capacity of 0.53 mAh cm−2 after cycling at 0.5 mA cm−2 and maintains nearly 100% CE over 300 stable cycles at 1.0 mA cm−2. Importantly, Asp can preferentially adsorb on the Zn (002) plane, guiding uniform Zn2+ horizontal deposition and effectively suppressing dendrite growth. Ultimately, the Zn//MnO2@HA‑Asp pouch cell exhibits a high discharge plateau of ∼1.5 V and a capacity of 11.7 mAh. This work provides an efficient strategy for realizing the two‑electron transfer process of Zn-Mn systems.