Zn/MnO₂ Battery Chemistry With H⁺ and Zn²⁺ Coinsertion

Abstract

Rechargeable aqueous Zn/MnO battery chemistry in a neutral or mildly acidic electrolyte has attracted extensive attention recently because all the components (anode, cathode, and electrolyte) in a Zn/MnO battery are safe, abundant, and sustainable. However, the reaction mechanism of the MnO cathode remains a topic of discussion. Herein, we design a highly reversible aqueous Zn/MnO battery where the binder-free MnO cathode was fabricated by in situ electrodeposition of MnO on carbon fiber paper in mild acidic ZnSO+MnSO electrolyte. Electrochemical and structural analysis identify that the MnO cathode experience a consequent H and Zn insertion/extraction process with high reversibility and cycling stability. To our best knowledge, it is the first report on rechargeable aqueous batteries with a consequent ion-insertion reaction mechanism.

Toward Tailorable Zn‐Ion Textile Batteries with High Energy Density and Ultrafast Capability: Building High‐Performance Textile Electrode in 3D Hierarchical Branched Design

“…They correspond well to the two potential plateaus in the charge/discharge curves (Figure e). The results certify the multiple ion intercalation of the MnO 2 composite, which is composed of the initially H + ion and the followed Zn 2+ ion . For both kinds of the cathodes, the self‐branched structured samples achieve the largest current density and the smallest potential difference between the redox peaks (Figure i,m).…”

Unravelling H+/Zn2+ Synergistic Intercalation in a Novel Phase of Manganese Oxide for High‐Performance Aqueous Rechargeable Battery

“…Moreover, its practical use is restricted by the low loading of active material. Meanwhile, compared with Zn 2+ , the monovalent H + with smaller ion radius shows high ion diffusion kinetics, and thus the utilization of H + insertion is vital to improve the rate performance of Zn‐MnO 2 battery . By tuning nanostructure of MnO 2 cathode, H + and Zn 2+ synergistic intercalation mechanism can be obtained, which is the key to improve the electrochemical performance of Zn‐MnO 2 battery, including capacity, cycling stability, and rate capability.…”

Challenges and perspectives for manganese‐based oxides for advanced aqueous zinc‐ion batteries

“…Akhtenskite‐structure MnO 2 (ε‐MnO 2 ) is a metastable phase composed of face‐shared [MnO 6 ] and [YO 6 ] octahedral (Y means vacancy), where Mn 4+ cations randomly occupy 50% of the octahedral positions of the hexagonal‐close‐packed (hcp) oxygen sublattice . Wang et al prepared the composite electrode of ε‐MnO 2 nanoflakes and carbon fiber paper by in situ electrodeposition. And the discharge capacity of the composite electrode is 290 mAh/g (Figure C).…”

“…Reproduced with permission from Ref. , Copyright 2017, ACS Publications. D, Schematic of galvanostatic discharge, including D1, D2, and D3 steps.…”

“…Different from CNTs and graphene, the 3D substrates (such as carbon fiber paper and SSWM) not only can improve the conductivity of the electrode, but also offer the support for the active material to form a stable porous structure . Recently, a MnO 2 @CFP cathode was constructed by electrodeposition, which can cycle 1000 time at a high rate of 6.5 C with a low capacity decay rate of 0.007% per cycle for 10 000 cycles . Moreover, Liang et al reported a SSWM@Mn 3 O 4 composite.…”