Interconnected Vertical δ-MnO₂ Nanoflakes Coated by a Dopamine-Derived Carbon Thin Shell as a High-Performance Self-Supporting Cathode for Aqueous Zinc Ion Batteries

Abstract

Aqueous zinc (Zn)-ion batteries (AZIBs) are one of the most promising secondary battery technologies for electricity storage with high performance-to-cost ratios. Herein, a highly reversible AZIB using interconnected vertical δ-MnO2 nanoflakes coated by a dopamine-derived carbon thin shell of ∼2 nm in thickness on carbon cloth as a self-supporting cathode is reported. The vertical nanoflake structure ensures the effective contact with electrolyte, large specific surface area and efficient stress relief during charge and discharge processes, and the coated thin carbon shell increases the electrical conductivity of the cathode and meanwhile relieves the dissolution of the electrode material during cycle. Thanks to these advantages, a high capacity of ∼346.7 mA h g–1 at 0.5 A g–1 and good long-term cycling stability with 96.8% capacity retention after 2000 cycles at 6.0 A g–1 can be delivered. Furthermore, the electricity storage mechanism is investigated using various characterization tools. Benefiting from the facile preparation and high performance, this study is believed to provide a valuable exploration of high-performance self-supporting cathodes for aqueous Zn-ion batteries.

Reaction mechanisms for electrolytic manganese dioxide in rechargeable aqueous zinc-ion batteries

“…Several studies have increased the charging potential to 1.9 V 20,38,39 and even to 2 V 18,40 ; however, this will result in the oxygen evolution reaction (OER) at the positive electrode. Therefore, galvanostatic charge-discharge (GCD) tests with the charging potential limited to 1.8 V, followed by a constant voltage period, can alleviate the OER issue.…”

Flexible Free-Standing Electrode of Nickel–Manganese Oxide with a Cracked-Bark Shape Composited with Aggregated Nanoparticles on Carbon Cloth for High-Performance Aqueous Asymmetric Supercapacitors

“…However, LIBs have some disadvantages in practical application including high price, low power density, unsatisfactory service lifetime, harsh production condition, sensitivity to the ambient temperature, and safety issue . Compared with LIBs, SCs have a higher power density (about 10–10 3 times higher than LIBs), more excellent cycling and rate performance, and low cost, and research on SCs has gained considerable consideration accordingly. , Moreover, especially for the SCs based on aqueous electrolytes, the benefits such as eco-friendliness, the higher-level safety, and more evident cost advantage further motivate study activities. However, the need to address the low energy density ( E ) is a research priority before the practical application of SCs. − …”

Poly(3,4-ethylenedioxythiophene)–Polystyrenesulfonate-Added Layered Vanadium Oxide Cathode for High-Performance Zinc-Ion Batteries

“…Since the electrochemical performance of the AZIBs principally relies on the cathodes, many active materials including manganese oxides, vanadium oxides, − polyanionic compounds, , and Prussian blue analogues (PBAs) , have been widely studied. Therefore, vanadium oxides are a promising candidate due to their high capacity of ∼400 mAh g –1 , originating from the multivalence of vanadium (+3 to +5), and to the controllable layered structure beneficial for Zn 2+ intercalation/deintercalation. − In addition, the abundant reserve in the earth crust also endows vanadium oxides with the application superiority for AZIBs.…”

“…5−10 Among these schemes, aqueous zinc-ion batteries (AZIBs) have emerged as a promising alternative to LIBs because of the high theoretical capacity (820 mAh g −1 ), low cost, high safety, low redox potential of the Zn electrode (−0.76 V versus the standard hydrogen electrode), and environmental benignity. 11 Since the electrochemical performance of the AZIBs principally relies on the cathodes, many active materials including manganese oxides, 12 vanadium oxides, 13−16 polyanionic compounds, 17,18 and Prussian blue analogues (PBAs) 19,20 have been widely studied. Therefore, vanadium oxides are a promising candidate due to their high capacity of ∼400 mAh g −1 , originating from the multivalence of vanadium (+3 to +5), and to the controllable layered structure beneficial for Zn 2+ intercalation/deintercalation.…”