Recent Advances on Challenges and Strategies of Manganese Dioxide Cathodes for Aqueous Zinc‐Ion Batteries

Abstract

Aqueous zinc‐ion batteries (AZIBs) are regarded as promising electrochemical energy storage devices owing to its low cost, intrinsic safety, abundant zinc reserves, and ideal specific capacity. Compared with other cathode materials, manganese dioxide with high voltage, environmental protection, and high theoretical specific capacity receives considerable attention. However, the problems of structural instability, manganese dissolution, and poor electrical conductivity make the exploration of high‐performance manganese dioxide still a great challenge and impede its practical applications. Besides, zinc storage mechanisms involved are complex and somewhat controversial. To address these issues, tremendous efforts, such as surface engineering, heteroatoms doping, defect engineering, electrolyte modification, and some advanced characterization technologies, have been devoted to improving its electrochemical performance and illustrating zinc storage mechanism. In this review, we particularly focus on the classification of manganese dioxide based on crystal structures, zinc ions storage mechanisms, the existing challenges, and corresponding optimization strategies as well as structure–performance relationship. In the final section, the application perspectives of manganese oxide cathode materials in AZIBs are prospected.

Oxygen Vacancies Boosted Proton Intercalation Kinetics for Aqueous Aluminum–Manganese Batteries

“…The reaction mechanism of the Al//O v -MnO 2 battery is shown in Figure S11. The H + and Al 3+ co-insertion mechanism is similar to that of the manganese dioxide cathode in ZIBs . Due to the small particle size, the reaction kinetics of H + is faster than that of Al 3+ , which leads to the first discharge plateau with reaction products MnOOH.…”

“…The H + and Al 3+ co-insertion mechanism is similar to that of the manganese dioxide cathode in ZIBs. 45 Due to the small particle size, the reaction kinetics of H + is faster than that of Al 3+ , which leads to the first discharge plateau with reaction products MnOOH. In the subsequent reaction, MnOOH dissolved into Mn 3+ and was further reduced to Mn 2+ , while Al 3+ inserted into the second plateau to form Al x MnO 2 .…”

Cation-Vacancy Modulated 2D Manganese Oxide Nanobelts for High-Performance Aqueous Zinc-Ion Storage

“…To date, various types of cathodes have been attempted, including vanadium-based materials, manganese-based materials, metal chalcogenides, and organic molecules. , Among these, manganese-based oxide materials are the most promising candidates for practical applications due to their wide range of polymorphs, high voltage, and ease of fabrication. However, the poor conductivity, sluggish ion transport kinetics, inferior structural stability, and intense electrostatic interactions still make the development of high-performance manganese-based cathodes a great challenge for the ZIBs, severely hindering their practical applications. − …”

Bi‐MOF Modulating MnO2 Deposition Enables Ultra‐Stable Cathode‐Free Aqueous Zinc‐Ion Batteries

“…Aqueous zinc ion batteries (ZIBs) show potential application in grid energy storage thanks to their high energy density using a Zn anode, which has a high theoretical gravimetric/volumetric capacity (820 mAh g −1 and 5851 mAh mL −1 ) and suitable redox potential (−0.76 V versus SHE), as well high safety and low cost. [1][2][3][4][5] To date, a few materials, such as manganese oxides, V-based, Prussian blue analogues (PBAs) have been used as the cathode for Zn-ion batteries due to their high charge density and high hydrated ionic radius of Zn 2+ . Among them, MnO 2 is particularly appealing due to its high energy density, earth-abundance, environmental benignity, and low-cost.…”