Dual metal ions and water molecular pre-intercalated d-MnO2 spherical microflowers for aqueous zinc ion batteries

Layered delta-MnO2 is a promising cathode material for aqueous zinc ion batteries (AZIBs) due to its high theoretical capacity, high operating voltage and low cost. However, the dissolution of MnO2 and the disproportionation of Mn3+ will lead to irreversible reaction and serious structural degradation of the material during cycling process. In this work, the Al3+ pre-intercalated K0.27MnO2 center dot 0.54H(2)O was prepared by a onestep hydrothermal method with citric acid as the complexing agent and weak reducing agent. Based on the pillars of bimetallic ions K+, Al3+ and water, the framework and interlayer of delta-MnO2 is stabilized. Besides, a certain amount of Al3+ facilitates the increase of crystal water compared with the pure K0.27MnO2 center dot 0.54H(2)O, which is not only conducive to promote the construction of porous and loose 3D morphology, but also beneficial to improve the stability of layered structure and accelerate the migration rate of zinc ions. Contributed to the dissolution/deposition reaction mechanism combined with H+/Zn2+ co-insertion/co-extraction mechanism, it has achieved the high capacity with the maximum reversible specific capacity of 269.5 mAh g(-1) at 0.5 A g(-1) and excellent stability with 205.8 mAh g(-1) even after 300 cycles in Zn//Al-KMO battery. (C) 2022 Elsevier Inc. All rights reserved.

Automated summary

In this study, layered delta-MnO2 with improved structural stability and enhanced ion migration rate was prepared by pre-intercalating Al3+. The material exhibited high reversible specific capacity and excellent stability in aqueous zinc ion batteries.