Layered manganese dioxide nanoflowers with Cu2+and Bi3+ intercalation as high-performance cathode for aqueous zinc-ion battery

For aqueous zinc ion batteries (AZIBs), birnessite MnO2 (delta-MnO2) has been intensively used as one of the most potential cathode materials due to its layered structure, which is conducive to reversible insertion/ extraction of zinc ions. However, delta-MnO2 has not been attained for zinc ion storage performance because of its inferior conductivity as well as the undesirable structural degradation upon charge/discharge cycling. Herein, we have designed two kinds of cathode materials of Cu0.06MnO2.1.7H(2)O (CuMO) and Bi0.09MnO2.1.5H(2)O (BiMO) with nanoflower structure for the first time by a facile one-step hydrothermal method, which will be applied for high-performance AZIBs.The pre-intercalated metal ions and water molecules serve as pillars to sustain the layered structures, improving the stability of these materials. Particularly, the CuMO may experience a replacement reaction except the zinc ion insertion/extraction to form metallic Cu during the cycling process, which can enhance the diffusion rate of Zn2+, thus resulting in an excellent electronic conductivity and exhibiting remarkable specific capacities. Furthermore, a pseudo-capacitance that is derived from the surface-adsorbed Cu(2+)and Bi3+ also contributes to the improved electrochemical performances. The reversible capacity of CuMO is estimated as 350 mAh g(-1) at 0.5 A g(-1), which is much higher than that of pure delta-MnO2 (190 mAh g(-1) at 0.5 A g(-1)). However, BiMO demonstrates long-term cycling stability, maintaining a capacity of 114.5 mAh g(-1) even after 1100 charged-discharged cycles at 1 A g(-1). The capacity retention is found to be as high as 98.6%, which is much higher than that of pure delta-MnO2 (53.8%). This can contribute to the development of high-performance AZIBs and the application of metal ion pre-intercalation methods in other areas. (c) 2022 Elsevier Inc. All rights reserved.

Automated summary

In this study, two cathode materials with nanoflower structures, Cu0.06MnO2·1.7H2O (CuMO) and Bi0.09MnO2·1.5H2O (BiMO), have been successfully designed for high-performance AZIBs. The layered structures of these materials are sustained by pre-intercalated metal ions and water molecules, improving their stability. CuMO exhibits excellent electronic conductivity and remarkable specific capacities, while BiMO demonstrates long-term cycling stability.