Tuning phase evolution of β-MnO2 during microwave hydrothermal synthesis for high-performance aqueous Zn ion battery. (October 2019)

• Record Type: Journal Article
• Authors: Liu, Mingqiang; Zhao, Qinghe; Liu, Hao; Yang, Jinglong; Chen, Xin; Yang, Luyi; Cui, Yanhui; Huang, Weiyuan; Zhao, Wenguang; Song, Aoye; Wang, Yuetao; Ding, Shouxiang; Song, Yongli; Qian, Guoyu; Chen, Haibiao; Pan, Feng
• Is Part Of: Nano energy. Volume 64(2019)
• Publication Date: 2019-10
• Subjects: Aqueous Zn battery -- β-MnO2 -- Phase evolution -- Electrochemistry; Nanoscience -- Periodicals; Nanotechnology -- Periodicals; Nanostructured materials -- Periodicals; Power resources -- Technological innovations -- Periodicals; Nanoscience; Nanostructured materials; Nanotechnology; Power resources -- Technological innovations; Periodicals; 621.042
• DOI: 10.1016/j.nanoen.2019.103942
• Languages: English
• ISSNs: 2211-2855

Abstract

Abstract: Mild aqueous Zn–MnO2 battery attracts lots of attention in energy storage filed due to its low cost, high safety and environmental friendliness. To achieve high-performance in battery, phase evolution processes of MnO2 during synthesis and electrochemical reactions need to be understood. Herein, the phase evolution during microwave hydrothermal and correlated battery performance of β-MnO2 are studied. The results demonstrate a phase evolution mechanism from an initial mixture of vernadite, nsutite, and pyrolusite (β-MnO2 ) to a final single β-MnO2 phase, along with enhanced structure stability, increased Mn valence, and decreased BET surface area. It is found that only when microwave hydrothermal time (MHT) ≥ 120 min, β-MnO2 showing both high capacity and excellent cycling performance can be obtained. β-MnO2 prepared under a MHT of 120 min shows a high reversible capacity of 288 mA h g −1 with a median voltage of 1.36 V vs. Zn/Zn 2+, and high capacity retentions of 91.8% after 200 cycles at 0.5C and 84.3% after 1000 cycles at 4C, respectively. In addition, the formation of inactive ZnMn2 O4 during cycling is observed, which contributes to the capacity fading of β-MnO2 after long-term cycling. This research makes a step forward to the practical application of Zn–MnO2 batteries, and contributes to the large-scale energy storage field. Graphical abstract: A comprehensive investigation on phase evolution during hydrothermal aging and eletrochemical process of β–MnO2 as cathode material in aqueous Zn–MnO2 battery.Image 1 Highlights: Phase transfromation of β-MnO2 during synthesis is demonstrated. Critical microwave hydrothermal time (MHT) of 120 min is needed to obtain a thermodynamically stable β-MnO2. β-MnO2 under MHT of 120 min shows both high capacity and superior cycling performance as cathode in Zn ion battery. Formation of inactive ZnMn2O4 is responsible for capacity fading of β-MnO2.