摘要
Aqueous Zn-ion batteries(AZIBs)are one of the promising battery technologies for the green energy storage and electric vehicles.As one attractive cathode material for AZIBs,α-MnO2 materials exhibit superior electrochemical properties.However,their long-term reversibility is still in great suspense.Considering the decisive effect of the structure and morphology on theα-MnO2 materials,hierarchicalα-MnO2 materials would be promising to improve the cycle performance of AZIB.Here,we synthesized theα-MnO2 urchin-like microspheres(AUM)via a self-assembled method.The porous microspheres composed of one-dimensionalα-MnO2 nanofibers with high crystallinity,which improved the surface area and active sites for Zn2+intercalation.The AUM-based AZIB realized a high initial capacity of 308.0 mA hg-1,and the highest energy density was 396.7 W hkg-1.The kinetics investigation confirmed the high capacitive contribution and fast ion diffusion of the AUM.Ex-situ XRD measurement further verified the synergistic insertion/extraction of H+and Zn2+ions during the charge/discharge process.The superiority of the AUM guaranteed good electrochemical performance and reversible phase evolution,and this application would promote the follow-up research on the advanced AZIB.
在绿色能源存储和电动汽车领域,水系锌离子电池(AZIB)是一种十分有潜力的电池技术.α-MnO2作为AZIB的一种热点正极材料,表现出十分优异的电化学性能.但是,α-MnO2正极的长期稳定性问题仍待解决.α-MnO2材料的结构和形貌会对其性能产生决定性的影响,因此构建多级结构的α-MnO2材料是一种提升AZIB循环充放电性能的可行方法.本文中,我们采用自组装法合成了一种α-MnO2海胆状微米球(AUM).这种微米球是由高度结晶的一维α-MnO2纳米线构建而成,这种疏松多孔的结构将有助于提升材料的比表面积和Zn2+离子嵌入的活性位点.基于AUM的AZIB器件实现了高达308.0 m A h g-1的初始容量,其最大能量密度可达396.7 W h kg-1.动力学分析表明,AUM正极具备较高比例的电容型容量贡献及快速离子扩散系数.非原位XRD测试进一步证实,在充放电过程中,存在H+和Zn2+离子的协同嵌入/脱嵌现象.AUM的这种优异特性,使器件实现了很好的电化学性能和循环可逆的结构相变,本工作将有助于高性能AZIB的进一步深入研究.
基金
supported by the National Key Research and Development Program of China(2016YFA0202400)
the 111 Project(B16016)
the National Natural Science Foundation of China(51702096,U1705256 and 51572080)
the Fundamental Research Funds for the Central Universities(2018ZD07 and JB2019132)。
作者简介
Corresponding authors:丁勇,email:dingy@ncepu.edu.cn,received his PhD from Hefei Institutes of Physical Science,Chinese Academy of Sciences(CAS)in 2016.After graduation,he became a lecturer in NCEPU.His research interest focuses on the 2D perovskite-based photoelectric devices,including perovskite solar cells and light-emitting diodes;Corresponding authors:戴松元,email:sydai@ncepu.edu.cn,is a professor of the School of Renewable Energy,NCEPU.He obtained his BSc degree in physics from Anhui Normal University in 1987,and MSc and PhD degrees in plasma physics from the Institute of Plasma Physics,CAS in 1991 and 2001,respectively.His research interests mainly focus on the synthesis and application of functional materials and nanomaterials,and the next-generation solar cells including dye sensitized solar cells,quantum dot solar cells and perovskite solar cells.自;吴云召,obtained his BSc degree from the North China Electric Power University(NCEPU)in 2015.Now he is a PhD candidate in NCEPU under the supervision of Prof.Songyuan Dai.His research interests mainly focus on the advanced electrode materials and charge storage mechanism for ZIBs and supercapacitors.
