用于可充电水性锌离子电池的Ti3C2@ε-MnO2电极

Advanced Ti3C2@ε-MnO2 cathode as rechargeable aqueous zinc-ion batteries

  • 摘要: 可充电水性锌-氧化锰(Zn-MnOx)电池具有成本低、安全性高、易于安装等特点,成为太阳能及风能储能装置的最佳选择。由于MnOx导电性欠佳,导致电池循环性能较差,为解决此问题,本文采用导电性优异、具有丰富化学终端(Tx,如=O、—F、—OH)的二维层状过渡金属碳化物(MXene) Ti3C2Tx材料作为MnOx颗粒的良好载体。基于化学终端的电负性,Mn2+能够与其产生强静电吸引,从而嵌入Ti3C2Tx MXene材料层间并吸附在其表面,使生成的Mn3O4颗粒牢牢地锚定在Ti3C2Tx MXene上,形成了Ti3C2@Mn3O4复合材料。当作为水性锌离子电池的正极材料时,Ti3C2@Mn3O4在第1次充电过程中,完全转化为Ti3C2@ε-MnO2。由于Ti3C2Tx MXene材料优异的导电性及层状结构,使Ti3C2@ε-MnO2电极展现出了优异的动力学和电化学性能,在0.2 C (1 C=308 mA·h·g−1)倍率下放电时,比容量高达440 mA·h·g−1,能量密度为607 W·h·kg−1,在1 C倍率下循环150次后,容量从270 mA·h·g−1增长至480 mA·h·g−1。优异的电池性能,简单的材料制备方法再加上低成本、高安全性及易于组装的特性,使可充电水性Zn-MnOx电池在大规模储能装置上的应用成为可能。

     

    Abstract: Due to the low cost, high safety and easy assembly, rechargeable aqueous zinc-manganese oxide (Zn-MnOx) batteries are the best devices for energy storage. However, poor conductivity of MnOx results in the bad cycle performance. Herein, highly conductive and layered Ti3C2Tx MXene with rich terminations (Tx, for example, =O, —F, —OH) were used as carriers for MnOx particles. Due to the electronegativity of the terminations, Mn2+ was intercalated into the layers and adsorbed on the surface of Ti3C2Tx MXene, making the generated Mn3O4 particles can firmly anchored, forming the Ti3C2@Mn3O4 composites. As for the cathode of zinc-ion batteries, Ti3C2@Mn3O4 was fully converted to Ti3C2@ε-MnO2 during the 1st charge process. Thanks to the excellent conductivity and layered structure of Ti3C2Tx MXene, Ti3C2@ε-MnO2 cathode presents excellent kinetic properties and electrochemical performance with a high specific capacity of 440 mA·h·g−1 and high energy density (607 W·h·kg−1) at 0.2 C (1 C=308 mA·h·g−1), and the capacities increase from 270 mA·h·g−1 to 480 mA·h·g−1 after 150 cycles at 1 C. Excellent electrochemical performance, simple material preparation methods, combined with the low cost, high safety and easy assembly characteristics, enable the possible application of rechargeable aqueous Zn-MnOx batteries in large-scale energy storage.

     

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