A Multi-Scale Structural Engineering Strategy for High-Performance MXene Hydrogel Supercapacitor Electrode,Advanced Science

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A Multi-Scale Structural Engineering Strategy for High-Performance MXene Hydrogel Supercapacitor Electrode
Advanced Science ( IF 14.3 ) Pub Date : 2021-08-02 , DOI: 10.1002/advs.202101664
Xianwu Huang ₁ , Jiahui Huang ₁ , Dong Yang ₁ , Peiyi Wu _{1,

2}

Affiliation

MXenes as an emerging two-dimensional (2D) material have attracted tremendous interest in electrochemical energy-storage systems such as supercapacitors. Nevertheless, 2D MXene flakes intrinsically tend to lie flat on the substrate when self-assembling as electrodes, leading to the highly tortuous ion pathways orthogonal to the current collector and hindering ion accessibility. Herein, a facile strategy toward multi-scale structural engineering is proposed to fabricate high-performance MXene hydrogel supercapacitor electrodes. By unidirectional freezing of the MXene slurry followed by a designed thawing process in the sulfuric acid electrolyte, the hydrogel electrode is endowed with a three-dimensional (3D) open macrostructure impregnated with sufficient electrolyte and H⁺-intercalated microstructure, which provide abundant active sites for ion storage. Meanwhile, the ordered channels bring through-electrode ion and electron transportation pathways that facilitate electrolyte infiltration and mass exchange between electrolyte and electrode. Furthermore, this strategy can also be extended to the fabrication of a 3D-printed all-MXene micro-supercapacitor (MSC), delivering an ultrahigh areal capacitance of 2.0 F cm^–2 at 1.2 mA cm^–2 and retaining 1.2 F cm^–2 at 60 mA cm^–2 together with record-high energy density (0.1 mWh cm^–2 at 0.38 mW cm^–2).

中文翻译：

高性能 MXene 水凝胶超级电容器电极的多尺度结构工程策略

MXenes 作为一种新兴的二维 (2D) 材料引起了人们对超级电容器等电化学储能系统的极大兴趣。然而，当自组装为电极时，2D MXene 薄片本质上倾向于平放在基板上，导致与集电器正交的高度曲折的离子路径并阻碍离子可及性。在此，提出了一种面向多尺度结构工程的简便策略来制造高性能 MXene 水凝胶超级电容器电极。通过单向冷冻 MXene 浆料，然后在硫酸电解质中进行设计的解冻过程，水凝胶电极被赋予了三维（3D）开放宏观结构，浸渍有足够的电解质和 H ⁺嵌入的微观结构，从而提供了丰富的活性位点用于离子存储。同时，有序通道带来了穿过电极的离子和电子传输路径，有利于电解质渗透以及电解质与电极之间的质量交换。此外，该策略还可以扩展到 3D 打印的全 MXene 微型超级电容器 (MSC) 的制造，在 1.2 mA cm ^{–2下提供 2.0 F cm}^–2的超高面积电容，并保留 1.2 F cm ^–2 60 mA cm ^–2以及创纪录的高能量密度（0.1 mWh cm ^–2和 0.38 mW cm ^–2）。

更新日期：2021-09-22

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