双向有序Ti3C2Tx/rGO复合气凝胶的制备及其电化学性能的研究

近年来,二维材料MXene因其优异的电化学性能引起了人们的关注,被广泛应用于电化学储能领域。然而,在组装电极过程中,MXene纳米片往往会产生严重的自堆积效应从而大幅限制了其电化学性能。设计三维结构的气凝胶是解决MXene自堆积问题同时开发高性能MXene基超级电容器电极材料的关键。本文利用氧化石墨烯(GO)改善了Ti₃C₂T_x气凝胶的力学强度,并通过双向冷铸和冷冻干燥、温和还原的方法制备了具有双向有序结构的Ti₃C₂T_x/rGO复合气凝胶(A-TGA)。A-TGA具有较好的力学性能和导电性,因此可直接作为超级电容器的电极材料。同时,双向有序的独特结构为电解质离子提供了无阻碍的传输通道,大幅提升了气凝胶的电化学性能。A-TGA在电流密度为1 A·g^-1时的比电容为370 F·g^-1,在100 mV·s^-1扫速下经过5 000次循环后,电容保持率高达94%,表现出优异的循环稳定性。

Preparation and Electrochemical Properties of Bidirectionally Aligned Ti3C2Tx/rGO Hybrid Aerogels

In recent years, two-dimensional MXene have attracted more attentions owing to their excellent electrochemical performance, resulting their widely used in electrochemical energy storage field. However, traditional electrodes fabrication processes may result in the self-restacking of MXene nanosheets, which may lead to the low electrochemical performance of MXene based electrode materials. It is effective to design a three-dimensional aerogel to suppress the self-restacking of MXene nanosheets and develop high-performance MXene based electrode materials. Ti₃C₂T_x/rGO hybrid aerogel (A-TGA) with bidirectionally aligned structure through the bidirectional freeze casting and freeze drying method was prepared in this paper, and the mechanical performance of the hybrid aerogel was improved by the mild reduction of graphene oxide (GO). The A-TGA shows excellent mechanical properties and electrical conductivity, so it can be used as the electrode material for supercapacitors, the unique bidirectionally aligned structure provides barrier-free transport channels for electrolyte ions, which can greatly improve the electrochemical properties of A-TGA. The A-TGA shows a specific capacitance of 370 F·g^-1 at 1 A·g^-1 and delivers an outstanding cycling performance with a capacitance retention up to 94% over 5 000 cycles at 100 mV·s^-1 scanning speed.