Article

Maximizing ion accessibility in MXene-knotted carbon nanotube composite electrodes for high-rate electrochemical energy storage

Xiang GaoState Key Laboratory of Materials Processing and Die & Mold Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology (HUST), 430074, Wuhan, P R ChinaXuan DuState Key Laboratory of Materials Processing and Die & Mold Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology (HUST), 430074, Wuhan, P R ChinaTyler S. MathisA. J. Drexel Nanomaterials Institute and Department of Materials Science and Engineering, Drexel University, Philadelphia, PA, 19104, USAMengmeng ZhangState Key Laboratory of Materials Processing and Die & Mold Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology (HUST), 430074, Wuhan, P R ChinaXuehang WangA. J. Drexel Nanomaterials Institute and Department of Materials Science and Engineering, Drexel University, Philadelphia, PA, 19104, USAJianglan ShuiSchool of Materials Science and Engineering, Beihang University, 100083, Beijing, P R ChinaYury GogotsiA. J. Drexel Nanomaterials Institute and Department of Materials Science and Engineering, Drexel University, Philadelphia, PA, 19104, USA. [email protected]Ming XuState Key Laboratory of Materials Processing and Die & Mold Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology (HUST), 430074, Wuhan, P R China. [email protected]

2020en

ABI

Abstract

Abstract Improving the accessibility of ions in the electrodes of electrochemical energy storage devices is vital for charge storage and rate performance. In particular, the kinetics of ion transport in organic electrolytes is slow, especially at low operating temperatures. Herein, we report a new type of MXene-carbon nanotube (CNT) composite electrode that maximizes ion accessibility resulting in exceptional rate performance at low temperatures. The improved ion transport at low temperatures is made possible by breaking the conventional horizontal alignment of the two-dimensional layers of the MXene Ti 3 C 2 by using specially designed knotted CNTs. The large, knot-like structures in the knotted CNTs prevent the usual restacking of the Ti 3 C 2 flakes and create fast ion transport pathways. The MXene-knotted CNT composite electrodes achieve high capacitance (up to 130 F g −1 (276 F cm −3 )) in organic electrolytes with high capacitance retention over a wide scan rate range of 10 mV s −1 to 10 V s −1 . This study is also the first report utilizing MXene-based supercapacitors at low temperatures (down to −60 °C).

Identifiers

DOI: 10.1038/s41467-020-19992-3

Citations and references

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