Journal Article

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

Gogotsi, Yury, Shui, Jianglan, Gao, Xiang, Du, Xuan, Mathis, Tyler S., Xu, Ming, Zhang, Mengmeng, Wang, Xuehang

2020

Overview

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). Improving the accessibility of ions in the electrodes of electrochemical energy storage devices is vital for charge storage and rate performance. Here, the authors report a new type of MXene-carbon nanotube composite electrode that maximizes ion accessibility, resulting in high rate performance at low temperatures.

• Publisher: Nature Publishing Group UK,Nature Publishing Group,Nature Portfolio
• Subject: 639/301/299 / 639/301/357/1018 / 639/4077/4079/4105 / Accessibility / Capacitance / Carbon / Carbon nanotubes / Electrochemistry / Electrodes / Electrolytes / Energy storage / Humanities and Social Sciences / Ion transport / Ions / Low temperature / multidisciplinary / MXenes / NANOSCIENCE AND NANOTECHNOLOGY / Nonaqueous electrolytes / Operating temperature / PHYSICS OF ELEMENTARY PARTICLES AND FIELDS / Science / Science (multidisciplinary)