Maximizing ion accessibility in MXene-knotted carbon nanotube composite electrodes for high-rate electrochemical energy storage.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 33268791.
- Also identified by DOI 10.1038/s41467-020-19992-3 and PMC identifier 7710708.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
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<sub>3</sub>C<sub>2</sub> by using specially designed knotted CNTs. The large, knot-like structures in the knotted CNTs prevent the usual restacking of the Ti<sub>3</sub>C<sub>2</sub> flakes and create fast ion transport pathways. The MXene-knotted CNT composite electrodes achieve high capacitance (up to 130 F g<sup>-1</sup> (276 F cm<sup>-3</sup>)) in organic electrolytes with high capacitance retention over a wide scan rate range of 10 mV s<sup>-1</sup> to 10 V s<sup>-1</sup>. This study is also the first report utilizing MXene-based supercapacitors at low temperatures (down to -60 °C).