Nano-Micro Letters

A Novel Strategy of In Situ Trimerization of Cyano Groups Between the Ti3C2Tx (MXene) Interlayers for High-Energy and High-Power Sodium-Ion Capacitors

Siyang Liu1, Fangyuan Hu1, *, Wenlong Shao2, Wenshu Zhang1, Tianpeng Zhang1, Ce Song3, Man Yao1, Hao Huang1, Xigao Jian1, 2, 3, *

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Nano-Micro Lett. (2020) 12: 135

First Online: 25 June 2020 (Article)

DOI:10.1007/s40820-020-00473-7

*Corresponding author. E-mail: hufangyuan@dlut.edu.cn (F. Hu), jian4616@dlut.edu.cn (X. Jian)

 

Abstract

 


Toc

2D MXenes are attractive for energy storage applications because of their high electronic conductivity. However, it is still highly challenging for improving the sluggish sodium (Na)-ion transport kinetics within the MXenes interlayers. Herein, a novel nitrogen-doped Ti3C2Tx MXene was synthesized by introducing the in-situ polymeric sodium dicyanamide (Na-dca) to tune the complex terminations, then utilized as intercalation-type pseudocapacitive anode of Na-ion capacitors (NICs). The as-prepared Ti3C2Tx/Na3TCM exhibits a high N-doping of 5.6 at% in the form of strong Ti−N bonding and stabilized triazine ring structure. The density functional theory calculations and kinetic analysis verify the ultra-fast Na-ion adsorption and diffusion kinetics. Consequently, coupling Ti3C2Tx/Na3TCM anode with different mass of activated carbon cathodes, the asymmetric MXene//carbon NICs are assembled. It is able to deliver high energy density (97.6 Wh kg−1), high power output (16.5 kW kg−1), and excellent cycling stability (≈82.6% capacitance retention after 8000 cycles). This work provides new ideas in fabricating polymer molecules/MXenes hybrid electrodes for high energy storage devices.


 

Keywords

Sodium-ion capacitors, MXene, Fast kinetics, Triazine polymerization, Nitrogen doping

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