Amino modification of Ti3C2 MXenes for high-performance supercapacitors

MXenes show great potential in energy storage due to their excellent conductivity, abundant surface groups and adjustable interlayer spacing. Amino modification is an effective strategy to improve electrochemical properties of MXene. However, the selection of amino source is still a key issue. Herein, the amino modification of Ti3C2 MXenes for high-performance supercapacitors has been investigated. The structure and electrochemical properties of Ti3C2 are modified by different amino sources, such as ethylenediamine (EDA), monoethanolamine (MEA) and hydrazine monohydrate (HM). EDA ensures Ti3C2 the largest interlayer spacing (13.96 & Aring;) and highest specific surface area (52.2 m2g- 1). In addition, there are more functional groups in EDA-modified Ti3C2 (EDATi3C2) resulted from the stronger electron-donating nature of EDA than HM and MEA. Thus, EDA-Ti3C2 exhibits the largest specific capacitance of 683 F g- 1 in 1 M H2SO4 electrolyte at 2 mV/s, and the capacitance maintains 97.3 % of the original after 10,000 cycles at 50 mV/s. As a comparison, MEA-Ti3C2 and HM-Ti3C2 show specific capacitances of 553 F g- 1 and 470 F g-1, respectively. Furthermore, the symmetric supercapacitor based on EDATi3C2 electrode achieves maximum energy density of 7.87 W h kg- 1 at power density of 600 W Kg-1, and the energy density still remains at 6.34 W h Kg- 1 even at an increased power density of 3000 W Kg-1. This study proposes a simple strategy to enhance electrochemical properties of MXene by amino modification, providing valuable insights for high-performance supercapacitors.