Supercapacitor is an important electrochemical energy storage / conversion device. As we know, the performance of supercapacitors is highly dependent on the inherent characteristics of the electrode materials. In particular, MXenes has proven to be a promising electrode material for supercapacitors. The rich chemical properties and surface functionalization, although enhancing the electrochemical activity of MXene in supercapacitors , have seriously deteriorated their self-discharge capabilities. This self-discharge behavior and its related mechanisms are still a blank.

Achievements

Recently, Southwest Jiaotong University ‘s Yang Weiqing Jiaoshou and Zhang Haitao, an associate professor in the internationally renowned journal ACS Nano published entitled "Unraveling and Regulating Self-Discharge Behavior of Ti 3 C 2 T the X-MXene-Based Supercapacitors " . A chemical interface cutting strategy was proposed to clarify the self-discharge behavior of Ti 3 C 2 T xMXene -based supercapacitors. Due to the chemical interface cutting strategy, the average oxidation state and local coordination information of MXene changed significantly. have a significant impact on the interaction between ions. the results show that with less F element of Ti . 3 C 2 T X MXenes (AT ~ 0.65%) and F higher element content MXenes (~ 8.09 at%) compared to The self-discharge rate has decreased by about 20% . The decrease of the F element can greatly increase the strongly bonded ions during the self-discharge process, and rapidly increase the transition potential by 50% .

Figure 1 Regulation of Self-Discharge Behavior of Ti 3 C 2 T x MXene -based Supercapacitors .

Figure 2 Self-discharge performance of Ti 3 C 2 T x MXene -based supercapacitors .

Figure 3 Morphology and structure of Ti 3 C 2 T x MXene -based supercapacitors .

Figure 4 Ti of XAFS map .

Figure 5 The theoretical calculation of DFT .

in conclusion

In summary, the strongly bound ( including F element less ) and weakly bonded ( including F elements more ) ion mixing may reduce the self-discharge rate. Through the chemical interface tailoring strategy, the significant changes in the average oxidation state and local coordination information of MXene have a significant effect on the interaction between ions. In theory, this greatly improves the self-discharge performance mainly due to the higher adsorption energy between the electrode and the electrolyte interface in the density functional theory. Therefore, this chemical interface cutting strategy can guide the design of MXenes -based supercapacitors with high performance and low self-discharge performance , which will promote its wider commercial application.

Original link:

https://pubs.acs.org/doi/abs/10.1021/acsnano.0c01056

Source: MXene Academic