Fabrication of a Covalent Triazine Framework Functional Interlayer for High-Performance Lithium–Sulfur Batteries

The shuttling effect of polysulfides is one of the major problems of lithium–sulfur (Li–S) batteries, which causes rapid capacity fading during cycling. Modification of the commercial separator with a functional interlayer is an effective strategy to address this issue. Herein, we modified the commercial Celgard separator of Li–S batteries with one-dimensional (1D) covalent triazine framework (CTF) and a carbon nanotube (CNT) composite as a functional interlayer. The intertwined CTF/CNT can provide a fast lithium ionic/electronic transport pathway and strong adsorption capability towards polysulfides. The Li–S batteries with the CTF/CNT/Celgard separator delivered a high initial capacity of 1314 mAh g−1 at 0.1 C and remained at 684 mAh g−1 after 400 cycles−1 at 1 C. Theoretical calculation and static-adsorption experiments indicated that the triazine ring in the CTF skeleton possessed strong adsorption capability towards polysulfides. The work described here demonstrates the potential for CTF-based permselective membranes as separators in Li–S batteries.

Biphenyl-Based Covalent Triazine Framework/Matrimid® Mixed-Matrix Membranes for CO2/CH4 Separation

Processes, such as biogas upgrading and natural gas sweetening, make CO2/CH4 separation an environmentally relevant and current topic. One way to overcome this separation issue is the application of membranes. An increase in separation efficiency can be achieved by applying mixed-matrix membranes, in which filler materials are introduced into polymer matrices. In this work, we report the covalent triazine framework CTF-biphenyl as filler material in a matrix of the glassy polyimide Matrimid®. MMMs with 8, 16, and 24 wt% of the filler material are applied for CO2/CH4 mixed-gas separation measurements. With a CTF-biphenyl loading of only 16 wt%, the CO2 permeability is more than doubled compared to the pure polymer membrane, while maintaining the high CO2/CH4 selectivity of Matrimid®.