Preparation of g-C3N4/CNTs composite by dissolution-precipitation method as sulfur host for high-performance lithium-sulfur batteries

Abstract

For suppressing the shuttle effect of lithium polysulfides (LiPS), the sulfur carrier with the dual function of physics and chemistry has become a research hotspot. Here, we propose a new method to prepare g-C3N4 (pCN)/CNTs sulfur host by dissolution-precipitation. Protonated g-C3N4 (pCN) was uniformly dispersed in H2SO4 and electrostatically self-assembled with CNTs. The uniformly dispersed pCN nanosheets provide a strong chemical adsorption capacity for further anchoring LiPS. By adjusting the ratio of pCN/CNTs, it is proved that pCN/CNTs composite with the best ratio of pCN/CNTs at 1:1 (termed as CC1:1) has excellent electrochemical performance, when compared with other pCN/CNTs composites and pristine g-C3N4. After cycling for 500 cycles, the final discharge specific capacity of CC1:1/S cathode is 711.9 mAh g−1 at 1 C, and each cycle has a low decay rate of 0.08%.