Photo‐synergetic nitrogen‐doped MXene /reduced graphene oxide sandwich‐like architecture for high‐performance lithium‐sulfur batteries

Abstract

A valid 3D sandwich-like architecture of highly conductive Ti3C2Tx nanosheets with efficient 2D polar adsorption surfaces was evenly intercalated into graphene oxide (GO) skeletons with strong bridging via modified liquid phase impregnation, followed by a novel photo-synthetic nitrogen doping process (N-RGO/Ti3C2Tx). This novel photo-synthetic nitrogen doping method not only reduced the GO in a short time but also induced nitrogen doping into the composite easily. Within the rationally designed sandwich-like architecture, Ti3C2Tx interacted with reduced GO to construct a 3D conductive layer structure while inhibiting mutual stacking, thereby facilitating fast ion/electron transport and strong chemisorption for polysulfides, and also effectively buffering the volume expansion of electrodes during the discharge. In addition, the moderate chemical modulation induced by nitrogen doping achieved abundant defects and active sites, thereby improving the chemical immobilization for polysulfides. As sulfur host, the N-RGO/Ti3C2Tx sandwich-like architecture with 76.4 wt% sulfur could deliver excellent electrochemical performance due to the synergy of the above-mentioned merits. A superior reversible capacity of approximately 1180 mAh g−1 could be achieved over 200 cycles at 0.1 C. Even after cycling 200 times at 0.5 C, a high capacity of 850 mAh g−1 could still be obtained with a capacity retention of 82.5%. We rationally designed a novel structure and then used a facile photo-synthetic nitrogen doping strategy for surface modification, thus offering a new idea for designing multifunctional sulfur host for high-performance lithium-sulfur batteries.