Hierarchically porous membranes with synergistic Co clusters and N active sites enabled High-Efficient Li-ion transporting and redox reaction activity in Li-S batteries

Sluggish redox kinetics, shuttle effect, poor Li+ conductivity, and large volume change of sulfur limit the practical applications of lithium-sulfur (Li-S) batteries. Herein, we propose the construction of a sandwich-structured interlayer with a membrane supporting layer and two-sided synergistic Co/N-codoped interfaces. The middle supporting layer with hierarchically porous frame and ultrahigh porosity of 90 % is constituted of carbon nanotubes (CNT) as core and N-doped carbon coating as the crosslinked shell, which can improve the conductivity of Li+ and electrons and provide enough space for polysulfide (LiPSs) anchoring and conversion. The two-sided synergistic Co/N-codoped interfaces including Co clusters and N active sites show strong adsorption of S/Li2Sx and exceptionally high catalytic activity. The theoretical calculation demonstrates that the LiPSs are preferentially adsorbed on Co clusters due to the stronger affinity, while the free N active sites can work as transition points for Li+ transfer during the LiPSs conversion and Li2S decomposition processes. In this way, the N active sites with transition capacity and Co clusters with high adsorption and catalytic ability exhibit high-efficient synergistic effect in mitigating the shuttle effect and reducing energy barrier of the redox reaction. Benefit from the hierarchically porous membrane and the two-sided synergistic Co clusters and N sites, high-efficient Li+/electron transport and catalytic activity are achieved simultaneously in Li-S batteries. The proposed strategy has important guiding significance for the design of novel multifunctional interlayers for high-performance Li-S batteries.