CoP nanocages intercalated MXene nanosheets as a bifunctional mediator for suppressing polysulfide shuttling and dendritic growth in lithium-sulfur batteries

The practical application of lithium–sulfur (Li-S) batteries has been hampered by the shuttle effect of lithium polysulfides (LiPSs) and seriously uncontrollable Li dendrite growth. Herein, we report an elaborate heterostructure (Ti3C2/CPNC), composed of Ti3C2 nanosheets-encapsulated CoP nanocages with abundant lithiophilic/sulfiphilic sites for suppressing polysulfide shuttling and dendritic growth in Li-S batteries. Functioning as a separator mediator, the Ti3C2/CPNC heterostructure affords a synergistic effect of strong chemical interactions and fast conversion kinetics toward LiPSs. A half cell with the Ti3C2/CPNC interlayer exhibits a remarkable cycling stability with a capacity decay of only 0.039 % per cycle at 1C after 1150 cycles. As a Li host, the Ti3C2/CPNC heterostructure with remarkable lithiophilicity and high conductivity regulates the uniform plating/stripping of Li. The integrated Li–S full cell harvests an excellent electrochemical performance, even at a high sulfur loading of 5.3 mg cm−2 with a negative to positive (N/P) electrode capacity ratio of 1.7:1. This work demonstrates the potential application of bifunctional mediators for fabricating Li–S full batteries with outstanding electrochemical performance.