Multifunctional TiN‐MXene‐Co@CNTs Networks as Sulfur/Lithium Host for High‐Areal‐Capacity Lithium‐Sulfur Batteries

The inevitable shuttling and slow redox kinetics of lithium polysulfides (LiPSs) as well as the uncontrolled growth of Li dendrites have strongly limited the practical applications of lithium‐sulfur batteries (LSBs). To address these issues, we have innovatively constructed the carbon nanotubes (CNTs) encapsulated Co nanoparticles in situ grown on TiN‐MXene nanosheets, denoted as TiN‐MXene‐Co@CNTs, which could serve simultaneously as both sulfur/Li host to kill “three birds with one stone” to (1) efficiently capture soluble LiPSs and expedite their redox conversion, (2) accelerate nucleation/decomposition of solid Li2S, and (3) induce homogeneous Li deposition. Benefiting from the synergistic effects, the TiN‐MXene‐Co@CNTs/S cathode with a sulfur loading of 2.5 mg cm−2 could show a high reversible specific capacity of 1129.1 mAh g−1 after 100 cycles at 0.1 C, and ultralong cycle life over 1000 cycles at 1.0 C. More importantly, it even achieves a high areal capacity of 6.3 mAh cm−2 after 50 cycles under a sulfur loading as high as 8.9 mg cm−2 and a low E/S ratio of 5.0 μL mg−1. Besides, TiN‐MXene‐Co@CNTs as Li host could deliver a stable Li plating/striping behavior over 1000 h. The 3D TiN‐MXene‐Co@CNTs conductive network has been designed to serve as a sulfur/Li host of LSBs, whose multicomponent heterostructure facilitated maximum exposure of active sites, thereby enhancing adsorption and catalytic activity. These superior features of TiN‐MXene‐Co@CNTs effectively suppressed the shuttling of soluble LiPSs and accelerated their conversions, as well as expedited the nucleation/decomposition of solid Li2S and reduced uniform Li deposition.