Construction of TiO ₂ /TiN Heterostructure and CNTs Co-modified Carbon Foam as a Self-Supporting Current Collector of Li–S Batteries

The shuttle effect and a low areal sulfur loading have always been predominant problems that severely limit the widespread application of lithium-sulfur (Li-S) batteries. Based on a nitrogen-enriched melamine foam, a self-supporting current collector with multifunctional properties is fabricated through the in situ construction of TiO₂/TiN heterostructures combined with CNTs. The flexible CNTs decoration further endows the functional carbon foam with a robust framework. Besides, this integrated structure establishes a continuous, highly conductive network that facilitates rapid electron transport and enhances the overall sulfur utilization efficiency within the electrode. Especially, the introduction of a TiO₂/TiN heterostructure combined with in situ nitrogen doping exhibits good chemical synergistic adsorption and favorable catalytic conversion kinetics for soluble lithium disulfides. The resulting self-supporting cathode (2.7 mg cm^-2 in sulfur loading) delivers an initial discharge capacity of 1059.1 mAh g^-1 at a current rate of 0.2 C. After 100 cycles, a reversible capacity of 936.2 mAh g^-1 is retained. When the sample is 6.8 mg cm^-2, a discharge capacity of 877.7 mAh g^-1 is delivered after 40 cycles at 0.1 C, and the corresponding areal capacity is 6.0 mAh cm^-2. This work provides a good idea for designing a high-performance binder-free current collector in Li-S batteries.