In-situ engineering of a defect-rich TiO₂ interphase coupled with sulfur vacancies in WS2/TiO2@C heterostructures for enhanced Li⁺ storage in 3D-printed anodes

Tungsten disulfide (WS₂) is a promising anode material for lithium-ion batteries due to its high theoretical capacity, however, its practical application is limited by poor intrinsic conductivity and severe volume variation during cycling. Herein, we develop a 3D printable WS₂/TiO 2 @C anode (3DP-WTCN) via sulfur vacancy activation and in-situ interphase engineering. In this system, sulfur vacancy enriched WS₂ provides abundant Li⁺ adsorption sites and accelerates reaction kinetics. Meanwhile, Ti 3 C 2 T x undergoes partial transformation to form a defect-rich TiO 2 interphase, accompanied by Ti–S-related interfacial interactions, which promote interfacial coupling between WS₂ and the Ti-containing phase. This interphase regulated heterostructure promotes efficient electron transport and facilitates rapid Li⁺ diffusion while mitigating structural degradation. Importantly, the interphase regulated system is integrated with 3D-printed electrode architecture, enabling interconnected conductive pathways, shortened ion diffusion distances, and high mass loading capability. As a result, the 3DP-WTCN anode exhibits 200–500% improvement in areal capacity as compared to WTCN, WS₂ and Ti₃C₂Tₓ anode. The WTCN anode delivers a reversible capacity of 697.1 mAh g⁻¹ at 0.2 A g⁻¹ with 80.2% capacity, corresponding to improvements of ~ 248% over pristine WS₂ and ~ 365% over Ti₃C₂Tₓ MXene, while the 3DP-WTCN anode further exhibits an additional average ~ 50% increase in specific capacity compared to the WTCN anode.