Binder-Free MoS2@TiO2 Heterojunction by In-Situ Magnetron Sputtering: Interfacial Defect Engineering for Fast-Charging Anodes

Abstract To address the conductivity and volume-expansion bottlenecks of MoS2 anodes, we report a scalable, binder-free MoS2@TiO2 heterojunction fabricated by an in situ two-stage magnetron sputtering strategy. Vertically aligned MoS2 nanosheets are conformally capped with an amorphous, oxygen-vacancy-rich TiO2 skin. The electrode retains 507 mAh g–1 with ∼100% Coulombic efficiency after 500 cycles at 2 A g–1 and delivers 1135 mAh g–1 even at 20 A g–1. XPS/UPS quantifies high-density oxygen vacancies (Ovs) in TiO2, while DFT reveals these vacancies lower Li+ adsorption energy to −4.003 eV and drive electron accumulation into MoS2. EIS verifies a charge-transfer resistance of only 22.4 Ω, and CV confirms pseudocapacitive-dominated kinetics. DOS/band-alignment analysis substantiates that Ovs generate a built-in electric field pointing from TiO2 to MoS2, which promotes interfacial charge redistribution and accelerates Li+ adsorption and diffusion. These atomistic insights into the interfacial electronic structure modulation highlight an industrially compatible interface-engineering route for fast-charging lithium-ion anodes.