Electron-Injection-Engineering Induced Phase Transition toward Stabilized 1T-MoS₂ with Extraordinary Sodium Storage Performance

Phase transition engineering, with the ability to alter the electronic structure and physicochemical properties of materials, has been widely used to achieve the thermodynamically unstable metallic phase MoS₂ (1T-MoS₂), although the complex operating conditions and low yield of previous strategies make the large-scale fabrication of 1T-MoS₂ a big challenge. Herein, we report a facile electron injection strategy for phase transition engineering and fabricate a composite of conductive TiO chemically bonded to 1T-MoS₂ nanoflowers (TiO-1T-MoS₂ NFs) on a large scale. The underlying mechanism analysis reveals that electron-injection-engineering triggers a reorganization of the Mo 4d orbitals and results in a 100% phase transition of MoS₂ from 2H to 1T. In the TiO-1T-MoS₂ NFs composite, the 1T-MoS₂ demonstrates a higher electronic conductivity, a lower Na⁺ diffusion barrier, and a more restricted S release than 2H-MoS₂. In addition, conductive TiO bonding successfully resolves the stability challenge of the 1T phase. These merits endow TiO-1T-MoS₂ NFs electrodes with an excellent rate capability (650/288 mAh g^-1 at 50/20 000 mA g^-1, respectively) and an outstanding cyclability (501 mAh g^-1 at 1000 mA g^-1 after 700 cycles) in sodium ion batteries. Such an improvement signifies that this facile and scalable phase-transition engineering combined with a deep mechanism analysis offers an important reference for designing advanced materials for various applications.