Anatase TiO₂ is a promising anode material for lithium-ion batteries (LIBs) owing to its low cost and stability. However, the intrinsically kinetic limits seriously hindered its lithium-ion storage capability. Here we present that anatase TiO₂ with rich oxygen vacancies can enhance its lithium-ion storage performance. We synthesize anatase TiO₂ with well-retained hierarchical structure by annealing the H₂Ti₅O₁₁·3H₂O yolk-shell spheres precursor in nitrogen atmosphere. EPR and XPS data evidence that the oxygen-deficient environment could generate abundant oxygen vacancies in the as-derived anatase TiO₂, which leads to improved electron conductivity and reduced charge-transfer resistance. The rich oxygen vacancies and high structural integrity of the hierarchical yolk-shell spheres enable the as-derived anatase TiO₂ yolk-shell spheres with a high specific capacity of 280 mAh g⁻¹ at 100 mA g⁻¹ and 71% of capacity retention after 5000 cycles at 2 A g⁻¹.

A novel hybrid, highly dispersed spinel Co-Mo sulfide nanoparticles on reduced graphene oxide (Co₃S₄/CoMo₂S₄@rGO), is reported as anode for lithium and sodium ion storage. The hybrid is synthesized by one-step hydrothermal method but exhibits excellent lithium and sodium storage performances. The as-synthesized Co₃S₄/CoMo₂S₄@rGO presents reversible capacity of 595.4 mA·h·g^-1 and 408.8 mA·h·g^-1 after 100 cycles at a current density of 0.2 A·g^-1 for lithium and sodium ion storages, respectively. Such superior performances are attributed to the unique composition and structure of Co₃S₄/CoMo₂S₄@rGO. The rGO provides a good electronically conductive network and ensures the formation of spinel Co₃S₄/CoMo₂S₄ nanoparticles, the Co₃S₄/CoMo₂S₄ nanoparticles provide large reaction surface for lithium and sodium intercalation/deintercalation, and the spinel structure allows fast lithium and sodium ion diffusion in three dimensions.

Nanostructured Mn₃O₄ was introduced to activated C (AC) by a novel sonochemical reaction, and the resulting nanocomposites were examined as supercapacitor electrodes. The sonication not only catalyzed the redox reaction but also promoted the diffusion of the precursors, causing the formation of coherent nanocomposites with Mn₃O₄ nanoparticles grown and uniformly distributed inside the mesopores of the AC. In addition, the extreme local condition in the sonochemical synthesis yielded an excessive amount of divalent manganese ions and oxygen vacancies. This novel microstructure endowed the sample with a superior performance, including a specific capacitance of 150 F/g compared with the value of 93 F/g for AC at a charge/discharge rate of 100 mA/g. A Li-ion capacitor delivered an energy density of 68 Wh/kg, compared with 41 Wh/kg for the AC capacitor at a power density of 210 W/kg.