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A novel eutectoid structure, WxC-embedded WS2 nanosheets hybrids composite, was developed by hydrothermal reaction followed by a carbonization process. The fabricated WS2–WxC hybrid nanosheets electrode was used for lithium-ion batteries as an anode material, and demonstrated the specific capacity of 272 mA h·g−1 at 0.01 A g−1 with enhanced rate competence and cycling behavior when compared with individual WS2 and W2C electrode. While the large interlayer spacing in WS2 facilitates rapid Li+ transport, the extremely high electronic conductivity of WxC provides a highly conductive electron transfer pathway, which facilitates fast and reversible (de)lithiation reactions during charging and discharging. Further, these outcomes point the way for developing future eutectoid hybrid systems for advanced energy-storage applications.

We explored the doping effect of Ge4+ on the Li4Ti5-xGexO12 (x = 0.0 and 0.05) anode material by looking at its electrochemical performance in both Li- and Na-ion batteries. Combined analysis using Rietveld refinement of high-resolution powder diffraction (HRPD) and transmission electron microscopy (TEM) unambiguously identified homogeneous Ge doping into the 16c octahedral Ti site of the Li4Ti5O12 (LTO) cubic spinel structure. This Ge doping leads to a much-reduced particle size, slightly expanded lattice and increased electrical conductivity due to the increased Ti3+ to Ti4+ ratio, these results were verified by HRPD, scanning electron microscopy (SEM), 4-point probe and x-ray photoelectron spectroscopy (XPS) analysis. The Li4Ti4.95Ge0.05O12 (Ge0.05-LTO) electrode shows much-improved capacity, high-rate capability and excellent cycling stability in a Li-half cell compared with an un-doped LTO electrode. This performance improvement is due to the reduced Li+ diffusion path and faster Li+ insertion/extraction kinetics that originate from Ge doping. In addition to these results, when tested as an anode for SIBs, the Ge0.05-LTO electrode exhibits enhanced capacity and cycling stability compared to un-doped LTO electrode, demonstrating its bi-functional, advantageous features in both LIB and SIB systems.