Efficient Lithium/Sodium‐Ion Storage by Core–Shell Carbon Nanospheres@TiO₂ Decorate by Epitaxial WSe₂ Nanosheets Derived from Bimetallic Polydopamine Composites

Abstract Metal‐polydopamine coordination chemistry attracts great attention owing to the synergistic effect of adjustable components and advantageous structures. However, few efforts have been devoted to exploring bimetal‐polydopamine composites, especially for multistructural composites with high‐capacity components and high stability. In this regard, the TiO₂@C‐WSe₂ core–shell nanospheres are designed and fabricated based on Ti‐W‐polydopamine composites after selenization, in which the TiO₂ nanoparticles are encapsulated or embedded in the carbon nanospheres and the external WSe₂ nanosheets are grown epitaxially on the carbon surfaces, featuring multiple channels for ion diffusion and abundant active edges for electrochemical reactions. The introduction of WSe₂ not only greatly improves the capacity but also results in exponential growth of the active edge. As a result, the as‐prepared TiO₂@C‐WSe₂ displayed long‐term cycling performance in lithium‐ion batteries. Furthermore, the anode is assembled into sodium‐ion batteries, manifesting a stable capacity of 352 mA h g⁻¹ at 1.0 A g⁻¹ even after 2000 cycles, one of the best performances for polydopamine‐based composites. Enhanced performance can be attributed to the synergies of high‐capacity components and different dimensional materials. This work highlights that the rational design of functional structures provides a novel inspiration for electrodes with effective nanoarchitectures.